Calcium can moderate changes on membrane structure and lipid composition in cowpea plants under salt stress

The effects of supplemental Ca²⁺ on membrane integrity and lipid composition of cowpea plants submitted to salt stress (75 mM NaCl) were evaluated. The experimental design was factorial (2 × 6 + 1) corresponding to six saline treatments supplemented with CaCl₂ and six saline treatments supplemented with CaSO₄, both at 0.5, 1.25, 2.5, 5.0, 7.5 and 10.0 mM, plus control treatment (plants grown in half-strength Hoagland’s nutrient solution without supplemental calcium addition). Samples of leaves and root tips were analyzed for total lipid, glycolipid and fatty acid contents and membrane damage symptoms. Salt stress greatly reduced total lipid content in leaves and roots and caused great damage to membrane structures. In leaves, the glycolipid content was differently influenced by calcium treatments. Moreover, salinity increased the saturated/unsaturated fatty acid ratio in leaves and an increase in the concentration of calcium intensified this response. In roots, only saturated fatty acids were detected and their content was strongly influenced by salinity and very little by calcium treatments. Supplemental Ca²⁺ was unable to ameliorate the negative effects of salinity on the structural integrity and fluidity of plant membranes in cowpea.     

Salt tolerance is unrelated to carbohydrate metabolism in cowpea cultivars

Under salinity stress, plants commonly accumulate carbohydrates for osmotic adjustment to balance the excess accumulated ions and to protect biomolecules. We selected two cowpea cultivars with contrasting response to salinity, Pitiúba (salt-tolerant) and TVu (salt-sensitive), to investigate whether the salt tolerance could be associated with changes in carbohydrate accumulation and metabolism in leaves and roots during a long-term experiment. Two salt treatments (0 and 75 mM NaCl) were applied to 10-day-old plants grown in nutrient solution for 24 days. Despite some changes in carbohydrate accumulation and carbohydrate metabolism enzymes induced by salt stress, no consistent alterations in carbohydrates could be found in leaves or roots in this study. Therefore, we suggest that tolerance to salt stress is largely unrelated to carbohydrate accumulation in cowpea.     

Water buffaloes (Bubalus bubalis) identified as an important reservoir of Shiga toxin-producing Escherichia coli in Brazil

The presence of Shiga toxin-producing Escherichia coli (STEC) in water buffaloes is reported for the first time in South America. The prevalence of STEC ranged from 0 to 64% depending on the farm. STEC isolates exhibiting the genetic profiles stx(1)stx(2)ehxA iha saa and stx(2)ehxA iha saa predominated. Of the 20 distinct serotypes identified, more than 50% corresponded to serotypes associated with human diseases.     

Calcium hypochlorite for removing stalks on eggs of the green lacewing Chrysoperla genanigra (Neuroptera: Chrysopidae)

The release of lacewings eggs in the field requires the removal of their silk stalk, otherwise the release is impaired, as the eggs can become entangled in these pedicels. This study evaluated the effect of three concentrations of chlorine solution associated with two different exposure times for removing the stalks of eggs of Chrysoperla genanigra Freitas, and on the hatchability of the treated eggs. The concentrations used were 0.0 (control), 2.0, 4.0, and 6.0 % chlorine granules of hth^®—containing as major components calcium hypochlorite and sodium chloride—dissolved in distilled water. The times used for each concentration were 60 and 120 s. Fifty eggs were used for each treatment. After each treatment, the eggs were washed in running water and then dried with a directed air flow. The best results were obtained with the concentrations of 2 % for 120 s and 4 % for 60 and 120 s, removing 100 % of stalks without reducing hatchability. At 6 %, egg destruction started to occur. We conclude that calcium hypochlorite can be used for removing stalks of C. genanigra eggs with no reduction in hatchability.     

Sequence variation of the alpha-lactalbumin gene in Holstein and Nellore cows

The alpha-lactalbumin is a subunit of lactose-synthase, an enzyme responsible for lactose production, a disaccharide that influences milk production. Sequence variations of bovine alpha -lactalbumin have been associated with differences in milk yield. This study aimed to analyze allelic frequency differences at position - 1689 (g. A > G) and + 15 (g. A > G) of the alpha-lactalbumin gene in Holstein (Bos taurus) and Nellore (Bos indicus) cows. Blood samples were analyzed from 34 Holstein, 104 Nellore, and 99 Dairy Nellore cows using PCR-RFLP. The different RFLP patterns were sequenced and a novel sequence variation on nucleotide - 46 was identified. An adenine at this position was designated as the A allele and a guanine was designated B allele. The frequencies of alleles A - 1689, A - 46, and A + 15 differed between Holstein and both Nellore breeds. The results show that differences in alpha-lactalbumin allelic variants in the 5'-flanking and the 5'-UTR region might be associated with differences in milk production between Holstein cows and cows from Nellore breeds. However, the lack of difference between Nellore and Dairy Nellore suggests that other sequence variantions that regulate milk production might be responsible for the selection of Dairy Nellore cows with superior milk production.     

Quantitative-Trait Loci Influencing Body-Mass Index Reside on Chromosomes 7 and 13: The National Heart, Lung, and Blood Institute Family Heart Study

Obesity is a risk factor for many chronic diseases, including glucose intolerance, lipid disorders, hypertension, and coronary heart disease. Even though the body-mass index (BMI) is a heterogeneous phenotype reflecting the amount of fat, lean mass, and body build, several studies have provided evidence of one or two major loci contributing to the variation in this complex trait. We sought to identify loci with potential influence on BMI in the data obtained from National Heart, Lung, and Blood Institute Family Heart Study. Two complementary samples were studied: (a) 1,184 subjects in 317 sibships, with 243 markers typed by the Utah Molecular Genetics Laboratory (UMGL) and (b) 3,027 subjects distributed among 401 three-generation families, with 404 markers typed by the Mammalian Genotyping Service (MGS). A genome scan using a variance-components-based linkage approach was performed for each sample, as well as for the combined sample, in which the markers from each analysis were placed on a common genetic map. There was strong evidence for linkage on chromosome 7q32.3 in each sample: the maximum multipoint LOD scores were 4.7 (P<10-5) at marker GATA43C11 and 3.2 (P=.00007) at marker D7S1804, for the MGS and UMGL samples, respectively. The linkage result is replicated by the consistent evidence from these two complementary subsets. Furthermore, the evidence for linkage was maintained in the combined sample, with a LOD score of 4.9 (P<10-5) for both markers, which map to the same location. This signal is very near the published location for the leptin gene, which is the most prominent candidate gene in this region. For the combined-sample analysis, evidence of linkage was also found on chromosome 13q14, with D13S257 (LOD score 3.2, P=.00006), and other, weaker signals (LOD scores 1.5-1.9) were found on chromosomes 1, 2, 3, 5, 6, 14, and 15.     

Isolation and characterization of soluble sulfated polysaccharide from the red seaweed Gracilaria cornea

The composition, structure and rheological properties of a soluble sulfated polysaccharide from Gracilaria cornea (Brazilian red marine alga) were investigated. Agarocolloid yield, intrinsic viscosity, monosaccharide composition, sulfate and cation content as well as molecular weight were determined. The main polysaccharide components were 3,6-anhydrogalactose (24.7%) and galactose (64.6%). In addition, minor components such as 6-O-methyl-galactose (8.5%), glucose (1.5%), xylose (0.7%) and sulfated groups (4.8%) were detected. Comparison between sulfate contents determined by Fourier transform IR (FT-IR) spectroscopy and microelemental analysis was made. Data from ¹³C NMR and FT-IR provided evidence of sulfation in C-4 and C-6 of galactose. Sodium, calcium, magnesium and potassium cations were detected in the agarocolloid. The intrinsic viscosities were lower than typical values for agar in the same experimental conditions. No gelation in 1.5, 2.0 and 3.0% (w/v) aqueous solution was observed, even by cooling up to 4 °C. Gel permeation chromatography indicated two major polysaccharide fractions of M_pk 7.4×10⁴ and 1.8×10⁴ g/mol and a minor fraction of M_pk 2.1×10⁶ g/mol, probably a protein–polysaccharide complex.     

The influence of thermal treatment and operational conditions on xanthan produced by X. arboricola pv pruni strain 106

The influence of thermal treatment and operational conditions (pH and stirrer speed) used in the process of xanthan production by Xanthomonas arboricola pv pruni strain 106 were evaluated through yield of xanthan, aqueous solution and fermentation broth viscosity, sodium content, pyruvate and acetyl content and molar mass. Different conditions used during the fermentation affected the xanthan characteristics. Thermal treatment decreased the final yield and pyruvate and acetyl content, and increased the xanthan aqueous solution and fermentation broth viscosities, as well as molar mass. In this study the best combination of yield and viscosity was obtained with the use of pH 7 and 400 rpm during fermentation and post-fermentation thermal treatment. Aggregation of xanthan molecules promoted by heating and detected through an increase of molar mass was apparently affected by the sodium content. As a result, a correlation between molar mass and xanthan solution viscosity could be observed.