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Collins Complete Guide to British Insects. Guide to Insects of the British Isles. Insect Behavior. A Buzz in the Meadow. Insect Microscopy. The triatomine Rhodnius prolixus Hemiptera, Triatominae has an abdomen sensed by stretch receptors in the abdominal cuticle that distend when it feeds on blood. This process triggers the release of serotonin and an unidentified peptide from several neurons, including from the central nervous system, mesothoracic ganglia, and the corpora cardiaca.
Drosophila and mosquitoes have MTs with large and small cell types. The large cells are the principal cells, which are responsible for most of the mass of the tubule. The small cells are thin stellate cells. The movement of water across the MTs occurs by both transcellular and paracellular pathways. In Drosophila MTs, a multipotent stem cell was identified that is able to generate all cell types of the adult. Therefore, different molecular markers and clonal analysis bioassays showed that these cells are able to proliferate and differentiate into several types of cells.
Insects are an extremely ancient grouping of organisms with short life spans and, frequently, multiple generations per year that inhabit a wide variety of environmental niches. Because of this, the mechanisms of homeostasis control may show considerable variation between genera, even though the basic underlying themes are conserved. Insects are vulnerable to desiccation because of their small size and high surface area to volume ratio.
Water can be obtained from the diet, but in order to maintain fluid homeostasis, it must equal the water lost through evaporation, respiration, and excretion. Excretory water loss is determined by the rate at which fluid enters the hindgut from the midgut and MTs, and the rate of reabsorption therein.
They derive from the central nervous system CNS that exerts its control by means of neurohormones released into the extracellular fluid directly from the CNS, or other hormones from glands themselves controlled by the CNS hormones. For example, the TRPs are immunolabelling in brain neurons of M.
Diuretic hormones DHs and antidiuretic hormones ADHs are endocrine factors that affect the regulation of fluid excretion. These hormones consist of a diverse group of peptides that are produced by neurosecretory cells in the brain and ventral nerve cord ganglia. Despite its name, usually, DHs stimulate the secretion of primary urine by MTs, and ADHs aldosterone and vasopressin increase the reabsorption of fluid from the hindgut. Primary urine formation must be driven by active transport, not by blood pressure.
Since insects have low pressure circulatory systems, primary urine isosmotic to the hemolymph is secreted by the MTs. Generally, DHs increase MT secretion by stimulating ion transport into the lumen accompanied by osmotically obliged water osmotic filtration , which will either reduce MTs secretion or stimulate fluid and vital solute reabsorption in the hindgut. There are exceptions to the function of DHs, and sometimes their names do not precisely describe their actions. The main transport through membrane is the sodium-potassium pump that maintains the sodium gradient with energy required from ATP.
In the absence of ATP, or if the pump is poisoned by metabolic inhibitors, sodium leaks into the cell, and the sodium gradient disappears. Without the potential energy stored in the sodium gradient, indirect active transport processes such as the sodium-glucose cotransporter are unable to function. In bumblebee Bombus atratus , a histochemical analysis of MT identified a mucous secretion produced by this organ. The Malpighi tubules of the giant mealworm Zophobas morio Coleoptera, Tenebrionidae show a short antimicrobial peptides AMP -ligase with weak luciferase activity that diverged long ago from beetle luciferases.
Malpighian tubules of Drosophila melanogaster , in addition to their excretory function, act as autonomous immune sensing organs because their cells secrete AMP in response to invading microbial pathogens. The AMPs diptericin, cecropin A, drosocin, and attacin A are constitutively expressed and are regulated in a developmental stage-specific manner.
The MTs of insects are also known to have mechanisms of active transport to remove toxic compounds such as alkaloids from vegetal sources 8 and chemical compounds that are present in the environment and are toxic for insects. Different functions of MTs have emerged with the development of postgenomic technologies, mainly in Drosophila , such as microarrays, proteomics, and metabolomics.
Molecular studies are revealing the mechanisms and modulation of the cell signaling in the MT that are related to stress tolerance in insects. Catae et al 79 studied the effects of thiamethoxam in the midgut and MTs of the Apis mellifera honeybee. This study showed cellular responses of MTs after the commitment of the midgut induced by exposure to this neonicotinoid. Although they were described for the first time in the 17th century and despite their apparent simple morphological organization, the MTs are key organs, performing different functions at different stages of development.
In view of their importance for the maintenance of the individual homeostasis, and multiple assigned functions, many researchers are still devoted to studies of the MTs, and this review in no way exhausts the subject. Recently, the understanding of transepithelial transport in insect MTs and its regulation processes has advanced considerably. Genomic and proteomic analysis studies may elucidate their intracellular signaling mechanisms, 81 , 82 regulating the immune response, 83 in addition to other functions of MTs, as their relationship with the bioluminescence mechanism in some insects.
The results indicate that MTs can be used for the evaluation of biomarkers, at the cellular level, in toxicological studies, especially studies done with sublethal doses and concentrations of chemicals. The various roles played by MTs reflect the interactions that organisms have with the environment in which they live. The different habitats of various organisms that have MTs as excretory system reflect the plasticity presented by this organ, and it may have many other functions too that have not been described.
We can expect in the coming years, in light of the new techniques available and the development of the omic-sciences transcriptomics, proteomics, and metabolomics , that new data will further elucidate the different mechanisms by which MTs perform their functions. Snodgrass RE. Principles of insect morphology. Study of Insects. Edgard Blucha, Wigglesworth, VB. The principles of insect physiology.
New York: John Wiley Sons.
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WOA2 - Pesticidal genes and methods of use - Google Patents
Renal tubule development in Drosophila: a closer look at the cellular level. J Am Soc Nephrol. Chapman RF.
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The insects : Structure and function. Fourth Ed. Cambridge University Press, Cambridge, Bradley TJ. The excretory system: structure and physiology. Comprehensive Insect Physiology , Biochemistry and Pharmacology , vol. Arab A, Caetano FH.
blahreistikap.tk Segmental specializations in the Malpighian tubules of the fire ant Solenopsis saevissima Forel Myrmicinae : an electron microscopical study. Arthropod Struct Dev. Annu Rev Entomol. Cruz-Landim C. Morfology and function of systems. Cruz-Landim C, Rodrigues L. Development of rectal glands and Malpighian Tubules in bess from the genera Melipona, with relation to the humidity of their natural habitat. Comparative studies of Malpighian tubules from larvae, pupae and adults workers of Melipona quadrifasciata anthidioides Lep. Apidae, Meliponinae.
Localization of calcium and acid phosphatase in the Malpighian tubules of nurse workers of Melipona quadrifasciata anthidioides Lep. Hymenoptera, Apidae, Meliponini. Biosci J. Skaer HB. Development of the alimentary canal. In The Development of Drosophila , ed. Non-apoptotic function of apoptotic proteins in the development of Malpighian tubules of Drosophila melanogaster. J Biosci Bangalore. Ettershank G, Brown WL. The Malpighian tubules as meristic characters in ants Hym. Anatomy and histology of digestory tract from Dinoponera gigantea and Paraponera clavata Formicidae: Ponerinae.