红豆草组织培养物的超低温保存及其超微结构的观察

红豆草(Onobrychis viciaefolia Scop.)组织培养物在5%DMSO+10%甘油+8%蔗糖的冰冻保护剂及以1℃/分钟的速度降温到-35—-40℃,停留2小时后,投入液氮,40℃水浴快速化冻等条件下,存活率达60—70%,并保持了高的分化能力。电子显微镜的观察结果表明,快速冰冻和1℃/分钟慢速冰冻至-35℃—40℃不停留,对细胞结构造成严重的致死性破坏;-35℃停留30分钟对细胞结构的损伤是可逆性的;停留2小时的其超微结构基本上与对照材料无明显差别。     

Sex determination in the dioecious Melandrium

Summary Melandrium album (2n=24), a dioecious species with heteromorphic sex chromosomes (XY, males and XX, females), has a strong genetic commitment for sex determination. We report here a procedure for obtaining haploid plants from cultured anthers and show that genotype, pollen stage, cold treatment and certain culture media components are essential for a reproducible yield of embryos. Our procedure increased the number of responsive anthers and not the number of responsive microspores per anther. Most likely, our experimental system allows the recovery of competent microspores, and this on a medium containing either an auxin or a cytokinin. All of the 36 anther-derived plants tested expressed a female phenotypic sex instead of the theoretical one male one female ratio. When analysed cytologically, the plants exhibited the corresponding female genetic sex (one or two X chromosomes).     

厦门附近海域浮游甲藻类的分布

本文报道了厦门附近海域浮游甲藻类49种,并对其生态特性以及与海洋环境因素的关系进行了详细研究与讨论。分析的204号样品,系1980年9月至1981年8月,逐月采自厦门海域的浔江区(Ⅰ区),西港区(Ⅱ区)和九龙江口区(Ⅱ区)。     

四川宝兴雉类生态和垂直分布的调查研究

宝兴位于四川盆地西缘山地,境内纵贯世界闻名的大雪山——即夹金山。 自19世纪30年代至20世纪30年代,先后有Verreaux(1838—1871),Geoffroy(1866),David(1871),Seinhoe(1871),Sharpe(1875),David et Oustalet(1877),Oustaler (1891—92),Styan(1899),Laubmann(1920),La Touch(1925—30),Smith(1931—34),Bangs(1932),Seys(1934)等对宝兴进行过调查和采集,而我     

Subcellular Distribution of UDP-Galactose:Ceramide Galactosyltransferase in Rat Brain Oligodendroglia

Oligodendrocytes isolated from 18-19-day-old rat brain were homogenized in 0.32 M sucrose. The homogenate was centrifuged at 100,000 g for 50 min in a gradient containing 0.8, 1.05, and 1.3 M sucrose. Three discrete bands were obtained at the interfaces 0.32-0.8 (F1), 0.8-1.05 (F2), and 1.05-1.3 M (F3). The distribution of UDP-galactose:ceramide galactosyltransferase (CgalT) activity in each fraction was measured using liposomes containing normal fatty acid-containing ceramides (NFA-CgalT activity) or 2-hydroxy fatty acid-containing ceramides (HFA-CgalT activity). Although detection of both CgalT activities was possible in all fractions, HFA-CgalT activity was enriched in F1 and F2 fractions, which also showed an enrichment of Golgi and endoplasmic reticulum markers, respectively. It is interesting that NFA-CgalT activity was significantly enriched in the F2 fraction. These results suggest that hydroxylated and nonhydroxylated galactocerebrosides may be synthesized at different intracellular locations.     

Distribution of the Glucose-1,6-Bisphosphate System in Brain and Retina

The distribution of glucose-1,6-bisphosphate (G16P2) synthase was measured in more than 70 regions of mouse brain, and nine layers of monkey retina. Activities in gray areas varied as much as 10-fold, in a hierarchical manner, from highest in telencephalon, especially the limbic system, to lowest in cerebellum, medulla, and spinal cord. The synthase levels were significantly correlated among different regions with G16P2 itself, as well as with previously published levels of a brain specific IMP-dependent G16P2 phosphatase. In contrast, neither G16P2 nor either its synthase or phosphatase correlated positively with phosphoglucomutase, and in all regions the G16P2 levels greatly exceeded requirements for activation of this mutase. This strengthens the view that G16P2 has some function besides serving as coenzyme for phosphoglucomutase. However, attempts to correlate the "G16P2 system," as defined by the three coordinately related elements, synthase, phosphatase, and G16P2, with other enzymes of carbohydrate metabolism, or with regional data of Sokoloff et al. [J. Neurochem. 28, 897-916 (1977)] for glucose consumption, were unsuccessful. This leaves open the possibility that brain G16P2 might serve as a phosphate donor for specific nonmetabolic effector proteins.     

Studies on the Tissue Distribution of the Puromycin-Sensitive Enkephalin-Degrading Aminopeptidases

An antiserum generated to the soluble form of the rat brain puromycin-sensitive enkephalin-degrading aminopeptidase was used to determine the tissue distribution of the soluble and membrane-associated forms of this enzyme. All tissues examined contained significant levels of the soluble enzyme form, with this enzyme accounting for greater than 90% of the arylamidase activity in brain, heart, and skeletal muscle. Native gel electrophoresis coupled with activity staining as well as inhibition studies were used to confirm the presence of this enzyme in various tissues. Serum was found not to contain this particular aminopeptidase. In contrast to the results obtained with the soluble enzyme form, brain was the only tissue found to contain the membrane-associated enzyme form. Although all tissues contained membrane-associated aminopeptidase activity only the brain enzyme could be maintained in solution in the absence of detergent. In addition, the brain membrane-associated enzyme could be distinguished from the membrane-associated aminopeptidase activity in other tissues on the basis of its sensitivity to inhibition by puromycin.     

Altered tissue specificity of the revertant shrunken allele upon Dissociation (Ds) excision is associated with loss of expression and molecular rearrangement at the corresponding non-allelic isozyme locus in maize

Summary Transposable element Activator (Ac) induced wild-type stable revertants, derived from McClintock's Dissociation (Ds) insertion shrunken (sh) mutant sh-m5933, have been examined for sucrose synthases, SS1 and SS2, encoded by the revertant (Sh) locus and the non-allelic gene Sus (previously designated as Ss2), respectively. A structurally normal Sh locus has been previously described in these revertants. Immuno-blot (Western) and Southern hybridization analyses reported here identify one of the nine alleles, Sh-r5, as unique for several features. It showed altered tissue specificity, as the SS1 protein encoded by the Sh-r5 allele was readily detectable in the immature embryo which is otherwise characterized by the Sus expression only. The level of Sh-r5 expression at the protein and enzyme level was marked by endosperm specific SS1 abundance and a significant down-regulation in the embryo similar to the standard Sh and Sus loci in endosperm and embryo, respectively. We infer that tissue specific levels of gene expression among maize Ss genes is significantly determined by trans-regulatory factors present in these two tissues. The Sh-r5 strain also exhibited a complete loss of the Sus expression in all tissues tested in the plant. Lack of any detectable phenotypic abnormality in the Sh-r5 strain due to the loss of SS2 protein indicated that either the SS2 protein is nonessential or that the two SS isozymes are functionally compensatory. Genomic filter hybridizations with the Sus cDNA clone indicated that the Sus locus in the Sh-r5 strain was not deleted and was, in fact, unique among these revertants. Together, these data provide an unusual insight into the regulation and function of the two SS isozymes in the maize plant.     

Seed abortion in wind-dispersed pods of Dalbergia sissoo: maternal regulation or sibling rivalry?

Summary Dalbergia sissoo, a wind-dispersed tropical tree, shows a positively skewed distribution of seeds per pod. This is attributed to the enhanced dispersal advantage of few-seeded pods due to their reduced wing loading (ratio of weight to pod surface area) and low settling velocity. The proximate mechanisms causing the positively skewed distribution were investigated. The distribution could not be attributed to the distribution pattern of ovule number per ovary, pollen grain limitation, lack of ovule fertilization, or post-fertilization elimination of many-seeded pods. Rather, it was caused by the post-fertilization abortion of seeds within a pod 2 weeks after fertilization. This intra-pod seed abortion (IPSA) is due to a dominance hierarchy of fertilized ovules from the distal (near stigma) to the basal end, generated by the temporal differences in fertilization. The dominant developing seeds at the distal end cause the abortion of others through the production and diffusion of an aborting agent. When the dominance hierarchy of the siblings is not intense, pods are formed with more than one seed. We argue that the positively skewed distribution of seeds per pod is not due to maternal regulation but is a result of sibling rivalry. We propose that this sibling rivalry is generated by genetic differences in pollen grain fitness and disucss the results in the context of parent-offspring conflict.