Pemoline and magnesium hydroxide: lack of effect on RNA and protein synthesis

Brain RNA polymerase isolated from rats treated with pemoline and magnesium hydroxide (Cylert) was not more active than enzyme from control animals. The drug did not increase enzymic activity in vitro. Pemoline did not significantly affect either RNA or protein synthesis in suspensions of Ehrlich ascites carcinoma cells.     

Requirement of Cks2 for the first metaphase/anaphase transition of mammalian meiosis

We generated mice lacking Cks2, one of two mammalian homologs of the yeast Cdk1-binding proteins, Suc1 and Cks1, and found them to be viable but sterile in both sexes. Sterility is due to failure of both male and female germ cells to progress past the first meiotic metaphase. The chromosomal events up through the end of prophase I are normal in both CKS2-/- males and females, suggesting that the phenotype is due directly to failure to enter anaphase and not a consequence of a checkpoint-mediated metaphase I arrest.     

Interanimal "memory" transfer: results from brain and liver homogenates

Sixty mice received either shock or no shock in a shuttle box, or nonspecific stress in another apparatus. Brain and liver homogenates from these animals were then injected into 120 naive recipients, who were all tested in the shuttle box. Subjects receiving brain or liver from shocked or stressed donors had significantly higher latencies than control counterparts. These results are interpreted in terms of stress, rather than a memory transfer hypothesis.     

Permselective Membranes: Spectroscopic and Conductivity Effects

The absorption spectrum of permselective ion-exchange membranes containing positively charged groups shows specific effects which depend on the nature of the negative gegenion used. Such colored permselective membranes with positive or negative functional groups show increased condutivity after illumination with light flashes. The increased conductivity returns slowly to the original value.     

Distinct kinetic changes in neurotransmitter release after SNARE protein cleavage

Neurotransmitter release is triggered by calcium ions and depends critically on the correct function of three types of SNARE [soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptor] proteins. With use of the large calyx of Held presynaptic terminal from rats, we found that cleavage of different SNARE proteins by clostridial neurotoxins caused distinct kinetic changes in neurotransmitter release. When elevating calcium ion concentration directly at the presynaptic terminal with the use of caged calcium, cleavage of SNAP-25 by botulinum toxin A (BoNT/A) produced a strong reduction in the calcium sensitivity for release, whereas cleavage of syntaxin using BoNT/C1 and synaptobrevin using tetanus toxin (TeNT) produced an all-or-nothing block without changing the kinetics of remaining vesicles. When stimulating release by calcium influx through channels, a difference between BoNT/C1 and TeNT emerged, which suggests that cleavage of synaptobrevin modifies the coupling between channels and release-competent vesicles.     

Transgenic RNAi reveals essential function for CTCF in H19 gene imprinting

The imprinted regulation of H19 and Insulin-like growth factor 2 expression involves binding of the vertebrate insulator protein, CCCTC binding factor (CTCF), to the maternally hypomethylated differentially methylated domain (DMD). How this hypomethylated state is maintained during oogenesis and the role of CTCF, if any, in this process are not understood. With the use of a transgenic RNA interference (RNAi)-based approach to generate oocytes with reduced amounts of CTCF protein, we found increased methylation of the H19 DMD and decreased developmental competence of CTCF-deficient oocytes. Our results suggest that CTCF protects the H19 DMD from de novo methylation during oocyte growth and is required for normal preimplantation development.