Search Results (242)

US food regulatory agencies have adopted a preference for researchers and testing labs to use ‘acid-adapted challenge cultures’ when performing inoculated validation studies of food processes that involve acidic treatments to accustom the cultures to acidic pH so that they will not be easily affected during processing. We evaluated acid adaptation in regard to the processing of South African style air-dried beef, notably biltong and droëwors, using a mixture of five serovars of Salmonella as well as a unique serovar isolated from dried beef (Salmonella Typhimurium 1,4,[5],12:i:-). Acid adaptation was obtained by growing cultures in tryptic soy (TS) broth containing 1% glucose. Non-adapted cultures were obtained by growth in TS broth without glucose or in TS broth with 1% glucose but buffered with 0.2 M phosphate buffer. Processes included biltong (dried solid beef) and droëwors (ground, sausage-style). Each trial was performed twice and triplicate samples were examined at each sampling point (i.e., n = 6). Statistical analysis was applied using analysis of variance (ANOVA) or one-way repeated measures (RM-ANOVA) and the Holm–Sidak test for pairwise multiple comparisons to determine significant differences (p < 0.05). We observed that in all processes examined (eight trials), treatments using acid-adapted cultures were more sensitive to the biltong and droëwors processes, giving greater reductions (5.3-log reduction) than when non-adapted cultures were used (3.8-log reduction). Acid adaptation leads to stressed conditions in Salmonella resulting in sensitization to the multiple hurdles found in biltong and droëwors processing (acid/vinegar, salt, desiccation). Based on our data, the use of non-adapted Salmonella cultures to achieve desired challenge culture process lethality could result in more robust processing conditions and a greater level of safety in these products as intended by US regulatory guidance. Full article

Drought stress is a major environmental factor that adversely affects plant growth and development. Spermidine (SPD), a polyamine, plays a critical role in plant defense mechanisms against drought stress. PEG was used to simulate osmotic stress, which mimics drought conditions under controlled environments. This study investigated the effects of exogenous spermidine (SPD) on the physiological and biochemical responses of mango plants under drought stress and explored its potential mitigation mechanisms. Two-year-old ‘Renong 1’ mango seedlings were subjected to drought stress induced by polyethylene glycol (PEG 6000) at concentrations of 5%, 15%, and 25%, simulating mild, moderate, and severe drought conditions, respectively. Plants were subsequently treated with 1 mmol/L spermidine. After PEG 6000 treatment and spermidine application for 3 days, the leaf morphology, relative chlorophyll content, malondialdehyde (MDA) levels, antioxidant enzyme activities (superoxide dismutase [SOD], peroxidase [POD], catalase [CAT]), and osmotic regulators (proline, soluble sugars, and soluble proteins) were analyzed. The results demonstrated that drought stress caused leaf chlorosis, desiccation, reduced relative chlorophyll content, elevated MDA levels (indicating lipid peroxidation), enhanced antioxidant enzyme activities, increased proline and soluble sugar accumulation for osmotic regulation, and decreased soluble protein content. Exogenous spermidine treatment significantly alleviated drought-induced damage by reducing leaf chlorosis, delaying relative chlorophyll degradation (by 20.0–25.7% under moderate drought and 14.1–19.1% under severe drought), and decreasing MDA levels (by 4.8–9.5% under moderate drought and 0.8–23.7% under severe drought). Furthermore, spermidine enhanced antioxidant enzyme activities (e.g., SOD activity increased by 24.9–37.4% and POD by 74.0–104.0% under moderate drought), regulated osmotic substance accumulation (e.g., proline decreased by 21%, 26%, and 24% under mild, moderate, and severe drought, respectively), and mitigated the reduction in soluble protein content (by 6.6% under moderate drought and 10.3% under severe drought). In conclusion, exogenous spermidine mitigates drought-induced damage in mango by preserving photosynthetic capacity, enhancing the antioxidant defense system, and modulating osmotic balance. These results showed that SPD could significantly improve plant vigor or survival rate under stress. It provides a theoretical basis for water-saving cultivation of mango, improving the stress resistance of mango varieties and the application of spermidine in tropical fruit production. Full article

All solitary and primitively eusocial bees of the temperate zones survive winter in a dormant diapausing state. Weight loss of Osmia and Megachile bees has been solely attributed to metabolism of stored triglycerides, as evidenced by loss of fat body. I hypothesized that uptake or loss of water vapor may represent another contributor to wintering weight change. Using a range of atmospheric humidities (0–88%), it is shown that wintering cocooned O. californica (adults) and M. rotundata (prepupae) gained weight in humid atmospheres and lost weight in drier air, the inflection point being between 35 and 47% humidity. Most of this weight change occurred in early winter. No humidity treatment enhanced mortality. Winter storage humidity is an available management variable for these bees when kept for commercial pollination. Full article

The polar environment is one of the most extreme environments of our world. However, even in the cold deserts of Antarctica, life thrives, often in the form of biocrusts (biological soil crusts)—complex communities consisting of hundreds of organisms. The reaction to abiotic stress in members of these communities is often inferred from laboratory experiments on isolated species and single factors, without taking into consideration any mitigation effects by the communities or complex habitats. In this study, we aimed to infer the stress situation of the filamentous green alga Klebsormidium in Antarctic biocrusts in situ using metatranscriptomic data. Klebsormidium is ubiquitous in biocrusts and well studied with respect to abiotic factors, allowing the comparison of lab experiments with the in situ situation. In this study, we identified Klebsormidium flaccidum to be present in biocrusts from Livingston Island (Antarctica). Metatranscriptomic data for the biocrust were used to investigate the presence of cold and desiccation stress in situ. To this end, we identified consistently expressed and stress-regulated genes in published stress transcriptomes of Klebsormidium that could serve as markers for environmental stress levels. These “marker genes” were used to construct marker gene indices to assess stress states in biocrusts by comparing transcript expression ratios under different conditions—a novel framework for the assessment of microbial community responses to environmental stressors. However, many potential marker genes behaved quite differently in the laboratory and in the natural environment. In the end, rather than relying on indices based on individual marker genes, comparing the expression levels of whole stressor-regulated gene sets proved to be a more reliable approach to examining stress in situ. This study highlights the potential of marker genes for broader ecological and environmental monitoring using metatranscriptomic data. Full article

Group 1 LEA proteins are involved in embryo water dynamics during the maturation stage of seed development and contribute to desiccation stress protection in vegetative and embryonic tissues. Nevertheless, their roles in durum wheat remain largely unexplored. This study represents the first comprehensive survey of group 1 LEA proteins and their encoding genes in Triticum turgidum ssp. Durum (durum wheat). Eight group 1 LEA (TtEM1 to TtEM8) genes were identified in the durum wheat genome, which were named according to their chromosomal location. Analyses of the physiochemical characteristics and subcellular location revealed that all TtEM proteins exhibited a highly disordered structure (more than 90% of tendency of disorder) and were located in the nucleus. Evolutionary analysis between the durum wheat family and all other known group 1 LEA proteins from Arabidopsis thaliana, rice (Oryza sativa), barley (Hordeum vulgare), and barrel medic (Medicago truncatula) showed four phylogenetic groups; each group shares the same conserved motifs and gene structure. Interestingly, almost TtEM genes harbor cis-elements related to hormone regulation, stress response, and growth regulation, indicating their function in stress tolerance and developmental control. Subsequently, Expression analysis of two homoeologous genes, TtEM1 and TtEM4, demonstrated that the two genes exhibited distinct expression profiles across different tissues and in response to various stress treatments, suggesting that these genes may be involved in regulating growth, development, and stress adaptation in durum wheat. TtEM1 and TtEM4 purified proteins act as molecular chaperones and protect LDH activity against desiccation, cold, and heat treatments. Moreover, TtEM1 and TtEM4 genes were proved to enhance heat, cold, oxidative, and drought tolerance in yeast. These results clearly described the characteristics and the evolutionary dynamics of the EM gene family in wheat, and unveiled their role in wheat development and response to abiotic stress. Full article

Soil moisture is one of the key hydrologic components indicating the performance of landfill final covers. Conventional compacted clay (CC) covers and evapotranspiration (ET) covers often suffer from moisture-induced stresses, such as desiccation cracking and irreversible hydraulic conductivity. Engineered turf (EnT) cover systems have been introduced recently as an alternative; however, their field-scale moisture distribution behavior remains unexplored. This study investigates and compares the soil moisture distribution characteristics of EnT, ET, and CC landfill covers at a shallow depth using one year of field-monitored data in a humid subtropical region. Three full-scale test Sections (3 m × 3 m × 1.2 m) were constructed side by side and instrumented with moisture sensors at a depth of 0.3 m. Distributional characteristics of moisture were evaluated with descriptive statistics, goodness-of-fit tests such as Shapiro–Wilk (SW) and Anderson–Darling (AD), Gaussian probability density functions, Q–Q plots, and standard-normal transformations. Results revealed that Shapiro–Wilk (W = 0.75–0.92, p < 0.001) and Anderson–Darling $(A^2=1.63\times {10}^3\mathrm{to}6.31\times {10}^3,p<0.001)$ tests rejected normality for every cover, while Levene’s test showed unequal variances between EnT and the other covers $(F>5.4\times {10}^4,$$p<0.001)$ but equivalence between CC and ET (F = 0.23, p = 0.628). EnT cover exhibited the narrowest moisture envelope $(95\%\mathrm{range}=0.156\mathrm{to}0.240{\mathrm{m}}^3/{\mathrm{m}}^3;\mathrm{CV}=10.6\%)$, whereas ET and CC covers showed markedly broader distributions (CV = 38.6 % and 33.3 %, respectively). These findings demonstrated that EnT cover maintains a more stable shallow soil moisture profile under dynamic weather conditions. Full article

Polyhexamethylene guanidine phosphate (PHMG-p), a widely used disinfectant component in household humidifiers, has been implicated in various health issues, including pulmonary toxicity. Many people use humidifiers to improve dry eye disease (DED). The current study was performed to elucidate the effect of PHMG-p on eye dryness in a rat model using metabolomics. Male Sprague Dawley rats were exposed to PHMG-p (0.1% and 0.3%) following a previously established DED induction model using scopolamine hydrobromide and desiccation stress. Ocular surface damage was assessed using corneal fluorescein staining, tear volume measurement, and tear break-up time (TBUT). Plasma and urine samples were analyzed using ¹H-NMR-based metabolomics to identify metabolic alterations associated with PHMG-P-p exposure and DED pathogenesis. PHMG-p exposure exacerbated DED symptoms, as evidenced by a significant reduction in tear volume, shorter TBUT, and increased corneal damage compared to the control group. Metabolomic profiling identified distinct metabolic changes in PHMG-p-exposed groups, including alterations in glutamate, glycine, citrate, and succinate metabolism. These metabolic changes correlated with increased levels of inflammatory cytokines such as IL-1β, IL-6, and TNF-α in the corneal and lacrimal gland tissues. Our findings suggest that PHMG-p exposure contributes to DED pathophysiology by inducing metabolic disturbances and inflammatory responses in the ocular surface. This study highlights the need for further investigation into the potential risks of PHMG-p exposure on ocular health and provides novel insights into the metabolic underpinnings of DED. Full article

Resurrection plants such as Ramonda serbica and Ramonda nathaliae are gaining scientific attention due to their exceptional ability to withstand extreme drought and cold. This study is the first to evaluate the changes in photosynthetic activity, antioxidant defense, and the role of protective proteins during the early hours of recovery of these species after freezing-induced desiccation. Specimens collected from natural habitats where temperatures dropped below −10 °C were rehydrated under controlled conditions, and measurements were taken at multiple time points from 1 h up to 7 days after recovery. Both species demonstrated a gradual increase in photosynthesis, with the CO₂ assimilation rate significantly improving after 24 h and reaching full restoration by day 7. This recovery aligned with increases in relative water content and stomatal conductance. Photosystem II efficiency was fully restored within 72 h. Notably, R. nathaliae exhibited higher thermal dissipation during stress than R. serbica. Antioxidant activity peaked between 1 and 3 h of rehydration and returned to baseline by day 7. Additionally, early rehydration stages triggered the accumulation of stress-related proteins such as dehydrins, early light-inducible proteins, small heat shock proteins, and fatty acid amide hydrolase. These results provide valuable insights into the desiccation–rehydration mechanisms of Ramonda species, demonstrating that they fully recover physiological functions within seven days and highlighting species-specific stress responses during early rehydration. Full article

Lichens, complex symbiotic associations between fungi and photosynthetic partners, are widespread in terrestrial ecosystems but remain poorly studied in tropical dry forests (TDFs). This review synthesizes current knowledge on the diversity, ecological roles, adaptive traits, and ethnobotanical uses of lichens in TDFs, with a focus on the Neotropics. As most lichens discussed here are crustose species that inhabit tree bark, this paper also provides a thoughtful review of the origin, distribution, and highly heterogeneous floristic composition of TDFs, which directly shape lichen habitats. It discusses how lichens have evolved to cope with seasonal water stress, emphasizing desiccation tolerance as a key feature of the symbiosis. This review also explores lichen community composition, interactions with host trees, microclimatic conditions, herbivory, and soil crust formation. Despite evidence of high species richness, functional diversity, and ecological importance, lichens in TDFs are largely overlooked in conservation strategies. Moreover, several regions remain vastly understudied, and many species likely remain undescribed. Ethnolichenological practices, though scarce, underscore the cultural and medicinal value of these organisms. Given the high rates of habitat loss and endemism in TDFs, there is a pressing need to expand research on lichen diversity and to investigate the evolutionary origins of their survival strategies. The conservation of these lichens is inseparable from the conservation of TDFs themselves. Understanding how lichens adapt to the harsh and variable conditions of TDFs is essential for integrating them into biodiversity conservation and ecosystem restoration frameworks. Full article

Amphibians are particularly vulnerable to hydric stress due to their permeable skin, biphasic life cycle, and strong dependence on aquatic and moist terrestrial environments. In the Northwestern Mediterranean Basin—one of Europe’s most climate-sensitive regions—the intensification of droughts associated with climate change poses a critical threat to amphibian populations. Increased aridification, either due to higher temperatures or to more frequent, prolonged, and severe drought episodes, can affect both aquatic and terrestrial life stages, directly altering breeding opportunities, larval development, post-metamorphic survival, and dispersal capacity. This review aims to gather and synthesize current knowledge on the ecological, physiological, and demographic impacts of drought on amphibians of the Northwestern Mediterranean across habitat types, including ephemeral ponds, permanent water bodies, lotic systems, and terrestrial landscapes, including a final section on possible mitigation actions. Drought-induced shifts in hydroperiod can drastically reduce reproductive success and accelerate larval development with fitness consequences while, on land, desiccation risk and habitat degradation could limit access to refugia and fragment populations by reducing structural connectivity. These environmental constraints are compounded by the interactions between drought and emerging infectious diseases. We discuss the current knowledge on how chytrid fungi (Batrachochytrium dendrobatidis and B. salamandrivorans) and ranaviruses may respond to temperature and moisture regimes, and how drought may affect their transmission dynamics, host susceptibility, and pathogen persistence. In these cases, microbiome disruption, pollutant concentration, and increased contact rates between species may amplify disease outbreaks under dry conditions, but a better understanding of the multifactorial effects of drought on amphibian biology and disease ecology is needed for predicting species vulnerability, identifying high-risk populations, and guiding future conservation and management strategies in Mediterranean environments. Full article

Forest ginseng (FG) is a rare medicinal and culinary plant in China, and its drying quality is heavily dependent on the drying method. This study investigated the effects of traditional hot air drying (HAD) and the self-developed negative-pressure circulating airflow-assisted desiccator drying (PCAD) method on the quality of FG using metabolomics and enzyme activity. The results revealed that the enzyme activities of dried FG were reduced considerably. PCAD preserved higher enzyme activity than HAD. Metabolomics data demonstrate that HAD promotes the formation of primary metabolites (amino acids, lipids, nucleotides, etc.), whereas PCAD promotes the formation of secondary metabolites (terpenoids, phenolic acids, etc.). A change-transformation network was built by combining the metabolites listed above and their biosynthetic pathways, and it was discovered that these biosynthetic pathways were primarily associated with the mevalonate (MVA) pathway, lipid metabolism, phenylpropane biosynthesis, and nucleotide metabolism. It is also believed that these findings are related to the chemical stimulation induced by thermal degradation and the ongoing catalysis of enzyme responses to drought stress. The facts presented above will give a scientific basis for the selection of FG drying processes, as well as helpful references for increasing the nutritional quality of processed FG. Full article

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