Insect Molecular Biology and Biochemistry

Insect Genomics Part 1

Summary Genomic sequencing has become a routinely used molecular biology tool in many insect science laboratories. In fact, whole-genome sequences for 22 insects have already been completed, and sequencing of genomes of many more insects is in progress. This information explosion on gene sequences has led to the development of bioin-formatics and several "omics" disciplines, […]

Insect Genomics Part 2

Sequenced Genomes Fruit fly, Drosophila melanogaster. The D. melano-gaster sequencing project used several types of sequencing strategies, including sequencing of individual clones, and sequencing of genomic libraries with three insert sizes (Adams et al., 2000). A portion of the D. melanogaster genome corresponding to approximately 120 megabases of euchromatin was assembled. This assembled genomic sequence […]

Insect Genomics Part 3

Global gene expression analysis (transcriptome analysis) DNA microarray fabrication. The DNA microarrays used for global gene expression analysis usually contain tens of thousands of probes which cover all the predicted genes in a genome, or sequences representing transcribed regions, also called expressed sequence tags (ESTs). For example, the Affymetrix GeneChip® Table 2 List of Applications […]

Insect Genomics Part 4

Proteomics Proteomics is the study of all proteins present in an organism, and deals with their quantification, identification, and modifications that alter their function. While statistically significant changes in mRNA levels are usually correlated with changes in protein levels, individual proteins can change drastically with little significant correlation at the mRNA level (Bonaldi et al., […]

Insect MicroRNAs: From Molecular Mechanisms to Biological Roles Part 1

Summary MicroRNAs (miRNAs) are endogenous, ca. 22-nucleo-tide, single-strand, non-coding RNAs that regulate gene expression by acting post-transcriptionally through base-pairing between the so called "seed" sequence of the miRNA (nucleotides 2-8 at its 5′ end) and its complementary seed match sequence present in the 3′ untranslated region of the target mRNA. Since the discovery of the […]

Insect MicroRNAs: From Molecular Mechanisms to Biological Roles Part 2

Mechanism of Action of miRNAs The functional role of a miRNA is ultimately characterized by its effects on the expression of target genes. Currently, the regulatory mechanisms involving miRNAs are related to mRNA cleavage or translational repression by binding to complementary sites usually located on the 3′ UTR region of the mRNA (Carrington and Ambros, […]

Insect MicroRNAs: From Molecular Mechanisms to Biological Roles Part 3

microCosm, TargetScan, and PicTar The miRBase database links miRNAs to targets using microCosm (http://www.ebi.ac.uk/enright-srv/microcosm/), TargetScan (Lewis et al., 2005; Grimson et al., 2007; Friedman et al., 2009) and PicTar (Lewis et al., 2005; Grimson et al., 2007; Friedman et al., 2009) prediction systems. These are therefore the most currently used, and are detailed below. microCosm, […]

Insect MicroRNAs: From Molecular Mechanisms to Biological Roles Part 4

Embryo Patterning and Morphogenesis After injecting anti-miDNA-2a and anti-miDNA-13a, D. melanogaster embryos exhibited defects in the head and posterior abdominal segments, including cuticle holes and denticle belt malformations. In view of the similarity of the induced phenotypes, Boutla and colleagues (2003) concluded that these related miRNAs, miR-2a and miR-13a, act on the same target genes, […]

Insect Transposable Elements Part 1

Introduction More than half a century ago, Barbara McClintock’s observation of unstable mutations in maize led to the discovery of two mobile genetic elements, Activator (Ac) and Dissociator (Ds) (McClintock, 1948, 1950). Her discovery of these mobile segments of DNA, later named transpos-able elements (TEs), set forth the revolutionary concept of a fluid and dynamic […]

Insect Transposable Elements Part 2

Methods to Uncover and Characterize Insect TEs Early Discoveries and General Criteria Before the availability of the large amount of genomic sequence data, TEs were often discovered by serendipitous observations during genetic experiments. As described in the introduction, McClintock’s observation of the unstable mutations in maize led to her discovery of two mobile genetic elements, […]

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