Comparative proteomics unravelled the hexachlorocyclohexane (HCH) isomers specific responses in an archetypical HCH degrading bacterium Sphingobium indicum B90A

Hexachlorocyclohexane (HCH) is a persistent organochlorine pesticide that poses threat to different life forms. Sphingobium indicum B90A that belong to sphingomonad is well-known for its ability to degrade HCH isomers (α-, β-, γ-, δ-), but effects of HCH isomers and adaptive mechanisms of strain B90A under HCH load remain obscure. To investigate the responses of strain B90A to HCH isomers, we followed the proteomics approach as this technique is considered as the powerful tool to study the microbial response to environmental stress. Strain B90A culture was exposed to α-, β-, γ-, δ-HCH (5 mgL^-1) and control (without HCH) taken for comparison and changes in whole cell proteome were analyzed. In β- and δ-HCH-treated cultures growth decreased significantly when compared to control, α-, and γ-HCH-treated cultures. HCH residue analysis corroborated previous observations depicting the complete depletion of α- and γ-HCH, while only 66% β-HCH and 34% δ-HCH were depleted from culture broth. Comparative proteome analyses showed that β- and δ-HCH induced utmost systemic changes in strain B90A proteome, wherein stress-alleviating proteins such as histidine kinases, molecular chaperons, DNA binding proteins, ABC transporters, TonB proteins, antioxidant enzymes, and transcriptional regulators were significantly affected. Besides study confirmed constitutive expression of linA, linB, and linC genes that are crucial for the initiation of HCH isomers degradation, while increased abundance of LinM and LinN in presence of β- and δ-HCH suggested the important role of ABC transporter in depletion of these isomers. These results will help to understand the HCH-induced damages and adaptive strategies of strain B90A under HCH load which remained unravelled to date.

Prostate cancer incidence and agriculture practices in Georgia, 2000-2010

BACKGROUND

Georgia has prostate cancer incidence rates consistently above the national average. A notable portion of Georgia's economy is rooted in agricultural production, and agricultural practices have been associated with an increased risk of prostate cancer.

METHODS

Statistical analyses considered county age-adjusted prostate cancer incidence rates as the outcome of interest and three agricultural variables (farmland as percent of county land, dollars spent per county acre on agriculture chemicals, and dollars spent per county acre on commercial fertilizers) as exposures of interest. Multivariate linear regression models analyzed for each separately. Data were obtained from National Cancer Institute Surveillance, Epidemiology and End Results (SEER) 2000-2010, United States Department of Agriculture (USDA) 1987 Agriculture Survey, and 2010 US Census.

RESULTS

In counties with equal to or greater than Georgia counties' median percent African-American population (27%), dollars per acre spent on agriculture chemicals was significantly associated (P = 0.04) and dollars spent of commercial fertilizers was moderately associated (P = 0.07) with elevated prostate cancer incidence rates. There was no association between percent of county farmland and prostate cancer rates.

CONCLUSION

This study identified associations between prostate cancer incidence rates, agriculture chemical expenditure, and commercial fertilizer expenditure in Georgia counties with a population comprised of more than 27% of African Americans.