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.     

myo-Inositol phosphorothioates, phosphatase-resistant analogues of myo-inositol phosphates. Synthesis of DL-myo-inositol 1,4-bisphosphate and DL-myo-inositol 1,4-bisphosphorothioate.

Syntheses of a metabolite of the second messenger myo-inositol 1,4,5-trisphosphate, myo-inositol 1,4-bisphosphate, and an analogue, the 1,4-bisphosphorothioate, are reported, by using phosphite chemistry on (+/-)-1,2:4,5-di-isopropylidene-myo-inositol. The synthesis of (+/-)-1,2:4,5-di-isopropylidene 3,6-bis[di-(2-cyanoethyl)]phosphite provides an intermediate that can be oxidized to either the corresponding bisphosphate or bisphosphorothioate. myo-Inositol phosphorothioates are proposed as novel analogues of myo-inositol phosphates; their resistance to phosphatase-catalysed breakdown is reported.     

Subcellular Location and Neuronal Release of Diazepam Binding Inhibitor

Diazepam binding inhibitor (DBI), a peptide located in CNS neurons, blocks the binding of benzodiazepines and beta-carbolines to the allosteric modulatory sites of gamma-aminobutyric acid (GABAA) receptors. Subcellular fractionation studies of rat brain indicate that DBI is compartmentalized. DBI-like immunoreactivity is highly enriched in synaptosomes obtained by differential centrifugation in isotonic sucrose followed by a Percoll gradient. In synaptosomal lysate, DBI-like immunoreactivity is primarily associated with synaptic vesicles partially purified by differential centrifugation and continuous sucrose gradient. Depolarization induced by high K+ levels (50 mM) or veratridine (50 microM) released DBI stored in neurons of superfused slices of hypothalamus, hippocampus, striatum, and cerebral cortex. The high K+ level-induced release is Ca2+ dependent, and the release induced by veratridine is blocked by 1.7 microM tetrodotoxin. Depolarization released GABA and Met5-enkephalin-Arg6-Phe7 together with DBI. DBI is also released by veratridine depolarization, in a tetrodotoxin-sensitive fashion, from primary cultures of cerebral cortical neurons, but not from cortical astrocytes. Depolarization fails to release DBI from slices of liver and other peripheral organs. These data support the view that DBI may be released as a putative neuromodulatory substance from rat brain neurons.     

Metabolic reduction of chromium,as related to its carcinogenic properties

At variance with Cr(III), Cr(VI) compounds easily cross cell membranes and exert genotoxic effects. No metabolic oxidation of Cr(III) could be detected, whereas Cr(VI) reduction was observed in the presence of body fluids and subcellular fractions of various tissues from several animal species. The differential efficiency of this process may account for the selection of target tissues in Cr(VI) carcinogenesis. For instance, reduction by saliva and gastric juice may explain a lack of carcinogenicity by the oral route; reduction inside erythrocytes may explain a lack of carcinogenicity at a distance from administration sites; reduction by the epithelial-lining fluid of terminal airways and by alveolar macrophages may be consistent with the occurrence of thresholds in lung carcinogenesis. Liver preparations displayed the top efficiency in reducing Cr(VI), whereas skeletal muscle, i.e., a typical target in experimental Cr(VI) carcinogenesis, had no detectable activity. Bronchial tree and peripheral lung parenchyma preparations from almost 100 individuals reduced Cr(VI) to a variable extent. The efficiency of lung parenchyma and of isolated alveolar macrophages was enhanced in cigarette smokers. In rats, Cr(VI) reduction by lung preparations was significantly stimulated by the repeated i.t. instillation of Cr(VI) itself. Among the electron donors (chiefly GSH) and enzymatic mechanisms responsible for the intracellular Cr(VI) reduction, such as cytochrome P-450 reductase, glutathione redactase, and aldehyde oxidase, an important role can be ascribed to cytosolic DT diaphorase activity, usually catalyzing a 2-electron reduction.     

Prevention by N-acetylcysteine of benzo[a]pyrene clastogenicity and DNA adducts in rats

The daily i.t. administration of benzo[a]pyrene (BP) to Sprague-Dawley rats, for 3 consecutive days, did not cause any toxicity or clastogenicity in bone marrow cells, as evaluated by monitoring the ratio of polychromatic to normochromatic erythrocytes and the frequency of micronucleated polychromatic erythrocytes. However, BP produced a considerable enhancement of binucleated and micronucleated pulmonary alveolar macrophages, as well as a significant increase in polymorphonucleates recovered by bronchoalveolar lavage. These effects were prevented by administering the thiol N-acetylcysteine (NAC) by gavage 5 h before each BP instillation. In addition, the i.t. treatment with BP resulted in the formation of BP diolepoxide (BPDE)-DNA adducts in lungs and liver, as assessed by synchronous fluorescence spectrophotometry, with fluorescence peaks of similar magnitude in the 2 tissues. Pretreatment with NAC by gavage completely prevented BPDE adducts to liver DNA and significantly decreased those to lung DNA.     

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.