Preparation and characterization of neutralizing monoclonal antibodies to feline calicivirus.

Fourteen neutralizing monoclonal antibodies (N-MoAbs) were prepared against the F4 strain of feline calicivirus (FCV), the prototype strain of FCV in Japan, and examined for their ability to neutralize FCV isolates. Neutralization-resistant variants of the F4 strain were selected under the presence of 4 individual N-MoAbs in cell culture systems and used in cross-neutralization tests and enzyme-linked immunosorbent assay with all of the 14 N-MoAbs. The results revealed the identification of at least two antigenic determinants on FCV F4: one being more broadly conserved among FCV isolates than the other. Usefulness of antigenic variants resistant to N-MoAbs for analysis of neutralization determinants on FCV was also demonstrated.     

Quantitative and morphological studies on the influence of zinc deficiency on the liver of pregnant rats

The effect of zinc deficiency on trace metals in the liver, spleen, kidney, pancreas and duodenum was investigated in the control and zinc-deficient rats at 17 days and 20 days of pregnancy. Zinc-deficient rats fell into limosis after 5 days of pregnancy. The contents of zinc, iron, copper and manganese in the maternal tissues were measured by colorimetry with 5NPPF. The morphological changes of the liver were observed by light and electron microscopy. The contents of zinc in the pancreas and duodenum were less in the zinc-deficient group than in the control at both 17 days and 20 days of pregnancy. The contents of the copper and manganese in the liver, kidney, pancreas, duodenum and spleen, however, were not significantly different from the control. The contents of iron in the liver, spleen and kidney in the deficient group increased greatly at 17 days and 20 days of pregnancy compared with the control group. The combination rate of transferrin with iron also increased significantly in the deficient group. Staining with Berlin blue or Turnbull's blue showed intense reaction to iron around the interlobular connective tissue of the liver in the zinc deficient group at 20 days of pregnancy. Ultrastructurally, the liver of the zinc-deficient rats showed the decrease of glycogen granules and increase of lipid-like granules and lysosomes with various sizes and electron densities. These findings suggest that zinc deficiency causes the increase of iron contents in the various organs during pregnancy, and that there is an intimate interrelationship between zinc and iron in the metabolism of iron during pregnancy.     

Meiotic Competence of Canine Oocytes Embedded in Collagen Gel

The present study was conducted to examine the meiotic competence of canine oocytes embedded in collagen gel, and to investigate the effects of timed exposure of the oocytes embedded in collagen gel to gonadotrophins during maturation culture, on their nuclear maturation. Cumulus-oocyte complexes (COCs) were collected from bitches at the anoestrous and dioestrous stages of the reproductive cycle. In the first experiment, half of the COCs were embedded in collagen gels. The COCs with or without collagen-gel embedding were cultured in a TCM-199 medium supplemented with 0.1 IU/ml human menopausal gonadotropin (hMG) and 10 IU/ml human chorionic gonadotropin (hCG) for 72 h. In the second experiment, the COCs embedded in collagen gels were cultured in TCM-199 medium with gonadotrophins (hMG and hCG) for various periods (0, 24, 48 and 72 h) and then cultured in the medium without gonadotrophins until reaching total culture period (72 h). The percentage of the oocytes reaching metaphase I and metaphase II (MI/MII) was significantly higher (p < 0.05) in COCs with collagen-gel embedding than in COCs without collagen-gel embedding. The percentage of oocytes that were arrested at the germinal vesicle stage was significantly lower (p < 0.05) in oocytes cultured with gonadotrophins than in oocytes cultured without gonadotrophins. However, there were no significant differences in the percentages of oocytes that reached each stage of meiosis among the groups, irrespective of the duration of exposure to gonadotrophins. These observations indicate that embedding of COCs by collagen gel enhances the meiotic competence of canine oocytes, but removal of hormone supplement from maturation medium does not improve the ability of the oocytes to reach MII stage.     

Cell proliferation activity of proliferating bile duct after bile duct ligation in rats

The cell proliferation activity of proliferating bile ducts produced by bile duct ligation (BDL) in rats was examined histologically, immunohistochemically, and ultrastructurally. Proliferating bile ducts, which were similar to normal bile ducts, increased with time after BDL. The cell proliferation activity of proliferating bile ducts, measured using proliferating-cell nuclear antigen and 5-bromo-2'-deoxyuridine antibodies, tended to be high at 1 and 3 days after BDL and decreased progressively at 2 to 4 weeks after BDL. On the other hand, alpha-smooth muscle actin-positive myofibroblast-like cells increased continuously after BDL. These findings indicate that there is a negative correlation between the cell proliferation activity of proliferating bile ducts and that of myofibroblast-like cells.     

Virulence characteristics of Yersinia pseudotuberculosis isolated from breeding monkeys in Japan

Between April 2001 and 2007, 18 Yersinia pseudotuberculosis outbreaks occurred in breeding monkeys at 12 zoological gardens in Japan, and 28 monkeys of 8 species died. A total of 18 Y. pseudotuberculosis strains from the dead monkeys, comprising one strain per outbreak, were examined for serotype and the presence of the virulence genes virF, inv, ypm (ypmA, ypmB and ypmC) and irp2. Of the 18 Y. pseudotuberculosis strains, 7 (38.9%) were serotype 4b, 7 (38.9%) were serotype 1b, and there was one each of serotypes 2b, 3, 6 and 7. All the 18 strains examined harbored virF and inv. Sixteen (88.9%) strains, including the strain of serotype 7, harbored ypmA. However, no strain harbored ypmB, ypmC and irp2.

This study demonstrated that among other pathogenic factors, almost all the Y. pseudotuberculosis isolated from the outbreaks had the ypm gene encoding the superantigenic toxin, YPM. As most of the monkeys who died in those outbreaks originated from South America and other regions, where the presence of the ypm gene have not been reported, YPM might be the cause, or at least the most important factor for, the high mortality of the breeding monkeys infected by Y. pseudotuberculosis in Japan. This is also the first report of a fatal case due to Y. pseudotuberculosis serotype 7 infection in the world.     

Estimation of variance and genomic prediction using genotypes imputed from low‐density marker subsets for carcass traits in Japanese black cattle

The influence of genotype imputation using low‐density single nucleotide polymorphism (SNP) marker subsets on the genomic relationship matrix (G matrix), genetic variance explained, and genomic prediction (GP) was investigated for carcass weight and marbling score in Japanese Black fattened steers, using genotype data of approximately 40,000 SNPs. Genotypes were imputed using equally spaced SNP subsets of different densities. Two different linear models were used. The first (model 1) incorporated one G matrix, while the second (model 2) used two different G matrices constructed using the selected and remaining SNPs. When using model 1, the estimated additive genetic variance was always larger when using all SNPs obtained via genotype imputation than when using only equally spaced SNP subsets. The correlations between the genomic estimated breeding values obtained using genotype imputation with at least 3,000 SNPs and those using all available SNPs without imputation were higher than 0.99 for both traits. While additive genetic variance was likely to be partitioned with model 2, it did not enhance the accuracy of GP compared with model 1. These results indicate that genotype imputation using an equally spaced low‐density panel of an appropriate size can be used to produce a cost‐effective, valid GP.     

Genetic variation affects de novo translocation frequency

Translocation is one of the most frequently occurring human chromosomal aberrations. The constitutional t(11;22)(q23;q11), which is the only known recurrent non-Robertsonian translocation, represents a good model for studying translocations in humans. Here we demonstrate polymorphisms of the palindromic sequence at the t(11;22) breakpoint that affect the frequency of de novo translocations in sperm from normal males. A typical allele consists of a perfect palindrome, producing ~10-5 de novo t(11;22) translocations. Alleles with an asymmetric center do not form the t(11;22). Our data show the importance of genome sequence on chromosomal rearrangements, a class of human mutation that is thought to be random.     

Effect of maturation culture period of oocytes on the sex ratio of in vitro fertilized bovine embryos

It has been suggested that the maturational stage of oocytes at time of insemination influences the sex ratio of resulting embryos. However, there are very few reports concerning the relationship between the maturation culture period of oocytes and the sex ratio of resulting embryos. The objective of this study was to investigate the effects of in vitro maturation culture period for bovine oocytes on the sex ratio of in vitro produced blastocysts using a novel technique of loop-mediated isothermal amplification (LAMP). Cumulus-oocyte complexes were collected from the ovaries of slaughtered cows, and then matured in vitro for various periods (16, 22, 28, and 34 h). After maturation culture for each period, the oocytes were inseminated with frozen-thawed spermatozoa, and then cultured in vitro. Blastocysts were harvested on Day 7 after insemination, and the sex of the embryos was examined using the LAMP method. The rates of oocytes matured to the metaphase II stage were significantly lower (P < 0.05) in the 16-h maturation group than in the other groups. The proportion of blastocyst formation after insemination was significantly higher (P < 0.05) in the 22-h maturation group than in the other groups. The proportion of male blastocysts increased with the increase in maturation culture period. The proportion of male blastocysts derived from oocytes matured for 34 h was significantly higher (P < 0.05) than from oocytes matured for 16 and 22 h. These results indicate that the sex ratio of in vitro fertilized embryos is apparently influenced by the maturation culture period of the oocytes.     

Prediction of Specific Japanese Sponge Cake Volume Using Pasting Properties of Flour

In Japanese soft wheat (Triticum aestivum L.) breeding programs, protein content (PC), and specific surface area (SSA) of flour have been used as important factors for the baking quality of Japanese sponge cake. We proposed batter pasting viscosity (BPV) as a parameter to predict the baking quality of Japanese sponge cake. BPV was measured using a Rapid Visco‐Analyser (RVA) with a modified heating profile. Twenty soft wheat samples from the 2006‐07 season and 22 from the 2007‐08 season, including Japanese soft wheat cultivars, advanced breeders' lines, and Western White (WW) imported from the United States, were milled and evaluated for solvent retention capacity (SRC) values of four solvents, batter pasting properties, flour pasting properties, PC, SSA, and specific cake volume (SCV) to investigate their relationships. BPV was the most strongly correlated of the parameters to SCV (r = –0.90, P < 0.001). Stepwise multiple regression analysis selected BPV and minimum viscosity (MV) of flour pasting as significant independent variables to predict SCV (corrected R² = 0.848). The variability in BPV related to cake batter expansion was highly explained by PC and sucrose SRC (corrected R² = 0.854, P < 0.001). MV was correlated to SSA (r = 0.56, P < 0.001) and might be related to the prevention of sponge cake shrinkage during baking.