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Ecdysis is the moulting of the cuticle in many invertebrates of the clade Ecdysozoa. Since the cuticle of these animals typically forms a largely inelastic exoskeleton, it is shed during growth and a new, larger covering is formed. The remnants of the old, empty exoskeleton are called exuviae.
Drosophila melanogaster is a species of fly in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly" or "pomace fly". Starting with Charles W. Woodworth's 1901 proposal of the use of this species as a model organism, D. melanogaster continues to be widely used for biological research in genetics, physiology, microbial pathogenesis, and life history evolution. As of 2017, five Nobel Prizes have been awarded to drosophilists for their work using the insect.
A pupa is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their life cycle, the stages thereof being egg, larva, pupa, and imago. The processes of entering and completing the pupal stage are controlled by the insect's hormones, especially juvenile hormone, prothoracicotropic hormone, and ecdysone. The act of becoming a pupa is called pupation, and the act of emerging from the pupal case is called eclosion or emergence.
Drosophila embryogenesis, the process by which Drosophila embryos form, is a favorite model system for genetics and developmental biology. The study of its embryogenesis unlocked the century-long puzzle of how development was controlled, creating the field of evolutionary developmental biology. The small size, short generation time, and large brood size make it ideal for genetic studies. Transparent embryos facilitate developmental studies. Drosophila melanogaster was introduced into the field of genetic experiments by Thomas Hunt Morgan in 1909.
Neuropeptides are chemical messengers made up of small chains of amino acids that are synthesized and released by neurons. Neuropeptides typically bind to G protein-coupled receptors (GPCRs) to modulate neural activity and other tissues like the gut, muscles, and heart.
Hox genes, a subset of homeobox genes, are a group of related genes that specify regions of the body plan of an embryo along the head-tail axis of animals. Hox proteins encode and specify the characteristics of 'position', ensuring that the correct structures form in the correct places of the body. For example, Hox genes in insects specify which appendages form on a segment, and Hox genes in vertebrates specify the types and shape of vertebrae that will form. In segmented animals, Hox proteins thus confer segmental or positional identity, but do not form the actual segments themselves.
FlyBase is an online bioinformatics database and the primary repository of genetic and molecular data for the insect family Drosophilidae. For the most extensively studied species and model organism, Drosophila melanogaster, a wide range of data are presented in different formats.
Period (per) is a gene located on the X chromosome of Drosophila melanogaster. Oscillations in levels of both per transcript and its corresponding protein PER have a period of approximately 24 hours and together play a central role in the molecular mechanism of the Drosophila biological clock driving circadian rhythms in eclosion and locomotor activity. Mutations in the per gene can shorten (perS), lengthen (perL), and even abolish (per0) the period of the circadian rhythm.
Planar Cell Polarity (PCP) is the protein mediated signaling that coordinates the orientation of cells in a layer of epithelial tissue. In vertebrates, examples of mature PCP oriented tissue are the stereo-cilia bundles in the inner ear, motile cilia of the epithelium, and cell motility in epidermal wound healing. Additionally, PCP is known to be crucial to major developmental time points including coordinating convergent extension during gastrulation and coordinating cell behavior for neural tube closure. Cells orient themselves and their neighbors by establishing asymmetric expression of PCP components on opposing cell members within cells to establish and maintain the directionality of the cells. Some of these PCP components are transmembrane proteins which can proliferate the orientation signal to the surrounding cells.
Crustacean cardioactive peptide (CCAP) is a highly conserved, amidated cyclic nonapeptide with the primary structure PFCNAFTGC-NH2 (ProPheCysAsnAlaPheTyrGlyCys-NH2) and a disulfide bridge between Cys3 and Cys9. It is found in crustaceans and insects where it behaves as a cardioaccelerator, neuropeptide transmitter for other areas of the nervous system and a hormone. CCAP was first isolated from the pericardial organs of the shore crab Carcinus maenas, where it has a role in regulating heartbeat. It was assumed that this was the peptide's main function and its name reflects this.
Orthodenticle (otd) is a homeobox gene found in Drosophila that regulates the development of anterior patterning, with particular involvement in the central nervous system function and eye development. It is located on the X chromosome. The gene is an ortholog of the human OTX1/OTX2 gene.
The halloween genes are a set of genes identified in Drosophila melanogaster that influence embryonic development. All of the genes code for cytochrome P450 enzymes in the ecdysteroidogenic pathway (biosynthesis of ecdysone from cholesterol). Ecdysteroids such as 20-hydroxyecdysone and ecdysone influence many of the morphological, physiological, biochemical changes that occur during molting in insects.
Naked cuticle (Nkd) is a conserved family of intracellular proteins encoded in most animal genomes. The original mutants were discovered by 1995 Nobel laureates Christiane Nüsslein-Volhard and Eric F. Wieschaus and colleagues in their genetic screens for pattern-formation mutants in the fruit fly Drosophila melanogaster. The Nkd gene family was first cloned in the laboratory of Matthew P. Scott. Like many cleverly named fly mutants, the name "naked cuticle" derives from the fact that mutants lack most of the hair-like protrusions from their ventral cuticle and thus appear "naked".
Ronald J. Konopka (1947-2015) was an American geneticist who studied chronobiology. He made his most notable contribution to the field while working with Drosophila in the lab of Seymour Benzer at the California Institute of Technology. During this work, Konopka discovered the period (per) gene, which controls the period of circadian rhythms.
Pigment dispersing factor (pdf) is a gene that encodes the protein PDF, which is part of a large family of neuropeptides. Its hormonal product, pigment dispersing hormone (PDH), was named for the diurnal pigment movement effect it has in crustacean retinal cells upon its initial discovery in the central nervous system of arthropods. The movement and aggregation of pigments in retina cells and extra-retinal cells is hypothesized to be under a split hormonal control mechanism. One hormonal set is responsible for concentrating chromatophoral pigment by responding to changes in the organism's exposure time to darkness. Another hormonal set is responsible for dispersion and responds to the light cycle. However, insect pdf genes do not function in such pigment migration since they lack the chromatophore.
Dally is the name of a gene that encodes a HS-modified-protein found in the fruit fly. The protein has to be processed after being codified, and in its mature form it is composed by 626 amino acids, forming a proteoglycan rich in heparin sulfate which is anchored to the cell surface via covalent linkage to glycophosphatidylinositol (GPI), so we can define it as a glypican. For its normal biosynthesis it requires sugarless (sgl), a gene that encodes an enzyme which plays a critical role in the process of modification of dally.
Cycle (cyc) is a gene in Drosophila melanogaster that encodes the CYCLE protein (CYC). The Cycle gene (cyc) is expressed in a variety of cell types in a circadian manner. It is involved in controlling both the sleep-wake cycle and circadian regulation of gene expression by promoting transcription in a negative feedback mechanism. The cyc gene is located on the left arm of chromosome 3 and codes for a transcription factor containing a basic helix-loop-helix (bHLH) domain and a PAS domain. The 2.17 kb cyc gene is divided into 5 coding exons totaling 1,625 base pairs which code for 413 aminos acid residues. Currently 19 alleles are known for cyc. Orthologs performing the same function in other species include ARNTL and ARNTL2.
Drosophila circadian rhythm is a daily 24-hour cycle of rest and activity in the fruit flies of the genus Drosophila. The biological process was discovered and is best understood in the species Drosophila melanogaster. Other than normal sleep-wake activity, D. melanogaster has two unique daily behaviours, namely regular vibration during the process of hatching from the pupa, and during mating. Locomotor activity is maximum at dawn and dusk, while eclosion is at dawn.
James "Jim" William Truman is an American chronobiologist known for his seminal research on circadian rhythms in silkmoth (Saturniidae) eclosion, particularly the restoration of rhythm and phase following brain transplantation. He is a professor emeritus at the University of Washington and a former senior fellow at Howard Hughes Medical Institution Janelia Research Campus.
Abdominal pigmentation in Drosophila melanogaster is a morphologically simple but highly variable trait that often has adaptive significance. Pigmentation has extensively been studied in Drosophila melanogaster. It has been used as a model for understanding the development and evolution of morphological phenotypes.
References
- 1 2 3 Dewey EM, McNabb SL, Ewer J, et al. (July 2004). "Identification of the gene encoding bursicon, an insect neuropeptide responsible for cuticle sclerotization and wing spreading". Curr. Biol. 14 (13): 1208–13. doi: 10.1016/j.cub.2004.06.051 . PMID 15242619.
- ↑ Fraenkel G, Hsiao C, Seligman M (January 1966). "Properties of bursicon: an insect protein hormone that controls cuticular tanning". Science. 151 (3706): 91–3. doi:10.1126/science.151.3706.91. PMID 5908970. S2CID 39062433.
- ↑ Huang J, Zhang Y, Li M, et al. (February 2007). "RNA interference-mediated silencing of the bursicon gene induces defects in wing expansion of silkworm". FEBS Lett. 581 (4): 697–701. doi: 10.1016/j.febslet.2007.01.034 . PMID 17270178. S2CID 21816309.
- ↑ Luo CW, Dewey EM, Sudo S, Ewer J, Hsu SY, Honegger HW, Hsueh AJ (February 2005). "Bursicon, the insect cuticle-hardening hormone, is a heterodimeric cystine knot protein that activates G protein-coupled receptor LGR2". Proc. Natl. Acad. Sci. U.S.A. 102 (8): 2820–5. doi: 10.1073/pnas.0409916102 . PMC 549504 . PMID 15703293.