Refinar búsqueda
Resultados 1-10 de 17
Impact of microorganisms and entomopathogenic nematodes used for plant protection on solitary and social bee pollinators: Host range, specificity, pathogenicity, toxicity, and effects of experimental parameters
2022
Erler, Silvio | Eckert, Jakob H. | Steinert, Michael | Alkassab, Abdulrahim T.
Pollinating bees are stressed by highly variable environmental conditions, malnutrition, parasites and pathogens, but may also by getting in contact with microorganisms or entomopathogenic nematodes that are used to control plant pests and diseases. While foraging for water, food, or nest material social as well as solitary bees have direct contact or even consume the plant protection product with its active substance (e.g., viruses, bacteria, fungi, etc.). Here, we summarize the results of cage, microcolony, observation hive assays, semi-field and field studies using full-size queen-right colonies. By now, some species and subspecies of the Western and Eastern honey bee (Apis mellifera, A. cerana), few species of bumble bees, very few stingless bee species and only a single species of leafcutter bees have been studied as non-target host organisms. Survival and reproduction are the major criteria that have been evaluated. Especially sublethal effects on the bees' physiology, immune response and metabolisms will be targets of future investigations. By studying infectivity and pathogenic mechanisms, individual strains of the microorganism and impact on different bee species are future challenges, especially under field conditions. Overall, it became evident that honey bees, bumble bees and few stingless bee species may not be suitable surrogate species to make general conclusions for biological mechanisms of bee-microorganism interactions of other social bee species. Solitary bees have been studied on leafcutter bees (Megachile rotundata) only, which shows that this huge group of bees (∼20,000 species worldwide) is right at the beginning to get an insight into the interaction of wild pollinators and microbial plant protection organisms.
Mostrar más [+] Menos [-]Nitrate exposure induces intestinal microbiota dysbiosis and metabolism disorder in Bufo gargarizans tadpoles
2020
Xie, Lei | Zhang, Yuhui | Gao, Jinshu | Li, Xinyi | Wang, Hongyuan
Excess nitrate has been reported to be associated with many adverse effects in humans and experimental animals. However, there is a paucity of information of the effects of nitrate on intestinal microbial community. In this study, the effects of nitrate on development, intestinal microbial community, and metabolites of Bufo gargarizans tadpoles were investigated. B. gargarizans were exposed to control, 5, 20 and 100 mg/L nitrate-nitrogen (NO₃–N) from eggs to Gosner stage 38. Our data showed that the body size of tadpoles significantly decreased in the 20 and 100 mg/L NO₃–N treatment group when compared to control tadpoles. Exposure to 20 and 100 mg/L NO₃–N also caused indistinct cell boundaries and nuclear pyknosis of mucosal epithelial cells in intestine of tadpoles. In addition, exposure to NO₃–N significantly altered the intestinal microbiota diversity and structure. The facultative anaerobic Proteobacteria occupy the niche of the obligately anaerobic Bacteroidetes and Fusobacteria under the pressure of NO₃–N exposure. According to the results of functional prediction, NO₃–N exposure affected the fatty acid metabolism pathway and amino acid metabolism pathway. The whole-body fatty acid components were found to be changed after exposure to 100 mg/L NO₃–N. Therefore, we concluded that exposure to 20 and 100 mg/L NO₃–N could induce deficient nutrient absorption in intestine, resulting in malnutrition of B. gargarizans tadpoles. High levels of NO₃–N could also change the intestinal microbial communities, causing dysregulation of fatty acid metabolism and amino acid metabolism in B. gargarizans tadpoles.
Mostrar más [+] Menos [-]Glyphosate has limited short-term effects on commensal bacterial community composition in the gut environment due to sufficient aromatic amino acid levels
2018
Nielsen, Lene Nørby | Roager, Henrik M. | Casas, Mònica Escolà | Frandsen, Henrik L. | Gosewinkel, Ulrich | Bester, Kai | Licht, Tine Rask | Hendriksen, Niels Bohse | Bahl, Martin Iain
Recently, concerns have been raised that residues of glyphosate-based herbicides may interfere with the homeostasis of the intestinal bacterial community and thereby affect the health of humans or animals. The biochemical pathway for aromatic amino acid synthesis (Shikimate pathway), which is specifically inhibited by glyphosate, is shared by plants and numerous bacterial species. Several in vitro studies have shown that various groups of intestinal bacteria may be differently affected by glyphosate. Here, we present results from an animal exposure trial combining deep 16S rRNA gene sequencing of the bacterial community with liquid chromatography mass spectrometry (LC-MS) based metabolic profiling of aromatic amino acids and their downstream metabolites. We found that glyphosate as well as the commercial formulation Glyfonova®450 PLUS administered at up to fifty times the established European Acceptable Daily Intake (ADI = 0.5 mg/kg body weight) had very limited effects on bacterial community composition in Sprague Dawley rats during a two-week exposure trial. The effect of glyphosate on prototrophic bacterial growth was highly dependent on the availability of aromatic amino acids, suggesting that the observed limited effect on bacterial composition was due to the presence of sufficient amounts of aromatic amino acids in the intestinal environment. A strong correlation was observed between intestinal concentrations of glyphosate and intestinal pH, which may partly be explained by an observed reduction in acetic acid produced by the gut bacteria. We conclude that sufficient intestinal levels of aromatic amino acids provided by the diet alleviates the need for bacterial synthesis of aromatic amino acids and thus prevents an antimicrobial effect of glyphosate in vivo. It is however possible that the situation is different in cases of human malnutrition or in production animals.
Mostrar más [+] Menos [-]Proximity to roads, but not exposure to metal pollution, is associated with accelerated developmental telomere shortening in nestling great tits
2020
Grunst, A.S. | Grunst, M.L. | Bervoets, L. | Pinxten, R. | Eens, M.
Comprehensively understanding the factors affecting physiology and fitness in urban wildlife requires concurrently considering multiple stressors. To this end, we simultaneously assessed how metal pollution and proximity to roads affect body condition and telomere shortening between days 8 and 15 of age in nestling great tits (Parus major), a common urban bird. We employed a repeated-measures sampling design to compare telomere shortening and body condition between nestlings from four urban study sites south of Antwerp, Belgium, which are located at different distances from a metal pollution point source. In addition, we explored associations between metal exposure and telomere dynamics on the individual level by measuring blood concentrations of five metals/metalloids, of which lead, copper and zinc were present at concentrations above the limit of detection. To assess whether roadway-associated stressors (e.g. noise and air pollution) might affect nestling condition and telomere shortening, we measured the proximity of nest boxes to roads. Metal exposure was not associated with nestling telomere length or body condition, despite elevated blood lead concentrations close to the metal pollution source (mean ± SE = 0.270 ± 0.095 μg/g wet weight at the most polluted study site), suggesting that nestlings may have some capacity to detoxify metals. However, nestlings from nest boxes near roads exhibited more telomere shortening between days 8 and 15 of age, and shorter telomeres at day 15. Nestlings in poorer condition also had shorter telomeres, but proximity to the road was unrelated to body condition. Thus, nutritional stress is unlikely to mediate the relationship between proximity to roads and telomere length. Rather, proximity to roads could have affected telomere shortening by exposing nestlings to air or noise pollution. Our study highlights that traffic-related pollution, which is implicated in human health problems, might also affect urban wildlife.
Mostrar más [+] Menos [-]Persistent organic pollutants and stable isotopes in pinnipeds from King George Island, Antarctica
2012
Cipro, Caio V.Z. | Bustamante, Paco | Taniguchi, Satie | Montone, Rosalinda Carmela
In the present work, fat, skin, liver and muscle samples from Leptonychotes weddellii (Weddell seal, n=2 individuals), Lobodon carcinophagus (crabeater seal, n=2), Arctocephalus gazella (Antarctic fur seal, n=3) and Mirounga leonina (southern elephant seal, n=1) were collected from King George Island, Antarctica, and analysed for POPs (PCBs, organochlorine pesticides and PBDEs) and stable isotopes (δ¹³C and δ¹⁵N in all tissues but fat). PBDEs could be found in only one sample (L. weddellii fat). Generally, PCBs (from 74 to 523ngg⁻¹lw), DDTs (from 14 to 168ngg⁻¹lw) and chlordanes (from 9 to 78ngg⁻¹lw) were the prevailing compounds. Results showed a clear stratification in accordance with ecological data. Nonetheless, stable isotope analyses provide a deeper insight into fluctuations due to migrations and nutritional stress. Correlation between δ¹⁵N and pollutants suggests, to some degree, a considerable ability to metabolize and/or excrete the majority of them.
Mostrar más [+] Menos [-]Ingestion of macroplastic debris by the common dolphinfish (Coryphaena hippurus) in the Western Equatorial Atlantic
2019
Menezes, Rafael | da Cunha-Neto, Manuel Alves | de Mesquita, Grazielly Campos | da Silva, Guelson Batista
We report the occurrence of macroplastic debris in the stomach of a common dolphinfish (Coryphaena hippurus) caught in the Western Equatorial Atlantic. On the deck, we noticed that the fish was remarkably undernourished and decided to remove its stomach for laboratory analysis. A large part of a plastic bowl and a tuna pectoral fin were the only items recorded in the fish stomach. The plastic measured 99.57 cm2 and weighed 12.77 g, likely blocking the digestive tract and reducing food intake by the fish, as supported by signs of starvation. This is the record of the largest plastic debris ingested by a dolphinfish to date. As the source of the plastic container was probably a tuna fishing boat, we suggest strengthening environmental education programs to enhance the awareness of fishermen and mitigate the impacts of plastic pollution on the pelagic ecosystem and associated organisms, such as C. hippurus.
Mostrar más [+] Menos [-]How Does Contamination of Rice Soils with Cd and Zn Cause High Incidence of Human Cd Disease in Subsistence Rice Farmers
2015
Chaney, Rufus L.
Rice (Oryza sativa L.) grown on Zn mine waste contaminated soils has caused unequivocal Cd effects on kidney and occasional bone disease (itai-itai) in subsistence rice farmers, but high intake of Cd from other foods has not caused similar effects. Research has clarified two important topics about how Cd from mine waste contaminated rice soils has caused Cd disease: (1) bioaccumulation of soil Cd into rice grain without corresponding increase in Zn, and (2) subsistence rice diets potentiate Cd absorption/bioavailability and risk to farm families. Absorption of Cd by rice roots occurs on the NRAMP5 Mn²⁺ transporter. Although other transporters can influence Cd uptake-transport to shoots and grain, making NRAMP5 null greatly reduces grain Cd. Zn²⁺ has little ability to inhibit Cd²⁺ transfer in rice but clearly inhibits Cd uptake in other plant species. The bioavailability of dietary Cd is increased for subsistence rice diets. Research has identified that low levels and bioavailability of Zn and Fe in polished rice grain cause upregulation of Cd absorption on the Fe²⁺ transporter of duodenum cells (DMT1). Added dietary Zn can also inhibit intestinal Cd absorption somewhat. Nutritional stress (Fe, Zn deficiency) in humans consuming subsistence rice diets thus promotes Cd accumulation and adverse effects. No other dietary (crop) Cd exposure has caused unequivocal Cd-induced renal proximal tubular dysfunction (the first adverse Cd effect) in humans. Recognition of the very unusual nature of Cd risk from rice compared to other crops should be taken into account in setting international limits of Cd in rice and other foods.
Mostrar más [+] Menos [-]Improving carbohydrate accumulation in Chlamydomonas debaryana induced by sulfur starvation using response surface methodology
2022
Tazi, Karima | Jamai, Latifa | Seddouk, Loubna | Ettayebi, Mohamed | Mohammed, Alaoui-Mhamdi | Aleya, Lotfi | Idrissi, Abdellatif Janati
Most methods that promote carbohydrate production negatively affect cell growth and microalgal biomass production. This study explores, in a two-stage cultivation strategy, in Chlamydomonas debaryana the optimization of certain culture conditions for high carbohydrate production without loss of biomass. In the first stage, the interaction between sodium bicarbonate supplementation, aeration, and different growth periods was optimized using the response surface methodology (RMS). The 3-factor Box-Behnken design (BBD) was applied, and a second-order polynomial regression analysis was used to analyze the experimental data. The results showed that 0.45 g L⁻¹ of sodium bicarbonate combined with a good aerated agitation (0.6 L min⁻¹) and a cultivation period of 18 days are optimal to produce 5.02 g L⁻¹ of biomass containing 43% of carbohydrates.Under these optimized growth conditions, accumulation of carbohydrates was studied using different modes of nutritional stress. The results indicated that carbohydrate content was improved and the maximum accumulation (about 60% of the dry weight) was recorded under sulfur starvation with only a 14% reduction in biomass as compared to control. This study showed promising results as to biomass production and carbohydrate yield by the microalgae C. debaryana in view of production of third-generation biofuels.
Mostrar más [+] Menos [-]Recent Advances of Nanotechnology in Mitigating Emerging Pollutants in Water and Wastewater: Status, Challenges, and Opportunities
2022
Naskar, Jishnu | Boatemaa, Mercy Adusei | Rumjit, Nelson Pynadathu | Thomas, George | George, P. J. | Lai, Chin Wei | Mousavi, Seyyed Mojtaba | Wong, Yew Hoong
Availability of clean and safe freshwater has become a looming global concern. The accelerated demography, industrialization, and climate changes contaminate the meager freshwater reserves. Pollution of water bodies is significantly detrimental to health, ecology, economy, and society. The rising number of malnutrition cases, stunted growth, hepatitis, gastroenteritis, skin ailments, cholera, respiratory disorders, liver malfunction, eye infections, and mortality have been attributed to exposure to compromised water. Thus, optimized, durable, and inexpensive wastewater treatment and remediation processes are necessary. Current conventional treatment strategies suffer from several drawbacks, which may be mitigated through nanotechnological intercession, promising sustainability. Nanomaterials include nanosorbents, carbon nanotubes, nanocomposites, nanofibers, graphene, nanodendrimers, nanomembranes, and nanocatalysts. They have unique properties that make attractive alternatives for wastewater remediation, purification, and contamination detection through pollutant-specific nanosensors and detectors. This review discusses water pollution, its impacts, conventional treatment strategies, nanotechnological contributions, venture possibilities, and associated commercial opportunities.
Mostrar más [+] Menos [-]Sanitation ladder and undernutrition among under-five children in Pakistan
2021
Khan, Asfand Yar | Fatima, Kaneez | ʻAlī, Muḥammad
While the state of sanitation in Pakistan has improved in the last decade, a significant proportion of its population is still using inadequate sanitation or no toilet facility at all. Open defecation has decreased over the years; however, it has been replaced by poor quality sanitation in rural areas that might still cause diarrhoea and undernutrition. The research regarding inadequate sanitation in Pakistan, especially in terms of the sanitation ladder, remains limited. The present research thus fills this research gap by assessing the impact of different types of sanitation on the prevalence of stunting and underweight (moderate as well as severe) among under-five children in Pakistan using the nationally representative micro survey, Pakistan Demographic and Health Survey (2017-18). The sanitation ladder comprises of piped to sewer (highest level, base) followed by flush to septic tank, flush to pit latrine, other improved, unimproved sanitation, and open defecation. In order to estimate the adjusted and unadjusted odds ratios of the determinants, this research uses logistic regressions are used to estimate adjusted and unadjusted odds ratios of the determinants. We show that toilets connected to piped sewerage network are rare in the rural areas of Pakistan and a large segment of the rural population is still practicing open defecation. The logistic regressions show that piped sewerage network and flush to septic tanks are associated with lowest odds (both adjusted and unadjusted) of stunting and underweight among under-five children. In multivariate regressions, pit latrines are associated with even higher adjusted odds of severe and moderate and severe stunting as well as underweight among under-five children, showing that poor quality pit latrines may bring the source of faecal contamination to the doorstep of the households. Therefore, interventions targeting reduction in open defecation should promote good quality toilets for sustainable long-term improvements in child health.
Mostrar más [+] Menos [-]