Fluorescence in situ hybridization landmarks for chromosomes of Culicoidesvariipennis (Diptera : Ceratopogonidae)

Because the three chromosomes of Culicoides variipennis (Coquillett) are mo rphologically indistinguishable, physical landmarks were needed so that the chromosomes can be identified uniquely and oriented unambiguously before i nitiating the construction of a physical map based on FISH (fluorescence in situ hybridization). When repetitive sequence clones p1887 and K8.1a8 were labeled with digoxigenin and probe K8a.2G2 was labeled with biotin-11-dUTP and digoxigenin, the 3 chromosomes could be differentiated unambiguously w hen visualized with specific band-pass filters. This provided the basis for C. variipennis FISH landmark probes that enabled the identification and or ientation of all 3 pairs of chromosomes. Using this multicolor FISH labelin g strategy, probes that provide unique landmarks for the C, variipennis FIS H physical map have been found and may be used in all FISH reactions where an unknown probe is placed to metaphase chromosomes of C. variipennis. A ph ysical map of the C. variipennis genome will provide the foundation for map -based positional cloning of the gene(s) that control vector competence for the bluetongue viruses.