Studies on DNA markers (D4S10 and D4S43/S127) genetically linked to Huntington's disease in Japanese families

Summary This is the first full report on the genetic linkage between Japanese Huntington's disease and the DNA markers D4S10 and D4S43/S127. With use of the HindIII, BglI, and EcoRI polymorphisms detected at D4S10, and the combination of all these polymorphisms to give composite haplotypes, nine Japanese Huntington's disease families were found to be informative. Three recombinants for D4S10 were detected in these families, giving a maximum lod score of 1.662 at a of 0.10. Similarly, when we used the MspI and PvuII polymorphisms detected by D4S43/S127, five families gave informative results. No recombinant was detected in these families, giving a maximum lod score of 3.348 at a of 0.00. These results clearly support the view that the Japanese Huntington's disease gene may be identical with the Western gene, in spite of the lower prevalence rate in Japan.     

Probability of paternity exclusion and the number of loci needed to determine the fathers in a troop of macaques

We calculated the probability of paternity exclusion (P) in 6 troops of rhesus and Japanese macaques housed in open enclosures and 68 wild troops of Japanese, crab-eating, and toque macaques using 33 genetic loci which encoded the blood protein variations detected by electrophoretic techniques. In the open enclosures, especially of rhesus troops, we obtained a fairly high probability of paternity exclusion and succeeded in determining the fathers of offspring. However, we found significant differences between the observed and calculated probabilities in most of the troops. These differences were ascribed to a situation whereby the Hardy-Weinberg equilibrium had not been attained in the troops and/or the numbers of variable loci were too small. In the wild troops of Japanese, crab-eating, and toque macaques, the means ofP were 0.2274 (0.0192–0.5017), 0.4635 (0.1676–0.7151), and 0.7382 (0.6266–0.7954), respectively. We also estimated the number of loci needed to determine the fathers of offspring with a probability of 0.8 assuming that ten males were present in the troop. The estimated number was about 13.5 times, 5 times and 1.8 times the number of loci examined on average in the troops of Japanese, crab-eating and toque macaques, respectively. This means that determination of most of the fathers of offspring in wild troops of these macaques, even of toque macaques which have a rather high probability of paternity exclusion, is difficult so long as we employ only electrophoretic techniques.     

Conservatism of sites of tRNA loci among the linkage groups of severalDrosophila species

Summary The sites of seven tRNA genes (Arg-2, Lys-2, Ser-2b, Ser-7, Thr-3, Thr-4, Val-3b) were studied by in situ hybridization.¹²⁵I-labeled tRNA probes fromDrosophila melanogaster were hybridized to spreads of polytene chromosomes prepared from fourDrosophila species representing different evolutionary lineages (D. melanogaster, Drosophila hydei, Drosophila pseudoobscura, andDrosophila virilis). Most tRNA loci occurred on homologous chromosomal elements of all four species. In some cases the number of hybridization sites within an element varied and sites on nonhomologous elements were found. It was observed that both tRNA ₂ ^Arg and tRNA ₂ ^Lys hybridized to the same site on homologous elements in several species. These data suggest a limited amount of exchange among different linkage groups during the evolution ofDrosophila species.     

Reduction of the level of the glycine cleavage system in the rat liver resulting from administration of dipropylacetic acid: an experimental approach to hyperglycinemia.

Prolonged administration of dipropylacetic acid, a branched-chain fatty acid, reduced the glycine cleavage activity in the liver of rat to about one-third of the activity in the control rat. The reduction of the activity appeared to be due mainly to reduction of the level of P-protein, a pyridoxal phosphate enzyme, which is responsible for the first step of the glycine cleavage, although dipropylacetic acid was also found to inhibit the activity of P-protein in vitro in a noncompetitive but partially competitive manner with respect to glycine. The rat treated with dipropylacetic acid may provide an experimental approach for the biochemical study of hyperglycinemia which accompanies to metabolic disorders of branchedchain keto acids. In the dipropylacetic acid-treated rat, however, the glycine concentration in the serum was not appreciably elevated and this may be accounted for by the fact that the activities of both the glycine cleavage system and serine dehydratase are considerably higher in the rat liver as compared with those in other animals including human.     

The primary structure of human H-protein of the glycine cleavage system deduced by cDNA cloning

A full-length cDNA encoding the human H-protein of the glycine cleavage system has been isolated from a lambda gt11 human fetal liver cDNA library. The cDNA insert was 1091 base pairs with an open reading frame of 519 base pairs which encoded a 125-amino acid mature human H-protein with a 48-amino acid presequence. Human H-protein is 97%, 86%, and 46% identical to the bovine, chicken, and pea H-protein, respectively.     

Degradation of rod outer segment proteins by cathepsin D.

The degradation of proteins of the rod outer segment (ROS) fraction by partially purified cathepsin D [EC 3.4.23.5] from the retinal pigment epithelium was studied. The ROS fraction, prepared from bovine eyes by sucrose density gradient centrifugation, had little cathepsin D activity. Partially purified cathepsin D, obtained from crude extract of bovine retinal pigment epithelium using bovine serum albumin as a substrate, hydrolyzed the porteine of the ROS fraction. The rate of degradation of ROS proteins was proportional to both the enzyme concentration and the incubation time. With ROS proteins as substrate, the optimal pH of cathepsin D was about 3.5. The degradation of ROS proteins was inhibited by pepstatin.     

TNF-α Acts as an Immunoregulator in the Mouse Brain by Reducing the Incidence of Severe Disease Following Japanese Encephalitis Virus Infection

Japanese encephalitis virus (JEV) causes acute central nervous system (CNS) disease in humans, in whom the clinical symptoms vary from febrile illness to meningitis and encephalitis. However, the mechanism of severe encephalitis has not been fully elucidated. In this study, using a mouse model, we investigated the pathogenetic mechanisms that correlate with fatal JEV infection. Following extraneural infection with the JaOArS982 strain of JEV, infected mice exhibited clinical signs ranging from mild to fatal outcome. Comparison of the pathogenetic response between severe and mild cases of JaOArS982-infected mice revealed increased levels of TNF-α in the brains of severe cases. However, unexpectedly, the mortality rate of TNF-α KO mice was significantly increased compared with that of WT mice, indicating that TNF-α plays a protective role against fatal infection. Interestingly, there were no significant differences of viral load in the CNS between WT and TNF-α KO mice. However, exaggerated inflammatory responses were observed in the CNS of TNF-α KO mice. Although these observations were also obtained in IL-10 KO mice, the mortality and enhanced inflammatory responses were more pronounced in TNF-α KO mice. Our findings therefore provide the first evidence that TNF-α has an immunoregulatory effect on pro-inflammatory cytokines in the CNS during JEV infection and consequently protects the animals from fatal disease. Thus, we propose that the increased level of TNF-α in severe cases was the result of severe disease, and secondly that immunopathological effects contribute to severe neuronal degeneration resulting in fatal disease. In future, further elucidation of the immunoregulatory mechanism of TNF-α will be an important priority to enable the development of effective treatment strategies for Japanese encephalitis.     

Dynamic Changes in Endothelial Cell Adhesion Molecule Nepmucin/CD300LG Expression under Physiological and Pathological Conditions

Vascular endothelial cells often change their phenotype to adapt to their local microenvironment. Here we report that the vascular endothelial adhesion molecule nepmucin/CD300LG, which is implicated in lymphocyte binding and transmigration, shows unique expression patterns in the microvascular endothelial cells of different tissues. Under physiological conditions, nepmucin/CD300LG was constitutively and selectively expressed at the luminal surface of the small arterioles, venules, and capillaries of most tissues, but it was only weakly expressed in the microvessels of the splenic red pulp and thymic medulla. Furthermore, it was barely detectable in immunologically privileged sites such as the brain, testis, and uterus. The nepmucin/CD300LG expression rapidly decreased in lymph nodes receiving acute inflammatory signals, and this loss was mediated at least in part by TNF-α. It was also down-regulated in tumors and tumor-draining lymph nodes, indicating that nepmucin/CD300LG expression is negatively regulated by locally produced signals under these circumstances. In contrast, nepmucin/CD300LG was induced in the high endothelial venule-like blood vessels of chronically inflamed pancreatic islets in an animal model of non-obese diabetes. Interestingly, the activated CD4⁺ T cells infiltrating the inflamed pancreas expressed high levels of the nepmucin/CD300LG ligand(s), supporting the idea that nepmucin/CD300LG and its ligand interactions are locally involved in pathological T cell trafficking. Taken together, these observations indicate that the nepmucin/CD300LG expression in microvascular endothelial cells is influenced by factor(s) that are locally produced in tissues, and that its expression is closely correlated with the level of leukocyte infiltration in certain tissues.