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Errors in the Elimination of X Chromosomes in SCIARA OCELLARIS
1Departmento de Biologia, Universidade de São Paulo, C. P. 11461, São Paulo, 05421, Brazil.
Genetics
|March 1, 1980
Summary
The sepia mutation in Sciara ocellaris causes errors in X-chromosome elimination during embryogenesis, leading to abnormal flies. These errors involve the number or type of X chromosomes eliminated, with a maternal influence observed.
Area of Science:
- Genetics
- Developmental Biology
- Entomology
Background:
- X-chromosome elimination is crucial for sex determination and development in Sciara ocellaris.
- The X-linked recessive mutation, sepia, was previously hypothesized to disrupt this process.
Purpose of the Study:
- To confirm the role of the sepia mutation in X-chromosome elimination errors.
- To classify the specific types of errors induced by the sepia mutation.
- To elucidate the mechanism of sepia's influence on X-chromosome elimination.
Main Methods:
- Analysis of 85,244 individuals of Sciara ocellaris.
- Phenotypic classification of aberrant flies (mosaics, gynandromorphs, exceptional individuals).
- Genetic analysis to determine the origin and types of X-chromosome elimination errors.
Main Results:
- Confirmed that the sepia mutation induces errors in X-chromosome elimination.
- Identified three types of aberrant flies: mosaics (0.01%), gynandromorphs (0.42%), and phenotypically exceptional individuals (0.25%).
- Classified elimination errors into three categories: number, type, or both number and type of X chromosome.
Conclusions:
- The sepia mutation's effects stem from errors in X-chromosome elimination during male meiosis or early zygote cleavage.
- Errors can involve the number, type, or both of the X chromosome being eliminated.
- Sepia acts maternally and only in the heterozygous condition, without directly affecting the X chromosome.
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