Brain cell karyotype of the phlebotomine sand fly Lutzomyia shannoni (Dyar) (Diptera: Psychodidae)

Abstract

The brain cell karyotype of New World sand fly Lutzomyia shannoni was described. This species has four pairs of chromosomes, 2N=8, with one pair of heteromorphic chromosomes.Key words: Lutzomyia shannoni -brain cell karyotype -heteromorphic chromosome Brain cell karyotypes of four Old World and eight New World sand flies were described and compared by Kreutzer et al. (1987Kreutzer et al. ( , 1988. Among the eight New World sand flies species, the chromosome number varies from 2N=6 in Lutzomyia trapidoi to 2N=8 in the following species:. spinicrassa, and L. longipalpis. Heteromorphic chromosomes were not observed in these species (Kreutzer et al. 1988). On the other hand, Yin et al. (1999) studied patterns of G-banding in mitotic karyotypes in populations of L. longipalpis and found ancestral patterns in the populations. This paper provides preliminary data of cytogenetic studies of New World sand fly L. shannoni.Fourth instar larvae were obtained from a L. shannoni colony maintained since 1992 in the Entomology Laboratory of Instituto Nacional de Salud of Colombia, and originated from collections in the Lower Magdalena Valley. The techniques used for rearing the sand fly followed standard protocols in our laboratory. The larval diet was made with bovine manure and dog food; this mixture was stored for three months and stirred every two weeks. The females were fed on hamster blood (Ferro et al. 1998 Kreutzer et al. (1987). The larvae were placed in 0.1% colchicine for 4 h; then the heads of larvae were removed and placed in a 2% orcein stain for 10 min, 25 ml glacial acetic acid, and 25 ml 85% lactic acid. After staining, the heads were placed in a small drop of 50% acetic acid on a microscope slides. The contens of the head capsule were removed by pressure. Then the pieces of the head capsule were discarded and the small drop of stain was added. The cover slide was placed on the slide and the tissue was squashed in folded filter paper to absorb excess stain/acid. The slides were photographed with an Olympus microscope system at 1000X. Forty slides were examined, each containing from 3 to 12 karyotypes. The chromosomes were identified according to relative size and centromere position (Sessions 1996).As reported by Bello et al. (1997) the complement is eight chromosomes for L. shannoni (Fig. 1A). We observed several karyotypes with one pair, chromosome I, as heteromorphic (Fig. 1B) and probably an X and Y chromosome. Determination of the sex of the larvae was not possible before dissection. Chromosomes I, III and IV were metacentric, whereas chromosome II was submetacentric. This karyotype was similar to that of L. spinicrassa except that in this species the heteromorphic chromosome was not observed (Kreutzer et al. 1987).Only in Old World sand fly Phlebotomus perniciosus has been reported with a pair of chromosome heteromorphic (Kreutzer et al. 1987). The pair of chromosome heteromorphic observed in L. shannoni and P. perniciosus suggest the presence of sex chomosomes in other species of the genera Lutzomyia an...

Genetic variability among populations of Lutzomyia (Psathyromyia) shannoni (Dyar 1929) (Diptera: Psychodidae: Phlebotominae) in Colombia

“…According to Bello et al (1997), Lu. shannoni has four pairs of chromosomes with one pair heteromorphic (Jiménez et al 2001). During the colonization of Lu.…”

Identification of the sex chromosome system in a sand fly species, Lutzomyia longipalpis s.l

“…This is the case of most sand fly species studied so far, from both the Phlebotomus and Lutzomyia genera,( Kreutzer et al 1987 , 1988 ). The exceptions are Phlebotomus perniciosus and Lutzomyia shannoni , in which heteromorphic chromosomes were observed ( Kreutzer et al 1987 ; Jiménez et al 2001 ). In both cases, the authors considered the heteromorphic pair as an XY pair, however, neither work was able to determine the sex of the larvae before dissection ( Kreutzer et al 1987 ; Jiménez et al 2001 ), and hence these species may have as well a ZW system.…”

“…The exceptions are Phlebotomus perniciosus and Lutzomyia shannoni , in which heteromorphic chromosomes were observed ( Kreutzer et al 1987 ; Jiménez et al 2001 ). In both cases, the authors considered the heteromorphic pair as an XY pair, however, neither work was able to determine the sex of the larvae before dissection ( Kreutzer et al 1987 ; Jiménez et al 2001 ), and hence these species may have as well a ZW system. As mentioned, despite the fact that most Diptera have an XY system, ZW species occur ( Kaiser and Bachtrog 2010 ; Ashman et al 2014 ; Vicoso and Bachtrog 2015 ; Blackmon et al 2017 ).…”

Comparación cariotípica de cinco especies de Lutzomyia (diptera: psychodidae) de la serie townsendi grupo verrucarum en Colombia.

“…Los autores determinaron un número cromosómico diploide de 8, el cual fue, a su vez, confirmado por White y Killick-Kendrick (17). Posteriormente, con esta misma especie, que indudablemente ha sido la más estudiada, y con otras del Nuevo y Viejo Mundo, se han efectuado diversas investigaciones citogenéticas, tales como las desarrolladas por Bhat y Modi (18), Troiano (19), Kreutzer et al (20,21), Yin et al (22) y Jimenez et al (23). El número cromosómico diploide de las especies estudiadas oscila entre 6 y 10 y, además, como característica notable se ha observado que los cariotipos están constituidos, principalmente, por pares de cromosomas homomórficos, aunque el dimorfismo sexual en el par 1 ha sido registrado como excepción en una especie (19).…”