Improving water treatment using a novel antibacterial kappa-carrageenan-coated magnetite decorated with silver nanoparticles

In this study, we aimed to fabricate an enhanced antibacterial agent to act against pathogenic bacteria in aqueous environments. To achieve this, silver nanoparticles (AgNPs) were inlaid on a kappa-carrageenan (KC) base and coated on Fe3O4 magnetic cores (Fe3O4@KC@Ag). Superparamagnetic Fe3O4 nanoparticles were designed at the center of the composite nanostructure, allowing magnetic recovery from aqueous media in the presence of a magnet. The synthesized nanoconjugate was characterized in each step using XRD, FT-IR, EDX, FE-SEM, TEM, DLS, VSM, and disk-diffusion antibacterial method. Results show that the nanocomposite system is formed, while the magnetic properties remain practically stable. The agglomeration of the AgNPs was decreased by the trap-like function of KC coating, which resulted in an improved antibacterial activity for the Fe3O4@KC@Ag formulation. These findings suggest that Fe3O4@KC@Ag nanocomposites could be promising agents for combating bacterial infections in aqueous environments.

Spatial and temporal variation of bacterial population in ambient air particulate matters (PM2.5, PM10 and TSP) of Isfahan city, Iran

Introduction: Airborne particles are considered as an important indicator of outdoor air quality. Many health problems have been linked to high concentrations of Particulate Matters (PMs) and their associated microorganisms. The aim of this study, therefore, was to investigate the population of bacteria in PMs in various times and locations. Materials and methods: The PM samples including PM2.5, PM10 and Total Suspended Particles (TSP) were taken from 4 different stations of Isfahan city, Iran on February (cold season) and July (warm season), 2019 using an air sampling pump on culture media. The number of bacterial colonies was counted after 48 h growth in the incubator at 37 oC. The PMs concentration and some morphological characteristics of bacteria were also investigated. Results: The highest number of bacterial colonies was in TSP followed by PM10 and PM2.5. The bacterial populations at two stations in north and east. of the region in the warm season were higher than in the cold season, and the respective situation in the other two stations at south and center of the city was reversed, which seems somehow to have been the result of the PMs concentration of difference of pollution sources in various locations and seasons. Conclusion: This study highlights the importance of PMs pollution especially PM2.5 (i.e. the main factor affecting the air quality of the study area) as the carrier of microbial pollution in the air which could adversely affect human health.

Tetracycline removal enhancement with Fe-saturated nanoporous montmorillonite in a tripartite adsorption/desorption/photo-Fenton degradation process

The adsorption and photo-Fenton degradation of tetracycline (TC) over Fe-saturated nanoporous montmorillonite was analyzed. The synthesized samples were characterized using XRD, FTIR, SEM, and XRF analysis, and the adsorption and desorption of TC onto these samples, as well as the antimicrobial activity of TC during these processes, were analyzed at different pH. Initially, a set of adsorption/desorption experiments was conducted, and surprisingly, up to 50% of TC adsorbed was released from Mt structure. Moreover, the desorbed TC had strong antibacterial activity. Then, an acid treatment (for the creation of nanoporous layers) and Fe saturation of the montmorillonite were applied to improve its adsorption and photocatalytic degradation properties over TC. Surprisingly, the desorption of TC from modified montmorillonite was still high up to 40% of adsorbed TC. However, simultaneous adsorption and photodegradation of TC were detected and almost no antimicrobial activity was detected after 180 min of visible light irradiation, which could be due to the photo-Fenton degradation of TC on the modified montmorillonite surface. In the porous structures of modified montmorillonite high, ˙OH radicals were created in the photo-Fenton reaction and were measured using the Coumarin technique. The ˙OH radicals help the degradation of TC as proposed in an oxidation process. Surprisingly, more than 90% of antimicrobial activity of the TC decreased under visible light (after 180 min) when desorbed from nanoporous Fe-saturated montmorillonite compared to natural montmorillonite. To the best of our knowledge, this is the first time that such a high TC desorption rate from an adsorbent with the least residual antimicrobial activity is reported which makes nanoporous Fe-saturated montmorillonite a perfect separation substance of TC from the environment.

Design of polysaccharidicAloe veragel incorporated PVA/tetracycline electrospun cell culture scaffolds for biomedical applications

In this study, hybrid nanofibrous 3D scaffolds containingAloe vera(AV), polyvinyl alcohol (PVA) and tetracycline hydrochloride (TCH) are fabricated by electrospinning for cell culture applications. The role of polysaccharides present in AV gel is found to enhance the biocompatibility of the nanofibrous scaffolds. Different combinations of the polymers were selected to produce homogenous nanofibers with favorable mean fiber diameter and tensile strength. The surface morphology of the products was studied by SEM and it is found that the mean fiber diameter is decreased to about 188 nm upon addition of the AV component. The electrospun scaffolds were investigated by FT-IR spectroscopy to reveal the chemical structure of the samples and their crystallinity was studied by XRD. The hydrophilicity of the scaffolds was tested by optical contact angle measurements and their mechanical strength was examined by tensile strength tests. It is found that PVA is the main component contributing the mechanical stability of the scaffold structure. The fabricated scaffolds presented a more pronounced inhibitory effect against Gram-positive bacterial strains ofS. aureusandB. cereus. Cell culture experiments using fibroblast L929 murine cells reveals that the AV/PVA/TCH scaffolds are promising for cell growth and the cells are capable of achieving a proper cell adhesion and proliferation. The cell viability experiment by MTT assay exhibits the contributing role of AV gel to L929 cell viability on the AV/PVA/TCH scaffolds.

Design and characterization of Persian gum/polyvinyl alcohol electrospun nanofibrous scaffolds for cell culture applications

Biocompatible electrospun nanofiber scaffolds were fabricated in this study using Persian gum (PG) and poly (vinyl alcohol) (PVA) to build an artificial extracellular matrix for cell growth. The preparation procedure involves mixing various ratios of PG/PVA to be electrospun and seeded with L929 fibroblasts. Upon addition of PG up to 60% to the solutions, a 30% decrease to around 240 μs·cm^-1 is found in electrical conductivity which is in the range of semi-conductive polymers, whereas the surface tension is increased to around 3%. The fabricated scaffolds were characterized by morphological, chemical, thermal and structural analyses including SEM, FTIR spectroscopy, DSC, XRD, and tensile stress. The results showed that incorporation of 50% PG to the polymer solutions causes the formation of nanofibers with the least bead-shaped segments. All ratios of nanofibers containing PG showed significant biocompatibility with the cultured cells, which is presumably due to the radical scavenging feature of PG. The MTT and SEM analyses demonstrated that the scaffolds containing 50% PG possess the optimal cell compatibility, adhesion and proliferation properties. The fabricated PG/PVA cell culture scaffolds are potentially appropriate for wound dressing and cell culture applications in biomedicine.

Production and characterization of biocompatible nanofibrous scaffolds made ofβ-sitosterolloaded polyvinyl alcohol/tragacanth gum composites

Electrospun polyvinyl alcohol (PVA) and tragacanth gum (TG) were used to develop nanofibrous scaffolds containing poorly water-solubleβ-Sitosterol (β-S). Different concentrations and ratios of the polymeric composite includingβ-S (10% w v^-1) in PVA (8% w v^-1) combined with TG (0.5 and 1% w v^-1) were prepared and electrospun. The synthesis method includes four electrospinning parameters of solution concentration, feeding rate, voltage, and distance of the collector to the tip of the needle, which are independently optimized to achieve uniform nanofibers with a desirable mean diameter for cell culture. The collected nanofibers were characterized by SEM, FTIR, and XRD measurements. A contact angle measurement described the hydrophilicity of the scaffold. MTT test was carried out on the obtained nanofibers containing L929 normal fibroblast cells. The mechanical strength, porosity, and deterioration of the scaffolds were well discussed. The mean nanofiber diameters ranged from 63 ± 20 nm to 97 ± 46 nm. The nanofibers loaded withβ-S were freely soluble in water and displayed a remarkable biocompatible nature. The cultured cells illustrated sheet-like stretched growth morphology and penetrated the nanofibrous pores of the PVA/β-S/TG scaffolds. The dissolution was related to submicron-level recrystallization ofβ-S with sufficient conditions for culturing L929 cells. It was concluded that electrospinning is a promising technique for poorly water-solubleβ-S formulations that could be used in biomedical applications.

Biocompatibility of electrospun cell culture scaffolds made from balangu seed mucilage/PVA composites

Synthesis of Balangu (Lallemantia royleana) seed mucilage (BSM) solutions combined with polyvinyl alcohol (PVA) was studied for the purpose of producing 3D electrospun cell culture scaffolds. Production of pure BSM nanofibers proved to be difficult, yet integration of PVA contributed to a facile and successful formation of BSM/PVA nanofibers. Different BSM/PVA ratios were fabricated to achieve the desired nanofibrous structure for cell proliferation. It is found that the optimal bead-free ratio of 50/50 with a mean fiber diameter of ≈180 nm presents the most desirable scaffold structure for cell growth. The positive effect of PVA incorporation was approved by analyzing BSM/PVA solutions through physiochemical assays such as electrical conductivity, viscosity and surface tension tests. According to the thermal analysis (TGA/DSC), incorporation of PVA enhanced thermal stability of the samples. Successful fabrication of the nanofibers is verified by FT-IR spectra, where no major chemical interaction between BSM and PVA is detected. The crystallinity of the electrospun nanofibers is investigated by XRD, revealing the nearly amorphous structure of BSM/PVA scaffolds. The MTT assay is employed to verify the biocompatibility of the scaffolds. The cell culture experiment using epithelial Vero cells shows the affinity of the cells to adhere to their nanofibrous substrate and grow to form continuous cell layers after 72 h of incubation.

Quince seed mucilage coated iron oxide nanoparticles for plasmid DNA delivery

This study investigates the potential of iron oxide nanoparticles (Fe₃O₄) and quince seed mucilage as combined genetic carriers to deliver plasmid DNA (pDNA) through the gastrointestinal system. The samples are characterized by x-ray diffraction (XRD), zeta potential, dynamic light scattering, FT-IR spectroscopy, field emission scanning electron microscopy and vibrating sample magnetometry. The stability of pDNA loading on the nanocarriers and their release pattern are evaluated in simulated gastrointestinal environments by electrophoresis. The XRD patterns reveal that the nanocarriers could preserve their structure during various synthesis levels. The saturation magnetization (M_s) of the Fe₃O₄cores are 56.48 emu g^-1without any magnetic hysteresis. Not only does the loaded pDNA contents experience a remarkable stability in the simulated gastric environment, but also, they could be released up to 99% when exposed to an alkaline environment similar to the intestinal fluid of fish. The results indicate that the synthesized nanoparticles could be employed as efficient low-cost pDNA carriers.

Evaluation of different direct and indirect SELEX monitoring methods and implementation of melt-curve analysis for rapid discrimination of variant aptamer sequences

Systematic Evolution of Ligands by Exponential enrichment (SELEX) is an iterative method for in vitro selection of aptamers from a random synthetic oligonucleotide library. Successful retrieving of aptamers by SELEX relies on optimization of various steps including target immobilization, aptamer partitioning, amplification, and ssDNA generation, which all require spending considerable effort and cost. Furthermore, due to the random nature of the initial library, SELEX may redirect toward the selection of low-affinity aptamers that are over-represented in the ssDNA population due to PCR bias. Thus, precise monitoring of the SELEX process is crucial to ensure the selection of target-specific aptamers. In the present study, we investigated the reliability and simplicity of different direct and indirect monitoring methods including UV-Vis spectroscopy, real-time PCR quantification and melt-curve analysis, electrophoretic mobility shift assay (EMSA) and enzyme-linked oligonucleotide assay (ELONA) for selection of DNA aptamers for a protein target. All the examined methods were capable of illustrating the gradual evolution of specific aptamers by the progression of SELEX and showed almost similar results regarding the identification of the enriched round of selection. Moreover, we describe the use of melt-curve analysis in the colony real-time PCR method as a simple, robust, and repeatable tool for pre-sequencing separation of distinct aptamer clones.

Fermented soybean meal affects the ruminal fermentation and the abundance of selected bacterial species in Holstein calves: a multilevel analysis

The effect of soybean meal (SBM) replacement with fermented SBM (FSBM) on ruminal fermentation and bacterial abundance in Holstein calves was investigated in this study. Thirty nine calves were randomized to: (1) control: 27% SBM + 0% FSBM (FSBM0, n = 13); (2) 18% SBM + 9% FSBM (FSBM9, n = 13); and (3) 13.5% SBM + 13.5% FSBM (FSBM13, n = 13). SBM contained a greater amount of large peptides containing 3 to 10 amino acids (AAs), while FSBM had a greater amount of ammonia nitrogen (NH3-N), free AAs, and small peptides containing 2 to 3 AAs. The calves fed FSBM13 had the lowest acetic acid, NH3-N, and the ratio of acetate to propionate, with the greatest concentration of caproic acid, valeric acid and isovaleric acid in ruminal fluid. Compared to those fed FSBM9 or FSBM13, the calves fed FSBM0 had the greatest proportion of Butyrivibrio fibrisolvens and Ruminococcus albus in rumen fluid. However, the ruminal abundance of Prevotella ruminicola in calves fed FSBM13 was greater than in calves fed FSBM0. Network analysis showed that the abundance of the Ruminococcus albus was associated with large peptides, and butyric acid was correlated with small peptide. Taken together, our findings suggest that FSBM may have the potential to boost calf performance by changing the fermentation products and the relative abundance of some members of the bacterial community in the rumen.

Transient expression of the full-length glycoprotein from infectious hematopoietic necrosis virus in bean (Phaseolus vulgaris) leaves via agroinfiltration

The glycoprotein of infectious hematopoietic necrosis virus (IHNV), the causative agent of acute disease in salmonids, is the only structural protein of the virus that can induce protective immunity in the fish host. Here, the reliability of bean (Phaseolus vulgaris) plant for the production of this viral protein was examined by the transient expression method. Using the syringe agroinfiltration method, leaves of bean plants were transformed with the expression construct encoding the full-length of IHNV glycoprotein (IHNV-G) gene. Furthermore, the transformation efficacy of two infiltration buffers including PBS-A (PBS+acetosyringone) and MMS-A (MES buffer + MgSO₄  + sucrose + acetosyringone) was compared. The analysis of mRNA and dot-blot assay confirmed the transcription and translation of IHNV-G protein in bean leaves. Moreover, Western blotting verified the production of intact, full-length (∼57 kDa) IHNV-G protein in the agroinfiltrated plants. Of note, the production level of IHNV-G using MMS-A agroinfiltration buffer was approximately five times higher compared to PBS-A buffer (0.48 vs. 0.1% of total soluble protein), indicating the effect of infiltration buffer on the transient transformation efficiency. The recombinant protein was purified at the final yield of 0.35 μg/g of fresh leaf tissue, using nickel affinity chromatography. The present work is the first report describing the feasibility of the plant expression platform for the production of IHNV-G protein, which can be served as an oral vaccine against IHNV infection.

Determination of phenolic compounds, antioxidant and anticancer activity of Chrozophora tinctoria accessions collected from different regions of Iran

The present study was conducted to determine the total phenolics, flavonoids, flavonols, anthocyanin, and carotenoids as well as the antioxidant activity of 10 different Crozophora tinctoria accessions originated from Iran. The highest contents of total phenolics, flavonoids, flavonols, anthocyanin, and carotenoids were detected in C.t (2), C.t (10), C.t (10), C.t (9), and C.t (3) accessions, respectively. The highest antioxidant activities of the samples, evaluated using 1,1-diphenyl-2-picrylhydrazyl and phosphomolibdate assays, were detected in C.t (8) and C.t (3), respectively. The highest phenyl aminolyase activity was observed in C.t (4). Ten phenolic compounds, including quercetin, catechin, ellagic acid, rosmarinic acid, hesperetin, eugenol, hesperidin, carvacrol, thymol, and kaempferol were identified and quantified using high-performance liquid chromatography (HPLC) technique. The best anticancer activity against HeLa cell lines was observed at C.t (8) accession, originated from Qazvin Region. This study confirmed that the C. tinctoria accessions with rich phenolics compounds may be recommended as a novel source of natural antioxidants for future aims in medicinal fields. PRACTICAL APPLICATIONS: According to this findings there was high variation among phenolics compounds of C. tinctoria which is revealed by HPLC analysis. This study identified phenolic compounds with antioxidant and anticancer activity in Iranian accessions of C. tinctoria. With an increase in the rate of cancer disease, superior accessions of C. tinctoria may be recommended as a novel source of natural antioxidants for ethno pharmacological aims as cancer therapy, and also in nutraceutical fields.

Molecular evolution and selection pressure analysis of infectious hematopoietic necrosis virus (IHNV) revealed the origin and phylogenetic relationship of Iranian isolates in recent epidemics in Iran

Infectious hematopoietic necrosis virus (IHNV) is the causative agent for a lethal salmonid disease. In this study, we surveyed the IHNV's epidemiology, diversity and the origin of infection in Iran. Phylogenetic analysis revealed that Iranian isolates belonged to one of the two lineages of E genogroup. Subsequently, a combination of phylogenetic, antigenic and structural analysis was performed to investigate the evolution of E genogroup lineages. Site-specific analysis of the viral glycoprotein showed different co-evolving and positively selected sites in each lineage. Most of these sites were mapped to the predicted antigenic patches of the glycoprotein. Further characterization revealed E lineages can be differentiated, in part, by specific mutations at positions 91 and 130, which are located in the structurally flexible regions of the glycoprotein, suggesting a key adaptative role for these sites. These data may assist in better monitoring the emerging isolates in regions infected to IHNV from E genogroup.

Effect of dietary date seed meal as an alternative carbohydrate source on immune-related gene expression of Pacific white shrimp Penaeus vannamei

Current study aimed to examine the effect of dietary date seed meal (DSM) as an alternative carbohydrate ingredient on immune-related genes expression of Pacific white shrimp (Penaeus vannamei). A total number of 750 shrimp (4.0 ± 0.1 g) were randomly assigned into five experimental treatments, each with three replicates. Experimental diets contained 0, 50, 100, 150 and 230 g/kg DSM substituted for both wheat and rice flour. Shrimp were fed at a rate of 5% body weight three times daily and the mRNA expression of α2-macroglobulin (α2-M), lipopolysaccharide and beta-1,3-glucan-binding protein (LGBP), integrin β, and peroxinectin (PX) was studied on five shrimp per treatment after 8 weeks feeding trial. The results showed that replacement of DSM up to 100 g/kg in the diet of P. vannamei caused no significant changes in the expression of α2-M and integrin β, however both of these genes showed lower expression in shrimp fed diets containing 150 and 230 g/kg DSM compared to control group. Moreover, no significant differences were observed in the expression of PX and LGBP between shrimp fed diets containing different amounts of DSM and control group. These findings demonstrated that as an inexpensive source of carbohydrate, DSM could be substituted up to 100 g/kg for wheat and rice flour in the diet of farmed shrimp without suppressive effects on the immune status.

Combined effects of dietary low molecular weight sodium alginate and Pediococcus acidilactici MA18/5M on growth performance, haematological and innate immune responses of Asian sea bass (Lates calcalifer) juveniles

Six weeks feeding trial was conducted to examine the effects of dietary administration of low molecular weight sodium alginate (LMWSA) and Pediococcus acidilactici MA 18/5M (PA) on humoral and mucosal immune responses, haematological parameters and growth performance, of Lates calcarifer juveniles. Fish (12.0 ± 0.2 g) were fed experimental diets as follows: Control (diet 1, basal diet), 5 g kg^-1 LMWSA (diet 2), 10 g kg^-1 LMWSA (diet 3), 0.9 × 10⁷ CFU g^-1 PA (diet 4), 5 g kg^-1 LMWSA + 0.9 × 10⁷ CFU g^-1 PA (Diet 5), and 10 g kg^-1 LMWSA + 0.9 × 10⁷ CFU g^-1 PA (Diet 6). Results indicated a significant (P < 0.05) increase in innate immune parameters including serum lysozyme, bactericidal, hemolytic and respiratory burst activities as well as mucosal immune responses including lysozyme and bactericidal activities, when diet was supplemented with immunostimulants. Moreover, the combined effects of LMWSA with PA resulted in more pronounced immunological responses compared to the control and singular administration. Red and white blood cell counts significantly increased with either singular or combined administration of LMWSA and PA compared with the control group (P < 0.05). The singular administration of PA and combined supplementation of 5 g kg^-1 LMWSA with PA significantly increased growth performance and feed intake compared with other experimental groups (P < 0.05). These results indicated that combined administration of LMWSA and PA can be considered as beneficial feed additive and immunostimulant in L. calcarifer juveniles.

Green synthesis of silver nanoparticles using Glaucium corniculatum (L.) Curtis extract and evaluation of its antibacterial activity

The metal nanoparticles, due to interesting features such as electrical, optical, chemical and magnetic properties, have been investigated repeatedly. Also, the mentioned nanoparticles have specific uses in terms of their antibacterial activity. The biosynthesis method is more appropriate than the chemical method for producing the nanoparticles because it does not need any special facilities; it is also economically affordable. In the current study, the silver nanoparticles (AgNPs) were obtained by using a very simple and low-cost method via Glaucium corniculatum (L.) Curtis plant extract. The characteristics of the AgNPs were investigated using techniques including: X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy. The SEM and TEM images showed that the nanoparticles had a spherical shape, and the mean diameter of them was 53.7 and 45 nm, respectively. The results of the disc diffusion test used for measuring the anti-bacterial activity of the synthesised nanoparticles indicated that the formed nanoparticles possessed a suitable anti-bacterial activity.

Green synthesis of silver nanoparticles with the Arial part of Dorema ammoniacum D. extract by antimicrobial analysis

Silver nanoparticles (SNPs) were synthesised by using the Arial part extract of Dorema ammoniacum D. and characterised by employing UV-visible spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction techniques. Transmission electron microscopy and field emission scanning electron microscopy were applied to investigate the morphological structure of the bio-synthesised SNPs. The antimicrobial activity of SNPs was studied against Gram positive (Bacillus cereus and Staphylococcus aureus) and Gram-negative (Escherichia coli and Salmonella typhimurium) bacteria by employing the disk diffusion agar process. An extremely antimicrobial effect was observed for SNPs. Utilising D. ammoniacum D. as a mediator for the synthesis of SNPs helped to save time and cost.

Changes of vitellogenin and Lipase in captive Sterlet sturgeon Acipenser ruthenus females during previtellogenesis to early atresia

Plasma chemistry, lipid metabolism and vitellogenin gene expression of captive Sterlet sturgeon Acipenser ruthenus were studied in different maturity stages. A total of 32 fish were sampled, and maturity stages were identified on the basis of histological criteria and direct observation. Females were classified to four groups: previtellogenic, vitellogenic, post-vitellogenic, and atresia. Blood, gonad and liver tissue samples were taken through non-lethal biopsy. Our results showed that plasma levels of glucose, cholesterol, triacylglycerol, high-density lipoprotein, low-density lipoprotein, very low-density lipoprotein, calcium, phosphorus, alkaline phosphatase activity, albumin and total protein increased during ovarian development and were highest at post-vitellogenic stage. The lowest amounts in atresia stage demonstrate that lipid and energy imbalance was related to reabsorption and digestion of the yolk. These results suggested that the VLDL was the main plasma lipoprotein component of Sterlet. We determined that lipoprotein lipase and hepatic lipase activity increased during vitellogenesis process which suggested the role of lipase enzymes in regulating blood lipid metabolism. RT-PCR analysis indicates that Vitellogenin (VTG) mRNA could be detected both in livers and ovaries of female Sterlet. Throughout the study, the expression level of VTG gene showed an increase both in ovaries and in livers reaching its peak at late vitellogenesis stage. This strongly indicated a relation between VTG mRNA and ovarian development.

Two Virus-Induced MicroRNAs Known Only from Teleost Fishes Are Orthologues of MicroRNAs Involved in Cell Cycle Control in Humans

MicroRNAs (miRNAs) are ~22 base pair-long non-coding RNAs which regulate gene expression in the cytoplasm of eukaryotic cells by binding to specific target regions in mRNAs to mediate transcriptional blocking or mRNA cleavage. Through their fundamental roles in cellular pathways, gene regulation mediated by miRNAs has been shown to be involved in almost all biological phenomena, including development, metabolism, cell cycle, tumor formation, and host-pathogen interactions. To address the latter in a primitive vertebrate host, we here used an array platform to analyze the miRNA response in rainbow trout (Oncorhynchus mykiss) following inoculation with the virulent fish rhabdovirus Viral hemorrhagic septicaemia virus. Two clustered miRNAs, miR-462 and miR-731 (herein referred to as miR-462 cluster), described only in teleost fishes, were found to be strongly upregulated, indicating their involvement in fish-virus interactions. We searched for homologues of the two teleost miRNAs in other vertebrate species and investigated whether findings related to ours have been reported for these homologues. Gene synteny analysis along with gene sequence conservation suggested that the teleost fish miR-462 and miR-731 had evolved from the ancestral miR-191 and miR-425 (herein called miR-191 cluster), respectively. Whereas the miR-462 cluster locus is found between two protein-coding genes (intergenic) in teleost fish genomes, the miR-191 cluster locus is found within an intron of a protein-coding gene (intragenic) in the human genome. Interferon (IFN)-inducible and immune-related promoter elements found upstream of the teleost miR-462 cluster locus suggested roles in immune responses to viral pathogens in fish, while in humans, the miR-191 cluster functionally associated with cell cycle regulation. Stimulation of fish cell cultures with the IFN inducer poly I:C accordingly upregulated the expression of miR-462 and miR-731, while no stimulatory effect on miR-191 and miR-425 expression was observed in human cell lines. Despite high sequence conservation, evolution has thus resulted in different regulation and presumably also different functional roles of these orthologous miRNA clusters in different vertebrate lineages.