Observation of some key stages of the embryonic development of Biomphalaria straminea (Dunker, 1848) (Molluska,Planorbidae)

Summary

Biomphalaria straminea is a freshwater snail and one of the intermediate hosts of the trematode parasite which causes schistosomiasis in Brazil. The main stages of embryonic development were analyzed with confocal laser scanning microscopy (CLSM), using the fluorescent probe DiOC and Nile Red as a vital stain in in vivo preparations. In fixed preparations nuclei were stained by the Feulgen reaction or the fluorescent DNA probe, Höechst 33342. Results obtained from the analysis of embryos at the stages of early cleavage, morula, blastula, gastrula, early trocophore and veliger showed that these stages are similar to those described for Biomphalaria glabrata and Biomphalaria tenagophila. CLSM optical sections of early trochophore showed important morphological structures such as the blastopore, stomodeum and shell gland; and in early veliger, internal organs such as the esophagus, stomach and male and female ducts were also clearly identified.     

A RANKL-Inducible Gene Znf216 in Osteoclast Differentiation

Osteoclasts possess catabolic activity in mineralized tissues and are involved in bone remodeling coordinating with osteoblasts. Although the pathway using receptor and activator of NF-κ B (RANK) and its ligand, RANKL, is known to be essential for osteoclast differentiation, their precise mechanisms are not fully understood. Using DNA microarray technology, we searched for genes that were up-regulated after RANKL stimulation in the macrophage cell line, RAW264.7 cells. A gene, Znf216, which encodes a zinc-finger protein, was detected among those genes up-regulated after RANKL stimulation. Expression of Znf216 was also induced by other cytokines such as TNFα and IL-1β. Although ectopic expression of full-length ZNF216 abrogated osteoclast differentiation, its truncated forms accelerated it. No significant inhibitory effect on the NF-κ B pathway was observed, however. These results suggest that ZNF216 is a potent inhibitory factor for osteoclast differentiation and that the mechanism is unlikely due to direct attenuation of the NF-κ B pathway.     

Isolation and characterization of microsatellite DNA loci for endangered fish,Japanese huchen (Hucho perryi)

Japanese huchen, Hucho perryi, is an endangered fish in Japan. In order to promote a conservation program for this species, it is necessary to evaluate its genetic diversity and population genetics. For this purpose, we designed 15 primers containing dinucleotide microsatellite regions and examined their allelic variation using a total of 23 wild individuals collected from two different localities. Eight loci showed moderate allelic variation ranging from two to four alleles, with expected heterozygosities from 0.043 to 0.548. These markers will be useful for the assessment of genetic variation for this species.     

The Relation of Concanavalin A Receptor Distribution to the Conjugation Process in Tetrahymena thermophila

By using fluorescent isothiocyanate-conjugated concanavalin A (FITC-Con A), cell surface events were examined under a light microscope during the early period of the conjugation process in Tetrahymena thermophila. Until the two complementary mating types (D-III and IV) were mixed, Con A-binding activities were hardly detected on the cell surface of ciliates. After mixing, however, the FITC-Con A (25 μg/ml) bound especially to the anterior cell surface at the early stage of conjugation, followed by characteristic changes of the Con A-binding pattern and, subsequently, by formation of a bright fluorescent ring around the area of contact between conjugants. Such alterations of FITC-Con A-binding pattern were found to be interrupted or eliminated by cycloheximide (2 μg/ml). These findings are related to the onset and subsequent conjugation in T. thermophila.     

秦岭川金丝猴个体间团抱模式及其影响因素

团抱行为作为保持体温与增进社会关系的一种有效途经在非人灵长类中广泛存在,受环境和社会因素影响在各物种间呈现出多样的模式。本研究自2007 年9 月至2008 年4 月间,运用焦点动物取样法和瞬时扫描取样法对秦岭北坡周至国家级自然保护区内的一群秦岭川金丝猴的团抱模式进行了1 637 回次的扫描,结果表明研究群内的个体回避单独休息,倾向于形成团抱,团抱主要发生在2 个或3 个个体之间,较少形成4 个或4 个以上个体的团抱;团抱主要由青少年个体和成年雌性组成,成年雄性和携婴雌性多参与小的团抱,青少年猴更频繁地出现在3 个个体的团抱中,未携婴雌性在4 个和4 个以上个体团抱中比例明显增加;秦岭川金丝猴各年龄性别组的个体对团抱伙伴的选择有各自的偏好,大多数团抱由成年雄性和未成年个体发起,但获得较少的团抱;雌性和携婴雌性较少主动发出但获得较多的团抱,这显示出雌性作为团抱的主体具有很高的社会亲和力;此外团抱模式还存在季节性的变化,冬季寒冷期团抱的频率和大小都会增加,并且个体选择在距离地面较近的区域团抱以保持体温,春季生育期个体倾向于在树冠层团抱以获得新鲜的食物并且避免婴猴被捕食。秦岭川金丝猴的团抱行为是物种在其独特的社会组织形式下对山地极端环境的一种适应,在进化中以行为模式获得更高适合度的具体策略。     

Evidence for divergent natural selection of a Lake Tanganyika cichlid inferred from repeated radiations in body size

Divergent natural selection is thought to play a vital role in speciation, but clear, measurable examples from nature are still few. Among the many possible sources of divergent natural selection, predation pressure may be important because predators are ubiquitous in food webs. Here, we show evidence for divergent natural selection in a Lake Tanganyika cichlid, Telmatochromis temporalis , which uses burrows under stones or empty snail shells as shelters. This species contains normal and dwarf morphs at several localities. The normal morph inhabits rocky shorelines, whereas the dwarf morph invariably inhabits shell beds, where empty snail shells densely cover the lake bottom. Genetic evidence suggested that the dwarf morph evolved independently from the normal morph at two areas, and morphological analysis and evaluation of habitat structure revealed that the body sizes of morphs closely matched the available shelter sizes in their habitats. These findings suggest that the two morphs repeatedly evolved through divergent natural selection associated with the strategy for sheltering from predators.     

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.     

非人灵长类饲养与管理过程中的福利保障

实验动物饲养管理和福利保障的问题已越来越被国际社会所关注.与发达国家相比,中国对实验动物福利的研究及大众化意识则相对滞后.中国作为世界上最大的实验灵长类动物的饲养与出口国,每年遭受的国际贸易损失始终位居全球首位.为此,本文引入了实验灵长类福利的"5个自由"理论:1)动物有避免干渴、饥饿和营养不良等不利因素影响的自由;2)动物有获得舒适生活条件的自由;3)动物有脱离痛苦、受伤和疾病骚扰的自由;4)动物有表达自然行为的自由;5)动物有脱离恐惧和心理压力的自由.在上述理论的基础上,提高实验动物福利应具体从饲养的物理环境、营养供给、饲养管理、繁殖管理及饲养环境的多样性等几方面着手.通过总结国际与此相关的研究进展,旨为中国相关研究提供素材和为完善国内现行的法规及标准提出一些思路.