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.     

Development and characterization of simple sequence repeat DNA markers for Zelkova serrata

We developed 14 microsatellite loci from an enriched genomic DNA library of a broad‐leaved deciduous tree, Zelkova serrata. Of 198 clones from the library, 112 contained microsatellite repeat regions. The M13‐tailed primer method was used for economy. Sequence‐specific primer pairs were designed for 58 of 76 candidate clones. Fourteen of these primer pairs successfully amplified polymorphic single loci among 34 individuals collected from the Kanto breeding region in Japan. The expected heterozygosity for the 14 microsatellite markers ranged from 0.378 to 0.876, suggesting that these will prove valuable for breeding and ecological studies on Z. serrata.     

Specialisation of bacterial endosymbionts that protect aphids from parasitoids

1. Infection by the bacterial endosymbiont Hamiltonella defensa is capable of protecting the pea aphid from parasitism by Aphidius ervi and the black bean aphid from parasitism by Lysiphlebus fabarum. Here we investigate protection of a third aphid species, the cowpea aphid, Aphis craccivora, from four parasitoid species: Binodoxys communis, B. koreanus, Lysiphlebus orientalis, and Aphidius colemani. 2. We compared parasitism of A. craccivora lines that were either infected with, or cured of H. defensa separately for the four parasitoid species. Infection by H. defensa almost completely eliminated parasitism of A. craccivora by B. communis and B. koreanus, but had no effect on parasitism by L. orientalis and A. colemani. 3. This indicates at least genus‐level specificity of protective effects by H. defensa and we discuss implications of our findings on the known world‐wide distribution of this host/symbiont interaction.     

Effects of saline intake on spermatophore and sperm ejaculation in the male swallowtail butterfly Papilio xuthus (Lepidoptera: Papilionidae)

Although sodium ions induce puddling behavior in males of some butterfly species, the role of sodium ions in male life history is unclear. Newly emerged laboratory‐reared males of the swallowtail butterfly Papilio xuthus were allocated to five adult diets: water (as a control) and 0.001, 0.01, 0.1 or 1 mol/L saline solution. Males preferred to take 0.1 mol/L saline solution. We attempted to hand‐pair males after two days of intake. Males on all diets, except those taking 1 mol/L saline solution, were likely to couple. Males taking 0.01 mol/L saline solution produced the largest spermatophore, although there were no significant differences in the number of eupyrene sperm bundles and apyrene spermatozoa between saline‐taking males and control males. Salt accumulation in the male body also had little effect on the number of both types of spermatozoon in the spermatophore.     

CHANGES IN THE CAPACITY FOR CLONAL GROWTH AND DIFFERENTIATION IN VITRO OF THE VERTEBRAL CARTILAGE CELLS WITH EMBRYONIC DEVELOPMENT II. VITALIZING EFFECT OF CONDITIONED MEDIUM ON THE CELLS OF YOUNGER EMBRYOS

Most of the younger cartilage cells taken from chick embryos at the stage 35 were known to regress after the initial cell multiplication in in vitro clonal culture. A partial supplementation of conditioned medium (CM) to the standard medium was effective to permit colony formation from many of these younger cells. Most colonies thus derived from the younger cells by the aid of CM expressed differentiative traits as cartilage, as the cells from older embryos did. CM exerted multiple effects on clonal development of the younger cells. It vitalized the cells destined to regress, to promote cell multiplication and to flatten the shape of the colony. The experimental results suggested that these effects were associated with an independent factor each.     

AN ANALYSIS ON THE TROPISM IN HVJ (SENDAI VIRUS) INFECTION: MANIFESTATION OF HIGH VIRAL SUSCEPTIBILITY IN SPREADING CULTURES OF ISOLATED ALLANTOIC EPITHELIAL CELLS OF THE CHICK EMBRYO

By culturing pure allantoic epithelial cells separated from the chorioallantoic membrane of a 10-day-old chick embryo, sheets of monolayered epithelial cells were obtained and maintained for at least one week. These cells were highly susceptible to infection with HVJ (Sendai virus) in vitro . In similarly cultured mesenchymal cells of the chorioallantoic membrane, the susceptibility was found to be very low. It was concluded that the tropism observed in HVJ infection in vitro can be explained by differences in the susceptibility to HVJ among various cell types.     

Cowpea aphid (Aphis craccivora) associated with different host plants has different facultative endosymbionts

Maternally inherited facultative endosymbiotic bacteria are common among insects, including many polyphagous insect herbivores. To investigate whether symbiont infection is structured by host plant in the polyphagous aphid Aphis craccivora Koch, pyrosequencing and diagnostic PCR were performed on 26 populations from two different host plants, alfalfa (Medicago sativa) or black locust (Robinia pseudoacacia). Results indicated that Aphis craccivora harbours distinctly different microbial communities in alfalfa versus locust. The facultative symbiont Hamiltonella was found only in aphids collected from alfalfa, and the facultative symbiont Arsenophonus was found only in aphids from locust. Hamiltonella is known to protect aphids against hymenopteran parasitoids, whereas the phenotypic effects of Arsenophonus in aphids are unknown. Correspondingly, a screen of the aphid samples for hymenopteran DNA indicated that Hamiltonella‐bearing alfalfa populations of A. craccivora experienced lower parasitism than Arsenophonus‐bearing locust populations. This study contributes to the growing body of evidence that correlative associations between bacterial endosymbionts and host plants may be a common phenomenon in polyphagous herbivores, and suggests that microbial symbionts have the potential to act as drivers for observed ecological differences among host‐associated populations of polyphagous insects.     

Strophiole of seeds of the black locust acts as a water gap

In Japan the black locust (Robinia pseudoacacia L.) is undergoing rapid habitat expansion, which has an adverse effect on native vegetation. It is therefore a priority to clarify the regeneration characteristics of the black locust and establish adequate management of this invasive species in Japan. To determine the germination characteristics of physically dormant black locust seeds, we observed anatomical features of the seed coat and identified the water gap that acts as a signal detector. Our microscopic observations showed that seed coats of this species had hilum, micropyle and strophiole. The anatomical features of these regions correspond to the general characteristics of papilionoid legume seeds. Based on our microscopic observations, water absorption blocking experiments and a dye tracking experiment, we identified the strophiole as a water gap in black locust seeds. Our results suggest that the opening of the strophiole is important for water uptake to the embryo and subsequent germination of black locust seeds under natural conditions.