Chemical Communication in a Post-Genomic World (2003) / Chapter Skim
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8 A genomic perspective on nutrient provisioning by bacterial symbionts of insects
8 A genomic perspective on nutrient provisioning by bacterial symbionts of insects
Pages 31-36
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From page 31... ...
The best studied such association is that between aphids and Buchnera aphidicola, which produces essential amino acids that are rare in the phloem sap diet Genomic studies of Buchnera have provided a new means for inferring metabolic capabilities of the symbionts and their likely contributions to hosts. Despite evolutionary reduction of genome size, involving loss of most ancestral genes, Buchnera retains capabilities for biosynthesis of all essential amino acids.
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From page 32... ...
Experimental studies have provided some evidence that the nonessential amino acid glutamate is the major nitrogenous compound exported from the aphid and used by Buchnera for production of the essential, limiting amino acids (8-10~. Reading the Genome Sequences of Insect Symbionts: Old Tools for New Tasks Complete genome sequences are available for Buchnera of three distantly related aphid species fAcyrthosiphon pisum (11)
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From page 33... ...
Degradation of Symbiont Provisioning Through Gene Inactivation and Loss In contrast to the situation in A pisum in which all of the essential amino acids pathways are conserved, several lines of evidence indicate that individual pathways are sometimes inactivated or lost in particular Buchnera strains.
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From page 34... ...
2. Transcript abundances of genes in essential and nonessential amino acid biosynthetic pathways.
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From page 35... ...
This suggests that Buchnera has one or more negative feedback mechanisms governing amino acid production (45-47~. For example, in studies on Aphis fabae provided with radioactively labeled glut amic acid, a greater proportion of label was incorporated into the essential amino acid isoleucine on diets lacking isoleucine than on diets containing it (48~.
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From page 36... ...
25. Plague, G
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