The matrix-tolerance hypothesis: an empirical test with frogs in the Atlantic Forest

The matrix-tolerance hypothesis suggests that the most abundant species in the inter-habitat matrix would be less vulnerable to their habitat fragmentation. This model was tested with leaf-litter frogs in the Atlantic Forest where the fragmentation process is older and more severe than in the Amazon, where the model was first developed. Frog abundance data from the agricultural matrix, forest fragments and continuous forest localities were used. We found an expected negative correlation between the abundance of frogs in the matrix and their vulnerability to fragmentation, however, results varied with fragment size and species traits. Smaller fragments exhibited stronger matrix-vulnerability correlation than intermediate fragments, while no significant relation was observed for large fragments. Moreover, some species that avoid the matrix were not sensitive to a decrease in the patch size, and the opposite was also true, indicating significant differences with that expected from the model. Most of the species that use the matrix were forest species with aquatic larvae development, but those species do not necessarily respond to fragmentation or fragment size, and thus affect more intensively the strengthen of the expected relationship. Therefore, the main relationship expected by the matrix-tolerance hypothesis was observed in the Atlantic Forest; however we noted that the prediction of this hypothesis can be substantially affected by the size of the fragments, and by species traits. We propose that matrix-tolerance model should be broadened to become a more effective model, including other patch characteristics, particularly fragment size, and individual species traits (e. g., reproductive mode and habitat preference).

Transparent Fault Tolerance for Web Services based Architectures

Service-based architectures enable the development of new classes of Grid and distributed applications. One of the main capabilities provided by such systems is the dynamic and flexible integration of services, according to which services are allowed to be a part of more than one distributed system and simultaneously serve different applications. This increased flexibility in system composition makes it difficult to address classical distributed system issues such as fault-tolerance. While it is relatively easy to make an individual service fault-tolerant, improving fault-tolerance of services collaborating in multiple application scenarios is a challenging task. In this paper, we look at the issue of developing fault-tolerant service-based distributed systems, and propose an infrastructure to implement fault tolerance capabilities transparent to services.

The Role of Phytochrome in Stress Tolerance

It is well-documented that phytochromes can control plant growth and development from germination to flowering. Additionally, these photoreceptors have been shown to modulate both biotic and abiotic stress. This has led to a series of studies exploring the molecular and biochemical basis by which phytochromes modulate stresses, such as salinity, drought, high light or herbivory. Evidence for a role of phytrochromes in plant stress tolerance is explored and reviewed.

Tolerance to iron chlorosis in non-grafted quince seedlings and in pear grafted onto quince plants

Grafting is a technique that may affect plant tolerance to iron chlorosis in plants cultivated for their fruit. Therefore, the objective of this study was to evaluate the tolerance of non-grafted quince seedlings and pear grafted onto quince plants cultivated in pots with alkaline soil. The experiment was conducted in a greenhouse at the University of Cordoba, Spain, in pots (3 L) filled with alkaline soil, with one plant per pot. The treatments consisted of two genotypes, quince (Cydonia oblonga Mill) semi-woody rooted cuttings, cultivar BA29, and pear (Pyrus Communis L.), cultivar Ercolini, grafted onto quince cultivar BA29 (rootstock), and two nutrient solutions with and without iron (80 mu M Fe-EDDHA) arranged in a completely random design with eight repetitions. Each pot received 250 mL of the nutrient solution on June 3rd, 2010. Chlorophyll indirect measurements and the main stem length were evaluated for six weeks after the commencement of the treatments. During the last week, the main stem dry matter weight and the leaf total iron content were determined. It was found that grafting pear seedlings onto quince rootstock resulted in a higher tolerance to iron deficiency than when quince was not grafted. Non-grafted quince plants without iron in the nutrient solution, compared to the results with its application, showed low SPAD (Soil-Plant Analyses Development) values and resulted in plants with a lower leaf iron content and lower dry matter production; however, decreased seedling stem growth was observed only in the last week of cultivation.

Impact of maternal mild hyperglycemia on maternal care and offspring development and behavior of Wistar rats

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The development of seedlings from fragments of monoembryonic seeds as an important survival strategy for Eugenia (Myrtaceae) tree species

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Arabidopsis thaliana Uncoupling Proteins (AtUCPs): insights into gene expression during development and stress response and epigenetic regulation

Mitochondrial inner membrane uncoupling proteins (UCP) catalyze a proton conductance that dissipates the proton electrochemical gradient established by the respiratory chain, thus affecting the yield of ATP synthesis. UCPs are involved in mitochondrial energy flow regulation and have been implicated in oxidative stress tolerance. Based on the global gene expression profiling datasets available for Arabidopsis thaliana, in this review we discuss the regulation of UCP gene expression during development and in response to stress, and provide interesting insights on the possible existence of epigenetic regulation of UCP expression.

Developmental changes in cold tolerance and ability to autoresuscitate from hypothermic respiratory arrest are not linked in rats and hamsters

In adult mammals, severe hypothermia leads to respiratory and cardiac arrest, followed by death. Neonatal rats and hamsters can survive much lower body temperatures and, upon artificial rewarming, spontaneously recover from respiratory arrest (autoresuscitate), typically suffering no long-term effects. To determine developmental and species differences in cold tolerance (defined here as the temperature of respiratory arrest) and its relation to the ability to autoresuscitate, we cooled neonatal and juvenile Sprague-Dawley rats and Syrian hamsters until respiration ceased, followed by rewarming. Ventilation and heartbeat were continuously monitored. In rats, cold tolerance did not change throughout development, however the ability to autoresuscitate from hypothermic respiratory arrest did (lost between postnatal days, P, 14 and 20), suggesting that the mechanisms for maintaining breathing at low temperatures was retained throughout development while those initiating breathing on rewarming were altered. Hamsters, however, showed increased cold tolerance until P26-28 and were able to autoresuscitate into adulthood (provided the heart kept beating throughout respiratory arrest). Also, hamsters were more cold tolerant than rats. We saw no evidence of gasping to initiate breathing following respiratory arrest, contributing to the hypothesis that hypothermic respiratory arrest does not lead to anoxia. (C) 2012 Elsevier B.V. All rights reserved.

Effect of phenobarbital on inducing insecticide tolerance and esterase changes in Aedes aegypti (Diptera: Culicidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Tolerance to water deficiency between two soybean cultivars: transgenic versus conventional

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Prospecting sugarcane genes involved in aluminum tolerance

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Mapping QTLs for aluminum tolerance in maize

Aluminum toxicity is one of the major constraints for plant development in acid soils, limiting food production in many countries. Cultivars genetically adapted to acid soils may offer an environmental compatible solution, providing a sustainable agriculture system. The aim of this work was to identify genomic regions associated with Al tolerance in maize, and to quantify the genetic effects on the phenotypic variation. A population of 168 F-3:4 families derived from a cross between two contrasting maize inbred lines for Al tolerance was evaluated using the NSRL and RSRL parameters in nutrient solution containing toxic level of aluminum. Variance analyses indicated that the NSRL was the most reliable phenotypic index to measure Al tolerance in the population, being used for further QTL mapping analysis. RFLP and SSR markers were selected for bulked segregant analysis, and additional SSR markers, flanking the polymorphisms of interest, were chosen in order to saturate the putative target regions. Seven linkage groups were constructed using 17 RFLP and 34 SSR markers. Five QTLs were mapped on chromosomes 2, 6 and 8, explaining 60% of the phenotypic variation. QTL(4) and marker umc043 were located on chromosomes 8 and 5, close to genes encoding for enzymes involved in the organic acids synthesis pathways, a widely proposed mechanism for Al tolerance in plants. QTL(2) was mapped in the same region as Alm2, also associated with Al tolerance in maize. In addition, dominant and additive effects were important in the control of this trait in maize.

Early development and nutrition of cover crop species as affected by soil compaction

A good cover crop should have a vigorous early development and a high potential for nutrient uptake that can be made available to the next crop. In tropical areas with relatively dry winters drought tolerance is also very important. An experiment was conducted to evaluate the early development and nutrition of six species used as cover crops as affected by sub-superficial compaction of the soil. The plants (oats, pigeon pea, pearl millet, black mucuna, grain sorghum, and blue lupin) were grown in pots filled with soil subjected to different subsurface compaction levels (bulk densities of 1.12, 1.16, and 1.60 mg m(-3)) for 39 days. The pots had an internal diameter of 10 cm and were 33.5 cm deep. Grasses were more sensitive to soil compaction than leguminous plants during the initial development. Irrespective of compaction rates, pearl millet and grain sorghum were more efficient in recycling nutrients. These two species proved to be more appropriate as cover crops in tropical regions with dry winters, especially if planted shortly before spring.

Effect of maternal obesity on diabetes development in adult rat offspring

This study aimed to evaluate whether maternal obesity leads to the onset of diabetes in adult Wistar rats offspring. MSG solution neonatally administration induced obesity in rats (F(1)MSG group, n = 30); and saline solution was also administrated to control rats (F1CON group, n = 13). In 3rd month of age, both control and MS G groups were mated for offspring (generation FA named as F2CON, n = 28 and F(2)MSG groups, n = 15; and so both generations were studied until 7th month of life. Lee Index was measured for experimental obesity validation from 5th to 7th month. Glycemia was weekly determined during pregnancy and monthly from 3rd to 7th month. In the end of experimental period all rats were submitted to oral glucose tolerance test (OGTT), with estimation of total area under the curve (AUC); and insulin tolerance test (ITT). Rats were then anesthetized and killed. Data were statistically analyzed with significance level of p < 0.05. Lee Index has confirmed obesity in all MSG rats. Glycemic levels comparisons between generations showed significant maternal interference in control and MSG groups. OGTT analysis showed higher glycemia in obese rats (F(1)MSG) and their offspring (F(2)MSG) as compared to their respective controls; and MSG groups increased AUC from OGTT. As regards ITT, F(2)MSG showed higher glycemia at 30 and 120 min, suggesting a delay of insulin action decreasing. Although glucose intolerance and insulin resistance clinical conditions represent as a factors for type 2 Diabetes mellitus development, this experimental model proposal was not efficient to induce type 2 Diabetes mellitus, but for obesity developing, glucose intolerance and insulin resistance in successive generations of rats. (c) 2007 Elsevier B.V. All rights reserved.