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Z Gong

Publications and source records attributed to Z Gong.

At least 73 records · Page 4Linked to original sources
PubMed1999

A class of neuroD-related basic helix-loop-helix transcription factors expressed in developing central nervous system in zebrafish.

Neuronal basic helix-loop-helix (bHLH) transcription factors such as neuroD and neurogenin have been shown to play important roles in neuronal development. In the present study, several distinct bHLH DNA fragments were isolated from the zebrafish genomic DNA by a pair of degenerate polymerase chain reaction (PCR) primers deduced from the conserved bHLH domains of neuroD and neurogenins. Based on the bHLH fragments, three complete neuroD-related cDNA clones, including complete coding regions, ndr1a, ndr1b, and ndr2 (ndr for neuroD related), were isolated and assembled by 5' and 3' rapid amplification of cDNA ends (RACE). A phylogenetic analysis indicated the presence of four groups of neuroD-related genes in the neuroD subfamily in vertebrates: neuroD, ndr1a/ndr1b/MATH-2, ndr2/NDRF, and neuroM/MATH3. Expression of the newly isolated neuroD-related genes was examined by reverse transcriptase (RT)-PCR and whole-mount in situ hybridization. Unlike neuroD, which was expressed broadly in primary neurons during early zebrafish development starting from 10 h postfertilization (hpf), expression of ndr1a and ndr1b started relatively late (around 22 hpf) and was restricted to the olfactory system: olfactory bulbs in the telecephalon (ndr1a and ndr1b) and olfactory organs (ndr1b) starting around 22 hpf. Although a faint ndr2 mRNA signal was detected by RT-PCR in early embryos, no ndr2 mRNA was detected by whole-mount in situ hybridization in embryos up to 72 hpf, suggesting that it is expressed rather late. Our observations suggest that the two novel neuroD-related genes, ndr1a and ndr1b, are involved in the development of the olfactory system and perhaps contribute to its functional complexity.

Amino Acid Sequence↗
PubMed1999

Fast skeletal muscle-specific expression of a zebrafish myosin light chain 2 gene and characterization of its promoter by direct injection into skeletal muscle.

A zebrafish myosin light chain 2 cDNA clone was isolated and characterized. Sequence analysis of the clone revealed a high homology with the mammalian and avian genes encoding the fast skeletal muscle isoform, MLC2f. In situ hybridization and Northern blot hybridization analyses indicated that the zebrafish MLC2f mRNA is expressed exclusively in the fast skeletal muscle. Ontogenetically, the MLC2f mRNA appears around 16 hours postfertilization (hpf) in the first few well-formed anterior somites. At later stages, the MLC2f mRNA can also be detected in fin buds, eye muscles, and jaw muscles. To develop a useful model system for analyzing muscle gene regulation, the promoter of the zebrafish MLC2f gene was isolated and linked to the chloramphenicol acetyltransferase (CAT) reporter gene. The MLC2f/CAT chimeric constructs were analyzed by direct injection into the zebrafish skeletal muscle, and significant CAT activity was observed; in contrast, little or no CAT activity was generated from a similarly injected prolactin gene promoter/CAT gene construct. Within the 1 kb of the MLC2f promoter region, several MEF2-binding sites and E-boxes were identified, suggesting that MLC2f can be regulated by muscle transcription factors MEF2 and myogenic bHLH proteins. A 5' deletion analysis indicated that the proximal 79 nucleotides from the transcription start site, which contains a single MEF2-binding site, is sufficient to drive a high level of CAT activity in injected muscle. Internal deletion of the MEF2 element in the -79-bp construct caused an 80% decrease in CAT activity, whereas internal deletion of the same MEF2 element in a -1044-bp construct had no effect on induced CAT activity. These observations suggest that an MEF2 element is important to activate the MLC2f gene in muscle cells, and the effect of loss of the proximal MEF2 element can be compensated for by the presence of the upstream MEF2 elements. This study also demonstrated that direct injection of DNA into skeletal muscle is a valid and valuable approach to analyze muscle gene promoters in the zebrafish.

Amino Acid Sequence↗
PubMed1999

Zebrafish tbx-c functions during formation of midline structures.

Several genes containing the conserved T-box region in invertebrates and vertebrates have been reported recently. Here, we describe three novel members of the T-box gene family in zebrafish. One of these genes, tbx-c, is studied in detail. It is expressed in the axial mesoderm, notably, in the notochordal precursor cells immediately before formation of the notochord and in the chordoneural hinge of the tail bud, after the notochord is formed. In addition, its expression is detected in the ventral forebrain, sensory neurons, fin buds and excretory system. The expression pattern of tbx-c differs from that of the other two related genes, tbx-a and tbx-b. The developmental role of tbx-c has been analysed by overexpression of the full-length tbx-c mRNA and a truncated form of tbx-c mRNA, which encodes the dominant-negative Tbx-c. Overexpression of tbx-c causes expansion of the midline mesoderm and formation of ectopic midline structures at the expense of lateral mesodermal cells. In dominant-negative experiments, the midline mesoderm is reduced with the expansion of lateral mesoderm to the midline. These results suggest that tbx-c plays a role in formation of the midline mesoderm, particularly, the notochord. Moreover, modulation of tbx-c activity alters the development of primary motor neurons. Results of in vitro analysis in zebrafish animal caps suggest that tbx-c acts downstream of early mesodermal inducers (activin and ntl) and reveal an autoregulatory feedback loop between ntl and tbx-c. These data and analysis of midline (ntl-/- and flh-/-) and lateral mesoderm (spt-/-) mutants suggest that tbx-c may function during formation of the notochord.

Amino Acid Sequence↗
PubMed1999

Isolation and characterization of viridin, a new 65 kDa antifungal protein from the mould Trichoderma viride.

A new extracellular antifungal protein with a yield of 10 mg per liter was isolated from the culture medium of the mould Trichoderma viride. The protein, which we named viridin, was purified by carboxymethyl-cellulose cation-exchange chromatography and Superose 12 HR 10/30 high-performance liquid chromatography. Viridin, a basic protein of approximately 65 kDa as determined by SDS-PAGE, inhibits the growth of the cotton pathogen Verticillum dahliae, the IC50 being 6 microM.

Androstenes↗
PubMed1999

[A study on the mechanism of the resistance of Shigellae to fluoroquinolones].

OBJECTIVE: To study the mechanism of the resistance of Shigellae to fluoroquinolones. METHODS: A total of 157 clinical isolates were collected. Antibiotic susceptibility testing, reserpine reverse reaction and plasmid conjugation experiment were performed. Accumulation of norfloxacin by shigellae was determined. The N-terminal coding region of gyrA gene was amplified by polymerase chain reaction (PCR), cloned and sequenced in eight fluoroquinolone-resistant isolates and one fluoroquinolone-sensitive isolate as well as in Shigella 51573 (the standard strain). RESULTS: The positive rate of norfloxacin-resistant isolates was 51.2% in the R plasmid conjugation experiment. R plasmid could not mediate resistance to fluoroquinolones. Reserpine could not decrease the minimum inhibition concentration of fluoroquinolones to Shigellae. Norfloxacin uptake by fluoroquinolone-resistant isolates was the same as that by the sensitive one. DNA sequence analysis of gyrA gene from fluoroquinolone-resistant isolates revealed five point mutations that resulted in amino acid change: Gly-81-->Ser, Ser-83-->Leu, Asp-87-->Asn, Asp-87-->Gly, Met-92-->Lys. CONCLUSION: The mutations of gyrA gene were implicated in the resistance of Shigellae to fluoroquinolones.

Anti-Infective Agents↗
PubMed1999

[Component in diphtheria-pertussis-tetanus-hepatitis B vaccine].

OBJECTIVE: To study immunogenecity of yeast-derived recombinant hepatitis B (YHB) component in diphtheria-pertussis-tetanus-YHB vaccine (DPTw-YHB). METHODS: Immunogenecity of tetra-valent DTPw-YHB vaccine and mono-valent recombinant YHB vaccine, and that of the tetra-valent vaccine with varied YHB component were compared. The efficiency and stability of recombinant YHB in the tetra-valent vaccine stored at 2 - 8 degrees C for 18 months were determined. RESULTS: The efficiency of recombinant YHB in the tetra-valent vaccine enhanced significantly in mice, as compared with that of mono-valent recombinant YHB vaccine, with an average mouse ED(50) of 1:2.0 - 1:3.1. There was no significant difference in efficiency of the tetra-valent vaccine with varied recombinant YHB component. Recombinant YHBin the DPTw-YHB tetra-valent vaccine still kept good stability stored at 2 - 8 degrees C for 18 months. CONCLUSION: Recombinant YHB in the tetra-valent vaccine was more immunogenic than the mono-valent YHB vaccine. No interference and inhibition of DPTw to recombinant YHB was found, indicating good compatibility between DPTw and YHB.

Animals↗
PubMed1999

[Differences in haemozoin production and pathogenicity between chloroquine-sensitive and chloroquine-resistant strains of Plasmodium berghei].

AIM: To better understand the differences in haemozoin formation and pathogenicity between chloroquine-sensitive(N) and chloroquine-resistant(RC) strains of Plasmodium berghei. METHODS: IRC mice were grouped as follows: group Xba I (Normal control, NC), group II (control treated with chloroquine alone, CC), group III (mice infected with N strain), group IV (mice infected with RC strain, RC) and group V (mice infected with RC strain and treated with chloroquine, RCC). Morphologic features of the parasites, parasitaemia, histological and ultrastructural changes of livers among the groups were compared. RESULTS: Severe damages of the hepatic cells of the N group including increased lysosomes and swollen and fused mitochondria were detected. On the contrary, the prominent features in liver section of the RC group were inflammatory cell (notably mononuclear) infiltration and Kupffer cell activation. Numerous trophozoites and schizonts were sequestrated in hepatic sinusoids and less degeneration of parenchymal cells was found except for some swollen and vacuolated mitochondria. Internal food vacuoles containing haemozoin were found in the parasites of the N group, whereas external food vacuoles without haemozoin granules were arranged in foamy appearance within the parasitized cell of the RC group. CONCLUSION: P. berghei RC strain may modify the mode of ingestion and degradation of hemoglobin in the parasites, resulting in impeding haemozoin formation. The difference in virulence between the N and RC strain of P. berghei is probably attributed to the significant differences in the induction of immune response of the host.

Animals↗
PubMed1999

Effects of alfentanil and esmolol on hemodynamic and catecholamine response to tracheal intubation.

OBJECTIVE: To compare the effects of alfentanil and esmolol on hemodynamic and catecholamine response to tracheal intubation. METHODS: Thirty-five adult patients were randomly allocated to one of three groups, Group A (control group). Group B (esmolol group) and Group C (alfentanil group). The patients received either 2 mg/kg esmolol (in Group B) or 30 microg/kg alfentanil (in Group C) before intubation. Tracheal intubation was performed with 4 mg/kg thiopental and 0.1 mg/kg vecuronium and 3% isoflurane. Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), heart rate (HR), norepinephrine (NE), epinephrine (E) and dopamine (DA) were measured before and after intubation. RESULTS: The control group had a baseline SBP of 149 +/- 23 mmHg while Groups B, C had a baseline SBP of 148 +/- 23, and 150 +/- 21 mmHg, respectively (P>0.05). Three min after tracheal intubation, the control group SBP increased to 160 +/- 30 mmHg and Group B remained at the baseline level, 147 +/- 5 mmHg, and Group C significantly decreased to 91 +/- 22 mmHg (P<0.01). Two min after intubation HR in Group B increased significantly but 3 min after intubation HR in Groups B and C were significantly lower than that of control group (P<0.05). NE in Groups A and B increased significantly to 5.75 +/- 3.51 and 6.75 +/- 3.30 nmol/L 3 min after intubation (P<0.01). In Group C, 3 min after intubation NE was not significantly different from the baseline but E decreased significantly (P<0.01). CONCLUSION: 2 mg/kg esmolol can moderate the hemodynamic response to tracheal intubation to a certain extent and 30 microg/kg alfentanil can completely attenuate the hemodynamic and catecholamine responses.

Adrenergic beta-Antagonists↗
PubMed1999

[Development and evaluation of a system for pulse generation and signal processing control in a plasma atomic fluorescence spectrometer with hollow cathode lamp as excitation source].

A Z80 processor was replaced with a 386 microcomputer to control pulse generation for hollow cathode lamp and fluorescence signal processing in a Baird Plasma AFS-2000 atomic fluorescence spectrometer. An interface board was designed for control purpose. The system was evaluated with detection limits, relative standard deviations and linear regression coefficients of 15 elements, which were in good agreement with the corresponding values in the manufacturer's manual. With the higher-level microprocessor in the system, the performance of the instrument was improved.

English Abstract↗
PubMed1999

[Atomic/ionic fluorescence in microwave plasma torch discharge excited by high current microsecond pulsed hollow cathode lamp-europium atomic/ionic fluorescence spectrometry].

Eu atomic and ionic fluorescence spectrometry in microwave plasma torch discharge excited by high current microsecond pulsed hollow cathode lamp (HCMP HCL-MPT AFS/IFS) was studied. Operating conditions were optimized. The best detection limits for AFS and IFS obtained with a desolvated ultrasonic nebulization system were 42.0 ng/mL for Eu I 462.7 nm and 21.8 ng/mL for Eu II 381.97 nm, respectively, both were better than those given by the instruction manual of a Baird ICP AFS-2000 spectrometer using pneumatic concentric nebulizer with desolvation for AFS, but were significantly higher than those obtained by using the Baird spectrometer with a mini-monochromator and a ultrasonic nebulzer system.

English Abstract↗
PubMed1998

A new splicing variant of a type III POU gene from zebrafish encodes a POU protein with a distinct C-terminal.

A zebrafish POU protein cDNA clone was isolated and sequenced. It appears to be a novel splicing variant of the previously reported zebrafish POU gene zp-12. There are four splicing variants and at least three of them lead to different C-terminal amino acid sequences. The four splicing variants are differentially regulated during development, indicating that they may be functionally diversified.

Alternative Splicing↗
PubMed1998

The skin-type antifreeze protein gene intron of the winter flounder is a ubiquitous enhancer lacking a functional C/EBPalpha binding motif.

The winter flounder antifreeze protein (AFP) intron contains a liver-specific enhancer (Element B) which was shown earlier to bind CCAAT/enhancer binding protein (C/EBP)alpha. In contrast, as demonstrated in the present studies, the intron of the skin-type AFP gene acted as a ubiquitous enhancer and contained a TA insertion at similar region to Element B (Element S) which destroyed its interaction with C/EBPalpha. Furthermore, a TA insertion of Element B by site-directed mutagenesis decreased its liver enhancer activity. The presence or absence of C/EBPalpha binding motifs in Element B and Element S, respectively, may provide a mechanism for their differential expression.

Animals↗
PubMed1998

Expression of zebrafish bHLH genes ngn1 and nrd defines distinct stages of neural differentiation.

Two zebrafish bHLH genes, neurogenin-related gene I (ngn1) and neuroD (nrd), have been isolated. ngn1 expression is initiated at the end of gastrulation in the neural plate and defines broad domains of cells that probably possess an ability to develop as neurons. This finding suggests that ngn1 may play a role during determination of cell fate in neuroblasts. ngn1 and pax-b are expressed in a mutually exclusive manner. nrd expression follows that of ngn1 in restricted populations of cells selected from ngn1-positive clusters of cells. The earliest nrd-positive cells in the brain and the trunk are a subset of the primary neurons. ngn1 is not expressed in the eye. Here, nrd transcription is activated at 25 hours postfertilization in the ventral retina. Expression of islet-1 occurs in nrd-positive cells after expression of nrd, and the expression of the two genes partially overlaps in time. These observations suggest that during eye development nrd expression may follow expression of some other neurodetermination gene(s). This supports the idea that expression of nrd is a necessary step leading toward overt neuronal differentiation.

Amino Acid Sequence↗
PubMed1998

Vertebrate genome evolution and the zebrafish gene map.

In chordate phylogeny, changes in the nervous system, jaws, and appendages transformed meek filter feeders into fearsome predators. Gene duplication is thought to promote such innovation. Vertebrate ancestors probably had single copies of genes now found in multiple copies in vertebrates and gene maps suggest that this occurred by polyploidization. It has been suggested that one genome duplication event occurred before, and one after the divergence of ray-finned and lobe-finned fishes. Holland et al., however, have argued that because various vertebrates have several HOX clusters, two rounds of duplication occurred before the origin of jawed fishes. Such gene-number data, however, do not distinguish between tandem duplications and polyploidization events, nor whether independent duplications occurred in different lineages. To investigate these matters, we mapped 144 zebrafish genes and compared the resulting map with mammalian maps. Comparison revealed large conserved chromosome segments. Because duplicated chromosome segments in zebrafish often correspond with specific chromosome segments in mammals, it is likely that two polyploidization events occurred prior to the divergence of fish and mammal lineages. This zebrafish gene map will facilitate molecular identification of mutated zebrafish genes, which can suggest functions for human genes known only by sequence.

Animals↗
PubMed1998

Assembly of a complete zebrafish mitochondrial 16S rRNA gene from overlapping expressed sequence tags.

A complete zebrafish mitochondrial 16S ribosomal RNA gene was assembled from our existing zebrafish EST clones by aligning them with the carp mitochondria 16S rRNA sequence. The overall homology between our assembled zebrafish mt 16S rRNA and the carp mt 16S rRNA is 83.5%. As the number of zebrafish ESTs grows, the assembly of more full-length cDNA sequences from overlapping EST data could be expected.

Animals↗
PubMed1998

[Investigation for polymorphism of ALDH2 exon12 in several Asian areas].

Mitochondrial aldehyde dehydrogenase (ALDH2) shows genetic polymorphism (Glu487Lys substitution) among Mongoloid populations, and the substitution is responsible for flushing symptom after alcohol intake. Recently, new ALDH2 alleles (ALDH2*3 and ALDH2*2Taiwan) in exon12 were reported in North American Indians and in Chinese from Taiwan by Novoradskey et al (1995). In the present study, we investigated the new allelic variants in exon12 for the five different ethnic groups (Mongolian, North Chinese, South Chinese, Myanmar, Japanese) by using PCR-SSCP and PCR-direct sequencing. Also, Glu 487 Lys substitution was analyzed to obtain additional information on gene geography of ALDH2 alleles in Asia reported so far. No new variants were found in the five population groups, but ALDH2*2 allele showed different frequencies among these groups. Especially, the frequencies of ALDH2*2 in Myanmer (0.02) and Mongolian (0.05) were significantly lower than other populations.

Aldehyde Dehydrogenase↗
PubMed1997

Rapid identification and isolation of zebrafish cDNA clones.

A fast and economical approach, referred to as cDNA clone tagging, was adapted to identify and isolate zebrafish cDNA clones. The basic approach was to partially sequence the coding region of size selected cDNA clones and the partial sequences were then used as tags for identifying the clones through homology search. To benefit maximally from the tagging approach, two cDNA libraries, derived from embryonic and adult fish poly(A)+ RNAs, respectively, were constructed by unidirectional cloning; conceptually, they have the potential to represent all expressed zebrafish genes. A total of 1084 clones were sequenced from the two libraries, and 511 clones were identified, based on sequence homology. These identified clones were derived from at least 261 genes, encoding 48 translational machinery proteins, 47 cytosolic proteins, 43 cytoskeletal proteins, 41 nuclear proteins, 32 membrane proteins, 22 secreted proteins, 20 mitochondrial proteins and 8 proteins with an unknown location. Of the 261 distinct cDNA clones identified, 254 were isolated for the first time in the zebrafish. These tagged cDNA clones, identified and unidentified, provide rich resources for developmental analysis as well as mapping of zebrafish genome. The long-term objective of this study is to establish a tagged zebrafish gene library that can be accessed both by hybridization screening against the plasmid DNAs and by electronic screening using the sequence information.

Animals↗