Uric Acid Secretion from Adipose Tissue and Its Increase in Obesity

Obesity is often accompanied by hyperuricemia. However, purine metabolism in various tissues, especially regarding uric acid production, has not been fully elucidated. Here we report, using mouse models, that adipose tissue could produce and secrete uric acid through xanthine oxidoreductase (XOR) and that the production was enhanced in obesity. Plasma uric acid was elevated in obese mice and attenuated by administration of the XOR inhibitor febuxostat. Adipose tissue was one of major organs that had abundant expression and activities of XOR, and adipose tissues in obese mice had higher XOR activities than those in control mice. 3T3-L1 and mouse primary mature adipocytes produced and secreted uric acid into culture medium. The secretion was inhibited by febuxostat in a dose-dependent manner or by gene knockdown of XOR. Surgical ischemia in adipose tissue increased local uric acid production and secretion via XOR, with a subsequent increase in circulating uric acid levels. Uric acid secretion from whole adipose tissue was increased in obese mice, and uric acid secretion from 3T3-L1 adipocytes was increased under hypoxia. Our results suggest that purine catabolism in adipose tissue could be enhanced in obesity.     

Ifit1 Inhibits Japanese Encephalitis Virus Replication through Binding to 5′ Capped 2′-O Unmethylated RNA

The interferon-inducible protein with tetratricopeptide (IFIT) family proteins inhibit replication of some viruses by recognizing several types of RNAs, including 5′-triphosphate RNA and 5′ capped 2′-O unmethylated mRNA. However, it remains unclear how IFITs inhibit replication of some viruses through recognition of RNA. Here, we analyzed the mechanisms by which Ifit1 exerts antiviral responses. Replication of a Japanese encephalitis virus (JEV) 2′-O methyltransferase (MTase) mutant was markedly enhanced in mouse embryonic fibroblasts and macrophages lacking Ifit1. Ifit1 bound 5′-triphosphate RNA but more preferentially associated with 5′ capped 2′-O unmethylated mRNA. Ifit1 inhibited the translation of mRNA and thereby restricted the replication of JEV mutated in 2′-O MTase. Thus, Ifit1 inhibits replication of MTase-defective JEV by inhibiting mRNA translation through direct binding to mRNA 5′ structures.     

Laser Capture Microdissection Assessment of Virus Compartmentalization in the Central Nervous Systems of Macaques Infected with Neurovirulent Simian Immunodeficiency Virus

Nonhuman primate-simian immunodeficiency virus (SIV) models are powerful tools for studying the pathogenesis of human immunodeficiency virus type 1 (HIV-1) in the brain. Our laboratory recently isolated a neuropathogenic viral swarm, SIVsmH804E, a derivative of SIVsmE543-3, which was the result of sequential intravenous passages of viruses isolated from the brains of rhesus macaques with SIV encephalitis. Animals infected with SIVsmH804E or its precursor (SIVsmH783Br) developed SIV meningitis and/or encephalitis at high frequencies. Since we observed macaques with a combination of meningitis and encephalitis, as well as animals in which meningitis or encephalitis was the dominant component, we hypothesized that distinct mechanisms could be driving the two pathological states. Therefore, we assessed viral populations in the meninges and the brain parenchyma by laser capture microdissection. Viral RNAs were isolated from representative areas of the meninges, brain parenchyma, terminal plasma, and cerebrospinal fluid (CSF) and from the inoculum, and the SIV envelope fragment was amplified by PCR. Phylogenetic analysis of envelope sequences from the conventional progressors revealed compartmentalization of viral populations between the meninges and the parenchyma. In one of these animals, viral populations in meninges were closely related to those from CSF and shared signature truncations in the cytoplasmic domain of gp41, consistent with a common origin. Apart from magnetic resonance imaging (MRI) and positron-emission tomography (PET) imaging, CSF is the most accessible assess to the central nervous system for HIV-1-infected patients. However, our results suggest that the virus in the CSF may not always be representative of viral populations in the brain and that caution should be applied in extrapolating between the properties of viruses in these two compartments.     

Genetic Diversity and Geographical Distribution of Indigenous Soybean-Nodulating Bradyrhizobia in the United States

We investigated the relationship between the genetic diversity of indigenous soybean-nodulating bradyrhizobia and their geographical distribution in the United States using nine soil isolates from eight states. The bradyrhizobia were inoculated on three soybean Rj genotypes (non-Rj, Rj₂Rj₃, and Rj₄). We analyzed their genetic diversity and community structure by means of restriction fragment length polymorphisms of PCR amplicons to target the 16S-23S rRNA gene internal transcribed spacer region, using 11 USDA Bradyrhizobium strains as reference strains. We also performed diversity analysis, multidimensional scaling analysis based on the Bray-Curtis index, and polar ordination analysis to describe the structure and geographical distribution of the soybean-nodulating bradyrhizobial community. The major clusters were Bradyrhizobium japonicum Bj123, in the northern United States, and Bradyrhizobium elkanii, in the middle to southern regions. Dominance of bradyrhizobia in a community was generally larger for the cluster belonging to B. elkanii than for the cluster belonging to B. japonicum. The indigenous American soybean-nodulating bradyrhizobial community structure was strongly correlated with latitude. Our results suggest that this community varies geographically.     

Assimilate translocation and expression of sucrose transporter,OsSUT1, contribute to high-performance ripening under heat stress in the heat-tolerant rice cultivar Genkitsukushi

High temperature reduces the grain quality of rice, a situation likely to become more frequent because of global warming. We studied the effects of high-temperature stress on grain quality of heat-tolerant cultivar ‘Genkitsukushi’ and heat-sensitive cultivar ‘Tsukushiroman’. When day/night temperatures were 31/26 °C from heading until maturity, the grain quality of ‘Genkitsukushi’ was rated at the first inspection grade (high quality), whereas ‘Tsukushiroman’ showed a remarkable increase in the percentage of white immature kernels (low quality). Nonstructural carbohydrate content in the stem of ‘Genkitsukushi’ the early maturation was significantly higher than in ‘Tsukushiroman’ and greatly decreased under high temperature. From 14 to 21 days after heading, the expression of the sucrose transporter gene, OsSUT1, was higher in the stem of ‘Genkitsukushi’ grown under high temperature than in ‘Tsukushiroman’. In addition, the expression of OsSUT1 in the grains of ‘Genkitsukushi’ was significantly higher than in ‘Tsukushiroman’ during the ripening period. These results indicate that sugar transport functions more effectively in ‘Genkitsukushi’ than in ‘Tsukushiroman’, and that the effectiveness of sugar transport contributes to maintaining high grain quality in ‘Genkitsukushi’ under high-temperature conditions.     

Novel polyvalent live vaccine against varicella–zoster and mumps virus infections

The varicella–zoster virus (VZV) Oka vaccine strain (vOka) is a highly immunogenic and safe live vaccine that has long been used worldwide. Because its genome is large, making it suitable for inserting foreign genes, vOka is considered a candidate vector for novel polyvalent vaccines. Previously, a recombinant vOka, rvOka‐HN, that expresses mumps virus (MuV) hemagglutinin‐neuraminidase (HN) was generated by the present team. rvOka‐HN induces production of neutralizing antibodies against MuV in guinea pigs. MuV also expresses fusion (F) protein, which is important for inducing neutralizing antibodies, in its viral envelope. To induce a more robust immune response against MuV than that obtained with rvOka‐HN, here an rvOka expressing both HN and F (rvOka‐HN‐F) was generated. However, co‐expression of HN and F caused the infected cells to form syncytia, which reduced virus titers. To reduce the amount of cell fusion, an rvOka expressing HN and a mutant F, F(S195Y) were generated. Almost no syncytia formed among the rvOka‐HN‐F(S195Y)‐infected cells and the growth of rvOka‐HN‐F(S195Y) was similar to that of the original vOka clone. Moreover, replacement of serine 195 with tyrosine had no effect on the immunogenicity of F in mice and guinea pigs. Although obvious augmentation of neutralizing antibody production was not observed after adding F protein to vOka‐HN, the anti‐F antibodies did have neutralizing activity. These data suggest that F protein contributes to induction of immune protection against MuV. Therefore this recombinant virus is a promising candidate vaccine for polyvalent protection against both VZV and MuV.     

Prevalence of staphylococcal enterotoxins in Staphylococcus pseudintermedius isolates from dogs with pyoderma and healthy dogs

To investigate the role of staphylococcal enterotoxins (SEs) produced by Staphylococcus pseudintermedius in the pathogenesis of pyoderma, isolates from dogs with pyoderma and healthy dogs were analyzed. According to reverse passive latex agglutination, 14/184 isolates (7.6%) from dogs with pyoderma and 9/87 (10.3%) from healthy dogs produced SEs (SEA, SEC or SED). According to multiplex PCR, 99 isolates (53.7%) from dogs with pyoderma and 97 (90.8%) from healthy dogs possessed one or more se genes. There was no significant difference regarding ses between dogs with pyoderma and healthy dogs. Therefore, SEs may not be a direct virulence factor in pyoderma.     

Reaction between Nitrite and Low Salt-soluble Diffusible Fraction of Meat. Some Compounds Influencing Nitrite Depletion and Producing Unidentified-N Compounds

A low salt-soluble, diffusible fraction of meat was separated into basic, neutral and acidic fractions. Investigations were then conducted on the reaction of each fraction with nitrite and on the recovery of the added nitrite.

The basic fraction shared the lowest ability to decompose nitrite and had 88% recovery of added nitrite-N. Hypoxanthine was one of the main components that affected the recovery in the basic fraction. In the neutral fraction, 42% of nitrite was decomposed, and the recovery of the nitrite was 107%. In the acidic fraction, more than 80% of nitrite was decomposed and 30% was converted to unidentified-N compounds. Among endogenous acidic substances tested, cysteic acid showed the highest ability to decompose nitrite, accompanying the production of unidentified-N compounds.