Antigen-presenting cell-T cell interaction in the chicken is MHC class II antigen restricted

The involvement of the MHC in the recognition of Ag by avian T lymphocytes was analyzed. PBL from chickens primed with keyhole limpet hemocyanin in vivo were induced to synthesize DNA in an in vitro response to specific Ag. Responding cells were T cells as judged by immunofluorescence staining. In vivo Ag-primed PBL were stimulated in vitro with specific Ag and further propagated in the presence of IL-2. Subsequent Ag-specific T cell proliferation required the presence of Ag-pulsed peripheral blood adherent cells (APC). T cell responses were restricted by the MHC of the APC; Ag presented by allogeneic APC did not support T cell proliferation. By using MHC-recombinant chicken lines, the gene products controlled by MHC class II loci were shown to restrict the T cell-APC interaction. This conclusion was substantiated by the inhibition of the Ag-specific T cell response by a mAb against chicken MHC class II gene products but not by a mAb against chicken MHC class I gene products.     

Hydrolysis of phospholipid monolayers by human spermatozoa. Inhibition by male contraceptive gossypol

Monomolecular films of phospholipid were used to study the interaction of intact human spermatozoa with model membranes. Exclusively with negatively charged phosphatidylglycerol monolayers rapid penetration of spermatozoa into the monolayer with subsequent hydrolysis of the lipid was triggered by the addition of 5 mM calcium into the medium. The results suggest the localization of a calcium-dependent phospholipase A2 at the outer acrosomal or plasma membrane of human spermatozoa with its active site exposed to the external environment. Preincubation of the cells with 100 microM gossypol completely abolished the ability of human spermatozoa to hydrolyze or penetrate monolayers of phosphatidylglycerol. The inhibition of the phospholipase activity by gossypol may contribute to the unknown contraceptive mechanisms of this non-steroidal male antifertility agent.     

Increased endogenous retroviral gene expression is a consequence of lymphocyte activation

Plasma cells of line 151(5) chickens have been shown to express elevated levels of endogenous retroviral envelope glycoprotein (VEG), measured relative to levels expressed by both immature B cells and resting peripheral B lymphocytes. In this study we analyzed the relationship between peripheral blood lymphocyte (PBL) maturation and the level of VEG expression. A culture system was developed that would support maturation of pokeweed mitogen-activated peripheral B lymphocytes. As analyzed by cytofluorometry, both Ig+ and Ig- lymphoblasts present in the pokeweed mitogen-stimulated cultures expressed detectable levels of VEG in contrast to bursacytes and PBL. Similarly, Ig- blasts, which were present in concanavalin A-stimulated cultures of PBL and presumed to represent activated T cells, were also positive for the expression of VEG. Immature T cells, i.e., thymocytes, although negative by immunofluorescence analysis, expressed VEG at levels that were detectable by radioimmunochemical techniques. These results indicate that T cells as well as B cells constitutively express VEG, and that mitogenic activation of the resting lymphocyte induces an increase in VEG expression.     

Muscle strength and mineral densities in the mandible

Bone mineral density (BMD) in the femoral neck and lumbar spine was measured for 355 postmenopausal 48- to 56-year-old women and the BMD in five different regions in the mandible for 77. All 355 women were also classified according to the size of the masseter muscle. Both skeletal measures and the BMD of the buccal cortex distally from the foramen mentale were compared with the size of the masseter muscle. This study indicates that functional stress, caused by the masseter muscle, is involved in maintaining bone mineral density in edentulous regions of the mandible. Those individuals who are physically active or are bruxists may lose less mineral, after extractions of teeth, from those regions of the jaw bones where the muscles are attached.     

Ribosomal RNA genes in Scots pine (Pinus sylvestris L.): Chromosomal organization and structure

The nuclear 18S, 5.8S and 25S rRNA genes exist as thousands of rDNA repeats in the Scots pine genome. The number and location of rDNA loci (nucleolus organizers, NORs) were studied by cytological methods, and a restriction map from the coding region of the Scots pine rDNA repeat was constructed using digoxigenin-labeled flax rDNA as a probe. Based on the maximum number of nucleoli and chromosomal secondary constrictions, Scots pine has at least eight NORs in its haploid genome. The size of the Scots pine rDNA repeat unit is approximately 27 kb, two- or threefold larger than the typical angiosperm rDNA unit, but similar in size to other characterized conifer rDNA repeats. The intergenic spacer region (IGS) of the rDNA repeat unit in Scots pine is longer than 20 kb, and the transcribed spacer regions surrounding the 5.8S gene (ITS1 and ITS2) span a region of 2.9 kb. Restriction analysis revealed that although the coding regions of rDNA repeats are homogeneous, heterogeneity exists in the intergenic spacer region between individuals, as well as among the rDNA repeats within individuals.     

Effects of acute CS2 intoxication on liver protein and drug metabolism

Rats pretreated with phenobarbitone and their controls were exposed to 0.15% atmospheric CS₂ for 2 h. Liver protein metabolism and microsomal drug metabolizing enzyme activities were analyzed 1, 4 and 46 h later. In the pretreated rats the [¹⁴C]leucine uptake was at first inhibited, then liver RNA tended to increase. This increase was followed by a decline in the [¹⁴C]leucine uptake, while RNA content diminished to the control level. In the control rats (not pretreated with phenobarbital) the effects of CS₂ on liver protein metabolism were less; only at 4 h after the exposure was liver RNA increased and [¹⁴C]leucine uptake slightly stimulated. In the pretreated rats CS₂ had decreased microsomal P-450 by about 50% at 1 and 4 h, and the activity of 7-O-dealkylase of ethoxycoumarin had decreased even more. The measurable UDPglucuronosyltransferase of the liver microsomes of the pretreated rats had increased by 26% at 1 h and by 80% at 4 h after the CS₂ exposure. The in vivo activation of microsomal UDPglucuronosyltransferase may result from a stimulated lipid peroxidation of reticuloendothelial membranes by CS₂ metabolites in vivo, as suggested by the diene conjugation spectra. In control rats CS₂ depressed only the ethoxycoumarin deethylase activity. All the microsomal changes caused by CS₂ exposure were restored within 46 h.It is suggested that the different action of CS₂ on the liver protein metabolism of rats pretreated with phenobarbitone and controls results from the different stage of protein turnover in the two groups, i.e. in the barbituratetreated animals there is a phase of increased protein synthesis and accordingly the protein turnover is more sensitive to the action of CS₂.     

Complex Genetic Effects on Early Vegetative Development Shape Resource Allocation Differences Between Arabidopsis lyrata Populations

Costs of reproduction due to resource allocation trade-offs have long been recognized as key forces in life history evolution, but little is known about their functional or genetic basis. Arabidopsis lyrata, a perennial relative of the annual model plant A. thaliana with a wide climatic distribution, has populations that are strongly diverged in resource allocation. In this study, we evaluated the genetic and functional basis for variation in resource allocation in a reciprocal transplant experiment, using four A. lyrata populations and F₂ progeny from a cross between North Carolina (NC) and Norway parents, which had the most divergent resource allocation patterns. Local alleles at quantitative trait loci (QTL) at a North Carolina field site increased reproductive output while reducing vegetative growth. These QTL had little overlap with flowering date QTL. Structural equation models incorporating QTL genotypes and traits indicated that resource allocation differences result primarily from QTL effects on early vegetative growth patterns, with cascading effects on later vegetative and reproductive development. At a Norway field site, North Carolina alleles at some of the same QTL regions reduced survival and reproductive output components, but these effects were not associated with resource allocation trade-offs in the Norway environment. Our results indicate that resource allocation in perennial plants may involve important adaptive mechanisms largely independent of flowering time. Moreover, the contributions of resource allocation QTL to local adaptation appear to result from their effects on developmental timing and its interaction with environmental constraints, and not from simple models of reproductive costs.     

Activation of Hypoxia Response in Endothelial Cells Contributes to Ischemic Cardioprotection

Small-molecule inhibition of hypoxia-inducible factor prolyl 4-hydroxylases (HIF-P4Hs) is being explored for the treatment of anemia. Previous studies have suggested that HIF-P4H-2 inhibition may also protect the heart from an ischemic insult. Hif-p4h-2^gt/gt mice, which have 76 to 93% knockdown of Hif-p4h-2 mRNA in endothelial cells, fibroblasts, and cardiomyocytes and normoxic stabilization of Hif-α, were subjected to ligation of the left anterior descending coronary artery (LAD). Hif-p4h-2 deficiency resulted in increased survival, better-preserved left ventricle (LV) systolic function, and a smaller infarct size. Surprisingly, a significantly larger area of the LV remained perfused during LAD ligation in Hif-p4h-2^gt/gt hearts than in wild-type hearts. However, no difference was observed in collateral vessels, while the size of capillaries, but not their number, was significantly greater in Hif-p4h-2^gt/gt hearts than in wild-type hearts. Hif-p4h-2^gt/gt mice showed increased cardiac expression of endothelial Hif target genes for Tie-2, apelin, APJ, and endothelial nitric oxide (NO) synthase (eNOS) and increased serum NO concentrations. Remarkably, blockage of Tie-2 signaling was sufficient to normalize cardiac apelin and APJ expression and resulted in reversal of the enlarged-capillary phenotype and ischemic cardioprotection in Hif-p4h-2^gt/gt hearts. Activation of the hypoxia response by HIF-P4H-2 inhibition in endothelial cells appears to be a major determinant of ischemic cardioprotection and justifies the exploration of systemic small-molecule HIF-P4H-2 inhibitors for ischemic heart disease.