[ { "id": "authors:eb1n6-2an16", "collection": "authors", "collection_id": "eb1n6-2an16", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150423-095744078", "type": "article", "title": "Erich Walther Six (1926-2014) In Memoriam", "author": [ { "family_name": "Lindqvist", "given_name": "B. H.", "clpid": "Lindqvist-B-H" }, { "family_name": "Bertani", "given_name": "L. E.", "clpid": "Bertani-L-E" } ], "abstract": "Erich Six was born in 1926 in Frankfurt, Germany. He studied at the University there, obtaining a Ph.D. in Biophysics in 1954. His research concerned indirect effects of radiation. As a research fellow of the German Research Council, he studied radiation effects on the green alga Acetabularia. In 1956 he came to the Biology Division of the California Institute of Technology in Pasadena, where he learned bacteriophage lore and joined G. and L.E. Bertani working on the genetics of phage P2. His first paper on P2 was in Volume 2 of Virology (PMID: 13593178). He was back in Germany, at the Max Planck Institute for Biology in T\u00fcbingen for most of 1958, but returned to the United States the following year, to the Department of Biology at the University of Rochester, as an associate of A.M. Campbell. Soon after, he was offered a faculty position in the Microbiology Department at the University of Iowa Medical School, where he remained, giving courses in microbial genetics, until his retirement in 1996. As Professor Emeritus, he continued to conduct experiments and to communicate actively with colleagues. His last paper was published in Virology in 2001 (PMID: 11312661).", "doi": "10.1016/j.virol.2015.01.012", "issn": "0042-6822", "publisher": "Elsevier", "publication": "Virology", "publication_date": "2015-04", "volume": "478", "pages": "153" }, { "id": "authors:jy9b0-ahn83", "collection": "authors", "collection_id": "jy9b0-ahn83", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150413-080942942", "type": "article", "title": "Genome Sequence of Magnetospirillum magnetotacticum Strain MS-1", "author": [ { "family_name": "Smalley", "given_name": "Matthew D.", "clpid": "Smalley-M-D" }, { "family_name": "Marinov", "given_name": "Georgi K.", "orcid": "0000-0003-1822-7273", "clpid": "Marinov-G-K" }, { "family_name": "Bertani", "given_name": "L. Elizabeth", "clpid": "Bertani-L-E" }, { "family_name": "DeSalvo", "given_name": "Gilberto", "clpid": "DeSalvo-G" } ], "abstract": "Here, we report the genome sequence of Magnetospirillum magnetotacticum strain MS-1, which consists of of 36 contigs and 4,136 protein-coding genes.", "doi": "10.1128/genomeA.00233-15", "pmcid": "PMC4384492", "issn": "2169-8287", "publisher": "American Society for Microbiology", "publication": "Genome Announcements", "publication_date": "2015-03", "series_number": "2", "volume": "3", "issue": "2", "pages": "Art. No. e00233-15" }, { "id": "authors:d4r7j-4x114", "collection": "authors", "collection_id": "d4r7j-4x114", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141022-080700248", "type": "article", "title": "Bugbuster \u2014 survivability of living bacteria upon shock compression", "author": [ { "family_name": "Willis", "given_name": "M. J.", "clpid": "Willis-M-J" }, { "family_name": "Ahrens", "given_name": "T. J.", "clpid": "Ahrens-T-J" }, { "family_name": "Bertani", "given_name": "L. E.", "clpid": "Bertani-L-E" }, { "family_name": "Nash", "given_name": "C. Z.", "clpid": "Nash-C-Z" } ], "abstract": "Shock recovery experiments were conducted on suspensions of 10^6/ml E. coli bacteria contained in a water-based medium that is emplaced within stainless steel containers. The water is shocked and recovered. These experiments simulate the environment of bacteria residing either in surface bodies of water or in subsurface water-filled cracks in rocks. Early Earth life is likely to have existed in such environments. However, the E. coli are not believed to be representative of early life and are merely used here for initial experiments. Some 10^(\u2212 2) to 10^(\u2212 4) of the bacteria population survived initial (800 ns duration) shock pressures in water of 220 and 260 MPa. TEM images of shock recovered bacteria indicate cell wall rupture and delamination. This appears to be the mortality mechanism.\nThe TEM images indicate cell wall indentations may be occurring as would be consistent with Rayleigh\u2013Taylor or Richtmyer\u2013Meshkov fluid instabilities. In the present case, we consider the experiments as representing three layers of fluids: (1) The water-based medium, a stronger and possibly denser cell wall medium, and the interior of the cell cytoplasm. Variations of only 10\u201315% are expected in density. (2) A second mechanism that may cause cell wall failure is the multiple shock (nearly isentropic) compression freezing of liquid water medium into ice VI or ice VII high pressure phase that are 20% to 25% denser than the liquid. The decrease in volume associated with the transformation is expected to induce overpressures in the still liquid cell cytoplasm.\nCell dynamic tensile wall strength thus appears to be a critical parameter from either of the above failure modes. Because the strain rate dependence of cell wall tensile strength is unstudied, we utilize the Grady and Lipkin [D.E. Grady, L. Lipkin, Criteria for impulsive rock fracture, Geophys. Res. Lett. 7 (1980) 255\u2013258] model of tensile failure versus time scale (strain rate). Our single datum is fit to this law and we assume that at low strain rates, overpressures exceeding the cell Turgor pressure require on the order of \u223c10^3 s. This model which has been applied to brittle media and metals for describing failure may permit application of short duration laboratory experiments as in the present ones to infer responses of organisms to much lower shock pressures, but for longer time scales (10^0 to 10^3 s) of planetary impacts.\nUsing the present data for E. coli and applying the Grady and Lipkin model, we find that a 1.5 km diameter impactor will cause mortality of bacteria within a radius of 10^2 km but upon stress related attenuation the subsurface bacteria outside of this radius should survive.", "doi": "10.1016/j.epsl.2006.03.054", "issn": "0012-821X", "publisher": "Elsevier", "publication": "Earth and Planetary Science Letters", "publication_date": "2006-07-30", "series_number": "3-4", "volume": "247", "issue": "3-4", "pages": "185-196" }, { "id": "authors:6b9h2-hgm48", "collection": "authors", "collection_id": "6b9h2-hgm48", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130124-103930877", "type": "article", "title": "Physical and genetic characterization of the genome of\n Magnetospirillum magnetotacticum, strain MS-1", "author": [ { "family_name": "Bertani", "given_name": "L. Elizabeth", "clpid": "Bertani-L-E" }, { "family_name": "Weko", "given_name": "Juliani", "clpid": "Weko-J" }, { "family_name": "Phillips", "given_name": "Khristie V.", "clpid": "Phillips-K-V" }, { "family_name": "Gray", "given_name": "Rachel F.", "clpid": "Gray-R-F" }, { "family_name": "Kirschvink", "given_name": "Joseph L.", "orcid": "0000-0001-9486-6689", "clpid": "Kirschvink-J-L" } ], "abstract": "Pulsed-field gel analysis of Magnetospirillum magnetotacticum, strain MS-1, indicates that the genome is a single, circular structure of about 4.3 mb. A few genes, identified by sequence similarity, have been localized and arranged in a map with dnaA, indicating the presumed origin of replication. There are at least two rRNA operons. In addition, rRNA genes are found on a 40 kb, possibly extrachromosomal, structure. The genes thought to be involved in magnetite synthesis, bfr and magA, are located in the same 17% of the genome. A one base pair-overlap seen in the bfr genes of MS-1 is found also in the closely related magnetic strain AMB-1, but not in the non-magnetic relative A.itersonii.", "doi": "10.1016/S0378-1119(01)00331-6", "issn": "0378-1119", "publisher": "Elsevier", "publication": "Gene", "publication_date": "2001-02-21", "series_number": "2", "volume": "264", "issue": "2", "pages": "257-263" }, { "id": "authors:wqkh1-9q955", "collection": "authors", "collection_id": "wqkh1-9q955", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130125-142540155", "type": "article", "title": "Paleoproterozoic snowball Earth: Extreme climatic and geochemical global change and its biological consequences", "author": [ { "family_name": "Kirschvink", "given_name": "Joseph L.", "orcid": "0000-0001-9486-6689", "clpid": "Kirschvink-J-L" }, { "family_name": "Gaidos", "given_name": "Eric J.", "orcid": "0000-0002-5258-6846", "clpid": "Gaidos-E-J" }, { "family_name": "Bertani", "given_name": "L. Elizabeth", "clpid": "Bertani-L-E" }, { "family_name": "Beukes", "given_name": "Nicholas J.", "clpid": "Beukes-N-J" }, { "family_name": "Gutzmer", "given_name": "Jens", "clpid": "Gutzmer-J" }, { "family_name": "Maepa", "given_name": "Linda N.", "clpid": "Maepa-L-N" }, { "family_name": "Steinberger", "given_name": "Rachel E.", "clpid": "Steinberger-R-E" } ], "abstract": "Geological, geophysical, and geochemical data support a theory that Earth experienced several intervals of intense, global glaciation (\"snowball Earth\" conditions) during Precambrian time. This snowball model predicts that postglacial, greenhouse-induced warming would lead to the deposition of banded iron formations and cap carbonates. Although global glaciation would have drastically curtailed biological productivity, melting of the oceanic ice would also have induced a cyanobacterial bloom, leading to an oxygen spike in the euphotic zone and to the oxidative precipitation of iron and manganese. A Paleoproterozoic snowball Earth at 2.4 Giga-annum before present (Ga) immediately precedes the Kalahari Manganese Field in southern Africa, suggesting that this rapid and massive change in global climate was responsible for its deposition. As large quantities of O_2 are needed to precipitate this Mn, photosystem II and oxygen radical protection mechanisms must have evolved before 2.4 Ga. This geochemical event may have triggered a compensatory evolutionary branching in the Fe/Mn superoxide dismutase enzyme, providing a Paleoproterozoic calibration point for studies of molecular evolution.", "doi": "10.1073/pnas.97.4.1400", "pmcid": "PMC26445", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "2000-02-15", "series_number": "4", "volume": "97", "issue": "4", "pages": "1400-1405" }, { "id": "authors:0z9d4-r3d28", "collection": "authors", "collection_id": "0z9d4-r3d28", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130124-105456864", "type": "article", "title": "Evidence for two types of subunits in the bacterioferritin of\n Magnetospirillum magnetotacticum", "author": [ { "family_name": "Bertani", "given_name": "L. Elizabeth", "clpid": "Bertani-L-E" }, { "family_name": "Huang", "given_name": "Jerry S.", "clpid": "Huang-J-S" }, { "family_name": "Weir", "given_name": "Barbara A.", "clpid": "Weir-B-A" }, { "family_name": "Kirschvink", "given_name": "Joseph L.", "orcid": "0000-0001-9486-6689", "clpid": "Kirschvink-J-L" } ], "abstract": "In order to investigate the role of bacterioferritin (Bfr) in the biomineralization of magnetite by microorganisms, we have cloned and sequenced the bfr genes from M. magnetotacticum. The organism has two bfr genes that overlap by one nucleotide. Both encode putative protein products of 18 kDa, the expected size for Bfr subunits, and show a strong similarity to other Bfr subunit proteins. By scanning the DNA sequence databases, we found that a limited number of other organisms, including N. gonorrhea, P. aeruginosa, and Synechocystis PCC6803, also have two bfr genes. When the sequences of a number of microbial Bfrs are compared with each other, they fall into two distinct types with the organisms mentioned above having one of each type. Differences in heme- and metal-binding sites and ferroxidase activities of the two types of subunits are discussed.", "doi": "10.1016/S0378-1119(97)00424-1", "issn": "0378-1119", "publisher": "Elsevier", "publication": "Gene", "publication_date": "1997-11-12", "series_number": "1-2", "volume": "201", "issue": "1-2", "pages": "31-36" }, { "id": "authors:1bk2d-nct40", "collection": "authors", "collection_id": "1bk2d-nct40", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:LJUpnas84", "type": "article", "title": "DNA sequences of the repressor gene and operator region of bacteriophage P2", "author": [ { "family_name": "Ljungquist", "given_name": "Elisabeth", "clpid": "Ljungquist-E" }, { "family_name": "Kockum", "given_name": "Kerstin", "clpid": "Kockum-K" }, { "family_name": "Bertani", "given_name": "L. Elizabeth", "clpid": "Bertani-L-E" } ], "abstract": "The nucleotide sequence of the repressor gene C of the temperate phage P2 has been determined. It codes for a nonbasic polypeptide, 99 amino acids long. Twelve repressor-defective mutants have been mapped. All but one are located within the presumed coding part of the gene. There is a strong promoter sequence and an 8-base-pair inverted repeat preceding the gene. The P2 repressor protein shows structural similarity to other DNA-binding proteins. The operator region for the early replication functions was located by sequencing the DNA of three virulent mutants. The sequence indicates that there are two repressor-binding sites. In addition, one of the sites shows sequence homology with part of the operator region of the biotin operon of Escherichia coli.", "doi": "10.1073/pnas.81.13.3988", "pmcid": "PMC345353", "issn": "0027-8424", "publisher": "National Academy of Sciences", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "publication_date": "1984-07-01", "series_number": "13", "volume": "81", "issue": "13", "pages": "3988-3992" } ]