DOCSLIB.ORG

Another Way of Being Anisogamous in Drosophila Subgenus

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Another Way of Being Anisogamous in Drosophila Subgenus Proc. NatI. Acad. Sci. USA Vol. 91, pp. 10399-10402, October 1994 Evolution Another way of being anisogamous in Drosophila subgenus species: Giant sperm, one-to-one gamete ratio, and high zygote provisioning (evoludtion of sex/paternty asune/male-derived contrIbutIon/Drosophia liftorais/Drosopha hydei) CHRISTOPHE BRESSAC*t, ANNE FLEURYl, AND DANIEL LACHAISE* *Laboratoire Populations, Gen6tique et Evolution, Centre National de la Recherche Scientifique, F-91198 Gif-sur-Yvette Cedex, France; and *Laboratoire de Biologie Cellulaire 4, Unit6 Recherche Associ6e 1134, Universit6 Paris XI, F-91405 Orsay Cedex, France Communicated by Bruce Wallace, July 11, 1994 ABSSTRACT It is generally assume that sexes n animals within-ejaculate short sperm heteromorphism in the Dro- have arisen from a productivity versus provisioning conflict; sophila obscura species group (Sophophora subgenus) to males are those individuals producing gametes n ily giant sperm found solely within the Drosophila subgenus. small, in excess, and individually bereft of all paternity assur- The most extreme pairwise comparison of sperm length ance. A 1- to 2-cm sperm, 5-10 times as long as the male body, between these taxonomic groups represents a factor of might therefore appear an evolutionary paradox. As a matter growth of 300 (12). In all Drosophila species described so far of fact, species ofDrosophila of the Drosophila subgenus differ in this respect, sperm contain a short acrosome, a filiform from those of other subgenera by producing exclusively sperm haploid nucleus, and a flagellum composed of two inactive of that sort. We report counts of such giant costly sperm in mitochondrial derivatives (13, 14) flanking one axoneme Drosophila littondis and Drosophila hydei females, indicating along its overall length: the longer the sperm, the larger the that they are offered in exceedingly small amounts, tending to flagellum and hence the more mitochondrial material. a one-to-one gamete ratio after a single mating. As a result, The cost of such exaggerated sperm and more generally of most ofthem are suces involved in a fertilization. Hence, sperm production is a matter of controversy in current the concept of "paternity assurance of individual sperm" thought on the evolution of sex since it happens to be arises. Evidence is further provided here that almost the entire substantial (15). Although definitely present in many orga- sperm Is incorporated into the egg during fertilization. Label- nisms, and more especially in vertebrates, the traditional ing with specific a ti in fertilized eggs reveals intact view on the universality of anisogamy has nevertheless been axonemes up to late gastrulation. The question, then, is why tempered by recent findings in nematodes that individuals selection has favored such an unusual strategy. Expations may produce more oocytes than sperm and that fecundity related to some preft functions are ruled out. It is may be limited by sperm production (16, 17). However, these therefore tentatively proposed that virtually every giant sperm organisms might appear somewhat heterodox considering consitutes a "direct paternal legacy to the embryo," which, in they are self-fertilizing hermaphrodites and their gamete contrast to any malederived nuptial glft, caunot be imd production switches from sperm to oocytes within each by female rematin. We suggest that dramatic shortage ofglant gonad (18, 19). If the productivity versus provisioning con- sperm with a high prospect of fusion and increased zygote flict is valid, there should exist a number of alternative provisioning is merely another way of being aniogamous. solutions. In fact, we report here empirical data based on sperm The evolution of anisogamy (two sexes) is traditionally counts in females and labeling in fertilized eggs in D. littoralis viewed as resulting from the conflicting demands of gamete and D. hydei consistently showing that the costs of making productivity on the one hand and zygote provisioning on the sperm happen to be considerably high in outcrossing orga- other (1-8). Central to the issue is the assumption that males nisms as well. Giant-sperm Drosophila have cracked the and females devote nearly equal amounts of resources to productivity/provisioning problem the other way round: it gamete production and that provisioning strongly affects turns out that some, though not all, Drosophila lineages have zygote survival. Implicit in this is a negative correlation evolved radically opposite evolutionary trends where male between sperm and oocyte outputs and between sperm gametes combine low productivity and high zygote provi- output and sperm length (9). However, drive to produce sioning with exaggerated size. The issue of why there is one smaller and smaller (i.e., male) gametes in increasing num- such sperm cell loaded with, for example in D. hydei, more bers might be countered because the zygotes produced have than 3 cm of inactive mitochondrial aggregates is actually a less provisioning and are consequently less viable and require functional as well as an evolutionary riddle. A possible clue more time to mature (10). The question is then whether drive to this is proposed in the present work suggesting that giant to produce enlarged male gametes can be evolutionary stable. sperm in these species, beyond transferring paternal genetic The evolution of sperm of inordinate length has sporadi- information, may be a direct resource donated to the off- cally occurred in the arthropod phylogenetic tree: ostracods spring. in crustaceans, Scutigera in millipedes, and waterbugs, ptiliid beetles, and fruitflies in insects (11, 12). Within Drosophila, MATERIALS AND METHODS this trend has seemingly been magnified uniquely in the subgenus Drosophila including Drosophila littoralis and Dro- Two species of the genus Drosophila, both of the subgenus sophila hydei, whose sperm length is on average 7.3 and 16.9 Drosophila, were used: mm, respectively; the latter produces the largest sperm so far (i) D. littoralis: Paris area, 1980 (collected by J. David). known among metazoans (12). In this way, Drosophila spe- (ii) D. hydei: Mt. Kenya (Kenya), altitude of 3050 m, cies provide a remarkable diversity ofsituations ranging from September 1984, Meteorological Station site, at top of bam- boo zone on the west side along the Naro Moru track D. M. L. Cariou, and M. Ashburner). The publication costs ofthis article were defrayed in part by page charge (collected by Lachaise, payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact. tTo whom reprint requests should be addressed. 10399 Downloaded by guest on September 30, 2021 10400 Evolution: Bressac et aL Proc. Nati. Acad. Sci. USA 91 (1994) Table 1. Number of giant sperm involved in one mating in two representatives of the Drosophila subgenus Sperm stored Sperm offered mean ± SE Sperm used Sperm used/ Species n mean + SE n Receptacle Spermatheca Total n mean + SE sperm offered D. littoralis 30 233.6 + 13.9 30 54.0 + 2.7 115.7 ± 3.9 169.7 ± 5.2 18 133.8 ± 5.2 0.57 D. hydei 30 83.4 ± 3.3 20 67.0 ± 1.8 3.1 ± 0.8 70.1 + 1.7 18 67.1 ± 2.0 0.80 n, Number of individuals tested. Both strains have been maintained in mass culture since Finally, the numbers of sperm used and sperm offered after collection. Considering late sexual maturity (20, 21), virgin one mating are very close to one another (compared to 7-day males and females were allowed to mate once and then nonrelatedD. melanogaster and afortiori nonrelated clades), separated. Sperm transferred. Thirty females for each spe- indicating that wastage is limited and gradual. As a result, the cies were dissected in PBS immediately after mating, and the ratio ofsperm used to sperm offered (that is, chance offusion contents of their uterine cavity were transferred onto a for each giant sperm) after one mating reaches exceedingly 12-mm diameter coverslip. This preparation was air dried, high values-0.57 in D. littoralis and 0.80 in D. hydei, fixed in ethanol (4 min at 200C), air dried again, and then respectively. incubated in a 4',6-diamidino-2-phenylindole solution (2 Of interest is the comparison of these data with some pg/ml in PBS) for 20 min at 200C. The coverslip was then available from the literature involving D. melanogaster, rinsed in PBS, mounted, and observed on an epifluorescence various other nonrelated insects (Papilio zelicaon and Schis- microscope. Sperm heads were counted exhaustively owing tocerca gregaria), and mammals (Fig. 1). Paternity assurance to their particular filiform shape. Sperm stored. For each ofindividual sperm-that is, the ratio ofsperm used to sperm species 30 females from another series were dissected 3 hr offered-increases from mammals to insects as a positive postmating and the same method was used on female storage function ofsperm length. Ofprimary importance is that while organs. 4',6-Diamidino-2-phenylindole-labeled sperm were insignificant (i.e., 10-9-10-6) in the former phylum, this value counted through the wall ofboth the unpaired ventral recep- becomes close to 1 in species producing exceedingly long tacle and the paired spermatheca. Sperm used. Eighteen sperm. inseminated females per species were individually placed in We used specific antibodies to label giant sperm axoneme oviposition boxes, and the hatched eggs were recorded daily, within just fertilized eggs and early embryos of the two giving an estimation of the number of sperm used. species (Fig. 2). Evidence is thereby provided for the incor- For confocal microscopic detection of the axoneme, em- poration ofthis complete or almost complete arthropod giant bryos were prepared according to Karr (22). A monoclonal sperm into the egg. In both species, the axoneme is detectable antibody, TAX49 (23), directed against axonemal tubulin during the first developmental stages. The giant sperm tail is from Paramecium, the specificity of which is similar to that tightly wound into a ball at the anterior end ofthe embryo up of the polyclonal antibody TAPp (24), was used as primary to early ventral furrow formation (i.e., early gastrulation).
Load more

Recommended publications
  • Sexual Selection, Sex Roles, and Sexual Conflict
    Downloaded from http://cshperspectives.cshlp.org/ on October 1, 2021 - Published by Cold Spring Harbor Laboratory Press The Sexual Cascade and the Rise of Pre-Ejaculatory (Darwinian) Sexual Selection, Sex Roles, and Sexual Conflict Geoff A. Parker Department of Evolution, Ecology and Behaviour, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom Correspondence: [email protected] After brief historic overviews of sexual selection and sexual conflict, I argue that pre-ejacu- latory sexual selection (the form of sexual selection discussed by Darwin) arose at a late stage in an inevitable succession of transitions flowing from the early evolution of syngamy to the evolution of copulation and sex roles. If certain conditions were met, this “sexual cascade” progressed inevitably, if not, sexual strategy remained fixed at a given stage. Prolonged evolutionary history of intense sperm competition/selection under external fertilization preceded the rise of advanced mobility, which generated pre-ejaculatory sexual selection, followed on land by internal fertilization and reduced sperm competition in the form of postcopulatory sexual selection. I develop a prospective model of the early evolution of mobility, which, as Darwin realized, was the catalyst for pre-ejaculatory sexual selection. Stages in the cascade should be regarded as consequential rather than separate phenomena and, as such, invalidate much current opposition to Darwin–Bateman sex roles. Potential for sexual conflict occurs throughout, greatly increasing later in the cascade, reaching its peak under precopulatory sexual selection when sex roles become highly differentiated. exual selection and sexual conflict are vast changed through evolutionary time, from Sfields in evolutionary biology; when possi- mostly gamete competition in early unicellu- ble, here, I refer to reviews.
    [Show full text]
  • Alan Robert Templeton
    Alan Robert Templeton Charles Rebstock Professor of Biology Professor of Genetics & Biomedical Engineering Department of Biology, Campus Box 1137 Washington University St. Louis, Missouri 63130-4899, USA (phone 314-935-6868; fax 314-935-4432; e-mail [email protected]) EDUCATION A.B. (Zoology) Washington University 1969 M.A. (Statistics) University of Michigan 1972 Ph.D. (Human Genetics) University of Michigan 1972 PROFESSIONAL EXPERIENCE 1972-1974. Junior Fellow, Society of Fellows of the University of Michigan. 1974. Visiting Scholar, Department of Genetics, University of Hawaii. 1974-1977. Assistant Professor, Department of Zoology, University of Texas at Austin. 1976. Visiting Assistant Professor, Dept. de Biologia, Universidade de São Paulo, Brazil. 1977-1981. Associate Professor, Departments of Biology and Genetics, Washington University. 1981-present. Professor, Departments of Biology and Genetics, Washington University. 1983-1987. Genetics Study Section, NIH (also served as an ad hoc reviewer several times). 1984-1992: 1996-1997. Head, Evolutionary and Population Biology Program, Washington University. 1985. Visiting Professor, Department of Human Genetics, University of Michigan. 1986. Distinguished Visiting Scientist, Museum of Zoology, University of Michigan. 1986-present. Research Associate of the Missouri Botanical Garden. 1992. Elected Visiting Fellow, Merton College, University of Oxford, Oxford, United Kingdom. 2000. Visiting Professor, Technion Institute of Technology, Haifa, Israel 2001-present. Charles Rebstock Professor of Biology 2001-present. Professor of Biomedical Engineering, School of Engineering, Washington University 2002-present. Visiting Professor, Rappaport Institute, Medical School of the Technion, Israel. 2007-2010. Senior Research Associate, The Institute of Evolution, University of Haifa, Israel. 2009-present. Professor, Division of Statistical Genomics, Washington University 2010-present.
    [Show full text]
  • Sex-Specific Spawning Behavior and Its Consequences in an External Fertilizer
    vol. 165, no. 6 the american naturalist june 2005 Sex-Specific Spawning Behavior and Its Consequences in an External Fertilizer Don R. Levitan* Department of Biological Science, Florida State University, a very simple way—the timing of gamete release (Levitan Tallahassee, Florida 32306-1100 1998b). This allows for an investigation of how mating behavior can influence mating success without the com- Submitted October 29, 2004; Accepted February 11, 2005; Electronically published April 4, 2005 plications imposed by variation in adult morphological features, interactions within the female reproductive sys- tem, or post-mating (or pollination) investments that can all influence paternal and maternal success (Arnqvist and Rowe 1995; Havens and Delph 1996; Eberhard 1998). It abstract: Identifying the target of sexual selection in externally also provides an avenue for exploring how the evolution fertilizing taxa has been problematic because species in these taxa often lack sexual dimorphism. However, these species often show sex of sexual dimorphism in adult traits may be related to the differences in spawning behavior; males spawn before females. I in- evolutionary transition to internal fertilization. vestigated the consequences of spawning order and time intervals One of the most striking patterns among animals and between male and female spawning in two field experiments. The in particular invertebrate taxa is that, generally, species first involved releasing one female sea urchin’s eggs and one or two that copulate or pseudocopulate exhibit sexual dimor- males’ sperm in discrete puffs from syringes; the second involved phism whereas species that broadcast gametes do not inducing males to spawn at different intervals in situ within a pop- ulation of spawning females.
    [Show full text]
  • Ecological Factors and Drosophila Speciation
    ECOLOGICAL FACTORS AND DROSOPHILA SPECIATION WARREN P. SPENCER, College of Wooster INTRODUCTION In 1927 there appeared H. J. Muller's announcement of the artificial transmutation of the gene. This discovery was received with enthusiasm throughout the scientific world. Ever since the days of Darwin biological alchemists had tried in vain to induce those seemingly rare alterations in genes which were coming to be known as "the building stones of evolution." In the same year Charles Elton published a short book on animal ecology. It was received with little acclaim. That is not sur- prising. To the modern biologist ecology has seemed a bit out-moded, rather beneath the dignity of a laboratory scientist. Without detracting from the importance of Muller's discovery, in the light of the develop- ments of the past 13 years we venture to say that Elton conies nearer to providing the key to the process of evolution than does radiation genetics. Here is a quotation from Elton's chapter on ecology and evolution. '' Many animals periodically undergo rapid increase with practically no checks at all. In fact the struggle for existence sometimes tends to disappear almost entirely. During the expansion in numbers from a minimum, almost every animal survives, or at any rate a very high proportion of them do so, and an immeasurably larger number survives than when the population remains constant. If therefore a heritable variation were to occur in the small nucleus of animals left at a min- imum of numbers, it would spread very quickly and automatically, so that a very large porportion of numbers of individuals would possess it when the species had regained its normal numbers.
    [Show full text]
  • Sperm Competition Enhances Functional Capacity of Mammalian
    Sperm competition enhances functional capacity SEE COMMENTARY of mammalian spermatozoa Montserrat Gomendio, Juan Martin-Coello, Cristina Crespo, Concepcio´ n Magan˜ a, and Eduardo R. S. Roldan* Reproductive Ecology and Biology Group, Department of Evolutionary Ecology, Museo Nacional de Ciencias Naturales (CSIC), Jose´Gutierrez Abascal 2, 28006 Madrid, Spain Edited by Ryuzo Yanagimachi, University of Hawaii, Honolulu, HI, and approved August 15, 2006 (received for review July 12, 2006) When females mate promiscuously, sperm from rival males com- Atlantic salmon (Salmo salar), sperm velocity is the key deter- pete within the female reproductive tract to fertilize ova. Sperm minant of sperm competition success (14). competition is a powerful selective force that has shaped sexual Among mammals, evidence of longer spermatozoa in polyan- behavior, sperm production, and sperm morphology. However, drous species suggests that improved sperm swimming velocity nothing is known about the influence of sperm competition on under sperm competition could be achieved by an increase in fertilization-related processes, because it has been assumed that sperm size (15). Sperm competition can also select for unique sperm competition only involves a race to reach the site of morphological traits that improve swimming velocity, as is the fertilization. We compared four closely related rodent species with case in the male common wood mouse (Apodemus sylvaticus), different levels of sperm competition to examine whether there which has spermatozoa with extremely long apical hooks by are differences in the proportion of spermatozoa that become which they intertwine, forming ‘‘trains’’ of spermatozoa (16). ready to interact with the ovum (‘‘capacitated’’) and in the pro- These sperm associations swim nearly twice as fast as nonasso- portion of spermatozoa that experience the acrosome reaction in ciated sperm toward the site of fertilization.
    [Show full text]
  • Polygyny, Mate-Guarding, and Posthumous Fertilization As Alternative Male Mating Strategies
    Polygyny, mate-guarding, and posthumous fertilization as alternative male mating strategies Kelly R. Zamudio*† and Barry Sinervo‡ *Museum of Vertebrate Zoology, 3101 Valley Life Sciences Building, University of California, Berkeley, CA 94720; and ‡Department of Ecology and Evolutionary Biology, A316 Earth and Marine Sciences Building, University of California, Santa Cruz, CA 95064 Edited by David B. Wake, University of California, Berkeley, CA, and approved October 27, 2000 (received for review December 14, 1999) Alternative male mating strategies within populations are thought Materials and Methods to be evolutionarily stable because different behaviors allow each Estimating Reproductive Success of Males. Paternity was estimated male type to successfully gain access to females. Although alter- by using nine microsatellite loci (Table 1) cloned from one native male strategies are widespread among animals, quantita- individual from the Los Ban˜os Grandes population, Merced tive evidence for the success of discrete male strategies is available County, California. Loci were cloned from genomic DNA by for only a few systems. We use nuclear microsatellites to estimate standard cloning methods (10). A genomic library was developed the paternity rates of three male lizard strategies previously by using size-selected fragments cloned into M13 vector and modeled as a rock-paper-scissors game. Each strategy has transformed into E. coli, followed by screening with a radiola- strengths that allow it to outcompete one morph, and weaknesses beled oligonucleotide with motif (CA)n. Plaques with inserts that leave it vulnerable to the strategy of another. Blue-throated containing microsatellites were sequenced for identification of males mate-guard their females and avoid cuckoldry by yellow- primer sites in the flanking regions.
    [Show full text]
  • Thermal Sensitivity of the Spiroplasma-Drosophila Hydei Protective Symbiosis: the Best of 2 Climes, the Worst of Climes
    bioRxiv preprint doi: https://doi.org/10.1101/2020.04.30.070938; this version posted May 2, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 1 Thermal sensitivity of the Spiroplasma-Drosophila hydei protective symbiosis: The best of 2 climes, the worst of climes. 3 4 Chris Corbin, Jordan E. Jones, Ewa Chrostek, Andy Fenton & Gregory D. D. Hurst* 5 6 Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Crown 7 Street, Liverpool L69 7ZB, UK 8 9 * For correspondence: [email protected] 10 11 Short title: Thermal sensitivity of a protective symbiosis 12 13 1 bioRxiv preprint doi: https://doi.org/10.1101/2020.04.30.070938; this version posted May 2, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 14 Abstract 15 16 The outcome of natural enemy attack in insects has commonly been found to be influenced 17 by the presence of protective symbionts in the host. The degree to which protection 18 functions in natural populations, however, will depend on the robustness of the phenotype 19 to variation in the abiotic environment. We studied the impact of a key environmental 20 parameter – temperature – on the efficacy of the protective effect of the symbiont 21 Spiroplasma on its host Drosophila hydei, against attack by the parasitoid wasp Leptopilina 22 heterotoma.
    [Show full text]
  • Mating Systems, Sperm Competition, and the Evolution of Sexual Dimorphism in Birds
    Evolution, 55(1), 2001, pp. 161±175 MATING SYSTEMS, SPERM COMPETITION, AND THE EVOLUTION OF SEXUAL DIMORPHISM IN BIRDS PETER O. DUNN,1,2 LINDA A. WHITTINGHAM,1 AND TREVOR E. PITCHER3 1Department of Biological Sciences, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201 2E-mail: [email protected] 3Department of Zoology, University of Toronto, Toronto Ontario, M5S 3G5, Canada Abstract. Comparative analyses suggest that a variety of factors in¯uence the evolution of sexual dimorphism in birds. We analyzed the relative importance of social mating system and sperm competition to sexual differences in plumage and body size (mass and tail and wing length) of more than 1000 species of birds from throughout the world. In these analyses we controlled for phylogeny and a variety of ecological and life-history variables. We used testis size (corrected for total body mass) as an index of sperm competition in each species, because testis size is correlated with levels of extrapair paternity and is available for a large number of species. In contrast to recent studies, we found strong and consistent effects of social mating system on most forms of dimorphism. Social mating system strongly in¯uenced dimorphism in plumage, body mass, and wing length and had some effect on dimorphism in tail length. Sexual dimorphism was relatively greater in species with polygynous or lekking than monogamous mating systems. This was true when we used both species and phylogenetically independent contrasts for analysis. Relative testis size was also related positively to dimorphism in tail and wing length, but in most analyses it was a poorer predictor of plumage dimorphism than social mating system.
    [Show full text]
  • Sperm Competition and Sex Change: a Comparative Analysis Across Fishes
    ORIGINAL ARTICLE doi:10.1111/j.1558-5646.2007.00050.x SPERM COMPETITION AND SEX CHANGE: A COMPARATIVE ANALYSIS ACROSS FISHES Philip P. Molloy,1,2,3 Nicholas B. Goodwin,1,4 Isabelle M. Cot ˆ e, ´ 3,5 John D. Reynolds,3,6 Matthew J. G. Gage1,7 1Centre for Ecology, Evolution and Conservation, School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, United Kingdom 2E-mail: [email protected] 3Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada 4E-mail: [email protected] 5E-mail: [email protected] 6E-mail: [email protected] 7E-mail: [email protected] Received October 2, 2006 Accepted October 26, 2006 Current theory to explain the adaptive significance of sex change over gonochorism predicts that female-first sex change could be adaptive when relative reproductive success increases at a faster rate with body size for males than for females. A faster rate of reproductive gain with body size can occur if larger males are more effective in controlling females and excluding competitors from fertilizations. The most simple consequence of this theoretical scenario, based on sexual allocation theory, is that natural breeding sex ratios are expected to be female biased in female-first sex changers, because average male fecundity will exceed that of females. A second prediction is that the intensity of sperm competition is expected to be lower in female-first sex-changing species because larger males should be able to more completely monopolize females and therefore reduce male–male competition during spawning.
    [Show full text]
  • View of the Invasion of Drosophila Suzukii in Gether with the 5′ UTR (Annotated in Green) Are Compared
    Yan et al. BMC Genetics 2020, 21(Suppl 2):146 https://doi.org/10.1186/s12863-020-00939-y RESEARCH Open Access Identification and characterization of four Drosophila suzukii cellularization genes and their promoters Ying Yan1,2*, Syeda A. Jaffri1, Jonas Schwirz2, Carl Stein1 and Marc F. Schetelig1,2* Abstract Background: The spotted-wing Drosophila (Drosophila suzukii) is a widespread invasive pest that causes severe economic damage to fruit crops. The early development of D. suzukii is similar to that of other Drosophilids, but the roles of individual genes must be confirmed experimentally. Cellularization genes coordinate the onset of cell division as soon as the invagination of membranes starts around the nuclei in the syncytial blastoderm. The promoters of these genes have been used in genetic pest-control systems to express transgenes that confer embryonic lethality. Such systems could be helpful in sterile insect technique applications to ensure that sterility (bi-sex embryonic lethality) or sexing (female-specific embryonic lethality) can be achieved during mass rearing. The activity of cellularization gene promoters during embryogenesis controls the timing and dose of the lethal gene product. Results: Here, we report the isolation of the D. suzukii cellularization genes nullo, serendipity-α, bottleneck and slow-as- molasses from a laboratory strain. Conserved motifs were identified by comparing the encoded proteins with orthologs from other Drosophilids. Expression profiling confirmed that all four are zygotic genes that are strongly expressed at the early blastoderm stage. The 5′ flanking regions from these cellularization genes were isolated, incorporated into piggyBac vectors and compared in vitro for the promoter activities.
    [Show full text]
  • On the Biology and Genetics of Scaptomyza Graminum Fallen (Diptera, Drosophilidae) Harrison D
    ON THE BIOLOGY AND GENETICS OF SCAPTOMYZA GRAMINUM FALLEN (DIPTERA, DROSOPHILIDAE) HARRISON D. STALKER1 Washington University, St. Louis MO. Received December 30, 1944 N THE spring of 1942 genetic work was begun on three Drosophilidae: I Scaptomyza graminum, S. adusta, and Chymomyza amoena. The purpose of this work was to make a comparison between the genetic chromosomes of Drosophila and those of some other Drosophilidae. Of the three species chosen, C. amoena soon proved itself unsatisfactory as a laboratory animal, partly because of the habit of the adults of constantly waving their wings as they moved about the culture bottle, with the result that they got stuck if the bottle or the food was at all moist. Both species of Scaptomyza could be cul- tured, but since it was difficult to secure large numbers of wild S. adusta, most of the work was done on S. graminum. Strains from the Rochester, N. Y., and St. Louis, Missouri, areas were studied, and large numbers of mutations were found, both in the progeny of the wild flies and as spontaneous occurrences in the laboratory. In 1943 all the laboratory stocks became infected with bacteria which made stock-keeping too difficult to warrant continuing the work. Since practically nothing is known about the genetics of any Drosophilidae other than Drosophila, it is felt that a description of the mutants discovered, as well as an account of some of the peculiarities of S. graminum, may have comparative value even though this account is of necessity somewhat frag- mentary. ACKNOWLEDGMENTS The author wishes to express his appreciation to DR.
    [Show full text]
  • INSIGHTS INTO ENDOSYMBIONT-MEDIATED DEFENSE of DROSOPHILA FLIES AGAINST PARASITOID WASPS a Dissertation by JIALEI XIE Submitted
    INSIGHTS INTO ENDOSYMBIONT-MEDIATED DEFENSE OF DROSOPHILA FLIES AGAINST PARASITOID WASPS A Dissertation by JIALEI XIE Submitted to the Office of Graduate and Professional Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Chair of Committee, Mariana Mateos Committee Members, Robert Wharton Adam Jones Cecilia Tamborindeguy Head of Department, Michael Masser December 2013 Major Subject: Wildlife and Fisheries Sciences Copyright 2013 Jialei Xie ABSTRACT Maternally-transmitted associations between endosymbiotic bacteria and insects are diverse and widespread in nature. To counter loss by imperfect vertical transmission, many heritable microbes have evolved compensational mechanisms, such as manipulating host reproduction and conferring fitness benefits to their hosts. Symbiont- mediated defense against natural enemies of hosts is increasingly recognized as an important mechanism by which endosymbionts enhance host fitness. Members of the genus Spiroplasma associated with distantly related Drosophila, are known to engage in either reproductive parasitism (i.e., male killing, MSRO strain) or defense against natural enemies (a parasitic wasp and a nematode). My previous studies indicate the Spiroplasma hy1 enhances survival of Drosophila hydei against the parasitoid wasp Leptopilina heterotoma, but whether this phenomenon can contribute to the long-term persistence of Spiroplasma is not clear. Here, I tracked Spiroplasma frequencies in fly lab populations repeatedly exposed to high or no wasp parasitism throughout ten generations. A dramatic increase of Spiroplasma prevalence was observed under high wasp pressure. In contrast, Spiroplasma prevalence in the absence of wasps did not change significantly over time; a pattern consistent with random drift. Thus, the defensive mechanism may contribute to the high prevalence of Spiroplasma in D.
    [Show full text]