Microorganismos del suelo y sustentabilidad de los agroecocistemas

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Microorganismos del suelo y sustentabilidad de los agroecocistemas

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Evaluación de comunidades microbianas edáficas mediante CLPP : estandarización de una técnica de laboratorio para reemplazar microplacas comerciales

129-136Variation of soil-microbial communities are good bioindicators of human impacts in soils, such as different soils management or contamination. Considering that traditional methods of isolation and taxonomic analysis do not consider the functionality of the microbial community, Community-Level Physiological Profiles (CLPP) emerged as a complementary methodology to study microbial communities. Several studies have shown that Biolog® EcoPlates® are very useful for determining physiological differences between communities from different samples. However, commercial microplates have some disadvantages which led us to the idea of replacing them by microplates prepared in the laboratory (Laboratory's). Here, we compared both types of microplates using soil samples from a bioremediation assay. We compared a) the average well color development for each sample, b) the averages of absorbance values for each type of microplate, c) Principal Components, and d) Shannon-Weaver's diversity index (H). Although Laboratory's showed significantly lower Average absorbance values than EcoPlates®, the principal component analysis and diversity index did not differ between types of microplates. In conclusion, both types of microplates showed a relatively similar ability to detect differences in the CLPP of the treatments studied. Consequently, microplates prepared in laboratory are a reliable and economical tool to study the physiology of soil microbial communities

Evaluación de comunidades microbianas edáficas mediante CLPP : estandarización de una técnica de laboratorio para reemplazar microplacas comerciales

129-136Variation of soil-microbial communities are good bioindicators of human impacts in soils, such as different soils management or contamination. Considering that traditional methods of isolation and taxonomic analysis do not consider the functionality of the microbial community, Community-Level Physiological Profiles (CLPP) emerged as a complementary methodology to study microbial communities. Several studies have shown that Biolog® EcoPlates® are very useful for determining physiological differences between communities from different samples. However, commercial microplates have some disadvantages which led us to the idea of replacing them by microplates prepared in the laboratory (Laboratory's). Here, we compared both types of microplates using soil samples from a bioremediation assay. We compared a) the average well color development for each sample, b) the averages of absorbance values for each type of microplate, c) Principal Components, and d) Shannon-Weaver's diversity index (H). Although Laboratory's showed significantly lower Average absorbance values than EcoPlates®, the principal component analysis and diversity index did not differ between types of microplates. In conclusion, both types of microplates showed a relatively similar ability to detect differences in the CLPP of the treatments studied. Consequently, microplates prepared in laboratory are a reliable and economical tool to study the physiology of soil microbial communities

Micorrizas arbusculares : Asociaciones simbióticas e indicadores de calidad ambiental en sistemas de cultivos extensivos

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Micorrizas arbusculares : Asociaciones simbióticas e indicadores de calidad ambiental en sistemas de cultivos extensivos

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Propiedades microbiológicas en un suelo de la Patagonia Argentina bajo la influencia de diferentes especies forestales

191-197In forest systems, leaf litter is usually the main source of nutrients for the vegetation and microorganisms. Leaf litter composition may vary according to the biomass and quality of the materials produced by different species. Tree roots affect the development and activity of microflora. The aim of this study was to evaluate the influence of two implanted tree species, with different composition of plant residues, on the soil characteristics. The soil is classified as an Andisol and is located in the Trevelín Forest Station, Chubut, Argentina, Lat. 43° S, Long 71°31' West. The samples were extracted from the surface soil of two forest plots with a dominant species each: Radiata Pine (Pinus radiata D. Don.) and European Oak (Quercus robur). The following analytical determinations were carried out on soil samples: organic carbon, microbial respiration, deshydrogenase activity, microbial count (bacterial communities, amilolytic, actinomyces and fungi) as well as the functional diversity of associated microbial communities. The Shannon-Weaver index (H) was calculated. The soil under Oak trees showed the highest values of microbial respiration, organic carbon and amilolytic and bacterial community counts. No significant differences were found in deshydrogenase activity, actinomyces and fungi counts between species. The principal component analysis showed significant variations in the physiology of microbial communities associated with these two tree species. The microorganism H diversity index was significantly greater for Pine. Plants residues of broadleaf species such as Oak have lower contents of recalcitrant substances than conifer species, and this fact, associated with the higher development of total and amylolytic bacteria, could result in an increase in the decomposition of plant residues in the soil and in higher organic carbon and microbial respiration values

Worth the ‘EEfRT’? The Effort Expenditure for Rewards Task as an Objective Measure of Motivation and Anhedonia

Background: Of the putative psychopathological endophenotypes in major depressive disorder (MDD), the anhedonic subtype is particularly well supported. Anhedonia is generally assumed to reflect aberrant motivation and reward responsivity. However, research has been limited by a lack of objective measures of reward motivation. We present the Effort-Expenditure for Rewards Task (EEfRT or ‘‘effort’’), a novel behavioral paradigm as a means of exploring effort-based decision-making in humans. Using the EEfRT, we test the hypothesis that effort-based decision-making is related to trait anhedonia. Methods/Results: 61 undergraduate students participated in the experiment. Subjects completed self-report measures of mood and trait anhedonia, and completed the EEfRT. Across multiple analyses, we found a significant inverse relationship between anhedonia and willingness to expend effort for rewards. Conclusions: These findings suggest that anhedonia is specifically associated with decreased motivation for rewards, and provide initial validation for the EEfRT as a laboratory-based behavioral measure of reward motivation and effort-base

Dental Health and Mortality in People With End-Stage Kidney Disease Treated With Hemodialysis: A Multinational Cohort Study

Background Dental disease is more extensive in adults with chronic kidney disease, but whether dental health and behaviors are associated with survival in the setting of hemodialysis is unknown. Study Design Prospective multinational cohort. Setting & Participants 4,205 adults treated with long-term hemodialysis, 2010 to 2012 (Oral Diseases in Hemodialysis [ORAL-D] Study). Predictors Dental health as assessed by a standardized dental examination using World Health Organization guidelines and personal oral care, including edentulousness; decayed, missing, and filled teeth index; teeth brushing and flossing; and dental health consultation. Outcomes All-cause and cardiovascular mortality at 12 months after dental assessment. Measurements Multivariable-adjusted Cox proportional hazards regression models fitted with shared frailty to account for clustering of mortality risk within countries. Results During a mean follow-up of 22.1 months, 942 deaths occurred, including 477 cardiovascular deaths. Edentulousness (adjusted HR, 1.29; 95% CI, 1.10-1.51) and decayed, missing, or filled teeth score ≥ 14 (adjusted HR, 1.70; 95% CI, 1.33-2.17) were associated with early all-cause mortality, while dental flossing, using mouthwash, brushing teeth daily, spending at least 2 minutes on oral hygiene daily, changing a toothbrush at least every 3 months, and visiting a dentist within the past 6 months (adjusted HRs of 0.52 [95% CI, 0.32-0.85], 0.79 [95% CI, 0.64-0.97], 0.76 [95% CI, 0.58-0.99], 0.84 [95% CI, 0.71-0.99], 0.79 [95% CI, 0.65-0.95], and 0.79 [95% CI, 0.65-0.96], respectively) were associated with better survival. Results for cardiovascular mortality were similar. Limitations Convenience sample of clinics. Conclusions In adults treated with hemodialysis, poorer dental health was associated with early death, whereas preventive dental health practices were associated with longer survival

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified