Variation in the diet of the viperine snake Natvix mama in relation to prey availability

The diet of the viperine snake was compared with food availability in the Ebro Delta, a wetland largely occupied by rice fields, in 1990 and 1991. Snake selection of prey type and size was studied seasonally and by snake group: males, females and immature snakes. Overall, feeding activity (percentage of individuals with prey and number of prey per stomach) increased with food availability. Diet analysis showed that viperine snakes mainly foraged on the green frog Rana perezi (adults and tadpoles) and the carp Cyprinus earpio. Conversely, viperine snakes rejected the mosquito fish Gambusia holbroki which is the most abundant species in autumn, when Natrix maura has a low feeding activity. Statistical comparisons between viperine snake diet and prey availability showed that males selected small carp, immature snakes selected tadpoles and, in spring, females selected frogs. The selection of small carp by males may reflect a sexual divergence of trophic niche related to sexual size dimorphism, as females are larger than males. As tadpoles are presumably easier to catch than fish, tadpole selection by immature individuals may reflect variance in capture abilities. In spring, the selection of frogs by females overlapped with vitellogenesis, suggesting that females compensate for the cost of reproduction by selecting green frogs, which have a greater biomass and higher energy content than fish. Carps eaten in spring were smaller than in summer. Moreover, in summer viperine snakes selected smaller carp than the available mean size. This divergent tendency between carp size selection and carp size availability reveals how seasonal diet shifts in prey size selection may be a response to an increase in prey size.     

Analysis of Immune Response Markers in Jorge Lobo's Disease Lesions Suggests the Occurrence of Mixed T Helper Responses with the Dominance of Regulatory T Cell Activity

Jorge Lobo’s disease (JLD) is a chronic infection that affects the skin and subcutaneous tissues. Its etiologic agent is the fungus Lacazia loboi. Lesions are classified as localized, multifocal, or disseminated, depending on their location. Early diagnosis and the surgical removal of lesions are the best therapeutic options currently available for JLD. The few studies that evaluate the immunological response of JLD patients show a predominance of Th2 response, as well as a high frequency of TGF-β and IL-10 positive cells in the lesions; however, the overall immunological status of the lesions in terms of their T cell phenotype has yet to be determined. Therefore, the objective of this study was to evaluate the pattern of Th1, Th2, Th17 and regulatory T cell (Treg) markers mRNA in JLD patients by means of real-time PCR. Biopsies of JLD lesions (N = 102) were classified according to their clinical and histopathological features and then analyzed using real-time PCR in order to determine the expression levels of TGF-β1, FoxP3, CTLA4, IKZF2, IL-10, T-bet, IFN-γ, GATA3, IL-4, IL-5, IL-13, IL-33, RORC, IL-17A, IL-17F, and IL-22 and to compare these levels to those of healthy control skin (N = 12). The results showed an increased expression of FoxP3, CTLA4, TGF-β1, IL-10, T-bet, IL-17F, and IL-17A in lesions, while GATA3 and IL-4 levels were found to be lower in diseased skin than in the control group. When the clinical forms were compared, TGF-β1 was found to be highly expressed in patients with a single localized lesion while IL-5 and IL-17A levels were higher in patients with multiple/disseminated lesions. These results demonstrate the occurrence of mixed T helper responses and suggest the dominance of regulatory T cell activity, which could inhibit Th-dependent protective responses to intracellular fungi such as L. loboi. Therefore, Tregs may play a key role in JLD pathogenesis.     

SuperSAGE analysis of the <Emphasis Type="Italic">Nicotiana attenuata</Emphasis> transcriptome after fatty acid-amino acid elicitation (FAC): identification of early mediators of insect responses

Background  

Plants trigger and tailor defense responses after perception of the oral secretions (OS) of attacking specialist lepidopteran larvae. Fatty acid-amino acid conjugates (FACs) in the OS of the Manduca sexta larvae are necessary and sufficient to elicit the herbivory-specific responses in Nicotiana attenuata, an annual wild tobacco species. How FACs are perceived and activate signal transduction mechanisms is unknown.     

Genetic variation and distances of five Italian native sheep breeds

Genetic distances among five of the most important Italian native sheep breeds were estimated by using gene frequencies of four blood group and seven blood protein loci and by three different computing methods. The values of the three distance matrices were highly correlated. Genetic distances were found within the range values reported in the literature for local breeds. Shorter distances fitted the historical evidence of migrations.     

Mechanism of action of levonorgestrel: in vitro metabolism and specific interactions with steroid receptors in target organs.

Levonorgestrel (LNG) is a synthetic steroid that displays potent progestional and androgenic effects but it lacks estrogen-like activity. To examine the mode of action of this progestin, we studied its metabolism in vitro in target organs and the specific interactions of LNG and its metabolites with putative steroid receptors. The results demonstrated that [³H]LNG was efficiently converted to A-ring reduced derivatives when incubated with rat hypothalamus and pituitary. Under optimal incubation conditions, [³H]5-dihydro LNG (5-LNG) and [³H]3-5-tetrahydro LNG (3,5-LNG) were identified as the major metabolic conversion products, while [³H]3ß, 5-LNG formation occured to a lesser extent. A-ring reduction of LNG was NADPH-dependent. Assessment of the relative binding affinities of LNG and its derivatives to progesterone (PR), androgen (AR) and estrogen (ER) receptors by displacement analysis revealed that unchanged LNG binds with high affinity to PR and AR but not to ER. 5-LNG exhibited a diminished though significant interactions with PR and an enhanced binding affinity for AR as compared with LNG, indicating that 5-reduction of LNG increases its affinity for AR. The most striking finding was that further reduction of the 5-LNG molecule at C-3 abolished its binding activity to PR, AR, and even to ER. The overall data provides a plausible explanation for the lack of estrogen agonistic action of LNG and for its potent progestational and androgenic effects.     

Anti HLA class I monoclonal antibody effect on PKC kinetics in PHA activated human peripheral blood mononuclear and E+ cells

Cytoplasmic protein kinase C (PKC) has been studied in phytohemagglutinin (PHA) activated peripheral blood mononuclear cells (PBMC) and macrophage depleted E+ cell culture. Within 10' after contemporanous addition of PHA and anti HLA class I monoclonal antibody 01.65 (MoAb) PKC is depleted in both cell types. Enzyme activity recovers in the following hours however at 72 hours is at control values in E+ cultures while in PBMC cultures it is still depleted at 68% of the control. Anti HLA class I MoAb induced tritiated lymidine (3H-TdR) incorporation inhibition appears to be related to low levels of PKC activity.     

Host-Symbiont Specificity Expressed during Early Adsorption of Rhizobium meliloti to the Root Surface of Alfalfa

Early (4 h) adsorption of Rhizobium meliloti L5-30 in low numbers to alfalfa roots in mineral solution was examined for competition with other bacterial strains. All tested competitor strains decreased the adsorption of L5-30 by extents which depended on the strain and its concentration. The decrease of adsorption by R. meliloti competitors (all of them infective in alfalfa) was nearly complete at saturation (97 to 99% decrease). All other heterologous rhizobia and Agrobacterium tumefaciens at saturating concentrations (10⁶ to 10⁷ per ml) decreased adsorption of L5-30 only partially, less than 60%. The differential effects of homologous and heterologous competitors indicate that initial adsorption of R. meliloti to the root surface of its host occurs in symbiont-specific as well as nonspecific modes and suggest the existence of binding sites on roots which are highly selective for the specific microsymbiont in the presence of other heterologous bacteria even in very unfavorable (less than 10⁻⁴) symbiont-competitor concentration ratios.     

Effect of oxidants and antioxidants on chromosomal breakage in Fanconi anemia lymphocytes

Summary Peripheral blood lymphocytes from eight Fanconi anemia (FA) patients, 14 FA heterozygotes, and nine normal subjects have been tested for their susceptibility to chromosomal breakage induction by diepoxybutane (DEB) and by two peroxides. In addition, the effect of five antioxidants was investigated in standard cultures and in cultures stressed either with DEB or with butylhydroperoxide (BHP) or with hydrogen peroxide (H₂O₂). DEB, BHP, and H₂O₂ dramatically increased the chromosomal breakage levels in homozygous and heterozygous FA cells. A partial correction of chromosomal instability was obtained by treating the patients' lymphocytes with antioxidants. A protective effect was also noted in the DEB or peroxide-stressed lymphocytes of patients and heterozygotes, grown in the presence of antioxidants.