Biology subjects

Alvarez, D.

Publications and source records attributed to Alvarez, D..

22 records · Page 2Linked to original sources

bioRxiv2019

Using Unmanned Aerial Vehicles (UAV) for free-roaming dog population size estimation

Population size estimation is performed for several reasons including disease surveillance and control, for example to design adequate control strategies such as vaccination programs or to estimate a vaccination campaign coverage. In this study, we aimed at assessing the benefits and challenges of using Unmanned Aerial Vehicles (UAV) to estimate the size of free-roaming domestic dog (FRDD) populations and compare the results with two regularly used methods for population estimations: a Bayesian statistical model based on capture-recapture data and the human:dog ratio estimation. Three studies sites of one square kilometer were selected in Peten department, Guatemala. UAV flight were conducted twice during two consecutive days per study site. The UAVs camera was set to regularly take pictures and cover the entire surface of the selected areas. A door-to-door survey was conducted in the same areas, all available dogs were marked with a collar and owner were interviewed. Simultaneously to the UAVs flight, transect walks were performed and the number of collared and non-collared dogs were recorded. Data collected during the interviews and the number of dogs counted during the transect walks informed a Bayesian statistical model. The number of dogs counted on the UAVs pictures and the estimates given by the Bayesian statistical model, as well as the estimates derived from using a 5:1 human:dog ratio were compared to dog census data. FRDD could be detected using the UAVs method. However, the method lacked of sensitivity, which could be overcome by choosing the flight timing and the study area wisely, or using infrared camera or automatic detection of the dogs. We also suggest to combine UAV and capture-recapture methods to obtain reliable FRDD population size estimated. This publication may provide helpful directions to design dog population size estimation methods using UAV.

ecology↗

bioRxiv2019

Anatomically remote education of B cells is required for colonic health

Mucosa-associated lymphoid tissues contain roughly 80% of all immune cells and produce virtually all of the bodys IgA1-3. Although the majority of IgA-secreting cells educated within a mucosal site home back to the same anatomic region, some cells are also found in distant mucosal tissues2-6. These observations underlie the notion of a common mucosal immune system, which holds that anatomically unrelated mucosal sites are functionally connected by a shared immune system2,3. However, the ontological basis of this separation between site of immune education and functionality has remained elusive. Here we show that mice lacking Peyers patches (PPs)--small-intestinal lymphoid tissue covered by antigen-sampling M cells--have no immunologic defect in the small-intestinal lamina propria. Surprisingly, the primary immunological abnormality in PP-deficient mice was a reduction in colonic B cells, including plasmablasts but not plasma cells. Adoptive transfer experiments conclusively demonstrated that PP-derived cells preferentially give rise to colonic--but not small-intestinal--B cells and plasmablasts. Finally, these PP-derived colonic B cells were critical for restraining colonic inflammation. Thus, PPs bridge the small-intestinal and colonic immune systems and provide a clear example of immune education being required in an anatomic compartment distinct from the effector site. Our findings, which highlight that the majority of fecal IgA is produced by colonic plasmablasts that originate from PPs, will help inform design of mucosal vaccines.

immunology↗

bioRxiv2019

Bioactive compounds from Chrysosporium multifidum, a fungus isolated from Hermetia illucens gut microbiota

The gut microbiota of insects contains a wide range of organisms that protect them against the attack of pathogens by releasing various types of bioactive compounds. In the present study, we report the isolation and identification of the fungus Chrysosporium multifidum as a component of the microbiota from the larval gut of Hermetia illucens. Extract from the broth culture of C. multifidum showed moderate activity on a strain of methicillin-resistant Staphylococcus aureus (MRSA). The bioguided isolation of the extract resulted in the characterization of six -pyrone derivatives (1-6) and one diketopiperazines (7), among them 5,6-dihydro-4-methoxy-6-(1-oxopentyl)-2H-pyran-2-one (4) showed the best activity (IC50 = 11.4 {+/-} 0.7 {micro}g/ml and MIC = 62.5 g/ml).

microbiology↗

bioRxiv2017

T helper cells modulate intestinal stem cell renewal and differentiation

In the small intestine, a cellular niche of diverse accessory cell types supports the rapid generation of mature epithelial cell types through self-renewal, proliferation, and differentiation of intestinal stem cells (ISCs). However, not much is known about interactions between immune cells and ISCs, and it is unclear if and how immune cell dynamics affect eventual ISC fate or the balance between self-renewal and differentiation. Here, we used single-cell RNA-seq (scRNA-Seq) of intestinal epithelial cells (IECs) to identify new mechanisms for ISC-immune cell interactions. Surprisingly, MHC class II (MHCII) is enriched in two distinct subsets of Lgr5+ crypt base columnar ISCs, which are also distinguished by higher proliferation rates. Using co-culture of T cells with intestinal organoids, cytokine stimulations, and in vivo mouse models, we confirm that CD4+ T helper (Th) cells communicate with ISCs and affect their differentiation, in a manner specific to the Th subtypes and their signature cytokines and dependent on MHCII expression by ISCs. Specific inducible knockout of MHCII in intestinal epithelial cells in mice in vivo results in expansion of the ISC pool. Mice lacking T cells have expanded ISC pools, whereas specific depletion of Treg cells in vivo results in substantial reduction of ISC numbers. Our findings show that interactions between Th cells and ISCs mediated via MHCII expressed in intestinal epithelial stem cells help orchestrate tissue-wide responses to external signals.

immunology↗