Tomonari Kotani | Kagoshima University (original) (raw)

Papers by Tomonari Kotani

Research paper thumbnail of Effect of the duration of nutritional enrichment on the fatty acid composition of commonly used rotifers Brachionus plicatilis sp. complex and larviculture performance of red sea bream Pagrus major

Aquaculture Science, Jun 20, 2017

Research paper thumbnail of The involvement of Nile tilapia (Oreochromis niloticus) Neu4 sialidase in neural differentiation during early ontogenesis

Biochimie

Neurogenesis is an important process for the formation of the central nervous system during ontog... more Neurogenesis is an important process for the formation of the central nervous system during ontogenesis. Mammalian sialidases are involved in neurogenesis through desialylation of sialo-glycoconjugates. However, the significance of fish sialidases, unlike that of mammals, in neurogenesis has not been investigated. The present study focuses on Nile tilapia (Oreochromis niloticus) because of its unique profiles of sialidases related to enzymatic properties, subcellular localization, and tissue-specific gene expression. First, the fish were cultured under aphotic condition, which is known to cause the delayed development of the retina and brain in various fish. Next, we investigate the effect of aphotic condition on the levels of tilapia sialidases. Our results revealed that the tilapia showed a decrease in the number of ganglion cell in the retina. The expression level of neu4 mRNA is up-regulated in the eyes from tilapia reared in Dark accompanied by the increase of retinal differentiation markers. These results indicated that tilapia Neu4 is involved in retinal development in Nile tilapia. Furthermore, we tried to clarify the function of tilapia Neu4 in the neuronal cells using two neuroblast cell lines (SH-SY5Y and Neuro2a cell lines). Tilapia Neu4 decreased sialic acid level of both nuclear glycoproteins as well as glycolipids. Moreover, tilapia Neu4 accelerated neurite formation in both two neural cell lines and, increased the acetylcholinesterase activity, but it did not affect cell proliferation. Collectively, these results suggest that Neu4 accelerate neurite differentiation during ontogenesis in tilapia.

Research paper thumbnail of Threshold and spectral sensitivity of vision in medaka Oryzias latipes determined by a novel template wave matching method

Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology

Diets based on red clover silage (RCS) typically increase the concentration of polyunsaturated fa... more Diets based on red clover silage (RCS) typically increase the concentration of polyunsaturated fatty acids (PUFA) in ruminant meat and milk and lower the efficiency of N utilization compared with grass silages (GS). Four multiparous Finnish Ayrshire cows (108 d postpartum) fitted with rumen cannulas were used in a 4 × 4 Latin square design with 21-d periods to evaluate the effect of incremental replacement of GS with RCS on milk production, nutrient digestion, whole-body N metabolism, and milk fatty acid composition. Treatments comprised total mixed rations offered ad libitum, containing 600 g of forage/kg of diet dry matter (DM), with RCS replacing GS in ratios of 0:100, 33:67, 67:33, and 100:0 on a DM basis. Intake of DM and milk yield tended to be higher when RCS and GS were offered as a mixture than when fed alone. Forage species had no influence on the concentration or secretion of total milk fat, whereas replacing GS with RCS tended to decrease milk protein concentration and yield. Substitution of GS with RCS decreased linearly whole-tract apparent organic matter, fiber, and N digestion. Forage species had no effect on total nonammonia N at the omasum, whereas the flow of most AA at the omasum was higher for diets based on a mixture of forages. Replacing GS with RCS progressively lowered protein degradation in the rumen, increased linearly ruminal escape of dietary protein, and decreased linearly microbial protein synthesis. Incremental inclusion of RCS in the diet tended to lower whole-body N balance, increased linearly the proportion of dietary N excreted in feces and urine, and decreased linearly the utilization of dietary N for milk protein synthesis. Furthermore, replacing GS with RCS decreased linearly milk fat 4:0 to 8:0, 14:0, and 16:0 concentrations and increased linearly 18:2n-6 and 18:3n-3 concentrations, in the absence of changes in cis-9 18:1, cis-9,trans-11 18:2, or total trans fatty acid concentration. Inclusion of RCS in the diet progressively increased the apparent transfer of 18-carbon PUFA from the diet into milk, but had no effect on the amount of 18:2n-6 or 18:3n-3 at the omasum recovered in milk. In conclusion, forage species modified ruminal N metabolism, the flow of AA at the omasum, and whole-body N partitioning. A lower efficiency of N utilization for milk protein synthesis with RCS relative to GS was associated with decreased availability of AA for absorption, with some evidence of an imbalance in the supply of AA relative to requirements. Higher enrichment of PUFA in milk for diets based on RCS was related to an increased supply for absorption, with no indication that forage species substantially altered PUFA bioavailability.

Research paper thumbnail of 学術報告要旨 Cross-mating study of euryhaline rotifer Brachionus plicatilis strains as a meanes to develop useful strains for live food

Research paper thumbnail of Effect of primary cultivation method and population growth phase on nutritional enrichment of euryhaline rotifer Brachionus plicatilis

Research paper thumbnail of Effect of high concentration of dissolved oxygen in the rearing water on the rearing performance and stress response in red sea bream and Japanese eel

In order to keep high performance in the rearing of finfish, it is important to maintain the diss... more In order to keep high performance in the rearing of finfish, it is important to maintain the dissolved oxygen level high. Recently, the system or machine to generate the oxygen supersaturation water has been developed, e.g., Nano-bubble generator [1]. Although some effects of oxygen supersaturation water have already been known [2,3], enough information has not been obtained yet. This study aimed to clarify the effect of oxygen supersaturation water on the rearing performance of red sea bream and Japanese eel. And the stress reception under oxygen supersaturation was also investigated. The oxygen supersaturation water was generated with the unit for dissolution of high oxygen concentration (Sanso Electronic Co. Ltd., Japan).

Research paper thumbnail of Growth Performance, Growth-Related Genes, Digestibility, Digestive Enzyme Activity, Immune and Stress Responses of de novo Camelina Meal in Diets of Red Seabream (Pagrus major)

Animals, 2021

A 60-day experiment was designed to assess the effect of different ratios of fish meal (FM): came... more A 60-day experiment was designed to assess the effect of different ratios of fish meal (FM): camelina meal plant protein (CM) on growth response and relative gene expression of growth-promoting factors, feed utilization potency, digestive enzymes activities, apparent digestibility (ADC), stress response, non-specific immunity of Pagrus major. Four isonitrogenous (490.7 g/kg of crude protein) and isolipidic (91.5 g/kg total lipid) experimental diets were formulated and designated as camelina meal (CM0), soyabean meal (SBM20.5), CM20.5, and CM33 based on protein contents. At the end of the feed trial, significantly higher (p < 0.05) weight gain, specific growth rate, and feed intake but lower feed conversion ratio were recorded in fish fed CM0, SBM20.5, and CM20.5 than fish fed CM33. The lowest growth, feed utilization, enzyme activity, and digestibility were recorded in fish fed CM33. Significantly higher pepsin, amylase, and protease activities were observed in fish fed CM0, SBM2...

Research paper thumbnail of Effects of stocking density on performance of snubnose pompano juvenile (Trachinotus blochii) reared in recirculating system

Can Tho University Journal of Science, 2021

This study aimed to determine appropriate densities for rearing pompano juvenile (Trachinotus blo... more This study aimed to determine appropriate densities for rearing pompano juvenile (Trachinotus blochii) in a recirculating system. Four treatments of stocking density were evaluated including 500, 1.000, 1.500, and 2.000 inds/m3 in triplicate. The experimental system for pompano rearing was designed with 120-L tanks connected to 1 settling tank, 1 filter tank, 1 stone filter tank (contained 250 L of filter volume for each tank). The system was fulfilled with marine water at 30 ‰ of salinity and aerated continuously. Pompano were initially stocked at 0.07 ± 0.03 g/fish of body weight and daily fed using commercial pellet contained 55% of crude protein. After 30 days of rearing, the fish stocked at 1.000 individuals/m3 showed the best results in growth rate (0.060 g/day of DWG and 10.97 %/day of SGR) and was significantly higher than the treatment stocked at 1,500 and 2,000 inds/m3 (p < 0.05), however, no significant difference was observed between 1,000 and 500 treatments (p > ...

Research paper thumbnail of Enrichment effects of fermented by-product of Shochu distillery on Brachionus plicatilis sp. rotifer and larviculture performance in Japanese flounder (Paralichthys olivaceus)

Aquaculture, 2021

Abstract The effective use of distillery by-products of the shochu sweet potato has long been con... more Abstract The effective use of distillery by-products of the shochu sweet potato has long been considered as a rich source of protein, fiber, amino acids, fatty acids, probiotics with a great potential as a functional feed for animals. This study applied fermented by-product of Shochu distillery (FBPSD) and salmon roe emulsion oil for rotifer enrichment to evaluate its effects on the: (i) nutritional composition of rotifers and (ii) feeding responses of Paralichthys olivaceus larvae when fed with enriched rotifers. The salmon roe oil enrichment was set as a control diet and FBPSD was supplemented at different doses (1, 5 and 10 % based on the salmon roe oil amount). The results showed that the rotifers supplemented with FBPSD at 5 and 10 % significantly enhanced protein, carbohydrate, and HUFA content. Similarly, the activity and expression profiles of targeted enzymes including trypsin, chymotrypsin, lipase and amylase effectively responded at early and middle-metamorphosis of the larvae to 5 and 10 % enrichment regiment. These two treatments were also found to be better supported in energy metabolism evidenced by Cytochrome-C-Oxidase (cox) and ATPase-pk (atp) gene expression in the larvae. Moreover, the expression levels of immune-related genes (IL-10, IL-1β, TNF-α, P2Y6) and antioxidant-related genes (SOD, CAT) were significantly improved at 5 and 10 % of FBPSD. Cessation of feeding and delay in growth during the metamorphic process was also molecularly demonstrated. Larvae suffered low survival (24.5 – 25.3 %) in control and 1 % supplementation of FBPSD, but significantly improved at 5 and 10 % (36.4 - 38.7%). However, the growth performance of larval fish was not remarkable after 40 days of culture. The results of this study revealed that FBPSD could be considered as a potential supplementary enrichment for live feed in fish larviculture, especially at 5 and 10 % rotifer enrichment dosage.

Research paper thumbnail of An integrative description of the digestive system morphology and function of Japanese flounder (Paralichthys olivaceus) during early ontogenetic development

Research paper thumbnail of Establishment and characterization of Neu1-knockout zebrafish and its abnormal clinical phenotypes

Biochemical Journal, 2020

Mammalian sialidase Neu1 is involved in various physiological functions, including cell adhesion,... more Mammalian sialidase Neu1 is involved in various physiological functions, including cell adhesion, differentiation, cancer metastasis, and diabetes through lysosomal catabolism and desialylation of glycoproteins at the plasma membrane. Various animal models have been established to further explore the functions of vertebrate Neu1. The present study focused on zebrafish (Danio rerio) belonging to Cypriniformes as an experimental animal model with neu1 gene deficiency. The results revealed that the zebrafish Neu1 desialyzed both α2–3 and α2–6 sialic acid linkages from oligosaccharides and glycoproteins at pH 4.5, and it is highly conserved with other fish species and mammalian Neu1. Furthermore, Neu1-knockout zebrafish (Neu1-KO) was established through CRISPR/Cas9 genome editing. Neu1-KO fish exhibited slight abnormal embryogenesis with the accumulation of pleural effusion; however, no embryonic lethality was observed. Although Neu1-KO fish were able to be maintained as homozygous, the...

Research paper thumbnail of Neuropeptide Y deficiency induces anxiety-like behaviours in zebrafish (Danio rerio)

Scientific Reports, 2020

Neuropeptide Y (NPY) controls energy homeostasis including orexigenic actions in mammalians and n... more Neuropeptide Y (NPY) controls energy homeostasis including orexigenic actions in mammalians and non-mammalians. Recently, NPY has attracted attention as a mediator of emotional behaviour and psychosomatic diseases. However, its functions are not fully understood. We established npy gene-deficient (NPY-KO) zebrafish (Danio rerio) to assess the relationship between NPY and emotional behaviours. The NPY-KO zebrafish exhibited similar growth, but pomc and avp mRNA levels in the brain were higher as compared to wild-type fish. NPY-KO zebrafish exhibited several anxiety-like behaviours, such as a decrease in social interaction in mirror test and decreased locomotion in black-white test. The acute cold stress-treated NPY-KO zebrafish exhibited anxiety-like behaviours such as remaining stationary and swimming along the side of the tank in the mirror test. Moreover, expression levels of anxiety-associated genes (orx and cck) and catecholamine production (gr, mr, th1 and th2) were significant...

Research paper thumbnail of Comparative study on early digestive enzyme activity and expression in red sea bream (Pagrus major) fed on live feed and micro-diet

Aquaculture, 2019

Comparative study on early digestive enzyme activity and expression in red sea bream (Pagrus majo... more Comparative study on early digestive enzyme activity and expression in red sea bream (Pagrus major) fed on live feed and micro-diet, Aquaculture (2019), doi: https://doi.org/10.1016/ j.aquaculture.2019.734721. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Research paper thumbnail of Effect of zinc and manganese supplementation in Artemia on growth and vertebral deformity in red sea bream (Pagrus major) larvae

Aquaculture, 2008

Feeding trials were carried out to determine the effects of zinc (Zn) and manganese (Mn) suppleme... more Feeding trials were carried out to determine the effects of zinc (Zn) and manganese (Mn) supplementation in Artemia on growth, survival, body composition and skeletal deformity of red sea bream larvae. Triplicate groups of red sea bream larvae from 15-30 day post-hatching (dph) were fed four types of Artemia enriched with Zn (Z), Mn (M), both Zn and Mn (ZM) and without Zn or Mn (control). At 30 dph, significantly higher (P b 0.05) growth performance of the fish was recorded in M group (TL = 15.60 ± 0.45 mm) compared to that of the control (TL = 14.90 ± 0.41 mm). Fish fed Artemia supplemented with only Zn and with both Zn and Mn showed similar growth performance compared to that of the control. Survival of the fish was not affected either by Zn or Mn supplementation. Increased Mn or both Zn and Mn in Artemia nauplii significantly elevated (P b 0.05) crude lipid content in 30dph juvenile compared to that in the Z group. At 30 dph, Mn content in juvenile of M and ZM groups was significantly higher (P b 0.05) compared to that in the other groups. Similarly, Zn content in the Z group was significantly higher (P b 0.05) compared to that in the M and control groups. Skeletal deformities in the experimental fish at 30 dph were highest (P b 0.05) in the control group and were significantly improved by supplementation with Zn and Mn. The major skeletal deformities were observed in the vertebral column, neural and hemal spines. In the vertebral column, occurrence of deformities in the neck, hemal and preural were higher than in other regions. The results of the present study demonstrated that maintenance of Mn level in Artemia nauplii from 12 to 42.8 µg g − 1 (dry-matter basis) improved growth performance of red sea bream larvae. Zn and Mn supplementation in Artemia promoted normal skeletal development of red sea bream larvae.

Research paper thumbnail of DHA Accumulation in the Polar Lipids of the Euryhaline Copepod Pseudodiaptomus inopinus and Its Transfer to Red Sea Bream Pagrus major Larvae

Frontiers in Marine Science

The euryhaline copepod Pseudodiaptomus inopinus play important roles in coastal waters as vectors... more The euryhaline copepod Pseudodiaptomus inopinus play important roles in coastal waters as vectors of docosahexanoic (DHA) and eicosapentaenoic (EPA) acids for larval fish. While DHA and EPA in polar lipids (PLs) are more effective for fish larval development than non-polar lipid forms (NLs), there is little knowledge how much these lipids are accumulated in copepods from microalgae and are effective for early development of fish larvae. We report PLs fatty acid profiles of P. inopinus fed DHA-poor microalgae and evaluate its significance as a food source for larvae development of Pagrus major, compared with DHA-enriched rotifers. Copepods and rotifers were fed a mixed diet of three algal species (Phaeodactylum tricornutum, Tisochrysis lutea, and Pavlova lutheri), in addition of DHA-supplemented Super Fresh Chlorella (SFC) for rotifers. Compared with SFC, the algal mixture had higher EPA but lower DHA. Copepods had higher DHA and EPA in total lipids than rotifers fed each diet. Copep...

Research paper thumbnail of <I>Nannochloropsis oculata</I> のバッチ培養における動物プランクトンの餌料として好適な培養状態を推定するための分光光度法の応用

Research paper thumbnail of Enrichment of Rotifers and Its Effect on the Growth and Survival of Fish Larvae

Rotifers, 2017

In order to improve the survival and growth of aquacultured finfish larvae, nutritional enrichmen... more In order to improve the survival and growth of aquacultured finfish larvae, nutritional enrichment of rotifers is necessary. In the development of methodologies for material and process, n-3HUFAs especially EPA and DHA were the main focused nutrients for enrichment. Although the addition of those fatty acids to rotifer was conducted in vitro, the enrichment of DHA or EPA to phospholipid was suggested recently, as well as the optimum ratio among DHA, EPA, and arachidonic acid. On the other hand, other nutrients, e.g., taurine, vitamin A, and some minerals, have also been suggested to enrich rotifers. These mean that not only specific nutrients but also the balance among nutrients is important to enrich rotifers nutritionally and improve the performance of cultured finfishes. Moreover, the influence by rotifer culture method and protocol and the development of enrichment method should be taken into consideration for improving the efficiency of enrichment. Future studies should investigate whether rotifers can acquire all these nutrients from the balanced nutrition.

Research paper thumbnail of The Current Status of the Morphological Classification of Rotifer Strains Used in Aquaculture

Morphological variations of euryhaline rotifers Brachionus, including lorica size and form, have ... more Morphological variations of euryhaline rotifers Brachionus, including lorica size and form, have been recognized since they have been used as the live food for finfish larvae. Based on these morphological variations, rotifer populations were divided into different morphotypes. Finfish larvae ingest suitable size of feed fitting to their mouth size. Therefore, the size of rotifer fed to larval fishes should also be optimum for the larval mouth. Newly aquacultured fish species increased dramatically; thus, rotifers with optimum size for these species are required. In order to obtain such rotifers, the search for a new type or population and artificial manipulation to change the size has been attempted. Consequently, the newly found and developed rotifer species for aquaculture were applied to the larval rearing of fish species with small mouth. Up to date, cross-mating is the only method to develop new rotifer strains. Therefore, strict management is necessary to avoid the contaminati...

Research paper thumbnail of Suitability of Tisochrysis lutea at different growth phases as an enrichment diet for Brachionus plicatilis sp. complex rotifers

Journal of Applied Phycology

In larviculture of marine finfish, Tisochrysis lutea cultured cells have a potential to be a sust... more In larviculture of marine finfish, Tisochrysis lutea cultured cells have a potential to be a sustainable enrichment diet for rotifers due to its de novo synthesis of docosahexaenoic acid (DHA). To improve its effectiveness in rotifer enrichment for later larviculture, we determined which growth phase of T. lutea can enhance DHA in polar lipids (PLs) in Brachionus plicatilis sp. complex rotifers without reducing their vigor. Tisochrysis lutea was harvested at logarithmic growth phase, deceleration growth phase, and stationary phase. The ambient concentrations of phosphorus (P) and nitrogen (N), and fatty acid composition of microalgae were measured. P was limited between logarithmic and deceleration growth phases, followed by N starvation in stationary phase. Total lipid DHA was lowest in logarithmic growth phase, whereas DHA levels increased in deceleration growth phase and maintained at high levels even in stationary phase. PL-DHA also increased during deceleration growth phase, although its abundance dropped during stationary phase. In a rotifer enrichment trial, T. lutea harvested in each phase were fed to B. plicatilis sp. complex rotifers for 12 h. The highest PL-DHA value for cells in deceleration growth phase reflected the concentrations of the rotifers. No significant differences were found in rotifer growth rate and egg ratio. Rotifers fed cells in deceleration growth phase exhibited higher swimming speeds than those fed the other cells, potentially linking to increased larval capture success. Therefore, we recommend the deceleration growth phase as an optimal timing for T. lutea harvest for the effective enrichment of B. plicatilis sp. complex rotifers.

Research paper thumbnail of Novel Nile tilapia Neu1 sialidases: Molecular cloning and biochemical characterization of the sialidases Neu1a and Neu1b

Research paper thumbnail of Effect of the duration of nutritional enrichment on the fatty acid composition of commonly used rotifers Brachionus plicatilis sp. complex and larviculture performance of red sea bream Pagrus major

Aquaculture Science, Jun 20, 2017

Research paper thumbnail of The involvement of Nile tilapia (Oreochromis niloticus) Neu4 sialidase in neural differentiation during early ontogenesis

Biochimie

Neurogenesis is an important process for the formation of the central nervous system during ontog... more Neurogenesis is an important process for the formation of the central nervous system during ontogenesis. Mammalian sialidases are involved in neurogenesis through desialylation of sialo-glycoconjugates. However, the significance of fish sialidases, unlike that of mammals, in neurogenesis has not been investigated. The present study focuses on Nile tilapia (Oreochromis niloticus) because of its unique profiles of sialidases related to enzymatic properties, subcellular localization, and tissue-specific gene expression. First, the fish were cultured under aphotic condition, which is known to cause the delayed development of the retina and brain in various fish. Next, we investigate the effect of aphotic condition on the levels of tilapia sialidases. Our results revealed that the tilapia showed a decrease in the number of ganglion cell in the retina. The expression level of neu4 mRNA is up-regulated in the eyes from tilapia reared in Dark accompanied by the increase of retinal differentiation markers. These results indicated that tilapia Neu4 is involved in retinal development in Nile tilapia. Furthermore, we tried to clarify the function of tilapia Neu4 in the neuronal cells using two neuroblast cell lines (SH-SY5Y and Neuro2a cell lines). Tilapia Neu4 decreased sialic acid level of both nuclear glycoproteins as well as glycolipids. Moreover, tilapia Neu4 accelerated neurite formation in both two neural cell lines and, increased the acetylcholinesterase activity, but it did not affect cell proliferation. Collectively, these results suggest that Neu4 accelerate neurite differentiation during ontogenesis in tilapia.

Research paper thumbnail of Threshold and spectral sensitivity of vision in medaka Oryzias latipes determined by a novel template wave matching method

Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology

Diets based on red clover silage (RCS) typically increase the concentration of polyunsaturated fa... more Diets based on red clover silage (RCS) typically increase the concentration of polyunsaturated fatty acids (PUFA) in ruminant meat and milk and lower the efficiency of N utilization compared with grass silages (GS). Four multiparous Finnish Ayrshire cows (108 d postpartum) fitted with rumen cannulas were used in a 4 × 4 Latin square design with 21-d periods to evaluate the effect of incremental replacement of GS with RCS on milk production, nutrient digestion, whole-body N metabolism, and milk fatty acid composition. Treatments comprised total mixed rations offered ad libitum, containing 600 g of forage/kg of diet dry matter (DM), with RCS replacing GS in ratios of 0:100, 33:67, 67:33, and 100:0 on a DM basis. Intake of DM and milk yield tended to be higher when RCS and GS were offered as a mixture than when fed alone. Forage species had no influence on the concentration or secretion of total milk fat, whereas replacing GS with RCS tended to decrease milk protein concentration and yield. Substitution of GS with RCS decreased linearly whole-tract apparent organic matter, fiber, and N digestion. Forage species had no effect on total nonammonia N at the omasum, whereas the flow of most AA at the omasum was higher for diets based on a mixture of forages. Replacing GS with RCS progressively lowered protein degradation in the rumen, increased linearly ruminal escape of dietary protein, and decreased linearly microbial protein synthesis. Incremental inclusion of RCS in the diet tended to lower whole-body N balance, increased linearly the proportion of dietary N excreted in feces and urine, and decreased linearly the utilization of dietary N for milk protein synthesis. Furthermore, replacing GS with RCS decreased linearly milk fat 4:0 to 8:0, 14:0, and 16:0 concentrations and increased linearly 18:2n-6 and 18:3n-3 concentrations, in the absence of changes in cis-9 18:1, cis-9,trans-11 18:2, or total trans fatty acid concentration. Inclusion of RCS in the diet progressively increased the apparent transfer of 18-carbon PUFA from the diet into milk, but had no effect on the amount of 18:2n-6 or 18:3n-3 at the omasum recovered in milk. In conclusion, forage species modified ruminal N metabolism, the flow of AA at the omasum, and whole-body N partitioning. A lower efficiency of N utilization for milk protein synthesis with RCS relative to GS was associated with decreased availability of AA for absorption, with some evidence of an imbalance in the supply of AA relative to requirements. Higher enrichment of PUFA in milk for diets based on RCS was related to an increased supply for absorption, with no indication that forage species substantially altered PUFA bioavailability.

Research paper thumbnail of 学術報告要旨 Cross-mating study of euryhaline rotifer Brachionus plicatilis strains as a meanes to develop useful strains for live food

Research paper thumbnail of Effect of primary cultivation method and population growth phase on nutritional enrichment of euryhaline rotifer Brachionus plicatilis

Research paper thumbnail of Effect of high concentration of dissolved oxygen in the rearing water on the rearing performance and stress response in red sea bream and Japanese eel

In order to keep high performance in the rearing of finfish, it is important to maintain the diss... more In order to keep high performance in the rearing of finfish, it is important to maintain the dissolved oxygen level high. Recently, the system or machine to generate the oxygen supersaturation water has been developed, e.g., Nano-bubble generator [1]. Although some effects of oxygen supersaturation water have already been known [2,3], enough information has not been obtained yet. This study aimed to clarify the effect of oxygen supersaturation water on the rearing performance of red sea bream and Japanese eel. And the stress reception under oxygen supersaturation was also investigated. The oxygen supersaturation water was generated with the unit for dissolution of high oxygen concentration (Sanso Electronic Co. Ltd., Japan).

Research paper thumbnail of Growth Performance, Growth-Related Genes, Digestibility, Digestive Enzyme Activity, Immune and Stress Responses of de novo Camelina Meal in Diets of Red Seabream (Pagrus major)

Animals, 2021

A 60-day experiment was designed to assess the effect of different ratios of fish meal (FM): came... more A 60-day experiment was designed to assess the effect of different ratios of fish meal (FM): camelina meal plant protein (CM) on growth response and relative gene expression of growth-promoting factors, feed utilization potency, digestive enzymes activities, apparent digestibility (ADC), stress response, non-specific immunity of Pagrus major. Four isonitrogenous (490.7 g/kg of crude protein) and isolipidic (91.5 g/kg total lipid) experimental diets were formulated and designated as camelina meal (CM0), soyabean meal (SBM20.5), CM20.5, and CM33 based on protein contents. At the end of the feed trial, significantly higher (p < 0.05) weight gain, specific growth rate, and feed intake but lower feed conversion ratio were recorded in fish fed CM0, SBM20.5, and CM20.5 than fish fed CM33. The lowest growth, feed utilization, enzyme activity, and digestibility were recorded in fish fed CM33. Significantly higher pepsin, amylase, and protease activities were observed in fish fed CM0, SBM2...

Research paper thumbnail of Effects of stocking density on performance of snubnose pompano juvenile (Trachinotus blochii) reared in recirculating system

Can Tho University Journal of Science, 2021

This study aimed to determine appropriate densities for rearing pompano juvenile (Trachinotus blo... more This study aimed to determine appropriate densities for rearing pompano juvenile (Trachinotus blochii) in a recirculating system. Four treatments of stocking density were evaluated including 500, 1.000, 1.500, and 2.000 inds/m3 in triplicate. The experimental system for pompano rearing was designed with 120-L tanks connected to 1 settling tank, 1 filter tank, 1 stone filter tank (contained 250 L of filter volume for each tank). The system was fulfilled with marine water at 30 ‰ of salinity and aerated continuously. Pompano were initially stocked at 0.07 ± 0.03 g/fish of body weight and daily fed using commercial pellet contained 55% of crude protein. After 30 days of rearing, the fish stocked at 1.000 individuals/m3 showed the best results in growth rate (0.060 g/day of DWG and 10.97 %/day of SGR) and was significantly higher than the treatment stocked at 1,500 and 2,000 inds/m3 (p < 0.05), however, no significant difference was observed between 1,000 and 500 treatments (p > ...

Research paper thumbnail of Enrichment effects of fermented by-product of Shochu distillery on Brachionus plicatilis sp. rotifer and larviculture performance in Japanese flounder (Paralichthys olivaceus)

Aquaculture, 2021

Abstract The effective use of distillery by-products of the shochu sweet potato has long been con... more Abstract The effective use of distillery by-products of the shochu sweet potato has long been considered as a rich source of protein, fiber, amino acids, fatty acids, probiotics with a great potential as a functional feed for animals. This study applied fermented by-product of Shochu distillery (FBPSD) and salmon roe emulsion oil for rotifer enrichment to evaluate its effects on the: (i) nutritional composition of rotifers and (ii) feeding responses of Paralichthys olivaceus larvae when fed with enriched rotifers. The salmon roe oil enrichment was set as a control diet and FBPSD was supplemented at different doses (1, 5 and 10 % based on the salmon roe oil amount). The results showed that the rotifers supplemented with FBPSD at 5 and 10 % significantly enhanced protein, carbohydrate, and HUFA content. Similarly, the activity and expression profiles of targeted enzymes including trypsin, chymotrypsin, lipase and amylase effectively responded at early and middle-metamorphosis of the larvae to 5 and 10 % enrichment regiment. These two treatments were also found to be better supported in energy metabolism evidenced by Cytochrome-C-Oxidase (cox) and ATPase-pk (atp) gene expression in the larvae. Moreover, the expression levels of immune-related genes (IL-10, IL-1β, TNF-α, P2Y6) and antioxidant-related genes (SOD, CAT) were significantly improved at 5 and 10 % of FBPSD. Cessation of feeding and delay in growth during the metamorphic process was also molecularly demonstrated. Larvae suffered low survival (24.5 – 25.3 %) in control and 1 % supplementation of FBPSD, but significantly improved at 5 and 10 % (36.4 - 38.7%). However, the growth performance of larval fish was not remarkable after 40 days of culture. The results of this study revealed that FBPSD could be considered as a potential supplementary enrichment for live feed in fish larviculture, especially at 5 and 10 % rotifer enrichment dosage.

Research paper thumbnail of An integrative description of the digestive system morphology and function of Japanese flounder (Paralichthys olivaceus) during early ontogenetic development

Research paper thumbnail of Establishment and characterization of Neu1-knockout zebrafish and its abnormal clinical phenotypes

Biochemical Journal, 2020

Mammalian sialidase Neu1 is involved in various physiological functions, including cell adhesion,... more Mammalian sialidase Neu1 is involved in various physiological functions, including cell adhesion, differentiation, cancer metastasis, and diabetes through lysosomal catabolism and desialylation of glycoproteins at the plasma membrane. Various animal models have been established to further explore the functions of vertebrate Neu1. The present study focused on zebrafish (Danio rerio) belonging to Cypriniformes as an experimental animal model with neu1 gene deficiency. The results revealed that the zebrafish Neu1 desialyzed both α2–3 and α2–6 sialic acid linkages from oligosaccharides and glycoproteins at pH 4.5, and it is highly conserved with other fish species and mammalian Neu1. Furthermore, Neu1-knockout zebrafish (Neu1-KO) was established through CRISPR/Cas9 genome editing. Neu1-KO fish exhibited slight abnormal embryogenesis with the accumulation of pleural effusion; however, no embryonic lethality was observed. Although Neu1-KO fish were able to be maintained as homozygous, the...

Research paper thumbnail of Neuropeptide Y deficiency induces anxiety-like behaviours in zebrafish (Danio rerio)

Scientific Reports, 2020

Neuropeptide Y (NPY) controls energy homeostasis including orexigenic actions in mammalians and n... more Neuropeptide Y (NPY) controls energy homeostasis including orexigenic actions in mammalians and non-mammalians. Recently, NPY has attracted attention as a mediator of emotional behaviour and psychosomatic diseases. However, its functions are not fully understood. We established npy gene-deficient (NPY-KO) zebrafish (Danio rerio) to assess the relationship between NPY and emotional behaviours. The NPY-KO zebrafish exhibited similar growth, but pomc and avp mRNA levels in the brain were higher as compared to wild-type fish. NPY-KO zebrafish exhibited several anxiety-like behaviours, such as a decrease in social interaction in mirror test and decreased locomotion in black-white test. The acute cold stress-treated NPY-KO zebrafish exhibited anxiety-like behaviours such as remaining stationary and swimming along the side of the tank in the mirror test. Moreover, expression levels of anxiety-associated genes (orx and cck) and catecholamine production (gr, mr, th1 and th2) were significant...

Research paper thumbnail of Comparative study on early digestive enzyme activity and expression in red sea bream (Pagrus major) fed on live feed and micro-diet

Aquaculture, 2019

Comparative study on early digestive enzyme activity and expression in red sea bream (Pagrus majo... more Comparative study on early digestive enzyme activity and expression in red sea bream (Pagrus major) fed on live feed and micro-diet, Aquaculture (2019), doi: https://doi.org/10.1016/ j.aquaculture.2019.734721. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Research paper thumbnail of Effect of zinc and manganese supplementation in Artemia on growth and vertebral deformity in red sea bream (Pagrus major) larvae

Aquaculture, 2008

Feeding trials were carried out to determine the effects of zinc (Zn) and manganese (Mn) suppleme... more Feeding trials were carried out to determine the effects of zinc (Zn) and manganese (Mn) supplementation in Artemia on growth, survival, body composition and skeletal deformity of red sea bream larvae. Triplicate groups of red sea bream larvae from 15-30 day post-hatching (dph) were fed four types of Artemia enriched with Zn (Z), Mn (M), both Zn and Mn (ZM) and without Zn or Mn (control). At 30 dph, significantly higher (P b 0.05) growth performance of the fish was recorded in M group (TL = 15.60 ± 0.45 mm) compared to that of the control (TL = 14.90 ± 0.41 mm). Fish fed Artemia supplemented with only Zn and with both Zn and Mn showed similar growth performance compared to that of the control. Survival of the fish was not affected either by Zn or Mn supplementation. Increased Mn or both Zn and Mn in Artemia nauplii significantly elevated (P b 0.05) crude lipid content in 30dph juvenile compared to that in the Z group. At 30 dph, Mn content in juvenile of M and ZM groups was significantly higher (P b 0.05) compared to that in the other groups. Similarly, Zn content in the Z group was significantly higher (P b 0.05) compared to that in the M and control groups. Skeletal deformities in the experimental fish at 30 dph were highest (P b 0.05) in the control group and were significantly improved by supplementation with Zn and Mn. The major skeletal deformities were observed in the vertebral column, neural and hemal spines. In the vertebral column, occurrence of deformities in the neck, hemal and preural were higher than in other regions. The results of the present study demonstrated that maintenance of Mn level in Artemia nauplii from 12 to 42.8 µg g − 1 (dry-matter basis) improved growth performance of red sea bream larvae. Zn and Mn supplementation in Artemia promoted normal skeletal development of red sea bream larvae.

Research paper thumbnail of DHA Accumulation in the Polar Lipids of the Euryhaline Copepod Pseudodiaptomus inopinus and Its Transfer to Red Sea Bream Pagrus major Larvae

Frontiers in Marine Science

The euryhaline copepod Pseudodiaptomus inopinus play important roles in coastal waters as vectors... more The euryhaline copepod Pseudodiaptomus inopinus play important roles in coastal waters as vectors of docosahexanoic (DHA) and eicosapentaenoic (EPA) acids for larval fish. While DHA and EPA in polar lipids (PLs) are more effective for fish larval development than non-polar lipid forms (NLs), there is little knowledge how much these lipids are accumulated in copepods from microalgae and are effective for early development of fish larvae. We report PLs fatty acid profiles of P. inopinus fed DHA-poor microalgae and evaluate its significance as a food source for larvae development of Pagrus major, compared with DHA-enriched rotifers. Copepods and rotifers were fed a mixed diet of three algal species (Phaeodactylum tricornutum, Tisochrysis lutea, and Pavlova lutheri), in addition of DHA-supplemented Super Fresh Chlorella (SFC) for rotifers. Compared with SFC, the algal mixture had higher EPA but lower DHA. Copepods had higher DHA and EPA in total lipids than rotifers fed each diet. Copep...

Research paper thumbnail of <I>Nannochloropsis oculata</I> のバッチ培養における動物プランクトンの餌料として好適な培養状態を推定するための分光光度法の応用

Research paper thumbnail of Enrichment of Rotifers and Its Effect on the Growth and Survival of Fish Larvae

Rotifers, 2017

In order to improve the survival and growth of aquacultured finfish larvae, nutritional enrichmen... more In order to improve the survival and growth of aquacultured finfish larvae, nutritional enrichment of rotifers is necessary. In the development of methodologies for material and process, n-3HUFAs especially EPA and DHA were the main focused nutrients for enrichment. Although the addition of those fatty acids to rotifer was conducted in vitro, the enrichment of DHA or EPA to phospholipid was suggested recently, as well as the optimum ratio among DHA, EPA, and arachidonic acid. On the other hand, other nutrients, e.g., taurine, vitamin A, and some minerals, have also been suggested to enrich rotifers. These mean that not only specific nutrients but also the balance among nutrients is important to enrich rotifers nutritionally and improve the performance of cultured finfishes. Moreover, the influence by rotifer culture method and protocol and the development of enrichment method should be taken into consideration for improving the efficiency of enrichment. Future studies should investigate whether rotifers can acquire all these nutrients from the balanced nutrition.

Research paper thumbnail of The Current Status of the Morphological Classification of Rotifer Strains Used in Aquaculture

Morphological variations of euryhaline rotifers Brachionus, including lorica size and form, have ... more Morphological variations of euryhaline rotifers Brachionus, including lorica size and form, have been recognized since they have been used as the live food for finfish larvae. Based on these morphological variations, rotifer populations were divided into different morphotypes. Finfish larvae ingest suitable size of feed fitting to their mouth size. Therefore, the size of rotifer fed to larval fishes should also be optimum for the larval mouth. Newly aquacultured fish species increased dramatically; thus, rotifers with optimum size for these species are required. In order to obtain such rotifers, the search for a new type or population and artificial manipulation to change the size has been attempted. Consequently, the newly found and developed rotifer species for aquaculture were applied to the larval rearing of fish species with small mouth. Up to date, cross-mating is the only method to develop new rotifer strains. Therefore, strict management is necessary to avoid the contaminati...

Research paper thumbnail of Suitability of Tisochrysis lutea at different growth phases as an enrichment diet for Brachionus plicatilis sp. complex rotifers

Journal of Applied Phycology

In larviculture of marine finfish, Tisochrysis lutea cultured cells have a potential to be a sust... more In larviculture of marine finfish, Tisochrysis lutea cultured cells have a potential to be a sustainable enrichment diet for rotifers due to its de novo synthesis of docosahexaenoic acid (DHA). To improve its effectiveness in rotifer enrichment for later larviculture, we determined which growth phase of T. lutea can enhance DHA in polar lipids (PLs) in Brachionus plicatilis sp. complex rotifers without reducing their vigor. Tisochrysis lutea was harvested at logarithmic growth phase, deceleration growth phase, and stationary phase. The ambient concentrations of phosphorus (P) and nitrogen (N), and fatty acid composition of microalgae were measured. P was limited between logarithmic and deceleration growth phases, followed by N starvation in stationary phase. Total lipid DHA was lowest in logarithmic growth phase, whereas DHA levels increased in deceleration growth phase and maintained at high levels even in stationary phase. PL-DHA also increased during deceleration growth phase, although its abundance dropped during stationary phase. In a rotifer enrichment trial, T. lutea harvested in each phase were fed to B. plicatilis sp. complex rotifers for 12 h. The highest PL-DHA value for cells in deceleration growth phase reflected the concentrations of the rotifers. No significant differences were found in rotifer growth rate and egg ratio. Rotifers fed cells in deceleration growth phase exhibited higher swimming speeds than those fed the other cells, potentially linking to increased larval capture success. Therefore, we recommend the deceleration growth phase as an optimal timing for T. lutea harvest for the effective enrichment of B. plicatilis sp. complex rotifers.

Research paper thumbnail of Novel Nile tilapia Neu1 sialidases: Molecular cloning and biochemical characterization of the sialidases Neu1a and Neu1b