A Versatile Approach for Adaptive Grid Mapping and Grid Flex-Graph Exploration with a Field-Programmable Gate Array-Based Robot Using Hardware Schemes.

Robotic exploration in dynamic and complex environments requires advanced adaptive mapping strategies to ensure accurate representation of the environments. This paper introduces an innovative grid flex-graph exploration (GFGE) algorithm designed for single-robot mapping. This hardware-scheme-based algorithm leverages a combination of quad-grid and graph structures to enhance the efficiency of both local and global mapping implemented on a field-programmable gate array (FPGA). This novel research work involved using sensor fusion to analyze a robot's behavior and flexibility in the presence of static and dynamic objects. A behavior-based grid construction algorithm was proposed for the construction of a quad-grid that represents the occupancy of frontier cells. The selection of the next exploration target in a graph-like structure was proposed using partial reconfiguration-based frontier-graph exploration approaches. The complete exploration method handles the data when updating the local map to optimize the redundant exploration of previously explored nodes. Together, the exploration handles the quadtree-like structure efficiently under dynamic and uncertain conditions with a parallel processing architecture. Integrating several algorithms into indoor robotics was a complex process, and a Xilinx-based partial reconfiguration approach was used to prevent computing difficulties when running many algorithms simultaneously. These algorithms were developed, simulated, and synthesized using the Verilog hardware description language on Zynq SoC. Experiments were carried out utilizing a robot based on a field-programmable gate array (FPGA), and the resource utilization and power consumption of the device were analyzed.

Hardware Schemes for Smarter Indoor Robotics to Prevent the Backing Crash Framework Using Field Programmable Gate Array-Based Multi-Robots.

The use of smart indoor robotics services is gradually increasing in real-time scenarios. This paper presents a versatile approach to multi-robot backing crash prevention in indoor environments, using hardware schemes to achieve greater competence. Here, sensor fusion was initially used to analyze the state of multi-robots and their orientation within a static or dynamic scenario. The proposed novel hardware scheme-based framework integrates both static and dynamic scenarios for the execution of backing crash prevention. A round-robin (RR) scheduling algorithm was composed for the static scenario. Dynamic backing crash prevention was deployed by embedding a first come, first served (FCFS) scheduling algorithm. The behavioral control mechanism of the distributed multi-robots was integrated with FCFS and adaptive cruise control (ACC) scheduling algorithms. The integration of multiple algorithms is a challenging task for smarter indoor robotics, and the Xilinx-based partial reconfiguration method was deployed to avoid computational issues with multiple algorithms during the run-time. These methods were coded with Verilog HDL and validated using an FPGA (Zynq)-based multi-robot system.

A Versatile Approach to Polygonal Object Avoidance in Indoor Environments with Hardware Schemes Using an FPGA-Based Multi-Robot.

Service robots perform versatile functions in indoor environments. This study focuses on obstacle avoidance using flock-type indoor-based multi-robots. Each robot was developed with rendezvous behavior and distributed intelligence to perform obstacle avoidance. The hardware scheme-based obstacle-avoidance algorithm was developed using a bio-inspired flock approach, which was developed with three stages. Initially, the algorithm estimates polygonal obstacles and their orientations. The second stage involves performing avoidance at different orientations of obstacles using a heuristic based Bug2 algorithm. The final stage involves performing a flock rendezvous with distributed approaches and linear movements using a behavioral control mechanism. VLSI architectures were developed for multi-robot obstacle avoidance algorithms and were coded using Verilog HDL. The novel design of this article integrates the multi-robot's obstacle approaches with behavioral control and hardware scheme-based partial reconfiguration (PR) flow. The experiments were validated using FPGA-based multi-robots.

Hardware-Efficient Scheme for Trailer Robot Parking by Truck Robot in an Indoor Environment with Rendezvous.

Autonomous grounded vehicle-based social assistance/service robot parking in an indoor environment is an exciting challenge in urban cities. There are few efficient methods for parking multi-robot/agent teams in an unknown indoor environment. The primary objective of autonomous multi-robot/agent teams is to establish synchronization between them and to stay in behavioral control when static and when in motion. In this regard, the proposed hardware-efficient algorithm addresses the parking of a trailer (follower) robot in indoor environments by a truck (leader) robot with a rendezvous approach. In the process of parking, initial rendezvous behavioral control between the truck and trailer robots is established. Next, the parking space in the environment is estimated by the truck robot, and the trailer robot parks under the supervision of the truck robot. The proposed behavioral control mechanisms were executed between heterogenous-type computational-based robots. Optimized sensors were used for traversing and the execution of the parking methods. The truck robot leads, and the trailer robot mimics the actions in the execution of path planning and parking. The truck robot was integrated with FPGA (Xilinx Zynq XC7Z020-CLG484-1), and the trailer was integrated with Arduino UNO computing devices; this heterogenous modeling is adequate in the execution of trailer parking by a truck. The hardware schemes were developed using Verilog HDL for the FPGA (truck)-based robot and Python for the Arduino (trailer)-based robot.

Pareto optimization with small data by learning across common objective spaces.

In multi-objective optimization, it becomes prohibitively difficult to cover the Pareto front (PF) as the number of points scales exponentially with the dimensionality of the objective space. The challenge is exacerbated in expensive optimization domains where evaluation data is at a premium. To overcome insufficient representations of PFs, Pareto estimation (PE) invokes inverse machine learning to map preferred but unexplored regions along the front to the Pareto set in decision space. However, the accuracy of the inverse model depends on the training data, which is inherently scarce/small given high-dimensional/expensive objectives. To alleviate this small data challenge, this paper marks a first study on multi-source inverse transfer learning for PE. A method to maximally utilize experiential source tasks to augment PE in the target optimization task is proposed. Information transfers between heterogeneous source-target pairs is uniquely enabled in the inverse setting through the unification provided by common objective spaces. Our approach is tested experimentally on benchmark functions as well as on high-fidelity, multidisciplinary simulation data of composite materials manufacturing processes, revealing significant gains to the predictive accuracy and PF approximation capacity of Pareto set learning. With such accurate inverse models made feasible, a future of on-demand human-machine interaction facilitating multi-objective decisions is envisioned.

Evidence for the involvement of branchial Vacuolar-type H+-ATPase in the acidification of the external medium by the West African lungfish, Protopterus annectens, exposed to ammonia-loading conditions.

African lungfishes are obligatory air-breathers with exceptionally high environmental ammonia tolerance. They can lower the pH of the external medium during exposure to ammonia-loading conditions. This study aimed to demonstrate the possible involvement of branchial vacuolar-type H+-ATPase (Vha) in the ammonia-induced acidification of the external medium by the West African lungfish, Protopterus annectens, and to examine whether its capacity to acidify the medium could be augmented after exposure to 100 mmol l-1 NH4Cl for six days. Two full coding cDNA sequences of Vha subunit B (atp6v1b), atp6v1b1 and atp6v1b2, were obtained from the internal gills of P. annectens. The sequence of atp6v1b1 comprised 1548 bp, encoding 515 amino acids (57.4 kDa), while that of atp6v1b2 comprised 1536 bp, encoding 511 amino acids (56.6 kDa). Using a custom-made antibody reactive to both isoforms, immunofluorescence microscopy revealed the collective localization of Atp6v1b (atp6v1b1 and atp6v1b2) at the apical or the basolateral membrane of two different types of branchial Na+/K+-ATPase-immunoreactive ionocyte. The ionocytes labelled apically with Atp6v1b presumably expressed Atp6v1b1 containing a PDZ-binding domain, indicating that the apical Vha was positioned to transport H+ to the external medium. The expression of Atp6v1b was regulated post-transcriptionally, as the protein abundance of Atp6v1b and Vha activity increased significantly in the gills of fish exposed to 100 mmol l-1 NH4Cl for six days. Correspondingly, the fish exposed to ammonia had a greater capacity to acidify the external medium, presumably to decrease the ratio of [NH3] to [NH4+] in order to reduce the influx of exogenous NH3.

ACSL: Adaptive correlation-driven sparsity learning for deep neural network compression.

Deep convolutional neural network compression has attracted lots of attention due to the need to deploy accurate models on resource-constrained edge devices. Existing techniques mostly focus on compressing networks for image-level classification, and it is not clear if they generalize well on network architectures for more challenging pixel-level tasks, e.g., dense crowd counting or semantic segmentation. In this paper, we propose an adaptive correlation-driven sparsity learning (ACSL) framework for channel pruning that outperforms state-of-the-art methods on both image-level and pixel-level tasks. In our ACSL framework, we first quantify the data-dependent channel correlation information with a channel affinity matrix. Next, we leverage these inter-dependencies to induce sparsity into the channels with the introduced adaptive penalty strength. After removing the redundant channels, we obtain compact and efficient models, which have significantly less number of parameters while maintaining comparable performance with the original models. We demonstrate the advantages of our proposed approach on three popular vision tasks, i.e., dense crowd counting, semantic segmentation, and image-level classification. The experimental results demonstrate the superiority of our framework. In particular, for crowd counting on the Mall dataset, the proposed ACSL framework is able to reduce up to 94% parameters (VGG16-Decoder) and 84% FLOPs (ResNet101), while maintaining the same performance of (at times outperforming) the original model.

RNA sequencing, de novo assembly and differential analysis of the gill transcriptome of freshwater climbing perch Anabas testudineus after 6 days of seawater exposure.

To obtain transcriptomic insights into branchial responses to salinity challenge in Anabas testudineus, this study employed RNA sequencing (RNA-Seq) to analyse the gill transcriptome of A. testudineus exposed to seawater (SW) for 6 days compared with the freshwater (FW) control group. A combined FW and SW gill transcriptome was de novo assembled from 169.9 million 101 bp paired-end reads. In silico validation employing 17 A. testudineus Sanger full-length coding sequences showed that 15/17 of them had greater than 80% of their sequences aligned to the de novo assembled contigs where 5/17 had their full-length (100%) aligned and 9/17 had greater than 90% of their sequences aligned. The combined FW and SW gill transcriptome was mapped to 13,780 unique human identifiers at E-value ≤1.0E-20 while 952 and 886 identifiers were determined as up and down-regulated by 1.5 fold, respectively, in the gills of A. testudineus in SW when compared with FW. These genes were found to be associated with at least 23 biological processes. A larger proportion of genes encoding enzymes and transporters associated with molecular transport, energy production, metabolisms were up-regulated, while a larger proportion of genes encoding transmembrane receptors, G-protein coupled receptors, kinases and transcription regulators associated with cell cycle, growth, development, signalling, morphology and gene expression were relatively lower in the gills of A. testudineus in SW when compared with FW. High correlation (R = 0.99) was observed between RNA-Seq data and real-time quantitative PCR validation for 13 selected genes. The transcriptomic sequence information will facilitate development of molecular resources and tools while the findings will provide insights for future studies into branchial iono-osmoregulation and related cellular processes in A. testudineus.

Proteomic Analysis of Zebrafish (Danio rerio) After Chemical Exposure.

Traditional toxicological screens based on the zebrafish model use observable phenotypic endpoints during their development to determine the toxicity of teratogens. Yet toxicity does not always translate to obvious phenotypic changes and the criteria used to score the toxicity of a teratogen are frequently subjected to human perception. The advancement in omics-based technologies has allowed us to quantitatively and objectively determine the toxicity of a teratogen based on biomolecular changes. The field of proteomics has been gaining popularity as a valuable tool in toxicology. Hence, in this chapter, we described a protocol for both label-free and label-based proteomic methods to analyse proteomic changes in both embryos and adult livers of zebrafish exposed to the teratogen TCDD (tetrachlorodibenzo-p-dioxin) as an example.

Tilapia and human CLIC2 structures are highly conserved.

Chloride intracellular channels (CLICs) exist in soluble and membrane bound forms. We have determined the crystal structure of soluble Clic2 from the euryhaline teleost fish Oreochromis mossambicus. Structural comparison of tilapia and human CLIC2 with other CLICs shows that these proteins are highly conserved. We have also compared the expression levels of clic2 in selected osmoregulatory organs of tilapia, acclimated to freshwater, seawater and hypersaline water. Structural conservation of vertebrate CLICs implies that they might play conserved roles. Also, tissue-specific responsiveness of clic2 suggests that it might be involved in iono-osmoregulation under extreme conditions in tilapia.

An integrated approach with the zebrafish model for biomonitoring of municipal wastewater effluent and receiving waters.

Comprehensive monitoring of water pollution is challenging. With the increasing amount and types of anthropogenic compounds being released into water, there are rising concerns of undetected toxicity. This is especially true for municipal wastewater effluents that are discharged to surface waters. This study was designed to integrate zebrafish toxicogenomics, targeted gene expression, and morphological analyses, for toxicity evaluation of effluent discharged from two previously characterized wastewater treatment plants (WWTPs) in Pima County, Arizona, and their receiving surface water. Zebrafish embryos were exposed to organic extracts from the WWTP1 effluent that were reconstituted to represent 1× and 0.5× of the original concentration. Microarray analyses identified deregulated gene probes that mapped to 1666, 779, and 631 unique human homologs in the 1×, 0.5×, and the intersection of both groups, respectively. These were associated with 18 cellular and molecular functions ranging from cell cycle to metabolism and are involved in the development and function of 10 organ systems including nervous, cardiovascular, haematological, reproductive, and hepatic systems. Superpathway of cholesterol biosynthesis, retinoic acid receptor activation, glucocorticoid receptor and prolactin signaling were among the top 11 perturbed canonical pathways. Real-time quantitative PCR validated the expression changes of 12 selected genes. These genes were then tested on zebrafish embryos exposed to the reconstituted extract of water sampled downstream of WWTP1 and another nearby WWTP2. The expression of several targeted genes were significantly affected by the WWTP effluents and some of the downstream receiving waters. Morphological analyses using four transgenic zebrafish lines revealed potential toxicity associated with nervous, hepatic, endothelial-vascular and myeloid systems. This study demonstrated how information can be obtained using adverse outcome pathway framework to derive biological effect-based monitoring tools. This integrated approach using zebrafish can supplement analytical chemistry to provide more comprehensive monitoring of discharged effluents and their receiving waters.

Na+/H+ Exchanger 3 Is Expressed in Two Distinct Types of Ionocyte, and Probably Augments Ammonia Excretion in One of Them, in the Gills of the Climbing Perch Exposed to Seawater.

The freshwater climbing perch, Anabas testudineus, is an euryhaline teleost and an obligate air-breather with the ability to actively excrete ammonia. Members of the Na+/H+ exchanger (NHE) family help maintain intracellular pH homeostasis and ionic balance through the electroneutral exchange of Na+ and H+. This study aimed to obtain, from the gills of A. testudineus, the full cDNA coding sequence of nhe3, and to determine the effects of exposure to seawater or 100 mmol l-1 of NH4Cl in fresh water on its mRNA and protein expression levels. Efforts were also made to elucidate the type of ionocyte that Nhe3 was associated with in the branchial epithelium of A. testudineus. The transcript level and protein abundance of nhe3/Nhe3 were very low in the gills of freshwater A. testudineus, but they increased significantly in the gills of fish acclimated to seawater. In the gills of fish exposed to seawater, Nhe3 was expressed in two distinct types of seawater-inducible Na+/K+-ATPase (Nka)-immunoreactive ionocytes. In Nkaα1b-immunoreactive ionocytes, Nhe3 had an apical localization. As these ionocytes also expressed apical Rhcg1 and basolateral Rhcg2, which are known to transport ammonia, they probably participated in proton-facilitated ammonia excretion in A. testudineus during seawater acclimation. In Nkaα1c-immunoreactive ionocytes, Nhe3 was atypically expressed in the basolateral membrane, and its physiological function is uncertain. For A. testudineus exposed to NH4Cl in fresh water, the transcript and protein expression levels of nhe3/Nhe3 remained low. In conclusion, the branchial Nhe3 of A. testudineus plays a greater physiological role in passive ammonia transport and acid-base balance during seawater acclimation than in active ammonia excretion during environmental ammonia exposure.

Molecular characterization of three Rhesus glycoproteins from the gills of the African lungfish, Protopterus annectens, and effects of aestivation on their mRNA expression levels and protein abundance.

African lungfishes are ammonotelic in water. They can aestivate for long periods on land during drought. During aestivation, the gills are covered with dried mucus and ammonia excretion ceases. In fishes, ammonia excretion through the gills involves Rhesus glycoproteins (RhGP/Rhgp). This study aimed to obtain the complete cDNA coding sequences of rhgp from the gills of Protopterus annectens, and to determine their branchial mRNA and protein expression levels during the induction, maintenance and arousal phases of aestivation. Three isoforms of rhgp (rhag, rhbg and rhcg) were obtained in the gills of P. annectens. Their complete cDNA coding sequences ranged between 1311 and 1398 bp, coding for 436 to 465 amino acids with estimated molecular masses between 46.8 and 50.9 kDa. Dendrogramic analyses indicated that Rhag was grouped closer to fishes, while Rhbg and Rhcg were grouped closer to tetrapods. During the induction phase, the protein abundance of Rhag, but not its transcript level, was down-regulated in the gills, suggesting that there could be a decrease in the release of ammonia from the erythrocytes to the plasma. Furthermore, the branchial transcript levels of rhbg and rhcg decreased significantly, in preparation for the subsequent shutdown of gill functions. During the maintenance phase, the branchial expression levels of rhag/Rhag, rhbg/Rhbg and rhcg/Rhcg decreased significantly, indicating that their transcription and translation were down-regulated. This could be part of an overall mechanism to shut down branchial functions and save metabolic energy used for transcription and translation. It could also be regarded as an adaptive response to stop ammonia excretion. During the arousal phase, it is essential for the lungfish to regain the ability to excrete ammonia. Indeed, the protein abundance of Rhag, Rhbg and Rhcg recovered to the corresponding control levels after 1 day or 3 days of recovery from 6 months of aestivation.

Ammonia exposure affects the mRNA and protein expression levels of certain Rhesus glycoproteins in the gills of climbing perch.

The freshwater climbing perch, Anabas testudineus, is an obligate air-breathing and euryhaline teleost capable of active ammonia excretion and tolerant of high concentrations of environmental ammonia. As Rhesus glycoproteins (RhGP/Rhgp) are known to transport ammonia, this study aimed to obtain the complete cDNA coding sequences of various rhgp isoforms from the gills of A. testudineus, and to determine their mRNA and protein expression levels during 6 days of exposure to 100 mmol l-1 NH4Cl. The subcellular localization of Rhgp isoforms in the branchial epithelium was also examined in order to elucidate the type of ionocyte involved in active ammonia excretion. Four rhgp (rhag, rhbg, rhcg1 and rhcg2) had been identified from the gills of A. testudineus They had conserved amino acid residues for NH4+ binding, NH4+ deprotonation, channel gating and lining of the vestibules. Despite inwardly directed NH3 and NH4+ gradients, there were significant increases in the mRNA expression levels of the four branchial rhgp in A. testudineus at certain time points during 6 days of ammonia exposure, with significant increases in the protein abundances of Rhag and Rhcg2 on day 6. Immunofluorescence microscopy revealed a type of ammonia-inducible Na+/K+-ATPase α1c-immunoreactive ionocyte with apical Rhag and basolateral Rhcg2 in the gills of fish exposed to ammonia for 6 days. Hence, active ammonia excretion may involve NH4+ entering the ionocyte through the basolateral Rhcg2 and being excreted through the apical Rhag, driven by a transapical membrane electrical potential generated by the apical cystic fibrosis transmembrane conductance regulator Cl- channel, as suggested previously.

Aestivation Induces Changes in the mRNA Expression Levels and Protein Abundance of Two Isoforms of Urea Transporters in the Gills of the African Lungfish, Protopterus annectens.

The African lungfish, Protopterus annectens, is ammonotelic in water despite being ureogenic. When it aestivates in mucus cocoon on land, ammonia is detoxified to urea. During the maintenance phase of aestivation, urea accumulates in the body, which is subsequently excreted upon arousal. Urea excretion involves urea transporters (UT/Ut). This study aimed to clone and sequence the ut isoforms from the gills of P. annectens, and to test the hypothesis that the mRNA and/or protein expression levels of ut/Ut isoforms could vary in the gills of P. annectens during the induction, maintenance, and arousal phases of aestivation. Two isoforms of ut, ut-a2a and ut-a2b, were obtained from the gills of P. annectens. ut-a2a consisted of 1227 bp and coded for 408 amino acids with an estimated molecular mass of 44.7 kDa, while ut-a2b consisted of 1392 bp and coded for 464 amino acids with an estimated molecular mass of 51.2 kDa. Ut-a2a and Ut-a2b of P. annectens had a closer phylogenetic relationship with Ut/UT of tetrapods than Ut of fishes. While the mRNA expression pattern of ut-a2a and ut-a2b across various tissues of P. annectens differed, the transcript levels of ut-a2a and ut-a2b in the gills were comparable, indicating that they might be equally important for branchial urea excretion during the initial arousal phase of aestivation. During the maintenance phase of aestivation, the transcript level of ut-a2a increased significantly, but the protein abundance of Ut-a2a remained unchanged in the gills of P. annectens. This could be an adaptive feature to prepare for an increase in the production of Ut-a2a upon arousal. Indeed, arousal led to a significant increase in the branchial Ut-a2a protein abundance. Although the transcript level of ut-a2b remained unchanged, there were significant increases in the protein abundance of Ut-a2b in the gills of P. annectens throughout the three phases of aestivation. The increase in the protein abundance of Ut-a2b during the maintenance phase could also be an adaptive feature to prepare for efficient urea excretion when water becomes available.

Common deregulated gene expression profiles and morphological changes in developing zebrafish larvae exposed to environmental-relevant high to low concentrations of glucocorticoids.

Synthetic glucocorticoids have been detected in environmental waters and their biological potency have raised concerns of their impact on aquatic vertebrates especially fish. In this study, developing zebrafish larvae exposed to representative glucocorticoids (dexamethasone, prednisolone and triamcinolone) at 50 pM to 50 nM from 3 h post-fertilisation to 5 days post-fertilisation were investigated. Microarray analysis identified 1255, 1531, and 2380 gene probes, which correspondingly mapped to 660, 882 and 1238 human/rodent homologs, as deregulated by dexamethasone, prednisolone and triamcinolone, respectively. A total of 248 gene probes which mapped to 159 human/rodent homologs were commonly deregulated by the three glucocorticoids. These homologs were associated with over 20 molecular functions from cell cycle to cellular metabolisms, and were involved in the development and function of connective tissue, nervous, haematological, and digestive systems. Glucocorticoid receptor signalling, NRF2-mediated oxidative stress response and RAR signalling were among the top perturbed canonical pathways. Morphological analyses using four transgenic zebrafish lines revealed that the hepatic and endothelial-vascular systems were affected by all three glucocorticoids while nervous, pancreatic and myeloid cell systems were affected by one of them. Quantitative real-time PCR detected significant change in the expression of seven genes at 50 pM of all three glucocorticoids, a concentration comparable to total glucocorticoids reported in environmental waters. Three genes (cry2b, fbxo32, and klhl38b) responded robustly to all glucocorticoid concentrations tested. The common deregulated genes with the associated biological processes and morphological changes can be used for biological inference of glucocorticoid exposure in fish for future studies.

Molecular Characterization of Aquaporin 1 and Aquaporin 3 from the Gills of the African Lungfish, Protopterus annectens, and Changes in Their Branchial mRNA Expression Levels and Protein Abundance during Three Phases of Aestivation.

African lungfishes can undergo long periods of aestivation on land during drought. During aestivation, lungfishes are confronted with desiccation and dehydration, and their gills become non-functional and covered with a thick layer of dried mucus. Aquaporins (Aqps) are a superfamily of integral membrane proteins which generally facilitate the permeation of water through plasma membranes. This study aimed to obtain the complete cDNA coding sequences of aqp1 and aqp3 from the gills of Protopterus annectens, and to determine their branchial mRNA and protein expression levels during the induction, maintenance and arousal phases of aestivation. Dendrogramic analyses of the deduced Aqp1 and Aqp3 amino acid sequences of P. annectens revealed their close relationships with those of Latimeria chalumnae and tetrapods. During the induction phase, there were significant decreases in the transcript levels of aqp1 and aqp3 in the gills of P. annectens, but the branchial Aqp1 and Aqp3 protein abundance remained unchanged. As changes in transcription might precede changes in translation, this could be regarded as an adaptive response to decrease the protein abundance of Aqp1 and Aqp3 in the subsequent maintenance phase of aestivation. As expected, the branchial transcript levels and protein abundance of aqp1/Aqp1 and aqp3/Aqp3 were significantly down-regulated during the maintenance phase, probably attributable to the shutdown of branchial functions and the cessation of volume regulation of branchial epithelial cells. Additionally, these changes could reduce the loss of water through branchial epithelial surfaces, supplementing the anti-desiccating property of the dried mucus. Upon arousal, it was essential for the lungfish to restore branchial functions. Indeed, the protein abundance of Aqp1 recovered partially, with complete recovery of mRNA expression level and protein abundance of Aqp3, in the gills of P. annectens after 3 days of arousal. These results provide insights into how P. annectens regulates branchial Aqp expression to cope with desiccation and rehydration during different phases of aestivation.

Metabolomic Characterizations of Liver Injury Caused by Acute Arsenic Toxicity in Zebrafish.

Arsenic is one of the most common metalloid contaminants in groundwater and it has both acute and chronic toxicity affecting multiple organs. Details of the mechanism of arsenic toxicity are still lacking and profile studies at metabolic level are very limited. Using gas chromatography coupled with mass spectroscopy (GC/MS), we first generated metabolomic profiles from the livers of arsenic-treated zebrafish and identified 34 significantly altered metabolite peaks as potential markers, including four prominent ones: cholic acid, glycylglycine, glycine and hypotaurine. Combined results from GC/MS, histological examination and pathway analyses suggested a series of alterations, including apoptosis, glycogenolysis, changes in amino acid metabolism and fatty acid composition, accumulation of bile acids and fats, and disturbance in glycolysis related energy metabolism. The alterations in glycolysis partially resemble Warburg effect commonly observed in many cancer cells. However, cellular damages were not reflected in two conventional liver function tests performed, Bilirubin assay and alanine aminotransferase (ALT) assay, probably because the short arsenate exposure was insufficient to induce detectable damage. This study demonstrated that metabolic changes could reflect mild liver impairments induced by arsenic exposure, which underscored their potential in reporting early liver injury.

Glucocorticoid activity detected by in vivo zebrafish assay and in vitro glucocorticoid receptor bioassay at environmental relevant concentrations.

Glucocorticoids are pharmaceutical contaminants of emerging concern due to their incomplete removal during wastewater treatment, increased presence in aquatic environment and their biological potency. The zebrafish is a popular model for aquatic toxicology and environmental risk assessment. This study aimed to determine if glucocorticoids at environmental concentrations would perturb expression of selected glucocorticoid-responsive genes in zebrafish and to investigate their potentials as an in vivo zebrafish assay in complementing in vitro glucocorticoid receptor bioassay. The relative expression of eleven glucocorticoid-responsive genes in zebrafish larvae and liver of adult male zebrafish exposed to three representative glucocorticoids (dexamethasone, prednisolone and triamcinolone) was determined. The expression of pepck, baiap2 and pxr was up-regulated in zebrafish larvae and the expression of baiap2, pxr and mmp-2 was up-regulated in adult zebrafish exposed to glucocorticoids at concentrations equivalent to total glucocorticoids reported in environmental samples. The responsiveness of the specific genes were sufficiently robust in zebrafish larvae exposed to a complex environmental sample detected with in vitro glucocorticoid activity equivalent to 478 pM dexamethasone (DEX-EQ) and confirmed to contain low concentration (0.2 ng/L or less) of the targeted glucocorticoids, and possibly other glucocorticoid-active compounds. The findings provided in vivo relevance to the in vitro glucocorticoid activity and suggested that the environmental sample can perturb glucocorticoid-responsive genes in its original, or half the diluted, concentration as may be found in the environment. The study demonstrated the important complementary roles of in vivo zebrafish and in vitro bioassays coupled with analytical chemistry in monitoring environmental glucocorticoid contaminants.