Chromium is not an essential trace element for mammals: effects of a “low-chromium�?diet

Chromium was proposed to be an essential trace element over 50?years ago and has been accepted as an essential element for over 30?years. However, the studies on which chromium’s status are based are methodologically flawed. Whether chromium is an essential element has been examined for the first time in carefully controlled metal-free conditions using a series of purified diets containing various chromium contents. Male Zucker lean rats were housed in specially designed metal-free cages for 6?months and fed the AIN-93G diet with no added chromium in the mineral mix component of the diet, the standard AIN-93G diet, the standard AIN-93G diet supplemented with 200?μg?Cr/kg, or the standard AIN-93G diet supplemented with 1,000?μg?Cr/kg. The chromium content of the diet had no effect on body mass or food intake. Similarly, the chromium content of the diet had no effect on glucose levels in glucose tolerance or insulin tolerance tests. However, a distinct trend toward lower insulin levels under the curve after a glucose challenge was observed with increasing chromium content in the diet; rats on the supplemented AIN-93G diets had significantly lower areas (P?<?0.05) than rats on the low-chromium diet. The studies reveal that a diet with as little chromium as reasonably possible had no effect on body composition, glucose metabolism, or insulin sensitivity compared with a chromium-“sufficient??diet. Together with the results of other recent studies, these results clearly indicate that chromium can no longer be considered an essential element.     

Catalytic antibodies from HIV-infected patients specifically hydrolyzing viral integrase suppress the enzyme catalytic activities

Human immunodeficiency virus type 1 integrase (IN) catalyzes integration of a DNA copy of the viral genome into the host genome. It was shown previously that IN preincubation with various oligodeoxynucleotides (ODNs) induces formation of dimers and oligomers of different gyration radii; only specific ODNs stimulate the formation of catalytically active dimers. Here we have shown that preincubation of IN with specific and nonspecific ODNs leads to a significant and comparable decrease in its hydrolysis by chymotrypsin, while nonspecific ODNs protect the enzyme from the hydrolysis by trypsin worse than specific ODNs; all ODNs had little effect on the IN hydrolysis by proteinase K. In contrast to canonical proteweases, IgGs from HIV‐infected patients specifically hydrolyze only IN. While d(pT)_n markedly decreased the IgG‐dependent hydrolysis of IN, d(pA)_n and d(pA)_n?d(pT)_n demonstrated no detectable protective effect. The best protection from the hydrolysis by IgGs was observed for specific single‐ and especially double‐stranded ODNs. Although IN was considerably protected by specific ODNs, proteolytic IgGs and IgMs significantly suppressed both 3′‐processing and integration reaction catalyzed by IN. Since anti‐IN IgGs and IgMs can efficiently hydrolyze IN, a positive role of abzymes in counteracting the infection cannot be excluded. Copyright © 2011 John Wiley & Sons, Ltd.     

CYP17 inhibitors for prostate cancer therapy

Prostate cancer (PC) is now the second most prevalent cause of death in men in the USA and Europe. At present, the major treatment options include surgical or medical castration. These strategies cause ablation of the production of testosterone (T), dihydrotestosterone (DHT) and related androgens by the testes. However, because these procedures do not affect adrenal, prostate and other tissues' androgen production, they are often combined with androgen receptor antagonists to block their action. Indeed, recent studies have unequivocally established that in castration-resistant prostate cancer (CRPC) many androgen-regulated genes become re-expressed and tissue androgen levels increase despite low serum levels. Clearly, inhibition of the key enzyme which catalyzes the biosynthesis of androgens from pregnane precursors, 17α-hydroxy/17,20-lyase (hereafter referred to as CYP17) could prevent androgen production from all sources. Thus, total ablation of androgen production by potent CYP17 inhibitors may provide effective treatment of prostate cancer patients. This review highlights the role of androgen biosynthesis in the progression of prostate cancer and the impact of CYP17 inhibitors, such as ketoconazole, abiraterone acetate, VN/124-1 (TOK-001) and TAK-700 in the clinic and in clinical development. Article from the special issue on Targeted Inhibitors.     

Additive inheritance of histone modifications in Arabidopsis thaliana intra-specific hybrids

Plant genomes are earmarked with defined patterns of chromatin marks. Little is known about the stability of these epigenomes when related, but distinct genomes are brought together by intra‐species hybridization. Arabidopsis thaliana accessions and their reciprocal hybrids were used as a model system to investigate the dynamics of histone modification patterns. The genome‐wide distribution of histone modifications H3K4me2 and H3K27me3 in the inbred parental accessions Col‐0, C24 and Cvi and their hybrid offspring was compared by chromatin immunoprecipitation in combination with genome tiling array hybridization. The analysis revealed that, in addition to DNA sequence polymorphisms, chromatin modification variations exist among accessions of A. thaliana. The range of these variations was higher for H3K27me3 (typically a repressive mark) than for H3K4me2 (typically an active mark). H3K4me2 and H3K27me3 were rather stable in response to intra‐species hybridization, with mainly additive inheritance in hybrid offspring. In conclusion, intra‐species hybridization does not result in gross changes to chromatin modifications.     

Seasonal and wastewater stream variation of trace organic compounds in a dairy processing plant aerobic bioreactor

Bioreactors are often an integral part of dairy factory efforts to reduce the biological oxygen demand of their wastewater. In this study, infeed, mixed liquor and supernatant samples of an aerobic bioreactor used by a dairy factory in South-Eastern Australia were analyzed for nutrients and organic compounds using gas chromatography-mass spectrometry and physicochemical analyses. Despite different concentrations of organic inputs into the bioreactor, nutrients and trace organic compounds were reduced significantly (i.e. average concentration of trace organic compounds: infeed = 1681 μg/L; mixed liquor = 257 μg/L; supernatant = 23 μg/L). However, during one sampling period the bioreactor was adversely affected by the organic loading. Trace organic compounds in the samples were predominantly fatty acids associated with animal products. The analyses suggest that it is possible to trace a disruptive input (i.e. infeed with high organic carbon concentrations) into an aerobic bioreactor by measuring concentrations of fatty acids or ammonia.     

Sustainability of algae derived biodiesel: a mass balance approach

A rigorous chemical engineering mass balance/unit operations approach is applied here to bio-diesel from algae mass culture. An equivalent of 50,000,000 gallons per year (0.006002 m3/s) of petroleum-based Number 2 fuel oil (US, diesel for compression-ignition engines, about 0.1% of annual US consumption) from oleaginous algae is the target. Methyl algaeate and ethyl algaeate diesel can according to this analysis conceptually be produced largely in a technologically sustainable way albeit at a lower available diesel yield. About 11 square miles of algae ponds would be needed with optimistic assumptions of 50 g biomass yield per day and m2 pond area. CO2 to foster algae growth should be supplied from a sustainable source such as a biomass-based ethanol production. Reliance on fossil-based CO2 from power plants or fertilizer production renders algae diesel non-sustainable in the long term.     

Increasing variation in taxonomic distinctness reveals clusters of specialists in the deep sea

Changes in biodiversity with latitude or along a given environmental gradient have been described in many studies, including for marine ecosystems. Currently there is no scientific consensus, however, regarding macroecological patterns of diversity vs depth. Here, we describe variation in the biodiversity of fishes along a depth gradient from 0 to 2000 m in the region of the Norfolk Ridge and Lord Howe Rise (Western Pacific), using data obtained during the NORFANZ voyage. We modelled α diversity (richness), β diversity (using Jaccard's coefficient), evenness, taxonomic distinctness and taxonomic resemblances among fish communities. Although α diversity did not change appreciably with depth, β diversity decreased significantly in deeper strata. Both taxonomic resemblances and Jaccard similarities diminished with depth, indicating convergence in community structure. In addition, average taxonomic distinctness showed no clear pattern with depth, but taxonomic trees constructed among species within deeper samples had more variable path‐lengths than those in shallower samples. The presence of taxonomically distinct clusters of highly related species at depth indicates specialised niches that have developed in a relatively extreme (dark, pressurized) yet stable environment. We propose that reduced β diversity and increased variation in taxonomic distinctness might serve as indicators of ecological communities living in harsh environments – a hypothesis that should be tested in other systems, such as deserts, high altitudes or latitudes.