Comparative Study of Erythrocyte Glycolytic Enzymes in Man and in Two Species of Lagomorphae

The authors made a comparative study of red cell enzyme glycolysis in man and in two species of Lagomorphae, the pika and the rabbit. The activities of the 12 enzymes of Embden-Meyerhoff pathway and of the two dehydrogenases of pentose shunt (glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase) were determined. Phosphoglycerate kinase and pyruvate kinase showed quite similar activities in pika erythrocytes and in erythrocytes from human umbilical cord. The levels of these enzymes differed significantly in the pika and in the rabbit. No differences were noted between pyruvate kinases from the rabbit and the neonatal man. The other activities gave values either identical to those found in the adult man or intermediate between the adult and the neonatal man. In the rabbit the levels of glycolitic enzymes were generally lower than in the pika except for lactate dehydrogenase and glycose-6-phosphate dehydrogenase. Some characteristics of erythrocyte metabolism specific to the pika may account for the differences observed in this species. The influence of red cell age cannot explain the variations observed for no significant reticulocytosis was observed in the circulating blood. The percentages found in the pika and the rabbit were essentially identical at determination.     

Diphenyl ether-chloroplast interactions

The diphenyl ethers acifluorfen (sodium-5-[2-chloro-4-(trifluoromethyl)-phenoxyl]-2-nitrobenzoate), acifluorfen-methyl (methyl-5-[2-chloro-4-(trifluoromethyl)-phenoxyl]-2-nitrobenzoate), and oxyfluorfen (2-chloro-1-[3-ethoxy-4-nitrophenoxy]-4-(trifluoromethyl)benzene have an absolute light requirement for herbicidal activity. CO₂-dependent O₂ evolution was inhibited in leaf disks obtained from 5-week-old spinach plants as a result of incubation in the light in the presence of each of the three diphenyl ethers. I₅₀'s were determined for inhibition by the diphenyl ethers of CO₂-dependent O₂ evolution in intact chloroplasts obtained from three species of varying susceptibilities (spinach, coffeeweed, and pea). Rankings obtained correlated well with relative susceptibilities and with relative effectiveness of the three compounds tested. Coupled and uncoupled photosynthetic electron transport in susceptible species were unaffected by the three compounds at concentrations in the I₅₀ range. Exposure to herbicidally inactive isomeric analogs of oxyfluorfen and acifluorfen did not affect photosynthesis in leaf disks but was effective in inhibiting photosynthesis in isolated chloroplasts. Photosynthetic abilities of intact tissue were not affected by herbicide treatment in red light. Red light was, however, as effective as white light in mediating the inhibition of photosynthesis in isolated intact chloroplasts by diphenyl ethers. The existence of two photoreceptors for diphenyl ether action, one located at the chloroplast envelope and a second outside of the chloroplast, is suggested as a possible basis for these findings.     

Weathering and morphogenesis in a tropical plateau

Weathering phenomena on the Campos do Jorda?o Plateau have been analysed in order to show their relationship to geomorphic compartition and morphogenetic dynamics.Correlations between weathering characteristics of surficial materials and geomorphic compartments are more conspicuous in saprolite than in soils.On the plateau highest areas gibbsite is the most important secondary mineral; at lower altitudes kaolinite prevails. Thus the spatial distribution of secondary minerals seems to out-line two weathering processes—alitization and monosialitization—defined and interpreted as two different stages within a general alitic weathering trend.On hillslopes, bedrock weathering degree reflects the intensity of morphogeneticactions. Hillslope deposit profiles frequently show degrees and sequences of weathering related to downslope mouvement processes rather than to incipient post-depositional pedogenetic activity.Red ferralitic materials overlaid by superficial podzolized ones point to the super-position of two pedogenetic trends linked to variations in environmental conditions.Ferralitic materials would be remnants of weathering processes active during the Tertiary at lower altitudes, prior to the plateau uplift.     

Extended summaries pesticides group symposium natural products as a source for new agricultural chemicals

The following are extended abstracts of six of the papers presented at the above meeting and, as so presented, they are entirely the responsibility of the authors and do not reflect the views of the Editorial Board of Pesticide Science.     

Detection of cyclodiene insecticide resistance-associated mutations by single-stranded conformational polymorphism analysis

Cyclodiene insecticide resistance is associated with replacements of a single amino acid within the putative lining of a δ-aminobutyric acid (GABA)-gated chloride ion channel gene Resistance to dieldrin (Rdl). Only two resistance-associated amino acid replacements have been identified; alanine to serine in Drosophila melanogaster, D. simulans, Aedes aegypti, and Tribolium castaneum and alanine to glycine as a second allele in D. simulans. Here we report that single stranded conformational polymorphism (SSCP) analysis of genomic DNA, amplified by the polymerase chain reaction (PCR) for exon 7 of the Rdl gene, can be used to genotype strains or individuals of all of these insects. This technique also appears simultaneously to distinguish between D. melanogaster and D. simulans, sibling species only reliably identifiable by examination of male genitalia. The relative advantages of this genotyping technique against other PCR-mediated techniques in monitoring for insecticide resistance are discussed.     

Factors associated with persistence of African animal trypanosomiasis in Lango subregion,northern Uganda

African animal trypanosomiasis (AAT) continues to inflict heavy losses on livestock production especially cattle in terms of decreased production and productivity in Uganda. AAT is a disease complex caused by tsetse fly-transmitted Trypanosoma brucei brucei, Trypanosoma brucei rhodesiense, Trypanosoma congolense, and Trypanosoma vivax. The disease is most important in cattle but also known to cause serious losses in pigs, camels, goats, and sheep. Several control measures including live bait technology, mass treatment of cattle with trypanocidal drugs, and deployment of tsetse traps have been used in the past 10 years, but the problem still persists in some areas. This necessitated an exploration of the factors associated with continued trypanosome infections in cattle, which are also known reservoirs for the zoonotic trypanosomiasis. A structured questionnaire was administered to 286 animal owners from 20 villages purposively selected from Lira, Kole, and Alebtong districts of Lango subregion to obtain information on the factors associated with persistence of infection. Over 50% of the respondents reported trypanosomiasis as a major challenge to their livestock. Land ownership (P = 0.029), type of livestock kept (P = 0.000), disease control strategy employed (P = 0.000), source of drugs (P = 0.046), and drug preparation (P = 0.017) were associated with persistent AAT infection. We recommend continued farmer sensitization on the threat of AAT and the available prevention and control options. The use of isometamidium chloride for prophylaxis against trypanosomiasis is highly recommended. There is also a need to foster qualified private veterinary drug supply in the region.