Longterm melatonin administration alleviates paraquat mediated oxidative stress in Drosophila melanogaster / La administración de melatonina a largo plazo mitiga el estrés oxidativo mediado por paraquat en Drosophila melanogaster

We investigated the effect of melatonin (MEL) in the activities of cytosolic superoxide dismutase (SOD) and catalase as well as in the levels of H2O2 and mitochondrial malondialdehyde (MDA) in paraquat-intoxicated Drosophila melanogaster. Paraquat (40 mM) was administrated for 36 h. Three groups of flies intoxicated with paraquat were used: PQ (exposed during 36h to paraquat), PQ-MEL (exposed during 36h to paraquat and then treated with MEL [0.43 mM] for 12 days) and PQ-Control (maintained in standard corn meal for 12 days). Two additional groups without pre-intoxication with PQ were added: Control (maintained in standard corn meal) and MEL (treated with MEL for 12 days). Immediately after PQ intoxication the concentration of MDA (17.240 ± 0.554 nmoles MDA/mg protein) and H2O2 (3.313 ± 0.086 nmol hydrogen peroxide/mg protein) and the activities of SOD and catalase (419.667 ± 0.731 and 0.216 ± 0.009 Units/mg of protein, respectively) in the PQ group were significantly increased with respect to Control. After 12 days of intoxication with PQ, the PQ-Control flies showed increases in H2O2 (4.336 ± 0.108) and MDA levels (8.620 ± 0.156), and in the activities of SOD and catalase (692.570 ± 0.433 and 0.327 ± 0.003, respectively) as compared to PQ-MEL (p<0.001). Treatment with MEL extended the life span of the groups PQ-MEL and MEL when compared to their corresponding controls. Motor activity decreased significantly in PQ-Control and PQ-MEL flies, suggesting that the damage caused by PQ affected the nervous system of flies. Our findings showed that oxidative damage caused by paraquat was observed even after 12 days and that melatonin mitigates this damage.

Investigamos el efecto de la melatonina (MEL) en la actividad de la superóxido dismutasa citosólica (SOD) y la catalasa, así como en las concentraciones del H2O2 y del malondialdehido mitocondrial (MDA) en la toxicidad inducida por paraquat (PQ) en Drosophila melanogaster. El paraquat (40 mM) fue administrado durante 36h. Tres grupos de moscas se utilizaron después de la intoxicación con paraquat: PQ (expuestas a paraquat durante 36 h), PQ-MEL (expuestas durante 36 horas a PQ y luego tratadas con MEL [0,43 mM] por 12 días) y PQ-Control (mantenidas en medio estándar por 12 días). Se incluyeron dos grupos adicionales sin pre-intoxicación con PQ: Control (mantenido en medio estándar) y MEL (tratado con MEL por 12 días). Inmediatamente después de la intoxicación con PQ, las concentraciones de MDA (17,240 ± 0,554 nmol de MDA/mg de proteína), H2O2 (3,313 ± 0,086 nmol de H2O2/mg de proteína) y las actividades de la SOD y catalasa (419,667 ± 0,731 y 0,216 ± 0,009 unidades/mg de proteína, respectivamente) se incrementaron significativamente con respecto al Control. Doce días después de la intoxicación con PQ, las moscas PQ-Control mostraron un aumento en la concentración de H2O2 (4,336 ± 0,108), de los niveles de MDA (8,620 ± 0,156) y en las actividades de la SOD y la catalasa (692,570 ± 0,433 y 0,327 ± 0,003, respectivamente) en comparación con el grupo PQ-MEL (p<0,001). El tratamiento con MEL extendió el tiempo de vida de los grupos PQ-MEL y MEL en comparación con sus correspondientes controles. La actividad motora disminuyó significativamente en las moscas de los grupos PQ-Control y PQ-MEL, lo que sugiere que el PQ afectó el sistema nervioso de las moscas. Nuestros hallazgos demostraron que el daño oxidativo causado por paraquat en las moscas fue observado aún después de 12 días de intoxicadas y que la melatonina logró mitigar este daño.

Fatty acid composition of Drosophila photoreceptor light-sensitive microvilli

Phototransduction, the mechanism underlying the electrical response to light in photoreceptor cells, has been thoroughly investigated in Drosophila melanogaster, an essential model in signal transduction research. These cells present a highly specialized photosensitive membrane consisting of thousands of microvilli forming a prominent structure termed a rhabdomere. These microvilli encompass the phototransduction proteins, most of which are transmembrane and exclusively rhabdomeric. Rhabdomere membrane lipids play a crucial role in the activation of the transient receptor potential ionic channels (TRP and TRPL) responsible for initiating the photoresponse. Despite its importance, rhabdomere lipid composition has not been established. We developed a novel preparation enriched in rhabdomere membranes to perform a thorough characterization of the lipidomics of Drosophila rhabdomeres. Isolated eyes (500) were homogenized and subjected to a differential centrifugation protocol that generates a fraction enriched in rhabdomere membrane. Lipids extracted from this preparation were identified and quantified by gas chromatography coupled to mass spectrometry. We found an abundance of low sterol esters (C16:0, C18:0), highly abundant and diverse triglycerides, free fatty acids, a moderate variety of mono and diacyglycerols (C:16:0, 18:0, C18:1) and abundant phospholipids (principally C18:2). This preparation opens a new avenue for investigating essential aspects of phototransduction.

Polytene chromosome map and inversion polymorphism in Drosophila mediopunctata

Drosophila mediopunctata belongs to the tripunctata group, and is one of the commonest Drosophila species collected in some places in Brazil, especially in the winter. A standard map of the polytene chromosomes is presented. The breakpoints of the naturally occurring chromosomal rearrangements are marked on the map. The distribution of breaking points through the chromosomes of D. mediopunctata is apparently non-random. Chromosomes X, II and IV show inversion polymorphisms. Chromosome II is the most polymorphic, with 17 inversions, 8 inversions in the distal region and 9 in the proximal region. Chromosome X has four different gene arrangements, while chromosome IV has only two