Small amphibians active on dry, sunlit substrates face a physiological conflict: exposure to solar radiation and heat transfer from sun-warmed substrates can increase body temperature and activity, but permeable skin makes such exposure costly through rapid evaporative water loss. Most amphibians reduce this cost by restricting water loss or by remaining in moist microhabitats. The endangered tepui summit toad Oreophrynella quelchii, however, is frequently observed basking for extended periods on dry, exposed sandstone, raising the question of whether this species copes with coupled heat-desiccation stress by suppressing evaporative water loss or by sustaining high evaporative flux and recovering from acute body mass loss. We investigated upper thermal tolerance, behavioural thermal avoidance, and water-loss dynamics in O. quelchii during a standardised dynamic heat-desiccation challenge. To provide ecological context, we also report limited observations from the sympatric frog Pristimantis aureoventris, which is associated with more buffered vegetation microhabitats. Oreophrynella quelchii exhibited CTmax values averaging 32.6 °C. Although this value is not exceptional among amphibians as a whole, it combines with previously reported extremely low CTmin values to produce a broad thermal tolerance breadth for a tropical amphibian. Behavioural avoidance occurred below CTmax, indicating a margin between voluntary retreat and critical thermal failure. During dynamic heat-desiccation exposure, evaporative flux increased with body temperature and vapour pressure deficit and approached passive evaporation estimates from a plaster-model reference, suggesting limited restriction of water loss under fixed-posture exposure. Despite this high evaporative flux, individuals reached the predefined acute body-mass-loss endpoint of approximately 10% initial mass and recovered after rehydration. Limited observations from P. aureoventris indicated lower thermal limits and lower evaporative flux under the same experimental framework, but trials were stopped at a lower safety endpoint and these data are interpreted as contextual rather than comparative because of the small sample size. Overall, our results suggest that O. quelchii does not cope with exposed tepui summit conditions primarily by strongly suppressing evaporative water loss. Instead, its physiological profile appears to combine broad thermal tolerance, behavioural avoidance of critical overheating, high evaporative flux, and the capacity to sustain and recover from acute body mass loss. This tolerance-based strategy may help explain how a small amphibian remains active on exposed tepui sandstone, while highlighting the need to integrate thermal and hydric traits when interpreting amphibian activity in extreme microhabitats.
The incubation period (I) for bird eggs varies among species and is used in establishing allometric relationships. Research on variations in I shed light on the evolutionary mechanisms that gave rise to the differentiation of embryonic development in distinct taxa of birds. Here, using a sampling of 444 images from 444 avian species, 89 families and 30 orders, we calculated their major geometric dimensions: volume (V) and surface area (S). An assessment of the relationship between I and the measured and calculated egg parameters demonstrated the closest and most significant correlation (R = -0.760) between I and the S/V ratio that was adopted as a conditional indicator and reflects the embryo's metabolic rate. Approximation of the values of these parameters made it possible to derive a power-law dependence for the prediction of I depending on the S/V value of a particular egg (R2 = 0.757). The prediction accuracy was higher (R2 = 0.783) if the eggs of the family Procellariiformes (petrels), whose I value is characterized by a longer time, were removed from the general sampling computation. We conclude that the value of the S/V ratio can characterize both the metabolism of an embryo and the conditional thermal conductivity of an egg, which aids in ensuring the temperature regime of egg incubation.
Alanyl-tRNA synthetase 1 (AARS1) has been identified as an enzyme that can recognise L-lactate directly and function as a lactyltransferase. However, its potential regulatory role in hypoxia tolerance remains unclear. In this study, we generated aars1 mutants in zebrafish using the CRISPR/Cas9 technique. We found that homozygous loss of aars1 was lethal, whereas heterozygous loss significantly enhanced hypoxia tolerance. Further investigation revealed that AARS1 negatively regulates HIF1α-mediated hypoxia signaling by promoting HIF1α degradation. Loss of AARS1 enhanced HIF1α stability and hypoxia-responsive gene expression; however, AARS1 restoration reversed this effect. This regulation mainly depended on the autophagy-lysosome pathway, revealing a non-canonical role for AARS1 in modulating HIF1α stability and adaptation to hypoxia.
An animal's metabolism is a vital trait for understanding their lifestyle and behavior in their environment. Metabolism scales with mass with an exponent of approximately ¾ for whole organisms across a variety of taxa, but this value alone cannot contextualize whether the animal is being constrained by morphological features. For water-breathing ectotherms, the balance between metabolic demand and supply is vital due to the low concentration of oxygen in water compared to air. Here we calculated the size dependence of the ratio of metabolic rate to gill surface area (the S metric) for both standard (SMR) and maximum (MMR) metabolic rate for two crustaceans: the Caribbean king crab (Maguimithrax spinosissimus) and Caribbean spiny lobster (Panulirus argus). The S metric scaling exponents for SMR and MMR were 0.11 and 0.17, and - 0.003 and - 0.175 for P. argus and M. spinosissimus, respectively. All S metric scaling exponents were not significantly different from 0, indicating that the gills may not be limiting metabolic demand for either species, although these results alone cannot definitely determine oxygen limitation. Crabs had a more negative S metric exponent during MMR suggesting that as size increases, the balance of metabolic supply and demand could become more constrained with a larger mass. It is important to understand if metabolic demand is being constrained by respiratory surface area as it can better contextualize the behavioral mechanisms these animals use in their environment.
In vertebrates, the canonical steroidogenic acute regulatory (StAR) proteins, which lack N-terminal MENTAL domains, transport cholesterol into mitochondria to initiate steroidogenesis. However, whether a vertebrate-like steroidogenic pathway exists in crustaceans remains controversial. In this study, the complete ORF of SpStAR-like was identified from the transcriptome data of the mud crab Scylla paramamosain and subsequently cloned from testicular cDNA. Bioinformatic analysis showed that the SpStAR-like protein, consistent with other crustacean StAR-like homologs, contains an extra N-terminal MENTAL domain and exhibits higher structural homology with StAR-related lipid transfer proteins (StARLTPs) than with canonical vertebrate StAR proteins. qRT-PCR analysis revealed ubiquitous SpStAR-like expression across all mud crab tissues, with transcript levels in testes significantly higher than those in ovaries and other tissues. The gene was expressed throughout gonadal development in both sexes, peaking at testicular stage T2 and ovarian stage O3, respectively. Functional investigations were performed via RNA interference as well as in vitro and in vivo cholesterol supplementation assays. SpStAR-like knockdown significantly repressed the transcription of steroidogenic genes (Hsd3b, Hsd17b, PGMRC1, ERR, GPCR89) and gonadal development-related genes (IAG, vtg, vtgR, CYP3A24, foxl-2). Exogenous cholesterol treatment elevated ovarian pregnenolone concentrations, as determined by ELISA, and up-regulated all aforementioned target genes. In vivo cholesterol injection increased hemolymph pregnenolone levels and promoted ovarian morphological maturation. This study provides preliminary molecular evidence for steroidogenic regulatory cascades in mud crabs and advances our understanding of crustacean reproductive endocrinology.
With increasing emphasis on extending healthy lifespan, aging research requires vertebrate models that permit efficient mechanistic investigation and intervention testing within practical time and cost constraints. The African turquoise killifish (Nothobranchius furzeri) has attracted growing attention because it combines an exceptionally short life cycle with an intact vertebrate physiological context and an expanding genetic toolkit, enabling relatively rapid evaluation of candidate aging interventions and mechanistic analysis across molecular, tissue, and organismal levels. This review assesses N. furzeri from an integrative-physiology perspective, focusing on germline-soma interactions, gut microbiota-host crosstalk, nutrient sensing and metabolic remodeling, temperature responsiveness, and AMPK-mTOR-linked programs. It also examines expanding genome-engineering and reporter approaches that support mechanistic and tissue-resolved investigation of these physiological processes. Building on recent reviews of killifish biology, disease modeling, regeneration, and the hallmarks of aging, we synthesize evidence across major intervention domains, distinguish established phenotypic effects from incompletely resolved mechanisms, and highlight functional endpoints, methodological standardization, and the appropriate interpretation of the model's translational relevance. Together, these features position N. furzeri as a strategically useful vertebrate platform for rapid mechanistic testing, intervention evaluation, and prioritization of aging-related pathways. Future progress will require improved methodological standardization, tissue-resolved causal studies, and question-driven cross-species validation where appropriate.
Continuous reliable measurements of body temperature are an integral part of physiological and behavioural studies on ectotherms, but often involve invasive surgeries for intracoelomic placement of data loggers. To validate the use of external data loggers, eleven bearded dragons (Pogona vitticeps) were instrumented with three temperature loggers (Ibutton DS1921G) each. One logger was coated with silicone and implanted intraperitoneally during anaesthesia. Following a period of recuperation, a custom-made harness with a logger on both the dorsal and ventral surface was placed around the chest, and the relationships of external and internal temperatures were compared. There was an excellent correlation between the average temperature recorded by the two external loggers and the temperature measured by the implanted logger (Pearson's Correlation: = 0.97 ± 0.03), indicating that the two external temperature loggers provide reliable measures of body temperature in Pogona vitticeps. We propose this simple technique as an alternative to internal loggers to avoid invasive procedures and improve animal welfare.
Endocrine fibroblast growth factors (FGF19 subfamily) play a key role in regulating metabolic homeostasis in vertebrates. However, their functional diversification in salmonids remains poorly understood. In this study, we conducted an integrative characterisation of Fgf19 and Fgf21 signalling in rainbow trout (Oncorhynchus mykiss) by combining phylogenetic, structural and expression analyses. Phylogenetic analyses revealed the conservation of single fgf19 and fgf21 genes, despite the extensive expansion of receptors post-Ss4R (salmonid-specific fourth-round whole genome duplication). Structural modelling and molecular dynamics simulations demonstrated the stable interactions of both ligands to multiple Fgfr isoforms, with receptor-specific energetic profiles and conserved core interaction residues. Tissue expression profiling revealed clear differences from mammalian models, such as predominant hepatic fgf19 expression and the absence of hepatic fgf21 under basal conditions. In addition, there were complex and tissue-dependent distributions of fgfr and klotho transcripts. These findings support a receptor-driven diversification model of endocrine Fgf signalling in salmonids, suggesting enhanced endocrine plasticity associated with the retention of receptors following post-genomic duplication. Taken together, our findings provide new insights into the structural and regulatory organisation of endocrine Fgf signalling, as well as its potential role in metabolic regulation in rainbow trout.
Understanding how organisms allocate energy across competing physiological demands is central to predicting responses to environmental variation. In seasonal environments, shifts in resource availability and activity impose dynamic constraints on energy storage, maintenance and reproduction. Here, we investigated seasonal changes in body composition in the tegu lizard Salvator merianae using the minimally invasive dual-energy X-ray absorptiometry (DEXA) technique. After DEXA validation against direct chemical analysis for this species, male and female individuals were repeatedly scanned across key phases of the annual cycle, including hibernation, reproduction and transition phases between them. Body composition remained largely unchanged during prolonged dormancy, despite fasting and inactivity, with lean and mineral compartments comparatively maintained in both sexes. In contrast, reproduction was associated with the most pronounced seasonal shifts, including reductions in fat reserves and increases in protein- and water-related compartments in both sexes, together with mineral remodeling that was more evident in females. In subsequent months, several of these components shifted back toward pre-reproductive values. These patterns indicate a coordinated reorganization of energy and body resources across seasons, with fat reserves mobilized during reproduction while lean and mineral compartments followed distinct, phase-dependent trajectories. Our results suggest a partial decoupling between energy storage and structural maintenance, consistent with the idea that key functional compartments may be differentially buffered against seasonal constraints. By linking within-individual variation in energy reserves to shifts in physiological demands, this study provides an integrative physiological perspective on how life-history trade-offs are expressed in seasonal environments. More broadly, these findings contribute to understanding how physiological flexibility may influence organismal performance under changing environmental conditions. SUMMARY STATEMENT: Validated DEXA measurements revealed broad maintenance of lean and mineral compartments during dormancy in both sexes, followed by fat mobilization during reproduction and sex-specific mineral remodeling, particularly in females.
Amphibian skin is a multifunctional physiological interface involved in cutaneous respiration, water balance, immune defense, pigmentation, and environmental sensing. High-altitude anurans from the Qinghai-Xizang Plateau (QXP) provide useful models for examining skin-related trait variation under complex environmental conditions. Here, we compared dorsal skin morphology, antioxidant- and pigmentation-related enzyme activities, and skin transcriptomic profiles between two high-altitude anurans, Rana kukunoris and Nanorana pleskei, sampled from lower- and higher-altitude localities. The two species exhibited distinct, trait-specific skin-response profiles. Histological comparisons based on individual-level values did not reach statistical significance, although the group means showed species-specific directional variation. In R. kukunoris, the higher-altitude group had a greater mean epidermal thickness but lower mean dermal thickness, pigment-cell abundance, and pigment-cell area. In N. pleskei, the higher-altitude group had greater mean numbers of epidermal and dermal pigment cells, granular glands, and mucous glands, but lower mean dermal thickness, granular gland area, and pigment-cell area. The biochemical responses were more pronounced: peroxidase activity was elevated in higher-altitude R. kukunoris, whereas tyrosinase activity was markedly elevated in higher-altitude N. pleskei. Transcriptomic analyses identified species-specific candidate functional signatures related to redox regulation, extracellular matrix organization, immune and inflammatory signaling, DNA repair-related processes, and melanogenesis-associated regulation. Overall, species-associated differentiation was more evident at the biochemical and transcriptomic levels than in the measured histological traits. The descriptive histological patterns, together with the enzyme-activity and transcriptomic profiles, suggest that the two species may differ in the relative contributions of structural, antioxidant, and pigmentation-related processes under multifactorial high-altitude environmental conditions. These findings provide a physiological framework for understanding skin-response variation in plateau amphibians without attributing the observed patterns to a single environmental driver.
Natural and anthropogenic environments may have strong impacts on wildlife. The Saint-Pierre and Miquelon archipelago (France) provides a gradient of environmental and anthropogenic pressures relevant to investigate physiological responses in wild brook charr Salvelinus fontinalis populations. This species is the only diadromous species present on the archipelago that is targeted in recreational fisheries, and a better knowledge of native populations is required to support conservation and management activities. We tested the hypothesis that transcriptional phenotypes of brook charr differ among the three main islands of the archipelago and among their respective hydrosystems in response to heterogeneous environmental and anthropogenic pressures. We quantified the expression of 52 candidate genes in both liver and gills for 230 individuals using high-throughput OpenArray qPCR chips developed by the GEN-FISH project. Our results reveal highly spatially structured gene expression patterns. At the island level, local conditions appear to exert specific pressures on brook charr populations. We found a higher expression of genes related to detoxification and oxidative stress in fish captured on Saint-Pierre. In Langlade, the higher expression of genes involved in cellular detoxification could highlight natural geological influences. Transcriptomic responses in gills were more marked than in liver tissue, highlighting the role of gills as a sensitive interface to environmental variations. Overall, the observed signatures underscore the need for more thorough characterization of environmental conditions in Saint-Pierre and Langlade in order to distinguish between anthropogenic and geological effects.
Hair glucocorticoid concentrations are increasingly used as proxies of longer-term glucocorticoid exposure in wild and laboratory animals. In this study, we measured hair corticosterone concentrations in the common vole Microtus arvalis (Arvicolinae) and the striped field mouse Apodemus agrarius (Murinae) to assess: (1) changes associated with three months of laboratory housing in adults; (2) age-related variation between adult voles and 15-day-old juveniles; and (3) sex-related differences in hair corticosterone concentrations. Hair cortisol was also quantified as a complementary and exploratory measure to determine whether it showed a pattern comparable to corticosterone across species and sampling time points. Hair samples were collected from wild-caught adults three days after capture, before the three-month experimental period, and again after three months of laboratory housing. Hair from juvenile voles was collected on postnatal day 15. Corticosterone and cortisol concentrations were quantified using two commercial ELISA kits. Hair corticosterone concentrations increased markedly in M. arvalis during laboratory housing, whereas in A. agrarius the increase was restricted to females. Fifteen-day-old juveniles showed significantly lower hair corticosterone concentrations than adults. An exploratory analysis did not detect an association between maternal and offspring hair corticosterone concentrations, but this analysis was limited by the small number of mothers. Hair cortisol concentrations remained low and showed no statistically detectable changes between sampling time points. These findings indicate that hair glucocorticoid measurements may provide information on longer-term glucocorticoid exposure in small mammals, while emphasising that their interpretation requires consideration of species, developmental stage, sex, housing history and analytical limitations.
The electrosensory system is an important component of the lateral line system in certain aquatic vertebrates. Ampullary organs (AOs), a type of highly sensitive electroreceptor, can detect weak, low-frequency electric fields, playing a critical role in prey detection and predator avoidance in certain species. However, the molecular mechanisms underlying AO function remain poorly understood. The axolotl (Ambystoma mexicanum), a model organism in developmental biology, also possesses AOs. Studies on its AOs are primarily confined to developmental origin and early-stages morphology, with limited attention to molecular and functional properties. In this study, we investigated the distribution, morphological, and transcriptome of juvenile axolotl AOs. In vivo and section staining results affirmed that juvenile axolotl AOs were located exclusively in the head, with a typical canal formed by epidermal invagination. Multiple conservatively expressed lateral line receptor marker genes are likely to be expressed in the AOs of the axolotl. We further found that genes encoding voltage-gated potassium channels (Kv) were highly expressed in AOs, and pharmacological inhibition of these channels impaired electrosensory behavior in axolotls, supporting an important role for Kv channels in axolotl electrosensitivity. Together, these findings enrich our understanding of AO morphology and function, and provide an important foundation for uncovering the molecular mechanisms underlying AO function.
Sex differences in the neural mechanisms underlying energy balance are a fundamental aspect of avian integrative physiology, yet remain poorly understood. The 26RFamide/pyroglutamylated RFamide peptide (26RFa/QRFP) is a hypothalamic orexigenic neuropeptide whose precise role and regulation in songbirds are unknown due to the lack of species-specific analytical tools. To investigate the 26RFa/QRFP system in the zebra finch (Taeniopygia guttata), we developed and validated a novel, high-affinity rabbit antiserum directed against a specific fragment of zebra finch 26RFa/QRFP. The specificity of this reagent was rigorously confirmed through a competitive enzyme-linked immunosorbent assay and cross-validated by the neuroanatomical colocalization of 26RFa/QRFP-like immunoreactive cell bodies and mRNA transcripts in the ventromedial and lateral hypothalamic areas. Using this validated platform, we identified striking female-biased dimorphism in the zebra finch diencephalon, with approximately 3.9-fold higher mature peptide content and 1.5-fold higher mRNA expression in females than in males (P < 0.05). These findings suggest that zebra finches employ sex-specific neuroendocrine strategies for metabolic regulation.
Investigating effects of co-occurring biotic and abiotic stressors on freshwater fishes is crucial to understand how they are coping with environmental change. In this study, we used disturbance cue produced from conspecifics subjected to a simulated predator chase to examine impacts of predation risk on the thermal- and hypoxia tolerance of female Pseudocrenilabrus multicolor, a mouth-brooding African cichlid. Using a series of thermal and hypoxia tolerance trials, we tested 1) how acute exposure to disturbance cue impacts thermal tolerance, 2) how acute exposure to disturbance cue impacts hypoxia tolerance, and 3) how concurrent exposure to warming, hypoxia, and predation risk alters their response. Acute exposure to disturbance cue during normoxia thermal tolerance trials increased critical thermal maximum (CTMax) and decreased agitation temperature (TAg) compared to the water control. When fish were exposed to disturbance cue during hypoxia tolerance trials, the dissolved oxygen level at which they initiated aquatic surface respiration (ASR) was lower than when exposed to water. Finally, acute exposure to disturbance cue during thermal tolerance trials run under hypoxia did not impact CTMax and TAg but elicited a lower temperature at first ASR and increased use of ASR compared to when given the water control. Overall, this suggests that exposure to disturbance cue may increase both thermal and hypoxia tolerance of P. multicolor. However, when these stressors co-occur, exposure to disturbance cue no longer conferred them a thermal tolerance advantage, and the fish appeared more stressed as they relied on ASR more often and at lower temperatures. Therefore, predation risk may be perceived and reacted to differently by prey when multiple abiotic stressors are also present.
Elevated atmospheric carbon dioxide (CO2) can acidify aquatic environments, which several studies have linked to molecular and behavioural responses in fish. However, few studies on CO2-induced acidification have focused on freshwater fishes and the potential for fish to overcome acute responses. Our study investigated the effects of acidification over a 20 d exposure on medaka (Oryzias latipes) behaviour and mRNA transcripts sampled from the brain and gill. Adult medaka were behaviourally assessed on days 0 (control), 5, 10, 15, and 20 following exposure to one of three levels of acidification (6.1pH [∼ 2500 ppm CO2], 5.9 pH [∼ 5500 ppm CO2], and 5.8 pH [∼ 8500 ppm CO2]). Whole brains were sampled on days 0, 5, 10, and 20 from pH treatments 6.1 and 5.8 to monitor relative abundance of mRNA of genes linked to GABA synthesis, reward-seeking behaviour, neurogenesis, feeding behaviour, circadian rhythm, and water and ion transport. Gill tissue was sampled in a similar fashion to explore mRNA abundance of genes related to ion transporters and acid-base regulation. Exposure to pH 5.8 altered some individual and group behaviours, including increased vertical activity and changes in zone preference on day-5. Sustained gill transcript responses occurred by day-5 of exposure, showing decreased relative mRNA abundance at 6.1 pH but increased abundance at 5.8 pH. Brain transcripts showed more delayed and selective adjustments. Our findings suggest that CO2-induced freshwater acidification causes some immediate behavioural responses in medaka, possibly linked to distinct, tissue-specific transcriptional pathways.
Climate change is intensifying heatwaves in tropical freshwaters, reducing thermal safety margins and threatening ectotherms such as the Amazonian prawn Macrobrachium amazonicum, an ecologically and socioeconomically important species. We tested whether acute warming reduces thermal safety margins and induces sublethal physiological impairment. CTMax was measured in a separate group of individuals, acute thermal safety margins were estimated, and prawns were exposed to environmental temperature, 31 °C, and 35 °C for 24 or 48 h to assess mitochondrial respiration, antioxidant defenses, and gill histopathology. M. amazonicum exhibited a high acute CTMax of 42.6 °C; however, thermal safety margins declined to 0.6-3.6 °C under heatwave scenarios. Warming stimulated respiratory complexes, especially Complex IV, suggesting compensatory activation of aerobic metabolism, but also increased proton leak and reduced respiratory control ratio, indicating impaired mitochondrial coupling. GPx activity declined after 48 h, while gill damage increased at 35 °C. Multivariate analysis showed that only 35 °C induced a coordinated physiological shift. Overall, M. amazonicum can enhance respiratory capacity under acute heat, but at the cost of mitochondrial efficiency and gill integrity. Future projections indicated contraction of thermally safe areas, raising concerns for fisheries and aquaculture.
As a myrmecophagous specialist, the Chinese pangolin (Manis pentadactyla) faces digestive challenges due to the chitin-rich diet of ants and termites, especially without teeth to chew. To investigate its digestive strategy, we analyzed the distribution of fecal particle sizes in wild and captive pangolins and measured the mean retention time (MRT) of particles and solutes of food in captive specimens. The mean particle size (dMEAN) in wild pangolin feces (0.452 mm) was slightly larger than that in captive pangolins (0.387 mm), but the difference was not statistically significant. Particle and solute digesta markers showed similar excretion patterns, but exhibited different retention times (particle MRT: 52.58-82.02 h; solute MRT: 29.99-52.81 h), resulting in a selectivity factor of 1.64. These results suggest that this extended retention, facilitated by intestinal elongation and potential gastric separation mechanisms, potentially represents an evolutionary adaptation to cope with a diet composed of both easily digestible components and chitinous exoskeleton relatively refractory to digestion.
Marine shrimp are among the most economically significant aquatic animals facing serious challenges from pathogen infections, particularly the white spot syndrome virus (WSSV), which leads to massive mortality in shrimp aquaculture. An understanding of shrimp defense mechanisms is crucial for developing effective protection strategies. Long noncoding RNA (lncRNA), one of the potential non-coding RNAs, plays regulatory roles in controlling several physiological processes, particularly immune responses. However, the role of lncRNA in WSSV infection in shrimp remains poorly understood. In this study, the putative lncRNAs and differentially expressed lncRNAs (DELs) from the gills of WSSV-infected Pacific white shrimp, Litopenaeus vannamei were identified. The total of 184 DELs were found among 2135 differential expressed genes (DEGs), and the expression of six selected DELs in different shrimp tissues and in the gills of shrimp infected with WSSV were confirmed. Among these DELs, lnc17924 was chosen to investigate its role in WSSV infection due to its significant response to WSSV administration. The lnc17924 knockdown prolonged shrimp survival following WSSV infection suggesting its role in regulation of WSSV infection. Investigation of the interaction network of lnc17924-miRNA-mRNA revealed that lnc17924 interacted with only miRNA_5514, which subsequently interacted with putative 925 differentially expressed mRNAs. Seven lnc17924-miRNA regulated mRNAs, including LvCLEC, LvKAT6A, LvNRE75, LvKLF10, LvHSP90, LvSPARC, and LvPDCD7, exhibited distinct responses following lnc17924 knockdown and WSSV infected shrimp. This study provides lncRNA profiling and comprehensive involvement of lncRNA, especially lnc17924, in the control of WSSV infection, thereby offering molecular insight for shrimp antiviral strategies.
Saline-alkaline fishes maintain internal homeostasis through effective intestinal ion and acid-base regulation. However, the specific intestinal epithelial cell populations mediating these functions remain poorly characterized. Here, we performed single-cell RNA sequencing on 23,909 mid-intestinal cells from juvenile Gymnocypris przewalskii, a fish native to the saline-alkaline Lake Qinghai, to generate a cell atlas of the mid-intestine. Several major cell classes were identified, including epithelial cells (ECs), enteroendocrine cells (EECs), goblet cells (GCs), and leukocytes (LCs), each exhibiting distinct subpopulation heterogeneity. Within the epithelial cell lineage, we identified a distinct cluster characterized by high expression of best4, cftr, and ca2, suggesting a candidate osmoregulatory cell population (referred to as Best4+ cells). To further evaluate this marker set, we compared fish exposed to freshwater with those exposed to artificial lake water and observed significantly elevated gene expression levels of best4, cftr and ca2 in intestinal cells under lake water conditions. Immunofluorescence detection of BEST4 and CA2 in mid-intestinal sections further provided tissue-level support for the epithelial association of these candidate markers. In addition to this candidate osmoregulatory cell population, the atlas also resolved absorptive epithelial cell states, together with heterogeneity within enteroendocrine cell, goblet cell, and leukocyte lineages. Overall, these findings identify a candidate epithelial cell population relevant to intestinal ion and acid-base regulation in G. przewalskii and clarify the cellular basis of intestinal specialization under saline-alkaline stress.
