Why Study Sciara?

The unique biological features of Sciara coprophila led it to be on the short list as a premier model organism in the 1930s at a Cold Spring Harbor meeting when Sciara competed with Drosophila melanogaster that was chosen and in the 1970s when Sydney Brenner compared the merits of Sciara with the worm Caenorhabditis elegans that was chosen. Thus, on these two occasions the scientific community has considered Sciara as an extremely valuable model organism due to its unique biology.

The lower dipteran fly Sciara has many unique biological properties:

• Chromosome imprinting
• Sex determination; evolution towards parthenogenesis
• Monopolar spindle in male meiosis I; centrosome structure/function
• Non-disjunction of the X chromosome in meiosis II
• Chromosome elimination in early embryogenesis
• Germ line limited (L) chromosomes
• DNA amplification in late larval salivary gland polytene chromosomes
• High resistance to radiation

Elucidation of these phenomena (described in more detail in the section on unique biological features) will help in our understanding of basic mechanisms in genetics, cell and developmental biology.

In addition, several aspects of Sciara render it favorable as experimental material:

• Long-term storage of larvae for many months at 4⁰C with virtually no care
• No need to collect virgins for mating as mothers have only sons or daughters
• Ease in collecting time-synchronized embryos in large batches
• No need to remove the thin chorion prior to embryo injections
• Salivary glands extend the full length of the larval body, providing much material
• Gigantic polytene chromosomes (more endoduplication cycles than Drosophila)
• Polytene chromosomes lack a chromocenter so are easier to spread