Identification and functional analysis of C-type lectin from mosquito Aedes albopictus in response to dengue virus infection.

BACKGROUND: C-type lectins (CTLs) are a large family of proteins with sugar-binding activity. CTLs contain an evolutionarily conserved C-type lectin domain (CTLD) that binds microbial carbohydrates in a calcium-dependent manner, thereby playing a key role in both microbial pathogenesis and innate immune responses. Aedes albopictus is an important vector for transmitting dengue virus (DENV) worldwide. Currently, the molecular characteristics and functions of CTLs in Ae. albopictus are largely unknown. METHODS: Transcripts encoding CTL proteins in the Ae. albopictus genome assembly were analyzed via sequence blast. Phylogenetic analysis and molecular characterization were performed to identify the functional domains of the CTLs. Quantitative analysis was performed to determine the gene expression features of CTLs during mosquito development and in different tissues of female adults after blood feeding. In addition, the functional role of CTLs in response to DENV infection was investigated in Ae. albopictus mosquito cells. RESULTS: We identified 39 transcripts encoding CTL proteins in the Ae. albopictus transcriptome. Aedes albopictus CTLs are classified into three groups based on the number of CTLDs and the domain architecture. These included 29 CTL-Ss (single-CTLDs), 1 immulectins (dual-CTLD) and 9 CTL-Xs (CTLDs with other domains). Phylogenetic analysis and structural modeling indicated that CTLs in Ae. albopictus are highly conserved with the homologous CTLs in Aedes aegypti. The expression profile assay revealed differential expression patterns of CTLs in both developmental stages and in adult female tissues. Knockdown and overexpression of three CTLs (CTL-S12, S17 and S19) confirmed that they can promote dengue virus infection in Ae. albopictus cells. CONCLUSIONS: The CTL genes in Ae. albopictus mosquito and other mosquito species are evolutionarily conserved and exhibit different developmental and tissue expression features. The functional assay indicated that three CTLs in Ae. albopictus mosquitoes are involved in promoting dengue virus infection. Our study revealed that CTLs play important roles in both the physiological processes and viral infection in mosquito vectors.

Investigating Enterocytozoon bieneusi in pigs farmed in Zhejiang Province, China: Occurrence, genotype identification, evolutionary analysis, and zoonotic risk assessment.

Enterocytozoon bieneusi is a widespread intracellular fungus that can infect both humans and animals, making it a significant zoonotic threat. In the current study, a total of 208 fecal samples were assayed to investigate the prevalence of E. bieneusi in pigs reared in Zhejiang Province, China. Employing polymerase chain reaction (PCR) amplification techniques specifically designed to target the internal transcribed spacer (ITS) region of the small subunit ribosomal RNA (rRNA) gene, the results revealed that 78 samples (37.5 %) tested positive for the presence of E. bieneusi. A total of 19 different genotypes of E. bieneusi were detected. Nine of these genotypes were already known: EbpC (n = 36), KIN-1 (n = 10), PigEbITS7 (n = 8), EbpA (n = 6), Henan III (n = 3), PigEbITS5 (n = 2), Henan-IV (n = 1), EbpD (n = 1), and TypeIV (n = 1), and 10 were novel: ZJP-I to ZJP-X (one each). The present investigation revealed that all the nine known genotypes identified in pigs here, have also been previously discovered in humans. Additionally, the novel genotypes of E. bieneusi discovered here were all classified as belonging to Group 1. These findings suggest the potential for cross-species transmission between humans and pigs.

Enterocytozoon bieneusi and Cryptosporidium bat genotype XXI and bat genotype XXII in fruit bats (Rousettus leschenaultii) inhabiting a tropical park in Hainan Province, China.

Bats stand as one of the most diverse groups in the animal kingdom and are key players in the global transmission of emerging pathogens. However, their role in transmitting Enterocytozoon bieneusi and Cryptosporidium spp. remains unclear. This study aimed to evaluate the occurrence and genetic diversity of the two pathogens in fruit bats (Rousettus leschenaultii) in Hainan, China. Ten fresh fecal specimens of fruit bats were collected from Wanlvyuan Gardens, Haikou, China. The fecal samples were tested for E. bieneusi and Cryptosporidium spp. using Polymerase Chain Reaction (PCR) analysis and sequencing the internal transcribed spacer (ITS) region and partial small subunit of ribosomal RNA (SSU rRNA) gene, respectively. Genetic heterogeneity across Cryptosporidium spp. isolates was assessed by sequencing 4 microsatellite/minisatellite loci (MS1, MS2, MS3, and MS16). The findings showed that out of the ten specimens analyzed, 2 (20 %) and seven (70.0 %) were tested positive for E. bieneusi and Cryptosporidium spp., respectively. DNA sequence analysis revealed the presence of two novel Cryptosporidium genotypes with 94.4 to 98.6 % sequence similarity to C. andersoni, named as Cryptosporidium bat-genotype-XXI and bat-genotype-XXII. Three novel sequences of MS1, MS2 and MS16 loci identified here had 95.4 to 96.9 % similarity to the known sequences, which were deposited in the GenBank. Two genotypes of E. bieneusi were identified, including a novel genotype named HNB-I and a zoonotic genotype PigEbITS7. The discovery of these novel sequences provides meaningful data for epidemiological studies of the both pathogens. Meanwhile our results are also presented that the fruit bats infected with E. bieneusi, but not with Cryptosporidium, should be considered potential public health threats.

Hax1 regulate focal adhesion dynamics through IQGAP1.

Cell migration is a highly orchestrated process requiring the coordination between the cytoskeleton, cell membrane and extracellular matrix adhesions. Our previous study demonstrated that Hax1 interacts with EB2, a microtubule end-binding protein, and this interaction regulate cell migration in keratinocytes. However, little is known about the underlying regulatory mechanism. Here, we show that Hax1 links dynamic focal adhesions to regulate cell migration via interacting with IQGAP1, a multidomain scaffolding protein, which was identified by affinity purification coupled with LC-MS/MS. Biochemical characterizations revealed that C-terminal region of Hax1 and RGCT domain of IQGAP1 are the most critical binding determinants for its interaction. IQGAP1/Hax1 interaction is essential for cell migration in MCF7 cells. Knockdown of HAX1 not only stabilizes focal adhesions, but also impairs the accumulation of IQGAP in focal adhesions. Further study indicates that this interaction is critical for maintaining efficient focal adhesion turnover. Perturbation of the IQGAP1/Hax1 interaction in vivo using a membrane-permeable TAT-RGCT peptide results in impaired focal adhesion turnover, thus leading to inhibition of directional cell migration. Together, our findings unravel a novel interaction between IQGAP1 and Hax1, suggesting that IQGAP1 association with Hax1 plays a significant role in focal adhesion turnover and directional cell migration. Video Abstract.

Association between SUMF1 polymorphisms and COVID-19 severity.

BACKGROUND: Evidence shows that genetic factors play important roles in the severity of coronavirus disease 2019 (COVID-19). Sulfatase modifying factor 1 (SUMF1) gene is involved in alveolar damage and systemic inflammatory response. Therefore, we speculate that it may play a key role in COVID-19. RESULTS: We found that rs794185 was significantly associated with COVID-19 severity in Chinese population, under the additive model after adjusting for gender and age (for C allele = 0.62, 95% CI = 0.44-0.88, P = 0.0073, logistic regression). And this association was consistent with this in European population Genetics Of Mortality In Critical Care (GenOMICC: OR for C allele = 0.94, 95% CI = 0.90-0.98, P = 0.0037). Additionally, we also revealed a remarkable association between rs794185 and the prothrombin activity (PTA) in subjects (P = 0.015, Generalized Linear Model). CONCLUSIONS: In conclusion, our study for the first time identified that rs794185 in SUMF1 gene was associated with the severity of COVID-19.

Molecular and expression characterization of insulin-like signaling in development and metabolism of Aedes albopictus.

BACKGROUND: Insulin-like signaling (IS) in insects is a conserved pathway that regulates development, reproduction and longevity. Insulin-like peptides (ILPs) activate the IS pathway by binding to the insulin receptor (InR) and trigger the ERK and AKT cascades. A varying number of ILPs were identified in Aedes aegypti mosquito and other insects. Aedes albopictus is an invasive mosquito which transmits dengue and Zika viruses worldwide. Until now, the molecular and expression characteristics of IS pathway in Ae. albopictus have not been investigated. METHODS: The orthologues of ILP in Ae. albopictus genome assembly was analyzed by using sequence blast. Phylogenetic analysis and molecular characterization were performed to identify the functional domains of ILPs. Quantitative analysis was performed to determine the expression characteristics of ILPs, InR as well as ERK and AKT in mosquito development and different tissues of female adults after blood-feeding. In addition, the knockdown of InR was achieved by feeding larvae with Escherichia coli-producing dsRNA to investigate the impact of IS pathway on mosquito development. RESULTS: We identified seven putative ILP genes in Ae. albopictus genome assembly, based on nucleotide similarity to the ILPs of Ae. aegypti and other insects. Bioinformatics and molecular analyses suggested that the ILPs contain the structural motif which is conserved in the insulin superfamily. Expression levels of ILPs, InR as well as ERK and AKT varied in Ae. albopictus development stages and between male and female adults. Quantitative analyses revealed that expression of ILP6, the putative orthologue of the insulin growth factor peptides, was highest in the midgut of female adults after blood-feeding. Knockdown of Ae. albopictus InR induces a significant decrease in the phosphorylation levels of ERK and AKT proteins and results in developmental delays and smaller body sizes. CONCLUSIONS: The IS pathway of Ae. albopictus mosquito contains ILP1-7, InR and ERK/AKT cascades, which exhibited different developmental and tissue expression characteristics. Feeding Ae. albopictus larvae with E. coli-producing InR dsRNA blocks the ERK and AKT cascades and interferes with the development of mosquito. Our data suggest that IS pathway plays an important role in the metabolism and developmental process and could represent a potential target for controlling mosquito-borne diseases.

Molecular-Based Detection of Enterocytozoon bieneusi in Farmed Masked Palm Civets (Paguma larvata) in Hainan, China: A High-Prevalence, Specificity, and Zoonotic Potential of ITS Genotypes.

Enterocytozoon bieneusi is a microsporidian and zoonotic species. This study investigated the prevalence and distribution of E. bieneusi genotypes in farmed masked palm civets using nested PCR, as well as assessed their zoonotic potential by phylogenetic analysis of the ITS region of the rRNA region. Here, we collected 251 fecal specimens from farmed masked palm civets (Paguma larvata) from the Hainan Island, China. In total, 128 of 251 samples were positive for E. bieneusi, with an average infection rate of 51.0%. Seventeen genotypes were identified including 12 known genotypes-HNR-VI (n = 56), SHR1 (n = 45), SHW7 (n = 6), KIN-1 (n = 3), D (n = 3), New1 (n = 3), EbpC (n = 2), CHC5 (n = 1), CHG19 (n = 1), CHN4 (n = 1), EbpA (n = 1), and Henan-III (n = 1)-and five novel genotypes (HNPL-I to HNPL-II; one each). Phylogenetic analysis categorized these genotypes into two groups. Thirteen of them were members of the zoonotic group 1, and the remaining four genotypes were in group 12. This study has shown that the infection rates of E. bieneusi in masked palm civets from Hainan were relatively high and provide baseline data to control and prevent microsporidiosis in farm-related communities. Therefore, infections in masked palm civets with zoonotic genotypes D, EbpC, CHN4, EbpA, KIN-1, and Henan-III should be considered potential threats to public health.

Frog Skin Derived Peptides With Potential Protective Effects on Ultraviolet B-Induced Cutaneous Photodamage.

Hyla annectans is a tree frog living in the southwestern plateau area of China where there is strong ultraviolet radiation and long duration of sunshine. So their naked skin may possess chemical defense components that protect it from acute photo-damage. However, no such peptide or components has been identified till to date. In the current work, two novel peptides (FW-1, FWPLI-NH2 and FW-2, FWPMI-NH2) were identified from the skin of the tree frog. Five copies of FW-1 and four copies of FW-2 are encoded by an identical gene and released from the same protein precursor, which possess 167 amino acid residues. FW-1 and -2 can exert significant anti-inflammatory functions by directly inhibiting Ultraviolet B irradiation (UVB)-induced secretion of inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). They may achieve this function by modulating the UV-induced stress signaling pathways such as Mitogen-activated protein kinases (MAPK) and Nuclear Factor Kappa B (NF-κB). Besides, FW-1 and -2 showed potential antioxidant effects on epidermis by attenuating the UVB-induced reactive oxygen species (ROS) production through an unknown mechanism. Considering small peptides' easy production, storage, and potential photo-protective activity, FW-1/2 might be exciting leading compounds or templates for the development of novel pharmacological agents for the suppression of UVB-induced skin inflammation. Moreover, this study might expand our knowledge on skin defensive mechanism of tree frog upon UVB irradiation.

The Ras/ERK signaling pathway couples antimicrobial peptides to mediate resistance to dengue virus in Aedes mosquitoes.

Aedes mosquitoes can transmit dengue and several other severe vector-borne viral diseases, thereby influencing millions of people worldwide. Insects primarily control and clear the viral infections via their innate immune systems. Mitogen-Activated Protein Kinases (MAPKs) and antimicrobial peptides (AMPs) are both evolutionarily conserved components of the innate immune systems. In this study, we investigated the role of MAPKs in Aedes mosquitoes following DENV infection by using genetic and pharmacological approaches. We demonstrated that knockdown of ERK, but not of JNK or p38, significantly enhances the viral replication in Aedes mosquito cells. The Ras/ERK signaling is activated in both the cells and midguts of Aedes mosquitoes following DENV infection, and thus plays a role in restricting the viral infection, as both genetic and pharmacological activation of the Ras/ERK pathway significantly decreases the viral titers. In contrast, inhibition of the Ras/ERK pathway enhances DENV infection. In addition, we identified a signaling crosstalk between the Ras/ERK pathway and DENV-induced AMPs in which defensin C participates in restricting DENV infection in Aedes mosquitoes. Our results reveal that the Ras/ERK signaling pathway couples AMPs to mediate the resistance of Aedes mosquitoes to DENV infection, which provides a new insight into understanding the crosstalk between MAPKs and AMPs in the innate immunity of mosquito vectors during the viral infection.

A novel Kunitz-type neurotoxin peptide identified from skin secretions of the frog Amolops loloensis.

A novel Kunitz-type neurotoxin peptide that inhibited voltage-gated sodium channel was purified and characterized from the skin secretions of rufous-spotted torrent frog, Amolops loloensis. It has a 240-bp cDNA encoding an 79-amino acid residue (aa) precursor protein containing 6 half-cysteines. The precursor was proven to release a 57-aa mature peptide with amino acid sequence, DRNPICNLPPKEGFCLWMMRRSFFNPSKGRCDTFGYRGCGGNKNNFETPRACKEACG. The mature was named amotoxin. Amotoxin shares sequence homology with other Kunitz-type toxins and also has three cysteine bridges. Amotoxin showed an inhibitory ability against trypsin with an inhibitory constant (Ki) of 0.087 µM. To the best of our knowledge, this is the first gene-encoded neurotoxin found in Amolops loloensis. Recombinant amotoxin showed similar functional properties as the native amotoxin. The functional properties of amotoxin may provide insights into the ecological adaptation of amphibians and deepen our understanding about the biological function spectrum of amphibian skin peptides.

Microarray analysis of long non-coding RNA expression profiles uncovers a Toxoplasma-induced negative regulation of host immune signaling.

BACKGROUND: Toxoplasma gondii is an obligate intracellular protozoan parasite that can infect mammalian cells and thereby regulate host gene expression. The long non-coding RNAs (lncRNAs) have been demonstrated to be an important class of RNA molecules that regulate many biological processes, including host-pathogen interactions. However, the role of host lncRNAs in the response to T. gondii infection remains largely unknown. METHODS: We applied a microarray approach to determine the differential expression profiles of both lncRNAs and mRNAs in the human foreskin fibroblast (HFF) cells after T. gondii infection. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to reveal the potential functions of T. gondii-induced genes. Based on the co-expression networks of lncRNAs and immune-related genes, the role of NONSHAT022487 on the regulation of UNC93B1 related immune signaling was investigated by the knockdown and over-expression of lncRNA in human macrophage derived from the PMA-induced promonocytic cell line THP-1. RESULTS: Our data showed that 996 lncRNAs and 109 mRNAs in HFF cells were significantly and differentially expressed following T. gondii infection (fold change ≥ 5, P < 0.05). The results from the GO and KEGG pathway analyses indicated that the mRNAs with differential expression were mainly involved in the host immune response. Remarkably, we identified a novel lncRNA, NONSHAT022487, which suppresses the expression of the immune-related molecule UNC93B1. After T. gondii infection, NONSHAT022487 impaired the secretion of the cytokines IL-12, TNF-α, IL-1ß and IFN-γ by downregulating UNC93B1 expression in human macrophage cells. CONCLUSIONS: Our study identified infection-induced lncRNA expression as a novel mechanism by which the Toxoplasma parasite regulates host immune signaling, which advances our understanding of the interaction of T. gondii parasites and host cells.

Plasmodium falciparum var Gene Is Activated by Its Antisense Long Noncoding RNA.

Plasmodium falciparum erythrocyte membrane protein 1, encoded by var gene, is an immunodominant antigen mediating immune evasion in humans. At a given time, only a single var gene is commonly expressed in one parasite. However, the regulation mechanism of var transcription remains largely unknown. In this study, we identified the antisense long non-coding RNA (aslncRNA) derived from var intron as an activation factor for the corresponding var gene. The exogenous artificial var aslncRNA transcribed by T7 RNA polymerase from episome can specifically activate the homologous var gene, and the exogenous aslncRNA activates transcription of both var mRNA and endogenous aslncRNA in a manner independent of the conserved intron sequence within the var gene family. Interestingly, the newly activated var gene and the previously dominant var gene then could be co-expressed in the same parasite nuclei, which suggests that the aslncRNA-mediated var gene activation could escape from the control of mutually exclusively expression of the var gene family. Together, our work shows that var aslncRNA is the activator responsible for var gene transcriptional regulation.

Angiostrongylus cantonensis daf-2 regulates dauer, longevity and stress in Caenorhabditis elegans.

The insulin-like signaling (IIS) pathway is considered to be significant in regulating fat metabolism, dauer formation, stress response and longevity in Caenorhabditis elegans. "Dauer hypothesis" indicates that similar IIS transduction mechanism regulates dauer development in free-living nematode C. elegans and the development of infective third-stage larvae (iL3) in parasitic nematodes, and this is bolstered by a few researches on structures and functions of the homologous genes in the IIS pathway cloned from several parasitic nematodes. In this study, we identified the insulin-like receptor encoding gene, Acan-daf-2, from the parasitic nematode Angiostrongylus cantonensis, and determined the genomic structures, transcripts and functions far more thorough in longevity, stress resistance and dauer formation. The sequence of Acan-DAF-2, consisting of 1413 amino acids, contained all of the characteristic domains of insulin-like receptors from other taxa. The expression patterns of Acan-daf-2 in the C. elegans surrogate system showed that pAcan-daf-2:gfp was only expressed in intestine, compared with the orthologue in C. elegans, Ce-daf-2 in both intestine and neurons. In addition to the similar genomic organization to Ce-daf-2, Acan-DAF-2 could also negatively regulate Ce-DAF-16A through nuclear/cytosolic translocation and partially restore the C. elegans daf-2(e1370) mutation in longevity, dauer formation and stress resistance. These findings provided further evidence of the functional conservation of DAF-2 between parasitic nematodes and the free-living nematode C. elegans, and might be significant in understanding the developmental biology of nematode parasites, particularly in the infective process and the host-specificity.

Comparative expression profile of microRNAs in Anopheles anthropophagus midgut after blood-feeding and Plasmodium infection.

BACKGROUND: Anopheles anthropophagus is one of the major vectors of malaria in Asia. MicroRNAs (miRNAs) play important roles in cell development and differentiation as well as in the cellular response to stress and infection. In a former study, we have investigated the global miRNA profiles in relation to sex in An. anthropophagus. However, the miRNAs contributing to the blood-feeding and infection with Plasmodium are still unknown. METHODS: High-throughput sequencing was performed to identify miRNA profiles of An. anthropophagus midguts after blood-feeding and Plasmodium infection. The expression patterns of miRNA in different midgut libraries were compared based on transcripts per million reads (TPM), and further confirmed by Northern blots. Target prediction and pathway analysis were carried out to investigate the role of regulated miRNAs in blood-feeding and Plasmodium infection. RESULTS: We identified 67 known and 21 novel miRNAs in all three libraries (sugar-feeding, blood-feeding and Plasmodium infection) in An. anthropophagus midguts. Comparing with the sugar-feeding, the experssion of nine (6 known and 3 novel) and ten (9 known and 1 novel) miRNAs were significantly upregulated and downregulated respectively after blood-feeding (P < 0.05, fold change ≥ 2 and TPM ≥ 10). Plasmodium infection induced the expression of thirteen (9 known and 4 novel) and eleven (9 known and 2 novel) miRNAs significantly upregulated and downregulated, respectively, compared with blood-feeding. The representative upregulated miR-92a in blood-feeding and downregulated miR-275 in Plasmodium infection were further confirmed by Northern Blot. Putative targets of these regulated miRNAs were further investigated and classified into their pathways. CONCLUSIONS: This study suggests that miRNAs are involved in the blood-feeding and Plasmodium infection in An. anthropophagus midgut. Further studies of the function of these differential expressed miRNAs will facilitate in better understanding of mosquito biology and anti-parasite immunity.

Alphavirus Replicon DNA Vectors Expressing Ebola GP and VP40 Antigens Induce Humoral and Cellular Immune Responses in Mice.

Ebola virus (EBOV) causes severe hemorrhagic fevers in humans, and no approved therapeutics or vaccine is currently available. Glycoprotein (GP) is the major protective antigen of EBOV, and can generate virus-like particles (VLPs) by co-expression with matrix protein (VP40). In this study, we constructed a recombinant Alphavirus Semliki Forest virus (SFV) replicon vector DREP to express EBOV GP and matrix viral protein (VP40). EBOV VLPs were successfully generated and achieved budding from 293 cells after co-transfection with DREP-based GP and VP40 vectors (DREP-GP+DREP-VP40). Vaccination of BALB/c mice with DREP-GP, DREP-VP40, or DREP-GP+DREP-VP40 vectors, followed by immediate electroporation resulted in a mixed IgG subclass production, which recognized EBOV GP and/or VP40 proteins. This vaccination regimen also led to the generation of both Th1 and Th2 cellular immune responses in mice. Notably, vaccination with DREP-GP and DREP-VP40, which produces both GP and VP40 antigens, induced a significantly higher level of anti-GP IgG2a antibody and increased IFN-γ secreting CD8+ T-cell responses relative to vaccination with DREP-GP or DREP-VP40 vector alone. Our study indicates that co-expression of GP and VP40 antigens based on the SFV replicon vector generates EBOV VLPs in vitro, and vaccination with recombinant DREP vectors containing GP and VP40 antigens induces Ebola antigen-specific humoral and cellular immune responses in mice. This novel approach provides a simple and efficient vaccine platform for Ebola disease prevention.

Structural and functional characterisation of FOXO/Acan-DAF-16 from the parasitic nematode Angiostrongylus cantonensis.

Fork head box transcription factors subfamily O (FoxO) is regarded to be significant in cell-cycle control, cell differentiation, ageing, stress response, apoptosis, tumour formation and DNA damage repair. In the free-living nematode Caenorhabditis elegans, the FoxO transcription factor is encoded by Ce-daf-16, which is negatively regulated by insulin-like signaling (IIS) and involved in promoting dauer formation through bringing about its hundreds of downstream genes expression. In nematode parasites, orthologues of daf-16 from several species have been identified, with functions in rescue of dauer phenotypes determined in a surrogate system C. elegans. In this study, we identified the FoxO encoding gene, Acan-daf-16, from the parasitic nematode Angiostrongylus cantonensis, and determined the genomic structures, transcripts and functions far more thorough in longevity, stress resistance and dauer formation. Acan-daf-16 encodes two proteins, Acan-DAF-16A and Acan-DAF-16B, consisting of 555 and 491 amino acids, respectively. Both isoforms possess the highly conserved fork head domains. Acan-daf-16A and Acan-daf-16B are expressed from distinct promoters. The expression patterns of Acan-daf-16 isoforms in the C. elegans surrogate system showed that p Acan-daf-16a:gfp was expressed in all cells of C. elegans, including the pharynx, and the expression of p Acan-daf-16b:gfp was restricted to the pharynx. In addition to the same genomic organization to the orthologue in C. elegans, Ce-daf-16, both Acan-DAF-16 isoforms could restore the C. elegans daf-16(mg54) mutation in longevity, dauer formation and stress resistance, in spite of the partial complementation of Acan-DAF-16B isoform in longevity. These findings provide further evidence of the functional conservation of DAF-16s between parasitic nematodes and the free-living nematode C. elegans.

Systematic identification of the lysine succinylation in the protozoan parasite Toxoplasma gondii.

Lysine succinylation is a new posttranslational modification identified in histone proteins of Toxoplasma gondii, an obligate intracellular parasite of the phylum Apicomplexa. However, very little is known about their scope and cellular distribution. Here, using LC-MS/MS to identify parasite peptides enriched by immunopurification with succinyl lysine antibody, we produced the first lysine succinylome in this parasite. Overall, a total of 425 lysine succinylation sites that occurred on 147 succinylated proteins were identified in extracellular Toxoplasma tachyzoites, which is a proliferative stage that results in acute toxoplasmosis. With the bioinformatics analysis, it is shown that these succinylated proteins are evolutionarily conserved and involved in a wide variety of cellular functions such as metabolism and epigenetic gene regulation and exhibit diverse subcellular localizations. Moreover, we defined five types of definitively conserved succinylation site motifs, and the results imply that lysine residue of a polypeptide with lysine on the +3 position and without lysine at the -1 to +2 position is a preferred substrate of lysine succinyltransferase. In conclusion, our findings suggest that lysine succinylation in Toxoplasma involves a diverse array of cellular functions, although the succinylation occurs at a low level.

[Preparation and antigenicity analysis of recombinant aegyptin-like protein of Aedes albopictus].

OBJECTIVE: To clone and express the aegyptin-like protein (alALP) encoding gene from Aedes albopictus salivary gland, and analyze its antigenicity. METHODS: The homology, secondary structure and antigen peptides of alALP and aegyptin protein (GenBank No. ABF18122.1) was analyzed by bioinformatics software tools. Total RNA was extracted from Ae. albopictus salivary gland. The coding region of alALP (GenBank No. AY826121) was amplified by PCR. RT-PCR product was digested with restriction enzyme and ligated into a pGEX-6P-1 vector. The recombinant pGEX-6P-1-alALP plasmid was transformed into E. coli BL21 and induced by IPTG. The recombinant soluble GST-alALP fusion protein was purified with Glutathione Sepharose 4B. The expression product was analyzed by SDS-PAGE and Western blotting. Mice were immunized each with 60 microg purified GST-alALP at every 2 weeks for 3 times, and mouse anti-GST-alALP serum was prepared. Western blotting assay with mice anti-GST-alALP serum and serum of mice exposed to Ae. albopictus bites was used to analyze its antigenicity. RESULTS: Bioinformatics prediction results showed that alALP and aegyptin had 65.58% homology with a similar secondary structure, and a conservative polypeptide. The product of RT-PCR was 762 bp. The recombinant plasmid pGEX-6P-1-alALP was confirmed by double restriction enzyme digestion, PCR and sequencing. SDS-PAGE and Western blotting analysis showed that the bacteria containing recombinant plasmid pGEX-6p-1-alALP expressed a soluble recombinant fusion protein (M(r) 56 000) after being induced with IPTG. Western blotting analysis revealed that GST-alALP protein was recognized by mouse anti-GST-alALP serum and serum of mice ex- posed to Ae. albopictus bites. CONCLUSION: Mature peptide gene of alALP can be expressed in prokaryotic expression system, and the recombinant protein shows antigenicity.

[Preparation and application of the polyclonal antibody of Toxoplasma gondii autophagy protein 8 (TgAtg8)].

OBJECTIVE: To prepare and evaluate specific-TgAtg8 polyclonal antibody. METHODS: The known Saccharomyces cerevisiae Atg protein sequences were used to identify Toxoplasma gondii homologous protein through bioinformatics analysis. TgAtg8 cDNA was amplified and cloned into prokaryotic expression vector pGEX-6p-1. The constructed pGEX-6p-1-TgAtg8 was transformed into E. coli BL21 cells and induced with IPTG for expression. The expression product was analyzed through SDS-PAGE and Western blotting. The recombinant TgAtg8 protein with an N-terminal glutathione-S transferase tag was used to immunize rabbits and raise specific polyclonal antibody against TgAtg8. Subsequently, the antibody was applied for Western blotting and IFA assay. RESULTS: Recombinant expression plasmid of pGEX-6p-1-TgAtg8 was confirmed correct by restriction enzyme digestion and sequencing. SDS-PAGE and Western blotting analysis showed that the recombinant TgAtg8 protein with the predicted molecular weight (M(r)40000) was expressed highly in E. coli BL21. After immunization, the specific antibodies against TgAtg8 protein were produced. The anti-TgAtg8 polyclonal antibody reacted specifically with TgAtg8 fusion protein or endogenous TgAtg8. Importantly, IFA assay determined that the TgAtg8 signal was generally distributed throughout the cytoplasm of the tachyzoites. However, the green fluorescence signal gathered into one or more green spots after induction of autophagy. CONCLUSION: The specific polyclonal antibody against TgAtg8 could be used to observe the dynamics of autophagosome formation in T. gondii, which is useful tool to investigate the autophagic machinery in this parasite.