Both vertebrates and invertebrates show a multitude of left–right asymmetries of brains and behaviors1. For example, cats, dogs, and many other species have a preferred paw when handling food2. But why should humans and other animals have lateralized brains? Based on a large comparative approach1, it is likely that asymmetries serve several purposes. First, by specializing on one limb or one side of its sensory system, the contralateral hemisphere goes through life-long cycles of motor and perceptual learning, thereby increasing the speed of processing and motor efficacy, decreasing reaction time, and enhancing discrimination ability. Second, by having two complementary, specialized hemispheres, neural processes are computed in parallel, thereby reducing cognitive redundancy1. For example, the right hemisphere excels in processing threat-related stimuli, providing the left visual field an advantage in reacting to a predator approaching from the left3. Here, we report that two-thirds of cats prefer a leftward sleeping position, giving their left visual field and thus their right brain half a privileged view of approaching animals without being obstructed by their own body.
The culture of Japanese eel (Anguilla japonica) is an important sector in Taiwan, but the shortage of eel fry disintegrated this sector. Giant mottled eel (A. marmorata) becomes an alternative species for aquaculture by degrees. However, few studies have been done on its biochemical characteristics and compositions. This study was to investigate the biochemical compositions in different sizes of giant mottled eels. Changes in chemical compositions and freshness index of giant mottled eel during storage were also studied to reveal the storage stability. In addition, the antioxidative activities of the tissue extracts were investigated in this study. Based on results of biochemical characteristics and functional compositions, the suitable utilization and processing of giant mottled eel was evaluated to develop new products. Crude protein in the muscle were ranged from 15.2~20.3%, and crude fat were 3.54~13.3%. The total amount of free amino acids (FAA) in the muscle was 93.8~176 mg/100g, and the major FAA were taurine, glutamic acid, glycine, alanine and lysine. The major nucleotide-related compound in the muscle was inosine 5’- monophosphate (IMP). Carnosine (Car) was the predominant small peptide, and its level reached 207~355 mg/100 g. The dominant fatty acid in the muscle was oleic acid (C18:1), followed by palmitic acid (C16:0). In addition, the contents of DHA (C22:6) and EPA (C20:5) were also high. The ratio of unsaturated fatty acid to total fatty acid was higher than that of saturated fatty acid. Giant mottled eel also contained abundant amount of minerals potassium, phosphorus and zinc, and vitamins A and E. The muscle pH value decreased at the early storage period and then increased after elongated storage. The total plate count (TPC) was closed to the limit value of 3×106 CFU/g during storage at 7°C and 25°C for 3 days and 1 day, respectively. For the limit value (25 mg/100 g) of volatile basic nitrogen (VBN), the storage time was 12 days and 16 hours, respectively. Trimethylamine (TMA) and K value also increased with increasing time. According to the results of organoleptic evaluation, TPC, VBN, K values, the self-life of giant mottled eel meat was 3 days and 8 hours during storage at 7°C and 25°C, respectively. During storage Car decreased, but b-alanine (b-Ala) and histidine (His) increased. Results showed that Car was degraded into b-Ala and His. Refrigeration storage and bleeding treatment could decrease the degradation rate. The methods including the scavenging effect of DPPH free radical, reducing power, chelating ability of Fe2+ and SOD activity are used to detect the antioxidative activities of giant mottled eel meat and its essence. Results showed that both extracts of tricholoacetic acid and phosphate buffer of eel meat and its essence possessed antioxidative activities. Eel essence had higher scavenging effect of DPPH free radical and reducing power than eel meat, but the latter had higher SOD activity. The roasted and seasoned products of giant mottled eel, Japanese eel and short-finned eel produced by the same factory showed VBN and TPC complied with national sanitation standards. According to the results of sensory evaluation, Japanese eel product had a higher score among three roasted products, but no significant difference was found. As compared with raw materials, the processed products of giant mottled eel had lower amounts of Car, His and β-Ala, but had higher amounts of glutamic acid, aspartic acid and total FAA. Seasoning sauce resulted in this difference. There were remarkable differences in total FAA amount and flavor intensity among different size of giant mottled eel products. Processing and seasoning conditions should be adjusted to obtain balanced seasoning products. Results of this project provided the data regarding the biochemical and functional properties of giant mottled eel for market promotion, and the reference for improving the quality of eel products. In addition, it also provided useful ways for suitable utilization and new product development.
