The significance of complex chromosomal rearrangements presents a diagnostic dilemma. In the past, the use of G-banding coupled with fluorescence in situ hybridization (FISH) has been the standard approach. The recent development of spectral karyotyping (SKY) and multicolor FISH (M-FISH) has resulted in an increased accuracy of identification of marker or other complex chromosomal rearrangements. However, owing to the additional cost and time associated with SKY or M-FISH, and the restricted availability of such imaging facilities in many centers, it is not feasible to perform these procedures routinely on every sample. In addition, the identification of an aberration by SKY or M-FISH will often require confirmation by FISH. A practical approach is needed to take advantage of the complementary strengths of each method. In our center we utilize an algorithm that dictates the use of routine G-banding for the initial preliminary evaluation of a patient, followed by SKY characterization if marker chromosomes or complex translocations are detected by the G-banding analysis. According to this algorithm, FISH is used to verify the results once the origin of the abnormal chromosome has been determined by SKY. To demonstrate the effectiveness of this algorithm, we have analyzed both amniocyte and lymphocyte slides, using a combination of G-banding, SKY, and FISH. Our results confirm that an algorithm which selectively uses SKY or M-FISH will provide an efficient and improved method for pre- and post-natal chromosomal analysis.

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A study relating to seasonal prevalence and host visitation of Mansonia mosquitoes in Trivandrum city was carried out between August 1984 and July 1985. The area chosen was the one which is a perennial breeding source for Mansonia mosquitoes. Only Mansonia uniformis and Mansonia annulifera were prevalent in this area of which the former was found to be the predominant species. Decrease in the number of Mansonia annulifera from the survey conducted during the previous year may be due to the disappearance of Pistia stratiotes and its replacement by Salvinia auriculata. Rainfall and temperature are the two important environmental factors which influence the number of Mansonia mosquitoes visiting the host. The maximum number of adults of Mansonia uniformis was collected during February to June 1985. No swarm of Mansonia uniformis was encountered during the present study, however, males were found to wait and mate with the resting as well as blood fed females in the vicinity of the host. Both sexes of Mansonia mosquitoes were parasitized by Arrenurus and limnesiid species of water mites. Maximum parasitization was seen during July 1985.

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