MOLECULAR CHARACTERIZATION OF AN APOLIPOPHORIN‐III GENE FROM THE CHINESE OAK SILKWORM,Antheraea pernyi (LEPIDOPTERA: SATURNIIDAE)

Apolipophorin‐III (ApoLp‐III) acts in lipid transport, lipoprotein metabolism, and innate immunity in insects. In this study, an ApoLp‐III gene of Antheraea pernyi pupae (Ap‐ApoLp‐III) was isolated and characterized. The full‐length cDNA of Ap‐ApoLp‐III is 687 bp, including a 5′‐untranslated region (UTR) of 40 bp, 3′‐UTR of 86 bp and an open reading frame of 561 bp encoding a polypeptide of 186 amino acids that contains an Apolipophorin‐III precursor domain (PF07464). The deduced Ap‐apoLp‐III protein sequence has 68, 59, and 23% identity with its orthologs of Manduca sexta, Bombyx mori, and Aedes aegypti, respectively. Phylogenetic analysis showed that the Ap‐apoLp‐III was close to that of Bombycoidea. qPCR analysis revealed that Ap‐ApoLp‐III expressed during the four developmental stages and in integument, fat body, and ovaries. After six types of microorganism infections, expression levels of the Ap‐ApoLp‐III gene were upregulated significantly at different time points compared with control. RNA interference (RNAi) of Ap‐ApoLp‐III showed that the expression of Ap‐ApoLp‐III was significantly downregulated using qPCR after injection of E. coli. We infer that the Ap‐ApoLp‐III gene acts in the innate immunity of A. pernyi.     

Molecular cloning,expression pattern and phylogenetic analysis of the <Emphasis Type="Italic">will die slowly</Emphasis> gene from the Chinese oak silkworm, <Emphasis Type="Italic">Antheraea pernyi</Emphasis>

The will die slowly (wds) gene coding for a WD-repeat protein with seven repeats has been characterized in Drosophila melanogaster. In this paper, the wds gene was isolated and characterized from the Chinese oak silkworm, Antheraea pernyi (Lepidoptera: Saturniidae). The obtained 1733 bp cDNA sequence contains an open reading frame of 1041 bp encoding a polypeptide of 346 amino acids, with 85% sequence identity to that from D. melanogaster. RT-PCR analysis showed that the wds gene was transcribed during four developmental stages and in all the tissues tested, consistent with the result observed in Bombyx mori based on EST resources and genome-wide microarray information. The mRNA expression level of the A. pernyi wds gene was not significantly down- or up- regulated under temperature stress compared to the control, indicating that it may be not involved in temperature stress tolerance. In search of database, the wds protein homologues were found in various kinds of eukaryotes, including fungi, plants, invertebrates and vertebrates, with 50–93% amino acid sequence identities between them, suggesting that they are highly conserved during the evolution of eukaryotes. Phylogenetic analysis based on the wds protein homologue sequences clearly separated the known fungi, plants, invertebrates and vertebrates, consistent with the topology tree on the classical systematics, suggesting the potential value of wds protein in eukaryotic phylogenetic inference. In vertebrates, two apparent types of the wds proteins were also defined by sequence alignment and phylogenetic analysis.     

The complete mitogenome and phylogenetic analysis of <Emphasis Type="Italic">Bombyx mandarina</Emphasis> strain Qingzhou

The complete nucleotide sequence of the mitogenome of Bombyx mandarina strain Qingzhou was determined. The circular genome is 15,717 bp long and has the typical gene organization and order of lepidopteran mitogenomes. All protein-coding sequences are initiated with a typical ATN codon, except the COI gene, which has a 4-bp TTAG putative initiator codon. Eleven of the 13 protein-coding gene have a complete termination codon (all TAA), but the remaining two genes terminate with incomplete codons. All transfer RNAs (tRNAs) have a clover-leaf structure typical of the mitochondrial tRNAs, and some of them have a mismatch in the four-stem-and-loop structure. The length of the A + T rich region of B. mandarina strain Qingzhou is 495 bp, shorter than that of B. mandarina strain Tsukuba (747 bp) but similar to that of Bombyx mori. Phylogenetic analysis based on the whole mitochondrial genome sequences of the available sequenced species (B. mori strains C-108, Aojuku, Backokjam, and Xiafang, B. mandarina strains Tsukuba, Ankang, and Qingzhou, and Antheraea pernyi) shows the origin of the domesticated silkmoth B. mori to be the Chinese B. mandarina. Nuclear mitochondrial pseudogene sequences were detected in the nuclear genome of B. mori with the MEGA BLAST search program. A phylogenetic analysis of these nuclear mitochondrial pseudogene sequences suggests that B. mori was domesticated independently in different areas and periods.     

Molecular characterization of DnaJ 5 homologs in silkworm Bombyx mori and its expression during egg diapause

A comparison of the cDNA sequences （1 056 bp） of Bombyx mori DnaJ 5 homolog with B. mori genome revealed that unlike in other Hsps, it has an intron of 234 bp. The DnaJ 5 homolog contains 351 amino acids, of which 70 contain the conserved DnaJ domain at the N-terminal end. This homolog orB. mori has all desirable functional domains similar to other insects, and the 13 different DnaJ homologs identified in B. mori genome were distributed on different chromosomes. The expressed sequence tag database analysis of Hsp40 gene expression revealed higher expression in wing disc followed by diapause-induced eggs. Microarray analysis revealed higher expression of DnaJ 5 homolog at 18th h after oviposition in diapause-induced eggs. Further validation of DnaJ 5 expression through qPCR in diapause-induced and nondiapause eggs at different time intervals revealed higher expression in diapause eggs at 18 and 24 h after oviposition, which coincided with the expression of Hsp70 as the Hsp 40 is its co-chaperone. This study thus provides an outline of the genome organization of lisp40 gene, and its role in egg diapause induction in B. mori.     

Cooperation between the chloroplast psbA 5′‐untranslated region and coding region is important for translational initiation: the chloroplast translation machinery cannot read a human viral gene coding region

Chloroplast mRNA translation is regulated by the 5′‐untranslated region (5′‐UTR). Chloroplast 5′‐UTRs also support translation of the coding regions of heterologous genes. Using an in vitro translation system from tobacco chloroplasts, we detected no translation from a human immunodeficiency virus tat coding region fused directly to the tobacco chloroplast psbA 5′‐UTR. This lack of apparent translation could have been due to rapid degradation of mRNA templates or synthesized protein products. Replacing the psbA 5′‐UTR with the E. coli phage T7 gene 10 5′‐UTR, a highly active 5′‐UTR, and substituting synonymous codons led to some translation of the tat coding region. The Tat protein thus synthesized was stable during translation reactions. No significant degradation of the added tat mRNAs was observed after translation reactions. These results excluded the above two possibilities and confirmed that the tat coding region prevented its own translation. The tat coding region was then fused to the psbA 5′‐UTR with a cognate 5′‐coding segment. Significant translation was detected from the tat coding region when fused after 10 or more codons. That is, translation could be initiated from the tat coding region once translation had started, indicating that the tat coding region inhibits translational initiation but not elongation. Hence, cooperation/compatibility between the 5′‐UTR and its coding region is important for translational initiation.     

Sexually dimorphic expression and regulatory sequence of dnali1 in the olive flounder Paralichthys olivaceus

Dynein axonemal light intermediate chain 1 (dnali1) is an important part of axonemal dyneins and plays an important role in the growth and development of animals. However, there is little information about dnali1 in fish. Herein, we cloned dnali1 gene from the genome of olive flounder (Paralichthys olivaceus), a commercially important maricultured fish in China, Japan, and Korea, and analyzed its expression patterns in different gender fish. The flounder dnali1 DNA sequence contained a 771 bp open reading frame (ORF), two different sizes of 5′ untranslated region (5′UTR), and a 1499 bp 3′ untranslated region (3′UTR). Two duplicated 922 nt fragments were found in dnali1 mRNA. The first fragment contained the downstream coding region and the front portion of 3′UTR, and the second fragment was entirely located in 3′UTR. Multiple alignments indicated that the flounder Dnali1 protein contained the putative conserved coiled-coil domain. Its expression showed sexually dimorphic with predominant expression in the flounder testis, and lower expression in other tissues. The gene with the longer 5′UTR was specifically expressed in the testis. The highest expression level in the testis was detected at stages IV and V. Transient expression analysis showed that the 922 bp repeated sequence 3′UTR of dnali1 down-regulated the expression of GFP at the early stage in zebrafish. The flounder dnali1 might play an important role in the testis, especially in the period of spermatogenesis, and the 5′UTR and the repetitive sequences in 3′UTR might contain some regulatory elements for the cilia.

     

Rapid depletion of mutant eukaryotic initiation factor 5A at restrictive temperature reveals connections to actin cytoskeleton and cell cycle progression

Eukaryotic initiation factor 5A (eIF5A) is the only protein in nature that contains hypusine, an unusual amino acid derived from the modification of lysine by spermidine. Two genes, TIF51A and TIF51B, encode eIF5A in the yeast Saccharomyces cerevisiae. In an effort to understand the structure–function relationship of eIF5A, we have generated yeast mutants by introducing plasmid-borne tif51A into a double null strain where both TIF51A and TIF51B have been disrupted. One of the mutants, tsL102A strain (tif51A L102A tif51aΔ tif51bΔ) exhibits a strong temperature-sensitive growth phenotype. At the restrictive temperature, tsL102A strain also exhibits a cell shape change, a lack of volume change in response to temperature increase and becomes more sensitive to ethanol, a hallmark of defects in the PKC/WSC cell wall integrity pathway. In addition, a striking change in actin dynamics and a complete cell cycle arrest at G1 phase occur in tsL102A cells at restrictive temperature. The temperature-sensitivity of tsL102A strain is due to a rapid loss of mutant eIF5A with the half-life reduced from 6 h at permissive temperature to 20 min at restrictive temperature. Phenylmethyl sulfonylfluoride (PMSF), an irreversible inhibitor of serine protease, inhibited the degradation of mutant eIF5A and suppressed the temperature-sensitive growth arrest. Sorbitol, an osmotic stabilizer that complement defects in PKC/WSC pathways, stabilizes the mutant eIF5A and suppresses all the observed temperature-sensitive phenotypes.     

Molecular cloning and expression analysis of a myosin light chain 1 (MLC‐1) gene from Indian meal moth Plodia interpunctella (Lepidoptera: Pyralidae)

Myosin light chain 1 (MLC‐1) protein acts in the organization, dynamics and transport processes associated with the cytoskeleton. In this work, an MLC‐1 gene was cloned and characterized from the Indian meal moth, Plodia interpunctella (Lepidoptera: Pyralidae). The isolated PiMLC‐1 cDNA is 913 bp, including a 5′‐untranslated region (UTR) of 79 bp, 3′‐UTR of 381 bp and an open reading frame (ORF) of 453 bp encoding a polypeptide of 150 amino acids, which contains two calcium binding domains (EF‐hands). The deduced PiMLC‐1 protein sequence has 39–94% comparison with other individuals. The qPCR analysis revealed that PiMLC‐1 was expressed in the four developmental stages (egg, larva, pupa and adult) and in all tissues tested, suggesting that it plays an important role in development of P. interpunctella. Based on the MLC‐1 amino acids, phylogenetic analysis showed a similar topology with the traditional classification, suggesting the potential value of the MLC‐1 protein in phylogenetic inference.     

cDNA cloning and mRNA expression of LIM protein gene homologue from the silkworm, Bombyx mori

LIM protein cDNA, from Bombyx mori that contains an open reading frame of 622 bp encoding 94 amino acids, was identified and characterized. The B. mori LIM protein homologue is classified into group 2 LIM proteins that contain glycine-rich LIM domain. B. mori LIM protein mRNA is up-regulated at late embryogenesis and detected in the mid-gut of 5th instar larvae.     

Molecular characterization of the sans fille gene in Antheraea pernyi: A highly conserved gene during the evolution of animals

Sans-fille (SNF) is the Drosophila homologue of mammalian general splicing factors U1A and U2B″, and plays an important role in sex determination in Drosophila melanogaster. In this study, the snf gene from Antheraea pernyi (Lepidoptera: Saturniidae), an economically important insect, was isolated and characterized. The obtained 925 bp cDNA sequence contains an open reading frame of 669 bp encoding a polypeptide of 222 amino acids, showing 78% sequence identity to that from D. melanogaster. A database search revealed that SNF protein homologs are present in many animals, including invertebrates and vertebrates, with more than 70% amino acid sequence identities, suggesting that they were highly conserved during the evolution of animals. Phylogenetic analysis revealed that A. pernyi SNF was closely related to Bombyx mori SNF. Quantitative real-time PCR (qRT-PCR) analysis showed that the A. pernyi snf gene was transcribed during five larval developmental stages, and in six tested tissues (ovaries, testes, silk glands, fat body, integument, and hemolymph), with the most abundance determined in the gonads (ovaries or testes). Investigation of expression changes throughout embryonic development indicated that A. pernyi snf mRNA was expressed at a low level from days 0 to 4, and reached a maximum level at day 10, but decreased to a low level before hatching. These results suggest that the product of the snf gene may play important roles in the development of A. pernyi.     

A chromosome‐scale genome assembly of Antheraea pernyi (Saturniidae,Lepidoptera)

Antheraea pernyi is a semi‐domesticated lepidopteran insect species valuable to the silk industry, human health, and ecological tourism. Owing to its economic influence and developmental properties, it serves as an ideal model for investigating divergence of the Bombycoidea super family. However, studies on the karyotype evolution and functional genomics of A. pernyi are limited by scarce genomic resource. Here, we applied PacBio sequencing and chromosome structure capture technique to assemble the first high‐quality A. pernyi genome from a single male individual. The genome is 720.67 Mb long with 49 chromosomes and a 13.77‐Mb scaffold N50. Approximately 441.75 Mb, accounting for 60.74% of the genome, was identified as repeats. The genome comprises 21,431 protein‐coding genes, 85.22% of which were functionally annotated. Comparative genomics analysis suggested that A. pernyi diverged from its common ancestor with A. yamamai ~30.3 million years ago, and that chromosome fission contributed to the increased chromosome number. The genome assembled in this work will not only facilitate future research on A. pernyi and related species but also help to progress comparative genomics analyses in Lepidoptera.     

Deciphering the DNA repair protein, Rad23 from kuruma shrimp Marsupenaeus japonicus: full-length cDNA cloning and characterization

Aims: Lesions of DNA are removed by nucleotide excision repair (NER) process in the living systems. NER process‐related host factors are believed to aid recovery steps during viral integration. Here, we report identification and characterization of a DNA repair molecule Rad23 from kuruma shrimp Marsupenaeus japonicus. Methods and Results: The full‐length cDNA of M. japonicus Rad23 gene (MjRad23) has 1149 bp coding for a putative protein of 382 amino acids with a 5′ untranslated region (UTR) of 92 bp and 3′ UTR region of 1116 bp. Quantitative expression analysis revealed MjRad23 is constitutively expressed in all the organs of healthy shrimp, whereas with high level in muscle tissue. Although MjRad23 expression is observed in every haemolymph samplings to post‐white spot syndrome virus infection, high expression is recorded at 2 h post infection (h.p.i.). MjRad23 consists of putative functional domains including one ubiquitin domain (UBQ), two ubiquitin‐associated domains (UBA) and one heat‐shock chaperonin‐binding motif (STI1). Multiple alignment of MjRad23 with Rad23 of other species showed highly significant identity ranging from 37 to 53%; however, high homology is observed with Rad23 of Bombyx mori (BmRad23). UBQ domain region alignment revealed maximum of 66% homology with Rad23 of Apis melifera (AmRad23). MjRad23 clustered with invertebrate sector along with insect species in evolution analysis. Three‐dimensional structural analyses demonstrated the highest identity between MjRad23 and human Rad23A (hHR23A). Conclusions: The present work revealed the presence of MjRad23 gene, which is essential in DNA repair process. Further studies are required to clarify the involvement of MjRad23 in NER process. Significance and Impact of the Study: This is the first report on identification and characterization of DNA repair protein in crustaceans, which will lead to further investigation to explore the molecular mechanisms behind the NER process.     

Molecular Cloning of cDNA for Trehalase from the European Honeybee,Apis mellifera L., and Its Heterologous Expression in Pichia pastoris

cDNA encoding the bound type trehalase of the European honeybee was cloned. The cDNA (3,001 bp) contained the long 5′ untranslated region (UTR) of 869 bp, and the 3′ UTR of 251 bp including a poly(A) tail, and the open reading frame of 1,881 bp consisting of 626 amino acid residues. The M _r of the mature enzyme comprised of 591 amino acids, excluded a signal sequence of 35 amino acid residues, was 69,177. Six peptide sequences analyzed were all found in the deduced amino acid sequence. The amino acid sequence exhibited high identity with trehalases belonging to glycoside hydrolase family 37. A putative transmembrane region similar to trehalase-2 of the silkworm was found in the C-terminal amino acid sequence. Recombinant enzyme of the trehalase was expressed in the methylotrophic yeast Pichia pastoris as host, and displayed properties identical to those of the native enzyme except for higher sugar chain contents. This is the first report of heterologous expression of insect trehalase.     

Evidence for a Negative Cooperativity between eIF5A and eEF2 on Binding to the Ribosome

eIF5A is the only protein known to contain the essential and unique amino acid residue hypusine. eIF5A functions in both translation initiation due to its stimulation of methionyl-puromycin synthesis and translation elongation, being highly required for peptide-bound formation of specific ribosome stalling sequences such as poly-proline. The functional interaction between eIF5A, tRNA, and eEF2 on the surface of the ribosome is further clarified herein. Fluorescence anisotropy assays were performed to determine the affinity of eIF5A to different ribosomal complexes and reveal its interaction exclusively and directly with the 60S ribosomal subunit in a hypusine-dependent manner (K_i^{60S-eIF5A-Hyp} = 16 nM, K_i^{60S-eIF5A-Lys} = 385 nM). A 3-fold increase in eIF5A affinity to the 80S is observed upon charged-tRNA_i^Met binding, indicating positive cooperativity between P-site tRNA binding and eIF5A binding to the ribosome. Previously identified conditional mutants of yeast eIF5A, eIF5A^Q22H/L93F and eIF5A^K56A, display a significant decrease in ribosome binding affinity. Binding affinity between ribosome and eIF5A-wild type or mutants eIF5A^K56A, but not eIF5A^Q22H/L93F, is impaired in the presence of eEF2 by 4-fold, consistent with negative cooperativity between eEF2 and eIF5A binding to the ribosome. Interestingly, high-copy eEF2 is toxic only to eIF5A^Q22H/L93F and causes translation elongation defects in this mutant. These results suggest that binding of eEF2 to the ribosome alters its conformation, resulting in a weakened affinity of eIF5A and impairment of this interplay compromises cell growth due to translation elongation defects.