草鱼血液的研究

本文报道了212尾池养草鱼Ctenopharyngodon idellus的血液中红细胞数、自细胞数、血红蛋白值、红细胞脆性值、比积及比重值、血细胞沉降率、白细胞分类计数和各型血细胞体的大小等正常数值和上述常数值在雌雄个体上的差异,以及鱼体年龄和繁殖季节产卵前后的差异等,为草鱼血液的常数值提供了较为系统的资料。     

Influence of Meloidogyne hapla on Alfalfa Yield and Host Population Dynamics

Self-thinning in alfalfa, a dynamic process involving the progressive elimination of the weakest plants, was enhanced by Meloidogyne hapla. Alfalfa stand densities decreased exponentially with time and were reduced 62% (P = 0.05) in the presence of M. hapla. As stand densities decreased over time, mean plant weights increased at a rate 2.59 times faster in the absence of M. hapla. In a stepwise multiple regression analysis, 65% of the total variation in yield could be explained by changes in stand density and 85% by average weight of individual stems. Alfalfa yields were suppressed (P = 0.05) by M. hapla, with suppression generally increasing with time and as the nematode population density increased. Yield suppression was attributable primarily to the decline in plant numbers and to suppression in individual plant weights.     

Efficient selection intensity in early generation index selection in groundnut (Arachis hypogaea L.)

Summary The F₂ potential of single and three-way crosses was evaluated using a set of physiological and yield components. Results were based on an index of selection using (a) only yield components and (b) both physiological and yield components. The indices were constructed using the percentage improvement of F₂ over the better parent of the corresponding F₁ cross for every character. The performance of F₂ plants assessed by the expected value of the regression index was ranked in descending order to provide a ranked F₂ distribution (FRD). The FRD was divided into four equal parts, T₂₅ (top 25%), T₅₀ (26–50%), T₇₅ (51–75%) and T₁₀₀ (76–100%). F₃ families derived from F₂ plants in T₂₅ were found to provide a higher frequency of selections for pod number than T₅₀, T₇₅ and T₁₀₀. The frequency of selections was higher in three-way than single crosses. Selection index based on physiological and yield components was more efficient in trapping F₂ plants providing selections in F₃ than the index based on yield components only. The results brought out the importance of bunch x bunch crosses as a complement to the usually advocated bunch x runner ones.     

Stoichiometry of proton uptake in isolated pea chloroplasts under different light intensities

The number of protons released inside the chloroplast thylakoids per electron which is transferred through the electron transport chain (H⁺/e^– ratio) was measured in isolated pea chloroplasts at pH 6.0 under continuous illumination and with methyl viologen as an electron acceptor. At saturating light intensity (200 W · m^–2) (strong light) the H⁺/e^– ratio was 3. At low intensity (0.9 W · m^–2) (weak light) the H⁺/e^– ratio was 2 with dark-adapted chloroplasts, but it was close to 3 with chloroplasts that were preilluminated with strong light. It is shown that the presence of azide in the reaction mixture leads to errors in the determination of the H⁺/e^– ratio due to underestimation of the initial rate of H⁺ efflux on switching off the light. To explain the above data, we assume that transformation of the electron transport chain occurs during illumination with strong light, namely, the Q cycle becomes operative.     

An experimental evaluation of diversity indices as environmental discriminators

Seven diversity indices were calculated for each of fifty-eight microcosm communities. All fifty-eight communities were initiated from equal density inoculations of fourteen algal species. Each microcosm developed in one of six controlled experimental environments; the environments differing only in their temporal patterns of disturbance. Five linear discriminating techniques were used to evaluate the diversity index most useful for discriminating between these environments. The Shannon-Wiener index was best according to two of the discriminating methodologies and second best using the other techniques. Evenness was best when the Shannon-Wiener index was second best and vice versa.     

Intrinsic competition between the gregarious parasite,Cotesia glomeratus and the solitary parasite.Cotesia rubecula [Hymenoptera: Braconidae] for their host.Artogeia rapae [Lepidoptera: Pieridae]

The solitary endoparasite,Cotesia rubecula, was superior to the gregarious endoparasite,Cotesia glomeratus, in tests of intrinsic competition for their hostArtogeia rapae. When an egg ofC. rubecula was oviposited in the host prior to those ofC. glomeratus, C. rubecula always won the ensuing competition. When an egg ofC. rubecula was laid in the same host within 48 h after oviposition byC. glomeratus, C. rubecula was successful in more than 90% of the interactions. Even when the egg ofC. rubecula was oviposited in the same host 72 to 96 h after oviposition byC. glomeratus, C. rubecula won the competition approximately 33% of the time. The implications of intrinsic competition are discussed in relation to the establishment ofC. rubecula in an ecosystem containingA. rapae andC. glomeratus.      

Social stimulation and the resumption of copulation in Rhesus (Macaca mulatto) and stumptail (Macaca arctoides) Macaques

Copulatory data derived from observations of social groups of rhesus and stumptail macaques were analyzed to test the hypothesis that pairs of animals would resume copulation significantly sooner if a second male copulated with the female shortly after the first male’s ejaculation. Data from both groups supported the hypothesis. These results, extending previous studies in Macaca nemestrina,suggest that the shortening of copulatory intervals by social stimuli occurs in several species, both in social groups and in experimentally created triads. These findings also are consistent with the hypothesis that socially mediated resumption of mating is related to intrasexual competition among males.     

Vertical community structure and resource utilization in neotropical forest cockroaches

ABSTRACT.

• 1 Patterns of vertical habitat use of ten species of cockroaches are examined. Three assemblages of cockroaches are recognized on the basis of morphology, foraging behaviour, foraging heights, and overlaps and breadths of vertical distributions.
• 2 Three apterous and brachypterous species occur near the ground and comprise one assemblage. They feed mainly on material in the leaf-litter.
• 3 Species that perch higher either migrate into the leaf-litter on a diel basis and feed on both leaf-litter and epiphyllic materials, or some are strictly arboreal and forage on algae, liverworts, lichens, spores, pollen and trichomes on the surfaces of leaves.
• 4 Trophic and behavioural correlations with perch height are described and the functions of perching are examined.
• 5 We conclude that studies of interactions among species are confounded by our lack of understanding of stage- and sex-specific interactions of coexisting species. A simplistic ‘species’approach to such interactions is inadequate because it does not recognize intraspecific variation.