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Extracellular vesicles (EVs) are nano-sized particles involved in intercellular communications that intrinsically possess many attributes as a modern drug delivery platform. Haematococcus pluvialis-derived EVs (HpEVs) can be potentially exploited as a high-value-added bioproduct during astaxanthin production. The encapsulation of HpEV cargo is a crucial key for the determination of their biological functions and therapeutic potentials. However, little is known about the composition of HpEVs, limiting insights into their biological properties and application characteristics. This study examined the protein composition of HpEVs from three growth phases of H. pluvialis grown under high light (350 µmol·m−2·s−1) and sodium acetate (45 mM) stresses. A total of 2038 proteins were identified, the majority of which were associated with biological processes including signal transduction, cell proliferation, cell metabolism, and the cell response to stress. Comparative analysis indicated that H. pluvialis cells sort variant proteins into HpEVs at different physiological states. It was revealed that HpEVs from the early growth stage of H. pluvialis contain more proteins associated with cellular functions involved in primary metabolite, cell division, and cellular energy metabolism, while HpEVs from the late growth stage of H. pluvialis were enriched in proteins involved in cell wall synthesis and secondary metabolism. This is the first study to report and compare the protein composition of HpEVs from different growth stages of H. pluvialis, providing important information on the development and production of functional microalgal-derived EVs. [ABSTRACT FROM AUTHOR]

Canthaxanthin is an important antioxidant with wide application prospects, and β-carotene ketolase is the key enzyme involved in the biosynthesis of canthaxanthin. However, the challenge for the soluble expression of β-carotene ketolase is that it hinders the large-scale production of carotenoids such as canthaxanthin and astaxanthin. Hence, this study employed several strategies aiming to improve the soluble expression of β-carotene ketolase and its activity, including selecting optimal expression vectors, screening induction temperatures, adding soluble expression tags, and adding a molecular chaperone. Results showed that all these strategies can improve the soluble expression and activity of β-carotene ketolase in Escherichia coli. In particular, the production of soluble β-carotene ketolase was increased 8 times, with a commercial molecular chaperon of pG-KJE8, leading to a 1.16-fold enhancement in the canthaxanthin production from β-carotene. Interestingly, pG-KJE8 could also enhance the soluble expression of β-carotene ketolase derived from eukaryotic microalgae. Further research showed that the production of canthaxanthin and echinenone was significantly improved by as many as 30.77 times when the pG-KJE8 was added, indicating the molecular chaperone performed differently among different β-carotene ketolase. This study not only laid a foundation for further research on the improvement of β-carotene ketolase activity but also provided new ideas for the improvement of carotenoid production. [ABSTRACT FROM AUTHOR]

As the world's largest farmed marine animal, oysters have enormous economic and ecological value. However, mass summer mortality caused by high temperature poses a significant threat to the oyster industry. To investigate the molecular mechanisms underlying heat adaptation and improve the heat tolerance ability in the oyster, we conducted genome-wide association analysis (GWAS) analysis on the F2 generation derived from the hybridization of relatively heat-tolerant Crassostrea angulata ♀ and heat-sensitive Crassostrea gigas ♂, which are the dominant cultured species in southern and northern China, respectively. Acute heat stress experiment (semi-lethal temperature 42 °C) demonstrated that the F2 population showed differentiation in heat tolerance, leading to extremely differentiated individuals (approximately 20% of individuals die within the first four days with 10% survival after 14 days). Genome resequencing and GWAS of the two divergent groups had identified 18 significant SNPs associated with heat tolerance, with 26 candidate genes located near these SNPs. Eleven candidate genes that may associate with the thermal resistance were identified, which were classified into five categories: temperature sensor (Trpm2), transcriptional factor (Gata3), protein ubiquitination (Ube2h, Usp50, Uchl3), heat shock subfamily (Dnajc17, Dnaja1), and transporters (Slc16a9, Slc16a14, Slc16a9, Slc16a2). The expressional differentiation of the above genes between C. gigas and C. angulata under sublethal temperature (37 °C) further supports their crucial role in coping with high temperature. Our results will contribute to understanding the molecular mechanisms underlying heat tolerance, and provide genetic markers for heat-resistance breeding in the oyster industry. [ABSTRACT FROM AUTHOR]

Crustins are crucial antimicrobial peptides in shrimp and play very important roles in innate immunity. In this research, a Type I crustin from Penaeus monodon (CarcininPm1) contained 108 residues was studied. The first 16 residues are signal peptide. It contained ten cysteines but did not form an intact whey acidic protein (WAP) domain. CarcininPm1 was observed to widely distribute in all tissues, while highly expressed in intestine. The expression level of CarcininPm1 in hepatopancreas was up-regulated 12- 20 times during 4-12h post challenged by Vibrio parahaemolyticus. And the transcription in heart, stomach and gills was also significantly enhanced at 4h post challenge. The mature peptide was expressed successfully in Eschericha coli by fusing to a SUMO protein, with protein production around 8 mg/mL. After cleavage with SUMO protease, carcininPm1 was obtained indicating its potential applications.

Lysozymes are crucial immune moleculars and play an important role in innate imunity. Here, a new lysozyme named Pmlyzi3 was found from the transcriptome data of Panaeus monodon. The Pmplyzi3 gene was 438bp in length, encoding a 146-residues peptide and the first 19 residues constituted a signal peptide. The mature peptide contained 10 cysteines and had 7 α-helixes in its N terminal. Moreover, it showed 88% identity with lysozyme-like protein from Penaeus vannamei. To express Pmlyzi3, pColdIV-SUMOPmlyzi3 plasmid was constructed by linked the Pmlyzi3 with SUMO tag, then transformed to Eschericha coli BL21 (DE3). By optimizing expression condition, SUMO-Pmlyzi3 was succeeded in expression in high level and purifing with Ni-NTA column. Following with SUMO protease excision, pure Pmlyzi3 was obtained by removing SUMO tag, which would be helped to study its function.