ENDOSPERM DEVELOPMENT IN THE DATE PALM (PHOENIX DACTYLIFERA) (ARECACEAE)

Date seeds were sampled at regular intervals from pollination (March) to mature fruit (September) and processed for light microscopy and SDS-PAGE. Seed fresh weight rose until early June and then declined slightly through September due to a continuous decrease in water content. Cell wall formation started in May in the free nuclear endosperm and proceeded centripetally from the inner integument to the seed center. Wall thickening in each cell started in cell corners and showed a layered appearance with calcofluor white staining. It started in early June in the center of the seed and proceeded centrifugally such that the outer cells showed cell wall thickening in late June. Thickened cell walls were soft and PAS positive at inception, but staining disappeared and hardness increased during wall maturation. Cell elongation in the radial direction accompanied wall thickening. Protein body formation started after cell wall thickening and followed the same centrifugal developmental pattern. Mature protein bodies occurred in even the outermost cells by early July. No further structural changes occurred after this time. The high molecular weight storage proteins appeared in late June, which is when protein bodies had formed in all but the outer endosperm cells; however, these proteins did not appear simultaneously and minor changes in protein bands continued until maturation. α-Galactosidase activity was present in the developing endosperm and peaked at 13 wk after pollination. The data suggest that the thickened wall is deposited as a highly substituted galactomannan, but that most of the galactose side branches are clipped off presumably by α-galactosidase during cell wall polymerization.     

Sex differences in heritability of BMI: a comparative study of results from twin studies in eight countries.

Body mass index (BMI), a simple anthropometric measure, is the most frequently used measure of adiposity and has been instrumental in documenting the worldwide increase in the prevalence of obesity witnessed during the last decades. Although this increase in overweight and obesity is thought to be mainly due to environmental changes, i.e., sedentary lifestyles and high caloric diets, consistent evidence from twin studies demonstrates high heritability and the importance of genetic differences for normal variation in BMI. We analysed self-reported data on BMI from approximately 37,000 complete twin pairs (including opposite sex pairs) aged 20-29 and 30-39 from eight different twin registries participating in the GenomEUtwin project. Quantitative genetic analyses were conducted and sex differences were explored. Variation in BMI was greater for women than for men, and in both sexes was primarily explained by additive genetic variance in all countries. Sex differences in the variance components were consistently significant. Results from analyses of opposite sex pairs also showed evidence of sex-specific genetic effects suggesting there may be some differences between men and women in the genetic factors that influence variation in BMI. These results encourage the continued search for genes of importance to the body composition and the development of obesity. Furthermore, they suggest that strategies to identify predisposing genes may benefit from taking into account potential sex specific effects.     

Heritability of adult body height: a comparative study of twin cohorts in eight countries.

A major component of variation in body height is due to genetic differences, but environmental factors have a substantial contributory effect. In this study we aimed to analyse whether the genetic architecture of body height varies between affluent western societies. We analysed twin data from eight countries comprising 30,111 complete twin pairs by using the univariate genetic model of the Mx statistical package. Body height and zygosity were self-reported in seven populations and measured directly in one population. We found that there was substantial variation in mean body height between countries; body height was least in Italy (177 cm in men and 163 cm in women) and greatest in the Netherlands (184 cm and 171 cm, respectively). In men there was no corresponding variation in heritability of body height, heritability estimates ranging from 0.87 to 0.93 in populations under an additive genes/unique environment (AE) model. Among women the heritability estimates were generally lower than among men with greater variation between countries, ranging from 0.68 to 0.84 when an additive genes/shared environment/unique environment (ACE) model was used. In four populations where an AE model fit equally well or better, heritability ranged from 0.89 to 0.93. This difference between the sexes was mainly due to the effect of the shared environmental component of variance, which appears to be more important among women than among men in our study populations. Our results indicate that, in general, there are only minor differences in the genetic architecture of height between affluent Caucasian populations, especially among men.     

青海省野牛沟地区主要兽类的数量与保护

作者于１９９０～１９９２年在青海省中部未受保护的野牛沟地区进行以有蹄类物种为重点的野生动物考察。考察结果表明：藏羚羊、藏原羚、野牦牛和岩羊的数量都超过１０００只,藏野驴约８００只,盘羊近２５０只,白唇鹿未估计数量。对其他１０种兽类也进行了考察。尽管有法律保护野生动物,但偷猎行为并没有得到控制。因此,必须尽快建立野牛沟自然保护区或野生动物管理区。     

Plant regeneration from protoplasts isolated from cotyledons of Sesbania bispinosa

Protoplasts were isolated from cotyledons of Sesbania bispinosa (Jacq.) W.F. Wight. In a liquid-over-agar culture system with Murashige and Skoog (MS) medium supplemented with 1 mg l^-1 2,4-dichlorophenoxyacetic acid (2,4-d, 2 mg l^-1 benzyladenine (BA), 1 mg l^-1 glutamine and 0.5 and formed callus. The first division occurred after 3–4 days. Callus formed from the protoplasts differentiated shoots by organogenesis on MS medium with 1 mg l^-1 indolebutyric acid (IBA) and 1 mg l^-1 BA. These shoots developed into complete plantlets when excised and cultured on MS medium with 0.5 mg l^-1 IBA.     

Bcl-2 and Fas/APO-1 regulate distinct pathways to lymphocyte apoptosis.

Activation of the cell surface receptor Fas/APO-1 (CD95) induces apoptosis in lymphocytes and regulates immune responses. The cytoplasmic membrane protein Bcl-2 inhibits lymphocyte killing by diverse cytotoxic agents, but we found it provided little protection against Fas/APO-1-transduced apoptosis in B lymphoid cell lines, thymocytes and activated T cells. In contrast, the cowpox virus protease inhibitor CrmA blocked Fas/APO-1-transduced apoptosis, but did not affect cell death induced by gamma-radiation or serum deprivation. Signalling through Fas/APO-1 did not down-regulate Bcl-2 or induce its antagonists Bax and Bcl-xS. In Fas/APO-1-deficient lpr mice, Bcl-2 transgenes markedly augmented the survival of antigen-activated T cells and the abnormal accumulation of lymphocytes (although they did not interfere with deletion of auto-reactive cells in the thymus). These data raise the possibility that Bcl-2 and Fas/APO-1 regulate distinct pathways to lymphocyte apoptosis.