Review Article |
Corresponding author: María Cecilia Giardini ( giardini.maria@inta.gob.ar ) Academic editor: Teresa Vera
© 2015 María Cecilia Giardini, Fabián H. Milla, Silvia Lanzavecchia, Mariela Nieves, Jorge L. Cladera.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Giardini MC, Milla FH, Lanzavecchia S, Nieves M, Cladera JL (2015) Sex chromosomes in mitotic and polytene tissues of Anastrepha fraterculus (Diptera, Tephritidae) from Argentina: a review. In: De Meyer M, Clarke AR, Vera MT, Hendrichs J (Eds) Resolution of Cryptic Species Complexes of Tephritid Pests to Enhance SIT Application and Facilitate International Trade. ZooKeys 540: 83-94. https://doi.org/10.3897/zookeys.540.6058
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Cytogenetics, which is considered a fundamental tool to understand basic genetic and genomic issues of species, has greatly contributed to the description of polymorphisms both at inter- and intra-specific level. In fact, cytogenetics was one of the first approaches used to propose Anastrepha fraterculus (Diptera: Tephritidae) as a complex of cryptic species. Different morphological variants of sex chromosomes have been reported among Argentinean populations of A. fraterculus. However, since this high structural variability in sex chromosomes does not pose a reproductive barrier, their role in speciation is yet to be unveiled. This review provides an update on general aspects of cytogenetics in Argentinean A. fraterculus populations, focused on the prevalence of X-Y arrangements.
Cytogenetics, karyotype variants, South American fruit fly, heterochromatin, centromeres, ribosomal genes
Cytogenetic studies have provided significant information about intra- and inter-species genetic variation (
Reproductive incompatibilities between A. sp.1 aff. fraterculus and A. sp. 2 aff. fraterculus living in sympatry were first described by
Polytene chromosome analysis and the availability of polytene maps of different genera of the family Tephritidae, as Ceratitis (
Karyological studies performed in wild populations of A. fraterculus from Argentina have shown structural variability in the sex chromosomes.
In an experiment under field cage conditions
After a revision of A. fraterculus´ chromosomes studies we concluded that the most frequent karyotype found in Argentina consists in five pairs of acrocentric autosomes, a submetacentric X chromosome (named X1,
After C-band staining (Figure
Anastrepha fraterculus has also been cytogenetically characterized by means of fluorescence
As a first attempt to study histone modifications in A. fraterculus chromosomes, we performed immunodetection assays with specific antibodies in mitotic preparations of Argentinean A. fraterculus to analyze the presence of histone H3 phosphorylated at positions 10 or 28 (preliminary reported in
The existence of polytene chromosomes in the salivary glands of A. fraterculus was first reported by
We have also performed a simultaneous analysis of mitotic and polytene nuclei of Argentinean A. fraterculus, and observed that neither the number of polytene chromosomes nor their banding patterns differentiate males from females (
18S rDNA FISH analysis in polytene and mitotic tissues. Polytene and mitotic chromosome preparations obtained from third instar larvae of male (A) and female (B) of A. fraterculus. In each case: 1 Polytene chromosomes DAPI stain 2 Polytene chromosomes 18S rDNA hybridization signa (FISH) 3 Polytene chromosomes merged image (DAPI/FISH) 4 Mitotic chromosomes DAPI stain 5 Mitotic chromosomes 18S rDNA hybridization signal (FISH) 6 Mitotic chromosomes merged image (DAPI/FISH).
This review summarizes the cytogenetic information available from Argentinean A. fraterculus, focused on sex chromosome variation. Figure
All the results described here represent valuable information to be further used in the identification of genetic entities in the A. fraterculus complex of cryptic species. Deeper characterization of the structural variation of the sex chromosomes and polytene chromosome needs to be addressed to have a complete genetic picture of this species, which represents one of the most destructive fruit flies of economic importance in Argentina and the South American region. A detailed taxonomic revision of A. fraterculus and the accurate elucidation of the complexity displayed by this species in South America are of uttermost importance to develop environment-friendly autocidal control methods as is the Sterile Insect Technique (SIT), ensuring its specificity and effectiveness.
The authors gratefully acknowledge the two anonymous reviewers for their comments and suggestions to improve the manuscript. This work was partially supported by the National Institute of Agriculture Technology (INTA) through the project AEBIO-242411 (module pests) to SBL, by Consejo Nacional de Investigaciones Científicas y Técnicas PIP0572 to MN, MAEC-AECID Fellowship for Researchers and Postgraduate Studies to MCG and by the Agencia Nacional de Promoción Científica y Tecnológica de Argentina (ANPCyT) through Fondo Nacional de Ciencia y Tecnología (FONCyT) (grants PICT 2012 0704) to JLC. We wish to thank Dr. Clara Goday (Departamento de Proliferación Celular y Desarrollo, Centro de Investigaciones Biológicas, CSIC, Madrid, España) who hosted a part of the research in her laboratory and for her valuable help in cytogenetic techniques. We are also grateful to Dr. Leonela Carabajal Paladino (Laboratory of Molecular Cytogenetics, Biology Centre ASCR, Ceske Budejovice, Czech Republic) and Dr. Alejandra Scannapieco (Laboratorio de Insectos de Importancia Económica, IGEAF, INTA) for their valuable contribution to improve this manuscript.