SCF-Fbxo42 promotes synaptonemal complex assembly by downregulating PP2A-B56

Meiosis creates genetic diversity by recombination and segregation of chromosomes. The synaptonemal complex assembles during meiotic prophase I and assists faithful exchanges between homologous chromosomes, but how its assembly/disassembly is regulated remains to be understood. Here, we report how two major posttranslational modifications, phosphorylation and ubiquitination, cooperate to promote synaptonemal complex assembly. We found that the ubiquitin ligase complex SCF is important for assembly and maintenance of the synaptonemal complex in Drosophila female meiosis. This function of SCF is mediated by two substrate-recognizing F-box proteins, Slmb/βTrcp and Fbxo42. SCF-Fbxo42 down-regulates the phosphatase subunit PP2A-B56, which is important for synaptonemal complex assembly and maintenance.     

Diet and trophic position of two mackerel species in the archipelago of Madeira,Portugal

The Atlantic chub mackerel Scomber colias and the blue jack mackerel Trachurus picturatus are two abundant species in the Macaronesia region which includes the archipelago of Madeira, Portugal. Both are key species in the trophic web, being important prey for several local top predators, such as seabirds and marine mammals. Nonetheless, little is known about their feeding ecology in oceanic environments. In this study, the authors describe the seasonal variation in the diet of S. colias and T. picturatus in the oceanic region of Madeira throughout a year. Visual inspection of stomach contents revealed that S. colias fed on a broader range of prey groups than T. picturatus, but for both species, zooplankton (particularly calanoid copepods) and fish were the most important food items. The diet of S. colias included a higher proportion of fish, namely Atlantic saury Scomberesox saurus and S. colias, than that of T. picturatus, that included mostly the longspine snipefish Macroramphosus scolopax. T. picturatus consumed a higher proportion of decapods and other copepods. Seasonal variation was found in the diet of both species, with zooplanktonic species being more important in colder months (February to April) for S. colias and during warm months (May to October) for T. picturatus. Their diet in other seasons was dominated by fish. Although they consume similar prey, carbon and nitrogen stable isotope analysis of muscle of S. colias and T. picturatus showed little overlap in their diets, and T. picturatus showed higher δ¹⁵N and a narrower isotopic niche.     

Can the use of zooplankton dormant stages from natural wetlands contribute to restoration of mined wetlands?

Wetlands are among the most diverse environments on the planet and are strongly threatened by human activities. Their restoration and/or mitigation of human impacts, therefore, relies on information that can aid to the management of impacted wetlands so that they return to a (semi-) natural state. We investigate in this study the relationship between dormant stages of zooplankton and clay removal in areas subjected to mining. We evaluate whether a gradual increase in topsoil addition from donor natural wetlands to the sediment of mined wetlands influenced the zooplankton community. Eight wetlands were sampled in the Sinos River floodplain, four natural and four mined. In the laboratory, four field sediment samples were incubated for zooplankton hatching in five treatments comprising sediments from: mined wetlands, natural wetlands, and three treatments containing mined sediments added with low (5%), medium (20%) and high (40%) quantities of sediment from natural wetlands. Hatching consisted of 61 individuals distributed across eight zooplankton taxa. Copepod nauplii were the most abundant (31.1%) followed by Epiphanes sp. (29.5%) and Ovalona glabra (16.4%). While natural wetlands provided 42.6% of the hatched zooplankton, mined wetlands had just 6.5%. Zooplankton richness and abundance were higher in natural wetland sediments compared with mined and added sediment wetlands. To some degree, the sediment soil donation from natural to mined wetlands was considered viable. As long as prior studies are performed to test the size and quality of the dormant banks present in the sediment of candidate donor wetlands, sediment from donor wetlands may aid in the establishment of a more diverse community in disturbed systems.

     

Performance evaluation of Baermann techniques: The quest for developing a microscopy reference standard for the diagnosis of Strongyloides stercoralis

BackgroundSoil-transmitted helminths (STH) are common in low and middle income countries where there is lack of access to clean water and sanitation. Effective diagnosis and treatment are essential for the control of STH infections. However, among STH parasites, Strongyloides stercoralis is the most neglected species, both in diagnostics and control strategies. Diagnostic methods cover different approaches, each with different sensitivities and specificities, such as serology, molecular techniques and microscopy based techniques. Of the later, the Baermann technique is the most commonly used procedure. In the literature, several ways have been described to perform the Baermann method, which illustrates the overall lack of a ‘(gold) reference standard’ method for the diagnosis of S. stercoralis infection. In this study we have evaluated the performance of three Baermann techniques in order to improve the reference standard for the microscopic diagnosis of S. stercoralis infection thereby facilitating individual case detection, mapping of the disease and proper evaluation of treatment responses.Methods/Principal findingsA community based cross sectional study was conducted at Zenzelima, Bahir Dar Zuria Ethiopia. A total of 437 stool samples were collected and analyzed by the following procedures: conventional Baermann (CB), modified Baermann (MB), and modified Baermann with charcoal pre-incubation (MBCI). The diagnostic sensitivity and Negative Predictive Value (NPV) of each technique was calculated using the combination of all the three techniques as a composite reference standard. Our result indicated that larvae of S. stercoralis were detected in 151 (34.6%) stool samples. The prevalence of S. stercoralis infection based on the three diagnostic methods was 9.6%, 8.0%, and 31.3% by CB, MB, and MBCI respectively. The sensitivity and NPV for CB, MB, and MBCI were 26.7% and 70.8%, 22.1% and 69.6%, and 87.0% and 93.2%, respectively. The MBCI showed significant difference (P- value = <0.001) in the sensitivity and NPV values when compared with CB and MB values. The agreement between CB, MB, and MBCI with the composite reference standard was 31.8%, 26.7%, 89.6%, respectively.Conclusion/SignificanceOur results suggest the superior performance of MBCI. It is relatively easy to implement, simple to perform and comparatively cheaper. The CB is by far the commonly used method in routine diagnostic although this technique significantly underestimates the true burden of the disease and thereby contributing to the exclusion of S. stercoralis from the control strategies. Therefore, MBCI is recommended as a routine microscopy-based diagnostic test for S. stercoralis infection, particularly in settings where molecular procedures are not available.     

An electromyographic analysis of two handwriting grasp patterns

BackgroundHandwriting is a fundamental skill needed for the development of daily-life activities during lifetime and can be performed using different forms to hold the writing object. In this study, we monitored the sEMG activity of trapezius, biceps brachii, extensor carpi radialis brevis and flexor digitorum superficialis during a handwriting task with two groups of subjects using different grasp patterns.Subjects and methodsTwenty-four university students (thirteen males and eleven females; mean age of 22.04 ± 2.8 years) were included in this study. We randomly invited 12 subjects that used the Dynamic Tripod grasp and 12 subjects that used the Static Tripod grasp.ResultsThe static tripod group showed statistically significant changes in the sEMG activity of trapezium and biceps brachii muscles during handwriting when compared to dynamic tripod group’s subjects. No significant differences were found in extensor carpi radialis brevis and flexor digitorum superficialis activities among the two groups.ConclusionThe findings in this study suggest an increased activity of proximal muscles among subjects using a transitional grasp, indicating potential higher energy expenditure and muscular harm with the maintenance of this motor pattern in handwriting tasks, especially during the progression in academic life.     

Study of the Stability Of Vaccinium myrtillus Peroxidase in Reverse Micellar Systems

The stability of a cationic peroxidase isolated and purified from a cell suspension of Vaccinium myrtillus, microencapsulated in reverse micelles of sodium dioctylsulfosuccinate (AOT) was evaluated. By using a central composite design (CCD), some relevant parameters for the enzymatic activity, such as surfactant and water concentration, pH and buffer molarity, were analysed. The response surface curves showed that 50 mM AOT, 500 mM water, 80 mM buffer and pH 7.6 were the best conditions for enzyme stability. The effect of carbohydrates and polyols on enzyme stability was also evaluated. At 20 mM, carbohydrates like arabinose, and trehalose increased the enzymatic stability by a factor of 4.4 and 2.3, respectively, but melezitose had no effect. From the three polyols tested, inositol and sorbitol increased the peroxidase stability by a factor of 3.8 and 1.8, respectively, while mannitol had no effect.     

Inflammatory intestinal damage induced by 5-fluorouracil requires IL-4

Background5-Fluorouracil (5-FU) induces intestinal mucositis, which is characterized by epithelial ulcerations in the mucosa and clinical manifestations, such as pain and dyspeptic symptoms. Cytokines participate in the inflammatory and functional events of intestinal mucositis. IL-4 is an important mediator of intestinal inflammation, with either anti-inflammatory or pro-inflammatory functions, depending on the model of intestinal inflammation. This study aimed to evaluate the role of IL-4 in 5-FU-induced intestinal mucositis.MethodsIL-4^+/+ or IL-4^?/? mice (25–30 g) were intraperitoneally injected with 5-FU (450 mg/Kg) or saline (C). After 3 days, the mice were sacrificed and the duodenum was evaluated for epithelial damage, MPO activity and cytokine concentration.Results5-FU induced significant damage in the intestinal epithelium of IL-4^+/+ mice (reduction in the villus/crypt ratio: control = 3.31 ± 0.21 μm, 5-FU = 0.99 ± 0.10 μm). However, the same treatment did not induce significant damage in IL-4^?/? mice (5-FU = 2.87 ± 0.19 μm) compared to wild-type mice. 5-FU-induced epithelial damage increased the MPO activity (neutrophil number) and the level of pro-inflammatory cytokines (IL-4, TNF-α, IL-1β and CXCL-8) in the duodenum. These results were not observed in IL-4^?/? mice treated with 5-FU.ConclusionOur data suggest that IL-4 participates as a pro-inflammatory cytokine in a 5-FU-induced intestinal damage model and suggests that IL-4 antagonists may be novel therapeutics for this condition.