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Z Gong

Publications and source records attributed to Z Gong.

At least 55 records · Page 3Linked to original sources
PubMed2000

An emergent mechanism of selective visual attention in Drosophila.

Due to the limited computational capacity of visual systems and the limited capacity to perform several mental operations at once, animals only select a small proportion of the stimuli available at any one time. It remains to be clarified how this process is related to the spatio-temporal dynamics of cell assemblies in the brain. By employing the flight simulator, selective visual attention behavior is studied in Drosophila. It has been found that for the visual objects presented, the tethered fruitflies display various attention patterns. Specifically, the learning memory mutants dunce and amnesiac possess attention patterns totally different from that of the wild-type fly. To explain these results from the viewpoint of dynamic cell assemblies, a neural network has been developed in which a possible link between the activity of cell assemblies, encoding of sensory information, and selective attention in Drosophila is proposed.

Animals↗
PubMed2000

Characterization of a zebrafish (Danio rerio) desmin cDNA: an early molecular marker of myogenesis.

Desmin is a muscle-specific protein and a constitutive subunit of the intermediate filaments (IF) in skeletal, cardiac and smooth muscles. It is an early marker of skeletal muscle myogenesis. We have characterized a clone of desmin cDNA from an embryonic zebrafish (Danio rerio) cDNA library. The full-length cDNA comprised 1798 nucleotides, encoding a protein of 473 amino acids. The predicted amino acid sequence of the zebrafish desmin shares a high degree of similarity to other vertebrate desmins, but also contains a sequence at the carboxyl terminal of the tail domain that is unique to the zebrafish. It carries many features which are distinctive of IF subunit proteins. These include the T/SSYRRXF/Y motif in the head domain, and the intermediate filament signature consensus, [I/V]-X-[T/A/C/I]-Y-[R/K/H]-X-[L/M]-L-[D/E], located in the carboxyl terminus of the central helical rod. Unlike other 3' UTR sequences, the 3' UTR of the zebrafish cDNA sequence has two CAYUG elements flanking a single polyadenylation site. The temporal and spatial expression patterns of desmin mRNA during early zebrafish development were studied. The onset of desmin expression occurred at the 1-3 somite stage (11 hpf). It increased throughout somitogenesis, with maximum expression at the Prim-6 stage (25 hpf), and decreasing expression towards the protruding-mouth stage (72 hpf). Desmin mRNA was initially localised exclusively to the somites, but was subsequently also detected in other musculature in the developing heart and fins. The onset of expression and the spatial localization of desmin mRNA in the zebrafish coincides with that reported for MyoD and myogenin.

Amino Acid Sequence↗
PubMed2000

The LIM/homeodomain protein islet-1 modulates estrogen receptor functions.

LIM/Homeodomain (HD) proteins are classically considered as major transcriptional regulators which, in cooperation with other transcription factors, play critical roles in the developing nervous system. Among LIM/HD proteins, Islet-1 (ISL1) is the earliest known marker of motoneuron differentiation and has been extensively studied in this context. However, ISL1 expression is not restricted to developing motoneurons. In both embryonic and adult central nervous system of rodent and fish, ISL1 is found in discrete brain areas known to express the estrogen receptor (ER). These observations led us to postulate the possible involvement of ISL1 in the control of brain functions by steroid hormones. Dual immunohistochemistry for ISL1 and ER provided evidence for ISL1-ER coexpression by the same neuronal subpopulation within the rat hypothalamic arcuate nucleus. The relationship between ER and ISL1 was further analyzed at the molecular level and we could show that 1) ISL1 directly interacts in vivo and in vitro with the rat ER, as well as with various other nuclear receptors; 2) ISL1-ER interaction is mediated, at least in part, by the ligand binding domain of ER and is significantly strengthened by estradiol; 3) as a consequence, ISL1 prevents ER dimerization in solution, thus leading to a strong and specific inhibition of ER DNA binding activity; 4) ISL1, via its N-terminal LIM domains, specifically inhibits the ER-driven transcriptional activation in some promoter contexts, while ER can serve as a coactivator for ISL1 in other promoter contexts. Taken together, these data suggest that ISL1-ER cross-talk could differentially regulate the expression of ER and ISL1 target genes.

Animals↗
PubMed2000

Use of an IRES bicistronic construct to trace expression of exogenously introduced mRNA in zebrafish embryos.

To understand gene function in developing vertebrate embryos, co-injection of an mRNA for a reporter protein and an mRNA for a testing factor is widely used. However, because of the mosaic segregation of injected nucleic acids during early embryogenesis, whether both mRNAs are translated in the same cell remains uncertain. In the present study, we tested a new system of tracing the expression of a testing gene in zebrafish using an internal ribosomal entry site (IRES) to express two proteins from the same mRNA template, thus eliminating the problem of independent translation observed in co-injection essays. A DNA construct was made for synthesizing bicistronic mRNA for NeuroD, a neurogenic transcription factor, and the enhanced green fluorescent protein (EGFP) reporter. When the bicistronic mRNA for NeuroD and EGFP was injected into zebrafish embryos at one cell stage, all EGFP-expressing embryos showed ectopic expression of neuroD mRNA and the mRNA of its potential downstream gene, islet-1. Thus, the IRES bicistronic mRNA construct might be a more convincing means of analyzing gene function in developing zebrafish embryos.

Animals↗
PubMed2000

Combined effect of isoflurane and esmolol on sympathetic responses to tracheal intubation.

BACKGROUND: Influences of isoflurane and esmolol on endotracheal intubation induced sympathetic changes could be different. The effect of isoflurane and its combination with esmolol on catecholamine, blood pressure and pulse during endotracheal intubation were investigated. METHODS: Thirty patients were anesthetized with 3.0% isoflurane and tracheal intubation was carried out at the 5th min following the exposure to isoflurane. Half of them received intravenous saline and the other half received esmolol 2 mg/kg at the 4th min. Cardiovascular parameters were recorded and venous blood samples were taken for measurement of catecholamines every min. RESULTS: One min after administration of isoflurane, there was increase of heart rate (P < 0.05), while at the same time the epinephrine level fell (P < 0.05) and norepinephrine level remained unaltered. Both catecholamines raised after intubation (P < 0.05). The sympathetic responses to and the beta-antagonistic effect of esmolol on intubation were not significantly changed in the presence of isoflurane. CONCLUSIONS: Isoflurane increased heart rate while paradoxically decreased epinephrine. Norepinephrine was more specifically related to endotracheal intubation, for its serum level had little change before the event. Based on catecholamine findings, the mechanism of isoflurane effect on the sympathetic system is probably different from that of endotracheal intubation.

Adrenergic beta-Antagonists↗
PubMed2000

[The changes in serum antibody level after immunization with HFRS vaccine].

OBJECTIVES: To observe the changes in serum antibody level after mass immunization with vaccine against hemorrhagic fever with renal syndrome (HFRS) and to evaluate its efficacy and effectiveness in the prevalent areas. METHODS: Healthy people aged 16 to 60 years in the villages were recruited as study subjects, excluding those suffered from HFRS previously, going out for more than nine months and those with contraindications, and were randomly allocated into immunization and control groups with 10,460 and 16,159 persons, respectively. Specific IgG antibody was determined with indirect immunofluorescent assay (IFA) and neutralizing antibody (NA) was determined with micro CPE method. RESULTS: Two weeks after the full-course immunization, sero-conversion rate for IFA reached 100% in those sero-negative before immunization, with a 95% confidence interval of 96.3 - 100.0%, and that for NA 44.4%, with a 95% CI of 22.0% - 69.0%. Geometric mean titer (GMT) were 72.1 and 4.6 for IFA and NA, respectively. Booster immunization was provided for them one year later. Positivity of IFA and NA was 28.6%, 83.3%, 75.0%, 53.1%, 22.6% and 14.8%, 55.6%, 35.0%, 31.3%, 26.0%, before booster immunization, two weeks, one year, one and a half years, two years after booster immunization, respectively. CONCLUSION: HFRS vaccine had good immunogenicity, but its duration of serum antibody sustenance was relatively short.

Adolescent↗
PubMed1999

Development of a rectal nicotine delivery system for the treatment of ulcerative colitis.

The aims of this investigation were: i. to develop a rectal nicotine delivery system with bioadhesives for the treatment of ulcerative colitis and ii. to evaluate nicotine transport and cytotoxicity of the delivery system using Caco-2 cell culture systems. Rectal nicotine suppository formulations were prepared in semi-synthetic glyceride bases (Suppocire AM and AI, Gattefosse Inc.) by fusion method. The in vitro release of nicotine was carried out in modified USP dissolution apparatus 1. Differential scanning calorimetry (DSC) and powder X-ray diffraction were used to study the polymorphic changes if any in the formulations. An LC method was used for the assay of nicotine. The effect of bioadhesives (glyceryl monooleate (GMO), and Carbopol) on the nicotine flux was evaluated using Caco-2 cell permeability studies and Caco-2 cell viability was determined using the MTT toxicity assay. In vitro release studies indicated that the low melting AI base was superior to that of the AM base. Presence of GMO in the formulation enhanced the release of nicotine whereas Carbopol showed an opposite effect. The enhanced release of nicotine in the presence of GMO was found to be partly due to the melting point lowering effect of this compound. Caco-2 cell absorption studies showed that there was a decrease in the flux of nicotine in the presence of both the bioadhesives. The flux of the fluorescein marker which is used to study the integrity of the cell monolayers was found to be slightly higher only in the presence of 10% (w/w) Carbopol. Nicotine, Carbopol, and GMO do not have any cytotoxic effect on these cell monolayers within the concentration range used in the formulations. Rectal nicotine formulations containing bioadhesives were developed and characterized. Both in vitro release and cell culture studies have indicated that one can manipulate the nicotine release from these rectal delivery systems by incorporation of various bioadhesives or the use of different bases in the formulation. Nicotine concentration below 2% (w/v) and bioadhesive concentration below 10% (w/w) do not have any cytotoxic effect on Caco-2 cells.

Acrylic Resins↗
PubMed1999

Capillary electrophoresis separation and permanganate chemiluminescence on-line detection of some alkaloids with beta-cyclodextrin as an additive.

Capillary electrophoresis has been used in combination with on-line permanganate chemiluminescence detection for the simultaneous determination of morphine, 6-monoacetylmorphine and heroin. It was found that beta-cyclodextrins could improve the separation efficiency and enhance the chemiluminescence signal. Improved sensitivity over capillary electrophoresis with UV detection was obtained. The procedure has detection limits of 23, 66 and 115 fmol for morphine, 6-monoacetylmorphine and heroin, respectively.

Alkaloids↗
PubMed1999

Cloning of zebrafish activin type IIB receptor (ActRIIB) cDNA and mRNA expression of ActRIIB in embryos and adult tissues.

A full-length cDNA encoding for activin type IIB receptor (ActRIIB) was cloned from zebrafish embryos. It encodes a protein with 509 amino acids consisting of a signal peptide, an extracellular ligand binding domain, a single transmembrane region, and an intracellular kinase domain with predicted serine/threonine specificity. The extracellular domain shows 74-91% sequence identity to human, bovine, mouse, rat, chicken, Xenopus and goldfish activin type IIB receptors, while the transmembrane region and the kinase domain show 67-78% and 82-88% identity to these known activin IIB receptors, respectively. In adult zebrafish, ActRIIB mRNA was detected by RT-PCR in the gonads, as well as in non-reproductive tissues, including the brain, heart and muscle. In situ hybridization on ovarian sections further localized ActRIIB mRNA to cytoplasm of oocytes at different stages of development. Using whole-mount in situ hybridization, ActRIIB mRNA was found to be expressed at all stages of embryogenesis examined, including the sphere, shield, tail bud, and 6-7 somite. These results provide the first evidence that ActRIIB mRNA is widely distributed in fish embryonic and adult tissues. Cloning of zebrafish ActRIIB demonstrates that this receptor is highly conserved during vertebrate evolution and provides a basis for further studies on the role of activin in reproduction and development in lower vertebrates.

Activin Receptors, Type II↗
PubMed1999

Characterization of two zebrafish cDNA clones encoding egg envelope proteins ZP2 and ZP3.

Two zebrafish cDNA clones encoding homologs of mammalian zona pellucida proteins ZP2 and ZP3 were isolated from a whole adult cDNA library. The ZP2 clone encodes a protein of 428 amino acids. Unlike other teleost ZP2s that contain an N-terminal repetitive domain enriched with prolines and glutamines, the zebrafish ZP2 has no such repetitive domain. In the C-terminal non-repetitive domain, the zebrafish ZP2 shares 55-76% sequence identity with other teleost ZP2s. The ZP3 cDNA clone encodes a protein of 431 amino acids, which shares 61% sequence identity with a carp ZP3. Similar to mammalian ZP proteins, both zebrafish ZP2 and ZP3 contain several potential phosphorylation sites. However, unlike mammalian ZP proteins, both zebrafish ZP proteins contain almost no glycosylation site, which has been proposed to be important for interaction with sperm; thus, the ZP proteins may behave differently in mammals and teleosts. Northern blot analysis indicated that both zebrafish ZP2 and ZP3 mRNAs were expressed exclusively in the ovary and hence the ovary is likely the only site for ZP2 and ZP3 biosynthesis.

Amino Acid Sequence↗
PubMed1999

[Preliminary study on ToRCH epidemic laws in Wuhan region].

OBJECTIVE: To investigate the ToRCH epidemic law in Wuhan region. METHODS: The ToRCH infection in the normal populations of Wuhan region was inspected through a whole year (from Mar. 1997 to Feb. 1998) by detecting the specific IgM antibodies to ToRCH in sera. RESULTS: The results showed that in the whole year, the average positive rates of IgM aitibodies to Toxo, RuV, CMV and HSV were 5.8%, 7.5%, 4.2% and 4.9% respectively. Three characteristics of the ToRCH epidemic in the region were concluded: (1) The epidemic of RuV obviously changed with seasons. Its infection rates were the highest (8.5%, 19.5%, 14.0%) during spring (March, April and May). However, the changes of Toxo, CMV and HSV were not obvious with seasons; (2). The adult infections were mainly recessive, which had no apparent clinical symptoms; (3) The cross infections of the four pathogens were common, the cross-reaction rate of the surveyed year was 2.6%. CONCLUSIONS: RuV infection of pregnant woman may result in congenital malformation of the emlbryo. Accoroding to the seasonal epidemic characteristics of RuV, women in pregnancy had better not to go to the public places during the sping seasons (March, April, May) as far as possible.

Adult↗
PubMed1999

Molecular cloning and biochemical characterization of a novel anthocyanin 5-O-glucosyltransferase by mRNA differential display for plant forms regarding anthocyanin.

UDP-glucose: anthocyanin 5-O-glucosyltransferase (5-GT) is responsible for the modification of anthocyanins to more stable molecules in complexes for co-pigmentation, supposedly resulting in a purple hue. The cDNA encoding 5-GT was isolated by a differential display applied to two different forms of anthocyanin production in Perilla frutescens var. crispa. Differential display was carried out for mRNA from the leaves of reddish-purple and green forms of P. frutescens, resulting in the isolation of five cDNA clones predominantly expressed in the red form. The cDNA encoded a polypeptide of 460 amino acids, exhibiting a low homology with the sequences of several glucosyltransferases including UDP-glucose: anthocyanidin 3-O-glucosyltransferase. By using this cDNA as the probe, we also isolated a homologous cDNA clone from a petal cDNA library of Verbena hybrida. To identify the biochemical function of the encoded proteins, these cDNAs were expressed in Saccharomyces cerevisiae cells. The recombinant proteins in the yeast extracts catalyzed the conversion of anthocyanidin 3-O-glucosides into the corresponding anthocyanidin 3,5-di-O-glucosides using UDP-glucose as a cofactor, indicating the identity of the cDNAs encoding 5-GT. Several biochemical properties (optimum pH, Km values, and sensitivity to inhibitors) were similar to those reported previously for 5-GTs. Southern blot analysis indicated the presence of two copies of 5-GT genes in the genome of both red and green forms of P. frutescens. The mRNA accumulation of the 5-GT gene was detected in the leaves of the red form but not in those of the green form and was induced by illumination of light, as observed for other structural genes for anthocyanin biosynthesis in P. frutescens.

Amino Acid Sequence↗
PubMed1999

Faithful expression of green fluorescent protein (GFP) in transgenic zebrafish embryos under control of zebrafish gene promoters.

Although the zebrafish has become a popular model organism for vertebrate developmental and genetic analyses, its use in transgenic studies still suffers from the scarcity of homologous gene promoters. In the present study, three different zebrafish cDNA clones were isolated and sequenced completely, and their expression patterns were characterized by whole-mount in situ hybridization as well as by Northern blot hybridization. The first clone encodes a type II cytokeratin (CK), which is specifically expressed in skin epithelia in early embryos and prominently expressed in the adult skin tissue. The second clone is muscle specific and encodes a muscle creatine kinase (MCK). The third clone, expressed ubiquitously in all tissues, is derived from an acidic ribosomal phosphoprotein P0 (arp) gene. In order to test the fidelity of zebrafish embryos in transgenic expression, the promoters of the three genes were isolated using a rapid linker-mediated PCR approach and subsequently ligated to a modified green fluorescent protein (gfp) reporter gene. When the three hybrid GFP constructs were introduced into zebrafish embryos by microinjection, the three promoters were activated faithfully in developing zebrafish embryos. The 2.2-kb ck promoter was sufficient to direct GFP expression in skin epithelia, although a weak expression in muscle was also observed in a few embryos. This pattern of transgenic expression is consistent with the expression pattern of the endogenous cytokeratin gene. The 1.5-kb mck promoter/gfp was expressed exclusively in skeletal muscles and not elsewhere. By contrast, the 0.8-kb ubiquitous promoter plus the first intron of the arp gene were capable of expressing GFP in a variety of tissues, including the skin, muscle, lens, neurons, notochord, and circulating blood cells. Our experiments, therefore, further demonstrated that zebrafish embryos can faithfully express exogenously introduced genes under the control of zebrafish promoters.

Animals↗
PubMed1999

Involvement of phosphatidylserine and non-phospholipid components of the hepatitis B virus envelope in human Annexin V binding and in HBV infection in vitro.

BACKGROUND/AIMS: We have previously demonstrated that human liver Annexin V (hAV), a Ca2+-dependent phospholipid binding protein, binds specifically to small HBsAg (SHBsAg). Because of the propensity of AV to bind phospholipids, we here examine the role of phospholipids, as component of the HBV envelope, in binding to hAV and in HBV infection. METHODS: The influence of phospholipids (phosphatidylserine and phosphatidylcholine) on the binding of hAV to SHBsAg or to anti-hAV monoclonals was determined by ELISA. Their influence on HBV infection was investigated using an in vitro HBV infection assay. RESULTS: Two monoclonals, specific against hAV, were able to block the binding of hAV to SHBsAg and recognized different epitopes of hAV. The binding of one of these monoclonals to hAV could be inhibited by phosphatidylserine, but not by phosphatidylcholine. Further experiments revealed that phosphatidylserine could also inhibit the binding of hAV to SHBsAg and could even prevent HBV infection in vitro. Phosphatidylcholine had no effect on the binding of hAV to SHBsAg and could not prevent HBV infection in vitro. However, since phosphatidylserine was not able to abolish the binding of the other blocking monoclonal to hAV, a non-phospholipid component of the HBV envelope must also be involved in hAV binding. CONCLUSIONS: These results indicate that phosphatidylserine and a non-phospholipid component of the HBV envelope are involved in hAV binding and in HBV infection.

Annexin A5↗
PubMed1999

Identification of differentially expressed genes in Con A-activated carp (Cyprinus carpio L.) leucocytes.

A cDNA library was constructed from the message RNA (mRNA) obtained from Con A-induced head kidney (HK) leucocytes of carp (Cyprinus carpio L.). Differential screening of the cDNA was carried out by hybridization against the total cDNA probes from normal, Con A-uninduced HK leucocytes or Con A-induced HK leucocytes of carp. The differential expression patterns of certain cDNA clones were confirmed by Southern-blot and Northern-blot analysis. Single-pass of the sequencing analysis and homology search in Genbank (EMBL) revealed those differentially expressed cDNA clones encode for cytochrome c oxidase sub-unit II and III (COII and COIII), elongation factor-1 beta (EF-1 beta), bleomycin hydrolase (BH), heat shock cognate protein 70 (HSC70) and 16S ribosomal RNA (16S rRNA).

Amino Acid Sequence↗
PubMed1999

Expression of a zebrafish iroquois homeobox gene, Ziro3, in the midline axial structures and central nervous system.

We describe a zebrafish gene, Ziro3, which is highly homologous to Xenopus and mouse iroquois3. Ziro3 expression starts during gastrulation in the dorsal axial mesoderm that develops into the notochord. Later, the expression is limited to the chordo-neural hinge in the tailbud. Ziro3 expression also occurs in the central nervous system (CNS), excluding the telencephalon. The level of Ziro3 expression differs in odd and even rhombomeres. In the midbrain-hindbrain boundary (MHB) and rhombomere 6, Ziro3 transcripts appear only after the formation of the cerebellum and otic vesicle, respectively.

Amino Acid Sequence↗
PubMed1999

Direct evidence for anthocyanidin synthase as a 2-oxoglutarate-dependent oxygenase: molecular cloning and functional expression of cDNA from a red forma of Perilla frutescens.

Anthocyanidin synthase (ANS), an enzyme of the biosynthetic pathway to anthocyanin, has been postulated to catalyze the reaction(s) from the colorless leucoanthocyanidins to the colored anthocyanidins. Although cDNAs have been isolated that encode putative ANS, which exhibits significant similarities in amino acid sequence with members of a family of 2-oxoglutarate-dependent oxygenases, no biochemical evidence has been presented which identifies the actual reaction that is catalyzed by ANS. Here we show that anthocyanidins are formed in vitro through 2-oxoglutarate-dependent oxidation of leucoanthocyanidins catalyzed by the recombinant ANS and subsequent acid treatment. A cDNA encoding ANS was isolated from red and green formas of Perilla frutescens by differential display of mRNA. Recombinant ANS tagged with maltose-binding-protein (MBP) was purified, and the formation of anthocyanidins from leucoanthocyanidins was detected by the ANS-catalyzed reaction in the presence of ferrous ion, 2-oxoglutarate and ascorbate, being followed by acidification with HCI. Equimolar stoichiometry was confirmed for anthocyanidin formation and liberation of CO2 from 2-oxoglutarate. The presumptive two-copy gene of ANS was expressed in leaves and stems of the red forma of P. frutescens but not in the green forma plant. This corresponds to the accumulation pattern of anthocyanin. The mechanism of the reaction catalyzed by ANS is discussed in relation to the molecular evolution of a family of 2-oxoglutarate-dependent oxygenases.

Amino Acid Sequence↗