83602 research outputs found
Sort by
Antibacterial Activity of Essential Oils and Extracts of Some Medicinal Plants against Bacterial Fish Pathogens
Get PDFIn this study, chemical compositions and in vitro antibacterial activities the components of essential oils and extracts of sage (Salvia officinalis L.), rosemary oil (Rosmarinus officinalis L.), lavandin (Lavandula x intermedia var. Super), and hyssop (Hyssopus officinalis L.) against fish pathogens: Gram-negative bacteria (Aeromonas caviae, Aeromonas hydrophila, Vibrio anguillarum, Yersinia ruckeri, Edwardsiella tarda, Pseudomonas aeruginosa) and Gram-positive bacteria (Lactococcus garvieae, Staphylococcus warneri, Vagacoccus salmoninarum) were investigated with Well Diffusion Agar assay. The composition of the essential oils and extracts were analyzed with GC/MS and HPLC, respectively. A total of 42 components in sage, 39 in rosemary, 44 in lavender, and 46 in hyssop were detected. As a result of this study, the sage and rosemary oils exhibited a broad-spectrum inhibitory effect (a strong antibacterial effect against Gram (+) and Gram (-) pathogens). Lavandin oil also showed a strong antibacterial effect against a majority of pathogens. The spectrum of inhibitory activity of hyssop oil was found narrower than other plant oils. In further studies, in vivo antibacterial effects of sage, rosemary and lavandin essential oils should be investigated
Effect of salinity on growth performance and resistance of the clam Cyclina sinensis against Vibrio parahaemolyticus infection
Get PDFWe examined the growth performance, immune parameters and the susceptibility to Vibrio parahaemolyticus in the clam Cyclina sinensis, which had been reared at different salinity levels of 10‰, 20‰ and 30‰ for 60 days. At the end of the feeding experiment, the biggest shell length and body weight was found in 20‰, followed by 30‰ and 10‰. No significant differences in superoxide dismutase (SOD) activity were observed among the clams held in 10‰, 20‰ and 30‰. Na+/K+ -ATPase (NKA) activity of the clams held in 20‰ and 30‰ were significantly lower than that in group 10‰. The lowest activities of lysozyme (LZM) and glutamic-pyruvic transaminase (GPT) were found in group 10‰. The Integrated Biomarker Response index (IBR) values of the clams had an inverse relationship with salinity: 11.28, 3.40 and 2.85 in 10‰, 20‰ and 30‰, respectively. At the end of the feeding experiment, the clams were infected with V. parahaemolyticus. As time after infection goes on, the survival rate of clams reared in 20‰ was not significantly different with the other two treatments from 24 to 48h after infection. However, from 72 to 120h after infection, it was significantly lower than those reared in 10‰, while it was significantly higher than those reared in 30‰. It is concluded that the clam C. sinensis reared in 10‰ seawater may reduce growth performance and immune ability, whereas increase resistance against V. parahaemolyticus infection
Potential role of L-ascorbic acid with Field cricket (Gryllus bimaculatus) meal in diets of Nile Tilapia (Oreochromis niloticus) during sex reversal and nursing
Get PDFA synthetic androgen 17-α methyltestosterone (MT) commonly used in the production of mono-sex fry of Nile tilapia (Oreochromis niloticus) during the first 21 days for sex reversal has been considered to suppress immunity thereby reduce survival. Present trial was conducted to evaluate whether vitamin C (L-ascorbic acid, AA) supplementation would benefit in terms of survival, growth, and stress resistance. Nile tilapia fry were fed with isonitrogenous (57.8±0.2% CP) diets formulated using Field cricket (Gryllus bimaculatus) meal (approx. 79%) and fish meal (approx. 20%) to use as control, and five other diets were prepared by supplementing 10, 20, 30 40 and 50 g of vitamin C (L-ascorbic acid per kg diet). Eighteen aquaria or glass tanks (100 L) were used having three replicates per treatment. Each aquarium was stocked with 300 fish (0.01±0.00 g). Fry were nursed for another 91 days to check their sex-ratio. Gonad histology showed increased number of spermatogonia when L-ascorbic dose was 30g/kg diet. At the end of the feeding trial results indicated significant increase (P<0.05) in growth, feed utilization and survival when fed with vitamin C at the dose of 10 g/kg diet during sex-reversal and nursing periods as compared to the control. Similarly, hematological information also showed 10 g vitamin C dose per kg diet. Polynomial regression showed that the optimum dietary ascorbic acid doses were calculated at 15.9, 10.0 and 12.0 g AA per kg diet for highest survival (83.5% max), weight gain and SGR, respectively, but the doses higher than 20 g of L-ascorbic acid/kg diet was not beneficial. Highest apparent digestibility (AD%) of protein (84.1%) was at 15.37g and AD% of lipid (91.4% max) was 17.8g of vitamin C/kg diet. Salinity challenge test also showed highest survival can be achieved at 15.8 g AA per kg diet. As the survival of fry is the most important parameter at these stages, the dose which resulted highest survival i.e., 15 g/kg diet is recommended
Effects of acute low salinity stress on the liver structure, physiology and biochemistry of juvenile Chinese sea bass (Lateolabrax maculatus)
Get PDFIn order to explore the effects of acute low salinity stress on the liver structure, physiology and biochemistry of the larvae of Lateolabrax maculatus, the experiment was carried out to transfer the juveniles direct from salinity 30‰ (control group) to salinity 20‰, 10‰, and 0‰, respectively. Changes in liver microstructure and related physiological and biochemical indexes at different time points were observed. The results showed that no fish died during the whole experiment and all of them returned to normal behavior within 15 minutes. The liver cells of juvenile Chinese sea bass showed pathological changes such as swelling, vacuolation and nuclear pyknosis after low salinity stress, and the lower the salinity, the earlier the abnormal phenomenon appeared. The total antioxidant capacity (T-AOC) and superoxide dismutase (SOD) of liver showed a rapid increase and then decrease; The level of malondialdehyde (MDA) returned to normal after high fluctuations. The activity of lysozyme (LZM) in experimental groups were higher than that in control group between 12h and 48h, while there was not significantly different before 6h in each group (P>0.05), all of them returned to normal in 96 h. The activity of alkaline phosphatase (ALP) and acid phosphatase (ACP) increased firstly and then decreased during the time of stress, and there was no significant difference between each group at the same time point (P>0.05). The comprehensive analysis showed that the juvenile Chinese sea bass had strong osmotic pressure regulation ability, and the acute low salinity stress had little effect on the liver structure and physiological and biochemical indexes
In Memoriam: Nguyễn Văn Lợi (1947-2020)
Get PDFThis is an "in memoriam" for Nguyễn Văn Lợi (1947-2020)
Effects of salinity, pH and alkalinity on hatching rate of fertilized eggs of Penaeus monodon
Get PDFThe fertilized eggs of "Nanhai 2" Penaeus monodon bred by our research group were incubated at the same temperature (30℃), different salinity (20, 25, 30, 35, 40), different pH (7.0, 7.5, 8.0, 8.5, 9.0) and different alkalinity (2.0 mmol/L, 2.5 mmol/L, 3.0 mmol/L, 3.5 mmol/L, 4.0 mmol/L) to explore the effects of salinity, pH and alkalinity on hatching rate of fertilized eggs of P. monodon. The results showed that the hatching rate of fertilization rate of P. monodon was closely related to salinity, and the best hatching rate was obtained when the seawater salinity was 30 with the average hatching rate was 82.60%. The hatching rate was very low when the salinity was as low as 20 or as high as 40, which was significantly lower than that of other treatments (P<0.05). The hatching effect of the fertilized eggs of P. monodon was closely related to the pH value of seawater, and the slightly alkaline seawater was conducive to the normal development of the fertilized eggs. Among them, the hatching effect of the seawater pH value of 8.0 was the best, and the average hatching rate of the fertilized eggs was 80.62%. Too low or too high pH value of the seawater was not conducive to the development of the embryo, and the hatching rate of the fertilized eggs decreased in varying degrees. There was no significant correlation between the hatching effect of fertilized eggs and the change of seawater alkalinity. The average hatching rate of fertilized eggs ranged from 78.65% to 83.12% in the alkalinity range of 2.0-4.0 mmol/L
Dietary conjugated linoleic acid supplementation alleviates high lipid-induced intestinal damage in grass carp (Ctenopharyngodon idella)
Get PDFHigh lipid diet has been shown to increase the intestinal permeability and inflammatory properties in mammals, and the conjugated linoleic acid (CLA) could alleviate the symptoms caused by high lipid diet. However, the information about the impact of high lipid diet on the intestine of fish was limited, and the effect of CLA on intestinal changes induced by high lipid diet in fish is still unknown. Therefore, an 8-week feeding trial was conducted to investigate CLA's potential effects against high lipid diet-induced intestinal physical and immune barrier damage in grass carp (Ctenopharyngodon idella). Three isonitrogenous diets, including fish meal-control diet, control diet supplemented with 3.5% soybean oil as high lipid diet (HL), and HL replaced with a 2.5% CLA diet (CLA) formulated. Compared to the control group, HL significantly increased the expression of pro-inflammation genes (TNF-α, IL-8, IL-1β, NF-κB p65, IκBα, IKKα, IKKβ, and IKKγ) and down-regulated the gene expression of anti-inflammation cytokine (IL-10). The expression of intestinal tight junction proteins (ZO-1, occludin, claudin c, and claudin b) in fish fed with high lipid diets was lower than those fed with control diets. In the CLA group, the gene expression of pro-inflammation cytokines was decreased, and the expression level of the anti-inflammation cytokine was increased, compared with those in HL group. Moreover, feeding with high lipid diets induced fish intestine and dietary CLA damage could alleviate the symptom as shown by HE staining. In conclusion, this research revealed that CLA could mitigate high lipid diet-induced inflammation and permeability in the intestine of grass carp
The Scalar Interpretation of the Additive Focus Particle *=Bv in Select Boro-Garo Languages
Get PDFThe paper looks into the scalar interpretation of the additive focus particle in select Boro-Garo languages, namely, Boro, Dimasa, Garo, Kokborok, Rabha, and Tiwa. The additive has the following forms: =bɯ in Bodo, =bo in Dimasa, =ba in Garo, =bo in Kokborok, =ba in Rabha, and =bo in Tiwa. Based on their phonetic similarity, we reconstruct the Boro-Garo proto-form as *=bV. The additive provides a scalar ‘even’ reading in three different constructions, namely, classifier-numeral, quantifier, and temporal adverbial constructions. In classifier-numeral constructions, a scalar reading is found when the numeral is ‘one’ and the clause is negative. However, with numerals greater than ‘one’, the particles may have either a scalar or non-scalar additive interpretation depending on the contexts. In the other two constructions, the particles contribute scalar meaning only in negative environments