Modified α-amylase activity among insecticide-resistant and -susceptible strains of the maize weevil, Sitophilus zeamais

Fitness cost is usually associated with insecticide resistance and may be mitigated by increased energy accumulation and mobilization. Preliminary evidence in the maize weevil (Coleoptera: Curculionidae) suggested possible involvement of amylases in such phenomenon. Therefore, α-amylases were purified from an insecticide-susceptible and two insecticide-resistant strains (one with fitness cost [resistant cost strain], and the other without it [resistant no-cost strain]). The main α-amylase of each strain was purified by glycogen precipitation and ion-exchange chromatography (≥70-fold purification, ≤19% yield). Single α-amylase bands with the same molecular mass (53.7 kDa) were revealed for each insect strain. Higher activity was obtained at 35-40 °C and at pH 5.0-7.0 for all of the strains. The α-amylase from the resistant no-cost strain exhibited higher activity towards starch and lower inhibition by acarbose and wheat amylase inhibitors. Opposite results were observed for the α-amylase from the resistant cost strain. Although the α-amylase from the resistant cost strain exhibited higher affinity to starch (i.e., lower K_m), its V_max-value was the lowest among the strains, particularly the resistant no-cost strain. Such results provide support for the hypothesis that enhanced α-amylase activity may be playing a major role in mitigating fitness costs associated with insecticide resistance.     

Role of mast cells as IL10 producing cells in paracoccidioidomycosis skin lesions

Recent works have demonstrated that mast cells may have an important role in immunologic reactions and inflammation once they synthesize and secrete many cytokines including IL4, IL5, IL6 and TNF-α. We have conducted research in order to verify if mast cells would participate in the local inflammatory immune response against Paracoccidioides brasiliensis in skin lesions characterized by a Th2 pattern of cytokines. Fifty-nine skin biopsies with previous histopathological diagnosis of paracoccidioidomycosis and immunohistochemical characterization of cytokines present in the inflammatory infiltrate were classified in three groups: group 1 (G1), with compact granuloma and a Th1 pattern of cytokines; group 2 (G2), with loose granuloma and a Th2 pattern of cytokines; group 3 (G3), both kind of granuloma in the same lesion, characterized by cytokines from Th1 and Th2 patterns. Ten biopsies from normal skin were used as control group. Mast cells were visualized and quantified by a toluidine blue/HCl staining and a double immunostaining was performed to detect a co-localization of mast cells and IL10. G2 presented an increased number of mast cells when compared to G1, G3 and control group and we frequently could find mast cells expressing IL10 in G2. The data obtained suggest that mast cells participate in the immune response against P. brasiliensis in skin lesions with loose granuloma and a Th2 pattern of cytokines. Considering these results, mast cells could constitute a source of IL10, contributing to a non-effective response against fungal antigens.     

Morphology and preliminary enzyme characterization of the salivary glands from the predatory bug Podisus nigrispinus (Heteroptera: Pentatomidae)

Podisus nigrispinus (Dallas) is a common predator in agricultural and natural systems in Neotropical America. Its feeding strategy involves extra-oral digestion and to better understand this process its salivary glands were extracted and subjected to morphological and preliminary enzyme characterization. The salivary glands of P. nigrispinus are formed by a pair of main and accessory gland complexes. The main salivary glands are further divided into an anterior and a posterior lobe. The compartmentalization of the salivary gland complex is likely to be important for the production, activation and release of the digestive enzymes used in the extra-oral digestion of prey items. Proteases and lipase, important digestive enzymes involved in zoophagy, were detected in the salivary glands of P. nigrispinus. The prevailing trypsin-like protease activity was characterized by using the serine-protease substrate N-alpha-benzoyl-L-Arg-p-nitroanilidine (L-BApNA) and the trypsin inhibitors tosyl-L-lysine chloromethyl ketone (TLCK) and benzamidine. The KM value obtained for trypsin-like activity was 1.57 mm and the different peaks of optimum pH and temperature activity suggest the presence of multiple forms of this enzyme in P. nigrispinus. Detection of amylase activity in the salivary glands of this predator suggests its ability to digest starch and obtain nutrients from plants, which may have adaptative value under prey scarcity.     

Egg exposure to pyriproxyfen in the tomato leaf miner Tuta absoluta: ovicidal activity or behavioural‐modulated hatching mortality?

Insecticide susceptibility varies with the insect life stage and although the egg stage is sometimes perceived as the most vulnerable, it is a difficult target for insecticide application and little studied as such. Egg susceptibility to insecticides is generally considered important for insect growth regulators and insect pests of reduced mobility like leaf miners because of their placement on the host plant part targeted by the insecticidal application. The egg exposure to the juvenile hormone mimic pyriproxyfen was studied here in the tomato leaf miner Tuta absoluta (Lepidoptera: Gelechiidae), a key tomato insect pest, aiming to assess if mortality is achieved due to insecticide ovicidal activity or due to behavioural impairment of the larvae preventing egg hatching. Survival analysis of treated tomato leaves and/or eggs indicated the importance of egg exposure to pyriproxyfen leading to a significant decrease in survival with a nearly 50% reduction in survival time, which peaked at the first instar. Ovicidal activity of pyriproxyfen in the tomato leaf miner was negligible, but image recording and behaviour analysis indicated behavioural impairment of larval activity compromising hatching and leaf mining by early instar larvae leading to high mortality at this stage (ca 50%). The likely causes and management implications of such findings are discussed.     

Anti-Trypanosoma cruzi and cytotoxic activities of Eugenia uniflora L

Chagas disease is caused by Trypanosoma cruzi, being considered a public health problem. An alternative to combat this pathogen is the use of natural products isolated from fruits such as Eugenia uniflora, a plant used by traditional communities as food and medicine due to its antimicrobial and biological activities. Ethanolic extract from E. uniflora was used to evaluate in vitro anti-epimastigote and cytotoxic activity. This is the first record of anti-Trypanosoma activity of E. uniflora, demonstrating that a concentration presenting 50% of activity (EC(50)) was 62.76 μg/mL. Minimum inhibitory concentration (MIC) was ≤ 1024 μg/mL. Our results indicate that E. uniflora could be a source of plant-derived natural products with anti-epimastigote activity with low toxicity.     

N-Acyl and N-sulfonyloxazolidine-2,4-diones are pseudo-irreversible inhibitors of serine proteases

The synthesis, inhibitory activity and mode of action of oxazolidine-2,4-diones against porcine pancreatic elastase, here used as a model for human neutrophil elastase, are reported. The nature of N-substitution at the oxazolidine-2,4-dione scaffold has large effect on the inhibitory potency against elastase. N-Acyl and N-sulfonyloxazolidine-2,4-diones emerged as potent pseudo-irreversible inhibitors, displaying high second-order rate constants for PPE inactivation. The title compounds were also shown to be potent inhibitors of human neutrophil elastase (HNE) and proteinase-3, and weak inhibitors of human cathepsin G. The results herein presented show that the oxazolidine-2,4-diones represent a new promising class of serine protease inhibitors.     

First Record of Teratopactus nodicollis (Coleoptera: Curculionidae) in Dry Bean (Phaseolus vulgaris)

Observations on the bioecology and damage of Teratopactus nodicollis Boheman on Phaseolus vulgaris were carried out on field samples by assessing the number of larvae and root damage in 40?ha of a dry bean field from the Federal District, Brazil (16°4??28.41???W; 47°30??21.13???S). Larvae caused the greatest damage at the stage of germination, emergence, and primary leaves, producing 50?% stand reduction. Most larvae pupated in August and September, and adult emergence occurred in middle October. Some larvae were infected with the fungus Metarhizium spp., a biological agent that would be naturally controlling this insect.     

Antinoceptive effect of triterpenoid α,β-amyrin in rats on orofacial pain induced by formalin and capsaicin

The effects of α,β-amyrin, a pentacyclic triterpene isolated from Protium heptaphylum was investigated on rat model of orofacial pain induced by formalin or capsaicin. Rats were pretreated with α,β-amyrin (10, 30, and 100 mg/kg, i.p.), morphine (5 mg/kg, s.c.) or vehicle (3% Tween 80), before formalin (20 μl, 1.5%) or capsaicin (20 μl, 1.5 μg) injection into the right vibrissa. In vehicle-treated controls, formalin induced a biphasic nociceptive face-rubbing behavioral response with an early first phase (0–5 min) and a late second phase (10–20 min) appearance, whereas capsaicin produced an immediate face-rubbing (grooming) behavior that was maximal at 10–20 min. Treatment with α,β-amyrin or morphine significantly inhibited the face-rubbing response in both test models. While morphine produced significant antinociception in both phases of formalin test, α,β-amyrin inhibited only the second phase response, more prominently at 30 mg/kg, in a naloxone-sensitive manner. In contrast, α,β-amyrin produced much greater antinociceptive effect at 100 mg/kg in the capsaicin test, which was also naloxone-sensitive. These results provide first time evidence to show that α,β-amyrin attenuates orofacial pain atleast, in part, through a peripheral opioid mechanism but warrants further detailed study for its utility in painful orofacial pathologies.     

Effect of coffee alkaloids and phenolics on egg-laying by the coffee leaf miner Leucoptera coffeella

The recognized importance of coffee alkaloids and phenolics mediating insect-plant interactions led to the present investigation aiming to test the hypothesis that the phenolics chlorogenic and caffeic acids and the alkaloid caffeine and some of its derivatives present in coffee leaves affect egg-laying by the coffee leaf miner Leucoptera (=Perileucoptera) coffeella (Guérin-Méneville & Perrottet) (Lepidoptera: Lyonetiidae), one of the main coffee pests in the Neotropical region. These phytochemicals were, therefore, quantified in leaves from 12 coffee genotypes and their effect on the egg-laying preference by the coffee leaf miner was assessed. Canonical variate analysis and partial canonical correlation provided evidence that increased leaf levels of caffeine favour egg-laying by the coffee leaf miner. An egg-laying preference bioassay was, therefore, carried out to specifically test this hypothesis using increasing caffeine concentrations sprayed on leaves of one of the coffee genotypes with the lowest level of this compound (i.e. Hybrid UFV 557-04 generated from a cross between Coffea racemosa Lour. and C. arabica L.). The results obtained allowed the recognition of a significant concentration-response relationship, providing support for the hypothesis that caffeine stimulates egg-laying by the coffee leaf miner in coffee leaves.     

Genetic variation and population structure of the endangered Hyacinth Macaw (<Emphasis Type="Italic">Anodorhynchus hyacinthinus</Emphasis>): implications for conservation

The Hyacinth Macaw (Anodorhynchus hyacinthinus) is one of 14 endangered species in the family Psittacidae occurring in Brazil, with an estimated total population of 6,500 specimens. We used nuclear molecular markers (single locus minisatellites and microsatellites) and 472 bp of the mitochondrial DNA control region to characterize levels of genetic variability in this species and to assess the degree of gene flow among three nesting sites in Brazil (Pantanal do Abobral, Pantanal de Miranda and Piauí). The origin of five apprehended specimens was also investigated. The results suggest that, in comparison to other species of parrots, Hyacinth Macaws possess relatively lower genetic variation and that individuals from two different localities within the Pantanal (Abobral and Miranda) belong to a unique interbreeding population and are genetically distinct at nuclear level from birds from the state of Piauí. The analyses of the five apprehended birds suggest that the Pantanal is not the source of birds for illegal trade, but their precise origin could not be assigned. The low genetic variability detected in the Hyacinth Macaw does not seem to pose a threat to the survival of this species. Nevertheless, habitat destruction and nest poaching are the most important factors negatively affecting their populations in the wild. The observed genetic structure emphasizes the need of protection of Hyacinth Macaws from different regions in order to maintain the genetic diversity of this species.