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Biomedical subjects

Z Gong

Publications and source records attributed to Z Gong.

At least 19 recordsLinked to original sources
PubMed2006

Benzo(a)pyrene inhibits expression of inducible heat shock protein 70 in vascular endothelial cells.

Benzo(a)pyrene (BaP), a ubiquitous environmental pollutant known to cause many diseases including atherosclerosis, induces a dose-dependent reduction in the levels of the inducible Hsp70. To explore the mechanism underlying the reduction of Hsp70, we measured the levels of Hsp70, cytoplasmic and nuclear heat shock factor 1 (HSF1) in porcine aortic endothelial cells using Western blot, and then further characterized the binding ability of HSF1 and heat shock element (HSE) by electrophoretic mobility shift assay. We found that when porcine aortic endothelial cells were treated by 0.1-10 microM of BaP for 24 h, there was a significant reduction of Hsp70, cytoplasmic and nuclear HSF1 and the binding rate of HSF1 and HSE at 5, 10 microM of BaP but less effective at lower concentrations. The effect of BaP on the Hsp70 expression level was markedly attenuated by co-treatment with phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C (PKC). Staurosporine (STP), an inhibitor of PKC, blocked the effect of PMA treatment in combination with BaP. These results suggest that BaP might inhibit Hsp70 levels by reducing the expression of HSF1 and decreasing binding of HSF1 and HSE via PKC-dependent signaling pathways that might be involved in the regulation of Hsp70 gene expression under BaP.

Animals↗
PubMed2006

Characterization and expression of a cDNA encoding a tubuliform silk protein of the golden web spider Nephila antipodiana.

Spider silks are renowned for their excellent mechanical properties. Although several spider fibroin genes, mainly from dragline and capture silks, have been identified, there are still many members in the spider fibroin gene family remain uncharacterized. In this study, a novel silk cDNA clone from the golden web spider Nephila antipodiana was isolated. It is serine rich and contains two almost identical fragments with one varied gap region and one conserved spider fibroin-like C-terminal domain. Both in situ hybridization and immunoblot analyses have shown that it is specifically expressed in the tubuliform gland. Thus, it likely encodes the silk fibroin from the tubuliform gland, which supplies the main component of the inner egg case. Unlike other silk proteins, the protein encoded by the novel cDNA in water solution exhibits the characteristic of an alpha-helical protein, which implies the distinct property of the egg case silk, though the fiber of tubuliform silk is mainly composed of beta-sheet structure. Its sequence information facilitates elucidation of the evolutionary history of the araneoid fibroin genes.

Amino Acid Sequence↗
PubMed2006

Antitumor activities of the four sesquiterpene lactones from Elephantopus scaber L.

AIM: To evaluate antitumor activity of sesquiterpene lactones (scabertopin (ES-2), isoscabertopin (ES-3), deoxyelephantopin (ES-4), isodeoxyelephantopin (ES-5)) isolated from Elephantopus scaber L. in vitro and in vivo. METHODS: SMMC-7721, Caco-2 and HeLa cell lines were treated with ES-2,3,4,5. Cell viability was determined by MTT assay. Agarose gel electrophoresis was used to detect DNA fragmentation. To evaluate in vivo antitumor activity of ES-4, experimental murine tumor model was used. RESULTS: It was shown that ES-2, ES-4, ES-5 exhibited significant antitumor effect in vitro in a concentration-dependent manner. However, the effect of ES-3 on the growth of tested cell lines was relatively weak. In HeLa cells exposed to ES-4 for 48 h, morphological changes and DNA ladder pattern evidencing on apoptosis were detected. ES-4 revealed in vivo antitumor activity. CONCLUSION: Antitumor activity of studied sesquiterpene lactones may be due, at least in part, to induction of apoptosis in vitro. ES-4 possesses also antitumor activity in vivo.

Antineoplastic Agents, Phytogenic↗
PubMed2005

Effects of thyroid hormone on the development of immune system in zebrafish.

Effects of thyroxine (T4) and methimazole (MMI) on the development of the zebrafish immune system were investigated using continuous immersion treatment experiments. The effects of the treatments on thymus development were determined using computer-aided thymus morphometric analyses on in situ hybridization serial sections of the thymus while the effects on immune-related gene expression levels were monitored using quantitative real-time PCR. The findings indicate that thymus development and thymopoiesis, as indicated by thymus size, thymus Rag-1-positive region, and TCRAC expression level, were affected by T4 and MMI-treatments. With the exception of Ikaros, MMI-treated fish has lower immune-related gene expression levels, although it is not certain whether the effect resulted indirectly from the concomitant growth-retardation and/or directly from an effect on lymphopoiesis itself. The findings were comparable with those in mammalian system, thus providing the first evidence that the thyroid relationship with thymus development and lymphopoiesis is likely to be conserved from fish to higher vertebrates. It suggests the possibility of using zebrafish as a model system to investigate the molecular mechanisms involved in thyroid hormone-dependent disorders in the immune system.

Animals↗
PubMed2005

Bioremediation of contaminated surface water by immobilized Micrococcus roseus.

The problems caused by contaminated surface water have gradually become more serious in recent years. Although various remediation technologies were investigated, unfortunately, no efficient method was developed. In this paper, a new bioremediation technology was studied using Micrococcus roseus, which was immobilized in porous spherical beads by an improved polyvinyl alcohol (PVA) - sodium alginate (SA) embedding method. The experimental results indicated that COD removal rate could reach 64.7 % within 72 hours when immobilized M. roseus beads were used, which was ten times as high as that of free cells. The optimum inoculation rate of immobilized M. roseus beads was 10 % (mass percent of the beads in water sample, g g(-1)). Suitable aeration was proved necessary to enhance the bioremediation process. The immobilized cells had an excellent tolerance to pH and temperature changes, and were also more resistant to heavy metal stress compared with free cells. The immobilized M. roseus beads had an excellent regeneration capacity and could be reused after 180-day continuous usage. The Scanning Electronic Microscope (SEM) analysis showed that the bead microstructure was suitable for M. roseus growth, however, some defect structures should still be improved.

Alginates↗
PubMed2005

Synthesis and evaluation of a new series of peptide-based endothelin receptor antagonists.

Novel peptide-based endothelin (ET) receptor antagonists were designed and synthesized in our laboratory. BQ-485, HIM-CO-Leu-d-Trp-d-Trp-OH, was selected as the leading compound. The primary structures of these new tripeptides were ABO-CO-Leu-d-Trp-d-AA(X)-OH. The introduction of unnatural aromatic amino acids into these tripeptides was useful in the structure-activity relationship studies. Among the 20 tripeptides, 16 of them showed high activities against the contraction of rat aortic smooth muscles induced by ET-1.

Animals↗
PubMed2004

Development and maturation of the immune system in zebrafish, Danio rerio: a gene expression profiling, in situ hybridization and immunological study.

The development and maturation of the immune system in zebrafish was investigated using immune-related gene expression profiling by quantitative real-time polymerase chain reaction, in situ hybridization (ISH), immunoglobulin (Ig) detection by immuno-affinity purification and Western blotting as well as immersion immunization experiments. Ikaros expression was first detected at 1 day post-fertilization (dpf) and thereafter increased gradually to more than two-fold between 28 and 42dpf before decreasing to less than the initial 1dpf expression level in adult fish (aged 105dpf). Recombination activating gene-1 (Rag-1) expression levels increased rapidly (by 10-fold) between 3 and 17dpf, reaching a maximum between 21 and 28dpf before decreasing gradually. However, in adult fish aged 105dpf, the expression level of Rag-1 had dropped markedly, and was equivalent to the expression level at 3dpf. T-cell receptor alpha constant region and immunoglobulin light chain constant region (IgLC) isotype-1, 2 and 3 mRNAs were detected at low levels by 3dpf and their expression levels increased steadily to the adult range between 4 and 6 weeks post-fertilization (wpf). Using tissue-section ISH, Rag-1 expression was detected in head kidney by 2wpf while IgLC-1, 2 and 3 were detected in the head kidney and the thymus by 3wpf onwards. Secreted Ig was only detectable using immuno-affinity purification and Western blotting by 4wpf. Humoral response to T-independent antigen (formalin-killed Aeromonas hydrophila) and T-dependent antigen (human gamma globulin) was observed in zebrafish immunized at 4 and 6wpf, respectively, indicating that immunocompetence was achieved. The findings reveal that the zebrafish immune system is morphologically and functionally mature by 4-6wpf.

Animals↗
PubMed2002

Morphologic transformation of the thymus in developing zebrafish.

The morphologic transformation of the developing zebrafish thymus from 1 week postfertilization (wpf) to 15 wpf is described. The thymus overall morphology changed from a small pouch-like shape at 1 wpf to a conical shape between 2 and 3 wpf before acquiring a more complex shape from 4 wpf onward. Rapid growth rate along the lateral axis at the region near the pharyngeal epithelium occurred between 1 and 2 wpf, whereas rapid growth rate along the dorsal-ventral axis occurred between 3 and 6 wpf. Expansion of thymocyte population beginning from 1 wpf became more evident by 2 to 3 wpf, as indicated by the apparent increase of different sizes of lymphocytes, recombination activating gene-1 (rag-1), and T-cell antigen receptor alpha chain constant region (TCRAC) -positive cells. Tissue section in situ hybridization (ISH) analysis with rag-1 probe reveals that cortex-medullary regionalization has begun between 1 and 2 wpf as rag-1 expression clearly demarcated the cortex, whereas the medulla was rag-1 negative. The presence of TCRAC-positive cells in the medulla by 2-3 wpf, suggests that the thymic selection processes had begun. The zebrafish thymus is morphologically mature by 3 wpf. Early signs of thymic involution were observed in zebrafish aged 15 wpf.

Animals↗
PubMed2001

A novel zebrafish bHLH gene, neurogenin3, is expressed in the hypothalamus.

Many basic helix-loop-helix transcriptional factors play important roles in vertebrate neurogenesis. Among them, Neurogenins act as determination factors and initiate the expression of differentiation genes such as neuroD and other neurogenic genes. Here we describe a zebrafish cDNA (neurogenin3 or ngn3) encoding a novel member of the Neurogenin family closest to mouse Ngn3 and human NGN3. Using a zebrafish radiation hybrid panel, ngn3 was mapped to zebrafish linkage group 13 and the region displayed a conserved synteny with the region of human chromosome 10 containing NGN3. As judged by RT-PCR and whole-mount in situ hybridization, ngn3 expression in zebrafish started much later than other neurogenin genes, at only around 24 h post-fertilization (hpf) and with a higher level of expression on the left side of the anterio-ventral diencephalon. Later at 48 hpf, ngn3 expression was detected in a small number of cells in the tuberal hypothalamus. Unlike Ngn3 in the mouse, zebrafish ngn3 mRNAs were not detected in developing pancreas and spinal cord. Genomic Southern blot hybridization suggested that a closely related sequence is present in the zebrafish genome and the hypothetical gene might result from the recent genome duplication in certain teleost lineage and share the function of the common ancestor with the currently characterized ngn3.

Amino Acid Sequence↗
PubMed2001

The Arabidopsis HOS1 gene negatively regulates cold signal transduction and encodes a RING finger protein that displays cold-regulated nucleo--cytoplasmic partitioning.

Low temperature is one of the most important environmental stimuli that control gene transcription programs and development in plants. In Arabidopsis thaliana, the HOS1 locus is a key negative regulator of low temperature-responsive gene transcription. The recessive hos1 mutation causes enhanced induction of the CBF transcription factors by low temperature as well as of their downstream cold-responsive genes. The hos1 mutant plants flower early, and this correlates with a low level of Flowering Locus C gene expression. The HOS1 gene was isolated through positional cloning. HOS1 encodes a novel protein with a RING finger motif near the amino terminus. HOS1 is ubiquitously expressed in all plant tissues. HOS1--GFP translational fusion studies reveal that HOS1 protein resides in the cytoplasm at normal growth temperatures. However, in response to low temperature treatments, HOS1 accumulates in the nucleus. Ectopic expression of HOS1 in wild-type plants causes cosuppression of HOS1 expression and mimics the hos1 mutant phenotypes.

Acclimatization↗
PubMed2001

Involving AP-2 transcription factor in connexin 26 up-regulation during pregnancy and lactation.

Gap junction connexin 26 (Cx26) is up-regulated in mammary epithelial cells during pregnancy and lactation. To understand the transcriptional regulation of Cx26, we identified a protected DNase I footprint region (-140 to -113) in the rat Cx26 promoter. This rCx26 Promoter Footprinting Region, or CPFR, contains an Sp binding site (CCGCCC) overlapping with an AP-2 binding site (GCCCGCGGC), and is evolutionarily conserved. Nuclear extracts from rat mammary glands and human MCF-10 mammary epithelial cells formed protein-DNA complexes with the labeled CPFR probe in the electrophoretic mobility shift assay (EMSA), and these complexes were markedly enhanced during pregnancy and lactation. Antibody supershift analysis further identified the presence of Sp1, Sp3, and AP-2 in these binding complexes. Human mammary epithelial MCF-10A and MCF-12A cells were transiently transfected with chimeric mutant rCx26 promoter/luciferase reporter constructs, and luciferase activities measured. Mutations along the CPFR fragment drastically reduced the promoter activity, specially at the Sp/AP-2 overlapping site. Cotransfection of AP-2 with rCx26 promoter/reporter constructs into MCF-10 cells markedly induced the reporter activity. These data infer that AP-2, along with previously reported Sp transcription factors, is involved in the up-regulation of Cx26 gene during pregnancy and lactation.

Animals↗
PubMed2001

Multiple tissue transformation in adult zebrafish by gene gun bombardment and muscular injection of naked DNA.

The efficiency of two direct gene transfer methods, gene gun (or particle bombardment) and intramuscular injection, in transforming adult zebrafish tissues in vivo was examined by a noninvasive approach using green fluorescent protein (GFP) reporter gene driven by the ubiquitously expressed human cytomegalovirus promoter. Particle bombardment of adult zebrafish caused internalization and expression of the plasmid only in the superficial layer such as epithelial cells, pigment cells, endothelial cells, and neurons, whereas direct injection primarily transformed muscle fibers of several bundles near or around the injection site. Expression was also evident in several nonmuscle tissues, such as skin epithelia, pigment cells, blood vessel cells, and neuron-like cells. GFP expression persisted for more than 50 days with both methods. These observations indicate the potential of these methods for functional analysis of tissue-specific promoters, delivery of DNA vaccine, and muscular expression of other useful genes.

Journal Article↗
PubMed2001

Cloning and developmental expression of a family of pleurocidin-like antimicrobial peptides from winter flounder, Pleuronectes americanus (Walbaum).

Low molecular weight antimicrobial peptides are an important component of the innate immune system in animals, yet they have not been examined widely in fish. Of particular interest is their expression during development and in response to environmental conditions and disease. Here, we report the isolation of four genomic sequences encoding putative antimicrobial peptides from the winter flounder, Pleuronectes americanus (Walbaum), as well as reverse transcription-PCR products from two tissues that form the first defensive barrier to microbes - skin and intestine. Alignment of the predicted polypeptide sequences shows a conserved hydrophobic signal peptide of 22 amino acids followed by 25 amino acids that are identical (WF2) or homologous to the amino acid sequence of pleurocidin, followed by a conserved acidic portion. Southern hybridisation analysis indicates that related peptides are encoded in the genomes of other flatfish species. Northern and RT-PCR analyses of RNA from multiple tissues show that two of the pleurocidin genes are expressed predominantly in the skin whereas two other genes are expressed mainly in the intestine. RT-PCR assays of total RNA from larvae of different ages provide the first evidence of developmental expression of antimicrobial peptides in fish and indicate that the pleurocidin gene is first expressed at 13 days post-hatch in winter flounder.

Amino Acid Sequence↗
PubMed2001

Expression of two novel zebrafish iroquois homologues (ziro1 and ziro5) during early development of axial structures and central nervous system.

Previously, we reported a zebrafish iroquois gene, ziro3, and its expression during early embryogenesis (Mech. Dev. 87 (1999) 165). In the present study, we have isolated two novel zebrafish iroquois genes, ziro1 and ziro5, homologs of mouse Irx1 and mouse Irx5, respectively. The expression of both genes is initiated in dorsal neuroectoderm and mesoderm during gastrulation. Later, their expression appears in the central nervous system (CNS), excluding the telencephalon and most of the diencephalon. ziro1 expression is complementary to that of ziro3 in the notochord and later in the gut. In contrast, ziro5 expression mostly overlaps with that of ziro3. Interestingly, all three iroquois zebrafish genes are expressed in the notochord while only Irx3 is active in the mouse notochord. Their expression in later stages of embryogenesis was also compared.

Amino Acid Sequence↗
PubMed2001

Expression pattern of two zebrafish genes, cxcr4a and cxcr4b.

We cloned and mapped two novel zebrafish genes, cxcr4a and cxcr4b, which are closely related to mammalian CXCR4. Expression analysis by reverse transcription-polymerase chain reaction and in situ hybridization demonstrated that these two genes are expressed in most cell lineages known to express Cxcr4 in mammals. These genes are co-expressed in lateral mesoderm and posterior midbrain. The transcripts of cxcr4a were detected in interneurons and endoderm, whereas cxcr4b was specifically expressed in sensory neurons, motoneurons and cerebellum. In the lateral mesoderm, cxcr4b transcripts appeared earlier than those of cxcr4a. Thus, the function of mammalian CXCR4 could be split between the two zebrafish genes. These genes probably derived from the genome duplication event, which occurred during the evolution of teleosts. Similar pairs of Cxcr4 may exist in other species, where genome duplication has occurred.

Amino Acid Sequence↗
PubMed2001

Modulation of abscisic acid signal transduction and biosynthesis by an Sm-like protein in Arabidopsis.

The phytohormone abscisic acid (ABA) regulates plant growth and development as well as stress tolerance. The Arabidopsis sad1 (supersensitive to ABA and drought) mutation increases plant sensitivity to drought stress and ABA in seed germination, root growth, and the expression of some stress-responsive genes. sad1 plants are also defective in the positive feedback regulation of ABA biosynthesis genes by ABA and are impaired in drought stress induction of ABA biosynthesis. SAD1 encodes a polypeptide similar to multifunctional Sm-like snRNP proteins that are required for mRNA splicing, export, and degradation. These results suggest a critical role for mRNA metabolism in the control of ABA signaling as well as in the regulation of ABA homeostasis.

Abscisic Acid↗
PubMed2001

Green fluorescent protein (GFP) transgenic fish and their applications.

The coupling of the GFP reporter system with the optical clarity of embryogenesis in model fish such as zebrafish and medaka is beginning to change the picture of transgenic fish study. Since the advent of first GFP transgenic fish in 1995, GFP transgenic fish technology have been quickly employed in many areas such as analyses of gene expression patterns and tissue/organ development, dissection of promoters/enhancers, cell lineage and axonal pathfinding, cellular localization of protein products, chimeric embryo and nuclear transplantation, cell sorting, etc. The GFP transgenic fish also have the potentials in analysis of upstream regulatory factors, mutagenesis screening and characterization, and promoter/enhancer trap. Our own studies indicate that GFP transgenic fish may become a new source of novel variety of ornamental fish. Efforts are also being made in our laboratory to turn GFP transgenic fish into biomonitoring organisms for surveillance of environmental pollution.

Animals↗