Impacts of perforated sheet pipe installation on some paddy soil properties

Paddy and Water Environment - Today, the world’s vision emphasizes the development of climate-adaptive agriculture for food security and provision of water with safe technology. Under extreme...     

Microsatellite multiplex panels for population genetic analysis of red sea bream <Emphasis Type="Italic">Pagrus major</Emphasis>

In this study, multiplex PCR panels were developed to amplify 20 microsatellite markers for red sea bream, Pagrus major, with the aim of reducing labor and material costs associated with genetic analysis of this species. The usefulness of these panels was validated in 200 fish collected at five sampling locations. The occurrence of null alleles was suggested at five markers, which were dropped from further analysis. The remaining 15 microsatellite loci showed high levels of heterozygosity (H _E range 0.34–0.97, H _O range 0.32–1) and a wide range in the number of alleles per locus (A; range 5–46). Increasing the number of microsatellite loci from three to ten and 15 improved the performance of the panels for population differentiation (F _ST) and estimation of Nei’s (D _S) genetic distance. The results of this study confirm the usefulness of genotyping a large number of microsatellite DNA markers to expand our knowledge of red sea bream population genetics.     

Line thinning promotes stand growth and understory diversity in Japanese cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis> D. Don) plantations

We studied the effects of line thinning on stand structure, microclimate and understory species diversity of two Cryptomeria japonica D. Don plantations in south-central Japan. In each of two study sites we compared stand structure between the thinned stand and an adjacent unthinned stand and found that line thinning increased the growth rate of residual trees such that stand basal area may recover within 10 years after thinning. In the thinned stand, more open canopy conditions resulted in higher maximum temperatures on the forest floor during the early growing season than in the unthinned stand. The thinned stand had greater understory plant species richness and biomass than the unthinned stand. This study suggested that line thinning could potentially enhance biodiversity while simultaneously increasing tree-growth rates in overstocked Cryptomeria japonica plantations.     

Lectin Histochemical Analysis of the Olfactory Bulbs in the Barfin Flounder (Verasper moseri)

Several lines of evidence have shown that the olfactory system of the fish contains the main and accessory olfactory systems. However, morphological data indicate that the accessory olfactory bulb, the primary centre for the accessory olfactory system, will not differentiate in the fish. Therefore, the fish olfactory bulb is supposed to engage in both main and accessory olfactory systems. To examine this possibility, we investigated the olfactory bulb of the barfin flounder ( Verasper moseri ) by histochemical examination using lectins. The olfactory bulb of the barfin flounder showed a laminar structure with four layers, and diffuse glomerular architecture was observed in the glomerular layer. Based on the expression patterns of sugar residues, the glomerular layer of the barfin olfactory bulb was largely divided into three portions. Heterogeneity in the lectin-binding pattern among olfactory glomeruli was clearly demonstrated by the fluorescent double-lectin staining. The results of this study suggest that the fish olfactory bulb contains both regions equivalent to the main and accessory olfactory bulbs, and they are subdivided into small subsets with different functions.     

Effects of vitamin A deficiency on the function of pituitary-gonadal system in male rats

The effects of vitamin A deficiency on the pituitary-gonadal function were examined by measurements of serum and pituitary level of pituitary hormones and serum testosterone concentration, and by investigations of histological changes in the testis and the pituitary gland in vitamin A-deficient (VAD) and supplemented (VAS) rats. The growth of VAD rats was retarded and their body weights were decreased after 9 weeks of experiments and attained about one half of the weight of control animals at 12 weeks. In the VAD rats, serum testosterone concentrations were decreased significantly compared with those in the VAS controls. Serum and pituitary concentrations of GH were significantly lower but those of LH were slightly lower in the VAD rats than those in the controls, while the serum FSH concentration was significantly higher than that in the control rats. The seminiferous tubules in the testes of VAD rats were comprised largely of Sertoli cells and a reduced number of spermatogonia and contained fibrous formation in their lumen. In the pituitary gland, GH cells were significantly reduced in number in the VAD rats, but gonadotropic (GTH) cells were increased remarkably in size and number, showing hypertrophy and vacuolation similar to those in castration cells. The cytological changes in the pituitary gland and the increased discharge of FSH represent a secondary and compensatory change similar to that seen following castration and vitamin E deficiency.     

The roles of vitamin A for cytoplasmic maturation of bovine oocytes

Vitamin A is one of the micronutrients which have been implicated in cattle reproduction. In cattle, ingested vitamin A, mainly as beta-carotene (BC) from forages and retinol ester from formula feed, is metabolized and transported to the oocytes and cumulus-granulosa cells in ovarian follicles through binding to various interacting molecules. The active form of vitamin A, retinoic acid (RA), functions as a regulator of gene expression in these targets. Early research showed the positive effects of vitamin A supplementation on bovine fertility in artificial insemination, and several studies on effects of vitamin A metabolites used in other artificial reproductive techniques (ART), including superovulation, ovum pick up, and in vitro maturation culture have provided evidence for the specific roles of vitamin A in oocyte cytoplasmic maturation (acquisition of developmental competence of oocytes during their meiotic maturation period for the embryonic development after fertilization). BC may enhance cytoplasmic maturation by its antioxidant properties which cannot be replaced by RA. Furthermore, RA may promote cytoplasmic maturation of bovine oocytes via its modulatory effects on the gene expression of gonadotrophin receptors, midkine, cyclooxygenase-2, and nitric oxide synthase in cumulus-granulosa cells.     

Tetraploid cells of enhanced green fluorescent protein transgenic mice in tetraploid/diploid-chimeric embryos

We succeeded in noninvasively analyzing the distribution of tetraploid (4n) cells in tetraploid<-->diploid (4n<-->2n) chimeric embryos by using enhanced green fluorescent protein (EGFP) transgenic (Tg) mouse embryos. We also evaluated whether this technique of analyzing 4n-cells in EGFP Tg 4n<-->2n chimeric embryos could be used to determine which characteristics of 4n-cells cause the death of 4n-embryos and restricted distribution of 4n-cells in 4n<-->2n-chimeric embryos after implantation. In our experiments, the distribution of 4n-cells in 4n<-->2n-embryos was normal until an embryonic age of 3.5 days (E3.5). With respect to morphological development, there were no differences between 4n-, diploid (2n), 4n<-->2n-, and diploid/diploid (2n<-->2n) chimeric embryos, but the number of cells in the tetraploid (4n) blastocyst was smaller than expected. This decrease in the number of cells may have caused cell death or reduced the rate of cell division in 4n-cells, and may have restricted the distribution of 4n-cells in 4n<-->2n-chimeric embryos. This study demonstrated the utility of EGFP transgenic mouse embryos for relatively easy and noninvasive study of the sequential distribution of cells in chimeric embryos.     

Testicular atrophy after bile duct ligation in chickens

Testicular atrophy associated with biliary obstruction in chickens, produced by the ligation of both extrahepatic bile ducts, was examined grossly, histologically, immunohistochemically, and ultrastructurally. Grossly, reduction in testicular size and volume was evident in chickens that underwent bile duct ligation (BDL). Histologically, there was marked reduction in tubular diameter, peritubular fibrosis, loss of spermatogenic cells, and tubules lined only by Sertoli cells. In addition, Leydig cells, which accumulated in the interstitium of the testes, contained numerous large lipid vacuoles, as determined by electron microscopy. These features suggest that BDL in chickens causes hypogonadism and low serum testosterone.     

Sequence comparison of the ORF 7 region of transmissible gastroenteritis viruses isolated in Japan

The 3' end region nucleotide sequence, including ORF7, of nine Japanese and two U.S.A. isolates of transmissible gastroenteritis virus (TGEV) were determined and compared. Nine Japanese TGEV strains have been isolated over the past 40 years (1956-1997). From the comparison of determined nucleotide sequences, we could divide the TGEV Japanese isolates into two groups and distinguish them from TGEV U.S.A. isolates.