Variability in host plant resistance of Sorghum to Striga Hermonthica infestation in West Africa

Fourteen elite sorghum lines were evaluated for their resistance to Striga hermonthica at three locations in Nigeria and Mali. Results showed that many of the lines especially MALISOR 84-1, SAMSORG 41, 97-SB-F5DT-64 (Keninkédié) and the check SRN 39 remained resistant to Striga in all locations with low emerged Striga counts, while SAMSORG 14 had the highest Striga infestation in all locations. Considerable variation in reaction to Striga infestation was observed on Séguètana, 97-SB-F5DT-63 (Wasa), 97-SB-F5DT-65, CMDT 38, CMDT 39 and CMDT 45 which were susceptible to Striga at Samaru, Nigeria but were resistant to Striga at both locations in Mali. Based on low Striga resistance and high grain yield, lines MALISOR 84-1, SAMSORG 41, 97-SB-F5DT-64, 97-SB-F5DT-65, CMDT 39 and SAMSORT 14 have been nominated for wider evaluation across more West African countries.     

Two common nonsynonymous paraoxonase 1 (<Emphasis Type="Italic">PON1</Emphasis>) gene polymorphisms and brain astrocytoma and meningioma

Background  

Human serum paraoxonase 1 (PON1) plays a major role in the metabolism of several organophosphorus compounds. The enzyme is encoded by the polymorphic gene PON1, located on chromosome 7q21.3. Aiming to identify genetic variations related to the risk of developing brain tumors, we investigated the putative association between common nonsynonymous PON1 polymorphisms and the risk of developing astrocytoma and meningioma.     

Long-term effects of graduated compression stockings on cardiorespiratory performance

The use of graduated compression stockings (GCS) in sport has been increasing in the last years due to their potential positive effects for athletes. However, there is little evidence to support whether these types of garments actually improve cardiorespiratory performance. The aim of this study was to examine the cardiorespiratory responses of GCS during running after three weeks of regular use. Twenty recreational runners performed three tests on different days: test 1) – a 5-min maximal effort run in order to determine the participants’ maximal aerobic speed; and tests 2) and 3) – a fatigue running test of 30 minutes at 80% of their maximal aerobic speed with either GCS or PLACEBO stockings at random. Cardiorespiratory parameters (minute ventilation, heart rate, relative oxygen consumption, relative carbon dioxide production, ventilatory equivalents for oxygen and carbon dioxide, and oxygen pulse) were measured. Before each test in the laboratory, the participants trained with the randomly assigned stockings (GCS or PLACEBO) for three weeks. No significant differences between GCS and PLACEBO were found in any of the cardiorespiratory parameters. In conclusion, the present study provides evidence that running with GCS for three weeks does not influence cardiorespiratory parameters in recreational runners.     

Extensive scar formation and regression during heart regeneration after cryoinjury in zebrafish

The zebrafish heart has the capacity to regenerate after ventricular resection. Although this regeneration model has proved useful for the elucidation of certain regeneration mechanisms, it is based on the removal of heart tissue rather than its damage. Here, we characterize the cellular response and regenerative capacity of the zebrafish heart after cryoinjury, an alternative procedure that more closely models the pathophysiological process undergone by the human heart after myocardial infarction (MI). Localized damage was induced in 25% of the ventricle by cryocauterization (CC). During the first 24 hours post-injury, CC leads to cardiomyocyte death within the injured area and the near coronary vasculature. Cell death is followed by a rapid proliferative response in endocardium, epicardium and myocardium. During the first 3 weeks post-injury cell debris was cleared and the injured area replaced by a massive scar. The fibrotic tissue was subsequently degraded and replaced by cardiac tissue. Although animals survived CC, their hearts showed nonhomogeneous ventricular contraction and had a thickened ventricular wall, suggesting that regeneration is associated with processes resembling mammalian ventricular remodeling after acute MI. Our results provide the first evidence that, like mammalian hearts, teleost hearts undergo massive fibrosis after cardiac damage. Unlike mammals, however, the fish heart can progressively eliminate the scar and regenerate the lost myocardium, indicating that scar formation is compatible with myocardial regeneration and the existence of endogenous mechanisms of scar regression. This finding suggests that CC-induced damage in zebrafish could provide a valuable model for the study of the mechanisms of scar removal post-MI.     

Influence of foraging behavior and host spatial distribution on the localized spread of the emerald ash borer, <Emphasis Type="Italic">Agrilus planipennis</Emphasis>

Management programs for invasive species are often developed at a regional or national level, but physical intervention generally takes place over relatively small areas occupied by newly founded, isolated populations. The ability to predict how local habitat variation affects the expansion of such newly founded populations is essential for efficiently targeting resources to slow the spread of an invasive species. We assembled a coupled map lattice model that simulates the local spread of newly founded colonies of the emerald ash borer (Agrilus planipennis Fairmaire), a devastating forest insect pest of ash (Fraxinus spp.) trees. Using this model, we investigated the spread of A. planipennis in environments with different Fraxinus spp. distributions, and explored the consequences of ovipositional foraging behavior on the local spread of A. planipennis. Simulations indicate that increased larval density, resulting from lower host tree density or higher initial population sizes, can increase the spread rate during the first few years after colonization by increasing a density-dependent developmental rate and via host resource depletion. Both the radial spread rate and population size were greatly influenced by ovipositional foraging behavior. Two known behaviors of ovipositing A. planipennis females, attraction towards areas with high ash tree density and attraction to stressed trees, had opposing effects on spread. Results from this model illustrate the significant influence of resource distribution and foraging behavior on localized spread, and the importance of these factors when formulating strategies to monitor and manage invasive pests.     

Long-term activation of semicarbazide-sensitive amine oxidase lowers circulating levels of uric acid in diabetic conditions

Uric acid is involved in nitrogenous waste in animals, together with ammonia and urea. Uric acid has also antioxidant properties and is a surrogate marker of metabolic syndrome. We observed that the elevated plasma uric acid of high-fat fed mice was normalized by benzylamine treatment. Indeed, benzylamine is the reference substrate of semicarbazide-sensitive amine oxidase (SSAO), an enzyme highly expressed in fat depots and vessels, which generates ammonia when catalysing oxidative deamination. Ammonia interferes with uric acid metabolism/solubility. Our aim was therefore to investigate whether the lowering action of benzylamine on uric acid was related to an improvement of diabetic complications, or was connected with SSAO-dependent ammonia production. First, we observed that benzylamine administration lowered plasma uric acid in diabetic db/db mice while it did not modify uric acid levels in normoglycemic and lean mice. In parallel, benzylamine improved the glycemic control in diabetic but not in normoglycemic mice, while plasma urea remained unaltered. Then, uric acid plasma levels were measured in mice invalidated for AOC3 gene, encoding for SSAO. These mice were unable to oxidize benzylamine but were not diabetic and exhibited unaltered plasma uric levels. Therefore, activated or abolished ammonia production by SSAO was without influence on uric acid in the context of normoglycemia. Our observations confirm that plasma uric acid increases with diabetes and can be normalized when glucose tolerance is improved. They also show that uric acid, a multifunctional metabolite at the crossroads of nitrogen waste and of antioxidant defences, can be influenced by SSAO, in a manner apparently related to changes in glucose homeostasis.     

Estimating the influence of population density and dispersal behavior on the ability to detect and monitor Agrilus planipennis (Coleoptera: Buprestidae) populations

Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), a phloem-feeding pest of ash (Fraxinus spp.) trees native to Asia, was first discovered in North America in 2002. Since then, A. planipennis has been found in 15 states and two Canadian provinces and has killed tens of millions of ash trees. Understanding the probability of detecting and accurately delineating low density populations of A. planipennis is a key component of effective management strategies. Here we approach this issue by 1) quantifying the efficiency of sampling nongirdled ash trees to detect new infestations of A. planipennis under varying population densities and 2) evaluating the likelihood of accurately determining the localized spread of discrete A. planipennis infestations. To estimate the probability a sampled tree would be detected as infested across a gradient of A. planipennis densities, we used A. planipennis larval density estimates collected during intensive surveys conducted in three recently infested sites with known origins. Results indicated the probability of detecting low density populations by sampling nongirdled trees was very low, even when detection tools were assumed to have three-fold higher detection probabilities than nongirdled trees. Using these results and an A. planipennis spread model, we explored the expected accuracy with which the spatial extent of an A. planipennis population could be determined. Model simulations indicated a poor ability to delineate the extent of the distribution of localized A. planipennis populations, particularly when a small proportion of the population was assumed to have a higher propensity for dispersal.     

The Osr1 and Osr2 genes act in the pronephric anlage downstream of retinoic acid signaling and upstream of Wnt2b to maintain pectoral fin development

Vertebrate odd-skipped related genes (Osr) have an essential function during the formation of the intermediate mesoderm (IM) and the kidney structures derived from it. Here, we show that these genes are also crucial for limb bud formation in the adjacent lateral plate mesoderm (LPM). Reduction of zebrafish Osr function impairs fin development by the failure of tbx5a maintenance in the developing pectoral fin bud. Osr morphant embryos show reduced wnt2b expression, and increasing Wnt signaling in Osr morphant embryos partially rescues tbx5a expression. Thus, Osr genes control limb bud development in a non-cell-autonomous manner, probably through the activation of Wnt2b. Finally, we demonstrate that Osr genes are downstream targets of retinoic acid (RA) signaling. Therefore, Osr genes act as a relay within the genetic cascade of fin bud formation: by controlling the expression of the signaling molecule Wnt2ba in the IM they play an essential function transmitting the RA signaling originated in the somites to the LPM.