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Male determining factor on chromosome 3 in the mosquito, Culex tritaeniorhynchus

R H Baker, R K Sakai

    The Journal of Heredity
    |September 1, 1976
    PubMed

    Insights

    The sex allele M in Culex tritaeniorhynchus mosquitoes can be found in different linkage groups (I or III), impacting genetic mapping. This finding is crucial for understanding mosquito genetics and developing control strategies.

    Area of Science:

    • Genetics
    • Entomology
    • Molecular Biology

    Background:

    • The sex determination system in Culex tritaeniorhynchus, a significant vector of Japanese encephalitis virus, has been a subject of genetic investigation.
    • Previous studies suggested a single linkage group for the sex allele M, but variations across populations indicated potential complexities.

    Purpose of the Study:

    • To investigate the chromosomal location of the sex-determining allele M in different populations of Culex tritaeniorhynchus.
    • To determine if the sex allele M is consistently associated with a specific linkage group or if it exhibits variability.

    Main Methods:

    • Genetic crosses were performed using laboratory wild-type and mutant stocks of Culex tritaeniorhynchus.
    • Linkage analysis was conducted by observing the inheritance patterns of the sex allele M in relation to known marker genes on different linkage groups.
    • Recombination frequencies were analyzed to assess the genetic distance and association between the sex allele and other markers.

    Main Results:

    • The sex allele M was found to be unlinked to mutants in linkage group I in some stocks, but linked to mutants in linkage group III in others.
    • This indicates that the sex allele M can be associated with either linkage group I (designated M1) or linkage group III (designated M3).
    • Other markers within linkage groups remained linked, and recombination frequencies were unaffected by the presence or absence of the M allele, suggesting independent segregation of the M allele between linkage groups.

    Conclusions:

    • The sex-determining allele M in Culex tritaeniorhynchus is not fixed to a single linkage group and can exist in different chromosomal locations (linkage groups I or III).
    • This variability in the sex allele's linkage group has implications for genetic mapping and understanding the evolution of sex determination in this mosquito species.
    • The designation M1 and M3 clarifies the allelic forms based on their linkage group association, with a defined gene order (Lp-M3-Adh-bw-ae) when M3 is present in linkage group III.

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