Expression of cyclin E in endomitotic silk-gland cells from mulberry silkworm

Sudhakar, Baluchamy ; Karumathil Gopinathan, P. (2000) Expression of cyclin E in endomitotic silk-gland cells from mulberry silkworm Gene, 257 (1). pp. 77-85. ISSN 0378-1119

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The silk glands of mulberry silkworm Bombyx mori are endoreplicating tissues in which the genomic DNA undergoes multiple rounds of replication without mitosis and nuclear division. In the absence of normal mitotic division, the cell cycle essentially alternates between the G1 and S phases. Cyclin E is crucial for the G1/S transition in both mitotic and endoreplicating cycles. We have cloned and characterized cyclin E (cyclin box) from B. mori, which is nearly identical to the Drosophilacyclin E box except for an insertion of 21 amino acids. Two distinct cyclin E transcripts (1.7 and 2.1 kb) were detected in the silk-gland cells of B. mori and in the B. mori-derived embryonic cell line, BmN. Using anti Cyclin E antibodies two protein bands of 52 and 44 kDa were detected in silk glands and BmN cells at comparable levels. Both BmN- and the silk-gland cells showed the presence of the interacting kinase Cdk2. Transcripts of the mitotic cyclin, cyclin B, were barely detectable in the endoreplicating silk-gland cells and amounted to only 4-7% of that seen in the mitotically dividing BmN cells. The near absence of cyclin B transcripts and the abundant expression of cyclin E in the silk glands correlate well with the alternation of only G1 and S phases without the intervening mitosis in these cells.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Bombyx mori; BmN Cells; Cell-cycle Regulation; Cyclins; Endomitosis; RT-PCR
ID Code:88109
Deposited On:27 Mar 2012 08:26
Last Modified:27 Mar 2012 08:26

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