Biomedical subjects

Mu-Yuan Zhu

Publications and source records attributed to Mu-Yuan Zhu.

14 recordsLinked to original sources

PubMed2006

Programmed cell death-involved aluminum toxicity in yeast alleviated by antiapoptotic members with decreased calcium signals.

The molecular mechanisms of aluminum (Al) toxicity and tolerance in plants have been the focus of ongoing research in the area of stress phytophysiology. Recent studies have described Al-induced apoptosis-like cell death in plant and animal cells. In this study, we show that yeast (Saccharomyces cerevisiae) exposed to low effective concentrations of Al for short times undergoes enhanced cell division in a manner that is dose and cell density dependent. At higher concentrations of Al or longer exposure times, Al induces cell death and growth inhibition. Several apoptotic features appear during Al treatment, including cell shrinkage, vacuolation, chromatin marginalization, nuclear fragmentation, DNA degradation, and DNA strand breaks, as well as concomitant cell aggregation. Yeast strains expressing Ced-9, Bcl-2, and PpBI-1 (a plant Bax inhibitor-1 isolated from Phyllostachys praecox), respectively, display more resistance to Al toxicity compared with control cells. Data from flow cytometric studies show these three antiapoptotic members do not affect reactive oxygen species levels, but decrease calcium ion (Ca(2+)) signals in response to Al stress, although both intracellular reactive oxygen species and Ca(2+) levels were increased. The data presented suggest that manipulation of the negative regulation process of programmed cell death may provide a novel mechanism for conferring Al tolerance.

Aluminum↗

PubMed2006

Cloning, characterization and tissue specific expression of Amur tiger (Panthera tigris altaica) IGF-I.

Insulin-like growth factor I (IGF-I) plays an important role in regulating gonad function, which is essential for normal reproduction in animals, especially in sexual receptivity and reproductive behavior. In this study, a cDNA encoding Amur tiger (Panthera tigris altaica) IGF-I was isolated from liver total RNA using RT-PCR. The IGF-I cDNA of Amur tiger (ATIGF-I) was highly homologous to that of other animals, 84.8% to rat, 93.7% to human and horse. Alignment analysis showed that the cysteine residues and many amino acid residues of putative mature ATIGF-I are highly conserved in mammalian species, confirming the high sequence homology observed in other species. DNA encoding the mature ATIGF-I peptide was ligated with pET-DsbA expression vector and highly expressed in Escherichia coli BL21 with IPTG induction. The recombinant proteins expressed existed mostly in the soluble protein fraction, and were purified with metal affinity resins. Western blotting confirmed that the recombinant proteins reacted with antibodies against IGF-I. The results obtained here should be useful for large-scale production of biological active ATIGF-I protein, as well as for further research on growth, development, and reproduction in the Amur tiger. Tissue specific expression of ATIGF-I mRNA in the Amur tiger was examined by reverse transcription-polymerase chain reaction (RT-PCR), The major ATIGF-I mRNA expression tissue was the liver, while medium signals were found in the uterus, ovary, and pituitary, and minor signals were detected in various tissues including the heart, spleen, pancreas, and kidney. The results indicate that IGF-I might play an important role in the reproductive system and in cub development in the Amur tiger.

Amino Acid Sequence↗

PubMed2006

[Effects of cu2+ on biosynthesis of camptothecin in cell cultures of Camptotheca acuminata].

Camptothecin is a strong anti-tumor compound isolated from Camptotheca acuminata. One of the most important way for the production of Camptothecin is by cell cultures of Camptotheca acuminata. The effect of Cu2+ on camptothecin accumulation in Camptotheca acuminata cell line was described in this paper. The results showed that the optimum CuCl2 concentration in B5 medium was 0.008 mg/mL, which increased camptothecin production for 30 times compare to the control while has no inhibitive effects on cell growth, at the same time, the peroxidase activity was increased and the anthocyanidin accumulation was inhibited. The promotive effects of Cu2+ on camptothecin accumulation in light was higher than that in dark.

Anthocyanins↗

PubMed2005

Nitric oxide mediates the fungal elicitor-induced hypericin production of Hypericum perforatum cell suspension cultures through a jasmonic-acid-dependent signal pathway.

Fungal elicitor prepared from the cell walls of Aspergillum niger induces multiple responses of Hypericum perforatum cells, including nitric oxide (NO) generation, jasmonic acid (JA) biosynthesis, and hypericin production. To determine the role of NO and JA in elicitor-induced hypericin production, we study the effects of NO scavenger 2- to 4-carboxyphenyl-4,4, 5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPITO), nitric oxide synthase inhibitor S,S'-1,3-phenylene-bis(1,2-ethanediyl)-bis-isothiourea, and inhibitors of the octadecanoid pathway on elicitor-induced NO generation, JA biosynthesis, and hypericin production. Pretreatment of the cells with cPITO and JA biosynthesis inhibitors suppresses not only the elicitor-induced NO generation and JA accumulation but also the elicitor-induced hypericin production, which suggests that both NO and JA are involved in elicitor-induced hypericin biosynthesis. S,S'-1,3-phenylene-bis(1,2-ethanediyl)-bis-isothiourea and cPITO inhibit both elicitor-induced NO generation and JA biosynthesis, while JA biosynthesis inhibitors do not affect the elicitor-induced NO generation, indicating that JA acts downstream of NO generation and that its biosynthesis is regulated by NO. External application of NO via its donor sodium nitroprusside induces hypericin production in the absence of fungal elicitor. Sodium-nitroprusside-induced hypericin production is blocked by JA biosynthesis inhibitors, showing that JA biosynthesis is essential for NO-induced hypericin production. The results demonstrate a causal relationship between elicitor-induced NO generation, JA biosynthesis, and hypericin production in H. perforatum cells and indicate a sequence of signaling events from NO to hypericin production, within which NO mediates the elicitor-induced hypericin biosynthesis at least partially via a JA-dependent signaling pathway.

Anthracenes↗

PubMed2005

Molecular cloning of giant panda pituitary prolactin cDNA and its expression in Escherichia coli.

cDNA encoding pituitary (PRL) of giant panda was obtained using RT-PCR and expressed in E. coli. The results revealed that panda PRL cDNA encodes a precursor protein of 229 amino acids including a putative signal peptide of 30 amino acids and a mature protein of 199 residues with one potential N-glycosylation site. Sequence comparison indicated that panda PRL shares a high degree of identity to other known PRL sequences ranging from 98% with mink PRL to about 50% with rodent PRL. Six cysteine residues and 29 conserved residues distributed in four domains (PD1, PD2, PD3, and PD4) of PRL were observed. through multiple sequence alignment. Fourteen key residues of binding sites 1 and 2 involved in receptor binding are conserved in panda PRL. GST fused recombinant panda PRL protein was efficiently expressed with the form of insoluble inclusion bodies in E. coli BL21 transformed with a pGEX-4T-1 expression vector containing the DNA sequence encoding mature panda PRL. Western blot analysis indicated that GST-panda PRL recombinant protein could be recognized by antibody against human PRL. Our results would contribute to further elucidating the structural and functional characteristics of pituitary PRL and provide a basis for the production of recombinant panda prolactin for future use in the breeding of giant panda.

Amino Acid Sequence↗

PubMed2004

Root border cell development is a temperature-insensitive and Al-sensitive process in barley.

In vivo and in vitro experiments showed that border cell (BC) survival was dependent on root tip mucigel in barley (Hordeum vulgare L. cv. Hang 981). In aeroponic culture, BC development was an induced process in barley, whereas in hydroponic culture, it was a kinetic equilibrium process during which 300-400 BCs were released into water daily. The response of root elongation to temperatures (10-35 degrees C) was very sensitive but temperature changes had no great effect on barley BC development. At 35 degrees C, the root elongation ceased whereas BC production still continued, indicating that the two processes might be regulated independently under high temperature (35 degrees C) stress. Fifty microM Al could inhibit significantly BC development by inhibiting pectin methylesterase activity in the root cap of cv. 2000-2 (Al-sensitive) and cv. Humai 16 (Al-tolerant), but 20 microM Al could not block BC development in cv. Humai 16. BCs and their mucigel of barley had a limited role in the protection of Al-induced inhibition of root elongation, but played a significant role in the prevention of Al from diffusing into the meristems of the root tip and the root cap. Together, these results suggested that BC development was a temperature-insensitive but Al-sensitive process, and that BCs and their mucigel played an important role in the protection of root tip and root cap meristems from Al toxicity.

Aluminum↗

PubMed2004

[Cloning and expression of pituitary prolactin gene in Ailuropoda melanoleuca].

The giant panda (Ailuropoda melanoleuca) is an endangered species and indigenous to China. It has been proposed that it has a highly specialized reproductive pattern with low fecundity, but little is known about its basic reproductive biology at molecular level. In this study,the pituitary prolactin (PRL) cDNA of giant panda was amplified by RT-PCR from pituitary total RNA and then cloned, sequenced and submitted to GenBank (GenBank accession No. AY161285). The sequence analysis revealed that the giant panda prolactin cDNA contains a 687-nucleotide open reading frame encoding the prolactin prohormone of 229 amino acid residues. The signal peptide contains 30 amino acid residues and the mature prolactin is composed of 199 amino acid residues. Then the DNA fragment amplified was subcloned into pGEX-4T-1 procaryotic expression plasmid and protein expression was induced by IPTG in Escherichia coil BL21. SDS-PAGE analysis revealed the PRL protein is infusible. The multiple sequence alignments revealed that the homology of giant panda is 95% to cat and pig, 80% - 70% to human, cow and goat, 52% to rat and 45.9% to mouse at the amino acid level. The 64th amino acid of giant panda prolactin is hydrophilic serine instead of hydrophobic proline of cat, goat, and cow or hydrophobic alanine of human.

Amino Acid Sequence↗

PubMed2004

[Regulation network and biological roles of LEAFY in Arabidopsis thaliana in floral development].

Recent research progress on regulation network and biological roles of LFY gene in Arabidopsis thaliana and its homologue genes in floral development are reviewed emphatically in the present paper. LFY gene expresses widely in both vegetative and reproductive tissues in different higher plants, therefore investigation on role of LFY gene on flowering is of general significance. LFY gene plays an important role to promote flower formation by interaction and coordination with other genes,such as TFL, EMF, AP1, AP2, CAL, FWA, FT, AP3, PI, AG, UFO, CO, LD, GA1 etc, and a critical level of LFY expression is essential. LFY gene not only controls flowering-time and floral transition,but also plays an important role in inflorescence and floral organ development. It was situated at the central site in gene network of flowering regulation,positively or negatively regulates the level or activities of flowering-related genes. Some physiological factors, such as carbon sources, phytohormones, affect directly or indirectly the expression and actions of LFY gene. This indicates that level of LFY expression can also be regulated with physiological methods. It is probable that we can explain the principal mechanism of flowering by regulation network of LFY gene.

Arabidopsis↗

PubMed2004

[The application of transgenic plant in evaluating the genotoxicity of environmental contaminants].

Environmental contaminants are powerful mutagenic factors for organisms. Several testing materials and methods have been used to assess the genotoxicity of environmental factors. Transgenic plants testing system can not only evaluate the level of genotoxicity, but also provide information on the genetic effects at molecular level. We introduce the use of transgenic plants in biomonitoring environmental factors.

Animals↗

PubMed2004

[Expression of CFL gene during differentiation of floral and vegetative buds in cucumber cotyledonary nodes cultured in vitro].

CFL gene, a LFY homologue, was cloned from cucumber (Cucumis sativus L.). In this paper, in situ hybridization was performed to analyze the expression pattern of CFL gene at the stage of floral and vegetative buds differentiation in cucumber cotyledonary nodes cultured in vitro. The results showed that at the stage of floral differentiation, CFL gene was strongly expressed in primordia, floral organ primordia, and each whirl of floral organs at the early stage of their formation, but weakly expressed or not expressed in floral organs after their formation (Fig. 2). At the stage of vegetative bud differentiation, CFL gene was strongly expressed in meristem, leaf primordium and young leaves, and no apparent expression signal was detected in mature tissues (Fig. 3). The results suggest that the expression of CFL gene be necessary for the differentiation and formation of floral and vegetative primordias, and it plays an important role in floral and vegetative development in cucumber. The results also indicate that CFL gene involving in mitosis initiation, mitosis controlling, and transformation of vegetative meristem to floral meristem.

Base Sequence↗

PubMed2003

Cloning and sequence analysis of FSH and LH in the giant panda (Ailuropoda melanoleuca).

The giant panda (Ailuropoda melanoleuca) is an endangered species and indigenous to China. It has been proposed that it has a highly specialized reproductive pattern with low fecundity, but little is known about its basic reproductive biology at the molecular level. In this report the genes encoding gonadotropin subunits alpha, follicle-stimulating hormone (FSH) beta and luteinizing hormone (LH) beta of the giant panda were amplified for the first time by RT-PCR from pituitary total RNA, and were cloned, sequenced and analyzed. The results revealed that the open reading region (ORF) of gonadotropin subunits alpha, FSH beta and LH beta are 363, 390 and 426 bp long, respectively. They displayed a reasonably high degree (74-94, 85-93, 75-91%, for alpha, FSH beta and LH beta subunits, respectively) of identity when deduced amino acids were compared with homologous sequences from partial available mammals including human, cattle, sheep, pig, rat, mouse. Three distinct differences were found at the site of 59 aa of the alpha subunit and 55 aa, 68 aa of FSH beta subunit. Our results provide an insight into understanding the mechanism of reproduction regulation and genetic characteristics of giant panda which will make an actual contribution to its conservation. In addition they lay a foundation for a further study towards producing recombinant panda FSH and LH which can be used in artificial breeding aimed to increase its captive reproductive efficiency.

Amino Acid Sequence↗

PubMed2003

Inhibition of growth and development of root border cells in wheat by Al.

The production and development of border cells vary with genotype, and they are released in wheat at an earlier stage of root development than other species studied so far. No significant difference was observed in the maximum number of border cells between Al-tolerant (Atlas 66) and Al-sensitive (Scout 66) cultivars in the absence of Al treatment. Al seriously inhibited the production and release of border cells, resulting in clumping of border cells in Scout 66, but less clustering in Atlas 66. The number of border cells released from roots treated with Al is significantly less than that from roots grown without Al treatment. Al treatment induced the death of detached border cells in vitro and they were killed by a 20-h treatment with 25 micro m Al. No significant difference in survival percentage of detached border cells was observed between Atlas 66 and Scout 66, regardless of the presence or absence of Al. The removal of border cells from root tips of both Atlas 66 and Scout 66 enhanced the Al-induced inhibition of root elongation concomitant with increased Al accumulation in the root. These results suggest that border cells adhered to the root tips play a potential role in the protection of root from Al injury in wheat.

Journal Article↗

PubMed2003

[Analysis of polymorphic RAPD fragments in P. Taiwanensis Hayata using an integrated microflluidic chip-based system].

Randomly amplified polymorphic DNA (RAPD) markers quickly provide linkage information, especially in conifers where haploid megagametophytes can be used for genotyping. Traditionally use of slab gel electrophresis results in qualitative data that can be manually manipulated to gain semiquantitative information about the polymorphic RAPD fragments. We have proposed the use of an integrated microfluidic chip-based system as a new tool in the analysis of polymorphic RAPD fragments. The chip-based method was found to be very sensitive,requiring much less sample and only quarter the time compared to the agarose gel method. The automated data analysis sizes and quantitates the DNA fragments, thus yielding a more thorough,reproducible, sensitive, and rapid analysis.

English Abstract↗

PubMed2002

[Environmental stress-induced programmed cell death in higher plants].

Programmed cell death (PCD) research in higher plants has blossomed in the past ten years. Many evidences suggested that reactive oxygen species,ethylene, Ca2+, salicylic acid, nitric oxide etc. are important signal molecules during environmental stress-induced PCD in plants. Like apoptosis in animals, there also exists a Caspase-dependent PCD signal transduction pathway, in which mitochondrion plays a role of central depot.

English Abstract↗