Genetic diversity and population structure in a regional collection of Kersting’s groundnut (Macrotyloma geocarpum (Harms) Maréchal & Baudet)

Genetic Resources and Crop Evolution - Kersting’s groundnut (Macrotyloma geocarpum (Harms) Maréchal & Baudet) is an important source of protein and essential nutrients that...     

Description of hydrological and erosion processes determined by applying the LISEM model in a rural catchment in southern Brazil

Purpose

Hydrosedimentological modeling is a tool that can be used to understand better important processes occurring at the catchment scale, such as runoff and sediment yield. The aim of this study was to use the Limburg Soil Erosion Model (LISEM) to describe the runoff and sediment yield during rainfall–runoff events in a small rural catchment in southern Brazil.

Materials and methods

The study was conducted in the Lajeado Ferreira Creek catchment (drainage area of 1.19 km²) where intense land use has caused a negative impact on water resources. Thirteen rainfall–runoff events that occurred in 2010 and 2011, including high-magnitude events, were used to model hydrosedimentological processes.

Results and discussion

Results

from the calibration and validation stages indicate that the model had a good performance when representing the hydrograph, including events with greater complexity. The use of a second soil layer in the model increased its efficiency, which is in accordance with the importance of subsurface flow in this catchment and its sensitivity to the physical properties of the soil, which are essential for controlling hydrosedimentological processes at the catchment scale. The simulation of sediment yield was overestimated by the model, constrained by the lack of sensitivity of the model to soil cohesion and the stability of soil aggregates. During the model calibration stage, these parameters had values different from those measured in the field.

Conclusions

The LISEM model performed well in representing runoff for events of different magnitudes. The discretization of the physical–hydrologic properties in the soil profile enabled the evaluation of the effect of subsurface impediment layers on water infiltration and runoff. The simulation was less accurate for suspended sediment concentration than for runoff. This indicates the need for further studies to either identify other factors controlling erosion and sediment yield that have not been identified by the model, or identify if the representation of the physical parameters is inadequate, especially the values of soil cohesion and aggregate stability.     

Sulfur isotope fractionation and sequential extraction to assess metal contamination on lake and river sediments

Purpose

The present study investigated lake and river sediments affected by metals from an acid mine drainage (AMD) from a former uranium mine. The role of bacterial sulfate reduction in the immobilization of contaminants was evaluated, and the analyses of acid volatile sulfide (AVS) and sequential extraction were performed. Consequently, the potential mobility and bioavailability of contaminants were established.

Materials and methods

Sulfur isotopic fractionation (δ³⁴S), AVS, and sequential extraction procedure were used to assess the sulfate bacterial reduction and the availability of contaminants in the environment at six sampling stations.

Results and discussion

The δ³⁴S indicated that bacterial reduction is a key process in the natural attenuation of contamination in the Águas Claras reservoir, precipitating metal sulfides. According to the USEPA criteria, adverse biological effects are expected for sample S1 (inside the reservoir) which is likely to be toxic, while for sediment S4 (in the river), the toxicity is uncertain. The other samples were classified as non-toxic, likely because of the decreased solubility of zinc sulfide. A decrease in the concentration of the contaminants downstream of the reservoir was observed. The predominance of U (0.4 %) in the labile fraction and the elevated concentrations of Zn (0.5 %) and Mn (0.7 %) in the sediments inside the reservoir raises concerns regarding the availability of these contaminants in the environment.

Conclusions

The main environmental impact appears to be concentrated in the Águas Claras reservoir, whereas the Antas creek does not seem to be affected by the AMD process. Although the bacterial sulfate reduction is effective in its production of sulfides capable of immobilizing the contaminants, the presence of Zn and U in the labile and reducible fraction is a matter of concern due to its long-term bioavailability. Thus, continuous monitoring of the redox potential of the waters and sediments, mainly in the reservoir, is recommended in order to assess and possibly prevent later dissolution of sequestered contaminants.

     

Interaction of common beans cultivars of the black group with years, locations and sowing seasons

The objectives of this study were to assess which environmental factors (local, season or years) are the most important to contribute for the interactions with genotypes of common black beans and to verify the existence of genotypes with broad and/or specific adaptation to the diverse planting seasons in Central Brazil. Data of grain yields for 13 genotypes in 18 field trials used for cultivar registration were utilized, across 2?years (2003 and 2004). Analyses of variance were carried out with decomposition of the genotype x environment interactions. Firstly, data of 18 trials were used, allowing a partial isolation of factors and, subsequently, eight trials were used to allow a complete isolation of the factors. The genotype x sowing seasons (R²?=?4.2?%) and genotype x year (R²?=?4.1?%) interactions were of the greatest important, while genotype x location was less important (R²?=?3.0?%). It was concluded that is more important to conduct evaluations of genotypes in different seasons and years rather than in different locations. The majority of the genotypes tested presented specific adaptation, although it was possible to identify superior lines with wide adaptation.     

Predictive value of prepartum serum metabolites for incidence of clinical and subclinical mastitis in grazing primiparous Holstein cows

The aim of this study was to measure changes in biochemical markers in the peripartum period of primiparous Holstein cows diagnosed with subclinical and clinical mastitis. In this study, 37 dairy cows were monitored daily during milking until 60 days postpartum and were categorized according to the occurrence of clinical mastitis (group mastitis (GM), n?=?9) or subclinical mastitis (group subclinical mastitis (GSUB), n?=?10) or absence of symptoms (control group (CG), n?=?18). Blood samples were collected weekly from ?30 to 60 days from calving. Samples were grouped for prepartum (?30 to 0 days from calving), early postpartum (0 to 30 days from calving), and late postpartum (30 to 60 days from calving) periods. Prepartum serum non-esterified fatty acid (NEFA) concentration was higher in GM than in CG (P?<?0.01). In addition, CG had higher prepartum serum glucose concentration than GM (P?=?0.03). In the early postpartum period, aspartate aminotransferase (AST) activity was lower in CG than in GSUB (P?<?0.05), and in the late postpartum period, AST activity was lower in CG than GSUB and GM (P?=?0.01). Somatic cell count was higher during the early and late postpartum periods for GM and GSUB when compared to CG (P?<?0.01). In this study, primiparous cows with low glucose and higher NEFA in the prepartum were more susceptible for mastitis in the early postpartum, probably due to low immune function associated to a more negative energy balance. In sum, increased prepartum serum NEFA concentration and decreased glucose in primiparous cows were associated with clinical mastitis incidence in the postpartum period.     

A laboratory protocol for determining glucose and maximum ethanol production from wheat grain: application to a complete genetic set of near-isogenic waxy lines

A laboratory protocol was developed to assess glucose and ethanol yields from wheat. The impact of the analyzed wholemeal flour quantity and the saccharification on the amount of released glucose was estimated. The whole process including the analytical methods (glucose and ethanol) was repeatable and reproducible. This protocol was used to assess the glucose and ethanol yields of six varieties and of a complete set of hexaploid near-isogenic waxy lines of cv. Trémie grown in three locations. As compared to the normal line of Trémie, double null (AnBnD) and triple null (nAnBnD) isogenic lines showed a low Hagberg falling number (218, 65, and 63 s, respectively), a higher grain protein content (10.7, 11.5, and 12.1% DM, respectively), a lower glucose yield (728, 703, and 707 kg/t, respectively), and a lower ethanol yield (463, 453, and 452 L/t, respectively). These values indicate a strong involvement of alleles encoded at Wx-B1 and Wx-D1 loci in grain composition.     

Profiles of sex steroids, fecundity and spawning of a migratory characiform fish from the Paraguay–Paraná basin: a comparative study in a three-river system

This study investigated for the first time the reproductive biology of Prochilodus lineatus in a system of rivers in southeastern Brasil, relating it to the role of tributary rivers in the reproductive success of this important commercial fish in the Upper Paraná River basin, where a cascade of hydroelectric dams were deployed. Specimens were caught bimonthly in three river sites: (S1) Grande River, downstream from the Porto Colômbia dam; (S2) Pardo River; and (S3) Mogi Guaçu River. Sex steroid plasma levels, fecundity, follicular atresia, oocyte diameter and gonadosomatic index (GSI) were compared among sites. In S1, fish exhibited changes in the reproductive parameters: lower GSI, oocyte diameter and fecundity and higher follicular atresia index, when compared to S2 and S3. Frequency of maturing fish was higher in S3 and spawning was only registered in S3. In sites S2 and S3, plasma concentrations of testosterone and 17β-estradiol in females and testosterone in males showed wide variations following gonadal maturation. Fish from S1 showed few significant variations in sex steroid concentrations throughout the gonadal cycle. These results indicate that P. lineatus does not reproduce in Grande River (S1), but probably uses the Pardo River (S2) as a migratory route towards the Mogi Guaçu River (S3) where they complete gonadal maturation and spawning. Our findings contribute for understanding the reproductive biology of P. lineatus and to highlight the importance of tributaries in impounded rivers as a favourable environment for migration and spawning of fish.     

Interactive effects of a high-quality protein diet and high stocking density on the stress response and some innate immune parameters of Senegalese sole Solea senegalensis

Amino acids (AA) regulate key metabolic pathways, including some immune responses. Therefore, this study aimed to assess whether an increased availability of dietary AA can mitigate the expected increase in plasma cortisol and metabolites levels due to high stocking density and its subsequent immunosuppression. Senegalese sole (Solea senegalensis) were maintained at low stocking density (LSD; 3.5 kg m^?2) or high stocking density (HSD; 12 kg m^?2) for 18 days. Additionally, both treatments were fed a control or a high protein (HP) diet (LSD, LSD HP, HSD and HSD HP). The HP diet slightly increased the levels of digestible indispensable AA, together with tyrosine and cysteine. HSD was effective in inducing a chronic stress response after 18 days of treatment since fish held at HSD presented higher plasma cortisol, glucose and lactate levels. Moreover, this increase in stress indicators translated in a decrease in plasma lysozyme, alternative complement pathway (ACP) and peroxidase activities, suggesting some degree of immunosuppression. Interestingly, while plasma glucose and lactate levels in HSD HP specimens decreased to similar values than LSD fish, plasma lysozyme, ACP and peroxidase activities increased, with even higher values than LSD groups for ACP activity. It is suggested that the HP diet may be used as functional feed since it may represent a metabolic advantage during stressful events and may counteract immunosuppression in sole.     

Synthesis and insecticidal activity of new 3-benzylfuran-2-yl N,N,N',N'-tetraethyldiamidophosphate derivatives

BACKGROUND: A series of 3-benzylfuran-2-yl N,N,N',N'-tetraethyldiamidophosphate derivatives were synthesized as potential new agents to control insects. Their structures were confirmed on the basis of IR, NMR and MS analyses. RESULTS: Ten 3-benzylfuran-2-ylN,N,N',N'-tetraethyl derivatives were prepared from the compound furan-2-yl N' (N,N,N',N'-tetraethyldiamidophosphate). The contact toxicity of all derivatives, at a dose of 10 microg mg(-1) insect, was evaluated against four insect species, Ascia monuste orseis Latr. (Lepidoptera: Pyralidae), Diaphania hyalinata (L.) (Lepidoptera: Pyralidae), Sitophilus zeamais Mots. (Coleoptera: Bruchidae) and Solenopsis saevissima (Smith) (Hymenoptera: Formicidae). The mortality range observed for some derivatives, such as 3-(3-methylbenzyl)furan-2-yl N,N,N',N'-tetraethyldiamidophosphate (82.5% mortality against D. hyalinata; 100% mortality against S. saevissima), was comparable with that of the commercial insecticide chlorpyrifos-methyl. The biological activity of the derivatives depended on the substitution pattern of the benzylic ring. Furan-2-yl N,N,N',N'-tetraethyldiamidophosphate, furan-2-yl N,N-diethylamidochlorophosphate and difuran-2-yl N,N-diethylamidophosphate were also evaluated, displaying, in some cases, activity comparable with that of chlorpyrifos-methyl (90%, 100% and 97.5% respectively against A. monuste orseis). Considerable activity was observed for some furan-2(5H)-ones evaluated. CONCLUSION: Ten 3-benzylfuran-2-yl N,N,N',N'-tetraethyldiamidophosphate derivatives were synthesized and fully characterized from a chemical point of view. The results obtained from the biological assays indicate that this class of compounds can be utilized for the design of new substances endowed with insecticidal activity.     

Environmental Behaviour of Metolachlor and Diuron in a Tropical Soil in the Central Region of Brazil

The environmental behaviour of metolachlor and diuron was studied in the Central-western region of Brazil, by means of a field study where six experimental plots were installed. The soil was classified as a Latosol, and the soil horizons were characterized. Sorption of metolachlor and diuron was evaluated in laboratory batch experiments. Metolachlor and diuron were applied to the experimental plots on uncultivated soil in October 2003. From this date to March 2004, the following processes were studied: leaching, runoff and dissipation in top soil. K _oc of metolachlor varied from 179 to 264 mL g^?1 in the soil horizons. K _oc of diuron in the Ap horizon was 917 mL g^?1, decreasing significantly in the deeper horizons. Field dissipation half-lives of metolachlor and diuron were 18 and 15 days, respectively. In percolated water, metolachlor was detected in concentrations ranging from 0.02 to 2.84 μg L^?1. In runoff water and sediment, metolachlor was detected in decreasing concentrations throughout the period of study. Losses of 0.02% and 0.54% of the applied amount by leaching and runoff, respectively, were observed confirming the high mobility of this herbicide in the environment. In percolated water, diuron was detected with low frequency but in relatively high concentrations (up to 6.29 μg L^?1). In runoff water and soil, diuron was detected in decreasing concentrations until 70 days after application, totalizing 13.9% during the whole sampling period. These results show the importance of practices to reduce runoff avoiding surface water contamination by these pesticides, particularly diuron.