The influence of eugenol, benzocaine and ice water on the welfare of adult grass carp (Ctenopharyngodon idella).

The aim of this study was to evaluate the effects of eugenol, benzocaine, and ice water during the sedative, anesthetic or euthanasia processes on the welfare of adult grass carp (Ctenopharyngodon idella). The experimental design was randomized and the animals were divided into eight groups. Sixty-two animals underwent an acclimation period. The neutral group used to obtain basal data of grass carp were not subjected to treatments, but anesthetized to collect blood samples and euthanized by medullary section. The others seven groups were submitted to seven treatments with eight repetitions (control group; ethanol; eugenol 50 mgL-1, eugenol 250 mgL-1, benzocaine 100 mgL-1, benzocaine 300 mgL-1, and ice water 2:1), their behavior was observed. Blood samples was collected and then euthanized by medullary sectioning. Biometric data were measured and a part of the liver was collected for hepatic glycogen analysis. There was a statistically significant difference in the time required to reach the anesthetic stage between the groups (p < 0.01). Benzocaine and eugenol at the higher concentration provided the fastest responses to sedatives and anesthetics, respectively. The animals subjected to higher anesthetic concentrations reached stage five and did not return from anesthesia, therefore, benzocaine and eugenol were effective euthanizing agents. Benzocaine at the lowest concentration showed the highest concentrations of glucose and cortisol (p < 0.05). Although benzocaine at 100 mgL-1 concentrations is widely used as an anesthetic in fish, this study demonstrated its use as a stressor agent. Basal data of grass carp for stress parameters are presented for the first time.

The compound paraquat dichloride hydrate significantly affects the in vitro growth rate of a Chromobacterium violaceum wild type strain / O composto hidrato-dicloreto de paraquat afeta a taxa de crescimento in vitro de uma cepa do tipo selvagem de Chromobaterium violaceum

Introduction: the toxicity of pesticides on bacterial cell growth is still limited. Objectives: The current study aimed to assess the in vitro growth rate of the C. violaceum wild type strain ATCC12472 exposed to the herbicide paraquat dichloride hydrate at different incubation times and final concentrations. Methodology: bacterial inocula were incubated in a nutrient broth medium containing the compound paraquat at final concentrations 100 and 1.000 µg mL-1 under aeration conditions. Spectrophotometric readings at different incubation times were carried out to estimate the in vitro bacterial growth rate. Moreover, the number of viable bacteria cells in the samples was also estimated in the presence of the paraquat at two concentrations tested based on colony-forming units grown on the nutrient broth agar. Results: significant decreases in the C. violaceum growth rate were detected, after one hour of paraquat exposure at a final concentration of 1,000 µg mL-1 (p<0.05) compared to all treatments tested. After two hours of paraquat exposure, significant decreases were progressively found at all final concentrations of 100 (p<0.01) and of 1,000 µg mL-1 (p<0.001). These data were also corroborated by counting the total number of colony-forming units at final concentrations tested. Conclusion: the findings described in current study suggest that the compound paraquat dichloride hydrate exerts significant effects on the in vitro growth rate of a C. violaceum wild type strain.

Introdução: a toxicidade de pesticidas sobre o crescimento de células bacterianas ainda é limitada. Objetivos: o presente estudo objetivou avaliar a taxa de crescimento in vitro de uma cepa selvagem de C. vilaceum ATCC12472 exposta ao herbicida hidratodicloreto de paraquat em diferentes tempos de incubação e concentrações finais. Metodologia: inóculos bacterianos foram incubados em um caldo nutritivo contendo o composto paraquat nas concentrações 100 e 1.000 µg mL-1 sob condições de aeração. Leituras espectrofotométricas em diferentes tempos de incubação foram realizadas para estimar a taxa de crescimento in vitro bacteriano. Além disso, o número de células bacterianas viáveis nas amostras foi também estimado na presença do paraquat nas duas concentrações testadas, baseado no número de unidades formadoras de colônias crescidas em meio nutritivo ágar. Resultados: diminuições significativas na taxa de crescimento da C. violaceum foram detectadas, após uma hora de exposição ao paraquat na concentração final de 1.000 µg mL-1 (p<0,05) em comparação aos demais tratamentos testados. Com duas horas de exposição ao paraquat, diminuições significativas foram progressivamente encontradas em todas as concentrações finais de 100 (p<0,01) e de 1.000 µg mL-1 (p<0,001). Tais dados foram corroborados pela contagem do número total de unidades formadoras de colônias nas concentrações analisadas. Conclusão: as descobertas descritas aqui sugerem que o composto hidrato-dicloreto de paraquat exerce efeitos significativos sobre a taxa de crescimento in vitro de uma cepa selvagem da bactéria C. violaceum

Methods for the evaluation of antibiotic resistance in Lactobacillus isolated from fermented sausages / Comparação de métodos para avaliação de resistência microbiana em Lactobacillus isolados de embutidos fermentados

ABSTRACT: The present study aimed to assess the antibiotic resistance in 54 indigenous Lactobacillus plantarum isolated from artisanal fermented sausages. The confirmation of the strain species was performed by multiplex-PCR assay. Antibiotic resistance was assessed by disk diffusion (DD) and Minimum Inhibitory Concentration (MIC) methods. Of 54 L. plantarum, 44 strains were genotypically confirmed as L. plantarum and 3 as Lactobacillus pentosus. The highest resistance rates were to ampicillin and streptomycin. The highest susceptibility rates were shown to tetracycline, chloramphenicol and penicillin G. None of the strains showed multidrug resistance. Resistance rates by DD and MIC were not different (P>0.05) for ampicillin, chloramphenicol, erythromycin and penicillin G. Future research should assess the genetic mechanisms underlying the phenotypic resistance in Lactobacillus strains to screen the potential probiotic strains for the development of functional meat products.

RESUMO: O presente estudo teve como objetivo avaliar a resistência a antibióticos, de 54 cepas nativas de Lactobacillus plantarum isoladas de salames artesanais. A confirmação genotípica da espécie foi realizada por ensaio de PCR multiplex. A resistência aos antibióticos foi avaliada pelos métodos de disco difusão e concentração inibitória mínima. Das 54 cepas, 44 foram confirmadas genotipicamente como L. plantarum e 3 como Lactobacillus pentosus. As maiores frequências de resistência foram para ampicilina e estreptomicina, e as maiores frequências de sensibilidade para tetraciclina, cloranfenicol e penicilina G. Nenhuma das cepas apresentou multirresistência. As frequências de resistência para ampicilina, cloranfenicol, eritromicina e penicilina G foram semelhantes pelos métodos testados (P>0,05). Pesquisas futuras devem ser realizadas para avaliar os mecanismos genéticos envolvidos na resistência fenotípica das cepas de Lactobacillus, no intuito de selecionar as potenciais cepas probióticas para aplicação em produtos cárneos funcionais.

Treponemes detected in digital dermatitis lesions in Brazilian dairy cattle and possible host reservoirs of infection.

The main pathogenic treponemes causing bovine digital dermatitis were identified from 17 infected herds in southern Brazil for the first time in this study using PCR. We did not find a relationship between treponeme phylogroup composition and clinical classification. Treponema phagedenis was present in all lesions. Rumen fluid was implicated as a reservoir location for these pathogens.

New method for early detection of two random amplified polymorphic DNA (RAPD) groups of Staphylococcus aureus causing bovine mastitis infection in Paraná State, Brazil

The aim of this work was to develop a fast and accurate molecular approach to allow early detection of two RAPD groups of S. aureus causing bovine mastitis. Seventy five S. aureus isolates from infected animals were characterized by RAPD. Genomic fragments isolated from the unique bands present in either group were cloned and sequenced. Based on the DNA sequences, specific primers were designed to allow for the simultaneous detection of either group by multiplex PCR of S. aureus DNA isolated from clinical and subclinical bovine mastitis. Results showed that these proposed primers set could be used to detect various clinical and subclinical S. aureus isolates as well as the detection of the microorganism in bulk milk. Their use as a specific method for effective and early diagnostic tool for S. aureus infection in dairy herds is suggested.

Esta pesquisa objetivou o desenvolvimento de técnica rápida e eficiente para diagnosticar precocemente diferentes linhagens de S. aureus causadoras de mastite bovina. Como resultados da metodologia empregada, foram isoladas duas linhagens destas bactérias que causam diferentes tipos de mastite bovina. Os fragmentos de DNA genômico caracterizando ambas as linhagens, por meio de RAPD foram inseridos em vetor plasmidial pGEM e clonados por meio de clones T10 F1 de Escherichia coli. As seqüências obtidas permitiram desenhar iniciadores específicos para o reconhecimento de ambas as linhagens, os quais foram testados com amostras de S. aureus e com outras linhagens próximas. O diagnóstico por meios moleculares, pode ser realizado diretamente de amostras coletadas de rebanhos leiteiros assim como dos equipamentos de ordenha. A significância deste estudo consiste em um rápido e acurado método para localizar animais infectados, representando importante ferramenta no manejo do rebanho, na redução de custos com tratamentos e, rápida recuperação de rebanhos infectados.

Regulation of gene expression in Mycoplasmas: contribution from Mycoplasma hyopneumoniae and Mycoplasma synoviae genome sequences

This report describes the transcription apparatus of Mycoplasma hyopneumoniae (strains J and 7448) and Mycoplasma synoviae, using a comparative genomics approach to summarize the main features related to transcription and control of gene expression in mycoplasmas. Most of the transcription-related genes present in the three strains are well conserved among mycoplasmas. Some unique aspects of transcription in mycoplasmas and the scarcity of regulatory proteins in mycoplasma genomes are discussed.