RESUMO
The tropane alkaloid (TA) scopolamine is suggested to protect Brugmansia suaveolens (Solanaceae) against herbivorous insects. To test this prediction in a natural environment, scopolamine was induced by methyl jasmonate (MJ) in potted plants which were left 10 days in the field. MJ-treated plants increased their scopolamine concentration in leaves and herbivory decreased. These findings suggest a cause-effect relationship. However, experiments in laboratory showed that scopolamine affect differently the performance of the specialist larvae of the ithomiine butterfly Placidina euryanassa (C. Felder & R. Felder) and the generalist fall armyworm Spodoptera frugiperda (J. E. Smith): the specialist that sequester this TA from B. suaveolens leaves was not negatively affected, but the generalist was. Therefore, scopolamine probably acts only against insects that are not adapted to TAs. Other compounds that are MJ elicited may also play a role in plant resistance against herbivory by generalist and specialist insects, and deserve future investigations.
Assuntos
Acetatos/farmacologia , Ciclopentanos/farmacologia , Herbivoria , Insetos , Oxilipinas/farmacologia , Escopolamina , Solanaceae/efeitos dos fármacos , Solanaceae/metabolismo , AnimaisRESUMO
Solenopsis saevissima has a midgut composed of columnar, regenerative, and goblet cells. The midgut epithelium was covered by a basal lamina. Outside the basal lamina, layers of inner oblique, circular, and outer longitudinal muscles were present. Columnar cells showed a basal plasma membrane containing numerous folds, mitochondria, and the nucleus. Rough endoplasmic reticulum, Golgi bodies, membrane bounded vacuoles, and spherocrystals were found in this region. The apical plasma membrane was constituted by microvilli, which were above a region rich in mitochondria. Regenerative cells were found in groups lying by the basal lamina. Goblet cells were associated with an ion-transporting mechanism between the haemolymph and the midgut epithelium. These cells were lying by the midgut lumen and large microvilli were evident, but the cytoplasmic features were similar to the columnar cells.
Assuntos
Formigas/ultraestrutura , Animais , Sistema Digestório/ultraestrutura , Microscopia Eletrônica , Organelas/ultraestruturaRESUMO
The delimitation of cryptic species within the main vector of the American visceral leishmaniasis, Lutzomyia longipalpis, remains a topic of controversy. An analysis of genetic variability based on 8 enzymatic loci revealed fixed differences in 2 diagnostic loci, adenylate kinase (Ak) and hexokinase (Hk), between sympatric and allopatric populations at 4 localities in Venezuela. The absence of heterozygotes for these 2 loci within 1 locality indicates, for the first time, the presence of 2 sympatric reproductively isolated populations or cryptic species within L. longipalpis. Significant differences were also detected between these cryptic species in the allele frequencies of glucose-6-phosphate isomerase (Gpi) and malate dehydrogenase, decarboxylating (Me). One species showed mean heterozygosities that ranged between 6.6% and 6.7%, with 1.6-1.9 alleles detected per locus, while the other had mean heterozygosities that ranged from 4.3% to 6.3%, with 1.3-1.6 alleles per locus. Comparisons of isozyme profiles with published data suggests that 1 species is similar to the L. longipalpis described in Colombian and Brazilian populations, whereas the other has not been previously reported.
Assuntos
Insetos Vetores/genética , Leishmaniose Visceral/transmissão , Psychodidae/genética , Alelos , Animais , Eletroforese em Gel de Poliacrilamida , Frequência do Gene , Variação Genética , Humanos , Insetos Vetores/classificação , Insetos Vetores/enzimologia , Isoenzimas/genética , Leishmaniose Visceral/epidemiologia , Psychodidae/classificação , Psychodidae/enzimologia , Venezuela/epidemiologiaRESUMO
Se realiza un estudio comparativo de microdureza en esmalte y dentina no fluorados y fluorados con una solución de NaF 0,05 por ciento, pH 6.7, incubados a 37§C durante 3 horas. Los ensayos de microdureza Vickers se realizaron en cortes de dientes, utilizando las mismas zonas de indentación antes y después de fluorar las muestras. Los resultados obtenidos indican un aumento en la microdureza del esmalte de un 10,89 por ciento y de un 5,8 por ciento para la dentina después de tratarlos con la solución de NaF, diferencia estadísticamente significativa (Test. t para muestras pareadas)
Assuntos
Esmalte Dentário/anatomia & histologia , Dentina/anatomia & histologia , Dureza , Técnicas In Vitro , Fluoretação , Dente/efeitos dos fármacosRESUMO
Se estudia la protección del esmalte humano de dientes temporales pulverizados mediante el empleo de una solución de NaF 0,05% a diferentes temperaturas. La muestra de tejido dentario se obtuvo por centrifugación-flotación. El ensayo in vitro se llevó a cabo para determinar la cantidad de polvo de esmalte fluorurado disuelto en un tampón ácido láctico/lactato de sodio 0,5 N; pH 4,5. El grado de protección del esmalte fluorurado está expresado por la cantidad en gramos de tejido disuelto. Los resultados obtenidos se observan en las tablas 2 y 3
Assuntos
Esmalte Dentário/efeitos dos fármacos , Técnicas In Vitro , Fluoreto de Sódio , Fluoretos TópicosRESUMO
An in vitro study about the influence of temperature on the solubility of deciduous powdered enamel protected by sodium fluoride (0.05%) was made to observe the variation of the weight loss when the tissue was exposed to 0.5 N lactate buffer at pH 4.5. The protective capacity of fluoride to decrease the acid solubility in temporary tooth enamel presumably can be attribute to increase the temperature measured by scale centrigrade.
Assuntos
Solubilidade do Esmalte Dentário/efeitos dos fármacos , Fluoreto de Sódio/farmacologia , Dente Decíduo/efeitos dos fármacos , Soluções Tampão , Criança , Feminino , Humanos , Concentração de Íons de Hidrogênio , Masculino , TemperaturaRESUMO
Un estudio in vitro de la acción del pH sobre esmalte de dientes temporales fluorurados tópicamente in vivo mediante una solución de NaF 0.05% fue llevado a la práctica para determinar la cantidad de tejido sano disuelto en una solución bufferizada de igual concentración (ácido láctico/lactato de sodio 0.5 N), pero a diferentes rangos de pH. El banco de esmalte aislado se obtuvo ocupando una técnica gravimétrica basándose en la densidad de los tejidos del diente. El polvo de esmalte fluorurado obtenido con un alto porcentaje de pureza fue sometido al test de solubilidad con el fin de poder encontrar una relación entre el grado de disolución ácida de la muestra en el buffer ácido láctico/lactato de sodio y los distintos pH a los cuales se tamponó la solución. La capacidad protectora de la sal fluorurada sobre el esmalte de dientes temporales frente a la acción de la solución a los pH indicados está expresada en peso disuelto en mg. Los resultados obtenidos muestran que existe una correlación lineal negativa (-0,9822) entre la variación del peso de pulverizado de esmalte disuelto y la acidez (pH) de la solución de ácido láctico/lactato de sodio 0,5 N