Limited Tryptic Proteolysis of the Benzodiazepine Binding Proteins in Different Species Reveals Structural Homologies

Peptide mapping can be used to elucidate further the structural similarities of the benzodiazepine binding proteins in different vertebrate species. Crude synaptic membrane preparations were photoaffinity-labeled with [3H]flunitrazepam and subsequently degraded with various concentrations of trypsin. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by fluorography allowed a comparison of the molecular weights of photolabeled peptides in different species. Tryptic degradation led to a common peptide of 40K in all species investigated, a finding indicating that the benzodiazepine binding proteins are structurally homologous in higher bony fishes and tetrapods.     

Phenolic and mineral content of leaves influences decomposition in European forest ecosystems

Summary Factors influencing decomposition in European forests growing on different soils were studied in stands dominated by the European beechFagus sylvatica L. Phenolic contents of freshly fallen leaves ofF. sylvatica growing on nutrient-poor soils (acid sandy soil) were higher than those of similar leaves on nutrient-rich soils (calcareous mull soil). Analysis of fallen leaves of different ages showed rapid decay of phenolics during the first winter on the ground. After 1 year the phenolic content of leaves ofF. sylvatica growing on nutrient-poor soils was still twice as high as in similar leaves on nutrient-rich soils. Field and laboratory experiments showed that a major decomposer (Oniscus asellus, Isopoda) preferred leaves from trees on nutrient-rich soils. Mineral contents of leaves ofF. sylvatica growing on different soils differed: on rich soils leaves had higher contents of Ca, Mg, Na, and K. These elements are important nutrients for decomposers. The distribution of major decomposers reflects the mineral content of their diet, which in turn reflects soil type. Different rates of leaf turnover and nutrient turnover in different forest ecosystems (even when the same tree species is dominant) are due to the decomposing system, which is influenced by the phenolic and mineral contents of the leaves.     

A function describing all-sized trunk diameter distribution in warm-temperate rain forests

A simple relation (v-lnB) (u-lnx)=c was recognized betweenx as dbh (or individual basal area) andB as the cumulative basal area abovex, for various stands of warm-temperate rain forests of Yakushima Island, southern Japan (v, u andc, parameters). The model parameters explained a difference in the pattern of stand development between secondary succession after clear-felling and gap regeneration within primary forests.     

我国浙江与日本和我国台湾森林植物区系的联系

作者在“试论浙江省森林植物区系”一文中对我国浙江与日本和我国台湾森林植物区系的联系已作了扼要的说明,本文就是在此基础上作更详尽的论述。浙江省东濒大海,隔海相望,东北方向有日本,其本部岛屿的南端为九州,和浙江北部的纬度相近,具有亚热带气候特征,出现了和浙江相类似的常绿阔叶林和竹林,九     

Tree species regeneration in a mid-elevation,temperate rain forest in Isla de Chiloé, Chile

The regeneration of canopy and subeanopy species in a mid-elevation, primary rain forest in the Coastal Range of Isla de Chiloé (42°30S), in the cold-temperate region of Chile, was studied by comparing seedling and sapling abundances under the forest canopy, and within 36 tree-fall gaps. The forest was dominated byAmomyrtus luma andLaurelia philippiana (33 and 32% of the main canopy individuals), and two subcanopy species (Myrceugenia ovata, andMyrceugenia planipes) were also important. Uncommon species in the canopy wereDrimys winteri, Amomyrtus meli, andRaphithamnus spinosus. Tree-fall gaps were created generally by the fall of several trees, and the main canopy species were the principal gap-makers. Gap sizes varied between 28 and 972 m², with a mean of 197 m². Seedling and sapling abundances indicate that the dominant species are capable of regenerating below the canopy, but they also germinate and show enhanced growth within small light gaps. For one of the common subcanopy species (M. planipes) and the two infrequent canopy species (D. winteri, andA. meli) regeneration seems to depend entirely on tree-fall gaps. Thus, in this forest, light gaps allow the persistence of infrequent canopy species, but seem less important for the regeneration and maintenance of dominant canopy species.     

The structure and phenology of a moist deciduous forest in the Central Indian Highlands

The vegetation structure and phenology of a 74.5 ha block of moist deeiduous forest in Kanha Tiger Reserve, Madhya Pradesh, India were investigated during primatological fieldwork. Within a grid of 0.25 ha quadrats all 9935 trees (woody plants > 2 m tall), of 63 species, were enumerated and their girth measured. The forest was dominated by the dipterocarp sal (Shorea robusta). Most species were rare and showed clumped distributions within the sea of sal whilst the dispersion of five large canopy trees could not be distinguished from random.The phenology of 215 trees, of 61 species, was monitored over 14 months using an index of phytophase abundance. Leaf renewal was highly synchronous between and within species, mostly occurring between February and June. One species was evergreen, 5 were semi-evergreen and 55 were deciduous. Flowering generally occurred between leaf fall and flush whilst fruiting peaked late in the hot weather and early monsoon.     

A new null hypothesis for measuring the degree of plant community organization

An attempt is made to derive a measure for the degree of plant community organization, which would not be based on species co-occurrence and co-abundance. The use of the independent random distribution hypothesis (IRDH) is suggested for this purpose. The hypothesis is expected to be valid, if no deterministic phytosociological-structure-generating mechanism is present. If structural variability is used as a statistic for testing the hypothesis, deviances from the conditions of IRDH (species distributions are independent from each other, environmental gradients are lacking) will be attributable either to species interactions (smaller structural variability than expected), or to environmental heterogeneity (greater structural variability than expected). Structural variability is evaluated as the variance of species diversity, the indexN=exp(H') is used for measuring diversity. The precise measure of the degree of community organizationW is computed as the shift between two empirical distributions:D ^* (VN) or Bootstrap distribution of variance of diversity in the community, andD ^o (VN) or the random community variability distribution, which is evaluated after simulating the IRDH conditions.A satisfactory interpretation can be given to the results of evaluatingW for 11 data sets of 10 relevés each.Abbreviation IRDH Independent random distribution hypothesis     

Conversion of cyanide to formate and ammonia by a pseudomonad obtained from industrial wastewater

Summary A cyanide-degrading pseudomonad was isolated by selective enrichment in a chemostat inoculated with coke-plant activated sludge and maintained at a dilution rate of 0.042/h for 60 days with a feed of 10 mg/l cyanide. The isolate, a facultative methylotroph capable of growth on methanol and methylamine, degraded cyanide to formate and ammonia; it could utilize the released ammonia as a nitrogen source but did not further metabolize formate under the experimental conditions employed. Both cyanide-degrading enzyme activity and respiratory resistance to cyanide were inducible and were enhanced by repeated exposure to the compound. Cell-free extracts stoichiometrically converted cyanide to formate and ammonia in a reaction that did not require oxygen. Enzyme activity, lost upon dialysis, was restored by less than equimolar ratios of NAD(P)H or ascorbate to cyanide, indicating that the reductants did not function directly as co-enzymes.