A marked change in insulin binding to rat thymic lymphocytes by fractionation of the cells into two subsets

As compared with the pre-separated thymic lymphocyte (TL) population, a marked reduction of insulin binding was found in the two fractions [supernatant lymphocytes (SL) and precipitate lymphocytes (PL)] separated by low-speed differential centrifugation from the TL population. The reduction in insulin binding to SL or PL appeared to be due to a decrease in the affinity rather than a decrease in the number of insulin receptors. The reduced insulin binding was enhanced to near the level of the TL population when SL and PL were mixed and then incubated for 90 min at 37 degrees C. Moreover, when the cell-free supernatant from the mixed and incubated fraction was added to SL and PL respectively, the insulin binding to each fraction was found to be enhanced.     

Distribution of actin-filament bundles in myoid cells,Sertoli cells,and tunica albuginea of rat and mouse testes

Summary Frozen sections of the rat and mouse testes were stained with either FITC-phalloidin or NBD-phallacidin and viewed with conventional fluorescence and confocal laser microscopes in order to demonstrate the arrangment of actin-filament bundles in myoid cells, Sertoli cells and tunica albuginea. Myoid cells are rich in actin-filament bundles crossing at right angles. These bundles running in different directions can also be visualized by means of electron microscopy. Nerve fibers occur in the vicinity of myoid cells, suggesting a neural control of the cell. At Sertoli cell junctions actin filaments occur at the circumference of the cell, where they show a honeycomb pattern. The ratio of the number of Sertoli cells per myoid cell can be calculated by means of confocal microscopy; this technique may provide a new parameter for determining spermatogenic activity. In the tunica albuginea of the juvenile mouse testis, actin filaments are arranged in an alternate fashion.     

Neurite-Promoting Activities of Phosphatidylinositol and Other Lipids on Fetal Rat Septal Neurons in Culture

Neurite-promoting activities of lipids were assessed using serum-free cultures of fetal rat septal neurons. The most potent one was phosphatidylinositol (PI), followed by PI 4-phosphate, phosphatidylserine, sphingomyelin, and phosphatidylcholine. The EC50 value for PI was 1.5 micrograms/ml (1.8 microM), and activity was maximal at 4 micrograms/ml (56% of total cells had neurites after 24 h). Cerebroside, sulfatide, and di- and triacylglycerols showed relatively low activities. Synthetic dipalmitoyl phosphatidylcholine was also active, with a maximal activity (47%) at 100 micrograms/ml, a finding implying that the unsaturated fatty acid moiety is not released and further used as substrate for the arachidonic acid cascade. Lysophospholipids, phosphatidylglycerol, and cardiolipin were rather cytotoxic and lacked activity, an observation suggesting that membrane perturbation is not responsible for the neurite-promoting activity. Treatment with a protein kinase C inhibitor, H-7, or an Na+,K(+)-ATPase inhibitor, ouabain, inhibited the PI-induced neurite outgrowth, but the cyclic AMP- and cyclic GMP-dependent protein kinase inhibitor HA1004 did not inhibit this activity, a result indicating that multiple elements (protein kinase C and Na+,K(+)-ATPase) are involved in the induction of neurites. Because phospholipids can be provided either as lipid vesicles or as lipoproteins produced by macrophages at regeneration sites, they may play an important role in the regeneration of certain populations of neurons.     

Aristoloside,an aristolochic acid derivative from stems of Aristolochia manshuriensis

Aristoloside, a new companion aristolochic acid derivative isolated from stems of Aristolochia manshuriensis has been shown to be 6-O-β-d-glucopyranoside of aristolochic acid-D on chemical and physicochemical evidence. Three known acids, aristolochic acids I, IV (both as their corresponding methyl esters), and -D have also been characterized from stems of the plant.     

Isolation of sulfated glycoproteins from human gastric juice with lysine-Sepharose

A procedure for the isolation of sulfated glycoproteins from human gastric juice is described. Sulfated glycoproteins are adsorbed on lysine-Sepharose at pH 2.0, where only the sulfate group of glycoproteins carries a negative charge. The method is simple and rapid, and moreover, the recovery of sulfate is excellent. The sulfated glycoproteins were readily separated from the glycoproteins and other components in gastric juice. The sulfate content of the isolated sulfated glycoproteins ranged from 4 to 15% and increased with increasing molarity of eluting salt.     

Purification of the agent inducing lipid peroxidation with dihydroxyfumaric acid in rat liver mitochondria

Dihydroxyfumaric acid induces lipid peroxidation in rat liver mitochondria as reported previously. When the mitochondria were solubilized with 0.35% ($\text{W}\text{V}$) sodium cholate, the supernatant itself could not catalyze lipid peroxidation with dihydroxyfumaric acid, but the precipitate slightly induced the reaction. The supernatant produced lipid peroxide in the presence of the precipitate and dihydroxyfumaric acid. The supernatant was heat sensitive contrary to the stability of the precipitate. An attempt was made to isolate active entity through a sephadex G-200 column and a DEAE-cellulose column, resulting in about 10-fold purification. At 408–410 nm the partially purified agent showed a maximum absorption, which disappeared rapidly after reduction with sodium dithionite and was slowly diminished with dihydroxyfumaric acid. The molecular weight was much larger than that of oxidized cytochrome c.     

Structural analysis of a Lotus japonicus genome. V. Sequence features and mapping of sixty-four TAC clones which cover the 6.4 mb regions of the genome.

We determined the nucleotide sequences of 64 TAC (transformation-competent artificial chromosome) clones selected from genomic libraries of Lotus japonicus accession Miyakojima MG-20 based on the sequence information of expressed sequence tags (ESTs), cDNAs, genes and DNA markers from L. japonicus and other legumes. The length of the DNA regions sequenced in this study was 6,370,255 bp, and the total length of the L. japonicus genome sequenced so far is 32,537,698 bp together with the nucleotide sequences of 256 TAC clones previously reported. Five hundred forty-eight potential protein-encoding genes with known or predicted functions, 127 gene segments and 224 pseudogenes were assigned to the newly sequenced regions by computer prediction and similarity searches against the sequences in protein and EST databases. Based on the nucleotide sequences of the clones, simple sequence repeat length polymorphism (SSLP) or derived cleaved amplified polymorphic sequence (dCAPS) markers were generated, and each clone was genetically localized onto the linkage map of two accessions of L. japonicus, MG-20 and Gifu B-129. The sequence data, gene information and mapping information are available through the World Wide Web at http://www.kazusa.or.jp/lotus/.     

Structural analysis of a Lotus japonicus genome. IV. Sequence features and mapping of seventy-three TAC clones which cover the 7.5 mb regions of the genome.

Using the sequence information of expressed sequences tags (ESTs), cDNAs and genes from Lotus japonicus and other legumes, 73 TAC (transformation-competent artificial chromosomes) clones were selected from a genomic library of L. japonicus accession MG-20, and their nucleotide sequences were determined. The length of the DNA sequenced in this study was 7,455,959 bp, and the total length of the DNA regions sequenced so far is 26,167,443 bp together with the nucleotide sequences of 183 TAC clones previously reported. By similarity searches against the sequences in protein and EST databases and prediction by computer programs, a total of 699 potential protein-encoding genes with known or predicted functions, 163 gene segments and 267 pseudogenes were assigned to the newly sequenced regions. Based oil the nucleotide sequences of the clones, simple sequence repeat length polymorphism (SSLP) or derived cleaved amplified polymorphic sequence (dCAPS) markers were generated, and each clone was located onto the linkage map of two accessions of L. japonicus, Gifu B-129 and Miyakojima MG-20. The sequence data, gene information and mapping information are available through the World Wide Web at http://www.kazusa.or.jp/lotus/.     

Effects of prey density, prey instar, and patch size on the development of the predatory mosquito, Toxorhynchites towadensis

Effects of prey density, prey instar, and patch size on the development of the predatory mosquito larva, Toxorhynchites towadensis, were investigated in the laboratory. Survivors of T. towadensis showed different developmental patterns in relation to prey age structure. All predatory larvae in containers with only second instar prey developed into the third instar. However, in several containers with fourth instar prey, mortality of predators was observed. During the third instar, no predatory larva died, but both prey density and prey instar significantly affected the survival of predators during their fourth instar. Large prey size promoted large predator adults, and predatory larvae which grew up in small surface containers responded by developing to large sizes than those in large containers. Larval developmental time of the predators differed in each treatment. During first and second instars, faster predator development was observed in containers with small surface areas and containing young prey individuals. However, when development was enhanced by the presence of old prey individuals, no surface effect was observed. The fastest predator development was observed with prey of mixed instars and high density. This study suggests that a small surface container containing prey of mixed instars and high density is suitable for development of predators.