146 research outputs found
Nematodes from sandy beaches of Guanabara Bay, Rio de Janeiro, Brazil
This work assessed the nematode composition in three sandy beaches located at Guanabara Bay, Rio de Janeiro, Brazil (22°24’ and 22°57’S; 42°33’ and 43°19’W). These microtidal, sheltered sandy beaches (Bica, Bananal and Coqueiros) were surveyed on January and June 2001, during the low tide. Samples were taken using a PVC core of 10cm2. Nematodes were extracted using the sugar-flotation methodology. The sediment of these beaches was mainly composed of sand and showed a variation between medium to very coarse sediments. In total 6312 specimens were identified up to the genus level or when possible to species level. At the three beaches, 62 genera were found, belonging to 25 families and distributed along of 8 orders. Chromadoridae was the most abundant family in terms of genera. All the families found have also been recorded from previously studied beaches. Amongst the genera found, four of them (Deontolaimus, Dracograllus, Phanodermella and Subsphaerolaimus) were for the first time recorded for Brazilian’s coastline. The number of genera occurring on the Guanabara beaches (31 for Bica, 39 for Bananal and 46 for Coqueiros) is more or less similar to another Brazilian sandy beach whereas these values showed higher variation concerning worldwide tropical and non-tropical beaches. The first occurrence of four genera for the Brazilian coastline suggest the possibility to discover new species in this bay, therefore to the need for further development of nematode taxonomy in Brazil
Tidal exposure or microhabitats: what determines sandy-beach nematode zonation? A case study of a macrotidal ridge-and-runnel sandy beach in Belgium
Lately, across-shore zonation has been found to be more important in structuring the nematode community of a tropical macrotidal sandy beach than microhabitat heterogeneity. To evaluate whether this zonation pattern applies to a temperate beach, a macrotidal ridge-and-runnels sandy beach in the North Sea was studied. We investigated whether a similar zonation occurs in sandbar and runnel microhabitats, and whether the runnels harbour a different community from the subtidal. Our results indicate that nematode communities from runnel and sandbar habitats are significantly different. In addition, horizontal zonation patterns for nematode communities differ between both habitats. Nematode assemblages from sandbars are divided to lower, middle and upper beach while upper and middle runnels cluster together. The subtidal and upper runnels showed dissimilar nematode assemblages, although runnels showed the same dominant species (Daptonema normandicum), which increases its abundance towards the upper runnels. This study illustrates the importance of microhabitat heterogeneity, which resulted in different zonation patterns across the sandy beach examined. The divergent zonation between sandbars and runnels in the macrotidal temperate sandy beach, compared with the pattern observed for a subtropical sandy beach with similar morphodynamics, indicates that generalizations about nematode distribution patterns should be made with caution
Evaluating environmental drivers of spatial variability in free-living nematode assemblages along the Portuguese margin
Understanding processes responsible for shaping biodiversity patterns on continental margins is an important requirement for comprehending anthropogenic impacts in these environments and further management of biodiversity. Continental margins perform crucial functions linked to key ecological processes which are mainly structured by surface primary productivity and particulate organic matter flux to the seafloor, but also by heterogeneity in seafloor characteristics. However, to what extent these processes control local and regional biodiversity remains unclear. In this study, two isobathic parallel transects located at the shelf break (300-400 m) and upper slope (1000 m) of the western Iberian margin were used to test how food input and sediment heterogeneity affect nematode diversity independently from the spatial factors geographical distance and water depth. We also examined the potential role of connectedness between both depth transects through molecular phylogenetic analyses. Regional generic diversity and turnover were investigated at three levels: within a station, between stations from the same depth transect, and between transects. High variability in food availability and high sediment heterogeneity at the shelf-break transect were directly linked to high diversity within stations and higher variation in community structure across stations compared to the upper slope transect. Contrastingly, environmental factors (food availability and sediment) did not vary significantly between stations located at the upper slope, and this lack of differences were also reflected in a low community turnover between these deeper stations. Finally, differences in nematode communities between both transects were more pronounced than differences within each of the isobathic transects, but these changes were paralleled by the previously mentioned environmental changes. These results suggest that changes in community structure are mainly dictated by environmental factors rather than spatial differences at the western Iberian margin. Furthermore, phylogenetic relationships revealed no evidence for depth-endemic lineages, indicating regular species interchanges across different depths
Physiological and thermographic response to heat stress in zebu cattle
AbstractThe objective of this study was to evaluate the heat tolerance of five zebu breeds using physical, physiological and hematological traits as well as thermographic responses. Forty cows of the Gir, Girolando, Nelore, Sindhi and Indubrasil breeds (eight cows each), approximately three years of age, were evaluated. Body weight, withers and hump heights as well as thoracic circumference were recorded. The density and length of the hair was obtained by collecting one square centimeter in the rump region and skin color using the CIELAB system. Rectal temperature, heart and respiratory rates were evaluated during the morning at 4:30h, and in the afternoon, at 14:30h, with six repetitions. Blood samples were collected for hematological evaluation. The surface temperature was obtained using an infrared camera FLIR® T400. Two images were taken from each animal, one laterally of the whole body and the other of the head region. Air temperature, wind speed, relative humidity were obtained from a mobile weather station. The statistics analysis included an analyzes of variance, principal factors, as well as cluster, discriminant and canonical analyzes, logistic regression and calculation of odds ratio. There were significant differences in the rectal temperature, heart and respiratory rates between breeds. Gir and Indubrasil breeds had the highest rectal temperatures. Breed was significant for surface temperatures and showed that physical and physiological factors affected breeds in different ways. Eye and brain surface temperatures were the most affected by environmental parameters. Also, environmental parameters affected packed cell volume and red cell number. Odds ratio test showed that the Gir breed was three times more likely to have higher rectal temperature compared with Sindhi as confirmed by the logistic regression. When the black globe temperature approached 35°C, the probability of the Gir animals having rectal temperatures above normal was approximately 70%. Gir was the breed least adapted to climate conditions of the experiment while the Sindhi and Girolando breeds showed the best physiological response to thermal stress
Changes In Motor Behavior During Pregnancy In Rats: The Basis For A Possible Animal Model Of Restless Legs Syndrome [alterações No Comportamento Motor De Ratas Prenhes: Bases Para Um PossÃvel Modelo Animal Da SÃndrome Das Pernas Inquietas]
PURPOSE: Pregnant women have a 2-3 fold higher probability of developing restless legs syndrome (RLS – sleep-related movement disorders) than general population. This study aims to evaluate the behavior and locomotion of rats during pregnancy in order to verify if part of these animals exhibit some RLS-like features. METHODS: We used 14 female 80-day-old Wistar rats that weighed between 200 and 250 g. The rats were distributed into control (CTRL) and pregnant (PN) groups. After a baseline evaluation of their behavior and locomotor activity in an open-field environment, the PN group was inducted into pregnancy, and their behavior and locomotor activity were evaluated on days 3, 10 and 19 of pregnancy and in the post-lactation period in parallel with the CTRL group. The serum iron and transferrin levels in the CTRL and PN groups were analyzed in blood collected after euthanasia by decapitation. RESULTS: There were no significant differences in the total ambulation, grooming events, fecal boli or urine pools between the CTRL and PN groups. However, the PN group exhibited fewer rearing events, increased grooming time and reduced immobilization time than the CTRL group (ANOVA, p<0.05). CONCLUSION: These results suggest that pregnant rats show behavioral and locomotor alterations similar to those observed in animal models of RLS, demonstrating to be a possible animal model of this sleep disorder.3610436441Allen, R.P., Walters, A.S., Montplaisir, J., Hening, W., Myers, A., Bell, T.J., Restless legs syndrome prevalence and impact: REST general population study (2005) Arch Intern Med, 165 (11), pp. 1286-1292McCrink, L., Allen, R.P., Wolowacz, S., Sherrill, B., Connolly, M., Kirsch, J., Predictors of health-related quality of life in sufferers with restless legs syndrome: A multi-national study (2007) Sleep Med, 8 (1), pp. 73-83Trenkwalder, C., Paulus, W., Restless legs syndrome: Pathophysiology, clinical presentation and management (2010) Nat Rev Neurol, 6 (6), pp. 337-346Phillips, B., Young, T., Finn, L., Asher, K., Hening, W.A., Purvis, C., Epidemiology of restless legs symptoms in adults (2000) Arch Intern Med, 160 (14), pp. 2137-2141Manconi, M., Govoni, V., De Vito, A., Economou, N.T., Cesnik, E., Mollica, G., Pregnancy as a risk factor for restless legs syndrome (2004) Sleep Med, 5 (3), pp. 305-308Goodman, J.D., Brodie, C., Ayida, G.A., Restless leg syndrome in pregnancy (1988) BMJ, 297 (6656), pp. 1101-1102Eriksson, L., Edén, S., Holst, J., Lindstedt, G., Von Schoultz, B., Diurnal variations in thyrotropin, prolactin and cortisol during human pregnancy (1989) Gynecol Obstet Invest, 27 (2), pp. 78-83Walters, A.S., Toward a better definition of the restless legs syndrome. 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Association between promoter methylation of MLH1 and MSH2 and reactive oxygen species in oligozoospermic men—A pilot study
MLH1 and MSH2 are important genes for DNA mismatch repair and crossing over during
meiosis and are implicated in male infertility. Therefore, the methylation patterns
of the DNA mismatch repair genes MLH1 and MSH2 in oligozoospermic males were
investigated. Ten oligozoospermic patients and 29 normozoospermic donors were
analysed. Methylation profiles of the MLH1 and MSH2 promotors were analysed. In
addition, sperm motility and seminal reactive oxygen species (ROS) were recorded.
Receiver operating characteristic (ROC) analysis was conducted to determine the accuracy
of the DNA methylation status of MLH1 and MSH2 to distinguish between oligozoospermic
and normozoospermic men. In oligozoospermic men, MLH1 was
significantly (p = .0013) more methylated compared to normozoospermic men.
Additionally, there was a significant positive association (r = .384; p = .0159) between
seminal ROS levels and MLH1 methylation. Contrary, no association between MSH2
methylation and oligozoospermia was found. ROC curve analysis for methylation status
of MLH1 was significant (p = .0275) with an area under the curve of 61.1%, a sensitivity
of 22.2% and a specificity of 100.0%. This pilot study indicates oligozoospermic
patients have more methylation of MLH1 than normozoospermic patients. Whether
hypermethylation of the MLH1 promoter plays a role in repairing relevant mismatches
of sperm DNA strands in idiopathic oligozoospermia warrants further investigation
Qualidade para o cozimento de grãos de feijão obtidos em diferentes épocas de semeadura
Efeito da radiação gama na absorção de água e no tempo de cocção em cultivares de soja
Colonization by benthic macroinvertebrates in two artificial substrate types of a Riparian Forest
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