Pronounced effects of the basal frond portion of the kelp Saccharina japonica on gonad qualities of the sea urchin Mesocentrotus nudus from a barren

The Amino Acids Glutamic Acid and Alanine in Feed Increase the Alanine Content in Gonads of the Sea Urchin Mesocentrotus nudus

“…179 mg/100 g total alanine, respectively. These contents were high when compared with those of the central frond portion of S. japonica (total glutamic acid, 180 mg/100 g; total alanine, 74 mg/100 g), which increased the alanine content in the gonads of M. nudus to > 400 mg/100 g (Takagi et al, 2020c). The leaching of amino acids supplemented with diets after 3 days of immersion would lower the alanine content in the gonads of the Glu S and Ala S (< 200 mg/100 g).…”

“…Free Amino Acid Content of Gonads Approximately 1.0 g of gonadal tissue from each animal was quickly frozen at −30 • C, and the free amino acid (FAA) contents in the tissue were analyzed using the method of Murata et al (1994) improved by Takagi et al (2020c). FAAs can be categorized into four groups: umami-tasting (aspartic acid and glutamic acid), sweet-tasting (alanine, glycine, serine, proline, and threonine), bitter-tasting (arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, tyrosine, and valine) amino acids and others according to Kaneko et al (2009).…”

“…Before use in the feeding experiment, a total of 100 g of the control diet was weighed and freeze-dried using a freeze-dryer (FDU-1200, Tokyo Rikakikai Co. Ltd., Tokyo, Japan) for 72 h, and the crude protein, crude lipid, carbohydrate and ash contents in the diet (n = 5) were analyzed according to AOAC methods (AOAC, 1990). The total amino acid (TAA) (total of FAAs and amino acids in proteins and peptides) content of the control diet was analyzed according to Takagi et al (2020c).…”

“…Feeding of S. japonica fronds improves the taste of M. nudus gonads by enhancing the umami taste and sweetness (a high alanine content) and decreasing the arginine content (Takagi et al, 2017(Takagi et al, , 2019. Takagi et al (2020c) suggested that a high content of glutamic acid in the basal frond portion of S. japonica could be converted to alanine through digestion. No changes in the glycine and alanine contents in the gonads of Gly S and an increase in the alanine content in the gonads of Glu S indicate that a high glutamic acid content in feed increases the alanine content in gonads.…”

“…Phillips et al (2009) reported that the taste of gonads from the sea urchin E. chloroticus fed feeds containing high amounts of glutamic acid and glycine was sweeter than that of those fed diets containing high amounts of valine and methionine. Takagi et al (2020c) suggested that a high alanine content in gonads of M. nudus fed the basal frond portion of S. japonica is synthesized from glutamic acid, which is highly contained in the frond portion. Feeding of the sporophyll of U. pinnatifida, which has a markedly high alanine content, increased the alanine content in the gonads of M. nudus, suggesting that the excess alanine in the sporophyll was directly accumulated in the gonads (Takagi et al, 2020b).…”