Molecular Weight Proteins Research Articles

Novel Pickering emulsion stabilized by natural fiber polysaccharide-protein extracted from Haematococcus pluvialis residues

As an excellent source of natural astaxanthin, Haematococcus pluvialis ( H. pluvialis ) is rich in nutritional elements in the residues after extraction of astaxanthin. At present, the residues of H. pluvialis are only used as feed in the breeding industry, but its application in food industry is still a challenge. In this study, fiber polysaccharide-protein complex also known as aqueous protein extraction from H. pluvialis residues (APHRs) was successfully extracted from the aqueous extract of H. pluvialis residues (AHRs). The protein and carbohydrate contents of APHRs were 23.6% and 64.9%, respectively. The protein of APHRs was composed of β-sheet (57.6%) and turns, and the molecular weight of protein was about 10 kDa. What's more, APHRs had good emulsifying stability and oil holding capacity. Microscopic images showed that fibrous polysaccharides were connected around protein particles, which can form a stable structural cross-linking. The low energy emulsion formed by APHRs showed the smallest particle size and the best storage stability compared with crude polysaccharides of H. pluvialis residues (CPHRs) and AHRs. The emulsion creaming index of APHRs, CPHRs, and AHRs in high energy emulsion was 1%, 52%, and 61% respectively. Owing to the existence of fibrous polysaccharides, the stability of APHRs emulsion was superior to that of CPHRs and AHRs. In summary, APHRs have excellent safety and stability, and it is likely food-grade raw material for stabilizing Pickering emulsion. • New materials for forming Pickering emulsions from H. pluvialis residues. • Fiber polysaccharide-protein made the emulsion have excellent stability. • This study expands the application forms of microalgae in food. • Increasing the added value of H. pluvialis , and realizing sustainable development.

4-Hexylresorcinol Treatment before Degumming Increases the β-Sheet Structure of Silk Sericin and BMP-2 Expression in RAW264.7 Cells.

Silk sericin is a degumming product used by the silk industry. The degumming process can affect the protein structure and molecular weight of silk sericin. The present study examined how pretreatment with 4-hexylresorcinol (4HR) affects the biomedical properties of silk sericin. Before the degumming process, silkworm cocoons were treated with 4HR solution. The protein structure of the final degumming product was evaluated by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy. Untreated silk sericin (S) and silk sericin pretreated with 4HR (S+4HR) were added to RAW264.7 cells, and the expression of BMP-2 was determined. The bone-regenerating capacity of S+4HR was evaluated using the critical-sized rat calvarial defect model. Compared with S, S+4HR showed an increase in β-sheet structures. Administration of S+4HR to RAW264.7 cells increased expression of BMP-2, mainly via the TLR-mediated signaling pathway. Bone volume, as measured by micro-computerized tomography, was significantly greater in the S+4HR group than in the S, gelatin alone, and unfilled control groups (p < 0.05 each). Expression of BMP-2 and runx2 in tissue specimens was significantly higher following treatment with S+4HR than with S (p < 0.05). Taken together, these findings show that 4HR pretreatment before the degumming process increased the β-sheet structure of silk sericin, as well as inducing BMP-2 expression and bone regeneration ability.

Spectroscopic techniques for elucidation of structural changes in temperate cowpea cultivars under germination: A useful tool for quality determination and industrial application

The present study investigated the molecular changes induced by germination in cowpea cultivars by spectroscopic techniques. The ATR FT-IR, Intrinsic fluorescence, and UV spectroscopic techniques revealed that germination shows alteration in cowpea cultivars. The ATR-FTIR showed slight differences in band intensities corresponding to carbohydrates, lipids, and protein regions at 700 to 4000 cm-1 wavenumbers. Starch order structure understanding their functionality showed a reduction of short-range ordered structures in Black cowpea flour and long ordered starch fraction in White cowpea flour under germination. The study quantified the degree of ordered starch and their alteration in amorphous/crystallinity nature concerning germination and cowpea cultivars. The secondary structures revealed a reduction of β-sheets and α-helix content, representing decreased ordered protein structures and their shifting into random coils and turn structures. The germinated flours showed decreased fluorescence intensities with the shift from 347 to 348, reflecting the redshifts due to decreased concentrations of fluorescent compounds during germination in cowpea flour. UV spectrum revealed a similar spectrum with an increase in absorption of cowpea flour under germination. The electrophoresis showed variations in the intensities of high (25 to 225 kDa) and low (19 to 10 kDa) molecular weight proteins in germinated cowpea cultivars than the native one. Overall, this study demonstrated the potential of ATR-FTIR, fluorescence and UV-based spectroscopy as non-destructive techniques to assess the alteration of pulses at the molecular level and structural changes under the germination process.

Kekerabatan merpati hias (Columba livia) dilihat dari profil protein darah

Objective: The purpose of this study was to predict the kinship of ornamental pigeons based on blood proteins. Methods: The research method used is exploratory descriptive with a laboratory observation-based approach. Research procedures include: Blood Sampling, Blood Protein Isolation, Purification, Measurement of concentration with a nanodrop spectrophotometer and Electrophoresis. Data analysis includes: Protein Band Profile and Determination of Protein Molecular Weight with RF formula and Relationship with MVSP version 3.22 program. Results : The protein profile in the plasma of ornamental pigeons is different from one type of pigeon to another. some of the protein appears in the ornamental pigeon species but does not appear in other breeds. Likewise with the target protein to be analyzed, some are expressed and some are not expressed in ornamental pigeons. Results based on the analysis of protein profiles and dendograms of the four specific proteins (hemoglobin, transferrin, posttransferrin, and immunoglobulin) contained in erythrocytes and blood plasma, it can be seen that there are two clusters. Cluster 1 is occupied by varieties of ornamental pigeons Moven and cluster 2 is occupied by varieties of ornamental pigeons Lahore, American fantail, Vienna, Indian Fantail, King, Capucine, Gondok and Modena. Conclusions: The results of the ornamental pigeon kinship prediction based on blood protein showed that each variety had different kinship relationships. King, Capucine, Gondok and Modena pigeons have the closest relationship, and Moven pigeons have the most distant relationship from the researched ornamental pigeons.

Effect of Alcalase Modification of Yellow Lupin (Lupinus luteus L.) Protein Isolate on Some Functional Properties and Antioxidant Activity.

Protein isolate obtained from sweet yellow lupin (Lupinus luteus L.) and its Alcalase hydrolysates were examined for their functional and antioxidant properties in relation to surface hydrophobicity of proteins and peptides and molecular weight distribution. Enzymatic hydrolysis improved the foaming characteristics of lupin proteins, while the emulsifying properties deteriorated. It means that good foaming properties of preparations are determined by the presence of low-molecular δ conglutin and small subunits of γ conglutins. In turn, larger proteins such as α and β conglutin are responsible for maintaining good emulsifying properties. The measured surface hydrophobicity was consistent with the results of emulsifying properties. It has also been shown that the scope of changes in antioxidant properties due to hydrolysis, measured by DPPH method and as reducing power, is more pronounced than with the use of ABTS and FRAP methods.

Optimization for Simultaneous Removal of Product/Process-Related Impurities of Peptide Fc-Fusion Protein Using Cation Exchange Chromatography

Fc fusion proteins are used as therapeutic agents with unique structures by combining the Fc domain of an antibody with other active proteins, cytokines, and enzymes. Peptide Fc-fusion proteins are complex fusion molecules that possess a structure different from that of monoclonal antibodies (mAbs) and are difficult to express, thereby affecting their quality. Many product/process-related impurities generated during the production of peptide Fc-fusion proteins pose a risk to the robustness of pre-existing three-column platforms for the purification of mAbs. Thus, we first evaluated the effect of pH, conductivity, and dynamic binding capacity (DBC; g of product per liter of resin) on the separation of host cell protein (HCP) and high molecular weight (HMW) and low molecular weight (LMW) proteins in strong cation exchange chromatography and then established an operating range using the design of experiments (DoE). Based on our studies, the optimal removal rates of HCP and HMW were achieved under the following conditions: 8 CV of wash buffer, 20–23 g/L of resin DBC, and an elution buffer conductivity of 63–66 mS/cm. The conductivity of the wash buffer used to remove the LMW was 50 mS/cm. In addition, reproducibility was confirmed by scaling up two batches using the Fractogel® EMD SO3− (M) resin. As a result of confirming with a validated test method in all batches, >55% yield, >98.2% purity, and >27% HCP reduction rate were satisfied. The cation exchanger exhibited an acceptable step yield and effectively reduced product/process-related impurities within the established range.

Comprehensive Genomic Characterization of the NAC Transcription Factors and Their Response to Drought Stress in Dendrobium catenatum

As a large transcription factor family, NAC family proteins (NAM, ATAF1,2, and CUC2) play critical roles in plant growth, development, and response to stresses. Herein, the NAC gene family of Dendrobium catenatum was identified and analyzed by bioinformatics methods. Their expression patterns in different tissues and under drought stress were analyzed using RNA-seq data and the quantitative real-time reverse transcription-polymerase chain reaction (RT-qPCR) method. A total of 90 NAC genes were identified, encoding amino acids with numbers ranging from 88 to 1065, with protein molecular weight ranging from 10.34 to 119.24 kD, and isoelectric point ranging from 4.5 to 9.99. Phylogenetic analysis showed that the DcNAC proteins could be divided into 17 subgroups, and each subgroup had conserved motif composition and gene structure. Twenty types of cis-elements were identified in the DcNAC promoters. RNA-seq analysis showed that the expression of DcNAC genes had tissue specificity and displayed different expression patterns under drought stress. Co-expression network analysis of the DcNAC genes revealed nine hub genes, and their expression levels were then validated by RT-qPCR. The results showed that DcNAC6, DcNAC18, DcNAC29, DcNAC44, and DcNAC51 (mainly in roots) as well as DcNAC16 and DcNAC64 (mainly in leaves) were considered as the candidate genes for drought tolerance in D. catenatum. Taken together, this study identified candidate NAC genes with potential functions in response to drought stress, which is valuable for development of drought resistance in D. catenatum.

Molecular Characterization, Expression, Evolutionary Selection, and Biological Activity Analysis of CD68 Gene from Megalobrama amblycephala.

CD68 is a highly glycosylated transmembrane glycoprotein that belongs to the lysosome-associated membrane glycoprotein family and is involved in various immune processes. In this study, Megalobrama amblycephala CD68 (MaCD68) was cloned and characterized, and its expression patterns and evolutionary characteristics were analyzed. The coding region of MaCD68 was 987 bp, encoding 328 amino acids, and the predicted protein molecular weight was 34.9 kDa. MaCD68 contained two transmembrane helical structures and 18 predicted N-glycosylation sites. Multiple sequence alignments showed that the MaCD68 protein had high homology with other fish, and their functional sites were also highly conserved. Phylogenetic analysis revealed that MaCD68 and other cypriniformes fish clustered into one branch. Adaptive evolution analysis identified several positively selected sites of teleost CD68 using site and branch-site models, indicating that it was under positive selection pressure during evolution. Quantitative real-time reverse transcription polymerase chain reaction analysis showed that MaCD68 was highly expressed in the head kidney, spleen, and heart. After Aeromonas hydrophila infection, MaCD68 was significantly upregulated in all tested tissues, peaking at 12 h post-infection (hpi) in the kidney and head kidney and at 120 hpi in the liver and spleen, suggesting that MaCD68 participated in the innate immune response of the host against bacterial infection. Immunohistochemical and immunofluorescence analyses also showed that positive signals derived from the MaCD68 protein were further enhanced after bacterial and lipopolysaccharide treatment, which suggested that MaCD68 is involved in the immune response and could be used as a macrophage marker. Biological activity analysis indicated that recombinant MaCD68 (rMaCD68) protein had no agglutination or bactericidal effects on A. hydrophila but did have these effects on Escherichia coli. In conclusion, these results suggest that MaCD68 plays a vital role in the immune response against pathogens, which is helpful in understanding the immune responses and mechanisms of M. amblycephala.

Effect of Grafted Insect Protein with Palatinose on Quality Properties of Phosphate-Free Meat Emulsion.

Due to concerns about the negative effects of phosphate on human health, the development of phosphate substitutes is an active area of research. Among the various methods, the structural modification of proteins has previously been established. In this study, we used grafting technology. Extracted insect protein was grafted with palatinose (GI), and 0.1 and 0.15% of GI were added to a phosphate-free meat emulsion mixed with 0.1% of eggshell powder (ES). The pH, myofibrillar protein solubility, and apparent viscosity increased with the addition of GI and ES (p < 0.05). Color values were also affected by GI and ES addition (decreased CIE L* and CIE a* and increased CIE b*; p < 0.05), while cooking loss was only improved by the addition of ES and not GI. Although the total fluid separated more than negative control (p < 0.05), the addition of ES improved emulsion stability and total expressible fluid separation and the fat separation reduced with addition of GI and ES (p < 0.05). Lipid oxidation was inhibited by the addition of GI and ES (p < 0.05). Moreover, the protein molecular weight distribution under 20 kDa was modified by the addition of GI, and the hardness and springiness of treatments decreased. In conclusion, the addition of GI and ES might be used to improve cooking loss, emulsion stability, and antioxidants, while the textural properties should be further researched.

Cloning and in silico characterization of an abiotic stress-inducible U-box domain-containing protein gene GsPUB8 from Glycine soja

The ubiquitination pathway is involved in the posttranslational modification of cellular proteins. However, the role of E3 ubiquitin ligase family proteins under abiotic stress conditions remains unclear, particularly in soybean. The core objective of the current study was to isolate and functionally characterize the GsPUB8 protein gene from wild soybean (Glycine soja) by using a homologous cloning method to investigate its abiotic stress responses. The GsPUB8 is a 40,562 Da molecular weight protein with 373 amino acid residues. The sequence alignment revealed the presence of U-box domain while the phylogenetic analysis showed an abundance of PUB8 proteins in both monocot and dicot plants. Analysis of gene structure predicted the absence of introns along with the presence of one exon. Furthermore, the activity of the GsPUB8 protein was anticipated in the plasma membrane and its expression was persuaded with NaCl, ABA, PEG6000, and NaHCO3 treatments with considerably higher manifestation in roots than leaves although, expressed in both vegetative and reproductive parts of G. soja. GsPUB8 protein showed 54% and 32% sequence identity to U-box domain containing 8 and 12 proteins from Arabidopsis thaliana and Oryza sativa subsp. japonica, respectively. GsPUB8 exhibited relatively higher expression under saline and drought stress particularly in roots. Whereas, the 3D model of GsPUB8 protein was generated using the SWISS-MODEL. This study can be used to manipulate the GsPUB8 protein or GsPUB8 gene for transformation purposes and its functional characterization under abiotic stress conditions.

Ultra-low protein residue of chitosan by one step H2O2 and sodium dodecyl sulfate treatment

Residual protein in chitosan-based biomaterials may cause inflammation, allergy, and immune rejection after surgery, impeding their clinical application. Facile production of chitosan with ultra-low protein content (residual protein <0.2 %) is yet to be addressed. Herein, we proposed a one-step method for preparing chitosan with residue protein content <0.2 % by using hydrogen peroxide and sodium dodecyl sulfate, which is simple, time-saving, cost-effective, and acid/alkali-free. Notably, the molecular weight of chitosan can be reduced simultaneously. The effects of experimental parameters (i.e. hydrogen peroxide concentration (0.01 %–1 %), SDS concentration (5 %–20 %), and reaction temperature (50 °C–70 °C)) on the protein removal and molecular weight decrease were systematically analyzed by response surface methodology. The results show that temperature and H2O2 concentration are the main parameters affecting the deproteinization of chitosan. Further characterizations on the resulting ultra-low protein residue chitosan revealed unchanged chemical structure, enhanced crystallinity, and reduced thermal stability. The proposed one-step deproteination method may have great potential for industrial mass production of ultra-low protein residue chitosan.

Profil Bobot Molekul Protein, Cemaran Logam Berat Timbal (Pb) Dan Kadmium (Cd), Serta Bakteri Escherichia coli Pada Ekstrak Cair Ikan Gabus (Channa striata)

The Snakehead fish extract is one of the fish extracts that has many benefits and has been used in the health sector such as emulsifiers, skin health drugs, helping muscle formation and growth, accelerating wound healing, maintaining fluid balance in blood vessels, improving poor nutrition, and being healthy. for digestion so that the quality characteristics of the extract need to be researched and maintained to be used. This study aims to determine the quality characteristics of the liquid extract of snakehead fish (Channa striata) based on quality parameters such as protein molecular weight profile, heavy metal contamination of lead (Pb), and cadmium (Cd), and bacterial contamination of Escherichia coli. Snakehead fish extract was obtained using the steaming extraction method at a temperature of 60oC, for 6 hours to obtain albumin levels of 12.549 mg/g, protein molecular weight profile analysis detected 7 major bands and 1 minor band in the molecular weight range 19.05 kDa - 92, 72 kDa, where the molecular weight of albumin protein is suspected to be in band number 3 53.72 kDa, E.coli bacteria contamination &lt; 3 APM/g and heavy metals lead (Pb) and cadmium (Cd) were not detected.

Black rice flour‐induced changes in gluten conformation in fresh, pre‐fermented and frozen dough

SummaryBlack rice flour greatly enriches the nutrition of flour products, and also alleviates the quality deterioration of frozen dough to a certain extent, but the gluten‐influenced mechanism remains unclear. The effects of black rice flour with different particle sizes on protein molecular weight distribution, secondary structure, fluorescence characteristics, thermogravimetric properties, and chemical interaction of the fresh dough (FD), pre‐fermented dough (PD), and thawed dough (TD) were investigated. The addition of black rice flour resulted in the breaking of disulfide bonds in the FD and an increase in the content of total SDS‐extractable protein. However, the depolymerization of large glutenin polymers in the PD and TD of the composite flour system was lower than wheat flour system, especially in the dough with small particle size black rice flour. As the particle size of black rice flour decreased, the intermolecular force of the composite flour dough system is more prominent, of which the hydrophobic interaction force contributes the most considerable value. In addition, TD in the composite flour system has less weight loss than that of wheat flour system. Therefore, adding black rice flour reduced the deterioration of gluten protein, and the small particle size of black rice flour showed advantages.

The Expression of Plasma Protein in Bali-polled Bulls Using 1D-SDS-PAGE

The fertility rate of bulls in a breeding program is not only described by the quantity and quality of semen. Factors, such as the interstice factor of the sperm and the plasma component of semen, affect the fertility rate of bulls. The fertility rate can also be determined by identifying the protein content of semen plasma. Therefore, the current study aimed to identify the relationship between seminal plasma protein molecular weight and semen quality of Bali-polled bulls. The study was conducted at the Laboratory of Semen Processing, Faculty of Animal Science, Hasanuddin University, Makassar, Indonesia, the Research Center for Applied Zoology, National Research and Innovation Agency, Cibinong, Indonesia and the Laboratory of Animal Biotechnology Center, IPB University, Bogor, Indonesia from November 2021 to January 2022. The samples came from 5 Bali-polled and 5 Bali-horned bulls. Semen collection was conducted twice a week using an artificial vagina. The concentration of seminal plasma protein was determined by the Bradford method of 1D-SDS-PAGE. The study results showed that fresh semen of Bali-polled and Bali-horned bulls was considered a normal category. Seminal plasma proteins of Bali-polled and Bali-horned bulls were classified using 8 bands to categorize molecular weight; 150 kD (IGF-1), 110 kD (A-kinase anchoring protein 3), 93 kD (A-kinase anchoring protein 4), 54-87 kD (Arylsulfatase-a), 44-62 kD (N-Acetyl-ß-Guicosaminidase), 44kD (Phosphoglycerate kinase), 15-30 kD (BSP A1/A2, BSP-A3 and BSP-30 [BSP1, BSP3, and BSP5]) and 12-14 kD (Acidic seminal fluid proteins). The findings indicated that both Bali-polled and Bali-horned bulls could have a high reproductive rate. In conclusion, protein analysis based on molecular weight using 1D-SDS-PAGE can be used as a biomarker for semen quality in Bali-polled bulls. Therefore, evaluating the semen quality with a molecular basis as an additional indicator of superior bull in the selection process is an alternative method.

Applications of MALDI-MS/MS-Based Proteomics in Biomedical Research.

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is one of the most widely used techniques in proteomics to achieve structural identification and characterization of proteins and peptides, including their variety of proteoforms due to post-translational modifications (PTMs) or protein–protein interactions (PPIs). MALDI-MS and MALDI tandem mass spectrometry (MS/MS) have been developed as analytical techniques to study small and large molecules, offering picomole to femtomole sensitivity and enabling the direct analysis of biological samples, such as biofluids, solid tissues, tissue/cell homogenates, and cell culture lysates, with a minimized procedure of sample preparation. In the last decades, structural identification of peptides and proteins achieved by MALDI-MS/MS helped researchers and clinicians to decipher molecular function, biological process, cellular component, and related pathways of the gene products as well as their involvement in pathogenesis of diseases. In this review, we highlight the applications of MALDI ionization source and tandem approaches for MS for analyzing biomedical relevant peptides and proteins. Furthermore, one of the most relevant applications of MALDI-MS/MS is to provide “molecular pictures”, which offer in situ information about molecular weight proteins without labeling of potential targets. Histology-directed MALDI-mass spectrometry imaging (MSI) uses MALDI-ToF/ToF or other MALDI tandem mass spectrometers for accurate sequence analysis of peptide biomarkers and biological active compounds directly in tissues, to assure complementary and essential spatial data compared with those obtained by LC-ESI-MS/MS technique.

Effect of wheat bran dietary fiber on structural properties and hydrolysis behavior of gluten after synergistic fermentation of Lactobacillus plantarum and Saccharomyces cerevisiae.

The effect of synergistic fermentation of Lactobacillus plantarum and Saccharomyces cerevisiae on the structural properties and aggregation behavior of gluten containing different wheat bran dietary fiber (WBDF) levels (0, 3, 6, 9, and 12%) was investigated. The results showed that WBDF addition affected the aggregation behavior of gluten at the molecular level, while WBDF significantly induced depolymerization behaviors in large aggregated gluten proteins (Molecular weight > 130 kDa) under reducing conditions (p < 0.05). In terms of secondary structure, WBDF significantly reduced glutamine side chain levels and reduced antiparallel β-sheet structures from 28.57 to 24.53% (p < 0.05). In addition, WBDF thermal properties and its water holding capacity were the main factors causing changes in thermal properties in the overall gluten system. This study provides new data for the improved production of sourdough whole grain and/or high fiber flour products.

Variation of Protein Band Pattern on the Skin Secretions of Chalcorana chalconota (Schlegel, 1837) Complex.

&lt;b&gt;Background and Objective:&lt;/b&gt; &lt;i&gt; Chalcorana chalconota &lt;/i&gt;is a complex frog species in West Sumatra which has been revised and designated as &lt;i&gt;Chalcorana parvaccola&lt;/i&gt; and &lt;i&gt;Chalcorana rufipes&lt;/i&gt; based on several studies such as morphology and genetics. Other studies such as protein band patterns can be a marker to differentiate species. This research was done to determine and prove the variations of protein band patterns found in skin secretions of the &lt;i&gt;C. chalconota &lt;/i&gt;species complex. &lt;b&gt;Materials and Methods:&lt;/b&gt; Frog samples were collected in the Pasia Laweh area, Pesisir Selatan, West Sumatra. The standard length measurement of the frog was carried out to determine the voltage that will be applied to the frog using an electric shock device (TAS/transcutaneous amphibian stimulator) in the process of removing the frog's skin secretions. Frog skin secretions were taken and used to see the pattern of protein bands using the SDS-PAGE method. &lt;b&gt;Results:&lt;/b&gt; The protein band patterns of skin secretions of &lt;i&gt;C. chalconota&lt;/i&gt; species complex were different between &lt;i&gt;C. parvaccola&lt;/i&gt; and &lt;i&gt;C. rufipes&lt;/i&gt;. In the skin secretions of &lt;i&gt;C. parvaccola&lt;/i&gt;, there were eight protein bands with a molecular weight ranging between 12-103 kDa while for &lt;i&gt;C. rufipes&lt;/i&gt; there were seven protein bands with a molecular weight ranging between 12-102 kDa. There were six protein bands shared by these two species. Two bands were only found in the skin secretions of &lt;i&gt;C. parvaccola&lt;/i&gt; and one band was only found in &lt;i&gt;C. rufipes&lt;/i&gt;. &lt;b&gt;Conclusion:&lt;/b&gt; Pattern and molecular weight of protein in &lt;i&gt;C. parvaccola&lt;/i&gt; and &lt;i&gt;C. rufipes&lt;/i&gt; skin secretions can be used as protein markers to distinguish the two species.

Photo-Reactivity and Photo-Transformation of Algal Dissolved Organic Matter Unraveled by Optical Spectroscopy and High-Resolution Mass Spectrometry Analysis

The rapid proliferation of planktonic algae induced by eutrophication and climate warming make algae dissolved organic matter (AOM) an important source of dissolved organic matter (DOM) in surface waters, but the understanding of the link between AOM composition and photo-reactivity/photo-transformation of DOM in aquatic systems is limited. Here, intracellular organic matter (IOM) from Microcystis aeruginosa was extracted and subjected to molecular weight (MW) fractionation. Results indicated that IOM had lower aromaticity and higher photosensitive activity compared to Suwannee River fulvic acid (SRFA). The photosensitive activity of IOM relied on both its molecular weight distribution and fluorescence components. The IOM fraction with the highest MW proteins had the lowest quantum yields of reactive intermediates (ΦRIs), which increased with the decrease of MW, while the fractions with more low-excitation tyrosine-like components had relatively higher ΦRIs. Parallel factor analysis and high-resolution mass spectrometry revealed that light radiation of IOM resulted in the composition transformation from tryptophan-like and tyrosine-like components to humic-like components, forming less aromatic and more saturated recalcitrant dissolved organic carbon. Our findings provide new insights into the photo-reactivity and photo-transformation of algae-derived organic matters and help to predict DOM formation involved in carbon cycling in water environment.

Production and Characterization of a SARS-CoV-2 Nucleocapsid Protein Reference Material.

Rapid antigen tests have become a widely used COVID-19 diagnostic tool with demand accelerating in response to the highly contagious SARS-CoV-2 Omicron variant. Hundreds of such test kits are approved for use worldwide, predominantly reporting on the presence of the viral nucleocapsid (N) protein, yet the comparability among manufacturers remains unclear and the need for reference standards is recognized. To address this lack of standardization, the National Research Council Canada has developed a SARS-CoV-2 nucleocapsid protein reference material solution, NCAP-1. Reference value determination for N protein content was realized by amino acid analysis (AAA) via double isotope dilution liquid chromatography-tandem mass spectrometry (LC-ID-MS/MS) following acid hydrolysis of the protein, in conjunction with UV spectrophotometry based on tryptophan and tyrosine absorbance at 280 nm. The homogeneity of the material was established through spectrophotometric absorbance readings at 280 nm. The molar concentration of the N protein in NCAP-1 was 10.0 ± 1.9 μmol L-1 (k = 2, 95% confidence interval). Reference mass concentration and mass fraction values were subsequently calculated using the protein molecular weight and density of the NCAP-1 solution. Changes to protein higher-order structure, probed by size-exclusion liquid chromatography (LC-SEC) with UV detection, were used to evaluate transportation and storage stabilities. LC-SEC revealed nearly 90% of the N protein in the material is present as a mixture of hexamers and tetramers. The remaining low molecular weight species (<30 kDa) were interrogated by top-down mass spectrometry and determined to be autolysis products homologous to those previously documented for N protein of the original SARS-CoV [Biochem. Biophys. Res. Commun.2008t, 377, 429-433].

Genome-Wide Identification and Expression Analysis of the NAC Gene Family in Alfalfa Revealed Its Potential Roles in Response to Multiple Abiotic Stresses.

NAC (NAM, ATAF1/2, and CUC2) transcription factors compose one of the largest families of plant-specific transcription factors; they are widely involved in plant growth and development and have especially important roles in improving stress resistance in plants. However, NAC gene family members in alfalfa (Medicago sativa L.) have not been systematically identified and analyzed genome-wide due to the complexity of the alfalfa reference genome. In this study, a total of 421 M. sativa NAC genes (MsNACs) were identified from the alfalfa “Xinjiangdaye” reference genome. Basic bioinformatics analysis, including characterization of sequence length, protein molecular weight and genome position and conserved motif analysis, was conducted. Expression analysis showed that 47 MsNACs had tissue-specific expression, and 64 MsNACs were expressed in all tissues. The transcriptomic profiles of the genes were very different, indicating that these MsNACs have various functions in alfalfa growth and development. We identified 25, 42 and 47 MsNACs that respond to cold, drought and salt stress based on transcriptome data analysis and real-time quantitative PCR (RT–qPCR). Furthermore, 22 MsNACs were found to respond to both salt and drought stress, and 15 MsNACs were found to respond to cold, salt and drought stress. The results of this study could provide valuable information for further functional analysis of MsNACs and for the improvement of stress resistance in alfalfa.