Pyruvate carboxylase as a sensitive protein biomarker for exogenous steroid chemicals

Assessing reproductive effects and epigenetic responses in Austrolebias charrua exposed to Roundup Transorb®: Insights from miRNA profiling and molecular interaction analysis

This study examines the effects of Roundup Transorb® (RDT) exposure on reproductive functions and ovarian miRNA expression in Austrolebias charrua. Exposure to RDT (at 0.065 or 5 mg. L-1 for 96 h) significantly disrupts fertility, evidenced by changes in fertilization rates and egg diameter. Profiling of ovarian miRNAs identified a total 205 miRNAs in A. charrua. Among these, three miRNAs were upregulated (miR-10b-5p, miR-132-3p, miR-100-5p), while ten miRNAs were downregulated (miR-499-5p, miR-375, miR-205-5p, miR-206-3p, miR-203a-3p, miR-133b-3p, miR-203b-5p, miR-184, miR-133a-3p, miR-2188-5p) compared to non-exposed fish. This study reveals that differentially expressed miRNAs are linked to molecular pathways such as steroid hormone biosynthesis, lipid and carbohydrate metabolism, bioenergetics, and antioxidant defense. It also analyzes molecular interactions between miRNAs and target genes during RDT exposure in annual killifish, providing insights into biomarkers in ecotoxicology. Moreover, it provides scope for developing environmental health assessment models based on epigenomic endpoints, supporting the protection of biodiversity and ecosystem services through the quantification of stress responses in living organisms exposed to pesticides.

How does temperature rise affect a freshwater catfish Rhamdia quelen? A proteomic approach

Outside of scientific circles, climate change is a hotly debated topic due to all its consequences. Changes in the temperature can affect aquatic organisms and it is important to understand and to detect earlier signals. This study aimed to analyze how a Neotropical fish species responds to temperature increases, using proteomic analysis as a tool. For this, fish of the species Rhamdia quelen, male and female, were exposed to two temperatures: 25 °C and 30 °C. After 96 h, the animals were anesthetized, euthanized and the liver was collected for proteomic analysis. Using freely available online software and databases (e.g. MetaboAnalyst, Gene Ontology and UniProt), we define the altered proteins in both sexes: 42 in females and 62 in males. Data are available via ProteomeXchange with identifier PXD046475. Differences between the two temperatures were observed mainly in the amino acid metabolic pathways. The cellular process and the immune response was altered, indicating that effects at lower levels of biological organization could serve as a predictor of higher-level effects when temperature rise affects wildlife populations. Thus, we conclude that the increase in temperature is capable of altering important cellular and physiological processes in R. quelen fish, with this response being different for males and females.

Different response of females and males Neotropical catfish (Rhamdia quelen) upon short-term temperature increase

Climate change has been one of the most discussed topics in the world. Global warming is characterized by an increase in global temperature, also in aquatic environments. The increased temperature can affect aquatic organisms with lethal and sublethal effects. Thus, it is necessary to understand how different species respond to temperature. This study aimed to evaluate how the Neotropical catfish species Rhamdia quelen responds to temperature increases. The fish were exposed to temperatures of 25 °C (control) and 30 °C after gradual temperature increase for 7 days. After 96 h in each temperature, the fish were anesthetized, blood was collected, and after euthanasia, brain, liver, posterior kidney, gills, muscle, and gonads were collected. The gonads were used for sexing, while other tissues were used for the hematological, biochemical, genotoxic, and histopathological biomarkers analysis. Hepatic proteomic analysis with a focus on energy production was also carried out. Blood parameter changes in both sexes, including an increase in glucose in males, leukopenia in females, and genotoxicity in both sexes. Hepatic proteins related to energy production were altered in both sexes, but mainly in males. Others biomarker alterations, such as histopathological, were not observed in other tissues; however, the antioxidant system was affected differently between sexes. These showed that R. quelen juveniles, at temperatures higher than its optimum temperature such as 30 °C, has several sublethal changes, such as hematological alterations, antioxidant system activation, and energetic metabolism alteration, especially in males. Thus, short-term temperature rise can affect females and males of R. quelen differently.

Transcriptomic Response to Selective Breeding for Fast Growth in Rainbow Trout (Oncorhynchus mykiss)

Genetic improvement for faster growth is a conventional approach to increase growth rates in aquaculture species; however, the genetic and physiological factors regulating growth performance in fish are not fully characterized. The objective of this study was to identify physiological mechanisms associated with faster growth rates by comparing the liver and muscle transcriptome of a rainbow trout line selectively bred for fast growth (growth line, GL) and a contemporary randomly mated control line (synthetic control, SC) from the same selective breeding program. A third genetic line from a commercial egg supplier (commercial A, CA) was also included to characterize differences in gene expression profiles between populations. Body weight of the GL at harvest was approximately 20% and 8% heavier (p < 0.05) than SC and CA, respectively. There were 145 and 36 differentially expressed genes (DEG) in liver and white muscle, respectively, between the GL and SC that were enriched for the growth hormone/insulin-like growth factor axis (GH/IGF) and PI3K-Akt, JAK-STAT, MAPK, and cAMP signal transduction pathways. A greater concentration of plasma IGF-I was detected in the GL compared with SC (p < 0.05). A unique gene profile was detected in CA, with 11 and 210 DEG in liver and white muscle; these genes associated with innate immunity, complement systems, and metabolic pathways. Collectively, these findings provide a more extensive characterization of the fast-growth phenotype in fish that furthers knowledge of the physiological basis for genetic variation in growth performance in selectively bred rainbow trout.

Identification and characterization of novel and conserved microRNAs in several tissues of the Chinese rare minnow (Gobiocypris rarus) based on illumina deep sequencing technology

BACKGROUND

MicroRNAs (miRNAs), which comprise a large family of endogenous small non-coding RNA molecules, play important roles in the regulation of gene expression in various biological processes. The Chinese rare minnow (Gobiocypris rarus) is a Chinese native fish species and is used extensively as an experimental fish in China; however, relevant biological data, especially miRNA transcriptome data, have not been well documented. To discover conserved and potential novel miRNAs in Chinese rare minnows, a pool of equal amounts of RNA obtained from 6 different adult rare minnow tissues (brain, eye, gill, liver, muscle and heart) was sequenced using illumina deep sequencing technology.

RESULTS

In the present study, 26,930,553 raw reads, representing 2,118,439 unique high-quality reads, were obtained from the pooled small RNA library. Using bioinformatics analysis, 352 conserved and 112 novel Chinese rare minnow miRNAs were first discovered and characterized in this study. Moreover, we found extensive sequence variations (isomiRs) in rare minnow miRNAs, including internal miRNA isomiRs and terminal isomiRs at both the 5' and 3' ends and nucleotide variants. Six conserved and 4 novel miRNAs were selected and validated in 6 different adult rare minnow tissues using quantitative real-time PCR (qPCR). The results showed that miR-30a, miR-30b, and Novel-37 are ubiquitously expressed in a variety of tissues. miR-16a, miR-9, miR-125b, miR-34a, and Novel-69 were predominantly expressed in the brain. Novel-115 and Novel-7 were highly expressed in gills, but were relatively weakly expressed in other tissues. These results provided the expression patterns of miRNA genes in Chinese rare minnow. Finally, based on bioinformatics predictions, we mainly found that Novel-94 and Novel-1b-5p were simultaneously targeted to the 3'UTR of Dmrt1, which controls sex determination and/or sexual differentiation in a variety of metazoans at different sites. Novel-29b targeted the 3'UTR of Foxl2, which is involved in the maintenance of ovarian function and the transcriptional regulation of gonadal differentiation-related genes. Novel-62 and Novel-53 targeted the 3'UTR of ERbeta1 and ERbeta2 (which regulate the transcription of target genes), respectively.

CONCLUSIONS

Rare minnow is a widely used model for assessing the risk of environmental pollution in China. Identifying and characterizing rare minnow miRNA genes is necessary to discover the biological function of miRNAs and to screen for new molecule biomarkers to assess the risk of environmental pollution in the future.

Defining the role of omics in assessing ecosystem health: Perspectives from the Canadian environmental monitoring program

Scientific reviews and studies continue to describe omics technologies as the next generation of tools for environmental monitoring, while cautioning that there are limitations and obstacles to overcome. However, omics has not yet transitioned into national environmental monitoring programs designed to assess ecosystem health. Using the example of the Canadian Environmental Effects Monitoring (EEM) program, the authors describe the steps that would be required for omics technologies to be included in such an established program. These steps include baseline collection of omics endpoints across different species and sites to generate a range of what is biologically normal within a particular ecosystem. Natural individual variability in the omes is not adequately characterized and is often not measured in the field, but is a key component to an environmental monitoring program, to determine the critical effect size or action threshold for management. Omics endpoints must develop a level of standardization, consistency, and rigor that will allow interpretation of the relevance of changes across broader scales. To date, population-level consequences of routinely measured endpoints such as reduced gonad size or intersex in fish is not entirely clear, and the significance of genome-wide molecular, proteome, or metabolic changes on organism or population health is further removed from the levels of ecological change traditionally managed. The present review is not intended to dismiss the idea that omics will play a future role in large-scale environmental monitoring studies, but rather outlines the necessary actions for its inclusion in regulatory monitoring programs focused on assessing ecosystem health.

Serotonergic regulation of melanocyte conversion: A bioelectrically regulated network for stochastic all-or-none hyperpigmentation

Experimentally induced depolarization of resting membrane potential in "instructor cells" in Xenopus laevis embryos causes hyperpigmentation in an all-or-none fashion in some tadpoles due to excess proliferation and migration of melanocytes. We showed that this stochastic process involved serotonin signaling, adenosine 3',5'-monophosphate (cAMP), and the transcription factors cAMP response element-binding protein (CREB), Sox10, and Slug. Transcriptional microarray analysis of embryos taken at stage 15 (early neurula) and stage 45 (free-swimming tadpole) revealed changes in the abundance of 45 and 517 transcripts, respectively, between control embryos and embryos exposed to the instructor cell-depolarizing agent ivermectin. Bioinformatic analysis revealed that the human homologs of some of the differentially regulated genes were associated with cancer, consistent with the induced arborization and invasive behavior of converted melanocytes. We identified a physiological circuit that uses serotonergic signaling between instructor cells, melanotrope cells of the pituitary, and melanocytes to control the proliferation, cell shape, and migration properties of the pigment cell pool. To understand the stochasticity and properties of this multiscale signaling system, we applied a computational machine-learning method that iteratively explored network models to reverse-engineer a stochastic dynamic model that recapitulated the frequency of the all-or-none hyperpigmentation phenotype produced in response to various pharmacological and molecular genetic manipulations. This computational approach may provide insight into stochastic cellular decision-making that occurs during normal development and pathological conditions, such as cancer.

Effects of 17 α-methyltestosterone on transcriptome, gonadal histology and sex steroid hormones in rare minnow Gobiocypris rarus

The 17α-methyltestosterone (MT), a synthetic androgen, is known for its interference effects on the endocrine system. Aiming to investigate the transcriptome profiling of gonads induced by MT and to understand the molecular mechanism by which MT causes adverse effects in fish, transcriptome profiling of gonads, gonadal histology and the sex steroid hormones in response to MT were analyzed in Gobiocypris rarus. Eight libraries, 4 from the ovary and 4 from the testis, were constructed and sequenced and then a total number of clean reads per sample ranging from 7.03 to 9.99 million were obtained. In females, a total of 191 transcripts were differentially regulated by MT, consisting of 102 up-regulated transcripts and 89 down-regulated transcripts. In males, 268 differentially expressed genes with 108 up-regulated and 160 down-regulated were detected upon MT exposure. Testosterone serves as the major sex steroid hormone content in G. rarus of both sexes. The concentrations of 17β-estradiol, testosterone and 11-ketotestosterone were significantly increased in females and decreased in males after MT exposure. Interestingly, MT caused a decreased number of vitellogenic oocytes in the ovary and spermatozoa in the testis. After MT exposure, four differentially expressed genes (ndufa4, slc1a3a, caskin-2 and rpt3) were found in G. rarus of both sexes. Overall, we suggest that MT seemed to affect genes involved in pathways related to physiological processes in the gonads of G. rarus. These processes include the electron transfer of Complex IV, endothelial cell activation, axon growth and guidance, and proteasome assembly and glutamate transport metabolic.