[
    {
        "id": "thesis:16403",
        "collection": "thesis",
        "collection_id": "16403",
        "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05212024-230410309",
        "primary_object_url": {
            "basename": "Helfer_RG_1940.pdf",
            "content": "final",
            "filesize": 31392762,
            "license": "other",
            "mime_type": "application/pdf",
            "url": "/16403/1/Helfer_RG_1940.pdf",
            "version": "v2.0.0"
        },
        "type": "thesis",
        "title": "A Comparison of X-ray Induced and Naturally Occurring Chromosomal Variations in Drosophila Pseudoobscura",
        "author": [
            {
                "family_name": "Helfer",
                "given_name": "Robert George",
                "clpid": "Helfer-Robert-George"
            }
        ],
        "thesis_advisor": [
            {
                "family_name": "Dobzhansky",
                "given_name": "Theodosius Grigorievich",
                "clpid": "Dobzhansky-Th"
            }
        ],
        "thesis_committee": [
            {
                "family_name": "Unknown",
                "given_name": "Unknown"
            }
        ],
        "local_group": [
            {
                "literal": "div_biol"
            }
        ],
        "abstract": "<p>Summary:</p>\r\n\r\n<p>1. The distribution of 347 breaks induced by X-ray treatment\r\nin the chromosomes of Drosophila pseudoobscura was studied.\r\nThe frequencies of the breaks in the different chromosomes\r\nare in the proportion to the lengths of the latter.</p>\r\n\r\n<p>2. The induced breaks in the third chromosome are not distributed\r\nentirely at random. The frequency of the breaks in the\r\nheterochromatin as compared with those in the euchromatin,\r\nis much greater than would be expected on the basis of the\r\nlengths of the heterochromatic portions in the salivary gland\r\ncells, but probably smaller than would be expected on the\r\nbasis of its length in the mitotic chromosomes. Within the\r\neuchromatic portions the frequency of breaks increases\r\nslightly from the proximal to the distal end.</p>\r\n\r\n<p>3. Aside from the regularity mentioned in the preceding paragraph,\r\nthe breaks in the third chromosome show no tendency to be\r\nconcentrated around any \"weak points.\" In any case, a\r\ncomparison of the induced breaks with those observed in\r\nthe naturally occurring chromosomal aberrations shows very\r\nfew coincidences. None of the inversions induced by X-ray\r\ntreatment proved similar to any of the naturally occurring\r\ninversions.</p>\r\n\r\n<p>4. The reunion of the chromosome fragments produced by X-ray\r\ntreatment is not at random, inversions being more and translocations\r\nless frequent than expected.</p>\r\n\r\n<p>5. Several mosaic chromosomal observations are described. An\r\nanalysis of these aberrations seems to argue in favor of the\r\n\"breakage first,\" rather than the \"contact\" hypothesis of\r\nthe origin of chromosomal aberrations.</p>\r\n\r\n<p>6. The \"breakage first\" hypothesis is also favored by the\r\nobserved aberration in which paternal as well as maternal\r\nchromosomes seem to be involved.</p>\r\n\r\n<p>7. An aberration involving a terminal attachment, and another\r\nshowing what appears to be a branched chromosome, are\r\ndescribed.</p>",
        "doi": "10.7907/jreq-0n39",
        "publication_date": "1940",
        "thesis_type": "phd",
        "thesis_year": "1940"
    },
    {
        "id": "thesis:17042",
        "collection": "thesis",
        "collection_id": "17042",
        "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03032025-224902902",
        "primary_object_url": {
            "basename": "Miller_DD_1940.pdf",
            "content": "final",
            "filesize": 27409244,
            "license": "other",
            "mime_type": "application/pdf",
            "url": "/17042/1/Miller_DD_1940.pdf",
            "version": "v2.0.0"
        },
        "type": "thesis",
        "title": "Cytological and Genetic Studies on Drosophila algonquin and Related Species",
        "author": [
            {
                "family_name": "Miller",
                "given_name": "Dwight Dana",
                "clpid": "Miller-Dwight-Dana"
            }
        ],
        "thesis_advisor": [
            {
                "family_name": "Sturtevant",
                "given_name": "Alfred Henry",
                "clpid": "Sturtevant-A-H"
            },
            {
                "family_name": "Dobzhansky",
                "given_name": "Theodosius Grigorievich",
                "clpid": "Dobzhansky-Th"
            }
        ],
        "thesis_committee": [
            {
                "family_name": "Unknown",
                "given_name": "Unknown"
            }
        ],
        "local_group": [
            {
                "literal": "div_biol"
            }
        ],
        "abstract": "No abstract.",
        "doi": "10.7907/adsk-sq92",
        "publication_date": "1940",
        "thesis_type": "phd",
        "thesis_year": "1940"
    },
    {
        "id": "thesis:2784",
        "collection": "thesis",
        "collection_id": "2784",
        "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06302004-101131",
        "type": "thesis",
        "title": "Genetic and Cytological Maps of the Autosomes in Drosophila pseudoobscura",
        "author": [
            {
                "family_name": "Tan",
                "given_name": "Jiazhen",
                "clpid": "Tan-Jiazhen"
            }
        ],
        "thesis_advisor": [
            {
                "family_name": "Dobzhansky",
                "given_name": "Theodosius Grigorievich",
                "clpid": "Dobzhansky-Th"
            }
        ],
        "thesis_committee": [
            {
                "family_name": "Unknown",
                "given_name": "Unknown"
            }
        ],
        "local_group": [
            {
                "literal": "Caltech Distinguished Alumni Award"
            },
            {
                "literal": "div_biol"
            }
        ],
        "abstract": "No Abstract.",
        "doi": "10.7907/72KD-6D58",
        "publication_date": "1936",
        "thesis_type": "phd",
        "thesis_year": "1936"
    }
]