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关键词： 彩色图谱   胚胎学   生物学   组织学   显微解剖学   解剖学   出版  

关键词： Agrobacterium tumefaciens   antibiotic   beta-glucuronidase gene   genetic transformation   Pinus taeda L.  

摘要： Three antibiotics were evaluated for their effects on the elimination of Agrobacterium tumefaciens during the genetic transformation of loblolly pine (Pinus taeda L.) using mature zygotic embryos as targets. Agrobacterium tumefaciens strains, EHA105, GV3101, and LBA 4404, all harbouring the plasmid pCAMBIA1301, which carries the selectable marker gene, hygromycin phosphotransferase (hpt) controlled by the cauliflower mosaic virus 35S promoter and terminator, and the uidA reporter gene (GUS) driven by the cauliflower mosaic virus 35S promoter and the terminator of nopaline synthase gene, were used in this study. Exposure to 350 mg l(-1) carbenicillin, claforan, and timentin respectively for up to 6 weeks did not eliminate the Agrobacterium, while antibiotics at 500 mg l(-1) eradicated them from the co-cultivated zygotic embryos. All three antibiotics increased callus growth and shoot regeneration at 350 and 500 mg l(-1) each, but reduced callus growth and shoot regeneration at 650 mg l(-1) when compared with controls. Putative transgenic calli were selected for continued proliferation and differentiation on 4.5 mg l(-1) hygromycin-containing medium. Transformed calli and transgenic plants produced on a selection medium containing 4.5 mg l(-1) hygromycin were confirmed by GUS histochemical assays, by polymerase chain reaction (PCR), and by Southern blot analysis. These results are useful for future studies on optimizing genetic transformation procedures in loblolly pine.

关键词： cartilage   chondrogenesis   hdf   limb development   nerve migration   versican  

摘要： Lateral plate mesoderm is native to the developing limb while other cells such as neurons extend migratory axonal processes from the neural tube. Questions regarding how axons migrate to their proper location in the developing limb remain unanswered. Extracellular matrix molecules expressed in developing limb cartilages, such as the versican proteoglycan, may function as inhibitory cues to nerve migration, thus facilitating its proper patterning. In the present study, a method is described for co-culture of neural tissue with high density micromass preparations of mouse limb mesenchyme in order to investigate neurite patterning during limb chondrogenesis in vitro. Comparison of hdf (heart defect) mouse limb mesenchyme, which bears an insertional mutation in the versican proteoglycan core protein, with wild type demonstrated that the described technique provides a useful method for transgenic analysis in studies of chondrogenic regulation of neurite patterning. Differentiating wild type limb mesenchyme expressed cartilage characteristic Type II collagen and versican at 1 day and exhibited numerous well defined cartilage foci by 3 days. Wild type neurites extended into central regions of host cultures between 3 and 6 days and consistently avoided versican positive chondrogenic aggregates. Wild type neural tubes cultured with hdf limb mesenchyme, which does not undergo cartilage differentiation in a wild type pattern, showed that axons exhibited no avoidance characteristics within the host culture. Results suggest that differentiating limb cartilages may limit migration of axons thus aiding in the ultimate patterning of peripheral nerve in the developing limb.

关键词： organiser   axial mesoderm   embryonic patterning   signalling activity   mouse embryo  

摘要： Embryonic patterning of the mouse during gastrulation and early organogenesis engenders the specification of anterior versus posterior structures and body laterality by the interaction of signalling and modulating activities. A group of cells in the mouse gastrula, characterised by the expression of a repertoire of "organiser" genes, acts as a source and the conduit for allocation of the axial mesoderm, floor plate and definitive endoderm. The organiser and its derivatives provide the antagonistic activity that modulates WNT and TGFbeta signalling. Recent findings show that the organiser activity is augmented by morphogenetic activity of the extraembryonic and embryonic endoderm, suggesting embryonic patterning is not solely the function of the organiser. (C) 2004 Elsevier Ltd. All rights reserved.

关键词： akt   apoptosis   Flk-1/KDR   heart   hypoxia-inducible factor   vascular endothelial growth factor   remodeling  

摘要： We proposed a model in which myocardial hypoxia triggers the apoptosis-dependent remodeling of the avian outflow tract (OFT) in the transition of the embryo to a dual circulation. In this study, we examined hypoxia-dependent signaling in cardiomyocyte apoptosis and outflow tract remodeling. The hypoxia-inducible transcription factor HIF-1alpha was specifically present in the nuclei of OFT cardiomyocytes from stages 25-32, the period of hypoxia-dependent OFT remodeling. HIF-1alpha expression was sensitive to changes in ambient oxygen concentrations, while its dimerization partner HIF-1beta was constitutively expressed. There was not a simple relationship between HIF-1alpha expression and apoptosis. Apoptotic cardiomyocytes were detected in HIF-1alpha-positive and -negative regions, and a hypoxic stimulus sufficient to induce nuclear accumulation of HIF-1alpha did not induce cardiomyocyte apoptosis. The hypoxia-dependent expression of the vascular endothelial growth factor receptor (VEGFR2) in the distal OFT myocardium may be protective as cardiomyocyte apoptosis in the early stages (25-30) of OFT remodeling was absent from this region. Furthermore, recombinant adenoviral-mediated expression of dominant negative Akt, an inhibitor of tyrosine kinase receptor signaling, augmented cardiomyocyte apoptosis in the OFT and constitutively active Akt suppressed it. Adenovirus-mediated forced expression of VEGF 165 induced conotruncal malformation such as double outlet right ventricle (DORV) and ventricular septal defect (VSD), similar to defects observed when apoptosis-dependent remodeling of the OFT was specifically targeted. We conclude that normal developmental remodeling of the embryonic avian cardiac OFT involves hypoxia/HIF-1-dependent signaling and cardiomyocyte apoptosis. Autocrine signaling through VEGF/VEGFR2 and Akt provides survival signals for the hypoxic OFT cardiomyocytes, and regulated VEGF signaling is required for the normal development of the OFT. (C) 2004 E

关键词： HYPOXIA (Water)   DISSOLVED oxygen in water   EMBRYOS   EMBRYOLOGY   FISHES   SEX hormones  

摘要： Hypoxia occurs over large areas in aquatic systems worldwide, and there is growing concern that hypoxia may affect aquatic animals, leading to population decline and changes in community by elimination of sensitive species. For the first time, we report that sublethal levels of hypoxia can significantly increase (+77.4%) malformation in fish embryonic development. Disruption of apoptotic pattern was clearly evident at 24 h post-fertilization, which may be a major cause of malformation. Furthermore, embryonic development was delayed, and balance of sex hormones (testosterone and estradiol) was disturbed during embryonic stages, implicating that subsequent sexual development may also be affected. Overall, our results imply that hypoxia may have a teratogenic effect on fish and delay fish embryonic development, which may subsequently impair species fitness leading to natural population decline.

关键词： 组织胚胎学   医学教学   教案书写   学习方法   多媒体教学  

摘要： 组织胚胎学是一门重要的医学基础课，属于形态学科之一。教学内容抽象枯燥，结构细微，医学名词繁多，对于大学一年级的学生来说，难度是可想而知的。通过教学中这几年的摸索和总结，就组织胚胎学教学中的几个问题谈一下自己的体会。

关键词： 组织学   胚胎学   教学实验室   开放式实验   实验设备   组织切片  

摘要： 实验教学是理论教学的必要补充和深化，是教学的重要环节。组织学是一门形态学科，要求对大量细胞、组织、器官的光镜和电镜结构进行认识，尽管我校本科和专科教学中理论课与实验课的教学比例已达到2：3或2：2，但仍不能满足学生观察组织切片的要求，学生也应该通过多观察组织切片和图片来更

关键词： 实验教学改革   实践环节   考试方法   初探   教学方法   实验课教学   组织胚胎学   改进  

摘要： 改革组胚实验课教学 ,必须加强实践环节 。

关键词： B超   胚胎组织残留   诊断  

摘要： 目的　探讨B超在诊断宫内胚胎组织残留中的应用价值及宫内胚胎组织残留的超声图像特征。方法　采用ALOKASSD - 1 4 0 0型超声诊断仪 ,对 1 0 2例临床拟诊为宫内胚胎组织残留的患者进行超声检查。结果　超声诊断阳性率为 90 2 % ,与术后病理诊断符合率为 92 2 %。结论　宫内胚胎组织残留具有一定的声像图表现 ,超声可做出较准确的诊断 。