Differential expression of tyrosinated tubulin in Spisula solidissima polar bodies.
The C-terminus of alpha-tubulin can be reversibly modified by a specific tyrosine ligase to yield an isoform known as Tyr-tubulin. Tyr-tubulin is typically found in more dynamic microtubule arrays such as the mitotic spindle, as opposed to stable structures like centrioles and flagella. In developing systems, it is expressed in relatively undifferentiated, proliferative cell types but is replaced by detyrosinated (Glu-) tubulin during differentiation. We found Tyr-tubulin highly enriched in a single polar body of Spisula solidissima embryos. Quantitation of DNA content by Hoechst staining indicates that polar body 1 (with twice the DNA content of polar body 2) is the Tyr-tubulin-positive cell. Other than the apoptosis marker caspase, this is, to our knowledge, the first distinguishing marker antigen for polar bodies, particularly for one polar body vs. another. This localization of Tyr-tubulin is unlikely to be a byproduct of the meiotic process itself, because it arises after ejection of both polar bodies is complete. Although polar bodies are typically thought of as a terminally differentiated vestige of meiosis, the localization of this more dynamic tubulin isoform suggests an active role in early development.
Alliegro
Mark C
MC
Marine Biological Laboratory, Woods Hole, Massachusetts, and Department of Cell Biology, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA. mallie@lshuhsc.edu
Alliegro
Mary Anne
MA
D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002454:Cell Differentiation; D004247:DNA / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D008540:Meiosis; D008870:Microtubules / Q000378:metabolism; D008974:Mollusca; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D008941:Spindle Apparatus; D013997:Time Factors; D014404:Tubulin / Q000096:biosynthesis* / Q000737:chemistry* / Q000378:metabolism; D014443:Tyrosine / Q000737:chemistry; D015053:Zygote / Q000378:metabolism
D020033:Protein Isoforms; D014404:Tubulin; C039520:tyrosine-tubulin; D014443:Tyrosine; D004247:DNA