Characterisation of human-associated viral communities is essential for epidemiological surveillance and to be able to anticipate new potential threats for blood transfusion safety. In high-resource countries, the risk of blood-borne agent transmission of well-known viruses (HBV, HCV, HIV and HTLV) is currently considered to be under control. However, other unknown or unsuspected viruses may be transmitted to recipients by blood-derived products. To investigate this, the virome of plasma from individuals at high risk for parenterally and sexually transmitted infections was analysed by high throughput sequencing (HTS).Purified nucleic acids from two pools of 50 samples from recipients of multiple transfusions, and three pools containing seven plasma samples from either HBV-, HCV- or HIV-infected blood donors, were submitted to HTS.Sequences from resident anelloviruses and HPgV were evidenced in all pools. HBV and HCV sequences were detected in pools containing 3.8×10(3) IU/mL of HBV-DNA and 1.7×10(5) IU/mL of HCV-RNA, respectively, whereas no HIV sequence was found in a pool of 150 copies/mL of HIV-RNA. This suggests a lack of sensitivity in HTS performance in detecting low levels of virus. In addition, this study identified other issues, including laboratory contaminants and the uncertainty of taxonomic assignment of short sequence. No sequence suggestive of a new viral species was identified.This study did not identify any new blood-borne virus in high-risk individuals. However, rare and/or viruses present at very low titre could have escaped our protocol. Our results demonstrate the positive contribution of HTS in the detection of viral sequences in blood donations.
Human exposure to boron occurs primarily through diet and drinking water sources. Animal studies have found that reduced fetal weight following gestational exposure to boron (as boric acid) is the most sensitive toxicological effect. However, recent studies suggest that newborns in areas with elevated boron in drinking water may receive levels of exposure that exceed the U.S. EPA oral reference dose for B. Currently, there are no data to inform a boron risk assessment accounting for this developmental window. To address this knowledge gap, the National Toxicology Program evaluated developmental toxicity following pre- and postnatal boron exposure. Time-mated female Sprague Dawley (Hsd: Sprague Dawley SD) rats were administered 0-20 mg B/kg/day (as boric acid) via gavage from gestation day 6 to 21; offspring were dosed via gavage at the same respective dose level from postnatal day (PND) 1 to 28. There were no dose-related effects on dam bodyweight, bodyweight gain, or feed consumption. Clinical findings were limited to low incidences of umbilical hernia in the 20 mg B/kg pups which resolved by study completion. Pup plasma boron concentrations increased in dose-proportional manner and were similar between PND 4 and PND 28. Postnatal weight gain was significantly reduced at 20 mg B/kg, with male and female pups weighing 23% less than the controls on PND 28. These findings demonstrate that postnatal growth in the Sprague Dawley rat is sensitive to boron exposure and highlights the importance of evaluating the potential toxicity of agents with known human exposures during early life stages.
The highly toxic environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has recently been shown to stimulate proliferation of two human squamous carcinoma cell lines, SCC-15G and SCC-25, by decreasing the sensitivity of the cells to high density growth arrest. TCDD is known to alter the activity of several endogenous growth-regulatory compounds, and this study was undertaken to investigate the possibility that modulation of transforming growth factor beta (TGF-beta) activity might be involved in the mechanism of growth stimulation by TCDD. TGF-beta inhibited monolayer growth and DNA synthesis of SCC-15G and SCC-25 cells equally well in the presence and the absence of 10 nM TCDD. TCDD alone stimulated proliferation and inhibited differentiation in both cell lines but had no effect on binding of 125I-TGF-beta to or secretion of TGF-beta by SCC-15G cells. Inhibition of growth of SCC-15G cultures by TGF-beta was incomplete, in that cell number continued to increase even in the presence of 100 pM TGF-beta, although at a greatly reduced rate compared to non-TGF-beta-treated controls. These cells, grown in 100 pM TGF-beta alone, reached growth arrest at the same density as non-TGF-beta-treated cultures but failed to reach density-dependent growth arrest when treated with TCDD. Cells treated for 12 h with TCDD exhibited maximal induction of ethoxyresorufin-O-deethylase activity. TGF-beta inhibited this induction in a dose-dependent manner even when added after a 12-h TCDD pretreatment. The inhibition was rapidly reversible after removal of TGF-beta, indicating that it occurred via a mechanism which did not involve inhibition of very early steps in the TCDD response pathway. These results demonstrate that the stimulatory effect of TCDD on keratinocyte proliferation is not mediated through alterations in TGF-beta activity and that TCDD and TGF-beta appear to exert their opposite effects on cellular proliferation by independent mechanisms.
SUMMARY Extracts of Sesbania drummondii administered to chickens by oral intubation are lethal within several days. Effects are dose-dependent; a dose of 1% of body weight is uniformly lethal in 5 days. Signs of poisoning include weakness, depression ( cns ), anorexia, diarrhea, ruffled feathers, cold feet, and rapid loss of body weight. Microscopic examination indicates damage to kidney glomeruli and leakage of protein into the kidney tubules. Packed cell volume and plasma glucose concentrations show no difference between controls and treated chickens; however, creatine kinase is increased and plasma cholinesterase and total plasma protein values are severely depressed in poisoned birds. Neither a specific toxin nor a mechanism of action for toxicity has yet been identified.
Recent epidemics caused by different mosquito‐borne viruses underline the viral diversity associated to mosquitoes. However, beyond human viral pathogens, we know little on other viruses of the mosquito virome. This unexplored diversity probably influences vector competence and other aspects of the mosquito biology, as shown for the mosquito bacteriome. We have analysed the virome of Culex pipiens, a mosquito vector of important arboviruses like Rift Valley fever virus or West Nile fever virus. To this end, we have coupled a metagenomics approach with a large sampling campaign involving different countries and habitats around the Mediterranean basin. Our results show for the first time conserved patterns in virus diversity among mosquito populations, as well as specificities probably linked to different environmental conditions. The discovery of a ubiquitous group of viruses strongly supports the existence of a core virome in Culex pipiens that is likely to influence mosquito physiology.
Numerous non-coding RNAs are known to be involved in the regulation of gene expression. In this work, we analyzed RNAs that co-immunoprecipitated with human RNA polymerase II from mitotic cell extracts and identified U1 small nuclear RNA (snRNA) as a major species. To investigate a possible splicing-independent recruitment of U1 snRNA to transcription units, we established cell lines having integrated a reporter gene containing a functional intron or a splicing-deficient construction. Recruitment of U snRNAs and some splicing factors to transcription sites was evaluated using fluorescence in situ hybridization (FISH) and immunofluorescence. To analyze imaging data, we developed a quantitative procedure, 'radial analysis', based on averaging data from multiple fluorescence images. The major splicing snRNAs (U2, U4 and U6 snRNAs) as well as the U2AF65 and SC35 splicing factors were found to be recruited only to transcription units containing a functional intron. By contrast, U1 snRNA, the U1-70K (also known as snRNP70) U1-associated protein as well as the ASF/SF2 (also known as SFRS1) serine/arginine-rich (SR) protein were efficiently recruited both to normally spliced and splicing-deficient transcription units. The constitutive association of U1 small nuclear ribonucleoprotein (snRNP) with the transcription machinery might play a role in coupling transcription with pre-mRNA maturation.
Subchronic Toxicity of Cupric Sulfate Administered in Drinking Water and Feed to Rats and Mice. HÉBERT, C. D., ELWELL, M. R., TRAVLOS, G. S., FITZ, C. J., AND BUCHER, J. R. (1993). Fundam. Appl. Toxicol. 21, 461–475. The effects of acute poisoning by cupric sulfate in a number of species are well known; however, the effects of chronic low-level ingestion of cupric sulfate are less well characterized. Because exposure of humans to cupric sulfate may occur through drinking water, food, soil, or ambient air, subchronic toxicity studies were conducted in male and female F344/N rats and B6C3F1 mice by the drinking water (2-week exposure) and dosed feed (2-and 13-week exposure) routes. Animals were evaluated for histopathology, clinical pathology, reproductive toxicity, and tissue metal accumulation, and target organs were examined by a variety of special stains and by electron microscopy to characterize the observed lesions. In drinking water, cupric sulfate concentrations of 300 to 100 ppm produced no ill effects, whereas concentrations of 3000 to 30,000 ppm were lethal to rats and mice within 2 weeks. In feed, cupric sulfate concentrations of 4000 to 16,000 ppm caused significant reductions in body weight gain in both species in the 2- and 13-week studies. Hyperplasia and hyperkeratosis of the limiting ridge of the forestomach were present in both species in the 2- and 13-week studies. Rats in the dosed feed studies had a dose-related increase in inflammation in the liver and changes in clinical chemistry parameters which were indicative of hepatocellular damage and cholestasis. Histologic changes in the kidneys of rats consisted of a dose-related increase in the number and size of eosinophilic protein droplets in the epithelial cytoplasm and the lumina of the proximal convoluted tubules. Droplets were larger and more numerous in males than in females. Urinalysis results were suggestive of renal tubular epithelial damage. Iron staining of spleens from treated animals indicated a marked depletion of iron stores in both male and female rats, but not in mice, while hematologic and clinical chemistry alterations in rats in the 13-week study, along with histologic changes in bone in the 2-week dosed feed study, were indicative of a microcytic anemia. Cupric sulfate produced no adverse effects on any of the reproductive parameters measured in rats or mice of either sex. These results indicate that cupric sulfate at high exposure levels is a hepatic and renal toxicant, as well as an inducer of anemia in rodents, with rats more sensitive than mice following subchronic exposure.
