Use of two transcription starts in the G6PD gene of the bark beetle Ips typographus

Abstract

The enzyme glucose-6-phosphate dehydrogenase (G6PD) of the bark beetle Ips typographus is derived from a gene that includes eight exons and spans over 7100 nucleotides (nt). By means of two transcription starts, the gene generates two mRNA isoforms that are present in similar amounts in the larvae, pupae and adults. The A isoform includes exon IA of 115 nt, which is followed by intron 1a extending to position 3457 of the gene. The B mRNA isoform begins with exon IB (100 nt) that occupies positions 3291-3390 within the 1a intron. Exons II to VII are included in both mRNA isoforms. The gene contains 31.6% (36.5% in the translated region) of the GC nucleotides. Two transcription starts and the exon/intron organization distinguish bark beetle G6PD from the homologous genes known in other insects. Two enzyme variants were detected in the protein extracts of individual bark beetles but their relationship to the A and B mRNA isoforms is uncertain.

Multiple transcripts encode glucose 6-phosphate dehydrogenase in the southern cattle tick, Rhipicephalus (Boophilus) microplus

“…The identification of more than one transcript encoding G6PDH in R. microplus was not unexpected, as two allelic products have been described for D. melanogaster (Giesel 1976;Fouts et al 1988), I. typographus (Doleželovǎ et al 2006), and humans (Hirono and Beutler 1989). In I. typographus, the two alleles encode proteins that are 540 aa and 526 aa in length, and the transcriptional start encoding the smaller variant is located within an intron of the gene (Doleželovǎ et al 2006).…”

“…In I. typographus, the two alleles encode proteins that are 540 aa and 526 aa in length, and the transcriptional start encoding the smaller variant is located within an intron of the gene (Doleželovǎ et al 2006). This is similar to the location of the transcriptional start for R. microplus G6PDH -B within Intron 2 of the available tick genomic sequence.…”

“…4), and encodes the G6PDH-A and -B variants. In humans (Martini et al 1986), cattle, fruit flies (Ganguly et al 1985), and the bark beetle (Doleželovǎ et al 2006), G6PDH is encoded by a single gene. Sequence information obtained by amplifying pooled gDNA provided some evidence to support that G6PDH-D may be encoded by the same gene that encodes -A and -B.…”

Genomic Mining of Phylogenetically Informative Nuclear Markers in Bark and Ambrosia Beetles

“…The presence of long and/or numerous introns seems widespread in beetles. This insect order has generally a higher number of introns compared to other insects [ 76 ], particularly so in the phytophagan beetles [ 23 ]. For example, a 300 bp short fragment of the gene Wingless , which is widely used in insect phylogeny, contains three complicated introns in weevils, but it is intron free in adephagan beetles and most other insect orders.…”

Energy balance-dependent regulation of ovine glucose 6-phosphate dehydrogenase protein isoform expression

“…Evidence from other species for G6PDH variants in electrophoretically separated protein extracts 22 , 23 was the aspiration in our research, while the pertinent investigation line was lacking in ruminants since the discovery of the second og6pdb transcript 16 . Our findings not only shed light and confirm similarities and differences in both, og6pdh transcript accumulation 24 and oG6PDH isoform protein expression, in respect to the energy balance changes, but also emphasize the significance of the alternative splicing g6pdb product in the regulation of g6pdh gene expression and oG6PDH enzyme activity.…”