The pentatricopeptide repeat (PPR) proteins characterized by tandem repeats of a degenerate 35-amino-acid motif function in all aspects of organellar RNA metabolism, many of which are essential for organellar gene expression. In this study, we report the characterization of a fission yeast Schizosaccharomyces pombe PPR protein, Ppr10 and a novel Ppr10-associated protein, designated Mpa1. The ppr10 deletion mutant exhibits growth defects in respiratory media, and is dramatically impaired for viability during the late-stationary phase. Deletion of ppr10 affects the accumulation of specific mitochondrial mRNAs. Furthermore, deletion of ppr10 severely impairs mitochondrial protein synthesis, suggesting that Ppr10 plays a general role in mitochondrial protein synthesis. Ppr10 interacts with Mpa1 in vivo and in vitro and the two proteins colocalize in the mitochondrial matrix. The ppr10 and mpa1 deletion mutants exhibit very similar phenotypes. One of Mpa1's functions is to maintain the normal protein level of Ppr10 protein by protecting it from degradation by the mitochondrial matrix protease Lon1. Our findings suggest that Ppr10 functions as a general mitochondrial translational activator, likely through interaction with mitochondrial mRNAs and mitochondrial translation initiation factor Mti2, and that Ppr10 requires Mpa1 association for stability and function.

Yellowfin tuna is one of the favorite aquatic foods and possesses high economic value due to its unique pleasant flavor and good nutrition quality. Volatile and nonvolatile compounds that affect the flavor quality of tuna fish during canning process were investigated. The volatiles were analyzed by headspace solid‐phase microextraction combined with GC‐MS and the nonvolatiles were characterized by free amino acids, 5′‐nucleotides, and organic acids. Histidine, lysine, inosinic acid, tartaric acid, and succinic acid were the key taste compounds in tuna fish. A total of 7, 9, and 7 aroma‐active compounds were identified in raw, cooked, and canned fish samples, respectively. Decanal, nonanal, octanal, and (E)‐2‐nonenal were the predominant odorants in raw samples. Octanal, nonanal, 2‐pentylfuran, 1‐octen‐3‐ol, hexanal, and 2‐ethylfuran contributed to the characteristic flavor of cooked samples. 2‐Methyl‐3‐furanthiol, octanal, and nonanal were the main aroma‐active compounds detected in the canned samples responsible for the meaty and fatty odor. Practical applications Yellowfin tuna is one of the most commercial fish species for its excellent economic and nutritional value. The tuna fish processing methods are mainly frozen, cooked, smoked, and canned after thermal processing. The flavor components of tuna would vary greatly depending on the processing method. Although quality characteristics are very important for the economic value of tuna, there is scarce information comparing the volatile and nonvolatile compounds in tuna meat during canning process. This research could provide basis data for the process and the quality improvement of tuna products.

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Marine organisms are rich sources of bioactive components, which are often reported to have antihypertensive effects. However, the underlying mechanisms have yet to be fully identified. The aim of this study was to investigate the antihypertensive effect of enzymatic hydrolysis of blue mussel protein (HBMP) in rats. Peptides with in vitro ACE inhibitory activity were purified from HBMP by ultrafiltration, gel filtration chromatography and reversed-phase high performance liquid chromatography. And the amino acid sequences of isolated peptides were estimated to be Val-Trp, Leu-Gly-Trp, and Met-Val-Trp-Thr. To study its in vivo action, spontaneously hypertensive rats (SHRs) were orally administration with high- or low-dose of HBMP for 28 days. Major components of the renin-angiotensin (RAS) system in serum of SHRs from different groups were analyzed, and gene expression profiling were performed in the kidney of SHRs, using the Whole Rat Genome Oligonucleotide Microarray. Results indicated although genes involved in RAS system were not significantly altered, those related to blood coagulation system, cytokine and growth factor, and fatty acids metabolism were remarkablely changed. Several genes which were seldom reported to be implicated in pathogenesis of hypertension also showed significant expression alterations after oral administration of HBMP. These data provided valuable information for our understanding of the molecular mechanisms that underlie the potential antihypertensive activities of HBMP, and will contribute towards increased value-added utilization of blue mussel protein.