教学课程资源库 更多>>

关键词： Oxygen Deficiency   Arachidonic Acid   incorporation   Thymidine  

摘要： Hypoxia plays important roles in some early stages of mammalian embryonic development and in various physiological functions. This study examined the effect of arachidonic acid on short-period hypoxia-induced regulation of G(1) phase cell-cycle progression and inter-relationships among possible signalling molecules in mouse embryonic stem cells. Hypoxia increased the level of hypoxia-inducible factor-1 alpha (HIF-1 alpha) expression and H2O2 generation in a time-dependent manner. In addition, hypoxia increased the levels of cell-cycle regulatory proteins (cyclin D-1, cyclin E, cyclin-dependent kinase 2 (CDK2) and CDK4). Maximum increases in the level of these proteins and retinoblastoma phosphorylation were observed after 12-24 h of exposure to hypoxic conditions, and then decreased. Alternatively, the level of the CDK inhibitors, p21(Cip1) and p27(Kip1) were decreased. These results were consistent with the results of [H-3]-thymidine incorporation and cell counting. Hypoxia also increased the level of [H-3]-arachidonic acid release and inhibition of cPLA(2) reduced hypoxia-induced increase in levels of the cell-cycle regulatory proteins and [H-3]-thymidine incorporation. The level of cyclooxygenase-2 (COX-2) was also increased by hypoxia and inhibition of COX-2 decreased the levels of cell-cycle regulatory proteins and [H-3]-thymidine incorporation. Indeed, the percentage of cells in S phase, levels of cell cycle regulatory proteins, and [H-3]-thymidine incorporation were further increased in hypoxic conditions with arachidonic acid treatment compared to normoxic conditions. Hypoxia-induced Akt and mitogen-activated protein kinase (MAPK) phosphorylation was inhibited by vitamin C (antioxidant, 10(-3) M). In addition, hypoxia-induced increase of cell-cycle regulatory protein expression and [H-3]-thymidine incorporation were attenuated by LY294002 (PI3K inhibitor, 10(-6) M), Akt inhibitor (10(-6) M), rapamycin (mTOR inhibitor, 10(-9) M), PD98059 (p44/42 inhibitor, 10

关键词： embryonic neural stem or progenitor cells   HIF-1 alpha   hypoxia   proliferation  

摘要： We recently reported that intermittent hypoxia facilitated the proliferation of neural stem/progenitor cells (NPCs) in the subventricule zone and hippocampus in vivo. Here, we demonstrate that hypoxia promoted the proliferation of NPCs in vitro and that hypoxia-inducible factor (HIF)-1 alpha, which is one of the key molecules in the response to hypoxia, was critical in this process. NPCs were isolated from the rat embryonic mesencephalon (E13.5), and exposed to different oxygen concentrations (20% O-2, 10% O-2, and 3% O-2) for 3 days. The results showed that hypoxia, especially 10% O-2, promoted the proliferation of NPCs as assayed by bromodeoxyuridine incorporation, neurosphere formation, and proliferation index. The level of HIF-1 alpha mRNA and protein expression detected by RT-PCR and western blot significantly increased in NPCs subjected to 10% O-2. To further elucidate the potential role of HIF-1 alpha in the proliferation of NPCs induced by hypoxia, an adenovirus construct was used to overexpress HIF-1 alpha, and the pSilencer 1.0-U6 plasmid as RNA interference vector targeting HIF-1 alpha mRNA was used to knock down HIF-1 alpha. We found that overexpression of HIF-1 alpha caused the same proliferative effect on NPCs under 20% O-2 as under 10% O-2. In contrast, knockdown of HIF-1 alpha inhibited NPC proliferation induced by 10% O-2. These results demonstrated that moderate hypoxia was more beneficial to NPC proliferation and that HIF-1 alpha was critical in this process.

关键词： human implantation   endometrium   microarray   implantation markers  

摘要： Embryonic implantation is a dynamic process of paracrine interactions between the maternal compartment and the conceptus and involves a receptive endometrium and a developmentally competent blastocyst. Herein, we review histology, clinical approaches, and the promise of transcriptomics in elucidating mechanisms underlying implantation and development of biomarkers of uterine receptivity-with an eye to diagnose and treat implantation-based disorders of miscarriage, fetal growth restriction, pre-eclampsia, and infertility. Published by Elsevier Ltd.

关键词： H9c2 cells   Shh   HIF-1 alpha   hypoxia   ischemia  

摘要： Chronic cardiac ischemia/hypoxia induces coronary collateral formation and cardiomyocyte proliferation. Hypoxia can induce cellular adaptive responses, such as synthesis of VEGF for angiogenesis and IGF-2 for proliferation. Both reduce apoptotic effects to minimize injury or damage. To investigate the mechanism of neoangiogenesis and proliferation of fetal heart under umbilical cord compression situation, we used H9c2 cardiomyoblast cell culture, and in vivo embryonic hearts as our study models. Results showed hypoxia induced not only the increase of IGF-2 and VEGF expression but also the activation of their upstream regulatory genes, HIF-1 alpha and Shh. The relationship between HIF-1 alpha and Shh was further studied by using cyclopamine and 2-ME2, inhibitor of Shh and HIF-1 alpha signaling, respectively, in the cardiomyoblast cell culture under hypoxia. We found that the two inhibitors not only blocked their own signal pathway, but also inhibited each other. The observations revealed when fetal heart under hypoxia that HIF-1 alpha and Shh pathways maybe involve in cell proliferation and neoangiogenesis to minimize injury or damage, whereas the complex cross-talk between the two pathways remains unknown.

关键词： Gentiana sp.   leaf explants   somatic embryogenesis   adventitious roots  

摘要： Gentiana kurroo (Royle), Gentiana cruciata (L.), Gentiana tibetica (King. ex Hook. f.), Gentiana lutea (L.), and Gentiana pannonica (Scop.) leaves derived from axenic shoot culture were used as explants. For culture initiation, leaves from the first and second whorls from the apical dome were dissected and cultured on Murashige and Skoog (MS) basal medium supplemented with three different auxins: 2,4-dichlorophenoxyacetic acid, 1-naphthaleneacetic acid (NAA), or 3,6-dichloro-o-anisic acid (dicamba) in concentrations of 0.5, 1.0, or 2.0 mg/l;and five different cytokinins: zeatin, 6-furfurylamonopurine (kinetin), N-phenyl-N'-1,2,3-thiadiazol-5-ylurea (TDZ), N-(2-chloro-4-pyridyl)N'-phenylurea, or 6-benzylaminopurine (BAP). The cytokinin concentrations used were dependent on the type of cytokinin and varied between 0.25 and 3.0 mg/l. After 2 mo. of culture, the morphogenic response of explants was assessed. Frequency of embryogenesis was the highest for G. kurroo (54.7%) and dependent on plant growth hormones (PGRs). This gentian was the only species showing morphogenic capabilities on media supplemented with all applied combinations of PGRs, while none of the 189 induction media permutations stimulated somatic embryogenesis from G. lutea explants. G. tibetica and G. cruciata both produced an average of 6.6 somatic embryos per explant, while G. pannonica and G. kurroo regenerated at 15.7 and 14.2 somatic embryos per explant, respectively. Optimum regeneration was achieved in the presence of NAA combined with BAP or TDZ. This auxin also stimulated abundant rhizogenesis. Somatic embryos were also regenerated from adventitious roots of G. kurroo, G. cruciata, and G. pannonica. Somatic embryos converted into plantlets on half strength MS medium.

关键词： Dibenzyl trisulfide   Guinea hen weed   Petiveria alliacea L   somatic embryogenesis   HPLC   UV-spectral analysis   molecular farming  

摘要： A procedure for producing somatic embryos enriched with dibenzyl trisulfide (DTS) using a hormone-dependent culture system is reported for Petiveria alliacea L. (Guinea hen weed). Leaf explants were cultured on a Murashige and Skoog medium supplemented with a range of naphthaleneacetic acid (NAA) concentrations and a fixed concentration of benzyladenine (BAP) at 11.0 mu M and sucrose or glucose at 30 g l(-1). Leaf explants cultured on all media types started to form callus at the cut surfaces of the discs 10-14 d after initiation. The type of sugar used influenced average fresh weight, the propensity to form roots, as well as the embryogenic response. The highest mean fresh weight (337.7 +/- 26.18 mg) and mean root number (23.7 +/- 1.69) was produced on media enriched with sucrose and supplemented with 53.7 mu M NAA and 11.0 mu M BAP. An ethanol extract of rhizogenic/embryogenic callus or somatic embryos was subjected to high-performance liquid chromatography analysis, which revealed the presence of DTS in both extracts. UV spectral analysis and the use of standard quantitation procedures showed that the quantity of DTS in the somatic embryo extract, at 0.16% (w/v), was approximately 30-fold higher than in rhizogenic/embryogenic callus (0.0055% w/v) of similar fresh weight. These results indicate that it is possible to biosynthesize approximately 6 mg of natural DTS from 3,808 mg of fresh somatic embryos within 10 wk from less than three leaf explants.

关键词： pallium   subpallimn   telencephalon   Xenopus   LIM-homeodomain   homology   evolution  

摘要： In Xenopus laevis, we analyzed the origin of the projection neurons and interneurons in the developing olfactory bulbs by studying the expression patterns of the genes x-Eomes, x-Lhx5, x-Dll3 and x-Pax6. Olfactory bulb interneurons were characterized by using four conserved molecular markers for distinct subpopulations: gamma-aminobutyric acid, calretinin, calbindin, and tyrosine hydroxylase. Immunohistochemistry was combined with tract-tracing experiments to demonstrate the projection neurons and the interneurons of the olfactory bulbs simultaneously. Taken together, the results showed: (1) the pallial nature of the olfactory bulb and its projection neurons in Xenopus, like in mammals with comparable central projection areas, (2) the subpallial origin of the interneurons that, most likely, follow migratory pathways comparable to those described for mammals, (3) the different interneuron types possess neurochemical characteristics similar to mammals. Therefore, the present results show that the origin, chemoarchitecture and central connections of the olfactory bulbs are highly conserved in evolution. (c) 2007 Elsevier Inc. All rights reserved.

关键词： Foetal   growth aspects   Altitude   Oxygen Deficiency   高海拔   oxygen delivery   Hypoxia   Pregnancy   Fetus   Chick Embryo   high altitude   altitudinal   Oxygen transfer   Fetal Growth   Birth Weight  

摘要： The compelling evidence that associates small size at birth with later cardiovascular disease in humans (Barker, 1998) encourages research into the determinants of fetal growth. It is generally accepted that both nutrient and oxygen supply to the fetus are important factors that modulate whether the genetic potential for fetal growth is achieved. In humans, fetal hypoxia occurs during pregnancy at high altitude (Moore, 1990) or under pathological pregnancies at sea level complicated by placental insufficiency (Baschat, 2004). In both cases, it has been shown that birth weight is reduced (Moore et al. 2004; Barker, 1998, respectively). However, in the former there may be confounding factors of altitudinal impoverishment, hypothermia and hypo-baria, and in the latter, decreases in fetal nutrient and oxygen transfer occur simultaneously, such that the cause of the reduced birth weight cannot be discerned.

关键词： TGF-beta   CTGF/CCN2   fibrosis   fibroblast   type I collagen  

摘要： Background. The matricellular protein connective tissue growth factor (CCN2) has been implicated in pathological Fibrosis, but its physiologic role remains elusive. in vitro, transforming growth factor-beta (TGF-beta) induces CCN2 expression in mesenchymal cells. Because CCN2 can enhance profibrotic responses elicited by TGF-beta, it has been proposed that CCN2 functions as an essential downstream signaling mediator for TGF-beta. To explore this notion, we characterized TGF-beta-induced activation of fibroblasts from CCN2-null (CCN2(-/-)) mouse embryos. Methods. The regulation of CCN2 expression was examined in vivo in a model of fibrosis induced by bleomycin. Cellular TGF-beta signal transduction and regulation of Collagen gene expression were examined in CCN2(-/-) MEFs by immunohistochemistry, Northern, Western and RT-PCR analysis, immunocytochemistry and transient transfection assays. Results. Bleomycin-induced skin fibrosis in the mouse was associated with substantial CCN2 up-regulation in lesional fibroblasts. Whereas in vitro proliferation rate of CCN2(-/-) MEFs was markedly reduced compared to wild type MEFs, TGF-beta-induced activation of the Smad pathways, including Smad2 phosphorylation, Smad2/3 and Smad4 nuclear accumulation and Smad-dependent transcriptional responses, were unaffected by loss of CCN2. The stimulation of COL1A2 and fibronectin mRNA expression and promoter activity, and of corresponding protein levels, showed comparable time and dose-response in wild type and CCN2(-/-) MEFs, whereas stimulation of alpha smooth muscle actin and myofibroblast transdifferentiation showed subtle impairment in MEFs lacking CCN2. Conclusion. Whereas endogenous CCN2 plays a role in regulation of proliferation and TGF-beta-induced myofibroblast trans differentiation, it appears to be dispensable for Smad-dependent stimulation of collagen and extracellular matrix synthesis in murine embryonic fibroblasts. (c) 2007 Elsevier Inc. All rights reserved.

关键词： 网络课程   组织学   胚胎学   建设   应用  

摘要： 组织学与胚胎学是研究机体的微细结构及相关功能的学科,是一门重要的医学形态学基础课。其特点是理论性与实践性较强,理论知识抽象,专业名词和概念多,繁杂难记,容易混淆,形态描述困难。加之,教学时数少、传统的教学方法又存在一些弊端等因素,导致组织学与胚胎学这门课程历年来被学生认为是最难学的医学基础课程之一。[第一段]