绿瘦蛇捕食鳄蜥的现象

鳄蜥(Shinisauruscrocodilurus)是濒危的孑遗物种,生存遭受多方威胁。除人为猎杀和生境受到破坏之外,天敌也是其致命的威胁之一,但目前关于其被天敌捕食的研究非常匮乏。本文报道了绿瘦蛇(Ahaetullaprasina)捕食鳄蜥的现象,以全事件记录法观察了这一行为过程。鳄蜥面对的被捕食风险可能较广。除蛇外,鳄蜥的天敌也可能是鸟类等动物。在饲养繁育中,要注意加强防范举措,以免鳄蜥被天敌侵害。     

The relation of time to direction and equality of cleavage in Ilyanassa embryos

Summary

Cleavage inhibition experiments using cytochalasin B and hydrostatic pressure demonstrate the existence of a “clock mechanism” specifying cleavage time and form in Ilyanassa obsoleta embryos. Cytokinesis but not karyokinesis is inhibited during these treatments. When second cleavage is inhibited, the following cleavage occurs approximately on schedule with controls. Two micromeres are produced in this cleavage even though treated embryos consist of only two cells. When third cleavage is inhibited, the following micromere cleavage occurs in a counter clockwise direction, typical for the controls. Treatment with nocodazole, an antitubulin drug, inhibits both cytokinesis and karyokinesis but does not affect the cleavage clock mechanism. Treatment with 2,4-dinitrophenol stops both cleavage and the clock mechanism. These results indicate that the cleavage clock in Ilyanassa requires energy but does not depend on centrosomal behavior or on the form of previous cleavages. With regard to the production of micromeres the clock may involve an interaction between the aster-spindle complex and special regions of the animal pole cortex.     

Developmental effects of trichloroacetate in Zebrafish embryos: Association with the production of superoxide anion

To assess the developmental toxicity of trichloroacetate (TCA), zebrafish embryos were exposed to 8 to 48 mM of TCA and evaluated for developmental milestones from 8‐ to 144‐hour postfertilization (hpf). All developmental toxicities are reported in this paper. Embryos were found to have developed edema in response to 16 to 48 mM of TCA exposure at 32‐ to 80‐hpf, experienced delay in hatching success in response to 24 to 48 mM at 80‐hpf. Lordosis was observed in developing embryos exposed to 40 to 48 mM at 55‐ to 144‐hpf. The observed toxic effects of TCA exposure were found to be concentration and exposure period independent. Effects were found to be associated with increases in superoxide anion production, but these increases were also found to be concentration and time independent. TCA resulted in concentration‐dependent increases in embryonic lethality at 144‐hpf, with an LC₅₀ determined to be 29.7 mM.     

Embryo donation and receipt in Australia: views on the meanings of embryos and kinship relations

Research on embryo donation and receipt continues to grow, highlighting how specific national contexts shape views and experiences. The present article reports on a qualitative study on embryo donation and receipt in Australia. Interviews were conducted with 15 participants: embryo donors and those seeking to donate (6), embryo recipients and those seeking donors (3), people with embryos in storage or previously in storage (5), and egg donors where resulting embryos were donated to a third party (1). A deductive thematic analysis identified four key themes: understandings of embryos as cells, potential children, and/or children; a focus on relationships between “siblings”; importance of language and “family words” in discussing relationships; and extended family members having difficulty understanding the concept of embryo donation. The article concludes with a consideration of the implications of the findings in terms of the practice of embryo donation and the policies that surround it.     

The stimulating effect of recombinant cytokine LIF on the mouse blastocysts during implantation

The effect of recombinant LIF cytokine (Leukemia inhibitory factor) on the isolated mouse embryos at the stages of middle and late blastocyst has been investigated. We have demonstrated here that this agent is necessary in vitro at the stage of normal trophoblast formation after the blastocysts hatch from zona pellucida. This cytokine (10 ng/ml) caused intensification of adhesion and proliferative activity of the trophoblast cells. This is important for intercellular interactions with endometrium and for invasion of embryos into the uterus. The recombinant LIF insignificantly influenced cells of the inner cell mass.     

Vitellogenin cleavage products as indicators for toxic stress in zebra fish embryos: a proteomic approach

Vitellogenins (Vtgs) are the major yolk proteins in all oviparous animals. Systematic and regulated processing of these during embryogenesis is crucial for embryonic development. In the present study, toxicant-induced disturbance of Vtg degradation processes during Danio rerio (DR) embryogenesis was analysed to establish a sensitive tool for monitoring toxic stress at the molecular level. A 2-DE-based proteomic approach for whole DR embryos was established to study Vtg cleavage products (lipovitellin (Lv) derivatives). Ethanol was chosen as a positive control for a toxicity related change in the proteome of whole zebra fish embryos. Protein extracts from embryos treated with two ethanol concentrations, 0.5 and 2% v/v, showing either no or very strong visible effects, like absent heartbeat and blood circulation, were examined. Significant changes in the Lv pattern were detected for both conditions. The results are interpreted as scope for the use of the high abundant Lv derivatives as sensitive stress indicators in zebra fish embryos reflecting the overall fitness of the intact organisms.     

栓皮栎体细胞胚胎发生的细胞组织学观察

以栓皮栎未成熟合子胚为外植体,在添加0.25mg/L 2,4-D和0.5mg/L 6-BA的MS培养基上6周可诱导产生2种类型的胚性愈伤组织,一种表面具光泽、白色;另一种表面光滑湿润具光泽,色泽淡黄或无色透明。组织切片表明,胚性愈伤组织的细胞体积小,细胞核大,细胞质浓,细胞排列紧密;非胚性愈伤组织细胞的体积大,细胞核小,细胞质稀薄。胚性细胞团培养在不含激素的培养基上可诱导产生体细胞胚。体细胞胚直接起源于胚性细胞团表皮或近表皮的单细胞,经历与合子胚相似的球形胚、心形胚、鱼雷胚和子叶胚发育阶段。所有发育时期的体细胞胚的胚轴、子叶均产生次生体胚,它们起源于细胞质较浓的表皮单细胞。     

Cathepsin L involved in the freezing resistance of murine normal hatching embryos and dormant embryos

The cryopreservation of mammalian embryos is an important technology in embryo engineering. The discovery and application of the embryo's own high freezing resistance factors are the main methods to improve the utilization of mammalian embryos in cryopreservation. Cathepsin L gene expression in the frozen and thawed dormant embryos displayed a significant difference from those normal hatched ones. The aim of the present study was to dig out the potential role of Cathepsin L in anti-freezing capacity of murine blastocysts by investigating the location and expression of Cathepsin L in frozen and thawed both activated and dormant hatching blastocysts. Different concentrations of Cathepsin L recombinant protein and E-64d were then respectively added into the embryo cryoprotectant and pre-cryo culture medium. Our results found that down-regulation of Cathepsin L improves the freezing resistance of murine normal hatching embryos by reducing apoptosis. Cathepsin L inhibitors can be used to improve the efficiency of cryopreservation and recovery of blastocysts in vitro. Our study provides a theoretical basis for the further development and application of Cathepsin L.