小鼠2-细胞胚胎单个卵裂球体外培养及其发育形成囊胚的玻璃化冷冻保存技术的研究

单个卵裂球分离和培养是生产同卵双胎或一卵多胎动物的一种有效方法。在羊和牛已经获得了来源于2-细胞和4-细胞期胚胎的单个卵裂球的活体后代;在兔也获得来源于4-细胞胚胎的单个卵裂球后代;在猪已获得8-细胞单个卵裂球的后代。但多数的研究者发现,小鼠单个卵裂球培养后的体外发育率、移植妊娠率和产仔率都很低。上述均为新鲜胚移植结果,至于分离后卵裂球发育成的囊胚再进行玻璃化冷冻保存尚未见报道。本实     

De novo methylation of MMLV provirus in embryonic stem cells: CpG versus non-CpG methylation

Nuclear factor Y (NF-Y) is a highly conserved trimeric activator that recognizes with high specificity and affinity the widespread CCAAT box promoter element. We previously cloned the genes of 23 NF-Y genes of Arabidopsis thaliana (Gene 264 (2001) 173). Now that the Arabidopsis genome sequencing project is complete, we present the cloning, alignments and expression profiles of the remaining six genes coding for the three NF-Y subunits. Consistent with our previous reports, most of the new members of the three subunits show a unique tissue-specific pattern, while another AtNF-YC9 is rather ubiquitous.     

Gender influence on jejunal migrating motor complex

The role of gender and the menstrual cycle in small bowel motility has not been clearly elucidated. Jejunal motility was recorded with a nasojejunal catheter incorporating five solid-state pressure transducers in ambulatory menstruating women and men of comparable age over 24 h. All women were studied twice, in the early follicular (early-F) and midluteal (mid-L) phases of the menstrual cycle, verified by determining serum levels of gonadal steroids and gonadotropins. The propagation velocity of phase III was slow and the contraction amplitude was high in both menstrual cycle phases compared with men, and these parameters were correlated with serum estrogen levels in the mid-L phase. In the early-F phase, migrating motor complex (MMC) cycle duration during sleep was long compared with other groups and positively correlated with estrogen concentrations, whereas in the mid-L phase MMC cycle duration during sleep was negatively correlated with serum progesterone levels. In all groups, the frequency of phase III contractions was low and the intercontractile interval measured from pressure peak to peak was long during sleep compared with the awake state. Postprandial motility did not display gender difference in any parameter examined. The results demonstrate that the majority of patterns of motility are similar in menstruating women and men, whereas certain aspects of the MMC, most conspicuously propagation velocity and phase III contraction amplitude, differ. We have also documented circadian variation of phase III contraction frequency in both women and men.     

Factor VIIa/tissue factor-induced signaling via activation of Src-like kinases, phosphatidylinositol 3-kinase, and Rac

Tissue factor (TF), apart from activating the extrinsic pathway of the blood coagulation, is a principal regulator of embryonic angiogenesis and oncogenic neoangiogenesis, but also influences inflammation, leukocyte diapedesis and tumor progression. The intracellular domain of TF lacks homology to other classes of receptors and hence the signaling mechanism is poorly understood. Here we demonstrate that factor VIIa (the natural ligand for TF) induces the activation of the Src family members c-Src, Lyn, and Yes, and subsequently phosphatidylinositol 3-kinase (PI3K), followed by stimulation of c-Akt/protein kinase B as well as the small GTPases Rac and Cdc42. In turn Rac mediates p38 mitogen-activated protein (MAP) kinase activation and cytoskeletal reorganization, whereas factor VIIa-induced p42/p44 MAP kinase stimulation required PI3K enzymatic activity but was not inhibited by dominant negative Rac proteins. We propose that this Src family member/PI3K/Rac-dependent signaling pathway is a major mediator of factor VIIa/TF effects in pathophysiology.     

A Novel Method for Tracking Individuals of Fruit Fly Swarms Flying in a Laboratory Flight Arena

The growing interest in studying social behaviours of swarming fruit flies, Drosophila melanogaster, has heightened the need for developing tools that provide quantitative motion data. To achieve such a goal, multi-camera three-dimensional tracking technology is the key experimental gateway. We have developed a novel tracking system for tracking hundreds of fruit flies flying in a confined cubic flight arena. In addition to the proposed tracking algorithm, this work offers additional contributions in three aspects: body detection, orientation estimation, and data validation. To demonstrate the opportunities that the proposed system offers for generating high-throughput quantitative motion data, we conducted experiments on five experimental configurations. We also performed quantitative analysis on the kinematics and the spatial structure and the motion patterns of fruit fly swarms. We found that there exists an asymptotic distance between fruit flies in swarms as the population density increases. Further, we discovered the evidence for repulsive response when the distance between fruit flies approached the asymptotic distance. Overall, the proposed tracking system presents a powerful method for studying flight behaviours of fruit flies in a three-dimensional environment.     

Proteomic analysis of symbiosome membranes in Cnidaria–dinoflagellate endosymbiosis

Symbiosomes are specific intracellular membrane‐bound vacuoles containing microalgae in a mutualistic Cnidaria (host)–dinoflagellate (symbiont) association. The symbiosome membrane is originally derived from host plasma membranes during phagocytosis of the symbiont; however, its molecular components and functions are not clear. In order to investigate the protein components of the symbiosome membranes, homogenous symbiosomes were isolated from the sea anemone Aiptasia pulchella and their purities and membrane intactness examined by Western blot analysis for host contaminants and microscopic analysis using various fluorescent probes, respectively. Pure and intact symbiosomes were then subjected to biotinylation by a cell impermeant agent (Biotin‐XX sulfosuccinimidyl ester) to label membrane surface proteins. The biotinylated proteins, both Triton X‐100 soluble and insoluble fractions, were subjected to 2‐D SDS‐PAGE and identified by MS using an LC‐nano‐ESI‐MS/MS. A total of 17 proteins were identified. Based on their different subcellular origins and functional categories, it indicates that symbiosome membranes serve as the interface for interaction between host and symbiont by fulfilling several crucial cellular functions such as those of membrane receptors/cell recognition, cytoskeletal remodeling, ATP synthesis/proton homeostasis, transporters, stress responses/chaperones, and anti‐apoptosis. The results of proteomic analysis not only indicate the molecular identity of the symbiosome membrane, but also provide insight into the possible role of symbiosome membranes during the endosymbiotic association.     

A study on the applicability of implantable microchip transponders for body temperature measurements in pigs

Background  

The applicability of an electronic monitoring system using microchip transponders for measurement of body temperatures was tested in 6-week-old conventional Danish weaners infected with classical swine fever virus (CSFV). Subcutaneous tissue temperatures obtained by the implantable transponders were compared with rectal temperatures, recorded by a conventional digital thermometer.