Neo-Sex Chromosomes in the Maculipennis Species Group ( Dichroplus : Acrididae, Melanoplinae): the Cases of D
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See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/303850240 Neo-sex Chromosomes in the Maculipennis Species Group ( Dichroplus : Acrididae, Melanoplinae): The Cases of D... Article in ZOOLOGICAL SCIENCE · June 2016 DOI: 10.2108/zs150165 CITATION READS 1 126 6 authors, including: Elio Rodrigo Castillo Yanina Mariottini National Scientific and Technical Research C… National Scientific and Technical Research C… 18 PUBLICATIONS 104 CITATIONS 24 PUBLICATIONS 89 CITATIONS SEE PROFILE SEE PROFILE Dardo A. Martí Claudio Bidau National Scientific and Technical Research C… Fundação Oswaldo Cruz 83 PUBLICATIONS 626 CITATIONS 123 PUBLICATIONS 1,207 CITATIONS SEE PROFILE SEE PROFILE Some of the authors of this publication are also working on these related projects: Analysis of the metabolic pathway of chlorogenic acid in the yerba mate (Ilex paraguariensis A. St.-Hil) genome: In silico study of prospecting on the genomic draft. View project Dynamics of Insect Behaviour View project All content following this page was uploaded by Alberto Taffarel on 10 June 2016. The user has requested enhancement of the downloaded file. ZOOLOGICAL SCIENCE 33: 303–310 (2016) © 2016 Zoological Society of Japan Neo-sex Chromosomes in the Maculipennis Species Group (Dichroplus: Acrididae, Melanoplinae): The Cases of D. maculipennis and D. vittigerum Elio R. D. Castillo1,2*, Alberto Taffarel1,2, Yanina Mariottini3, Valeria Fernández-Arhex4, Dardo A. Martí1, and Claudio J. Bidau5 1Laboratorio de Genética Evolutiva. Instituto de Biología Subtropical (IBS) CONICET- Universidad Nacional de Misiones. Félix de Azara 1552, Piso 6°. CP3300. Posadas, Misiones Argentina 2Comité Ejecutivo de Desarrollo e Innovación Tecnológica (CEDIT) Félix de Azara 1890, Piso 5°, Posadas, Misiones 3300, Argentina 3Centro de Estudios Parasitológicos y de Vectores (CEPAVE), CCT La Plata CONICET, Bulevar 120 e/60 y 64 S/N. 1900, La Plata, Argentina 4CONICET- INTA EEA Bariloche, Bote Modesta Victoria, 4450 (8400), Bariloche, Río Negro, Argentina 5Paraná y los Claveles, 3304, Garupá, Misiones, Argentina South American melanopline grasshoppers display a disproportionate number of derived karyo- types, including many cases of neo-sex chromosome systems. This is especially true of the genus Dichroplus and its Maculipennis species group. We analyzed the karyotype and neo-sex chromo- somes in mitosis and meiosis of Dichroplus maculipennis and D. vittigerum from Argentina using conventional and fluorescent cytogenetic protocols in order to elucidate the behavior and origin of these neo-XY systems in relation to the current phylogeny of this group. Our results showed that D. maculipennis (2n = 22♂/22♀; neoXY/neoXX) and D. vittigerum, whose karyotype is described here for the first time (2n = 18♂/18♀; neoXY/neoXX), show highly evolved neo-XY systems, although with significant differences between them. Furthermore, both species differ for two auto- somal fixed Robertsonian fusions present in D. vittigerum. Analysis of karyotypic character state optimization strongly suggests the independent origin and evolution of neo-sex systems within this species group. Key words: Dichroplus maculipennis, Dichroplus vittigerum, grasshopper, karyotype character state opti- mization, Melanoplinae, sex chromosomes karyotypically conservative, this is so only in diploid number INTRODUCTION and gross morphology of chromosomes (Hewitt, 1979). Fur- The origin, nature, genetics, and evolution of sex chro- thermore, many cases of karyotypic rearrangements that mosomes has long been a topic of great relevance in biol- modify the number and structure of chromosomes have ogy, and their meiotic properties have been under study been reported, and these frequently involve sex chromo- since the beginnings of cytogenetics (McClung, 1902; somes (White, 1973; Castillo et al., 2010a, b, 2014). Stevens, 1905; White, 1973; Bachtrog, 2006; Kaiser and Although the ancestral chromosomal sex-determining sys- Bachtrog, 2010; Bachtrog et al., 2011, 2014). In this respect, tem of the Acrididae (and all Orthopteroid orders; Blackman, some groups of organisms have proven to be excellent 1995) is known to be X0 male/XX female, the sex chromo- models for analyses of meiotic behavior. One such group is somes have undergone evolutionary structural changes in constituted by grasshoppers of the Acridoidea superfamily, many independent lineages, with the consequent production especially the Acrididae, due to their large size, low number of multiple sex chromosome systems that impose selective of chromosomes, and the clarity of their meiotic process pressures on the meiotic system required for their establish- (Hewitt, 1979; John, 1990; Bidau and Martí, 2010). Although ment in natural populations (Veltsos et al., 2008; Castillo et it has been traditionally thought that this family is rather al., 2010b; Bidau et al., 2011; Warchalowska-Sliwa´ et al., 2011, 2015). These pressures involve modifications that * Corresponding author. Tel. : +54-3764422186 (ex: 106); ensure proper meiotic segregation of sex chromosomes, E-mail: [email protected] which in turn undergo further molecular and structural mod- Supplemental material for this article is available online. ifications in a process called “Y-chromosome degeneration” doi:10.2108/zs150165 (Veltsos et al., 2008; Bidau et al., 2011). 304 E. R. D. Castillo et al. The South American Melanoplinae are an ideal acridoid CONICET-UNaM, Posadas and INTA EEA Bariloche, respectively. group for the study of the evolution of sex chromosomes Male meiotic preparations were performed by crushing testes folli- due to the disproportionately high number of cases in which cles in ferric haematoxylin. Female meiosis slide preparation fol- neo-sex chromosome systems have arisen in different lin- lowed the laboratory protocol cited in Martí and Bidau (1995). Mitotic eages (Mesa et al., 1982; Castillo et al., 2010a, b). One metaphase chromosomes from male and female gastric caeca were obtained following the procedure described by Castillo et al. (2011). tribe, the Dichroplini is especially interesting in this respect Silver staining of kinetochores and chromatid cores were per- because of its high chromosomal diversity in both autosomal formed according to the procedure of Rufas (1985). Briefly, air-dried and sex chromosome systems (Bidau and Martí, 2010; male meiotic preparations were incubated in 2 × SSC at 60°C for Castillo et al., 2010a, b, 2014). Within this tribe, the genus 10 min and stained with 50% AgNO3 in dH2O (pH adjusted to 3.5 Dichroplus Stål, which includes 24 species, has received with formic acid). Microscopic observation of silver stained prepara- special attention from the cytogenetic point of view (e.g., tions involved bright field and Nomarski interference optics. C- Bidau and Martí, 2001). banding was performed following the protocol of Sumner (1972), Dichroplus maculipennis is a widespread grasshopper with modifications. Chromomycine A3 (CMA3) and DAPI (4′, 6- (common name, tucura) belonging to the Maculipennis sub- diamidino-2-fenylindole) staining was performed following the proto- group of the homonymous species group (Cigliano and Otte, col described in Schweizer (1980). Autosomes were classified in three arbitrary size groups as is 2003). The subgroup also includes D. conspersus Bruner, standard practice for the description of acridoid karyotypes (Hewitt, 1900, D. robustulus (Stål, 1878), and D. vittatus Bruner, 1900 1979; John, 1983): L (large), M (medium-sized), and S (small) auto- (Cigliano and Otte, 2003; Eades et al., 2015). D. vittigerum somes. We used the terminology proposed by White (1940a, b) to (Blanchard, 1851) is a closely related species within the describe the chromosome arms of recently evolved neo-X and neo- Maculipennis group and the sole representative of the Y chromosomes: the autosomal arm of neo-X, which shares homol- Vittigerum subgroup (Eades et al., 2015). ogy with the neo-Y, is referred to as XR, while XL is the arm derived Dichroplus maculipennis has a wide but seemingly dis- from the original X chromosome fused to an autosome. This junct distribution in Chile, Argentina, Uruguay and southern nomenclature is strictly applicable to simple centric fusion-derived Brazil (see fig. 11 in Cigliano and Otte, 2003) which overlaps neo-XY systems. Measurements of chromosome lengths were per- widely with that of D. vittigerum (Eades et al., 2015). Both formed on gut caeca mitotic metaphases using MicroMeasure v. 3.3 (Reeves, 2001). species are important components of orthopteran diversity in the Argentine pampas and Argentine and Chilean Patagonia, Karyotype optimization and D. maculipennis is a major pest in several areas To re-evaluate the maculipennis species group chromosomal (Sánchez and de Wysiecki, 2008; Mariottini et al., 2011, evolution onto the Dichroplus phylogeny and test the hypothesis 2012, 2013). proposed by Colombo et al., 2005, we mapped the character “auto- Despite the considerable cytogenetic interest that the somes involved in neo-sex chromosome formation” using the soft- Dichroplini have caused, D. maculipennis and D. vittigerum ware TNT v1.1 (Goloboff et al., 2008).We consider autosomes from have been rather neglected from this angle especially con- the standard karyotypes (2n = 22 + X0/XX) involved in neo-sex sidering the wealth of such studies in other species of the chromosome origin as the karyotypic character to map onto the genus and the Maculipennis species group regarding popu-