Search results for "Guano"

2017

Because they can form seasonal mixed-species groups during mating and maternal care, bats are exciting models for studying interspecific hybridization. Myotis myotis and M. blythii are genetically close and morphologically almost identical, but they differ in some aspects of their ecology and life-history traits. When they occur in sympatry, they often form large mixed maternity colonies, in which their relative abundance can vary across time due to a shift in the timing of parturition. For the first time, we used non-invasive genetic methods to assess the hybridization rate and colony composition in a maternity colony of M. myotis and M. blythii located in the French Alps. Bat guano was co…

Biogeochemical cycling and ecological thresholds in a High Arctic lake (Svalbard)

2019

Lakes are a dominant feature of the Arctic landscape and a focal point of regional and global biogeochemical cycling. We collected a sediment core from a High Arctic Lake in southwestern Svalbard for multiproxy paleolimnological analysis. The aim was to find linkages between the terrestrial and aquatic environments in the context of climate change to understand centennial-long Arctic biogeochemical cycling and environmental dynamics. Two significant thresholds in elemental cycling were found based on sediment physical and biogeochemical proxies that were associated with the end of the cold Little Ice Age and the recent warming. We found major shifts in diatom, chironomid and cladoceran comm…

Guano-Derived Nutrient Subsidies Drive Food Web Structure in Coastal Ponds.

2016

A stable isotope study was carried out seasonally in three coastal ponds (Marinello system, Italy) affected by different gull guano input to investigate the effect of nutrient subsidies on food web structure and dynamics. A marked 15N enrichment occurred in the pond receiving the highest guano input, indicating that gull-derived fertilization (guanotrophication) had a strong localised effect and flowed across trophic levels. The main food web response to guanotrophication was an overall erosion of the benthic pathway in favour of the planktonic. Subsidized primary consumers, mostly deposit feeders, switched their diet according to organic matter source availability. Secondary consumers and,…

Human-Bat Interactions in Rural Southwestern Madagascar through a Biocultural Lens

2021

Human-bat interactions are common in rural areas across the tropics. Over 40 bat species occur in Madagascar, most of which are endemic. Forest loss is changing the distribution of bats throughout the island, with potential increases in both the abundance of synanthropic species and human-bat interactions. We set out to study knowledge of, interactions with, and attitudes towards bats in rural Madagascar, including reports of food and ethnomedicinal uses of bats, their cultural representations in folklore, and the existence of culturally enforced taboos in relation to them. We administered 108 surveys with open- and closed-ended questions with adults from the Tanala and Betsileo ethnic grou…

Are sacred caves still safe havens for the endemic bats of Madagascar?

2018

AbstractDespite conservation discourses in Madagascar increasingly emphasizing the role of customary institutions for wildlife management, we know relatively little about their effectiveness. Here, we used semi-structured interviews with 54 adults in eight villages to investigate whether sacred caves and taboos offer conservation benefits for cave-dwelling bats in and around Tsimanampetsotsa National Park, south-west Madagascar. Although some caves were described as sites of spiritual significance for the local communities, most interviewees (c. 76%) did not recognize their present-day sacred status. Similarly, only 22% of the interviewees recognized taboos inhibiting bat hunting and consum…

Double methylation of tRNA-U54 to 2′-O-methylthymidine (Tm) synergistically decreases immune response by Toll-like receptor 7

2018

Abstract Sensing of nucleic acids for molecular discrimination between self and non-self is a challenging task for the innate immune system. RNA acts as a potent stimulus for pattern recognition receptors including in particular human Toll-like receptor 7 (TLR7). Certain RNA modifications limit potentially harmful self-recognition of endogenous RNA. Previous studies had identified the 2′-O-methylation of guanosine 18 (Gm18) within tRNAs as an antagonist of TLR7 leading to an impaired immune response. However, human tRNALys3 was non-stimulatory despite lacking Gm18. To identify the underlying molecular principle, interferon responses of human peripheral blood mononuclear cells to differentia…

The Guanine-Based Purinergic System: The Tale of An Orphan Neuromodulation.

2016

Guanine-based purines (GBPs) have been recently proposed to be not only metabolic agents but also extracellular signaling molecules that regulate important functions in the central nervous system. In such way, GBPs-mediated neuroprotection, behavioral responses and neuronal plasticity have been broadly described in the literature. However, while a number of these functions (i.e., GBPs neurothophic effects) have been well-established, the molecular mechanisms behind these GBPs-dependent effects are still unknown. Furthermore, no plasma membrane receptors for GBPs have been described so far, thus GBPs are still considered orphan neuromodulators. Interestingly, an intricate and controversial f…

Preventive effects of guanosine on intestinal inflammation in 2, 4-dinitrobenzene sulfonic acid (DNBS)-induced colitis in rats

2018

Background: Guanosine, a guanine-based purine, is an extracellular signaling molecule exerting anti-inflammatory and antioxidative effects in several in vivo and in vitro injury models. We aimed to investigate its protective effects on 2, 4-dinitrobenzene sulfonic acid (DNBS)-induced colitis in rat. Methods: Rats were divided into five groups and colitis was induced by intracolonic instillation of DNBS (15 mg/rat). Guanosine (4 or 8 mg/kg) was administered for 6 days i.p. starting the day of the colitis induction. Body weight loss, stool consistency, colon weight/length, histological analysis, myeloperoxidase activity (MPO) and pro-inflammatory cytokine levels were assessed. Immunoblotting …

Cardiovascular toxicity of abacavir: a clinical controversy in need of a pharmacological explanation.

2017

: There is a long-lasting controversy surrounding an association between abacavir (ABC) and an increased risk of cardiovascular disease in HIV-positive patients. Although differing in their specifics, a number of published cohort studies and clinical trials support such an association, usually relating it to recent exposure to the drug, independently of traditional predisposing factors. However, other clinical trials have failed to reveal such a relation and have pointed to methodological differences to explain discrepancies. Significantly, the controversy has been fueled by the lack of a credible mechanism of action to justify the putative detrimental actions of ABC. There is a myriad of c…

The Expression of NOX From Synthetic Promoters Reveals an Important Role of the Redox Status in Regulating Secondary Metabolism of

2020

Redox cofactors play a pivotal role in primary cellular metabolism, whereas the clear link between redox status and secondary metabolism is still vague. In this study we investigated effects of redox perturbation on the production of erythromycin in Saccharopolyspora erythraea by expressing the water-forming NADH oxidase (NOX) from Streptococcus pneumonia at different levels with synthetic promoters. The expression of NOX reduced the intracellular [NADH]/[NAD+] ratio significantly in S. erythraea which resulted in an increased production of erythromycin by 19∼29% and this increment rose to 60% as more oxygen was supplied. In contrast, the lower redox ratio resulted in a decreased production…