Immune response to BCG-Moreau (Rio de Janeiro) strain. Spectrum of delayed hypersensitivity in genetically defined mice

Abstract Generation of delayed hypersensitivity (DTH) in genetically defined mice immunized with Mycobacterium bovis BCG of the Moreau (Rio de Janeiro) strain was studied. This vaccine strain has been reported as the most virulent and able to induce strong tuberculin sensitivity. Mice were selected by the expression of Bcg gene trait, by responsiveness to mycobacterial antigens and H2 haplotype. DTH was evaluated by the ear-swelling test of mice immunized subcutaneously with live BCG at doses ranging from 1 μg to 1000 μg. A survey of inbred strains of mice showed H2b and H2q mice as high responders, H2d as an intermediate responder, H2k as a low responder and H2a as a non-responder. Study of H2-congenic pairs of high and non-responder strains showed significant DTH in all mice independently of the genetic background and H2 haplotype. A mouse strain expressing Bcg (r) trait displayed DTH superior to a Bcg (s) strain. Comparison of DTH response of strains expressing Bcg (r) or (s) trait showed no relationship between the Bcg locus and DTH to mycobacteria. These data suggest DTH is under polygenic control including the major histocompatibility complex but excluding the Bcg locus.     

Evolutionary Consequences of Predation for Pathogens in Prey

This article investigates the impact of predation on the coexistence and competitive exclusion of pathogen strains in the prey. Two types of predator are considered—a generalist and a specialist. For each type of predator, we assume that the predator can discriminate among susceptible and infected with each strain prey. The two strains will competitively exclude each other in the absence of predation with the strain with the larger reproduction number persisting. If a generalist predator preys discriminantly and the disease is fatal, then depending on the predation level, a switch in the dominant pathogen may occur. Thus, for some predation levels, the first strain may persist while for other predation levels the second strain may persist. Furthermore, a specialist predator preying discriminantly may mediate the coexistence of the two strains. Although in most cases increasing predation reduces the disease load in the prey, when predation leads to coexistence, it may also lead to increase in the disease load.     

Ribosome origins: The relative age of 23S rRNA Domains

The modern ribosome and its component RNAs are quite large and it is likely that at an earlier time they were much smaller. Hence, not all regions of the modern ribosomal RNAs (rRNA) are likely to be equally old. In the work described here, it is hypothesized that the oldest regions of the RNAs will usually be highly integrated into the machinery. When this is the case, an examination of the interconnectivity between local RNA regions can provide insight to the relative age of the various regions. Herein, we describe an analysis of all known long-range RNA/RNA interactions within the 23S rRNA and between the 23S rRNA and the 16S rRNA in order to assess the interconnectivity between the usual Domains as defined by secondary structure. Domain V, which contains the peptidyl transferase center is centrally located, extensively connected, and therefore likely to be the oldest region. Domain IV and Domain II are extensively interconnected with both themselves and Domain V. A portion of Domain IV is also extensively connected with the 30S subunit and hence Domain IV may be older than Domain II. These results are consistent with other evidence relating to the relative age of RNA regions. Although the relative time of addition of the GTPase center can not be reliably deduced it is pointed out that the development of this may have dramatically affected the progenotes that preceded the last common ancestor.     

A Semivolatile Floral Scent Marks the Shift to a Novel Pollination System in Bromeliads

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Atrazine,desethylatrazine (DEA) and desisopropylatrazine (DIA) degradation by Pleurotus ostreatus INCQS 40310

Abstract

Atrazine is the most common herbicide applied in crops of economic relevance, such as sugar cane, soybean, and corn. Atrazine and its derivatives desethylatrazine (DEA) and desisopropylatrazine (DIA) are toxic to the environment, affecting animal and human health. Thus, this study aimed to evaluate the degradation of atrazine and its derivatives by the fungus Pleurotus ostreatus INCQS 40310, as well as the potential of the enzymes involved in this process. P. ostreatus INCQS 40310 was able to degrade atrazine (82%), DEA (71%), and DIA (56%) over 22?days of fungal cultivation. Proteomic analysis indicated the participation of hydrolases and peroxidases during the degradation process. Additionally, resting cells of the fungus were tested to verify the action of intracellular enzymes in the degradation process, suggesting the participation of cytochrome P450 enzymatic complex. Resting cells experiments promoted the degradation of 50% of atrazine, 36% of DIA, 30% of DEA. So far, this is the first work evaluating the biodegradation of DEA and DIA by fungus.