Carotenoids represent the most abundant lipid-soluble phytochemicals that have been shown to exhibit benefits for nutrition and health. The production of natural carotenoids is not yet cost effective ...to compete with chemically synthetic ones. Therefore, the demand for natural carotenoids and improved efficiency of carotenoid biosynthesis has driven the investigation of metabolic engineering of native carotenoid producers. In this study, a new
Sphingobium
sp. was isolated, and it was found that it could use a variety of agro-industrial byproducts like soybean meal, okara, and corn steep liquor to accumulate large amounts of nostoxanthin. Then we tailored it into three mutated strains that instead specifically accumulated ∼5 mg/g of CDW of phytoene, lycopene, and zeaxanthin due to the loss-of-function of the specific enzyme. A high-efficiency targeted engineering carotenoid synthesis platform was constructed in
Escherichia coli
for identifying the functional roles of candidate genes of carotenoid biosynthetic pathway in
Sphingobium
sp. To further prolong the metabolic pathway, we engineered the
Sphingobium
sp. to produce high-titer astaxanthin (10 mg/g of DCW) through balance in the key enzymes β-carotene ketolase (BKT) and β-carotene hydroxylase (CHY). Our study provided more biosynthesis components for bioengineering of carotenoids and highlights the potential of the industrially important bacterium for production of various natural carotenoids.
Microalgae are recognized as a promising and valuable source of lutein. However, the current two-stage method for lutein production has drawbacks, such as complex operations and a long cultivation ...time. Additionally, utilizing heterotrophic fermentation to cultivate microalgae for lutein production leads to low lutein content due to the absence of light. In this study, we proposed a novel cultivation method that involves light induction of the seed culture to enhance lutein production during the heterotrophic cultivation phase of Chlorella protothecoides CS-41. To gain comprehensive insights into the underlying mechanisms of this method, we conducted qualitative and quantitative analyses of specific metabolites related to central carbon metabolism. The results revealed that low-light induction of seeds exhibited higher carbon efficiency compared to cells continuously subjected to heterotrophic cultivation, which may explain the observed increase in biomass and lutein content in cultures. Cultures after low-light induction of seed exhibited significantly higher lutein content (2.71 mg/g), yield (66.49 mg/L) and productivity (8.59 mg/L/d) compared to those consistently cultivated under heterotrophic conditions (2.37 mg/g, 37.45 mg/L, 4.68 mg/L/d). This cultivation strategy effectively enhances lutein yields, reduces production costs and holds the potential for broader application in other algal species for pigment production.
Cognitive impairment is a core characteristic of schizophrenia, but its underlying neural mechanisms remain poorly understood. Reduced brain-derived neurotrophic factor (BDNF), a protein critical for ...neural plasticity and synaptic signaling, is one of the few molecules consistently associated with cognitive deficits in schizophrenia although the etiological pathway leading to BDNF reduction in schizophrenia is unclear. We examined microRNA-195 (miR-195), a known modulator of BDNF protein expression, as a potential mechanistic component. One-hundred and eighteen first-episode patients with schizophrenia either antipsychotic medication-naïve or within two weeks of antipsychotic medication exposure and forty-seven age- and sex-matched healthy controls were enrolled. MiR-195 and BDNF mRNA and BDNF protein levels in peripheral blood were tested. Cognitive function was assessed using the MATRICS Consensus Cognitive Battery (MCCB). MiR-195 was significantly higher (p = 0.01) whereas BDNF mRNA (p < 0.001) and protein (p = 0.016) levels were significantly lower in patients compared with controls. Higher miR-195 expression was significantly correlated to lower BDNF protein levels in patients (partial r = -0.28, p = 0.003) and lower BDNF protein levels were significantly associated with poorer overall cognitive performance by MCCB and also in speed of processing, working memory, and attention/vigilance domains composite score (p = 0.002-0.004). The subgroup of patients with high miR-195 and low BDNF protein showed the lowest level of cognitive functions, and miR-195 showed significant mediation effects on cognitive functions through BDNF protein. Elevated miR-195 may play a role in regulating BDNF protein expression thereby influencing cognitive impairments in schizophrenia, suggesting that development of cognition enhancing treatment for schizophrenia may consider a micro-RNA based strategy.
Background
Circular RNA (circRNA) and N6‐methyladenosine (m6A) play a critical role in tumour occurrence and development, including colorectal cancer (CRC). However, little is known about the ...interaction between circRNA and m6A in the radiosensitivity of CRC. Here, we investigated the role of a novel m6A‐regulated circRNA in CRC.
Methods
Differentially expressed circRNAs from radiosensitive and radioresistant CRC tissues were screened. Modifications of the selected circRNAs were examined by methylated RNA immunoprecipitation assay. Finally, the selected circRNAs were subjected to radiosensitivity assay.
Results
We identified that circAFF2 is closely related to both radiosensitivity and m6A in CRC. CircAFF2 was highly expressed in patients with radiosensitive rectal cancer, and patients with high expression of circAFF2 had a better prognosis. In addition, circAFF2 can enhance the radiosensitivity of CRC cells both in vitro and in vivo. The regulation of circAFF2 involves ALKBH5‐mediated demethylation, followed by its recognition and degradation via YTHDF2. Rescue experiments revealed that circAFF2 could reverse the radiosensitivity induced by ALKBH5 or YTHDF2. Mechanistically, circAFF2 binds with CAND1, promotes the binding of CAND1 to Cullin1 and inhibits its neddylation, subsequently impacting the radiosensitivity of CRC.
Conclusion
We identified and characterised circAFF2 as a novel m6A‐modified circRNA and validated the ALKBH5/YTHDF2/circAFF2/Cullin‐NEDD8 axis as a potential radiotherapy target for CRC.
The expression of circAFF2 is regulated by ALKBH5‐mediated demethylation, and YTHDF2 mainly mediates its degradation in an m6A‐dependent manner. CircAFF2 enhanced the radiosensitivity of CRC cells by binding to CAND1 and promoting the interaction of CAND1 with Cullin1, thereby inhibiting neddylation modification in CRC cells.
Objective
Previous studies have implicated intricate interactions between innate immunity and the brain in schizophrenia. Monocytic Toll-like receptor (TLR) 4 signaling, a crucial “sensor” of innate ...immunity, was reported to be over-activated in link with cognitive impairment in schizophrenia. As TLR4 is predominantly expressed on gliocytes prior to expression in neurons, we hypothesized that higher TLR4 levels may contribute to cognitive deterioration by affecting white matter microstructure.
Methods
Forty-four patients with stable chronic schizophrenia (SCS) and 59 healthy controls (HCs) were recruited in this study. The monocytic function was detected with lipopolysaccharide (LPS) stimulation to simulate bacterial infection. Basal and LPS- stimulated levels of TLR4, nuclear factor-kappa B (NF-κB), and interleukin (IL)-1β were quantified with flow cytometry. Cognitive function was assessed by the MATRICS Consensus Cognitive Battery (MCCB) and psychopathological symptoms were evaluated by the Positive and Negative Syndrome Scale (PANSS). We employed diffusion tensor imaging with a 3-T scanner and evaluated white-matter integrity with fractional anisotropy (FA). Subcortical volume and cortical thickness were also assessed.
Results
The TLR4/NF-κB/IL-1β signaling pathway was activated in patients with SCS, but responded sluggishly to LPS stimulation when compared with HCs. Furthermore, monocytic TLR4 expressions were inversely correlated with cognitive function and white matter FA, but not with cortical thickness or subcortical gray matter volume in schizophrenia.
Conclusion
Our findings support altered TLR4 signaling pathway activity in association with deficits in cognition and white matter integrity in schizophrenia.
A stable Chlorella zofingiensis mutant (E17) produced by chemical mutagen was characterized with respect to growth, astaxanthin biosynthesis, and phytoene desaturation. The mutant E17 could grow well ...and produce normal levels of colored carotenoids in the presence of 0.25 μM norflurazon, in which the growth of wild type (WT) cells was greatly limited due to inhibited carotenoid formation. Induced by high-light irradiation or glucose, E17 produced 44 or 36% more astaxanthin than WT when cultured in media without norflurazon. A point mutation (C—T) was revealed to occur in the PDS gene of E17, leading to an amino acid change (L516F) in its coding region. The mutated PDS exhibited 31-fold resistance to norflurazon when compared to WT as determined by an in vitro assay. Surprisingly, the mutated PDS exhibited higher efficiency in converting phytoene to ζ-carotene. No difference in PDS transcripts was found between E17 and WT cells cultured either in normal or induced conditions. In contrast, higher transcript levels of β-carotene ketolase and hydroxylase were found in the E17 cells. Taken together, we conclude that a point mutation in Chlorella PDS gene makes E17 resistant to norflurazon and synthesize higher amounts of carotenoids including astaxanthin.
Nutrient supplementation is common in microalgae cultivation to enhance the accumulation of biomass and biofunctional products, while the recovery mechanism from nutrient starvation is less ...investigated. In this study, the influence of remodeled carbon metabolism on cell cycle progression was explored by using different light wavelengths under N-repletion and N-recovery. The results suggested that blue light enhanced cell enlargement and red light promoted cell division under N-repletion. On the contrary, blue light promoted cell division by stimulating cell cycle progression under N-recovery. This interesting phenomenon was ascribed to different carbon metabolisms under N-repletion and N-recovery. Blue light promoted the recovery of photosystem II and redirected carbon skeletons into proteins under N-recovery, which potentially accelerated cell recovery and cell cycle progression. Although red light also facilitated the recovery of photosystem II, it mitigated the degradation of polysaccharide and then arrested almost all the cells in the G1 phase. By converting light wavelengths at the 12 h of N-recovery with blue light, red and white lights were proved to increase biomass concentration better than continuous blue light. These results revealed different mechanisms of cell metabolism of Chlamydomonas reinhardtii during N-recovery and could be applied to enhance cell vitality of microalgae from nutrient starvation and boost biomass production.
Combining C 4 D technique and cross-correlation velocity measurement technique, a new measurement method, which is suitable for the bubble/slug velocity measurement in millimeter-scale pipelines, is ...proposed. Based on the series resonance principle and the simulated inductor technique, a new C 4 D sensor is developed. With two conductance signals obtained by two new C 4 D sensors (the upstream sensor and the downstream sensor), the bubble/slug velocity measurement is implemented by the cross-correlation velocity measurement technique. Experiments are carried out in three pipelines with different inner diameters of 4.50, 5.46, and 6.44 mm, respectively. The experimental results show that the proposed bubble/slug velocity measurement method is effective, the development of the new C 4 D sensor is successful, and the velocity measurement accuracy is satisfactory. The relative error of bubble velocity measurement is less than 5.41% and the relative error of slug flow velocity measurement is less than 4.90%.
Microalgae have potential for eco-friendly chemicals, however, only a few of them have been exploited. This study investigated four new microalgae on their growth and production of fatty acids and ...carotenoids grown photoautotrophically, heterotrophically, or mixotrophically using improved techniques to monitor glucose metabolism, carotenoid and lipid formation. Depending on trophic modes, the microalgae demonstrated different growth rates, ranging from 0.23 d−1 of photoautotrophic Selenastraceae sp. B10 to 1.03 d−1 of heterotrophic Pectinodesmus sp. F13. Scenedesmus sp. DHS gained the highest biomass due to its fastest glucose consumption. Heterotrophic Selenastraceae sp. B10 accumulated the highest amounts of lutein (7.49 mg g−1) and lipids (63.15% of DCW), while mixotrophic Pectinodesmus sp. F13 achieved the highest productivity of lutein (5.60 mg L−1 d−1). Photoautotrophic Chlorella sp. Mg exhibited the highest production of α-linolenic acid (37.19% of total fatty acids). Taken together, the studied microalgae have great potential as feedstock for commercially attractive production of lipids or/and lutein.
•A Nile Red staining based technique was established for monitoring algal lipids.•Glucose stimulated the algae to produce lipids and carotenoids.•Selenastraceae sp. has potential for the coproduction of lutein and biodiesel.•Chlorella sp. Mg synthesizes high amounts of α-linolenic acid.
Multi-channel chitosan–polycaprolactone (CH–PCL)/collagen conduits were fabricated for potential applications in long-gap peripheral nerve repair. CH–PCLs with various PCL percentages changing from ...around 30 to 45 wt% were used for the fabrication of conduits, and the collagen content in the conduits was controlled at about 8 wt% or less in order to ensure the required mechanical strength and degradation rate of the resulting conduits. The porosity and average channel diameter of the conduits with a dimension of around 5 mm in outer diameter and 30 mm in length were optimized as around 80% and 200 μm, respectively. Swelling index, compressive load, deformation recovery and bending stiffness of the conduits were measured, respectively. In vitro degradation measurements was conducted in phosphate buffer saline, and results revealed that the effect of collagen content on the degradation rate of the conduits was not significant until the degradation time reached around 6 weeks. After being implanted into rabbits for various durations, the degradation of the conduits appeared to be strongly dependent on the collagen content in addition to the dependence on the degradation time. After 10-week in vivo degradation, some conduits that contained 6 wt% or less content of collagen still showed shape integrity and required compressive mechanical properties, suggesting that the degradation rate of the conduits can be effectively regulated by the collagen content while the required properties for the conduits would be well maintained.
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