The effects of immune rhesus monkey serum on schistosomula of Schistosoma mansoni during cultivation in vitro

Clegg J. A. and Smithers S. R., 1972. The effect of immune rhesus monkey serum on schistosomula of Schistosoma mansoni during cultivation in vitro. International journal for Parasitology2: 79–98. The sera of rhesus monkeys hyperimmunized by 2–4 exposures to S. mansoni cercariae contain an antibody lethal to schistosomula cultivated in vitro. The antibody (IgG) is dependent on labile factors in fresh monkey serum. It can be absorbed by adult worms cultivated in vitro and it is not the antibody responsible for CHR or COP reactions. A titre of lethal antibody sufficient to kill all schistosomula in vitro is maintained for 2–3 months following challenge: it then falls to a moderate level which may be retained for several years. After inactivation, hyperimmune serum inhibits the growth of cultured schistosomula but does not kill them. Following a small primary infection rhesus serum develops a marked growth-inhibiting property and a low titre of lethal antibody at about 4 months, i.e. the time when resistance to reinfection can first be reliably demonstrated.     

日本血吸虫皮肤型童虫透射电镜观察

本文报道应用透射电镜观察并比较0.5、3和12小时龄的日本血吸虫皮肤型童虫的超徽结构特征。结果表明,除了外质膜外,其他的超微结构,如体被、肌层、体被下细胞、胞质桥、头腺、钻腺和食道等结构在尾蚴感染后3小时均未见再有明显的变化。     

浙江桂及其相近种的亲缘关系及分类等级探讨

浙江桂、普陀桂和日本桂(天竺桂)是樟属植物中的三个相近种。六十多年以来,围绕着它们的亲缘关系及其分类等级,植物学界展开了反复的讨论,至今仍然存在着较大的分歧。在文献考证的基础上,笔者通过赴模式产地考察与采集鉴定,从比较形态学、扫描电镜观察、种子油脂成份的化学分析和地理分布区等方面,进一步研究了这三个种的异同,认为浙江桂是中国大陆的特有种;普陀桂应当归并入日本桂,作为一个变种处理;日本桂的原变种在中国仅见产于台湾省,而在大陆并无自然分布。     

免疫血清及补体对体外培养日本血吸虫童虫的杀伤作用

本文报道抗体、补体、补体加抗体对机械转变日本血吸虫童虫的杀伤作用,并比较其杀伤效率。用光学显微镜及扫描电镜观察形态变化。结果显示杀伤率为补体加抗体>单纯补体>单纯抗体。除去补体血清中的B因子,杀伤率明显下降,说明补体C_3旁路途径参与杀伤童虫的作用。童虫孵育于含有补体及抗体的培养基中72h后,虫体头背部体棘零乱或消失,有些体被破损及脱皮。     

Freshwater snails of São Tomé, with special reference to Bulinus forskalii (Ehrenberg), host of Schistosoma intercalatum

São Tomé Island has 3 known taxa of freshwater gastropod, here identified to species for the first time; Neritina afra Sowerby, Ferrissia eburnensis Binder and a distinctive form of Bulinus forskalii (Ehrenberg). The Bulinus acts as intermediate host for the parasite Schistosoma intercalatum Fisher, the cause of human schistosomiasis in foci of infection detected in recent years on São Tomé. A morphological characterization of this snail is presented, in respect of the shell, radula and copulatory organ. It is compared with B. forskalii populations sampled on the African mainland (Nigeria, Cameroon, Gabon and Angola) and with related taxa. Despite differences in the shell from the commonly found form of B. forskalii it seems appropriate to identify the São Tomé population as an extreme conchological variant of this taxon.     

Purification and characterization of soybean nodule nitrite reductase

A nodule cytosol nitrite reductase was isolated from soybean [ Glyine max (L.) Mer. cv. Tracy] grown in the presence of nitrate. Enzyme activity increased when increased amounts of nitrate were supplied to the plant. A purification procedure involving ammonium sulfate precipitation, gel filtration, DEAE Sephadex and Blue Sepharose chromatography resulted in an activity capable of forming 6.7 μmol ammonia (mg protein)⁻¹ min⁻¹. This represented a 235-fold increase in specific activity. The molecular weight, estimated by gel filtration, was 55 000. The pH optimum for activity was 7.1. Ammonia formed stoichiometrically as nitrice was consumed. From Lineweaver-Burk plots, K_m values of 0.5m M for nitrite and 0.2m M for methyl viologen were calculated. Spectral data suggest the association of a heme chromophore with the enzyme.     

The Glycine–Glomus–Rhizobium symbiosis. IV. Interactions between the mycorrhizal and nitrogen-fixing endophytes

Abstract Soybean (Glycine max (L.) Men) plants were grown under controlled conditions in an experiment designed as a 4 × 4 factorial. The factors were N or P nutrition, with different strains of Rhizobium japonicum or N-fertilization as levels of the first factor and different species of vesicular-arbuscular mycorrhizal (VAM) fungi or P fertilization as levels of the other. Organisms used were R. japonicum strains USDA 110, USDA 136, and 61A118, and the VAM fungi Glomus versiforme (Karst.) Berch, Glomus fasciculatum (Thaxt. sensu Gerd.) Gerd. and Trappe, and Glomus mosseae (Nicol. & Gerd.) Gerd. and Trappe. There were 16 treatments: nine Rhizobium + Glomus combinations, three Rhizobium + V and three Glomus+ N combinations, and one non-symbiotic set of plants supplied with N + P. The tripartite symbioses were evaluated by analysis of variance against the Rhizobium + P and Glomus + N comparison treatments for effects on root and leaf dry mass, root N and P content, nodule mass and activity, and VAM colinization. Significant to highly significant main effects and interactions were found in virtually all evaluations due to both Rhizobium strain and VAM–fungal species. We conclude that different endophyte isolates affect not only the host plant, but also the development and function of their co-endophytes. These findings establish the existence of inter-endophyte compatibility, an important consideration when selecting or engineering for desirable endophyte traits.     

Isolation of an Asm− mutant of Rhizobium japonicum defective in symbiotic N2-fixation

Abstract A mutant strain of Rhizobium japonicum (CJ9) unable to assimilate ammonium (Asm⁻) was isolated following mutagenesis with N -methyl N -nitro-nitrosoguanidine (NTG). Glutamate synthase activity was not detectable in cell-free extracts of the mutant strain in contrast to the wild type and revertant strains. Although mutant CJ9 induced nitrogenase activity in an 'in vitro' assay system under microaerobic conditions, it failed to fix nitrogen (acetylene reduction) in soybean root nodules. These properties of mutant CJ9 constitute a new Asm⁻ mutant class in Rhizobium spp.     

Schistosoma haematobium: experimental infection in capuchin monkey, Cebus apella

South American capuchin monkeys (Cebus apella) have been included in a series of nonhuman primates under evaluation for their potential use as models in a study of the basic biology of Schistosoma haematobium. Emphasis has been given to involvement of the urogenital system, a prominent feature of infection in man. Preliminary observations on Cebus apella with moderate numbers of S. haematobium from Iran showed that there may be serious involvement of the urogenital system with development of pronounced hydronephrosis accompanied by pathobiological alteration of the urinary bladder, ureters, and kidneys. There were heavy deposits of parasite eggs in the major viscera.