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.

Reception of photoperiodic information by fetal siberian hamsters: Role of the mother's pineal gland

Abstract: The rate of reproductive development in juvenile male Siberian hamsters is strongly influenced by daylength (photoperiod). Recent studies indicate that reception of photoperiodic cues begins during fetal life. The present experiments yielded a further demonstration that developing male Siberian hamsters receive information about the photoperiod to which their mother is exposed during pregnancy. The possibility that photoperiodic information is transmitted from mother to young after birth was investigated by cross-fostering young gestated on 12L and 16L to mothers from the other photoperiod. Litters were cross-fostered on the day of birth and then were transferred, along with their foster mothers, to 14L. We found no influence of the mother after birth, indicating that transmission of photoperiodic information from mother to young must occur during gestation. To determine if the pineal gland of the mother is required for this response, adult females were pinealectomized or sham-operated and paired with intact males in 12L, 14L, or 16L. After parturition parents and offspring were exposed to 14L. The influence of prenatal photoperiod on postnatal testicular development in 14L was blocked by pinealectomy of the mother. Postnatal testicular development was retarded in offspring that experienced a photoperiod transfer from either 15L to 14L or 8L to 12L at birth. In contrast, the inhibitory effect of a transfer from 16L to 14L at birth was abolished when juvenile males were exposed to a single long photoperiod (16.3 h light) at age 17-21 days and then were returned to 14L.

The nature of circulating estrogen; lipoprotein-bound estrogen in human plasma.

Abstract: IN THE COURSE of investigations on the activity of the naturally occurring blood estrogens, it was found that the viscera were essential for estrogenic stimulation (Szego and Roberts, 1945). No evidence for estrogenic activity could be obtained in the eviscerated rat under a wide variety of conditions. Apparently, the presence of exogenous estrogen in the circulating blood was not in itself an adequate stimulus. From these and other observations it seemed possible that the estrogen molecule might undergo, under normal conditions in vivo, certain changes which endow it with the physico-chemical properties necessary for its activity. Accordingly, studies on the nature of circulating estrogen in several species were undertaken (Szego and Roberts, 1946). It was shown that approximately two-thirds of the estrogenic activity of whole blood, cells, plasma, and serum occurred closely associated with the blood protein.

Influence of 3-methylanthranilic and anthranilic acids on the formation of tryptophan synthetase in Escherichia coli.

Abstract: It is now well recognized that the product of a series of biosynthetic reactions can play an important controlling role in its formation, either by inhibiting the activity or the formation of the enzymes concerned with its synthesis (Vogel, 1957; Pardee, 1959). Since the extent of such control is largely dependent on the intracellular concentration of the particular metabolite involved, the levels of enzyme function or formation can be controlled by manipulations which affect the intracellular concentrations of the repressing substance (Gorini and Maas, 1957). Thus, cultures grown in the presence of high concentrations of a particular repressor show a depressed content of the enzymes concerned with its synthesis. On the other hand, the maintenance of low levels of repressor, by controlled low level feeding to strains with a requirement for the repressing metabolite, results in an elevated enzyme level in such cultures. In some strains which have a partial block in the synthesis of a repressor the level of the corresponding enzymes is also high (Yanofsky, 1960). The latter observation suggests that specific inhibitors of reactions leading to repressor synthesis might be employed to control enzyme formation. This paper deals with an examination of this possibility with the tryptophan-synthesizing system of Escherichia coli, which is well suited for such a study. Tryptophan represses the formation of tryptophan synthetase in Aerobacter aerogenes (Monod and CohenBazire, 1953) as well as other enzymes involved in tryptophan synthesis in E. coli (Yanofsky, 1960). Contrariwise, strains which appear to be partially blocked in tryptophan synthesis, as evidenced by the stimulation of growth by