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Myosin heavy chain (MHC) isoforms and meat quality characteristics of different muscles were investigated to explore their potential relationships in yaks. Results showed that semitendinosus (ST), longissimus thoracis (LT), and infraspinatus (IS) have a greater ratio of MHC IIb (47.84%), MHC IIa (73.27%), and MHC I (24.26%), respectively, than the other two muscles. Compared with LT or ST, IS exhibited more intense color, greater water-holding capacity, and initial tenderness with higher intermuscular fat (IMF) and collagen (of lower cross-linking level), presenting overall better quality. Variations in MHC isoforms accounted for the muscle-specific meat quality. Specifically, MHC I was positively associated with redness, myoglobin, IMF, collagen, pH, and thermal stability and negatively associated with myofibril fragmentation index, fiber thickness, collagen cross-linking, and drip loss. These results provide insights into the relationships between MHC isoforms and meat quality in yaks and the MHC I isoform has an extensive influence on meat quality., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Aspartic proteases (ASPs) are important hydrolases for parasitic invasion of host tissues or cells. This was the first study on Demodex ASP. First, the complete coding sequence (CDS) was amplified, cloned and sequenced. Then, the protein physical and chemical properties was analysed. Finally, the recombinant plasmid, expression and purification system was established. Results showed that the lengths of CDS of Demodex folliculorum and D. brevis were 1161 and 1173 bp, respectively. The molecular weight of the protein was approximately 40 KDa. It contained an aspartic acid residue, a substrate-binding site and signal peptide, yet lacked a transmembrane domain and was located in the membrane or extracellular matrix. The phylogenetic and conserved motif analyses showed that D. folliculorum and D. brevis clustered separately and then formed a single branch, which finally clustered with other Acariformes species. The prokaryotic expression systems for recombinant ASP with His-tag (rASP-His) and GST-tag (rASP-GST) were constructed. The inclusion bodies of rASP-His were renaturated by gradient urea and purified using NI beads, while those of rASP-GST were renaturated by sarkosyl and Triton X-100 and purified using GST beads. Conclusively, the prokaryotic expression and purification system of Demodex rASP was successfully established for further pathogenic mechanism research., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Accurate classification and identification of mosquitoes are essential for the prevention and control of mosquito-borne diseases. In this study, adult mosquitoes were collected from 15 cities across 14 provinces in China. They were identified morphologically with the dominant species determined. Furthermore, representative samples were identified at the molecular level based on rDNA 28S D5. In total, 880 adult mosquitoes were collected belonging to Culex (266), Aedes (473), Armigeres (13), and Anopheles (5). Aedes albopictus and "C. pipiens subgroup" were the dominant species. A total of 140 sequences of 28S D5 region (68 for "C. pipiens subgroup", 51 for Ae. albopictus, 18 for Ar. subalbatus, and three for An. sinensis) ranging from 148 to 161 bp were obtained, with 100 % success of amplification and sequencing. Molecular identification were consistent with morphological classification. Sequence analysis showed that "C. pipiens subgroup" was identified into three clades: the traditional C. pipiens subgroup (Clade I), the newly discovered C. cf. perexiguus (Clade II), and C. new sp. (Clade III). Clade I contained the most abundant haplotypes (16) widely distributed without geographical differences. Clade II included six haplotypes that were aggregately distributed south of the Yangtze River. Only three sequences in Clade III showed two haplotypes with no geographical differences. Further morphological comparisons demonstrated differences in body color, beaks, and abdomens among the three clades. In conclusion, the rDNA 28S D5 region could effectively distinguish Culex, Aedes, Armigeres, and Anopheles species at the lower category level, demonstrating its potential as a mini-DNA barcode for mosquito identification., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

The present study investigated the effect of slaughter age (2.43 ± 0.20, 4.15 ± 0.19, 6.62 ± 0.18, 10.59 ± 0.74 years) and postmortem aging time (1, 24, and 72 h) on the tenderness and water-holding capacity (WHC) of yak longissimus thoracis muscles to determine the most suitable age for slaughter to ensure product consistency. Under conventional postmortem aging conditions (4 °C), muscles of each age group exhibited the effect of cold shortening. Once the cold shortening occurred, the age effect on thickening muscle fiber and developing cross-links of collagen, considered to intensify the meat toughness, became less important. Owing to greater carcass weight and intramuscular fat, muscles of the older carcass (over 6-year-old) were less influenced by the cold shortening effect during the chilling process and showed lessened sarcomere contraction, delayed formation of drip loss channels, and increased level of myofibril fragmentation index (MFI) and myofiber structural disintegration, resulting in greater tenderness and WHC, especially 6-7 years group. Aging of 72 h structurally disintegrated the collagen cross-linking and integrity of muscle fibers and elevated the MFI, improving the meat tenderness. Therefore, the suitable slaughter age for yak is 6-7 years old and after 72 h aging, improved quality of yak meat can be obtained., Competing Interests: Declaration of Competing Interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The parasitic lice of Hominidae are a class of blood-sucking insects, having a large fragment expansion region in ribosome 18S V4 region. In this study, the value of the E23-5-E23-6 stem-loop structure in the insertion region for molecular identification of lice were explored through motif analysis and secondary structure construction. Five pubic lice samples from China were morphologically identified, and primers for the rRNA 18S V4 region were designed for molecular identification. The V4 sequence of the parasitic lice of Hominidae was retrieved from GenBank for sequence analysis. The five samples were identified as pubic lice based on V4 region, which were of the same specie but geographically different from Australian strains in Genbank, with the identity of 99.06-99.46%. Compared with the human lice, both the chimpanzee lice and pubic lice had large indel fragments in the V4 region. Comparison results showed that Muscle and MAFFT had better alignment and phylogeny results than Clustal. The large expansion region, comprising E23-5 and E23-6, was located between E23-4 and E23-7. The V4 secondary structure showed that the stem-loop structures of the lice parasitizing on pubic area, human, and chimpanzee were different in the E23-5 and E23-6, which could effectively distinguish the three parasitic lice and divide the human lice into five genotypes. This is suitable not only for the identification of three lice species in higher taxonomic ranks but also for genotype identification of human lice in lower taxonomic ranks. The difference between the stem-loop structure is more intuitive than that between the primary sequences., Competing Interests: Declaration of Competing Interest None of the authors have conflicts of interest to report., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Nano-Au and methylene blue (MB) were assembled layer-by-layer (LBL) into films on the glassy carbon electrode modified by thiourea for detection of human chorionic gonadotrophin (HCG). The electrode modification process was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron micrograph (SEM). The factors influencing the performance of the amperometric immunosensor were studied in detail. Tests performed with this immunosensor showed good linearity, the working range for the system was 1.0-100.0 mIU/mL with a detection limit of 0.3 mIU/mL at 3sigma. Moreover, the studied immunosensor exhibited high sensitivity and long-term stability. The present work supplied a promising test method for clinical immunoassay.

A highly sensitive and label-free amperometric immunosensor has been developed for the detection of carcinoembryonic antigen (CEA) based on layer-by-layer (LBL) assembly of gold nanoparticles (GNPs), multi-walled carbon nanotubes-thionine (MWNTs-THI) and chitosan (CHIT) on 3-mercaptopropanesulfonic, sodium salt (MPS)-modified gold electrode surface by electrostatic adsorption. The stepwise LBL assembly process of electroactive species on electrode surface was characterized by means of cyclic voltammetry (CV) in PBS. The factors influencing the performance of the resulting immunosensor were studied in detail. The morphologies of MWNTs, MWNTs-THI and GNPs-MWNTs-THI-CHIT were further characterized by transmission electron microscopy (TEM). The immunosensor was highly sensitive to CEA with a detection limit of 0.01 ng mL(-1) (signal/noise ratio of 3) and the linear range with two concentration intermittences was from 0.5 to 15.0 ng mL(-1) and from 15.0 to 200.0 ng mL(-1), respectively. In addition, the prepared immunosensor could be regenerated 10 times with 5 M urea solution. When the immunosensor was stored at 4 degrees C and measured intermittently (every 4-6 days), no apparent change was found over 3 months. The immunosensor system showed an excellent reproducibility and stability.