Nutrient-deficient Environments Research Articles

Continuous solutions for a two-dimensional cross-diffusion problem involving doubly degenerate diffusion and logistic proliferation

Emerging from the modeling of intricate structures formed by bacterial motion in nutrient-deficient environments, the doubly degenerate nutrient taxis system [Formula: see text] is considered in smoothly bounded domains [Formula: see text]. In contrast to frameworks devoid of logistic growth where only small-data global solutions have so far been found in the literature, quadratic degradation in the logistic growth is shown to markedly amplify the overall dissipative effects to the extent that, for arbitrary smooth initial data, an associated no-flux type initial-boundary problem possesses global continuous weak solutions. Central to our findings is the identification of an advantageous dissipative structure subtly embedded in the system, the exploitation of which leads to the establishment of a positive lower bound for nutrients levels within any finite time interval, thereby ruling out the appearance of cross-degeneracies within such timeframes.

"Exploring therapeutic potential and toxicological profiles of Cuscuta species: insights from pharmacological studies and an anti-cholinergic toxicity report."

This study examines the therapeutic potential and toxicological profiles of Cuscuta species based on recent pharmacological investigations: "a therapeutic potential vs. toxicological risks of Cuscuta species: a pharmacological-toxicology dilemma." The study encompasses diverse research areas, including the mitigation of Bisphenol A (BPA)-induced ovarian damage using Cuscuta chinensis flavonoids (CCFs), acute and sub-acute toxicity assessments of Cuscuta chinensis Lam. water extract (CLW), and observations on Cuscuta campestris toxicity in horses. In addition, this scientific study discusses the interplant communication dynamics between soybean and the parasitic dodder (Cuscuta australis) under nutrient deficiency conditions. Key significant findings highlight the efficacy of CCFs in alleviating BPA-induced ovarian damage, the safety profile of CLW within specified doses, and clinical manifestations of C. campestris toxicity in horses. Moreover, insights into interplant communication mechanisms emphasise the significance of protein-mediated interactions in nutrient-deficient environments. The report illustrates the potential toxicity of Dodder in humans, and further research findings into its chemical composition and toxicological profiles reveal great data on its phytotoxicity. Greater awareness and understanding of the risks associated with consuming Dodder and other similar plant species are crucial for preventing plant intoxication and have been a significant major focus of the present toxicology study of Cuscuta species. Hence, by addressing these objectives, the scientific study aims to balance the therapeutic benefits of Cuscuta species with their potential toxicological risks, contributing to a more nuanced understanding of their role in pharmacology and toxicology. This dual focus is crucial for guiding future research and informing safe usage practices.

Hyaluronan-based hydrogel delivering glucose to mesenchymal stem cells intended to treat osteoarthritis

Mesenchymal stem cell (MSC) therapy shows promise in regenerative medicine. For osteoarthritis (OA), MSCs delivered to the joint have a temporal window in which they can secrete growth factors and extracellular matrix molecules, contributing to cartilage regeneration and cell proliferation. However, upon injection in the non-vascularized joint, MSCs lacking energy supply, starve and die too quickly to efficiently deliver enough of these factors. To feed injected MSCs, we developed a hyaluronic acid (HA) derivative, where glucose is covalently bound to hyaluronic acid. To achieve this, the glucose moiety in 4-aminophenyl-β-D-glucopyranoside was linked to the HA backbone through amidation. The hydrogel was able to deliver glucose in a controlled manner using a trigger system based on hydrolysis catalyzed by endogenous ß-glucosidase. This led to glucose release from the hyaluronic acid backbone inside the cell. Indeed, our hydrogel proved to rescue starvation and cell mortality in a glucose-free medium. Our approach of adding a nutrient to the polymer backbone in hydrogels opens new avenues to deliver stem cells in poorly vascularized, nutrient-deficient environments, such as osteoarthritic joints, and for other regenerative therapies.

Abstract 5729: ADCK1 inhibition alters cell proliferation and cell cycle progression in liver cancer cells

Abstract In 2020, there were over 830,000 reported liver cancer deaths. Incidence rates of liver cancer have tripled, and death rates have doubled since the 1980s; giving this disease one of the highest mortality rates when compared to its incidence rate. Hepatocellular carcinoma (HCC) is derived from hepatocytes and is the main type of liver cancer in adults, accounting for 75-85% of all primary liver cancers. Current treatment options for HCC like radiation therapy and chemotherapy are imperfect and cause significant side effects. Tumorigenesis is dependent on an organism’s cellular metabolism. Metabolic reprogramming is a promising area of focus for cancer therapeutics. Cancer cells thrive in nutrient-deficient environments by hijacking and reprogramming the cells existing cellular metabolism. Metabolic reprogramming is driven by genetic alterations and environmental cues. AarF Domain Containing Kinase 1 (ADCK1) is a protein-coding gene that acts as a mitochondrial protein with putative kinase activity. The role of ADCK1 has not been well studied, particularly in liver cancer. Our group has sought to study how ADCK1 impacts the metabolism and cellular environment of HCC cells to help establish a more effective drug target. Bioinformatics performed by our lab report that ADCK1 was highly expressed in HCC tumor cells. The expression levels of ADCK1 were also correlated with a decrease in patient survival. ADCK1 knockout clones were generated; these knockout cells showed decreased proliferation and altered cell cycle progression. Proteomics analysis demonstrated that loss of ADCK1 was also seen to alter the expression of proteins involved in several cellular processes related to the cell cycle and cellular metabolism. How ADCK1 regulates these processes will be studied in the future. Citation Format: Noel A. Jacquet, Yunfeng Zhao. ADCK1 inhibition alters cell proliferation and cell cycle progression in liver cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5729.

Soil nutrient conditions alter viral lifestyle strategy and potential function in phosphorous and nitrogen metabolisms

As one of the most abundant members of microbial communities, viruses are considered to influence prokaryotic mortality and biogeochemical cycles. While extensive research has been conducted to explore viral diversity and community dynamics in marine ecosystems, our understanding of soil viruses, particularly within agroecosystems, remains limited. Here, we conducted metagenomics and viromics analyses in a paddy ecosystem subjected to four different levels of soil nutrient modification by pig manure applications (PM0: 0 kg ha−1, PM1: 1930 kg ha−1, PM2: 3860 kg ha−1 and PM3: 5790 kg ha−1) over a period of 9 years. We aimed to investigate viral community adaptation and virus-host interactions in response to varying soil nutrient conditions. Our findings revealed that the viral communities are more adaptable to changes in soil nutrient contents compared to prokaryotic communities. Specifically, the relative abundance of Caudoviricetes decreased significantly with increasing levels of soil available phosphorus and total nitrogen. The ratio of lytic-lysogenic cycles increased with higher manure application rates, accompanied by an elevated prevalence of functional genes related to cell processes and viral protein structure. Moreover, we identified several putative auxiliary metabolic genes (AMGs) associated with phosphorus and nitrogen cycles, including phoA, phoH, phoB, and gdh, with the first discovery of phoB and gdh as soil viral-encoded AMG. Notably, the association between viruses and phoB-encoding bacteria displayed greater similarity within nutrient-deficient environments compared to nutrient-enriched environments, while the converse interaction pattern emerged between viruses and gdh-encoding bacteria. Collectively, our study highlights the importance of soil nutrient conditions in driving the transition between lytic-lysogenic cycles, as well as the interaction patterns between viruses and key bacteria. The insights gleaned from our findings significantly enrich our understanding of viral ecology within agricultural ecosystems.

Nutrient Deficiencies Impact on the Cellular and Metabolic Responses of Saxitoxin Producing Alexandrium minutum: A Transcriptomic Perspective.

Dinoflagellate Alexandrium minutum Halim is commonly associated with harmful algal blooms (HABs) in tropical marine waters due to its saxitoxin production. However, limited information is available regarding the cellular and metabolic changes of A. minutum in nutrient-deficient environments. To fill this gap, our study aimed to investigate the transcriptomic responses of A. minutum under nitrogen and phosphorus deficiency. The induction of nitrogen and phosphorus deficiency resulted in the identification of 1049 and 763 differently expressed genes (DEGs), respectively. Further analysis using gene set enrichment analysis (GSEA) revealed 702 and 1251 enriched gene ontology (GO) terms associated with nitrogen and phosphorus deficiency, respectively. Our results indicate that in laboratory cultures, nitrogen deficiency primarily affects meiosis, carbohydrate catabolism, ammonium assimilation, ion homeostasis, and protein kinase activity. On the other hand, phosphorus deficiency primarily affects the carbon metabolic response, cellular ion transfer, actin-dependent cell movement, signalling pathways, and protein recycling. Our study provides valuable insights into biological processes and genes regulating A. minutum's response to nutrient deficiencies, furthering our understanding of the ecophysiological response of HABs to environmental change.

The potential role of subseafloor fungi in driving the biogeochemical cycle of nitrogen under anaerobic conditions

Fungi represent the dominant eukaryotic group of organisms in anoxic marine sedimentary ecosystems, ranging from a few centimeters to ~ 2.5 km below seafloor. However, little is known about how fungi can colonize anaerobic subseafloor environments for tens of millions of years and whether they play a role in elemental biogeochemical cycles. Based on metabolite detection, isotope tracer and gene analysis, we examined the anaerobic nitrogen conversion pathways of 19 fungal species (40 strains) isolated from1.3 to 2.5 km coal-bearing sediments below seafloor. Our results show for the first time that almost all fungi possess anaerobic denitrification, dissimilatory nitrate reduction to ammonium (DNRA), and nitrification pathways, but not anaerobic ammonium oxidation (anammox). Moreover, the distribution of fungi with different nitrogen-conversion abilities in subseafloor sediments was mainly determined by in situ temperature, CaCO3, and inorganic carbon contents. These findings suggest that fungi have multiple nitrogen transformation processes to cope with their requirements for a variety of nitrogen sources in nutrient deficient anaerobic subseafloor sedimentary environments.

Heterogeneous nutrient supply modulates root exudation and accumulation of medicinally valuable compounds in Artemisia annua and Hypericum perforatum.

Plants have evolved complex mechanisms to adapt to nutrient-deficient environments, including stimulating lateral root proliferation into local soil patches with high nutrient content in response to heterogeneous nutrient distribution. Despite the widespread occurrence of this phenomenon in soil, the effect of heterogeneous nutrient distribution on the accumulation of secondary compounds in plant biomass and their exudation by roots remains largely unknown. This study aims to fill this critical knowledge gap by investigating how deficiency and unequal distributions of nitrogen (N), phosphorus (P), and iron (Fe) affect plant growth and accumulation of the antimalarial drug artemisinin (AN) in leaves and roots of Artemisia annua, as well as AN exudation by roots. Heterogeneous N and P supplies strongly increased root exudation of AN in half of a split-root system exposed to nutrient deficiency. By contrast, exposure to a homogeneous nitrate and phosphate deficiency did not modulate root exudation of AN. This indicates that a combination of local and systemic signals, reflecting low and high nutritional statuses, respectively, were required to enhance AN exudation. This exudation response was independent of the regulation of root hair formation, which was predominantly modulated by the local signal. In contrast to the heterogeneous supply of N and P, heterogeneous Fe supply did not modulate AN root exudation but increased AN accumulation in locally Fe-deficient roots. No modulation of nutrient supply significantly changed the accumulation of AN in A. annua leaves. The impact of a heterogeneous nitrate supply on growth and phytochemical composition was also investigated in Hypericum perforatum plants. Unlike in A. annue, the uneven N supply did not significantly influence the exudation of secondary compounds in the roots of H. perforatum. However, it did enhance the accumulation of several biologically active compounds, such as hypericin, catechin, and rutin isomers, in the leaves of H. perforatum. We propose that the capacity of plants to induce the accumulation and/or differential exudation of secondary compounds under heterogeneous nutrient supply is both species- and compound-specific. The ability to differentially exude AN may contribute to A. annua's adaptation to nutrient disturbances and modulate allelopathic and symbiotic interactions in the rhizosphere.

Geomyces Species (LC374638), a Fungal Endophyte, Promotes the Growth of Honeysuckle (Lonicera caerulea) through Symbiosis

Honeysuckle (Lonicera caerulea), also known as "haskap" in Japan, is a shrub that produces edible berries and inhabits mountainous and wetland areas with harsh environments. In this study, we surveyed the relationship between honeysuckle and the root endophytic fungi. Root samples were collected from the wet land region in Hokkaido, Japan, and subjected to microscopic observation and fungal strain isolation. Totally 47 endophytic fungal strains were isolated from the roots. Inoculation tests showed that a strain of Geomyces sp. promotes the growth of the seedlings and colonizes the epidermal and cortical cells of roots. It suggested that the strain acts as a mycorrhiza-like fungus for the arbuscular mycorrhizal plant. We speculate that honeysuckle establishes a symbiotic relationship with endophytic fungi to overcome acidic and nutrient-deficient environments. This is the first report demonstrating that endophytic ascomycetes promote the growth of host plants belonging to the Caprifoliaceae family.

Festuca coelestis Increases Drought Tolerance and Nitrogen Use via Nutrient Supply-Demand Relationship on the Qinghai-Tibet Plateau.

Drought and nutrient deficiency pose great challenges to the successful establishment of native plants on the Qinghai-Tibet Plateau. The dominant factors and strategies that affect the adaptation of alpine herbs to dry and nutrient-deficient environments remain unclear. Three water gradients were established using two-factor controlled experiments: low water (WL), medium water (WM), and high water (WH). The field water-holding capacities were 35%, 55%, and 75%, respectively. Nitrogen fertilizer (N) was applied at four levels: control (CK), low (FL), medium (FM), and high (FH) at 0, 110, 330, and 540 mg/kg, respectively. The results revealed that N was the main limiting factor, rather than phosphorous (P), in Festuca coelestis under drought stress. Under water shortage conditions, F. coelestis accumulated more proline and non-structural carbohydrates, especially in the aboveground parts of the leaves and stems; however, the root diameter and aboveground nitrogen use efficiency were reduced. Appropriate N addition could mitigate the adverse effects by increasing the release of N, P, and enzyme activity in the bulk soil and rhizosphere to balance their ratio, and was mainly transferred to the aboveground parts, which optimized the supply uptake relationship. The effects of water and fertilizer on the physiological adaptability and nutrient utilization of F. coelestis were verified using structural equation modeling. Based on their different sensitivities to water and nitrogen, the WHFM treatment was more suitable for F. coelestis establishment. Our results demonstrated that the disproportionate nutrient supply ability and preferential supply aboveground compared to below ground were the main factors influencing F. coelestis seedling establishment under drought conditions. This study provides evidence for a better understanding of herbaceous plants living in high mountain regions and offers important information for reducing the risk of ecological restoration failure in similar alpine regions.

Inherent tendency of Synechococcus and heterotrophic bacteria for mutualism on long-term coexistence despite environmental interference.

Mutualism between Synechococcus and heterotrophic bacteria has been found to support their prolonged survival in nutrient-depleted conditions. However, environmental interference on the fate of their mutualism is not understood. Here, we show that exogenous nutrients disrupt their established mutualism. Once the exogenous nutrients were exhausted, Synechococcus and heterotrophic bacteria gradually reestablished their metabolic mutualism during 450 days of culture, which revived unhealthy Synechococcus cells. Using metagenomics, metatranscriptomics, and the 15N tracer method, we reveal that the associated bacterial nitrogen fixation triggered the reestablishment of the mutualism and revival of Synechococcus health. During this process, bacterial community structure and functions underwent tremendous adjustments to achieve the driving effect, and a cogeneration of nitrogen, phosphorus, iron, and vitamin by the heterotrophic bacteria sustained Synechococcus’s prolonged healthy growth. Our findings suggest that Synechococcus and heterotrophic bacteria may have an inherent tendency toward mutualism despite environmental interference. This may exhibit their coevolutionary adaptations in nutrient-deficient environments.

The Role and Therapeutic Potential of Macropinocytosis in Cancer.

Macropinocytosis, a unique endocytosis pathway characterized by nonspecific internalization, has a vital role in the uptake of extracellular substances and antigen presentation. It is known to have dual effects on cancer cells, depending on cancer type and certain microenvironmental conditions. It helps cancer cells survive in nutrient-deficient environments, enhances resistance to anticancer drugs, and promotes invasion and metastasis. Conversely, overexpression of the RAS gene alongside drug treatment can lead to methuosis, a novel mode of cell death. The survival and proliferation of cancer cells is closely related to macropinocytosis in the tumor microenvironment (TME), but identifying how these cells interface with the TME is crucial for creating drugs that can limit cancer progression and metastasis. Substantial progress has been made in recent years on designing anticancer therapies that utilize the effects of macropinocytosis. Both the induction and inhibition of macropinocytosis are useful strategies for combating cancer cells. This article systematically reviews the general mechanisms of macropinocytosis, its specific functions in tumor cells, its occurrence in nontumor cells in the TME, and its application in tumor therapies. The aim is to elucidate the role and therapeutic potential of macropinocytosis in cancer treatment.

Inter-specific competition between finger millet and Guinea grass for growth and nutrient uptake under nutrient-limited conditions

ABSTRACT Crop–weed interactions in nutrient-deficient environments can induce strong intra- and inter-specific competition for such nutrients. The study investigated nutrient uptake by finger millet (FM; Eleusine coracana (L.) Gaertn.) in the presence of the upland weed, Guinea grass (GG; Panicum maximum Jacq), under nutrient-limited conditions. A pot experiment was conducted with different neighbor-densities of the two species, including monocultures and mixed cultures. The effects of inter-specific/intra-specific competition on nutrient uptake and growth of the two plant species were measured. Varied plant combinations impacted on plant dry weight, uptake, and use efficiency of nitrogen, phosphorus, and potassium by FM. Root and shoot dry weights of FM were markedly reduced in the presence of GG compared to that when neighbors were from the same species. The largest reduction of tissue nutrient concentration of FM was recorded in FM:GG plant combination of 1:2. The results indicated that the growth and nutrient uptake of FM was suppressed when it co-existed with GG due to strong inter-specific competition under nutrient-limited conditions. GG maintained similar biomass irrespective of the fertilizer treatment and plant combinations, demonstrating its ability to outcompete neighboring species when resources are limited in the growing environment. The present study also provides scientific evidence that GG is well adapted to nutrient-poor environments, which is attained through enhancing the use efficiency of limited nutrients in biomass formation. This might have helped GG to gain the competitive advantage over other plants in the same habitat and dominate in most agro-ecological systems as an invasive weed species.

Unraveling and targeting RAS-driven metabolic signaling for therapeutic gain.

RAS mutations are among the most frequent oncogenic drivers observed in human cancers. With a lack of available treatment options, RAS-mutant cancers account for many of the deadliest cancers in the United States. Recent studies established that altered metabolic requirements are a hallmark of cancer, and many of these alterations are driven by aberrant RAS signaling. Specifically, RAS-driven cancers are characterized by upregulated glycolysis, the differential channeling of glycolytic intermediates, upregulated nutrient scavenging pathways such as autophagy and macropinocytosis, and altered glutamine utilization and mitochondrial function. This unique metabolic landscape promotes tumorigenesis, proliferation, survival in nutrient deficient environments and confers resistance to conventional cytotoxic and targeted therapies. Emerging work demonstrates how these dependencies can be therapeutically exploited in vitro and in vivo with many metabolic inhibitors currently in clinical trials. This review aims to outline the unique metabolic requirements induced by aberrant RAS signaling and how these altered dependencies present opportunities for therapeutic intervention.

Genotypic and Phenotypic Characterization of Highly Alkaline-Resistant Carnobacterium maltaromaticum V-Type ATPase from the Dairy Product Based on Comparative Genomics.

Although Carnobacterium maltaromaticum derived from dairy products has been used as a lactic acid bacterium industrially, several studies have reported potential pathogenicity and disease outbreaks. Because strains derived from diseased fish and dairy products are considered potentially virulent and beneficial, respectively, their genotypic and phenotypic characteristics have attracted considerable attention. A genome-wide comparison of 30 genome sequences (13, 3, and 14 strains from diseased aquatic animals, dairy products, and processed food, respectively) was carried out. Additionally, one dairy and two nondairy strains were incubated in nutrient-rich (diluted liquid media) and nutrient-deficient environments (PBS) at pH 10 to compare their alkaline resistance in accordance with different nutritional environments by measuring their optical density and viable bacterial cell counts. Interestingly, only dairy strains carried 11 shared accessory genes, and 8 genes were strongly involved in the V-type ATPase gene cluster. Given that V-type ATPase contributes to resistance to alkaline pH and salts using proton motive force generated via sodium translocation across the membrane, C. maltaromaticum with a V-type ATPase might use nutrients in food under high pH. Indeed, the dairy strain carrying the V-type ATPase exhibited the highest alkaline resistance only in the nutrient-rich environment with significant upregulation of V-type ATPase expression. These results suggest that the gene cluster of V-type ATPase and increased alkaline resistance of dairy strains facilitate adaptation in the long-term ripening of alkaline dairy products.

Identifying genome level variation in generalist and specialist bacteria and their relationship to abiotic conditions in European freshwater ecosystems

Microbial biodiversity is one of the increasingly studied fields, yet we are unable to accurately pinpoint the intricacies of how the biotic landscape changes with its abiotic counterpart. Every organism reacts differently to physical changes in its surrounding(Zeglin (2015)). While there are some generalist microbes that can grow in limited capacity in many different types of environment, there are also some specialists that can flourish in very specific environments(Monard et al. (2016)). We hypothesize that both generalists and specialists have developed advanced strategies that allow them thrive under diverse conditions or in very specific niches, and that these changes should be traceable on the genomic level. We expect to see variations in factors like genome sizes, number of genes, GC content, metabolic pathways that yield growth and replication advantages in nutrient deficient niches and defense mechanisms. We also expect to identify genomic streamlining in organisms that survive in nutrient deficient environments. We are currently studying the genetic basis of why these generalists are so universally present though in smaller numbers, and what allows the specialists to efficiently exploit the abiotic factors of their specific environment in order to flourish. To pursue this, we have sampled and sequenced metagenomes from 47 lakes spread across Europe with strongly diverging environmental conditions such as pH, temperature, organic and nutrient content, elevation, and conductivity. We’ve identified reads from more than 9000 taxonomically unique organisms, of which 700 were identified as generalists and 1200 as specialists, based on niche width permutations. In total we have assembled 313 high quality Metagenome Assembled Genomes (MAGs). Which now allow us to get a more detailed insight into the genetic basis and specific adaptations of these organisms.

Succession mechanism of microbial community with high species diversity in nutrient-deficient environments with low-dose ionizing radiation

It remains a mystery why microbial community succession can violate the competitive exclusion principle to form high species diversity in nutrient-deficient environments (NDE) with low-dose ionizing radiation (LDIR). In this research, artificial microbial communities containing three common strains downloaded from China Tiangong-1 space station were cultivated in NDE with and without LDIR, respectively. By comparing their identities and differences in cellular phenotype, extracellular pH, intracellular triglycerides and population dynamics under the two circumstances, a new hypothesis was put forward from observed phenomena and experimental data to expound new interspecific relationships and interactions induced by LDIR to produce new dynamic mechanisms to drive microbial community succession with high species diversity. A set of highly valid kinetic models was then developed from this hypothesis, and finally, the hypothesis proposed was verified through a large number of digital simulations. The results show that induced by LDIR, specific feedback regulation of microbial populations by mutual promotion and restraint mechanisms might exist in microbial communities, which can cause asynchronous convergent fluctuations of microbial populations. These fluctuations remarkably alleviate interspecific competition and inhibit the emergence of dominant species, leading to the formation and maintenance of higher species diversity. The results can provide a theoretical basis for understanding the ecological effect of LDIR on microbial communities in NDE as well as its application for ecological engineering purposes.

Identification of lipid biomarkers of metastatic potential and gene expression (HER2/p53) in human breast cancer cell cultures using ambient mass spectrometry.

In breast cancer, overexpression of human epidermal growth factor receptor 2 (HER2) correlates with overactivation of lipogenesis, mutation of tumor suppressor p53, and increased metastatic potential. The mechanisms through which lipids mediate p53, HER2, and metastatic potential are largely unknown. We havedeveloped a desorption electrospray ionization mass spectrometry (DESI-MS) method to identify lipid biomarkers of HER2/p53 expression, metastatic potential, and disease state (viz. cancer vs. non-cancerous) in monolayer and suspension breast cancer cell cultures (metastatic potential: MCF-7, T-47D, MDA-MB-231; HER2/p53: HCC2218 (HER2+++/p53+), HCC1599 (HER2-/p53-), HCC202 (HER2++/p53-), HCC1419 (HER2+++/p53-) HCC70 (HER2-/p53+++); non-cancerous: MCF-10A). Unsupervised principal component analysis(PCA) of DESI-MS spectra enabled identification of twelve lipid biomarkers of metastatic potential and disease state, as well as ten lipids that distinguish cell lines based on HER2/p53 expression levels (> 200 lipids were identified per cell line). In addition, we developed a DESI-MS imaging (DESI-MSI) method for mapping the spatial distribution of lipids in metastatic spheroids (MDA-MB-231). Of the twelve lipids that correlate with changes in themetastatic potentialof monolayercell cultures, three were localized to the necrotic coreof spheroids, indicating a potential role in promoting cancer cell survival in nutrient-deficient environments. One lipid species, which was not detected in monolayer MDA-MB-231 cultures, was spatially localized to the periphery of the spheroid, suggesting a potential role in invasion and/or proliferation. These results demonstrate thatcombiningDESI-MS/PCA of monolayer and suspension cell cultures with DESI-MSI of spheroids isa promising approach for identifying lipid biomarkers of specific genotypes and phenotypes, as well as elucidating the potential functionof these biomarkers in breast cancer. Graphical Absract.

Comprehensive Analysis of Zinc Derivatives Pro-proliferative, Anti-Apoptotic and Antimicrobial Effect on Human Fibroblasts and Keratinocytes in a Simulated, Nutrient-deficient Environment In Vitro.

Zinc as therapeutic agent in skin and wound care has been known for centuries, but its role is controversial and comprehensive investigations in nutrient-deficient environments are lacking. We aimed to provide a broad analysis of different zinc derivatives on proliferation, apoptosis and antimicrobial properties in a simulated nutrient-deficient environment in vitro. Human fibroblasts (CRL2522) and keratinocytes (HaCaT) were treated with a broad concentration range (10 – 0.0001 µg/mL) of zinc-sulfate (ZnSO4), -gluconate (ZnGluc) and -histidine (ZnHis) for 1-6 days under nutrient-deficient media conditions. Cell proliferation was investigated by XTT assay. Targeted analyzes in proliferation (E2F1, PCNA) and apoptosis (TP53) associated genes were performed via qRT-PCR and apoptosis was determined via FACS (annexin V/7-AAD staining). Antimicrobial efficacy was investigated using a quantitative suspension method against S. aureus, P. aeruginosa, E. coli, and C. albicans. The results indicated that 0.1 to 0.001 µg/mL Zn increased cell proliferation in both cell lines. Fibroblasts were more susceptible with significant proliferation peaks on days 2 & 6, and days 1 & 4 for keratinocytes. No relevant changes in gene expression were detected for E2F1 and PCNA nor for TP53. Annexin-V/7-AAD-staining of fibroblasts revealed a small, yet insignificant reduction of apoptosis induction for ZnGluc and ZnSO4. ZnGluc and ZnSO4 (0.1%) achieved high microbial reductions (4-5 log10 reductions) against tested pathogens. ZnGluc and ZnSO4 showed relevant pro-proliferative and antimicrobial, as well as tendential anti-apoptotic features in a simulated nutrient-deficient microenvironment in vitro. This further validates a potential benefit of local zinc treatment in deficient wound microenvironments.

A consortium of non-rhizobial endophytic microbes from Typha angustifolia functions as probiotic in rice and improves nitrogen metabolism.

Endophytic microbes isolated from plants growing in nutrient-deficient environments often possess properties that improve nutrition of agriculturally important plants. A consortium of non-rhizobial endophytic microbes isolated from a macrophyte Typha angustifolia growing in the marginal wetlands associated with a Uranium mine was characterized for their beneficial effect on rice and the mechanisms of growth promotion were investigated. The microbes were identified and characterized for their potential plant growth promoting (PGP) properties. Effect of these microbes on nitrogen (N)-metabolism of rice was tested as Typha endophytes were predominantly (N)-fixing. Relative N-use efficiency and expression of genes involved in N-uptake and assimilation were investigated in treated plants. Evidence of horizontal gene transfer (HGT) of dinitrogen reductase gene was observed within the consortium from a Pseudomonas stutzeri strain. The consortium behaved as plant probiotic and showed substantial growth benefits to Typha, their natural host as well as to rice. Typha endophytes colonized rice endosphere significantly increasing biomass, shoot length and chlorophyll content in rice plants both under N-sufficient and N-deficient conditions. N-uptake and assimilation genes were upregulated in plants treated with the endophytes even after three weeks post infection. Our results suggested, HGT of nitrogen-fixation trait to be highly prevalent among endophytes isolated from nutrient-poor habitats of the uranium mine. A long-term nitrogen deficiency response in the treated plants was elicited by the consortium improving N-uptake, assimilation and relative N-use efficiency of rice plants. This appeared to be at least one of the main strategies of plant growth promotion.