In nutrient-rich, vegetative conditions, the yeast Saccharomyces cerevisiae transports a resident protease, aminopeptidase I (API), to the vacuole by the cytoplasm to vacuole targeting (Cvt) pathway, thus contributing to the degradative capacity of this organelle. When cells subsequently encounter starvation conditions, the machinery that recruited precursor API (prAPI) also sequesters bulk cytosol for delivery, breakdown, and recycling in the vacuole by the autophagy pathway. Each of these overlapping alternative transport pathways is specifically mobilized depending on environmental cues. The basic mechanism of cargo packaging and delivery involves the formation of a double-membrane transport vesicle around prAPI and/or bulk cytosol. Upon completion, these Cvt and autophagic vesicles are targeted to the vacuole to allow delivery of their lumenal contents.Key questions remain regarding the origin and formation of the transport vesicle. In this study, we have cloned the APG9/CVT7 gene and characterized the gene product. Apg9p/Cvt7p is the first characterized integral membrane protein required for Cvt and autophagy transport. Biochemical and morphological analyses indicate that Apg9p/Cvt7p is localized to large perivacuolar punctate structures, but does not colocalize with typical endomembrane marker proteins. Finally, we have isolated a temperature conditional allele of APG9/CVT7 and demonstrate the direct role of Apg9p/Cvt7p in the formation of the Cvt and autophagic vesicles. From these results, we propose that Apg9p/Cvt7p may serve as a marker for a specialized compartment essential for these vesicle-mediated alternative targeting pathways.

Maillard reacted peptides (MRPs) were synthesized by conjugating a peptide fraction (1000–5000 Da) purified from soy protein hydrolyzate with galacturonic acid, glucosamine, xylose, fructose, or glucose. The effect of MRPs was investigated on human salt taste and on the chorda tympani (CT) taste nerve responses to NaCl in Sprague–Dawley rats, wild-type, and transient receptor potential vanilloid 1 (TRPV1) knockout mice. MRPs produced a biphasic effect on human salt taste perception and on the CT responses in rats and wild-type mice in the presence of NaCl + benzamil (Bz, a blocker of epithelial Na+ channels), enhancing the NaCl response at low concentrations and suppressing it at high concentrations. The effectiveness of MRPs as salt taste enhancers varied with the conjugated sugar moiety: galacturonic acid = glucosamine > xylose > fructose > glucose. The concentrations at which MRPs enhanced human salt taste were significantly lower than the concentrations of MRPs that produced increase in the NaCl CT response. Elevated temperature, resiniferatoxin, capsaicin, and ethanol produced additive effects on the NaCl CT responses in the presence of MRPs. Elevated temperature and ethanol also enhanced human salt taste perception. N-(3-methoxyphenyl)-4-chlorocinnamid (a blocker of TRPV1t) inhibited the Bz-insensitive NaCl CT responses in the absence and presence of MRPs. TRPV1 knockout mice demonstrated no Bz-insensitive NaCl CT response in the absence or presence of MRPs. The results suggest that MRPs modulate human salt taste and the NaCl + Bz CT responses by interacting with TRPV1t.

This study was conducted to investigate the changes in lipids and their effect on the taste of migaki-nishin during drying. Lipid was extracted from herring fillets on different drying stages to measure the degree of lipid oxidation and changes in lipid composition, and fatty acid profile. Peroxide value, carbonyl value and acid value of the lipids were significantly increased (P < 0.05) during the drying period. Marked increase in free fatty acids, with decreases in triglyceride and phospholipid content were observed in proportion to drying time and this result suggested that hydrolysis was induced by lipases and phospholipases. The decreases in polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were observed in the total lipids and phospholipid fraction. In addition, significant increase in PUFAs especially DHA was found in the free fatty acid fraction. Sensory evaluation showed that an addition of DHA to mentsuyu significantly (P < 0.05) enhances the intensities of thickness, mouthfulness and continuity. These results suggest that during drying period lipid oxidation was not only occurred but also lipolysis predominantly released DHA, which might have a contribution to kokumi enhancement of migaki-nishin.

ABSTRACT:Migaki-nishin is a Japanese term that refers to dried herring fillets. It is widely consumed in Japan due to its characteristic flavor enhancing properties. This study was conducted to investigate the changes in chemical and sensory properties of migaki-nishin during drying. Chemical analyses showed that extractive nitrogen and amount of peptides increased significantly (P < 0.05) up to the eighth day of drying and then slightly decreased by the tenth day. Glutamic acid, alanine, glycine, and histidine were the most abundant free amino acids and the largest increase was found in samples dried for 10 days. A decrease in Hunter's L* value (lightness) and increase in b* value (yellowness) as well as browning intensity suggested that nonenzymatic browning occurred in migaki-nishin during drying. Fluorescence spectrophotometric determination also revealed that Maillard reactions progressed throughout the drying period. In addition, available lysine content and free amino groups decreased significantly (P < 0.05) as drying progressed. Sensory evaluation showed that addition of water-soluble extracts to Japanese noodle soup (mentsuyu) linearly enhanced the flavor characteristics such as thickness, mouthfulness and continuity with the increased length of drying time.These results suggest that during the drying period, proteolysis as well as Maillard reaction products increased markedly, which might contribute to the characteristic taste and flavor of migaki-nishin.

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