Isolation of microsatellites from an enriched genomic library of the plant-parasitic nematode <Emphasis Type="Italic">Meloidogyne incognita</Emphasis> and their detection in other root-knot nematode species

The root-knot nematode Meloidogyne incognita is a polyphagous pest distributed from temperate to tropical regions. However, the lack of suitable markers leads to a poor knowledge of its population genetic structure and colonization process. Here we describe the first characterization of 15 microsatellite loci from this nematode, that were developed from an enriched genomic library. Although the variability of these microsatellites was generally low, three of them exhibited a significant level of intrapopulation polymorphism, with three to seven alleles detected. The observed and expected heterozygosities ranged from 0.025 to 0.385 and from 0.024 to 0.779, respectively. Thus, these new microsatellite markers have potential value for the implementation of genotyping experiments in this nematode. Furthermore, successful cross-amplification of the variable microsatellite loci in seven other Meloidogyne species provides the opportunity of using these markers for population genetic studies in these damaging plant-parasitic nematodes.     

Mitochondrial pathophysiology, reactive oxygen species, and cardiovascular diseases.

This article discusses mitochondrial pathophysiology, reactive oxygen species, and cardiovascular diseases. Mitochondrial respiratory chains are responsible for energy metabolism/ATP production through the tricyclic antidepressant cycle, coupling of oxidative phosphorylation, and electron transfer. The mitochondrion produces reactive oxygen species as "side products" of respiration. The mitochondrial derived reactive oxygen species is involved in the pathogenesis of various clinical disorders including heart failure, hypoxia, ischemia/reperfusion injury, diabetes, neurodegenerative diseases, and the physiologic process of aging. Observational and mechanistical studies of these pathologic roles of mitochondria are discussed in depth in this article.     

An empirical bayes estimator of seismic events using wavelet packet bases

An empirical Bayes (EB) estimator is constructed to denoise a time series containing quarry blasts in New England. This estimator is portable and can be used more generally to denoise seismic events. The EB estimator uses adaptive wavelet packet analysis (WPA) for transformation selection via an EB approximation to the standard entropy functional. We compare this basis selection method to the discrete wavelet transform (DWT) and best basis selection via Stein’s unbiased risk estimator (SURE). The relation of sparsity of representation to quality of estimation over a range of signal-to-noiserations (SNR) for synthetic quarry blast events is demonstrated. For functions with sparse representations, we have found that, at moderate SNR, WPA significantly out performs DWT. The EB best basis performs similarly to SURE best basis, thereby lending credence to the EB method. Finally, we compare DWT and WPA. methods for denoising quarry blast events recorded in New England.     

Trophic control of bud break in peach (Prunus persica) trees: a possible role of hexoses

Vegetative buds of peach (Prunus persica L. Batsch.) trees act as strong sinks and their bud break capacity can be profoundly affected by carbohydrate availability during the rest period (November-February). Analysis of xylem sap revealed seasonal changes in concentrations of sorbitol and hexoses (glucose and fructose). Sorbitol concentrations decreased and hexose concentrations increased with increasing bud break capacity. Sucrose concentration in xylem sap increased significantly but remained low. To clarify their respective roles in the early events of bud break, carbohydrate concentrations and uptake rates, and activities of NAD-dependent sorbitol dehydrogenase (SDH), sorbitol oxidase (SOX) and cell wall invertase (CWI) were determined in meristematic tissues, cushion tissues and stem segments. Only CWI activity increased in meristematic tissues shortly before bud break. In buds displaying high bud break capacity (during January and February), concentrations of sorbitol and sucrose in meristematic tissues were almost unchanged, paralleling their low rates of uptake and utilization by meristematic tissues, and indicating that sorbitol and sucrose play a negligible role in the bud break process. Hexose concentrations in meristematic tissues and glucose imported by meristematic tissues correlated positively with bud break capacity, suggesting that hexoses are involved in the early events of bud break. These findings were confirmed by data for buds that were unable to break because they had been collected from trees deprived of cold. We therefore conclude that hexoses are of greater importance than sorbitol or sucrose in the early events of bud break in peach trees.     

Regulation of protein metabolism by insulin: value of different approaches and animal models

Insulin induces protein accretion by stimulating protein synthesis and inhibiting proteolysis. However, the mechanisms of regulation of protein metabolism by insulin are complex and still not completely understood. The use of approaches combining hyperinsulinemic clamp and isotopic methods, or measurement of the activation of intracellular kinases involved in insulin signaling, in addition to the use of different animal models in a comparative physiology process, provide better understanding of the potential regulation of protein metabolism by insulin. Studies using the clamp technique in lactating goats have shown a clear inhibitory effect of insulin on proteolysis, with an interaction between the effects of insulin and amino acids. Such studies revealed that the insulin-inhibited proteolysis is improved in lactating goats, this adaptative process limiting the mobilization of body protein under the conditions of amino acid deficit which occurs during early lactation. Insulin signaling studies in growing chickens have also provided some interesting features of insulin regulation compared to mammals. Refeeding or insulin injection leads to the activation of the early steps of insulin receptor signaling in the liver but not in the muscle. Muscle p70 S6 kinase, a kinase involved in the insulin activation of protein synthesis, was found to be markedly activated in response to insulin and to refeeding, suggesting that other signaling pathways than those classically described in mammalian muscles may be involved in signal transduction. Finally, although the role of insulin has been doubtful and has long been considered to be minor in ruminants and in avian species, this hormone clearly regulates protein metabolism in both species.     

Design of Division Specific Primers of Ralstonia solanacearum and Application to the Identification of European Isolates

A PCR diagnostic test for detection of Ralstonia solanacearum at the infraspecific level was developed, based on polymorphisms within the 16S rRNA gene sequence. Partial sequences of this gene were determined for three French isolates which showed the characteristics of R. solanacearum subdivision 2a described by Taghavi et al. (1996). Oligonucleotide primers were designed to incorporate the nucleotide triplet (at positions 458–460 of the 16S rRNA gene) which differs between divisions 1 and 2 16S rRNA sequences of R. solanacearum isolates. A simple PCR test unambiguously revealed the division of each isolate. The PCR test was useful for identification of isolates of R. solanacearum from Europe.     

Effects of hypoxia on respiratory physiology of turbot, Scophthalmus maximus

Variations in respiratory and acid-base status were studied in turbot (Scophthalmus maximus) during progressive severe hypoxia followed by recovery under normoxic conditions. The first behavioural strategy of turbot under hypoxia was an increase in amplitude and frequency of ventilation. Consequently, standard O₂ consumption remained unchanged over a broad range of O₂ tensions, until a low critical level of 30 mmHg. The hyperventilation induced a moderate blood alkalosis, compensated by a lactic acidosis. The fact that blood pH did not decrease below control values could be explained by the retention in white muscle of most of the lactate produced and by a high capacity for H⁺ excretion. During the recovery period, the marked increase in O₂ uptake corresponding to an oxygen debt repayment, was partly related to the lactate elimination. When total energy contributions of aerobic and anaerobic processes were assessed in terms of ATP, the anaerobic contribution, estimated at the deepest hypoxia level, was higher than 20% of the total energy budget and appeared to totally compensate for the decline in aerobic metabolism. Moreover, the high value of O₂ tension in arterial blood in normoxia and during recovery from hypoxia showed high diffusing capacity of gills in turbot. Our results explain the high tolerance of turbot for O₂ deficient waters.     

Potential of combined biological control agents to cope with <Emphasis Type="Italic">Phytophthora parasitica,</Emphasis> a major pathogen of <Emphasis Type="Italic">Choisya ternata</Emphasis>

The Cook Agronomy Farm of Washington State University is a long-term precision agriculture study site. Since 2000, the farm has been in various three-year no-till rotations with winter wheat, spring wheat, and various rotation crops such as barley, canola, peas, lentils, and chickpea. The spatial distribution of root lesion nematodes (Pratylenchus spp.) and their relationships with soil and terrain variables were studied by collecting soil samples at 127 and 124 geo-referenced points in two 12-ha fields during the spring of 2010 and 2011, respectively. Pratylenchus spp. were detected in more than 85% of the sampled locations in both fields. Nematode densities spatially mapped using ArcGIS software occurred in an aggregated pattern. Previous rotation crops had no effect on the spatial distribution. Classification and regression tree analysis (CART) using soil and terrain variables, and nematode density, explained 61 and 34% of the variability associated with nematode density in 2010 and 2011, respectively. Soil edaphic factors, such as organic matter, were stronger predictors of nematode populations than rotation effects.     

Population trends in a community of large Procellariiforms of Indian Ocean: Potential effects of environment and fisheries interactions

Despite the worrying conservation status of several albatross and petrel population, the long-term trends of many populations remain largely unknown and the causes of decline in many cases are known or very strongly suspected to be incidental mortality in fisheries. Here we combine long-term monitoring of population trends, breeding success and band recoveries to examine the past and current status of five species of albatrosses and giant petrels breeding at the same site: sooty albatross (Phoebetria fusca), light-mantled albatross (Phoebetria palpebrata), wandering albatross (Diomedea exulans), northern giant (Macronectes halli) and southern giant petrels (Macronectes giganteus) on Possession Island, Crozet archipelago. We identified three groups of trends over a 25-years period (1980-2005) suggesting common underlying causes for these species in relation to their bioclimatic foraging ranges. The Antarctic species - light-mantled albatross and southern giant petrel - appeared stable and increased recently, the Sub-Antarctic species - wandering albatross and northern giant petrel - declined with intermediate periods of increase, and finally the subtropical species - sooty albatross - declined all over the period. Breeding success, indicative of environmental conditions, showed two kinds of pattern (low and fluctuating versus high and/or increasing) which were consistent with oceanographic variations as found in a previous study. We present the analysis of fisheries-related recoveries, indicative of fisheries bycatch risks showing specific catch rates. No direct relationship between population trends and longline fishing effort was detected, probably because census data alone are not sufficient to capture the potentially complex response of demographic parameters of different life stages to environmental variation. This study highlights the contrasted changes of procellariiform species and the particularly worrying status of the subtropical sooty albatrosses, and in a lesser extent of Sub-Antarctic species.