Search Results (231)

The cryopreservation of limited sperm samples, especially those retrieved from patients, poses significant challenges due to the small number of viable cells available for freezing. Traditional microliter cryopreservation methods are fraught with difficulties, as thawed sperm cells become nearly impossible to locate under a microscope due to their mobility and the multiple focal planes presented by larger drops. This search time is critical, as sperm cells enter a state of decline post thaw. Conversely, when sperm cells are cryopreserved in nanoliter volumes, they can be easily discovered but do not survive the freezing and thawing processes entirely. This phenomenon is attributed to the diffusion of water molecules from the droplet into the surrounding oil, which, while designed to limit evaporation, inadvertently increases solute concentrations in the aqueous environment, leading to cellular desiccation. This article elucidates the mechanisms underlying this lethal diffusion effect and presents a novel approach for freezing in nanoliter volumes, which has demonstrated significantly improved survival rates through carefully optimized procedures in clinical trials. Our findings highlight the importance of adapting cryopreservation techniques to enhance the viability of individual sperm cells, ultimately facilitating better outcomes in assisted reproductive technologies. This study provides the first quantification of nanoscale water diffusion dynamics during cryopreservation, establishing a predictive model that explains the catastrophic loss of sperm viability and identifying the critical role of water diffusion as a major impediment for limited samples. The novelty of our results lies in both elucidating this specific mechanism of cell death and introducing a novel approach: utilizing water-saturated oil as a protective layer. This method effectively mitigates the osmotic stress caused by water loss, demonstrating remarkably improved cell survival. This work not only advances the scientific understanding of cryopreservation at the nanoscale but also offers a practical, impactful solution poised to revolutionize fertility treatments for patients with low sperm counts and holds promise for broader applications in biological cryopreservation. Full article

Plant abiotic stresses are the main cause of significant crop losses worldwide. The moss Pseudocrossidium replicatum is highly tolerant to different types of abiotic stress, such as desiccation. Our group is interested in identifying and characterising differentially expressed genes in response to abiotic stress in this species. However, a collection of validated reference genes for RT-qPCR analysis is essential to normalise the expression of genes in response to the conditions of interest. Here, we assessed 13 candidate reference genes for P. replicatum based on their expression stability across transcriptomes from six abiotic stress-related conditions using the RefFinder, BestKeeper, geNorm, and NormFinder programs. The stability and reliability of the proposed reference genes were evaluated under six experimental conditions: control, dehydration, rehydration, abscisic acid (ABA), NaCl, and sorbitol. Interestingly, most proposed reference genes exhibited high stability (low M values) across all analysed abiotic stress conditions. A pairwise variation analysis indicated that only one pair is necessary to normalise RT-qPCR experiments. Each gene was confirmed to normalise the expression of both upregulated and downregulated genes. This represents the first report of validated reference genes for RT-qPCR gene expression studies under abiotic stress in the protonemal tissue of a fully desiccation-tolerant moss. Full article

Nostoc flagelliforme, a filamentous cyanobacterium inhabiting desert biological soil crusts (BSCs), has developed exceptional strategies to endure extreme environmental stresses, including severe desiccation, intense ultraviolet (UV) radiation, and drastic temperature fluctuations. These organisms must effectively sense and predict environmental changes, particularly the onset of desiccation. This review explores recent advancements in the molecular mechanisms that enable N. flagelliforme to survive under such harsh conditions, with a focus on stress signal sensing, transduction pathways, and photosynthetic adjustments. Key molecular adaptations include the production of extracellular polysaccharide (EPS) sheaths for water retention, the accumulation of compatible solutes like trehalose, and the synthesis of UV-absorbing compounds such as scytonemin and mycosporine-like amino acids (MAAs). Furthermore, N. flagelliforme utilizes a complex signal transduction network, including light-sensing pathways, to regulate responses to rehydration and desiccation cycles. This review emphasizes the integrative nature of N. flagelliforme’s adaptive mechanisms and highlights their potential for biotechnological applications, such as enhancing drought tolerance in crops and advancing ecological restoration in arid regions. Full article

Background/Objectives: Desiccation profoundly influences the distribution and abundance of intertidal seaweeds, necessitating robust molecular adaptations. Sargassum muticum is a brown seaweed inhabiting intertidal rocky substrates. During low tides, this species undergoes periodic aerial exposure. Such environmental conditions necessitate robust physiological mechanisms to mitigate desiccation stress. Yet, the molecular basis of this adaptation remains poorly understood. Methods: To investigate desiccation-responsive genes and elucidate the underlying mechanisms of adaptation, we exposed S. muticum to 6 h of controlled desiccation stress in sterilized ceramic trays, simulating natural tidal conditions, and performed comparative transcriptome analysis using RNA-seq on the Illumina NovaSeq 6000 platform. Results: High-quality sequencing identified 66,192 unigenes, with 1990 differentially expressed genes (1399 upregulated and 591 downregulated). These differentially expressed genes (DEGs) were categorized into regulatory genes—including mitogen-activated protein kinase (MAPK), calmodulin, elongation factor, and serine/threonine-protein kinase—and functional genes, such as heat shock protein family members (HSP20, HSP40, and HSP70), tubulin (TUBA and TUBB), and endoplasmic reticulum homeostasis-related genes (protein disulfide-isomerase A6, calreticulin, and calnexin). Gene Ontology (GO) enrichment highlighted upregulated DEGs in metabolic processes like glutathione metabolism, critical for oxidative stress mitigation, while downregulated genes were linked to transport functions, such as ammonium transport, suggesting reduced nutrient uptake during dehydration. KEGG pathway analysis revealed significant enrichment in “protein processing in endoplasmic reticulum” and “MAPK signaling pathway-plant”, implicating endoplasmic reticulum stress response and conserved signaling cascades in desiccation adaptation. Validation via qRT-PCR confirmed consistent expression trends for key genes, reinforcing the reliability of transcriptomic data. Conclusions: These findings suggest that S. muticum undergoes extensive biological adjustments to mitigate desiccation stress, highlighting candidate pathways for future investigations into recovery and tolerance mechanisms. Full article

Pyropia haitanensis (T.J. Chang and B.F. Zheng) undergoes periodic dehydration and rehydration cycles, necessitating robust adaptive mechanisms. Despite extensive research on its physiological responses to desiccation stress, the comprehensive metabolic pathways and recovery mechanisms post-rehydration remain poorly understood. This study investigated the metabolic responses of P. haitanensis to varying degrees of desiccation stress using LC-MS and UPLC-MS/MS. Under mild dehydration, the thallus primarily accumulated sugars and proline, while moderate and severe dehydration triggered the accumulation of additional osmoprotectants like alanine betaine and trehalose to maintain turgor pressure and water retention. Concurrently, the alga activated a potent antioxidant system, including enzymes and non-enzymatic antioxidants, to counteract the increased reactive oxygen species levels and prevent oxidative damage. Hormonal regulation also plays a crucial role in stress adaptation, with salicylic acid and jasmonic acid upregulating under mild dehydration and cytokinins and gibberellin GA₁₅ accumulating under severe stress. Rehydration triggered the recovery process, with indole acetic acid, abscisic acid, and jasmonic acid promoting rapid cell recovery. Additionally, arachidonic acid, acting as a signaling molecule, induced general stress resistance, facilitating the adaptation of the thallus to the dynamic intertidal environment. These findings reveal P. haitanensis’ metabolic adaptation strategies in intertidal environments, with implications for enhancing cultivation and stress resistance in this economically important seaweed. Full article

In drylands, microalgae dwelling in the biocrust are inevitably confronted with nitrogen deficiency and desiccation stress, despite the protection afforded by the soil biological complex. However, the environmental adaptive features and mechanisms of these microalgae remain largely unknown. In this study, we explored the adaptive changes of a biocrust-derived unicellular microalga, Vischeria sp. WL1 (Eustigmatophyceae), in the face of long-term nitrogen deficiency. Attention was focused on the alterations in cell wall properties and the associated desiccation resistance. After exposure to long-term nitrogen deficiency, the cell walls of Vischeria sp. WL1 thickened substantially, accompanied by enhanced rigidity and an improvement in desiccation resistance. In contrast, Vischeria sp. WL1 cells cultivated under nitrogen-replete conditions were highly vulnerable to desiccation stress. Additional cell wall alterations after nitrogen starvation included distinct surface sculpturing, variations in monosaccharide composition, and changes in functional groups. Collectively, this study provides valuable insights into the survival strategies of biocrust-derived microalgae in nitrogen-deficient dryland environments. Full article

Deinococcus radiodurans is a remarkably unique microorganism, exhibiting extraordinary tolerance to extreme conditions such as ionizing radiation, ultraviolet light, and desiccation. However, the response mechanisms of D. radiodurans under low-temperature stress remain largely unexplored and have yet to be fully elucidated. The DohD protein is a hydrophilic member of the late embryogenesis abundant 3 (LEA3) family of D. radiodurans, playing a pivotal role in abiotic stress adaptation. Bioinformatics analysis revealed that DohD contains tandem repeats and disordered domains, with a remarkably high α-helix content (91.41%). Furthermore, DohD exhibits extremely low homology with other proteins, highlighting its uniqueness to D. radiodurans. Under low-temperature stress (15 °C), the expression of dohD was significantly upregulated (5-fold), regulated by a dual mechanism involving positive control by DrRRA and negative regulation by Csp. Circular dichroism spectroscopy unveiled temperature-dependent structural plasticity: as the temperature increased from 0 °C to 50° C, the α-helix content decreased from 23.5% to 18.7%, while the antiparallel β-sheet content increased from 31.3% to 50.8%. This suggests an α-helix to β-sheet interconversion mechanism as a strategy for thermal adaptation. Additionally, deletion of dohD impaired the tolerance of D. radiodurans to cold, desiccation, oxidative, and high-salt stresses, accompanied by the reduced activities of antioxidant enzymes (SOD, CAT, POD) and the downregulation of related gene expression. This study elucidates the multifunctional role of DohD in stress resistance through structural dynamics, transcriptional regulation, and redox homeostasis, providing valuable insights into the adaptation mechanisms of extremophiles. Full article

Understanding how woody plants cope with severe water shortages is critical, especially for regions where droughts are becoming more frequent and intense. We studied the effects of drought intensity, focusing on post-drought resprouting, autumn leaf senescence and the subsequent spring bud burst. Furthermore, we aimed to study population differentiation in the drought and post-drought responses. We performed a summer dry-out experiment in a common garden of potted Prunus spinosa L. (Rosaceae) saplings. We analysed responses across different visual stress symptom categories and examined differentiation between provenances from a local origin (Western Europe, Belgium), a lower latitude (Spain) and a higher latitude (Sweden). The chance of post-drought resprouting was greater for the more severely affected plants than for the less severely affected ones, and it occurred earlier. The plants that displayed wilting of the leaves during the drought had a leaf senescence 2.7 days earlier than the controls, whereas that of plants with 25 to 75% and more than 75% of desiccated leaves was 7 and 15 days later, respectively. During the drought, the local provenance was the first to develop visual symptoms compared to the other two provenances. However, among plants that exhibited no or only mild symptoms, this provenance also had a higher likelihood of post-drought resprouting. Among the control plants, the higher-latitude provenance displayed leaf senescence earlier, while the lower-latitude provenance senesced later compared to the local provenance. However, these differences in the timing of leaf senescence among the three provenances disappeared in treated plants with more than 25% of desiccated leaves due to the drought. Whereas leaf senescence could be earlier or later depending on the developed drought symptoms, the timing of bud burst was only delayed. Results indicate that resprouting and timing of leaf senescence are responsive to the severity of the experienced drought in a provenance-dependent way. Full article

Background: Nanocrystals, a carrier-free nanotechnology, offer significant advantages for pulmonary drug delivery by enhancing the dissolution and solubility of poorly soluble drugs while maintaining favorable biological properties and low toxicity. This study aims to investigate the aerodynamic performance and stability of nanocrystal-based dry powders (NC-DPs). Methods: Nanocrystalline suspensions were produced via wet media milling and subjected to stability studies before undergoing nano spray drying. A factorial design was employed to optimize the process parameters. The influence of mannitol and leucine, individually and in combination, was evaluated in terms of aerodynamic properties (Aerodynamic Particle Sizer (APS), in silico modeling) and the physicochemical stability at room temperature (in a desiccator) and accelerated conditions (40 ± 2 °C, 75 ± 5% relative humidity). Results: APS analysis revealed that leucine-containing powders (K-NC-Ls) exhibited the smallest median (1.357 µm) and geometric mean (1.335 µm) particle sizes, enhancing dispersibility. However, in silico results indicated the highest exhaled fraction for K-NC-L, highlighting the need for optimized excipient selection. Although mannitol showed the lowest exhaled fraction, it was mainly deposited in the extra-thoracic region in silico. The mannitol/leucine combination (K-NC-ML) revealed a low exhaled fraction and high lung deposition in silico. Also, K-NC-ML demonstrated superior stability, with a 6% reduction in D[0.5] and a 5% decrease in span overtime. Furthermore, no significant changes in crystallinity, thermal behavior, drug release, or mass median aerodynamic diameter were observed under stress conditions. Conclusions: These findings confirm that combined incorporation of mannitol and leucine in NC-DP formulations enhances stability and aerodynamic performance, making it a promising approach for pulmonary drug delivery. Full article

A syndrome called “Kiwifruit Decline Syndrome” (KiDS) affects kiwifruit in several Mediterranean areas, causing growth arrest and wilt that rapidly progress to desiccation, scarce root growth, absence of fibrous roots, brown soft-rotting areas, and cortical detachment from the central cylinder. The origin is considered multifactorial, and a correlation with hydraulic conductance impairment caused by a high vapor pressure deficit (VPD) and temperature was detected. In this work, over-tree micro-sprinkler irrigation and shading nets were tested to protect leaves from overheating and locally decrease VPD. Leaf gas exchanges, leaf temperature, stem water potential, stem growth, root starch content, root xylem vessel diameter, density, and vulnerability to cavitation were assessed. A positive effect of over-tree irrigation associated with shading was observed: lower leaf temperature, higher stem water potential, stomatal conductance, and photosynthesis were detected; moreover, root starch content was higher in the summer. Narrow xylem vessel diameters were observed, indicating a long-term adaptation to rising VPD for lower vulnerability to cavitation, in all plants, but higher diameter, lower density, and higher vulnerability index indicated lower plant water stress under over-tree irrigation associated with shading. These results indicate that microclimate control by proper agronomic management can protect kiwifruit from climate stress, decreasing the risk of KiDS onset. Full article

The extensive utilization of nano-zero-valent iron (nZVI) and its engineered derivatives has prompted significant environmental concerns, particularly regarding their phytotoxicological impacts, which remain inadequately characterized. This investigation systematically evaluated the phytotoxicological responses induced by nZVI, Chlorella vulgaris biochar (BC), and Chlorella vulgaris biochar loaded with nano-zero-valent iron (BC/nZVI) on mung bean seed germination and subsequent seedling development. The experimental data revealed that both the nZVI and BC/nZVI treatments significantly suppressed the germination indices, including germination rate, radicle and plumule elongation, and biomass accumulation, with nZVI demonstrating the most pronounced inhibitory effects. During the vegetative growth phases, nZVI exposure substantially impaired plant morphogenesis, manifested through reduced vertical growth, diminished fresh and dry biomass production, and the onset of premature foliar chlorosis, necrosis, desiccation, and, ultimately, plant mortality. A comparative analysis indicated that the BC/nZVI composites exhibited less severe photosynthetic inhibition relative to pristine nZVI. Biochemical assays demonstrated that nZVI exposure elicited the substantial upregulation in antioxidant enzyme activities, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), concomitant with abnormal ferric ion accumulation in root tissues. Notably, BC/nZVI composites demonstrated the partial mitigation of these physiological disturbances. These empirical findings underscore that excessive iron bioavailability from nZVI induces substantial phytotoxicological stress, while BC matrix incorporation provides the partial amelioration of these adverse effects on seedling ontogeny. Full article

Microbes that survive transport to and in the stratosphere endure extremes of low temperature, atmospheric pressure, and relative humidity, as well as high fluxes in ultraviolet radiation (UVR). The high atmosphere thus provides an ideal environment to explore the genetic and physiological determinants conveying high tolerance to desiccation and UVR. In this study, we examined Curtobacterium aetherium L6-1, an actinobacterium obtained from stratospheric aerosol sampling that displays high resistance to desiccation and UVR. We found that its phylogenetic relatives are resistant to desiccation, but only C. aetherium displayed a high tolerance to UVR. Comparative genome analysis and directed evolution experiments implicated genes encoding photolyase, DNA nucleases and helicases, and catalases as responsible for UVR resistance in C. aetherium. Differential gene expression analysis revealed the upregulation of DNA repair and stress response mechanisms when cells were exposed to UVR, while genes encoding sugar transporters, sugar metabolism enzymes, and antioxidants were induced upon desiccation. Based on changes in gene expression as a function of water content, C. aetherium can modulate its metabolism through transcriptional regulation at very low moisture levels (X_w < 0.25 g H₂O per gram dry weight). Uncovering the genetic underpinnings of desiccation and UVR resistance in C. aetherium provides new insights into how bacterial DNA repair and antioxidant mechanisms function to exhibit traits at the extreme ends of phenotypic distributions. Full article

The rhizosphere microbiota of arid plants plays a crucial role in adaptation to environmental stress. However, few studies have characterized microorganisms associated with Agave species and their contribution to resilience against salinity and drought. This study aimed to isolate and characterize halotolerant bacteria from the rhizosphere of Agave potatorum Zucc from two different sites and evaluate their in vitro Na⁺ sequestration, desiccation resistance, and phytohormone production. These traits were compared with those of halotolerant bacteria isolated from a highly saline soil at a third site. Bacteria were obtained through serial dilutions and cultured on R2A plates supplemented with varying NaCl concentrations. The most efficient Na⁺-sequestering isolates underwent an 18-day desiccation assay, and their production of indole-3-acetic acid (IAA) and gibberellic acid (GA₃) was quantified. Among the 48 halotolerant isolates obtained, 7 (SM1, SM10, SPM5, SM7, SM19, VZ9, and SPM1) exhibited the highest Na⁺ sequestration efficiency. Among these isolates, SM1 exhibited the highest in vitro Na⁺ sequestration capacity (10.74 μg L⁻¹, p < 0.05). SM1 and SPM1 demonstrated the greatest desiccation resistance, at 88.39% and 83.05%, respectively. Additionally, SM7 produced the highest levels of IAA (13.69 μg mL⁻¹, p < 0.05), while SM1 exhibited the highest GA₃ production (1285.38 μg mL⁻¹, p < 0.05). Based on these characteristics, isolates SPM1 and SM1 exhibited the highest efficiency in tolerating drought and salinity stress. However, isolate SPM1 may colonize the rhizosphere of A. potatorum more effectively, likely due to its adaptation as a native isolate to the edaphic and environmental conditions in which this agave thrives. Molecular identification confirmed that the isolates belong to the genera Kosakonia, Priestia, Streptomyces, Bacillus, Stutzerimonas, Pseudomonas, and Exiguobacterium. This study highlights the diversity of halotolerant bacteria in the rhizosphere of A. potatorum and their potential as bioinoculants for enhancing soil fertility and restoring degraded soils. Full article

In this study, the acid resistance and desiccation tolerance of 20 strains of Cronobacter malonaticus were explored, and their genetic variances with respect to their survival in stressful conditions were identified by genomic analysis. The strains showed significant variances in acid tolerance when exposed to simulated gastric acid (pH 3.5) for 2 h. Strain 685 demonstrated less viability, suggesting greater susceptibility. Desiccation in infant formula also yielded sub-lethally injured cells, with variable strain recovery, highlighting strain 685 as the strain with the lowest recovery. Strains were determined to contain single nucleotide polymorphisms (SNPs) in the ompR and rpoS genes, suggesting loss-of-function mutations and potentially elucidating the stress sensitivity mechanism of strain 685. This study underscores the importance of genetic factors in C. malonaticus resilience and the necessity for developed detection methods for assessing food safety risk, especially in relation to powdered infant formulas. Our results provide important information on the pathogenic potential of C. malonaticus and help guide future research priorities to mitigate risks associated with foodborne pathogens. Full article

Rosa rugosa is an excellent aromatic plant species valued for both essential oil extraction and ornamental applications. This study aimed to evaluate its adaptive responses, bioaccumulation capacity, and production quality under cadmium (Cd) stress, providing insights for phytoremediation and sustainable agriculture. A controlled pot experiment was conducted using two cultivars (R. rugosa ‘Zizhi’ and its bud mutation R. rugosa ‘Baizizhi’) subjected to various Cd treatments. Growth parameters and physiological indices, such as antioxidant enzyme activities, chlorophyll content, photosynthesis rates, and floral volatile organic compounds, were systematically analyzed. Cd concentrations ranging from 5 to 50 mg·kg⁻¹ maintained plant growth, but significantly elevated antioxidant activities (SOD + 65.94–300.53%, POD + 37.58–75.06%, CAT + 12.48–12.62%) and chlorophyll content (+20.27–242.79%). In contrast, 400 mg·kg⁻¹ Cd severely inhibited growth, inducing chlorosis and leaf desiccation. Total floral volatiles showed a hormetic response, peaking at 200 mg·kg⁻¹ (+46.08%). Sesquiterpenoids showed greater Cd-responsiveness than monoterpenoids, though core aromatic profiles remained stable. The species exhibited root bioconcentration BAF > 0.1 and limited translocation TF < 1, indicating phytostabilization potential. Despite tolerance up to 400 mg·kg⁻¹, field application is recommended below 50 mg·kg⁻¹—a threshold exceeding China’s soil Cd limits (GB 15618-2018). These findings position it as a dual-purpose crop for ecological restoration and fragrance production in Cd-impacted areas. Full article