The aim of this study was to elucidate the effect of fish-oil-derived monounsaturated fatty acids (MUFAs) containing large amounts of C20:1 and C22:1 isomers on metabolic disorders in mice. Male ...C57BL/6J mice were fed a 32% lard diet (control) or a 27% lard plus 5% saury-oil-derived MUFA diet for 6 weeks. Dietary MUFA improved insulin resistance and alleviated metabolic syndrome risk factors by reducing blood glucose and lipids. These favorable changes may be attributed to an improved adipocytokine profile. MUFA ingestion resulted in favorable changes in mRNA expression of genes involved in glucose/lipid metabolism (SCD-1, CPT1a, UCPs, and CS) as well as inflammation (MAC1, MMP3, and SAA3) and alterations in fatty acid composition. Our data suggest that marine MUFA improved glucose/lipid homeostasis and hindered the development of metabolic syndrome in obese mice.
We evaluated the effectiveness of two representative marine zooplankton, the harpacticoid copepod
Tigriopus japonicus
and the euryhaline cladoceran
Diaphanosoma celebensis
, as live food for red sea ...bream
Pagrus major
larvae. Chicken-dropping extract (CDE) was applied to both zooplankton cultures to improve population growth. Population growth of both zooplankton was significantly enhanced by CDE supplementation (at 1 or 2 ml/l). The highest amount of docosahexaenoic acid (DHA) and higher DHA/eicosapentaenoic acid ratio were detected in
T. japonicus
, whereas
D. celebensis
showed similar values to that of
Artemia
. Effectiveness of both animals as live food was tested by rearing red sea bream larvae on them for 28 days and comparing the results with those for
Artemia
. There were no significant differences in total length (8.6 ± 1.1–8.7 ± 0.7 mm) or wet weight (8.2 ± 0.3–9.4 ± 0.1 mg) among fish larvae feeding on the three different zooplankton. Survival rate was significantly higher with
T. japonicus
(39.4 ± 3.1 %) than with
D. celebensis
(20.8 ± 3.8 %) and
Artemia
(16.7 ± 9.8 %). Viability was significantly higher in fish fed with
T. japonicus
(60.0 ± 27.8 %) and
D. celebensis
(60.0 ± 32.2 %) than in those fed with
Artemia
(44.4 ± 12.3 %). Fish fed with
T. japonicus
contained higher n-3 highly unsaturated fatty acids than those fed with
D. celebensis
and
Artemia
. It is concluded that
T. japonicus
and
D. celebensis
have high potential as live food in marine fish larviculture.
We investigated the effect of saury oil on the alleviation of metabolic syndrome in mice. Saury oil contains 18% (w/w/) n-3 polyunsaturated fatty acids (n-3 PUFA) and 35% (w/w) monounsaturated fatty ...acids (MUFA). Diabetic KKAy mice were fed a 10% soybean oil diet (control) or a 10% saury oil diet for 4 weeks, and diet-induced obese C57BL/6J mice were fed a high-fat diet containing 32% lard (control) or 22% lard plus 10% saury oil for 6 weeks. After the intervention periods, the levels of glucose, insulin and lipids in plasma had decreased significantly for the saury oil diet group, and insulin sensitivity had improved. These favorable changes may be attributed to the increased adiponectin and decreased TNFα and resistin levels in plasma. The saury oil diet also resulted in downregulated expression of the lipogenic genes (
SREBP
-
1
,
SCD
-
1
,
FAS
, and
ACC
) as well as upregulation of the fatty acid oxidative gene,
CPT
-
1
, and the energy expenditure-related genes (
PGC1α
and
PGC1β
) in white adipose tissue for the diet-induced obese C57BL/6J mice. An increase in n-3 PUFA levels and the concomitant decrease in the n-6/n-3 PUFA level ratio in serum, white adipose tissue, and liver with a saury oil diet are likely to be involved in the beneficial changes to the metabolic indicators. MUFA may also play a positive role in remodeling lipid composition. Based on these mice models, our results suggest a potential use for saury oil for improving metabolic abnormalities.
Hyperlipidemia associated with obesity is closely related to the development of atherosclerosis. Both n-3 polyunsaturated fatty acids (PUFAs) and long-chain monounsaturated fatty acids (MUFAs; i.e., ...C20:1 and C22:1 isomers) supplementation modulate risk factors for metabolic syndrome via multiple mechanisms, including the restoration of impaired lipid metabolism. We therefore examined the effects of pollock oil, which contains a considerable amount of n-3 PUFAs as well as long-chain MUFAs, on plasma hyperlipidemia and hepatic steatosis in diet-induced obese mice.
Male C57BL/6J mice (24-26 g) were divided into two groups (n = 10/group) and were fed a high-fat diet containing 32% lard (control group) or 17% lard plus 15% pollock oil (experimental group) for 6 weeks. For both groups, fat comprised 60% of the total caloric intake.
Although body and liver masses for the two groups did not differ significantly, hepatic lipids concentrations (triglycerides and total cholesterols) were lower (P < 0.05) after pollock oil ingestion. After 2 weeks on the specified diets, plasma lipid levels (total cholesterol, LDL cholesterol, and triglycerides) significantly decreased (P < 0.05) in the experimental group compared with the control group, although plasma HDL cholesterol levels did not differ. At the end of 6 weeks, plasma adiponectin levels increased (P < 0.05), whereas plasma resistin and leptin levels decreased (P < 0.05) in the experimental mice. Increased levels of long-chain MUFAs and n-3 PUFAs in plasma, liver and adipose tissue by ingesting pollock oil were possibly correlated to these favorable changes. Expression of hepatic genes involved in cholesterol metabolism (SREBP2, HMGCR, and ApoB) and lipogenesis (SREPB1c, SCD-1, FAS, and Acacα) was suppressed in the experimental group, and may have favorably affected hyperlipidemia and hepatic steatosis induced by the high-fat diet.
We demonstrated that pollock oil supplementation effectively improved hyperlipidemia, attenuated hepatic steatosis, and downregulated the express of hepatic genes involved in cholesterol and lipid metabolism in mice with diet-induced obesity.
Nocardia seriolae infection is one of the most serious bacterial diseases in Seriola species in Japanese aquaculture. In this study, the absorption-enhancing effect of citric acid on oral ...oxytetracycline (OTC) treatment against nocardiosis was evaluated with experimentally infected juvenile yellowtail, Seriola quinqueradiata, followed by serum, kidney and spleen OTC level analysis. When 50 mg/kg body weight (BW) of OTC was administered orally in combination with 1250 mg/kg BW of citric acid, the serum OTC level increased 3-fold at 6 h post single-dose administration, while no effect was observed when the dose of citric acid was set at 50 mg/kg BW. OTC levels in the kidney and spleen were increased 2-fold when 50 mg/kg BW of OTC and 1250 mg/kg BW of citric acid were administered for 5 consecutive days. This coadministration improved the clinical efficacy of oral OTC treatment against nocardiosis by significantly reducing the mortality rate compared to that of the group that received OTC alone and the untreated control group. These results suggest that coadministration of 1250 mg/kg BW of citric acid enhanced OTC absorption and therefore improved the clinical efficacy of oral OTC treatment against nocardiosis.
•Nocardiosis is one of the most serious diseases in Japanese aquaculture.•Oral treatment with OTC did not show sufficient efficacy against nocardiosis.•The coadministration of citric acid with OTC enhanced the oral absorption of OTC.•The coadministration of citric acid improved the efficacy of oral OTC treatment against nocardiosis.
Studies have demonstrated the beneficial effect of palmitoleic acid (C16:1 n-7) on reducing muscle insulin resistance and preventing beta-cell apoptosis. However, the effect of palmitoleic acid on ...diabetes remains to be elucidated. The aim of this study was to examine the antidiabetic effect of palmitoleic acid in KK-Ay mice, a spontaneous model for studies of obese type 2 diabetes with low insulin sensitivity.
KK-Ay mice were orally administered vehicle, 300 mg/kg of palmitoleic acid, or 300 mg/kg of palmitic acid (C16:0) on a daily basis for 4 weeks.
Palmitoleic acid reduced body weight increase, ameliorated the development of hyperglycemia and hypertriglyceridemia, and improved insulin sensitivity. In addition, hepatic characteristics were significantly affected, as weight of the liver and hepatic triglyceride levels were lower in the palmitoleic acid group when compared to the control (vehicle and palmitic acid groups). Oil red O staining clearly indicated reduced hepatic lipid accumulation in response to palmitoleic acid. Furthermore, palmitoleic acid down-regulated mRNA expressions of proinflammatory adipocytokine genes (TNFα and resistin) in white adipose tissue and lipogenic genes (SREBP-1, FAS, and SCD-1) in liver.
These results suggest that palmitoleic acid improves hyperglycemia and hypertriglyceridemia by increasing insulin sensitivity, in part owing to suppressing proinflammatory gene expressions and improving hepatic lipid metabolism in diabetic mice.
The distribution patterns of many fishes between the three continents (Africa, Australia, and South America) in the Southern Hemisphere have been uncovered to be influenced by mostly vicariance or ...historical dispersal. Although some demersal fishes with intercontinental distribution are suggested to be more influenced by current/recent dispersal, few genetic studies have been made for demersal fishes so far. To provide more information for such fishes, genetic divergence was analyzed for two pairs of gadiform species and subspecies distributed around Australasia and South America: the blue grenadier, Macruronus novaezelandiae (from New Zealand) and the Patagonian grenadier, M. magellanicus (from South America) as well as two subspecies of the southern blue whiting, Micromesistius australis pallidus (from New Zealand) and M. a. australis (from South America). The sequence analyses of two mitochondrial DNA regions showed no divergence between Australasian and South American populations of the grenadiers and the southern blue whiting. The microsatellite DNA analysis also indicated significant but very minimal genetic differentiation between the two geographic populations of each pair. These results imply rather recent separation of the two geographic populations. Current/recent dispersal may be an important common factor for determining the distribution of demersal fishes in the Southern Hemisphere. Nonetheless, low but significant genetic differentiation observed requires treating the two populations of the economically important grenadiers and southern blue whiting, respectively, as different stocks for proper resource management.
Proteases of
Neobenedenia girellae were examined by using zymographic analysis. Zymography of
N. girellae homogenate revealed proteases at approximately 88, 107, 149 and 167
kDa for the adult worms ...and approximately 147 and 166
kDa for the oncomiracidia, respectively. The enzyme activities were inhibited by Pefabloc SC but were not inhibited by E-64 and Pepstatin A, indicating that these proteases were serine proteases. The gelatinolytic activities of these proteases were more active at pH 8.5, when pH range of 5.5–11.5 was examined, and increased with the increase of temperature within the range of 15–37
°C. Further, the effect of proteinase inhibitors, pHs and temperatures on
N. girellae were examined. Egg laying of mature
N. girellae was suppressed by Pefabloc SC and seawater of pH 5.5 to 6.5 and at pH 9.5. Additionally, egg laying of mature
N. girellae was suppressed by low incubation temperatures (10, 15, 20
°C). The oncomiracidia treated with Pefabloc SC and seawater of pH 5.5 and pH 9.5 were also affected and cilia of the treated parasites ceased moving. These results suggest that serine proteases of the parasite could be important for their survival, and their physiological active substances such as proteases, may have adapted to higher water temperature and tend to be suppressed at pH 5.5–6.5 and pH 9.5. The results of this study could be informative to develop an effective control method against outbreaks of the parasites.
Trimethylamine-N-oxide (TMAO) is abundant in marine fish. Formaldehyde synthesis by TMAO demethylation during storage markedly deteriorates fish meat. In the present work, we cloned the extremely ...aspartic acid-rich proteins from skeletal muscle of a commercially important species, walleye pollack, in the course of molecular identification of trimethylamine-N-oxide demethylase (TMAOase). One of the cDNAs, designated as aspolin1, encodes an extremely aspartic acid-rich protein of 228 amino acids which is converted to the TMAOase after processing between Ala42 and Asp43. Mature aspolin1/TMAOase protein contains 179 Asp in 186 total amino acids. The other cDNA, designated as aspolin2, has a common nucleotide sequence with aspolin1 in the 5' part and encodes a protein which has an additional Asp polymer and a C-terminal cysteine-rich region. The amino acid sequence of the C-terminal cysteine-rich region of aspolin2 is highly homologous to the mammalian histidine-rich Ca2+-binding protein. Aspolin1/TMAOase and aspolin2 mRNA was most abundant in the skeletal muscle. A lower level of the mRNA was also detected in kidney, heart, spleen, and brain. Synthetic Asp polymer showed marked TMAOase activity in the presence of Fe2+, whereas a monomer and oligomers did not. Purified TMAOase protein bound to Fe2+ with low affinity, which may be responsible for the catalytic activity. Poly aspartic acid-Fe2+ complex generated after death would be involved in formaldehyde synthesis by the demethylation of TMAO during the storage of fish meat.
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