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.

Effects of Progesterone and Related Compounds on Fertilization, Transportation and Development of Rabbit Eggs

Abstract: Isolated mature rabbits were treated with progesterone or other related compounds for 3 days before insemination and an ovulating injection of HCG. They were examined on various days later to ascertain the fertilization, transportation and development of eggs. Subcutaneous injection of 1–4 mg progesterone rabbit reduced the fertilization rate from 66 to 22%; feeding with 1–4 mg medroxyprogesterone acetate from 88 to 51%; with 0.2 to 20 mg chlormadinone from 66 to 2%, while feeding with 2-mg norethynodrel, norethindrone acetate, or methyltestosterone had no effect. The rate of egg recovery in terms of C.L. was low (51–82%) and the presence of eggs in the uterus on day was high (27–82%) in the animals treated with progesterone and its derivatives. The disturbance of fertilization appears closely related to the rapid egg transport. Many fertilized or unfertilized eggs recovered from the uterus were degenerating and a few eggs were recovered from the vagina. Uterine or tubal inj semination increased the ferti...

Multiple sequence elements and a maternal mRNA product control cdk2 RNA polyadenylation and translation during early Xenopus development.

Abstract: Cytoplasmic poly(A) elongation is one mechanism that regulates translational recruitment of maternal mRNA in early development. In Xenopus laevis, poly(A) elongation is controlled by two cis elements in the 3' untranslated regions of responsive mRNAs: the hexanucleotide AAUAAA and a U-rich structure with the general sequence UUUUUAAU, which is referred to as the cytoplasmic polyadenylation element (CPE). B4 RNA, which contains these sequences, is polyadenylated during oocyte maturation and maintains a poly(A) tail in early embryos. However, cdk2 RNA, which also contains these sequences, is polyadenylated during maturation but deadenylated after fertilization. This suggests that cis-acting elements in cdk2 RNA signal the removal of the poly(A) tail at this time. By using poly(A) RNA-injected eggs, we showed that two elements which reside 5' of the CPE and 3' of the hexanucleotide act synergistically to promote embryonic deadenylation of this RNA. When an identical RNA lacking a poly(A) tail was injected, these sequences also prevented poly(A) addition. When fused to CAT RNA, the cdk2 3' untranslated region, which contains these elements, as well as the CPE and the hexanucleotide, promoted poly(A) addition and enhanced chloramphenicol acetyltransferase activity during maturation, as well as repression of these events after fertilization. Incubation of fertilized eggs with cycloheximide prevented the embryonic inhibition of cdk2 RNA polyadenylation but did not affect the robust polyadenylation of B4 RNA. This suggests that a maternal mRNA, whose translation occurs only after fertilization, is necessary for the cdk2 deadenylation or inhibition of RNA polyadenylation. This was further suggested when poly(A)+ RNA isolated from two-cell embryos was injected into oocytes that were then allowed to mature. Such oocytes became deficient for cdk2 RNA polyadenylation but remained proficient for B4 RNA polyadenylation. These data show that CPE function is developmentally regulated by multiple sequences and factors.