Piebald mutation on a C57BL/6J background

The classic piebald mutation in the endothelin receptor type B (Ednrb) gene was found on rolling Nagoya genetic background (PROD-s/s) mice with white coat spotting. To examine whether genetic background influenced the phenotype in the piebald mutant mice, we generated a congenic strain (B6.PROD-s/s), produced by repeated backcrosses to the C57BL/6J (B6) strain. Although B6.PROD-s/s mice showed white coat spotting, 7% of B6.PROD-s/s mice died between 2 and 5 weeks after birth due to megacolon. The PROD-s/s, s/s and Japanese fancy mouse 1 (JF1) strains, which also have piebald mutations on different genetic backgrounds with B6, showed only pigmentation defects without megacolon. In expression analyses, rectums of B6.PROD-s/s with megacolon mice showed ~5% of the level of Ednrb gene expression versus B6 mice. In histological analyses, aganglionosis was detected in the rectum of megacolon animals. The aganglionic rectum was thought to lead to severe constipation and intestinal blockage, resulting in megacolon. We also observed an abnormal intestinal flora, including a marked increase in Bacteroidaceae and Erysipelotrichaceae and a marked decrease in Lactobacillus and Clostridiales, likely inducing endotoxin production and a failure of the mucosal barrier system, leading ultimately to death. These results indicate that the genetic background plays a key role in the development of enteric ganglion neurons, controlled by the Ednrb gene, and that B6 has modifier gene (s) regarding aganglionosis.     

Timing of Puberty and Its Relationship with Body Growth and Season in Male Raccoons (Procyon lotor) in Hokkaido

The raccoon (Procyon lotor), indigenous to North America, has naturalized in Japan as an invasive alien species, having been introduced into the country in the 1970s. In Hokkaido, the northernmost island of Japan, feral raccoons have been increasing in number and spreading throughout the island. The age at the onset of puberty for raccoons is important for estimating individual lifetime reproductive success and population growth. The present study investigated the timing of and potential factors affecting the onset of puberty in male raccoons in Hokkaido. External characteristics and histology of testes were studied in 151 male feral raccoons and in 1 captive juvenile. For the majority of feral yearling raccoons, prepubertal development began in May, and spermatozoa production began in October prior to their second mating season. However, some larger juveniles attained puberty during the juvenile period. The captive juvenile, which was fed throughout the winter, attained puberty only 11 months after birth. These results suggest that if male raccoons can achieve enough body growth before the first mating season, puberty can be attained early. In both juveniles and yearlings, spermatozoa production was only observed after autumn. This timing coincided with the recrudescence of seasonally active spermatogenesis in adult males. Therefore, attaining puberty in male raccoons appears to require both adequate body nutrient development and several environmental factors that control seasonal testicular changes.     

Changes in circulating adiponectin and metabolic hormone concentrations during periparturient and lactation periods in Holstein dairy cows

Although our previous report demonstrated that adiponectin and AdipoR1 gene expressions changed among different lactation stages in the bovine mammary gland, its in vivo kinetics remain unclear in ruminant animals. In this study, we investigated the changes in circulating concentrations of adiponectin, as well as other metabolic hormones and metabolites, (i) during the periparturient period and (ii) among different lactation stages, in Holstein dairy cows. In experiment 1, serum adiponectin concentrations increased after parturition. Serum insulin concentrations were lower in the postpartum than prepartum period, whereas serum growth hormone (GH) concentrations increased in the postpartum period. Serum nonesterified fatty acids (NEFA) levels were increased during the postpartum period and were dependent on the parity. In experiment 2, there was no significant difference in plasma adiponectin concentrations among lactational stages. Plasma insulin concentrations tended to be lower in early lactation while plasma GH levels tended to be higher. Plasma NEFA concentrations were significantly lower in mid‐ and late‐lactation stages than non‐lactation stages. These findings indicate that elevation of serum adiponectin might be involved in energy metabolism just around parturition, and might exert its action through regulation of receptor expression levels in target tissues in each lactational stage in Holstein dairy cows.     

Effect of calcitonin on adrenocorticotropic hormone secretion stimulated by corticotropin‐releasing hormone in the hen anterior pituitary

The presence of a receptor for calcitonin (CT) and the effect of chicken CT (cCT) on adrenocorticotropic hormone (ACTH) secretion stimulated by rat/human corticotropin‐releasing hormone (rhCRH) in the hen anterior pituitary were studied. The specific [¹²⁵I]cCT binding component was present in the plasma membrane of hen anterior pituitary and this binding component had properties of a receptor which has binding specificity to cCT, reversibility, saturable binding, high affinity and limited capacity. When anterior pituitary cells were incubated in vitro, cCT increased the maximal secretion of chicken ACTH stimulated by rhCRH. These results suggest that CT may act directly on the anterior pituitary via its receptor binding and enhances the ACTH secretion by CRH.     

治沟骨干工程台阶式泄水建筑物的消能防冲研究

进行了可用于治沟骨干坝的3种不同坡度的台阶式泄水建筑物的模型试验。结果表明,在跌落水流时,消力池跃前断面单位能量随斜坡变陡和相对坝高Hdam/yc增加而增大,但当Hdam/yc增加到某一值后,逐渐趋于平缓。消力池跃前断面底部压力yp与堰上临界水深yc呈现正比线性相关,yp大小与台阶个数N无关。比较跃前断面压力修正系数λ>1和λ=1时的消能率,当Hdam/yc=10左右时,其消能率相对误差可达7%左右,但当Hdam/yc≥70时,其相对误差则降至1%。试验结果也同时显示出λ与yp/y1同样有着很好的线性关系,其相关系数r=0.99999。     

Mass spectrometric detection of proopiomelanocortin (POMC)-related peptides following molecular cloning of POMC cDNA in bigeye tuna Thunnus obesus

Several pituitary hormones, including adrenocorticotropin (ACTH), melanotropin (MSH) and β-endorphin, are generated from a common precursor protein, proopiomelanocortin (POMC). In fish, in addition to steroidogenesis of ACTH and melanogenesis of MSH, immunomodulating activity has been found in some POMC-related peptides. To investigate the functions of these peptides in the homologous system, it is necessary to establish a convenient detection method for the peptides. The present study aimed to establish a method for the detection of POMC-related peptides in bigeye tuna Thunnus obesus using a small amount of tissue sample, but not requiring peptide purification. We first determined the nucleotide sequence of tuna POMC cDNA. The cDNA was composed of 1084 base pairs (excluding the poly A tail) that encoded POMC consisting of 222 amino acids. We then fractionated an acid-acetone extract of one pituitary by reverse-phase high performance liquid chromatography (HPLC) and determined the molecular weight of each separated peptide by mass spectrometry. Consequently, we detected eight POMC-related peptides by comparing the values to the deduced amino acid sequence. Thus, the present study enabled the detection of POMC-related peptides from a small amount of tissue without the use of several purification steps.     

连接与切断处理对土壤氮素资源异质环境中结缕草主匍匐茎的影响效应

通过实验检验了克隆植物结缕草在异质生境条件下的生理整合作用。结缕草被栽植于4种类型的“生境”内(它们的总体土壤氮素资源水平呈现梯度变化),并同时对匍匐茎的节间实施连接与切断2种处理。实验结果表明,呈连接状态的结缕草克隆的平均复合节数量、平均匍匐茎长度和生物量在各个生境类型间并未表现出明显的差异。但主匍匐茎实施切断处理后的结缕草克隆的上述各项指标均显著减小。生长于贫瘠土壤斑块上的复合节平均根系生物量和根/茎比均高于肥沃土壤斑块。这一特征与其它典型的克隆植物明显不同。结缕草克隆在保持连接的情况下,土壤氮素对节间长度和比节间长度的伸长生长以及分蘖的形成具有促进作用。实验过程中的节间切断处理抑制了节间的进一步伸长但提高了比节间长度。保持结缕草克隆整合并尽量避免严重干扰显得十分重要,特别是在结缕草早期生长阶段。