ScienceAsia 24 (1998): 215-230 |doi: 10.2306/scienceasia1513-1874.1998.24.215

C-BANDING IN POLYTENE CHROMOSOMES OF SIX SIMULIUM SPECIES (DIPTERA: SIMULIIDAE) FROM DOI IN THANON NATIONAL PARK, NORTHERN THAILAND

CHALIOW KUVANGKADILOK^a, CHAINARONG BOONKEMTONG^b AND SUWANNEE PHAYUHASENA^a

ABSTRACT: The polytene chromosomes of Simulium (Nevermannia) caudisclerum, S. (N.) feuerborni, S. (Simulium) fenestratum, S. (S.) rufibasis, S. (S.) nakhonense and S. (Montisimulium) sp. G consistently showed C-banding of single thin to thick bands at centromere regions. telomeres and some interstitial sites. Despite the low amount of C-banded heterochromatin, these species showed intraspecific and interspecific differences in amount and distribution of heterochromatin. The larvae of S. (S.) rufibasis collected from different locations showed two different C-banding patterns. Pattern two had more C- banded materials in centromeres and interstitial regions than those in pattern one. In comparison with the C-banding pattern of S. (N.) caudisclerum which is presumed to be the most primitive species, the Simulium species in the present study were divided into three groups. Each group had cytological characteristic marked by differences in C-banding of centromeric heterochromatin. Therefore, the C-banding methods used are capable of demonstrating centromeric and interstitial heterochromatin whose satellite DNA has been increased and/or decreased during chromosome evolution. Moreover, C-banding technique successfully revealed that band 84B2 on the chromosome arm IIIL of S. (S.) nakhonense was a sex-linked heterochromatic band which is involved in differentiation of genetic X-chromosomal and Y-chromosomal segments.

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a Department of Biology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
b National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Rama VI Road, Bangkok, 10400, Thailand.

Received July 10, 1998