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Title: Engrailed in the cockroach Periplaneta americana : cloning, expression and role in specifying synaptic connections.
Author: Marie, Bruno.
ISNI:       0000 0001 3618 9122
Awarding Body: University of Sussex
Current Institution: University of Sussex
Date of Award: 1999
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engrailed-related genes are homeobox containing transcription factors and have been cloned in numerous taxa. Their roles, in segmentation of the early embryo and in neural development, have been extensively described. Within the insects, some species have a single engrailed-related gene whilst others have two copies, raising the question of when and how often this duplication occurred. Here I report the cloning of two engrailed-related genes cren 1 and cren 2 in the cockroach Periplaneta americana. By comparing conserved domains and by carrying out a phylogenetic analysis, I conclude that these two genes are likely to be the product of a recent duplication in the cockroach lineage. Differentially spliced cren 2 isoforms that lack some regulatory domains have also been isolated. The roles these isoforms could play in regulating developmental processes are discussed. cren 1 and cren 2 are co-expressed during early embryogenesis; their segmental pattern of expression appears in an anteriorposterior progression. Double-stranded RNA interference was used to abolish the expression of Engrailed which is a putative positional determinant in an array of sensory neurones in the cockroach cereal system. This treatment radically alters the axonal arborization and choice of postsynaptic interneural partners of an identified Engrailed-positive sensory afferent. The neurone now resembles a neighbouring, Engrailed-negative cell, which is itself unaffected by the double-stranded RNA.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Genetics