Search Results (43)

Interest in the subject of umbilical cord clamping is long-standing. New evidence reveals that placental transfusion, facilitated by delayed cord clamping (DCC), reduces death and need for blood transfusions for preterm infants without evidence of harm. Even a brief delay in clamping the cord shows improved survival and well-being, but waiting at least two minutes is even better. We propose that three major benefits from DCC contribute to reduced mortality of preterm infants: (1) benefits from the components of blood; (2) assistance from the continued circulation of blood; and (3) the essential mechanical interactions that result from the enhanced volume of blood. The enhanced blood volume generates mechanical forces within the microcirculation that support the newborn’s metabolic and cardiovascular stability and secure short- and long-term organ health. Several unique processes prime preterm and term newborns to receive the full placental transfusion, not to be misinterpreted as extra blood or over-transfusion. Disrupting cord circulation before the newborn’s lung capillary bed has been fully recruited and the lungs can replace the placenta as a respiratory, gas-exchanging organ may be harmful. Early cord clamping also denies the newborn a full quota of iron-rich red blood cells as well as valuable stem cells for regeneration, repair, and seeding of a strong immune system. We propose that delayed cord clamping and intact-cord stabilization have the potential to save lives by protecting many neonates from hypovolemia, inflammation, and ischemia. Full article

Harmful algal blooms (HABs) formed by toxic microalgae have seriously threatened marine ecosystems and food safety and security in recent years. Among them, Karenia selliformis has attracted the attention of scientists and society due to its acute and rapid neurotoxicity in mice. Herein, the growth and gymnodimine A (GYM-A) production of K. selliformis were investigated in diverse culture systems with different surface-to-volume (S/V) ratios and nitrogen/phosphorus concentrations. The results showed that the specific growth rates (μ), maximal cell yields, and GYM-A production levels of K. selliformis increased with higher S/V, but no significant differences were observed under different culture volumes with the same S/V, which indicated that light penetration and gas exchange in the seawater culture systems actually influenced the growth and GYM-A production of K. selliformis. The maximum cell density and photosynthetic efficiency of K. selliformis decreased under nitrogen (N) and phosphorus (P) deficiency, suggesting that the growth of K. selliformis was significantly inhibited by the deficiency in N or P. Both N and P limitation conditions, especially P deficiency, promoted the cellular GYM-A quotas of K. selliformis. In this study, a scientific basis is provided for understanding the effects of culture systems and nutrient concentrations on the growth and toxin production of K. selliformis. Full article

Dinoflagellate species that form some of the most frequent toxic blooms are also bioluminescent, yet the two traits are rarely linked when studying bloom development and persistence. P. bahamense is a toxic, bioluminescent dinoflagellate that previously bloomed in Florida with no known record of saxitoxin (STX) production. Over the past 20 years, STX was identified in P. bahamense populations. The goal of this study was to examine toxin dynamics and associated molecular mechanisms in spatially and temporally distinct P. bahamense populations from the Indian River Lagoon, FL. SxtA4 is a key gene required for toxin biosynthesis. SxtA4 genotype analysis was performed on individual cells from multiple sites. Cell abundance, toxin quota cell⁻¹, and sxtA4 and RubisCo (rbcL) transcript abundance were also measured. There was a significant negative correlation between cell abundance and toxin quota cell⁻¹. While the sxtA4+ genotype was dominant at all sites, its frequency varied, but it occurred at 90–100% in many samples. The underlying mechanism for toxin decrease with increased cell abundance remains unknown. However, a strong, statistically significant negative correlation was found between stxA4 transcripts and the sxtA4/rbcL ratio, suggesting cells make fewer sxtA4 transcripts as a bloom progresses. However, the influence of sxtA4− cells must also be considered. Future plans include bioluminescence measurements, normalized to a per cell basis, at sites when toxicity is measured along with concomitant quantification of sxtA4 gene and transcript copy numbers as a means to elucidate whether changes in bloom toxicity are driven more at the genetic (emergence of sxtA4− cells) or transcriptional (repression of sxtA4 in sxtA4+ cells) level. Based on the results of this study, a model is proposed that links the combined traits of toxicity and bioluminescence in P. bahamense bloom development. Full article

This study aimed to test the hypothesis of the year-round presence of toxigenic Microcystis and cyanotoxins in the water and ice of the shallow eutrophic Lake Ytyk-Kyuyol located in the continuous permafrost zone. Three independent approaches—mass-spectrometry, molecular methods and light microscopy—were applied in the study. The cyanobacterial biomass ranged from 1.0 × 10⁻⁴ to 4.8 mg L⁻¹. Microcystis flos-aquae and M. aeruginosa were the dominant morphospecies in plankton throughout the observation. In environmental DNA, the presence of M. aeruginosa was supported and mcy gene regions responsible for microcystin biosynthesis were detected through a BLAST (Basic Local Alignment Search Tool) search and phylogenetic estimation based on newly obtained 16S rRNA, 16S–23S ITS rRNA, mcyA and mcyE nucleotide sequences. The intracellular microcystin concentration ranged from <0.1 to 803 ng L⁻¹, and the microcystin quota in the Microcystis biomass was extremely low. For the first time, it was shown that Microcystis cells containing mcy genes and microcystins presented permanently in the water column, both during the ice-free period and under ice, as well as inside thick ice covers within 7 months of severe winter. We hypothesized that minor pelagic and ice populations of Microcystis could participate in increasing cell density in the spring. However, further studies are needed to confirm the viability of the overwintering Microcystis colonies in the water and inside the ice of Lake Ytyk-Kyuyol. Full article

The world’s human population is increasing as is the demand for new sustainable sources of energy. Accordingly, microalgae-based carbohydrates for biofuel production are being considered as an alternative source of raw materials for producing biofuels. Microalgae grow in photobioreactors under constantly changing conditions. Models improve our understanding of microalgae growth. In this paper, a photoacclimated model for continuous microalgae cultures in photobioreactors was used to study the time-varying behavior and sensitivity of solutions under optimal productivity conditions. From the perspective of dynamic simulation in this work, light intensity was found to play an influential role in modifying metabolic pathways as a cell stressor. Enhancing carbohydrate productivity by combining nutritional deficiency and light intensity regulation modeling strategies could be helpful to optimize the process for the highest yield in large-scale cultivation systems. Under the proposed simulation conditions, a maximum carbohydrate productivity of 48.11 gCm${}^{-3}$d${}^{-1}$ was achieved using an optimal dilution rate of 0.2625 d${}^{-1}$ and 350 $\mathsf{\mu }$molm${}^{-2}$s${}^{-1}$ of light intensity. However, it is important to note that, a particular set of manipulated inputs can generate multiple outputs at a steady state. A numerical solution of the sensitivity functions indicated that the model outputs were especially sensitive to changes in parameters corresponding to a minimum nitrogen quota, maximum nitrogen intake rate, dilution rate, and maximum nitrogen quota compared to to other model parameters. Full article

The successful cultivation of Dinophysis norvegica Claparède & Lachmann, 1859, isolated from Japanese coastal waters, is presented in this study, which also includes an examination of its toxin content and production for the first time. Maintaining the strains at a high abundance (>2000 cells per mL⁻¹) for more than 20 months was achieved by feeding them with the ciliate Mesodinium rubrum Lohmann, 1908, along with the addition of the cryptophyte Teleaulax amphioxeia (W.Conrad) D.R.A.Hill, 1992. Toxin production was examined using seven established strains. At the end of the one-month incubation period, the total amounts of pectenotoxin-2 (PTX2) and dinophysistoxin-1 (DTX1) ranged between 132.0 and 375.0 ng per mL⁻¹ (n = 7), and 0.7 and 3.6 ng per mL⁻¹ (n = 3), respectively. Furthermore, only one strain was found to contain a trace level of okadaic acid (OA). Similarly, the cell quota of pectenotoxin-2 (PTX2) and dinophysistoxin-1 (DTX1) ranged from 60.6 to 152.4 pg per cell⁻¹ (n = 7) and 0.5 to 1.2 pg per cell⁻¹ (n = 3), respectively. The results of this study indicate that toxin production in this species is subject to variation depending on the strain. According to the growth experiment, D. norvegica exhibited a long lag phase, as suggested by the slow growth observed during the first 12 days. In the growth experiment, D. norvegica grew very slowly for the first 12 days, suggesting they had a long lag phase. However, after that, they grew exponentially, with a maximum growth rate of 0.56 divisions per day (during Days 24–27), reaching a maximum concentration of 3000 cells per mL⁻¹ at the end of the incubation (Day 36). In the toxin production study, the concentration of DTX1 and PTX2 increased following their vegetative growth, but the toxin production still increased exponentially on Day 36 (1.3 ng per mL⁻¹ and 154.7 ng per mL⁻¹ of DTX1 and PTX2, respectively). The concentration of OA remained below detectable levels (≤0.010 ng per mL⁻¹) during the 36-day incubation period, with the exception of Day 6. This study presents new information on the toxin production and content of D. norvegica, as well as insights into the maintenance and culturing of this species. Full article

Organism growth is often determined by multiple resources interdependently. However, growth models based on the Droop cell quota framework have historically been built using threshold formulations, which means they intrinsically involve single-resource limitations. In addition, it is a daunting task to study the global dynamics of these models mathematically, since they employ minimum functions that are non-smooth (not differentiable). To provide an approach to encompass interactions of multiple resources, we propose a multiple-resource limitation growth function based on the Droop cell quota concept and incorporate it into an existing producer–grazer model. The formulation of the producer’s growth rate is based on cell growth process time-tracking, while the grazer’s growth rate is constructed based on optimal limiting nutrient allocation in cell transcription and translation phases. We show that the proposed model captures a wide range of experimental observations, such as the paradox of enrichment, the paradox of energy enrichment, and the paradox of nutrient enrichment. Together, our proposed formulation and the existing threshold formulation provide bounds on the expected growth of an organism. Moreover, the proposed model is mathematically more tractable, since it does not use the minimum functions as in other stoichiometric models. Full article

The genus Amphidinium has been the subject of recent attention due to the production of polyketide metabolites. Some of these compounds have shown significant bioactivities and could be related to species interactions in the natural benthic microenvironment. Among these compounds, amphidinols (AMs) are suspected to be related to fish kills and probably implicated in ciguatera symptoms associated with the occurrence of benthic harmful algal blooms (bHABs). Here, we present the first report of a variety of AMs produced by cultured strains from several species from the Mexican Pacific, the Gulf of California, and the Gulf of Mexico. Through ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS), ten previously known AMs (AM02, -04, -05, -06, -07, -09, -11, -14, -15, and -17), four recently reported AMs (N7, N8/N9, N12, and N13), and three new variants (U1, U2, and U3) were identified. Of the twelve analyzed Amphidinium cultures, five were not AM producers, and the cell quotas of the remaining seven strains ranged from close to nondetectable to a maximum of 1694 fg cell⁻¹, with many intermediate levels in between. The cultures from the Mexican North Pacific coast produced AMs in a higher quantity and variety than those from worldwide locations. This is the first study of AMs from Mexican Amphidinium strains, and our results confirm the relevance of continuing the investigation of the genus bioactive metabolites. Full article

Since environmental benefits and supply chain resilience are commonly assumed for circular economy strategies, this study tests this hypothesis in the context of lithium-ion battery recycling and cell manufacturing. Therefore, the use of recyclates from different cathode active materials and from different recycling routes, namely hydrometallurgy and direct recycling, in a subsequent cell production is modelled with the recyclate quotas prescribed by the amended European Battery Regulation and analysed using life cycle assessment methodology. This study concludes that both, negative and positive environmental impacts can be achieved by the usage of recyclates, depended on the cell technology and the recycling process chosen. Newly constructed lithium iron phosphate (LFP) cells using a share of 11.3% of recyclates, which are obtained from LFP cells by a hydrometallurgical process, achieve a deterioration in the ecology by 7.5% for the global warming potential (GWP) compared to LFP cells without any recyclate share at all. For the same recyclate quota scenario, hydrometallurgical recyclates from lithium nickel manganese cobalt oxide cells (NMC), on the other hand, achieve savings in GWP of up to 1.2%. Recyclates from direct recycling achieve savings in GWP for LPF and NMC of a maximum of 6.3% and 12.3%, by using a recyclate share of 20%. It can be seen that circular economy can raise large savings potentials ecologically, but can also have a contrary effect if not properly applied. Full article

Freshwater components in the Southern Ocean, whether sea ice meltwater or meteoric water, influence the growth of phytoplankton by affecting water stability and supplying dissolved iron (DFe). In addition, melting sea ice stimulates phytoplankton blooms by providing ice algae. In this study, sea ice meltwater and meteoric water in the Amundsen Sea (AS) were differentiated by their stable oxygen isotopic compositions (δ¹⁸O), while the phytoplankton carbon fixation rate (CFR) and iron uptake rate (FeUR) values were determined using the ¹⁴C and ⁵⁵Fe tracer assays, respectively. Our results showed that FeUR exhibits a significant positive response only to sea ice meltwater, suggesting that DFe and algae provided by sea ice melting may be the main cause. In addition, the CFR had a slightly positive response to the freshwater input and a stronger correlation with the phytoplankton biomass, suggesting that the freshwater input may have enhanced the CFR through the algae released from sea ice melting. The FeUR normalized to the phytoplankton biomass was significantly positively correlated with the mixed layer depth, suggesting that water stability regulates the phytoplankton growth and the resulting Fe demand. A higher Fe demand per unit of carbon fixation during sea ice formation leads to a higher Fe/C ratio in phytoplankton. Although no significant correlations were observed between the FeUR, CFR, and meteoric water, meteoric water may have an effect on larger phytoplankton sensitive to Fe deficiencies. The results of culture experiments with DFe addition showed that the added Fe significantly enhanced the Fe uptake, carbon fixation, and Fe/C ratio of the cells, especially for micro-phytoplankton. The more pronounced response of micro-phytoplankton means that the meteoric water input may affect the efficiency of carbon export. Our study provides the first measurements of phytoplankton Fe quotas in the AS in austral late summer and early autumn, providing insights into how meteoric water and sea ice meltwater affect seasonal changes in Antarctic ecosystems. Full article

Copper is a critical metal nutrient required by marine microalgae but may be toxic when supplied in excess. Maintaining an optimal intracellular Cu content is thus fundamentally necessary for microalgae and relies on cellular regulatory metabolisms and the process of Cu uptake that buffers the variation in environmental Cu availability. In this article the current progress in understanding the Cu requirements and acquisition mechanisms of marine microalgae is reviewed. Cu requirement by microalgae is primarily determined by the amount of Cu-dependent enzymes involved in cellular metabolisms and can be adjusted by Cu-sparing pathways. Decrease in metabolic Cu quotas caused a decline in the abundance of cuproenzymes and the dependent cellular metabolisms, and an induction of Cu acquisition pathways. Conventional models of Cu uptake describe the dependence of Cu uptake rate on free Cu²⁺ ions or kinetically labile species. A reductive, high-affinity Cu uptake system in marine microalgae is identified which enables cells to directly utilize organically complexed Cu, highlighting the importance of cell surface Cu reduction in the marine Cu cycle. This review provides new insights into Cu uptake models that may update the existing knowledge of Cu availability in the ocean. Full article

The marine dinoflagellate microalga Amphidinium carterae is a source of amphidinols, a fascinating group of polyketide metabolites potentially useful in drug design. However, Amphidinium carterae grows slowly and produces these toxins in tiny amounts, representing a hurdle for large-scale production. Understanding dinoflagellate growth kinetics under different photobioreactor conditions is imperative for promoting the successful implementation of a full-scale integrated bioproduct production system. This study evaluates the feasibility of growing Amphidinium carterae under different ranges of nitrogen concentration (NO₃⁻ = 882–2646 µM), phosphorus concentration (PO₃³⁻ = 181–529 µM), and light intensity (Y₀ = 286–573 µE m⁻² s⁻¹) to produce amphidinols. A mathematical colimitation kinetic model based on the “cell quota” concept is developed to predict both algal growth and nutrient drawdown, assuming that all three variables (nitrogen, phosphorous and light) can simultaneously colimit microalgal growth. The model was applied to the semicontinuous culture of the marine microalgae Amphidinium carterae in an indoor LED-lit raceway photobioreactor. The results show that both growth and amphidinol production strongly depend on nutrient concentrations and light intensity. Nonetheless, it was possible to increase Amphidinium carterae growth while simultaneously promoting the overproduction of amphidinols. The proposed model adequately describes Amphidinium carterae growth, nitrate and phosphate concentrations, and intracellular nitrogen and phosphorus storage, and has therefore the potential to be extended to other systems used in dinoflagellate cultivation and the production of bioproducts obtained therein. Full article

Prostate cancer is a serious public health concern in the United States. The primary obstacle to effective long-term management for prostate cancer patients is the eventual development of treatment resistance. Due to the uniquely chaotic nature of the neoplastic genome, it is difficult to determine the evolution of tumor composition over the course of treatment. Hence, a drug is often applied continuously past the point of effectiveness, thereby losing any potential treatment combination with that drug permanently to resistance. If a clinician is aware of the timing of resistance to a particular drug, then they may have a crucial opportunity to adjust the treatment to retain the drug’s usefulness in a potential treatment combination or strategy. In this study, we investigate new methods of predicting treatment failure due to treatment resistance using a novel mechanistic model built on an evolutionary interpretation of Droop cell quota theory. We analyze our proposed methods using patient PSA and androgen data from a clinical trial of intermittent treatment with androgen deprivation therapy. Our results produce two indicators of treatment failure. The first indicator, proposed from the evolutionary nature of the cancer population, is calculated using our mathematical model with a predictive accuracy of 87.3% (sensitivity: 96.1%, specificity: 65%). The second indicator, conjectured from the implication of the first indicator, is calculated directly from serum androgen and PSA data with a predictive accuracy of 88.7% (sensitivity: 90.2%, specificity: 85%). Our results demonstrate the potential and feasibility of using an evolutionary tumor dynamics model in combination with the appropriate data to aid in the adaptive management of prostate cancer. Full article

The Vietnamese Mekong Delta is predicted to be one of the regions most impacted by climate change, causing increased temperature and salinity in inland waters. We hypothesized that the increase in temperature and salinity may impact the microcystin (MC) production of two Microcystis strains isolated in this region from a freshwater pond (strain MBC) and a brackish water pond (strain MTV). The Microcystis strains were grown at low (27 °C), medium (31 °C), high (35 °C) and extremely high (37 °C) temperature in flat photobioreactors (Algaemist). At each temperature, when cultures reached a stable state, sea salt was added to increase salinity to 4‰, 8‰, 12‰ and 16‰. MC concentrations and cell quota were reduced at high and extremely high temperatures. Salinity, in general, had comparable effects on MC concentrations and quota. At a salinity of 4‰ and 8‰, concentrations of MC per mL of culture and MC cell quota (based on chlorophyll, dry-weight and particle counts) were higher than at 0.5‰, while at the highest salinities (12‰ and 16‰) these were strongly reduced. Strain MBC produced five MC variants of which MC-RR and MC-LR were most abundant, followed by MC-YR and relatively low amounts of demethylated variants dmMC-RR and dmMC-LR. In strain MTV, MC-RR was most abundant, with traces of MC-YR and dmMC-RR only in cultures grown at 16‰ salinity. Overall, higher temperature led to lower MC concentrations and cell quota, low salinity seemed to promote MC production and high salinity reduced MC production. Hence, increased temperature and higher salinity could lead to less toxic Microcystis, but since these conditions might favour Microcystis over other competitors, the overall biomass gain could offset a lower toxicity. Full article

Bloom-forming cyanobacteria produce and release odorous compounds and pose threats to the biodiversity of aquatic ecosystem and to the drinking water supply. In this study, the concentrations of β-cyclocitral in different bacterial growth phases were investigated using GC–MS to determine the growth stage of Microcystis aeruginosa at high risk for β-cyclocitral production. Moreover, the synchronicity of the production of β-cyclocitral and its precursor β-carotene at both population and single-cell levels was assessed. The results indicated that β-cyclocitral was the main odorous compound produced by M. aeruginosa cells. The intracellular concentration of β-cyclocitral (C_β-cc) as well as its cellular quota (Q_β-cc) increased synchronously in the log phase, along with the increase of cell density. However, they reached the maximum values of 415 μg/L and 10.7 fg/cell in the late stationary phase and early stationary phase, respectively. The early stage of the stationary phase is more important for β-cyclocitral monitoring, and the sharp increase in Q_β-cc is valuable for anticipating the subsequent increase in C_β-cc. The molar concentrations of β-cyclocitral and β-carotene showed a linear relationship, with an R² value of 0.92, suggesting that the production of β-cyclocitral was linearly dependent on that of β-carotene, especially during the log phase. However, the increase in Q_β-cc was slower than that in β-carotene during the stationary phase, suggesting that β-cyclocitral production turned to be carotene oxygenase-limited when the growth rate decreased. These results demonstrate that variations of β-cyclocitral production on a single-cell level during different bacterial growth phases should be given serious consideration when monitoring and controlling the production of odorous compounds by M. aeruginosa blooms. Full article