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Development, genetic and cytogenetic analyses of genetic sexing strains of the Mexican fruit fly, Anastrepha ludens Loew (Diptera: Tephritidae).

Zepeda-Cisneros CS, Meza Hernández JS, García-Martínez V, Ibañez-Palacios J, Zacharopoulou A, Franz G - BMC Genet. (2014)

Bottom Line: To increase the efficiency of this technique, we have developed a genetic sexing strain (GSS) in which the sexing mechanism is based on a pupal colour dimorphism (brown-black) and is the result of a reciprocal translocation between the Y chromosome and the autosome bearing the black pupae (bp) locus.The translocation strain named Tapachula-7 showed minimal effect on survival and the best genetic stability of all ten strains.The present work is the first report of the construction of GSS of Anastrepha ludens, with potential use in a future Moscafrut operational program.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Anastrepha ludens is among the pests that have a major impact on México's economy because it attacks fruits as citrus and mangoes. The Mexican Federal government uses integrated pest management to control A. ludens through the Programa Nacional Moscas de la Fruta [National Fruit Fly Program, SAGARPA-SENASICA]. One of the main components of this program is the sterile insect technique (SIT), which is used to control field populations of the pest by releasing sterile flies.

Results: To increase the efficiency of this technique, we have developed a genetic sexing strain (GSS) in which the sexing mechanism is based on a pupal colour dimorphism (brown-black) and is the result of a reciprocal translocation between the Y chromosome and the autosome bearing the black pupae (bp) locus. Ten strains producing wild-type (brown pupae) males and mutant (black pupae) females were isolated. Subsequent evaluations for several generations were performed in most of these strains. The translocation strain named Tapachula-7 showed minimal effect on survival and the best genetic stability of all ten strains. Genetic and cytogenetic analyses were performed using mitotic and polytene chromosomes and we succeeded to characterize the chromosomal structure of this reciprocal translocation and map the autosome breakpoint, despite the fact that the Y chromosome is not visible in polytene nuclei following standard staining.

Conclusions: We show that mitotic and polytene chromosomes can be used in cytogenetic analyses towards the development of genetic control methods in this pest species. The present work is the first report of the construction of GSS of Anastrepha ludens, with potential use in a future Moscafrut operational program.

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Schematic representation of alternate and adjacent-1 segregation in males with a Y-autosome translocation
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Figure 5: Schematic representation of alternate and adjacent-1 segregation in males with a Y-autosome translocation

Mentions: In the evaluation of a GSS, it is important to consider the productivity and the product quality, both of which are tightly linked to the structure of the translocation. The segregation behaviour of the translocation during male meiosis will determine the number of genetically balanced or unbalanced individuals in the next generation. During male meiosis simple Y-autosome translocations can segregate in two different ways if they follow the rule that homologous centromeres segregate: alternate or adjacent-1 segregation. In the former the two translocation chromosomes stay together and segregate from the X chromosome. In the latter the A-Y chromosome segregates together with the X chromosome while the Y-A chromosome segregates with the non-translocated autosomal homologue. Figure 5 shows, that after fertilization only alternate segregation results in genetically balanced offspring while adjacent-1 segregation results in offspring where the chromosomal segment between the translocation breakpoint and the tip of respective chromosome arm is either present in three copies or segregation only in a haploid condition. At least in the medfly such long deletions lead to early lethality which is manifested as reduced egg hatch. The triplication type adjacent-1 offspring can survive, depending on the length of the triplication, even to the adult stage, although at severely reduced numbers [12]. Only if the autosome breakpoint is very close to the tip, i.e. the triplication is very short, such flies mate and produce offspring (Franz, personal communication). Both forms of segregation are completely legitimate and that explains why they occur at equal frequency in most translocation strains, at least in medfly. Consequently, only half of the sperm produced by males carrying a Y-autosome translocation lead to viable, genetically balanced offspring, i.e. such males are 50% sterile. In a third form of segregation, adjacent-2, homologous centromeres do not segregate, i.e. this is a form of non-disjunction and therefore significantly less likely to occur.


Development, genetic and cytogenetic analyses of genetic sexing strains of the Mexican fruit fly, Anastrepha ludens Loew (Diptera: Tephritidae).

Zepeda-Cisneros CS, Meza Hernández JS, García-Martínez V, Ibañez-Palacios J, Zacharopoulou A, Franz G - BMC Genet. (2014)

Schematic representation of alternate and adjacent-1 segregation in males with a Y-autosome translocation
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4255765&req=5

Figure 5: Schematic representation of alternate and adjacent-1 segregation in males with a Y-autosome translocation
Mentions: In the evaluation of a GSS, it is important to consider the productivity and the product quality, both of which are tightly linked to the structure of the translocation. The segregation behaviour of the translocation during male meiosis will determine the number of genetically balanced or unbalanced individuals in the next generation. During male meiosis simple Y-autosome translocations can segregate in two different ways if they follow the rule that homologous centromeres segregate: alternate or adjacent-1 segregation. In the former the two translocation chromosomes stay together and segregate from the X chromosome. In the latter the A-Y chromosome segregates together with the X chromosome while the Y-A chromosome segregates with the non-translocated autosomal homologue. Figure 5 shows, that after fertilization only alternate segregation results in genetically balanced offspring while adjacent-1 segregation results in offspring where the chromosomal segment between the translocation breakpoint and the tip of respective chromosome arm is either present in three copies or segregation only in a haploid condition. At least in the medfly such long deletions lead to early lethality which is manifested as reduced egg hatch. The triplication type adjacent-1 offspring can survive, depending on the length of the triplication, even to the adult stage, although at severely reduced numbers [12]. Only if the autosome breakpoint is very close to the tip, i.e. the triplication is very short, such flies mate and produce offspring (Franz, personal communication). Both forms of segregation are completely legitimate and that explains why they occur at equal frequency in most translocation strains, at least in medfly. Consequently, only half of the sperm produced by males carrying a Y-autosome translocation lead to viable, genetically balanced offspring, i.e. such males are 50% sterile. In a third form of segregation, adjacent-2, homologous centromeres do not segregate, i.e. this is a form of non-disjunction and therefore significantly less likely to occur.

Bottom Line: To increase the efficiency of this technique, we have developed a genetic sexing strain (GSS) in which the sexing mechanism is based on a pupal colour dimorphism (brown-black) and is the result of a reciprocal translocation between the Y chromosome and the autosome bearing the black pupae (bp) locus.The translocation strain named Tapachula-7 showed minimal effect on survival and the best genetic stability of all ten strains.The present work is the first report of the construction of GSS of Anastrepha ludens, with potential use in a future Moscafrut operational program.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Anastrepha ludens is among the pests that have a major impact on México's economy because it attacks fruits as citrus and mangoes. The Mexican Federal government uses integrated pest management to control A. ludens through the Programa Nacional Moscas de la Fruta [National Fruit Fly Program, SAGARPA-SENASICA]. One of the main components of this program is the sterile insect technique (SIT), which is used to control field populations of the pest by releasing sterile flies.

Results: To increase the efficiency of this technique, we have developed a genetic sexing strain (GSS) in which the sexing mechanism is based on a pupal colour dimorphism (brown-black) and is the result of a reciprocal translocation between the Y chromosome and the autosome bearing the black pupae (bp) locus. Ten strains producing wild-type (brown pupae) males and mutant (black pupae) females were isolated. Subsequent evaluations for several generations were performed in most of these strains. The translocation strain named Tapachula-7 showed minimal effect on survival and the best genetic stability of all ten strains. Genetic and cytogenetic analyses were performed using mitotic and polytene chromosomes and we succeeded to characterize the chromosomal structure of this reciprocal translocation and map the autosome breakpoint, despite the fact that the Y chromosome is not visible in polytene nuclei following standard staining.

Conclusions: We show that mitotic and polytene chromosomes can be used in cytogenetic analyses towards the development of genetic control methods in this pest species. The present work is the first report of the construction of GSS of Anastrepha ludens, with potential use in a future Moscafrut operational program.

Show MeSH
Related in: MedlinePlus