Sexual dimorphism and dichromatism in the cyprinid fish <Emphasis Type="Italic">Puntius titteya</Emphasis>

We documented sexual dimorphism and dichromatism in the cyprinid fish Puntius titteya. We observed no sexual difference in body size, although males had longer fins than females. Male body coloration was redder and exhibited a higher saturation than that of females. However, in females, coloration in the cheek (around the gill cover) was near red and exhibited high saturation compared to coloration of the abdomen. These results clearly indicate sexual dimorphism in fin size and dichromatism in P. titteya, which suggests that this species has a high potential use as a model for studying sexual selection.     

Hyperlipidemia in mast cell-deficient W/WV mice

Approximately 70% of the W/WV mice lacking mast cells due to a genetic defect showed hypertriglyceridemia combined with hypercholesterolemia. Increases of various magnitudes in chylomicrons, very-low-density lipoprotein, and intermediate-density lipoprotein were observed in the plasma of W/WV mice compared to those in the plasma of congenic normal mice. The increase in these lipoproteins was seen even in normolipidemic W/WV mice. Activities of both lipoprotein lipase and hepatic triacylglycerol lipase in the plasma after heparin injection were markedly lower in the W/WV mice than in the congenic normal mice, although activities of both lipoprotein lipase in the heart and adipose tissue and hepatic triacylglycerol lipase in the liver were not decreased. These results suggest that the W/WV mice have genetic defects in one or more of the following: secretion of both lipases from their synthesising cells, transport to the endothelium, and anchoring to the endothelial surface. Heparin deficiency in these mice may be responsible for the impairment and, thereby, may partially contribute to the hyperlipidemia.     

Differential mechanism and site of action of CCK on the pancreatic secretion and growth in rats

Recent studies demonstrated that cholecystokinin (CCK) at physiological levels stimulates pancreatic enzyme secretion via a capsaicin-sensitive afferent vagal pathway. This study examined whether chemical ablation of afferent vagal fibers influences pancreatic growth and secretion in rats. Bilateral subdiaphragmatic vagal trunks were exposed, and capsaicin solution was applied. Pancreatic wet weight and pancreatic secretion and growth in response to endogenous and exogenous CCK were examined 7 days after capsaicin treatment. Perivagal application of capsaicin increased plasma CCK levels and significantly increased pancreatic wet weight compared with those in the control rats. Oral administration of CCK-1 receptor antagonist loxiglumide prevented the increase in pancreatic wet weight after capsaicin treatment. In addition, continuous intraduodenal infusion of trypsin prevented the increase in plasma CCK levels and pancreatic wet weight after capsaicin treatment. There were no significant differences in the expression levels of CCK-1 receptor mRNA and protein in the pancreas in capsaicin-treated and control rats. Intraduodenal administration of camostat or intravenous infusion of CCK-8 stimulated pancreatic secretion in control rats but not in capsaicin-treated rats. In contrast, repeated oral administrations of camostat or intraperitoneal injections of CCK-8 significantly increased pancreatic wet weight in both capsaicin-treated and control rats. Present results suggest that perivagal application of capsaicin stimulates pancreatic growth via an increase in endogenous CCK and that exogenous and endogenous CCK stimulate pancreatic growth not via vagal afferent fibers but directly in rats.     

Mutations in a Saccharomyces cerevisme host showing increased holding stability of the heterologous plasmid pSRI

Summary We have isolated Saccharomyces cerevisiae mutants, smp, showing stable maintenance of plasmid pSRI, a Zygosaccharomyces rouxii plasmid. The smp mutants were recessive and were classified into at least three different complementation groups. The three mutants also showed increased stability of YRp plasmids and the mutations are additive for plasmid stability. One mutation, smp1, confers a respiration-deficient (rho ⁰) phenotype and several Rho^– mutants independently isolated by ethidium bromide treatment of the same yeast strain also showed increased stabilities of pSR1 and YRp plasmids. The wild-type S. cerevisiae cells showed a strongly biased distribution of pSR1 molecules as well as YRp plasmids to the mother cells at mitosis, while the smpf mutant did not show this bias. Another mutation, smp3, at a locus linked to ade2 on chromosome XV, confers temperature-sensitive growth. The SMP3 gene encodes a 59.9 kDa hydrophobic protein and disruption of the gene is lethal.     

Glycosidic fraction of flue-cured tobacco leaves: its separation and component analysis

The fraction containing glycosidic components was separated from flue-cured tobacco (Nicotiana tabacum L.) leaves by a facile method. Some components of the fraction were isolated and elucidated to be syringin, coniferin, cichoriin, benzyl-beta-D-glucoside, Blumenol A-beta-D-glucoside, and 5,6-epoxy-5,6-dihydro-3-hydroxy-beta-ionyl-beta-D-glucoside. Syringin and coniferin were detected in the Nicotiana species for the first time.     

Site specific cytosine methylation in rice nonautonomous transposable element <Emphasis Type="Italic">nDart</Emphasis>

The mobile nonautonomous element nDart, which is active in intact rice plants, exhibits locus specific transposition. Due to the high homogeneity of nDart elements, the locus specificity of nDart transposition might be controlled by factors other than genetic differences. In this study, we elucidated the regulation of the locus specificity of nDart transposition. The difference of transpositional activities in 10 nDart elements among rice varieties exhibiting nDart transposition was clearly correlated with the methylation state of nDart elements. Both hyper- and hypo-methylated nDart elements were inactive, while site specific methylation in both subterminal regions was identified in active nDart loci. The specific methylation sites contain the pentamer motif GCC/ACG. The repeated motifs in the subterminal region of nDart elements may contribute to the stable secondary structure of nDart elements with low free energy. Our results suggested that site specific cytosine methylation may loosen the stable secondary structure of the nDart element to allow it to bind TPase, which then perform the excision of nDart elements from genomic loci.     

Theste13+ gene encoding a putative RNA helicase is essential for nitrogen starvation-induced G1 arrest and initiation of sexual development in the fission yeastSchizosaccharomyces pombe

When the fission yeastSchizosaccharomyces pombe is starved for nitrogen, the cells are arrested in the G1 phase, enter the G0 phase and initiate sexual development. Theste13 mutant, however, fails to undergo a G1 arrest when starved for nitrogen and since this mutant phenotype is not suppressed by a mutation in adenylyl cyclase (cyr1), it would appear thatste13 ⁺ either acts independently of the decrease in the cellular cAMP level induced by starvation for nitrogen, or functions downstream of this controlling event. We have used functional complementation to clone theste13 ⁺ gene from anS. pombe genomic library and show that its disruption is not lethal, indicating that, while the gene is required for sexual development, it is not essential for cell growth. Nucleotide sequencing predicts thatste13 ⁺ should encode a protein of 485 amino acids in which the consensus motifs of ATP-dependent RNA helicases of the DEAD box family are completely conserved. Point mutations introduced into these consensus motifs abolished theste13 ⁺ functions. The predicted Ste13 protein is 72% identical to theDrosophila melanogaster Me31B protein over a stretch of 391 amino acids. ME31B is a developmentally regulated gene that is expressed preferentially in the female germline and may be required for oogenesis. Expression of ME31B cDNA inS. pombe suppresses theste13 mutation. These two evolutionarily conserved genes encoding putative RNA helicases may play a pivotal role in sexual development.     

Cloning and expression of the gene encoding <Emphasis Type="BoldItalic">Streptomyces coelicolor</Emphasis> A3(2) α-galactosidase belonging to family 36

The α-galactosidase gene of Streptomyces coelicolor A3(2) was cloned, expressed in Escherichia coli and characterized. It consisted of 1497 nucleotides encoding a protein of 499 amino acids with a predicted molecular weight of 57,385. The observed homology between the deduced amino acid sequences of the enzyme and α-galactosidase from Thermus thermophilus was over 40%. The α-galactosidase gene was assigned to family 36 of the glycosyl hydrolases. The enzyme purified from recombinant E. coli showed optimal activity at 40 °C and pH 7. The enzyme hydrolyzed p-nitrophenyl-α-D-galactopyroside, raffinose, stachyose but not melibiose and galactomanno-oligosaccharides, indicating that this enzyme recognizes not only the galactose moiety but also other substrates.     

Ethanol production from cellobiose by Zymobacter palmae carrying the Ruminocuccus albus beta-glucosidase gene

Its metabolic characteristics suggest Zymobacter palmae gen. nov., sp. nov. could serve as a useful new ethanol-fermenting bacterium, but its biotechnological exploitation would require certain genetic improvements. We therefore established a method for transforming Z. palmae using the broad-host vector plasmids pRK290, pMFY31 and pMFY40 as a source of transforming DNA. Using electroporation, the frequency of transformation was 10(5) to 10(6) transformants/mug of DNA. To confer the ability to ferment cellobiose, which is a hydrolysis product from cellulosic materials treated enzymatically or with acid, the beta-glucosidase gene from Ruminococcus albus was introduced into Z. palmae, where its expression was driven by its endogenous promoter. About 56% of the enzyme expressed was localized on the cell-surface or in the periplasm. The recombinant Z. palmae could ferment 2% cellobiose to ethanol, producing 95% of the theoretical yield with no accumulation of organic acids as metabolic by-products. Thus, expression of beta-glucosidase in Z. palmae expanded the substrate spectrum of the strain, enabling ethanol production from cellulosic materials.