Relationships between the first ovulation postpartum and polymorphism in genes relating to function of immunity, metabolism and reproduction in high-producing dairy cows

The decrease in fertility and conception rates of high-producing dairy cows is one of the major negative impacts for today's producers. The recovery of ovarian activity postpartum is affected by the status of immunity, metabolism and reproduction and plays a critical role in subsequent fertility after parturition in the cow. In the present study we investigated the relationships between polymorphisms in genes relating to the above functions and the first postpartum ovulation as a marker of the recovery of ovarian function in the cow. In immune function related-factors, the occurrence of first postpartum ovulation within 3 weeks in the C/C genotypes of tumor necrosis factor α (TNFα) exon (55.4%) and the A/G genotypes of TNFα promoter (55.4%) was significantly higher than that in T/T genotypes of TNFα exon (14.3%) and A/A genotypes of TNFα promoter (14.3%). Moreover, anovulatory cows with the T/T genotype of TNFα exon and the A/A genotype of TNFα promoter tended to have a prolonged days open compared with those of the other genotypes of TNFα polymorphisms. In metabolic function-related factors, ovulatory and anovulatory cows had a different distribution for alleles of the growth hormone receptor, but there were no significant differences in genotype and allele frequency of insulin-like growth factor-I polymorphism. No significant relationships were found between ovarian function after parturition and polymorphisms for reproduction-related genes. In conclusion, polymorphisms of TNFα gene both in exon and promoter regions have a strong association with the early first ovulation within 3 weeks after parturition in the high-producing dairy cow. Taken together, polymorphisms of TNFα gene could be strongly related to early first ovulation after parturition, thus being an effective tool of selection for improving reproductive performance in the high-producing dairy cow.     

Multiple taste functions of the umami substances in muscle extracts of yellowtail and bastard halibut

Boiled muscle extracts obtained from yellowtail Seriola quinqueradiata and bastard halibut Paralichthys olivaceus were treated with two kinds of purified enzymes (acid phosphatase and glutamate decarboxylase), and the change in contents of nucleotides, related compounds, and free amino acids was examined. The change in taste qualities was also investigated by a taste test. The enzyme treatment resulted in a marked decrease in the contents of such umami substances as inosine 5′-monophosphate (IMP) and glutamic acid (Glu). The taste test revealed that the treatment of these fish muscle extracts with both or either of the enzymes caused a sharp decrease in umami intensity and also an increase in sourness but not a change in pH. The treatment also effected marked decreases in thickness and overall taste intensity. These findings suggest that IMP and Glu function not only to intensify the thickness and overall taste as well as the umami, but also to repress the sourness sensation elicited by the fish muscle extracts.     

Multiple copies of <Emphasis Type="Italic">AMT2</Emphasis> are prerequisite for the apple pathotype of <Emphasis Type="Italic">Alternaria alternata</Emphasis> to produce enough AM-toxin for expressing pathogenicity

The apple pathotype of Alternaria alternata produces the cyclic depsipeptide AM-toxin and causes Alternaria blotch of apple. Previously, we cloned AMT2 from the apple pathotype as an orthologue of AFTS1, which is required for biosynthesis of the decatrienoic acid ester AF-toxin I of the strawberry pathotype. These genes were predicted to encode aldo-keto reductases involved in biosynthesis of a common precursor, 2-hydroxy-isovaleric acid, of AF-toxin I and AM-toxin. In this study, we analyzed the function of AMT2 in AM-toxin biosynthesis in the apple pathotype. DNA gel blot analysis of the apple pathotype strain IFO8984 with five restriction enzymes suggested that this strain has a single copy of AMT2 in the genome. However, gene disruption experiments showed that IFO8984 probably has three copies of AMT2. We made mutants having one or two copies of AMT2 disrupted. The single-copy mutants produced less AM-toxin than did the wild type and were still as pathogenic as the wild type. The two-copy mutants produced trace or undetectable amounts of AM-toxin and were markedly reduced in pathogenicity. Thus, AMT2 was verified to be required for AM-toxin biosynthesis and hence pathogenicity. The fact that the two-copy mutants have a remaining copy of AMT2 suggests that multiple copies of AMT2 are prerequisite for the pathogen to produce enough AM-toxin for full pathogenicity.     

Utilization of genetically modified soybean meal in Nile tilapia <Emphasis Type="Italic">Oreochromis niloticus</Emphasis> diets

The utilization of genetically modified soybean meal (GM SBM) was compared with that of non-GM SBM in Nile tilapia. Four experimental diets were formulated to include either non-GM or GM SBM at 34 or 48%, respectively. These diets were fed to juvenile Nile tilapia (49.5 g average weight) for 12 weeks. The uptake of the cauliflower mosaic virus 35S promoter fragment of the GM SBM in fish muscle was examined at 8th and 12th week. After 12th week, fish were fed the non-GM SBM diets to determine the residual span of the incorporated promoter fragment. There was no significant difference in specific growth rate or feed efficiency between GM and non-GM groups at the same inclusion level. A small number of muscles from fish receiving both levels of GM SBM diet were positive for the promoter fragment. Additionally, the promoter fragment was not detected by the second day after changing to the non-GM SBM diets. These results indicate that the utilization of GM SBM was similar to that of non-GM SBM and the promoter fragment was rarely found in fish muscles, suggesting that suitability and safety of GM SBM in Nile tilapia diet were similar to those of non-GM SBM.     

High-resolution linkage mapping of the rat hooded locus

To identify a gene responsible for the hooded phenotype in the rat, high-resolution linkage mapping for the hooded locus was performed using IS (non-hooded) and LEA (hooded) rats. The map revealed that only Kit gene existed in the critical region, suggesting that the Kit is a strong candidate gene. However, mutation was not found in the coding region of the LEA rat Kit gene. Further, the expressions of Kit mRNA were not different in fetal neural tubes and both neonatal and adult skins between IS and LEA rats. Furthermore, Kit-positive cells, possibly melanocytes, were found in the non-pigmented hair follicles of hooded phenotype rats. Several hypotheses are conceivable to account for mechanisms in the appearance of hooded phenotype.     

Age estimation of Antarctic minke whales <Emphasis Type="Italic">Balaenoptera bonaerensis</Emphasis> based on aspartic acid racemization technique

Counting of the growth layers in the earplugs is the most accepted technique for determining chronological age of Antarctic minke whales; however, unreadable growth layers form in some individuals, especially in young animals. In this study, aspartic acid racemization (AAR) technique was developed for estimating ages in this species with the aim of complementing the age estimated using earplugs. To validate the technique and to determine the specific coefficients for age estimation, the ratio of d and l-enantiomers of aspartic acid (Asp D/L) in lens of 18 whales and 20 fetuses were analyzed and compared with earplug-based age estimates. The equation for age estimation by AAR in this species was as follows: Log_e{[1 + (Asp D/L)_act]/[1 ? (Asp D/L)_act]} = 2.30 × 10^?3 × earplug age (year) + 0.0201 (p < 0.001, r ²  = 0.918). There is a strong correlation between the age estimates by AAR and earplugs. This study was successful in developing the AAR technique for the Antarctic minke whale, and the application of this technique can complement the age estimation of this species based on earplug readings, especially for young animals with unreadable earplugs.     

High susceptibility of Djungarian hamsters (Phodopus sungorus) to the infection with Babesia microti supported by hemodynamics

As the comparative study was carried out on the susceptibility by the pursuit of parasitemia among the Djungarian, Syrian, and Chinese hamsters as well as BALB/c mice infected with the Syrian hamster-adapted Babesia microti strain, and Djungarian hamsters showed the highest parasitemia among them. Then, the other hematological parameters were pursued in the Djungarian hamsters infected with the hamster-adapted B. microti strain. Remarkable symptoms observed were hemoglobinuria clinically, anemia hematologically, and splenomegaly macroscopically during all over the observation period for 24 weeks post infection (PI). Parasitemia began to rise at 2 weeks and peaked at 4 weeks PI. After that, parasitemia decreased gradually but was maintained with a level of about 10% on average until 24 weeks PI at the end of the experiment. A decrease in the RBC count, Hb, and PCV, and an increase in the reticulocyte and WBC counts due to the development of immature neutrophils, lymphocytes and monocytes were recognized together with a rise of parasitemia. The hamsters had macrocytic hypochromic anemia due to the increase of MCV and the decrease of MCHC in the growth phase of the parasite. It was considered that the Djungarian hamsters will be useful for the infection examination, isolation, maintenance, and passage of B. microti in laboratory.     

Microbial mineralization of organic matter in sinking particles,bottom sediments and seawater in a coastal fish culturing area

Microbial mineralization rates in sinking particles, bottom sediments and seawater were determined in a coastal fish (red sea bream Pagrus major) culturing area to clarify the mineralization process of organic matter (OM) in the entire water column. The mineralization rates of ¹⁴C‐labelled glutamate and glucose per unit volume were highest in the sinking particles and were 131–572 and 7–49 times higher than those of the seawater and bottom sediments respectively. The turnover time of glutamate tended to be shorter than that of glucose at all three sites of the water column. Bacteria appeared to prefer amino acids to monosaccharides because amino acids could be utilized as both energy and nitrogen sources. The sedimentation rate of particulate organic carbon (POC) derived from phytoplankton accounted for 9–61% of the total POC, and it was particularly high in early summer (61% and 50% at fish cage and non‐cage stations respectively). The present study clearly shows that sinking particles serve as an important site of microbial mineralization process of OM within the water column, and that phytoplankton production was another serious cause of organic pollution of the seafloor in addition to the organic wastes directly discharged from fish farms.     

Vitrification of fully grown and growing porcine oocytes using germinal vesicle transfer

The survival rate of vitrified germinal vesicle (GV) stage porcine oocytes is very low, and it is not known if the vitrification damages the nucleus, cytoplasm or both. We have evaluated the eventual GV or cytoplasmic damage in fully grown (FG) and growing vitrified oocytes. Fifty-five percent of nonvitrified FG cumulus-denuded oocytes reached the metaphase II (MII) stage in culture. When growing oocytes from preantral (PA) and early antral (EA) follicles were matured in vitro, almost all oocytes were arrested at the GV stage (GV stage: PA 88.9 and EA 79.5%, respectively). When fresh GVs from FG, PA and EA oocytes were transferred into fresh enucleated FG oocytes and matured in vitro, some of them reached the MII stage (MII stage: FG/FG 57.5%, PA/FG 9.3% and EA/FG 35.3%, respectively). The maturation rate of vitrified FG oocytes was only 6.1% but increased dramatically when vitrified GVs from FG, PA and EA oocytes were transferred into fresh enucleated FG oocytes (MII stage: VitFG/FG 43.9%, VitPA/FG 7.1% and VitEA/FG 26.3%, respectively). These results were not significantly different from those for the nonvitrified groups (MII stage: FG/FG 57.5%, PA/FG 9.3% and EA/FG 35.3%, respectively). We activated the reconstructed oocytes that received fresh or vitrified GVs (FG/FG, EA/FG, VitFG/FG and VitEA/FG) and examined their embryonic development. Cleaved embryos (nonvitrified groups 13.0-61.8%, vitrified groups 33.3-40.0%) and blastocysts (nonvitrified groups 0.0-18.2%, vitrified groups 0.0-2.9%) were obtained after activation. These results demonstrate that vitrified porcine GVs maintain maturational and developmental competence and that vitrification predominantly damages the cytoplasm.