Distribution and flux of organochlorine pesticides in sediment from Prydz Bay, Antarctic: Implication of sources and trends.

Surface sediments were collected from Prydz Bay, Antarctica to investigate the distribution patterns, origins, annual fluxes, and trends of organochlorine pesticides (OCPs) in the marginal sea of polar areas. The concentrations of OCPs ranged from 0.80 to 7.90 ng/g dry weight, with dichlorodiphenytrichloroethanes (DDTs) as the main components. Levels of hexachlorocyclohexanes (HCHs) and DDTs in sediment from Prydz Bay were comparable to the majority of marine sediment worldwide. The distributions of OCPs were characterized by a distinct "quasi-concentric circle" pattern, which has significantly positive relationship with total organic carbon (TOC) of sediment and controlled by the local hydrodynamic conditions and sources of organic matter. Source apportionment demonstrated that HCHs and chlordanes in Prydz Bay were mainly derived from the long range atmospheric transport (LRAT) of these compounds from off regions. However, current inputs of DDT-based compounds and lindane are suggested to exist either as a result of the LART from the neighbouring countries or re-emission from melting glacier. The annual sedimentary fluxes of OCPs were 0.007 to 7.12 pg/cm2/yr, about one to three orders of magnitude lower than some data from the Arctic areas. Based on a rough calculation of r-HCH, only 0.3-1.5% of the air-seawater net deposition would be buried in sediment, implying a long active lifetime of OCPs in Antarctica. We preliminarily indicate an increase of OCP contamination in Antarctic environment afterwards when considering the possible occurrence of "fresh" sources and low proportion of sedimentary sink.

Transcriptome­wide piRNA profiling in human gastric cancer.

Piwi­interacting RNAs (piRNAs) comprise the largest class of non­coding RNAs. They represent a molecular feature shared by all non­aging biological systems, including germline and somatic cancer stem cells, which display an indefinite capacity of renewal and proliferation and are potentially immortal. They have been identified in animal stomachs, but their relationship with human gastric cancers remains largely unclear. The present study aimed to identify the piRNAs associated with human gastric cancers across the whole transcriptome. Fresh tumor tissues and adjacent non­tumorous tissues from stomachs were examined using a piRNA microarray (23,677 piRNAs) that was then validated by qPCR. The differential expression of piRNAs between cases and controls was analyzed. The transposable elements (TEs) that are potentially targeted by the risk piRNAs were searched. The expression of the nearest genes that are complementary to the sequences of the piRNAs was examined in the stomach tissue. The regulatory effects of genome­wide significant and replicated cancer­risk DNA variants on the piRNA expression in stomach were tested. Based on the findings, we identified a total of 8,759 piRNAs in human stomachs. Of all, 50 were significantly (P<0.05) and differentially (>2­fold change) expressed between the cases and controls, and 64.7% of the protein­coding genes potentially regulated by the gastric cancer­associated piRNAs were expressed in the human stomach. The expression of many cancer­associated piRNAs was correlated with the genome­wide and replicated cancer­risk SNPs. In conclusion, we conclude that piRNAs are abundant in human stomachs and may play important roles in the etiological processes of gastric cancers.

Transcriptome-wide piRNA profiling in human brains for aging genetic factors.

OBJECTIVE: Piwi-interacting RNAs (piRNAs) represent a molecular feature shared by all nonaging biological systems, including the germline and somatic cancer stem cells, which display an indefinite renewal capacity and lifespan-stable genomic integrity and are potentially immortal. Here, we tested the hypothesis that piRNA is a critical genetic determinant of aging in humans. METHODS: Expression of transcriptome-wide piRNAs (n=24k) was profiled in the human prefrontal cortex of 12 subjects (84.9±9.5, range 68-100, years of age) using microarray technology. We examined the correlation between these piRNAs' expression levels and age, adjusting for covariates including disease status. RESULTS: A total of 9,453 piRNAs were detected in brain. Including seven intergenic and three intronic piRNAs, ten piRNAs were significantly associated with age after correction for multiple testing (|r|=0.9; 1.9×10-5≤p≤9.9×10-5). CONCLUSION: We conclude that piRNAs might play a potential role in determining the years of survival of humans. The underlying mechanisms might involve the suppression of transposable elements (TEs) and expression regulation of aging-associated genes.