Flow cytometric analysis of European flat oyster, Ostrea edulis, haemocytes using a monoclonal antibody specific for granulocytes

The importance of haemocytes in mollusc defence mechanisms can be inferred from their functions. They participate in pathogen elimination by phagocytosis (Cheng, 1981; Fisher, 1986). Hydrolytic enzymes and cytotoxic molecules produced by haemocytes contribute to the destruction of pathogenic organisms (Cheng, 1983; Leippe & Renwrantz, 1988; Charlet et al., 1996; Hubert et al., 1996; Roch et al., 1996). Haemocytes may also be involved in immunity modulation by the production of cytokines and neuropeptides (Hughes et al., 1990; Stefano et al., 1991; Ottaviani et al., 1996). As a result, the literature dealing with bivalve haemocyte studies has increased during the last two decades. Most of these publications use microscopy for morphological analysis (Seiler & Morse, 1988; Auffret, 1989; Hine & Wesney, 1994; Giamberini et al., 1996; Carballal et al., 1997; Lopez et al., 1997; Nakayama et al., 1997), and functional analysis (e.g. phagocytosis) (Hinsch & Hunte, 1990; Tripp, 1992; Mourton et al., 1992; Fryer & Bayne, 1996; Mortensen & Glette, 1996). Flow cytometry represents a rapid technique applicable to both morphological and functional studies of cells in suspension. While the measurements based on autofluorescence provide information on cell morphology, the analyses with fluorescent markers including labelled antibodies, offer data on phenotyping and cell functions. As a result, its application has greatly contributed to the investigation of immunocyte functions and differentiation in vertebrates (Stewart et al., 1986; Rothe & Valet, 1988; Ashmore et al., 1989; Koumans-van Diepen et al., 1994; Rombout et al., 1996; Caruso et al., 1997). Some authors studied oyster haemocyte populations by flow cytometry based on cellular autofluorescence (Friedl et al., 1988; Fisher & Ford, 1988; Ford et al., 1994). However, no analysis using specific monoclonal antibodies has been reported to date. In this study, a protocol for studying European flat oyster, Ostrea edulis, haemocytes by flow cytometry using a monoclonal antibody specific for granulocytes and an indirect immunofluorescence technique have been developed. European flat oysters, Ostrea edulis, 7-9 cm in shell length were obtained from shellfish farms in Marenne Oléron bay (Charente Maritime, France) on the French Atlantic coast. All individuals were purchased just before each experiment and processed without any previous treatment.     

Studies on oligosaccharyl transferase in yeast

In yeast, OT consists of nine different subunits, all of which contain one or more predicted transmembrane segments. In yeast, five of these proteins are encoded by essential genes, Swp1p, Wbp1p, Ost2p, Ost1p and Stt3p. Four others are not essential Ost3p, Ost4p, Ost5p, Ost6p. All yeast OT subunits have been cloned and sequenced (Kelleher et al., 1992; 2003; Kelleher & Gilmore, 1997; Kumar et al., 1994; 1995; Breuer & Bause, 1995) and the structure of one of them, Ost4p, has been solved by NMR (Zubkov et al., 2004). Very recently, the preliminary crystal structure of the lumenal domain of an archaeal Stt3p homolog has been reported (Mayumi et al., 2007). Homologs of all OT subunits have been identified in higher eukaryotic organisms (Kelleher et al., 1992; 2003; Kumar et al., 1994; Kelleher & Gilmore, 1997).     

What can we Learn from Oxygen and Hydrogen Isotope Compositions of Tree-ring Cellulose in Higher Plants (英文)

Stable isotope ratios in tree-ring cellulose have been shown to be reliable recorders of changes in the ambient climate (Leuenberger et al., 1998). Thus, isotopic fractionations associated with both physical and biochemical processes during cellulose synthesis in higher plants (Epstein & Krishnaumurthy, 1990; Roden et al., 2000; Saurer et al., 1997a; 1997b; 2000) can be used as archives for past climatic indicators. Superimposed on the climatic induced isotopic signal are the long-term responses of plant physiological processes to past changes in environmental conditions including CO2 enrichment.     

Linkage and association studies of QTL for nuclear families by mixed models

The transmission disequilibrium test (TDT) has been utilized to test the linkage and association between a genetic trait locus and a marker. Spielman et al. (1993) introduced TDT to test linkage between a qualitative trait and a marker in the presence of association. In the presence of linkage, TDT can be applied to test for association for fine mapping (Martin et al., 1997; Spielman and Ewens, 1996). In recent years, extensive research has been carried out on the TDT between a quantitative trait and a marker locus (Allison, 1997; Fan et al., 2002; George et al., 1999; Rabinowitz, 1997; Xiong et al., 1998; Zhu and Elston, 2000, 2001). The original TDT for both qualitative and quantitative traits requires unrelated offspring of heterozygous parents for analysis, and much research has been carried out to extend it to fit for different settings. For nuclear families with multiple offspring, one approach is to treat each child independently for analysis. Obviously, this may not be a valid method since offspring of one family are related to each other. Another approach is to select one offspring randomly from each family for analysis. However, with this method much information may be lost. Martin et al. (1997, 2000) constructed useful statistical tests to analyse the data for qualitative traits. In this paper, we propose to use mixed models to analyse sample data of nuclear families with multiple offspring for quantitative traits according to the models in Amos (1994). The method uses data of all offspring by taking into account their trait mean and variance-covariance structures, which contain all the effects of major gene locus, polygenic loci and environment. A test statistic based on mixed models is shown to be more powerful than the test statistic proposed by George et al. (1999) under moderate disequilibrium for nuclear families. Moreover, it has higher power than the TDT statistic which is constructed by randomly choosing a single offspring from each nuclear family.     

Lack of an Additive Effect between the Deletions of Klf5 and Nkx3-1 in Mouse Prostatic Tumorigenesis

Prostate cancer is one of the most common malignancies.The development and progression of prostate cancer are driven by a series of genetic and epigenetic events including gene amplification that activates oncogenes and chromosomal deletion that inactivates tumor suppressor genes.Whereas gene amplification occurs in human prostate cancer,gene deletion is more common,and a large number of chromosomal regions have been identified to have frequent deletion in prostate cancer,suggesting that tumor suppressor inactivation is more common than oncogene activation in prostatic carcinogenesis (Knuutila et al.,1998,1999;Dong,2001).Among the most frequently deleted chromosomal regions in prostate cancer,target genes such as NKX3-1 from 8p21,PTENfrom 10q23 andATBF1 from 16q22 have been identified by different approaches (He et al.,1997;Li et al.,1997;Sun et al.,2005),and deletion of these genes in mouse prostates has been demonstrated to induce and/or promote prostatic carcinogenesis.For example,knockout of Nkx3-1 in mice induces hyperplasia and dysplasia (Bhatia-Gaur et al.,1999;Abdulkadir et al.,2002) and promotes prostatic tumorigenesis (Abate-Shen et al.,2003),while knockout of Pten alone causes prostatic neoplasia (Wang et al.,2003).Therefore,gene deletion plays a causal role in prostatic carcinogenesis (Dong,2001).     

南中国海野生海水鱼类外寄生车轮虫新记录

研究对采自南中国海的7种海水鱼类进行了调查研究, 并分离获得4种隶属于车轮虫属的种类,分别为浦氏车轮虫Trichodina puytoraci Lom, 1962; 日本车轮虫Trichodina japonica Imai, et al., 1991; 直钩车轮虫Trichodina rectuncinata Raabe, 1958 与鲀车轮虫Trichodina fugu Imai, et al., 1997。研究发现鲀车轮虫Trichodina fugu Imai, et al., 1997为寄主鱼虫纹东方鲀Takifugu vermicularis的病原, 且能在野生条件下将其致死。上述4种车轮虫的形态分类学数据均基于干银法标本获得。研究是对我国南中国海车轮虫的首次报道。       

Expression pattern of mouse sFRP-1 and mWnt-8 gene during heart morphogenesis

The Wnt genes encode a large family of secreted proteins that play a key role in embryonic development and tissue differentiation in many species (Rijsewijk et al., 1987 and Nusse and Varmus, 1992). Genetic and biochemical studies have suggested that the frizzled proteins are cell surface receptors for Wnts (Vinson et al., 1989, Chan et al., 1992, Bhanot et al., 1996 and Wang et al., 1996). In parallel, a number of secreted frizzled-like proteins with a conserved N-terminal frizzled motif have been identified (Finch et al., 1997, Melkonyan et al., 1997 and Rattner et al., 1997). One of these proteins, FrzA, the bovine counterpart of the murine sFRP-1 (93% identity) is involved in vascular cell growth control, binds Wg in vitro and antagonizes Xwnt-8 and hWnt-2 signaling in Xenopus embryos (Xu et al., 1998 and Duplàa et al., 1999). In this study, we report that sFRP-1 is expressed in the heart and in the visceral yolk sac during mouse development, and that sFRP-1 and mWnt-8 display overlapping expression patterns during heart morphogenesis. From 8.5 to 12.5 d.p.c., sFRP-1 is expressed in cardiomyocytes together with mWnt-8 but neither in the pericardium nor in the endocardium; at 17.5 d.p.c., they are no longer present in the heart. In mouse adult tissues, while sFRP-1 is highly detected in the aortic endothelium and media and in cardiomyocytes, mWnt-8 is not detected in these areas. Immunoprecipitation experiments demonstrates that FrzA binds to mWnt-8 in cell culture experiments.     

Involvement of phenylalanine 272 of DNA polymerase beta in discriminating between correct and incorrect deoxynucleoside triphosphates

DNA polymerase beta is a small monomeric polymerase that participates in base excision repair and meiosis [Sobol, R., et al. (1996) Nature 379, 183-186; Plug, A., et al. (1997) Proc. Natl. Acad. Sci. U.S.A. 94, 1327-1331]. A DNA polymerase beta mutator mutant, F272L, was identified by an in vivo genetic screen [Washington, S., et al. (1997) Proc. Natl. Acad. Sci. U.S.A. 94, 1321-1326]. Residue 272 is located within the deoxynucleoside triphosphate (dNTP) binding pocket of DNA polymerase beta according to the known DNA polymerase beta crystal structures [Pelletier, H., et al. (1994) Science 264, 1891-1893; Sawaya, M., et al. (1997) Biochemistry 36, 11205-11215]. The F272L mutant produces errors at a frequency 10-fold higher than that of wild type in vivo and in the in vitro HSV-tk gap-filling assay. F272L shows an increase in the frequency of both base substitution mutations and frameshift mutations. Single-enzyme turnover studies of misincorporation by wild type and F272L DNA polymerase beta demonstrate that there is a 4-fold decrease in fidelity of the mutant as compared to that of the wild type enzyme for a G:A mismatch. The decreased fidelity is due primarily to decreased discrimination between the correct and incorrect dNTP during ground-state binding. These results suggest that the phenylalanine 272 residue is critical for maintaining fidelity during the binding of the dNTP.     

Vestibular input to brain monoamine neurons--a review

Yates et al. reported that serotonergic RN neurons are associated with vestibulo-sympathetic responses and may control BP changes during body repositioning (Yates et al., 1992; 1993). Pompeiano et al. demonstrated that LC-NA neurons participate in the postural control and modify the vestibulo-spinal reflex (Pompeiano et al., 1990; 1991a; 2001). Nishiike et al. (1996a) examined the effects of caloric vestibular stimulation on the neuronal activity of LC-NA neurons in rats. The predominant effect of CA with both hot- and cold-water on the electrical activity of LC neurons is inhibitory and persists for several minutes. GABAA receptors located on the postsynaptic membrane of LC neurons are responsible for these inhibitory responses. The VLM may inhibit LC neuronal activity in response to the CA via GABAA receptors (Nishiike et al., 1997). It is suggested that LC-NA inhibition is involved in the development of motion sickness (Nishiike et al., 2001).     

Structural changes in the neck linker of kinesin explain the load dependence of the motor's mechanical cycle.

The two-headed motor protein kinesin hydrolyzes ATP and moves on microtubule tracks towards the plus end. The motor develops speeds and forces of the order of hundreds of nanometers per second and piconewtons, respectively. Recently, the dependence of the velocity, the dissociation rate and the displacement variance on the load and the ATP concentration were measured in vitro for individual kinesin molecules (Coppin et al., 1997; Visscher et al., 1999) over a wide range of forces. The structural changes in the kinesin motor that drive motility were discovered by Rice et al. (1999). Here we present a phenomenological model for force generation in kinesin based on the bi-stable, nucleotide-dependent behavior of the neck linker. We demonstrate that the model explains the mechanical, kinetic and statistical (experimental) data of Coppin et al. (1997). We also discuss the relationship between the model results and experimental data of Visscher et al. (1999).     

The epithelial Na(+) channel (ENaC) is related to the hypertonicity-induced Na(+) conductance in rat hepatocytes

The epithelial Na(+) channel (ENaC) is composed of the subunits alpha, beta, and gamma [Canessa et al., Nature 367 (1994) 463-467] and typically exhibits a high affinity to amiloride [Canessa et al., Nature 361 (1993) 467-470]. When expressed in Xenopus oocytes, conflicting results were reported concerning the osmo-sensitivity of the channel [Ji et al., Am. J. Physiol. 275 (1998) C1182-C1190; Hawayda and Subramanyam, J. Gen. Physiol. 112 (1998) 97-111; Rossier, J. Gen. Physiol. 112 (1998) 95-96]. Rat hepatocytes were the first system in which amiloride-sensitive sodium currents in response to hypertonic stress were reported [Wehner et al., J. Gen. Physiol. 105 (1995) 507-535; Wehner et al., Physiologist 40 (1997) A-4]. Moreover, all three ENaC subunits are expressed in these cells [B?hmer et al., Cell. Physiol. Biochem. 10 (2000) 187-194]. Here, we injected specific antisense oligonucleotides directed against alpha-rENaC into single rat hepatocytes in confluent primary culture and found an inhibition of hypertonicity-induced Na(+) currents by 70%. This is the first direct evidence for a role of the ENaC in cell volume regulation.     

Epigenetic Variations in Plant Hybrids and Their Potential Roles in Heterosis

Heterosis,one of the most important biological phenomena,refers to the phenotypic superiority of a hybrid over its genetically diverse parents with respect to many traits such as biomass,growth rate and yield.Despite its successful application in breeding and agronomic production of many crop and animal varieties,the molecular basis of heterosis remains elusive.The classic genetic explanations for heterosis centered on three hypotheses:dominance (Davenport,1908;Bruce,1910;Keeble and Pellew,1910;Jones,1917),overdominance (East,1908;Shull,1908) and epistasis (Powers,1944;Yu et al.,1997).However,these hypotheses are largely conceptual and not connected to molecular principles,and are therefore insufficient to explain the molecular basis of heterosis (Birchler et al.,2003).Recently,many studies have explored the molecular mechanism of heterosis in plants at a genome-wide level.These studies suggest that global differential gene expression between hybrids and parental lines potentially contributes to heterosis in plants (e.g.,Swanson-Wagner et al.,2006;Zhang et al.,2008;Wei et al.,2009;Song et al.,2010).Research suggests that genetic components,including cis-acting elements and trans-acting factors,are critical regulators of differential gene expression in hybrids (Hochholdinger and Hoecker,2007;Springer and Stupar,2007;Zhang et al.,2008).However,other research indicates that epigenetic components,the regulators of chromatin states and genome activity,also have the potential to impact heterosis (e.g.,Ha et al.,2009;He et al.,2010;Groszmann et al.,2011;Barber et al.,2012;Chodavarapu et al.,2012;Greaves et al.,2012a;Shen et al.,2012).     

Metal hyperaccumulation: a model system for coevolutionary studies

Recent years have seen a flurry of research activity concerning the hyperaccumulation of heavy metals by plants. Much of the interest in hyperaccumulation has been fueled by the commercial potential of phytoremediation, the use of plants to clean up contaminated soils (Baker et al ., 1994; Salt et al ., 1995; Chaney et al ., 1997, 2000). These applications have in turn spurred many studies of the genetics and physiology of metal uptake (e.g. Krämer et al ., 1996; Lasat et al ., 1996; Salt & Krämer, 1999; Baker et al ., 2000; see also Krämer, 2000; Lombi et al ., 2000). Although phytoremediation provides an intriguing and potentially profitable backdrop, the ecology and evolution of hyperaccumulation in natural populations are interesting subjects in their own right. Two papers in this issue (Ghaderian et al ., pp. 219–224; Davis & Boyd, pp. 211–217) are exciting contributions to the growing consensus that hyperaccumulation may act as a defense against herbivores and pathogens, and suggest that hyperaccumulation may become a model system for research in this area.     

A Video Demonstration of Preserved Piloting by Scent Tracking but Impaired Dead Reckoning After Fimbria-Fornix Lesions in the Rat

Piloting and dead reckoning navigation strategies use very different cue constellations and computational processes (Darwin, 1873; Barlow, 1964; O’Keefe and Nadel, 1978; Mittelstaedt and Mittelstaedt, 1980; Landeau et al., 1984; Etienne, 1987; Gallistel, 1990; Maurer and Séguinot, 1995). Piloting requires the use of the relationships between relatively stable external (visual, olfactory, auditory) cues, whereas dead reckoning requires the integration of cues generated by self-movement. Animals obtain self-movement information from vestibular receptors, and possibly muscle and joint receptors, and efference copy of commands that generate movement. An animal may also use the flows of visual, auditory, and olfactory stimuli caused by its movements. Using a piloting strategy an animal can use geometrical calculations to determine directions and distances to places in its environment, whereas using an dead reckoning strategy it can integrate cues generated by its previous movements to return to a just left location. Dead reckoning is colloquially called "sense of direction" and "sense of distance."Although there is considerable evidence that the hippocampus is involved in piloting (O’Keefe and Nadel, 1978; O’Keefe and Speakman, 1987), there is also evidence from behavioral (Whishaw et al., 1997; Whishaw and Maaswinkel, 1998; Maaswinkel and Whishaw, 1999), modeling (Samsonovich and McNaughton, 1997), and electrophysiological (O’Mare et al., 1994; Sharp et al., 1995; Taube and Burton, 1995; Blair and Sharp, 1996; McNaughton et al., 1996; Wiener, 1996; Golob and Taube, 1997) studies that the hippocampal formation is involved in dead reckoning. The relative contribution of the hippocampus to the two forms of navigation is still uncertain, however. Ordinarily, it is difficult to be certain that an animal is using a piloting versus a dead reckoning strategy because animals are very flexible in their use of strategies and cues (Etienne et al., 1996; Dudchenko et al., 1997; Martin et al., 1997; Maaswinkel and Whishaw, 1999). The objective of the present video demonstrations was to solve the problem of cue specification in order to examine the relative contribution of the hippocampus in the use of these strategies. The rats were trained in a new task in which they followed linear or polygon scented trails to obtain a large food pellet hidden on an open field. Because rats have a proclivity to carry the food back to the refuge, accuracy and the cues used to return to the home base were dependent variables (Whishaw and Tomie, 1997). To force an animal to use a a dead reckoning strategy to reach its refuge with the food, the rats were tested when blindfolded or under infrared light, a spectral wavelength in which they cannot see, and in some experiments the scent trail was additionally removed once an animal reached the food. To examine the relative contribution of the hippocampus, fimbria–fornix (FF) lesions, which disrupt information flow in the hippocampal formation (Bland, 1986), impair memory (Gaffan and Gaffan, 1991), and produce spatial deficits (Whishaw and Jarrard, 1995), were used.Open in a separate windowClick here to view.^{(44M, flv)}     

湖北秭归三叶虫Ushbaspis hubeiensis新材料及其研究意义

文中通过对Ushbaspis hubeiensis (Lin,1978)新材料的研究,对该种三叶虫躯体构造特征做了重要补充,使人们对它有更全面的认识,也将为今后进一步对乌什巴盾壳虫类(ushbaspid) 三叶虫的分类、系统演化的研究以及对寒武纪第二世生物地层划分,提供一些重要依据。文中还就张文堂等（1980）将采自贵州湄潭的Kepingaspis sp.标本鉴定为Metaredlichioides constrictus Qian and Yao,1974提出质疑。