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The microRNA toolkit of insects

View Article: PubMed Central - PubMed

ABSTRACT

Is there a correlation between miRNA diversity and levels of organismic complexity? Exhibiting extraordinary levels of morphological and developmental complexity, insects are the most diverse animal class on earth. Their evolutionary success was in particular shaped by the innovation of holometabolan metamorphosis in endopterygotes. Previously, miRNA evolution had been linked to morphological complexity, but astonishing variation in the currently available miRNA complements of insects made this link unclear. To address this issue, we sequenced the miRNA complement of the hemimetabolan Blattella germanica and reannotated that of two other hemimetabolan species, Locusta migratoria and Acyrthosiphon pisum, and of four holometabolan species, Apis mellifera, Tribolium castaneum, Bombyx mori and Drosophila melanogaster. Our analyses show that the variation of insect miRNAs is an artefact mainly resulting from poor sampling and inaccurate miRNA annotation, and that insects share a conserved microRNA toolkit of 65 families exhibiting very low variation. For example, the evolutionary shift toward a complete metamorphosis was accompanied only by the acquisition of three and the loss of one miRNA families.

No MeSH data available.


Properties of the miRNAs identified in Blattella germanica.(A) Length range of the mature miRNA sequence. (B) Length range of the loop of the miRNA precursor. (C) Sequence logo showing the proportion of each nucleotide in each position on the mature mRNA. In the mature miRNA, the most frequent nucleotide in the first position is Uracil (represented as T), whereas the other positions show similar frequencies of each one of the 4 possible bases.
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f2: Properties of the miRNAs identified in Blattella germanica.(A) Length range of the mature miRNA sequence. (B) Length range of the loop of the miRNA precursor. (C) Sequence logo showing the proportion of each nucleotide in each position on the mature mRNA. In the mature miRNA, the most frequent nucleotide in the first position is Uracil (represented as T), whereas the other positions show similar frequencies of each one of the 4 possible bases.

Mentions: The frequencies of occurrence of the mature miRNA in the 5p or 3p arm of the hairpin precursor are consistently similar in the 86 conserved miRNAs: 49% are placed in the 3p and 44% in 5p. When both are similarly expressed and the ratio between the most abundant divided by the least abundant is <2, we considered the miRNAs of both arms as co-mature, which represent a 7% of the miRNAs. The sample of novel miRNAs is smaller, and the frequencies of occurrence of the mature miRNA in the 5p or 3p arm are not so similar (3p = 64%, 5p = 27%, co-mature = 9%, n = 11) (Supplementary Table S1). The length of mature miRNAs ranges between 20 and 25 nucleotides, the most common being 22 nucleotides (Fig. 2A). Moreover, the loop length of the precursor ranges between 8 and 40 nucleotides, the most common being 14–15 nucleotides (Fig. 2B). In 66% of the cases the first nucleotide of the mature miRNA is U, as occurs in miRNAs, in general20, followed by A (17%), C (11%) and G (6%) (Fig. 2C).


The microRNA toolkit of insects
Properties of the miRNAs identified in Blattella germanica.(A) Length range of the mature miRNA sequence. (B) Length range of the loop of the miRNA precursor. (C) Sequence logo showing the proportion of each nucleotide in each position on the mature mRNA. In the mature miRNA, the most frequent nucleotide in the first position is Uracil (represented as T), whereas the other positions show similar frequencies of each one of the 4 possible bases.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5121899&req=5

f2: Properties of the miRNAs identified in Blattella germanica.(A) Length range of the mature miRNA sequence. (B) Length range of the loop of the miRNA precursor. (C) Sequence logo showing the proportion of each nucleotide in each position on the mature mRNA. In the mature miRNA, the most frequent nucleotide in the first position is Uracil (represented as T), whereas the other positions show similar frequencies of each one of the 4 possible bases.
Mentions: The frequencies of occurrence of the mature miRNA in the 5p or 3p arm of the hairpin precursor are consistently similar in the 86 conserved miRNAs: 49% are placed in the 3p and 44% in 5p. When both are similarly expressed and the ratio between the most abundant divided by the least abundant is <2, we considered the miRNAs of both arms as co-mature, which represent a 7% of the miRNAs. The sample of novel miRNAs is smaller, and the frequencies of occurrence of the mature miRNA in the 5p or 3p arm are not so similar (3p = 64%, 5p = 27%, co-mature = 9%, n = 11) (Supplementary Table S1). The length of mature miRNAs ranges between 20 and 25 nucleotides, the most common being 22 nucleotides (Fig. 2A). Moreover, the loop length of the precursor ranges between 8 and 40 nucleotides, the most common being 14–15 nucleotides (Fig. 2B). In 66% of the cases the first nucleotide of the mature miRNA is U, as occurs in miRNAs, in general20, followed by A (17%), C (11%) and G (6%) (Fig. 2C).

View Article: PubMed Central - PubMed

ABSTRACT

Is there a correlation between miRNA diversity and levels of organismic complexity? Exhibiting extraordinary levels of morphological and developmental complexity, insects are the most diverse animal class on earth. Their evolutionary success was in particular shaped by the innovation of holometabolan metamorphosis in endopterygotes. Previously, miRNA evolution had been linked to morphological complexity, but astonishing variation in the currently available miRNA complements of insects made this link unclear. To address this issue, we sequenced the miRNA complement of the hemimetabolan Blattella germanica and reannotated that of two other hemimetabolan species, Locusta migratoria and Acyrthosiphon pisum, and of four holometabolan species, Apis mellifera, Tribolium castaneum, Bombyx mori and Drosophila melanogaster. Our analyses show that the variation of insect miRNAs is an artefact mainly resulting from poor sampling and inaccurate miRNA annotation, and that insects share a conserved microRNA toolkit of 65 families exhibiting very low variation. For example, the evolutionary shift toward a complete metamorphosis was accompanied only by the acquisition of three and the loss of one miRNA families.

No MeSH data available.