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Kom Sukontason - One of the best experts on this subject based on the ideXlab platform.
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morphology of puparia of Megaselia scalaris diptera phoridae a fly species of medical and forensic importance
Parasitology Research, 2006Co-Authors: Worachote Boonsriwong, Somsak Piangjai, Sirisuda Siriwattanarungsee, Kom SukontasonAbstract:Megaselia scalaris (Loew), a scuttle fly, is a fly species of medical and forensic importance. For use in forensic investigation, fly specimens found to associate with human corpses have to be identified at species level. Herein, we present the morphology of the puparia of the above fly species using scanning electron microscopy. The characteristic of the intersegmental spines along the dorsal and lateral segments and sculpture of the pupal respiratory horn of this puparia may be useful in future studies, to distinguish it from other closely related species.
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ultrastructure of the ommatrichia in Megaselia scalaris loew diptera phoridae
Micron, 2005Co-Authors: Kom Sukontason, Somsak Piangjai, Wej Choochote, Roy C. VogtsbergerAbstract:Using both scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the ommatrichia, or hair-like processes that are located between the facets of the compound eye, were examined on an adult male Megaselia scalaris (Loew) fly. Each ommatrichium was observed to be a tapering structure bearing a longitudinally grooved cuticle and are anchored tightly in flexible sockets. Ultrathin sectioning and TEM revealed a thick wall in the ommatrichia, and their function was proposed to be mechanoreception based on characteristics from both SEM and TEM observations.
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Ultrastructure of Coeloconic Sensilla on Postpedicel and Maxillary Palp of Megaselia scalaris (Diptera: Phoridae)
Annals of the Entomological Society of America, 2005Co-Authors: Kom Sukontason, Roy C. Vogtsberger, Noppawan Boonchu, Tarinee Chaiwong, Somsak Piangjai, Henry DisneyAbstract:The external morphology of coeloconic sensilla (peg-like sense organs protruding from deep pits) on the postpedicel (third antennal segment) and maxillary palp from a female Megaselia scalaris (Loew) is described using scanning electron microscopy. The pegs of the sensilla located on the postpedicel are “starfruit-like” in shape and are completely contained within deep depressions. Transmission electron microscopy showed that each peg has a thick and nonporous wall. The coeloconic sensilla of the maxillary palps are long, linear, and blunt-tipped and protrude over the cuticular surface. Possible functions of the sensilla are discussed.
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observations on first and second instar larvae of Megaselia scalaris loew diptera phoridae
Journal of Vector Ecology, 2004Co-Authors: Noppawan Boonchu, Kom Sukontason, Tarinee Chaiwong, Somsak Piangjai, Roy C. VogtsbergerAbstract:The ultrastructure of the first and second-instar larvae of Megaselia scalaris (Loew) was studied using scanning electron microscopy (SEM). Significant changes in morphological features were observed in the anterior and posterior spiracles, but only minimal changes in the labium and mouthhooks were seen. The ultrastructure of M. scalaris larvae not only provides chronological transformation of their larval instars, but it can also be used to explain their feeding behavior and mode of respiration. In addition, morphological structures useful for specific identification of first or second-instar larvae collected from human corpses may be used in forensic investigations.
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mouthparts of Megaselia scalaris loew diptera phoridae
Micron, 2003Co-Authors: Kom Sukontason, Noppawan Boonchu, Tarinee Chaiwong, Somsak Piangjai, Roy C. VogtsbergerAbstract:Mouthparts of adult Megaselia scalaris (Loew), a fly species of medical importance, were examined using scanning electron microscopy. Sexual dimorphism of the labellum was observed in the mouthpart structures of this species. The labella of males were clothed with a dense covering of microtrichia, but these were found to be entirely absent from the labella of females. Aside from this difference, trichoid and conical sensilla that are most likely used as taste or contact chemoreceptors appear on the labellum and labrum of both sexes. In addition, five pairs of sharply pointed teeth at the ventral surface of the labellum is another feature that is shared by the two sexes. A plausible feeding mechanism for this fly is also advanced.
John T Trumble - One of the best experts on this subject based on the ideXlab platform.
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effects of contaminants of emerging concern on Megaselia scalaris lowe diptera phoridae and its microbial community
Scientific Reports, 2017Co-Authors: Marcus J Pennington, Jason Rothman, Michael B Jones, Quinn S Mcfrederick, Jay Gan, John T TrumbleAbstract:Drought, rising temperatures, and expanding human populations are increasing water demands. Many countries are extending potable water supplies by irrigating crops with wastewater. Unfortunately, wastewater contains biologically active, long-lived pharmaceuticals, even after treatment. Run-off from farms and wastewater treatment plant overflows contribute high concentrations of pharmaceuticals to the environment. This study assessed the effects of common pharmaceuticals on a cosmopolitan saprophagous insect, Megaselia scalaris (Diptera: Phoridae). Larvae were reared on artificial diets spiked with contaminants of emerging concern (CECs) at environmentally relevant concentrations. Female flies showed no oviposition preference for treated or untreated diets. Larvae exposed to caffeine in diets showed increased mortality, and larvae fed antibiotics and hormones showed signs of slowed development, especially in females. The normal sex ratio observed in M. scalaris from control diets was affected by exposure to caffeine and pharmaceutical mixture treatments. There was an overall effect of treatment on the flies' microbial communities; notably, caffeine fed insects displayed higher microbial variability. Eight bacterial families accounted for approximately 95% of the total microbes in diet and insects. Our results suggest that CECs at environmentally relevant concentrations can affect the biology and microbial communities of an insect of ecological and medical importance.
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chronic exposure to elevated levels of manganese and nickel is not harmful to a cosmopolitan detritivore Megaselia scalaris diptera phoridae
Insect Science, 2009Co-Authors: Mary A Sorensen, Mae C Chasedunn, John T TrumbleAbstract:Environmental contamination with metals such as manganese (Mn) and nickel (Ni) often results in elevated concentrations of these metals in plant tissues. At high concentrations, these metals are known to have detrimental effects on certain insect herbivores. Using laboratory bioassays and artificial diet, we investigated the development and survival of a cosmopolitan insect detritivore, Megaselia scalaris (Diptera: Phoridae), exposed to concentrations of Mn and Ni reaching 2 600 mg Mn/kg and 5 200 mg Ni/kg dry mass (dm) in artificial diet. Surprisingly, Ni and Mn at the concentrations tested did not harm this fly. Treatment groups from diets with 260-2 600 mg Mn/kg dm and 1 300-5 200 mg Ni/kg dm had significantly shorter larval development times, overall times to adult emergence, and both pupariation and pupal eclosion times compared to a control group. Wing length of females, a correlate of adult fitness, was also greater in metal treatment groups. Other measures including rate of egg hatch, percentage of emerging flies that were female, and wing length of male flies, were not significantly different in metal treatment groups. We conclude that Megaselia scalaris is tolerant of exceptionally high levels of Mn and Ni.
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Individual and joint actions of selenate and methylmercury on the development and survival of insect detritivore Megaselia scalaris (Diptera: Phoridae).
Archives of environmental contamination and toxicology, 2006Co-Authors: P. D. Jensen, L. R. Johnson, John T TrumbleAbstract:Despite the important roles played by insects in most ecosystems, surprisingly little is known about how anthropogenic pollutants or their mixtures interact to affect insect populations. The independent and joint actions of selenate and methylmercury on a ubiquitous insect detritivore, Megaselia scalaris (Loew), were determined in this study. Ovipositing females did not distinguish between untreated food sources and those contaminated with toxic concentrations of selenate, methylmercury, or both chemicals in combination. Even at the highest concentrations of pollutants, no negative effects were observed for the egg stage. However, larval survival was significantly decreased and development significantly prolonged by selenate and methylmercury individually at low or intermediate ecologically relevant treatment levels. Potentiation was strongly evident because mixtures containing concentrations as little as only 1% of the respective individual median lethal tolerances (LC50s) caused significantly more mortality and delayed larval development than would be expected from the responses selenate and methylmercury elicit individually. However, survival and pupal development was not affected at any rate tested. Female fecundity was significantly decreased by methylmercury but not by selenate or mixture treatments. The relative toxicity to M. scalaris of each of the individual and joint treatments was selenate (LC50 = 260 μg/g) < methylmercury (LC50 = 22 μg/g) < the mixture at approximately 5% of the LC50 concentration of each of the components (12 μg/g selenate plus 1.0 μg/g methylmercury). The increased mortality and delayed larval development within sites contaminated by selenate, methylmercury, or combination of the two have substantial implications for the ecology, population dynamics, and sustainability of M. scalaris populations. If these results can be extrapolated to other arthropod detritivores, ecosystem food-web function may be substantially affected.
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developmental responses of a terrestrial insect detritivore Megaselia scalaris loew to four selenium species
Ecotoxicology, 2005Co-Authors: Peter D Jensen, Maria D Rivas, John T TrumbleAbstract:Megaselia scalaris (Loew) (Diptera: Phoridae) is an important and ubiquitous terrestrial detri- tivore that consumes both animal and plant material. Because both plants and animals convert selenium pollutants into various forms, the relative toxicities of ecologically relevant concentrations of sodium selenate, sodium selenite, seleno-L-methionine, and Se-(methyl) selenocysteine hydrochloride to larvae were assessed in diet bioassays. In addition, ovipositional preferences of adults and developmental effects on the eggs and larvae were measured. With chronic exposure selenocysteine was the most toxic of the selenium species to the larvae (LC50 :8 3lg/g wet weight), followed by seleno-L-methionine (LC50: 130 lg/g), selenate (LC50: 258 lg/g), and selenite (LC50: 392 lg/g). Ovipositing females did not discriminate between the highest treatment concentrations of any of the pollutants as compared to the controls, indicating a lack of avoidance behavior. Larval development time was significantly increased with exposure to selenate at 100 lg/g wet weight and above, selenite at 300 lg/g and above, and at 50 lg/g and 25 lg/g and above for seleno-L-methionine and selenocysteine respectively. Pupal development was not affected by any of the selenium treatments. Significant differences between male and female adult eclosion times were observed, with females eclosing later than males as selenium concentrations increased. Significant decreases in larval survival relative to controls occurred at the lowest treatment tested (100 lg/g) for both selenate and selenite and at 100 lg/g for seleno-L-methionine, and 50 lg/g for selenocysteine. The population level implications of lack of avoidance of contaminated food, and the effects of increased development times, reduced survivorship, and non-synchronized male and female emergence are discussed.
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ovipositional response developmental effects and toxicity of hexavalent chromium to Megaselia scalaris a terrestrial detritivore
Archives of Environmental Contamination and Toxicology, 2004Co-Authors: John T Trumble, Peter D JensenAbstract:The effects of hexavalent chromium (Cr VI) on ovipositional response, development, and survival of a common terrestrial detritivore, Megaselia scalaris (Diptera: Phoridae), were assessed in the laboratory. Ovipositing females did not discriminate between substrates containing 0, 50, 500, or 1000 µg/g, indicating a lack of avoidance behavior. Eggs placed on artificial diets containing up to 1000 µg/g either did not absorb Cr VI or were unaffected as measured by eclosion rates. However, development and survival of larvae were significantly reduced at the higher concentrations tested. Concentrations of 500 µg/g in their food increased larval development times by nearly 65%. At 1000 µg/g, larval developmental times doubled. The time required from onset to completion of pupariation was not significantly different regardless of Cr VI concentration. Although males eclosed before females, there was no significant difference between the sexes in the time required for adult eclosion. In addition, there were no signifi- cant differences in the percentage of males and females emerging from any of the treatments. At concentrations of 500 or 1000 µg/g, Cr VI decreased larval survival. Survival was reduced by 44.3% at 500 µg/g as compared with the controls. There was no additional mortality from the onset of the puparial stage to adult eclosion for larvae fed diets containing 500 µg/g Cr VI. At 1000 µg/g Cr VI, larval survival decreased by 86.6%. An additional 7.4% mortality was recorded in the puparial stage, for a decrease in total survival (larval plus puparial stages) of 94%. Thus, nearly all of the observed mortality occurred during the larval stage rather than the puparial stage. The population level implications of lack of avoidance of contaminated food and the effects of increased developmental times and reduced survivorship are discussed.
Roy C. Vogtsberger - One of the best experts on this subject based on the ideXlab platform.
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ultrastructure of the ommatrichia in Megaselia scalaris loew diptera phoridae
Micron, 2005Co-Authors: Kom Sukontason, Somsak Piangjai, Wej Choochote, Roy C. VogtsbergerAbstract:Using both scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the ommatrichia, or hair-like processes that are located between the facets of the compound eye, were examined on an adult male Megaselia scalaris (Loew) fly. Each ommatrichium was observed to be a tapering structure bearing a longitudinally grooved cuticle and are anchored tightly in flexible sockets. Ultrathin sectioning and TEM revealed a thick wall in the ommatrichia, and their function was proposed to be mechanoreception based on characteristics from both SEM and TEM observations.
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Ultrastructure of Coeloconic Sensilla on Postpedicel and Maxillary Palp of Megaselia scalaris (Diptera: Phoridae)
Annals of the Entomological Society of America, 2005Co-Authors: Kom Sukontason, Roy C. Vogtsberger, Noppawan Boonchu, Tarinee Chaiwong, Somsak Piangjai, Henry DisneyAbstract:The external morphology of coeloconic sensilla (peg-like sense organs protruding from deep pits) on the postpedicel (third antennal segment) and maxillary palp from a female Megaselia scalaris (Loew) is described using scanning electron microscopy. The pegs of the sensilla located on the postpedicel are “starfruit-like” in shape and are completely contained within deep depressions. Transmission electron microscopy showed that each peg has a thick and nonporous wall. The coeloconic sensilla of the maxillary palps are long, linear, and blunt-tipped and protrude over the cuticular surface. Possible functions of the sensilla are discussed.
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observations on first and second instar larvae of Megaselia scalaris loew diptera phoridae
Journal of Vector Ecology, 2004Co-Authors: Noppawan Boonchu, Kom Sukontason, Tarinee Chaiwong, Somsak Piangjai, Roy C. VogtsbergerAbstract:The ultrastructure of the first and second-instar larvae of Megaselia scalaris (Loew) was studied using scanning electron microscopy (SEM). Significant changes in morphological features were observed in the anterior and posterior spiracles, but only minimal changes in the labium and mouthhooks were seen. The ultrastructure of M. scalaris larvae not only provides chronological transformation of their larval instars, but it can also be used to explain their feeding behavior and mode of respiration. In addition, morphological structures useful for specific identification of first or second-instar larvae collected from human corpses may be used in forensic investigations.
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mouthparts of Megaselia scalaris loew diptera phoridae
Micron, 2003Co-Authors: Kom Sukontason, Noppawan Boonchu, Tarinee Chaiwong, Somsak Piangjai, Roy C. VogtsbergerAbstract:Mouthparts of adult Megaselia scalaris (Loew), a fly species of medical importance, were examined using scanning electron microscopy. Sexual dimorphism of the labellum was observed in the mouthpart structures of this species. The labella of males were clothed with a dense covering of microtrichia, but these were found to be entirely absent from the labella of females. Aside from this difference, trichoid and conical sensilla that are most likely used as taste or contact chemoreceptors appear on the labellum and labrum of both sexes. In addition, five pairs of sharply pointed teeth at the ventral surface of the labellum is another feature that is shared by the two sexes. A plausible feeding mechanism for this fly is also advanced.
Robin L. Cooper - One of the best experts on this subject based on the ideXlab platform.
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characterization of development behavior and neuromuscular physiology in the phorid fly Megaselia scalaris
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2003Co-Authors: Douglas A. Harrison, Robin L. CooperAbstract:The Phoridae is known as ‘scuttle flies’ because they walk in rapid bursts of movement with short pauses between. In this study, larval locomotive behavior and development was characterized in the phorid, Megaselia scalaris. Comparison was made with the well-characterized fruit fly model, Drosophila melanogaster. Developmentally, the rate of maturation was consistently slower for Megaselia than Drosophila. This disparity was exaggerated at lower temperatures, particularly during larval development. In addition to slower growth, movements in Megaselia were also slower, as evidenced by reduced rates of larval body wall contractions and mouth hook movements. Megaselia larvae also displayed a unique behavior of swallowing air when exposed to a small pool of liquid. This permitted floating upon immersion and, therefore, might prevent drowning in the natural environment. The anatomical and physiological properties of a neuromuscular junction in the phorid larvae were also examined. The innervation of the motor nerve terminals on the ventral abdominal muscle (m6) is innervated by Type Ib and Is axons, similar to Drosophila .A s in Drosophila, the Is terminals produce larger excitatory postsynaptic potentials (EPSPs) than the Ib. The amplitudes of the EPSPs in M. scalaris were reduced compared to those of D. melanogaster, but unlike D. melanogaster the EPSPs showed marked facilitation when stimulated with a 20 Hz train. We conclude that there may be differences in synaptic structure of the nerve terminals that could account for the different electrophysiological behaviors. 2003 Elsevier Science Inc. All rights reserved.
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Characterization of development, behavior and neuromuscular physiology in the phorid fly, Megaselia scalaris
Comparative biochemistry and physiology. Part A Molecular & integrative physiology, 2003Co-Authors: Douglas A. Harrison, Robin L. CooperAbstract:The Phoridae is known as 'scuttle flies' because they walk in rapid bursts of movement with short pauses between. In this study, larval locomotive behavior and development was characterized in the phorid, Megaselia scalaris. Comparison was made with the well-characterized fruit fly model, Drosophila melanogaster. Developmentally, the rate of maturation was consistently slower for Megaselia than Drosophila. This disparity was exaggerated at lower temperatures, particularly during larval development. In addition to slower growth, movements in Megaselia were also slower, as evidenced by reduced rates of larval body wall contractions and mouth hook movements. Megaselia larvae also displayed a unique behavior of swallowing air when exposed to a small pool of liquid. This permitted floating upon immersion and, therefore, might prevent drowning in the natural environment. The anatomical and physiological properties of a neuromuscular junction in the phorid larvae were also examined. The innervation of the motor nerve terminals on the ventral abdominal muscle (m6) is innervated by Type Ib and Is axons, similar to Drosophila. As in Drosophila, the Is terminals produce larger excitatory postsynaptic potentials (EPSPs) than the Ib. The amplitudes of the EPSPs in M. scalaris were reduced compared to those of D. melanogaster, but unlike D. melanogaster the EPSPs showed marked facilitation when stimulated with a 20 Hz train. We conclude that there may be differences in synaptic structure of the nerve terminals that could account for the different electrophysiological behaviors.
Walther Traut - One of the best experts on this subject based on the ideXlab platform.
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the sex determining gene doublesex in the fly Megaselia scalaris conserved structure and sex specific splicing
Genome, 2000Co-Authors: Sylvia Kuhn, Volker Sievert, Walther TrautAbstract:The well-known sex-determining cascade of Drosophila melanogaster serves as a paradigm for the pathway to sexual development in insects. But the primary sex-determining signal and the subsequent step, Sex-lethal (Sxl), have been shown not to be functionally conserved in non-Drosophila flies. We isolated doublesex (dsx), which is a downstream step in the cascade, from the phorid fly Megaselia scalaris, which is a distant relative of D. melanogaster. Conserved properties, e.g., sex-specific splicing, structure of the female-specific 3' splice site, a splicing enhancer region with binding motifs for the TRA2/RBP1/TRA complex that activates female-specific splicing in Drosophila, and conserved domains for DNA-binding and oligomerization in the putative DSX protein, indicate functional conservation of dsx in M. scalaris. Hence, the dsx step of the sex-determining pathway appears to be conserved among flies and probably in an even wider group of insects, as the analysis of a published cDNA from the silkmoth ind...
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tromb a new retrotransposon of the gypsy ty3 group from the fly Megaselia scalaris
Gene, 2000Co-Authors: Garnet Suck, Walther TrautAbstract:Abstract We describe TROMB , a new LTR retrotransposon, from the phorid fly Megaselia scalaris . Three full-length copies (4226, 4160 and 4129 bp) and a truncated one (319 bp) have been isolated. The target site consensus is TATAT, with a 4 bp target site duplication TATA. The LTRs are short (142 bp) and contain a TATA-box and a polyadenylation signal. The isolated copies are degenerate to different degrees and presumably inactive. The polyprotein coding sequence contains scattered stop codons and deletions/insertions at non-homologous positions. The consensus sequence among the three full-length copies, however, has an uninterrupted open reading frame and, presumably, represents the original sequence of the active element. Southern hybridization experiments showed TROMB to be present at a low copy number in two wild-type strains of M. scalaris and absent in a related species, M. abdita . The order of domains in the polyprotein coding region, the target site specificity for AT-rich sequences, and the protein sequence similarity to blastopia , mdg3 and micropia place TROMB in the gypsy – Ty3 group of LTR retrotransposons.
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sequence conservation and expression of the sex lethal homologue in the fly Megaselia scalaris
Genome, 2000Co-Authors: Volker Sievert, Sylvia Kuhn, Achim Paululat, Walther TrautAbstract:Sex-lethal (Sxl) is Drosophila melanogaster's key regulating gene in the sex-determining cascade. Its homologue in Megaselia scalaris, the chromosome 3 gene Megsxl, codes for a protein with an overall similarity of 77% with the corresponding D. melanogaster sequence. Expression in M. scalaris, however, is very unlike that in D. melanogaster. Megsxl transcripts with a long ORF occur in both sexes. Differential splicing is conserved but not sex-specific. There are several splice variants, among them one is common to gonads and somatic tissues of all developmental stages investigated, one is specific for ovaries and embryos, and a third one is not found in ovaries. In the ovary, Megsxl is heavily transcribed in nurse cells and transported into eggs. These results suggest a non-sex-determining function during early embryogenesis; the presence of Megsxl RNA in testes and somatic tissues calls for other (or more) functions. Key words: sex determination, RNA-binding domain, differential splicing, RNA in situ hyb...
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an x y dna segment from an early stage of sex chromosome differentiation in the fly Megaselia scalaris
Genome, 1998Co-Authors: Walther Traut, Brigitte WollertAbstract:The sex chromosomes of the Megaselia scalaris wild-type strain Wien are homomorphic. We studied a roughly 1.8 kb X/Y DNA segment of this strain. It includes, at one end, the first part of a coding sequence for a protein of the vespid antigen 5 family. Molecular differentiation between the X and Y chromosomes has commenced, but homology, even of short DNA stretches, is still assessable beyond doubt. The most conspicuous differences between the X and the homologous Y segment were insertions/deletions in the noncoding region: among them, deletions, a duplication, and an insertion of a mobile element. These structural changes grossly disrupted homology. In comparison, base substitutions, though more numerous, contributed little to the differentiation of the X/Y DNA segment.
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sex determination in the fly Megaselia scalaris a model system for primary steps of sex chromosome evolution
Genetics, 1994Co-Authors: Walther TrautAbstract:The fly Megaselia scalaris Loew possesses three homomorphic chromosome pairs; 2 is the sex chromosome pair in two wild-type laboratory stocks of different geographic origin (designated "original" sex chromosome pair in this paper). The primary male-determining function moves at a very low rate to other chromosomes, thereby creating new Y chromosomes. Random amplified polymorphic DNA markers obtained by polymerase chain reaction with single decamer primers and a few available phenotypic markers were used in testcrosses to localize the sex-determining loci and to define the new sex chromosomes. Four cases are presented in which the primary male-determining function had been transferred from the original Y chromosome to a new locus either on one of the autosomes or on the original X chromosome, presumably by transposition. In these cases, the sex-determining function had moved to a different locus without an obvious cotransfer of other Y chromosome markers. Thus, with Megaselia we are afforded an experimental system to study the otherwise hypothetical primary stages of sex chromosome evolution. An initial molecular differentiation is apparent even in the new sex chromosomes. Molecular differences between the original X and Y chromosomes illustrate a slightly more advanced stage of sex chromosome evolution.