The Immunoglobulin Gene Superfamily is characterized by a common protein\r\nhomology unit that is present in arguably the largest and most diverse set of genes and\r\ngene families of any protein motif. This distribution indicates that the homology unit is\r\na remarkably versatile functional unit. Its central role in defining the complex\r\nphenotypes of the immune and nervous systems, likewise, is testament to the ability of\r\nthe motif to support an amazing and unique degree of diversification. Understanding\r\nmore about the function, structure and evolution of the Immunoglobulin Gene\r\nSuperfamily can provide insights into both the general issues of complex system\r\nevolution as well as the specific nature of the various systems the superfamily plays a\r\ncentral role in. This thesis is a collection of work aimed at a more thorough\r\nunderstanding of these elements. Particularly, these works summarize much of our\r\ncurrent understanding of the members of the Immunoglobulin Gene Superfamily along\r\nwith speculations on their evolutionary history as well as both the evolutionary and\r\nsomatic mechanisms responsible for their diversity. This work includes initial\r\ndescriptions of several features relevant to somatic diversification of rearranging\r\nimmune receptors, including: l) the role of joining imprecision in the generation of\r\njunctional diversity in immunoglobulin kappa chain; 2) the initial description of the T-cell\r\nbeta chain J/C locus; 3) the translation of T-cell beta chain D gene segments in all\r\nthree reading frames; 4) the occurrence of a cryptic rearrangement signal in most\r\nrearranging V families; 5) the first description of the mechanisms of class switching\r\nbetween heavy chain mu and delta genes; 6) the limited diversity of germline T-cell\r\nbeta chains; 7) the shared complementary determining region structure of T-cell beta\r\nchains and immunoglobulin heavy chains. Also, from these efforts, new members of\r\nthe superfamily have been identified including MHC class I molecules, L3T4 and\r\nMyelin Associated Glycoprotein. Various observations concerning the evolutionary\r\nrelationships of these molecules and motifs have been made. Particularly, a variation\r\non the basic homology unit motif has been proposed that probably more nearly\r\nrepresents the primordial sequence and function.
\r\n\r\nAs a result of these discoveries, a new, comprehensive picture of the\r\nimmunoglobulin superfamily is emerging that has implications for interpreting current\r\nfunctional relationships in the context of the evolutionary history of the members.\r\nParticularly, it is suggested from this work that the ability of the homology unit to\r\naccommodate diversity has made possible the evolution of the superfamily. Given the\r\ntremendous diversity within the superfamily, it might be assumed that selective\r\npressures favoring diversity have driven its evolution. However, much of the analysis\r\nwithin this collection suggests that, on the contrary, diversity is an inherent feature of\r\nthe conserved protein and gene structure of the homology unit and that it was the a\r\npriori diversity itself that drove and shaped the evolution of the complex systems that\r\nemploy the homology unit today. This basic diversity is the consequence of three\r\ncharacteristics of the homology unit. First, the tertiary structure of the protein motif is\r\nsuch that homology units tend to interact preferentially to form homo- or heterodimers,\r\nforming the basis of many of the receptors and the receptor/ligand interactions common\r\nwithin the superfamily. These combinatorial associations increase both the somatic and\r\nevolutionary potential for diversification. This can lead to the rather sudden\r\nappearance of new functional associations between existing members of the superfamily\r\npreadapted for otherwise unrelated functions. Second, except for a minimal number of\r\namino acid residues involved in critical intra- and interchain interactions, the primary\r\nstructure of these units can vary dramatically and still provide for essentially the same\r\ntertiary structure. This has been borne out by various crystallographic studies. The\r\nvariability is particularly true of the loop structures normally identified with antigen\r\nspecificity, but seen in other extended families as well. Reduced constraints on\r\nstructural sequences inherently promote the establishment of variation within\r\npopulations. Third, with very few exceptions the genes of the superfamily, the\r\nhomology units are not only encoded by discrete exons, but these exons have a shared\r\n1/2 splicing rule. That is, each is begun with the second 2 bases of a codon and ended\r\nwith the first base. This allows the in-frame splicing of any number of tandem\r\nhomology units, while maintaining functional protein domains. This rule generally\r\napplies to the non-homology unit exons of member genes as well. This allows, through\r\nrelatively simple genetic events, the development of new contexts for homology unit\r\nexpression, both by simple expansion and contraction of homology unit number and\r\nexon shuffling. This is probably at work, as well, in the frequent occurrence and\r\nutilization of alternative transcripts seen throughout the superfamily. Many of the\r\nrecognized occurrences of alternative splicing, such as that between membrane-bound\r\nand secreted forms, indicate that this gene structure provides for a further level of\r\nfunctional diversity and the expansion of the virtual genetic information.
\r\n\r\nBeyond the explicit discussion of the superfamily members, this work also\r\nspeaks to various issues of evolution in general. In particular, the history of the\r\nsuperfamily suggests the importance of canalization and non-gradual episodes of\r\nevolutionary change. It can contribute, as well, to the discussion of adaptive versus\r\nneutral change.
", "doi": "10.7907/mcbv-n026", "publication_date": "1993", "thesis_type": "phd", "thesis_year": "1993" }, { "id": "thesis:2656", "collection": "thesis", "collection_id": "2656", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06202007-083735", "primary_object_url": { "basename": "Herman_pk_1991.pdf", "content": "final", "filesize": 13913514, "license": "other", "mime_type": "application/pdf", "url": "/2656/1/Herman_pk_1991.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Protein Sorting in the Eukaryotic Secretory Pathway: An Essential Role for a Novel Yeast Protein Kinase", "author": [ { "family_name": "Herman", "given_name": "Paul Kenneth", "clpid": "Herman-Paul-Kenneth" } ], "thesis_advisor": [ { "family_name": "Emr", "given_name": "Scott D.", "orcid": "0000-0002-5408-6781", "clpid": "Emr-S-D" } ], "thesis_committee": [ { "family_name": "Emr", "given_name": "Scott D.", "orcid": "0000-0002-5408-6781", "clpid": "Emr-S-D" }, { "family_name": "Sternberg", "given_name": "Paul W.", "orcid": "0000-0002-7699-0173", "clpid": "Sternberg-P-W" }, { "family_name": "Dunphy", "given_name": "William G.", "orcid": "0000-0001-7598-8939", "clpid": "Dunphy-W-G" }, { "family_name": "Brokaw", "given_name": "Charles J.", "clpid": "Brokaw-C-J" }, { "family_name": "Tanouye", "given_name": "Mark", "clpid": "Tanouye-M" } ], "local_group": [ { "literal": "div_biol" } ], "abstract": "The yeast vps mutants are defective for the intracellular sorting of proteins to the vacuolar compartment. Mutants from two particular vps complementation groups, vpsl5 and vps34, share a common set of phenotypes that suggested that the VPS15 and VPS34 gene products might be functioning at a similar step of the vacuolar protein sorting pathway. vpsl5 and vps34 mutants exhibit specific defects in the sorting of soluble hydrolases to the vacuolar compartment. Whereas soluble hydrolases such as carboxypeptidase Y are almost quantitatively mislocalized to the cell surface, vacuolar membrane proteins appear to be properly localized to the vacuole.\r\n\r\nThe wild-type VPS15 and VPS34 genes were both cloned from yeast genomic DNA libraries by complementation of temperature-sensitive growth defects associated with mutations in these genes. Haploid yeast strains carrying a disruption of either locus were viable but exhibited a severe ts growth defect indicating that both genes are essential for vegetative growth at elevated temperatures. The vps34 null mutant was also found to exhibit a defect in the segregation of the vacuolar compartment upon cell division.\r\n\r\nThe predicted sequence of the VPS15 gene product exhibits significant similarity to the catalytic domains of the serine/threonine family of protein kinases. Point mutations altering specific amino acid residues of Vpsl5p that are highly conserved in all protein kinases result in the biological inactivation of Vpsl5p. The kinase domain mutants exhibit severe vacuolar protein sorting and ts growth defects. In addition, Vpsl5p is phosphorylated in vivo in a reaction that requires a wild-type Vpsl5p kinase domain. Subcellular fractionation experiments indicate that Vpsl5p is peripherally associated with the cytoplasmic face of a late Golgi or vesicle compartment. A vpsl5 mutant that encodes a protein lacking 30 carboxy-terminal amino acids exhibits a severe ts defect in vacuolar protein delivery. At the restrictive temperature, carboxpeptidase Y accumulates in a specific intracellular compartment that may represent a normal transport intermediate between the Golgi and vacuolar compartments. The vacuolar delivery defect in this mutant has an extremely rapid rate of onset suggesting that Vps15p is directly involved in the sorting of soluble proteins to the vacuole. Altogether, these data suggest that Vpsl5p regulates specific protein phosphorylation reactions in vivo that are required for the delivery of soluble hydrolases to the vacuole.", "doi": "10.7907/38ba-0w26", "publication_date": "1991", "thesis_type": "phd", "thesis_year": "1991" }, { "id": "thesis:6290", "collection": "thesis", "collection_id": "6290", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04112011-112805564", "type": "thesis", "title": "Genetic, Molecular and Biochemical Studies of Vacuole Biogenesis and Maintenance in the Yeast Saccharomyces cerevisiae", "author": [ { "family_name": "Robinson", "given_name": "Jane Suzanna", "clpid": "Robinson-Jane-Suzanna" } ], "thesis_advisor": [ { "family_name": "Emr", "given_name": "Scott D.", "orcid": "0000-0002-5408-6781", "clpid": "Emr-S-D" } ], "thesis_committee": [ { "family_name": "Emr", "given_name": "Scott D.", "orcid": "0000-0002-5408-6781", "clpid": "Emr-S-D" }, { "family_name": "Abelson", "given_name": "John N.", "clpid": "Abelson-J-N" }, { "family_name": "Brokaw", "given_name": "Charles J.", "clpid": "Brokaw-C-J" }, { "family_name": "Meyerowitz", "given_name": "Elliot M.", "orcid": "0000-0003-4798-5153", "clpid": "Meyerowitz-E-M" }, { "family_name": "Sternberg", "given_name": "Paul W.", "orcid": "0000-0002-7699-0173", "clpid": "Sternberg-P-W" } ], "local_group": [ { "literal": "div_biol" } ], "abstract": "Using a selection for spontaneous mutants that mislocalize a vacuolar CPY-Inv\r\nfusion protein to the cell surface, 505 Saccharomyces cerevisiae mutants with defects in\r\nprotein sorting were identified. Seventeen of these mutants were dominant; the others\r\ndefined 25 new vps (for vacuolar protein sorting) complementation groups. Alleles of\r\neach vps complementation group exhibit defects in the targeting and final processing of\r\nsoluble vacuolar enzymes (CPY, PrA and PrB). Two of the genes, VPS17 and VPS15,\r\nmap to ChXV and ChII, respectively. The vpsll, vps16, vps18 and vps33 mutants\r\nexhibit morphological defects, their cells containing debris of a membranous nature and\r\nhighly abnormal vacuole remnants. Intercrosses with other vacuole function-defective\r\nmutants (vpl, pep, sip and end), revealed genetic overlaps. It is evident that more than\r\n50 gene products are involved in biogenesis and maintenance of the yeast vacuole.\r\nAlleles of 7 of the vps complementation groups are temperature-sensitive for vegetative\r\ncell growth at 37\u00b0C, and this recessive, Ts phenotype cosegregated with the vps defect\r\nin each case. This easily complemented phenotype has facilitated cloning of six of the\r\ngenes.\r\nThe VPS18 gene was chosen for further studies. A plasmid complementing the\r\nTs growth defect of vps18-1 was isolated and shown by integrative mapping to carry\r\nDNA from the VPS18 locus. Yeast strains with a deletion of the entire VPS18 coding\r\nregion (\u0394vps18), are viable and exhibit the same phenotypes as vps18-1. \u0394vps18, \u03b1 strains have smaller \u03b1-factor halos on sst2,a lawns than do VPS18, \u03b1 strains.\r\nImmunoprecipitation of \u03b1-factor indicated that it is secreted from the \u0394vps18 mutant in\r\nprecursor form. Several of the other severely defective vps mutants also show this \u03b1-factor\r\nprocessing defect. DNA sequencing of VPs18 showed an open reading frame\r\nencoding a 918aa protein, hydrophilic in nature. The protein sequence revealed a zinc finger like, cysteine-rich motif in its C-terminal region. A synthetic mutant with a\r\ncysteine to serine alteration has a temperature-conditional CPY sorting defect with very\r\nrapid onset. Therefore, Vps18p may be a zinc-binding protein, directly necessary for\r\ncorrect vacuolar protein sorting and proper functioning of the Golgi compartment that\r\ncontains Kex2p.\r\n", "doi": "10.7907/zfzc-0035", "publication_date": "1991", "thesis_type": "phd", "thesis_year": "1991" }, { "id": "thesis:8616", "collection": "thesis", "collection_id": "8616", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:07282014-141222100", "primary_object_url": { "basename": "Preugschat_f_1990.pdf", "content": "final", "filesize": 25667020, "license": "other", "mime_type": "application/pdf", "url": "/8616/1/Preugschat_f_1990.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Proteolytic processing of the nonstructural proteins of dengue 2 virus", "author": [ { "family_name": "Preugschat", "given_name": "Frank", "clpid": "Preugschat-F" } ], "thesis_advisor": [ { "family_name": "Strauss", "given_name": "James H.", "clpid": "Strauss-J-H" }, { "family_name": "Strauss", "given_name": "Ellen G.", "clpid": "Strauss-E-G" } ], "thesis_committee": [ { "family_name": "Brokaw", "given_name": "Charles J.", "clpid": "Brokaw-C-J" }, { "family_name": "Davidson", "given_name": "Norman R.", "clpid": "Davidson-N-R" }, { "family_name": "Meyerowitz", "given_name": "Elliot M.", "clpid": "Meyerowitz-E-M" }, { "family_name": "Rothenberg", "given_name": "Ellen V.", "clpid": "Rothenberg-E-V" } ], "local_group": [ { "literal": "div_biol" } ], "abstract": "The genomes of many positive stranded RNA viruses and of all\r\nretroviruses are translated as large polyproteins which are proteolytically\r\nprocessed by cellular and viral proteases. Viral proteases are structurally\r\nrelated to two families of cellular proteases, the pepsin-like and trypsin-like\r\nproteases. This thesis describes the proteolytic processing of several\r\nnonstructural proteins of dengue 2 virus, a representative member of the\r\nFlaviviridae, and describes methods for transcribing full-length genomic\r\nRNA of dengue 2 virus. Chapter 1 describes the in vitro processing of the\r\nnonstructural proteins NS2A, NS2B and NS3. Chapter 2 describes a system\r\nthat allows identification of residues within the protease that are directly or\r\nindirectly involved with substrate recognition. Chapter 3 describes\r\nmethods to produce genome length dengue 2 RNA from cDNA templates.
\r\n\r\nThe nonstructural protein NS3 is structurally related to viral trypsinlike\r\nproteases from the alpha-, picorna-, poty-, and pestiviruses. The\r\nhypothesis that the flavivirus nonstructural protein NS3 is a viral\r\nproteinase that generates the termini of several nonstructural proteins was\r\ntested using an efficient in vitro expression system and antisera specific for\r\nthe nonstructural proteins NS2B and NS3. A series of cDNA constructs\r\nwas transcribed using T7 RNA polymerase and the RNA translated in\r\nreticulocyte lysates. Proteolytic processing occurred in vitro to generate\r\nNS2B and NS3. The amino termini of NS2B and NS3 produced in vitro\r\nwere found to be the same as the termini of NS2B and NS3 isolated from\r\ninfected cells. Deletion analysis of cDNA constructs localized the protease\r\ndomain necessary and sufficient for correct cleavage to the first 184 amino\r\nacids of NS3. Kinetic analysis of processing events in vitro and experiments\r\nto examine the sensitivity of processing to dilution suggested that an\r\nintramolecular cleavage between NS2A and NS2B preceded an\r\nintramolecular cleavage between NS2B and NS3. The data from these\r\nexpression experiments confirm that NS3 is the viral proteinase\r\nresponsible for cleavage events generating the amino termini of NS2B and\r\nNS3 and presumably for cleavages generating the termini of NS4A and NS5\r\nas well.
\r\n\r\nBiochemical and genetic experiments using viral proteinases have\r\ndefined the sequence requirements for cleavage site recognition, but have\r\nnot identified residues within proteinases that interact with substrates. A\r\nbiochemical assay was developed that could identify residues which were\r\nimportant for substrate recognition. Chimeric proteases between yellow\r\nfever and dengue 2 were constructed that allowed mapping of regions\r\ninvolved in substrate recognition, and site directed mutagenesis was used\r\nto modulate processing efficiency.
\r\n\r\nExpression in vitro revealed that the dengue protease domain\r\nefficiently processes the yellow fever polyprotein between NS2A and NS2B\r\nand between NS2B and NS3, but that the reciprocal construct is inactive.\r\nThe dengue protease processes yellow fever cleavage sites more efficiently\r\nthan dengue cleavage sites, suggesting that suboptimal cleavage efficiency\r\nmay be used to increase levels of processing intermediates in vivo. By\r\nmutagenizing the putative substrate binding pocket it was possible to\r\nchange the substrate specificity of the yellow fever protease; changing a\r\nminimum of three amino acids in the yellow fever protease enabled it to\r\nrecognize dengue cleavage sites. This system allows identification of\r\nresidues which are directly or indirectly involved with enzyme-substrate\r\ninteraction, does not require a crystal structure, and can define the\r\nsubstrate preferences of individual members of a viral proteinase family.
\r\n\r\nFull-length cDNA clones, from which infectious RNA can be\r\ntranscribed, have been developed for a number of positive strand RNA\r\nviruses, including the flavivirus type virus, yellow fever. The technology\r\nnecessary to transcribe genomic RNA of dengue 2 virus was developed in\r\norder to better understand the molecular biology of the dengue subgroup. A\r\n5' structural region clone was engineered to transcribe authentic dengue\r\nRNA that contains an additional 1 or 2 residues at the 5' end. A 3'\r\nnonstructural region clone was engineered to allow production of run off\r\ntranscripts, and to allow directional ligation with the 5' structural region\r\nclone. In vitro ligation and transcription produces full-length genomic\r\nRNA which is noninfectious when transfected into mammalian tissue\r\nculture cells. Alternative methods for constructing cDNA clones and\r\nrecovering live dengue virus are discussed.
", "doi": "10.7907/nn0p-gt03", "publication_date": "1990", "thesis_type": "phd", "thesis_year": "1990" }, { "id": "thesis:522", "collection": "thesis", "collection_id": "522", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-02062007-131016", "type": "thesis", "title": "Effects of Hydrazine and Other Toxicants on Early Life Stages of California Brown Algae", "author": [ { "family_name": "James", "given_name": "David Earl", "clpid": "James-David-Earl" } ], "thesis_advisor": [ { "family_name": "North", "given_name": "Wheeler J.", "clpid": "North-W-J" } ], "thesis_committee": [ { "family_name": "North", "given_name": "Wheeler J.", "clpid": "North-W-J" }, { "family_name": "Brooks", "given_name": "Norman H.", "clpid": "Brooks-N-H" }, { "family_name": "Brokaw", "given_name": "Charles J.", "clpid": "Brokaw-C-J" }, { "family_name": "Morgan", "given_name": "James J.", "clpid": "Morgan-J-J" }, { "family_name": "Jackson", "given_name": "George", "clpid": "Jackson-George" }, { "family_name": "Hoffmann", "given_name": "Michael R.", "orcid": "0000-0001-6495-1946", "clpid": "Hoffmann-M-R" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Toxicity of hydrazine to early life stages of several species of California brown algae was demonstrated to occur at environmentally relevant concentrations. Effects of hydrazine on benthic organisms had not been previously studied.
\r\n\r\nPreliminary studies evaluated toxicity of boric acid, chlorine (as hypochlorite), lithium ion, tributyltin chloride and Zn(II).
\r\n\r\nA reliable bioassay technique was developed using digital image analysis to measure vegetative growth inhibition of brown algal gametophytes. Hydrazine toxicity threshold of Macrocystis pyrifera gametophytes was almost constant in 10 96-hour experiments, ranging from 3 - 5 ppb (96-160 nM).
\r\n\r\nDifferences in resistance to short-term hydrazine exposures were observed among three algal families of the order Laminariales. Two of three tested members of the family Alariaceae, Pterygophora californica and Eisenia arborea were among the most resistant species tested. The three tested species in the family Lessoniaceae, Macrocystis pyrifera, Nereocystis luetkeana and Pelagophycus porra, all fast-growing canopy-formers, were among the most sensitive tested species. Tested representatives of the family Laminariaceae varied in resistance. Laminaria farlowii was resistant. Laminaria dentigera and Laminaria ephemera were fairly sensitive.
\r\n\r\nHydrazine autoxidation rates varied by an order of magnitude in seawater sampled from different locations. Rates showed strong temperature dependence. Autoxidation at 10\u00b0C and below was much slower and indicated a higher activation energy than autoxidation at 20\u00b0C and above.
\r\n\r\nUndiluted trace hydrazine powerplant emissions from a time period when algal community composition changed in the vicinity of an outfall were compared to growth inhibition results from multivariate hydrazine toxicity experiments on Macrocystis gametophytes. Results indicated that several trace hydrazine discharges were of sufficient duration and concentration to have inhibited algal microscopic stages.
", "doi": "10.7907/WRCJ-G589", "publication_date": "1989", "thesis_type": "phd", "thesis_year": "1989" }, { "id": "thesis:7493", "collection": "thesis", "collection_id": "7493", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:02222013-111607349", "type": "thesis", "title": "Models for the Avoidance Response in Phycomyces", "author": [ { "family_name": "Matus Bloch", "given_name": "Ivan J.", "clpid": "Matus-Bloch-Ivan-J" } ], "thesis_advisor": [ { "family_name": "Berg", "given_name": "Howard C.", "clpid": "Berg-Howard-C" } ], "thesis_committee": [ { "family_name": "Berg", "given_name": "Howard C.", "clpid": "Berg-Howard-C" }, { "family_name": "Lester", "given_name": "Henry A.", "orcid": "0000-0002-5470-5255", "clpid": "Lester-H-A" }, { "family_name": "Brokaw", "given_name": "Charles J.", "clpid": "Brokaw-C-J" }, { "family_name": "Revel", "given_name": "Jean-Paul", "clpid": "Revel-J-P" }, { "family_name": "Pine", "given_name": "Jerome", "clpid": "Pine-J" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "The sporangiophore of the fungus Phycomyces is able to avoid obstacles placed a few millimeters from its growing zone. The work described in this thesis presents evidence that the avoidance response is mediated by gases. Avoidance occurs in still air in the diffusion limit, even at relative humidities close to 100%. It is shown that the effect of the surfaces of the obstacles cannot only be to reflect these gases: the surfaces must play a more active role. Models in which the surfaces adsorb growth-inhibitors or adsorb an inert precursor that is re-emitted as a growth-promoter that decays are in agreement with our experimental observations.
", "doi": "10.7907/c5e3-v765", "publication_date": "1988", "thesis_type": "phd", "thesis_year": "1988" }, { "id": "thesis:11472", "collection": "thesis", "collection_id": "11472", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04162019-154502622", "type": "thesis", "title": "The Avoidance Response of Phycomyces in a Controlled Environment", "author": [ { "family_name": "Meyer", "given_name": "Paul Wells", "clpid": "Meyer-Paul-Wells" } ], "thesis_advisor": [ { "family_name": "Berg", "given_name": "Howard C.", "clpid": "Berg-Howard-C" } ], "thesis_committee": [ { "family_name": "Berg", "given_name": "Howard C.", "clpid": "Berg-Howard-C" }, { "family_name": "Brokaw", "given_name": "Charles J.", "clpid": "Brokaw-C-J" }, { "family_name": "Lester", "given_name": "Henry A.", "orcid": "0000-0002-5470-5255", "clpid": "Lester-H-A" }, { "family_name": "Pine", "given_name": "Jerome", "clpid": "Pine-J" }, { "family_name": "Revel", "given_name": "Jean-Paul", "clpid": "Revel-J-P" } ], "local_group": [ { "literal": "div_biol" } ], "abstract": "If an object is placed 1 mm away from the growing zone of a Phycomyces sporangiophore growing in air, then after 2 to 6 min the sporangiophore bends away from the object, without ever touching it, at a rate of about 1\u00b0/min. The sporangiophore stops bending after about 30 min. This is called the avoidance response of Phycomyces.
\r\n\r\nHow does the sporangiophore detect the object? It seems likely that a chemical mechanism is involved, since other physical stimuli (light, electric and magnetic fields) have already been ruled out.
\r\n\r\nA simple mechanism was proposed 10 years ago, in which the ambient air currents near the surface of an object modify the distribution of a hypothetical, short-lived effector gas emitted by the sporangiophore. However, the avoidance response occurs at its usual rate in the complete absence of ambient air currents. Thus, the suppression of air currents near the surface of a solid object cannot provide the signal for the response.
\r\n\r\nThe avoidance rate depends significantly on the recent history of the experimental chamber, on the length of time the sporangiophore has spent inside the experimental chamber, and on other factors. By carefully controlling environmental variables, the variation in avoidance rate of different sporangiophores in successive experiments can be held to less than \u00b110%. This allows accurate determination of the distance dependence of the response, and accurate comparison of different types of barriers.
\r\n\r\nThe rate of the response falls off above 90 % relative humidity - but does not fall to zero. Surprisingly, the sporangiophore avoids a thin, 120 \u00b5m diameter parallel wire placed 0.5 mm away at about the same rate as it avoids another sporangiophore placed at the same distance. Also, the distance dependence of the avoidance response appears to be much weaker than previously reported, and the response may depend on the chemical composition of the object, in contrast to previous reports. These findings, combined with the results of calculations presented in Appendix 3, argue strongly against the hypothesis that the barrier acts merely by reflecting a diffusible substance emitted by the sporangiophore.
\r\n\r\nThe only remaining viable chemical mechanism for the avoidance response requires that the signal molecule emitted by the sporangiophore be adsorbed by the surface of the avoided object for a nonzero length of time, and not just be reflected by it. Three new versions of this hypothesis are presented which are consistent with the experimental results.
", "doi": "10.7907/s6zv-r568", "publication_date": "1986", "thesis_type": "phd", "thesis_year": "1986" }, { "id": "thesis:11455", "collection": "thesis", "collection_id": "11455", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04122019-155653613", "type": "thesis", "title": "The Structure and Expression of the Gene Coding for Bindin, a Species Specific Sea Urchin Protein", "author": [ { "family_name": "Gao", "given_name": "Boning", "orcid": "0000-0002-1382-395X", "clpid": "Gao-Boning" } ], "thesis_advisor": [ { "family_name": "Davidson", "given_name": "Eric H.", "clpid": "Davidson-E-H" } ], "thesis_committee": [ { "family_name": "Davidson", "given_name": "Eric H.", "clpid": "Davidson-E-H" }, { "family_name": "Brokaw", "given_name": "Charles J.", "clpid": "Brokaw-C-J" }, { "family_name": "Davidson", "given_name": "Norman R.", "clpid": "Davidson-N-R" }, { "family_name": "Rothenberg", "given_name": "Ellen V.", "orcid": "0000-0002-3901-347X", "clpid": "Rothenberg-E-V" }, { "family_name": "Strauss", "given_name": "James H.", "clpid": "Strauss-J-H" } ], "local_group": [ { "literal": "div_biol" } ], "abstract": "Bindin is a major protein of the sea urchin sperm acrosome granule which mediates the species-specific adhesion and binding of sperm to the egg. Bindin protein has been purified from the sperm of the sea urchin Strongylocentrotus purpuratus (S. purpuratus) and the protein has been partially sequenced. The work presented in this thesis is the isolation and the sequence analysis of bindin cDNA and gene, and the study of the expression of the bindin gene.
\r\n\r\nA \u03bbgt10 cDNA library was constructed from S. purpuratus testes poly(A)+ RNA. The library which was screened with a synthetic DNA probe prepared according to the known protein sequence yielded clones representing bindin cDNA. One of these clones containing an 1873 base pair (bp) insert was sequenced and found to code for a bindin precursor (prebindin) which is twice as large as the mature bindin protein. Upon immunoprecipitation with bindin antibody, the testes poly(A)+ RNA in vitro translation product yields a larger precursor. The bind in cDNA was used to study the tissue specificity of expression. The results show that bindin is a sperm specific protein -- its messenger RNA is not detected in the eggs, ovaries, early embryos, coelomocytes, tubefeet, lantern tissue or intestine that we tested.
\r\n\r\nSperm DNA isolated from several individuals was probed with bindin cDNA and reveals that there is one bindin gene per haploid genome. Haploid female coelomocyte DNA also possesses one bindin gene.
\r\n\r\nBindin cDNA was used to screen an EcoRI partially digested sea urchin S. purpuratus DNA charon 4A library. A clone containing a 14 kilobase (Kb) insert hybridized to the 3' end of the bindin cDNA. It also has overlapping restriction enzyme recognition sites with the 3' end of the bindin cDNA. There is an intron in the genomic clone upstream of this overlapping region since it did not hybridize with bindin cDNA. A \u03bbgt10 mini-genomic library was made and a 1.3 Kb genomic DNA clone which hybridized with bindin cDNA has been characterized and partially sequenced. It contains a 219 bp exon in which the 5' end lies 2 bp upstream of the AUG translation initiation codon. This exon is flanked by introns on either side. Thus, there are at least three introns in the bindin gene.
", "doi": "10.7907/h0pw-fh17", "publication_date": "1986", "thesis_type": "phd", "thesis_year": "1986" }, { "id": "thesis:11393", "collection": "thesis", "collection_id": "11393", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:02132019-181420941", "type": "thesis", "title": "Chemotaxis of Escherichia coli Studied Using Ionophoretic Stimulation", "author": [ { "family_name": "Segall", "given_name": "Jeffrey Edward", "clpid": "Segall-Jeffrey-Edward" } ], "thesis_advisor": [ { "family_name": "Berg", "given_name": "Howard C.", "clpid": "Berg-Howard-C" } ], "thesis_committee": [ { "family_name": "Brokaw", "given_name": "Charles J.", "clpid": "Brokaw-C-J" }, { "family_name": "Fender", "given_name": "Derek H.", "clpid": "Fender-D-H" }, { "family_name": "Hopfield", "given_name": "John J.", "clpid": "Hopfield-J-J" }, { "family_name": "Lester", "given_name": "Henry A.", "orcid": "0000-0002-5470-5255", "clpid": "Lester-H-A" }, { "family_name": "Simon", "given_name": "Melvin I.", "clpid": "Simon-M-I" }, { "family_name": "Berg", "given_name": "Howard C.", "clpid": "Berg-Howard-C" } ], "local_group": [ { "literal": "div_biol" } ], "abstract": "Chemotactic responses of the bacterium Escherichia coli were elicited by iontophoretic ejection of charged compounds from micropipettes. Responses were measured using cells tethered by a single flagellum and following the direction of rotation of the cell body (with cells viewed from above the surface to which the flagellum is attached) . Mean response latencies to addition of attractant or repellent were 0.1 to 0.2 seconds. Brief pulses of attractants and repellents were used to determine the impulse response for chemotaxis. In response to a brief pulse of attractant the counterclockwise (CCW) bias (fraction of time that the flagellar motor spent rotating CCW) increased rapidly to a peak, then fell below the prestimulus value, returning to baseline within 5 seconds -- the response was biphasic. Repellent impulse responses were similar but inverted. The attractant impulse response accurately predicted responses to step changes, linear ramp changes and sine wave changes in receptor occupancy. Mutants defective in the enzymes responsible for methylation (cheR) and demethylation (cheB), which do not adapt to attractant stimuli, gave monophasic impulse responses--only the initial peak was evident. Mutants defective in the cheZ gene product had responses that were slower than the wild-type by a factor of about 10. The responses of flagellar motors on filamentous cells also were studied. The reversals of two motors on the same cell were not correlated, but fluctuations in bias were correlated for motors less than l 0 microns apart. Responses of motors of filamentous cells to iontophoretic application of aspartate indicated that the internal chemotaxis signal travels about 2 microns in cells lacking the cheR and cheB gene products and about 6 microns in cells with a defective cheZ gene product. These data are consistent with a simple model involving destruction of a cellular chemotaxis signal by the cheZ gene product.
", "doi": "10.7907/6r2y-ba72", "publication_date": "1985", "thesis_type": "phd", "thesis_year": "1985" }, { "id": "thesis:5095", "collection": "thesis", "collection_id": "5095", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-12212004-095323", "type": "thesis", "title": "The Role of Filamin in the Morphogenesis of the Skeletal Muscle Sarcomere", "author": [ { "family_name": "Gomer", "given_name": "Richard Hans", "orcid": "0000-0003-2361-4307", "clpid": "Gomer-Richard-Hans" } ], "thesis_advisor": [ { "family_name": "Lazarides", "given_name": "Elias", "clpid": "Lazarides-E" } ], "thesis_committee": [ { "family_name": "Lazarides", "given_name": "Elias", "clpid": "Lazarides-E" }, { "family_name": "Brokaw", "given_name": "Charles J.", "clpid": "Brokaw-C-J" }, { "family_name": "Hudspeth", "given_name": "A. James", "clpid": "Hudspeth-A-J" }, { "family_name": "Meyerowitz", "given_name": "Elliot M.", "orcid": "0000-0003-4798-5153", "clpid": "Meyerowitz-E-M" }, { "family_name": "Revel", "given_name": "Jean-Paul", "clpid": "Revel-J-P" } ], "local_group": [ { "literal": "div_biol" } ], "abstract": "During chicken skeletal myogenesis in tissue culture, filamin is found on stress fibers in myoblasts and early myotubes. Approximately one day after fusion and shortly before \u03b1-actinin transits to Z lines, filamin disappears from the cells. The disappearance of filamin is correlated with a cessation of its synthesis. Approximately six days after fusion, filamin reappears at the Z lines of myogenic cells, shortly before desmin and vimentin transit to the Z line. In adult muscle, filamin is found at the periphery of the Z disk, along with desmin and vimentin. Peptide map analysis of the various filamins shows that gizzard and fibroblast filamins are identical while myoblast filamin is quite similar to these two filamins. Cultured myotube and adult myofibril filamins are virtually identical to each other and are quite different polypeptides when compared to gizzard, fibroblast and myoblast filamins. Analysis of terminally differentiated slow and fast muscle shows that both muscle types contain identical, skeletal muscle type filamins although in the slow muscle, filamin is distributed additionally on the I band. The molar filamin to actin ratio is 1:25 in gizzard and fibroblast, 1:54 in myoblasts, 1:820 in fast skeletal myofibrils and 1:82 in slow skeletal myofibrils.
\r\n\r\nThese results offer several new insights into eucaryotic molecular morphogenesis. From the disappearance of filamin during myogenesis, we see that a morphogenetic process may involve the temporary removal of a family of proteins. The different distributions of identical filamin polypeptides in slow and fast muscle indicates that filamin may be synthesized at different times and rates in the two myogenic processes. It appears that, at least in the case of the skeletal muscle sarcomere, temporal control of protein synthesis may be an important part of eucaryotic molecular morphogenesis.
", "doi": "10.7907/97M8-B306", "publication_date": "1983", "thesis_type": "phd", "thesis_year": "1983" }, { "id": "thesis:11873", "collection": "thesis", "collection_id": "11873", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10292019-140253277", "primary_object_url": { "basename": "Wang_C_1983.pdf", "content": "final", "filesize": 47575481, "license": "other", "mime_type": "application/pdf", "url": "/11873/1/Wang_C_1983.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Induction and Methylation of Heat Shock Proteins in Cultured Vertebrate Cells", "author": [ { "family_name": "Wang", "given_name": "Chung", "clpid": "Wang-Chung" } ], "thesis_advisor": [ { "family_name": "Lazarides", "given_name": "Elias", "clpid": "Lazarides-E" } ], "thesis_committee": [ { "family_name": "Lazarides", "given_name": "Elias", "clpid": "Lazarides-E" }, { "family_name": "Brokaw", "given_name": "Charles J.", "clpid": "Brokaw-C-J" }, { "family_name": "Attardi", "given_name": "Giuseppe", "clpid": "Attardi-G" }, { "family_name": "Revel", "given_name": "Jean-Paul", "clpid": "Revel-J-P" }, { "family_name": "Clarke", "given_name": "Steven G.", "clpid": "Clarke-Steven-G." } ], "local_group": [ { "literal": "div_biol" } ], "abstract": "When vertebrate cells are exposed to sodium arsenite, they respond by increased synthesis of a small number of polypeptides similar to the heat shock proteins, which are induced by exposure to 40-45\u00b0C. The 70,000 dalton inducible protein (hsp70) is the most commonly induced species and this protein is methylated at both lysyl and arginyl residues. In chicken fibroblasts, the hsp70 is composed of two major distinct isoelectric variants, as well as several minor components. The more acidic one (hsp70A; pI 5.6) is highly conserved and found in all vertebrate tissues and cultured cells examined, while the more basic one (hsp70B; pI 6.0) at present has only been found in avian cells.
\r\n\r\nThe hsp70 is a prominent cytoplasmic constituent under normal growth conditions. In chicken fibroblasts, the induction by arsenite not only increases the synthesis of hsp70 but also results in an accumulation of this protein. In contrast, the induction in 3T3 and SR-RSV 3T3 cells results in increased synthesis, but no accumulation of this polypeptide.
\r\n\r\nIn chicken cells, \u03b5-N-trimethyl-lysine has been identified as the major component of methyl-lysine species in hsp70, but the contribution of \u03b5-N-monomethyl-lysine and \u03b5-N-dimethyl-lysine is evident. The methyl-arginine of hsp70 is exclusively NG-monomethyl-arginine; these methylations appear to be stoichiometric. Furthermore, these methylations can be modulated by arsenite. In particular, in hsp70A the amount of \u03b5-N-trimethyl-lysine decreases and the \u03b5-N-dimethyl-lysine significantly increases, while in hsp70B the quantity of NG-monomethyl-arginine is reduce fivefold in the presence of sodium arsenite. In 3T3 and SR-RSV 3T3 cells, \u03b5-N-trimethyl-lysine appears to be the only methylated lysine species; both NG-monomethyl-arginine and NG,NG-dimethyl-arginine have been identified as the methylated arginyl residues. Similar to the homologous polypeptide in chicken fibroblasts, the level of arginyl methylation of hsp70 of 3T3 cells can be reduced in the presence of arsenite. This arsenite-induced reduction in arginyl methylation of hsp70 appears to be restricted to the polypeptides synthesized during the arsenite incubation. However, the arginyl methylation level of hsp70 of SR-RSV 3T3 is constitutively lower than their untransformed counterpart (3T3 cells), and the methylation cannot be reduced further by arsenite. In addition, the level of lysyl methylation of hsp70 remains the same after arsenite treatment and transformation. Since the basic amino acid methylation in total cellular proteins remains unchanged after arsenite incubation and Rous sarcoma virus transformation, the reduction in arginyl methylation of hsp70 in chicken fibroblasts and 3T3 cells by these treatments appears to be specific.
", "doi": "10.7907/mpys-2s35", "publication_date": "1983", "thesis_type": "phd", "thesis_year": "1983" }, { "id": "thesis:3662", "collection": "thesis", "collection_id": "3662", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09202006-152443", "type": "thesis", "title": "Iron Reduction and Micronutrient Nutrition of Juvenile Macrocystis pyrifera (L.) C. A. Agardh (Giant Kelp) Determined by a Chemically Defined Medium, Aquil", "author": [ { "family_name": "Anderson", "given_name": "Lisa", "clpid": "Anderson-Lisa" } ], "thesis_advisor": [ { "family_name": "North", "given_name": "Wheeler J.", "clpid": "North-W-J" } ], "thesis_committee": [ { "family_name": "Morgan", "given_name": "James J.", "clpid": "Morgan-J-J" }, { "family_name": "Brooks", "given_name": "Norman H.", "clpid": "Brooks-N-H" }, { "family_name": "Lowenstam", "given_name": "Heinz A.", "clpid": "Lowenstam-H-A" }, { "family_name": "Brokaw", "given_name": "Charles J.", "clpid": "Brokaw-C-J" }, { "family_name": "North", "given_name": "Wheeler J.", "clpid": "North-W-J" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Iron reduction and micronutrient nutrition of juvenile Macrocystis pyrifera (L.) C. A. Agardh (giant kelp) were investigated using a chemically defined artificial seawater medium, Aquil. Juvenile sporophytes were grown and Aquil formulations were prepared in a Class 1000 cleanroom. Weights of the juveniles at the beginning and end of experiments determined the success of the various Aquil formulations.
\r\n\r\nMicronutrient experiments showed that kelp store surprisingly large quantities of Fe, Mn, Cu, Zn, Mo, Co and I, enough for 20- to 30-fold increases in weight. A maximum growth rate of 0.38 per day was measured for juvenile Macrocystis grown in Aquil. X-ray fluorescence analysis of dried, pressed blades determined kelp tissue element concentrations.
\r\n\r\nKelp grew fastest with 250 nM Fe, 5 nM Mn, 100 nM Zn, 1000 tiM No and 300 mM Co. Concentrations of iodine up to 500 nM I- and of copper up to 500 nM produced neither stimulating nor inhibitory responses. Theoretical chemical species concentrations in Aquil formulations were calculated using the thermodynamic equilibrium computer program REDEQL2.
\r\n\r\nKelp reduced Fe(III) to Fe(II) supporting the hypothesis that prior to uptake, iron is reduced in and then dissociates from the chelate complex, Fe-EDTA. This mediation was enhanced by the presence of light. The effects of photoreduction alone on Fe(III) reduction were studied, establishing its minor contribution as a source of Fe(II).
", "doi": "10.7907/t2eq-ve46", "publication_date": "1982", "thesis_type": "phd", "thesis_year": "1982" }, { "id": "thesis:10888", "collection": "thesis", "collection_id": "10888", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05152018-105719665", "primary_object_url": { "basename": "Granger_BL_1982.pdf", "content": "final", "filesize": 113586082, "license": "other", "mime_type": "application/pdf", "url": "/10888/1/Granger_BL_1982.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Composition and Function of Intermediate Filaments in Avian Muscle Cells and Erythrocytes", "author": [ { "family_name": "Granger", "given_name": "Bruce Leslie", "clpid": "Granger-Bruce-Leslie" } ], "thesis_advisor": [ { "family_name": "Lazarides", "given_name": "Elias", "clpid": "Lazarides-E" } ], "thesis_committee": [ { "family_name": "Lazarides", "given_name": "Elias", "clpid": "Lazarides-E" }, { "family_name": "Brockes", "given_name": "Jeremy P.", "orcid": "0000-0002-3395-5159", "clpid": "Brockes-Jeremy-P" }, { "family_name": "Brokaw", "given_name": "Charles J.", "clpid": "Brokaw-C-J" }, { "family_name": "Berg", "given_name": "Howard C.", "clpid": "Berg-Howard-C" }, { "family_name": "Revel", "given_name": "Jean-Paul", "clpid": "Revel-J-P" } ], "local_group": [ { "literal": "div_biol" } ], "abstract": "Intermediate filaments comprise a family of morphologically similar cytoplasmic structures whose individual subunits are biochemically and immunologically distinguishable, and largely cell-type specific. This thesis is an investigation of the intermediate filaments in avian smooth and skeletal muscle, and avian erythrocytes.
\r\n\r\nConditions have been found under which sheets of interconnected Z-discs can be generated from skeletal muscle. The stability of these sheets demonstrates that the Z-discs of adjacent myofibrils are firmly linked to one another. Desmin, the intermediate filament subunit characteristic of muscle, encircles each Z-disc and thereby forms an insoluble, two-dimensional scaffold at right angles to the fiber axis within each Z-plane. Desmin may thus be responsible for maintaining the cross-striated appearance of skeletal muscle fibers, and may function to mechanically integrate the contractile actions of their constituent myofibrils. Vimentin, the intermediate filament subunit characteristic of mesenchymal cells, coexists with desmin at the periphery of the Z-disc, and demonstrates that a terminally differentiated cell can possess more than one class of intermediate filament subunit.
\r\n\r\nA 230,000 dalton polypeptide, named synemin, copurifies with desmin from smooth muscle. It coexists and colocalizes with desmin and vimentin in skeletal muscle at all stages of differentiation, from fusing myoblasts to mature fibers. Nondenaturing conditions under which synemin can be separated from desmin and vimentin have not been found.
\r\n\r\nDetection of synemin in avian erythrocytes has led to the realization that this cell might be a relatively simple model system for the study of intermediate filaments. A fraction of the intermediate filaments in avian erythrocytes is stably associated with the plasma membrane, but can be selectively removed from it with water; this results in preparations consisting predominantly of vimentin and synemin. Immunoelectron microscopy reveals that vimentin forms the bulk of the core filament in these cells, and synemin exists at regular intervals along this core. The axial periodicity of synemin appears to change during erythropoiesis, perhaps in accordance with some structural or functional change in the filaments. Synemin appears to crosslink the filaments through self-association, and may thus regulate the rigidity or dispersion of the intermediate filament network in erythrocytes as well as in muscle cells.
", "doi": "10.7907/z9x1-xs25", "publication_date": "1982", "thesis_type": "phd", "thesis_year": "1982" }, { "id": "thesis:11843", "collection": "thesis", "collection_id": "11843", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10222019-143344602", "type": "thesis", "title": "Behavioral Neurogenetic Studies of a Circadian Clock in Drosophila melanogaster", "author": [ { "family_name": "Orr", "given_name": "Dominic Ping-Yim", "clpid": "Orr-Dominic-Ping-Yim" } ], "thesis_advisor": [ { "family_name": "Strumwasser", "given_name": "Felix", "clpid": "Strumwasser-F" }, { "family_name": "Konopka", "given_name": "Ronald J.", "clpid": "Konopka-Ronald-J" } ], "thesis_committee": [ { "family_name": "Brokaw", "given_name": "Charles J.", "clpid": "Brokaw-C-J" }, { "family_name": "Konopka", "given_name": "Ronald J.", "clpid": "Konopka-Ronald-J" }, { "family_name": "Konishi", "given_name": "Masakazu", "clpid": "Konishi-M" }, { "family_name": "Hopfield", "given_name": "John J.", "clpid": "Hopfield-J-J" }, { "family_name": "Strumwasser", "given_name": "Felix", "clpid": "Strumwasser-F" } ], "local_group": [ { "literal": "div_biol" } ], "abstract": "The circadian clock controlling the locomotor activity of the adult fruitfly, Drosophila melanogaster, is studied in one wild-type and five clock mutant strains. Locomotive activity of individual flies are monitored using arrays of infra-red beams and detectors. It is found that the temperature compensation mechanism is intact in the mutants And and ClkK06, is slightly defective in the mutant pers and is grossly defective in the mutants perl1 and perl2. In the pers and perl1 mutants, this defect is enhanced when both eyes and major parts of both optic lobes are eliminated by a genetic mutation (sine oculus). The inter-individual variation of periods in a strain is found to increase much more than linearly with the average period of the same strain. The interaction between the And and the per loci and that between the And and ClkK06 loci are found to be either very weak or non-existent (effects of mutations additive), whereas the interactions among the various alleles in the per locus are found to be strong (effects of mutations non-additive).
\r\n\r\nTen 'Phase Resetting Curves' (PRC) obtained with saturating light pulses for six strains of flies at various temperatures are presented. All the ten cases exhibit basically 'type-1' resetting behavior (average slope = 1). Comparisons of the PRC's for pers, perl1 and wild-type at 17\u00b0C suggest that the mutations pers and perl1 change the period of the circadian clock by differentially shortening and lengthening, respectively, the duration of the 'subjective day' phase of the oscillation. Comparisons between the PRC's for pers at 17\u00b0C, 22\u00b0C, and 25\u00b0C and comparison between the wild-type PRC's at 17\u00b0C and 22\u00b0C do not reveal major changes in the temporal structure of these two circadian clocks over the stated temperature ranges.
\r\n\r\nThe responses of one wild-type and five mutant circadian clocks to sustained dim light of the range 5 x 10-4 lux to 50 lux at 22\u00b0C are studied. In each strain, a critical 'window' of light intensity is found within which a variety of unstable clock features, including arrhythmia, are observed. The light intensity at which this critical window occurs in each of the mutant is 5 to 10 times lower than that in the wild-type. Responses from a ERG-defective mutant (norpA) are found to be qualitatively, but not quantitatively, similar to that of the wild-type. Responses from an eyeless and ocelli-less mutant (sine oculus) indicate that both period changes and arrhythmicity can be elicited by light in the absence of the compound eyes and ocelli. However, the sharp dependence of the occurences of these phenomena on light intensity is lost in this mutant.
\r\n\r\nArguments are presented to suggest that none of the four mutations -- And, ClkK06, pers, and perl1 -- cause changes of period by mimicking the effects of tonic light on the Drosophila circadian system.
\r\n\r\nThe phase resetting curves (PRC) and the dim light responses described above are found to be incompatible with a particular model of the Velocity Response Curve (VRC) theory to inter-relate the phasic to tonic effects of light, in which the tonic effect of light is assumed to be the result of a summation of the effects of a contiguous series of single Light pulses, taking into account adaptation.
", "doi": "10.7907/wp4e-5054", "publication_date": "1982", "thesis_type": "phd", "thesis_year": "1982" }, { "id": "thesis:10886", "collection": "thesis", "collection_id": "10886", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05142018-174410594", "primary_object_url": { "basename": "Gard_DL_1982.pdf", "content": "final", "filesize": 118360636, "license": "other", "mime_type": "application/pdf", "url": "/10886/1/Gard_DL_1982.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Intermediate Filaments and Myogenesis in vitro", "author": [ { "family_name": "Gard", "given_name": "David Lynn", "clpid": "Gard-David-Lynn" } ], "thesis_advisor": [ { "family_name": "Lazarides", "given_name": "Elias", "clpid": "Lazarides-E" } ], "thesis_committee": [ { "family_name": "Lazarides", "given_name": "Elias", "clpid": "Lazarides-E" }, { "family_name": "Brokaw", "given_name": "Charles J.", "clpid": "Brokaw-C-J" }, { "family_name": "Kennedy", "given_name": "Mary B.", "orcid": "0000-0003-1369-0525", "clpid": "Kennedy-M-B" }, { "family_name": "Mitchell", "given_name": "Herschel K.", "clpid": "Mitchell-H-K" }, { "family_name": "Revel", "given_name": "Jean-Paul", "clpid": "Revel-J-P" } ], "local_group": [ { "literal": "div_biol" } ], "abstract": "This thesis describes my investigations into the composition and function of intermediate filaments (IF) during myogenesis in vitro. I have found that avian embryonic myotubes cultured in vitro contain two intermediate filament subunits, desmin and vimentin. Prior to myoblast fusion vimentin is the sole IF subunit protein detectable by electrophoretic and immunological techniques. The onset of desmin synthesis and its cytoplasmic accumulation appear to coincide with fusion of myoblasts into multinucleate myotubes. Immunofluorescence reveals dense networks of desmin- and vimentin-containing filaments in the sarcoplasm of immature myotubes; however, late in myogenesis antisera to both desmin and vimentin are observed to stain the Z-lines of myofibrils. Double immunofluorescence microscopy using antisera to \u03b1-actinin and desmin revealed that this association occurs after the assembly of \u03b1-actinin into Z-lines, at a time when individual myofibrils are being organized into bundles. Phosphorylation of intermediate filament proteins in muscle has been previously reported (O'Connor et al., Proc. Natl. Acad. Sci. U.S.A. 76: 819-823, 1979). Using two-dimensional tryptic analysis I have found that desmin from embryonic myotubes is phosphorylated at multiple sites which correspond to sites phosphorylated by cAMP-dependent protein kinase in vitro. I have observed phosphorylation of desmin and vimentin in intact myotubes at all stages of myogenesis. However, treatment of mature (7 day and older) myotubes with 8-BrcAMP or isoproterenol results in a specific 2-3 fold increase in phosphorylation of these proteins, with a corresponding increase in 32PO4 incorporation into one major phosphopeptide of desmin. Preliminary evidence indicates that treatment of 6-8 day myotubes with 8-BrcAMP or isoproterenol significantly inhibits the transition of intermediate filaments to the Z-line which occurs during normal myogenesis. These observations suggest that intermediate filaments containing desmin and vimentin are responsible for the organization of skeletal muscle myofibrils into an integral contractile machinery, and that cAMP-dependent phosphorylation of desmin and vimentin plays an important role in the regulation of this function.
", "doi": "10.7907/e5gk-4c77", "publication_date": "1982", "thesis_type": "phd", "thesis_year": "1982" } ]