Uptake hydrogenase in Rhizobium and nodule leghemoglobin in cow pea miscellany hosts

Two effective strains of green gram rhizobia S24 (slow growing and Hup⁺) and M11 (fast growing and Hup^-) were tested for leghemoglobin production in nodules and effectivity on six species of cow pea miscellany hosts. Both strains nodulate green gram [Vigna radiata (L.) (Wilczek)], black gram [Vigna mungo (L.) (Hepper)], cow pea [Vigna unguiqulata (L.)], moth bean [Vigna aconitifolia (Jacq.) (Marechel)], Cluster bean [Cyamopsis tetragonoloba (L.) (Taub.)] and pigeon pea [Cajanus cajan (L.)]. In all these hosts, nodules formed by strain M11 contained 1.5 to 2 times more leghemoglobin than the nodules formed by strain S24. Gel electrophoresis of nodule contents of different host species showed a high concentration of a fast-moving ferricoxy leghemoglobin in the nodules of plants inoculated with strain M11 as compared to that of strain S24. Strain M11, however, was relatively less effective than strain S24 on black gram, cow pea and moth bean and was at par with the later on green gram, cluster bean and pigeon pea. Hydrogen recycling ability of the strain S24 was observed in nodules of all the host species. The effective functioning of strain S24 at low levels of leghemoglobin suggests an involvement of recycling hydrogenase in maintaining an appropriate oxidation-reduction potential in nodules.Abbreviations Lb Leghemoglobin - Cvr cultivar     

Nitrogen fixation and nitrate utilization by marine and freshwater Beggiatoa

Four newly isolated marine strains of Beggiatoa and five freshwater strains were tested for nitrogen fixation in slush agar medium. All strains reduced acetylene when grown microaerobically in media containing a reduced sulfur source and lacking added combined nitrogen. The addition of 2 mmol N, as nitrate or ammonium salts, completely inhibited this reduction. Although not optimized for temperature or cell density, acetylene reduction rates ranged from 3.2 to 12 nmol·mg prot^-1 min^-1. Two freshwater strains did not grow well or reduce acetylene in medium lacking combined nitrogen if sulfide was replaced by thiosulfate. Two other strains grew well in liquid media lacking both combined nitrogen and reduced sulfur compounds but only under lowered concentrations of air. All freshwater strains grew well in medium containing nitrate as the combined nitrogen source. Since they did not reduce acetylene under these conditions, we infer that they can assimilate nitrate.     

Trichomonas vaginalis: Dependence of resistance among different mouse strains upon the non-H-2 gene haplotype,sex, and age of recipient hosts

The genetic control of resistance or susceptibility to Trichomonas vaginalis infection has been studied in mice of various strains infected by different routes. $\text{BALB}\text{c}$ and $\text{DBA}\text{2}$ female mice appear to be highly susceptible to intraperitoneal, subcutaneous, or intravaginal infection by T. vaginalis. By contrast, female mice on A background are resistant to T. vaginalis infection via any route. $\text{C}\text{57}\text{BL}\text{6}$ and C3H female mice display intermediate levels of resistance following intraperitoneal or subcutaneous inoculum, whereas they display high levels of resistance to intravaginal infection. On the other hand, susceptibility or resistance to T. vaginalis infection appears to be influenced by the host sex, since males inoculated subcutaneously display much higher levels of resistance than females of the same strain. Lastly, the age of the host seems to play an important role in determining the course of infection. Susceptibility to T. vaginalis decreases with age, being maximal at 3–4 weeks and minimal at 40–42 weeks. All together these results suggest that resistance or susceptibility to T. vaginalis infection is regulated by genes mapping outside the major histocompatibility complex (H-2 in the mouse), whose activity is modulated by the anatomic site first coming into contact with the protozoon, the sex, and the age of the recipient host.     

Trypanosoma cruzi: In vivo and in vitro correlation between T-cell activation and susceptibility in inbred strains of mice

The in vivo susceptibility of several inbred strains of mice to the Y and CL strains of Trypanosoma cruzi was compared to the in vitro ability of spleen cells from infected mice to generate factor(s) able to activate macrophages to a trypanocidal state. Spleen cells from resistant immune mice generate higher levels of the factor(s) and do so at earlier times during infection than those of susceptible mice. The spleen cells capable of generating the in vitro factor(s) are also capable of conferring resistance upon passive transfer. Removal of immunoglobulin-bearing cells from the immune spleen cell population did not affect either transfer of protection in vivo or generation of the factor(s) in vitro. The cellular basis underlying the differences between susceptible and resistant mouse strains has not yet been determined.     

Morphometric parameters of the midgut cells of Aedes aegypti L. (Insecta,Diptera) under various conditions

Summary Previous morphometric or biochemical investigations have yielded different data on the distribution of free and membrane-bound ribosomes in midgut cells of Aedes aegypti. In the present paper ribosomal distribution has been morphometrically analysed to determine whether different mosquito strains, different food and different narcosis used in these previous studies, and/or methodological errors, could account for the different results.Most of the cellular parameters in the stomach epithelium of female A. aegypti, strain Rockefeller, and their changes during blood digestion, are comparable to those measured for another Aedes strain (Segemaganga, Hecker and Rudin 1979), and are generally similar to those of Anopheles stephensi (Hecker 1978). Proteolytic activity against casein is similar for both Aedes strains with a maximum activity being registered around 30 h after a blood meal. During digestion of human serum there is no increase in the ratio of membranebound to free ribosomes, and no significant increase in the surface area of the rough endoplasmic reticulum or of the number of bound or free ribosomes. Proteolytic activity is distinctly lower than during blood digestion. Immobilization of mosquitoes prior to dissection by ether narcosis or by shaking in a test tube has no significant influence on cellular parameters in females fed on sugar solution and investigated 3days after emergence.It is concluded that the differences in ribosomal parameters previously obtained by morphometrical (Hecker and Rudin 1979) and biochemical (Gander et al. 1980) methods, can only partly be explained by the selection of different food for the mosquitoes, and must also have been caused by methodological inadequacies.

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Zusammenfassung Frühere morphometrische und biochemische Untersuchungen erbrachten teilweise unterschiedliche Resultate betreffend Verteilung freier und membrangebundener Ribosomen in Mitteldarmzellen von Aedes aegypti. In der vorliegenden Arbeit wurde morphometrisch untersucht, ob diese Unterschiede bedingt waren durch die Verwendung verschiedener Mückenstämme, unterschiedlichen Futters und verschiedener Narkosemethoden durch die beiden Arbeitsgruppen, oder ob methodische Einflüsse dafür verantwortlich waren.Die meisten Zellparameter im Magenepithel von A. aegypti, Stamm Rockefeller, wie auch ihre Änderungen während der Verdauung eines Blutmahls, entsprachen den für einen andern Aedes-Stamm (Segemaganga, Hecker und Rudin 1979) gemessenen Werten und stimmten im allgemeinen mit denjenigen für Anopheles stephensi (Hecker 1978) überein. Die proteolytische Aktivität gegen Casein war bei beiden Stämmen gleich mit einem Aktivitäts-Maximum um 30h nach Blutmahl. Bei der Verdauung von menschlichem Serum konnte keine Zunahme des Verhältnisses von membrangebundenen zu freien Ribosomen, keine signifikante Oberflächenvergrößerung des rauhen endoplasmatischen Retikulums und keine signifikante Erhöhung der Zahl gebundener und freier Ribosomen gemessen werden. Die Proteaseaktivität war deutlich schwächer als während der Verdauung von Blut. Betäubung der Mücken vor der Sektion mit Aether oder durch Schütteln in Reagenzgläsern ergab im Vergleich keinen signifikanten Einfluß auf die Zellparameter von Zuckerwasser-gefütterten Weibchen, die drei Tage nach dem Schlüpfen untersucht wurden.Unterschiede in den Ribosomenparametern, die mit morphometrischen Methoden (Hecker und Rudin 1979) einerseits und biochemischen (Gander et al. 1980) andererseits untersucht wurden, konnten nur teilweise durch die Wahl unterschiedlichen Futters für die Mücken durch die beiden Arbeitsgruppen erklärt werden. Es müssen zusätzlich methodische Einflüsse für diese Unterschiede verantwortlich sein.

     

Trypanosoma cruzi: Lactate dehydrogenase isoenzymes and infections in mice

Total plasma LDH isoenzyme (EC 1.1.1.27) levels increased significantly over the normal level in mice infected with strains of Trypanosoma cruzi from three different geographic locations, but some strain differences were observed. The most rapid increase was exhibited by the blood-induced Tulahuen strain, but this strain, unlike the House 510 or House 11, did not elicit an increase during the early period of infection. Overall increases in LDH-1 and LDH-2, heart isoenzymes, were most marked in vector-derived House 510 infections, but, as in the Tulahuen strain, a considerable increase was also observed in blood-induced infections. The House 510 strain also elicited significant increases in LDH-4; these were particularly high during the early period of the blood-induced infection. By contrast, the vector-derived Tulahuen strain elicited a higher increase in LDH-4 during the early period than the House 510 or House 11 strains. Comparable similarites and differences were also observed in regard to LDH-3, 5, and “X.” The most marked isoenzyme increases were those of “LDH-X” exhibited by the blood-induced House 510 and vector-derived Tulahuen strains.Parallel histopathologic studies of liver, heart, and skeletal muscle disclosed significant pathology in all the infections. Animals with blood-induced Tulahuen strain infections characteristically showed extensive necrosis with marked multiplication of parasites throughout the liver, but little or no evident damage to the heart and skeleal muscle. Animals infected with House 510 and House 11 strains exhibited minimal pathology in the liver but severe damage to the heart and skeletal muscle. Increases in LDH-4 and LDH-5, isoenzymes which represent both liver and skeletal muscle, in blood-induced Tulahuen infections were attributed largely to liver damage, but in the House 510 and House 11 infections were related more to skeletal muscle.     

Schistosoma japonicum: Infection characteristics in mice of various strains and a difference in the response to eggs

Female mice of 12 inbred strains were exposed to 20–25 cercariae of Schistosoma japonicum and infection status determined at day 40 by counting numbers of adult worms, eggs in faeces and eggs in a segment of liver. Most mouse strains appeared to be ‘permissive’ hosts although at least one strain (129/J) was shown to be relatively resistant in terms of day 40 adult worm numbers. In a radioisotopic lung assay for sensitivity to eggs, and developed as a rapid means of assessing granuloma formation, CBA/H mice were shown to differ from C57BL/6 mice in being non-responders. Histological examination of lungs of sensitized CBA/H and C57BL/6 mice injected intravenously with eggs established that granuloma formation was much more intense in C57BL/6 than CBA/H mice. Preliminary indications are that infected CBA/H mice are also low anti egg circumoval precipitin (COP) responders. Analysis of immune responses to isolated egg antigens in these two strains, and identification of the antigens of eggs to which such responses are directed in C57BL/6 mice, should provide insights into immunological disease processes (such as granulomatous inflammation) in this model system of japonicum schistosomiasis.     

Dipetalonema viteae: Microfilariae production in various mouse strains and in nude mice

Adult female Dipetalonema viteae worms obtained from hamsters were introduced beneath the dorsal skin of $\text{Balb}\text{c}$, $\text{C}{}_{57}\text{Bl}\text{6}$, and $\text{C}{}_3\text{H}\text{He}$ mice. The microfilaraemia from the transplanted worms in $\text{Balb}\text{c}$ mice was higher and persisted longer than in $\text{C}{}_{57}\text{Bl}\text{6}$, and in $\text{C}{}_3\text{H}\text{He}$ mice was intermediate between these two strains. The transplanted adult worms were killed earlier in $\text{C}{}_{57}\text{Bl}\text{6}$ compared to $\text{Balb}\text{c}$ mice; adult worms were killed before the microfilariae were cleared from the circulation. D. viteae infective larvae did not reach maturity in mice but when female worms were implanted into mice which had been infected with third-stage infective larvae 6 or 19 days previously, microfilarial production was inhibited. Outbred as well as inbred nude mice infected with 10 or 20 infective larvae died by Day 15, whereas the normal littermate control mice that received the same number of infective larvae remained alive and healthy. There was no difference in the duration and level of microfilaraemia from implanted female worms in outbred nudes and their heterozygous littermate control mice. In contrast, microfilaraemia in inbred $\text{Balb}\text{c}$ Nu+ was similar to that of inbred $\text{Balb}\text{c}\text{Nu}\text{Nu}$ only until Day 45; thereafter the microfilaraemia declined to zero around Day 160 in the Nu+, at which time it was still high and persisted longer in the $\text{Balb}\text{c}\text{Nu}\text{Nu}$. Transplanted adults were viable in inbred $\text{Balb}\text{c}\text{Nu}\text{Nu}$ for a longer time than in $\text{Balb}\text{c}$ Nu+. When infected, amicrofilaraemic nudes, littermate controls, and three strains of mice were challenged, a very low level short-lasting microfilaraemia resulted.     

Chromosome replacement in mixed populations of compound-2L; free-2R and standard strains of Drosophila melanogaster

Summary Crosses between compound-2L; free-2R (free-arm) and standard strains of Drosophila melanogaster produce two classes of inviable aneuploid hybrids in equal proportions: monosomic 2L and trisomic 2L. The lethal period for monosomics occurs during embryogenesis while the trisomics survive to late pupae. Since the hybrids are inviable, standard and free-arm strains within a mixed population remain genetically isolated. Genetic isolation in the absence of mating isolation offers an extreme example of unstable equilibrium. Relative fitness data indicate that an unstable equilibrium will be established between free-arm and standard strains at a ratio of 2.51. Indeed, in three cage experiments established at initial ratios of 31, free arms to standards, laboratory (Oregon R) or native (Okanagan S) standard strains were completely replaced in approximately 100 days by free-arm lines derived either from laboratory or from native genetic background. In contrast, one cage established at an initial ratio of 41 failed to show replacement and for 92 days remained at approximately the initial ratio. Subsequent genetic analysis of flies removed from this cage identified the presence of an anomalous strain through which genetic information was transferred reciprocally between the free-arm and standard lines. The second chromosomes carried by this strain consisted of a free-2R and a standard second on the right arm of which was attached a duplication for all of 2L. While the origin of the 2L·2R+2L chromosome was uncertain, genetic and cytological examinations revealed that it represented the reciprocal crossover product expected from an exchange that generated a F(2R). Additional crosses disclosed that the transmission frequency of the asymmetrical pair of second chromosomes, as well as their right-arm crossover products, was disproportionately in favor of the short arm. Since unequal transmission was invariably greater from female parents, this phenomenon was viewed as further evidence in support of the drag hypothesis.Supported by research grant A5853 from the National Science and Engineering Research council of Canada to D.G.H.