Insect UV-, and green-photoreceptor membranes studied by the freeze-fracture technique

Summary The membranes of the microvilli of UV- and green-photoreceptors of the ant Myrmecia gulosa have been studied with the freeze-fracture technique. Both inner fracture faces, the cytoplasmic P-face and the extracellular E-face, are covered by globular particles. The P-face particles appear to be randomly distributed, occasionally forming clusters. Their density is about 7,000/m², and their mean diameter is 8.5 nm. The E-face particles, however, are arranged in an ordered square pattern with a center-to-center spacing of 9 nm. The density and distribution of P- and E-face particles are the same in both the UV- and the green-photoreceptor membranes. No differences were found in the ultrastructural organization of photoreceptor membranes after dark or light adaptation. It is suggested that the P-face particles represent rhodopsin molecules.     

Comparison of species ordinations resulting from alternative indices of interspecific association and different numbers of included species

Summary Several measures of interspecific association are compared. Dispersion and covariance are limited in value because they respond to the commonness of the species compared. Correlation is not so limited but it responds to discrepancies in commonness among the species. The practical result of these relationships between commonness and association is that only the most common species can occupy periferal positions in a species ordination. Rare species are relegated to positions near the center not on the basis of their phytosociological pattern but simply because of their rarity. Both Cole's index of association and the tetrachoric correlation overcome the problem imposed by the relationship between ordination position and species commonness and they both produce very similar results. The effect of differing numbers of species on the ordination configuration is examined using both Pearson's correlation and Cole's index. The basic pattern of the ordination is set with the first few species when Cole's index is used, however, since rare species are given more weight in the analysis with this index, the addition of several very rare species can change the configuration of the ordination.Nomenclature of species is given in Table 1.Research supported by the Eastern Deciduous Forest Biome Project, US-IBP, funded by the National Science Foundation under Interagency Agreement AG-199, BMS69-01147 A09 with the Energy Research and Development Administration — Oak Ridge National Laboratory. Research also supported by the U.S. Energy Research and Development Administration under contract with the Union Carbide Corporation. Contribution No. 240 from the EDFB, US-IBP. Publication No. 790. Environmental Sciences Division, ORNL.     

Enhanced ozone exposure of European beech (Fagus sylvatica) stimulates nitrogen mobilization from leaf litter and nitrogen accumulation in the soil

Abstract

In a lysimeter study with young beech trees, the effects of elevated ozone concentration on the decomposition and fate of nitrogen in ¹⁵N‐labeled leaf litter were analyzed after one growing season. Nitrogen in the litter was dominated by a relatively inert, residual fraction, but easily decomposable nitrogen was present in substantial amounts. Nitrogen loss was significantly higher at twice‐ambient ozone which was largely attributed to an enhanced mobilization of residual nitrogen. Enhanced mobilization of nitrogen from litter at twice‐ambient ozone exposure resulted in additional ¹⁵N incorporation into the soil down to 30 cm depth. Only 0.41–0.62% of the nitrogen in the litter was incorporated into plant material at both ozone concentrations. Twice‐ambient ozone exposure changed the distribution of the nitrogen taken up from litter inside the beech trees in favor of the shoot, where it may have been used in biosynthetic processes required for defense reactions.     

Ionic liquid-enabled synthesis,cholinesterase inhibitory activity,and molecular docking study of highly functionalized tetrasubstituted pyrrolidines

A small library of novel spiropyrrolidine heterocyclic hybrids has been prepared regioselectively in 1-butyl-3-methylimidazoliumbromide ([bmim]Br) with good to excellent yields using a [3+2] cycloaddition reaction. These synthesized compounds were evaluated as potential agents for treating Alzheimer’s disease. Compound 4b showed the most potent activity, with an IC₅₀ of 7.9 ± 0.25 µM against acetylcholinesterase (AChE). The inhibition mechanisms for the most active compounds on AChE and butyrylcholinesterase (BChE) receptors were elucidated using molecular docking simulations.     

Low-Fat Diets May Prevent Weight Gain in Sedentary Women: Prospective Observations From the Population Study of Women in Gothenburg,Sweden

The Population Study of Women in Gothenburg, Sweden is an ongoing prospective study of female residents who were recruited from the local registry in 1968–1969 when they were 38–60 years old. The data presented here were collected from 361 healthy women who underwent a baseline physical examination including a supplementary dietary history interview and returned for a second general health examination 6 years later. This report identifies a subgroup of 57 women who were sedentary during their leisure time and appear to have been particularly susceptible to gaining weight as a function of the fat content of their diets. Specifically, longitudinal analysis of body weights in the whole sample revealed a statistical interaction between leisure-time physical activity and habitual dietary fat intake (energy-%), as reported at the baseline examination, in the prediction of subsequent weight change. Further stratified analysis suggested that weight changes were significantly dependent on dietary fat intake among the sedentary women only. High energy intake also predicted weight gain in the sedentary group, although the predictive value for a high-fat diet was of marginal significance after adjusting for total energy consumption. These results suggest that sedentary recreational activity plus a low-fat diet may have a combined contribution to weight change that is not equivalent to the sum of the separate effects. Such a synergy between two modifiable lifestyle factors seems highly relevant for prevention of obesity.     

Design,molecular docking and synthesis of novel 5,6-dichloro-2-methyl-1H-benzimidazole derivatives as potential urease enzyme inhibitors

A novel series of 5,6-dichloro-2-methyl-1H-benzimidazole derivatives was synthesized and then screened for their urease inhibitory activity. All compounds showed more potent inhibitory activity in the range of IC₅₀ = 0.0294 ± 0.0015–0.1494 ± 0.0041 µM than thiourea (IC₅₀ = 0.5117 ± 0.0159 µM), as a reference inhibitor. Among all the tested compounds, the compound 15 (IC₅₀ = 0.0294 ± 0.0015 µM) having strong electron-withdrawing nitro group on the phenyl ring was recorded as the most potent inhibitor of urease. All compounds were docked at the active sites of the Jack bean urease enzyme to investigate the reason of the inhibitory activity and the possible binding interactions of enzyme-ligand complexes.     

Biology and comparative predation efficacy of three heteropteran species recorded as predators ofBemisia tabaci in Maharashtra

Two mirids,Deraeocoris sp. andCampylomma nicolasi Reuter and one lygaeid,Geocoris ochropterus Fieber were found preying onB. tabaci (Gennadius) for the first time in Maharashtra State of India during 1987–88. Their biology and predation capacity onB. tabaci were studied in detail under laboratory conditions. The nymphal stage ofDeraeocoris sp. passed through 6 instars, whereas 5 instars in case of the remaining species.G. ochropterus, Deraeocoris sp. andC. nicolasi consumed on an average 482.5, 275.3 and 128.8 nymphs of 57.3, 25.5 and 20.6 days, respectively. On the basis of consumption rate per day,Deraeocoris sp. proved to be a superior predator. Part of Ph. D. Thesis submitted to Marathwada Agricultural University, Parbhani 431402, India.     

Methodological considerations with the use of urine samples for assessment of mercury excretion and markers of renal damage

Objective:?To provide recommendations for design and analysis of studies using urine specimens to evaluate renal function or mercury excretion in children.

Methods:?An analysis of mercury, albumin, γ-glutamyl transpeptidase (γ-GT) and N-acetyl-β-D-glucosaminidase (NAG) concentrations was carried out.

Results:?Mercury concentration and creatinine-corrected renal markers were higher in daytime compared with overnight samples. Excretion rates increased with urinary flow rate. γ-GT and NAG concentrations decreased with storage time at ?20°C. Differences by age, sex and race were noted.

Conclusions:?We recommend use of these creatinine-corrected markers and collection of timed overnight urine samples, stored at ?70°C, with control for urinary flow rate, age, sex and race in statistical models.     

Quantitative Analysis of the Sex Pheromone of Several Phycitid Moths by Electron-capture Gas Chromatography

β-Phenetyl alcohol and procaine hydrochloride are known to alter membrane structure. Their effects on the syntheses of tyramine oxidase and arylsulfatase were studied in Klebsiella aerogenes. β-Phenetyl alcohol inhibited the syntheses of membrane-bound tyramine oxidase and arylsulfatase, located in the periplasm, under non-repressing and derepressing conditions, but did not affect the syntheses of β-galactosidase and histidase, which are located internally. In contrast, procaine hydrochloride stimulated the synthesis of tyramine oxidase and derepressed the synthesis of arylsulfatase, but inhibited non-repressed synthesis of arylsulfatase. Thus, derepressed synthesis of cellular arylsulfatase was affected by the level of tyramine oxidase synthesis. Structural alterations in the cell membrane seem to impair the formation of active-arylsulfatase protein in the periplasmic space.