VirusHound-I: prediction of viral proteins involved in the evasion of host adaptive immune response using the random forest algorithm and generative adversarial network for data augmentation.

Throughout evolution, pathogenic viruses have developed different strategies to evade the response of the adaptive immune system. To carry out successful replication, some pathogenic viruses encode different proteins that manipulate the molecular mechanisms of host cells. Currently, there are different bioinformatics tools for virus research; however, none of them focus on predicting viral proteins that evade the adaptive system. In this work, we have developed a novel tool based on machine and deep learning for predicting this type of viral protein named VirusHound-I. This tool is based on a model developed with the multilayer perceptron algorithm using the dipeptide composition molecular descriptor. In this study, we have also demonstrated the robustness of our strategy for data augmentation of the positive dataset based on generative antagonistic networks. During the 10-fold cross-validation step in the training dataset, the predictive model showed 0.947 accuracy, 0.994 precision, 0.943 F1 score, 0.995 specificity, 0.896 sensitivity, 0.894 kappa, 0.898 Matthew's correlation coefficient and 0.989 AUC. On the other hand, during the testing step, the model showed 0.964 accuracy, 1.0 precision, 0.967 F1 score, 1.0 specificity, 0.936 sensitivity, 0.929 kappa, 0.931 Matthew's correlation coefficient and 1.0 AUC. Taking this model into account, we have developed a tool called VirusHound-I that makes it possible to predict viral proteins that evade the host's adaptive immune system. We believe that VirusHound-I can be very useful in accelerating studies on the molecular mechanisms of evasion of pathogenic viruses, as well as in the discovery of therapeutic targets.

MultiToxPred 1.0: a novel comprehensive tool for predicting 27 classes of protein toxins using an ensemble machine learning approach.

Protein toxins are defense mechanisms and adaptations found in various organisms and microorganisms, and their use in scientific research as therapeutic candidates is gaining relevance due to their effectiveness and specificity against cellular targets. However, discovering these toxins is time-consuming and expensive. In silico tools, particularly those based on machine learning and deep learning, have emerged as valuable resources to address this challenge. Existing tools primarily focus on binary classification, determining whether a protein is a toxin or not, and occasionally identifying specific types of toxins. For the first time, we propose a novel approach capable of classifying protein toxins into 27 distinct categories based on their mode of action within cells. To accomplish this, we assessed multiple machine learning techniques and found that an ensemble model incorporating the Light Gradient Boosting Machine and Quadratic Discriminant Analysis algorithms exhibited the best performance. During the tenfold cross-validation on the training dataset, our model exhibited notable metrics: 0.840 accuracy, 0.827 F1 score, 0.836 precision, 0.840 sensitivity, and 0.989 AUC. In the testing stage, using an independent dataset, the model achieved 0.846 accuracy, 0.838 F1 score, 0.847 precision, 0.849 sensitivity, and 0.991 AUC. These results present a powerful next-generation tool called MultiToxPred 1.0, accessible through a web application. We believe that MultiToxPred 1.0 has the potential to become an indispensable resource for researchers, facilitating the efficient identification of protein toxins. By leveraging this tool, scientists can accelerate their search for these toxins and advance their understanding of their therapeutic potential.

Experimental Observation of Flat Bands in One-Dimensional Chiral Magnonic Crystals.

Spin waves represent the collective excitations of the magnetization field within a magnetic material, providing dispersion curves that can be manipulated by material design and external stimuli. Bulk and surface spin waves can be excited in a thin film with positive or negative group velocities and, by incorporating a symmetry-breaking mechanism, magnetochiral features arise. Here we study the band diagram of a chiral magnonic crystal consisting of a ferromagnetic film incorporating a periodic Dzyaloshinskii-Moriya coupling via interfacial contact with an array of heavy-metal nanowires. We provide experimental evidence for a strong asymmetry of the spin wave amplitude induced by the modulated interfacial Dzyaloshinskii-Moriya interaction, which generates a nonreciprocal propagation. Moreover, we observe the formation of flat spin-wave bands at low frequencies in the band diagram. Calculations reveal that depending on the perpendicular anisotropy, the spin-wave localization associated with the flat modes occurs in the zones with or without Dzyaloshinskii-Moriya interaction.

ß-Carotene Supplementation Improves Pancreas Function during Moderate Ethanol Consumption: Initial Characterization from a Morphological Overview.

Alcohol is believed to harm acinar cells, pancreatic ductal epithelium, and pancreatic stellate cells. After giving ethanol and/or ß-carotene to C57BL/6 mice, our goal was to evaluate their biochemistry, histology, and morpho-quantitative features. There were six groups of C57BL/6 mice: 1. Group C (control), 2. Group LA (low-dose alcohol), 3. Group MA (moderate-dose alcohol), 4. Group B (ß-carotene), 5. Group LA + B (low-dose alcohol combined with ß-carotene), and 6. Group MA + B (moderate-dose alcohol combined with ß-carotene). After the animals were euthanized on day 28, each specimen's pancreatic tissue was taken. Lipase, uric acid, and amylase were assessed using biochemical assessment. Furthermore, the examination of the pancreatic structure was conducted using Ammann's fibrosis scoring system. Finally, the morpho-quantitative characteristics of the pancreatic islets and acinar cells were determined. In the serum of the MA + B group, there were higher amounts of total amylase (825.953 ± 193.412 U/L) and lower amounts of lipase (47.139 ± 6.099 U/L) (p < 0.05). Furthermore, Ammann's fibrosis punctuation in the pancreas revealed significant variations between the groups (p < 0.001). Finally, the stereological analysis of pancreatic islets showed that the groups were different (p < 0.001). These findings suggest that antioxidant treatments might help decrease the negative effects of ethanol exposure in animal models.

Antibiotic discovery against Piscirickettsia salmonis using a combined in silico and in vitro approach.

Piscirickettsia salmonis is one of the main pathogens causing considerable economic losses in salmonid farming. The DNA gyrase of several pathogenic bacteria has been the target of choice for antibiotic design and discovery for years, due to its key function during DNA replication. In this study, we carried out a combined in silico and in vitro approach to antibiotic discovery targeting the GyrA subunit of Piscirickettsia salmonis. The in silico results of this work showed that flumequine (-6.6 kcal/mol), finafloxacin (-7.2 kcal/mol), rosoxacin (-6.6 kcal/mol), elvitegravir (-6.4 kcal/mol), sarafloxacin (-8.3 kcal/mol), orbifloxacin (-7.9 kcal/mol), and sparfloxacin (-7.2 kcal/mol) are docked with good affinities in the DNA binding domain of the Piscirickettsia salmonis GyrA subunit. In the in vitro inhibition assay, it was observed that most of these molecules inhibit the growth of Piscirickettsia salmonis, except for elvitegravir. We believe that this methodology could help to significantly reduce the time and cost of antibiotic discovery trials to combat Piscirickettsia salmonis within the salmonid farming industry.

Review and perspective on bioinformatics tools using machine learning and deep learning for predicting antiviral peptides.

Viruses constitute a constant threat to global health and have caused millions of human and animal deaths throughout human history. Despite advances in the discovery of antiviral compounds that help fight these pathogens, finding a solution to this problem continues to be a task that consumes time and financial resources. Currently, artificial intelligence (AI) has revolutionized many areas of the biological sciences, making it possible to decipher patterns in amino acid sequences that encode different functions and activities. Within the field of AI, machine learning, and deep learning algorithms have been used to discover antimicrobial peptides. Due to their effectiveness and specificity, antimicrobial peptides (AMPs) hold excellent promise for treating various infections caused by pathogens. Antiviral peptides (AVPs) are a specific type of AMPs that have activity against certain viruses. Unlike the research focused on the development of tools and methods for the prediction of antimicrobial peptides, those related to the prediction of AVPs are still scarce. Given the significance of AVPs as potential pharmaceutical options for human and animal health and the ongoing AI revolution, we have reviewed and summarized the current machine learning and deep learning-based tools and methods available for predicting these types of peptides.

Intraoperative Fascial Plane Blocks Facilitate Earlier Tracheal Extubation and Intensive Care Unit Discharge After Cardiac Surgery: A Retrospective Cohort Analysis.

OBJECTIVES: Novel fascial plane blocks may allow early tracheal extubation and discharge from the intensive care unit (ICU). The present study primarily aimed to determine whether fascial plane blocks, in comparison with intravenous analgesia alone, significantly shortened tracheal extubation times in patients undergoing cardiac surgery. The secondary objectives were to compare each block's performance with that of intravenous analgesia alone in terms of the individual tracheal extubation time and length of ICU stay. DESIGN: Retrospective observational study. SETTING: Single-center study. PARTICIPANTS: Patients who underwent cardiac surgery between 2018 and 2019 were identified from a prospective clinical registry. After obtaining ethics approval, the clinical and electronic records of patients undergoing cardiac surgery in 2018 were analyzed. Data of patients receiving fascial plane blocks (erector spinae plane [ESP], pectoral plane I and II [PECs], and serratus anterior plane [SAP] blocks) with intravenous analgesia were compared with those of patients receiving only intravenous analgesia. A propensity score (PS) model was used to control for differences in the baseline characteristics. Adjusted p < 0.05 was considered statistically significant. MEASUREMENTS AND MAIN RESULTS: Of the 589 patients screened, 532 met the inclusion criteria; 404 received a fascial plane block. After PS matching, weighted linear regression revealed that by receiving a block, the predicted extubation time difference was 9.29 hours (b coefficient; 95% CI: -11.98, -6.60; p = 0.022). Similar results were obtained using PS weighting, with a reduction of 7.82 hours (b coefficient; 95% CI: -11.89, -3.75; p < 0.001) in favor of the block. In the fascial-plane-block group, ESP block achieved the best performance. The length of ICU stay decreased by 1.1 days (b coefficient; 95% CI: -1.43, -0.79; p = 0.0001) in the block group. No complications were reported. CONCLUSIONS: Fascial plane block is associated with reduced extubation times and lengths of ICU stay. ESP block achieved the best performance, followed by PECs and SAP blocks. After PS matching, only ESP block reduced the extubation time.

An Updated Overview of the Role of CYP450 during Xenobiotic Metabolization in Regulating the Acute Myeloid Leukemia Microenvironment.

Oxidative stress is associated with several acute and chronic disorders, including hematological malignancies such as acute myeloid leukemia, the most prevalent acute leukemia in adults. Xenobiotics are usually harmless compounds that may be detrimental, such as pharmaceuticals, environmental pollutants, cosmetics, and even food additives. The storage of xenobiotics can serve as a defense mechanism or a means of bioaccumulation, leading to adverse effects. During the absorption, metabolism, and cellular excretion of xenobiotics, three steps may be distinguished: (i) inflow by transporter enzymes, (ii) phases I and II, and (iii) phase III. Phase I enzymes, such as those in the cytochrome P450 superfamily, catalyze the conversion of xenobiotics into more polar compounds, contributing to an elevated acute myeloid leukemia risk. Furthermore, genetic polymorphism influences the variability and susceptibility of related myeloid neoplasms, infant leukemias associated with mixed-lineage leukemia (MLL) gene rearrangements, and a subset of de novo acute myeloid leukemia. Recent research has shown a sustained interest in determining the regulators of cytochrome P450, family 2, subfamily E, member 1 (CYP2E1) expression and activity as an emerging field that requires further investigation in acute myeloid leukemia evolution. Therefore, this review suggests that CYP2E1 and its mutations can be a therapeutic or diagnostic target in acute myeloid leukemia.

Application of Quantitative Structure-Activity Relationships in the Prediction of New Compounds with Anti-Leukemic Activity.

Leukemia invades the bone marrow progressively and, through unknown mechanisms, outcompetes healthy hematopoiesis. Protein arginine methyltransferases 1 (PRMT1) are found in prokaryotes and eukaryotes cells. They are necessary for a number of biological processes and have been linked to several human diseases, including cancer. Small compounds that target PRMT1 have a significant impact on both functional research and clinical disease treatment. In fact, numerous PRMT1 inhibitors targeting the S-adenosyl-L-methionine binding region have been studied. Through topographical descriptors, quantitative structure-activity relationships (QSAR) were developed in order to identify the most effective PRMT1 inhibitors among 17 compounds. The model built using linear discriminant analysis allows us to accurately classify over 90% of the investigated active substances. Antileukemic activity is predicted using a multilinear regression analysis, and it can account for more than 56% of the variation. Both analyses are validated using an internal "leave some out" test. The developed model could be utilized in future preclinical experiments with novel drugs.

Effectiveness of Cerium Oxide Nanoparticles in Non-Alcoholic Fatty Liver Disease Evolution Using In Vivo and In Vitro Studies: A Systematic Review.

Nonalcoholic fatty liver disease (NAFLD) describes a spectrum of liver abnormalities, from benign steatosis to nonalcoholic steatohepatitis (NASH). Because of their antioxidant capabilities, CeNPs have sparked a lot of interest in biological applications. This review evaluated the effectiveness of CeNPs in NAFLD evolution through in vivo and in vitro studies. Databases such as MEDLINE, EMBASE, Scopus, and Web of Science were looked for studies published between 2012 and June 2023. Quality was evaluated using PRISMA guidelines. We looked at a total of nine primary studies in English carried out using healthy participants or HepG2 or LX2 cells. Quantitative data such as blood chemical markers, lipid peroxidation, and oxidative status were obtained from the studies. Our findings indicate that NPs are a possible option to make medications safer and more effective. In fact, CeNPs have been demonstrated to decrease total saturated fatty acids and foam cell production (steatosis), reactive oxygen species production and TNF-α (necrosis), and vacuolization in hepatic tissue when used to treat NAFLD. Thus, CeNP treatment may be considered promising for liver illnesses. However, limitations such as the variation in durations between studies and the utilization of diverse models to elucidate the etiology of NAFLD must be considered. Future studies must include standardized NAFLD models.

In Silico Design of a Chimeric Humanized L-asparaginase.

Acute lymphoblastic leukemia (ALL) is the most common cancer among children worldwide, characterized by an overproduction of undifferentiated lymphoblasts in the bone marrow. The treatment of choice for this disease is the enzyme L-asparaginase (ASNase) from bacterial sources. ASNase hydrolyzes circulating L-asparagine in plasma, leading to starvation of leukemic cells. The ASNase formulations of E. coli and E. chrysanthemi present notorious adverse effects, especially the immunogenicity they generate, which undermine both their effectiveness as drugs and patient safety. In this study, we developed a humanized chimeric enzyme from E. coli L-asparaginase which would reduce the immunological problems associated with current L-asparaginase therapy. For these, the immunogenic epitopes of E. coli L-asparaginase (PDB: 3ECA) were determined and replaced with those of the less immunogenic Homo sapiens asparaginase (PDB:4O0H). The structures were modeled using the Pymol software and the chimeric enzyme was modeled using the SWISS-MODEL service. A humanized chimeric enzyme with four subunits similar to the template structure was obtained, and the presence of asparaginase enzymatic activity was predicted by protein-ligand docking.

Mechanisms Underlying the Selective Therapeutic Efficacy of Carbamazepine for Attenuation of Trigeminal Nerve Injury Pain.

Different peripheral nerve injuries cause neuropathic pain through distinct mechanisms. Even the site of injury may impact underlying mechanisms, as indicated by the clinical finding that the antiseizure drug carbamazepine (CBZ) relieves pain because of compression injuries of trigeminal but not somatic nerves. We leveraged this observation in the present study hypothesizing that because CBZ blocks voltage-gated sodium channels (VGSCs), its therapeutic selectivity reflects differences between trigeminal and somatic nerves with respect to injury-induced changes in VGSCs. CBZ diminished ongoing and evoked pain behavior in rats with chronic constriction injury (CCI) to the infraorbital nerve (ION) but had minimal effect in rats with sciatic nerve CCI. This difference in behavior was associated with a selective increase in the potency of CBZ-induced inhibition of compound action potentials in the ION, an effect mirrored in human trigeminal versus somatic nerves. The increase in potency was associated with a selective increase in the efficacy of the NaV1.1 channel blocker ICA-121431 and NaV1.1 protein in the ION, but no change in NaV1.1 mRNA in trigeminal ganglia. Importantly, local ICA-121431 administration reversed ION CCI-induced hypersensitivity. Our results suggest a novel therapeutic target for the treatment of trigeminal neuropathic pain.SIGNIFICANCE STATEMENT This study is based on evidence of differences in pain and its treatment depending on whether the pain is above (trigeminal) or below (somatic) the neck, as well as evidence that voltage-gated sodium channels (VGSCs) may contribute to these differences. The focus of the present study was on channels underlying action potential propagation in peripheral nerves. There were differences between somatic and trigeminal nerves in VGSC subtypes underlying action potential propagation both in the absence and presence of injury. Importantly, because the local block of NaV1.1 in the trigeminal nerve reverses nerve injury-induced mechanical hypersensitivity, the selective upregulation of NaV1.1 in trigeminal nerves suggests a novel therapeutic target for the treatment of pain associated with trigeminal nerve injury.

Understanding autophagy role in cancer stem cell development.

Cancer stem cells (CSCs) are a small subpopulation of immature cells located in the tumor mass. These cells are responsible for tumor development, proliferation, resistance and spreading. CSCs are characterized by three unique features: the ability to self-renew, differentiation and tumor formation. CSCs are similar to stem cells, but they differ in the malignant phenotype. CSCs become immortal and survive harsh environmental conditions such as hypoxia, starvation and oxidative stress. However, this harsh tumor microenvironment induces the activation of autophagy, which further increases the CSCs stemness profile, and all these features further increase tumorigenicity and metastasis capacity. Autophagy is induced by the extracellular and cellular microenvironment. Hypoxia is one of the most common factors that highly increases the activity of autophagy in CSCs. Therefore, hypoxia-induced autophagy and CSCs proliferation should be elucidated in order to find a novel cure to defeat cancer cells (CSCs and non-CSCs). The remaining challenges to close the gap between the laboratory bench and the development of therapies, to use autophagy against CSCs in patients, could be addressed by adopting a 3D platform to better-mimic the natural environment in which these cells reside. Ultimately allowing to obtain the blueprints for bioprocess scaling up and to develop the production pipeline for safe and cost-effective autophagy-based novel biologics.

A bioinformatics analysis of the CatSper channel in the class Actinopterygii.

The regulation of sperm motility is controlled by several variables, including mainly ion concentrations. In fish, Ca2+ concentrations play an important role in the regulation of sperm motility, and several reports highlight the importance of certain Ca2+ channels in the regulation of this cell function. CatSper is a calcium channel scarcely studied in fish. In the species Salmo salar, it has been shown that it is key in the regulation of sperm motility. Taking into account the relevance of this channel in sperm activation in fish, in this study we evaluated the presence and probable functionality of this channel in the class Actinopterygii. For this purpose, a rational bioinformatic analysis was carried out, which had been previously validated using in vitro techniques by our group. The bioinformatic analysis of the present work revealed that the functionality of CatSper of the species of the class Actinopterygii could be exclusive to freshwater and anadromous fish species. The results of this study showed that only some anadromous and freshwater fish species contain 11 subunits of the CatSper channel, which are enough to trigger sperm motility. Consequently, this study provides new data for a better understanding of the sperm activation mechanism in fish.

Long-term nitrite-oxidizing bacteria suppression in a continuous activated sludge system exposed to frequent changes in pH and oxygen set-points.

Research has proven the adaptation of nitrite-oxidizing bacteria to unfavorable environmental conditions, and this work presents a novel concept to prevent nitrite oxidation during partial nitrification in wastewater. The approach is based on the real-time updating of mathematical models of the process to search for optimal set-points of pH and oxygen concentration in a continuous activated sludge reactor with a high sludge age (20.3 days). A heuristic optimization technique by 13 optimum set-points simultaneously maximized the degree of ammonia oxidation (α) and nitrite accumulation (ß), achieving an (α + ß) = 190% per day. The activated sludge reactor was conducted for 780 days under three control schemes: open-loop control, fuzzy model supervisory control and phenomenological supervisory control. The phenomenological supervisory control system achieved the best results, simultaneously reaching 95% ammonium oxidation and 90% nitrite accumulation. The Haldane kinetics were analyzed using steady-state concentrations of all nitrogen species, concluding that the simultaneous maximization of α + ß led to selecting set-points at the extreme values of the following ranges: pH = 7.5-8.5 and DO = 0.8-1.0 mg O2/L, which enabled the inhibition of one nitrifier species. At the same time, the other one was relieved from inhibition. The 16sRNA assays indicated that the nitrite-oxidizing bacteria presence (genera Nitrobacter and Nitrospira) shifted from 32% to less than 8% after 280 days of continuous operation with optimal pH and oxygen set-points.

Effect of exogenous lipids on cryotolerance of Atlantic salmon (Salmo salar) spermatozoa.

The development of semen cryopreservation strategies is necessary to improve the semen storage technologies of species of great commercial interest for aquaculture. Recent studies demonstrate that lipids play an important role in the fertility and cryotolerance of fish gametes. This study investigated the effect of exogenous lipids in the freezing medium on the post-thaw functional parameters of Salmo salar spermatozoa. Semen samples (n = 12) were incubated in standard extender supplemented with different concentrations of oleic acid (OA, C18:1n9), linoleic acid (LA, C18:2n6), arachidonic acid (ARA, C20:4n6) and cholesterol-loaded cyclodextrin (CLC). Post-thaw motility, membrane integrity, mitochondrial membrane potential (ΔΨm), superoxide anion (O2•-) and fertility rates were analyzed. The results revealed that the semen incubated with 0.003 mmol/L OA increased the motility (~7%) and ΔΨm (~2%) (P < 0.05), but membrane integrity and fertility were not increased. The addition of 0.003 mmol/L LA increased the motility (~4%) and all LA extenders increased the ΔΨm (P < 0.05); however, LA increased the O2•- levels and decreased the membrane integrity and fertility (P < 0.05). Semen incubated with ARA improved sperm motility (~5%), membrane integrity (~10.5%) and fertility rates (~11%) (P < 0.05). The maximum improvement in post-thaw sperm functionality was observed by adding 0.003 mmol/L ARA. In contrast, sperm quality parameters and fertility were decreased by the CLC addition (P < 0.05). This study showed that ARA could be considered as an additive for semen cryopreservation and could be relevant in the reproductive process and reproductive management of Salmo salar.

Effect of in vitro cold acclimation of Deschampsia antarctica on the accumulation of proteins with antifreeze activity.

Deschampsia antarctica has managed to colonize the maritime Antarctic. One of the main factors associated with its tolerance to low temperatures is the presence of apoplastic proteins with antifreeze activity. This work focuses on the effect of cold acclimation of D. antarctica on the accumulation of apoplastic proteins with antifreeze activity. Antifreeze proteins present in apoplastic extracts were purified by ice affinity purification, and their identity was determined by protein sequencing. D. antarctica plants were subjected to 22 days of cold acclimation at 4 °C. The highest content of apoplastic proteins with antifreeze activity was obtained at between 12 and 16 days of acclimation. Protein sequencing allowed their identification with >95% probability. Percentage coverage was 74% with D. antarctica ice recrystallization inhibition protein 1 (DaIRIP1) and 55% with DaIRIP3. Cold acclimation of D. antarctica improved the yield of apoplastic proteins, and resulted in an increase in the antifreeze activity of apoplastic extracts. An in silico analysis suggested that the fluctuations presented by the three-dimensional structures of DaIRIPs help to explain the presence of certain DaIRIPs in apoplastic extracts under the cold acclimation conditions evaluated.

Short-term storage sperm of coho salmon (Oncorhynchus kisutch) at 4 °C: Effect of sperm: Extender dilution ratios and antioxidant butyl-hydroxytoluene (BHT) on sperm function.

Short-term storage of semen is a necessary key procedure in fish; it allows maximizing the use of gametes. Nevertheless, sperm quality decreases during storage has been associated with oxidative stress damage due to an increase in reactive oxygen species (ROS) during storage. This study was designed to optimize a short-term storage protocol for Coho salmon (Oncorhynchus kisutch) spermatozoa, evaluating the effect of extender dilution and the addition of butyl-hydroxytoluene (BHT) antioxidant on sperm function parameters. In the first experiment, fresh semen was diluted in Storfish®: extender dilution (1:2 and 1:3) and a control sample undiluted and stored at 4 °C for 7-days. In both experiments motility (MO), viability and integrity of plasma membrane, mitochondrial membrane potential (MMP) and superoxide anion level (O2-) were evaluated at 0, 3 and 7 days. Result shows that, 1:3 dilution maintained a higher sperm function for a longer period time. In the second experiment, spermatozoa were suspended in Storfish® (1:3) supplemented with two different concentrations of BHT (1.0 mM and 2.0 mM) and a control sample without antioxidant and stored at 4 °C for 7 days. The results demonstrated that, antioxidant-supplemented samples greater MO than control samples (P < 0.05). The viability remained >75% during storage in all groups. MMP was higher in 2.0 mM BHT compared to 1.0 mM and control (P < 0.05), in addition, this concentration reduced O2- level (P < 0.05). In conclusion, sperm: extender dilution 1:3 and adding of 2.0 mM BHT in sperm storage extender may enhance protection sperm function in Oncorhynchus kisutch against effects harmful of the oxidative stress during the in vitro storage.

Role of voltage-gated L-type calcium channel in the spermatozoa motility of Atlantic salmon (Salmo salar).

Ca2+ cations play a key role in the initiation of spermatozoa motility in Atlantic salmon (Salmo salar). In this study we assess the importance of the voltage-gated L-type calcium channels in the spermatozoa motility of Atlantic salmon by combined in vitro and in silico approaches. The results of this study showed that as in other fish species, voltage-gated L-type calcium channels are significant in the spermatozoa motility of Salmo salar. The in vitro assays showed that total and progressive motilities decrease significantly (****p < .001) when Salmo salar spermatozoa are treated with verapamil, which has its binding site in the pore of the voltage-gated L-type calcium channel according to the in silico analysis.

The CatSper channel is present and plays a key role in sperm motility of the Atlantic salmon (Salmo salar).

Among all the Ca2+ channels, CatSper channels have been one of the most studied in sperm of different species due to their demonstrated role in the fertilization process. In fish sperm, the calcium channel plays a key role in sperm activation. However, the functionality of the CatSper channels has not been studied in any of the fish species. For the first time, we studied the relationship of the CatSper channel with sperm motility in a fish, using Atlantic salmon (Salmo salar) as the model. The results of our study showed that the CatSper channel in Salmo salar has chemical-physical characteristics similar to those reported for mammalian CatSper channels. In this work, it was shown that Salmo salar CatSper 3 protein has a molecular weight of approximately 55-kDa similar to Homo sapiens CatSper 3. In silico analyses suggest that this channel forms a heterotetramer sensitive to the specific inhibitor HC-056456, with a binding site in the center of the pore of the CatSper channel, hindering or preventing the influx of Ca2+ ions. The in vitro assay of the sperm motility inhibition of Salmo salar with the inhibitor HC-056456 showed that sperm treated with this inhibitor significantly reduced the total and progressive motility (p < .0001), demonstrating the importance of this ionic channel for this cell. The complementation of the in silico and in vitro analyses of the present work demonstrates that the CatSper channel plays a key role in the regulation of sperm motility in Atlantic salmon.