Allometric growth patterns in hatchery-reared larvae of the catfish Lophiosilurus alexandri (Pisces: Pseudopimelodidae)

The aim of the present study was to characterize the relationships that occur between morphometric variables of larvae of Lophiosilurus alexandri Steindachner, 1876 through their allometric growth analysis. Total length, head length and body height were correlated with standard length, head height and body height, as well as eye diameter and head height with head length. The results revealed allometric positive relation during the initial development, where the b coefficient varied between 1.10 and 2.81. The variable pre-anal distance in relation to the standard length and the snout length in relation to the head length revealed an allometric negative relation, where the b coefficient was 0.85 and 0.94, respectively

Peptide labeling with lanthanide-NHS-ester-DOTA investigated by nano-HPLC

International audienceLabeling of peptides and proteins using chelators binding metal ions has become a novel approach for quantitative proteomics in recent years. The aim of this work was the optimization of a new method for peptide derivatization with lanthanide labels (holmium, lutetium, and thulium) followed by nano high performance liquid chromatography (nano-HPLC) separation with UV detection. Matrix-assisted laser desorption ionization-mass spectrometry (MALDI MS) was used to confirm the derivatization and to identify the derivatized peptides. Peptides were labeled with the three different lanthanide metals using a bifunctional DOTA-based (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) reagent. The results demonstrate that the derivatization reaction using the chelating reagent DOTA-NHS-ester was effective for single peptides and peptide mixtures. Furthermore, an efficient pre-cleaning method was applied by nano-HPLC using a C-18 trap column for elimination of the excess of labeling reagent. The application of the optimized method to label peptides in a Cytochrome C digest delivered comparable results to those obtained with model peptides. © 2014 Elsevier B.V

Development and standardization of a western blotting test for detection of antibodies against B. abortus

ABSTRACT Brucellosis is an infectious disease caused by bacteria of the genus Brucella spp. with diagnosis based on use of serological techniques. The present study aimed to develop and standardize a western blotting (WB) test for detection of antibodies against B. abortus. Samples from two groups of cattle were analyzed: group I: 60 serum samples from true positive and true negative vaccinated animals (30 positive samples from infected animals according to rose bengal test (RBT), 2-mercaptoethanol, serum agglutination test (SAT) and complement fixation test (CFT) and 30 RBT negatives samples); group II: 383 field samples (90 positive and 293 CFT negative sera). The most reactive band in the western blotting, which properly identified and separated infected from non - infected had a molecular weight of ≤ 20kDa. The sensitivity, specificity and accuracy of the WB compared to RBT was 93%, 99%, 98%, respectively and k= 0.938. When compared to CFT, the sensitivity, specificity and accuracy of the WB was 97%, 98% and 97%, respectively and k= 0.929. The WB developed and standardized in the present study is a serological test with potential use as a confirmatory test for the diagnosis of bovine brucellosis