ISSN:
0192-253X
Keywords:
Gene expression
;
mRNA localization
;
ascidian embryos
;
Life and Medical Sciences
;
Genetics
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
Notes:
We have cloned and characterized the temporal and spatial expression of ScCAl5, a cDNA clone encoding an actin gene in the ascidian Styela clava. The partial nucleotide and derived amino acid sequences of this single- copy gene suggest that it is a cytoskeletal actin. Northern analysis shows that ScCAl5 corresponds to a 1.8-kb mRNA that is transcribed during oogenesis, during embryonic development, and in the adult. In situ hybridization shows that maternal ScCA15 mRNA is distributed uniformly in the cyto- plasm of the oocyte and unfertilized egg. During the period of ooplasmic segregation following fertilization, however, ScCAl5 mRNA appears to be translocated into the ectoplasm, a specialized cytoplasmic region of the egg. During the early cleavages, the ectoplasmic transcripts are partitioned to ectodermal cells in the animal hemisphere, which are precursors of the epidermis and nervous system of the larva. Maternal ScCA15 mRNA is degraded just before gastrulation and replaced by zygotic transcripts which begin to accumulate between the neurula and mid-tailbud stages. Zygotic ScCAl5 mRNA accumulates primarily in the epidermal and neural cells, although lower levels of these transcripts may also be present in tail muscle cells. These results show that two mechanisms are used to concentrate ScCA15mRNA in the ectodermal cells during development: (1) localization and differential segregation of maternal transcripts and (2) specific expression of the ScCA15 gene. ScCAl5 mRNA is detected by in situ hybridization in the testes, ovaries, alimentary tract, and endostyle of adults. In the testes, ScCA15 mRNA is present in developing sperm, whereas in the ovary, these transcripts are present in the germinal epithelium and developing oocytes. In the alimentary tract, ScCAl5 mRNA is confined to the gastric epithelium of the esophagus, stomach, and intestine. Since the ScCA15 gene is expressed in embryonic and adult tissues that are undergoing rapid cell division, this actin is likely to function in some aspect of cell proliferation.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/dvg.1020110103
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