Rearrangement of immunoglobulin genes in chicken B cell development

Immunoglobulin gene rearrangement in the chicken has evolved not to generate antibody diversity per se but to generate an immunoglobulin variable region which can be diversified by subsequent somatic gene conversion events. While the molecular mechanism of V(D)J recombination in chickens cannot be distinguished from that seen in other species, the way in which this recombination is regulated during chicken B lymphocyte development does differ from the more widely known models of gene rearrangement in humans and rodents. In this review we focus on these differences, relating V(D)J recombination to the progression of chicken B cell development in the bursa of Fabricius.     

In vivo damage and recA-dependent repair of plasmid and chromosomal DNA in the radiation-resistant bacterium Deinococcus radiodurans

Deinococcus radiodurans R1 and other members of this genus share extraordinary resistance to the lethal and mutagenic effects of ionizing radiation. We have recently identified a RecA homolog in strain R1 and have shown that mutation of the corresponding gene causes marked radiosensitivity. We show here that following high-level exposure to gamma irradiation (1.75 megarads, the dose required to yield 37% of CFU for plateau-phase wild-type R1), the wild-type strain repairs > 150 double-strand breaks per chromosome, whereas a recA-defective mutant (rec30) repairs very few or none. A heterologous Escherichia coli-D. radiodurans shuttle plasmid (pMD68) was constructed and found to be retained in surviving D. radiodurans R1 and rec30 following any radiation exposure up to the highest dose tested, 3 megarads. Plasmid repair was monitored in vivo following irradiation with 1.75 megarads in both R1/pMD68 and rec30/pMD68. Immediately after irradiation, plasmids from both strains contained numerous breaks and failed to transform E. coli. While irradiation with 1.75 megarads was lethal to rec30 cultures, a small amount of supercoiled plasmid was regenerated, but it lacked the ability to transform E. coli. In contrast, wild-type cultures showed a cell division arrest of about 10 h, followed by exponential growth. Supercoiled plasmid was regenerated at normal levels, and it readily transformed E. coli. These studies show that D. radiodurans retains a heterologous plasmid following irradiation and repairs it with the same high efficiency as its chromosomal DNA, while the repair defect in rec30 prevents repair of the plasmid. Taken together, the results of this study suggest that plasmid DNA damaged in vivo in D. radiodurans is repaired by recA-dependent mechanisms similar to those employed in the repair of chromosomal DNA.     

Cholinergic blockade and the mesenteric artery response to head-up tilt-induced central hypovolaemia

The methylation of phosphatidylethanolamine is an auxiliary pathway for phosphatidylcholine biosynthesis in liver. Two forms of the enzyme, phosphatidylethanolamine N-methyltransferase, which catalyses this reaction, are located on the endoplasmic reticulum and mitochondria-associated membranes. Both forms are encoded by a single murine gene, Pempt, located on chromosome 11. The expression of the gene begins at birth. An inverse relationship exists between the rate of liver growth and the expression of phosphatidylethanolamine N-methyltransferase. However, disruption of the Pempt gene does not alter liver growth in mice or cause any other obvious phenotype.     

Types of social support as predictors of psychiatric morbidity in a cohort of British Civil Servants (Whitehall II Study)

BACKGROUND: Few studies have examined prospectively both the direct and buffering effects of types of social support and social networks on mental health. This paper reports longitudinal associations between types of social support and psychiatric morbidity from the Whitehall II study. METHODS: Social support was measured by the Close Persons Questionnaire and psychiatric morbidity by the General Health Questionnaire at baseline (1985-1988) and at first follow-up (1989) in 7697 male and female London-based civil servants aged 35-55 years at baseline. The cohort was followed up and baseline measures were used to predict psychiatric disorder measured by the General Health Questionnaire at second follow-up (1991-1993). RESULTS: Longitudinal analyses showed that low confiding/emotional support in men and high negative aspects of close relationships in men and women were associated with greater risk of psychiatric morbidity even after adjustment for baseline General Health Questionnaire score. There was no evidence of a buffering effect among men or women who experienced life events or chronic stressors. Controlling for a personality measure of hostility did not affect the observed relations. CONCLUSIONS: The present findings illustrate that different types of support are risk factors for psychological distress and that they operate in different ways for men and women. Direct effects of emotional support are predictive of good mental health in men and negative aspects of close relations predict poor mental health in both men and women. Emotional support is predictive of good mental health in women whereas, confiding alone is not.     

Controlled-release products for the control of the estrus cycle in cattle, sheep, goats, deer, pigs, and horses

This paper describes the estrus cycles of a number of livestock breeds and reviews the controlled-release drug delivery systems that are currently available for the purpose of controlled breeding. The bovine estrus cycle is reviewed in detail, and the estrus cycles of other species are described in a manner that highlights similarities and differences between species. Pertinent formulation and pharmacokinetic information about current drug delivery systems is presented and discussed, and recent advances in this area are also described.     

Effect of dietary insulin on the response of suckling mice enterocytes to Escherichia coli heat-stable enterotoxin

OBJECTIVE: There are many different approaches to vaginal reconstruction. Methods include simple dilatation, skin grafts techniques, amnion grafts and the use of bowel segments for vaginal replacement. METHOD: We herein discuss the most common surgical techniques and present our series of 15 patients who underwent intestinal vaginoplasty with either sigmoid colon or cecum. RESULTS: The complication rate was low, with two patients requiring revision for prolapse. Ten patients are sexually active with only one describing any degree of dyspareunia. CONCLUSION: When dealing with vaginal aplasia, intestinal vaginoplasty seems to have clear advantages with an excellent surgical success rate and low incidence of complications.     

The human HNRPD locus maps to 4q21 and encodes a highly conserved protein

The hnRNP D protein interacts with nucleic acids both in vivo and in vitro. Like many other proteins that interact with RNA, it contains RBD (or "RRM") domains and arg-gly-gly (RGG) motifs. We have examined the organization and localization of the human and murine genes that encode the hnRNP D protein. Comparison of the predicted sequences of the hnRNP D proteins in human and mouse shows that they are 96.9% identical (98.9% similar). This very high level of conservation suggests a critical function for hnRNP D. Sequence analysis of the human HNRPD gene shows that the protein is encoded by eight exons and that two additional exons specify sequences in the 3' UTR. Use of two of the coding exons is determined by alternative splicing of the HNRPD mRNA. The human HNRPD gene maps to 4q21. The mouse Hnrpd gene maps to the F region of chromosome 3, which is syntenic with the human 4q21 region.