How can river-estuarine planktonic copepods survive river floods?

Distribution of brackish-water zooplankton was surveyed in the Chikugo River estuary, Japan, at 3-h intervals for 24h, including several hours when the river was heavily flooded because of rainfall and discharge from an upstream dam. The populations of the dominant copepods Pseudodiaptomus inopinus and Sinocalanus sinensis were concentrated in the mixing zone of the salt wedge before river flooding. During the period of flooding, they were almost completely swept out from the river, but examination of water trapped by a sediment grab sampler revealed that adults of Pseudodiaptomus inopinus were aggregated immediately above the bottom of the submerged channel outside the river mouth. After the flood, aggregations of both species appeared again in the river together with the salt wedge, and the proportion of adults in the aggregations became significantly higher than before. These results suggest that immature copepods suffer population losses through river flooding, but that the copepods can survive such flooding by means of both behavioral and reproductive mechanisms; that is, adult copepods maintain their position on the bottom of submerged channels outside the river mouth during a river flood and replace the population loss through reproduction after the flood. Channels outside river mouths are thus regarded as important topographic refuges for river-estuarine zooplankton to survive a flood.     

Establishment of a novel dwarf rat strain: cartilage calcification insufficient (CCI) rats

Rats with dwarfism accompanied by skeletal abnormalities, such as shortness of the limbs, tail, and body (dwarf rats), emerged in a Jcl-derived Sprague-Dawley rat colony maintained at the Institute for Animal Experimentation, St. Marianna University Graduate School of Medicine. Since the dwarfism was assumed to be due to a genetic mutation based on its frequency, we bred the dwarf rats and investigated their characteristics in order to identify the causative factors of their phenotypes and whether they could be used as a human disease model. One male and female that produced dwarf progeny were selected, and reproduction was initiated by mating the pair. The incidence of dwarfism was 25.8% among the resultant litter, and dwarfism occurred in both genders, suggesting that it was inherited in an autosomal recessive manner. At 12 weeks of age, the body weights of the male and female dwarf rats were 40% and 57% of those of the normal rats, respectively. In soft X-ray radiographic and histological examinations, shortening and hypoplasia of the long bones, such as the tibia and femur, were observed, which were suggestive of endochondral ossification abnormalities. An immunohistochemical examination detected an aggrecan synthesis disorder, which might have led to delayed calcification and increased growth plate thickening in the dwarf rats. We hypothesized that the principal characteristics of the dwarf rats were systemically induced by insufficient cartilage calcification in their long bones; thus, we named them cartilage calcification insufficient (CCI) rats.     

STUDIES ON PROTEIN METABOLISM IN HIGHER PLANTS. III. CHANGES IN THE SOLUBLE PROTEIN COMPONENTS WITH LEAF GROWTH

Water soluble protein was extracted from tobacco leaves (BrightYellow) and fractionated through chromatographic and immunochemicalprocedures. Six different UV-absorbing components, 7 antigeniccomponents, and 4 enzyme activities (phosphatase, protease,peroxidase and RNase) were detected on the Sephadex chromatogramsof leaf extracts. An UV-absorbing fraction, Fr. I-2, (immunochemicallydesignated as Pr. Imm-I) corresponded to the known "FractionI " of S. G. WILDMAN. The contents of the three antigenic components,Imm-a, Imm-b and Imm-c, having estimated molecular weights of1 to 2 10⁵, showed significant fluctuations during growthof the leaves. Peroxidase and another antigenic component (Imm-f)of smaller molecular weight showed increase with age of theleaves. Properties of the protein components thus detected wereinvestigated. (Received May 11, 1967; )     

Expression of Tyrosinase Gene in Transgenic Albino Mice: The Heritable Patterned Coat Colors

To elucidate the regulatory mechanism for tyrosinase gene expression in vivo, we microinjected a mouse tyrosinase minigene, mg-Qrs-J, into the fertilized eggs of BALB/c albino mice. As a result, we obtained six pigmented founder mice that exhibited non-standard coat color variations as well as the wild-type phenotype. These founder mice were subsequently crossed with BALB/c albino mice to establish the transgenic lines. As a consequence, two primary lines and five sublines have been obtained from four of the six founder mice. We found that not only uniformly pigmented phenotypes but also patterned phenotypes were inherited by their descendants. The possible underlying mechanism of the patterned phenotypes is discussed.     

家蚕抑前胸腺肽类似物的活性鉴定和结构分析

以家蚕Bombyx mori抑前胸腺肽的氨基酸序列作为基础,通过氨基酸残基的添加、减少和置换,人工合成了一组与家蚕抑前胸腺肽结构类似的多肽。利用家蚕前胸腺体外培养技术,结合蜕皮激素放射免疫分析方法,鉴定了与抑前胸腺肽结构类似的多肽的生理活性,并对它们的活性特征、化学参数、结构和功能、信号传导途径进行了综合的比较和分析。类似物899808的生物学功能与抑前胸腺肽的相同而且活性近似;类似物899805和899809对家蚕前胸腺蜕皮激素的生物合成表现出随浓度增加而增加的促进作用,而低浓度下几乎不促进;899803、899804、899806和899807类似物对家蚕前胸腺蜕皮激素的生物合成的促进和抑制作用与它们的浓度有着依赖关系。实验结果表明,对抑前胸腺肽的氨基酸序列作任何改变,都导致其生理活性的下降、丧失甚至相反的活性。