Migration and differentiation of gonadal germ cells under cross-sex germline chimeras condition in domestic chickens

A series of experiments was conducted to investigate migration, proliferation and differentiation of gonadal germ cells (GGCs) collected from the gonads of 7-day-old chick embryos under cross-sex germline chimera conditions. The migratory and proliferative abilities of exogenous GGCs were examined by transferring 50 fluorescently labeled GGCs collected from White Leghorn (WL) embryos into the blood of 2-day-old Rhode Island Red (RIR) embryos. No significant difference was observed in the number of fluorescently labeled GGCs in the gonads of recipient embryos among any of the four possible donor and recipient sex combinations. Cross-sex germline chimeras were produced to examine the differentiation of GGCs by transferring 100 GGCs from WL embryos into 2-day-old RIR embryos. Exogenous-GGC-derived progeny were obtained from both male and female recipients, except when female GGCs were transferred into male recipients. The migratory ability of GGCs recovered from the 7-day-old embryonic gonad was not influenced by cross-sex germ cell transfer conditions, whereas the differentiation of the GGCs was affected by the sex combinations of GGCs donors and recipients.     

Expression and regulation of Foxa2 in the rat uterus during early pregnancy

The forkhead box a (Foxa) protein family has been found to play important roles in mammals. Recently, the expression of Foxa2 was reported in the mouse uterus, and it was reported to be involved in regulation of implantation. However, the regulation of Foxa2 expression in the uterus is still poorly understood. Therefore, the present study was conducted to investigate the expressional profiles of Foxa2 in the rat uterus during the estrus cycle and pregnancy. Furthermore, the effect of steroid hormones and Hedgehog protein on the expression of Foxa2 was analyzed in vivo and in vitro. In this study, the level of expression of Foxa2 was low in the rat uterus during the different stages of the estrus cycle. However, the expression increased transiently during early pregnancy at 3.5 days post coitus (dpc) and decreased at 5.5 dpc. In ovariectomized rats, P4 treatment had no effect on the expression of Foxa2 compared with the expression in control animals. Moreover, the expression of Foxa2 in cultured epithelial cells was not increased by P4 treatment in vitro. However, Foxa2 expression was significantly decreased in the rat uterus after 24 h of E2 treatment. Treatment of cells with a recombinant Hedgehog protein significantly increased the expression of Foxa2. These results suggest that the expression of Foxa2 may transiently increase just before the implantation and it may be regulated by E2 and Hedgehog protein.     

Unchanged Distribution Density of Anionic Sites on the Glomerular Wall in Rats with Active Heymann Nephritis

In various kinds of glomerulonephritis, alteration of anionic charge on the glomerular basement membrane (GBM) and podocytes has been controversial for more than decade. To elucidate the relation between glomerular protein leakage and anionic sites on the glomerular wall, we examined the distribution of anionic sites on the GBM and podocytes of rats with active Heymann nephritis (AHN). Urinalysis for protein levels was conducted, and the kidneys were examined using electron microscopic cytochemistry for the assessment of anionic charge with two cationic probes. The anionic sites on podocytes were decreased in number in the AHN rats; however, the distributions of anionic sites on the GBM were similar in density to those seen in the control animals. From these results, we consider that the decrease in anionic charge density on podocytes might be attributable to protein leakage and that the charge barrier of the GBM is irrelevant to the protein leakage in AHN rats.     

日本水稻生产的发展和新课题

在过去的125a的时间里,日本的水稻种植面积和产量发生了巨大的变化。结果显示,水稻耕作面积自1883年开始逐渐增加,二战前后一度有所减少,20世纪60年代后又有所增加,1969年达到史上最高峰,1970年后持续减少。而水稻产量呈现了不断递增的趋势,现在维持在900万如左右。20世纪70年代前后,由于人均稻米消费量的减少,优质食味水稻育种及栽培成为主导方向,仅越光、一见钟情、日之光、秋田小町4个品种就占水稻全部种植面积的66％。此外,随着大气变暖造成稻米品质的下降,耐高温品种的选育和栽培研究得到广泛开展,并取得了一定的成果。当前,除了水稻食味研究以外,正朝着饲料用、米粉用和生物能源用的“新型需要稻”和水稻节水等多方向发展。本文通过阐述日本水稻生产的发展和方向,对确立中国今后的水稻育种及栽培研究目标具有参考意义。     

Predation on glass eels of Japanese eel <Emphasis Type="Italic">Anguilla japonica</Emphasis> in the Tone River Estuary,Japan

Aquaculture of Japanese eel Anguilla japonica relies upon the natural recruitment of their glass eels (juveniles); however, predation that could influence glass eel recruitment remains unknown. In the present study, we aimed to elucidate the proportion of predation on A. japonica glass eels through stomach content analysis of predatory fishes collected in the estuary region of the Tone River system and its vicinity in Japan. Species of the predated glass eels were identified by DNA barcoding. A total of 270 predatory fishes of 15 taxa was collected over 2 years. The overall proportion of predation on glass eels, genetically identified as Japanese eel, was 0.7%, but this rose to 2.0% when data were limited to fishes caught during the peak months of glass eel recruitment. A glass eel was found in the stomach contents of a channel catfish Ictalurus punctatus, an invasive species in this river system, and a blackfin sea bass Lateolabrax latus. These fishes are therefore considered potential predators of A. japonica glass eels. However, as the proportion of predation was low, and the glass eels represented only small proportions of predator stomach contents, further investigation is needed for a better understanding of predation on A. japonica glass eels, and its effects on the early life stages of this endangered species.     

Molecular Monitoring of the Main Changes in Bacterial Floral Diversity in the Gastrointestinal Tract of a Thoroughbred Foal with Catarrhal Enteritis by Using PCR-DGGE

In this study, the main changes in bacterial floral diversity in the gastrointestinal tract of a Thoroughbred foal were monitored by using polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE). The foal died of catarrhal enteritis of the cecum and large colon. Diarrheal feces and gastrointestinal contents were compared with normal feces. The closest relatives of the bacterium in the samples were Lactobacillus johnsonii (100% similarity), uncultured Bacteroides sp. (92.5% similarity), Bacteroides fragilis (96.3% similarity), and Enterococcus faecium/Enterococcus durans (100% similarity); these were detected by PCR-DGGE using a universal primer set. Monitoring revealed that the numbers of Escherichia coli/Shigella sonnei (97.9% similarity) were significantly higher in the diarrheal feces. Thus, PCR-DGGE is a useful tool for monitoring the main changes in bacterial floral diversity occurring in the gastrointestinal tracts of Thoroughbreds.     

Sex differences in stress responses to transportation in goats: Effects of gonadal hormones

The present study examined sex differences and the involvement of gonadal hormones in stress responses caused by road transportation in Shiba goats. In experiment 1, we investigated the stress responses of males and females to transportation. Plasma levels of cortisol (Cor) significantly increased during 1 h of transportation, and those in females were significantly higher than those in males. Plasma glucose (Glu) and free fatty acid (FFA) levels also increased similarly in both females and males by transportation, and there were no sex differences. Food intake following transportation decreased only in males compared with that in the basal session, in which the animals were not transported. Experiment 2 examined the involvement of gonadal hormones in stress responses to transportation using castrated males. Goats were given cholesterol (Cho), 5α‐dihydrotestosterone (DHT) or 17β‐estradiol (Es). The plasma Cor levels increased during transportation regardless of hormone treatment, and those in DHT treated goats were significantly lower than those in Cho or Es treated animals. Plasma Glu and FFA levels also increased during transportation, regardless of hormone treatment, and there were no differences between treatments. Food intake following transportation was significantly lower than that in the basal session only in goats given DHT. In conclusion, gender affects Cor secretion that is increased by transportation and the decrease of food intake following transportation in Shiba goats, and the major cause of these differences is androgen.     

Structural differences between myofibrillar protein,paratropomyosin, and tropomyosin as revealed by high‐performance liquid chromatography

Paratropomyosin (PTM) composes myofibril functions to weaken the rigor linkages formed between actin and myosin during postmortem aging of muscles. PTM has the similar physico‐chemical properties as tropomyosin (TM) that is a regulatory protein of myofibrils. So far, it is unclear whether PTM is definitely different from TM, because the primary structure of PTM has not been determined yet. The aim of this study was to clarify structural difference of PTM from TM. PTM was prepared by column chromatography immediately after slaughter from broiler breast muscle, and purified by high‐performance liquid chromatography (HPLC). Purified PTM was successfully separated from TM, and the recovered PTM molecule was reduced with dithiothreitol to separate again by HPLC. Two subunits were obtained and peptides from each digested subunit by V8 protease were recovered by HPLC, and then amino acid sequences of the peptides were analyzed by protein sequencing. As a result, some amino acid residues were replaced from that of TMα1 isoform which is the major isoform of TM, and also was different between the two subunits. Therefore, it is concluded that PTM clearly differs from TM and it is suggested that functional difference in PTM from TM is attributed to amino acid replacements in subunits composing PTM.