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.

Reduced levels of acetylcholine receptor expression in chick ciliary ganglion neurons developing in the absence of innervation

Abstract: Chick ciliary ganglion neurons receive innervation from a single source, the accessory oculomotor nucleus (AON), and nicotinic ACh receptors (AChRs) mediate chemical synaptic transmission through the ganglion. Previous experiments examining the developmental expression of AChRs in embryonic chick ciliary ganglion neurons in situ have shown that AChR levels increase substantially in the neurons at the time of innervation. Prior to synapse formation, few AChRs are detected in the neurons. In the present experiments, the role of presynaptic inputs in inducing an increase in AChRs was established by examining AChR levels in ciliary ganglion neurons that have been deprived of innervation by surgical ablation of the AON prior to synapse formation. AChR levels were dramatically reduced in neurons of input-deprived ganglia as compared to control innervated neurons at all developmental stages examined from embryonic day (ED) 5 to ED 12 as determined by indirect immunocytochemical labeling of frozen ganglion sections with the anti- AChR monoclonal antibody mAb 35, and light microscopy. In contrast, neuronal somata of input-deprived and control ganglia had equivalent levels of immunolabeling for three other components, a transmembrane glycoprotein of synaptic vesicles, SV2, and two microtubule-associated proteins, MAP 1B and MAP 2, from ED 5 up to ED 10. The results demonstrate that presynaptic inputs specifically increase the levels of AChR expression in developing neurons. In addition, changes in the levels of immunolabeling for AChRs, SV2, MAP 1B, and MAP 2 in neuronal somata after ED 10 demonstrate that other major developmental events also influence the levels of these components in neurons. Declines in the intensity of AChR, SV2, MAP 1B, and MAP 2 immunolabeling within a subset of neuronal somata in both operated and control ganglia at ED 10 and 12 coincide with the period of neuronal cell death. Increases in AChR labeling in the rest of the neuronal population of input-deprived ganglia at ED 12 suggest that, in addition to innervation, synapse formation with the peripheral target tissue influences AChR levels in developing neurons in situ.

Gonadal steroids regulate proenkephalin gene expression in a tissue-specific manner within the female reproductive system.

Abstract: Proenkephalin gene expression undergoes marked changes within the female reproductive system of rodents during the estrous cycle and in pregnancy. In order to define the factors responsible for this regulation, the effects of 17-β-estradiol (E2) and progesterone (P4) have been examined in the ovary and uterus. In the ovary of the rat and hamster, E2 and P4 were without effect on proenkephalin RNA levels when injected individually. However, P4 increased ovarian transcript abundance 2- to 3-fold after pretreatment of animals with E2. In the uterus of either species, E2 had little effect but P4 alone stimulated both proenkephalin RNA abundance and total content severalfold. Glucocorticoids and androgen reproduced this stimulatory effect on proenkephalin transcript levels. The interaction between E2 and P4 on proenkephalin gene expression in the uterus varied with species. In the rat, E2 inhibited stimulation by P4, while in the hamster uterus the two hormones had a synergistic effect, producing a 15-fold ele...

Silicate uptake and silica shell formation by synchronously dividing cells of the diatom navicula pelliculosa (bréb.) hilse(1,2,3).

Abstract: Cells of the freshwater diatom Navicula pelliculosa were induced to divide synchronously by the addition of excess silicate (20 mg Si/liter) to a culture which had been silicate-starved for 14 hr. After a 3- to 4-hr lag period, characterized by rapid silicate uptake (6.5 mg Si/liter/4 hr) and silica shell formation, the cell number then doubled in the succeeding 2-3 hr. This system promises to have significance in the study of silicon metabolism, transport phenomena, and silica deposition.