Nuclear magnetic resonance imaging of mummified corpses

Clinical applications of nuclear magnetic resonance (NMR) imaging have demonstrated its great potential for noninvasive examinations of soft tissues. Here preliminary experiments are reported on mummified human tissue by means of NMR cross-sectional and transmission imaging. For this purpose the natural viscosity of the tissues has been lowered by rehydration with an aqueous solution of 20% acetone.     

Solubilized DNA-dependent RNA polymerase from human placenta: A Mn(2+)-dependent enzyme

The 100-fold purified RNA polymerase activity from human placenta is completely dependent upon added DNA. The enzyme is most active at 3 mM Mn(2+) in the presence of 100 mM (NH(4))(2)SO(4). Denatured DNA is a better template than native DNA. alpha-Amanitin completely inhibits the incorporation of 3H-UMP, while rifampicin has no influence upon the enzymatic activity.     

A short-oligonucleotide microarray that allows improved detection of gastrointestinal tract microbial communities

Background  

The human gastrointestinal (GI) tract contains a diverse collection of bacteria, most of which are unculturable by conventional microbiological methods. Increasingly molecular profiling techniques are being employed to examine this complex microbial community. The purpose of this study was to develop a microarray technique based on 16S ribosomal gene sequences for rapidly monitoring the microbial population of the GI tract.     

Effects of a natural flood disturbance on species richness and beta diversity of stream benthic diatom communities

Natural hydrological disturbances in streams may reduce biomass and species richness and change community composition within streams. Disturbances can also affect beta diversity among streams if their effects are species specific or vary across sites. We investigated the effect of a natural flood on species richness, community composition and among-streams beta diversity of benthic diatoms (total community and three functional groups: low profile, high profile and motile) of seven streams in New Zealand. Sampling occurred shortly before, 10 days after and 40 days after the flood. Species richness of the total diatom community did not change after the flood. The high-profile group was the only one whose species richness declined after the flood, whereas species richness of the low-profile group increased. Community composition changed after the flood, mostly as a result of species replacement rather than richness differences over time. Finally, among-streams beta diversity did not change after the flood, suggesting that variation in species composition of benthic diatoms among streams may be maintained in the face of flood disturbances.     

Patchy bed disturbance and fish predation independently influence the distribution of stream invertebrates and algae

1. The identification of factors determining the patchy distribution of organisms in space and time is a central concern of ecology. Predation and abiotic disturbance are both well-known drivers of this patchiness, but their interplay is still poorly understood, especially for communities dominated by mobile organisms in frequently disturbed ecosystems. 2. We investigated the separate and interactive influences of bed disturbance by floods and predation by fish on the benthic community in a flood-prone stream. Electric fields excluded fish predators from half of 48 stream bed patches (area 0·49 m(2) ) with contrasting disturbance treatments. Three types of bed disturbance were created by either scouring or filling patches to a depth of 15-20 cm or by leaving the patches undisturbed, thus mimicking the mosaic of scour and fill caused by a moderate flood. Benthic invertebrates and algae were sampled repeatedly until 57 days after the disturbance. 3. Disturbance influenced all ten investigated biological response variables, whereas predation affected four variables. Averaged across time, invertebrate taxon richness and total abundance were highest in stable patches. Algal biomass and densities of five of the seven most common invertebrate taxa (most of which were highly mobile) were higher in fill than in scour patches, whereas two taxa were more abundant in scour and stable than in fill patches. Furthermore, two common invertebrate grazers were more abundant and algal biomass tended to be reduced in fish exclusion patches, suggesting a patch-scale trophic cascade from fish to algae. 4. Our results highlight the importance of patchy physical disturbance for the microdistribution of mobile stream organisms and indicate a notable, but less prevalent, influence of fish predation at the patch scale in this frequently disturbed environment. Disturbance and predation treatments interacted only once, suggesting that the observed predation effects were largely independent of local bed disturbance patterns.     

Protective effect of bixin on carbon tetrachloride-induced hepatotoxicity in rats

Background

The liver is an important organ for its ability to transform xenobiotics, making the liver tissue a prime target for toxic substances. The carotenoid bixin present in annatto is an antioxidant that can protect cells and tissues against the deleterious effects of free radicals. In this study, we evaluated the protective effect of bixin on liver damage induced by carbon tetrachloride (CCl₄) in rats.

Results

The animals were divided into four groups with six rats in each group. CCl₄ (0.125 mL kg^-1 body wt.) was injected intraperitoneally, and bixin (5.0 mg kg^-1 body wt.) was given by gavage 7 days before the CCl₄ injection. Bixin prevented the liver damage caused by CCl₄, as noted by the significant decrease in serum aminotransferases release. Bixin protected the liver against the oxidizing effects of CCl₄ by preventing a decrease in glutathione reductase activity and the levels of reduced glutathione and NADPH. The peroxidation of membrane lipids and histopathological damage of the liver was significantly prevented by bixin treatment.

Conclusion

Therefore, we can conclude that the protective effect of bixin against hepatotoxicity induced by CCl₄ is related to the antioxidant activity of the compound.