Effects of biochar amendment on root traits and contaminant availability of maize plants in a copper and arsenic impacted soil

Background and aims

Biochar has been proposed as a tool to enhance phytostabilisation of contaminated soils but little data are available to illustrate the direct effect on roots in contaminated soils. This work aimed to investigate specific root traits and to assess the effect of biochar amendment on contaminant availability.

Methods

Amendment with two different types of biochar, pine woodchip and olive tree pruning, was assessed in a rhizobox experiment with maize planted in a soil contaminated with significant levels of copper and arsenic.

Results

Amendment was found to significantly improve root traits compared to the control soil, particularly root mass density and root length density. Copper uptake to plants and ammonium sulphate extractable copper was significantly less in the biochar amended soils. Arsenic uptake and extractability varied with type of biochar used but was not considered to be the limiting factor affecting root and shoot development.

Conclusions

Root establishment in contaminated soils can be enhanced by biochar amendment but choice of biochar is key to maximising soil improvement and controlling contaminant availability.     

No evidence of murine leukemia virus-related viruses in live attenuated human vaccines

Background

The association of xenotropic murine leukemia virus (MLV)-related virus (XMRV) in prostate cancer and chronic fatigue syndrome reported in previous studies remains controversial as these results have been questioned by recent data. Nonetheless, concerns have been raised regarding contamination of human vaccines as a possible source of introduction of XMRV and MLV into human populations. To address this possibility, we tested eight live attenuated human vaccines using generic PCR for XMRV and MLV sequences. Viral metagenomics using deep sequencing was also done to identify the possibility of other adventitious agents.

Results

All eight live attenuated vaccines, including Japanese encephalitis virus (JEV) (SA-14-14-2), varicella (Varivax), measles, mumps, and rubella (MMR-II), measles (Attenuvax), rubella (Meruvax-II), rotavirus (Rotateq and Rotarix), and yellow fever virus were negative for XMRV and highly related MLV sequences. However, residual hamster DNA, but not RNA, containing novel endogenous gammaretrovirus sequences was detected in the JEV vaccine using PCR. Metagenomics analysis did not detect any adventitious viral sequences of public health concern. Intracisternal A particle sequences closest to those present in Syrian hamsters and not mice were also detected in the JEV SA-14-14-2 vaccine. Combined, these results are consistent with the production of the JEV vaccine in Syrian hamster cells.

Conclusions

We found no evidence of XMRV and MLV in eight live attenuated human vaccines further supporting the safety of these vaccines. Our findings suggest that vaccines are an unlikely source of XMRV and MLV exposure in humans and are consistent with the mounting evidence on the absence of these viruses in humans.     

No association of xenotropic murine leukemia virus-related viruses with prostate cancer

BACKGROUND: The association of the xenotropic murine leukemia virus-related virus (XMRV) with prostate cancer continues to receive heightened attention as studies report discrepant XMRV prevalences ranging from zero up to 23%. It is unclear if differences in the diagnostic testing, disease severity, geography, or other factors account for the discordant results. We report here the prevalence of XMRV in a population with well-defined prostate cancers and RNase L polymorphism. We used broadly reactive PCR and Western blot (WB) assays to detect infection with XMRV and related murine leukemia viruses (MLV). METHODOLOGY/PRINCIPAL FINDINGS: We studied specimens from 162 US patients diagnosed with prostate cancer with a intermediate to advanced stage (Gleason Scores of 5-10; moderate (46%) poorly differentiated tumors (54%)). Prostate tissue DNA was tested by PCR assays that detect XMRV and MLV variants. To exclude contamination with mouse DNA, we also designed and used a mouse-specific DNA PCR test. Detailed phylogenetic analysis was used to infer evolutionary relationships. RNase L typing showed that 9.3% were homozygous (QQ) for the R462Q RNase L mutation, while 45.6% and 45.1% were homozygous or heterozygous, respectively. Serologic testing was performed by a WB test. Three of 162 (1.9%) prostate tissue DNA were PCR-positive for XMRV and had undetectable mouse DNA. None was homozygous for the QQ mutation. Plasma from all three persons was negative for viral RNA by RT-PCR. All 162 patients were WB negative. Phylogenetic analysis inferred a distinct XMRV. CONCLUSIONS AND THEIR SIGNIFICANCE: We found a very low prevalence of XMRV in prostate cancer patients. Infection was confirmed by phylogenetic analysis and absence of contaminating mouse DNA. The finding of undetectable antibodies and viremia in all three patients may reflect latent infection. Our results do not support an association of XMRV or MLV variants with prostate cancer.     

Size assortment in mixed-species groups of juvenile-phase striped parrotfish (Scarus iserti) in The Bahamas

Striped parrotfish (Scarus iserti) often form heterospecific groups with other reef fishes. In this study, we examined the species and body size composition of these groups on reefs in The Bahamas. Groups averaged approximately 4 S.?iserti and 2 associated species, with surgeonfish (Acanthurus chirurgus and A.?bahianus), slippery dick (Halichoeres bivittatus), and bluehead wrasse (Thalassoma bifasciatum) as the most common associates. Fewer groups than expected had only 1 associate; groups with 3 or more associates were more common than expected. Both the S.?iserti and associated species tended to be closely size-matched within a group, perhaps due to benefits of size assortment in lowering predation risk. Likewise, the high frequency of groups with greater than a single associate species suggests that associates may benefit from not being the only phenotypically different individual in a group.     

Non-redox roles for iron-sulfur clusters in enzymes

In recent years a number of enzymes have been discovered which, contrary to prior expectations, contain FeS clusters but do not participate in redox reactions. In all cases but one, where the FeS cluster in these enzymes has been identified, it is a [4Fe-4S] cluster. In mammalian aconitase a single Fe atom of the [4Fe-4S] cluster participates in catalysis of hydration-dehydration reactions by direct ligation to the substrates. A number of hydrolyases containing FeS clusters have now been identified. In Bacillus subtilis glutamine phosphoribosyl-pyrophosphate amidotransferase the [4Fe-4S] cluster is essential for the active structure of the enzyme, but probably does not participate directly in catalysis. Rather, the cluster may serve as part of a mechanism of oxidative inactivation of the enzyme in vivo, which is followed by its intracellular degradation. The role played by a [4Fe-4S] cluster in Escherichia coli endonuclease III is at present completely unknown. Thus, a number of novel roles for FeS clusters in enzymology and protein structure have been discovered, and more novel findings must be anticipated.     

PERMANENT GENETIC RESOURCES: Microsatellite DNA primers for the candy darter, Etheostoma osburni and variegate darter, Etheostoma variatum, and cross-species amplification in other darters (Percidae)

In order to investigate a potential hybrid zone between the candy darter, Etheostoma osburni, and variegate darter, Etheostoma variatum, and examine population variation within E. osburni, a suite of primers for 15 polymorphic microsatellite loci were developed. The average number of alleles per locus was 5.5 in E. osburni and 7.6 in E. variatum, and the average observed heterozygosities were 62.5% and 71.4%, respectively. There were no deviations from Hardy-Weinberg equilibrium and no observed linkage disequilibrium after Bonferroni correction. The utility of these primers was also tested in 11 species of darters representing all four genera of darters. Success of cross-species amplification was largely consistent with phylogenetic relationships of darters.