Identification of a Bombyx mori gene encoding small heat shock protein BmHsp27.4 expressed in response to high-temperature stress

Characterization, expression profiling, and thermal tolerance analysis of heat shock protein 70 in pine sawyer beetle, Monochamus alternatus hope (Coleoptera: Cerambycidae)

Monochamus alternatus Hope (Coleoptera: Cerambycidae) warrants attention as a dominant transmission vector of the pinewood nematode, and it exhibits tolerance to high temperature. Heat shock protein 70 (HSP70) family members, including inducible HSP70 and heat shock cognate protein 70 (HSC70), are major contributors to the molecular chaperone networks of insects under heat stress. In this regard, we specifically cloned and characterized three MaltHSP70s and three MaltHSC70s. Bioinformatics analysis on the deduced amino acid sequences showed these genes, having close genetic relationships with HSP70s of Coleopteran species, collectively shared conserved signature structures and ATPase domains. Subcellular localization prediction revealed the HSP70s of M. alternatus were located not only in the cytoplasm and endoplasmic reticulum but also in the nucleus and mitochondria. The transcript levels of MaltHSP70s and MaltHSC70s in each state were significantly upregulated by exposure to 35-50°C for early 3 h, while MaltHSP70s reached a peak after exposure to 45°C for 2-3 h in contrast to less-upregulated MaltHSC70s. In terms of MaltHSP70s, the expression threshold in females was lower than that in males. Also, both fat bodies and Malpighian tubules were the tissues most sensitive to heat stress in M. alternatus larvae. Lastly, the ATPase activity of recombinant MaltHSP70-2 in vitro remained stable at 25-40°C, and this recombinant availably enhanced the thermotolerance of Escherichia coli. Overall, our findings unraveled HSP70s might be the intrinsic mediators of the strong heat tolerance of M. alternatus due to their stabilized structure and bioactivity.

Identification and Expression Analysis of Four Small Heat Shock Protein Genes in Cigarette Beetle, Lasioderma serricorne (Fabricius)

Small heat shock proteins (sHsps) are molecular chaperones that play crucial roles in the stress adaption of insects. In this study, we identified and characterized four sHsp genes (LsHsp19.4, 20.2, 20.3, and 22.2) from the cigarette beetle, Lasioderma serricorne (Fabricius). The four cDNAs encoded proteins of 169, 180, 181, and 194 amino acids with molecular weights of 19.4, 20.2, 20.3, and 22.2 kDa, respectively. The four LsHsp sequences possessed a typical sHsp domain structure. Quantitative real-time PCR analyses revealed that LsHsp19.4 and 20.3 transcripts were most abundant in pupae, whereas the transcript levels of LsHsp20.2 and 22.2 were highest in adults. Transcripts of three LsHsp genes were highly expressed in the larval fat body, whereas LsHsp20.2 displayed an extremely high expression level in the gut. Expression of the four LsHsp genes was dramatically upregulated in larvae exposed to 20-hydroxyecdysone. The majority of the LsHsp genes were significantly upregulated in response to heat and cold treatments, while LsHsp19.4 was insensitive to cold stress. The four genes were upregulated when challenged by immune triggers (peptidoglycan isolated from Staphylococcus aureus and from Escherichia coli 0111:B4). Exposure to CO₂ increased LsHsp20.2 and 20.3 transcript levels, but the LsHsp19.4 transcript level declined. The results suggest that different LsHsp genes play important and distinct regulatory roles in L. serricorne development and in response to diverse stresses.

Molecular cloning and functional analysis of small heat shock protein 19.1 gene from the Chinese oak silkworm, Antheraea pernyi

Small heat shock proteins (sHSPs) are a class of highly conserved proteins that are ubiquitously found in all types of organisms, from prokaryotes to eukaryotes. In the current study, we identified and characterized the full-length cDNA encoding sHSP 19.1 from the oak silkworm, Antheraea pernyi. Ap-sHSP is 510 bp in length, and encodes a protein of 169 amino acid residues. The protein contains conserved domains found in insect sHSPs, and it belongs to the α-crystallin-HSPs_p23-like superfamily. Recombinant Ap-sHSP was expressed in Escherichia coli cells, and a rabbit anti-Ap-sHSP 19.1 antibody was generated to confirm the biological functions of Ap-sHSP 19.1 in A. pernyi. Real-time polymerase chain reaction and western blot analysis revealed that Ap-sHSP 19.1 expression was highest in the fat body, followed by the midgut, and the lowest expression was found in the Malpighian tubule. Ap-sHSP 19.1 transcript expression was significantly induced following challenge with microbial pathogens. In addition, the expression of Ap-sHSP 19.1 was strongly induced after heat shock. These results suggest that Ap-sHSP 19.1 plays a crucial role in immune responses and thermal tolerance in A. pernyi.

Characteristics of six small heat shock protein genes from Bactrocera dorsalis: Diverse expression under conditions of thermal stress and normal growth

To explore the functions of small heat shock proteins (sHsps) in relation to thermal stress and development in Bactrocera dorsalis (Hendel), one of the most economically important pest species attacking a wide range of fruits and vegetables, six full-length cDNAs of sHsp genes (BdHsp17.7, 18.4, 20.4, 20.6, 21.6 and 23.8) were cloned, and the expression patterns in different developmental stages and tissues, as well as in response to both thermal and 20-hydroxyecdysone (20E) exposures, were examined using real time quantitative PCR. The open reading frames (ORFs) of six sHsps are 453, 489, 537, 543, 567 and 630bp in length, encoding proteins with molecular weights of 17.7, 18.4, 20.4, 20.6, 21.6 and 23.8kDa, respectively. BdHsp18.4 and BdHsp20.4 maintained lower expression levels in both eggs and larvae, whereas remarkably up-regulated after the larval-pupal transformation, suggesting that these two sHsps may be involved in metamorphosis. Significant tissue specificity exists among sHsps: the highest expression of BdHsp20.6 and BdHsp23.8 in the Malpighian tubules and ovary, respectively, versus a peak in the fat body for others. BdHsp20.4 and BdHsp20.6 were significantly up-regulated by thermal stress. In contrast, BdHsp18.4 and BdHsp23.8 reacted only to heat stress. BdHsp17.7 and BdHsp21.6 were insensitive to both heat and cold stresses. The degree of sHsps response depends on intensity of 20E treatment, i.e., dose and time. These results strongly suggest functional differentiation within the sHsp subfamily in B. dorsalis. The physiological function of sHsp members under thermal stress and normal growth remains the subjects of further investigation.

Composite Electrospun Scaffold Derived from Recombinant Fibroin of Weaver Ant (Oecophylla smaragdina) as Cell-Substratum

Unlike silkworm (Bombyx mori) fibroin (SF), weaver ant (Oecophylla smaragdina) fibroin (WAF) is much less studied. Due to differences in amino acid composition and protein structure, this work aimed to produce the recombinant WAF protein, designated as WAF1, and investigated on its potential application as a biomaterial for producing a cell-substratum. The composite electrospun scaffolds derived from poly(vinyl alcohol) (PVA), WAF1, and extracted SF were produced by electrospinning. SEM images revealed non-woven and smooth fibers of PVA, PVA-WAF1, and PVA-SF scaffolds with the average diameters of 204.1 ± 59.9, 206.5 ± 71.5, and 238.4 ± 77.9 nm, respectively. ATR-FTIR spectra indicated characteristic absorption peaks related to the chemical structure of PVA and protein. The PVA-WAF1 scaffold demonstrated a higher water uptake, a slightly higher rate of degradation, and a similar low cytotoxicity as compared with the PVA-SF scaffold. Although the adhesion and proliferation of cells on the PVA-WAF1 scaffold were lower than those on the PVA-SF scaffold, it showed significantly greater values of adhering and proliferating cells than the PVA scaffold. The results of this work suggested that WAF1 could be used as a biomaterial for producing a cell-substratum that supports cell adhesion and growth.

Cloning & sequence identification of Hsp27 gene and expression analysis of the protein on thermal stress in Lucilia cuprina

Hsp27, a highly conserved small molecular weight heat shock protein, is widely known to be developmentally regulated and heat inducible. Its role in thermotolerance is also implicated. This study is a sequel of our earlier studies to understand the molecular organization of heat shock genes/proteins and their role in development and thermal adaptation in a sheep pest, Lucilia cuprina (blowfly), which exhibits unusually high adaptability to a variety of environmental stresses, including heat and chemicals. In this report our aim was to understand the evolutionary relationship of Lucilia hsp27 gene/protein with those of other species and its role in thermal adaptation. We sequence characterized the Lchsp27 gene (coding region) and analyzed its expression in various larval and adult tissues under normal as well as heat shock conditions. The nucleotide sequence analysis of 678 bps long-coding region of Lchsp27 exhibited closest evolutionary proximity with Drosophila (90.09%), which belongs to the same order, Diptera. Heat shock caused significant enhancement in the expression of Lchsp27 gene in all the larval and adult tissues examined, however, in a tissue specific manner. Significantly, in Malpighian tubules, while the heat-induced level of hsp27 transcript (mRNA) appeared increased as compared to control, the protein level remained unaltered and nuclear localized. We infer that Lchsp27 may have significant role in the maintenance of cellular homeostasis, particularly, during summer months, when the fly remains exposed to high heat in its natural habitat.

KPNA3-knockdown eliminates the second heat shock protein peak associated with the heat shock response of male silkworm pupae (Bombyx mori) by reducing heat shock factor transport into the nucleus

In this study, we investigated the role of karyopherin alpha 3 in the heat shock response in male silkworm pupae. Karyopherin alpha recognizes the classical nuclear location sequence on proteins and transports them into the nucleus by forming a trimetric complex with karyopherin beta. Three predicted karyopherin alphas (KPNA1, KPNA2 and KPNA3) have been identified from the silkworm Bombyx mori. Pull-down assay result showed that KPNA3 can pull down heat shock transcription factor (HSF) from proteins extracted from tissues using non-denature lysis buffer. After 45 °C heat shock on male B. mori pupae for 30 min, we identified two heat shock protein (HSP) mRNA expression peaks correlating with HSP19.9, HSP20.4 and HSP25.4 at 4 h (peak 1) and 24 h (peak 2). The second peak was eliminated after knockdown of KPNA3. Similar results were obtained following knockdown of HSF, which is the trans-activating factor of heat shock. However, KPNA3 knockdown was not accompanied by the decreased HSF protein levels at 24 h after heat shock which were observed following HSF knockdown. We also expressed recombinant protein GST-KPNA3 and His-HSF in Escherichia coli to perform GST pull-down assay and the result confirmed the interaction between KPNA3 and HSF. We concluded that KPNA3 knockdown eliminates the second heat shock protein peak in the heat shock response of male silkworm pupae by reducing HSF transport into the nucleus.

Cloning of expansin genes in ramie (Boehmeria nivea L.) based on universal fast walking

Gene cloning is the first step to study the expression profiles and functions of a particular gene; considerable cloning methods have been developed. Expansin, thought to involve in the cell-wall modification events, was not cloned in ramie (Boehmeria nivea L.), which is one of the most important bast fiber crops with little conducted molecular research, especially on its fiber development. Studying the expansin gene family will uncover its possible relationship with ramie fiber development and other growth events. As a result, five expansin genes were cloned with full-length and their sequence information was investigated. Additionally, the phylogenetic analysis was conducted, which suggested that the cloned genes belong to the α-subfamily, and these genes expressed differently during ramie fiber developmental process. In this study, we aimed to apply a strategy for cloning novel full-length genes from genomic DNA of ramie, based on using degenerate primers, touchdown polymerase chain reaction and universal fast walking protocols. By cloning five full-length expansin genes, we believe the polymerase chain reaction-based gene cloning strategy could be applied to general gene studies in ramie and other crops.