kDa Polypeptide Research Articles

Analysis of virulence factors in extracellular vesicles secreted by Naegleria fowleri

Naegleria fowleri is the etiological agent of primary amebic meningoencephalitis (PAM), a rapidly progressive acute and fulminant infection that affects the central nervous system, particularly of children and young adults, which has a mortality rate greater than 95%, and its symptomatologic similarity with other meningitis caused by virus or bacteria makes it difficult to make a quick and timely diagnosis that prevents the progression of the infection. It is necessary to know the antigenic determinants as well as the pathogenicity mechanisms of this amoeba to implement strategies that allow for better antiamoebic therapeutic and diagnostic targets that directly impact the health sector. Therefore, the aim of this work was to analyze some virulence factors as part of extracellular vesicle (EV) cargo secreted by N. fowleri. The EV secretion to the extracellular medium was evaluated in trophozoites fixed and incubated with anti-N. fowleri antibody while molecular identification of EV cargo was performed by SDS-PAGE, Western blot, and RT-PCR. Our results showed that N. fowleri secretes a wide variety of vesicle sizes ranging from 0.2 to > 2 μm, and these EVs were recognized by antibodies anti-Naegleropore B, anti-19 kDa polypeptide band, anti-membrane protein Mp2CL5, anti-protease cathepsin B, and anti-actin. Furthermore, these vesicles were localized in the trophozoites cytoplasm or secreted into the extracellular medium. Specifically in relation to small vesicles, our purified exosomes were recognized by CD63 and Hsp70 markers, along with the previously mentioned proteins. RT-PCR analysis was made through the isolation of EVs from N. fowleri trophozoite culture by concentration, filtration, and ultracentrifugation. Interestingly, we obtained PCR products for Nfa1, NPB, Mp2CL5, and CatB genes as part of exosomes cargo. This suggests that the molecules identified in this work could play an important role in communication as well as in infectious processes caused by this amoeba. Therefore, the study and characterization of the pathogenicity mechanisms, as well as the virulence factors released by N. fowleri remains a key point to provide valuable information for the development of therapeutic treatments, vaccine design, or biomarkers for a timely diagnosis against infections caused by protozoa.

Heterologous expression and purification of glutamate decarboxylase-1 from the model plant Arabidopsis thaliana: Characterization of the enzyme's in vitro truncation by thiol endopeptidase activity

Plant glutamate decarboxylase (GAD) is a Ca2+-calmodulin (CaM) activated enzyme that produces γ-aminobutyrate (GABA) as the first committed step of the GABA shunt. Our prior research established that in vivo phosphorylation of AtGAD1 (AT5G17330) occurs at multiple N-terminal serine residues following Pi resupply to Pi-starved cell cultures of the model plant Arabidopsis thaliana. The aim of the current investigation was to purify recombinant AtGAD1 (rAtGAD1) following its expression in Escherichia coli to facilitate studies of the impact of phosphorylation on its kinetic properties. However, in vitro proteolytic truncation of an approximate 5 kDa polypeptide from the C-terminus of 59 kDa rAtGAD1 subunits occurred during purification. Immunoblotting demonstrated that most protease inhibitors or cocktails that we tested were ineffective in suppressing this partial rAtGAD1 proteolysis. Although the thiol modifiers N-ethylmaleimide or 2,2-dipyridyl disulfide negated rAtGAD1 proteolysis, they also abolished its GAD activity. This indicates that an essential -SH group is needed for catalysis, and that rAtGAD1 is susceptible to partial degradation either by an E. coli cysteine endopeptidase, or possibly via autoproteolytic activity. The inclusion of exogenous Ca2+/CaM facilitated the purification of non-proteolyzed rAtGAD1 to a specific activity of 27 (μmol GABA produced/mg) at optimal pH 5.8, while exhibiting an approximate 3-fold activation by Ca2+/CaM at pH 7.3. By contrast, the purified partially proteolyzed rAtGAD1 was >40 % less active at both pH values, and only activated 2-fold by Ca2+/CaM at pH 7.3. These results emphasize the need to diagnose and prevent partial proteolysis before conducting kinetic studies of purified regulatory enzymes.

Isolation and Characterization of Submitochondrial Reticulum Complex Associated with Midpiece of Bovine Cauda Epididymal Sperm

The mitochondrial sheath of mammalian spermatozoa adheres to an underlying organized network of electron-dense material termed the submitochondrial reticulum (SMR). The objective of the present study is to characterize the structural components of the SMR. We have isolated SMR fractions from midpieces of bovine cauda sperm. SDS-PAGE of SMR fractions revealed four major polypeptides of 56kDa, 54kDa, 34kDa, and 31kDa. Proteomic analyses of the four polypeptides revealed that 56kDa and 54kDa polypeptides identified as glycerol kinase and 34kDa and 31kDa polypeptide identified as VDAC2 and VDAC3, respectively (Voltage-Dependent Anion-Selective Channel Protein 2/3). Western blots of midpiece stained with anti-56kDa, anti-54KDa, anti-34kDaVDAC2, and anti-31kDaVDAC3 antibodies demonstrated the presence of 56kDa, 54kDa, 34kDa, and 31kDa immunoreactive bands, respectively. Four polypeptides are localized to midpiece. Glycerol kinase activity was quantitively assayed in tails. We proposed that glycerol kinase and VDAC2/VDAC 3 polypeptides play an important role in sperm motility and in midpiece function.

Gel properties and in vitro digestion of sea bass (Lateolabrax japonicus) myofibrillar protein – Lipid composite gels: Focus on lipid type and content

The effects of lipid type and content on gel and digestion properties of myofibrillar proteins (MPs) were studied. The MPs sol was combined with three types of lipid (peanut oil, sunflower oil, and lard) with different contents (0.5–2%) to obtain composite gels. As for whiteness, no differ was observed in composite gels without or with lipid addition. The water holding capacity and hardness of composite gels with lipid addition increased. Moreover, fourier transform infrared spectra (FTIR) demonstrated composite gels with 1% emulsion addition exhibited the highest β-sheet content. The confocal laser scanning microscope (CLSM) revealed that networks of composite gels with 1% emulsion addition possessed more densely compared to control group. During the in vitro digestion, high performance liquid chromatography (HPLC) results showed the peptide (>10 kDa) contents of composite gels with lipid addition were lower than that of control group under the simulated gastric phase. Moreover, the 2–5 kDa polypeptide content of composite gels with lipid addition was higher than that in observed in control group under intestinal phase. The results illustrated the gel and in vitro digestion mechanism of composite gels with lipid addition, which can be valuable for the fabrication of functional surimi products.

Development of an in vitro aggregation assay for long synthetic polypeptide, amyloidogenic gelsolin fragment AGelD187N 173-242.

Aggregation of the gelsolin protein fragment is the hallmark of the hereditary systemic disease gelsolin amyloidosis. As with other protein misfolding diseases, there is an urgent need for efficient disease-modifying treatment for gelsolin amyloidosis. The formation of amyloids can be reproduced by incubating the disease-causing amyloidogenic 8 kDa polypeptide, 70-residue gelsolin protein fragment, AGelD187N 173-242, in vitro and monitoring the process by thioflavin T dye. However, for screening of potential aggregation inhibitors, the required protein amounts are large and the biotechnological production of amyloidogenic proteins has many challenges. Conversely, use of shorter synthetic regions of AGelD187N 173-242 does not mimic the in vivo aggregation kinetics of full-length fragment as they have different aggregation propensity. In this study, we present an in vitro aggregation assay for full-length AGelD187N 173-242 that has been produced by solid-phase chemical synthesis and after that monomerized carefully. Chemical synthesis allows us to produce high quantities of full-length fragment efficiently and at low cost. We demonstrate that the generated aggregates are fibrillar in nature and how the purity, terminal modification, initial aggregates and seeding affect the aggregation kinetics of a synthetic gelsolin fragment. We also present sufficient quality criteria for the initial monomerized synthetic polypeptide.

Drought stress alleviation through nutrient management in Cyamopsis tetrogonoloba L.

Drought is one of the most serious issues since it reduces plant development and, as a result, yield significantly. This research is an attempt to provide an organic solution to combat the global issue of plant stress due to drought. To reduce the impact of drought on Cyamopsis tetragonoloba, the traditional preparation Panchagavya was used, and its effects on growth, photosynthetic and non-photosynthetic pigment synthesis, thylakoid protein composition, antioxidant activity, anatomy, and yield were investigated. Initially, drought had a negative effect on plant growth and other activities; however, as the duration of the treatment increased, the effect of drought decreased significantly. The plants that were under drought stress and were provided with nutrients, showed more plant growth and yield. Flavonoid and anthocyanin production was 50% higher in the plants under drought stress with nutrient supplementation than in the plants under drought stress and the control plants. The accumulation of 55, 47, 33, 27, and 20 kDa polypeptides of thylakoid protein also increased under nutrient conditions. Drought stress reduced overall fruit output by 10% relative to the control group (well irrigate plants). Nutrition management increased plant performance under stress conditions. Fresh & dry pod weights of control, drought stress, and drought with nutrients were recorded at 3.2 g & 0.6 g, 3 g & 0.52 g, and 4.5 g & 1.2 g, respectively. Under drought stress with nutrients, plants had more stomata per unit than control plants. This is the first study in which Panchagavya was used to alleviate drought. With the addition of beneficial nutrients, water use efficiency can be improved, and drought's negative impacts can be mitigated tangentially by activating plant physiological, biochemical, and metabolic processes. This study will add the crucial information required to determine the response of plants under drought stress conditions as well as how to alleviate its effects in a traditional organic way.

Epitope specific antibodies to N- and C cytoplasmic domains of the Plasmodium falciparum chloroquine resistance transporter (PfCRT) differentiate native and post-translationally modified variant

Polymorphisms in Plasmodium falciparum chloroquine resistance transporter (or PfCRT) were shown to be causative of decreased sensitivity to diverse quinoline-based antimalarials. In this report we describe the identification of a post-translational variant of PfCRT using highly characterized antibodies raised against its N- and C-terminal cytoplasmic domains (e.g., 58 and 26 amino acids, respectively). Western blot analyses of P. falciparum protein extracts with anti N-PfCRT antiserum revealed two polypeptides with apparent molecular masses of 52 kDa and 42 kDa, relative to the calculated molecular mass of PfCRT of 48.7 kDa. The 52 kDa polypeptide was detectable with anti C-PfCRT antiserum, only after alkaline phosphatase treatment of P. falciparum extracts. Detailed epitope mapping of anti N- and C-PfCRT antisera revealed epitopes covering two previously identified phosphorylation sites, Ser411 and Thr416, whereby substitution of these residues with Asp amino acid, to mimic phosphorylated residues, dramatically inhibited anti C-PfCRT binding. Consistently, alkaline phosphatase treatment of P. falciparum extract unmasked the binding of anti C-PfCRT to the 52 kDa polypeptide, suggesting that the 52 kDa but not 42 kDa polypeptide is phosphorylated at its C-terminal Ser411 and Thr416. Interestingly, Pfcrt expressed in HEK-293F human kidney cells showed the same reactive polypeptides with anti N- and C-PfCRT antisera, consistent with PfCRT origin of the two polypeptides (e.g., 42 kDa and 52 kDa), but lacking PfCRT phosphorylation at its C-terminal. Immunohistochemical staining of late trophozoite-infected erythrocytes with anti N-or C-PfCRT antisera showed both polypeptides are localized to the parasite's digestive vacuole. Moreover, both polypeptides are detected in chloroquine-susceptible and -resistant strains of P. falciparum. This is the first report describing a post-translationally modified variant of PfCRT. The physiologic role of the 52 kDa phosphorylated PfCRT in P. falciparum remains to be determined.

Biological and Immunological Characterization of a Functional L-HN Derivative of Botulinum Neurotoxin Serotype F.

Botulinum neurotoxins (BoNTs) can cause nerve paralysis syndrome in mammals and other vertebrates. BoNTs are the most toxic biotoxins known and are classified as Class A biological warfare agents. BoNTs are mainly divided into seven serotypes A-G and new neurotoxins BoNT/H and BoNT/X, which have similar functions. BoNT proteins are 150 kDa polypeptide consisting of two chains and three domains: the light chain (L, catalytic domain, 50 kDa) and the heavy chain (H, 100 kDa), which can be divided into an N-terminal membrane translocation domain (HN, 50 kDa) and a C-terminal receptor binding domain (Hc, 50 kDa). In current study, we explored the immunoprotective efficacy of each functional molecule of BoNT/F and the biological characteristics of the light chain-heavy N-terminal domain (FL-HN). The two structure forms of FL-HN (i.e., FL-HN-SC: single chain FL-HN and FL-HN-DC: di-chain FL-HN) were developed and identified. FL-HN-SC could cleave the vesicle associated membrane protein 2 (VAMP2) substrate protein in vitro as FL-HN-DC or FL. While only FL-HN-DC had neurotoxicity and could enter neuro-2a cells to cleave VAMP2. Our results showed that the FL-HN-SC had a better immune protection effect than the Hc of BoNT/F (FHc), which indicated that L-HN-SC, as an antigen, provided the strongest protective effects against BoNT/F among all the tested functional molecules. Further in-depth research on the different molecular forms of FL-HN suggested that there were some important antibody epitopes at the L-HN junction of BoNT/F. Thus, FL-HN-SC could be used as a subunit vaccine to replace the FHc subunit vaccine and/or toxoid vaccine, and to develop antibody immune molecules targeting L and HN domains rather than the FHc domain. FL-HN-DC could be used as a new functional molecule to evaluate and explore the structure and activity of toxin molecules. Further exploration of the biological activity and molecular mechanism of the functional FL-HN or BoNT/F is warranted.

Transcriptional analysis in bacteriophage Fc02 of Pseudomonas aeruginosa revealed two overlapping genes with exclusion activity.

Little is known about the gene expression program during the transition from lysogenic to lytic cycles of temperate bacteriophages in Pseudomonas aeruginosa. To investigate this issue, we developed a thermo-sensitive repressor mutant in a lysogen and analyzed the phage transcriptional program by strand-specific RNA-Seq before and after thermo-induction. As expected, the repressor gene located on the phage DNA forward strand is transcribed in the lysogen at the permissive temperature of 30°C. Upstream the repressor gene, we noticed the presence of two overlapped ORFs apparently in the same transcript. One ORF is a gene that encodes a protein of 7.9 kDa mediating the exclusion of various super-infecting phages. The other ORF, placed in an alternate reading frame with a possible AUG initiation codon at 25 nucleotide downstream of the AUG of the first gene, is expected to encode a 20.7 kDa polypeptide of yet an unknown function. Upon lifting repression at 40°C, the transcription of an operon which is involved in the lytic cycle is started from a promoter on the reverse phage DNA strand. The first gene in the operon is a homolog of the antirepresor ner, a common gene in the lysis-lysogeny regulation region of other phages. Interestingly, the next gene after ner is gene 10 that on the reverse strand overlaps the overlapped gene olg1 on the forward strand. Curiously, gene 10 expression also shows superinfection exclusion. Strand-specific RNA-Seq also has uncovered the transcription succession of gene modules expressed during the phage lytic stage. The conservation of overlapped genes with similar functions may be evolutionarily selected.

Fibrinogen-Related Protein, Fgl2, of Hamster Cauda Epididymal Fluid: Enzymatic Characterization, and Identification of Fgl2-Binding Proteins and Ligand of Defective Hamster Sperm Organelles.

The luminal environment of the mammalian epididymidis performs a dual function; sperm maturation and maintaining sperm viability. We previously identified a secretory protein (260/280KDa oligomers) of hamster cauda epididymal principal cells that binds to nonviable sperm. The 260/280KDa oligomers are composed of 64kDa FGL2 (fibrinogen-like protein-2) and 33kDa FGL1) (fibrinogen-like protein-1). The potential mechanism by which FGL2 binds to degenerative sperm is not clearly demonstrated. In this study, we report the downstream sequence of prothrombinase activity of FGL2, the identification of organelles, and characterize candidate proteins that bind FGL2. The following reaction sequence confirms that FGL2 is a phospholipid-activated serine protease; the conversion of prothrombin to thrombin by FGL2, followed by the conversion of soluble fibrinogen to insoluble fibrin polymers by thrombin. FGL2 binds intensely to tails than heads of de-membranated sperm. A spectrum of polypeptides of cauda sperm tails binds to FGL2. Proteomic analyses of 65KDa, 16kDa, and 13kDa polypeptides of tails correspond to a-Kinase anchor protein 4, glutathione peroxidase 4, and cytochrome c oxidase subunit 4, respectively. Annexin V, a calcium-dependent phosphatidylserine-binding protein localized to the flagellum and co-precipitated with FGL2. We have demonstrated a novel protective mechanism for recognizing and eliminating defective spermatozoa from viable sperm population.

Characterization of proteases from Irpex lacteus grown on minimally denatured soybean meal.

Acid and thermal stabilities are important properties for the preparation of acidic protein beverage. It is an important method for enzymatic modification to improve the functional properties of protein. Irpex lacteus protease showed a selective hydrolysis to soy proteins. The purpose of this study was to investigate the mechanism of enzymatic hydrolysis and its effects on acid and thermal stabilities of soy proteins. The I.lacteus protease selectively hydrolyzed the α and α' subunits of the native soybean β-conglycinin (7S globulin) to produce products that presented as the 55 kDa band upon sodium dodecyl sulfate polyacrylamide gel electrophoresis. The amino acid sequences of 55 kDa polypeptides were analyzed in gel multi-enzyme digestion followed by liquid chromatography-mass spectrometry. By matching the multi-enzyme digestion peptides with the published polypeptide chain sequences of the α and α' subunits, it was confirmed that the 55 kDa polypeptides were formed by eliminating amino acid residues on both sides of the N- and C-terminals. From the published protein structure database (https://www.uniprot.org/), it is known that the cleaved peptide bonds were in extension regions. Non-selective enzyme hydrolysis of both β-conglycinin (7S globulin) and glycinin (11S globulin), with corresponding drastic increases in the degree of hydrolysis, was observed when the substrates were preheated to the denaturation degree of 40% and above. However, 55 kDa hydrolyzed products and B polypeptides showed some extent of resistance to the proteolysis by I.lacteus protease even if denaturation degree was 100%. Both selective and non-selective hydrolysis of soy proteins by I.lacteus protease improved the acid and heat stabilities under the same hydrolysis conditions (enzyme/substrate ratio, time, and temperature). Enzymatic hydrolysis of soybean proteins by the I.lacteus protease can effectively improve the acid and thermal stabilities of proteins. This discovery is significant to avoid aggregation during processing in the beverage industry. In the near future, the protease has potential application value for modification of other proteins. © 2022 Society of Chemical Industry.

A ferritin gene in the marine copepod Acartia tonsa as a highly sensitive biomonitor for nano-contamination

Toxicology is not only for eco-risk assessments, but also for the real-time environmental monitoring based on the quick response of specific biomarkers. Ferritin gene (ftn) is a potential biomarker involving in crucial protective responses in biota. However, little information is available concerning the ftn in marine copepod Acartia tonsa (A. tonsa), a model organism widely applied in toxicology assessments. Our study for the first time identified and characterized the ftn in A. tonsa, along with its time-dependent transcriptional response to the reproductive toxicity of two newly emerged nanomaterials. The full-length cDNA of ftn contains a 114-bp 5′-untranslated region (UTR), a 236-bp 3′-untranslated region, and a 510-bp open reading frame which encodes an 18.51 kDa polypeptide composed of 169 amino acids. The ftn sequence has an iron binding signature and a potential phosphorylation site, which is closely-related to the ftn of Calanus sinicus and Pseudodiaptomus annandalei genes at the phylogenetical level. The ftn showed a quick and highly sensitive response to nanomaterial exposures, even at no observed effect concentrations. In detail, after exposure to nickel nanomaterials (up to 17.0 mg/L), the ftn was significantly upregulated immediately at 0.5 h and peaked at 9.5-fold in adults within 48 h, along with a significant reduction of egg hatching rate. When exposed to CdSe/ZnS quantum dots (up to 135 mg/L), no significant change in egg productions or hatching rates was observed, while the expression of ftn still significantly increased to over 3.0-fold in the initial 48 h. After that, the upregulation of ftn induced by CdSe/ZnS quantum dots or nickel nanoparticles both gradually returned back within 96 h. These findings demonstrate the highly sensitive response of this new cloned ftn to nanomaterial exposures, and highlight the suitability of ftn in A. tonsa as a promising biomonitor for nano-contamination in marine environments.

Seroprevalence of Fasciola-infection using Enzyme-linked immunosorbent assay in large ruminants from Pakistan

Fasciolosis, caused by liver fluke species of the genus Fasciola, are well recognized because of its high veterinary impact. Stool examination for Fasciola eggs is not a sensitive method, and limited efforts to find a reliable and cheaper means of detection are available. The present study aimed to develop rapid diagnostic ELISA test against fasciolosis. The excretory/secretory (ES) and somatic (SA) products of Fasciola helminths were analysed using polyacrylamide gel electrophoresis (PAGE). Immunogenicity was evaluated by immunoblotting using hyperimmune sera raised in rabbits and seroprevalence was determined by indirect ELISA. The results of SA antigen of Fasciola species showed polypeptide bands ranged from 10kDa-100kDa, while ES antigen of Fasciola showed bands of 15kDa-55kDa. The immunoblotting results showed the most prominent bands against ES antibodies were 25, 35, 55-70, 100 and 250 kDa and SA antigens showed 10, 15-25, 35, 70, 100 and 250 kDa polypeptide bands. The sensitivity and specificity of developed indirect ELISA for SA antigens was 95.45% and 87.1%, while for ES antigens was 100% and 77.42% respectively. The overall seroprevalence recorded for fascioliasis based on SA antigen was 39.8% and 29.8% for ES antigen. The fasciolosis did not show significant association with host type, sex and age groups of examined animals, however significantly higher infection was found in months of September and October. The result provides sensitive in house immunodetection assay for diagnosis of fasciolosis alternative to commercial kits with high import cost.

Role of HSP and Leptin in Dairy Animals during Thermal Stress: A Review

Thermal stress is a unique and complex process which alters the normal physiological mechanisms. Heat shock proteins (HSPs) are known to be highly conserved and ubiquitous proteins synthesized in response to several stimuli. The HSP inducers have been categorized as environmental (heat shock, UV radiation, heavy metals, amino acids, oxidative stress, etc.) pathological (bacterial or parasitic infections, fever, inflammation, etc.) and physiological (growth factors, cell differentiation, hormonal stimulation or tissue development, caloric restriction, etc.). The HSPs play an important role for maintaining cellular functioning under environmental challenges and protein denaturation conditions. There is a great potential for using HSP72 expression to detect natural adaptation and exposure to stress in natural populations. Leptin is a 16 kDa polypeptide hormone secreted primarily from the cells of white adipose tissue. Leptin acts through both central and peripheral mechanisms to affect feeding behaviour, lipid and glucose metabolism, thermogenesis, reproductive and endocrine functions. Leptin also plays an important role in the regulation of body weight and composition, e.g. reduction in feed intake and increase in energy expenditure. Bovine lymphocytes express Ob-Rb gene (leptin receptor) and also express leptin. There are ample information on the central role of leptin in brain and neural tissue regulation. In dairy cattle, the increase in milk yield has been associated with a negative energy balance and a decrease in fertility during early lactation. The hormone leptin is involved in regulation of nutritional status and reproductive function.

Overexpression, biochemical characterization, and anticancer activates of L-asparaginase from Bacillus subtilis

L-asparaginases convert L-asparagine into L-aspartate and ammonia. The L-asparaginase from Bacillus subtilis was cloned and expressed in the E. coli strain BL21(DE3)pLysS in the current study. Using glutathione sepharose 4B column chromatography, the L-asparaginase enzyme was uniformly purified 173.34 times, with a final specific activity of 1769.13 IU/mg protein and a yield of 56.14%. The isolated enzyme was identified as a 36 kDa polypeptide chain by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The immobilized enzyme was placed on top of the Ca alginate beads. The immobilized enzyme is quite stable and retains the majority of its activity at 4 °C (74 percent). The enzymatic and structural characteristics of free and immobilized recombinant L-asparaginase were studied. The activity of the free enzyme peaked after 30 min of incubation at pH 8.0 and 45 °C. After 30 minutes at 50 °C, the immobilized enzyme showed its peak activity at a pH of 8.5. The refined enzyme's amino acid makeup was identified. An enzyme that heals leukemia, Bacillus subtilis L-asparaginase, can be successfully mass-produced using this technique.

Vaccinia virus H7-protein is required for the organization of the viral scaffold protein into hexamers

Viruses of the giant virus family are characterized by a structurally conserved scaffold-capsid protein that shapes the icosahedral virion. The vaccinia virus (VACV) scaffold protein D13, however, transiently shapes the newly assembled viral membrane in to a sphere and is absent from the mature brick-shaped virion. In infected cells D13, a 62 kDa polypeptide, forms trimers that arrange in hexamers and a honey-comb like lattice. Membrane association of the D13-lattice may be mediated by A17, an abundant 21 kDa viral membrane protein. Whether membrane binding mediates the formation of the honey-comb lattice or if other factors are involved, remains elusive. Here we show that H7, a 17 kDa protein conserved among poxviruses, mediates proper formation of D13-hexamers, and hence the honey comb lattice and spherical immature virus. Without H7 synthesis D13 trimers assemble into a large 3D network rather than the typical well organized scaffold layer observed in wild-type infection, composed of short D13 tubes of discrete length that are tightly associated with the endoplasmic reticulum (ER). The data show an unexpected role for H7 in D13 organization and imply that formation of the honey-comb, hexagonal, lattice is essential for VACV membrane assembly and production of infectious progeny. The data are discussed with respect to scaffold proteins of other giant viruses.

MO443: Accumulation of REG-1Α in Proximal Tubules of a Rat Model of Chronic Kidney Disease: A New Biomarker at the Interface Between Renal Impairment and Neurodegenerative Diseases

Abstract BACKGROUND AND AIMS Chronic kidney disease (CKD) increases the risk of developing cognitive dysfunction and it has been identified as a modifiable risk factor for Alzheimer's disease (AD) [1]. Regenerating family member 1 alpha (Reg-1α) protein, originally identified as a 16 kDa polypeptide in the pancreas, is increased in cerebrospinal fluid (CSF) and in neurons of AD patients [2, 3]. Reg-1α is also elevated in blood in inflammatory conditions and chronic illnesses such as diabetes and interestingly, in patients with renal function impairment [4, 5]. It is not known whether Reg-1α is synthesized in the kidney or the modifications observed in CKD are merely due to a decline in the glomerular filtration rate. The aim of our study was to localize and quantify the Reg-1α protein in the kidneys of normal rats or CKD rats (5/6 nephrectomized rats) and determine, in a second time, if serum Reg-1α level is a suitable marker for assessment of renal function. As Reg-1a is able to cross the altered blood-brain barrier, it might be a new interesting biomarker at the interface between renal impairment and neurodegenerative diseases. METHOD A total of 16 3-month-old rats were randomly allocated to 5/6 nephrectomy (Nx) or Sham operation. Three months after surgery, serum creatinine and urea, systolic blood pressure (SBP) were measured and renal fibrosis (Sirius Red) was quantified. The expression of Reg-1α was evaluated by double-immunofluorescence using anti-Reg-1α and anti-Aquaporin-1 (Aqp-1) (as a proximal tubule marker) antibodies to determine the localization of Reg-1α in the kidney. RESULTS 5/6Nx rats showed increased serum creatinine levels (97.3 ± 17.6 versus Sham 26.3 ± 0.8 µmol/L; P < 0.05) and serum urea levels (23.9 ± 8.9 versus Sham 4.7 ± 0.1 mmol/L). They also had a higher SBP (158 ± 12 versus Sham 133 ± 5 mmHg) and renal fibrosis increased in the 5/6Nx group (8.1 ± 1.5 versus Sham 2.7 ± 0.2% staining). The double-immunofluorescence revealed an increased expression of Reg-1α of 5/6Nx rats compared with the Sham group. This expression seemed to be specific to the cytoplasm of the proximal tubules, with a ring-shaped distribution (preliminary results, Figure 1). CONCLUSION Our data show, for the first time, a proximal tubule-specific accumulation in Reg-1α in CKD suggesting an influence of impaired renal function on Reg-1α accumulation. Further assessment of Reg-1a in the blood, the blood-brain barrier and neuroinflammation status in this model is needed to better understand the potential effect of kidney accumulation of Reg-1α on brain dysfunction. Should this effect be confirmed, Reg-1α would be a new actor involved in the kidney-brain dialogue.

Structure and immunoreactivity of purified Siberian apricot (Prunus sibirica L.) kernel allergen under high hydrostatic pressure treatment

In the present study, the allergen in Siberian apricot (Prunus sibirica L.) kernel (SAK) was extracted, purified, and identified. The effect of high-pressure processing on the physiochemical property, structure, as well as the allergenicity of the allergen were determined. The changes in the molecular morphology and secondary structure of Siberian apricot kernels allergen (SAKA) after high hydrostatic pressure (HHP) processing were analyzed using atomic force microscopy and circular dichroism respectively. The immunoreactivity was evaluated by western blotting and indirect-binding enzyme-linked immunosorbent assays. Our result showed that after HHP processing, the intensity of a 40 kDa polypeptide band in SAKA was decreased. The immunoreactivity of SAKA was reduced to 72.74% ± 1.09% after high pressure processing at 500 MPa for 900 s. The results of this study may provide important implications for identification of apricot kernel allergen as well as the development of apricot kernels foods and beverages with low level of allergenicity.

Diagnostic potential of 36-55 kDa somatic antigens of Fasciola gigantica for bovine fasciolosis

Fascioliasis causes huge economic losses in livestock industry by reducing the growth, fertility rate, meat and milk yield. In the present study, somatic antigens isolated from Fasciola gigantica were assessed for the early detection of infection by developing antibody detection enzyme immunoassay. The somatic antigens extracted from adult F. gigantica worms was separated on SDS-PAGE and immunogenicity was determined by Western blot (WB). The results showed polypeptides bands between 15 to 95 kDa, and most prominent bands were 15, 28, 36, 38, 55, 72 and 95 kDa polypeptides. The WB revealed a single polypeptide of size between 36 to 55 kDa as antigenic. The sensitivity and specificity of ELISA test established for 36 to 55 kDa somatic antigens was 95.45% (95% CI: 77.16% to 99.88%) and 87.1% (95% CI: 70.17% to 96.37%), respectively. Kappa value revealed that the strength of agreement is considered to be very ‘good’. In house established ELISA was implemented in the field and 12.1% (31/256) large ruminants were found positive, while 4.68% (12/256) with postmortem examination. The fasciolosis did not show significant (P>0.05) association with host type, breed and age groups, while significant (P<0.01) association with host sexes. The result confirmed that in-house established ELISA test had good value for serodiagnosis of fasciolosis in cattle and buffaloes for large scale epidemiological studies.

A peroxidase purified from cowpea roots possesses high thermal stability and displays antifungal activity against Colletotrichum gloeosporioides and Fusarium oxysporum

Plants encode specific class III peroxidases (POX) as large multigene families that are involved in lignification, cell elongation, stress defense, and seed germination. However, many functions associated with these plant enzymes are not fully understood. Here, a class III peroxidase (Vu-RPOX) was purified from cowpea (Vigna unguiculata) roots with 0–90% ammonium sulfate precipitation, chitin column and Resource Q anion-exchange chromatography. Vu-RPOX is a glycoprotein composed by a 58 kDa polypeptide chain and pI of 3.79. Two peptide sequences of Vu-RPOX (RGLDVVNDIKT and RCSTFINRL) generated by Nano ESI-Q-TOF MS/MS analysis showed variable identity with seed coat peroxidase of Glycine max, peroxidase E5 of Vigna radiata, hypothetical peroxidase of Phaseolus vulgaris, and peroxidase E5-like of Vigna unguiculata. Vu-RPOX follows the Michaelis-Menten kinetics, optimal activity at pH 6.0, and was high thermo-stable when incubated up to 75 °C for 90 min. The catalytic activity of Vu-RPOX decreased in the presence of the classic peroxidase inhibitors, but was not inhibited by MgCl2, NH4Cl, MnCl2, CaCl2, and NaCl. Vu-RPOX delay the vegetative growth of the phytopathogenic fungi Colletrotrichum gloeosporioides and Fusarium oxysporum. Based on its properties Vu-RPOX is a potentially useful molecule for application in biomedical, biotechnological, industrial, and agricultural areas particularly because it showed high stability when exposed to a wide range of temperatures and performance at pH 4–7 and impairment of mycelial growth of C. gloeosporioides and F. oxysporum.