Morphological and biochemical changes of salmonella hadar exposed to aqueous garlic extract / Cambios morfológicos y bioquímicos de salmonella hadar expuestas a extracto acuoso de ajo

The effect on Salmonella hadar growth was investigated using fresh sterile liquid medium (Pronadisa, Hispanlab) containing aqueous garlic extract (AGE) at different concentration (0, 11, 12, and 13 mg/ml). The garlic extract added at these final concentrations had a bacteriostatic effect on Salmonella hadar. The effect of these bacteriostatic concentration of AGE on the growth of the tested serovar, revealed a pattern of inhibition characterized by: (i) a transitory inhibition phase whose duration was proportional to AGE concentration (ii) a resumed growth phase which showed a lower rate of growth than in uninhibited controls, and (iii) an entry into stationary phase at a lower culture density. The minimal inhibitory concentration and minimum bactericidal concentrations were very close, garlic MIC was 12 mg/ml and the MBC was 14 mg/ml. Among enzymatic activities followed with the API-ZYM system, significant changes during the inhibition phase were detected. These biochemical changes represent an adaptative response towards the garlic stress. Some cellular enzymatic activities disappeared, whereas others were induced or maintained after AGE addition. TEM images of the samples treated with the bacteriostatic concentration of AGE (12 mg/ml) revealed the rupture of cell walls and nonhomogeneous disposition of cytoplasmic materials within treated bacteria.

El efecto sobre el crecimiento de Salmonella hadar fue investigado utilizando un medio líquido estéril fresco (Pronadisa, Hispanlab) conteniendo el extracto acuoso de ajo (EAA) en diferentes concentraciones (0, 11, 12 y 13 mg/ml). El extracto de ajo añadido con estas concentraciones tuvo un efecto bacteriostático sobre Salmonella hadar. La prueba serovar reveló un patrón de inhibición caracterizado por: (i) una fase de inhibición transitoria cuya duración fue proporcional a la concentración de EAA, (ii) una reanudación de la fase de crecimiento, la cual mostró una tasa más baja de crecimiento que controles sin inhibición, y (iii) una ingreso en fase estacionaria con una menor densidad de cultivo. La concentración mínima inhibitoria (CMI) y la concentración mínima bactericida (CMB) fueron muy cercanas, la CMI de ajo fue de 12 mg/ml y la CMB fue de 14 mg/ml. Las actividades enzimáticas seguidas con el sistema API-ZYM, mostraron cambios significativos durante la fase de inhibición. Estos cambios bioquímicos representan una respuesta adaptativa al estrés del ajo. Algunas actividades enzimáticas celulares desaparecieron, mientras que otras fueron inducidas o mantenidas después de la adición de EAA. Las imágenes de MET de las muestras tratadas con la concentración del bacteriostático EAA (12 mg/ml) revelaron la ruptura de las paredes celulares y la disposición no homogénea de materiales citoplasmáticos dentro de las bacterias tratadas.

Refined mapping of the autosomal recessive non-syndromic deafness locus DFNB13 using eight novel microsatellite markers.

The locus for a type of an autosomal recessive non-syndromic deafness (ARND), DFNB13, was previously mapped to a 17-cm interval of chromosome 7q34-36. We identified two consanguineous Tunisian families with severe to profound ARND. Linkage analyses with microsatellites surrounding the previously identified loci detected linkage with markers corresponding to the DFNB13 locus in both families. Haplotype analyses assigned this locus to a 3.2-Mb region between markers D7S2468 and D7S2473. In order to refine this interval, we identified nine dinucleotide repeats in the 7q34 region. To investigate the polymorphism of these repeats, a population study of 74 unrelated individuals from different regions of Tunisia was carried out. Our results demonstrated that eight of the nine repeats are polymorphic. The average number of alleles at these informative loci was 9.12 with a polymorphism information content of 0.71. Little evidence for linkage disequilibrium between some marker pairs was found. Haplotype analysis using these microsatellites refined the DFNB13 interval to an area of 2.2 Mb between the D7S5377 and D7S2473. In order to identify the DFNB13 gene, we sequenced and eliminated three candidate genes. Other known and predicted genes are being screened for deafness-causing mutations.

Contribution of blotting techniques to the study of rapeseeds (Brassica napus L.) lipases.

A recent advance in the study of plant lipases involving immunological techniques is presented. In an attempt to characterize lipases of cotyledons from germinating rapeseed seedlings and to investigate an eventual cross-reactivity with animal lipases, we have prepared anti-porcine pancreatic lipase antibodies raised in rabbit. It is shown by enzyme-linked immunosorbent assay and dot-blotting that these antibodies react with lipases in the rapeseed crude extract and in the different cellular fractions obtained by differential centrifugation. Preincubation of the antiserum with the rapeseed crude extract affects the amount of antibodies binding to the porcine pancreatic lipase. We demonstrate immunochemical cross-reactivity between rapeseed and porcine pancreatic lipase. Using the immunoblotting procedure, it is found that antibodies bind specifically to a single polypeptide with a molecular mass of about 55 kDa. Rapeseed lipase activity decreased after immunoprecipitation suggesting that antibodies were bound to some catalytic site residues. We conclude from the data obtained in this study that the two different lipase species present close similarities in amino acid sequence and antigen characteristics.

Evidence of cross-reactivity between porcine pancreatic and rapeseed (Brassica napus L.) lipases.

A cross-reactivity between animal and plant lipases was determined, using immunological techniques. It was shown by ELISA and dot-blotting that these antibodies react with lipases in the rapeseed crude extract and in the different cellular fractions obtained by differential centrifugation. Pre-incubation of the antiserum with the rapeseed crude extract affects the amount of antibodies binding to the porcine pancreatic lipase. Antibodies were able to precipitate lipase activity from 3-day-old rapeseed crude extract. These epitopes seem to be located in the catalytic site, suggesting that a consensus sequence exists in oleaginous lipases and that it will be universal.