Coastal zone use and migratory behaviour of the southern population of Mugil liza in Brazil

We analysed the ratios Sr:Ca and Ba:Ca in the otoliths of 55 adults of the southern population of Mugil liza in Brazil (Paraná to Rio Grande do Sul) to investigate its coastal zone use and migratory behaviour. All individual M. liza analysed had Sr:Ca and Ba:Ca values indicating that their birth was in the marine environment, which is consistent with the southern population migration to spawn in the ocean,. Juveniles exhibited at least three coastal use and recruitment strategies (contingents): the majority (89%) of M. liza juveniles migrated toward brackish water. They entered the estuary before completing the first year of life (64%) or after (25%) their first year of life. The remaining 11% did not appear to enter brackish or freshwater water as a nursery or at any point in their life cycle. Some adults returned to the estuary after spawning in the ocean but others (of both sexes) never returned to the estuary after spawning, remaining in the marine environment. The pattern of juvenile habitat use in the Brazilian southern population of M. liza seems to be recurrent throughout the extent of its distribution as a consequence of the reproductive spawning aggregation behaviour, which mixes all contingents (with marine or estuarine preferences).     

Evolution in Fast Forward: a Potential Role for Mutators in Accelerating Staphylococcus aureus Pathoadaptation

Pathogen evolution and subsequent phenotypic heterogeneity during chronic infection are proposed to enhance Staphylococcus aureus survival during human infection. We tested this theory by genetically and phenotypically characterizing strains with mutations constructed in the mismatch repair (MMR) and oxidized guanine (GO) system, termed mutators, which exhibit increased spontaneous-mutation frequencies. Analysis of these mutators revealed not only strain-dependent increases in the spontaneous-mutation frequency but also shifts in mutational type and hot spots consistent with loss of GO or MMR functions. Although the GO and MMR systems are relied upon in some bacterial species to prevent reactive oxygen species-induced DNA damage, no deficit in hydrogen peroxide sensitivity was found when either of these DNA repair pathways was lost in S. aureus. To gain insight into the contribution of increased mutation supply to S. aureus pathoadaptation, we measured the rate of α-hemolysin and staphyloxanthin inactivation during serial passage. Detection of increased rates of α-hemolysin and staphyloxanthin inactivation in GO and MMR mutants suggests that these strains are capable of modifying virulence phenotypes implicated in mediating infection. Accelerated derivation of altered virulence phenotypes, combined with the absence of increased ROS sensitivity, highlights the potential of mutators to drive pathoadaptation in the host and serve as catalysts for persistent infections.     

Lasalocid-catalyzed proton conductance in Streptococcus bovis as affected by extracellular potassium

The effect of extracellular potassium on lasalocid-catalyzed proton conductance in Streptococcus bovis 24 was measured by using the fluorescent probe 9-aminoacridine. Increasing external potassium concentration resulted in decreased proton flux into S. bovis cells exposed to the ionophore. These results suggest that lasalocid catalyzes K+/H+ exchange diffusion in S. bovis cells.     

Activation of latent collagenase from polymorphonuclear leukocytes by oxygen radicals

Polymorphonuclear leukocytes (PMN) accumulating at inflammatory sites have the potential to degrade collagen by releasing the metalloproteinase collagenase (EC 3.4.24.7), which is stored within the specific granules of these cells in a latent, inactive, form. In order to elucidate the activation mechanism the latent enzyme (molecular weight 91,000) was purified from human PMN and incubated with the oxygen radical-generating system of xanthine oxidase (EC 1.1.3.22) and hypoxanthine. This coincubation resulted in the activation of the latent enzyme as assessed by the collagenolytic attack on human and bovine cartilaginous tissue. Two parameters for collagenolysis were used: loss of hydroxyproline-containing fragments, and mechanical measurements reflecting the stability of tissue specimens. Superoxide dismutase (EC 1.15.1.1) as well as catalase (EC 1.11.1.6) were capable of inhibiting the activation of latent PMN collagenase by the oxygen radical-generating system. The results indicate the hydroxyl radical to be the final oxidant responsible for the activation of latent PMN collagenase. Thus a new activation mechanism of latent collagenase is presented in this paper and discussed together with the potential relevance in pathophysiologic states of acute and chronic inflammation.     

Migration and reproductive biology of Mugil liza (Teleostei: Mugilidae) in south Brazil

The mullet Mugil liza occurs along the Atlantic coast of South America from Venezuela to Argentina, but 95% of the commercial catch is collected from south Brazil between São Paulo and Argentina. Mugil liza is a single spawner with oocyte development occurring synchronously in two groups. Spawning happens in marine areas and occurs after migration. The reproductive migration occurs from Argentina (38° S) to the southern Brazilian states (24–26° S) from April to July, with peak spawning in June between northern Santa Catarina and Paraná. The presence of hyaline oocytes was associated with high salinity and sea surface temperatures of 19–21° C, and followed the seasonal northward displacement of these oceanographic conditions. The average size at first maturity (L_m) for both sexes was 408·3 mm total length, L_T. Males (L_m = 400·1) matured earlier than females (L_m = 421·9 mm). Fecundity ranged from 818 992 to 2 869 767 oocytes (mean = 1 624 551) in fish that were between 426 and 660 mm L_T.     

A unique glycosyltransferase involved in the initial assembly of Moraxella catarrhalis lipooligosaccharides

Moraxella catarrhalis express three predominant forms of lipooligosaccharide (LOS) molecules on the bacterial surface. These major glycolipids contain specific carbohydrate epitopes that distinguish each glycoform into serotype A, B, or C LOS. All three serotypes, however, share a common glucose containing inner-core structure, consisting of an alpha-glucose attached to 2-keto-3-deoxyoctulosonic acid (KDO), which is unique among Gram-negative bacteria. Many of the LOS glycosyltransferase genes (lgt) responsible for assembly of the extended M. catarrhalis LOS structure have been identified. In this report, we now describe the identification and characterization of Lgt6, a unique glycosyltransferase that is responsible for the addition of the first glucose to the inner core thus initiating the assembly of full length LOS. Isogenic mutants defective in the expression of lgt6 were constructed in all three M. catarrhalis LOS serotypes and the resulting LOS glycoforms consisted of KDO(2)-lipid A-OH as analyzed by urea sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry. In addition, the expression of lgt6 in trans in a heptose-deficient Neisseria meningitidis NMB gmhX mutant resulted in the addition of a hexose to the LOS of this strain. These studies demonstrate that Lgt6 functions as an alpha-(1-5)-glucosyltransferase in M. catarrhalis adding the primary glucose to the KDO(2)-lipid A-OH in LOS biosynthesis. The function of Lgt6 is required for the completion of both the major and minor oligosaccharide chains in M. catarrhalis.     

Central obesity and health-related factors among middle-aged men: a comparison among native Japanese and Japanese-Brazilians residing in Brazil and Japan

The objective of this study was to investigate the influence of different cultural environments on the development of obesity by examining the association of central obesity, lifestyle, and selected coronary risk factors among people with identical Japanese genetic backgrounds living in Japan and Brazil. One hundred and four native Japanese and 286 Japanese-Brazilians residing in Brazil and Japan aged 35 years or over were studied. Obesity, metabolic risk factors for coronary disease, and history of regular sports activity, daily physical activity, and eating habits were assessed. The results showed Japanese-Brazilians residing in Brazil with significantly higher waist circumference values, and greater prevalence of central obesity compared to native Japanese and Japanese-Brazilians residing in Japan. The risk of developing central obesity was found to be 2.8 times higher among Japanese-Brazilians residing in Brazil. However, this association was no longer found to be significant after adjusting for lifestyle factors in the logistic model. Additionally, waist circumference was found to be significantly associated with metabolic risk factors for coronary disease. These findings suggest substantial variation in measures of central obesity among the three groups of Japanese ancestry, and underscore the heterogeneity of risk factors among communities of Japanese ancestry living in different cultural environments. The results also suggest that immigrant men exposed to the Brazilian cultural environment are more susceptible to the development of central obesity, and it seems to be associated with various lifestyle items and metabolic risk factors for coronary disease.     

An In-Depth Examination of Perceptions of Physical Activity in Regularly Active and Insufficiently Active Older African American Women: A Participatory Approach

Despite considerable research and programmatic efforts to alleviate racial/ethnic disparities in physical activity (PA), disparities in PA among older minorities and major racial ethnic groups persist. This study explored perceptions of PA among regularly active (RA) and insufficiently active (IA) older African American women (AAW) and the factors that influence (positively and negatively) their physical participation in their socio-cultural environment. A total of 20 AAW aged 60 to 80 years participated in a cross-sectional mixed-methods study (i.e., qualitative and quantitative) employing participatory research approaches (i.e., photoelicitation) along with an objective assessment of PA. Nine women were considered RA and 11 IA according to current PA recommendations. RA and IA women held two major beliefs about the nature of PA (i.e., PA as a broadly defined construct that goes beyond traditional exercise routines; and PA and exercise are synonymous and can be used interchangeably) and had a good understanding of its benefits. Participants in both groups did not know about the importance of PA intensity for health benefits. Barriers and facilitator of PA were found to be similar among RA and IA participants. Special attention should be paid to providing access to no or low cost opportunities for PA participation in safe environments.     

Lasalocid-catalyzed proton conductance in Streptococcus bovis as affected by extracellular potassium.

The effect of extracellular potassium on lasalocid-catalyzed proton conductance in Streptococcus bovis 24 was measured by using the fluorescent probe 9-aminoacridine. Increasing external potassium concentration resulted in decreased proton flux into S. bovis cells exposed to the ionophore. These results suggest that lasalocid catalyzes K+/H+ exchange diffusion in S. bovis cells.