Breakdown of Ficus and Eucalyptus leaves in an organically polluted river in India: fungal diversity and ecological functions

1. At two organically polluted sites in the River Nethravathi, banyan and eucalypt leaves were colonized by one or two species of aquatic hyphomycetes. A total of three or four species were identified at the two sites in samples of water and naturally occurring leaves.
2. Spore production from stream‐exposed leaves by aquatic hyphomycetes was lower by a factor of up to 1 million compared with an earlier study in geographically close but unpolluted streams.
3. Exponential decay rates and loss rates of phosphorus and calcium, were not statistically different from an earlier study in unpolluted streams. Nitrogen increased during decomposition more slowly in the current study.
4. The microbial community on both leaves released enzymes active against starch, pectin, cellulose and xylan.
5. Banyan leaves conditioned for 12 weeks were more palatable to the gastropod Notopala sp. than unconditioned leaves.
6. Together with earlier data from unpolluted streams, the study provides evidence that organic pollution severely restricts diversity of aquatic hyphomycetes and their reproductive output, but does not have an equally strong effect on ecological functions generally associated with this group.     

Functional genomics by NMR spectroscopy. Phenylacetate catabolism in Escherichia coli.

Aerobic metabolism of phenylalanine in most bacteria proceeds via oxidation to phenylacetate. Surprisingly, the further metabolism of phenylacetate has not been elucidated, even in well studied bacteria such as Escherichia coli. The only committed step is the conversion of phenylacetate into phenylacetyl-CoA. The paa operon of E. coli encodes 14 polypeptides involved in the catabolism of phenylacetate. We have found that E. coli K12 mutants with a deletion of the paaF, paaG, paaH, paaJ or paaZ gene are unable to grow with phenylacetate as carbon source. Incubation of a paaG mutant with [U-13C8]phenylacetate yielded ring-1,2-dihydroxy-1,2-dihydrophenylacetyl lactone as shown by NMR spectroscopy. Incubation of the paaF and paaH mutants with phenylacetate yielded delta3-dehydroadipate and 3-hydroxyadipate, respectively. The origin of the carbon atoms of these C6 compounds from the aromatic ring was shown using [ring-13C6]phenylacetate. The paaG and paaZ mutants also converted phenylacetate into ortho-hydroxyphenylacetate, which was previously identified as a dead end product of phenylacetate catabolism. These data, in conjunction with protein sequence data, suggest a novel catabolic pathway via CoA thioesters. According to this, phenylacetyl-CoA is attacked by a ring-oxygenase/reductase (PaaABCDE proteins), generating a hydroxylated and reduced derivative of phenylacetyl-CoA, which is not re-oxidized to a dihydroxylated aromatic intermediate, as in other known aromatic pathways. Rather, it is proposed that this nonaromatic intermediate CoA ester is further metabolized in a complex reaction sequence comprising enoyl-CoA isomerization/hydration, nonoxygenolytic ring opening, and dehydrogenation catalyzed by the PaaG and PaaZ proteins. The subsequent beta-oxidation-type degradation of the resulting CoA dicarboxylate via beta-ketoadipyl-CoA to succinyl-CoA and acetyl-CoA appears to be catalyzed by the PaaJ, PaaF and PaaH proteins.     

Method of non-destructive mechanical testing of new surface coatings for prostheses]

Research into new surface coatings and surface processing methods for prostheses is subject to numerous studies. The aim of this study was to test an innovative biomechanical measuring method for the examination of the ingrowth of bone implants. Using a transcortical model, coated (n=14) or uncoated (n=14) titanic cylinders were implanted into the lateral condyle of 28 New Zealand White Rabbits. After 6 weeks or 6 months the animals were sacrificed and the osseointegration of the implants was evaluated biomechanically and histologically. Up to traction of 50 N the load dependent movement between bone and testing cylinder did not lead to a destruction of the bone-implant-interface. Therefore, biomechanical and histological investigations could be performed in the same specimen. The results of both evaluations showed a significant correlation (correlation coefficient -0.79; p < 0.01) and were absolutely reproducible. With the method of non-destructive mechanical testing, it is possible to halve the number of required animals. Additionally, the results of the biomechanical and histological analysis can be compared and thus serve as an internal control. In summary, the method of non-destructive mechanical testing represents an ideal tool to study new surface coatings and surface processing methods for prostheses.     

MITOCHONDRIAL DNA SEQUENCE VARIATION AMONG NATURAL POPULATIONS OF THE TRINIDAD GUPPY,POECILIA RETICULATA

Guppies were sampled from eight populations representing four river drainage basins in northern Trinidad, and from one population on the nearby island of Tobago. For each individual, a 465 base pair (bp) segment of the control region of the mitochondrial genome was sequenced. The resulting DNA sequences were subjected to sequence divergence calculations and the populations were linked by maximum parsimony analysis to determine their phylogenetic relationships. Mitochondrial DNA (mtDNA) sequence variation was found both within and between river drainages, correlated with the geographic features of northern Trinidad. The variation observed exists primarily between drainages, particularly between the Oropuche drainage and all other Trinidad drainages examined. Estimates of time of divergence between guppy populations of different drainages, based on mtDNA sequence variation, ranged from 100,000 to 200,000 for the most recently separated populations and from 600,000 to 1.2 million years between the Oropuche populations and all others examined. Examination of fish from northeastern South America will be required to determine whether these populations differentiated in their present locations or were the result of separate invasions of Trinidad from different Venezuelan sources. However, genetic isolation of these populations appears to predate the current physical separation of the island of Trinidad from the Venezuelan mainland.     

An isozyme study of clone diversity and relative importance of sexual and vegetative recruitment in the grass Brachypodium pinnatum

We asked whether differences in abundance and seed prodtiction of Brachypodium pinnatum after 16 yr of four different experimental land use regimes were reflected in differences in vegetative dispersal distance, clone diversity, clone area, and the proportions of sexual and vegetative recruitment. Mean vegetative dispersal distance was 5.5 mm yr'. Electrophoresis of 5 polymorphic isozyme loci of 20 tillers sampled at defined positions in each of twelve 1 × 6 m sampling areas (3 per treatment) revealed considerable clonal diversity. Per sampling area we found on average 9.98 enzyme phenotypes (clones), mean Simpson index was 0.825. and mean Shannon index 0.801. The mean ratio of sexual vs vegetative recruitment was about 1:32000. Despite this low ratio, clonal diversity within the population of" B. pinnatum was higher than reported for other clonal plant populations, possibly because of its high ramet densities. Moan clone area was 5.73 m²-. i.e. mean clone radius was 1.35 m. None of the 10 pairwise correlations between abundance and seed production on the one hand, and number of clones per plot sample, plot Simpson index, plot Shannon index, ratio of vegetative vs sexual recruitment, and clone area on the other, was significant. Mean clone radius was 245 times larger than the mean distance of yearly vegetative dispersal which suggests old ages and low turnover rates of clones. The time scale of the inert response of clonal diversity of B. pinnatum to changes in land use appears to largely exceed the experimental period of 16 yr.     

The Apparent Turnover of 1-Aminocyclopropane-1-Carboxylate Synthase in Tomato Cells Is Regulated by Protein Phosphorylation and Dephosphorylation

In suspension-cultured cells of tomato (Lycopersicon esculentum Mill.), the activity of 1-aminocyclopropane-1-carboxylate synthase (ACC-S) rapidly increases in response to fungal elicitors. The effect of inhibitors of protein kinases and protein phosphatases on the regulation of ACC-S was studied. K-252a, an inhibitor of protein kinases, prevented induction of the enzyme by elicitors and promoted its apparent turnover in elicitor-stimulated cells, causing a 50% loss of activity within 4 to 8 min in both the presence and absence of cycloheximide. Calyculin A, an inhibitor of protein phosphatases, caused a rapid increase of ACC-S in the absence of elicitors and an immediate acceleration of the rate of ACC-S increase in elicitor-stimulated cells. In the presence of cycloheximide there was no such increase, indicating that the effect depended on protein synthesis. Cordycepin, an inhibitor of mRNA synthesis, did not prevent the elicitor-induced increase in ACC-S activity but strongly reduced the K-252a-induced decay and the calyculin A-induced increase of its activity. In vitro, ACC-S activity was not affected by K-252a and calyculin A or by treatments with protein phosphatases. These results suggest that protein phosphorylation/dephosphorylation is involved in the regulation of ACC-S, not by regulating the catalytic activity itself but by controlling the rate of turnover of the enzyme.     

Immunoelectron microscopic localization of cytochrome P-450 isoenzyme CYP4A1 in liver,ileum and kidney of nafenopin treated male rats.

A monoclonal antibody raised against and specific for cytochrome P-450 isoenzyme CYP4A1 was used to investigate the subcellular distribution of this enzyme in the liver, kidney and ileum of nafenopin treated rats by means of immunoelectron microscopy. In the liver and kidney, labelling was restricted to peroxisomes and mitochondria of hepatocytes and proximal tubular epithelial cells whereas in ileum, immunolabelling was exclusively detected in mitochondria of absorptive cells.     

First documentation of golden jackal (Canis aureus) reproduction in Germany

Mammal Research - The golden jackal (Canis aureus), a mesocarnivore, is currently expanding from eastern towards western Europe. Reproduction of the species could be confirmed in several areas in...