Phlebotominae in peri‐domestic and forest environments inhabited by Alouatta caraya in northeastern Argentina

Multiple species of Phlebotominae are vectors of Leishmania (Protozoa: Trypanosomatidae), which causes visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL). To describe the Phlebotominae (Diptera: Psychodidae) related to the environments of black and gold howler monkeys Alouatta caraya (Humbodlt, 1812) (Primates: Atelidae), potential vectors were sampled in different landscapes and vertical strata of sleeping trees. Phlebotomine captured between December 2011 and March 2012 (2365 individuals) belonged to eight species, of which Nyssomyia neivai (Pinto, 1926) (61.4%) and Migonemyia migonei (França, 1920) (18.73%) were the most abundant, and Ny. withmani was recorded for the first time in the Chaco province. In the ‘peri‐domestic’ landscape, the phlebotomine were mainly captured in henhouses (78.7%), whereas the tree canopy in ‘rural’ and ‘wild’ landscapes yielded 31.2% and 29.1% of the phlebotomine, respectively. A significant association between the type of landscape and the species of phlebotomine was observed by multivariate analysis. Lutzomyia longipalpis (Lutz & Neiva, 1912) and Mg. migonei were associated with ‘peri‐domestic’ landscape, and Ny. neivai was associated with the ‘wild’ landscape. The results of this prospective study suggest that the interaction between phlebotomine and A. caraya could be a key factor with respect to understanding the epidemiology of leishmaniasis.     

Involvement of a protein with molybdenum cofactor in the in vitro activation of nitrate reductase from a chlA mutant of Escherichia coli K12

Chlorate-resistant mutants are pleiotropically defective in molybdoenzyme activities. The inactive derivative of the molybdoenzyme, respiratory nitrate reductase (nitrite: (acceptor) oxidoreductase, EC 1.7.99.4), which is present in cell-free extracts of chlA mutants can be activated by addition of purified protein PA, the presumed active product of the chlA+ locus, but the activity of the purified protein PA is low, since comparatively large amounts of protein PA are required for the activation. Addition of 10 mM tungstate to the growth medium of a chlBchlC double mutant leads to inactivation of both the molybdenum cofactor and protein PA. Protein PA prepared from such cells was unable to potentiate the in vitro activation of nitrate reductase present in the soluble fraction of a chlA mutant. Quantitation of inactive protein PA was determined immunologically using protein PA-specific antiserum. When a heat-treated extract of a wild-type strain was added to purified protein PA or to the supernatant fraction of a chlBchlC double mutant grown with tungstate, a large stimulation in the ability of these preparations to activate chlA nitrate reductase was found. We equate the activator of protein PA with molybdenum cofactor because: (1) both are absent from heated extracts of tungstate-grown chlBchlC double mutant and cofactor defective chlA and chlE mutants; (2) both are present in heated extracts of wild-type strain; and (3) they behave identically on molecular-sieve columns.     

Localized and transient changes in plasma membrane fluidity during in vitro myoblast fusion: an 1H-NMR study.

High resolution proton NMR was used to study the cell surface molecular events which take place during in vitro myoblast differentiation and fusion. The CH3 and (CH2)n spectral signals were followed throughout in vitro myogenic development. The results show that although both the T1 and T2 relaxation times of the CH3 and (CH2)n groups are sensitive to the fusion process, T1 is the most sensitive. Both T1 of CH3 and (CH2)n increased before fusion indicating a higher degree of molecular motion and then returned to their original values. These results demonstrate how mobile lipid domains observed with proton NMR can be used to study the changes taking place during myoblast differentiation, particularly myoblast membrane fusion.     

Phenotypically normal transgenic T-cyt tobacco plants as a model for the investigation of plant gene expression in response to phytohormonal stress

The tumour-inducing T-DNA gene 4 (T-cyt gene) of the nopaline Ti plasmid pTiC58 was cloned and introduced into tobacco cells by leaf disc transformation using Agrobacterium plasmid vectors. Tobacco shoots exposed to elevated cytokinin levels were unable to develop roots and lacked apical dominance. Using exogenously applied phytohormone manipulations we were able to regenerate morphologically normal transgenic tobacco plants which differed in endogenous cytokinin levels from normal untransformed plants. Although T-cyt gene mRNA levels, as revealed by dot-blot hybridization data, in these rooting plants were only about half those in primary transformed shoots the total amount of cytokinins was much lower than in crown gall tissue or cytokinin-type transformed shoots as reported by others. Nevertheless the cytokinin content in T-cyt plants was about 3 times greater than in control tobacco plants.Elevated cytokinin levels have been shown to change the expression of several plant genes, including some nuclear genes encoding chloroplast proteins. Our results show that the mRNA levels of chloroplast rbcL gene increase in cytokinin-type transgenic tobacco plants as compared with untransformed plants. Data obtained suggest that T-cyt transgenic plants are a good model for studying plant gene activity in different parts of the plant under endogenous cytokinin stress.     

Increase in the immunogenicity of cancer cells exposed to microwaves

A suspension of 10(7) melanoma cells, submitted to microwave hyperthermia (2,450 MHz, 20 minutes, 44 degrees C) leads to a partial protection in mice inoculated 26 days afterwards with a suspension of 10(7) active cells of B16 melanoma (95% vitality). The period of 26 days between the two injections corresponds to the moment where the sera antibodies have an highest level. The kinetics of the primary response of the humoral immunity shows that B16 melanoma proliferation and number of deads can be related to an hypogammaglobulinemia.     

Effect of methylation of histidine-48 on some enzymatic and pharmacological activities of snake venom phospholipases A2

The effects on some pharmacological and enzymatic properties were determined following methylation of histidine at the enzymatic active site of the basic relatively toxic $\text{Naja}$$\text{nigricollis}$ and the acidic relatively non-toxic $\text{Naja}$$\text{naja}$$\text{atra}$ phospholipases A₂. Following methylation a very low residual enzymatic activity (0.4 -- 1% of control) was accompanied by a parallel loss in intraventricular lethality, anticoagulant potency, direct hemolytic action and ability to block directly and indirectly evoked contractions of the mouse phrenic nerve-diaphragm preparation. Since methylation does not impair the enzyme's ability to bind monomeric of micellar substrates or Ca²⁺, the results suggest that the pharmacologicallly active region of the molecule is different from the micellular substrate binding site but strongly influenced by the invariant histidine-48 located at the enzymatic active site.     

Androgen dynamics in vitro in the normal and hyperplastic human prostate gland

The dynamics of uptake and metabolism in vitro of androgens by normal and hyperplastic human prostate glands was studied by means of a new experimental design proposed by Gurpide & Welch (1969). Prostate slices were perfused with a medium containing [(3)H]testosterone and [(14)C]androstenedione, or 5alpha-dihydro-[(3)H]testosterone and [(14)C]testosterone. The entry into the slices, the irreversible metabolism, the conversion between the compounds and the tissue retention or ;uptake' of the steroids were measured at the steady state. A similar portion of the three androgens entered the tissue and was irreversibly metabolized. Conversion of testosterone into 5alpha-dihydrotestosterone was much greater than the interconversion of testosterone and androstenedione. The prostate slices retained 5alpha-dihydrotestosterone at a concentration three times that in the medium, whereas testosterone and androstenedione were retained to a smaller extent. At a steroid concentration of 0.11mumol/l in the medium, the various parameters did not differ significantly in experiments performed with slices from normal and hyperplastic glands. When the steroid concentration in the medium was increased tenfold, however, a difference between normal and hyperplastic glands was evident. The normal glands increased the uptake and metabolism proportionally to the elevation of the steroid concentration in the medium. In the hyperplastic glands the entry and metabolism lagged behind the increase in steroid supply, whereas the tissue uptake became disproportionately high. The possible causes of this finding are discussed.