生物学最新文献

{"title":"Real-time imaging reveals a role for macrophage protrusive motility in melanoma invasion.","authors":"Gayathri Ramakrishnan, Veronika Miskolci, Miranda Hunter, Morgan A Giese, Daniela Münch, Yiran Hou, Kevin W Eliceiri, Michael R Lasarev, Richard M White, Anna Huttenlocher","doi":"10.1083/jcb.202403096","DOIUrl":"10.1083/jcb.202403096","url":null,"abstract":"<p><p>Macrophages are primary cells of the innate immune system that mediate tumor progression. However, the motile behavior of macrophages and interactions with tumor cells are not well understood. Here, we exploit the optical transparency of larval zebrafish and perform real-time imaging of macrophage-melanoma interactions. We found that macrophages are highly motile in the tumor microenvironment. Macrophages extend dynamic projections between tumor cells that precede invasive melanoma migration. Modulating macrophage motility with a dominant inhibitory mutation in Rac2 inhibits recruitment to the tumor and impairs tumor invasion. However, a hyperactivating mutation in Rac2 does not affect macrophage recruitment but limits macrophage projections into the melanoma mass and reduces invasive melanoma cell migration. Taken together, these findings reveal a role for Rac2-mediated macrophage protrusive motility in melanoma invasion.</p>","PeriodicalId":15211,"journal":{"name":"Journal of Cell Biology","volume":"224 2","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11586626/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142681870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neuronal constitutive endolysosomal perforations enable α-synuclein aggregation by internalized PFFs.","authors":"Anwesha Sanyal, Gustavo Scanavachi, Elliott Somerville, Anand Saminathan, Athul Nair, Ricardo F Bango Da Cunha Correia, Beren Aylan, Ewa Sitarska, Athanasios Oikonomou, Nikos S Hatzakis, Tom Kirchhausen","doi":"10.1083/jcb.202401136","DOIUrl":"https://doi.org/10.1083/jcb.202401136","url":null,"abstract":"<p><p>Endocytosis, required for the uptake of receptors and their ligands, can also introduce pathological aggregates such as α-synuclein (α-syn) in Parkinson's Disease. We show here the unexpected presence of intrinsically perforated endolysosomes in neurons, suggesting involvement in the genesis of toxic α-syn aggregates induced by internalized preformed fibrils (PFFs). Aggregation of endogenous α-syn in late endosomes and lysosomes of human iPSC-derived neurons (iNs), seeded by internalized α-syn PFFs, caused the death of the iNs but not of the parental iPSCs and non-neuronal cells. Live-cell imaging of iNs showed constitutive perforations in ∼5% of their endolysosomes. These perforations, identified by 3D electron microscopy in iNs and CA1 pyramidal neurons and absent in non-neuronal cells, may facilitate cytosolic access of endogenous α-syn to PFFs in the lumen of endolysosomes, triggering aggregation. Inhibiting the PIKfyve phosphoinositol kinase reduced α-syn aggregation and associated iN death, even with ongoing PFF endolysosomal entry, suggesting that maintaining endolysosomal integrity might afford a therapeutic strategy to counteract synucleinopathies.</p>","PeriodicalId":15211,"journal":{"name":"Journal of Cell Biology","volume":"224 2","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142877267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Functional improvements in β-conglycinin by preparing bioconjugates with carboxymethyl cellulose.","authors":"Yui Hataishi, Aya Tanaka, Misaki Ishizuka, Hibine Mizobuchi, Tadashi Yoshida, Makoto Hattori","doi":"10.1007/s10616-024-00664-9","DOIUrl":"10.1007/s10616-024-00664-9","url":null,"abstract":"<p><p>β-Conglycinin was conjugated with carboxymethyl cellulose (CMC) by using water-soluble carbodiimide to improve its function. Two kinds of CMC differing in average molecular weight (about 1 kDa and 90 kDa) were used to investigate the relationship between molecular weight of conjugated saccharide and saccharide content in the conjugates and degree of functional changes in β-conglycinin. The β-conglycinin-CMC conjugates were purified by dialysis using a dialysis membrane whose molecular weight cutoff is 100 kDa. Composition of the β-conglycinin-low molecular weight (LMW) CMC and β-conglycinin-high molecular weight (HMW) CMC was β-conglycinin: CMC = 1:3.3 and 1:2.1 (weight ratio) respectively which was confirmed by BCA method and phenol sulfuric acid method. Conjugation was confirmed by SDS-PAGE with CBB. Solubility of β-conglycinin in the range of pH4.0-7.0 was much improved by conjugation with both LMW and HMW CMC. Emulsifying property of β-conglycinin at pH5.0 and pH7.0 was much improved by conjugation with HMW CMC and greater improvement was achieved by conjugation with LMW CMC. Immunogenicity of β-conglycinin was decreased by conjugation with LMW CMC.</p>","PeriodicalId":10890,"journal":{"name":"Cytotechnology","volume":"77 1","pages":"6"},"PeriodicalIF":2.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11582224/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142709406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Drug repurposing opportunities for breast cancer and seven common subtypes.","authors":"Yilong Lin, Songsong Wang, Yun Zhang, Jing She, Yue Zhang, Ruidan Zhao, Zhongquan Qi, Ruiqin Yang, Liyi Zhang, Qingmo Yang","doi":"10.1016/j.jsbmb.2024.106652","DOIUrl":"10.1016/j.jsbmb.2024.106652","url":null,"abstract":"<p><p>Breast cancer is a substantial global health problem, and drug repurposing provides novel opportunities to address the urgent need for therapeutics. According to significant Mendelian randomization (MR) results, we identified 26 genes for overall breast cancer, 25 genes for ER+ breast cancer and 4 genes (CASP8, KCNN4, MYLK4, TNNT3) for ER- breast cancer. In order to explore the differences between 5 intrinsic subtypes, we found 29 actionable druggable genes for Luminal A breast cancer, 2 genes (IGF2 and TNNT3) for Luminal B breast cancer, 1 gene (FAAH) for Luminal B HER2 negative breast cancer, and 3 genes (CASP8, KCNN4, and TP53) for triple-negative breast cancer. After colocalization analysis, we determined OPRL1 as a prioritized target in both overall and Luminal A breast cancer. Additionally, FES and FAAH were considered prioritized targets for ER+ breast cancer. Through molecular docking, crizotinib stand out as a prioritized FES target drug repurposing opportunity with the lowest binding energy (-10.13 kJ·mol^-1) and CCK-8 assay showed ER+ cell groups were more sensitive to crizotinib than ER- cell groups. In conclusion, OPRL1 was identified as a prioritized target for both overall and Luminal A breast cancer. Moreover, FES and FAAH were recognized as prioritized targets for ER+ breast cancer.</p>","PeriodicalId":51106,"journal":{"name":"Journal of Steroid Biochemistry and Molecular Biology","volume":" ","pages":"106652"},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142774642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Yinjia pills inhibits the malignant biological behavior of HeLa cells through PKM2-medicated inhibition of JAK/STAT3 pathway.","authors":"Ying Shi, Xiaoli Min, Yi Li, Lihua Guo, Zheng Cai, Dongge Li, Xueying Jiang, Ni Feng, Xiaolin Li, Xiaoxia Yang","doi":"10.1007/s10616-024-00668-5","DOIUrl":"10.1007/s10616-024-00668-5","url":null,"abstract":"<p><p>Cervical cancer is one of the most common tumors in women and is a major problem in gynecological health. Studies have shown that Yinjia pills (YJP), a traditional Chinese medicine, can effectively slow the progression of cervical cancer. Therefore, this study mainly explored the molecular mechanism by which YJP delays the progression of cervical cancer. The expression level of PKM2 in cervical cancer was evaluated by the gene expression profiling interactive analysis (GEPIA) database, and the prognostic value of the PKM2 gene was evaluated by the Kaplan‒Meier plotter database. HeLa cervical cancer cells were treated with different concentrations of YJP (2.5, 5, 10, and 20 mg/mL). The levels of the inflammatory factors were detected by ELISA. Cell proliferation activity, migration and invasion were detected by CCK-8 assay, Transwell assays and cell scratch experiment. Apoptosis was detected by flow cytometry. Western blotting was used to detect the expression of proteins. In this study, PKM2 was upregulated in both cervical squamous cell carcinoma (CESC) and endometrial adenocarcinoma tissues, and a Kaplan‒Meier analysis showed that higher PKM2 expression was associated with lower patient survival. YJP inhibited the proliferation, migration and invasion of HeLa cells in a dose-dependent manner, promoted the apoptosis of HeLa cells, and inhibited the expression of inflammatory factors. In addition, YJP inhibited the activation of the JAK/STAT3 pathway and the occurrence of EMT. Knockdown of PKM2 also inhibited the malignant biological behavior of HeLa cells, but overexpression of PKM2 weakened the inhibitory effect of YJP on the malignant biological behavior of HeLa cells. Angoline, a JAK/STAT3 pathway inhibitor, attenuated the effect of PKM2 overexpression on the efficacy of YJP. In conclusion, YJP can inhibit the activation of the JAK/STAT3 pathway by regulating PKM2, thereby inhibiting the malignant biological behavior of HeLa cells.</p>","PeriodicalId":10890,"journal":{"name":"Cytotechnology","volume":"77 1","pages":"5"},"PeriodicalIF":2.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11579276/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142686038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High mobility group protein N2 inhibits the progression of hepatocellular carcinoma and the related molecular mechanisms.","authors":"Gang Li, Guanbo Zhang, Jinsong Li, Jie Zhang, Zhi Yang, Lin Yang, Jiaxing Wang","doi":"10.1007/s10616-024-00678-3","DOIUrl":"10.1007/s10616-024-00678-3","url":null,"abstract":"<p><p>High mobility group protein N2 (HMGN2) related pathways are involved in chromatin regulation/acetylation. It has been reported to be involved in several types of cancers. A recent sequencing study suggested that HMGN2 might be involved in the progression of hepatocellular carcinoma (HCC). This study aimed to explore the role of HMGN2 in HCC, which has been proven to be involved in the development of HCC. In this study, we collected clinical samples and cultured normal hepatocytes and hepatocellular carcinoma cell lines to detect HMGN2 expression levels using reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) and western blot assay. Subsequently, to determine the role of HMGN2 in HCC, HMGN2 was overexpressed in HCC cell lines. MTT (3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di- phenytetrazoliumromide) assay was used to detect the cell proliferative capacity, and proliferation-related proteins were detected by RT-qPCR and western blot assay. To observe the effect of HMGN2 on cell migration and invasion capacity, Transwell assay was performed. Then, cell apoptosis was detected by flow cytometry, and caspase3 and cleaved-caspase3 were detected using western blot assay. Finally, EMT (epithelial to mesenchymal transition)-related proteins, and matrix metalloproteinase-2 (MMP-2) and MMP-9 expression were detected by RT-qPCR and western blot assay. HMGN2 expression was decreased in HCC tissues as well as in HCC cell lines. After overexpression of HMGN2, MTT results suggested that cell proliferation was decreased, and flow cytometry results showed that the apoptosis level was increased and ki-67 and proliferating cell nuclear antigen (PCNA) expression levels were decreased. On the contrary, cleaved-caspase 3 expression level was increased. HCC cells overexpressing HMGN2 showed a drastic reduction in the number of migrating and invading cells, and the expression levels of MMP-2 and MMP-9 were significantly decreased. Finally, E-cadherin expression was elevated in HCC cells transfected with the HMGN2-plasmid, while N-cadherin showed the opposite result. HMGN2 expression was significantly decreased in patients with HCC. HMGN2 inhibits the malignant behavior of HCC cells and is a potential therapeutic target for HCC.</p>","PeriodicalId":10890,"journal":{"name":"Cytotechnology","volume":"77 1","pages":"20"},"PeriodicalIF":2.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11638430/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142827676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The impact of graphene quantum dots on osteogenesis potential of Wharton's jelly mesenchymal stem cells in fibrin hydrogel scaffolds.","authors":"Kaveh Khazaeel, Abbas Sadeghi, Fatemeh Khademi Moghaddam, Tayebeh Mohammadi","doi":"10.1007/s10616-024-00672-9","DOIUrl":"10.1007/s10616-024-00672-9","url":null,"abstract":"<p><p>Bone tissue engineering is a promising approach to overcome the limitations of traditional autograft bone transplantation. Graphene quantum dots (GQDs) have been suggested as an enhancement for osteogenic differentiation. This study aimed to investigate the ability of the fibrin hydrogel scaffold in the presence of graphene quantum dots to promote osteogenic differentiation of human Wharton's jelly-derived mesenchymal stem cells (hWJ-MSCs). The hWJ-MSCs were isolated from the Wharton's jelly of the human umbilical cord using a mechanical method. Fibrin hydrogel scaffolds were prepared by mixing 15 µl of thrombin solution with fibrinogen solution. GQDs were incorporated into the scaffolds at concentrations of 0, 5, and 10 µg/ml. Cell viability was determined through DAPI staining and the MTT assay. Osteogenic differentiation was assessed by measuring alkaline phosphatase (ALP) activity, quantifying calcium deposition using Alizarin Red S staining, and analyzing the gene expression of BGLAP, COL1A1, Runx-2 and ALP via qPCR. Scanning electron microscopy (SEM) was employed to analyze the scaffold architecture. SEM analysis revealed that the fibrin hydrogel exhibited a suitable architecture for tissue engineering, and DAPI staining confirmed cell viability. The MTT results indicated that the GQDs and fibrin hydrogel scaffold exhibited no cytotoxic effects. Furthermore, the incorporation of GQDs at a concentration of 10 µg/ml significantly enhanced ALP activity, calcium deposition, and the expression of osteogenesis-related genes compared to the control. The findings suggest that the combination of fibrin hydrogel and GQDs can effectively promote the osteogenic differentiation of hWJ-MSCs, contributing to the advancement of bone tissue engineering.</p>","PeriodicalId":10890,"journal":{"name":"Cytotechnology","volume":"77 1","pages":"14"},"PeriodicalIF":2.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11628478/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142812660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Triptolide attenuates LPS-induced chondrocyte inflammation by inhibiting inflammasome activation via the Wnt/β-catenin and NF-κB signaling pathways.","authors":"Hangchu Shi, Qiming Liu, Wang He, Xuming Ma, Xiaoqiang Shen, Yang Zou","doi":"10.1007/s10616-024-00680-9","DOIUrl":"10.1007/s10616-024-00680-9","url":null,"abstract":"<p><p>Osteoarthritis (OA) is a common form of arthritis characterized by subchondral bone proliferation and articular cartilage degeneration. Recently, the Nod-like receptor pyrin domain 3 (NLRP3) inflammasome has gained attention due to its association with synovial inflammation in OA. Triptolide (TP), known for its immunosuppressive and anti-inflammatory effects, has been studied in various diseases. However, the specific impact of TP on OA and its underlying mechanism remains largely unexplored. In this study, chondrocytes were treated with a specific concentration of TP, and subsequent analysis through Western blotting and immunofluorescence staining revealed decreased expression levels of MMP-13, NLRP3, Caspase-1, ASC, β-catenin, p-p65, and IκB compared to the model group. ELISA results demonstrated significantly lower levels of IL-1β, IL-18, and TNF-α in the TP treatment group compared to the model group. In addition, triptolide ameliorates the degradation of the extracellular matrix (ECM) by enhancing the expression of collagen-II. In conclusion, our findings suggest that TP exhibits anti-inflammatory effects on chondrocytes in the presence of LPS-induced inflammation by inhibiting the activation of the NLRP3 inflammasome via the Wnt/β-catenin and NF-κB pathway. These results contribute to a better understanding of TP's potential therapeutic benefits in managing OA.</p>","PeriodicalId":10890,"journal":{"name":"Cytotechnology","volume":"77 1","pages":"13"},"PeriodicalIF":2.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11628479/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142812661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The CaCo-2 cell junction derangement exerted by the single addition of oxysterols commonly detected in foods is markedly quenched when they are in mixture.","authors":"Noemi Iaia, Federico Canzoneri, Fiorella Biasi, Giuseppe Poli, Roberto Menta, Gabriella Testa, Paola Gamba","doi":"10.1016/j.jsbmb.2024.106648","DOIUrl":"10.1016/j.jsbmb.2024.106648","url":null,"abstract":"<p><p>The selective permeability of the gut epithelial barrier is heavily reliant on the stability of cell junctions, often challenged by a variety of dietary stressors, including non-enzymatic cholesterol oxidation products (COPs). A marked decrease of the tight junctions claudin-1 and occludin, and of the adherens junction E-cadherin was previously detected in differentiated CaCo-2 monolayers challenged by a single addition of 7β-hydroxycholesterol (7βOHC) or 7-ketocholesterol (7KC) in the lowest micromolar range. However, in the diet, oxysterols are occurring in a mixture. Hence, the aim of the present study was to evaluate whether cell incubation with all the main dietary COPs together quench the intercellular junction derangement previously observed as exerted by 7βOHC and 7KC singularly added. Two chocolate prototypes, respectively made with fresh (oxy-Mix1) or six-months stored whole milk powder (oxy-Mix2), were compared. The second prototype showed an almost double content of total COPs (3.34 µM, approximately 1337 ng /g of chocolate) than the first one (1.69 µM, approximately 675 ng /g of chocolate). Importantly, even in the CaCo-2 cell monolayers treated with six-months stored mixture of COPs oxy-Mix2, no alterations were observed of those cell junctions markedly affected by identical concentration of 7βOHC or 7KC used alone. The junctions' derangement started to be significantly evident when oxy-Mix2 was used at higher concentration (5 µM, approximately 2 µg oxysterols/g of product) or when treatments were carried out with repeated doses of oxy-Mix2 every 24 hours. Although achieved in a still widely adopted in vitro model system, these findings could orientate the definition of a safe shelf-life for dairy products, certainly for milk chocolate.</p>","PeriodicalId":51106,"journal":{"name":"Journal of Steroid Biochemistry and Molecular Biology","volume":" ","pages":"106648"},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142755806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adaptive significance of age- and light-related variation in needle structure, photochemistry, and pigments in evergreen coniferous trees.","authors":"James Oluborode, Tamara Chadzinikolau, Magda Formela-Luboińska, Zi-Piao Ye, Piotr Robakowski","doi":"10.1007/s11120-024-01125-2","DOIUrl":"https://doi.org/10.1007/s11120-024-01125-2","url":null,"abstract":"<p><p>Evergreen conifers thrive in challenging environments by maintaining multiple sets of needles, optimizing photosynthesis even under harsh conditions. This study aimed to investigate the relationships between needle structure, photosynthetic parameters, and age along the light gradient in the crowns of Abies alba, Taxus baccata, and Picea abies. We hypothesized that: (1) Needle structure, photochemical parameters, and photosynthetic pigment content correlate with needle age and light levels in tree crowns. (2) The photosynthetic capacity of ageing needles would decline and adjust to the increasing self-shading of branches. Our results revealed a non-linear increase in the leaf mass-to-area ratio. The maximum quantum yield of photosystem II photochemistry decreased linearly with needle age without reaching levels indicative of photoinhibition. Decreased maximum electron transport rates (ETR_max) were linked to declining values of saturating photosynthetic photon flux density and increasing non-photochemical quenching of fluorescence (NPQ), indicating energy losses as heat. The chlorophyll a to chlorophyll b ratio linearly decreased, suggesting older needles sustain high light capture efficiency. These findings offer new insights into the combined effects of needle ageing and self-shading on photochemistry and pigment content. This functional needle balance highlights the trade-off between the costs of long-term needle retention and the benefits of efficient resource utilization. In environments where air temperature is less of a constraint on photosynthesis due to climate warming, evergreen coniferous trees could sustain or enhance their photosynthetic capacity. They can achieve this by shortening needle lifespan and retaining fewer cohorts of needles with higher ETR_max and lower NPQ compared to older needles.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 1","pages":"1-14"},"PeriodicalIF":2.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142865127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}