||Cytological, cytogenetic and biochemical studies were performed in the
following insect cell lines: Trichoplusia ni, TN-368; Drosophila
melanogaster, Schneider's 1; Aedes aegypti, ATC-10; Aedes aegypti, Mos.
20A; Aedes albopictus, ATC-15; Aedes albopictus, B1C4; Aedes
albopictus, C6/36; Aedes pseudoscutellaris, Mos. 61; Anopheles gambiae,
Mos. 55; Anopheles stephensi, Mos. 43; Culex quinquefasciatus. All insect
cell lines exhibited most of the characteristics associated with
transformed or neoplastic cells. Distinct "spontaneous" SCE frequencies
reflecting phylogenetic relationships were observed among three mosquito
species from two genera. The clastogens BrdU, EMS, MMS, ENU, and MNU were
found to induce SCEs and the differences in the number of exchanges
between insect and mammalian cells after compensating for genome sizes,
reflect either their differential susceptibility to the damage initially
inflicted to the DNA or to their capacities to perform DNA repair. By
comparing the rate of SCE increase in the insect and mammalian cells, it
was concluded that dissimilarities in number of SCEs between these two
groups of organisms is more likely due to differences in their repair
mechanism(s) in the case of BrdU and to the degree of initial DNA damage
in the case of the alkylating agents. An in vitro assay system designed
to test potential mutagens/carcinogens in fresh water is proposed using
mosquito cell lines of larval origin. The advantages of such a system are
discussed. Electrophoretic characterization of eleven insect cell lines
was performed utilizing 24 enzyme systems. Positive identification of all
cultures was possible. A positive correlation was found between number of
isozymes, enzyme activity and metabolic importance of the enzyme system.
The electrophoretic data revealed that Anopheles gambiae (Mos. 55) and the
Culex quinquefasciatus cell lines are in fact the same cell line.
Similarly, the Aedes pseudoscutellaris (Mos. 61) cell line was found to be
Aedes albopictus (C6/36). Biochemical differences were noticed between
cells growing in an insect medium and cultures maintained in a mammalian
medium. The superiority of slab polyacrylamide electrophoresis over starch
gel, agar gel and cellulose acetate electrophoresis in visualizing insect
isozymes is discussed.