Qiu-Ning Liu

The complete mitochondrial genome of the wild silkworm moth, Actias selene.

The complete mitochondrial genome (mitogenome) of Actias selene (Lepidoptera: Saturniidae) was determined to be 15,236 bp, including 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes and a control region. The arrangement of 13 PCGs was similar to that of other sequenced lepidopterans. The AT skew of the mitogenome of A. selene was slightly negative, indicating a higher number of T compared to A nucleotides. The nucleotide composition of the mitogenome of A. selene was also biased toward A+T nucleotides (78.91%). All PCGs were initiated by ATN codons, except for the gene encoding cytochrome c oxidase subunit 1 (cox1), which may be initiated by the TTAG, as observed in other lepidopterans. Three genes, including cox1, cox2, and nad5, had incomplete stop codons consisting of just a T. With an exception for trnS1(AGN), all the other tRNA genes displayed a typical clover-leaf structure of mitochondrial tRNA. The A+T-rich region of the mitogenome of A. selene was 339 bp in length, and contains several features common to the Lepidopteras, including non-repetitive sequences, a conserved structure combining the motif ATAGA and an 18-bp poly-T stretch and a poly-A element upstream of trnM gene. Phylogenetic analysis showed that A. selene was close to Saturniidae.

The complete mitogenome of Bombyx mori strain Dazao (Lepidoptera: Bombycidae) and comparison with other lepidopteran insects

The complete mitochondrial genome (mitogenome) of Bombyx mori strain Dazao (Lepidoptera: Bombycidae) was determined to be 15,653bp, including 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes and a A+T-rich region. It has the typical gene organization and order of mitogenomes from lepidopteran insects. The AT skew of this mitogenome was slightly positive and the nucleotide composition was also biased toward A+T nucleotides (81.31%). All PCGs were initiated by ATN codons, except for cytochrome c oxidase subunit 1 (cox1) gene which was initiated by CGA. The cox1 and cox2 genes had incomplete stop codons consisting of just a T. All the tRNA genes displayed a typical clover-leaf structure of mitochondrial tRNA. The A+T-rich region of the mitogenome was 495bp in length and consisted of several features common to the lepidopteras. Phylogenetic analysis showed that the B. mori Dazao was close to Bombycidae.

Characterization of the complete mitochondrial genome of Diaphania pyloalis (Lepidoptera: Pyralididae)

The complete mitochondrial genome (mitogenome) of Diaphania pyloalis (Lepidoptera: Pyralididae) was determined to be 15,298 bp and has the typical gene organization of mitogenomes from lepidopteran insects. It consists of 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes and an A+T-rich region. The A+T content of this mitogenome is 80.83% and the AT skew is slightly positive. All PCGs are initiated by ATN codons, except for cytochrome c oxidase subunit 1 (cox1) gene which is initiated by CGA. Only the cox2 gene has an incomplete stop codon consisting of just a T. All the tRNA genes display a typical clover-leaf structure of mitochondrial tRNA. The A+T-rich region of the mitogenome is 332 bp in length, including several common features found in lepidopteran mitogenomes. Phylogenetic analysis showed that the D. pyloalis is close to Pyralididae.

Characterization of the complete mitochondrial genome of Bombyx mori strain H9 (Lepidoptera: Bombycidae).

The complete mitochondrial genome (mitogenome) of Bombyx mori strain H9 (Lepidoptera: Bombycidae) is 15,670base pairs (bp) in length, encoding 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes and a control region. The nucleotide composition of the genome is highly A+T biased, accounting for 81.31%, with a slightly positive AT skewness (0.059). The arrangement of 13 PCGs is similar to that of other sequenced lepidopterans. All the PCGs are initiated by ATN codons, except for the cytochrome c oxidase subunit 1 (cox1) gene, which is proposed by the TTAG sequence as observed in other lepidopterans. Unlike the other PCGs, the cox1 and cytochrome c oxidase subunit 2 (cox2) genes have incomplete stop codons consisting of just a T. All tRNAs have typical structures of insect mitochondrial tRNAs, which is different from other sequenced lepidopterans. The structure of A+T-rich region is similar to that of other sequenced lepidopterans, including non-repetitive sequences, the ATAGA binding domain, a 18bp poly-T stretch and a poly-A element upstream of transfer RNA M (trnM) gene. Phylogenetic analysis shows that the domesticated silkmoth B. mori originated from the Chinese Bombyx mandarina.

Identification of immune response-related genes in the Chinese oak silkworm, Antheraea pernyi by suppression subtractive hybridization

Insects possess an innate immune system that responds to invading microorganisms. In this study, a subtractive cDNA library was constructed to screen for immune response-related genes in the fat bodies of Antheraea pernyi (Lepidoptera: Saturniidae) pupa challenged with Escherichia coli. Four hundred putative EST clones were identified by suppression subtractive hybridization (SSH), including 50 immune response-related genes, three cytoskeleton genes, eight cell cycle and apoptosis genes, five respiration and energy metabolism genes, five transport genes, 40 metabolism genes, ten stress response genes, four transcription and translation regulation genes and 77 unknown genes. To verify the reliability of the SSH data, the transcription of a set of randomly selected immune response-related genes were confirmed by semi-quantitative reverse transcription-PCR (RT-PCR) and real-time quantitative reverse transcription-PCR (qRT-PCR). These identified immune response-related genes provide insight into understanding the innate immunity in A. pernyi.

The complete mitochondrial genome of the common cutworm, Spodoptera litura (Lepidoptera: Noctuidade)

Abstract The complete mitochondrial genome (mitogenome) of Spodoptera litura (Lepidoptera: Noctuidae) was determined to be 15,374 bp (GenBank accession No. KF543065), including 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes and an A + T-rich region. It has the typical gene organization and order of mitogenomes from lepidopteran insects. The AT skew of this mitogenome was slightly positive and the nucleotide composition was also biased toward A + T nucleotides (81.03%). All PCGs were initiated by ATN codons, except for cytochrome c oxidase subunit 1 (cox1) gene which was initiated by CGA. Four of the 13 PCGs harbor the incomplete termination codon by T. All the tRNA genes displayed a typical clover-leaf structure of mitochondrial tRNA, with the exception of trnS1 (AGN). The A + T-rich region of the mitogenome was 326 bp in length.

IDENTIFICATION AND EXPRESSION ANALYSIS OF VITELLOGENIN RECEPTOR FROM THE WILD SILKWORM, Bombyx mandarina

The vitellogenin receptor (VgR) plays a key role on embryonic development in oviparous animals. Here, we cloned a VgR gene, which was identified from the wild silkworm Bombyx mandarina (BmaVgR) using reverse transcriptase polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). Sequence analysis revealed that BmaVgR is 5,861 bp long with an open reading frame encoded by 1,811 amino acid residues. The predicted amino acid sequence has 99.7 and 98.2% identity with the VgRs of Actias selene and Bombyx mori, respectively. The class B domain sequence of BmaVgR was cloned and expressed in Escherichia coli, and purified by a Ni-NTA column. Polyclonal antibodies were produced against the purified recombinant protein, and titer of the antibody was about 1:12,800 measured by enzyme-linked immunosorbent assay (ELISA). Western blot and RT-qPCR showed that BmaVgR was expressed in the ovary and fat body of female larvae and the ovary of moth, and the expression level was highest at the third day and then declined from third day to seventh in fat body of pupa. After knockdown of the BmaVgR gene through RNA interference (RNAi), other three BmaVgR-related genes (Vg, egg-specific protein, and low molecular weight lipoprotein LP gene) were all downregulated significantly.

Prokaryotic expression of vitellogenin receptor gene of Actias selene Hubner

Vitellogenin receptor plays a key role in the embryonic development of oviparous animals. A vitellogenin receptor (VgR) gene was cloned from Actias selene using reverse transcriptase-polymerase chain reaction and rapid amplification of cDNA end PCR. Sequence analysis revealed that this gene was 5848 bp and encoded a protein of 1812 amino acids peptide with high similarity to Bombyx mori VgR. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and western blotting analysis demonstrated that a 24 and 40 KD recombinant proteins corresponding to the ligand-binding domains of A. selene VgR was successfully expressed in Escherichia coli cells.