Immunocytochemical study of the epithelial lining of naturally occurring cysts in the rat intermediate lobe.

An immunocytochemical study of the epithelial lining of naturally occurring cysts in the rat intermediate lobe (IL) has been carried out. Paraffin-embedded sections, in which cysts were identifiable, were treated either with anti-serotonin or anti-S-100 protein sera. S-100-positive cells were intermingled with glandular cells surrounding the cyst lumen. These S-100-positive cells sent slender cytoplasmic processes as if to cover the apical surface of neighbouring cells. Rarely were 5-HT-immunopositive cells seen in the cyst epithelial lining. Most cells of the marginal layer of the IL were found reactive either to an S-100 or a-5-HT serum. The presence of an epithelial lining positive to S-100 protein sera is in keeping with the notion that cysts in the IL might form as evaginations of the epithelial lining of the pituitary cleft. The lack of correspondence between 5-HT-positive cells in the marginal layer and the cyst lining is controversial. A peculiar spatial relationship of 5-HT cells with the vascular network of the IL is suggested.     

Fertilized and unfertilized ova are transported at different rates by the hamster oviduct

To determine if the egg provides any clues for the regulation of ovum transport in the hamster, oocyte and embryo transport were compared. On the evening preceding ovulation, the animals were randomly assigned to one of five groups. They were caged overnight with a male of proven fertility (Group 1) or they were isolated (Group 2). Other females were artificially inseminated in both uterine horns at 2200 h either with fertile epididymal spermatozoa (Group 3), spermatozoa rendered infertile by freezing and thawing (Group 4), or with fertile spermatozoa in one uterine horn and infertile spermatozoa in the contralateral horn (Group 5). The number, condition, and distribution of ova in the genital tract were assessed at various intervals during the next 4 days. The rate of fertilization and normal development in females or sides inseminated with fertile or infertile spermatozoa was over 90% and 0% respectively. Embryos in Groups 1 and 3 reached the uterus 1 day earlier than unfertilized oocytes in Groups 2 and 4. In group 5, the transport of embryos resulting from insemination with fertile spermatozoa followed a pattern similar to those in Groups 1 and 3; the oocytes in the contralateral tract resembled those of Groups 2 and 4. The different transport rates of embryos and oocytes were not associated with the reproductive state of the female but with the condition of the ova. Moreover, the different transport rates were observed in animals transporting the two types of eggs simultaneously on different sides indicating that there is a local recognition of some unidentified factor unequally present in fertilized and unfertilized eggs.     

70-Kilodalton Heat Shock Protein Induction in Cerebellar Astrocytes and Cerebellar Granule Cells In Vitro: Comparison with Immunocytochemical Localization After Hyperthermia In Vivo

Induction of the 70-kDa heat shock protein, hsp70, was evaluated in cultured cerebellar astrocytes and granule cell neurons subjected to a hyperthermic stress, using a monoclonal antibody and an oligonucleotide probe that selectively recognize stress-inducible species of hsp70-related proteins and RNAs, respectively. Immunoblots of cultures enriched in either granule cells or astrocytes, and immunocytochemical localization studies in cocultures of these cell types, demonstrated that hsp70 induction was restricted to the astrocyte population. Amino acid incorporation experiments showed little difference in the loss and recovery of overall protein synthesis activity in these two cell types following transient hyperthermic stress. RNA blot hybridizations confirmed the preferential glial induction of hsp70. In vivo immunocytochemical studies in brains of adult rats following hyperthermia were consistent with earlier observations that suggested a primarily glial and vascular localization of the heat shock response in most brain regions, although the intense immunoreactivity in the cerebellar granule cell layer suggests that there is induction of hsp70 in these neurons under in vivo conditions. These results suggest the potential value of such defined cell cultures in identifying mechanisms responsible for differences in the heat shock response of various cell types in vitro, and in revealing factors that may account for the apparent absence of the stress response in cultured cerebellar granule cell neurons.     

An A alpha Ser-434 to N-glycosylated Asn substitution in a dysfibrinogen, fibrinogen Caracas II, characterized by impaired fibrin gel formation.

We have identified a unique N-glycosylated Asn substitution for a Ser at position 434 of the A alpha chain of an abnormal fibrinogen designated fibrinogen Caracas II. This dysfibrinogen was characterized by impaired fibrin monomer aggregation. Since there were 4 Thr residues immediately following the mutation, a new Asn-X-Thr/Ser-type consensus sequence, Asn-Thr-Thr arose for N-glycosylation of the Asn. The extra oligosaccharide was found to consist mainly of a disialylated biantennary structure comprising 81.9%, while a neutral and a monosialylated biantennary oligosaccharide represented only 3.6% and 14.5%, respectively. The mutation resides in the carboxyl-terminal region of the A alpha chain, which could fold back to form an extra small globular region located near the central region of the molecule (Erickson, H.P., and Fowler, W.E. (1983) Ann. N. Y. Acad. Sci. 408, 146-163; Weisel, H.P., Stauffacher, C.V., Bullitt, E., and Cohen, C. (1985) Science 230, 3124-3133). Therefore, the participation of this region, referred to as an additional central domain or an alpha domain, in fibrin gel formation is strongly implicated.     

Assessment of counting efficiencies for labeled protein and other macromolecules in filter disk assays

A several-fold greater counting efficiency is observed for protein labeled with [³H]leucine than for free [³H]leucine using a conventional filter disk assay. A similar, though less marked, effect is noted for ¹⁴C-labeled molecules. These results are comparable to those reported by others for counting efficiencies of labeled DNA and deoxynucleotides and illustrate the generality of this effect with regard to macromolecules and their low-molecular weight precursors. This phenomenon, presumably due to differences in the distribution of large and small molecules within filters, gives rise to errors in the quantitation of macromolecule synthesis if a counting efficiency identical to that of the precursor is assumed to apply. A convenient method for determining counting efficiencies of various molecules bound to filters is presented which eliminates this problem.     

Diabetes-induced rat hyposensitivity to compound 48/80

Rat mortality and contractile responses of isolated tracheas to compound 48/80 from rats made diabetic 4 days before by a single intravenous injection of alloxan and from diabetic rats that had been treated with insulin 6 h before were compared with control animals. Diabetic animals and tracheal segments from diabetic rats were significantly less responsive to compound 48/80 than control and insulin-treated diabetic animals. On the other hand, diabetic animals have a lower quantity of peritoneal mast cells than control rats, and insulin restored the normal quantity of cells in diabetic animals. These data indicate that diabetes elicits an hyposensitivity to compound 48/80, possibly related to a diabetes-induced decrease in the mast cell count.     

Human Cdc14A becomes a cell cycle gene in controlling Cdk1 activity at the G2/M transition

Cdc14 belongs to a dual-specificity phosphatase family highly conserved through evolution that preferentially reverses CDK (Cyclin dependent kinases) –dependent phosphorylation events. In the yeast Saccharomyces cerevisiae, Cdc14 is an essential regulator of late mitotic events and exit from mitosis by counteracting CDK activity at the end of mitosis. However, many studies have shown that Cdc14 is dispensable for exiting mitosis in all other model systems analyzed. In fission yeast, the Cdc14 homologue Flp1/Clp1 regulates the stability of the mitotic inducer Cdc25 at the end of mitosis to ensure Cdk1 inactivation before cytokinesis. We have recently reported that human Cdc14A, the Cdc14 isoform located at the centrosomes during interphase, down-regulates Cdc25 activity at the G2/M transition to prevent premature activation of Cdk1-Cyclin B1 complexes and untimely entry into mitosis. Here we speculate about new molecular mechanisms for Cdc14A and discuss the current evidence suggesting that Cdc14 phosphatase plays a role in cell cycle control in higher eukaryotes.     

Assessment of the Resistance to Uranium (VI) Exposure by Arthrobacter sp. Isolated from Hanford Site Soil

Production of nuclear fuel has resulted in hazardous waste streams that have contaminated the soil and groundwater. Arthrobacter strains, G975, G968, and G954 were used in the prescreening tests to evaluate their tolerance to UO₂ ²⁺ and investigate bacteria-U(VI) interactions under oxidizing pH-neutral conditions. Experiments have shown G975 is the fastest growing and the most uranium tolerant strain that removed about 90% of uranium from growth media. Atomic Force Microscopy images exhibited an irregular surface structure, which perhaps provided a larger surface area for uranium precipitation. The data indicate that aerobic heterotrophic bacteria may offer a solution to sequestering uranium in oxic conditions, which prevail in the vadose zone.