Molecular cloning, expression and purification of lactoferrin from Tibetan sheep mammary gland using a yeast expression system

Genetic Variations of MSTN and Callipyge in Tibetan Sheep: Implications for Early Growth Traits

Tibetan sheep are vital to the ecosystem and livelihood of the Tibetan Plateau; however, traditional breeding methods limit their production and growth. Modern molecular breeding techniques are required to improve these traits. This study identified a single nucleotide polymorphism (SNP) in myostatin (MSTN) and Callipyge in Tibetan sheep. The findings indicated notable associations between MSTN genotypes and growth traits including birth weight (BW), body length (BL), chest width (ChW), and chest circumference (ChC), as well as a particularly strong association with cannon circumference (CaC) at 2 months of age. Conversely, Callipyge polymorphisms did not have a significant impact on Tibetan sheep. Moreover, the analyses revealed a significant association between sex and BW or hip width (HW) at 2 months of age and ChW, ChC, and CaC at 4 months of age. Furthermore, the study's results suggested that the genotype of MSTN as a GA was associated with a notable sex effect on BW, while the genotype of Callipyge (CC) showed a significant impact of sex on CaC at 2 months of age. These results indicated that the SNP of MSTN could potentially serve as a molecular marker for early growth traits in Tibetan sheep.

Production of Bioactive Porcine Lactoferrin through a Novel Glucose-Inducible Expression System in Pichia pastoris: Unveiling Antimicrobial and Anticancer Functionalities

Lactoferrin (LF) stands as one of the extensively investigated iron-binding glycoproteins within milk, exhibiting diverse biological functionalities. The global demand for LF has experienced consistent growth. Biotechnological strategies aimed at enhancing LF productivity through microbial expression systems offer substantial cost-effective advantages and exhibit fewer constraints compared to traditional animal bioreactor technologies. This study devised a novel recombinant plasmid, wherein the AOX1 promoter was replaced with a glucose-inducible G1 promoter (PG1) to govern the expression of recombinant porcine LF (rpLF) in Pichia pastoris GS115. High-copy-number PG1-rpLF yeast clones were meticulously selected, and subsequent induction with 0.05 g/L glucose demonstrated robust secretion of rpLF. Scaling up production transpired in a 5 L fermenter, yielding an estimated rpLF productivity of approximately 2.8 g/L by the conclusion of glycerol-fed fermentation. A three-step purification process involving tangential-flow ultrafiltration yielded approximately 6.55 g of rpLF crude (approximately 85% purity). Notably, exceptional purity of rpLF was achieved through sequential heparin and size-exclusion column purification. Comparatively, the present glucose-inducible system outperformed our previous methanol-induced system, which yielded a level of 87 mg/L of extracellular rpLF secretion. Furthermore, yeast-produced rpLF demonstrated affinity for ferric ions (Fe3+) and exhibited growth inhibition against various pathogenic microbes (E. coli, S. aureus, and C. albicans) and human cancer cells (A549, MDA-MB-231, and Hep3B), similar to commercial bovine LF (bLF). Intriguingly, the hydrolysate of rpLF (rpLFH) manifested heightened antimicrobial and anticancer effects compared to its intact form. In conclusion, this study presents an efficient glucose-inducible yeast expression system for large-scale production and purification of active rpLF protein with the potential for veterinary or medical applications.

Heterologous Expression and Bioactivity Determination of Monochamus alternatus Antibacterial Peptide Gene in Komagataella phaffii (Pichia pastoris)

Insects have evolved to form a variety of complex natural compounds to prevent pathogen infection in the process of a long-term attack and defense game with various pathogens in nature. Antimicrobial Peptides (AMPs) are important effector molecules of the insect immune response to the pathogen invasion involved in bacteria, fungi, viruses and nematodes. The discovery and creation of new nematicides from these natural compounds is a key path to pest control. A total of 11 AMPs from Monochamus alternatus were classified into 3 categories, including Attacin, Cecropin and Defensin. Four AMP genes were successfully expressed by Komagataella phaffii KM71. The bioassay results showed that the exogenous expressed AMPs represented antimicrobial activity against Serratia (G−), Bacillus thuringiensis (G+) and Beauveria bassiana and high nematicide activity against Bursaphelenchus xylophilus. All four purified AMPs’ protein against B. xylophilus reached LC50 at 3 h (LC50 = 0.19 mg·mL−1 of MaltAtt-1, LC50 = 0.20 mg·mL−1 of MaltAtt-2 and MaltCec-2, LC50 = 0.25 mg·mL−1 of MaltDef-1). Furthermore, the AMPs could cause significant reduction of the thrashing frequency and egg hatching rate, and the deformation or fracture of the body wall of B. xylophilus. Therefore, this study is a foundation for further study of insect biological control and provides a theoretical basis for the research and development of new insecticidal pesticides.

Precision cellular agriculture: The future role of recombinantly expressed protein as food

Cellular agriculture is a rapidly emerging field, within which cultured meat has attracted the majority of media attention in recent years. An equally promising area of cellular agriculture, and one that has produced far more actual food ingredients that have been incorporated into commercially available products, is the use of cellular hosts to produce soluble proteins, herein referred to as precision cellular agriculture (PCAg). In PCAg, specific animal- or plant-sourced proteins are expressed recombinantly in unicellular hosts-the majority of which are yeast-and harvested for food use. The numerous advantages of PCAg over traditional agriculture, including a smaller carbon footprint and more consistent products, have led to extensive research on its utility. This review is the first to survey proteins currently being expressed using PCAg for food purposes. A growing number of viable expression hosts and recent advances for increased protein yields and process optimization have led to its application for producing milk, egg, and muscle proteins; plant hemoglobin; sweet-tasting plant proteins; and ice-binding proteins. Current knowledge gaps present research opportunities for optimizing expression hosts, tailoring posttranslational modifications, and expanding the scope of proteins produced. Considerations for the expansion of PCAg and its implications on food regulation, society, ethics, and the environment are also discussed. Considering the current trajectory of PCAg, food proteins from any biological source can likely be expressed recombinantly and used as purified food ingredients to create novel and tailored food products.

Mutations in FGFR1 were associated with growth traits in sheep (Ovis aries)

For its role in the mediation of myoblast proliferation, fibroblast growth factor receptor 1 (FGFR1) was considered a functional candidate gene for growth performance in Tibetan sheep. Via the polymerase chain reaction-restriction fragment length polymorphism (PCR-PFLP) approach, four single nucleotide polymorphisms (SNPs) including g.14752C > T (intron 1), g.45361A > G (intron 7), g.49400A > G (3'UTR region) and g.49587A > T (3'UTR region), were identified in 422 ewes. The association analysis demonstrated that individuals carrying the AA genotype of g.49400A > G had significantly greater withers height, length than those with GG genotype (p < 0.05). Individuals with genotype AA of g.49587A > T had significantly greater weight and chest circumference than those with genotype TT (p < 0.01). Additionally, the individuals with Hap1/1 diplotypes (CAAA-CAAA) were highly significantly associated with weight and chest circumference than Hap1/2 diplotypes (CAAA-CAAT) (p < 0.05). The quantitative real-time polymerase chain reaction (qPCR) analysis revealed that the FGFR1 was detectable expressed in muscle tissues within three different age stage. Remarkably higher mRNA expression was detected at fetal lamb stage as compared with adult ewes (p < 0.01). The outcome of this research confirmed that both g.49400A > G and g.49587A > T of FGFR1 were involved in growth-related traits, which may be considered to be genetic markers for improving the growth traits of Tibetan sheep.

Aptamer-functionalized pH-responsive polymer-modified magnetic nanoparticles for specific enrichment and sensitive determination of lactoferrin

A new type of aptamer-functionalized pH-responsive polymer-modified magnetic nanoparticles (ApMNPs) is introduced for specific enrichment and sensitive determination of lactoferrin (Lf) in complex matrixes. In the construction, Fe₃O₄@3-(Triethoxysilyl)propylmethacrylate@poly(4-Vinyl-1, 3-dioxolan-2-one-acrylic acid) (Fe₃O₄@MPS@p(VEC-AA)) were synthesized as pH-responsive polymer-modified magnetic nanoparticles (pMNPs) through free radical polymerization to increase the tunable interaction. Lf-binding aptamers were conjugated onto pMNPs through the reaction of amino-group in aptamer and epoxide-group in VEC, innovatively applied to prepare Lf-ApMNPs. On the basis of the synergistic effect of specific affinity of aptamer on Lf and tunable hydrophobic/hydrophilic property of pH-responsive polymer, Lf-ApMNPs presented good selectivity toward Lf, excellent adsorption capacity (as high as 233.9 mg g^-1), as well as good recoveries in the range 93.6-99.6% in Lf-related nutrition samples. Significantly, the introduction of pH-responsive monomer (AA) effectively regulated the adsorption-desorption process of Lf, with the function similar to a switch. Moreover, the good performances of Ct-ApMNPs toward α-Chymotrypsin showed that ApMNPs exhibited universality to other proteins through easily changing the binding aptamer, thereby offering a facile and efficient approach for specific enrichment and sensitive determination of targets in real biological samples.

Effects of Dietary Protein Levels on Growth Performance, Carcass Traits, Serum Metabolites, and Meat Composition of Tibetan Sheep during the Cold Season on the Qinghai-Tibetan Plateau

Simple Summary

The Tibetan sheep (Ovis aries) is an ovine breed well adapted to the harsh plateau environment. For a long period of time, Tibetan sheep farming has been an important pillar industry for native herders on the Qinghai-Tibetan Plateau. With the increasing demand for sheep meat and products, nutrition research has gained increasing importance. In this study, the effects of three different dietary protein levels (10.1%, 12.1%, and 14.1%) on growth performance, carcass traits, serum metabolites, and meat composition were investigated in Tibetan sheep during the cold season. The results showed that the diets containing 12.1% and 14.1% protein were better than a diet containing 10.1% protein for enhancing the growth performance, carcass performance, and meat products of the Tibetan sheep.

Abstract

Dietary protein is a critical nutrient that directly influences the health and production of livestock. Recent studies showed that protein supplements could enhance the growth performance of Tibetan sheep. However, there is a lack of information regarding the influence of dietary protein levels on carcass traits and meat composition. This study investigated the effects of dietary protein levels on growth performance, carcass traits, serum metabolites, and meat composition in Tibetan sheep during the cold season on the Qinghai-Tibetan Plateau. A total of eighteen 1-year-old, healthy, castrated Tibetan sheep with similar initial body weights (31.7 ± 0.72 kg) were randomly divided into three treatment groups with different dietary protein level (low protein (LP, 10.1%); medium protein (MP, 12.1%); high protein (HP, 14.1%)) diets. The results indicated that the Tibetan sheep fed with the MP and HP diets had greater final body weights (BWs), average daily gains (ADGs), and average daily feed intakes (ADFIs) (p < 0.05). The MP and HP diets also improved the hot carcass weight, net meat (including the fat) weight, and bone weight of the sheep significantly (p < 0.05). Besides, the dietary protein levels could significantly affect the serum concentrations of growth hormone (p < 0.05). The diameter of muscle fibers in the MP group was significantly greater than that in the LP group (p < 0.05), while the density of muscle fibers showed the opposite trend. The dietary protein levels only significantly (p < 0.05) influenced the ether extract content and profile content of the longissimus dorsi muscle but had no effect on other parameters of meat composition. In summary, our results indicate that dietary protein levels affect growth performance, carcass traits, and meat composition and that diets containing 12.1% and 14.1% protein are recommended to obtain better production performance and meat products in Tibetan sheep, rather than a diet containing 10.1% protein, during the cold season on the Qinghai-Tibetan Plateau.

Dietary supplements during the cold season increase rumen microbial abundance and improve rumen epithelium development in Tibetan sheep

Livestock on the Qinghai-Tibetan Plateau are faced with extreme harsh winters and are often in negative energy balance during this period. Dietary supplementation can improve growth performance of Tibetan sheep and, consequently, we hypothesized that it would also increase microbial abundance and rumen epithelium development. To test this hypothesis, we examined the effect of feed supplementation during the cold season on rumen microbes, fermentation, epithelium development, and absorptive capability in Tibetan sheep. Eighteen 1-yr-old ewes (BW = 29.4 ± 1.79, kg) were offered oat hay ad libitum for 60 d and divided randomly into three groups: 1) no supplement; control group (CON); 2) urea-molasses lick block supplement (BS); and 3) concentrate feed supplement (CS). The ADG of CS ewes (143.3, g/d) was greater (P < 0.05) than BS ewes (87.9, g/d), which was greater (P < 0.05) than CON ewes (44.5, g/d). Serum concentrations of GH, IGF-1, and IGF-2 in the CS and BS groups were greater than in the CON group (P < 0.05). Greater relative abundance of protozoa, Ruminococcus albus, Fibrobacter succinogenes, Streptococcus bovis, and Ruminobacter amylophilus was observed in the CS and BS groups than in the CON group (P < 0.05), and relative abundances of rumen fungi, Butyrivibrio fibrisolvens, and Prevotella ruminicola in the CS group were greater than in the BS and CON groups (P < 0.05). Ruminal total VFA, ammonia, and microbial protein concentrations in the CS and BS groups were greater than in the CON group (P < 0.05), and in the CS group were greater than in the BS group (P < 0.05). Ruminal papillae width and surface area in the CS and BS groups were greater than in the CON group (P < 0.05), while in the CS group were greater than in the BS group (P < 0.05). The mRNA expressions of IGFBP5, NHE1 (sodium/hydrogen antiporter, isoform 1), DRA (downregulated in adenoma), and Na+/K+-ATPase (sodium/potassium ATPase pump) in ruminal epithelium were greater in the CS and BS groups than in the CON group (P < 0.05), and in the CS group was greater than in the BS group (P < 0.05), while NHE3 (sodium/hydrogen antiporter, isoform 3), MCT1 (monocarboxylate transporter 1), and MCT4 (monocarboxylate transporter 4) mRNA expressions in the CS group were greater than in the BS and CON groups (P < 0.05). It was concluded that supplementing Tibetan sheep during the cold season increases rumen microbial abundance and improves fermentation parameters, rumen epithelium development, and absorptive capability.

High-Level Expression of Recombinant Bovine Lactoferrin in Pichia pastoris with Antimicrobial Activity

In this study, bovine lactoferrin (bLf), an iron-binding glycoprotein considered an important nutraceutical protein because of its several properties, was expressed in Pichia pastoris KM71-H under AOX1 promoter control, using pJ902 as the recombinant plasmid. Dot blotting analysis revealed the expression of recombinant bovine lactoferrin (rbLf) in Pichia pastoris. After Bach fermentation and purification by molecular exclusion, we obtained an expression yield of 3.5 g/L of rbLf. rbLf and predominantly pepsin-digested rbLf (rbLfcin) demonstrated antibacterial activity against Escherichia coli (E. coli) BL21DE3, Staphylococcus aureus (S. aureus) FRI137, and, in a smaller percentage, Pseudomonas aeruginosa (Ps. Aeruginosa) ATCC 27833. The successful expression and characterization of functional rbLf expressed in Pichia pastoris opens a prospect for the development of natural antimicrobial agents produced recombinantly.