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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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a) The short translocation fragment representing the Y-2 chromosome of mitotic metaphases or Y-III of polytene chromosomes. b) Reference map of chromosome III showing the region involved in translocation; arrow in the map shows the position of the breakpoint. Bar = 10µm
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Figure 4: a) The short translocation fragment representing the Y-2 chromosome of mitotic metaphases or Y-III of polytene chromosomes. b) Reference map of chromosome III showing the region involved in translocation; arrow in the map shows the position of the breakpoint. Bar = 10µm

Mentions: Polytene chromosomes. Polytene chromosomes were analyzed in male larvae from the GSS T(Y:bp+)-7. The analysis was focused only on males where the reciprocal translocation can be observed. Although the Y chromosome cannot be identified in polytene nuclei using standard staining, we succeeded to identify the autosome involved in the translocation and map the autosomal breakpoint. Anastrepha ludens shows a characteristic ectopic pairing between the telomeres of the autosomes [21], a phenomenon that also was observed in other Tephritidae species as Bactrocera oleae [22] and B. cucurbitae [23]. One of the most frequent ectopic pairing has been observed between the polytene elements III and V (Figure 3f). Polytene chromosomes from the strain T(Y:bp+)-7 are shown in Figure 3a-e. The ectopic pairing of the two telomeres, chromosome III and V are shown, but interestingly only one homolog of the polytene element III is involved in this. In all cases, a part of a single chromosome III is connected with its telomere to the telomere of chromosome V. This region should represent the distal part of the chromosome element involved in the Y-autosome translocation. In this ectopic pairing either the telomere of the intact chromosome III is taking part (Figure 3a); or the fragment of the chromosome that is connected to the Y chromosome (Y-A) (Figure 3b-e) is pairing. Based on these observations as well as on the mitotic karyotype of this strain, we can conclude that polytene chromosome III corresponds to the longest chromosome of the mitotic karyotype, i.e. chromosome 2. Taking into account both the mitotic karyotype and polytene chromosomes analyses of this GSS, we can propose the structure of the T(Y:bp+)-7. According to the chromosome maps of A. ludens [21] the chromosome III has a breakpoint at the beginning of the region 25 (Figure 4). This breakpoint produces two autosomal fragments of different size: The short fragment includes the distal part of the chromosome from the telomere to 25 chromosomal region (24.67 µm) while the second fragment consisting of the rest of the chromosome element III. The short fragment is joined to that part of the Y chromosome that carries the centromere Y-2 (Figure 2d). The second autosomal fragment, with the autosomal centromere, is linked to remaining region of the Y chromosome resulting in the 2-Ychromosome (Figure 2d) that is slightly shorter than the wild-type chromosome element III. Each of these new chromosomes, 2-Y and Y-2 has its centromere and telomere sufficient for their stability.


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)

a) The short translocation fragment representing the Y-2 chromosome of mitotic metaphases or Y-III of polytene chromosomes. b) Reference map of chromosome III showing the region involved in translocation; arrow in the map shows the position of the breakpoint. Bar = 10µm
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: a) The short translocation fragment representing the Y-2 chromosome of mitotic metaphases or Y-III of polytene chromosomes. b) Reference map of chromosome III showing the region involved in translocation; arrow in the map shows the position of the breakpoint. Bar = 10µm
Mentions: Polytene chromosomes. Polytene chromosomes were analyzed in male larvae from the GSS T(Y:bp+)-7. The analysis was focused only on males where the reciprocal translocation can be observed. Although the Y chromosome cannot be identified in polytene nuclei using standard staining, we succeeded to identify the autosome involved in the translocation and map the autosomal breakpoint. Anastrepha ludens shows a characteristic ectopic pairing between the telomeres of the autosomes [21], a phenomenon that also was observed in other Tephritidae species as Bactrocera oleae [22] and B. cucurbitae [23]. One of the most frequent ectopic pairing has been observed between the polytene elements III and V (Figure 3f). Polytene chromosomes from the strain T(Y:bp+)-7 are shown in Figure 3a-e. The ectopic pairing of the two telomeres, chromosome III and V are shown, but interestingly only one homolog of the polytene element III is involved in this. In all cases, a part of a single chromosome III is connected with its telomere to the telomere of chromosome V. This region should represent the distal part of the chromosome element involved in the Y-autosome translocation. In this ectopic pairing either the telomere of the intact chromosome III is taking part (Figure 3a); or the fragment of the chromosome that is connected to the Y chromosome (Y-A) (Figure 3b-e) is pairing. Based on these observations as well as on the mitotic karyotype of this strain, we can conclude that polytene chromosome III corresponds to the longest chromosome of the mitotic karyotype, i.e. chromosome 2. Taking into account both the mitotic karyotype and polytene chromosomes analyses of this GSS, we can propose the structure of the T(Y:bp+)-7. According to the chromosome maps of A. ludens [21] the chromosome III has a breakpoint at the beginning of the region 25 (Figure 4). This breakpoint produces two autosomal fragments of different size: The short fragment includes the distal part of the chromosome from the telomere to 25 chromosomal region (24.67 µm) while the second fragment consisting of the rest of the chromosome element III. The short fragment is joined to that part of the Y chromosome that carries the centromere Y-2 (Figure 2d). The second autosomal fragment, with the autosomal centromere, is linked to remaining region of the Y chromosome resulting in the 2-Ychromosome (Figure 2d) that is slightly shorter than the wild-type chromosome element III. Each of these new chromosomes, 2-Y and Y-2 has its centromere and telomere sufficient for their stability.

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