Archival tagging reveals swimming depth and ambient and peritoneal cavity temperature in age-0 Pacific bluefin tuna, <Emphasis Type="Italic">Thunnus orientalis</Emphasis>, off the southern coast of Japan

Although archival tags have been deployed in Thunnus since the early 1990s, few studies have placed such loggers on the small-size growth stage. In this study, Pacific bluefin tuna (PBT, Thunnus orientalis) 20–26.5 cm in fork length (FL) were fitted with archival tags and released off the southern coastal area of Japan from July to August in 2012, 2013, and 2014. Time-series data on swimming depth, ambient water temperature, and peritoneal cavity temperatures collected at 30-s intervals during 78–144 days were analyzed in 11 age-0 PBT. In August, the age-0 PBT spent 69.5 to 83.4% of their time within the mixed layer at mean temperatures between 27.6 and 28.3 °C, while previous studies reported that PBT with FL > 50 cm in the East China Sea are found most often in zones with temperatures between 14 and 19 °C. The thermal difference between the peritoneal cavity and ambient temperature was less than 1 °C for age-0 PBT in August, indicating that they were not in danger of overheating. The mean daytime swimming depths of age-0 PBT were significantly and positively correlated with the depth of the thermocline, especially from August to October. By focusing their swimming depths around the thermocline, the age-0 PBT potentially maximize the probability of encountering prey. There was a significant correlation between the mean nighttime depth and lunar illumination. The change in vertical distribution with the lunar cycle during nighttime is likely a form of predator avoidance.     

Synergistic Function of rolB, rolC, ORF13 and ORF14 of TL-DNA of Agrobacterium rhizogenes in Hairy Root Induction in Nicotiana tabacum

Comparison of the frequency of rooting in the tobacco leaf segmentsinoculated with Agrobacterium tumefaciens harboring variouscombinations of rolB, rolC, ORF13 and ORF14 of TL-DNA of Riplasmid (pRiHRI) revealed that the genes differ in their functionto stimulate adventitious root induction. A single gene rolBinduced roots, while rolC, ORF13 and ORF14 independently promotedthe root induction by the rolB gene. The effects of these geneson the rolB-mediated rooting were in the order of ORF13>rolCORF14. Present address: Laboratory of Phylogenetic Botany, Departmentof Biology, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba,263-8522 Japan. ² Present address: Department of Chemical and Biological Sciences,Faculty of Science, Japan Women's University, 2-8-1 Mejirodai,Bunkyo-ku, Tokyo, 112-8681 Japan.     

Cholesterol inclusion in liposomes affects induction of antigen-specific IgG and IgE antibody production in mice by a surface-linked liposomal antigen

In the previous study, we investigated the induction of ovalbumin (OVA)-specific antibody production in mice by OVA-liposome conjugates made using four different lipid components, including unsaturated carrier lipid and three different saturated carrier lipids. All of the OVA-liposome conjugates tested induced IgE-selective unresponsiveness. The highest titer of anti-OVA IgG was observed in mice immunized with OVA-liposomes made using liposomes with the highest membrane fluidity, suggesting that the membrane fluidity of liposomes affects their adjuvant effect. In this study, liposomes with five different cholesterol inclusions, ranging from 0% to 43% of the total lipid, were made, and the induction of OVA-specific antibody production by OVA-liposome conjugates was compared among these liposome preparations. In contrast to the results in the previous study, liposomes that contained no cholesterol and possessed the lowest membrane fluidity demonstrated the highest adjuvant effect for the induction of IgG antibody production. In addition, when the liposomes with four different lipid compositions were used, OVA-liposome conjugates made using liposomes that did not contain cholesterol induced significantly higher levels of anti-OVA IgG antibody production than did those made using liposomes that contained cholesterol and, further, induced significant production of anti-OVA IgE. These results suggest that cholesterol inclusion in liposomes affects both adjuvanticity for IgG production and regulatory effects on IgE synthesis by the surface-coupled antigen of liposomes.     

Evolutionary Dynamics of Nitrogen Fixation in the Legume–Rhizobia Symbiosis

The stabilization of host–symbiont mutualism against the emergence of parasitic individuals is pivotal to the evolution of cooperation. One of the most famous symbioses occurs between legumes and their colonizing rhizobia, in which rhizobia extract nutrients (or benefits) from legume plants while supplying them with nitrogen resources produced by nitrogen fixation (or costs). Natural environments, however, are widely populated by ineffective rhizobia that extract benefits without paying costs and thus proliferate more efficiently than nitrogen-fixing cooperators. How and why this mutualism becomes stabilized and evolutionarily persists has been extensively discussed. To better understand the evolutionary dynamics of this symbiosis system, we construct a simple model based on the continuous snowdrift game with multiple interacting players. We investigate the model using adaptive dynamics and numerical simulations. We find that symbiotic evolution depends on the cost–benefit balance, and that cheaters widely emerge when the cost and benefit are similar in strength. In this scenario, the persistence of the symbiotic system is compatible with the presence of cheaters. This result suggests that the symbiotic relationship is robust to the emergence of cheaters, and may explain the prevalence of cheating rhizobia in nature. In addition, various stabilizing mechanisms, such as partner fidelity feedback, partner choice, and host sanction, can reinforce the symbiotic relationship by affecting the fitness of symbionts in various ways. This result suggests that the symbiotic relationship is cooperatively stabilized by various mechanisms. In addition, mixed nodule populations are thought to encourage cheater emergence, but our model predicts that, in certain situations, cheaters can disappear from such populations. These findings provide a theoretical basis of the evolutionary dynamics of legume–rhizobia symbioses, which is extendable to other single-host, multiple-colonizer systems.     

Relationship between body iron stores and diquat toxicity in male Fischer-344 rats

The effects of body iron stores on diquat (DQ)-induced toxicity were examined in male Fischer-344 rats, which are sensitive to this herbicide. The rats (5 weeks old) were fed diets containing 40 (lower iron storage [LIS] group) or 320 ppm iron (higher iron storage [HIS] group) for 5 weeks. The concentrations of nonheme iron and ferritin in the liver and kidney were significantly higher in the HIS group than in the LIS group (P<0.0001), although there was no significant differences between the HIS and LIS groups in hematological parameters, including red blood cell count, hemoglobin concentration, and mean corpuscular volume. Three hours after administration of 0.1 mmol DQ/kg, serum alanine aminotransferase and urea nitrogen were significantly higher than in controls (saline injection) for both the LIS and HIS groups (P<0.01), and, after DQ injection, these parameters were significantly higher in the HIS group than in the LIS group (P<0.01). When the rats were injected with 0.075 or 0.1 mmol DQ/kg, the survival time was significantly shorter in the HIS group than in the LIS group (P<0.05). These findings suggest that higher body iron stores result in more severe DQ toxicity in Fischer-344 rats.     

T cell-independent regulation of IgE antibody production induced by surface-linked liposomal antigen

Control of IgE Ab production is important for the prevention of IgE-related diseases. However, in contrast to the existing information on the induction of IgE production, little is known about the regulation of the production of this isotype, with the exception of the well-documented mechanism involving T cell subsets and their cytokine products. In this study, we demonstrate an alternative approach to interfere with the production of IgE, independent of the activity of T cells, which was discovered during the course of an investigation intended to clarify the mechanism of IgE-selective unresponsiveness induced by surface-coupled liposomal Ags. Immunization of mice with OVA-liposome conjugates induced IgE-selective unresponsiveness without apparent Th1 polarization. Neither IL-12, IL-10, nor CD8(+) T cells participated in the regulation. Furthermore, CD4(+) T cells of mice immunized with OVA-liposome were capable of inducing Ag-specific IgE synthesis in athymic nude mice immunized with alum-adsorbed OVA. In contrast, immunization of the recipient mice with OVA-liposome did not induce anti-OVA IgE production, even when CD4(+) T cells of mice immunized with alum-adsorbed OVA were transferred. In the secondary immune response, OVA-liposome enhanced anti-OVA IgG Ab production, but it did not enhance ongoing IgE production, suggesting that the IgE-selective unresponsiveness induced by the liposomal Ag involved direct effects on IgE, but not IgG switching in vivo. These results suggest the existence of an alternative mechanism not involving T cells in the regulation of IgE synthesis.     

Extracellular Formation of O-Butylhomoserine by Anaerobes

Clostridium BB–264, Cl. acetobutyricum 314–48, Cl. kaneboi, Cl. saccharoperbutylacetonicum and other two strains of Cl isolated recently produced an unidentified ninhydrin-positive compound in medium containing 5 % glucose, 1 % ammonium acetate, 0.1 % potassium dihydrogen phosphate, 0.04 % magnesium sulfate, 0.001 % ferrous sulfate, 0.1 % yeast extract, 10 μg/liter of biotin and 1 % calcium carbonate.

This ninhydrin-positive compound was eluted with solvent composed of butanol: acetic acid: water (4: 1: 2) by chromatography on cellulose powder column. It was crystallized from ethanol and then identified as an amino acid, O-butylhomoserine (Abbrev. as O-BHSer). Yield of this amino acid increased by adding homoserine or butanol to the medium. The increase was also recognized with addition of glycine, lysine, serine, threonine or valine. The formation of this amino acid was repressed by adding methionine to the medium.

Gas pressure to the culture is one of the important factors that make the amino acid formation by anaerobes possible.     

Contribution of Zinc Deficiency to Insulin Resistance in Patients with Primary Biliary Cirrhosis

The relationship between metabolic abnormalities of trace elements and insulin resistance has been established. Recent studies have revealed that insulin resistance is associated with autoimmune responses. The purpose of this study was to examine the correlation between zinc or copper metabolism and insulin resistance in patients with primary biliary cirrhosis (PBC). Sixteen patients with PBC were divided into two groups: early and advanced stage disease. The overall value of the homeostasis model assessment of insulin resistance (HOMA-IR) in patients with advanced stage PBC was significantly higher than that in patients with early stage PBC, although the mean value in advanced stage PBC was significantly lower than that in hepatitis C virus (HCV)-related liver cirrhosis. There was an inverse correlation between serum zinc concentrations and HOMA-IR values in patients with PBC, while we found no correlation between serum copper levels and HOMA-IR values. HOMA-IR values were inversely associated with peripheral platelet counts, indicating the relationship between insulin resistance and hepatic fibrosis. These results suggest that zinc deficiency plays important roles of insulin resistance and subsequent hepatic fibrosis in patients with PBC, although insulin resistance in advanced stage PBC was significantly milder than that in HCV-related liver cirrhosis.