Increase In Cell Density Research Articles

Stem cell mechanoadaptation. I. Effect of microtubule stabilization and volume changing stresses on cytoskeletal remodeling.

Here, we report on the first part of a two-part experimental series to elucidate spatiotemporal cytoskeletal remodeling, which underpins the evolution of stem cell shape and fate, and the emergence of tissue structure and function. In Part I of these studies, we first develop protocols to stabilize microtubules exogenously using paclitaxel (PAX) in a standardized model murine embryonic stem cell line (C3H/10T1/2) to maximize comparability with previously published studies. We then probe native and microtubule-stabilized stem cells' capacity to adapt to volume changing stresses effected by seeding at increasing cell densities, which emulates local compression and tissue template formation during development. Within the concentration range of 1-100 nM, microtubule-stabilized stem cells maintain viability and reduce proliferation. PAX stabilization of microtubules is associated with increased cell volume as well as flattening of the cell and nucleus. Compared to control cells, microtubule-stabilized cells exhibit thick, bundled microtubules and highly aligned, thicker and longer F-actin fibers, corresponding to an increase in the Young's modulus of the cell. Both F-actin and microtubule concentration increase with increasing PAX concentration, whereby the increase in F-actin is more prominent in the basal region of the cell. The corresponding increase in microtubule is observed more globally across the apical and basal region of the cell. Seeding at increasing target densities induces local compression on cells. This increase in local compression modulates cell volume and concomitant increases in F-actin and microtubule concentration to a greater degree than microtubule stabilization via PAX. Cells seeded at high density exhibit higher bulk modulus than corresponding cells seeded at low density. These data demonstrate the capacity of stem cells to adapt to an interplay of mechanical and chemical cues, i.e., respective compression and exogenous microtubule stabilization; the resulting cytoskeletal remodeling manifests as evolution of mechanical properties relevant to development of multicellular tissue constructs.

EFFECT OF LOCALLY ISOLATED <i>SCENEDESMUS</i> SP. TN1 ON BIOMASS PRODUCTION AND NUTRIENT REMOVAL FROM COOKING COCOON WASTEWATER: EFFECTS OF INITIAL ALGAL CELL DENSITY AND TEMPERATURE

Scenedesmus sp. TN1, a local freshwater microalga, was cultivated in cooking cocoon wastewater. The effects of initial algal cell density and temperature on microalgae growth and the removal of total nitrogen (T-N), total phosphorus (T-P), and chemical oxygen demand (COD) were studied. The initial algal cell densities were 5, 10, 15, and 20 mg/l. The experimental temperatures varied from 20 °C to 30 °C. The growth rate increased with the increase in initial algal cell density up to 15 mg/l and was statistically stable thereafter. A similar trend of total nitrogen, total phosphorus, and COD removal efficiency was observed. The optimum temperature for microalgae growth and nutrient removal was 30 °C. After 9 days of cultivation, Scenedesmus sp. TN1 exhibited nutrient removal efficiencies of 88.28%, 82.91%, 92.01%, and 89.16% for T-N, T-P, biological oxygen demand (BOD5), and COD, respectively. The maximum biomass production and nutrient removal efficiencies of Scenedesmus sp. TN1 were observed at cultivation conditions of 15 mg/l initial algal cell density at 30 °C. This study compiled information on the cultivation conditions for cooking cocoon wastewater treatment practices.

Bb0689 contributes to the virulence of Borrelia burgdorferi in a murine model of Lyme disease.

Borrelia burgdorferi, the Lyme disease pathogen, continuously changes its gene expression profile in order to adapt to ticks and mammalian hosts. The alternative sigma factor RpoS plays a central role in borrelial host adaptation. Global transcriptome analyses suggested that more than 100 genes might be regulated by RpoS, but the main part of the regulon remains unexplored. Here, we showed that the expression of bb0689, a gene encoding an outer surface lipoprotein with unknown function, was activated by RpoS. By analyzing gene expression using luciferase reporter assays and quantitative reverse transcription PCR, we found that expression of bb0689 was induced by an elevated temperature, a reduced pH, and increased cell density during in vitro cultivation. The transcriptional start site and a functional promoter for gene expression were identified in the 5' regulatory region of bb0689. The promoter was responsive to environmental stimuli and influenced by RpoS. We also showed that bb0689 expression was expressed in B. burgdorferi during animal infection, suggesting the importance of this gene for infection. We further generated a bb0689 mutant and found that the infectivity of the mutant was severely attenuated in a murine infection model. Although bb0689-deficient spirochetes exhibited no defect during in vitro growth, they were defective in resistance to osmotic stress. Cis-complementation of the mutant with a wild-type copy of bb0689 fully rescued all phenotypes. Collectively, these results demonstrate that the RpoS-regulated gene bb0689 is a key contributor to the optimal infection of B. burgdorferi in animals.

Stress-induced premature senescence in high five cell cultures: a principal factor in cell-density effects

The Baculovirus Expression Vector System (BEVS) is highly valued in vaccine development, protein engineering, and drug metabolism research due to its biosafety, operational convenience, rapid scalability, and capacity for self-assembling virus-like particles. However, increasing cell density at the time of inoculation severely compromises the production capacity of BEVS, resulting in the “cell density effect”. This study aimed to explore the mechanisms of the cell density effect through time-series analysis of transcriptomes and proteomes, with the goal of overcoming or alleviating the decline in productivity caused by increased cell density. The dynamic analysis of the omics of High Five cells under different CCI (cell density at infection) conditions showed that the impact of the “cell density effect” increased over time, particularly affecting genetic information processing, error repair, protein expression regulation, and material energy metabolism. Omics analysis of the growth stage of High Five cells showed that after 36 h of culture (cell density of about 1 × 106 cells/mL), the expression of ribosome-related proteins decreased, resulting in a rapid decrease in protein synthesis capacity, which was a key indicator of cell aging. Senescence verification experiments showed that cells began to show obvious early aging characteristics after 36 h, resulting in a decrease in the host cell’s ability to resist stress. Overexpression and siRNA inhibition studies showed that the ndufa12 gene was a potential regulatory target for restricting the “cell density effect”. Our results suggested that stress-induced premature senescence in High Five cell cultures, resulting in reduced energy metabolism and protein synthesis capabilities, was a critical factor contributing to cell density effects, and ultimately affecting virus production. In conclusion, this study provided new insights into managing virus production limitations due to cell density effects and offered innovative strategies to mitigate the adverse effects of cellular aging in biomanufacturing technologies.Graphical abstract

Enhanced Oil Recovery in a Co-Culture System of Pseudomonas aeruginosa and Bacillus subtilis.

Microbial enhanced oil recovery (MEOR) is a promising technology for oil field extraction. This study investigated a co-culture system of Pseudomonas aeruginosa and Bacillus subtilis to increase MEOR efficacy. We analyzed bacterial growth, biosurfactant production, and crude oil emulsified performance under different inoculation ratios. Compared to single cultures, the co-culture system showed superior growth and functional expression, with an optimal inoculation ratio of 1:1. Quantitative assessments of the cell numbers and biosurfactant production during the co-culture revealed that rapid B. subtilis proliferation in early stages significantly stimulated P. aeruginosa growth. This interaction increased cell density and rhamnolipid production by 208.05% and 216.25%, respectively. The microscopic etching model displacement results demonstrated enhanced emulsification and mobilization of crude oil by the co-culture system, resulting in 94.48% recovery. A successful field application in a block-scale reservoir increased cumulative oil production by 3.25 × 103 t. An analysis of microbial community structure and function in different phases revealed that after co-culture system injection, Pseudomonas became the dominant genus in the reservoir community, with an average abundance of 24.80%. Additionally, the abundance of biosurfactant-producing and hydrocarbon-degrading bacteria increased significantly. This research and the application of the P. aeruginosa and B. subtilis co-culture system provide novel insights and strategies for MEOR.

CXCL1-CXCR2 signaling mediates the activation of microglia in the nucleus tractus solitarii to promote pancreatic cancer-induced pain

Pancreatic cancer can cause severe abdominal pain. Its peripheral mechanisms have been studied, but the role of central nervous system in pancreatic cancer-induced pain remains unclear. The current study focused on the nucleus tractus solitarii (NTS), a primary center of visceral sensation located in medulla oblongata. Neurons in the NTS were activated and exhibited increased excitability among mice with pancreatic cancer-induced pain. Transcriptome analysis revealed that pancreatic cancer-induced pain was associated with neuroinflammation in the NTS, involving changes in chemokines expression. In mice with pancreatic cancer-induced pain, the microglia activation in the NTS was observed, characterized by increased cell density and decreased process number and length, while injection of microglia inhibitor minocycline in the NTS alleviated pancreatic cancer-induced pain. The cytokine CXCL1 and its receptor CXCR2 were upregulated in the NTS of mice with pancreatic cancer-induced pain. Blocking CXCL1-CXCR2 signaling by injection of CXCL1 neutralizing antibody or CXCR2 antagonist SB225002 in the NTS of mice with pancreatic cancer-induced pain alleviated abdominal hypersensitivity and hunching behavior, and also reversed the activation of neurons and microglia. Additionally, injection of recombinant CXCL1 in the NTS of sham-operated mice induced abdominal pain, and activated the neurons and microglia. In summary, our study highlights the critical role of NTS microglia activation mediated by CXCL1-CXCR2 signaling in pancreatic cancer-induced pain.

The trans-differentiation promotion of parietal epithelial cells by magnesium isoglycyrrhizinate to improve podocyte injury induced by high fructose consumption

BackgroundPodocytes have limited proliferative capacity, which leads to irreversible glomerular injury in diverse kidney diseases. Magnesium isoglycyrrhizinate (MgIG), a hepatoprotective agent in clinic, has been reported to improve glomerular podocyte injury. However, the underlying mechanism of MgIG in ameliorating podocyte injury remains unclear. PurposeGlomerular parietal epithelial cells (PECs) are recognized as podocyte progenitors and play a pivotal role in the recovery following glomerular injury. This work aims to investigate the protective mechanisms of MgIG in mitigating glomerular injury by promoting PEC trans-differentiation. Study DesignA rat model of progressive glomerular podocyte injury, and in vitro models using the primary podocytes and primary PECs, were established to further explore the pharmacological mechanism of MgIG. MethodsFour-week-old male Sprague-Dawley (SD) rats were fed a 10 % fructose solution for 3, 6, 9 and 12 weeks to induce glomerular injury. The effects of MgIG on the progressive changes in podocytes and PECs, and the correlation between PEC density and podocyte loss, were analyzed. The mechanism of MgIG in triggering PEC trans-differentiation was investigated, by examining adenosine secretion in injured podocytes, as well as the expression of cluster of differentiation 44 (CD44), nephrin, adenosine receptor A2B (ARA2B) and glucocorticoid receptor (GR) in PECs both in vivo and in vitro. ResultsRats fed a high fructose diet exhibited progressive changes in glomerular PECs, including increased cell density and a preference for trans-differentiation. A positive correlation was observed between PEC density and podocyte loss. Co-culture experiments demonstrated that extracellular adenosine accumulation from injured podocytes induced by high fructose exposure promoted PEC trans-differentiation via ARA2B. MgIG significantly improved podocyte injury and exhibited effects similar to dexamethasone on nephrin upregulation and CD44 inhibition. Moreover, the effect of MgIG on PEC ARA2B activation was more effective than that of dexamethasone. The co-expression of paired box 2 (PAX2)+-Nephrin+ in glomeruli indicated that MgIG induced PEC trans-differentiation and podocyte regeneration in model rats. Accordingly, podocyte loss and increased urine albumin-to-creatinine ratio (UACR) were also alleviated. Moreover, MgIG, which acts as a GR agonist to activate GR, reversed the upregulation of CD44 and decreased ARA2B induced by tumor necrosis factor-α (TNF-α) in primary PECs. The siRNA interference experiment manifested that MgIG exhibited a more pronounced enhancement of GR upregulation, in contrast to ARA2B activation, to promote PEC trans-differentiation. ConclusionThis work reports for the first time that PECs respond to the accumulation of extracellular adenosine from injured podocytes via activating ARA2B and focuses on the role of adenosine and adenosine receptors in the trans-differentiation of PECs. Furthermore, this study provides the first evidence that MgIG may promote podocyte regeneration by enhancing PEC trans-differentiation through GR activation, providing a research basis for investigating the glucocorticoid-like activity of MgIG in ameliorating glomerular podocyte injury.

Rare atypical type a thymoma: a case report and literature review

BackgroundAn atypical type A thymoma variant was recently added to the World Health Organization classification of type A thymoma in 2015. This novel form of type A thymoma presents with hypercellularity, increased mitotic activity, and necrosis. In particular, necrosis seems to be related to postoperative recurrence and metastasis, but the clinical significance of these changes still needs to be studied.Case presentationA 76-year-old man underwent thoracoscopic surgery for tumour resection due to an anterior mediastinal mass. Pathological examination revealed that the tumour invaded the surrounding thymic tissue. Cells were arranged in nest-like and whirl-like patterns, accompanied by prominent comedo-like necrosis, increased cell density, mild atypia, and a mitotic count of 4–6 per 10 high-power fields. Immunohistochemistry revealed positive expression of cytokeratin 19 and P63 in the tumour cells. Lymphocytes in the background were positive for CD3 and CD5, did not express terminal deoxynucleotide transferase, CD20, or CD117, and had an MIB-1 labelling index(LI) value of 15%. On the basis of these findings, the tumour was finally diagnosed as an atypical type A thymoma variant.ConclusionsWe report a case of atypical type A thymoma and review the literature to enhance our understanding of and provide accumulated pathological data on this rare disease.

Functional Differentiation along the Rostro-Caudal Axis of the Avian Hippocampal Formation

Introduction: Different functional domains can be identified along the longitudinal axis of the mammalian hippocampus. We have recently hypothesized that a similar functional gradient may exist along the longitudinal axis of the avian hippocampal formation (HF) as well. If the 2 gradients are homologous, we would expect the caudal HF to be more responsive to acute stress than the rostral HF. Methods: We restrained 8 adult Dekalb White hens in a bag for 30 min under red-light conditions and compared FOS-immunoreactive (FOS-ir) cell densities in different hippocampal subdivisions to control hens. Results: Although we could find no evidence of an activated stress response in the hypothalamic-pituitary-adrenal axis of the restrained birds, we did find a significant increase in FOS-ir cell densities in the rostral HF of the restrained birds compared to controls. Conclusion: We speculate that the HF response is not due to an acute stress response, but instead, it is related to the change in spatial context that was part of taking the birds and restraining them in a different room. We see no activation in the caudal HF. This would be consistent with our hypothesis that the longitudinal axis of the avian HF is homologous to the long axis of the mammalian hippocampus.

Exploring the role of different cell types on cortical folding in the developing human brain through computational modeling

The human brain’s distinctive folding pattern has attracted the attention of researchers from different fields. Neuroscientists have provided insights into the role of four fundamental cell types crucial during embryonic development: radial glial cells, intermediate progenitor cells, outer radial glial cells, and neurons. Understanding the mechanisms by which these cell types influence the number of cortical neurons and the emerging cortical folding pattern necessitates accounting for the mechanical forces that drive the cortical folding process. Our research aims to explore the correlation between biological processes and mechanical forces through computational modeling. We introduce cell-density fields, characterized by a system of advection-diffusion equations, designed to replicate the characteristic behaviors of various cell types in the developing brain. Concurrently, we adopt the theory of finite growth to describe cortex expansion driven by increasing cell density. Our model serves as an adjustable tool for understanding how the behavior of individual cell types reflects normal and abnormal folding patterns. Through comparison with magnetic resonance images of the fetal brain, we explore the correlation between morphological changes and underlying cellular mechanisms. Moreover, our model sheds light on the spatiotemporal relationships among different cell types in the human brain and enables cellular deconvolution of histological sections.

Calcification in sea urchin larvae is associated with low metabolic costs.

The energetic costs to generate calcium carbonate skeletons and shells in marine organisms remain largely speculative due to the scarcity of empirical data. However, this information is critical to estimate energetic limitations of marine calcifiers that can explain their sensitivities to changes in sea water carbonate chemistry in past, present and future marine systems. The cost of calcification was evaluated using larval stages of the purple sea urchin, Strongylocentrotus purpuratus. We developed a skeleton re-mineralization assay, in which the skeleton was dissolved in live larvae followed by a re-mineralization over a few days. During skeleton re-mineralization, energetic costs were estimated through the measurement of key metabolic parameters including whole animal metabolic rates, citrate synthase (CS) enzyme activities and mRNA expression as well as mitochondrial densities in the calcifying primary mesenchyme cells (PMCs). Minor increases in a CS activity and a 10-15% increase in mitochondrial densities in PMCs were observed in re-mineralizing larvae as compared to control larvae. Re-mineralization under three different pH conditions (pH 8.1, pH 7.6 and pH 7.1) decreased with decreasing pH accompanied by pronounced increases in CS expression levels and increased mitochondrial densities in PMCs at pH 7.6. Despite a prominent increase in mitochondrial density of primary mesenchyme cells, particularly in the calcifying cohort of this cell type, this work demonstrated a low overall metabolic response to increased mineralization rates on the whole animal level under both, high and low pH conditions. We conclude that calcification in sea urchin larvae is compromised under low pH conditions, associated with low energetic efforts to fuel compensatory processes.

No Benefit of 3% Hypertonic Saline Following Experimental Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a stroke subtype with a high mortality rate (~ 40%). After ICH, the mass effect of the hematoma and edema contribute to raised intracranial pressure (ICP) and poor outcome. Endogenous compensatory mechanisms that blunt ICP elevations include redirection of venous blood and cerebrospinal fluid, along with brain tissue compliance (e.g., decreased cell volume, increased cell density); however, these limited reserves can be exhausted after severe stroke, resulting in decompensated ICP that requires careful clinical management. Management strategies can include administration of hypertonic saline (HTS), an osmotic agent that putatively attenuates edema, and thereby ICP elevations. Evidence regarding the efficacy of HTS treatment following ICH remains limited. In this study, adult male rats were given a collagenase-induced striatal ICH and a bolus of either 3% HTS or 0.9% saline vehicle at 2- and 14-hours post-stroke onset. Neurological deficits, edema, ipsilateral cell volume and density (in areas S1 and CA1), and contralateral CA1 ultrastructural morphology were assessed 24 h post-ICH. Animals had large bleeds (median 108.2 µL), extensive edema (median 83.9% brain water content in ipsilateral striatum), and evident behavioural deficits (median 5.4 neurological deficit scale score). However, HTS did not affect edema (p ≥ 0.4797), behaviour (p = 0.6479), cell volume (p ≥ 0.1079), or cell density (p ≥ 0.0983). Qualitative ultrastructural assessment of contralateral area CA1 suggested that HTS administration was associated with paradoxical cellular swelling in ICH animals. Overall, there was no benefit with administering 3% HTS after ICH.

Objective: To investigate the use of biological ensiling of organic residues generated by pectiniculture as a nutritive medium in the production of the microalgae Tetraselmis suecica. Theoretical Framework: Biological ensiling is a process that transforms organic residues into a nutritive source through fermentation. In this context, pectiniculture residues, specifically the soft parts of fan shells, can be recycled and used

Objective: To investigate the use of biological ensiling of organic residues generated by pectiniculture as a nutritive medium in the production of the microalgae Tetraselmis suecica. Theoretical Framework: Biological ensiling is a process that transforms organic residues into a nutritive source through fermentation. In this context, pectiniculture residues, specifically the soft parts of fan shells, can be recycled and used as alternative media. Microalgae, such as T. suecica, are photosynthetic organisms that require nutrients for their growth, and their cultivation can benefit from these residues. Method: Twelve vertical bioreactors were used with three experimental treatments (T1, T2, T3) and treatments, one control (CT), with three replicates per treatment. The microalgae were inoculated at a density of 70 x 104 cells mL-1 in a culture volume of 80 L. Cultures were grown in open air with constant aeration. 0-, 60-, 70-, and 80-mL L-1 of the biological silage of fan shell soft parts (EBCA) were dosed. The silage was also chemically characterized and the growth of the microalgae and its relationship with temperature, salinity and pH were determined. Results and Discussion: The results showed that the dosage of 70 mL L-1 of EBCA in T. suecica cultures favors the growth of the microalgae. A significant increase in biomass and cell density was observed compared to the other treatments, indicating that this concentration of silage provides a suitable nutrient medium. The study also analyzed how temperature, salinity and pH conditions affect the growth of T. suecica, finding that certain optimal ranges of these factors can maximize biomass production. Research Implications: Our study demonstrates that pectin culture waste can be effectively recycled as a culture medium for T. suecica production, offering a sustainable and environmentally friendly solution for waste management. This could reduce reliance on traditional culture media and promote more sustainable practices in aquaculture and the microalgal industry. Originality/Value: This study stands out for its innovative approach in the use of organic waste from pectiniculture, such as the soft parts of the fan shell, for the generation of an alternative nutrient medium for microalgae. In addition, large volumes of fan shell wastes are currently being generated, so our work contributes to the management of these wastes.

Differential regulation of expression of the protein kinases DYRK1A and DYRK1B in cancer cells

The protein kinases DYRK1A and DYRK1B are pivotal regulators of cell cycle progression by promoting cell cycle exit into quiescence. DYRK1B appears to play a more important role in cancer cell quiescence than DYRK1A, as evidenced by its overexpression or copy number variations in human tumour samples. Nonetheless, the stimuli driving DYRK1B upregulation and the potential divergence in expression patterns between DYRK1A and DYRK1B remain largely elusive. In the present study, we scrutinized the regulatory pathways modulating DYRK1B expression relative to DYRK1A in PANC-1 and A549 cancer cell lines across varying conditions. Serum deprivation, pharmacological mTOR inhibition and increased cell density resulted in the differential upregulation of DYRK1B compared to DYRK1A. We then aimed to assess the role of protein kinases MST1 and MST2, which are key transmitters of cell density dependent effects. Unexpectedly, exposure to the MST1/2 inhibitor XMU-MP-1 resulted in increased DYRK1B levels in A549 cells. Further investigation into the off-target effects of XMU-MP-1 unveiled the inhibition of Aurora kinases (AURKA and AURKB) as a potential causative factor. Consistently, AURK inhibitors VX-680 (tozasertib), MLN8237 (alisertib), AZD1152-HQPA (barasertib) resulted in the upregulation of DYRK1B expression in A549 cells. In summary, our findings indicate that the expression of DYRK1A and DYRK1B is differentially regulated in cancer cells and reveal that the kinase inhibitor XMU-MP-1 increases DYRK1B expression likely through off target inhibition of Aurora kinases.

Modulation of textural properties in microwave treated gluten-free quinoa sponge cake by alkaline amino acids

Lysine (Lys) and Arginine (Arg) (0.6%) was added to the quinoa flour to improve the textural quality and physical properties of gluten-free sponge cake treated with different heating methods. The gluten-free sponge cake fortified Lys and Arg increased cell density and surface area fraction, compared to water bath (WB) treatment, with the microwave (MW) treatment further enhancing these effects. Furthermore, MW combined Lys treatment showed the best texture characteristics of sponge cake. The water distribution determined by 1H NMR presented that water molecules are bound by the protein network structure. FTIR spectrum proved MW combined with Lys promoted the transition from disordered structure to ordered structure of protein in quinoa sponge cake, which enhanced the expansion of protein molecules and the exposure of hydrophobic regions, thus promoting protein aggregation. SDS-PAGE revealed when alkaline amino acids were present, they can regulate the ordered aggregation of protein molecules under MW alternating electric field, leading to enhanced intermolecular interactions. Finally, microstructure evaluations by SEM demonstrated MW combined with alkaline amino acids formed a stable three-dimensional gel network structure, thus improving the quality of gluten-free quinoa sponge cake. Therefore, the study findings pointed to the feasibility of using MW to improve the physical and textual quality of quinoa gluten-free food.

Modified culture media development using locally available fertilizers and vitamin supplements for continuous mass culture of Chaetoceros gracilis

Microalgae culture is a vital nutritional resource for hatchery development in aquaculture and has gained significant interest as a sustainable food ingredient, versatile feedstock for biofuels, with broad industrial applications. The high cost of microalgae culture media hinders mass production, necessitating the development of affordable, simpler alternatives for commercial viability. The aim of this study was to develop a modified culture media for Chaetoceros gracilis utilizing locally available fertilizers and vitamins. In the first experiment, the cell density of C. gracilis across four fertilizers combinations (T1, T2, T3 and T4) with three replicates was evaluated to identify the best performing fertilizers recipe. The significantly higher cell density was observed in T1, where a combination of urea, TSP, mineral mix, EDTA, silicate gel, NPK, compost were used, than the other treatments where one or more ingredients were missing. The growth curve showed that with 1 ml/L fertilizers combination of T1 cell density peaked (21.8×10^5 cell/ml) at day three with the death phase starting at day 04. In the second experiment, the effect of vitamin addition was evaluated with T1 considering as control (V0-without vitamin supplement) and, the Multivitamin-Zinc B and Neobion addition with T1 as treatment V1 and V2, respectively. While Neobion addition significantly increased cell density, multivitamin-Zinc B addition reduced the cell density. Finally, the potentiality of continuous culture of C. gracilis with the modified fertilizer media (V2) was evaluated. The cell density in 300 L tank culture starting from 6.6×10^5 cell/ml peaked 23.8 ×10^5 cell/ml at day two and remained relatively static until investigation finished with the supplement of V2 media two days interval. The present study suggest that development of modified fertilizer media using affordable, locally sourced ingredients for algae cultivation in the hatcheries and aquaculture industry could create an alternative to relying on pure laboratory-grade media.

Geometric constraint of mechanosensing by modification of hydrogel thickness prevents stiffness-induced differentiation in bone marrow stromal cells.

Extracellular matrix (ECM) stiffness is fundamental in cell division, movement and differentiation. The stiffness that cells sense is determined not only by the elastic modulus of the ECM material but also by ECM geometry and cell density. We hypothesized that these factors would influence cell traction-induced matrix deformations and cellular differentiation in bone marrow stromal cells (BMSCs). To achieve this, we cultivated BMSCs on polyacrylamide hydrogels that varied in elastic modulus and geometry and measured cell spreading, cell-imparted matrix deformations and differentiation. At low cell density BMSCs spread to a greater extent on stiff compared with soft hydrogels, or on thin compared with thick hydrogels. Cell-imparted matrix deformations were greater on soft compared with stiff hydrogels or thick compared with thin hydrogels. There were no significant differences in osteogenic differentiation relative to hydrogel elastic modulus and thickness. However, increased cell density and/or prolonged culture significantly reduced matrix deformations on soft hydrogels to levels similar to those on stiff substrates. This suggests that at high cell densities cell traction-induced matrix displacements are reduced by both neighbouring cells and the constraint imposed by an underlying stiff support. This may explain observations of the lack of difference in osteogenic differentiation as a function of stiffness.

Optimizing Nitrate and Tryptone to Enhance Growth and Triacylglycerol Accumulation in Phaeodactylum tricornutum.

Phaeodactylum tricornutum, a unicellular diatom, is considered a potential feedstock for the production of biofuel and a promising producer for high-value products eicosapentaenoic acid and fucoxanthin. However, a high-efficient cultivating strategy to achieve commercial production of triacylglycerol (TAG) from the diatom is an urgent demand. In this study, we optimized the content and ratio of nitrate and tryptone in the medium to enhance biomass and TAG accumulation simultaneously. Growth with tryptone as the sole nitrogen gave rise to the lowest cell density but the highest TAG content in P. tricornutum relative to nitrate, nitrite, ammonium or urea cultures. In 500 μM NaNO3 cultures, the growth of P. tricornutum increased with the increasing concentration (from 294 to 7056 μM nitrogen) of supplemented tryptone, however supplementation of high tryptone (≥882 μM nitrogen) decreased the neutral lipid content. Elevating nitrogen concentration from 294 to 882 μM via tryptone addition in 250 μM nitrate culture increased cell densities from day 6 to 10 and neutral lipid content on day 10. In particular, supplementing 588 μM nitrogen of tryptone in the 250 μM nitrate culture gave rise to the highest neutral lipid content on days 8 and 10 (increased by 109% and 62% relative to 500 μM nitrate-sole) with a comparable growth to that in 500 μM nitratesole culture from day 2 to 8. In conclusion, we optimized nitrate/tryptone ratio and found that a suitable tryptone addition to a relatively low nitrate culture was favourable to the biomass and TAG accumulation simultaneously in P. tricornutum.

Sustainable transforming toxic sludge into amino acids via bacteria-algae consortium

The utilization of residual sludge by microalgae represents an environmentally sustainable method for resource recovery. In this study, Tetradesmus obliquus was cultured in hydrolysate derived from toxic sludge. Under symbiotic conditions with bacteria, Tetradesmus obliquus demonstrated enhanced toxin degradation capability and biomass accumulation, which exhibited a 1.39-fold increase in algal cell density, a 1.50-fold increase in Rubisco activity, and a total protein content of 341.83 ± 6.99 mg/L on the 30th day of cultivation. Metabolic utilization of substances in the hydrolysate by microalgae led to a toxicity removal rate of up to 60.43% by day 10. Phenylalanine showed the most significant increase among essential amino acids, and transcriptomic profiling identified genes (gene_16399, gene_16602) involved in phenylalanine enrichment. Macrotranscriptomics showed that bacteria upregulated the TCS system and tryptophan metabolism, supplying microalgae with more CO2 and IAA, which enhanced amino acid enrichment. This study established a non-toxic and biomass-accumulating bacterial-algal co-cultivation system.

Innovative Utilization of Blood Cockle Shell Waste (Anadara granosa) as a Growth Medium for Nitzschia sp.

Shellfish are a fishery commodity in Indonesia with increasing production annually, including a projected 137 thousand tons in 2024. Among the various types of shellfish, blood cockle is one of the most popular among citizens. Only 11-16% of their body is consumable, while the majority of it consists of shells that end up as waste. This waste is generally processed into crafts or animal feed. Blood cockle shell waste contains nitrogen (N) and phosphorus (P), which are necessary for higher and lower plants. This study was conducted to explore the potential of blood cockle shell waste as a growth medium for the microalgae Nitzschia sp. Reduction of the N and P ratio in this study was carried out to increase cell density by limiting nutrients of Nitzschia sp. There were five treatments with four replications in this study: P1 as a positive control (f/2 medium; N/P 8:1), P2 (cockle shell fertilizer medium/CSF; N/P 1,3:1), P3 (CSF+NaNO3; N/P 0,1:1), P4 (CSF+NaNO3; N/P 0,121:1), and P5 (CSF+NaNO3; N/P ratio 0,144:1). The results showed a significant difference (p<0.05) in the population of Nitzschia sp. in P3 with the highest density of 862.500 cells/ml and average daily growth of 275.000 cells/day. Based on this, the lowest N/P ratio limitation showed the best growth in Nitzschia sp. The low ratio indicates the prevention of toxicity in the culture medium. N limitation in this study also showed optimization of N utilization in the metabolic process of Nitzschia sp. N limitation is a strategy to increase the accumulation of nutrients in some microalgae, including Nitzschia sp., as observed in this study.