ALS and SAD‐like nicotinic acetylcholine receptor subunit genes are widely distributed in insects

Abstract

Segments of nicotinic acetylcholine receptor alpha subunit genes have been isolated from a panel of insect species by polymerase chain reaction, using degenerate oligonucleotide primers designed to recognize conserved regions of the Drosophila melanogaster ALS and SAD genes. The amplified segments encode elements of typical alpha-subunits anticipated to play roles in ligand binding and ion channel formation. Each is also clearly either ALS or SAD-like. The predicted protein sequences display extremely high levels of conservation (over 85% for each subtype) even though derived from very distantly related insect species.

Cloning and Functional Characterisation of Two Novel Nicotinic Acetylcholine Receptor α Subunits from the Insect Pest Myzus persicae

“…The present study was therefore undertaken to extend knowledge of insect receptors to include a commercially important pest, the peach-potato aphid Myzus persicae. The results confirm the presence of two a subunits similar to those already identified in other insect species (Sgard et al, 1993) and also indicate differences in the functional properties of apparently homologous subunits isolated from different species, at least when expressed in heterologous systems.…”

“…The distinctive electrophysiological and pharmacological characteristics of insect nAChR receptor subunits reported from Xenopus ooeyte expression studies should be considered in the light of clear structural evidence that the a subunits described to date fall into the following two related groups: (1) Da2, Mpal, and aLl, in addition to subunits from other insect species recognised in our earlier study (Sgard et al, 1993); and (2) Mpa2, ALS, and again others described in our earlier study (Sgard et al, 1993). Although the members of these two main a-subunit groups must have been subject to strong selective pressure over extended periods of evolutionary time so that they have retained fundamental similarities in amino acid sequences (Le Novere and Changeux, 1995;Ortells and Lunt, 1995), there is clearly some functional diversity.…”

“…A genomic DNA fragment coding for a portion of an M. persicae nAChR a subunit (termed Mpa 1) that had originally been isolated by PCR (Sgard et al, 1993) was used as a probe to screen the M. persicae eDNA library. Clones corresponding to two distinct nAChR a subunits, Mpa I and Mpa2, were isolated.…”

“…Half the primary library (~5 x i0~independent recombinants) was then screened by using a random primer-labelled 300-bp M. perstcae nAChR genomic fragment previously isolated by PCR and coding for a portion of a putative nAChR a subunit (termed Mpa I ) (Sgard et al, 1993). Filters were hybridised overnight and washed under moderate stringency (65°C; 3 x saline-sodium citrate [0.15 Msodium chloride, 0.015 M trisodium citrate (pH 7.0)1, 0.1% sodium dodecyl sulphate).…”

Characterization of the nicotinic acetylcholine receptor subunit gene Mdα2 from the house fly, Musca domestica

“…A forward primer Ma2F (5¢-ACCCTGCGCCGCAAGACCCTCT-3¢) and reverse primer Ma2R (5¢-CAGGGCCAG TGAGGTGGAGGGTATGA-3¢) were designed based on the partial Mda2 sequence previously reported (Sgard et al, 1993 for 30 s, and 68°C for 2.5 min and a final extension at 68°C for 7 min. PCR product analysis, purification, cloning, and sequencing were done as described above.…”