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The aim of this study was isolation and characterization of heterotrophic bacteria capable of ammonium and nitrite removal at 15 °C (optimal temperature for growing rainbow trout Oncorhynchus mykiss). Environmental isolates were grown in liquid media containing ammonium or nitrite, and best strains in terms of growth and ammonium or nitrite removal were identified via 16S rRNA sequencing. Dyadobacter sp. (no. 68) and Janthinobacterium sp. (no. 100) were selected for optimal adaptation to growth at 15 °C and best ammonium and nitrite removal (P < 0.05), respectively. A heterotrophic ammonium and nitrite removal (HAN) microbial complex, containing selected strains, was prepared and applied in a trout culture system. After 10 days, the effect of microbial HAN complex was investigated in terms of ammonium and nitrite removal, as well as stress and immune indices present in the plasma of cultivated trout. Compared to a standard cultivation setup, addition of the HAN complex had a clear beneficial effect on keeping the un-ionized ammonia and nitrite level below prescribed standards (P < 0.05). This resulted in reduction of stress and immune reactions of cultivated fish (P < 0.05), leading to an augmentation of final weight and survival. Application of the selected microbial complex resulted in a significant improvement of the aquaculture ecosystem.

Background There is increasing recognition of the concordance between marine biogeographic and phylogeographic boundaries. However, it is still unclear how population-level divergence translates into species-level divergence, and what are the principal factors that first initiate that divergence, and then maintain reproductive isolation. This study examines the likely forces driving population and lineage divergences in the broadly-distributed Indo-Pacific spiny lobster Panulirus homarus , which has peripheral divergent lineages in the west and east. The study focuses particularly on the West Indian Ocean, which is emerging as a region of unexpected diversity. Mitochondrial control region (mtCR) and COI sequences as well as genotypes of 9 microsatellite loci were examined in 410 individuals from 17 locations grouped into 7 regions from South Africa in the west, and eastward across to Taiwan and the Marquesas Islands. Phylogenetic and population-level analyses were used to test the significance and timing of divergences and describe the genetic relationships among populations. Results Analyses of the mtCR revealed high levels of divergence among the seven regions (Ф ST  = 0.594, P <  0.001). Microsatellite analyses also revealed significant divergence among regions, but at a much lower level (F ST  = 0.066, P <  0.001). The results reveal different patterns of mtCR v. nDNA divergence between the two distinct peripheral lineages: a subspecies in South Africa and Madagascar, and a phylogeographically diverged population in the Marquesas. The results also expose a number of other more fine-scale population divergences, particularly in the Indian Ocean. Conclusions The divergence of peripheral lineages in the west and east of the species’ range appear to have been initiated and maintained by very different processes. The pattern of mitochondrial and nuclear divergence of the western lineage, implicates processes of parapatric isolation, secondary contact and introgression, and suggests possible maintenance through adaptation and behavioural reproductive isolation. In contrast, the eastern lineage appears to have diverged through a rare colonisation event, maintained through long-term isolation, and matches expectations of the core-periphery hypothesis. The process of active peripheral speciation may be a common force in the Indo-Pacific that helps drive some of the regions’ recognized biogeographic boundaries.

Panulirus homarus is an economically important spiny lobster that is widespread through the Indo-West Pacific Region, but has an uncertain taxonomic status, with three or four geographic subspecies having been described. This study used mitochondrial (16S, COI and control region) and nuclear (18S, ITS-1) DNA sequences to examine specimens of all putative subspecies and forms from throughout their range, in order to determine their genetic validity, and understand the evolutionary history of this species. Despite the range of diversity present in the loci examined, the results were consistent across genes. P. h. rubellus from the SW Indian Ocean comprised the most divergent lineage that was reciprocally monophyletic with respect to all other P. homarus (approx. 9% divergence in COI), and has likely evolved reproductive barriers. The putative P. h. \"Brown\" subspecies from the Marquesas Is in the central Pacific also comprised a somewhat divergent monophyletic lineage (approx. 3% in COI), but may simply be an allopatric population. The widespread P. h. homarus was not diverged at all from the described P. h. megasculpta from the NW Indian Ocean. The degree of evolutionary divergence of populations at the extremes distribution of the species is somewhat surprising, given the long pelagic larval stage, but suggests that allopatric speciation has been an important driver in the evolution of the genus.

Genetic diversity is vital for the maintenance of genetic pool in cultured shrimps. In order to estimate the current status of genetic diversity in Litopenaeus vannamei shrimp in Iran, as an exotic species, a total of 45 individuals from Amiri and Gorgeaj farms in Jask port of Hormozgan province and one hatchery in Gomishan city of Golestan province, were detected using four microsatellite loci. The number of alleles per locus was 5–10, and the mean effective number of alleles ( N e ) across populations and loci ranged from 4.834 to 5.148. The overall mean observed heterozygosity ( H o ) ranged from 0.450 to 0.479, which was lower than the expected one (0.789–0.794). There was nothing remarkable about any of the allele frequencies across populations or loci. The mean inbreeding coefficient ( F IS ) and pairwise genetic differentiation ( F ST ) among populations were 41.6 % and 0.133, respectively. The three studied populations departed from Hardy–Weinberg equilibrium (HWE). Analysis of molecular variance revealed 14 % variability among and 86 % within populations. However, considering departing from HWE and the high F IS and F , the moderate pairwise F ST values, importance of introducing genetically diverse broodstock and monitoring to control inbreeding is discussed.

The present study examined the morphological variations of 162 specimens of Chondrostoma regium (Heckel, 1843) collected from Beheshtabad, Shalmzar, Karoun, Gandman, Sheikh Ali Khan (Chaharmahal-e Bakhtiari Province), Tof Sefid and Seimareh (Isfahan Province), Khersan, Beshar (Kohgoluyeh and Boyer-Ahmad Province), Dinevarab, Alvand (Kermanshah Province), Homeil (Ilam Province), Doab, Kafraj (Lorestan Province) and Zab (Kurdistan Province). A total of 27 morphometric and 11 meristic characteristics were assessed. To investigate the morphological variations between the studied populations, the morphometric and meristic characteristics were analyzed using one-way analysis of variance (ANOVA), Kruskal-Wallis test, principal component analysis (PCA), multivariate analysis of variance (MANOVA), and canonical variates analysis (CVA). The results of the study showed that there were differences in regards to 20 morphometric and 10 meristic characteristics (p

This study was conducted to examine the phylogenetic relationship of the genus Turcinoemacheilus in Iran based on osteological characteristics. A total of 25 fish specimens of four species belonging to the genus Turcinoemacheilus from Tigris and Isfahan basins were considered as in-group and Cobitis linea as out-group. The skeletal elements were examined after clearing and staining. A total of 19 character-states were described that showed differences between the studied taxa. Phylogenetic analysis was performed using osteological characters with the maximum parsimony method. Based on the results, the most parsimonious tree with a length of 29, the consistency index of 1, and a retention index of 1 was obtained. Turcinoemacheilus hafezi and T. bahaii with 76% support were in a sister group and the two species of T. kosswigi and T. saadii with 97% support were in another clad. The presence of the lateral fontanel in T. hafezi, the overlap of the internal lateral-wall of autoplatinii with posterior lateral-wall of the ethmoid, symmetry of the posterior part of the autoplatinii and divergence of the hemal spin’s process in T. kosswigi, ratio of the ascending process to the horizontal process of the maxillary, and beginning of the first dorsal-fin petrigiophore to vertebra 17 in T. bahaii were distinguishing osteological characters of the studied species.

The osteological characteristics is an important tool for clarification of the phylogenetic statue of the family Nemechelidae. Since any information is available about osteological features of the genus Turcinoemacheilus, hence the present study provides a detailed osteological characteristics of the Turcinoemacheilus hafezi as representative of this genus. Ten specimens of T. hafezi were collected from the Shalamzar Stream, Tigris basin, Iran and cleared and stained for osteological examination. According to the results, T. hafezi is osteologicaly characterized by absence of the preethmoideum-I and postcleithrum, having four basibranchials, presence of the sesamoid ossification, free and short epural with the reduced neural process and pleurostyle, connection of the hypural-1 to the parahypural, no connection of the hypurals 3, 4, and 5 to the pleurostyle, and no bony bridge between the parietal.

Rapid and accurate identification of microorganisms have a significant impact on strategies and fish health management programs. Hence, in this study a duplex PCR assay based on the 16s rRNA gene for simultaneous detection of Aeromonas hydrophila RTICC 1032 and Escherichia coli RTICC 2325 from pure cultures, and challenged fish tissues was performed and their results compared with the results of single PCR assays for each bacterium. For this purpose, an experiment with three treatments including artificially infected with A. hydrophila, E. coli and a mixture of them with a control group was designed. Fish were injected intraperitoneally with 1 ml of sterile physiological saline containing 106 CFU/ml of the corresponding bacteria. Samples were collected from liver, kidney and spleen 48 hrs post-injection. A duplex PCR based 16S rRNA genes was developed for the simultaneous detection of A. hydrophila and E. coli. The PCR reaction conditions were optimized to permit detection of organisms from agar plates and fish tissues in less than 8 hrs. Each of the two pairs of oligonucleotide primers exclusively targeted 16S rRNA gene of the specific microorganism. When duplex PCR assay was used to simultaneous detection of the pathogens in asymptomatic fish, spleen and liver were negative for A. hydrophila, whereas kidney was positive for two bacteria. Samples of control group with negative results of duplex PCR were also negative by the culture method. On the whole, the duplex PCR has advantages in terms of its accuracy, sensitivity, ease of use, time of length analysis and cost-effectiveness compared to the single PCR and traditional method.

This study aims to evaluate the effect of nano titanium dioxide and microplastics, alone and in combination, on immune system function and oxidative stress of juvenile Nile tilapia, Oreochromis niloticus. For this purpose, fish were randomly divided into 27 100L tanks using a 3×3 factorial design, including three concentrations of Nano titanium dioxide (0, 1, and 5 mg/l) and three concentrations of microplastic (0, 0.5, and 1 mg/l) separately and together each in triplicate. The results showed that immunoglobulin, malondialdehyde (MDA), and glutathione reductase (GR) had significant effects in all groups (P<0.05). Lysozyme, total antioxidant capacity (TAC), and glutathione peroxidase (GPx) showed significant differences between the combined groups and the control (P<0.05). No significant differences were observed in C3 and C4 between groups exposed to MPs and Nano-TiO2 and the control (P>0.05). Superoxide dismutase (SOD) showed significant differences between the group exposed to MPs and Nano-TiO2 alone and the control group (P<0.05). In conclusion, the results showed that MPs could have a synergistic effect on the toxicity of Nano-TiO2.

The nucleoprotein of infectious hematopoietic necrosis virus (IHNV) is considered as the main target antigen for detection of IHNV infection in salmonid fish. This study aimed at improving the expression and solubility of IHNV nucleoprotein (IHNV-NP) in E. coli expression system. The effects of several expression strategies including host strain type, protein expression temperature, heat-shock treatment prior to protein induction, and additives in the growth medium and in the cell lysis buffer were examined. Results showed that bacterial strain type had a great impact on protein expression level, whereas it was not effective in preventing protein aggregation. Production of soluble IHNV-NP was proportionally increased with decreased incubation temperature. Heat-shock treatment prior to protein induction did not change the percent of solubility. For cells grown at low temperature, the presence of additives in the lysis buffer enhanced the solubility of IHNV-NP up to 24%. The highest yield of soluble protein was obtained via incorporation of osmolytes in the growth medium of cells exposed to a mild salt stress, in the following order: sucrose > sorbitol > glycerol > glycine. Soluble protein obtained by the optimized condition was efficiently purified in high yield and successfully detected by two monoclonal antibodies in a sandwich ELISA. Taken together, a combination of proper host strain, low-temperature expression, and timely application of osmolytes in the growth medium provided sufficient quantities of soluble recombinant IHNV-NP that has the potential to be used for diagnostic purposes.