Spatial-temporal patterns of functional feeding groups in mountain streams of Córdoba, Argentina

La estructura trófica de las comunidades bentónicas está condicionada por la disponibilidad de recursos alimenticios, los cuales a su vez varían en función del tamaño del arroyo, la cobertura y el tipo de sustrato. El objetivo de este trabajo fue analizar la distribución de los grupos funcionales alimentarios de macroinvertebrados en diferentes hábitats de arroyos serranos de la Provincia de Córdoba (Argentina) y examinar las variables ambientales que explican esta distribución en la escala de hábitat. Se consideraron cuatro arroyos en dos períodos hidrológicos (alto y bajo caudal) en los cuales se recolectaron tres muestras de bentos en rabiones y correderas de sustrato fino y grueso. Los colectores de depósito fueron dominantes en la mayoría de los hábitats, arroyos y períodos hidrológicos, excepto en los rabiones durante el periodo de bajo caudal en el cual predominaron los colectores filtradores. Las variables más importantes que explicaron la distribución de los grupos funcionales a escala de hábitat fueron la velocidad de la corriente, el tipo de sustrato y la abundancia de macroalgas y de ramas y hojas. La abundancia de los grupos funcionales varió en función de los arroyos, de los distintos hábitats y de los periodos hidrológicos. La dominancia de los colectores demuestra la importancia del rol de este grupo funcional y que el detrito fino sería el recurso alimenticio principal en estos ecosistemas lóticos. La fenología y la forma de vida de las especies y la cantidad y calidad de materia orgánica retenida en cada hábitat explicarían el patrón espacio-temporal de variación de los grupos funcionales alimentarios.Trophic structure of benthic communities is influenced by the availability of food resources which indeed may be conditioned by stream size, shading and substrate. This study aims to analyze the distribution of macroinvertebrate Functional Feeding Groups in different habitats of mountain streams (Córdoba, Argentina) and to assess the environmental variables conditioning this distribution at the habitat level. Four streams were sampled in two hydrological periods (high and low discharge) and three benthic samples were taken in riffles and runs of coarse and fine substrate. Gathering collectors were dominant in most of the habitats, streams and periods except in riffles during the low water period in which filtering collectors dominated. At the habitat level, current velocity, substrate, abundance of macroalgae and twigs and leaves were the most important variables explaining functional feeding group distribution. Functional feeding group abundances varied in relation to the stream, the hydrological period and the habitat. The dominance of collectors demonstrates the importance of the role of this functional group and that fine detritus is the main food resource in these lotic ecosystems. The phenology and life history of the species, and the amount and type of organic matter retained in each habitat may explain the observed spatial-temporal patterns

El bentos y su fracción derivante: composición y estructura en un arroyo regulado (Achiras, Córdoba)

Flow regulation modifies the physico-chemical conditions of the fluvial system and consequently its biota. The aim of this study was to analyze the composition and structure of benthic and drift, upstream and downstream of the Achiras dam before and after construction. Sampling of benthos (Surber nets, 0.09 m2 and 300 μ) and drift (nets 1 m long, 300 μ and 0.0192 m2) were performed in high water and low water periods. The organisms were identified to the lowest possible taxonomic level and benthic Feeding Functional Groups were identified. Density, taxonomic richness, Shannon diversity and evenness for benthos and drift were calculated. Data were compared by three-way ANOVAs. The structure of both assemblages varied spatially and temporally. Benthic community showed a total of 110 taxa, corresponding to 8 phyla, while drift assemblage 55 taxa corresponding to 6 phyla. In both assemblages, the phylum Arthropoda was the most abundant. In the site below the dam and in the post-construction period, the benthos richness was greater, while drift evenness exhibited the highest value at the site below the dam during low water period. The filtering collectors and scrapers showed significant differences between year, site and hydrological period. The chironomids Tanytarsus sp. and Rheotanytarsus sp. were the most abundant among collectors while filtering Camelobaetidius penai and Stenophysa sp. among the scrapers. Data obtained in this study show that both data of benthic structure and its drifting fraction as the GFA data would indicate no significant changes attributable to dam effect. Longer studies would be required since in regulated systems most ecological changes happen more slowly than observed immediately.Facultad de Ciencias Naturales y Muse

El bentos y su fracción derivante: composición y estructura en un arroyo regulado (Achiras, Córdoba)

Flow regulation modifies the physico-chemical conditions of the fluvial system and consequently its biota. The aim of this study was to analyze the composition and structure of benthic and drift, upstream and downstream of the Achiras dam before and after construction. Sampling of benthos (Surber nets, 0.09 m2 and 300 μ) and drift (nets 1 m long, 300 μ and 0.0192 m2) were performed in high water and low water periods. The organisms were identified to the lowest possible taxonomic level and benthic Feeding Functional Groups were identified. Density, taxonomic richness, Shannon diversity and evenness for benthos and drift were calculated. Data were compared by three-way ANOVAs. The structure of both assemblages varied spatially and temporally. Benthic community showed a total of 110 taxa, corresponding to 8 phyla, while drift assemblage 55 taxa corresponding to 6 phyla. In both assemblages, the phylum Arthropoda was the most abundant. In the site below the dam and in the post-construction period, the benthos richness was greater, while drift evenness exhibited the highest value at the site below the dam during low water period. The filtering collectors and scrapers showed significant differences between year, site and hydrological period. The chironomids Tanytarsus sp. and Rheotanytarsus sp. were the most abundant among collectors while filtering Camelobaetidius penai and Stenophysa sp. among the scrapers. Data obtained in this study show that both data of benthic structure and its drifting fraction as the GFA data would indicate no significant changes attributable to dam effect. Longer studies would be required since in regulated systems most ecological changes happen more slowly than observed immediately.Facultad de Ciencias Naturales y Muse

El bentos y su fracción derivante: composición y estructura en un arroyo regulado (Achiras, Córdoba)

Flow regulation modifies the physico-chemical conditions of the fluvial system and consequently its biota. The aim of this study was to analyze the composition and structure of benthic and drift, upstream and downstream of the Achiras dam before and after construction. Sampling of benthos (Surber nets, 0.09 m2 and 300 μ) and drift (nets 1 m long, 300 μ and 0.0192 m2) were performed in high water and low water periods. The organisms were identified to the lowest possible taxonomic level and benthic Feeding Functional Groups were identified. Density, taxonomic richness, Shannon diversity and evenness for benthos and drift were calculated. Data were compared by three-way ANOVAs. The structure of both assemblages varied spatially and temporally. Benthic community showed a total of 110 taxa, corresponding to 8 phyla, while drift assemblage 55 taxa corresponding to 6 phyla. In both assemblages, the phylum Arthropoda was the most abundant. In the site below the dam and in the post-construction period, the benthos richness was greater, while drift evenness exhibited the highest value at the site below the dam during low water period. The filtering collectors and scrapers showed significant differences between year, site and hydrological period. The chironomids Tanytarsus sp. and Rheotanytarsus sp. were the most abundant among collectors while filtering Camelobaetidius penai and Stenophysa sp. among the scrapers. Data obtained in this study show that both data of benthic structure and its drifting fraction as the GFA data would indicate no significant changes attributable to dam effect. Longer studies would be required since in regulated systems most ecological changes happen more slowly than observed immediately.Facultad de Ciencias Naturales y Muse

Rac1 and Rac3 GTPases Regulate the Development of Hilar Mossy Cells by Affecting the Migration of Their Precursors to the Hilus

We have previously shown that double deletion of the genes for Rac1 and Rac3 GTPases during neuronal development affects late developmental events that perturb the circuitry of the hippocampus, with ensuing epileptic phenotype. These effects include a defect in mossy cells, the major class of excitatory neurons of the hilus. Here, we have addressed the mechanisms that affect the loss of hilar mossy cells in the dorsal hippocampus of mice depleted of the two Rac GTPases. Quantification showed that the loss of mossy cells was evident already at postnatal day 8, soon after these cells become identifiable by a specific marker in the dorsal hilus. Comparative analysis of the hilar region from control and double mutant mice revealed that synaptogenesis was affected in the double mutants, with strongly reduced presynaptic input from dentate granule cells. We found that apoptosis was equally low in the hippocampus of both control and double knockout mice. Labelling with bromodeoxyuridine at embryonic day 12.5 showed no evident difference in the proliferation of neuronal precursors in the hippocampal primordium, while differences in the number of bromodeoxyuridine-labelled cells in the developing hilus revealed a defect in the migration of immature, developing mossy cells in the brain of double knockout mice. Overall, our data show that Rac1 and Rac3 GTPases participate in the normal development of hilar mossy cells, and indicate that they are involved in the regulation of the migration of the mossy cell precursor by preventing their arrival to the dorsal hilus

Promises of stem cell therapy for retinal degenerative diseases

With the development of stem cell technology, stem cell-based therapy for retinal degeneration has been proposed to restore the visual function. Many animal studies and some clinical trials have shown encouraging results of stem cell-based therapy in retinal degenerative diseases. While stem cell-based therapy is a promising strategy to replace damaged retinal cells and ultimately cure retinal degeneration, there are several important challenges which need to be overcome before stem cell technology can be applied widely in clinical settings. In this review, different types of donor cell origins used in retinal treatments, potential target cell types for therapy, methods of stem cell delivery to the eye, assessments of potential risks in stem cell therapy, as well as future developments of retinal stem cells therapy, will be discussed

Prevalence of Staphylococcus spp. nasal colonization among doctors of podiatric medicine and associated risk factors in Spain

Abstract Background This study aimed to estimate the prevalence of methicillin-susceptible and -resistant Staphylococcus aureus (MSSA and MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE) nasopharyngeal carriage among Doctors of Podiatric Medicine (Podiatrists) and to determine the potential risk factors. Methods A cross-sectional study was carried out in 2016–2017 among 239 podiatrists in Spain. The presence of MSSA, MRSA, and MRSE was determined by microbiological analysis of nasal exudate and antimicrobial susceptibility was determined. Each podiatrist completed a questionnaire. The questionnaire comprised various parameters such as sex, age, podiatry experience duration, underlying diseases, prior antibiotic treatment, hospitalization during the last year, and use of a protective mask, an aspiration system, or gloves. Results The prevalence of MSSA, MRSA, and MRSE was 23.0%, 1.3%, and 23.8%, respectively. The MSSA prevalence was higher among podiatrists who did not use an aspiration system (32.3%) compared to those who did (19.3%; p = 0.0305), and among podiatrists with respiratory diseases (36.8%) compared to those without (20.8%; p = 0.0272). The MRSE prevalence was higher among men (33.7%) compared to women (8.6%; p = 0.0089), podiatrists aged ≥50 (38.5%) compared to ≤35 (17.8%; p = 0.0101), and podiatrists with ≥15 (39.3%) compared to ≤5 years of podiatry experience (12.5%; p = 0.0015). Among the S. aureus strains, 84.5% were resistant to penicillin, 22.4% to erythromycin, 20.7% to clindamycin, and 12.7% to mupirocin. The MRSE strains were resistant to penicillin (93.0%), erythromycin (78.9%), and mupirocin (73.7%). Conclusions The prevalence of S. aureus and S. epidermidis nasal carriage is low among Spanish podiatrists compared to other health professionals