Biomedical subjects
J S Kaye
Publications and source records attributed to J S Kaye.
Ethics--a proper study for the nurse.
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Steroid hormone dependence of four DNase I-hypersensitive regions located within the 7000-bp 5'-flanking segment of the ovalbumin gene.
Four DNase I-hypersensitive regions (I-IV) occur in the 5'-flanking region of the ovalbumin gene in hen oviducts. One is centered close to the cap site (position +1) of transcription and the others at -0.8, -3.3 and -6.0 kb. The correlation of hypersensitivity with transcription was determined for each region in oviducts of chicks, where expression of the ovalbumin gene can be controlled by administration and withdrawal of steroid hormones. DNase I-hypersensitive regions were mapped by the indirect end-labeling technique and ovalbumin mRNA levels were determined by the dot blot assay. Diethylstilbestrol (DES) induces the appearance of hypersensitive regions I-IV whereas progesterone induces regions I, II and IV, but not region III. Upon withdrawal, regions II and III, and most of regions I and IV, disappear. A weak zone of hypersensitivity in region I near the cap site persists during withdrawal and a new zone of hypersensitivity appears between regions I and II. There is strong correlation between hypersensitivity at regions I-IV and gene transcription; ovalbumin mRNA levels are high in stimulated chicks, where hypersensitive regions are present, and drop to very low levels in withdrawn chicks, where the hypersensitivity is absent. We suggest that proteins, perhaps hormone receptors acting together with tissue-specific factors, induce DNAse I-hypersensitive regions I-IV of the ovalbumin gene.
Hormonally induced alterations of chromatin structure in the polyadenylation and transcription termination regions of the chicken ovalbumin gene.
We have studied the chromatin structure of a 16-kb region of the chicken genome containing the 3'-terminal 2 kb of the ovalbumin pre-mRNA coding sequence and the 14-kb segment located immediately downstream from the main mRNA polyadenylation site. Using the indirect end-labelling technique, four major and two minor DNase I-hypersensitive regions were found in the oviduct chromatin, whereas they were not present in liver, kidney or erythrocyte chromatin. The first hypersensitive region (region A) was present in chromatin of oviducts from laying hen and estrogen- or progesterone-stimulated immature chicks, in which the ovalbumin gene is expressed, but not in the chromatin of 'acute withdrawn' chicks where the gene is no longer transcribed. Region A spans 1.3 kb, from 7.2 to 8.5 kb downstream from the ovalbumin gene capsite (position +1), and encompasses the 3' moiety of the last exon including the major polyadenylation signal and polyadenylation site located at +7546 and +7564, respectively. Region A also contains a minor polyadenylation signal present at +7294 and the corresponding polyadenylation site at +7368. Two putative termination sequences at +8445 and +8483 are also found at the 3' extremity of region A in a 170-bp DNA segment within which 90% of the ovalbumin primary transcripts apparently terminate. Two minor hormone-independent DNase I-hypersensitive regions (a1 and a2) located at +8.6 and +8.8 kb are also specific to oviduct chromatin.(ABSTRACT TRUNCATED AT 250 WORDS)
A close association between sites of DNase I hypersensitivity and sites of enhanced cleavage by micrococcal nuclease in the 5'-flanking region of the actively transcribed ovalbumin gene.
The organization of chromatin was analysed in a segment of the chicken ovalbumin gene extending 6.5 kb upstream from the start site of transcription. Nuclei of chicken oviduct cells and of erythrocytes, and preparations of 'naked' DNA were digested with DNase I and with micrococcal nuclease. The locations of specific nuclease cleavage sites were determined by analyzing the fragments obtained with an indirect end-labeling technique. In oviduct nuclei there are four regions of DNase I hypersensitivity centered at approximately 0.15, 0.80, 3.2 and 6.0 kb upstream from the mRNA cap site. DNase I hypersensitive regions are absent from the 5'-flanking regions of erythrocyte nuclei. Micrococcal nuclease cleavage sites were found that are unique to oviduct nuclei and others that are enhanced in oviduct nuclei, relative to erythrocyte nuclei and to naked DNA. The locations of these micrococcal nuclease cleavage sites are closely associated with the DNase I hypersensitive regions. Nuclease hypersensitivity in the 5'-flanking region of oviduct nuclei reflects alterations in chromatin structure that are specifically correlated with gene expression. Our results suggest the presence at hypersensitive regions of specific proteins which alter the chromatin structure, making the DNA more accessible to nuclease attack.
Organization of chromatin during spermiogenesis: beaded fibers, partly beaded fibers, and loss of nucleosomal structure.
The aggregation of chromatin during spermiogenesis in the house cricket and many other animals is an orderly process involving the formation of a series of long, thick, well defined structures. The differentiation of chromatin preliminary to the development of such unusual structures is given attention here. Examination of nuclei after lysis and spreading indicated that fibers with closely spaced nucleosomes, like the fibers of somatic chromatin, make up the chromatin in all stages of early spermiogenesis and most of middle spermiogenesis. The thick structures of late spermatids cannot be formed by aggregation of fibers of this somatic type, however; just before thick structures form, chromatin fibers lose the nucleosomal structure. During the process, fibers with nucleosomes spaced at irregular intervals and with long stretches of smooth thin fiber are found, as if nucleosomes at one site on a fiber are broken down independently of those at adjacent sites. Since prior studies of cricket proteins have indicated that somatic histones persist during the stages when nucleosome structure disappears, the observations imply that the histones which are organized in nucleosomes during early stages must become incorporated into different kinds of nucleoprotein complexes during succeeding stages of spermiogenesis.
Acrosomal bands: specialized structures on the nuclear surface of holding the acrosomal granule.
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Chromatographic fractionation of histones on Bio-Gel P.
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Fractionation of cricket testis nuclei on gradients of colloidal silica for study of basic protein changes during spermiogenesis.
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Basic protein changes during the final stages of sperm maturation in the house cricket.
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Histones of spermatogenous cells in the house cricket.
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Staining of histones on polyacrylamide gels with amido black and fast green.
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An electrophoretic analysis of the histones of the house cricket.
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The fine structure and arrangement of microcylinders in the lumina of flagellar fibers in cricket spermatids.
Flagellar structure in spermatids of several species of cricket was studied with the electron microscope. The flagella of mid-spermatids contain the usual 9 + 2 set of fibers and a set of nine accessory fibers. At first all are hollow, then the lumina become filled with an electron-opaque matrix material in which narrow electron-lucent microcylinders are embedded. The accessory fibers and one central fiber become filled first, then the B subfibers and the other central fiber, and finally the A subfiber. In all but the B subfibers, microcylinders are arranged in a circular or oval group that lies against the wall of the lumen and encloses one or several additional microcylinders. In accessory fibers there are 9-11 microcylinders in the outer group and 4-5 in the inner group. In the central fibers and the A subfibers there are 7-9 microcylinders that enclose one or two more. In the B subfibers there is a crescentic group of 6-7 microcylinders that partially encloses 2-3 more. Microcylinders become packed as though they are independent units; the matrix appears to be an amorphous substance that fills the spaces around the microcylinders. The mean diameter of the microcylinders is 36 A, and they have a center-to-center distance of 56 A. In both respects they resemble wall subunits of flagellar fibers and microtubules and they may be similar structures but with a different localization. The diameter of accessory fibers is about 350 A, which is 25% greater than that of the other flagellar fibers and of cytoplasmic microtubules. Rotation tests suggest that the accessory fibers have 16 wall-subunits.
The fine structure and chemical composition of nuclei during spermiogenesis in the house cricket. I. Initial stages of differentiation and the loss of nonhistone protein.
The early stages of nuclear differentiation in spermatids of the house cricket are described with regard to the fine structural elements and chemical components which occur. Particular attention is given to the loss of nonhistone protein from the nucleus and its relation to chromatin structure. Granular elements about 25 to 80 mmicro in diameter, and fibers about 8 mmicro in diameter occur in the earliest spermatid nucleus. The fibers are found in diffuse and condensed chromatin while granules are found only in diffuse material. DNA and histone parallel the chromatin fibers in distribution, while nonhistone protein and RNA parallel the granules in distribution. The granules and most of the nonhistone protein are lost, simultaneously, after the early spermatid stage. The protein loss occurs without detectable change in the structure of chromatin fibers. Chromatin fibers first show a structural change in mid spermiogenesis, when they become thicker and very contorted. Unusually thin fibers (about 5 mmicro) also appear in mid spermatid nuclei; they are apparently composed of nonhistone protein and free of DNA and histone.