Effects of resveratrol treatment on mitochondria and subsequent embryonic development of bovine blastocysts cryopreserved by slow freezing

This study evaluated the effects of cryopreservation by slow freezing on the mitochondrial function, DNA integrity, and developmental ability of bovine embryos and examined whether resveratrol treatment of the frozen‐thawed blastocysts improved embryonic viability. In vitro produced bovine embryos were subjected to slow freezing. After thawing, the ATP content and mitochondrial DNA integrity (mtDNA), determined by real‐time PCR targeting short and long mitochondrial sequences, was found to be lower in frozen‐thawed embryos than in fresh embryos, and mtDNA copy number was significantly reduced during the 24‐hr incubation post warming. Furthermore, immunostaining against double‐strand DNA revealed DNA damage in frozen‐thawed embryos. When frozen‐thawed embryos were incubated in the medium containing 0.5 µM resveratrol, SIRT1 expression, and survival rate of the embryos significantly improved compared with the vehicle‐treated embryos. In addition, cell‐free mtDNA content in medium was higher in case of resveratrol‐treated embryos than of vehicle‐treated embryos. In conclusion, slow freezing affects mitochondrial integrity and function in the blastocysts. In the frozen‐thawed embryos, mitochondria were removed during post‐thawing incubation and resveratrol enhanced the process, resulting in improved survivability of the embryos.     

Parent‐of‐origin effects on carcass traits in Japanese Black cattle

Variances caused by the differential expression of paternally and maternally imprinted genes controlling carcass traits in Japanese Black cattle were estimated in this study. Data on marbling score (BMS), carcass weight, rib thickness, rib‐eye area (REA) and subcutaneous fat thickness (SFT) were collected from a total of 13,115 feedlot steers and heifers in a commercial population. A sire–maternal grandsire model was used to analyse the data, and then, imprinting parameters were derived by replacing the genetic effect of the dam with the effect of the maternal grandsire in the imprinting model to calculate the genetic parameter estimates. The proportions of the total genetic variance attributable to imprinted genes ranged from 8.7% (SFT) to 35.2% (BMS). The remarkably large imprinting variance of BMS was mainly contributed by maternally expressed inheritance because the maternal contribution of the trait was much larger than that of the paternal trait. The parent‐of‐origin effect originating from maternal gene expression was also observed for REA. The results suggested the existence of genomic imprinting effects on the traits of the Japanese Black cattle. Hence, the parent‐of‐origin effect should be considered for the genetic evaluation of Japanese Black cattle in breeding programmes.     

RFLPs of chloroplast and mitochondrial DNA in wild soybean, Glycine soja, growing in China

RFLPs of chloroplast (cp) and mitochondrial (mt) DNA have been used to characterize the cytoplasmic genome of wild soybean, Glycine soja, growing in China. We have found from the RFLPs of that the cytoplasmic genomes of most Chinese wild soybeans have a combination of cpIII with mt-a or a combination of cpII with mt-b accompanied by mtIV or mtV according to our classification. CpII was not observed in combination with mt-a and cpIII was not observed in combination with mt-b. The regional distribution of these two types showed clines with opposite directions. The Yangtze River Valley had the greatest diversity in each of cp and two mt profiles detected in this study and the cytoplasmic genome combining these three profiles showed the highest degree of polymorphism in this region. The Yangtze River Valley may be a center of cytoplasmic diversity of wild soybean and may contain various genetic resources of soybean.     

Effect of water temperature on the feeding activity and the resultant mercury levels in the muscle of cultured bluefin tuna Thunnus orientalis (Temminck and Schlegel)

Tuna muscle often contains high levels of mercury, and fish samples with mercury concentrations ten times higher than the specified safety standards have been reported. Here, we report on the relationship between water temperature and the concentration of mercury in the tail muscle tissue of cultured bluefin tuna Thunnus orientalis. The fish used in this study were cultured at Fisheries Laboratory of Kinki University (Amami Experimental Station, Kagoshima, Japan). One hundred fish weighing 26.2–89.4 kg were selected for analysis between February 2007 and January 2008. Water temperature during rearing ranged from 21 to 29 °C. The total mercury levels were measured using the reduction vaporizing atomic absorption method after acid digestion. Body weight increased approximately 1.5 times that observed in a previous study, despite feeding activity either being the same or less than that observed previously. The average mercury concentration in white muscle was 0.353 mg kg^?1, remaining almost constant and independent of body growth. Unlike previous studies, seasonality was not observed in this study. Based on these findings, water temperatures within a certain range were considered to stabilize feeding activity and increase feeding efficiency. Consequently, water temperature is considered to have a moderating effect on seasonal fluctuations in muscle mercury concentrations in cultured bluefin tuna.     

Effects of an Enterococcus faecium‐based probiotic on growth performance and health of Pirarucu,Arapaima gigas

Intensive fish farming has resulted in an increased concern for disease outbreaks. Probiotic use is one of the strategies being developed to improve fish health and productivity. Measures of probiotic colonization, growth performance, haematological characteristics and parasite load were used to evaluate the effect of diets supplemented with Enterococcus faecium on growth and health of Arapaima gigas juveniles. A completely randomized design with four treatments (diet with E. faecium at 1 × 10⁶ CFU/g and 1 × 10⁸ CFU/g, control diet and diet with the culture medium MRS) and three replicates was used. Ninety‐six Arapaima juveniles were distributed in 12 cages fed with the specified diet for 68 days. Colonization of the intestinal tract by lactic acid bacteria reduced the total number of heterotrophic bacteria in fish fed with probiotics compared to controls. Fish fed a supplemented diet containing 1 × 10⁸ CFU/g presented higher values of weight gain, survival and fish growth uniformity, and lower values of feed conversion ratio. The prevalence of Trichodina sp. could have affected the survival of fish in the control group. Reduction in parasite load and an increase in haematocrit, the number of erythrocytes, thrombocytes, neutrophils and monocytes were also observed in fish fed the diet containing 1 × 10⁸ CFU/g. Enterococcus faecium presented a probiotic effect in A. gigas juveniles and can be recommended for use at a concentration of 1 × 10⁸ CFU/g to modify the gut microbiota, improve growth performance and haematology and reduce parasitic load.     

Nonrandom distribution of chum salmon stocks in the Bering Sea and the North Pacific Ocean estimated using mitochondrial DNA microarray

More than 1,000 age-identified chum salmon Oncorhynchus keta collected at 23 stations in the Bering Sea and the North Pacific Ocean in June to July 2003 were used to estimate their origin of stocks using a DNA microarray developed for analyzing the mitochondrial (mt)DNA haplotypes. The observed haplotype distribution was nearly the same as that reported previously for fish collected in September 2002 and 2003 in the present surveyed areas. A conditional maximum-likelihood method for estimation of stock compositions indicated that the Japanese stocks mainly distributed in north central Bering Sea, whereas the Russian stocks were mainly in western Bering Sea. The North American stocks were abundant in eastern Bering Sea and around the Aleutian Islands. Such an area-specific stock composition was not significantly different between mature and immature fish. Thus, the combined results of 2 years suggest that the distribution of chum salmon is nonrandom in the surveyed areas in summer and autumn, and that fish of the same origin migrate together to the same area irrespective of age.     

Temperature characteristics in seed germination and growth of <Emphasis Type="Italic">Zostera japonica</Emphasis> Ascherson &; Graebner from Ago Bay,Mie Prefecture,central Japan

The optimal water temperature in seed germination and the upper critical water temperature in seedling growth were determined for Zostera japonica collected from Ago Bay, Japan. The relationship between the seed germination rates and seed storage period (0, 30, and 60 days) at 0°C was also examined. The optimal water temperature in seed germination was in the range 15–20°C regardless of the storage period, in which germination rates were up to 14%. Seedlings, grown from seeds up to 10 cm in total length, were cultured for 1 week at various water temperatures to measure their relative growth rates. The optimal water temperature in early growth was in the range 20–25°C; relative growth rates ranged from 3.8 to 4.2%. Seedlings could survive up to a water temperature of 29°C, but most seedlings withered at 30 or 35°C. The optimal water temperatures for seed germination and seedling growth were related to the seasonal changes of water temperature in the sampling site. Although seedlings were hardly observed in Ago Bay in summer, Z. japonica might extend its distribution as far as where the summer water temperature is lower than 29°C.     

First report of ‘<Emphasis Type="Italic">Candidatus</Emphasis> Phytoplasma malaysianum’ associated with <Emphasis Type="Italic">Elaeocarpus</Emphasis> yellows of <Emphasis Type="Italic">Elaeocarpus zollingeri</Emphasis>

“Elaeocarpus yellows” (ELY) is a widely reported phytoplasma disease of Elaeocarpus zollingeri trees in Japan. The phytoplasma associated with ELY (ELY phytoplasma) had not been identified at the species level because its 16S rRNA sequence had yet to be reported. Here, we report the results of a sequence analysis based on 16S rRNA and secA gene sequences, which showed that the ELY phytoplasma is related to ‘Candidatus Phytoplasma malaysianum’. To our knowledge, this is the first report showing the occurrence of ‘Ca. P. malaysianum’ outside Malaysia and the infection of E. zollingeri by the phytoplasma.     

Assessing Silicon Availability in Soils of Rice-Growing Lowlands and Neighboring Uplands in Benin and Nigeria

Silicon(Si) is known as a beneficial nutrient in the cultivation of rice, playing a key role in photosynthesis enhancement, lodging resistance and tolerance to various environmental stress. The present study aimed to examine available Si content in both lowland soils(n = 29) and neighboring upland soils(n = 21) collected from Benin and Nigeria and to evaluate the validity of the assessment results through a pot experiment. Our results revealed that the acetate-buffer method predicted Si concentration in rice straw at the harvest stage(R~2 = 0.68, P < 0.01) better than the anaerobic-incubation method(R2 = 0.31, P > 0.05), and 76% of the uplands and 38% of the lowlands were deficient(< 50 mg/kg) in acetate-buffer soluble Si. These findings suggest that the Si-deficiency soils prevail across the study area, making rice plants starved for Si and prone to environmental stress.