Immunological Difference between Glucose-6-P Dehydrogenase and Hexose-6-P Dehydrogenase from Human Liver

SHAW and Barto¹ have demonstrated the presence of an autosomally inherited glucose-6-P dehydrogenase (G6PD) in the deer mouse. Subsequently, Ohno et al.² found a similar enzyme in trout and showed that this enzyme and the autosomally inherited mouse enzyme differed from the sex-linked G6PD in possessing marked catalytic activity with galactose-6-P. This autosomally inherited G6PD was therefore named hexose-6-P dehydrogenase (H6PD)^2,3. It was shown to oxidize glucose-6-P, galactose-6-P, mannose-6-P and 2-deoxy glucose-6-P with a K_m of the order of 10^?5 M. It also oxidizes glucose with a K_m of 0.7 M³. It appears to be identical to the so-called “glucose dehydrogenase”. The enzyme utilizes both NAD and NADP and is microsome-bound. G6PD is localized in the soluble fraction of the cells of various tissues. Although it has been shown that two dehydrogenases from liver have different substrate specificity, molecular weight and elec-trophoretic mobility^3,4, it has been suggested that the two enzymes are merely isozymes and they might be interconvertible^5–7. We have now partially purified the two enzymes from human liver and show that they have different immunological properties.     

The Effect of Growth Temperature on Enzyme and Amino-acid Levels in Wheat Plants

Wheat plants were grown under constant conditions of light intensity,daylength, and humidity at controlled day temperatures of 5,10, and 20 °C. Selected plants were harvested at three stagesof growth for analysis of the levels of four enzymes (aspartateand alanine aminotransferases, glutamic dehydrogenase and glutamicdecarboxylase) and of free amino acids. The effect of growthtemperature on enzyme levels was most marked in the case ofglutamic decarboxylase, which showed highest activity in plantsgrown at 5°C. The concentrations of most free amino acidsalso were highest in plants grown at 5 °C, irrespectiveof the stage of plant development.     

Survival, development and life tables of two congeneric ladybirds in aphidophagous guilds

Two congeneric aphidophagous ladybirds, Coccinella septempunctata and Coccinella transversalis, were reared on three aphid species, Lipaphis erysimi, Myzus persicae and Aphis nerii, to estimate the effect of prey quality and intra- and interspecific interactions on their survival and development of life stages. Mortality of first instar ladybirds of both species was highest feeding on A. nerii. Preimaginal mortafity was lowest when feeding on L. erysimi （C. septempunctata, 1.6% and C. transversalis, 3.2%）, and highest when feeding on A. nerii （ C. septempunctata, 6.2% and C. transversalis, 8.2%）. Comparatively higher weight and larger size of C. septempunctata along with the lower levels of mortality recorded suggested that it is more likely to have acted as an intraguild predator than C. transversalis. High recorded mortality of C. transversalis is attributed to probable intraguild predation on account of its smaller size. The major sources of mortality were probably cannibalism, intraguild predation and other unknown factors. Lower prey quality increased the incidence of cannibalism and intraguild predation, especially in C. transversalis. The investigation suggests an intrinsic competitive advantage for C. septempunctata over C. transversalis in guilds of three aphid species.     

Larvicidal efficacy of Aloe barbadensis and Cannabis sativa against the malaria vector Anopheles stephensi (Diptera: Culicidae)

Anopheles stephensi is the primary vector of malaria, an endemic disease in India. An effort to control An. stephensi larvae by leaf extracts of Aloe barbadensis (Liliaceae) and Cannabis sativa (Moraceae) was made under laboratory conditions. A carbon tetrachloride extract of A. barbadensis was the most effective of all the extracts tested for larvicidal activity against the anopheline larvae, with LC₅₀ 15.58 and 8.04 p.p.m. after 24 and 48 h of exposure, respectively. Thus, the leaf extract of A. barbadensis has active components that could be useful as a larvicide of ecocongenial nature against malaria vectors.     

Evaluation of larvicidal potential of certain insect pathogenic fungi extracts against Anopheles stephensi and Culex quinquefasciatus

Fungal metabolites are attracting attention as potential microbial insecticides, and they are anticipated to overcome the problems of pesticide resistance and environmental pollution that are associated with the indiscriminate use of conventional synthetic insecticides. The relative bioefficacies of selected fungal pathogens, Aspergillus flavus, A. niger, A. parasiticus, Fusarium sporotrichoides and Penicillium verrucosum were observed against Anopheles stephensi and Culex quinquefasciatus larvae. A. flavus demonstrated the greatest bioefficacy with 50% lethal concentration (LC₅₀) values of 9.54 and 10.98 ppm against Anopheles stephensi and Culex quinquefasciatus larvae, respectively, after 24‐h exposure. The bioefficacy of A. flavus increased in both species with an exposure time of 48 h, with LC₅₀ values of 7.26 and 8.55 ppm, respectively.     

Studies on the Resistance of Carrot Roots to Pythium aphanidermatum (Eds.) Fitz.

Carrot roots were found to be resistant to Pythium aphanidermatumbut not to Rkizopus stolonifer. Such factors as temperatureof incubation for the inoculated hosts and pH of the host tissuedid not provide any clue to the resistance of carrot to theformer pathogen. Tests for a preformed inhibitor of pectic enzymesof the fungus in carrot, or formation of such a substance asa result of host-fungus interaction, gave negative results.The resistance was attributed to the presence of a phenoliccompound in carrot, which inhibited the growth of the former,but not of the latter. When the factor for resistance was appliedin the susceptible hosts at the site of inoculation with thefungus, the hosts showed resistance.     

Guard cell zeaxanthin tracks photosynthetically active radiation and stomatal apertures in Vicia faba leaves*

Zeaxanthin, antheraxanthin and violaxanthin concentrations in guard cells from sonicated abaxial epidermal peels of Vicia faba were measured from dawn to dusk, and compared with concentrations in mesophyll tissue of the same leaves. Measured changes in guard cell zeaxanthin and violaxanthin concentrations indicate that guard cells operate the xanthophyll cycle throughout the day. Mesophyll tissue had no detectable zeaxanthin at dawn, whereas guard cells had 30–50 mmol mol^?1 chlorophyll a+b. On a chlorophyll basis, maximal zeaxanthin levels were 3–4 fold higher in guard cells than in mesophyll cells. Zeaxanthin concentrations tracked levels of photosynthetically active radiation (PAR) in both mesophyll and guard cells. In the mesophyll, most of the zeaxanthin changes occurred in mid-morning and mid-afternoon. In guard cells, zeaxanthin concentrations changed nearly linearly with PAR in the early morning and late afternoon, and closely tracked PAR levels throughout the day. Guard cell zeaxanthin concentrations were also closely correlated with stomatal apertures. The close relationship between zeaxanthin concentrations and PAR levels in guard cells indicates that zeaxanthin is well suited to function as a molecular photosensor in stomatal movements.     

Lipophosphoglycan Is Present in Distinctly Different Form in Different Entamoeba histolytica Strains and Absent in Entamoeba moshkovskii and Entamoeba invadens1

ABSTRACT. Lipophosphoglycan has recently been demonstrated on the cell surface of Entamoeba histolytica strain HM-1:IMSS. A monoclonal antibody against this molecule had failed to react with some other strains of E. histolytica, including the strain Rahman. To determine if a structurally distinct lipophosphoglycan existed in Rahman, [³H]galactose-labeled glycoconjugates were electrophoresed through sodium dodecyl sulfate polyacrylamide gel electrophoresis. The electrophoretic pattern in Rahman was very different compared to that obtained with strains HM-1:IMSS and 200:NIH. A number of experiments including sensitivity to mild acid, nitrous acid and phosphoinositol-specific phospholipase C suggest that the Rahman glycoconjugate is indeed a lipophosphogylcan-like molecule but distinctly different from that of HM-1:IMSS. Mild acid-treated glycoconjugates from Rahman and HM-1:IMSS revealed the presence of neutral trisaccharides and monosaccharides in Rahman but not in HM-1:IMSS. Human immune sera from amoebiasis patients and a polyclonal antibody against HM-1:IMSS liphophosphoglycan both recognized Rahman glycoconjugate. Thus, while lipophosphoglycan molecules from the two strains share common epitopes, they are clearly distinct from each other. Molecules bearing resemblance to lipophosphoglycan could not be detected in other Entamoeba species, namely Entamoeba invadens and Entamoeba moshkovskii.