Oxidative phosphorylation efficiency, proton conductance and reactive oxygen species production of liver mitochondria correlates with body mass in frogs

ody size is a central biological parameter affecting most biological processes (especially energetics) and mitochondria is a key organelle controlling metabolism and is also the cell's main source of chemical energy. However, the link between body size and mitochondrial function is still unclear, especially in ectotherms. In this study, we investigated several parameters of mitochondrial bioenergetics in the liver of three closely related species of frogs (the common frog Rana temporaria, the marsh frog Pelophylax ridibundus and the bull frog Lithobates catesbeiana). These particular species were chosen due to their differences in adult body mass. We found that the mitochondrial coupling efficiency was markedly increased with animal size, which lead to a higher ATP production (+70%) in the larger frogs (L. catesbeiana) compared to the smaller frogs (R. temporaria). This was essentially driven by a strong negative dependence of mitochondrial proton conductance on body mass. Liver mitochondria from the larger frogs (L. catesbeiana) displayed 50% of the proton conductance of mitochondria from the smaller frogs (R. temporaria). Contrary to our prediction, the low mitochondrial proton conductance measured in L. catesbeiana was not associated with higher radical oxygen species production. Instead, liver mitochondria from the larger individuals produced significantly lower radical oxygen species than those from the smaller frogs. Collectively, the data shows that key bioenergetics parameters of mitochondria (proton leak, ATP production efficiency and radical oxygen species production) are correlated with body mass in frogs. This research expands our understanding of the relationship between mitochondrial function and the evolution of allometric scaling in ectotherms

Truthmaking as Alethic-Fact Building

Explora las concepciones de los "hacedores de verdad" que utilizan el concepto de construcción de hechos aléticos. Se discierne entre características deseables de estas concepciones y se rechazan las indeseables. Se formula, además, una versión de este tipo de teorías y se la defiende frente a diversos argumentos.The thesis explores alethic-fact building conceptions of truthmaking, discerning which features of them are desirable, and arguing against the non-desirable. It formulates a general sketch of a view called alethic-fact building. It responds to arguments against alethic-fact grounding

Improvement of accession distinctiveness as an added value to the global worth of the yam (Dioscorea spp) genebank

Open Access JournalMisidentification of accessions is a common problem in genebanks. Along the years, mistakes accumulate and this is particularly true when dealing with a large number of accessions requiring annual regeneration. Human errors such as mislabeling or misreading and material mix up during planting or storage are the main causes for misidentification of accessions. The international collection of yam, maintained at IITA, has accumulated ‘non true to type’ accessions along the years. In the present study, 53 morphological descriptors were used to detect uniformity of individuals within accessions of the yam gene bank collection i.e. agro morphological mismatch between individual plants of the same accession. Based on a similarity matrix, individual pairs with less than 0.90 similarity coefficients, which varies in six descriptors and more, were considered as distinct and mismatched, whereas those that had similarity coefficients greater than or equal to 0.90 were considered as clones from the same parent. Overall, 20.60% of the total 3156 accessions were found not true to type i.e., misidentified individuals. The descriptive analysis shows that morphological traits like distance between lobes, upward folding of leaf along main vein, young stem color, old stem color, leaf shape, leaf density and plant vigor are the most discriminative descriptors for individual identification within accession. Some other traits were also found species specific and they may aid in distinguishing misidentifications between species

Field collection, preservation and large scale DNA extraction procedures for cassava (Manihot esculenta Crantz.)

Some genetic studies using molecular methods such as diversity assessment or marker-assisted selection require collection of a large number of samples from fields located in the vicinity or in remote areas, followed by isolation of good quality DNA in a short time span. In the present study, different tissue preservation methods were compared for subsequent DNA extraction using a modified CTAB method in two 96-well plates, following grinding of leaf tissues with a GenoGrinder 2000. We found that preservation of leaf tissues in NaCl-CTAB-azide buffer (as described in Rogstad, 1992) at 4°C is a better storage procedure than preservation at -20°C to obtain good quality DNA. Comparison of DNA extraction with or without use of phenol revealed that the quality of DNA was not drastically affected when non-phenol extraction protocol was used and did not affect PCR amplification. Thus, the recommended DNA extraction procedure allowed us to process 192 samples per day at a cost of $0.80 per sample, with an average yield of 1.8  g, suitable for both PCR and genotyping

Modeling and evaluating human-mediated dispersal mechanisms at landscape scale: a study of road network and invasion parameters for Lasius neglectus ants invasive species

International audienceAnts invasive species Biological invasions are considered, right after climate and land use changes, to be one of the principal causes of biodiversity erosion. This phenomenon is related to global change, since climate and land use modifications affect environmental conditions, and are partly responsible for the introduction and proliferation of exotic species into new environments. Furthermore, human-mediated dispersal acts as a dispersal vector for many exotic species, both at the introduction and secondary spread stages. On the one hand, introduction stage is a consequence of human-mediated long distance dispersal, due to human activities (and especially commercial exchanges), and is known to happen at large spatial scales (continental or global scales). On the other hand, secondary spread occurs at smaller spatial and time scales (like landscape scale) and can be provided by natural and human-mediated dispersal mechanisms, once the introduction had brought the exotic species into a novel environment, and after it has succeeded in establishing itself (i.e. survive and reproduce). Few works have pointed out the role of these second stages in small-scale invasive species spread. And yet, a lot of invasive species are susceptible to be partly or completely dispersed by local human processes happening at local spatial and time scales (materials transportation, for example). The lack of consideration for this potential important mode of dispersal seems to be the consequence of multiple factors: human-mediated dispersal is generally considered as a long distance dispersal process, more responsible for invasive species introduction than for secondary spread, it is difficult to qualify and quantify this mode of dispersal because of the multiplicity of potentially involved human activities being its vector, for a given organism that can disperse naturally, it is complicated to distinguish between natural and human-mediated dispersal, as they may occur at similar scale.In this paper, we study the spreading pattern of Lasius neglectus, an invasive ant species originated from Anatoly, which invaded Europe in the last decades and which is currently present in the Rhône valley, in France. We present a numerical model enabling the estimation of multiple human-mediated dispersal parameters, based on ground-truth sampling and minimizing a priori

Pathogenesis of napkin dermatitis: part I

A dermatite da área da fralda irritativa primária é a dermatite da área da fralda mais prevalente, sendo provavelmente a afecção cutânea mais freqüente na primeira infância, constituindo fonte significativa de desconforto para a criança. O uso da fralda ocasiona aumento da temperatura e da umidade locais. Há conseqüente maceração da pele, que se torna mais susceptível à irritação ocasionada pelo contato prolongado da urina e das fezes com a pele da região coberta pelas fraldas. Freqüentemente surge infecção secundária por Candida ou por bactérias como Bacillos faecallis, Proteus, Pseudomonas, Staphylococcus e Streptococcus. O uso de pós, óleos, sabões e pomadas irritantes agravam o quadro clínico. Diante disso, é importante que se conheça a fisiopatologia da doença para que se possa fazer correta prevenção e tratamento apropriado.Irritant contact dermatitis is the most prevalent diaper dermatitis and, probably, the most common cause of skin disease in infancy. The wearing of diaper leads to overhydration, increased local temperature and humidity. Constant maceration and prolonged contact with urine and stools makes the skin under the diaper more susceptible. There is often secondary infection due to Candida or bacteria, such as Bacillus faecallis, Proteus, Pseudomonas, Staphylococcus e Streptococcus. Oils, soaps, powders and ointments can be irritants and aggravate the rash. It is important to know the pathophysiology of the disease for appropriate treatment and preventio

Applying forecasting Revenue Management techniques to enrolment management in a university centre

Revenue Management methodology is shown to be an innovative application for fixed capacity firms or service entities which require a management system that supports pricing and inventory decision-making. The present research study takes one of the elements of this philosophy – demand forecasting and estimation - as a theoretical basis and applies it to the case study. The aim is to obtain the predicted demand of enrolments in each academic year. This will support the improvement and optimisation of the operations related to capacity management in a university centr