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M D Zhou

Publications and source records attributed to M D Zhou.

7 recordsLinked to original sources
PubMed2000

[Genetic diversity and differentiation of cultivated Fagoyrum tataricum populations from three counties in south Liangshan Automomous Prefecture of Yi Nationality, Sichuan, China].

Genetic diversity and differentiation among 8 cultivated populations of Fagopyrum tataricum from the counties of Jinyang, Leibo and Miyi in south Liangshan Autonomous Prefecture of Yi Nationality, Sichuan Province, China were investigated using allozyme electrophoresis. The allozymic diversity is roughly correlated with agrobiological features. The results suggest that genetic diversity of F. tataricum is quite high. The mean number of alleles per locus A is 1.8; the percentage of polymorphic loci P is 46.6%, and the mean observed heterozygosities Ho and the mean expected heterozygosities He are 0.187 and 0.218 respectively, the ratios of gene diversities of heterozygosities Fsr is 0.22, which indicates that there is 22 percent of genetic differentiation among populations, and suggests that for protecting genetic resources all the populations should be included in.

Edible Grain↗
PubMed2000

[Genetic diversity of Fagoyrum tataricum cultivated in north Liangshan Prefecture of Yi Nationality, Sichuan, China].

In the present paper is stated the accomplishment of the studies of 17 populations of cultivated Fagopyrum tataricum (L.) Gaertn. from the counties of Yuexi and Ganluo in North Liangshan Autonomous Prefecture of Yi Nationality, Sichuan Province, China by means of starch gel electrophoresis and cluster analysis of agrobiology features. Seven enzymes, and 15 loci were assessed. The result shows that the genetic diversity of F. tataricum within population is higher than in the South Prefecture and in species F. esculentum from other areas. The A, P, Ho and He are 1.9, 52.1%, 0.190 and 0.262 respectively. The FST is 0.199 which is close to the average level of wild plants. A conservation strategy of the genetic resource of F. tataricum is suggested. Two populations of local variety "Youchiqiao" have the richest genetic diversity, P = 60.0%, Ho = 0.260 and 0.301 and they should be protected particularly. Two populations of local variety "Xiaomiqiao" with higher genetic diversity, as well as three populations of local varieties of "Qiukuqiao", "Equkuqiao" and "Geluokuqiao" with special genetic position should be protected too.

China↗
PubMed1995

Retinoid-dependent pathways suppress myocardial cell hypertrophy.

Utilizing an in vitro model system of cardiac muscle cell hypertrophy, we have identified a retinoic acid (RA)-mediated pathway that suppresses the acquisition of specific features of the hypertrophic phenotype after exposure to the alpha-adrenergic receptor agonist phenylephrine. RA at physiological concentrations suppresses the increase in cell size and induction of a genetic marker for hypertrophy, the atrial natriuretic factor (ANF) gene. RA also suppresses endothelin 1 pathways for cardiac muscle cell hypertrophy, but it does not affect the increase in cell size and ANF expression induced by serum stimulation. A trans-activation analysis using a transient transfection assay reveals that neonatal rat ventricular myocardial cells express functional RA receptors of both the retinoic acid receptor and retinoid X receptor (RAR and RXR) subtypes. Using synthetic agonists of RA, which selectively bind to RXR or RAR, our data indicate that RAR/RXR heterodimers mediate suppression of alpha-adrenergic receptor-dependent hypertrophy. These results suggest the possibility that a pathway for suppression of hypertrophy may exist in vivo, which may have potential therapeutic value.

Animals↗
PubMed1993

A new serum-responsive, cardiac tissue-specific transcription factor that recognizes the MEF-2 site in the myosin light chain-2 promoter.

We have identified a serum-responsive, cardiac tissue-specific transcription factor, BBF-1, that recognizes an AT-rich sequence (element B), identical to the myocyte enhancer factor (MEF-2) target site, in the cardiac myosin light chain-2 (MLC-2) promoter. Deletion of the element B sequence alone from the cardiac MLC-2 promoter causes, as does that of the MEF-2 site from other promoters and the enhancer of skeletal muscle genes, a marked reduction of transcription. BBF-1 is distinguishable from cardiac MEF-2 on the basis of immunoprecipitation with an antibody which recognizes MEF-2 but not BBF-1. Unlike MEF-2, BBF-1 is present exclusively in nuclear extracts from cardiac muscle cells cultured in a medium containing a high concentration of serum. Removal of serum from culture medium abolishes BBF-1 activity selectively with a concomitant loss of the positive regulatory effect of element B on MLC-2 gene transcription, indicating that there is a correlation between the BBF-1 binding activity and the tissue-specific role of the element B (MEF-2 site) sequence. The loss of element B-mediated activation of transcription is reversed following the refeeding of cells with serum-containing medium. These data demonstrate that cardiac muscle cells contain two distinct protein factors, MEF-2 and BBF-1, which bind to the same target site but that, unlike MEF-2, BBF-1 is serum inducible and cardiac tissue specific. BBF-1 thus appears to be a crucial member of the MEF-2 family of proteins which will serve as an important tool in understanding the regulatory mechanism(s) underlying cardiogenic differentiation.

Animals↗
PubMed1992

A single transcription factor binds to two divergent sequence elements with a common function in cardiac myosin light chain-2 promoter.

The cardiac myosin light chain-2 (MLC-2) gene promoter contains several positive and negative cis-acting sequences that are involved in the regulation of its expression. We describe here the properties of two activator sequences, elements A and P, and their DNA-binding factors (ABFs). Element A (CCAAAAGTGG), located at -61, has homology with the evolutionarily conserved sequence CC(A/T)6GG, present in the genes of many contractile proteins. Element P (TAACCTTGAAAGC), located 114 bp upstream of element A, is conserved in both chicken and rat cardiac MLC-2 gene promoters. Deletion mutagenesis demonstrated that these two elements are involved in the positive regulation of MLC-2 gene transcription. At least two sequence-specific element A-binding proteins, ABF-1 and ABF-2, were identified by gel shift analysis of the fractionated cardiac nuclear proteins. ABF-1 binds to element A with strict dependence on the internal element A sequence AAAAGT. In contrast, ABF-2 exhibits a relaxed sequence requirement, as it recognizes the consensus CArG and CCAAT box sequences as well. ABF-2 also recognizes the distal element P despite the fact that the sequences of elements A and P are divergent. DNase I footprinting, methylation interference, and gel shift analyses demonstrated unequivocally that the element A-DNA affinity-purified protein ABF-2 binds to element P with sequence specificity. Since both elements A and P play a positive regulatory role in MLC-2 gene transcription and bind to a single protein (ABF-2), it would appear that ABF-2 is a key transcription factor with the ability to recognize divergent sequence elements involved in a common regulatory pathway during myogenesis.

Animals↗
PubMed1992

Mechanism of tissue-specific transcription: interplay between positive and negative regulatory factors.

At least four regulatory cis-acting DNA sequences, CCAAAAGTGG (element A), TTATTTTTA (element B), TATTTATT (element C), and TATTACCTTTAT (element S), were identified in cardiac myosin light chain-2 (MLC2) proximal promoter as target sites for sequence-specific binding of nuclear proteins. For muscle-specific transcription, the proximal promoter (-53 to +1) consisting only of elements B and C is required. Addition of element A to this promoter results in a muscle-specific up-regulation, whereas the addition of element S exerts a negative effect on transcription. The negative and positive regulatory effects of elements S and A respectively were demonstrated by site-specific mutations of the promoter following transient transfection of cardiac muscle cells in culture. Elements S and A interact separately with distinct nuclear protein factor present in both muscle and non-muscle cells, even though their regulatory activities are restricted to muscle cells. Among the multiple complexes resulting from the interaction of nuclear proteins and elements S and A DNAs, one requires both S and A sequences together for binding. Element B, which exerts a muscle-specific positive effect on transcription, binds to a nuclear protein present in cardiac muscle, but not in non-muscle cells. DNA-protein binding assays and mutational analysis of the MLC2 promoter suggest that the contribution of the functionally opposed cis-elements depends upon an interplay between the positively and negatively acting DNA-binding proteins via protein-protein interactions to mediate opposite regulatory effects on gene transcription.

Animals↗