Secondary lignification of the root exodermis of Kandelia obovata is crucial for its response to adversity such as high salinity and anaerobic environment, and this lignification is also effective in blocking cadmium transport to the roots. However, how the differences in lignification of root exodermis at different developmental stages respond to Cd stress and its regulatory mechanisms have not been revealed. In this study, after analyzing the root structure and cell wall thickness using a Phenom scanning electron microscope as well as measuring cadmium content in the root cell wall, we found that the exodermis of young and mature roots of K. obovata responded to Cd stress through the polymerization of different lignin monomers, forming two different mechanisms: chelation and blocking. Through small RNA sequencing, RLM-5 '-RACE and dual luciferase transient expression system, we found that miR397 targets and regulates KoLAC4/17/7 expression. The expression of KoLAC4/17 promoted the accumulation of guaiacyl lignin during lignification and enhanced the binding of cadmium to the cell wall. Meanwhile, KoLAC7 expression promotes the accumulation of syringyl lignin during lignification, which enhances the obstruction of cadmium and improves the tolerance to cadmium. These findings enhance our understanding of the molecular mechanisms underlying the differential lignification of the root exodermis of K. obovata in response to cadmium stress, and provide scientific guidance for the conservation of mangrove forests under heavy metal pollution.

Species of the Karenia genus are widely distributed in global waters and frequently cause harmful algal blooms (HABs), posing significant threats to coastal ecosystems, aquaculture, and human safety. Among them, Karenia brevis is one of the most extensively studied species due to its production of brevetoxins, which are highly toxic to marine life and can adversely impact public health. In this study, we developed a rapid detection method that combines Recombinase-aided amplification (RAA) with CRISPR/LbCas12a, aimed at the precise identification of K. brevis. Specific RAA primers and crRNAs were designed based on the highly variable regions of the internal transcribed spacer (ITS) sequence of K. brevis. After screening multiple RAA primer pairs and crRNAs, the optimal combination was identified, ensuring both high efficiency and specificity of the detection system. For field application, two detection modes were employed: fluorescence-based (FQ) and lateral flow dipstick (LFD), along with a simple and rapid DNA extraction method. Sensitivity tests demonstrated that the detection limit of this method was 5.9 × 10³ copies/µL for plasmid DNA and 1 cell/mL for live cells. Environmental water samples collected during a HAB event in Lianjiang, Fujian Province, in May 2024, tested negative for K. brevis using the RAA-CRISPR/LbCas12a system. However, two other Karenia species—Karenia mikimotoi and Karenia longicanalis—were identified through ITS fragment amplification, cloning sequencing and phylogenetic analysis. In spiked experiments where K. brevis was introduced into natural water samples, the RAA-CRISPR/LbCas12a system accurately detected its presence. Overall, the RAA-CRISPR/LbCas12a detection system demonstrated excellent sensitivity, specificity and operational simplicity, making it a promising tool for rapid field detection of K. brevis and potentially suitable for broader applications in HAB monitoring.

Harmful algal blooms (HABs), mainly formed by dinoflagellates, have detrimental effects on marine ecosystems and public health. Therefore, detecting HABs is crucial for early warning and prevention of HABs as well as the mitigation of their adverse effects. Although various methods, such as light microscopy, electron microscopy, real-time PCR, and microarrays, have already been established for the detection of HABs, they are still cumbersome to be exploited in the field. Therefore, rapid nucleic detection methods such as recombinase polymerase amplification (RPA) and loop-mediated isothermal amplification (LAMP)-lateral flow dipstick (LFD) have been developed for monitoring bloom-forming algae. However, the CRISPR/Cas-based detection of HABs has yet to be applied to this field. In this study, we developed a method for detecting Karenia mikimotoi (K. mikimotoi), a typical ichthyotoxic dinoflagellate responsible for global blooms. Our method utilized Cas12a from Lachnospiraceae bacterium ND2006 (LbCas12a) to target and cleave the internal transcribed spacer (ITS) of K. mikimotoi, guided by RNA. We leveraged the target-activated non-specific single-stranded deoxyribonuclease cleavage activity of LbCas12a to generate signals that can be detected using fluorescence-read machines or LFDs. By combining RPA and LbCas12a with reporters, we significantly enhanced the sensitivity, enabling the detection of ITS-harboring plasmids at concentrations as low as 9.8 aM and genomic DNA of K. mikimotoi at levels as low as 3.6 × 10−5 ng/μl. Moreover, we simplified the genomic DNA extraction method using cellulose filter paper (CFP) by directly eluting the DNA into RPA reactions, reducing the extraction time to < 30 s. The entire process, from genomic DNA extraction to result reporting, takes less than an hour, enabling the identification of nearly a single cell. In conclusion, our method provided an easy, specific, and sensitive approach for detecting K. mikimotoi, offering the potential for efficient monitoring and management of K. mikimotoi blooms.

As an important mangrove species, Kandelia obovata plays an irreplaceable role in the coastal ecosystem. However, due to a lack of genetic technology, there is limited research on its functional genes. As such, establishing an efficient and rapid functional verification system is particularly important. In this study,tobacco rattle virus (TRV) and the phytoene desaturase gene KoPDS were used as the vector and target gene, respectively, to establish a virus-induced gene silencing system (VIGS) in K. obovata. Besides, the system was also used to verify the role of a Chlorophyll a/b binding protein (Cab) gene KoCAB in leaf carbon sequestration of K. obovata. RNA-Seq and qRT-PCR showed that the highest gene-silencing efficiency could reach 90% after 10 days of inoculation and maintain above 80% after 15 days, which was achieved with resuspension buffer at pH 5.8 and Agrobacterium culture at OD600 of 0.4-0.6. Taken together, the TRV-mediated VIGS system established herein is the first genetic analysis tool for mangroves, which may greatly impel functional genomics studies in mangrove plants.

Histone acetylation modification significantly affects secondary metabolism in filamentous fungi. However, how histone acetylation regulates secondary metabolite synthesis in the lovastatin (a lipid-lowering drug) producing Aspergillus terreus remains unknown because protein is involved and has been identified in this species. Here, the fungal-specific histone deacetylase gene, hstD, was characterized through functional genomics in two marine-derived A. terreus strains, Mj106 and RA2905. The results showed that the ablation of HstD resulted in reduced mycelium growth, less conidiation, and decreased lovastatin biosynthesis but significantly increased terrein biosynthesis. However, unlike its homologs in yeast, HstD was not required for fungal responses to DNA damage agents, indicating that HstD likely plays a novel role in the DNA damage repair process in A. terreus. Furthermore, the loss of HstD resulted in a significant upregulation of H3K56 and H3K27 acetylation when compared to the wild type, suggesting that epigenetic functions of HstD, as a deacetylase, target H3K27 and H3K56. Additionally, a set of no-histone targets with potential roles in fungal growth, conidiation, and secondary metabolism were identified for the first time using acetylated proteomic analysis. In conclusion, we provide a comprehensive analysis of HstD for its targets in histone or non-histone and its roles in fungal growth and development, DNA damage response, and secondary metabolism in A. terreus.

In contrast to typical planktonic hydromedusae, Cladonema medusae are mostly benthic, with specialised adhesive branches to adhere to the substrate. In this study, a Cladonema species discovered in a laboratory aquarium in Fuzhou, China, was confirmed as a new species, based on morphological and molecular analyses. The species was named Cladonema multiramosum sp. nov. Its medusa is distinct from that of congeners possessing substantially more adhesive branches (8–24, rarely 5–7), and tiny branches on the upper radial canals. The validity of C. multiramosumum sp. nov. was also supported by molecular phylogenetic analyses based on the mitochondrial 16S rDNA sequence. However, C. multiramosum sp. nov. medusa also displayed considerable phenotypic plasticity with respect to its radial canals, tentacles, stinging branches per tentacle, oral tentacles, manubrium, and gonads, hindering species identification based solely on morphology. Although some morphological characteristics of hydroids (filiform tentacles and medusa buds) and nematocysts could also be used as diagnostic characters in the genus Cladonema, this information is unavailable for some Cladonema species. Thus, the taxonomy within the genus Cladonema was re-evaluated based mainly on the morphological characteristics of the medusa. Further revision of the genus Cladonema should be made when supplementary information on the life cycle and DNA barcoding are updated.

原生动物是水生食物网中主要的植食性生物,在自然水体中能够有效控制浮游植物的生物量,具有预防及延缓赤潮发生的潜在应用价值.在福建沿岸分离筛选出一种常见的原生动物—厚游仆虫(Euplotes crassus),通过研究其对三种常见有毒赤潮藻类的毒素耐受性、抑藻率及自身在赤潮压力下的生长速率,评测厚游仆虫对常见有毒赤潮藻类的抑制作用,挖掘其作为控藻生物的应用潜力.将厚游仆虫分别接种于不同浓度的剧毒卡尔藻(Karlodinium veneficum)、赤潮异弯藻(Heterosigma akashiwo)及米氏凯伦藻(Karenia mikimotoi)中,在温度20℃、光照度100μmol·M–2·s–1和光暗比12 h:12 h的条件下进行共培养.结果显示,厚游仆虫对剧毒卡尔藻和赤潮异弯藻具有明显的抑制作用,持续抑藻时间可达72 h以上,且未见藻细胞数量的明显反弹,而对于米氏凯伦藻则没有明显的抑制能力.说明厚游仆虫在一定条件下可作为一种有效可行的控藻生物,但其对赤潮藻类的抑制作用具有一定的种类特异性.结果证明,在赤潮形成初期厚游仆虫对赤潮藻类的摄食压力可能有助于抑制或延缓剧毒卡尔藻及赤潮异弯藻赤潮的发生与发展,其在赤潮治理中的实际应用还需结合野外水体做进一步研究.

Terrein, a major secondary metabolite from Aspergillus terreus, shows great potentials in biomedical and agricultural applications. However, the low fermentation yield of terrein in wild A. terreus strains limits its industrial applications. Here, we constructed a cell factory based on the marine-derived A. terreus RA2905, allowing for overproducing terrein by using starch as the sole carbon source. Firstly, the pathway-specific transcription factor TerR was over-expressed under the control of a constitutive gpdA promoter of A. nidulans, resulting in 5 to 16 folds up-regulation in terR transcripts compared to WT. As expected, the titer of terrein was improved in the two tested terR OE mutants when compared to WT. Secondly, the global regulator gene stuA, which was demonstrated to suppress the terrein synthesis in our analysis, was deleted, leading to greatly enhanced production of terrein. In addition, LS-MS/MS analysis showed that deletion of StuA cause decreased synthesis of the major byproduct butyrolactones. To achieve an optimal strain, we further refactored the genetic circuit by combining deletion of stuA and overexpression of terR, a higher terrein yield was achieved with a lower background of byproducts in double mutants. In addition, it was also found that loss of StuA (both ΔstuA and ΔstuA::OEterR) resulted in aconidial morphologies, but a slightly faster growth rate than that of WT. Our results demonstrated that refactoring both global and pathway-specific transcription factors (StuA and TerR) provides a high-efficient strategy to enhance terrein production, which could be adopted for large-scale production of terrein or other secondary metabolites in marine-derived filamentous fungi.

海葵白化是由于海葵失去体内共生的虫黄藻和(或)共生的虫黄藻失去体内色素而导致海葵变白的生态现象.为探究鬼手海葵(Aiptasia pulchella)白化和白化恢复后相关的分子机制,本研究对海葵进行慢性热胁迫处理,以白化海葵和白化恢复后的海葵为研究对象,采用2代IIlumina Hi-seq测序技术进行转录组测序,探究两者在基因表达水平方面的差异变化,分别获得50109686和43163786条Clean reads,注释后获得24565和24157个Unigene.比较转录组分析结果显示,白化海葵与白化恢复后的海葵之间存在214个差异表达基因,其中白化海葵的高表达基因有101个,白化恢复后海葵的高表达基因有113个,这些差异表达基因主要与DNA复制、新陈代谢、离子转运和胶原蛋白有关.对不同处理所涉及的全部28050个表达基因进行基因集富集分析(gene set enrichment analysis,GSEA),结果发现,白化海葵在胶原蛋白和离子转运方面显著富集表达,白化恢复后的海葵在核酸修复方面显著富集表达,推测这些生物学过程在海葵白化和白化后修复过程中发挥重要作用.本研究获得的转录组数据和研究结果初步揭示了海葵共生体系在共生失衡后进行适应性调节的分子机制,为海葵及珊瑚共生体系应对环境变化的适应性机制研究提供了理论依据.

Diverse microbial ecosystems underpin life in the sea. Among these microbes are many unicellular eukaryotes that span the diversity of the eukaryotic tree of life. However, genetic tractability has been limited to a few species, which do not represent eukaryotic diversity or environmentally relevant taxa. Here, we report on the development of genetic tools in a range of protists primarily from marine environments. We present evidence for foreign DNA delivery and expression in 13 species never before transformed and for advancement of tools for eight other species, as well as potential reasons for why transformation of yet another 17 species tested was not achieved. Our resource in genetic manipulation will provide insights into the ancestral eukaryotic lifeforms, general eukaryote cell biology, protein diversification and the evolution of cellular pathways.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.