Improving thermo-tolerance of Saccharomyces cerevisiae by precise regulation of the expression of small HSP.

The level of heat resistance in microbial cells is an important factor in determining the energy consumption and product synthesis efficiency of fermentation processes. Current research generally believes that heat shock proteins (HSPs) are the most closely related functional molecules to heat resistance inside cells. They can stabilize cell structures and allow cells to perform their normal physiological functions. Based on our previous transcriptome data, this study applies synthetic biology methods to validate the functionality of heat-resistant elements. The researchers introduced gene circuits expressing small HSPs (sHSP-HB8, HSP12, HSP26, HSP30, HSP42, and ibpa-MB4) with different promoter strengths (TDH3p, YNL247wp) into Saccharomyces cerevisiae strains for functional verification. All engineered strains, with the exception of No. 3 and No. 8, demonstrated a significantly higher growth rate and cell viability at 42 °C. Among them, No. 7 (YNL247wp-HSP12-SLM5t) and No. 11 (YNL247wp-sHSP-HB8-SLM5t), the two best performing engineered strains, exhibited a 19.8% and 17.2% increase in cell density, respectively, compared to the control strain. Additionally, the analysis of pyruvate kinase (PK) and malate dehydrogenase (MDH) enzyme activities indicated that the engineered strains enhanced protein quality at higher temperatures. The research methods and ideas presented in this paper have significant scientific reference value for exploring and applying other stress-resistant gene circuits.

[Adsorption Characteristics of Arsenic and Cadmium by FeMnNi-LDH Composite Modified by Fulvic Acid and Its Mechanisms].

Toxic As(Ⅲ) and Cd(Ⅱ) ions in water can be transferred and enriched into human bodies through the food chain, causing serious health damage at excessive levels. In this study, fulvic acid (FA) was selected as the modifier of iron-manganese-nickel layered double hydroxide (FeMnNi-LDH), and a stable layered composite (FA@FeMnNi-LDH) was prepared using the co-precipitation method, which could adsorb As(Ⅲ) anions and Cd(Ⅱ) cations simultaneously, especially with the higher adsorption capacity of the cation Cd(Ⅱ). Its structure was characterized by XRD, TEM, FT-IR, and XPS, and the adsorption capacity and mechanisms of As(Ⅲ) and Cd(Ⅱ) in water by the composite were also investigated. The results showed that with typical characteristic peaks of layered double hydroxides, the synthesized composite possessed a stable structure, maximum FA loading capacity, and optimal adsorption performance. The adsorption kinetics of As(Ⅲ) and Cd(Ⅱ) conformed to the pseudo-second-order kinetic model, and the adsorption isotherms well-followed the Langmuir model, with the maximum adsorption capacity at 25℃ being 249.60 mg·g-1 for As(Ⅲ) and 156.50 mg·g-1 for Cd(Ⅱ), respectively. The composite exhibited a good adsorption performance on As(Ⅲ) and Cd(Ⅱ) in the range of pH 2-7 and pH 4-7, respectively. The competitive adsorption effect of co-existed anions on As(Ⅲ) showed a sequence of PO43->CO32->NO3-, and that of co-existed cations on Cd(Ⅱ) was Pb2+>Cu2+>K+. The adsorption capacity of As(Ⅲ) and Cd(Ⅱ) decreased with the increase in the concentration of competing ions. The main adsorption mechanism for As(Ⅲ) was ion-exchange occurring in the interlayers of LDH, and that for Cd(Ⅱ) was coordination complexation occurring with the loaded FA, respectively. In conclusion, the prepared FA@FeMnNi-LDH composite material posed a good application prospect for adsorption removal of As(Ⅲ) and Cd(Ⅱ) in water and their toxicity control.

Involvement of LIMK2 in actin cytoskeleton remodeling during the definitive endoderm differentiation.

LIM kinases are involved in various cellular events such as migration, cycle, and differentiation, but whether they have a role in the specification of mammalian early endoderm remains unclear. In the present study, we found that depletion of LIMK2 severely inhibited the generation of definitive endoderm (DE) from human embryonic stem cells (hESCs) and promoted an early neuroectodermal fate. Upon the silencing of LIMK2 during the endodermal differentiation, the assembly of actin stress fibers was disturbed, and the phosphorylation of cofilin was decreased. In addition, knockdown of LIMK2 during DE differentiation also interfered the upregulation of epithelial-to-mesenchymal transition (EMT)-related genes and cell migration. Collectively, the results highlight that the serine/threonine kinase LIMK2, acting as a key regulator in actin remodeling, plays a critical role in endodermal lineage determination.

RSL3 Drives Ferroptosis through NF-κB Pathway Activation and GPX4 Depletion in Glioblastoma.

Glioblastoma, the most aggressive form of malignant glioma, is very difficult to treat because of its aggressively invasive nature and high recurrence rates. RAS-selective lethal 3 (RSL3), a well-known inhibitor of glutathione peroxidase 4 (GPX4), could effectively induce oxidative cell death in glioblastoma cells through ferroptosis, and several signaling pathways are involved in this process. However, the role of the nuclear factor kappa-B (NF-κB) pathway in glioblastoma cell ferroptosis has not yet been investigated. Therefore, we aimed to clarify the underlying mechanism of the NF-κB pathway in RSL3-induced ferroptosis in glioblastoma cells. We found that RSL3 led to an increase in lipid ROS concentration and downregulation of ferroptosis-related proteins such as GPX4, ATF4, and SLC7A11 (xCT) in glioblastoma cells. Additionally, the NF-κB pathway was activated by RSL3, and its inhibition by BAY 11-7082 could alleviate ferroptosis. The murine xenograft tumor model indicated that NF-κB pathway inhibition could mitigate the antitumor effects of RSL3 in vivo. Furthermore, we found that GPX4 knockdown could not effectively induce ferroptosis. However, NF-κB pathway activation coupled with GPX4 silencing induced ferroptosis. Additionally, ATF4 and xCT expression might be regulated by the NF-κB pathway. Collectively, our results revealed that the NF-κB pathway plays a novel role in RSL3-induced ferroptosis in glioblastoma cells and provides a new therapeutic strategy for glioblastoma treatment.

Excess dietary sodium selenite alters apoptotic population and oxidative stress markers of spleens in broilers.

Three hundred 1-day-old avian broilers were fed on a basic diet (0.2 mg/kg selenium) or the same diet amended to contain 1, 5, 10, and 15 mg/kg selenium supplied as sodium selenite (n = 60/group). In comparison with those of 0.2 mg/kg selenium group, the percentages of annexin V-positive splenocytes were increased in 5, 10, and 15 mg/kg selenium groups. TUNEL assay revealed that apoptotic cells with brown-stained nuclei distributed within the red pulp and white pulp of the spleens with increased frequency of occurrence in 10 and 15 mg/kg selenium groups in comparison with that of 0.2 mg/kg Se group. Sodium selenite-induced oxidative stress in spleens of chickens was evidenced by decrease in glutathione peroxidase, superoxide dismutase, and catalase activities and increase in malondialdehyde contents. The results indicate that excess dietary selenium in the range of 5-15 mg/kg of feed causes oxidative stress, which may be mainly responsible for the increased apoptosis of splenocytes in chickens.