Co-variation in frequency and severity of cardiovascular and skeletal defects in Sprague-Dawley rats after maternal administration of dimethadione, the N-demethylated metabolite of trimethadione

BACKGROUND: The anticonvulsant trimethadione is a potent inducer of ventricular septation defects, both clinically and in rodents. Teratogenicity requires its N‐demethylation to dimethadione, the proximate teratogen. It was previously demonstrated trimethadione only induced membranous ventricular septation defects in rat (Fleeman et al., 2004 ), and our present goal is to determine whether direct administration of dimethadione increases the incidence and severity of septation defects. METHODS: Pregnant Sprague‐Dawley rats were divided into five groups and administered either distilled water (control) or four different regimens of dimethadione. The core treatment was 300 mg/kg dimethadione b.i.d. on gestation day 9, 10 with additional groups given one additional dose of dimethadione 12 hr earlier, 12 hr later or two additional doses 12 hr earlier and later. Caesarian sections occurred on gestation day 21 and fetuses were examined for standard developmental toxicity endpoints. RESULTS: The broadest dosing regimen yielded the highest incidence and the most severe heart and axioskeletal findings with a decrease in mean fetal body weight. The overall incidence of ventricular septation defects was 74%, of which 68% were membranous and 9% muscular. Outflow tract anomalies (17%) were also observed, as were malformations of the axioskeleton (97%), but not of the long bones, and of particular interest was the high incidence of sternoschesis. CONCLUSIONS: Unlike trimethadione, dimethadione induces more serious muscular septation defects that are believed to be more clinically relevant. This, when taken together with the high incidence of total septation anomalies suggests dimethadione is useful for the study of chemically induced ventricular septation defects. Birth Defects Res (Part B) 92:206–215, 2011. © 2011 Wiley‐Liss, Inc.     

荧光Real-time PCR鉴定鸡胸骨总RNA质量

为了更准确地鉴定提取鸡骨总RNA的质量,试验分别用核酸蛋白检测仪、1%琼脂糖凝胶电泳和荧光Real-time PCR检测评价3种不同的方法提取成年鸡胸骨总RNA的质量。结果显示,荧光Real-time PCR可更好地鉴定提取的骨总RNA的质量。用核酸蛋白检测仪、1%琼脂糖凝胶电泳能粗略检测RNA的纯度和完整性,但不能反映提取过程中是否引起基因不均一的减少,所检测的纯度也不能精确反映RNA的反转录效率。     

四种鹤的胸骨和肩带骨比较

本文对国家一类保护动物丹顶鹤、白枕鹤、白头鹤、白鹤的胸骨与肩带骨进行了比较,阐明白鹤与鹤属的3种鹤在骨胳特征上的重要差别,进一步论证把白鹤从鹤属分离出来与肉垂鹤合为一个属是正确的。本文首次就胸骨和肩带骨特征提出4种鹤的检索表。文中附有胸骨和肩带骨的量度和12幅鹤的胸骨图。     

A comparative study of lectin binding to cultured chick sternal chondrocytes and intact chick sternum

Cultured chondrocytes derived from the caudal and cephalic ends of embryonic chick sterna have been compared with each other and with whole sternum, by using a panel of 21 lectins to probe the distribution of oligosaccharides in glycoconjugates of cells and matrix at various times of culture or development. On culture in collagen gels, the cells changed their morphology with time, degrading glycan in the surrounding culture medium and depositing new matrix, the glycan content of which reflected the site of origin of the cells, indicating that the glycan phenotype of both cells and matrix (‘glycotype’) was predetermined and persistent. Sterna of embryonic chicks showed unexpected complexity in their distribution pattern of glycan, containing at least six distinct regions. Major regional temporal differences were evident among saccharides terminating in α-N-acetyl galactosamine and β-galactose, while changes in glycans terminating in fucose, sialic acid and α-mannose were somewhat less marked. Subsets of complex N-glycans changed little. This revised version was published online in November 2006 with corrections to the Cover Date.     

Ontogenetic analysis of siliceous cell wall formation in Triparma laevis f. inornata (Parmales,Stramenopiles)

Triparma laevis f. inornata is a unicellular alga belonging to the Bolidophyceae, which is most closely related to diatoms. Like diatoms, T. laevis f. inornata has a siliceous cell wall. The cell wall of T. laevis f. inornata consists of four round plates (three shields and one ventral plate) and one dorsal and three girdle plates. But, unlike diatoms, T. laevis f. inornata cells can grow when concentrations of silica are depleted. We took advantage of this ability, using TEM to study the ontogeny of the siliceous plate, pattern center formation, and development. Two types of pattern centers (annulus and sternum) were observed in the early and middle stage of plate formation. During their formation, the annuli were initially crescent‐shaped but eventually their ends fused to make a ring. Only outward silica deposition of the branching ribs occurred on the growing annulus until it became a ring, resulting in an unfilled circle inside the annulus. The pattern center of the shield plate was always an annulus, but in ventral plates both annulus and sternum were observed. The annuli and sterna in T. laevis f. inornata round plates were very similar to the annuli and sterna in diatom valves. These results suggested that the round plates of Parmales are homologous to diatom valves. This information on the plate ontogeny of T. laevis f. inornata provides new insights into the evolution of the siliceous cell wall in the Parmales and diatoms.     

Valve morphogenesis in an araphid diatom Rhaphoneis amphiceros (Rhaphoneidaceae,Bacillariophyta)

The pattern centre in valve morphogenesis is an annulus in centric diatoms or a sternum in pennate diatoms. The genus Rhaphoneis is currently placed within a lineage that diverges at the root of the pennate diatom clade in most molecular phylogenies, and its valves have a unique pattern to their striae, i.e. radiating from both apices, giving the impression that a pattern centre exists at both ends of the valve and virgae (ribs) formation proceeds centripetally. The present study, however, shows that the pattern centre is actually a linear sternum and the formation of virgae proceeds centrifugally, a pattern centre that is commonly found in most araphid diatoms. Thus, the hypothesis that valve morphogenesis based on a linear sternum and perpendicular virgae is a synapomorphy of pennate diatoms is supported. Our study also demonstrates that the pattern of valve formation can be observed by light microscopy with a direct mounting method when the specimen is relatively large, i.e. exceeding approximately 50 µm in valve length. An important advantage of the use of the direct mounting method is that it requires no repeated centrifugation steps for dehydration, steps necessary for observation by a scanning electron microscope, causing the loss and/or collapse of the specimen, particularly with fragile valves in the early stages of development.     

红羊新蚤的地理分布、宿主关系和鉴别特征的研究(蚤目：多毛蚤科)

自从红羊新蚤Neopsylla hopgyangensis Li,Bai & chen,1986从宁夏回族自治区的海原和贺兰山林区发现并报道(四川动物5(2)：1-3)以后,青海、甘肃和陕西均先后发现他们以往鉴定为二齿新蚤的大多数为红羊新蚤。本文报道红羊新蚤的地理分布、海拔、主要宿主及鉴别特征的应用。     

明晰双肋藻(硅藻门)的超微结构研究北大核心CSCD

在对武陵山区硅藻分类和多样性研究中,收集到了一种双肋藻的标本,经研究鉴定,其为明晰双肋藻[Amphipleura pellucida(Kützing)Kützing]。光学显微镜观察和扫描电子显微镜观察结果表明:明晰双肋藻具有以下特征:(1)纺锤形的壳瓣外形。(2)长而直的中央胸骨。(3)仅着生在靠近壳面两端的短壳缝系统。(4)线纹密度为38~39条/10μm,孔纹密度为54~58个/10μm。(5)壳缝的外近缝端呈直线状,远缝端略微膨大。(6)孔纹内侧开口被圆形筛膜覆盖。该研究结果为明晰双肋藻提供了清晰的超微结构图片资料以及科学的描述。     

Thoracic skeletal defects and cardiac malformations: A common epigenetic link?

Congenital heart defects (CHDs) are the most common birth defects in humans. In addition, cardiac malformations represent the most frequently identified anomaly in teratogenicity experiments with laboratory animals. To explore the mechanisms of these drug-induced defects, we developed a model in which pregnant rats are treated with dimethadione, resulting in a high incidence of heart malformations. Interestingly, these heart defects were accompanied by thoracic skeletal malformations (cleft sternum, fused ribs, extra or missing ribs, and/or wavy ribs), which are characteristic of anterior-posterior (A/P) homeotic transformations and/or disruptions at one or more stages in somite development. A review of other teratogenicity studies suggests that the co-occurrence of these two disparate malformations is not unique to dimethadione, rather it may be a more general phenomenon caused by various structurally unrelated agents. The coexistence of cardiac and thoracic skeletal malformations has also presented clinically, suggesting a mechanistic link between cardiogenesis and skeletal development. Evidence from genetically modified mice reveals that several genes are common to heart development and to formation of the axial skeleton. Some of these genes are important in regulating chromatin architecture, while others are tightly controlled by chromatin-modifying proteins. This review focuses on the role of these epigenetic factors in development of the heart and axial skeleton, and examines the hypothesis that posttranslational modifications of core histones may be altered by some developmental toxicants.