A potyvirus vector efficiently targets recombinant proteins to chloroplasts,mitochondria and nuclei in plant cells when expressed at the amino terminus of the polyprotein

Plant virus‐based expression systems allow quick and efficient production of recombinant proteins in plant biofactories. Among them, a system derived from tobacco etch virus (TEV; genus potyvirus) permits coexpression of equimolar amounts of several recombinant proteins. This work analyzed how to target recombinant proteins to different subcellular localizations in the plant cell using this system. We constructed TEV clones in which green fluorescent protein (GFP), with a chloroplast transit peptide (cTP), a nuclear localization signal (NLS) or a mitochondrial targeting peptide (mTP) was expressed either as the most amino‐terminal product or embedded in the viral polyprotein. Results showed that cTP and mTP mediated efficient translocation of GFP to the corresponding organelle only when present at the amino terminus of the viral polyprotein. In contrast, the NLS worked efficiently at both positions. Viruses expressing GFP in the amino terminus of the viral polyprotein produced milder symptoms. Untagged GFPs and cTP and NLS tagged amino‐terminal GFPs accumulated to higher amounts in infected tissues. Finally, viral progeny from clones with internal GFPs maintained the extra gene better. These observations will help in the design of potyvirus‐based vectors able to coexpress several proteins while targeting different subcellular localizations, as required in plant metabolic engineering.     

The Influence of Sex Steroid Hormones in the Immunopathology of Experimental Pulmonary Tuberculosis

The relation between men and women suffering pulmonary tuberculosis is 7/3 in favor to males. Sex hormones could be a significant factor for this difference, considering that testosterone impairs macrophage activation and pro-inflammatory cytokines production, while estrogens are proinflammatory mediator’s inducer. The aim of this work was to compare the evolution of tuberculosis in male and female mice using a model of progressive disease. BALB/c mice, male and female were randomized into two groups: castrated or sham-operated, and infected by the intratracheal route with a high dose of Mycobacterium tuberculosis strain H37Rv. Mice were euthanized at different time points and in their lungs were determined bacilli loads, inflammation, cytokines expression, survival and testosterone levels in serum. Non-castrated male mice showed significant higher mortality and bacilli burdens during late disease than female and castrated male animals. Compared to males, females and castrated males exhibited significant higher inflammation in all lung compartments, earlier formation of granulomas and pneumonia, while between castrated and non-castrated females there were not significant differences. Females and castrated males expressed significant higher TNF-α, IFN γ, IL12, iNOS and IL17 than non-castrated males during the first month of infection. Serum Testosterone of males showed higher concentration during late infection. Orchidectomy at day 60 post-infection produced a significant decrease of bacilli burdens in coexistence with higher expression of TNFα, IL-12 and IFNγ. Thus, male mice are more susceptible to tuberculosis than females and this was prevented by castration suggesting that testosterone could be a tuberculosis susceptibility factor.     

Multi-Level Determinants of Parasitic Fly Infection in Forest Passerines

The study of myiasis is important because they may cause problems to the livestock industry, public health, or wildlife conservation. The ecology of parasitic dipterans that cause myiasis is singular, as they actively seek their hosts over relatively long distances. However, studies that address the determinants of myiasis dynamics are very scarce. The genus Philornis include species that may be excellent models to study myiasis ecology, as they exclusively parasitize bird nestlings, which stay in their nests until they are fully fledged, and larvae remain at the point of entry until the parasitic stage is over, thus allowing the collection of sequential individual-level infection data from virtually all the hosts present at a particular area. Here we offer a stratified multi-level analysis of longitudinal data of Philornis torquans parasitism in replicated forest bird communities of central Argentina. Using Generalized Linear Models and Generalized Linear Mixed Models and an information theory approach for model selection, we conducted four groups of analyses, each with a different study unit, the individual, the brood, the community at a given week, and the community at a given year. The response variable was larval abundance per nestling or mean abundance per nestling. At each level, models included the variables of interest of that particular level, and also potential confounders and effect modifiers of higher levels. We found associations of large magnitude at all levels, but only few variables truly governed the dynamics of this parasite. At the individual level, the infection was determined by the species and the age of the host. The main driver of parasite abundance at the microhabitat level was the average height of the forest, and at the community level, the density of hosts and prior rainfall. This multi-level approach contributed to a better understanding of the ecology of myiasis.     

Structure-activity studies of dermorphin. The role of side chains of amino acid residues on the biological activity of dermorphin

Seventeen analogues of dermorphin were synthesized and bio-assayed to determine the influence of side chains of the individual amino acid residues forming the sequence of dermorphin on the biological activity of this opioid peptide. Syntheses were carried out using solid-phase procedure, and the analogues obtained were purified by gel filtration on Sephadex G-10. Biological activities determined in guinea pig ileum (GPI) and mouse vas deferens (MVD) tests showed that the N-terminal tetrapeptide is responsible for the activity of dermorphin. Substitutions in the C-terminal fragment, particularly in position 5, for other amino acid residues results in substantial differentiation towards mu and delta receptors.     

Consanguinity analysis of congenital deafness in Northern Israel.

Consanguinity analysis of heterogeneous populations was performed on a group of 82 Israeli Jewish families with congenitally deaf probands, including 37 multiplex families with normal parents, 10 multiplex families with deaf parents, and 35 simplex families with deafness of unknown cause. Representative gene frequency was estimated as .0198, with two to four major gene loci per ethnic group. In both the simplex families and those with deaf parents, the only significant etiology found was homozygosity for pathologic recessive genes. Comparison of these findings in Israeli isolates with those in panmictic populations seems to imply that the genetic loci are not identical in the various isolates.     

Effect of 0.25 N sodium chloride treatment on DNA denaturation in situ in thymus lymphocytes

Extraction of cells with 0.25 N NaCl changes the profile of DNA denaturation in situ. The portion of DNA denaturing at lower temperatures (“thermosensitive” fraction) shows increased sensitivity to heat following salt extraction while the “thermoresistant” DNA fraction is further stabilized. The results suggest that proteins extractable with 0.25 N NaCl while providing local counterions for DNA phosphates of the “thermosensitive” DNA fraction also decrease the strength of DNA-histone interactions within the “thermoresistant” fraction.     

Multi-scale variability in tropical soil nutrients following land-cover change

The effects of land-cover change on soil properties have reached regional proportions in the southwestern Amazon, and can be detected in their patterns at the scale of hundreds of thousands of square kilometers. Spatial analysis of an extensive soil profile database revealed four nested spatial scales at which different patterns in soil properties occur: <3, <10, <68, and >68 km. The shortest scales account for the majority of the spatial variability in the biogeochemically important properties (phosphorus, nitrogen, organic carbon), while the longest scales explain the most for pedologic properties (pH, aluminum, percent clay and sand). The magnitude and sign of correlations among soil properties changed with scale, indicating major shifts in distribution and soil dynamics depending on the scale of observation and analysis. Precipitation, substrate composition, topography, and biological influences vary over large areas, leading to variable distribution of soil properties, and complicating the evaluation of the effect of deforestation on biogeochemical cycling. We modeled the relationships among scale-specific patterns in soil properties and the soil forming state factors to tease out the relative impact of changing land cover. Soil property short-scale variability corresponded with the distribution of land cover and terrain attributes, medium scale variation with geology and state soil map classifications, and long scale with geology and precipitation. The strength of these relationships may be partially attributable to the resolution of the maps used as proxies for the soil forming factors. Land-cover change has already left a discernable imprint on broad-scale soil nutrient patterns, although it is still not the dominant process.     

Genetic diversity of Plasmodium falciparum and its implications in the epidemiology of malaria

Genetic diversity provides Plasmodium falciparum with the potential capacity of avoiding the immune response, and possibly supporting the selection of drug or vaccine resistant parasites. These genetic characters play key roles in the selection of appropriate malaria control measures. Diverse clones of Plasmodium falciparum, often denoted as strains, has been documented, and the degree of genetic diversity supported by several kinds of PCR (polymerase chain reaction) assays. Many studies in different endemic regions with differences in their level of disease transmission have clarified the interactions between the parasite populations and malaria epidemiology. This paper describes recombination events of the malaria parasite life cycle that originate such genetic diversity in P. falciparum, reviewing different studies on this aspect and its implications in the immunity and development of control measures in regions with different degrees of endemicity.     

Genetic and morpho-physiological differentiation in a limpet population across an intertidal gradient

Marine organism adaptive capacity to different environmental conditions is a research priority to understand what conditions are important in structuring the spatial distribution of natural populations. In this context, this study evaluates whether potential differences in Siphonaria lessonii morphology (size and shell shape) and physiology (water loss regulation) at different shore heights are linked to genetically distinguishable individuals. To achieve this goal, we compared size-frequency distribution, morphometric, and genetic data (ISSR-PCR technique) of S. lessonii from the upper, middle and lower shore. We complemented these field samplings with laboratory experiments on water loss and mortality. Genetic analysis showed different genetic composition for individuals from the upper and lower shore. This pattern was accompanied by morpho-physiological variations: the upper shore had fewer small limpets, lower shell shape dispersion (with a morphotype characterized by a higher shell), and less water loss and mortality related to air exposure than the lower shore. The results reported herein support the idea that the extreme and unpredictable conditions of the upper shore may impose strong selection pressure on its inhabitants, leading to considerable morpho-physiological differentiation consistent with different genetic composition. This probably plays an important role in structuring the spatial distribution of natural S. lessonii populations with a possible effect on size-structure distribution.