Evaluation of Genetic Variation Among Wild Populations and Local Varieties of Rice

Cultivated rice (Oryza sativa L.) is derived from Asian wild rice (Oryza rufipogon Griff). Vietnamese local varieties and wild natural populations in Vietnam and Myanmar were examined to evaluate the levels of genetic variation in cultivated and wild rice. In total, 222 Vietnamese local varieties were analyzed with ten microsatellite markers. Using marker genotype and gene diversity data, the local varieties were differentiated based on geographical distribution, cropping season, and human preference. A total of 976 wild plants were collected at six natural sites of wild populations (three each in Myanmar and Vietnam), and the degrees of variation among populations were analyzed with five microsatellite markers. Phylogenetic analyses revealed wide genetic differentiation among wild populations. The diversity values detected in a single wild population in Vietnam were higher than those in whole Vietnamese local varieties. These results indicate that wild rice has much greater genetic variation than cultivated rice.     

An SNP caused loss of seed shattering during rice domestication

Loss of seed shattering was a key event in the domestication of major cereals. We revealed that the qSH1 gene, a major quantitative trait locus of seed shattering in rice, encodes a BEL1-type homeobox gene and demonstrated that a single-nucleotide polymorphism (SNP) in the 5' regulatory region of the qSH1 gene caused loss of seed shattering owing to the absence of abscission layer formation. Haplotype analysis and association analysis in various rice collections revealed that the SNP was highly associated with shattering among japonica subspecies of rice, implying that it was a target of artificial selection during rice domestication.     

Ghrelin in domestic animals: distribution in stomach and its possible role

Ghrelin, a novel growth-hormone-releasing acylated peptide, was recently isolated from rat and human stomachs. In rat, peripheral or central administration of ghrelin stimulates the secretion of growth hormone (GH) from the pituitary gland. Recent work suggests that ghrelin plays an important role in energy homeostasis, body weight, and food intake. We examined the distribution of cells immunoreactive to ghrelin in the stomachs of domestic animals and rats, using a polyclonal antibody for the N-terminal fragment of rat ghrelin [1-11]. We measured the plasma levels of ghrelin before and after feeding in cows, and GH levels after central administration of ghrelin in Shiba goats, to elucidate the possible role of ghrelin. Immunostained cells were widely distributed from the neck to the base of the oxyntic gland in all animals. The plasma ghrelin concentration in cows decreased significantly 1 h after feeding, and then recovered to pre-feeding levels. Administration of ghrelin into the third ventricle in Shiba goats dramatically increased the plasma GH concentration dose-dependently. These results suggest that ghrelin plays an important role in GH secretion and feeding regulation in domestic animals.     

Involvement of activin and inhibin in the regulation of food and water intake in the rat

The expression of activin and inhibin has been demonstrated in the hypothalamus, but their physiological roles in the brain remain to be elucidated. In the present study, involvement of activin and inhibin in the regulation of food and water intake was examined. Male rats were deprived of food or water for 12 and 60 hr, and mRNA levels of activin/inhibin alpha, betaA and betaB subunits in the hypothalamus were estimated by RT-PCR. Gene expression of alpha subunit transiently decreased at 12 hr of food deprivation, while it did not change during water deprivation. Food and water deprivation for 60 hr increased mRNA levels of betaA and betaB subunits, respectively. These results indicated that gene expression of each subunit was independently regulated. Injection of activin A (0.5 and 4.0 microg) into the third ventricle decreased food intake. Water intake was suppressed by 4.0 microg, but not 0.5 microg, of activin A. Intracerebroventricular injection of inhibin A (0.5 and 4.0 microg) decreased water intake in a dose dependent manner without affecting food intake, suggesting that inhibin could act independently of activin. Taken together, it is suggested that activin and inhibin take part in the central regulation of nutrient and fluid balance, though further study is needed to determine precise molecular species involved.     

Recruitment and movement of the hard clam Meretrix lusoria in a tidal river of northern Kyushu,Japan

Size-frequency distributions of Meretrix lusoria, a commercially important bivalve in Japan, were compared among 6 sites in tidal flats of a small river in Kafuri Bay, northern Kyushu, Japan during 2006–2008. In Kafuri Bay, the hard clam resource is strictly managed and mean biomass of this species on the fishing ground (about 1.5 km²) exceeded 1.5 kg m^?2 in 2008. Small clams (<5 mm in shell length, SL) were most abundant in the border area between the river and the sea, while large clams (>40 mm SL) were rare there. In contrast, in the lower site of the marine area (site L), most clams were >30 mm SL. These results indicate that small clams move from riverine to marine areas with growth (post-settlement movement). Year-round, very small clams (<1 mm SL) were present and clams that were 2–5 mm SL were very rare, although the spawning season is thought to occur in summer. Probably, the early growth of many new recruits is very slow and most may even be <1 mm SL in the next spring, although some clams grow to >5 mm SL in a short period of time.     

Suppressive effect of culture supernatant of erythrocytes and serum from dogs infected with Babesia gibsoni on the morphological maturation of canine reticulocytes in vitro

The present study evaluated the effects of infected culture supernatant of erythrocytes, fractionation of culture supernatant and serum from dogs infected with Babesia gibsoni (B. gibsoni) on the maturation of canine reticulocytes in vitro. The SDS-PAGE demonstrated that significantly broader bands were generated by both the infected culture supernatant of erythrocytes and the serum from dogs chronically infected with B. gibsoni. The culture supernatant of erythrocytes infected with B. gibsoni strongly suppressed the maturation of reticulocytes. Prior studies showed that chronically infected serum had inhibitory effects on both the maturation of reticulocytes and the canine pyrimidine 5''-nucleotidase subclass I and purine-specific 5''-nucleotidase activity. In addition, serum free infected culture supernatant of erythrocytes had an inhibitory effect on the morphological maturation of reticulocytes. These results suggest that infected serum and culture supernatant of erythrocytes might accumulate excess proteins and/or metabolites as a result of the inhibited maturation of reticulocytes and decreased activity of erythrocyte 5''-nucleotidase. Furthermore, the fractions observed at >150 kDa- and 150-70 kDa- in the infected culture supernatant and serum retarded the maturation of canine reticulocytes in vitro. The results obtained from the in vitro examinations, in the present study, suggested that B. gibsoni itself and/or its metabolites might release certain proteins in the infected culture supernatant and serum from infected dogs and as a result delay morphological maturation of canine reticulocytes.     

Genetic association between GHSR1a 5′UTR‐microsatellite and nt‐7(C>A) loci and growth and carcass traits in Japanese Black cattle

We carried out a genetic association study between five nucleotide polymorphisms (5′UTR microsatellite ((TG)_n), nt‐7(C>A), L24V, DelR242 and Intron 1 microsatellite) of the GHSR1a gene and growth and carcass traits in 1285 steers sired by 117 Japanese Black bulls in a progeny testing program. We report herein, a significant association between the 5′UTR microsatellite and nt‐7(C>A) loci and growth and carcass traits. We also propose a translational hypothesis that the association is due to differences in the secondary structure of GHSR1b mRNA (the non‐spliced type with the 5′UTR microsatellite) among the GHSR1a gene haplotypes. Furthermore, we predicted the potential increase in profitability due to increased carcass weight in cow‐calf fattening enterprises through planned matings based on DNA testing of the 5′UTR microsatellite. Statistical analysis revealed that the 5′UTR microsatellite locus had a significant additive effect on carcass weight (CW) and average daily gain (ADG), but not on beef marbling score (BMS). One of the four major microsatellite alleles (19‐TG allele) with an allele frequency of 0.145, had a significantly (P < 0.0007) desirable effect on CW and ADG. We concluded that the 19‐TG allele could potentially be economically useful nucleotide markers for growth and carcass traits in Japanese Black cattle.     

Grain qualities and their genetic derivation of 7 new rice for Africa (NERICA) varieties

NERICA are interspecific rice varieties from crossing between the high-yielding Asian rice ( Oryza sativa spp. Japonica) with locally adapted African rice ( Oryza glaberrima). In this study, we analyzed grain qualities of 7 NERICA varieties (NERICA 1 to 7) and genetic derivation of quality-related genes. Quality analyses of NERICA grains showed that 7 NERICA varieties were clearly classified into two groups based on the difference of amylose content, and the difference influenced the pasting and physical properties of grains. Genetic analysis of the gene encoding granule-bound starch synthase I (GBSSI), which is known as a key enzyme on amylose synthesis in rice grain, revealed that varieties with higher amylose content ( approximately 29%) have the gene derived from O. glaberrima parent, and group 2 with lower amylose content ( approximately 22%) have the gene from O. sativa parent. These results indicated that the difference in amylose content as well as grain properties among 7 NERICA varieties is mainly determined by the genetic derivation of GBSSI. Further genetic analysis of starch synthesis-related genes suggested that the genetic derivation of SSIIa also influences the chain length of amylopectin in 7 NERICA varieties.     

Drop of egg production in chickens by experimental infection with an avian metapneumovirus strain PLE8T1 derived from swollen head syndrome and the application to evaluate vaccine

Decreases in egg production and increased incidence of abnormal eggs due to malformation of egg shells were observed in specific pathogen free (SPF) 173-day-old laying hens inoculated intravenously with an avian metapneumovirus (aMPV) strain PLE8T1. This strain was derived from an isolate from broiler birds exhibiting swollen head syndrome (SHS). Some SPF birds inoculated with the virus showed, slight diarrhea without any respiratory symptoms. Thus, the PLE8T1 strain was used as a challenge virus to evaluate efficacy of aMPV vaccines. SPF chickens which received a live attenuated aMPV vaccine (NEMOVAC; Merial) at 7 or 77 days old and an inactivated aMPV vaccine (OVO-4; Merial) at 105 days old were protected against poor egg production caused by the challenge with the PLE8T1 strain. Thus, aMPV, the PLE8T1 strain passaged 22 times after isolation, from birds exhibiting SHS, could induce a drop in egg production in laying hens accompanied by malformation of egg shells. It was suggested that this challenge system could be applied to evaluate the efficacy of aMPV vaccine.