KISS1 Gene Expression in the Developing Brain of Female Pigs in Pre- and Peripubertal Periods

Puberty is associated with an increase in gonadotropin secretion as a result of an increase in gonadotropin-releasing hormone (GnRH) secretion. Kisspeptin is considered to play a key role in puberty onset in many mammalian species, including rodents, ruminants and primates. The present study aimed to determine if changes in hypothalamic expression of the KISS1 gene, encoding kisspeptin, are associated with the onset of puberty in pigs. The animals (n=4 in each group) were perfused with 4% paraformaldehyde at 0, 1, 2, 3 and 4 months old, as prepubertal stages, and at 5 months old, as the peripubertal stage, following each blood sampling. KISS1 gene expressions in coronal sections of brains were visualized by in situ hybridization. Plasma luteinizing hormone (LH) was measured by radioimmunoassay. KISS1 mRNA signals were observed in the arcuate nucleus (ARC) at all ages examined without any significant difference in the number of KISS1-expressing cells, indicating that the KISS1 gene is constantly expressed in the ARC throughout pubertal development in pigs. The plasma LH concentration was the highest in 0-month-old piglets and significantly decreased in the 1- and 2 month-old groups (P<0.05), suggesting a developing negative feedback mechanism affecting gonadotropin release during the prepubertal period. Considering the potent stimulating effect of kisspeptin on gonadotropin release in prepubertal pigs, kisspeptin secretion rather than kisspeptin synthesis may be responsible for the onset of puberty in pigs.     

Chronic Peripheral Administration of Kappa-Opioid Receptor Antagonist Advances Puberty Onset Associated with Acceleration of Pulsatile Luteinizing Hormone Secretion in Female Rats

Puberty in mammals is timed by an increase in gonadotropin-releasing hormone (GnRH) secretion. Previous studies have shown involvement of the two neuropeptides, kisspeptin and neurokinin B (NKB), in controlling puberty onset. Little is known about the role of the other key neuropeptide, dynorphin, in controlling puberty onset, although these three neuropeptides colocalize in the arcuate kisspeptin neurons. The arcuate kisspeptin neuron, which is also referred to as the KNDy neuron, has recently been considered to play a role as an intrinsic source of the GnRH pulse generator. The present study aimed to determine if attenuation of inhibitory dynorphin-kappa-opioid receptor (KOR) signaling triggers the initiation of puberty in normal developing female rats. The present study also determined if stimulatory NKB-neurokinin 3 receptor (NK3R) signaling advances puberty onset. Female Wistar-Imamichi rats were weaned and intraperitoneally implanted with osmotic minipumps filled with nor-binaltorphimine (nor-BNI), a KOR antagonist, or senktide, a NK3R agonist, at 20 days of age. Fourteen days of intraperitoneal infusion of nor-BNI or senktide advanced puberty onset, manifested as vaginal opening and the first vaginal estrus in female rats. Frequent blood sampling showed that nor-BNI significantly increased luteinizing hormone (LH) pulse frequency at 29 days of age compared with vehicle-treated controls. Senktide tended to increase this frequency, but its effect was not statistically significant. The present results suggest that the inhibitory input of dynorphin-KOR signaling plays a role in the prepubertal restraint of GnRH/LH secretion in normal developing female rats and that attenuation of dynorphin-KOR signaling and increase in NKB-NK3R signaling trigger the onset of puberty in female rats.     

Effects of intramuscular fat deposition on the beef traits of Japanese Black steers (Wagyu)

Effects of intramuscular fat deposition on the chemical composition, tenderness, and free amino acids (FAA) concentration of beef were studied using various classified carcasses of 21 Japanese Black (Wagyu) steers. The Beef Marbling Standard (BMS) No., judged on the market in 1998, and fat content, ranged from 2 to 10 and 4.8 to 39.0% in the M. longissimus thoracis, respectively. Moisture content was negatively correlated with the fat content (r =?0.98, P < 0.01). In contrast, protein content was relatively constant up to approximately 23% fat, corresponding to BMS No.4, and decreased as the fat content increased. Cooking loss was also constant up to approximately 28% fat, corresponding to BMS No.4, and markedly decreased with fat content increase. The beef in these cases were, however, classified into BMS No. around 9 and 11, respectively, according to the BMS model in 1988. A negative correlation was found between the shear‐force value and the fat content (r =?0.83, P < 0.05). Most FAA concentrations on the wet weight of meat were correlated negatively with the fat content, except glutamine, and this negative relationship was still observed when the concentrations were recalculated on the basis of protein. These results indicate that higher marbling Wagyu beef (above approx. 23% fat) would have an extremely lower content of protein, which would partly explain the lower cooking loss and FAA with fat increase. In addition, some other reasons not relating to protein content (e.g. high fat content preventing the breakdown of protein to FAA) seem to explain the negative correlation between fat and FAA.     

Rhizopus Rot of Mulberry-grafted Saplings Caused by Rhizopus oryzae

A new disease on stocks of mulberry-grafted saplings was found in Tsukuba in 1999. A representative isolate of the Rhizopus species that was consistently isolated from rotted tissues was pathogenic to healthy mulberry stocks. The causal fungus was identified morphologically as Rhizopus oryzae Went & Prinsen Geerligs. Rhizopus rot (“Naefuhaibyou” in Japanese) was proposed for the name of the disease. This is the first report on a mulberry disease caused by R. oryzae. Received 30 March 2001/ Accepted in revised form 4 June2001     

Analysis of weed vegetation of no-tillage upland fields based on the multiplied dominance ratio

The objective of the present study was to clarify the characteristics of weed vegetation in no-tillage upland fields in Japan. Vegetation surveys were conducted in two stages and the obtained data were analyzed based on the multiplied dominance ratio. The first was a two-year survey of a no-tillage field and a tilled field where no-tillage or tillage farming had been carried out for more than 10 years. The no-tillage field surveyed exhibited a different seasonal succession from the tilled field. Summer annuals dominated the tilled field in summer, and winter annuals dominated in spring. Perennials occupied the no-tillage field in spring; summer annuals also dominated in summer. The second survey was of 19 and 22 fields, including some no-tillage fields, in the summer of 2000 and the spring of 2001. The vegetation in both summer and spring was classified into three vegetation types, principally dependent on the no-tillage periods: types I and II consisted mainly of tilled and under 3-year-old no-tillage fields, and type III comprised no-tillage fields three years old or over. Type II vegetation was characterized primarily by the presence of biennials and perennials of Asteraceae, and type III by perennials, such as sweet vernalgrass ( Anthoxanthum odoratum ), in addition to the same species as type II. Summer annuals such as southern crabgrass ( Digitaria ciliaris ) were abundant in many fields in summer regardless of the vegetation types.     

圈养大熊猫麻疹病毒易感性流行病学调查

成都大熊猫繁育研究基地对圈养的7只8～21岁的大熊猫血清犬瘟热病毒(CDV)中和抗体滴度进行了测定.结果显示,尽管这些大熊猫自2003年起每年接受2次CDV弱毒疫苗接种,该弱毒疫苗是由未知家犬犬瘟热病毒株制作的,大熊猫血清犬瘟热病毒中和抗体滴度却在2×到256×的较大范围内(平价值=16)波动.通常单次的麻疹病毒弱毒疫苗注射足以导致宿主产生相应的稳定的免疫反应,在大熊猫上抗犬瘟热中和抗体变化幅度较大提示在宿主与疫苗的关系中存在某种程度的不足.