Sex chromatin body as a marker of radiation-induced sex chromosome aberrations in the potato tuber moth, Phthorimaea operculella (Lepidoptera: Gelechiidae)

Abstract

Genetic sexing technique based on the construction of a balanced lethal strain (BLS) has been proposed for Phthorimaea operculella (Zeller). The isolation of female with T(W;Z) translocation is a fundamental step to develop such a strain. Gamma irradiation was used to induce the requested translocations. The availability of sex-linked morphological marker is required to facilitate the detection of such mutations. Since a visible sex-linked marker has not been found in P. operculella, the main objective of our study was therefore to determine the possibility of using sex heterochromatin body as a marker to identify the required translocated females. The appearance of sex heterochromatin body and the analysis of sex chromosomes in F 1 females of irradiated P. operculella females were investigated. The percentage of abnormality in sex heterochromatin body in highly polyploid Malpighian tubule nuclei was positively correlated with the applied dose. Based on the appearance of this body, three mutant lines were isolated: elongated, small and fragmented lines. W chromosome was easily distinguished from Z chromosome when the analysis of pachytene sex chromosome bivalents of P. operculella females was carried out. The aberrations involved in W chromosome directly influenced the appearance of sex heterochromatin body in highly polyploid somatic cells of the isolated mutant lines. The results showed that sex heterochromatin could be used as sex determination and cytogenetic marker in P. operculella.

The Effect of X-Rays on Cytological Traits ofTuta absoluta(Lepidoptera: Gelechiidae)

“…The detailed karyotype analysis of non-irradiated T. absoluta larvae allowed us to identify radiation-induced chromosomal aberrations in F 1 individuals, as was previously done in other Lepidoptera species (Saifutdinov 1989;Al-Taweel et al 1990;Carpenter 1991;Carpenter et al 1997;Makee & Tafesh 2006). The presence of sex chromatin in this species is a useful parameter for monitoring the effect of radiation, as its morphology and quantity can be used as a marker to identify sex chromosome aberrations (Makee & Tafesh 2006).…”

“…Lepidopteran females display a heterochromatic body in the interphase nuclei (reviewed in Traut & Marec 1996) also called sex chromatin body, which is derived from the W chromosome (Traut et al 2007). The chromosomal aberrations induced by radiation can be seen in changes in the number of chromosomes, and/or aberrant chromosome morphology and quantity of sex chromatin bodies Carpenter et al 2005;Makee & Tafesh 2006).…”

Sex Chromosomes and Sex Determination in Lepidoptera

“…From older larvae, Malpighian tubules provide an excellent material to determine presence or absence of W chromatin easily. This has been used as a marker for radiation-induced sex chromosome aberrations [Rathjens, 1974;Makee and Tafesh, 2006], in studies on intersexes of Lymantria dispar [Mosbacher, 1973] and especially the influence of Wolbachia on sex determination and sex-specific lethality of their hosts [Hiroki et al, 2002;Kageyama and Traut, 2004].…”

Mapping of pachytene bivalents of female codling moth Cydia pomonella (Linnaeus) (Lep., Tortricidae)

“…In orcein‐stained female preparations, the sex chromosome bivalent (WZ) was easily distinguished because of the deeply stained heterochromatin of the W chromosome. Similarly, a heteromorphic WZ bivalent is present in species such as E. kuehniella and Phthorimaea operculella Zeller (Weith and Traut 1980; Makee and Tafesh 2006). However, in P. gossypiella females no heteromorphic bivalent was found (Bartlett and Del Fosses 1991).…”