Species variations amongst proteinases in liver lysosomes

Cathepsin B, H, L and D activities in liver lysosomes were compared between species. Although cathepsin B and D were detected in bovine, pig, chicken and rat liver, striking species differences were evident for cathepsin H and L. Cathepsin L activity was particularly high in chicken lysosomal extracts, but could not be detected in bovine and pig extracts. Whereas there was no significant cathepsin H activity in bovine extracts, rat liver lysosomal extracts contained large amounts of cathepsin H activity.     

Food acquisition by competing surfperch on a patchy environmental gradient

Synopsis Black surfperch, Embiotoca jacksoni, and striped surfperch, Embiotoca lateralis, coexisted along steep sloping rocky habitats at Santa Cruz Island, California. The range of depths occupied (to 15 m) was characterized by a strong gradient in abundance of prey and a changing mosaic of substrate types from which surfperch harvested food. Availability of prey and diversity of benthic substrates were greatest in shallowest areas and both declined with increasing depth. Individuals of both surfperch species were residential within a narrow range of depths, with the result that different segments of their populations were consistently exposed to different foraging environments. These two phenomena (residential behavior combined with a gradient in availability of resources) resulted in variation in foraging behaviors and diets among individuals that resided at different depths. The pattern of within-population variation differed between the surfperch species. Black surfperch individuals achieved similar taxonomic diets and expended similar foraging effort at all depths, but deep-water foragers captured much less prey biomass per unit effort. The taxonomic composition of striped surfperch diets differed among depths, and although similar amounts of prey biomass were captured everywhere, individuals in deep areas expended much greater effort to obtain that level of food return. For both species, habitat profitability (food return to foraging effort) declined with depth. The difference in habitat profitability appeared to influence fitness components of both surfperches. Individuals occupying deep habitats were about 5% shorter in standard length than conspecifics of the same chronological age living in shallow areas; the disparity in body size resulted in an estimated difference in clutch size of 10–18%.     

Testing for ecophenotypic variation in a benthic foraminifer

A method for identifying ecophenotypic variants is tested, using two morphological variants of the benthic foraminifer Reophax dentaliniformis Brady from the Baltic Sea. Results show that the example does not correspond to the model for ecophenotypic variation. This is interpreted as showing that the two forms are genetically differentiated and that the gene flow between them is restricted by the water circulation pattern in the Baltic.     

Pregnant mares' serum gonadotropin source influences fertilization and fresh or thawed embryo development,but the effect is genotype specific

The influence of the source of pregnant mares' serum gonadotropin (PMSG) on the num ber, quality, and in vitro development of mouse embryos before and after freezing was evaluated among three genotypes: N:NIH(S), C57BL/6N, and C3H/HeN-MTV^?. Immature females were given PMSG from one of five commercial sources. Following col lection ( 116 hr later), embryos were evaluated for stage of development, and four-to eight-cell embryos were pooled within genotype and assigned to standardized fresh or freeze-thaw culture trials. Different PMSG sources stimulated the production of different num bers of total embryos (P < 0.05) but not necessarily more embryos suitable for freezing. Differences in embryo production among genotypes indicated that absolute embryo num bers using a single mouse genotype may not accurately reflect the potency of a specific gonadotropin source. The PMSG source also affected the ability of an embryo to survive in culture either immediately after collection or after frozen storage. The effect, however, was genotype specific, with some mouse strains being relatively insensitive to PMSG source, whereas gonadotropin source played a major role in determining in vitro viability in others. Development rates for freshly collected embryos differed, often inconsistently, from those of thawed embryos regardless of the PMSG source used, demonstrating that fresh embryo development cannot be used to estimate expected post-thaw survival. In vitro development of thawed embryos is influenced not only by genotype, but also the source of the gonadotropin used to promote follicular development and oocyte maturation. These findings may explain, in part, the wide variation in embryo viability and culture rates reported among laboratories and intraspecies animal populations.     

Analysis of variations of handling-time inTrichogramma maidis

Variation in handling-time is studied in the association betweenTrichogramma maidis Pintureau & Vœgelé [Hym.: Trichogrammatidae] and one of its factitious hosts: the eggs of the Mediterranean flour mothEphestia kuehniella Zeller [Lep.: Pyralidae]. It is shown that the duration of egg laying behaviour decreases exponentially from the first host egg encountered onwards. This decreasing kinetic, which corresponds to a learning ability, shows a high variability between females, but a mother-daughter regression analysis fails to demonstrate any genetic transmissibility of this learning ability over 2 successive generations. Once the learning is over, there remains a residual variability which is, in part, under genetic control. The possible consequences of these results on the stability of host-parasite associations are discussed.      

GENETIC RELATEDNESS OF TWO POPULATIONS OF THE SOUTHERN ELEPHANT SEAL, MIROUNGA LEONINA

Blood samples from southern elephant seals ( Mirounga leonina ) from Heard and Macquarie Islands were surveyed electrophoretically for protein variation. Thirty proteins encoded by a minimum of 35 loci were screened, four of which were found to be polymorphic. Statistically significant differences in allele frequencies were found between the two populations at three loci. Heterozygosity estimates for the Heard and Macquarie island populations were 0.034 ± 0.020 (mean ± standard error) and O.029 ± 0.017 respectively, with a Nei distance of 0.007. The findings suggest that the two populations may have diverged genetically and very limited gene flow exists between the islands, a finding consistent with limited information from mark-recapture studies.     

大豆-根瘤菌共生体系光合与固氮关系研究

水培大豆和田间生长的大豆,接种根瘤菌 Rhizobium B16-11C 后植株全氮含量、叶片叶绿素含量和净光合速率及种子产量都明显增加。比较 Clark 大豆的结瘤品系和不结瘤品系获类似结果。摘除根瘤后3天内叶片净光合速率无明显变化。大豆植株遮阴、去叶或切掉地上部导致根瘤活性明显下降。但去豆荚不能提高根瘤固氮的比活性。根瘤活性的日变化不能用根瘤蔗糖、淀粉含量或周围温度的变化来解释,其控制因子尚待深入研究。     

南京地区繁缕和小繁缕群体的研究

繁缕(Stellaria media)和小繁缕(S.apetala)是两个形态相似的近缘种,有人把后者作为前者的亚种或变种来处理。本文通过对南京地区不同生境的三个自然群体和三个人工控制栽培群体的取样,以群体为单位,分别测算了叶、萼片、雄蕊、花瓣、果实和种子的8个数量性状的变异,绘制了多角形图;对花粉粒和种子进行了扫描;还通过花蕾套袋试验对种子活力作了检查。结果发现繁缕和小繁缕都是近亲繁殖植物,在形态上区别明显,对生态环境的要求基本相同,但小繁缕似更能耐受人为的践踏和刈割。     

Genetic variation and population structure of cod, Gadus morhua L., in some fjords in northern Norway

Biochemical genetic polymorphism in cod from several fjords in Troms, northern Norway was analysed. Gene frequencies at several polymorphic loci ( Hb, Pgi, Ldh, Pgm, Gpd and Idh ) are given. Significant variation was found both within and between fjords, and even between samples from the same locality sampled in different years, indicating a mosaic structure of the cod population in the area studied. The results of the haemoglobin variation are compared to similar results obtained more than 20 years ago in the same and adjacent areas. The biochemical genetic variation is discussed in relation to stability of gene frequencies, isolation mechanisms and migration patterns.