Drosophila melanogaster as an indispensable model to decipher the mode of action of neurotoxic compounds

Exposure to some toxic compounds causes structural and behavioral anomalies associated with the neurons in the later stage of life.Those toxic compounds are termed as a neurotoxicant,which can be a physical factor,a toxin,an infection,radiation,or maybe a drug.The incongruities caused due to a neurotoxicant further depend on the toxicity of the compound.More importantly,the neurotoxicity of the compound is associated with the concentration and the time point of exposure.The neurodevelopmental defect appears depending on the toxicity of the compound.A neurodevelopmental defect may be associated with a delay in developmental time,defective growth,structural abnormality of many organs,including sensory organs,behavioral abnormalities,or death in the fetus stage.Numerous model organisms are employed to assess the effect of neurotoxicants.The current review summarizes several methods used to check the effect of neurotoxicant and their effect using the model organism Drosophila melanogaster.

Structural Variations in Wing Patterning of Seasonal Polyphenic Melanitis leda (Satyrinae)

Seasonal polyphenism is a common phenomenon observed among members of the Lepidopteran subfamily Satyrinae. Melanitis leda, being a member of that subfamily, exhibits seasonal variation in terms of wing patterning. In butterflies, wing patterning is due to the nanostructural architecture of the scales, which reflects and refracts incident light, with or without the combination of pigments. The current scanning electron, fluorescence and optical microscope study divulge fine structural and signal changes that occur with different season in the scales of M. leda and give rise to the different wing pattern in butterfly. The structural and consequent signal changes are likely to be correlated with behavioural processes such as mate selection and escape from predation.

Fine structural description of the compound eye of the Madagascar ＇hissing cockroach＇ Gromphadorhinaportentosa （Dictyoptera： Blaberidae）

The compound eyes of the wingless adults of the Madagascar ＇hissing cockroach＇ Gromphadorhinaportentosa Sachum, 1853 were examined by light and electron microscopy. Each eye contains 2 400-2 500 mostly hexagonal facets. However, irregularities affecting both shape and size of the ommatidia are relatively common, especially towards the margins of the eye. An individual ommatidium of this eucone type of apposition eye contains eight retinula cells, which give rise to a centrally-fused, tiered rhabdom. The distal end of the latter is funnel-shaped and accommodates the proximal end of the cone in its midst, Further below, the rhabdom （then formed by the rhabdomeres of four retinula cells） assumes a squarish profile with microvilli aligned in two directions at right-angle to each other. Cross sections through the proximal regions of the rhabdom display triangular rhabdom outlines and microvilli （belonging to 3-4 retinula cells different from those involved in the squarish more distal rhabdom） that run in three directions inclined to one another by 120°. Overall the organization of the eye conforms to the orthopteroid pattern and particularly closely resembles that of the American cockroach Periplaneta americana. However, since G. portentosa possesses fewer ommatidia, this could be a consequence of its inability to fly. On the other hand, the large size of the facets and the voluminous rhabdoms suggest considerable absolute sensitivity and an ability to detect the plane of linearly polarized light. Based on the pattern of microvillus orientations in combination with the crepuscular lifestyle G. portentosa leads and the habitat it occurs in, the prediction is made that this insect uses its green receptors for e-vector discrimination in the environment of down-welling light that reaches the forest floor.

Impact of Hierarchical Architecture of Cryptotermes brevis Wing on the Modulation of Bacterial Adhesion

The wing architecture is an inspiration to fabricate novel materials with exquisite properties.The current study characterizes the structure and biological function of a termite’s wing.The topography of the surface of the wing was studied by electron microscopy,and surface profilometer.The physicochemical property of the surface was analyzed by Fourier transform infrared spectroscopy,X-ray diffraction spectroscopy,energy-dispersive X-ray spectroscopy,and gas chromatography-mass spectrometry analysis of the epicuticle content.Water Contact Angle measurement confirmed the hydrophobicity of the wing surface.When microorganisms come in contact with the surface of the wing,they adhere to the wing surface due to cell surface properties of their own and the surface chemistry of the wing.The current study reported the adhesion behavior of two bacterial species.The bactericidal activity of the wing was confirmed by counting the bacterial cell viability and examination under a confocal laser scanning microscope.Adhesion of bacteria was observed under the electron microscope.Bacterial oxidative stress,the topography of the wing,and the surface chemistry of the wing are the crucial factors that induce bactericidal activity.The nanostructure along with the chemical composition of the wing can be mimicked for the fabrication of novel material with antibacterial properties.