RESUMEN
The objective of this research was to study variations in allometry of body characters in females and males of two populations of blow flies, Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae), under different environmental conditions to establish patterns of morphological variation. Body size of both males and females in the experimental population was significantly higher than in the individuals of the natural population, indicating an important influence of food on body size. All genitalic and non-genitalic characters in males and females of the two populations showed a trend towards negative allometry rather than isometry. Allometric patterns were modified in both sexes and between populations. The data show generally larger allometric slopes in females than in males. We confirmed that the environmental conditions have an important effect on allometric patterns and body size.
Asunto(s)
Dípteros/crecimiento & desarrollo , Ambiente , Animales , Biometría , Tamaño Corporal , Femenino , Masculino , PorcinosRESUMEN
Males of many animals perform 'copulatory courtship' during copulation, but the possible reproductive significance of this behaviour has seldom been investigated. In some animals, including the spider Physocyclus globosus (Pholcidae), the female discards sperm during or immediately following some copulations. In this study, we determined which of several variables associated with copulation correlated with paternity success in P. globosus when two males mate with a single female. Then, by determining which of these variables also correlated with sperm dumping, we inferred which variables may affect paternity via the mechanism of sperm dumping. Male abdomen vibration (a copulatory courtship behaviour) and male genitalic squeezing both correlated with both paternity and sperm dumping; so, these traits may be favoured by biased sperm dumping. Biased sperm dumping may also be the mechanism by which possible cryptic female choice favours another male trait that was the subject of a previous study, responsiveness to female stridulation.
Asunto(s)
Conducta Sexual Animal , Arañas , Animales , Femenino , Genitales Femeninos/fisiología , Masculino , Paternidad , EspermatozoidesRESUMEN
The presence of chlorimuron ethyl and metsulfuron methyl in two soils was determined by a modified petri dish bioassay. Pregerminated seeds of maize and sunflower were placed in petri dishes containing 85 to 100 g of treated soil. Radicle root lengths were measured after 24 h. Chlorimuron had no effect on maize on the Balcarce soil, however 0.007 microg g(-1) decreased sunflower root length. Chlorimuron decreased maize and sunflower root length regardless application dose on the San Cayetano soil. Metsulfuron decreased maize root length at 0.04 microg g(-1) and sunflower at 0.021 microg g(-1) on the Balcarce soil. On the San Cayetano soil metsulfuron at 0.001 microg g(-1) decreased maize and sunflower root length. The phytotoxicity of chlorimuron and metsulfuron changed according to soil type and dose. Maize and sunflower were 1.3-1.5 and 1.3-1.8 times respectively more sensitive to chlorimuron on the San Cayetano soil than on the Balcarce soil. In the case of metsulfuron, maize was similarly sensitive on both soils but sunflower was 1.7-2.0 times more sensitive on the San Cayetano soil than on the Balcarce soil. Phytotoxicity increased as organic matter (OM) content decreased and/or when the soil pH and concentration increased.
Asunto(s)
Arilsulfonatos/análisis , Residuos de Plaguicidas/análisis , Pirimidinas/análisis , Contaminantes del Suelo/análisis , Compuestos de Sulfonilurea/análisis , Argentina , Arilsulfonatos/efectos adversos , Bioensayo/métodos , Helianthus/crecimiento & desarrollo , Residuos de Plaguicidas/efectos adversos , Pirimidinas/efectos adversos , Semillas/crecimiento & desarrollo , Contaminantes del Suelo/efectos adversos , Compuestos de Sulfonilurea/efectos adversos , Zea mays/crecimiento & desarrolloRESUMEN
Fertilized hen eggs were externally treated with 3.1 mg 2,4-dichlorophenoxyacetic acid butyl ester (2,4-D ester) before starting incubation. Liver lipid composition, (14C)2,4-dichlorophenoxyacetic acid (14C-2,4-D) subcellular distribution and covalent binding to proteins and lipids of chicks hatched from these eggs were studied. Furthermore, catalase, glutathione S-transferase and glucose 6-phosphatase activities as well as reduced glutathione content were determined. The herbicide produced a significant decrease on the total lipids, specially on phospholipids, both in total liver and microsomes. (14C-2,4-D) subcellular distribution in liver demonstrated that the herbicide passed through the plasmatic membrane and it was present in all the studied fractions. Herbicide bound covalently to hepatic proteins and lipids, being the binding to proteins tenfold higher than to lipids. Because these results might be of potential relevance to the understanding of the 2,4-D toxicity, further studies on the mechanisms of these reactions are necessary. On the other hand, the microsomal and cytosolic glutathione S-transferases activities remained unchanged, even though in vitro studies 2,4-D ester caused a decrease of the enzyme activities with an I50 value of 0.2 mM. No significant change in reduced glutathione content between control and treated livers was observed. The catalase activity increased two-fold whereas glucose 6-phosphatase activity decreased 46% with respect to the corresponding control values. These results indicate that 2,4-D ester may have effects on the metabolism of xenobiotics.
Asunto(s)
Ácido 2,4-Diclorofenoxiacético/análogos & derivados , Pollos , Lípidos/análisis , Hígado/efectos de los fármacos , Proteínas/análisis , Ácido 2,4-Diclorofenoxiacético/farmacocinética , Ácido 2,4-Diclorofenoxiacético/toxicidad , Animales , Animales Recién Nacidos , Embrión de Pollo , Hígado/química , Hígado/enzimología , Proteínas/efectos de los fármacosRESUMEN
The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) produced a deleterious effect on the growth of Rhizobium sp. M4, that was reversed by transferring the cells to a fresh control medium. The uptake of 2,4-D by Rhizobium sp. was not affected by chloramphenicol, indicating that it is constitutive rather than inducible. The mechanism of transport also appears to be energy independent, since uptake was not inhibited by azide or arsenate.
Asunto(s)
Ácido 2,4-Diclorofenoxiacético/farmacología , Rhizobium/efectos de los fármacos , Ácido 2,4-Diclorofenoxiacético/metabolismo , Arseniatos/farmacología , Azidas/farmacología , Transporte Biológico , Rhizobium/crecimiento & desarrollo , Rhizobium/metabolismo , Azida SódicaRESUMEN
The effects of 1 mM 2,4-Dichlorophenoxyacetic acid on Rhizobium sp. in pure culture was studied. In a previous work it was demonstrated that this herbicide produces an alteration on the saturated to unsaturated phospholipid acyl chains ratio. In the present paper, it was found that this alteration produces a modification on the membrane fluidity in bacteria that had achieved the stationary phase. The same results were obtained when determinations were done in liposomes from sonicated lipids of treated bacteria, indicating that changes in phospholipid acyl chains may be the main cause of membrane fluidity alteration. In addition, it was determined that leucine transport as well as Ca(++)-ATPase activity (a membrane enzyme) was affected under the experimental conditions.
Asunto(s)
Ácido 2,4-Diclorofenoxiacético/farmacología , Fluidez de la Membrana/efectos de los fármacos , Rhizobium/efectos de los fármacos , ATPasas Transportadoras de Calcio/efectos de los fármacos , ATPasas Transportadoras de Calcio/metabolismo , Glucosa/metabolismo , Leucina/metabolismo , Succinatos/farmacocinética , Ácido SuccínicoRESUMEN
The effects of 2,4-dichlorophenoxyacetic butyl ester (2,4-D b.e.) on protein and nucleic acid contents of different tissues of chicks born from externally treated hen's eggs were studied. Residues of 2,4-D b.e. were also determined and quantified by gas liquid chromatography (GLC). A diminished DNA content was observed in skeletal muscle and stomach, an increased one was found in cerebrum and cerebellum, whereas no variations were observed in the other analysed tissues. Protein levels were found decreased in kidney, cerebrum and heart. Besides, the GLC determinations revealed the presence of the 2,4-D b.e. in all the studied tissues finding the highest concentrations in kidney. 2,4-D did not appear to be a significant metabolite of 2,4-D b.e. in this experimental system. The dissimilar effects of 2,4-D b.e. on protein and nucleic acid contents of the studied tissues would be related to a different tissue susceptibility to the drug and/or to drug distribution.