Biographical Memoirs Volume 59 (1990) / Chapter Skim
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Theophilus Shickel Painter
Theophilus Shickel Painter
Pages 308-337
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= his?
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I Muller, one of the original trio of Morgan's graduate students, tract created a great stir in genetics with his 1927 discovery that X-rays will induce mutations at frequencies hundreds, even thousands, of times higher than rates of spontaneous mutation.
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out the relation of point mutations to radiation dosage, Painter collaborates! with Muller in analyzing chromosomal rearrangements, and Patterson explored an exciting new field mosaic types of mutation produced by X-rays.
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More than a clecacle earlier he had established, in studies of the fertilization and development of Ascaris eggs, that each chromosome controls development inclividually. Chromosomes, furthermore—although they seem to disappear after the close of each mitotic cell division—have a persistent continuity and reappear in the next mitosis in the same place they occupier!
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The second, John Thomas Patterson, was the young head of the Zoology Department at the University of Texas in Austin. Patterson offered Painter the academic post that brought him to the institution where he would spend the remainder of his life.
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He often visited his students in the laboratory to exchange ideas, giving them encouragement as well as direction. He taught undergraduate courses in aciclition to graduate cytology, and for many years- a popular premedical course in comparative anatomy.
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CHROMOSOME CYTOLOGY AND SEX CHROMOSOMES Back at the University of Texas after his military service, Painter resumed his cytological studies of spermatogenesis in a common small lizard, Anolis caroZinensas. But he quickly turned to a new problem: the number of mammalian chromosomes and their morphology, with particular emphasis on the nature of sex determination.
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As in insects, then, if all egg cells carry a single X-chromosome anct if fertilization by the two sorts of spermatozoa is random, the X-bearing sperm would produce female offspring; the Y-bearing sperm wouIcl produce males. Having thus shown that sex determination in a marsupial mammal corresponds to the process already known from invertebrates, Painter set his sights on placental, or eutherian, mammals, and- through a fortunate circumstance was able to obtain fresh human testicular tissue.
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the morphology and behavior of the sex chromosomes (X and Y) during meiosis; and (4)
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and soft somatic tissues (especially embryonic tissues) that could be smeared; using coIchicine to halt clividing cells in metaphase and hence greatly increase the number of such cells observable; and using hypotonic salt solutions to spread the chromosomes of dividing cells apart to eliminate their clumping into uncountable masses, I
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have a high chromosome number ranging from fortyfour to sixty; ant! that all of them have, or probably have, an XX-XY type of sex determination depending upon a particular pair of sex chromosomes in which the Y-chromosome (carried by the male)
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He hypothesized instead that there tract been a deletion of the part of that chromosome that normally carries the allele in question a hypothesis he subsequently verified by observing that these mice carried two heteromorphic pairs of chromosomes, the sex chromosome pair, plus another pair in which one homologue was very much smaller than its partner. Painter's study of the Japanese waltzing mouse appears to have been the first cytological identification of a deletion producing a specific genetic effect (1927,1~.
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Though transIocations investigated -My and [~-~) clid not at that time reveal the fact that all transIocations are actually reciprocal exchanges, they did show that the size of the cytological piece taken from one chromosome and attached to another did not correspond precisely in size to the portion of the genetic map that was transIocated.
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Heitz and Hans Bauer in SwitzerIancI, Painter identifier! the strangelooking tangled balls of thick strands to be seen in the nuclei of the salivary glands of all Diptera (first describer!
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in 1934, Painter continued his analysis of giant salivary gland chromosomes in stocks carrying deletions, inversions, or transIocations. When one chromosome of a homologous pair carried a cleletion, the longer mate formed a loop or buckle at the region, so that the exact points of breakage of the deletion could be cletermined at the level of incliviclual crossbands.
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Painter was greatly interested in the nature and function of the heterochromatin. From the comparison of salivary chromosomes with those of regular somatic cells or cells of the germ line, he conclucled that about three-eighths of the X-chromosome of Drosophila is missing in the salivary gland chromosomes, and that the Y-chromosome of the male is missing almost entirely, although in the usual somatic cells the Y-chromosome—unlike the Y of a mammal is very large, almost as large as the X-chromosome.
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chromosome map of Chromosome Ill, Painter concentrated on this new clirection until his research was interrupted in 1944. With his student Allen Driven, he examined the course of clevelopment of the salivary gland nucleus in the fly Simulium virgatum in order to see just how the giant paired salivary gland chromosomes arose and what their structure might be in comparison with simpler, single-strancled chromatids of more ordinary cells.
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Painter even undertook to assay the relation of cell growth in the pollen grains of a flowering plant, Rhoeo discolor, to the amounts of nucleic acid they possessed an investigation he initiates] prior to Avery, MacLeod, and McCarty's clemonstration that, in pneumococcus transformations of genetic type, it is the nucleic acid, not protein, that acts as the genetic material.
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Without a cloubt Painter served his university effectively cluring a most trying period. He played the role of conservative in the best sense.
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His colleagues testify that he spent more time in the library reacting current periodicals and books than did any graduate student. He also asked to be reassigned to the teaching of cell biology to untlergracluates anti cytology to graduate students, and thus addled to his burden all the reviewing and relearning required for teaching.
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Painter and Biesele searched for the origin of this cellular structure of endoplasmic tubules that apparently derive from outpockets of the nuclear membrane of the cell as the gland cell undergoes endomitosis. As this process enters a stage comparable to the prophase of ordinary mitosis, the numerous nuclei in the gland cell fragment and a myriad of ribosome-like bodies pass out through nuclear pores to become the polyribosomes attached to the walls of the endoplasmic tubules.
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He frequently attencled the meetings of scientific societies and, in adclition to serving on other committees of the American Philosophical Society, was a member of its Council from 1965 to 1967. He server!
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THE AUTHOR OF THIS MEMOIR iS deeply indebted to the University of Texas Faculty Committee that prepared the Memorial Minute on T
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Zool., 19:355-85. 1916 Some phases of cell mechanics.
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Zool., 35: 13-38. The sex chromosomes of the monkey.
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A cytological map of the X-chromosome of Drosophila melanogaster. Science, 73:647-48.
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69:74. The morphology of the third chromosome in the salivary gland of Drosophila melanogaster and a new cytological map of this element.
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1941 The effects of an alkaline solution (pH 13) on salivary gland chromosomes.
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Arts Sci., 36:443-48. Nuclear phenomena associated with secretion in certain gland cells with special reference to the origin of the cytoplasmic nucleic acid.
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1969 The origin of the nucleic acid bases found in the royal jelly of the honey bee.
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