Insect muscle actins differ distinctly from invertebrate and vertebrate cytoplasmic actins

Abstract

Invertebrate actins resemble vertebrate cytoplasmic actins, and the distinction between muscle and cytoplasmic actins in invertebrates is not well established as for vertebrate actins. However, Bombyx and Drosophila have actin genes specifically expressed in muscles. To investigate if the distinction between muscle and cytoplasmic actins evidenced by gene expression analysis is related to the sequence of corresponding genes, we compare the sequences of actin genes of these two insect species and of other Metazoa. We find that insect muscle actins form a family of related proteins characterized by about 10 muscle-specific amino acids. Insect muscle actins have clearly diverged from cytoplasmic actins and form a monophyletic group emerging from a cluster of closely related proteins including insect and vertebrate cytoplasmic actins and actins of mollusc, cestode, and nematode. We propose that muscle-specific actin genes have appeared independently at least twice during the evolution of animals: insect muscle actin genes have emerged from an ancestral cytoplasmic actin gene within the arthropod phylum, whereas vertebrate muscle actin genes evolved within the chordate lineage as previously described.

Molecular genetics of actin function

“…Actin phylogenetic trees ([55,56,58,59]; Figure 1) produce relatively few groupings which can be considered significant [56,59], a consequence of the high sequence conservation of actins. The major divisions correspond to conventional taxonomic classifications.…”

“…Indeed, vertebrate cytoplasmic actins are more similar to arthropod actins than to vertebrate muscle actins [55], indicating a very ancient common origin for actin genes [59]. Within arthropods, Drosophila melanogaster (Diptera) and Bombyx mori (Lepidoptera) muscle actins form a group distinct from their cytoplasmic actins [59].…”

Induction of actin gene expression in the mosquito midgut by blood ingestion correlates with striking changes of cell shape

“…They are highly conserved in evolution at both the nucleic and amino acid sequence levels (Fyrberg et al, 1980;Zafar and Sodja, 1983;Mounier et al, 1987;Hadden and Sodja, 1994). In contrast to the high conservation of their amino acid sequence, actins have a broad spectrum of functions.…”

Detection and Quantification of Infectious Hypodermal and Hematopoietic Necrosis Virus and White Spot Virus in Shrimp Using Real-Time Quantitative PCR and SYBR Green Chemistry

“…All the PCR primers were designed using Primer Express Software version 1.0 (PE Applied Biosystems) and are listed in Table 1. The primers for ␤-actin were designed based on the conserved sequences of the Drosophila melanogaster, sea urchin, and insect ␤-actin genes (4,7,21). The reaction mixture for IHHNV, WSV, and ␤-actin amplifications contained 1ϫ PCR buffer (PE Applied Biosystems), 2 mM MgCl 2 , a 0.8 M concentration of each forward and reverse primer, 0.4 mM deoxynucleoside triphosphate, and 2.5 U of AmpliTaq Gold (PE Applied Biosystems).…”