Search Results (2,208)

Understanding the molecular basis of heat tolerance in microalgae is crucial for developing resilient strains for industrial biotechnology. This study identified two desert Chlorella strains, XDA024 (thermotolerant) and XDA121 (heat-sensitive), through short-term thermal screening. The thermotolerant strain XDA024 survived exposure to 50 °C for 3 h, whereas XDA121 succumbed within 1 h at 40 °C. Physiological analyses revealed that the superior heat resistance of XDA024 was associated with enhanced activities of key antioxidant enzymes, including superoxide dismutase, catalase, and peroxidase, which effectively mitigated oxidative damage, alongside an elevated proline content contributing to osmoregulation. Transcriptomic profiling under acute heat stress (45 °C, 3 h) revealed that the unique thermotolerance of XDA024 was underpinned by the upregulation of genes related to photosystem stability and lipid synthesis, processes supported by activated calcium signaling and antioxidant pathways. In contrast, XDA121 exhibited significant downregulation of photosynthesis-related genes and promoted lipid degradation, resulting in membrane instability. Exogenous application of phosphatidylethanolamine (PE) and monoethanolamine (MEA) markedly increased the survival rate of XDA121 by more than threefold, primarily by alleviating membrane damage through enhanced membrane integrity and modulated antioxidant enzyme activities. These findings indicate that thermotolerance in desert Chlorella (Chlorophyta) is governed by the integrated coordination of antioxidant defense mechanisms, lipid metabolism, and photosystem protection. This research provides crucial insights and practical strategies for engineering heat-resistant microalgal strains for sustainable biofuel and bioproduct production. Full article

Aspergillus flavus and its aflatoxins pose serious threats to human and animal health, negatively affecting agricultural productivity and the global economy. Although chemical preservatives are widely used, their effectiveness remains limited by increased fungal resistance and environmental concerns, highlighting the need for sustainable alternatives. Microbial volatile organic compounds (mVOCs) represent a promising biocontrol strategy. Here, we investigate how glutamine regulates mVOC biosynthesis in Streptomyces alboflavus TD-1 and enhances its antifungal activity against A. flavus. Antifungal assays showed that supplementation with 40 mM glutamine significantly enhanced inhibitory activity, leading to 69.0% inhibition of conidial germination and 64.5% inhibition of mycelial biomass. Transcriptome profiling identified 283 differentially expressed genes, including the two-component system regulator gluR, which was strongly upregulated. CRISPR/Cas9-mediated disruption of gluR confirmed its regulatory role. Specifically, the mutant strain produced reduced levels of antifungal mVOCs, such as dimethyl trisulfide and o-anisidine, and exhibited diminished inhibition of A. flavus. Collectively, these findings demonstrate that exogenous glutamine enhances the mVOC-mediated suppression of A. flavus by S. alboflavus TD-1 through nutrient-sensing and transcriptional regulation of volatile biosynthesis. Although aflatoxin levels were not quantified in this study, the enhanced growth inhibition and the identified mVOC shifts provide a mechanistic basis for future studies that directly quantify aflatoxin production under storage-relevant conditions. Full article

Discrimination of cancer cells from normal growing cells is crucial to specifically target cancer cells. The transcription factor E2F1 is the principal target of the tumor suppressor pRB. E2F1 activated by growth stimulation activates cell cycle-related genes and facilitates cell proliferation. E2F1 activated by loss of pRB control, such as forced inactivation of pRB, activates tumor suppressor genes such as ARF and TAp73 and induces apoptosis. We show here that these genes are specifically activated by exogenously expressed E2F1 or forced inactivation of pRB but not by growth stimulation in epithelial cells. This observation indicates that E2F1 activity induced by forced inactivation of pRB contains distinct E2F1 activity that activates these tumor suppressor genes. Cancer cells survive with concomitant dysfunction of apoptosis-inducing pathways, suggesting the presence of distinct E2F1 activity specifically in cancer cells. We determined the presence of distinct E2F1 activity using E2F responsive elements of the ARF and TAp73 genes by reporter assay. All 33 cancer cell lines tested possessed distinct E2F1 activity, but five normal growing cell lines did not. These results indicate that distinct E2F1 activity is a unique characteristic of cancer cells that facilitates discrimination from normal growing cells to specifically target cancer cells. Full article

This study aims to investigate the effects of dietary vitamin C supplementation on vitamin C synthesis, transport, and egg deposition in breeding geese. A total of 450 female and 90 male 221-day-old Yangzhou geese were randomly assigned to five treatment groups with six replicates each (15 females and 3 males per replicate). The control group received a basal diet, while the other four groups were fed diets supplemented with 100, 200, 300, and 400 mg/kg vitamin C over a 16-week feeding trial. The results showed that dietary vitamin C supplementation increased the vitamin C content in both serum and egg yolks and modulated the expression of key vitamin C-related genes. Specifically, the intestinal and ovarian sodium-dependent vitamin C transporters 1 and 2 (SVCT1/SVCT2) were upregulated, whereas hepatic and renal L-Gulonolactone oxidase (GLO) and SVCT1 were suppressed. These findings indicate that exogenous vitamin C enhances intestinal absorption, inhibits hepatic synthesis, and promotes yolk deposition, with 300 mg/kg emerging as an effective and practical supplementation level that provides a physiological basis for its application in poultry nutrition. Full article

When kept at a low temperature, yellow melons are prone to chilling injury. It is widely known that applying putrescine (Put) after harvest can prevent chilling harm in fruit. The best dosage of Put for treating yellow melon remains unknown, and the underlying mechanisms are not well understood. This study aimed to investigate the effects of exogenous putrescine application on chilling injury in melons and to elucidate the underlying physiological and molecular mechanisms involved. In this study, melons were treated with various concentrations of Put (0, 1, 2, and 4 mM), and the phenotype, chilling injury index, endogenous polyamine content, activities of crucial enzymes, and expression levels of associated genes (CmADC, CmODC, CmSAMDC1-4, CmSPDS1-2, CmSPMS1-2, and CmCBF1-4) were measured during storage. In our study on yellow melon, we found that treatment with 2 mM Put optimally alleviated chilling injury. This effect was achieved by enhancing the activities of ADC, AIH, CPA, ODC, SAMDC, DAP, and PAO, thereby regulating the endogenous levels of Put, Spd, and Spm. Furthermore, Put mainly impacted the expression of CmCBFs, which might help regulate downstream cold-inducible genes, leading to the improvement of tolerance in yellow melon fruit. Exogenous Put enhances melon chilling tolerance by activating endogenous polyamine biosynthesis and the CBF signaling pathway. This provides an effective strategy for post-harvest preservation of melons and might serve as a guide for future research into the mechanism involved in Put-induced chilling tolerance in horticulture crops. Full article

The stable and safe integration of exogenous DNA into the genome is crucial to both genetic engineering and gene therapy. Traditional transgenesis approaches, such as those using retroviral vectors, result in random genomic integration, posing the risk of insertional mutagenesis and transcriptional dysregulation. Safe harbor sites (SHSs), genomic loci that support reliable transgene expression without compromising endogenous gene function, genomic integrity, or cellular physiology, have been identified and characterized across various model organisms. Well-established SHSs such as AAVS1, ROSA26, and CLYBL are routinely utilized for targeted transgene integration in human cells. Recent advances in genome architecture, gene regulation, and genome editing technologies are driving the discovery of novel SHSs for precise and safe genetic modification. This review aims to provide a comprehensive overview of SHSs and their applications that will guide investigators in the choice of SHS, especially when complementary sites are needed for more than one transgene integration. First, it outlines safety and functional criteria that qualify a genomic site as a safe harbor site. It then discusses the two primary strategies for identifying SHSs: i) traditional lentiviral-based random transgenesis, and ii) modern genome-wide in silico screening followed by CRISPR-based validation. This review also provides an updated catalogue of currently known SHSs in the human genome, detailing their characteristics, uses, and limitations. Additionally, it discusses the diverse applications of SHSs in basic research, gene therapy, CAR T cell-based therapy, and biotechnological production systems. Finally, it concludes by highlighting challenges in identifying universally applicable SHSs and outlines future directions for their refinement and validation across biological systems. Full article

Reproductive-stage drought arrests silk elongation, causing a greater anthesis-silking interval and subsequent kernel loss in maize. Exogenous brassinolide (BR) is known to increase drought tolerance; however, its influence on silk growth under water deficit remains unresolved. Here, we subjected maize to drought before tassel emergence (V13) and then applied foliar BR at concentrations of 0, 0.1, 0.5, or 1 mg mL⁻¹, with distilled water-sprayed plants serving as controls. Silk elongation under water-deficit stress was partially restored by 0.1 and 0.5 mg mL⁻¹ BR but suppressed by 1 mg mL⁻¹, with 0.5 mg mL⁻¹ increasing silk length by 2.9-fold compared to the stress control, recovering it to 26.5% of the well-watered level. This protection was underpinned by elevated antioxidant capacity (POD, SOD, and CAT by 31–77%, 12–46%, and 20–33%, respectively) and a 25–76% rise in proline relative to the distilled water-sprayed, which collectively curtailed oxidative damage, as evidenced by 36–67% reductions in O₂⁻ and H₂O₂ levels and a 24% decrease in MDA content. Critically, BR reprogrammed sugar metabolism: sucrose phosphate synthase (SPS) activity declined, while sucrose synthase (SS-I) and vacuolar invertase (VIN) activities surged, thereby shifting carbon partitioning from sucrose toward hexoses to sustain energy supply for silk growth. Genome-wide RNA-seq identified 6171 upregulated and 3295 downregulated genes, significantly enriched in 20 pathways, including starch/sucrose metabolism, glycolysis/gluconeogenesis, and phenylpropanoid biosynthesis. The expression of key genes, including sucrose invertase (INV) and hexokinase (HK), was significantly upregulated by 2.4- to 8.7-fold and 2.3- to 4.0-fold, respectively, compared to the distilled water-sprayed control. This multi-level analysis demonstrates that BR mitigates drought-induced silk growth arrest by orchestrating antioxidant defense, osmotic regulation, and metabolic reprogramming into a coordinated network, providing mechanistic insights into brassinosteroid-mediated reproductive stress adaptation in maize. Full article

Extracellular polymeric substances (EPSs) produced by actinomycetes of the genus Rhodococcus play crucial roles in their ecological success, metabolic versatility, and biotechnological value. This review summarizes existing studies of Rhodococcus EPSs, emphasizing the biochemical composition, functional attributes, and practical significance of EPSs, as well as their importance in biomedicine, bioremediation, and other applications (food industry, biomineralization) with respect to the EPS chemical composition and biological roles. Rhodococcus species synthesize complex EPSs composed primarily of polysaccharides, proteins and lipids that, like in other bacteria, support cell adhesion, aggregation, biofilm formation, and horizontal gene transfer (and can prevent exogenous DNA binding) and are highly important for resistance against toxicants and dissolution/assimilation of hydrophobic compounds. EPSs produced by different species of Rhodococcus exhibit diverse structures (soluble EPSs, loosely bound and tightly bound fractions, capsules, linear and branched chains, amorphous coils, rigid helices, mushroom-like structures, extracellular matrix, and a fibrillar structure with a sheet-like texture), leading to variations in their properties (rheological features, viscosity, flocculation, sorption abilities, compression, DNA binding, and interaction with hydrophobic substrates). Notably, the EPSs exhibit marked emulsifying and flocculating properties, contributing to their recognized role in bioremediation. Furthermore, EPSs possess antiviral, antibiofilm, anti-inflammatory, and anti-proliferating activities and high viscosity, which are valuable in terms of biomedical and food applications. Despite extensive industrial and environmental interest, the molecular regulation, biosynthetic pathways, and structural diversity of Rhodococcus EPSs remain insufficiently characterized. Advancing our understanding of these biopolymers could expand new applications in biomedicine, bioremediation, and biotechnology. Full article

Using the cotyledonary node method, four traits related to callus induction rate were identified in 185 soybean germplasm resources. Cultivation of callus tissue is crucial for soybean (Glycine max (L.) Merr.) genetic transformation and functional genomics studies. Identifying genes associated with the induction rate of soybean callus tissue is therefore essential for biotechnological breeding and for understanding the molecular genetic mechanisms of soybean regeneration. The efficiency of genetic transformation impacts the breeding rate of soybeans, with its success rate dependent on the soybean regeneration system. Subsequently, whole genome association analysis (GWAS) and multidimensional functional validation were conducted. GWAS identified 66 significantly associated SNP loci corresponding to the four traits. Expression analysis in extreme phenotypes highlighted four candidate genes: Glyma.12G164100 (GmARF1), Glyma.12G164700 (GmPPR), Glyma.02G006200 (GmERF1), and Glyma.19G128800 (GmAECC1), which positively regulate callus formation. Overexpression and gene-editing assays in hairy roots confirmed that these genes significantly enhanced callus formation rate and density, with GmARF1 exerting the most prominent effect. Hormone profiling revealed elevated levels of gibberellin (GA), auxin (IAA), cytokinin (CTK), and other phytohormones in transgenic lines, consistent with enhanced responsiveness to exogenous GA. Overall, the results suggest that these four candidate genes may promote soybean regeneration, with GmARF1 showing the most pronounced effect. These results provide valuable genetic resources for improving soybean regeneration efficiency and accelerating genetic transformation-based breeding. Full article

Climate change increasingly challenges viticulture, demanding innovative and sustainable strategies to preserve grapevine productivity and grape quality. MicroRNA-encoded peptides (miPEPs) have emerged as natural regulators of gene expression, providing a novel mechanism for fine-tuning plant metabolism. Here, we evaluated whether exogenous application of miPEP164c, previously shown to repress VviMYBPA1 in vitro, can modulate flavonoid pathways in field-grown grapevines (Vitis vinifera L. cv. Vinhão). Grape clusters were sprayed with 1 µM miPEP164c before and during véraison, and molecular, biochemical, and metabolomic analyses were performed at harvest. miPEP164c treatment significantly upregulated pre-miR164c transcripts, leading to post-transcriptional silencing of VviMYBPA1 and strong downregulation of the proanthocyanidin-related genes VviLAR1, VviLAR2, and VviANR. Correspondingly, LAR and ANR activities were reduced by up to 75%, and total proanthocyanidin content decreased by nearly 30%. Metabolomic profiling showed reduced flavan-3-ols and moderate shifts in phenolic acids and stilbenoids, while anthocyanins increased slightly. Overall, miPEP164c reprogrammed flavonoid metabolism under vineyard conditions, selectively lowering tannin biosynthesis without affecting other key phenolics. These findings establish miPEPs as promising biostimulants for precise modulation of grape berry composition, offering new tools for urgently needed sustainable and precision viticulture and improved wine quality under climate change and the increasing environmental challenges it poses. Full article

Citrus species develop fruits through both sexual reproduction and parthenocarpy, following a growth pattern with an initial exponential phase dominated by cell division in the ovary wall, followed by a linear phase driven by cell expansion in juice vesicles. Sustained carbohydrate supply is essential to support the metabolic energy required for these processes, which are tightly regulated by hormonal signaling pathways involving gibberellins (GAs), auxins (IAA), cytokinins, and abscisic acid (ABA). Recent studies across cultivars have identified genes associated with hormone biosynthesis, carbohydrate metabolism, cell cycle regulation, and abscission in ovule and pericarp tissues. Manipulation of these hormones through targeted treatments and cultural practices has shown potential to enhance fruit set and growth. Notably, exogenous GA₃ application promotes fruit set in parthenocarpic cultivars by upregulating GA20ox2/GA3ox and CYCA1.1, whereas synthetic auxins enhance fruit enlargement by improving assimilate partitioning and water uptake. Optimizing such treatments, however, requires a comprehensive understanding of physiological, environmental, and agronomic factors influencing fruit development. This review summarizes recent advances in hormonal and molecular regulation of citrus fruit set and developments, assesses applied strategies to improve productivity, and identifies current knowledge gaps needed to refine biotechnological and management aimed at enhancing both yield and fruit quality. Full article

The excessive and random production of summer shoots poses significant challenges to pest and disease management and the improvement of fruit quality in citrus orchards. Although heavy fruit load has been observed to reduce summer shoot numbers, the mechanism is not well understood. This study combined a field investigation with a de-fruiting experiment to demonstrate that significant negative correlation exists between fruit load and summer shoot numbers in citrus orchard. Metabolomic analysis further indicated that fruits at the cell expansion stage function as dominant carbohydrate sinks, attracting more soluble sugars. De-fruiting significantly elevated sugar content and upregulated the transcript levels of sink strength-related genes (Sucrose synthase, CsSUS4/5/6) by more than 3.0-fold in the axillary buds. Additionally, exogenous application of sugar-related DAMs (differentially accumulated metabolites), such as sucrose, significantly promoted axillary bud outgrowth. Taken together, our findings confirm that heavy fruit load suppresses shoot branching, primarily through competing for soluble sugars. This provides a physiological basis for managing summer shoots by regulating fruit load, offering a practical strategy to enhance citrus orchard management and the effectiveness of pest and disease control programs. Full article

This study systematically evaluated insect resistance in transgenic poplar lines carrying three distinct Bacillus thuringiensis (Bt) gene vector architectures: a single-gene pb vector (Cry1Ac), a reverse-oriented double-gene n19 vector (Cry1Ac-Cry3A), and a forward-oriented double-gene n5 vector (Cry3A-Cry1Ac). The transgenic lines were accordingly designated as pb8/pb9, n19a/n19b, and DB7/DB16, respectively. Molecular analyses confirmed stable Bt gene integration, with the expression of Cry3A being consistently higher than that of Cry1Ac expression. Bioassays showed that dual-gene lines conferred broader insect resistance to pests than that of single-gene lines against both lepidopteran (Hyphantria cunea) and coleopteran (Plagiodera versicolora, Anoplophora glabripennis) pests. In contrast, the single-gene line pb9 exhibited specialized, high efficacy against H. cunea, achieving 100% mortality. Transcriptomic analysis of P. versicolora larvae fed the double-gene high-resistance n19a line and low-resistance DB16 line revealed multi-level molecular responses to Bt stress, including up-regulation of toxin-activating proteases, altered receptor expression, and suppression of growth-related genes. These changes were associated with significant developmental delay (8.33–20.83% reduction in the molting index). Our findings characterize the insect resistance and molecular profiles of the six transgenic poplar lines, as follows: multi-gene lines (n19a/n19b and DB7/DB16) confer broad-spectrum pest resistance, whereas single-gene lines (pb8/pb9) exhibit targeted efficacy. These results support the utility of these lines for pest-specific poplar breeding programs. Full article

Transient receptor potential melastatin 2 (TRPM2) channel is a Ca²⁺-permeable, redox-activated cardiac ion channel protective in ischemia–reperfusion, but whether it regulates atrial endocrine output under stress is unclear. Here, we investigated whether TRPM2 contributes to the atrial natriuretic peptide (ANP) response during β-adrenergic stimulation. We compared how male C57BL/6J wild-type (WT) and TRPM2 knockout (TRPM2^−/−) mice (8–12 weeks old) respond to β-adrenergic stress induced by isoproterenol (ISO) using echocardiography, histology, RT-PCR, electrophysiology, Ca²⁺ imaging, ELISA, and atrial RNA-seq. We detected abundant Trpm2 transcripts in WT atria and measured ADP-ribose (ADPr)-evoked currents and hydrogen peroxide (H₂O₂)-induced Ca²⁺ influx characteristic of TRPM2; these were absent in TRPM2^−/− cells. Under the ISO-induced hypertrophic model, TRPM2^−/− mice developed greater cardiac hypertrophy, fibrosis, and systolic dysfunction compared with WT mice. Atrial bulk RNA-seq showed significant induction of Nppa (ANP precursor gene) in WT + ISO, accompanied by higher circulating ANP; TRPM2^−/− + ISO showed blunted Nppa and ANP responses. ISO-treated TRPM2^−/− mice exhibited more blunt responses, in both Nppa transcripts and circulating ANP levels. Exogenous ANP attenuated ISO-induced dysfunction, hypertrophy, and fibrosis in TRPM2^−/− mice, suggesting that TRPM2 is needed for the cardioprotective endocrine response via ANP to control stress-induced β-adrenergic remodeling. Full article

The inhibition of low-position tillering in machine-transplanted seedlings affects rice yields. Paclobutrazol (PBZ) is a plant growth regulator that can improve seedling quality and promote low-position tillering in machine-transplanted seedlings. However, the physiological mechanisms underlying the promotion of tiller bud formation induced by exogenous PBZ via sucrose transport remain unclear. Thus, rice cultivar ‘Yongyou 12’ was used to analyze the effects of different seeding rates and the application of exogenous PBZ, gibberellin (GA₃), and water (control) on sucrose transport and metabolism as well as tiller bud development. Exogenous PBZ application combined with a low seeding rate significantly increased the number of tillers as well as seedling fullness (by 42.35%). Increases were also detected for the seedling cytokinin content, chlorophyll content (by 10.55%), and sucrose transport from leaves to the stem base. These changes were associated with the upregulated expression of sucrose transporter genes in leaves and the stem base, as well as increased activities of key sucrose-metabolizing enzymes in the stem base. Notably, the opposite trend was observed after exogenous GA₃ was applied or a high seeding rate was used. Hence, a low seeding rate combined with exogenous PBZ application is useful for controlling seedling height, promoting the formation of low-position tillering, facilitate sucrose translocation from leaves to the stem base, and increasing sucrose metabolism in the basal part of rice plants. These findings provide a theoretical basis for optimizing low-position tillering in machine-transplanted seedlings. Full article