AQUATIC PHYSIOLOGY AND BIOTECHNOLOGY
Year:2015 | Volume:3 | Issue:1|Papers Count:6

Microalgae lipid is used as a feedstock for biodiesel production. Lipid content is correlated with the microalgae species and growth conditions. In this study, variations in total lipid content in the green microalgae of Chlorella sp. under nitrogen starvation stress after 4, 8 and 12 days was examined.Microalgae were cultured in the Zinder-8+N medium. When they reached the semi-logarithmic growth phase, biomass was harvested and transferred to Zinder-8-N medium. The total lipid content was calculated after extraction with a solution of chloroform/methanol (2: 1). Triacylglycerol which is used in biodiesel production separated qualitatively using thin layer chromatography.The results showed that the total lipid content under stress condition after 4, 8 and 12 days increased significantly compared to control (P≤0.05), in average 23.46% more than the control. Also, according to the result of thin layer chromatography, triacylglycerol concentration increased in the microalgae under the stress. In general, nitrogen starvation stress led to increased total lipid content in the green microalgae of Chlorella sp.

Because of the similarities in appearance between species of Oligochaeta, identify, characterize and differentiate them from each other to determine the population dynamics or molecular and phylogenies studies seems necessary.The aim of this study is to provide an identification key and diagnostic methods for the two species of genus Limnodrilus in the Anzali Wetland. In compare key features to identify and separate the two species was found in L. hoffmeisteri genital sheath is shorter and thicker than Limnodrilus claparedianus. Statistical analysis showed that this is a significant difference between the two species (P<0.05). The average length of the penial sheath in L. hoffmeister and L. claparedianus respectively were 695.31±91.63 and 1117.06±198.31 micrometer. The average length of the upper tooth and lower in L. claparedianus respectively were 9.74 ±1.82 and 6.68±0.91 micrometer, in L. hoffmeister were respectively 7.5±2.07 and 5.64±1.29 micrometer. Although in the visual observations the upper teeth of chaeta of L. claparedianus was longer than L. hoffmeisteri but a significant difference was not observed between the averages of the two species.

The purpose of this study was to determine the effect of nickel (Ni) doped TiO2 NPs on gill histopathology of zebrafish (Danio rerio). In this study, a total number of 200 zebrafish (Danio rerio) with average weight of 3g and length body of 4cm were used. In this study, four non-lethal concentrations of Ni doped TiO2 NPs were used that included 1, 10, 30, 100 mg/L; also control group was considered. The results showed that the Ni doped TiO2 NPs on gill tissue cause some impacts such as secondary bending blades, blades secondary hypertrophy, increased mucus secretion, fusion in the secondary lamellae, hyperplasia and eventually necrosis increases. Although histological changes in gill tissue were observed in all groups, but the severity of these changes increased with increasing concentration of Ni doped TiO2 NPs. Moreover, changes were significant between exposure group and control group in parameters of diameter of gill filaments, diameter of secondary lamellae, and length of secondary lamellae (P<0.05). In conclusion, the present study indicated that Ni doped TiO2 NPs can have considerable effects on fish gill tissue.

This study investigated the effects of different levels of synbiotic Biomin Imbo in the diet on growth performance, food efficiency, survival, digestive enzymes activity and some mucus immunological indices of banded cichlide. The experiment designed using a completely randomized test in a control (0 g synbiotic) and 5 treatments, including 0.5, 1, 1.5, 2 and 2.5 g/Kg synbiotic diet, any group with 3 replicates and 15 fish per treatment for 60 days. The results of this study showed that the addition of 0.5 g/Kg synbiotic in diet hadn't significant effect on growth parameters and feed efficiency (P>0.05). However, higher levels of Biomin Imbo synbiotic on diets significantly increased growth parameters such as final weight, percent of body weight, daily growth rate (SGR) and feed efficiency parameters such as feed conversion ratio (FCR) and protein efficiency ratio (PER) (P<0.05). Fish fed dietary with synbiotic showed significant changes in non-specific skin mucus immune parameters, including lysozyme, total protein and alkaline phosphatase (P<0.05). Eventually results of this study showed that synbiotic Biomin Imbo have the beneficial effects on metabolism and growth of banded cichlide, also it increases the safety of juveniles and increase the survival of this fishes.

The lethal concentration and nephrotoxic effects of sea anemone, Stichodactyla sp., mucus on zebra fish, Danio rerio were examined. Sea carpet was collected from an intertidal zone of the Hormoz Island, frozen in nitrogen tank (-160°C), and transported to the laboratory to have its mucus isolated. The lethal concentration (LC5096h) of mucus for the fish, determined as 175.03 mg/L.Three concentrations of mucus (250, 500, 1000 mg/L) were made and added to the fish aquaria. Then, the histological changes of the fish kidney were examined. In 1000 mg/L, the fish was killed in less than 2h and pathologic lesions of the kidney were evident, including congestion, enlargement and necrosis of the glomerulus, reduction of Bowman’s space, fluids inside tubular and glomerular capillaries inflation in interstitial space, but in 500 and 250 mg/L, no death were observed and a slight increase in glomerular volume was observed. Results showed that mucus of the sea anemone could be harmful and even lethal to the zebra fish by damaging its kidney, the severity of which depended on its concentration.

Although pluripotency markers are well known in mammals, our knowledge concerning them is still shallow about fish and other aquatic organisms. In this regard, the expression of nanog oct4, sox2, klf4, lin28, c-myc genes considered as a core circuit of pluripotency in various organisms were investigated in different developmental embryonic stages of zebrafish Danio rerio, including morulla, mid-blastula, gastrula and segmentation with 71, 105.5, 310 and 684 degree/hour post fertilization, respectively. The results of quantitative gene expression using Real Time PCR techniques revealed that In mid-blastulla stage, the lin28 and klf4 had maximum significant expression but no significant expression was observed for oct4 and c-myc. In addition, maximum expression of sox2 gene, known as pluripotency key in mouse and human, were observed after gastrula stage in zebrafish. Moreover, nanog showed significant expression in morulla stage, but no difference was observed in the other stages. In conclusion, lin28, klf4, oct4 and c-myc markers could be considered as the most important pluripotency markers in zebrafish but the sox2 is probably involved in the differentiation process and It seems that nanog has other roles beyond maintaining pluripotency according to its expression pattern.