Microalgae possess high photosynthetic efficiency, robust adaptability, and substantial biomass, serving as excellent biological resources for large-scale cultivation. Malic enzyme (ME), a ubiquitous metabolic enzyme in living organisms, catalyzes the decarboxylation of malate to produce pyruvate, CO₂, and NAD(P)H, playing a role in multiple metabolic pathways including energy metabolism, photosynthesis, respiration, and biosynthesis. In this study, we identified the Scenedesmus quadricauda malic enzyme gene (SqME) and its biological functions, aiming to provide excellent target genes for the genetic improvement of higher plants. Based on the RNA-seq data from S. quadricauda under the biofilm cultivation mode with high CO₂ and light energy transfer efficiency and small water use, a highly expressed gene (SqME) functionally annotated as ME was cloned. The physicochemical properties of the SqME-encoded protein were systematically analyzed by bioinformatics tools. The subcellular localization of SqME was determined via transient transformation in Nicotiana benthamiana leaves. The biological functions of SqME were identified via genetic transformation in Nicotiana tabacum, and the potential of SqME in the genetic improvement of higher plants was evaluated. The ORF of SqME was 1 770 bp, encoding 590 amino acid residues, and the encoded protein was located in chloroplasts. SqME was a NADP-ME, with the typical structural characteristics of ME. The ME activity in the transgenic N. tabacum plant was 1.8 folds of that in the wild-type control. Heterologous expression of SqME increased the content of chlorophyll a, chlorophyll b, and total chlorophyll by 20.9%, 26.9%, and 25.2%, respectively, compared with the control. The transgenic tobacco leaves showed an increase of 54.0% in the fluorescence parameter NPQ and a decrease of 30.1% in Fo compared with the control. Moreover, the biomass, total lipids, and soluble sugars in the transgenic tobacco leaves enhanced by 20.5%, 25.7%, and 9.5%, respectively. On the contrary, the starch and protein content in the transgenic tobacco leaves decreased by 22.4% and 12.2%, respectively. Collectively, the SqME-encoded protein exhibited a strong enzymatic activity. Heterologous expressing of SqME could significantly enhance photosynthetic protection, photosynthesis, and biomass accumulation in the host. Additionally, SqME can facilitate carbon metabolism remodeling in the host, driving more carbon flux towards lipid synthesis. Therefore, SqME can be applied in the genetic improvement of higher plants for enhancing photosynthetic carbon fixation and lipid accumulation. These findings provide scientific references for mining of functional genes from S. quadricauda and application of these genes in the genetic engineering of higher plants.
Nicotiana/genetics* ; Photosynthesis/physiology* ; Malate Dehydrogenase/biosynthesis* ; Plant Leaves/genetics* ; Scenedesmus/enzymology* ; Carbon Cycle/genetics* ; Lipid Metabolism/genetics* ; Plants, Genetically Modified/metabolism*

This paper reviews the status quo of recent years’ research on autophagy and damage of chondrocytes in Kashin-Beck disease （KBD） and osteoarthritis （OA）. PI3K/AKT signaling pathway and mTOR regulate the autophagy activity of chondrocytes. PI3K/AKT signaling pathway can promote the proliferation of chondrocytes and cause their damage by inhibiting their autophagy activity. This might play an important role in the occurrence and progression of bone and joint diseases such as KBD and OA， and provide scientific basis for revealing the pathogenesis and treatment plan of them.

Chondroitin sulfate (CS) is a sulfurated glycosaminoglycan, a major component of the extracellular matrix, widely distributed in skin, cartilage and vascular tissue. CS plays an important role in the physiological state regulation of articular cartilage, which affects tensile strength and elasticity of tissues by influencing aggrecan. Previous studies have shown that CS sulfate modification may be related to the growth and development disorders of cartilage tissue and the occurrence of osteoarticular diseases. At the same time, CS is also a common joint supplement, often used in the treatment of osteoarthritis and Kashin-Beck disease. In this paper, the research progress of CS sulfate modification characteristics in Kashin-Beck disease and osteoarthritis and the application of the preparation in the treatment of Kashin-Beck disease and osteoarthritis are reviewed, aiming to provide help for the investigation of the etiology of Kashin-Beck disease and the treatment of osteoarthritis and Kashin-Beck disease.

Objective To investigate the clinical effect of calcium hydroxide in the treatment of dental pulp diseases. Methods The control group in the treatment of the conventional mummification agent, the study group used calcium hydroxide in the treatment process, compared the two groups of clinical curative effect, dental pulp disease patients the incidence of adverse reactions. Results The study group of dental pulp disease in patients with clinical total efficiency up to 92.00％, the control group of dental pulp disease in patients with clinical total effective rate was only 72.00％, the difference between the two groups was statistically significant(P<0.05).After the treatment of different measures, the incidence of adverse reactions in the study group (8.00％) was significantly lower than that in the control group(28.00％), the difference between the two groups was statistically significant (P<0.05). Conclusion The use of calcium hydroxide in the treatment of patients with dental pulp disease can significantly improve the clinical efficacy, and help to protect the quality of life of patients, physical and mental health.