Genetic signs of multiple colonization events in Baltic ciscoes with radiation into sympatric spring- and autumn-spawners confined to early postglacial arrival

Presence of sympatric populations may reflect local diversification or secondary contact of already distinct forms. The Baltic cisco (Coregonus albula) normally spawns in late autumn, but in a few lakes in Northern Europe sympatric autumn and spring- or winter-spawners have been described. So far, the evolutionary relationships and taxonomic status of these main life history forms have remained largely unclear. With microsatellites and mtDNA sequences, we analyzed extant and extinct spring- and autumn-spawners from a total of 23 Swedish localities, including sympatric populations. Published sequences from Baltic ciscoes in Germany and Finland, and Coregonus sardinella from North America were also included together with novel mtDNA sequences from Siberian C.sardinella. A clear genetic structure within Sweden was found that included two population assemblages markedly differentiated at microsatellites and apparently fixed for mtDNA haplotypes from two distinct clades. All sympatric Swedish populations belonged to the same assemblage, suggesting parallel evolution of spring-spawning rather than secondary contact. The pattern observed further suggests that postglacial immigration to Northern Europe occurred from at least two different refugia. Previous results showing that mtDNA in Baltic cisco is paraphyletic with respect to North American C.sardinella were confirmed. However, the inclusion of Siberian C.sardinella revealed a more complicated pattern, as these novel haplotypes were found within one of the two main C.albula clades and were clearly distinct from those in North American C.sardinella. The evolutionary history of Northern Hemisphere ciscoes thus seems to be more complex than previously recognized

Functional investigation of MiR92b-3p for diagnosis and miRNA-based cure in chemically induced liver injury in fish: a project description

The continued lack of knowledge concerning the molecular background of adverse effects caused by microcystin-LR (MC-LR) is surprising. This toxin requires additional attention, not only for its ability to cause acute poisoning, but also for its ability to initiate cancer in acute doses, and potentially, to promote cancer via chronic exposure to low concentrations in drinking water. Our recent studies on whitefish (Coregonus lavaretus) revealed that long-term exposure to MC-LR resulted in severe liver injury, followed by regeneration of the liver and its unexpected resilience to further toxin uptake. These effects were accompanied by perturbations of hepatic microRNAs (miRNAs) that have target genes involved in cytoskeletal remodeling, cell metabolism, cell cycle regulation, and apoptosis. Among the most pronounced individual alterations, the reduction of MiR92b-3p expression was the most remarkable, and we suggest roles for the miRNA in the aberrant processes of liver cells. This project addresses potential involvement of MiR92b-3p in the as yet unknown regulatory network of MC-induced hepatotoxicity in fish. After a suite of biochemical, physiological, anatomical, and transcriptomic analyses in vitro and in vivo, we will show how MiR92b-3p works in a damaged liver and which processes it targets. Finally, the research will confirm if and how MiR92b-3p can be targeted therapeutically. We expect it to be shown effective enough to pave a way for its use as a tool for treatment of liver damage in fish. What is more, the RNA-based silencing technique that will be used should yield exciting data for our understanding of the system-level biology of vertebrates

Neurotoxicity of cyanobacterial toxins

Eutrophication of marine and fresh waters can lead to excessive development of cyanobacterial blooms, which may contain strains that produce toxins. These toxins are secondary metabolites which can accumulate in the food chain and contaminate drinking water, thus posing a potential threat to the health of humans and aquatic organisms. These toxins include a variety of compounds with different mechanisms; this review focuses on the neurotoxicity of microcystin and other cyanotoxins. Although the hepatotoxic action of microcystins is commonly known, its neurotoxic effects have also been described, e.g. oxidative stress, cytoskeletal changes and changes in protein phosphatase activity. These effects have been partially explained by the discovery in the blood brain barrier of the same membrane transporters involved in microcystins hepatotoxic mechanisms. Additionally, this paper reviews other cyanotoxins that are known or suspected to target cholinergic synapses and voltage gated channels, including anatoxin a, anatoxin a(s), antillatoxins, cylindrospermopsin, homoanatoxin a, jamaicamide, kalkitoxin and saxitoxins. The neurotoxic and cytotoxic effects of the cyanotoxins discussed here are of particular interest because of their pharmacological potential. This review also discusses the potential of these compounds to serve as drugs for cancer and central nervous system failure

CYP1A gene expression in adipose fin of rainbow trout (Oncorhynchus mykiss Walbaum) exposed to benzo[a]pyrene

Proximate to the environment, adipose fin of fish may be considered as a lipid storing tissue, and thus can be a target for either waterborne or dietary polycyclic aromatic compounds (PACs). We determined the effects of benzo[a]pyrene (B[a]P), a model PAC member, on CYP1A gene expression in adipose fin and compared that with the effects in gill of juvenile rainbow trout (Oncorhynchus mykiss Walbaum) using the quantitative reverse transcription polymerase chain reaction (Q-RT-PCR). The results of the study demonstrated that constitutive CYP1A mRNA was present in adipose fin of rainbow trout, but the transcripts were far less abundant than those in gill tissue. We confirmed high CYP1A gene induction potential of the gills in rainbow trout injected with benzo[a]pyrene, but also showed moderately and transiently induced CYP1A mRNA in adipose fin. The modest and transitory gene expression may preclude rainbow trout adipose fin CYP1A mRNA levels from using it as an indicator of sustained exposure of fish to the polycyclic aromatic compounds

Exploring Baltic Sea cyanobacteria for small-molecule inhibitors of microRNA function: a project description

Cyanobacteria constitute a rich source of biologically active and structurally diverse compounds. The pharmacological potential of these compounds resides among others in their ability to control the proliferation and growth of cancer cell lines and potent disease-causing microbial agents. Despite recent scientific advances, the way these compounds interact with the body’s molecular structure are still unclear and science still has to discover how the cyanobacterial metabolites interact with cell structures and how cells react to them. In this project, we will study yet unexamined cyanobacterial metabolites, especially the compounds which act as chemical ligands for microRNA (miRNA) -binding sites, making them promising regulators (inhibitors) of gene networks that are involved in various diseases. We will first develop a stable cell line that constitutively expresses a unique miRNA reporter system. Then, we will conduct a screen on chemical compounds discovered in Baltic cyanobacteria to identify small molecules with inhibitory activity and specificity to MIR92b-3p, which has a significant impact on liver cell behavior in humans. We assume that a successful MIR92b-3p inhibitor will bind to the precursors of MIR92b-3p miRNA, disabling the action of either of the two processing enzymes involved in the biogenesis of any miRNA in a cell (Drosha or Dicer), thus affecting the MIR92b function. The discoveries made with these inhibitory chemical molecules could provide insight into the role of the MIR92 pathway in liver diseases and cancer, and possibly, if promising results appear, they may facilitate a strategy for treating some human diseases in the future

MicroRNA expression in liver of whitefish (Coregonus lavaretus) exposed to microcystin-LR

MicroRNAs (miRNAs) are small, highly conserved, non-coding RNAs that regulate gene expression of target mRNAs through cleavage or translational inhibition. In the field of toxicology, the relationship between toxicity and microRNA expression is poorly understood. In the present study we analyzed the abundance of 9 selected miRNAs (omy-miR-21, omy-miR-21t, omy-miR-122, omy-miR-125a, omy-miR-125b, omy-miR-125t, omy-miR-199-5a, omy-miR-295, omy-let-7a) and mRNA of 3 genes (histone H2A, ribosome protein rpl19, and Dicer which is a miRNA processing enzyme) in liver samples of whitefish exposed to Microcystin-LR (MC-LR) at a dose of 100µg*kg-1body weight for 24 or 48h. In the examined liver tissue, omymiR-122 showed the highest relative constitutive level, what is consistent with data obtained from fish and mammals. Unexpectedly, the reference H2A mRNA level was consistently up-regulated (over 20-fold; P<0.05) in fish liver after both 24 and 48h of exposure to MC-LR. The result may suggest that MC-LR acts as an initiator of specific cell-physiologic signals triggering DNA replication in fish liver cells. MC-LR treatment had no effect on the examined miRNAs levels, except for omy-miR-125a and omy-let-7a. Whereas omy-miR-125a was up-regulated (ER=2.68; S.E. 1.61-6.78; P<0.05), omy-let-7a was down-regulated (ER=0.55; S.E. 0.32-0.79; P<0.05) in whitefish liver after 48h of the treatment with MC-LR, when compared to controls. More work with the fish is essential for understanding the crosstalk of the regulatory network controlled by the two miRNAs in the context of MC-LR toxicity

Preliminary evaluation of ER- and AhR-mediated gene expression patterns in rainbow trout (Oncorhynchus mykiss) liver after short-term exposure to zearalenone in binary mixtures

While estrogenic properties of mycotoxin zearalenone (ZEA) has been an extensively studied issue, little is known about molecular background of its biological responses that cannot be simply explained by the estrogenic potential. The present study describes effects of ZEA (10mg*kg-1 body weight) in binary mixtures either with benzo[a]pyrene (B[a]P), or with 17β-estradiol (E2) on ER- and AhR-dependent gene expression in juvenile rainbow trout liver, evaluated using Real-Time qPCR. The study revealed dual nature of ZEA, as the treatment with this compound alone increased mRNA levels of both ER- and AhR-mediated gene expression. However, our results did not show any synergistic or additive effect of ZEA in binary mixures with E2 or B[a]P on studied gene expression levels. Whether the intriguing potential of ZEA to elicit distinct signals was a result of binding affinity to AhR or/and ER and AhR mutual receptor interactions, should be investigated in further experiments

Influence of zearalenone on selected biochemical parameters in juvenile rainbow trout ( Oncorhynhus mykiss)

Zearalenone (ZEA) is a mycoestrogen frequently found in food and animal feed materials all over the world. Despite its hydrophobic character, ZEA is also found in surface and ground waters which suggests an environmental risk for aquatic animals. Knowledge concerning mycotoxin-related mechanisms of toxicity is still incomplete, e.g. little is known about the influence of ZEA exposure on fish. The aim of this study was to investigate the effect of ZEA on selected biochemical parameters in juvenile rainbow trout after 24, 72, and 168 h of intraperitoneal exposure (10 mg/kg of body weight). The analysis showed a slight tendency towards prolonged blood clotting time and significant iron deficiency in the liver and ovary of exposed animals. However, no differences in aminotransferase (AlaAT, AspAT) activity or glucose levels in fish plasma was observed. The results of this study suggest that although trout exposed to ZEA did not exhibit any distinct symptoms of liver damage, the mycotoxin tested was able interfere with blood coagulation and iron-storage processes