Daphnia pulex through physical and chemical factors

Regarding the key role and importance of Daphnia in aquaculture, particularly for survival and adaptation of fishes in larval stages, a comprehensive study on hatching rate of Daphnia ephippial eggs was implemented to obtain an optimum technique. The effects of abiotic factors was investigated on the hatching response of Daphnia pulex diapausing eggs collected from live food ponds in Cultivation and Breeding Centre of Gorgan. After isolation, the eggs were kept in dry and wet conditions at 4°C for 2 months in darkness. Following the preincubation period, the eggs in each group were subdivided into 2 parts and treated with 1% NaOCl and distilled water. The effect of temperature levels (15 C, 20 C, 25 C) and photoperiod levels (12L: 12D, 24L: 0D) were identified on the hatching of eggs in AdaM medium during 15 days. Results indicated that the exposure of wet-kept eggs to 12-hour photoperiod and 25 C without soaking in 1% NaOCl, caused the maximum rate and speed of hatching

Seasonal changes of fatty acids in Nerita textilis on intertidal area of Chabahar Bay (Oman Sea)

The aim of this research was to identify and isolate the fatty acids composition of Nerita textiles in intertidal area of Chabahar Bay, and also to explore the seasonal changes of fatty acid content in Nerita textiles. GC/MS resulted thirteen fatty acids, that saturated fatty acids (SFA) of palmitic acid (16:0) was the most abundant category of fatty acid obtained in total lipids. There were no significant differences in total saturated fatty acids between different seasons. No significant differences were also observed in total unsaturated fatty acids between different seasons. The majority of unsaturated fatty acid reached their maximum levels during winter, while saturated acids reached their maximum levels in summer. Saturated acids were more than unsaturated fatty acids. Statistical analysis showed the positive significant correlation between temperature and saturated fatty acids and a negative significant correlation between temperature and unsaturated fatty acids. Biomarker fatty acids revealed that diet of Nerita textiles probably includes phytoplankton, zooplankton, detritus, bacteria, diatoms, red and brown algae. The results showed that meat quality indicated n-6/n-3 ratio in the range of 1.9 to 4.3

Effects of different levels of Daphnia and Artemia extracts on food acceptability and growth factor rates of beluga (Huso huso Linnaeus, 1758)

In a 30 day feeding trial, Daphnia and Artemia extracts were added to diets of juvenile Beluga (Huso huso) at different levels to evaluate its effects on growth and survival rate of the fish. The trial was carried out in aquaculture research center of the Gorgan University, during which three different dietary levels of extracts (1:25, 1: 50 and 1:100) were used in 250 liter PVC tanks filled with about 125 liters of water. A total of 20 juvenile Beluga with an average weight of 5 plus or minus 0.2g each was stocked in tanks and were fed 4 meals a day. Growth and survival factors were analyzed at the end of the trial period. The results showed that the addition of extracts in diets led to improvement of body weight increase, weight increase percentage, specific growth rate (SGR), daily growth rate (DGR), daily growth index (DGI), condition factor (CF), price index (PI) and decrease of food conversion ratio (FCR) compared to the control treatment. The best improvement of growth index was achieved at the dietary level 1:50 Artemia extracts. There was no significant difference (P>0.05) in survival among treatments

Evaluation of metallothionein protein as a biomarker of Mercury pollution in Scat (Scatophagus argus)

Total Metallothionein (MT) biosynthesis and Mercury bioaccumulation under control & acute Mercury exposure were investigated in Scat (Scatophagus argus). Tissues from liver and gill of samples Scats were exposed to different Mercury concentrations (10, 20, 30μ g/l) for 24, 48, 72 hours. Mercury contents were determined through Cold Vapour Atomic Absorption Spectrometry (CVAAS). Total MT levels were determined by Enzyme-linked Immunosorbent Assay (ELISA) method. Induction of MT during exposure was tissue specific, displaying different response patterns in gill and liver. Mercury accumulated in liver much stronger than gill and the latter also showed lower MT level. Although after exposure to different mercury concentration during different periods, MT biosynthesis in liver showed a significant increase (P<0.05) but in gill did not significantly modify total MT except for 72h exposure at 30 g/l. Nonetheless, the relationship between MT biosynthesis and Mercury bioaccumulation in both tissues was significant. The results suggest that this form of MT presence in S. argus was Hg-inducible and could be extended as a biomarker of Mercury pollution in marine ecosystems and especially in Persian Gulf

The effects of prebiotic oligofructose on hematological, serum biochemical parameters and liver enzymes of juvenile beluga (Huso huso)

The aim of the present study was to investigate the effects of dietary oligofructose (1, 2 and 3%) on blood profiles of beluga Huso huso juveniles (18.77±0.76g). After 7 weeks feeding on experimental diets hematological parameters, metabolic products (cholesterol, glucose and total protein) and serum enzymes (lactate dehydrogenase, alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase) were measured. Compared to the control group (0% oligfructose), oligofructose had no effects on red blood cell counts (RBC), mean corposcular volume (MCV), mean cellular hemoglobin concentration (MCH) or mean cell hemoglobin concentration (MCHC) (P>0.05). However, hematocrit (Hct), hemoglobin concentration (Hb) and leucocyte counts (WBC) were significantly higher in fish fed 2% oligofructose (P0.05). These results indicate an immunomodulatory effect and the potential to reduce serum cholesterol levels in beluga sturgeon

Large scale structure around a z=2.1 cluster

The most prodigious starburst galaxies are absent in massive galaxy clusters today, but their connection with large scale environments is less clear at $z\gtrsim2$. We present a search of large scale structure around a galaxy cluster core at $z=2.095$ using a set of spectroscopically confirmed galaxies. We find that both color-selected star-forming galaxies (SFGs) and dusty star-forming galaxies (DSFGs) show significant overdensities around the $z=2.095$ cluster. A total of 8 DSFGs (including 3 X-ray luminous active galactic nuclei, AGNs) and 34 SFGs are found within a 10 arcmin radius (corresponds to $\sim$15 cMpc at $z\sim2.1$) from the cluster center and within a redshift range of $\Delta z=0.02$, which leads to galaxy overdensities of $\delta_{\rm DSFG}\sim12.3$ and $\delta_{\rm SFG}\sim2.8$. The cluster core and the extended DSFG- and SFG-rich structure together demonstrate an active cluster formation phase, in which the cluster is accreting a significant amount of material from large scale structure while the more mature core may begin to virialize. Our finding of this DSFG-rich structure, along with a number of other protoclusters with excess DSFGs and AGNs found to date, suggest that the overdensities of these rare sources indeed trace significant mass overdensities. However, it remains puzzling how these intense star formers are triggered concurrently. Although an increased probability of galaxy interactions and/or enhanced gas supply can trigger the excess of DSFGs, our stacking analysis based on 850 $\mu$m images and morphological analysis based on rest-frame optical imaging do not show such enhancements of merger fraction and gas content in this structure.Comment: 11 pages, 4 figures, ApJ accepte

Analysis of and workarounds for element reversal for a finite element-based algorithm for warping triangular and tetrahedral meshes

We consider an algorithm called FEMWARP for warping triangular and tetrahedral finite element meshes that computes the warping using the finite element method itself. The algorithm takes as input a two- or three-dimensional domain defined by a boundary mesh (segments in one dimension or triangles in two dimensions) that has a volume mesh (triangles in two dimensions or tetrahedra in three dimensions) in its interior. It also takes as input a prescribed movement of the boundary mesh. It computes as output updated positions of the vertices of the volume mesh. The first step of the algorithm is to determine from the initial mesh a set of local weights for each interior vertex that describes each interior vertex in terms of the positions of its neighbors. These weights are computed using a finite element stiffness matrix. After a boundary transformation is applied, a linear system of equations based upon the weights is solved to determine the final positions of the interior vertices. The FEMWARP algorithm has been considered in the previous literature (e.g., in a 2001 paper by Baker). FEMWARP has been succesful in computing deformed meshes for certain applications. However, sometimes FEMWARP reverses elements; this is our main concern in this paper. We analyze the causes for this undesirable behavior and propose several techniques to make the method more robust against reversals. The most successful of the proposed methods includes combining FEMWARP with an optimization-based untangler.Comment: Revision of earlier version of paper. Submitted for publication in BIT Numerical Mathematics on 27 April 2010. Accepted for publication on 7 September 2010. Published online on 9 October 2010. The final publication is available at http://www.springerlink.co

LARGE-SCALE STRUCTURE AROUND A z=2.1 CLUSTER

The most prodigious starburst galaxies are absent in massive galaxy clusters today, but their connection with large-scale environments is less clear at $z\gtrsim 2$. We present a search of large-scale structure around a galaxy cluster core at z = 2.095 using a set of spectroscopically confirmed galaxies. We find that both color-selected star-forming galaxies (SFGs) and dusty star-forming galaxies (DSFGs) show significant overdensities around the z = 2.095 cluster. A total of eight DSFGs (including three X-ray luminous active galactic nuclei, AGNs) and 34 SFGs are found within a 10' radius (corresponds to ~15 cMpc at $z\sim 2.1$) from the cluster center and within a redshift range of ${\rm{\Delta }}z=0.02$, which leads to galaxy overdensities of ${\delta }_{{\rm{DSFG}}}\sim 12.3$ and ${\delta }_{{\rm{SFG}}}\sim 2.8$. The cluster core and the extended DSFG- and SFG-rich structures together demonstrate an active cluster formation phase, in which the cluster is accreting a significant amount of material from large-scale structure while the more mature core may begin to virialize. Our finding of this DSFG-rich structure, along with a number of other protoclusters with excess DSFGs and AGNs found to date, suggest that the overdensities of these rare sources indeed trace significant mass overdensities. However, it remains puzzling how these intense star formers are triggered concurrently. Although an increased probability of galaxy interactions and/or enhanced gas supply can trigger the excess of DSFGs, our stacking analysis based on 850 μm images and morphological analysis based on rest-frame optical imaging do not show such enhancements of merger fraction and gas content in this structure