Corticosterone binding by rat brain cytosol

Significant quantities of corticosterone were associated with macromolecules of the brain cytosol following intrathecal administration of [³H]corticosterone to adrenalectomized rats. Fifteen times more steroid was found associated with proteins from adrenalectomized rats than from control animals or adrenalectomized animals pretreated with corticosterone. Pretreatment of adrenalectomized rats with 11-dehydrocorticosterone, Cortisol and cortisone decreased the amount of [³H]corticosterone found associated with protein, whereas progesterone, oestradiol and testosterone did not interfere with the association of [³H]corticosterone with macromolecules of the cytosol. Further evidence for protein-steroid interaction was obtained by incubating [³H]corticosterone (B), [³H]cortisol (F), or 11-[³H]deoxycortisol (S) with brain cytosols. The degree of binding was in the order B > F > S.     

Identified taste bud cell proliferation in the perihatching chick [published erratum appears in Chem Senses 1998 Aug;23(4):459]

Developing taste buds in the anterior mandibular floor of perihatching chicks were studied by high voltage electron microscopic autoradiography in order to identify proliferating gemmal cell types. Montaged profiles of 29 taste buds in five cases euthanized between embryonic day 21 and posthatching day 2 were analyzed after a single [3H]thymidine injection administered on embryonic day 16, 17 or 18. Results showed that dark cells comprised 55% of identified (n = 900 cells) and 62% of labeled (n = 568 cells) gemmal cells as compared with light, intermediate, basal or perigemmal bud cells. Dark cells had both a greater (P < 0.05) number of labeled cells and a greater amount of label (grains/nucleus) than the other four bud cell types, irrespective of injection day. The nuclear area (micron 2) of dark cells was not significantly larger (P > 0.05) than that of the other gemmal cell types and therefore cannot account for the greater amount for label in the dark cells. Interestingly, only dark cells showed a positive correlation (P < 0.003) between amount of label and nuclear area. Results suggest that, during the perihatching period of robust cell proliferation, dividing dark cells may give rise primarily, but not exclusively, to dark cell progeny.      

Fibroblast dedifferentiation as a determinant of successful regeneration

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Allotetraploid hybrids between citrus and seven related genera produced by somatic hybridization

We have developed an efficient protoplast-fusion method to produce somatic hybrid allopolyploid plants that combine Citrus with seven related genera, including four that are sexually incompatible. In this paper we report the creation of 18 new allotetraploid hybrids of Citrus, including ten among sexually incompatible related genera, that may have direct cultivar potential as improved citrus rootstocks. All hybrids were confirmed by cytological and RAPD analyses. If fertile, the attributes of these hybrids may be amenable to further genetic manipulation by breeding at the tetraploid level. Wide somatic hybridization of Citrus via protoplast fusion bypasses biological barriers to the natural allopolyploidization of Citrus, and creates new evolutionary opportunities that would be difficult or impossible to achieve by natural or conventional hybridization.Florida Agricultural Experiment Station Journal Series No. R-04520