Worcester Foundation for Biomedical Research

About: Worcester Foundation for Biomedical Research is a based out in . It is known for research contribution in the topics: Estrone & Estrogen. The organization has 2195 authors who have published 2646 publications receiving 115809 citations. The organization is also known as: Worcester Foundation for Experimental Biology.

Molecular cloning of the microtubule-associated mechanochemical enzyme dynamin reveals homology with a new family of GTP-binding proteins

Abstract: A complementary DNA encoding the D100 poly-peptide of rat brain dynamin—a force-producing, microtubule-activated nucleotide triphosphatase—has been cloned and sequenced. The predicted amino acid sequence includes a guanine nucleotide-binding domain that is homologous with those of a family of antiviral factors, inducible by interferon and known as MX proteins, and with the product of the essential yeast vacuolar protein sorting gene VPS1. These relationships imply the existence of a new family of GTPases with physiological roles that may include microtubule-based motility and protein sorting.

Membrane vesiculation as a feature of the mammalian acrosome reaction.

Abstract: Short papers submitted expressly for this section, reporting original and significant findings of immediate interest and judged to be acceptable without major revision, will be published within approximately three months. See inside back cover for details. The term membrane vesiculation is used in this report to denote the occurrence of multiple unions between two cellular membranes lying in close apposition, with the formation first of a double-walled fenestrated layer and ultimately of an array of separate membrane-bounded vesicles. The stages are illustrated in Fig. 1. The process depicted by these diagrams is essentially the same as that suggested by Tormey (9) to explain his observations on cells of the ciliary epi-thelium in which the formation of a fenestrated layer from two contiguous membranes was inferred to take place. In the ciliary epithelium, the membranes involved were the cell membranes lining invaginations and interdigitating processes of neighboring cells. Tormey cites other data and work of several other authors, which support the thesis that membrane vesiculation is often to be ascribed to fixation of tissue with osmium te-troxide, glutaraldehyde-fixed tissue usually showing instead intact parallel membranes. Cell membranes in close apposition in other situations have also been described as undergoing vesiculation. Thus, vesicles considered to have been derived from fused sperm and egg membranes were reported by the Colwins (5) in an electron microscope study of early fertilization in the anne-lid Hydroides hexagonus. Piko and Tyler (7) believed that the plasma and acrosome membranes in the rat spermatozoon are removed largely by vesiculation, as the spermatozoon passes into the egg. In the bull sperm head illustrated by Saacke and Almquist (8, Fig. 16), the row of vesicles arranged about the nucleus appears to have arisen by multiple fusions between plasma and acrosome membranes, and a closely similar change has been seen in a monkey spermatozoon (L. E. Franklin, unpublished data). In these observations on animal gametes, the assumption has been that the changes seen were attributable to a natural process ; yet all these authors used osmium tetroxide as fixative, and consequently could have been misled by the production of artifacts. However, data have now been obtained with glutaraldehyde-fixed tissue which show that extensive vesiculation takes place between plasma and acrosome membranes in the course of the acrosome reaction evinced by hamster and rabbit spermatozoa as they pass through the egg investments. Information on the mammalian acrosome reaction has been meager at …

Fluctuations in Plasma Testosterone Levels in Adult Male Rats and Mice

Abstract: Testosterone (T) levels in the plasma of male laboratory rats and mice were measured by radioimmunoassay. There was a striking individual variation with values ranging from less than 1 ng/ml to over 30 ng/ml in mice of the same age and strain housed under identical conditions. Using chronic indwelling catheters inserted into a jugular vein, blood was collected from adult conscious male rats every 24 hr for 4 or 8 days and every 30 min for 2l/2 or 8 hr. Considerable differences in plasma T levels were observed between different animals, and 2– to 5–fold fluctuations of T concentrations in the plasma were detected between samples collected from the same animal at different times. These large and irregular changes in plasma levels of T are unlike the fairly stable levels observed in the human but bear certain resemblance to the pulsatile release of T described in bulls and rams and perhaps also to the social dominance related differences in plasma T levels in Rhesus monkeys. (Endocrinology 92: 1223, 1973)

Hormonal regulation of uterine secretion of prostaglandin F2 alpha during luteolysis in ruminants.

Abstract: In recent years, considerable progress has been made in our understanding of the endocrine mechanisms that control the pattern and timing of uterine secretion of prostaglandin F2 alpha (PGF2 alpha) during luteolysis in ruminants. Oxytocin may be important in establishing a pulsatile pattern of secretion. Neurohypophyseal oxytocin appears to be released in a pulsatile fashion and may initiate each episode of PGF2 alpha secretion from the uterus. Uterine PGF2 alpha stimulates release of oxytocin from the corpus luteum. Luteal oxytocin further stimulates secretion of PGF2 alpha from the uterus and may induce a transient refractoriness of the uterus to subsequent stimulation with oxytocin. Uterine refractoriness subsides after approximately 6 h. A similar desensitization phenomenon occurs in response to PGF2 alpha at the level of the corpus luteum. Together, uterine and luteal refractoriness may account for the interval between pulses of PGF2 alpha observed during luteolysis. Uterine secretory responsiveness to oxytocin increases at luteolysis, when endogenous, pulsatile secretion of PGF2 alpha normally begins. Thus, the acquisition by the uterus of responsiveness to oxytocin may determine when endogenous secretion of PGF2 alpha occurs during the estrous cycle. Uterine secretory responsiveness to oxytocin develops slowly, in the presence of progesterone. Progesterone exerts two types of effects that contribute to the regulation of PGF2 alpha secretion. First, prolonged exposure to progesterone appears to promote uterine accumulation of arachidonic acid, prostaglandin endoperoxide synthase, and other substances needed for synthesis of PGF2 alpha. Second, progesterone exerts a suppressive effect on secretion, which wanes after prolonged exposure. Together, these effects of progesterone ensure that PGF2 alpha is secreted only at the appropriate time to induce luteolysis.(ABSTRACT TRUNCATED AT 250 WORDS)