Photoelectrocatalytic nitrogen fixation is emerging as a promising alternative to the energy-intensive Haber-Bosch process. This study presented Bi2MoO6 composite catalysts, incorporating surface-grown metal Bi, synthesized on conductive nickel foam using a simple one-pot method with glucose as the reducing agent. The introduction of metal Bi enhanced light absorption through the surface plasmon resonance effect, promoted efficient electron-hole pair separation, and improved electron transfer efficiency. The increased nitrogen selectivity of Bi/Bi2MoO6/NF-60 was attributed to the enhanced intrinsic activity and the increase in electrochemically active sites provided by the Bi metal. At an applied voltage of − 1.1 V (vs. RHE), the nitrogen reduction rate for Bi/Bi2MoO6/NF-60 was 30.39 µmol h−1 cm−2, with a Faradaic efficiency of 14.01

Background: As a broad-spectrum fluoroquinolone, enrofloxacin (ENR) is commonly employed to manage bacterial infections in aquatic species. Nevertheless, there have been no documented pharmacokinetic and residue studies conducted on Dybowski’s frog (Rana dybowskii). Therefore, the objective of our study was to characterize the pharmacokinetics (PK) of ENR and its metabolite ciprofloxacin (CIP) in R. dybowskii, establish withdrawal times, and evaluate the physiological effects associated with ENR administration. Methods: Adult Rana dybowskii (120 individuals; 60 males and 60 females) were sex-separated and acclimated in four tanks. Prior to dosing, three males and three females were randomly selected as untreated controls (without ENR administration). Following the oral gavage of ENR (10 mg/kg), blood, liver, and kidney tissues were collected at 0.25, 0.5, 1, 1.5, 2, 4, 6, 8, 12, 24, 36, 48, and 72 h (n = 6) for pharmacokinetic analysis. Muscle and oviduct tissues were additionally sampled at 1, 3, 7, 15, and 30 days post-dose (n = 6) for ENR content determination. Serum/tissue ENR concentrations were measured via Liquid Chromatography–Tandem Mass Spectrometry (LC-MS/MS) and analyzed using a non-compartmental model (WinNonLin 6.1 software) to calculate PK parameters including peak time (Tmax), peak concentration (Cmax), and area under the curve (AUC0−t). In studying the physiology effects of ENR administration, biochemical enzyme activities and gene expressions in the liver and intestine were assessed post-ENR administration. Results: ENR demonstrated rapid absorption and extensive distribution in R. dybowskii. The withdrawal periods were determined to be over 33 days for females and 34 days for males in R. dybowskii. Following ENR administration, there was an increase in immune enzymes (AKP (alkaline phosphatase) and ACP (acid phosphatase)) as well as glycolytic enzymes (HK (hexokinase), PK (pyruvate kinase), PFK (phosphofructokinase)). Antioxidant enzyme levels, specifically SOD (superoxide dismutase) and CAT (catalase), peaked at 1.5 h post-ENR administration but subsequently declined by the 8 h mark. Additionally, following ENR treatment, IGF1, PI3K, and Akt exhibited up-regulation, whereas Keap1 and GYS1 showed down-regulation. Conclusions: The administration of ENR at a dosage of 10 mg/kg significantly enhances the activities of AKP and ACP, promotes glycolysis, and activates the Keap1/Nrf2 and PI3K-Akt signaling pathways in R. dybowskii. These findings establish a foundation for the rational application of ENR and the determination of withdrawal times in frog aquaculture.

Chicory is a unique and nutritious vegetable crop. However, the molecular mechanisms underlying anthocyanin biosynthesis in chicory remain poorly understood. We combined transcriptomics and metabolomics analyses to explore the molecular basis of anthocyanin biosynthesis in red-budded (Z1) and yellow-budded (Z7) chicory. Integrated transcriptomics and metabolomics analyses were performed to investigate the molecular basis of anthocyanin biosynthesis in chicory. A total of 26 key structural genes, including F3’H, DFR, CHS, and ANS, were identified and enriched in pathways such as flavonoid and anthocyanin biosynthesis. Additionally, 29 transcription factors were identified, including 11 MYB, five bHLH, and two WD40 transcription factors, with seven MYB genes upregulated and four genes downregulated, indicating their roles in regulating anthocyanin biosynthesis. Notably, the MYB transcription factor, CI35997, which is homologous to RLL2A in lettuce, was predicted to positively regulate anthocyanin biosynthesis. Other transcription factors, such as AP2/ERF, bZIP, NAC, and Trihelix, have also been implicated. Metabolomics analysis revealed that cyanidin derivatives were the main contributors to the red coloration of chicory buds, with cyanidin-3-O-(6-O-malonyl)-glucoside being the most abundant. Furthermore, a competitive relationship between lignin and anthocyanin biosynthesis was observed, wherein the downregulation of lignin-related genes enhanced anthocyanin accumulation. This study identified key structural genes and transcription factors that offer molecular-level insights into anthocyanin biosynthesis in chicory. These findings provide valuable guidance for genetic improvement of chicory and other crops with high anthocyanin content.

Fatty acids (FAs), especially the polyunsaturated fatty acids (PUFAs), play pivotal roles in growth and development. Fish possess a remarkable ability to synthesize PUFAs, rendering them a crucial and significant source of these essential FAs for human consumption. Despite extensive research on the metabolic processes of FAs, the primary processes underlying FA content variation and corresponding regulatory mechanisms remain largely unexplored. We quantified the muscular FA profiles of 304 common carp samples. High variation in muscle FA content among samples was observed, with the coefficients of variation ranging from 0.36 to 0.92. With genome-wide association studies (GWAS), we identified 1410 SNPs significantly associated with the FA content. The genetic variation at genes participating in oxidation, ubiquitination, and transcriptional factors was associated with the content of multiple FAs, while few variants were observed in the FA-synthesis genes. For the total PUFA (TPUFA) content, transcriptome analysis of groups with the highest and lowest TPUFA content identified 715 differentially expressed genes (DEGs), including genes involved in oxidation and ubiquitination. Using multiple genomic selection programs with the associated SNPs for FA content, we obtained high and positive correlations ranging from 0.65 to 0.92 between the real FA contents and estimated breeding values. These findings manifested the major-effect processes governing the differences in muscular FA content and their regulatory mechanisms. The optimal genomic selection programs provide novel and feasible perspectives to enhance FA content in common carp.

While the evolution of mitochondrial protein-coding genes in angiosperms has been extensively studied, the post-transcriptional RNA processing remains under-explored. Leveraging newly generated and public RNA-seq data from twenty representative angiosperms, we systematically inferred the gain-and-loss dynamics of RNA editing sites within mitochondrial protein-coding genes. Our findings reveal magnoliids retain more ancestral RNA editing sites compared to monocots and eudicots. Furthermore, we uncovered contrasting correlations between gene expression levels and RNA editing density: negative in core mitochondrial genes but positive in variable genes. We also identified widespread occurrence of stop codon-lacking transcripts of four genes (ccmC, nad6, sdh3 and sdh4) across angiosperms, a phenomenon mainly reported in Arabidopsis thaliana. Besides the known t-element previously identified in A. thaliana, we revealed another distinct motif that may contribute to the post-transcriptional processing of nad6 transcripts. Novel stem-loop motifs that may mediate the formation of stop codon-lacking transcripts of ccmC, sdh3 and sdh4 genes were also identified. Collectively, our study sheds light on the ancestral RNA editing characteristics of angiosperm mitochondrial genes, and provides evidence that the processing-derived stop codon-lacking transcripts predate the divergence of angiosperms.

Bacterial co-infections pose a significant threat to aquaculture, often leading to more severe outcomes compared than mono-infections. Understanding the underlying mechanisms is essential to preventing and controlling diseases. In this study, we investigated the effects of mono-infection and co-infection with Flavobacterium psychrophilum (Fp) and Aeromonas salmonicida (As) on rainbow trout (Oncorhynchus mykiss). Results indicated that the mortality rate in the co-infection group was significantly higher than that in the mono-infected groups, with more severe histopathological damage observed in the liver and muscle tissues. On day 7 post-infection, the antioxidant enzyme (SOD and CAT) activity in the liver of the co-infection group peaked and subsequently declined. Transcriptomic analysis revealed that Fp mono-infection primarily activated the Toll-like receptor signaling pathway, whereas As mono-infection activated the MAPK signaling pathway. In contrast, co-infection (Fp + As) showed significant enrichment of DEGs in the p53 pathway, suggesting a unique apoptotic response potentially contributing to host defense through the elimination of compromised cells. This study demonstrates that co-infection with F. psychrophilum and A. salmonicida synergistically exacerbates disease progression in rainbow trout. These findings provide novel insights into co-infection risks, elucidate key immunopathological pathways, and establish a scientific basis for developing targeted disease interventions in aquaculture.

Fish are rich sources of amino acids (AAs), particularly human essential amino acids (HEAAs). Exploring the regulatory mechanisms behind the changes in the combined AA content in the fillet and enhancing the content of AAs, especially HEAAs, in fillets of farmed fish is crucial for meeting human nutritional needs. After hot acidic hydrolysis of 304 common carp fillets, we quantified the contents of 17 single AAs and 5 AA groups and observed significant variations among them. Except for Pro, 16 single AAs and all AA groups showed medium-to-high heritabilities over 0.2. Through a genome-wide association study (GWAS), we identified 1974 SNPs and candidate genes associated with at least one AA content. Using transcriptome data from groups with the highest and lowest contents for each AA, 7089 candidate genes were related to the concentrations of at least two AAs. For the total HEAA content, 121 SNPs and their associated genes preferred ATPase-coupled transmembrane transporter activity, and 4727 differentially expressed genes were enriched in cytokine activity, chemokine activity, oxidoreductase activity, and ion binding. With the optimal genomic selection programs and associated SNPs, the correlation between the actual AA contents and estimated breeding values was high and positive, ranging from 0.76 to 0.90. These findings revealed the major-effect processes and regulatory mechanisms modulating the differences in fillet AA contents. The genomic selection programs will guide the future selection of common carp with high AA contents.

The presence of intermuscular bones severely affects the edibility and value-added processing of crucian carp (Carassius auratus), becoming a constraint to the high-quality development of its industry. Our previous study identified bmp6 as the key osteogenic regulator and successfully developed a new crucian carp strain lacking intermuscular bones (WUCI) using CRISPR/Cas9 technology. To accelerate its industrialization, we comprehensively assessed WUCI’s growth performance, hematological parameters, antioxidant capacity, innate immunity, and disease resistance. The results demonstrated that the WUCI exhibited significant growth performance compared to the wild-type crucian carp (WT), with significantly higher weight gain (WG) and specific growth rate (SGR) (p < 0.05) from one month to four months of age. The α-amylase (α-AL) activity of the liver and intestines of WUCI was significantly higher than that of WT. WUCI also displayed enhanced intestinal antioxidant capacity, with superoxide dismutase (SOD) and catalase (CAT) activities significantly higher than those in WT (p < 0.05). The malondialdehyde (MDA) content in the spleen of WUCI was significantly lower than that of WT (p < 0.05); no differences were observed in the liver and intestines (p > 0.05). Additionally, hepatic acid phosphatase (ACP) activity in WUCI was significantly higher than that in WT (p < 0.05). In contrast, splenic ACP and intestinal alkaline phosphatase (ALP) activities were significantly lower than those in WT (p < 0.05). Notably, the iron concentration in the serum was significantly higher in WUCI than in the WT (p < 0.05). Meanwhile, WUCI exhibited significantly lower a expression of hepcidin, TF, and TFR1 mRNA in the liver compared to WT (p < 0.05), while FPN mRNA expression was significantly higher (p < 0.05). Routine blood tests revealed significantly lower WBC in WUCI compared to that of WT (p < 0.05). Following an Aeromonas hydrophila challenge, WT demonstrated a rapid transcriptional induction of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) and immunoregulatory mediators (IL-10, TGF-β), with mRNA levels reaching maximal expression at 24 h post-infection (hpi) followed by progressive attenuation. In contrast, WUCI exhibited a delayed immune activation profile characterized by the peak expression of TNF-α, IL-1β, IL-6, and IL-10 transcripts after 72 hpi, with the maximum transcript abundance remaining lower than corresponding peak values observed in WT at 24 hpi. Finally, we observed that the mortality rate of WUCI was slightly higher post A. hydrophila infection when compared to WT, but was not significant (p > 0.05). In conclusion, this study provides a comprehensive evaluation of WUCI, revealing its distinct growth advantages, physiological adaptations, and immune function, presenting its potential for aquaculture breeding applications.

Multiple distinct specialized regions shape the architecture of maize leaves. Among them, the fringe-like and wedge-shaped auricles alter the angle between the leaf and stalk, which is a key trait in crop plant architecture. As planting density increased, a small leaf angle (LA) was typically selected to promote crop light capture efficiency and yield. In the present study, we characterized two paralogous INDETERMINATE DOMAIN (IDD) genes, ZmIDD14 and ZmIDD15, which contain the Cys2-His2 zinc finger domain and function redundantly to regulate auricle development and LA in maize. Loss-of-function mutants showed decreased LA by reducing adaxial sclerenchyma thickness and increasing the colourless cell layers. In addition, the idd14;idd15 double mutant exhibited asymmetrically smaller auricles, which might cause by a failed maintenance of symmetric expression of the key auricle size controlling gene, LIGULELESS(LG1). The transcripts of ZmIDD14 and ZmIDD15 enriched in the ligular region, where LG1 was highly expressed, and both proteins physically interacted with ZmILI1 to promote LG1 transcription. Notably, the idd14;idd15 enhanced the grain yield of hybrids under high planting densities by shaping the plant architecture with a smaller LA. These findings demonstrate the functions of ZmIDD14 and ZmIDD15 in controlling the abaxial/adaxial development of sclerenchyma in the midrib and polar development along the medial-lateral axes of auricles and provide an available tool for high-density and high-yield breeding in maize.

The common carp (Cyprinus carpio) is a crucial freshwater species cultivated worldwide for food consumption. Female carp have better growth performance than males, which fascinates scholars to uncover the mechanism of gonadal differentiation and produce mono-sex populations. However, the mechanism of ovarian development at single-cell resolution is limited. Here, we conducted single-nucleus RNA sequencing in adolescent common carp ovaries. Our study obtained transcriptional profiles of 13,155 nuclei and revealed 13 distinct cell clusters in the ovaries, including three subtypes of germ cells and four subtypes of granulosa cells. We subsequently performed pseudotime trajectory analysis to delineate potential mechanisms underlying the development of germ cells and granulosa cells. We identified 1250 dynamic expression genes in germ cells and 1815 in granulosa cells (q-value < 0.01), including zp3, eif4a2 and aspm in germ cells and fshr and esr1 in granulosa cells. The functional annotation showed that dynamic expression genes in germ cells were involved in sperm–egg recognition and some terms related to meiosis, such as sister chromatid segregation and homologous recombination. Genes expressed dynamically in granulosa cells were related to the TGF-β signaling pathway, response to gonadotropin, and development of primary female sexual characteristics. In addition, the dynamic genes expressed in granulosa cells might relate to the complex communication between different cell types. In summary, our study provided a transcriptome profile of common carp ovaries at single-nucleus resolution, and we further revealed the potential cell type-specific mechanisms underlying oogenesis and the differentiation of granulosa cells, which will facilitate breeding all-female common carp populations.

Temperature is a limiting factor in the growth of aquatic organisms and can directly affect many chemical and biological processes, including metabolic enzyme activity, aerobic respiration, and signal transduction. In this study, physiological, transcriptomic, and metabolomic analyses were performed to characterize the response of Litopenaeus vannamei to cold stress. We subjected L. vannamei to gradually decreasing temperatures (24 °C, 20 °C, 18 °C, 14 °C, and 12 °C) and studied the changes in the hepatopancreas. The results showed that extreme cold stress (12 °C) caused structural damage to the hepatopancreas of L. vannamei. However, shrimp exhibited response mechanisms to enhance cold tolerance, through regulating changes in key genes and metabolites in amino acid, lipid metabolism, and carbohydrate metabolism, including (a) increased level of methylation in cells to enhance cold tolerance; (b) increased content of critical amino acids, such as proline, alanine, glutamic acid and taurine, to ameliorate energy metabolism, protect cells from cold-induced osmotic imbalance, and promote ion transport and DNA repair; (c) accumulation of unsaturated fatty acids to improve cell membrane fluidity; and (d) regulation of the metabolic pattern shift to rely on anaerobic metabolism with a gradual decrease in aerobic metabolism and enhance glycolysis to produce enough ATP to maintain energy metabolic balance. When the temperature dropped further, cold stress impaired antioxidant and immune defense responses in shrimp. This study provides an integrated analysis of the physiology, transcriptome, and metabolome of L. vannamei in response to cold stress.

In this work, a new composite photocatalyst was synthesized by flower-like Bi2O3 and two-dimensional multilayer V2C using a facile hydrothermal method. Compared with the pristine sample, the specific surface area of Bi2O3/V2C MXene composite is significantly increased, which is favourable to improve the photocatalytic efficiency. The analysis of the UV-vis absorption spectrum and band gap energy shows that the construction of heterojunction broadens the light response range, improves the light absorption capacity, and obtains a narrower band gap than any of the single component, which is beneficial to the utilization of light. PL, TPC and EIS analysis revealed that Bi2O3/V2C MXene composite had stronger carrier mobility, which further confirmed that the photocatalytic oxidation performance of the system was the dominant reason in the photocatalytic NO pollutant removal process. This study provides a new idea for better understanding the two-dimensional MXene material-based photocatalyst and improving the NO removal efficiency.

Bi2MoO6 was synthesized on fibrous CuO/CF via a hydrothermal method, and its performance was subsequently evaluated. To ensure stable adhesion, copper foam (CF) was employed as the conductive substrate. The synthesized Bi2MoO6@CuO/CF composite demonstrates significantly enhanced light absorption capabilities. Electrochemical tests indicate that the composite exhibits a synergistic effect between enhanced visible light absorption and improved electrochemical reaction by specific charge transfer pathways, leading to increased activity in the nitrogen reduction reaction (NRR). The experimental data reveal that the nitrogen fixing efficiency and Faradaic efficiency of the Bi2MoO6@CuO/CF composite are 48.61 mu gcm(-2)h(-1) and 10.5 %, respectively. Compared to CuO/CF, the nitrogen fixation performance of the composite is 1.78 times higher, and its Faradaic efficiency is improved by 2.05 times. Ultimately, this novel composite photocatalyst, with its robust nitrogen fixation and light absorption capacities, represents a promising alternative to the current energy-intensive nitrogen fixation processes.

Temperature is an important factor in the physiological processes of aquatic organisms and can seriously affect several chemical and biological processes in their bodies, including respiratory metabolism, antioxidant capacity, immune capacity, and signal transduction. In this study, physiological, transcriptomic, and metabolomic analyses were used to investigate the response of Penaeus vannamei to cold stress. The results indicated that cold stress disrupted nucleotide metabolism and inhibited gluconeogenesis. However, shrimp exhibited response mechanisms in order to enhance cold tolerance, regulating changes in key genes and metabolites in amino acid and lipid metabolism to increase energy supply and protect cell membrane stability. In addition, the response included regulating Ca2+ pumps and ion channels to maintain intracellular ion homeostasis and osmotic balance. When the temperature dropped further, oxidative damage occurred due to overwhelming of the antioxidant defense system, and immune function was inhibited. This research provides some references regarding the molecular mechanisms involved in responding to cold stress and potential strategies to improve cold tolerance in P. vannamei; these are important references for studying the cold stress response of shrimp.

The rainbow trout (Oncorhynchus mykiss) is an important commercial fish. Studies have shown that probiotics can promote the healthy growth of fish. In this study, we assessed the impact of an endogenous Bacillus subtilis strain (RT-BS07) on the growth, survival and immunological response of juvenile rainbow trout. Additionally, the morphology of rainbow trout’s intestinal tissue was measured. Control (CT) and experimental groups (B) were fed with conventional and probiotic-supplemented diets (1.0 × 108 CFU per gram) for 42 days, respectively. Following feeding, a challenge experiment was carried out with Aeromonas hydrophila at 1.0 × 107 CFU/mL to determine the experimental fish’s tolerance to the bacteria. The results showed that the weight gain rate (WGR) in group B was 118.2%, which was significantly higher than that in group CT (54.86%) after 42 days. The height of intestinal villi and the number of goblet cells increased in group B, thus increasing the resistance of rainbow trout to pathogenic bacteria. The alkaline phosphatase (AKP) activity (U/mg prot) in the liver, spleen and intestinal tissues of group B was significantly higher than that in the CT group. The expression of interleukin-1β (IL-1β) in the intestinal tissue of group B was 6-fold higher than that in group CT. Furthermore, the expression of growth hormone-2 (GH-2) in the spleen was 3-fold higher than that in group CT. After 12 days of A. hydrophila injection, the survival rate was 40% and 70% in group CT and group B, respectively. Collectively, the present study demonstrated that the addition of endogenous B. subtilis strain (1.0 × 108 CFU per gram) to the feed can effectively promote the growth of rainbow trout and enhance immunity, which is beneficial to rainbow trout culture.

In this work, a novel SnS2@MoO3 composite catalyst was designed as the photocathode for PEC to catalytic conversion of nitrogen into ammonia under ambient conditions for the first time. The composite catalyst shows high yield, high stability and high product selectivity by taking advantage of not only photocatalysis but also electrocatalysis mechanism. The best nitrogen fixation performance was 30.04 & mu;g h-1 mg-1 (-0.7 V) and the best Faraday efficiency was 13.41% (-0.6 V) at room temperature and atmospheric pressure. Compared to pure MoO3 and SnS2, the nitrogen fixation performance is improved by 2.3 times and 4.6 times, and the Faraday efficiency is enhanced by 2.0 times and 3.5 times, respectively. The double layer capacitance of the heterojunction is 1.5 times that of SnS2 and 1.7 times that of MoO3 according to linear analysis, indicating that the composite has a higher electrochemically active area than SnS2 and MoO3. It can be concluded that the photoelectric synergistic effect between SnS2 and MoO3 further promote electron transfer under the light and electric conditions and exhibit higher nitrogen fixation catalytic performance. The strong stability in both photoelectric catalytic performance and crystal structures was also confirmed in the SnS2@MoO3 composite.

Simple and sensitive measurement of long non-coding RNA (lncRNA) is critical for early detection of malignancies. Herein, we demonstrate one-step self-assembly of quantum dot (QD)-based spherical nucleic acid (SNA) nanostructure for accurate monitoring of lncRNAs in living cells and tissues. When target lncRNA is present, it binds with a dumbbell probe to expose the complementary domain of Cy5-labeled primer, which subsequently induces cascade primer exchange reaction to produce abundant Cy5-labeled initiators. The Cy5-labeled initiators subsequently hybridize with hairpin probes on the QD surface to activate isothermal circular strand-displacement polymerization reaction, generating the QD-DNA-Cy5 nanostructures and inducing efficient Forster resonance energy transfer (FRET) between donor QD and acceptor Cy5. The obtained FRET signals are accurately quantified by single-molecule imaging. Notably, the single QD-based SNA nanostructure functions not only as a signal transmitter but also as a protector against non-specific amplification. Moreover, this assay utilizes only one DNA polymerase to achieve two-stage amplification, avoiding careful modulation of multiple enzymes. The self-assembly of QD nanosensor can be accomplished in single-step and single-tube manners at room temperature, eliminating precise temperature control and labor-intensive reaction protocols. This QD nanosensor achieves high sensitivity with a limit of detection (LOD) of 65.25 aM, and it is capable of quantifying lncRNA expression at single-cell level, differentiate tumor cells from normal cells, and distinguish breast cancer patients from healthy individuals, providing a versatile paradigm for biomedical research and early clinic diagnostics.

METTL3 and METTL14 are two components that form the core heterodimer of the main RNA m6A methyltransferase complex (MTC) that installs m6A. Surprisingly, depletion of METTL3 or METTL14 displayed distinct effects on stemness maintenance of mouse embryonic stem cell (mESC). While comparable global hypo-methylation in RNA m6A was observed in Mettl3 or Mettl14 knockout mESCs, respectively. Mettl14 knockout led to a globally decreased nascent RNA synthesis, whereas Mettl3 depletion resulted in transcription upregulation, suggesting that METTL14 might possess an m6A-independent role in gene regulation. We found that METTL14 colocalizes with the repressive H3K27me3 modification. Mechanistically, METTL14, but not METTL3, binds H3K27me3 and recruits KDM6B to induce H3K27me3 demethylation independent of METTL3. Depletion of METTL14 thus led to a global increase in H3K27me3 level along with a global gene suppression. The effects of METTL14 on regulation of H3K27me3 is essential for the transition from self-renewal to differentiation of mESCs. This work reveals a regulatory mechanism on heterochromatin by METTL14 in a manner distinct from METTL3 and independently of m6A, and critically impacts transcriptional regulation, stemness maintenance, and differentiation of mESCs.

Salinity is an important factor in the aquatic environment, and its fluctuations always result in osmotic stress, which affects the survival, distribution, and physiological activities of crustaceans. Crustaceans counter them through osmoregulation, which consists of many mechanisms. Palaemon gravieri is an important economic species in Palaemonidae, widely distributed in the southern East China Sea and the China Yellow Sea, and has a good adaptability to salinity stress. Currently, there are only a few studies on the effects of salinity on P. graviera. Therefore, it is particularly important to study the molecular responses of P. gravieri to salinity fluctuations. In this study, P. gravieri was treated with salinities of 10, 25, and 40, and the hepatopancreas and gills of shrimp in the different salinity groups were sampled after 24 h. The samples were used for RNA extraction and transcriptome analysis. In total, 80,994 unigenes were obtained, of which 19,114 were annotated. The differences in gene expression between different tissues at the same salinity were more significant. Many metabolism-related genes were downregulated in the gills, such as beta-hexosaminidase subunit alpha (HEXA), 10-formyltetrahydrofolate dehydrogenase (ALDH1L1), and Alcohol dehydrogenase class-3 (ADH5). Scanning transmission electron microscope analysis showed that the expression levels of some stress-(but not salinity stress) related genes changed after stress (mostly upregulated), suggesting the existence of secondary stress. Gene set enrichment analysis (GSEA) focused on the expression of transporters in osmoregulation, and the results showed that they mainly played a role in the gills, but ATP-binding cassette (ABC) transporters were more active in the hepatopancreas. This study showed that the response of P. gravieri to salinity change was different not only between the hepatopancreas and gills, but also between low salinity and higher salinity, and the ion transport-related genes were mainly expressed in the gills. Overall, these results improve our understanding of salt tolerance mechanism in P. gravieri.

The mitochondrial genome of Liriodendron tulipifera exhibits many ancestral angiosperm features and a remarkably slow evolutionary rate, while mitochondrial genomes of other magnoliids remain yet to be characterized. We assembled nine new mitochondrial genomes, representing all genera of perianth-bearing Piperales, as well as for a member of the sister clade: three complete or nearly complete mitochondrial genomes from Aristolochiaceae and six additional draft assemblies including Thottea, Asaraceae, Lactoridaceae, and Hydnoraceae. For comparative purpose, a complete mitochondrial genome was assembled for Saururus, a member of the perianth-less Piperales. The average number of short repeats (50-99 bp) was much larger in genus Aristolochia than in other angiosperm mitochondrial genomes, and approximately 30% of repeats (<350 bp) were found to have the capacity to mediate recombination. We found mitochondrial genomes in perianth-bearing Piperales comprising conserved repertories of protein-coding genes and rRNAs but variable copy numbers of tRNA genes. We identified several shifts from cis- to trans-splicing of the Group II introns of nad1i728, cox2i373, and nad7i209. Two short regions of the cox1 and atp8 genes were likely derived from independent horizontal gene transfer events in perianth-bearing Piperales. We found biased enrichment of specific substitution types in different lineages of magnoliids and the Aristolochiaceae family showed the highest ratio of A:T > T:A substitutions of all other investigated angiosperm groups. Our study reports the first mitochondrial genomes for Piperales and uses this new information for a better understanding of the evolutionary patterns of magnoliids and angiosperms in general.