During the terrestrialization of plants c. 470 Ma, overcoming nitrogen limitation was a major evolutionary challenge. While nonvascular plants may acquire nitrogen through rhizoids and surface diffusion, symbiotic interactions likely provide an important strategy to overcome nitrogen limitation. This study reveals that the amphibious liverwort Ricciocarpos natans (an extant bryophyte lineage) undergoes nitrogen-driven organogenesis. Under nitrogen-limiting conditions, the plant reprograms its development to form specialized scales, creating symbiotic niches. The formation of these symbiotic scales is activated by a nitrogen-sensing mechanism that suppresses the abscisic acid (ABA) and auxin signaling pathways. This hormonal reprogramming promotes an aquatic morphology with robust scales while suppressing the terrestrial form. These specialized scales likely support colonization by nitrogen-fixing bacteria, exemplified here using the model diazotroph Rhodopseudomonas palustris, demonstrating the capacity of ventral scales to function as symbiotic niches that enhance host nitrogen acquisition. This discovery identifies a nitrogen-responsive, scale-associated symbiotic strategy in Ricciocarpos natans (Marchantiales), providing comparative insight into how nonvascular plants adapt to nitrogen limitation and offering mechanistic clues regarding microbial recruitment pathways in plant-microbe interactions.

Mammalian torpor imposes unique metabolic constraints, yet the mechanisms of nitrogen metabolism during this state remain unclear. In this study, we show that the urea cycle is selectively regulated rather than broadly suppressed in torpid bats. A significantly increased abundance of carbamoyl-phosphate synthase 1 (CPS1) maintained its functional capacity during torpor and arousal in Myotis ricketti. Proteomic analyses and confocal microscopy identified a specific association and co-localization between CPS1 and agmatinase (AGMAT), an ATP-independent enzyme involved in nitrogen metabolism. Co-localization of CPS1 and AGMAT was also observed in torpid Rhinolophus ferrumequinum, a phylogenetically distant species. Fluorescence resonance energy transfer (FRET) further supported an indirect CPS1-AGMAT interaction. Most urea cycle enzymes exhibited stable or only moderately reduced expression during bat torpor, and metabolic profiling demonstrated sustained nitrogen flux. Together, these findings reveal a conserved adaptive mechanism that maintains urea cycle function, potentially enhancing osmotic stability and energy efficiency during prolonged fasting and water scarcity.

Frequent and extreme drought exerts profound effects on vegetation growth and production worldwide. It is imperative to identify key genes that regulate plant drought resistance and to investigate their underlying mechanisms of action. Long-chain fatty acids and their derivatives have been demonstrated to participate in various stages of plant growth and stress resistance; however, the effects of medium-chain fatty acids on related functions have not been thoroughly studied. Here, we integrate lipidomic, transcriptomic, and genetic analyses to elucidate the roles of the medium-chain acyl-acyl carrier protein thioesterase of Umellularia californica FatB (UcFatB) in drought tolerance and plant growth. Arabidopsis and tomato transgenic lines overexpressing UcFatB showed that the medium chain fatty acids mainly affect the male reproductive process of plant development. Transcriptomic and non-targeted lipid metabolomic combination analysis revealed significant changes in lauric acid-related metabolic pathways, as evidenced by increased phosphatidylcholine accumulation and upregulated stress-response gene expression. Consistent with the thicker waxy cutin layer and increased membrane integrity, UcFatB-overexpression enhanced drought tolerance in both Arabidopsis and tomato. Furthermore, methyl laurate and phosphatidylcholine application improved tomato drought resistance and fruit yield. These findings provide new insights into the potential genetic resources and cost-effective chemicals for enhancing drought resistance in crops.

Cortical granules are minute, normally extrusive organelles with multiple forms and functions, found beneath the pellicle of various ciliates, which have long been acknowledged as taxonomically relevant features, especially for the Hypotricha. However, proper assessment of their relevance to systematics is still limited by the scarcity of ultrastructural data allowing for fine-tuning homology recognition among the different kinds of granules. In this study, the morphology of cortical granules from five hypotrichous ciliates was examined using electron microscopy for the first time, revealing them to be extrusomes of different types. The results suggest the widespread presence of extrusomes among hypotrichs and explain their biogenesis after electron microscopy observations. Concurrently, phylogenetic analyses were performed using the Small Subunit Ribosomal RNA (SSU rRNA) gene to map the distribution of these organelles onto different taxa and discuss their evolution within the Dorsomarginalia and Kentrurostylida. Our findings indicate that pigmentocysts appear at various phylogenetic positions and emerged relatively late, exemplifying convergent evolution, and that similarities among extrusome types are relevant for delineating natural groups. Based on our results, new insights to hypotrichs systematics are proposed based on cortical granules: (i) the morphology and distribution patterns of the granules are now used to delineate major clades of the order Kentrurostylida, shedding light on the non-monophyly of the genera Anteholosticha, Bakuella, and Neobakuella; (ii) the redefinition of Pseudokeronopsidae, Pseudourostylidae, and Thigmokeronopsinae; and (iii) the recognition of pigmentocysts as a diagnostic feature and possible synapomorphy of the sister-clade of Stylonychinae, within Dorsomarginalia.

Bioremediation of cadmium (Cd) pollution, a recognized low-carbon green environmental protection technology, is significantly enhanced by the discovery of Cd-tolerant microorganisms and their underlying tolerance mechanisms. This study presents Colpoda sp., a soil ciliate with widespread distribution, as a novel bioindicator and bioremediator for Cd contamination. With a 24h-LC50 of 5.39mgl-1 and an IC50 of 24.85μgl-1 in Cd-contaminated water, Colpoda sp. achieves a maximum bioaccumulation factor (BAF) of 3.58 and a Cd removal rate of 32.98±0.74% within 96h. The toxic responses of Colpoda sp. to Cd stress were assessed through cytological observation with transmission electron microscopy (TEM), oxidative stress kinase activity, and analysis of Cd-metallothionein (Cd-MTs) and the cd-mt gene via qRT-PCR. The integrated biomarker response index version 2 (IBRv2) and structural equation models (SEM) were utilized to analyze key factors and mechanisms, revealing that the up-regulation of Cd-MTs and cd-mt expression, rather than the oxidative stress system, is the primary determinant of Cd accumulation and tolerance in Colpoda sp. The ciliate's ability to maintain growth under 24.85μgl-1 Cd stress and its capacity to absorb and accumulate Cd particles from water into cells are pivotal for bioremediation. A new mathematical formula and regression equations based on Colpoda sp.'s response parameters have been established to evaluate environmental Cd removal levels and design remediation schemes for contaminated sites. These findings provide a novel bioremediation and monitoring pathway for Cd remobilization and accumulation in soil and water, potentially revolutionizing the governance of Cd pollution.

Peat moss (Sphagnum) is a non-vascular higher plant with unique xylem-like hyaline (H) cells that are accompanied by photosynthetic chlorophyllous cells. These cellular structures play crucial roles in water storage and carbon sequestration. However, it is largely unknown how peat moss develops the H cells. This study systematically explored the Sphagnum Developmental Cell Atlas and Lineage and classified leaf cell development into two lineages with six stages (S0-S5) based on changes in key cellular traits, including the formation of spiral secondary cell walls (S4) and the presence of water pores (S5). Cell lineage-specific subcellular remodeling was transcriptionally regulated during leaf development, and vacuole-mediated clearance of organelles and cell death led to mature dead H cells. Interestingly, expression of land plant conserved Vascular-related NAC Domain (VND) genes correlated with H cell formation. Overall, these results suggest that the origination of xylem-like H cells is related to VND, likely through the neofunctionalization of vacuole-mediated cell death to attempt xylem formation in peat moss, suggesting potential uncoupling of xylem and phloem cell origins. This study positions peat moss as a potential model organism for studying integrative evolutionary cell biology.

Frontoniidae, the largest family of the order Peniculida, is non-monophyletic with its members dispersed among other families in phylogenetic trees, which complicated the unsolved inner relationship of the order. In this study, we conducted phylogenetic analyses using 34 newly obtained nuclear sequences and 29 COI sequences from the families Frontoniidae and Stokesiidae. Additionally, the nematodesmata of Frontoniidae species were described using light and electron microscopy. Our findings revealed that Frontonia depressa represents a distinct lineage within the order Peniculida, leading to the establishment of a new genus, Protofrontonia, based on the distinctive morphology of F. depressa as a diagnostic feature. The finer differentiation of nematodesmata and cysts were adopted as novel characters for evolutionary discussion of the major Peniculida lineages. We propose that the strengthened nematodesmata, enabling the ability to feed on larger food, represents a derived feature of the ‘true’ Frontoniidae lineage, while a cyst with a papula may serve as a common derived feature of Stokesiidae and its Frontoniidae affinity. It is suggested that divergent evolution may have also occurred in the lineages retaining Frontoniidae plesiomorphies, albeit not reflected in the traditional taxonomic features.

The single-celled eukaryote Euplotes aediculatus was chosen to test and compare the toxic effects of Cu and CuO nanoparticles (NPs). The antioxidant enzymatic activity, morphological changes, and functional groups on the membrane were determined using spectrophotometry, microscopy, and Fourier transform infrared spectroscopy after NPs treatment. The toxicity of the NPs to cells was dose-dependent, and the 24 h-LC50 values of the CuNPs and CuONPs were 0.46 µg/L and 1.24 × 103 µg/L, respectively. These NPs increased the activities of superoxide dismutase, glutathione peroxidase, and catalase and destroyed the cell structure; moreover, the CuNPs were more toxic than the CuONPs. In addition to the higher enzymatic activity, CuNPs also caused nucleoli disappearance, chromatin condensation, and mitochondrial and pellicle damage. The oxidization of the functional groups of the membrane (PO2 − , C–O–C, and δ(COH) of carbohydrates) also confirmed the severe damage caused by CuNPs. Our study showed that oxidative stress and organelle destruction played important roles in the toxic effects of these NPs on this protozoan. Compared with other aquatic organisms, E. aediculatus can be considered a potential indicator at the preliminary stage of environmental pollution.

纤毛虫原生动物在环境恶劣的条件下可形成包囊,待环境转好时又脱包囊变为营养体.目前,对不同纤毛虫细胞去分化规律的比较研究仍不足.本文利用扫描电镜和透射电镜对腹毛亚纲三伪尖毛虫(Oxytricha trifallax)形成包囊过程进行了观察,结果发现:纤毛器去分化起始于口纤毛器,波动膜先于口围带去分化,腹面体纤毛器则从缘棘毛开始去分化;背触毛在该过程中则发生再分化,裸毛基体长出纤毛杆;相比营养期,包囊期出现较多 自噬泡且线粒体发生降解.比较不同腹毛亚纲纤毛虫成包囊过程中细胞分化特征发现,细胞是否发生扭转、背触毛是否再分化存在差异,这或能在一定程度上为腹毛类纤毛虫阶元间界定提供不同于经典分类特征的参考.

高压冷冻及冷冻替代技术是一种利用高压和低温对含水组织样品进行瞬间冷冻固定和低温脱水的电镜样品制备技术,它因可以保存更加真实的细胞超微结构而常应用于透射电镜观察和分析.本文利用模式动物小鼠为材料,将这种技术应用于体扫描电镜的样品制备,并与常规化学固定的样品制备进行比较.结果显示在小鼠心肌组织中,高压冷冻及冷冻替代技术可以有效避免常规制备样品中的细胞器膜结构皱缩、细胞质分布不均匀、细胞核膜收缩形成锯齿状、甚至局部断裂等现象,使细胞超微结构更接近其生活时的状态.

New organelle acquisition through neofunctionalization of the endomembrane system (ES) with respect to plant secondary metabolism is a key evolutionary strategy for plant adaptation, which is overlooked due to the complexity of angiosperms. Bryophytes produce a broad range of plant secondary metabolites (PSMs), and their simple cellular structures, including unique organelles, such as oil bodies (OBs), highlight them as suitable model to investigate the contribution of the ES to PSMs. In this opinion, we review latest findings on the contribution of the ES to PSM biosynthesis, with a specific focus on OBs, and propose that the ES provides organelles and trafficking routes for PSM biosynthesis, transportation, and storage. Therefore, future research on ES-derived organelles and trafficking routes will provide essential knowledge for synthetic applications.

The Class Nassophorea is not monophyletic with unsolved relationship of four orders, which calls for discussion to combine morphological features and molecular phylogeny. In the present study, the ultrastructure of Apocolpodidium etoschense in the order Colpodidiida is first studied. Comparisons between orders of Nassophorea were conducted and a discussion of systematics was performed based on a SSU rRNA gene-based phylogeny. The order Colpodidiida and Nassulida shared the following features: Two pairs of alveolocysts in the cortex, the presence of a ''B-cartwheel'' in the distal region of the kinetosome, the presence of cytostomal lamellae and subcytostomal lamellae in the cytopharyngeal basket, and spindle trichocysts with a simple tip. These similarities shape a core group of Nassophorea, which are morphologically and genetically different from the order Microthoracida. Consequently, Microthoracida should be regarded as an independent taxon rather than a member of Nassophorea. Within the core group of Nassophorea, Colpodidiida as an independent order is further validated by its delicate cytopharyngeal basket which lacks nematodesmal lamellae; while the non-monophyly of the order Nassulida might be explained by differentiation of the cartwheels in kinetosomes and the arrangement of kinetosomes with postciliary microtubules in the nassulid organelle 3 within its members.

Physiologically relevant electrical microenvironments play an indispensable role in manipulating bone metabolism. Although implanted biomaterials that simulate the electrical properties of natural tissues using conductive or piezoelectric materials have been introduced in the field of bone regeneration, the application of electret materials to provide stable and persistent electrical stimulation has rarely been studied in biomaterial design. In this study, a silicon dioxide electret-incorporated poly(dimethylsiloxane) (SiO2/PDMS) composite electroactive membrane was designed and fabricated to explore its bone regeneration efficacy. SiO2 electrets were homogeneously dispersed in the PDMS matrix, and sandwich-like composite membranes were fabricated using a facile layer-by-layer blade-coating method. Following the encapsulation, electret polarization was conducted to obtain the electreted composite membranes. The surface potential of the composite membrane could be adjusted to a bone-promotive biopotential by tuning the electret concentration, and the prepared membranes exhibited favorable electrical stability during an observation period of up to 42 days. In vitro biological experiments indicated that the electreted SiO2/PDMS membrane promoted cellular activity and osteogenic differentiation of mesenchymal stem cells. In vivo, the electreted composite membrane remarkably facilitated bone regeneration through persistent endogenous electrical stimulation. These findings suggest that the electreted sandwich-like membranes, which maintain a stable and physiological electrical microenvironment, are promising candidates for enhancing bone regeneration.

Although many reports have demonstrated that nanoparticles can have a negative effect on aquatic organisms, the toxic effects on symbiotic organisms remain poorly understood. The present study conducts ultrastructure, enzyme activity, and transcriptomics to assess the toxic effects to the Paramecium bursaria-Chlorella symbiotic system from exposure to copper nanoparticles (CuNPs) for 24 h. We found that in both the host and symbiotic algae, CuNP exposure induced high reactive oxygen species level, which leads to oxidative damage and energy metabolism disorder. Moreover, transmission electron micrographs (TEMs) showed that the symbiotic algae in the cytoplasm of P. bursaria were enveloped in the digestive vacuole and digested, and the level of acid phosphatase activity increased significantly within 24 h, which indicated that the stability of the symbiotic system was affected after CuNP exposure. We speculated that the increased energy demand in the host and symbiotic algae resulted from oxidative stress, precipitating the decrease of the photosynthetic products provided to the host, the digestion of the symbiont, and the destruction of the stable symbiotic relationship. The study provides the first insight into the mechanisms of nanoparticles' toxicity to the symbiotic relationship in the ecosystem, which may help to understand the environmental effects and toxicological mechanisms of nanoparticles.

为探究纳米材料进入水环境后对水生生物的影响,本文利用扫描及透射电子显微镜观察了纳米银和纳米铜对纤毛虫绿草履虫(Paramecium bursaria)细胞超微结构的损伤情况.结果表明:(1)两种纳米材料对细胞结构的损伤方式具有一定的相似性,损伤主要表现在绿草履虫细胞的表膜、线粒体以及细胞核等结构,且损伤程度随时间增加逐渐加重.(2)纳米铜对细胞超微结构造成的损伤程度比纳米银严重.实验结果表明,两种纳米材料均对纤毛虫具有生物毒性,推测其通过氧化应激导致细胞表面及内部结构损伤.

纳米氧化锌(ZnONPs)被广泛应用于医药材料等领域,但不适当的排放会给水生生态环境带来安全隐患.本研究用ZnO NPs对单细胞真核生物绿草履虫(Paramecium bursaria)的急性和慢性毒理进行测试,结合电镜技术、荧光技术以及酶活力测定、DHE荧光探针技术对ZnO NPs的致毒机制进行探索.结果显示ZnO NPs对绿草履虫的24h-LC50和24h-EC50分别为0.39 mg/L和0.04 mg/L,与其他受试动物相比较为敏感.超微结构显示ZnO NPs可对绿草履虫细胞表膜、刺丝泡、线粒体和细胞核等结构造成损伤.酶活力和荧光探针等结果推测ZnO NPs可能是通过诱导活性氧的积累使绿草履虫遭受氧化胁迫继而死亡.另外,ZnO NPs的解离度与锌离子的毒性测定结果表明锌离子是ZnO NPs导致绿草履虫死亡的主要因素,因此通过改性以抑制ZnO NPs的溶解度可以提高纳米材料使用的安全性.

Ciliated protozoans form dormant cysts for survival under adverse conditions. The molecular mechanisms regulating this process are critical for understanding how single-celled eukaryotes adapt to the environment. Despite the accumulated data on morphology and gene coding sequences, the molecular mechanism by which lncRNAs regulate ciliate encystment remains unknown. Here, we first detected and analyzed the lncRNA expression profile and coexpressed mRNAs in dormant cysts versus vegetative cells in the hypotrich ciliate Pseudourostyla cristata by high-throughput sequencing and qRT-PCR. A total of 853 differentially expressed lncRNAs were identified. Compared to vegetative cells, 439 and 414 lncRNAs were upregulated and downregulated, respectively, while 47 lncRNAs were specifically expressed in dormant cysts. A lncRNA-mRNA coexpression network was constructed, and the possible roles of lncRNAs were screened. Three of the identified lncRNAs, DN12058, DN20924 and DN30855, were found to play roles in fostering encystment via their coexpressed mRNAs. These lncRNAs can regulate a variety of physiological activities that are essential for encystment, including autophagy, protein degradation, the intracellular calcium concentration, microtubule-associated dynein and microtubule interactions, and cell proliferation inhibition. These findings provide the first insight into the potentially functional lncRNAs and their coexpressed mRNAs involved in the dormancy of ciliated protozoa and contribute new evidence for understanding the molecular mechanisms regulating encystment.

The development of heterogeneous acid catalysts with higher activity than homogeneous acid catalysts is critical and still challenging. In this study, acidic poly(ionic liquid)s with swelling ability (SAPILs) were designed and synthesized via the free radical copolymerization of ionic liquid monomers, sodium p-styrenesulfonate, and crosslinkers, followed by acidification. The 31P nuclear magnetic resonance chemical shifts of adsorbed trimethylphosphine oxide indicated that the synthesized SAPILs presented moderate and single acid strength. The thermogravimetric analysis results in the temperature range of 300–345 °C revealed that the synthesized SAPILs were more stable than the commercial resin Amberlite IR-120(H) (245 °C). Cryogenic scanning electron microscopy testing demonstrated that SAPILs presented unique three-dimensional (3D) honeycomb structure in water, which was ascribed to the swelling-induced self-assembly of the molecules. Moreover, we used SAPILs with micron-sized honeycomb structure in water as catalysts for the hydrolysis of cyclohexyl acetate to cyclohexanol, and determined that their catalytic activity was much higher than that of homogeneous acid catalysts. The equilibrium concentrations of all reaction components inside and outside the synthesized SAPILs were quantitatively analyzed using a series of simulated reaction mixtures. Depending on the reaction mixture, the concentration of cyclohexyl acetate inside SAPIL-1 was 7.5–23.3 times higher than that outside of it, which suggested the high enrichment ability of SAPILs for cyclohexyl acetate. The excellent catalytic performance of SAPILs was attributed to their 3D honeycomb structure in water and high enrichment ability for cyclohexyl acetate, which opened up new avenues for designing highly efficient heterogeneous acid catalysts that could eventually replace conventional homogeneous acid catalysts.

MicroRNAs (miRNAs) regulate the expression of target genes in diverse cellular processes and play important roles in different physiological processes. However, little is known about the microRNAome (miRNAome) during encystment of ciliated protozoa. In the current study, we first investigated the differentially expressed miRNAs and relative signaling pathways participating in the transformation of vegetative cells into dormant cysts of Pseudourostyla cristata (P. cristata). A total of 1608 known miRNAs were found in the two libraries. There were 165 miRNAs with 1217 target miRNAs. The total number of differential miRNAs screened between vegetative cells and dormant cysts databases were 449 with p < 0.05 and |log2 fold changes| > 1. Among them, the upregulated and downregulated miRNAs were 243 and 206, respectively. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that some of the differentially expressed miRNAs were mainly associated with oxidative phosphorylation, two-component system, and biosynthesis of amino acids. Combining with our bioinformatics analyzes, some differentially expressed miRNAs including miR-143, miR-23b-3p, miR-28, and miR-744-5p participates in the encystment of P. cristata. Based on these findings, we propose a hypothetical signaling network of miRNAs regulating or promoting P. cristata encystment. This study shed new lights on the regulatory mechanisms of miRNAs in encystment of ciliated protozoa.

The guided bone regeneration (GBR) concept has been extensively utilized to treat maxillofacial bone defects in clinical practice. However, the repair efficacy of currently available GBR membranes is often compromised by their limited bone regeneration potential and deficient antibacterial activity. In this study, inspired by the bi-layered structure design of the commonly used Bio-GideⓇmembrane, we designed and fabricated a new kind of multifunctional bi-layered "GBR scaffold" combining solution electrospinning writing (SEW) and solution electrospinning (SES) techniques using a single SEW printer. Copper-loaded mesoporous silica nanoparticles (Cu@MSNs) were incorporated into the poly(lactic-co-glycolic acid)/gelatin (PLGA/Gel, denoted as PG) fiber matrix to construct a composite PG-Cu@MSNs fibrous scaffold. The obtained GBR scaffold consisted of a loose and porous SEW layer to support and facilitate bone ingrowth, and a dense and compact SES layer to resist non-osteoblast interference. The resulting enhanced mechanical properties, coordinated degradation profile, and facile preparation procedure imparted the composite scaffold with good clinical feasibility. In vitro biological experiments indicate that the PG-Cu@MSNs composite scaffold exhibited favorable osteogenic and antibacterial properties. Furthermore, an in vivo rat periodontal defect model further confirmed the promising bone regeneration efficacy of the PG-Cu@MSNs scaffold. In conclusion, the developed electrowritten Cu@MSNs-incorporated bi-layered scaffold with hierarchical architecture and concurrent osteogenic and antibacterial functions may hold great potential for application in GBR.