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Published on: October 31, 2016
Chromosome segregation and spindle structure in crane fly spermatocytes following Colcemid treatment
Abstract:
Chromosome segregation in primary spermatocytes of the crane fly Nephrotoma suturalis was studied after exposure to Colcemid at doses that did not completely inhibit spindle formation. Colcemid was added either to the medium in which larvae were cultured or to Tricine buffer in which isolated testes were incubated. Patterns of chromosome segregation were analyzed in fixed, Feulgen-stained smears of testes from Colcemid-treated larvae and in living cell preparations. Anomalies observed during the first meiotic division at higher than normal frequencies in Colcemid-treated spermatocytes included anaphase lagging of autosomes, chromosomal strands, tripolar and tetrapolar divisions, and unequal distribution of chromosomes to secondary cells. Following those doses of Colcemid that induced the above anomalies, the length of the birefringent spindle in primary spermatocytes was shorter than normal. This effect on spindle length also was apparent in Giemsa-stained preparations of fixed cells, in which the two centrosomes at the spindle poles were differentiated from the rest of the cytoplasm. The results indicate a correlation between the inhibition of spindle formation and the induction of anomalous patterns of chromosome segregation.
Insights
Colcemid exposure in crane fly spermatocytes disrupted chromosome segregation, leading to abnormal cell divisions. This study links impaired spindle formation to these segregation errors during meiosis.
Area of Science:
- Cell Biology
- Genetics
- Developmental Biology
Background:
- Chromosome segregation is crucial for accurate cell division in meiosis.
- Spindle formation is essential for proper chromosome segregation.
- Colcemid is a known inhibitor of microtubule polymerization, affecting spindle dynamics.
Purpose of the Study:
- To investigate the effects of sublethal Colcemid doses on chromosome segregation in Nephrotoma suturalis primary spermatocytes.
- To determine the relationship between spindle formation inhibition and chromosome segregation anomalies.
Main Methods:
- Crane fly larvae (Nephrotoma suturalis) were exposed to Colcemid during culture or incubation of isolated testes.
- Chromosome segregation patterns were analyzed in fixed, Feulgen-stained smears and living cell preparations.
- Spindle length and centrosome organization were examined in fixed, Giemsa-stained cells.
Main Results:
- Colcemid treatment induced anomalies in chromosome segregation, including anaphase lagging, chromosomal bridges, and multipolar divisions.
- Primary spermatocytes exhibited shorter spindles after Colcemid exposure.
- A correlation was observed between reduced spindle length and increased segregation errors.
Conclusions:
- Inhibition of spindle formation by Colcemid directly correlates with aberrant chromosome segregation patterns.
- These findings highlight the critical role of spindle integrity in ensuring accurate meiotic chromosome distribution.
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