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Cnidarian nervous systems utilize chemical transmission to transfer signals through synapses and neurons. To date, ample evidence has been accumulated for the participation of neuropeptides, primarily RFamides, in neurotransmission. Yet, it is still not clear if this is the case for the classical fast neurotransmitters such as GABA, Glutamate, Acetylcholine and Monoamines. A large repertoire of cnidarian Fast Neurotransmitter related Genes (FNGs) has been recently identified in the genome of the sea anemone, Nematostella vectensis. In order to test whether FNGs are localized in cnidarian neurons, we characterized the expression patterns of eight Nematostella genes that are closely or distantly related to human central and peripheral nervous systems genes, in adult Nematostella and compared them to the RFamide localization. Our results show common expression patterns for all tested genes, in a single endodermal cell layer. These expressions did not correspond with the RFamide expressing nerve cell network. Following these results we suggest that the tested Nematostella genes may not be directly involved in vertebrate-like fast neurotransmission.  相似文献   

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We investigated the gene expression changes in rat hepatic restoration with Rat Genome 230 2.0 chip containing 11,789 known genes and 13,231 unknown genes (taking up 90 percent of rat whole genome) following a 2/3 hepatectomy. The expression profiles and roles of these genes in rat liver regeneration (LR) were assayed using bioinformatics and systems biology method. Among the above genes, 1,004 known genes and 857 unknown genes were found to be associated with rat LR. The numbers of the known genes up-regulated, down-regulated, and up/down-regulated were 622, 443, and 15, respectively; that of the unknown genes were 367, 400, and 14, respectively. Out of the above two groups of genes, the ones up- and down-regulated 20 times or more were 62 and 38, 8, and 14, respectively. Notably, The highest expression level of dehydrogenase/reductase member 7 (DHRS7) was more than 968-fold compared to control, and alpha-1-B glycoprotein (A1BG), the product of gene with the lowest expression abundance, was 58 times lower than control. During rat liver regeneration, 467 up–regulated, 282 down–regulated, 10 up/down-regulated genes, and 1,031 undetected genes in our study interacted with each other and formed a network with a total of 4,014 connectivities. Among them, the genes for the regulation, synthesis, transport, signal transduction, protein modification, and physiological response formed 630, 290, 691, 373, 2010, and 20 connectivities, respectively; and the genes jun, fos, myc, ptgs2, ccna2, ccl2 had relatively higher degree of connectivity. The results indicated that cell apoptosis and inflammatory response were enhanced in the initial phase and the early part of progressive phase in LR.  相似文献   

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The patterning and differentiation of the vertebrate endoderm requires signaling from adjacent tissues. In this report, we demonstrate that signals from the notochord are critical for the development of the hypochord, which is a transient, endodermally derived structure that lies immediately ventral to the notochord in the amphibian and fish embryo. It appears likely that the hypochord is required for the formation of the dorsal aorta in these organisms. We show that removal of the notochord during early neurulation leads to the complete failure of hypochord development and to the elimination of expression of the hypochord marker, VEGF. Removal of the notochord during late neurulation, however, does not interfere with hypochord formation. These results suggest that signals arising in the notochord instruct cells in the underlying endoderm to take on a hypochord fate during early neural stages, and that the hypochord does not depend on further notochord signals for maintenance. In reciprocal experiments, when the endoderm receives excess notochord signaling, a significantly enlarged hypochord develops. Overall, these results demonstrate that, in addition to patterning neural and mesodermal tissues, the notochord plays an important role in patterning of the endoderm.  相似文献   

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Knowing Music, Making Music: Javanese Gamelan and the Theory of Musical Competence and Interaction. Benjamin Brinner. Chicago: University of Chicago Press, 1995. 363 pp.  相似文献   

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The mechanisms involved in the regulation of gene expression in eukaryote cells, although an area of active research, are still largely unknown. This is at least partly due to the lack of good experimental model systems. One type of system which is being exploited with some considerable success is the induction of proteins by steroid hormones. Studies on the effects of estrogen and progesterone on the synthesis of the egg white proteins in the chick oviduct, for instance, have yielded substantial insight into both the regulation of protein synthesis by steroid hormones [1] and the arrangement of the DNA sequences coding for these proteins [2, 3].
The need for other good inducible systems clearly exists and the induction of vitellogenin, the precursor of the major egg yolk proteins, by estrogen in the livers of the chicken and frog ( Xenopus laevis ) is one that is attracting increasing interest. In common with the chick oviduct, large amounts of a specific protein are synthesised in response to a well defined hormonal stimulus. However, the induction of vitellogenin also has the advantage that the response is not complicated by the extensive hyperplasia that follows estrogen treatment in the chick oviduct [4, 5] and that vitellogenin may be induced in vitro [6–11].
The aims of this review are first to discuss recent data on the induction of vitellogenin and vitellogenin mRNA both in vivo and in vitro and then to relate this data to the properties of the estrogen receptor, present in chicken and Xenopus liver, which is thought to mediate the induction of vitellogenin by estrogen.  相似文献   

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Previous studies with tissue recombination experiments demonstrated that the splanchnic mesenchymes, including hepatic, pulmonary and stomach mesenchymes can support hepatocyte differentiation from the hepatic endoderm in 9.5-day mouse embryos. This phenomenon corresponds to the second hepatic induction. The present study was undertaken to determine whether direct cell-cell contacts between the hepatic endoderm and mesenchyme are required for hepatocyte differentiation, using transfilter experiments in which membrane filters with various pore sizes were inserted between the endoderm and the hepatocyte-inducing mesenchyme (the chick lung mesenchyme). Hepatocyte differentiation occurred even when the direct cell-cell contacts between the hepatic endoderm and the mesenchyme were absent, suggesting that humoral factors may work in this interaction. However, growth of hepatocytes was most prominent in the transfilter experiments with filters having pore sizes of 0.2 and 0.8 mum, which permitted mesenchymal cells or their cell processes to penetrate to the side of the endoderm. These results suggest that two types of tissue interactions, including humoral mesenchymal factors and very local tissue interactions such as direct cell-cell contacts, may be involved in the second step of hepatic induction.  相似文献   

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When F9 stem cells are treated in suspension with retinoic acid, they differentiate into embryoid bodies (EBs) consisting of an inner core of undifferentiated stem cells surrounded by an outer layer of visceral endoderm (VE). When these EBs are plated onto a fibronectin (FN)-coated substrate, VE-derived parietal endoderm (PE) cells migrate onto the substrate. It has been suggested that increased levels of tPA associated with the emerging PE cells may help mediate PE outgrowth. We now show that goat anti-human tPA, an anticatalytic antibody that crossreacts with mouse tPA, and a panel of serine protease inhibitors partially inhibit PE outgrowth. Extracellular matrix (ECM) degradation analysis demonstrates that PE cell-mediated degradation of [3H]proline-labeled ECM is time- and cell concentration-dependent. A serine protease inhibitor reduced the extent of degradation, suggesting that tPA might play a role in PE outgrowth by cleaving the ECM. In support of this contention, we demonstrate that incubation of purified FN with conditioned medium plus plasminogen results in FN proteolysis. The degradation of FN is blocked by either serine protease inhibitors or goat anti-human tPA. Our data suggest that enhanced production of tPA during PE outgrowth may facilitate the migratory behavior of PE cells by mediating the degradation of ECM components such as FN.  相似文献   

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BackgroundDefinitive endoderm (DE) is one of the three germ layers which during in vivo vertebrate development gives rise to a variety of organs including liver, lungs, thyroid and pancreas; consequently efficient in vitro initiation of stem cell differentiation to DE cells is a prerequisite for successful cellular specification to subsequent DE-derived cell types [1, 2]. In this study we present a novel approach to rapidly and efficiently down regulate pluripotency genes during initiation of differentiation to DE cells by addition of dimethyl sulfoxide (DMSO) to Activin A-based culture medium and report its effects on the downstream differentiation to hepatocyte-like cells.ResultsAddition of DMSO to the Activin A-based medium during DE specification resulted in rapid down regulation of the pluripotency genes OCT4 and NANOG, accompanied by an increase expression of the DE genes SOX17, CXCR4 and GATA4. Importantly, the expression level of ALB in DMSO-treated cells was also higher than in cells which were differentiated to the DE stage via standard Activin A treatment.  相似文献   

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SYNOPSIS. Cell-free fluid from sexually reactive cultures of Tetrahymena pyriformis, syngen 7 can induce mating in otherwise unreactive mixtures of cells of 2 mating types. Rare individual cells may initiate the production of this substance, but once it is produced, the entire culture becomes sexually reactive.  相似文献   

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The role of medical anthropology in tackling the problems and challenges at the intersections of public health, medicine, and technology was addressed during the 2009 Society for Medical Anthropology Conference at Yale University in an interdisciplinary panel session entitled Training, Communication, and Competence: The Making of Health Care Professionals.The discipline of medical anthropology is not very formalized in the health setting. Although medical anthropologists work across a number of health organizations, including schools of public health, at the Centers for Disease Control (CDC), and at non-governmental organizations (NGOs), there is an emerging demand for an influential applied medical anthropology that contributes both pragmatically and theoretically to the health care field.The role of anthropology at the intersections of public health, medicine, and technology was addressed during the 2009 Society for Medical Anthropology Conference at Yale University in September. In a conference session entitled Training, Communication, and Competence: The Making of Health Care Professionals, health professional career issues, including training and education, medical entrepreneurship, and the maintenance of clinical relationships with patients were examined. The presentations encompassed macro approaches to institutional reform in training, education, and health care delivery, as well as micro studies of practitioner-patient interaction. Seemingly disparate methodological, disciplinary, and theoretical orientations were united to assess the increasing relevance of medically oriented anthropology in addressing the challenges of health care delivery, health education, and training.Margaret Bentley, a professor of public health at the University of North Carolina, Chapel Hill, spoke about the increasing “epidemic of global health” in universities, noting a doubling of global health majors within the past three years. Despite this expansion of the field, a common discipline of global health continues to be developed. In September, the Association of Schools of Public Health (ASPH) and the University of Minnesota hosted a Global Health Core Competency Development Consensus Conference with the initiative to explore “workforce needs, practice settings, and to identify core constructs, competency domains, and a preliminary global health competency model”1. Given the current variability in training, Bentley believes medical anthropology is uniquely suited to inform training in global health because of its offerings in the way of interdisciplinary methods and team-based applied field experience.Anthropologists Carl Kendall of Tulane University and Laetitia Atlani of Université de Paris X Nanterre have seen medical anthropologists examine models of health strictly within a clinical experience. Understanding of the social determinants of epidemiology, methodological issues of population health, and survey research is crucial. However, training individuals through a more formalized program (currently in development in Europe) will allow anthropologists to better understand context, explain complex models, humanize aggregate statistics, and articulate methods of the multidimensional “social field” of health outside of the clinical experience.The social field of health, however, as Robert Like of the University of Medicine and Dentistry of New Jersey explained, shares an uncomfortable interface with clinical medicine. Recent efforts by the New Jersey Board of Examiners to incorporate cultural competency legislation have been robustly criticized. Evaluations of six-hour training sessions on cultural competency training have revealed health professionals’ frustration with the health care system’s inability to deal with “culturally different” individuals. In fact, the majority of health professionals who were required to complete the training believe cultural competency to be an area of study that is a “waste of time.”This opposition to cross-cultural education and the value of “cultural competence” training also has been a topic of great debate among anthropologists and health researchers. Despite the ubiquitous use of the term among research and health professionals, cultural competency is a term that cannot be defined precisely enough to operationalize.In “Anthropology in the Clinic: The Problem of Cultural Competency and How to Fix It,” Arthur Kleinman and Peter Benson asserted that the static notion of culture in the medical field “suggests that a culture can be reduced to a technical skill for which clinicians can be trained to develop expertise” [1]. T.S. Harvey, a linguistic and medical anthropologist at the University of California, Riverside, expounded on Kleinman’s opposition to competence as an acquired “technical skill” [1] and suggested reconceptualizing the approach to competence as communication. Although Kleinman’s explanatory models approach [2] provides a health care professional with what to ask the patient, Harvey pulls from Dell Hymes’ communicative competence [3] to understand how to ask it. Harvey recommended viewing competence as a “sociolinguistic acquisition … like a foreign language” where competencies are rule-governed and communication and speech events are formulaic.Harvey also noted that the “onus of cultural competency” is too often placed on the practitioner. Inevitably, there is an asymmetry in every clinical encounter, whereby the “would-be patient” is perpetually considered the “passive receptor.” Patients also share a stake in their health and, as such, should be taught communicative competence as well.Harvey also noted that the “onus of cultural competency” is too often placed on the practitioner. Inevitably, there is an asymmetry in every clinical encounter, whereby the “would-be patient” is perpetually considered the “passive receptor.” Patients also share a stake in their health and, as such, should be taught communicative competence as well.The role of the patient is made ever more complex by the power relationship that exists in the patient-provider context. Through ethnographic research, Sylvie Fainzang, director of research in the Inserm (Cermes), examines how doctors and patients lie. She argues that lying, in the context of secrecy, is an indication of a power relationship [4]. Fainzaing’s further research on the relationship between doctors and patients has yielded additional information on how patients learn about their diagnoses and how they will react to these diagnoses. Though a clinical encounter between a doctor and patient is expected to be one of informed consent, doctors often judge patients upon their ability to “intellectually understand” [4] and assess who is “psychologically ready” [4] to bear the information. This leads to manipulated, misinformed, and “resigned consent” [4]. This sort of social training of obligation of a subject to medical authority provides the patient with the choice either to conform or overthrow the rules as defined by society.Collectively, this interdisciplinary panel worked to inform the discussion on how medical anthropology can address training, communication, and competence at the intersections of medicine, public health, and education. By reviewing health professionals’ growing interest in public health, training in health education and competence, and the patient-provider relationship, medical anthropology can be seen as both relevant and necessary to addressing the challenges faced by the medical and health community today.  相似文献   

14.
Foregut Formation of the Nemerteans and Its Role in Nemertean Systematics   总被引:4,自引:0,他引:4  
Along a line of the four nemertean orders, Archi-, Palaeo-,Hetero-, and Hoplonemertea established by Iwata, formation ofthe foregut is described in detail on the basis of data hithertorecorded. The axiality of the egg, larva and adult worm of aspecies may change as a function of foregut morphogenesis inthe embryo. During foregut formation the mouth moves from thevegetal pole to the ventral side of the body. In Archinemertea,the larva has an angle of 60° formed by the long axis ofthe body and the foregut, while in Palaeonemertea the angleis 45°. This relationship is retained in the adult. Theplacement of the mouth thus obtained in the larva and adultworm seems to be important for the systematics of the Nemertea,especially for the Archinemertea and Palaeonemertea.  相似文献   

15.
Despite an abundance of studies on chromatin states and dynamics, there is an astonishing dearth of information on the expression of genes responsible for regulating histone and DNA modifications. We used here a set of 156 defined epigenetic modifier genes (EMG) and profiled their expression pattern in cells of different lineages. As reference value, expression data from human embryonic stem cells (hESC) were used. Hepatocyte-like cells were generated from hESC, and their EMG expression was compared to primary human liver cells. In parallel, we generated postmitotic human neurons (Lu d6), and compared their relative EMG expression to human cortex (Ctx). Clustering analysis of all cell types showed that neuronal lineage samples grouped together (94 similarly regulated EMG), as did liver cells (61 similarly-regulated), while the two lineages were clearly distinct. The general classification was followed by detailed comparison of the major EMG groups; genes that were higher expressed in differentiated cells than in hESC included the acetyltransferase KAT2B and the methyltransferase SETD7. Neuro-specific EMGs were the histone deacetylases HDAC5 and HDAC7, and the arginine-methyltransferase PRMT8. Comparison of young (Lu d6) and more aged (Ctx) neuronal samples suggested a maturation-dependent switch in the expression of functionally homologous proteins. For instance, the ratio of the histone H3 K27 methyltransfereases, EZH1 to EZH2, was high in Ctx and low in Lu d6. The same was observed for the polycomb repressive complex 1 (PRC1) subunits CBX7 and CBX8. A large proportion of EMGs in differentiated cells was very differently expressed than in hESC, and absolute levels were significantly higher in neuronal samples than in hepatic cells. Thus, there seem to be distinct qualitative and quantitative differences in EMG expression between cell lineages.  相似文献   

16.
Abstract Ciliary folds form the dorsolateral walls of the foregut in numerous polychaetes. These feeding structures have not been recognized earlier. They are described here for 26 species in 16 families. The folds consist of ciliated cells, usually associated with gland cells, and have no intrinsic muscular system. Protraction of the dorsolateral folds to make contact with the substratum during uptake of food is mainly achieved by contractions of the musculature of the body wall in the anterior part of the body. These folds either occur alone or are associated with a ventral pharyngeal organ. Dorsolateral ciliated folds are structures originally adapted to microphagy. From the present study and the literature it is obvious that these structures are widespread among polychaetes of various taxa. This distribution and their similar structure suggest that dorsolateral folds are phylogenetically old structures which might already have been present in the stem species of polychaetes.  相似文献   

17.
高原鼢鼠肝脏组织细胞周期相关基因的进化和表达   总被引:1,自引:0,他引:1  
高原鼢鼠Myospalax baileyi是一种世居青藏高原的地下鼠,对严重的低氧环境有很强的适应性。低氧诱导细胞周期G1、G2期阻滞。为了探讨高原鼢鼠适应低氧环境的分子机制,应用生物信息学方法对p53下游细胞周期基因p21、CyclinD1、CyclinE、CDK6、CDK2、14-3-3-σ、Gadd45α、B99和CyclinB1的序列和编码的氨基酸序列进行了进化分析,并以SD大鼠Rattus norvegicus为对照,研究了这些基因在不同海拔(3 300 m、2 260 m)条件下的表达模式。结果表明:(1)高原鼢鼠细胞周期相关基因的序列与以色列鼹鼠Nannospalax galili同源性最高,达到90%以上;p21、CyclinD1、CyclinE和CyclinB1编码蛋白与以色列鼹鼠存在明显的趋同进化位点;SIFT评估发现,p21和CyclinB1氨基酸序列分别在第27号位点和第105号位点的变异对细胞周期调控功能有显著影响;(2)与低海拔条件相比,在高海拔条件下,高原鼢鼠肝脏组织中与G1期相关的基因p21表达水平显著上升,p21下游基因CyclinD1、CyclinE...  相似文献   

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The fine structure of the salivary glands of Cymatium intermediusis described. It isconcluded that both the posterior acid secretingand anterior acinous lobes are homologous withthe salivaryglands of other prosobranchs. At least six different types ofsecretion have beenidentified and their possible roles discussed.The anterior lobes secrete mucin and proteinsbelieved to beenzymes, and the posterior lobes are specialized for acid productionas well assecreting protein (probably a peptide toxin). Themechanisms of acid secretion and protectionfrom damage to thesnail before its release are also considered. (Received 12 January 1998; accepted 1 March 1998)  相似文献   

20.
In vitro mariner transposon mutagenesis of Streptococcus pneumoniae chromosomal DNA was used to isolate regulatory mutants affecting expression of the comCDE operon, encoding the peptide quorum-sensing two-component signal transduction system controlling competence development. A transposon insertion leading to increased comC expression was found to lie directly upstream from the S. pneumoniae clpP gene, encoding the proteolytic subunit of the Clp ATP-dependent protease, whose expression in Bacillus subtilis is controlled by the CtsR repressor. In order to examine clp gene regulation in S. pneumoniae, a detailed analysis of the complete genome sequence was performed, indicating that there are five likely CtsR-binding sites located upstream from the clpE, clpP, and clpL genes and the ctsR-clpC and groESL operons. The S. pneumoniae ctsR gene was cloned under the control of an inducible promoter and used to demonstrate regulation of the S. pneumoniae clpP and clpE genes and the clpC and groESL operons by using B. subtilis as a heterologous host. The CtsR protein of S. pneumoniae was purified and shown to bind specifically to the clpP, clpC, clpE, and groESL regulatory regions. S. pneumoniae Delta ctsR, Delta clpP, Delta clpC, and Delta clpE mutants were constructed by gene deletion/replacement. ClpP was shown to act as a negative regulator, preventing competence gene expression under inappropriate conditions. Phenotypic analyses also indicated that ClpP and ClpE are both required for thermotolerance. Contrary to a previous report, we found that ClpC does not play a major role in competence development, autolysis, pneumolysin production, or growth at high temperature of S. pneumoniae.  相似文献   

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