Tregear, James W. (1989) The lectin gene family of Ricinus communis. PhD thesis, University of Warwick.

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Abstract

The aim of this project has been to isolate, characterise and investigate the expression patterns of the various members of the castor bean lectin gene family. Genomic Southern blotting experiments showed that the gene family contains approximately eight members, of which two appear to be ricin-like.

Castor bean genomic DNA was cloned into a bacteriophage lambda vector and the resulting recombinant clones screened with a ricin cDNA probe. Seventeen positive clones were isolated, amongst which at least five different groups could be recognised, on the basis of Southern blotting data. Four different lambda clones were selected for further analysis. One of the clones was found to contain a functional ricin gene with an identical restriction pattern to that of the ricin cDNA, but none of the clones appears to contain an authentic Riclnus communis agglutinin (RCA I) gene. DNA sequencing and RNAse protection data showed that three of the clones analysed contain lectin pseudogenes.

The expression pattern of the functional ricin gene in pCBG3Hl (lambda clone 10) was investigated at the transcriptional level using RNAse protection. The results obtained show that the mRNA transcribed from this gene accumulates during the late (post-testa) stages of seed development. The pCBG3Hl ricin gene appears to use multiple cap and poly(A) sites.

The developmental profile of lectin gene transcript levels observed in this study is similar to the patterns previously observed at the protein and translatable mRNA levels. This indicates a close correlation between the accumulation of the lectin proteins and the amounts of steady state transcripts. DNA sequencing enabled the identification of putative transcriptional regulatory elements in the promoter of the pCBG3Hl ricin gene, including an element resembling the RY repeat previously implicated in seed-specific gene expression.

Ultimately, it is hoped that studies of this type will make it possible for the network of regulatory processes governing the expression pattern of the castor bean lectin genes to be unravelled.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QK Botany
Library of Congress Subject Headings (LCSH):	Plant lectins, Castor oil plant -- Genetics, Plant gene isolation, Plant gene expression
Official Date:	August 1989
Dates:	Date Event August 1989 Submitted
Institution:	University of Warwick
Theses Department:	Department of Biological Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Roberts, L. M. (Lynne M.)
Sponsors:	Science and Engineering Research Council (Great Britain)
Format of File:	pdf
Extent:	xvii, 282 leaves : illustrations
Language:	eng

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