Breeding of Barbus bynni (Pisces,Cyprinidae) in Jebel Aulia Reservoir,Sudan

Barbus bynni begins to mature at Age IV. Ripening of gonads of mature fish starts in May when water temperature approaches the annual maximum. However, the spawning season coincides with the onset of the flood season in July. These facts, as well as the cyclic growth of the gonads, show that B. bynni spawns once a year. Fecundity varies with size of fish and gonads. However, this levels off in the middle size group. At this age the fecundity was estimated to be 1 424 693 eggs.     

Seasonal abundance,breeding and sex-structure of populations of Tilapia nilotica (L.) and Labeo niloticus (F.) in the Jebel Aulia Dam area of the White Nile

Seasonal abundance, maturation and sex-structure were studied in populations of T. nilotica and L. niloticus in the Jebel Aulia reservoir and in the White Nile below the dam. L. niloticus showed a single annual breeding cycle from mid-July to December and was most abundant in October in the lake, and in early November in the river. T. nilotica showed two distinct annual seasons of abundance: summer (April to June) and autumn (November to October). Spawning activity was highest in summer (April to June) and autumn (late July to September). The sex-ratio varied inversely with age (size); males were predominant in populations of older fish, perhaps because of their greater endurance to adverse conditions as evidenced by their better survival in hypoxic water.     

大鼠非致瘤四倍体细胞系的建立及细胞遗传学和酶学特征

从大鼠自然诱发的肉瘤细胞中,我们建立了一个四倍体细胞系(4n=84),命名为RC(ratcell)。它具有典型的成纤维细胞外形,能在玻璃表面贴壁生长,但不能生长在琼脂半固体培养基中。该细胞在含15％小牛血清的RPMI 1640培养基中生长良好,至今已连续繁殖112世代,细胞群体倍增时间约为15小时。染色体G-带分析表明,RC为整四倍体细胞,它的1条X染色体在第32至34区为均染区。RC细胞核仁组织者(NORs)活性显然比大鼠二倍体细胞NORs活性的加倍还高(P<0.001)。这个具有非常高NORs活性的RC细胞系对于研究细胞18S+28S rRNA基因转录活性的调控、基因表达与基因剂量关系有一定的意义。RC细胞还有异常高的磷酸酯酶活性,而且它的同工酶谱也与大鼠肌肉细胞明显不同。体内接种实验和扫描电镜的观察表明,RC是非致瘤细胞。RC细胞各号染色体的C-带图样与大鼠二倍体细胞无明显的差异。     

横断山区四种湍蛙的细胞遗传学研究

通过染色体组型分析,C带(BSG技术)分析及一种简便的Ag-NORs带分析,对四川湍蛙、理县湍蛙、棕点湍蛙和棘皮湍蛙的种间关系、染色体的演化及其性染色体等问题进行了初步探讨。结果表明:(1)四川湍蛙、理县湍蛙和棕点湍蛙之间的亲缘关系较近,而它们与棘皮湍蛙的亲缘关系较远;(2)在近缘种的分化中,染色体结构异染色质的变化和臂间倒位是重要的因素之一,这在小型染色体上表现得尤为突出;(三)四川湍蛙具有在形态上分化很明显的性染色体。C带分析表明,此性染色体主要由常染色质构成,但在其Y染色体的长臂上存在明显的中间C带,推测尚处于性染色体分化的初期阶段。     

Selection for yield and yield components in the early generations of a potato breeding programme

Summary A number of unselected potato (Solanum tuberosum L.) clones were grown at two locations (a seed site and a ware site) in three consecutive years. The repeatability of total yield and yield components in the first two clonal years was compared with the same characters recorded in the third clonal year. Selection for yield in the first clonal year was only marginally more effective than a random reduction in number of genotypes, while selection in the second clonal year appeared to be somewhat more effective as judged by performance in the third clonal year. The inefficiency of selection in the first clonal year was ascribed, at least in part, to the inaccuracy of yield assessment as well as the carry-over effect of the mother tubers. Correlations of total yield were higher between different years in the same location than between different locations. Selection under growing conditions suitable for production of seed tubers tended to result in selection of early maturing clones which would not necessarily be optimal for ware growing conditions.     

Reproductive strategies of the orang-utan: New data and a reconsideration of existing sociosexual models

Recent field data indicate that MacKinnon’s model of the orang-utan’s sexual and agonistic activity needs to be revised. In this model, male reproductive activity is concentrated in an extended phase of subadulthood and in early adulthood. According to this model, the role of older adult males is primarily that of range guardian, and in that role they would ensure that the offspring they had generated earlier would have safe access to food resources. This study presents cases suggesting that subadult males, even though sexually active, may have low reproductive success. In previous studies adult males were shown to display less sexual initiative than subadult males. In this study an adult male was at times involved infrequent mating activity in response to proceptive activity of females in the course of consortship. This adult male proved to be a successful breeder, thus refuting the hypothesis of adult male sterility. The female is most likely to conceive through cooperative mating in lengthy consortships with the dominant resident adult male. We hypothesize that the extended subadult phase represents a submissive strategy, allowing subadult males to remain in the home range of adult males but with minimal reproductive success.     

Chromosome numbers and reproduction inRubus subgen.Malachobatus

A review of current knowledge of chromosome numbers and modes of reproduction in the genusRubus L. is presented. Chromosome numbers from some species of subg.Malachobatus Focke together with results of crossing experiments are reported for the first time.     

Biochemical and autoradiographic studies of TRH receptors in sections of rabbit spinal cord

Receptors for thyrotropin-releasing hormone (pGlu-His-Pro-NH2, TRH) on thaw-mounted sections of rabbit spinal cord have been identified biochemically and visualized by light microscopic autoradiography. Binding of [3H] [3-Me-His2]TRH to 20 microns sections exhibited high apparent affinity and a pharmacological specificity almost identical to that previously demonstrated for spinal TRH receptors in membranes. In autoradiograms, the highest density of TRH receptors appeared in the substantia gelatinosa of the dorsal gray and around the central canal, with intermediate levels in the ventral gray.     

Syntheses and biological activities of azido ubiquinone derivatives

A general method for the synthesis of azido-ubiquinone derivatives has been developed directly by substituting one hydrogen atom on the benzoquinone ring with an azido group under weakly acidic conditions. The reaction takes several hours and the yield is generally low. The azido-ubiquinone was purified by preparative thin layer chromatography, and identified by NMR, IR and mass spectra. All the synthesized azido-ubiquinone derivatives show partial activity in mediating biological electron transfer in the dark, and show partial or complete inhibition upon photolysis.