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1.
Bioorg Chem ; 147: 107329, 2024 Apr 03.
Artículo en Inglés | MEDLINE | ID: mdl-38608410

RESUMEN

By co-culturing two endophytic fungi (Chaetomium virescens and Xylaria grammica) collected from the medicinal and edible plant Smilax glabra Roxb. and analyzing them with MolNetEnhancer module on GNPS platform, seven undescribed chromone-derived polyketides (chaetoxylariones A-G), including three pairs of enantiomer ones (2a/2b, 4a/4b and 6a/6b) and four optical pure ones (1, 3, 5 and 7), as well as five known structural analogues (8-12), were obtained. The structures of these new compounds were characterized by NMR spectroscopy, single-crystal X-ray diffraction, 13C NMR calculation and DP4+ probability analyses, as well as the comparison of the experimental electronic circular dichroism (ECD) data. Structurally, compound 1 featured an unprecedented chromone-derived sulfonamide tailored by two isoleucine-derived δ-hydroxy-3-methylpentenoic acids via the acylamide and NO bonds, respectively; compound 2 represented the first example of enantiomeric chromone derivative bearing a unique spiro-[3.3]alkane ring system; compound 3 featured a decane alkyl side chain that formed an undescribed five-membered lactone ring between C-7' and C-10'; compound 4 contained an unexpected highly oxidized five-membered carbocyclic system featuring rare adjacent keto groups; compound 7 featured a rare methylsulfonyl moiety. In addition, compound 10 showed a significant inhibition towards SW620/AD300 cells with an IC50 value of PTX significantly decreased from 4.09 µM to 120 nM, and a further study uncovered that compound 10 could obviously reverse the MDR of SW620/AD300 cells.

2.
Nat Commun ; 14(1): 6972, 2023 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-37914724

RESUMEN

Lichens are of great ecological importance but mechanisms regulating lichen symbiosis are not clear. Umbilicaria muhlenbergii is a lichen-forming fungus amenable to molecular manipulations and dimorphic. Here, we established conditions conducive to symbiotic interactions and lichen differentiation and showed the importance of UMP1 MAP kinase in lichen development. In the initial biofilm-like symbiotic complexes, algal cells were interwoven with pseudohyphae covered with extracellular matrix. After longer incubation, fungal-algal complexes further differentiated into primitive lichen thalli with a melanized cortex-like and pseudoparenchyma-like tissues containing photoactive algal cells. Mutants deleted of UMP1 were blocked in pseudohyphal growth and development of biofilm-like complexes and primitive lichens. Invasion of dividing mother cells that contributes to algal layer organization in lichens was not observed in the ump1 mutant. Overall, these results showed regulatory roles of UMP1 in symbiotic interactions and lichen development and suitability of U. muhlenbergii as a model for studying lichen symbiosis.


Asunto(s)
Ascomicetos , Líquenes , Simbiosis/fisiología , Ascomicetos/fisiología , Diferenciación Celular , Filogenia
3.
Org Biomol Chem ; 21(34): 6949-6955, 2023 08 30.
Artículo en Inglés | MEDLINE | ID: mdl-37581482

RESUMEN

Euphorlactone A (1), a rare rearranged ent-atisane norditerpenoid with an undescribed 3-nor-2,4-olide-ent-atisane scaffold, and euphorlactone B (2), a new ent-atisane diterpenoid with an unprecedented seven-membered lactone ring C, were isolated from the roots of Euphorbia fischeriana. Their planar structures with absolute configurations were extensively elucidated by analysis of 1D and 2D NMR data, electronic circular dichroism (ECD) calculations, Rh2(OCOCF3)4-induced ECD curves, and single-crystal X-ray diffraction. Euphorlactone A (ELA) showed a remarkable AChE (acetylcholinesterase) inhibitory activity (IC50 = 2.13 ± 0.06 µM and Ki = 0.058 µM), which was five times stronger than that of the positive control (rivastigmine, IC50 = 12.46 ± 0.82 µM), and further in vitro enzyme inhibition kinetic analysis and molecular docking studies were performed to investigate the AChE inhibitory mechanism.


Asunto(s)
Diterpenos , Euphorbia , Euphorbia/química , Simulación del Acoplamiento Molecular , Acetilcolinesterasa , Cinética , Diterpenos/química , Raíces de Plantas/química , Estructura Molecular
4.
Front Pharmacol ; 14: 1224906, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37456754

RESUMEN

Acute lung injury (ALI) is an inflammatory condition and there are no effective treatments. A novel new compound----colchicine-myricetin hybrid (CMyrH) was herein designed and synthesized. To evaluate the activity of CMyrH in ALI, we used a bleomycin (BLM) induced BEAS-2B injury model in vitro and established a well-recognized rat model of BLM-induced lung injury in vivo. The results demonstrated that colchicine-myricetin hybrid protected BEAS-2B cells against BLM-induced cell injury in an increased dose manner, and reduced wet/dry weight ratio, histological scoring, and inflammation cytokines IL-1ß, IL-6, IL-18, and TNF-α levels of lung tissue of the rats. Furthermore, we found colchicine-myricetin hybrid inhibited caspase-1, ASC, GSDMD, and NLRP-3 expression in vivo. Meanwhile, we used molecular docking to analyze the binding mode of colchicine-myricetin hybrid and human neutrophil elastase (HNE), it revealed that colchicine-myricetin hybrid showed strong binding affinity toward human neutrophil elastase when compared to its parent molecules. In conclusion, It is suggested that colchicine-myricetin hybrid antagonized acute lung injury by focusing on multi-targets via multi-mechanisms, and might be served as a potential therapeutic agent for acute lung injury.

5.
Math Biosci Eng ; 20(6): 11482-11501, 2023 Apr 28.
Artículo en Inglés | MEDLINE | ID: mdl-37322991

RESUMEN

How to improve the robustness to resist attacks and how to adaptively match the key parameters of the watermarking algorithm with the performance requirements to achieve the best performance in different applications are two hot issues in the research of audio watermarking algorithms. An adaptive and blind audio watermarking algorithm based on dither modulation and butterfly optimization algorithm (BOA) is proposed. Based on the convolution operation, a stable feature is designed to carry the watermark, which will improve the robustness by means of the stability of this feature to prevent the watermark loss. Blind extraction will be achieved only by comparing the feature value and the quantized value without the original audio. The BOA is used to optimize the key parameters of the algorithm which can be matched with the performance requirements by coding the population and constructing the fitness function. Experimental results confirm that this proposed algorithm can adaptively search for the optimal key parameters that match the performance requirements. Compared with other related algorithms in recent years, it exhibits strong robustness against various signal processing attacks and synchronization attacks.


Asunto(s)
Seguridad Computacional , Interpretación de Imagen Asistida por Computador , Interpretación de Imagen Asistida por Computador/métodos , Algoritmos , Procesamiento de Señales Asistido por Computador
6.
Bioorg Chem ; 135: 106482, 2023 06.
Artículo en Inglés | MEDLINE | ID: mdl-36947936

RESUMEN

The arthropod-associated fungi have been demonstrated to be a remarkable producer of structurally captivating and bioactive secondary metabolites for drug discovery. In this study, eleven new indoloquinazoline alkaloids, namely aspergilloids A-K (1-11), along with five known congeners (12-16), were obtained from fungus Aspergillus clavatonanicus, which was isolated from the gut of a centipede collected in our Tongji campus. All these compounds were rarely defined by a 6/5/5 indolone ring system in conjugation with a five-membered spiral ring (1-5 and 10-16) or an opening five-membered spiral ring (6-9). Their structures were elucidated by widespread spectroscopic analyses, mainly including HRESIMS and 1D and 2D NMR data, single-crystal X-ray diffraction, and electronic circular dichroism (ECD) data analyses. The cardiomyocyte protective activity assay revealed that compounds 1, 2, 5, 12-14, and 16 ameliorated cold ischemic injury at 48 h post cold ischemia (CI), and compounds 1, 5, and 14 prevented cold ischemia induced Ser9 dephosphorylation of GSK3ß at 12 h post CI. Our current study highlights indoloquinazoline alkaloids as the first class of natural cardiomyocyte protective agents against cold ischemic injury, which furnishes promising lead molecules for the development of new cardioprotectants in heart transplantation medicine.


Asunto(s)
Alcaloides , Miocitos Cardíacos , Alcaloides/química , Hongos , Espectroscopía de Resonancia Magnética , Estructura Molecular
7.
Nat Prod Res ; 37(24): 4081-4088, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36661108

RESUMEN

Euphorfinoids M and N (1 and 2), two previously undescribed ent-abietane diterpenoids, together with seven known analogues (3-9), were isolated from the roots of wild Euphorbia fischeriana. Their structures were elucidated by spectroscopic analysis, including extensive NMR, HR-ESIMS, ECD, and comparison with structurally related known analogues. Bioassays against proliferative effects of HeLa cell line showed that compound 1 was the most active with IC50 3.62 ± 0.31 µM.


Asunto(s)
Antineoplásicos Fitogénicos , Diterpenos , Euphorbia , Humanos , Abietanos/farmacología , Abietanos/química , Diterpenos/química , Euphorbia/química , Células HeLa , Espectroscopía de Resonancia Magnética , Raíces de Plantas/química , Estructura Molecular , Antineoplásicos Fitogénicos/química
8.
Sci China Life Sci ; 66(4): 892, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36598622

RESUMEN

This paper contains errors in the authors' affiliations. Wenjia Li, is a Ph.D. candidate in the University of Chinese Academy of Sciences, Jiangchun Wei and Xingzhong Liu are professors in the University of Chinese Academy of Sciences, which is missing in the original version. The affiliations have been corrected.

9.
iScience ; 26(1): 105770, 2023 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-36590161

RESUMEN

Lichens are well known as pioneer organisms or stress-tolerant extremophiles, potentially playing a core role in the early formation of terrestrial ecosystems. Epiphytic macrolichens are known to contribute to the water- and nutrient cycles in forest ecosystem. But due to the scarcity of fossil record, the evolutionary history of epiphytic macrolichens is poorly documented. Based on new fossil of Jurassic Daohugouthallus ciliiferus, we demonstrate the hitherto oldest known macrolichen inhabited a gymnosperm branch. We applied energy dispersive X-ray spectroscopy and geometric morphometric analysis to complementarily verify lichen affinity of D. ciliiferus and quantitatively assess the potential relationships with extant lichenized lineages, providing new approaches for study of this lichen adpression fossil. Considering the results, and the inferred age of D. ciliiferus, a new family, Daohugouthallaceae, is established. This work updates current knowledge to the early evolution of epiphytic macrolichens and reveals more complex lichen-plant interactions in a Jurassic forest ecosystem.

10.
Nat Prod Res ; 37(8): 1300-1309, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-34758696

RESUMEN

Euphorfinoids A and B (1 and 2), a pair of ent-atisane diterpenoid epimers with a vicinal 2,3-diol moiety, together with four known analogues (3-6), were isolated from the roots of wild Euphorbia fischeriana. Their structures were elucidated by spectroscopic analysis, including extensive NMR, HR-ESIMS, NMR calculations, X-ray diffraction, and comparison with structurally related known analogues. Our bioassays have established that compound 1 displayed moderate anti-proliferative effects on Hcc1806 cell line with IC50 15.53 ± 0.21 µM, and compound 5 showed remarkable inhibitory effects against AChE with IC50 32.56 ± 2.74 µM by an in vitro screened experiment.


Asunto(s)
Antineoplásicos Fitogénicos , Diterpenos , Euphorbia , Euphorbia/química , Antineoplásicos Fitogénicos/química , Diterpenos/química , Línea Celular Tumoral , Raíces de Plantas/química , Estructura Molecular
11.
J Fungi (Basel) ; 8(10)2022 Sep 22.
Artículo en Inglés | MEDLINE | ID: mdl-36294559

RESUMEN

The lichenized fungal genus Astrothelium is an important element of crustose lichen communities in tropical to subtropical forests. Morphological and molecular phylogenetic approaches to investigate species diversity of Astrothelium (Trypetheliaceae) from Southern China were carried out in this study. Bayesian and maximum-likelihood (ML) analyses were generated based on the combined data set of internal transcribed spacer (ITS), partial regions of the nuclear ribosomal large subunit (LSU), and the largest subunit of RNA polymerase II gene sequences (RPB1). The morphological comparison with the known Astrothelium taxa and molecular phylogeny support five new species: Astrothelium jiangxiense sp. nov., A. luminothallinum sp. nov., A. pseudocrassum sp. nov., A. subeustominspersum sp. nov., and A. subrufescens sp. nov. All these species are described and illustrated in detail.

12.
Phytochemistry ; 203: 113372, 2022 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-35964805

RESUMEN

Nine previously undescribed diterpenoids, euphorfiatnoids A-I, together with seven known diterpenoids, were isolated from the roots of wild Euphorbia fischeriana. Their structures were elucidated by the interpretation of HRESIMS, UV, and NMR data. Their configurations were determined by electronic circular dichroism (ECD) spectroscopy analysis and the structure of euphorfiatnoid A was confirmed by X-ray crystallography. To further understand the antitumor effects of E. fischeriana, we tested the cytotoxicity of these compounds against H460, HepG2, and MCF-7 cell lines in vitro using MTT assays. Euphorfiatnoid B exhibited the most promising inhibitory effect against H460 cells with an IC50 value of 9.97 µM. Euphorfiatnoid A and C also exhibited moderate cytotoxicity against HepG2 cells with IC50 values of 11.64 and 13.10 µM, respectively.


Asunto(s)
Antineoplásicos Fitogénicos , Antineoplásicos , Diterpenos , Euphorbia , Antineoplásicos Fitogénicos/química , Antineoplásicos Fitogénicos/farmacología , Diterpenos/química , Euphorbia/química , Humanos , Células MCF-7 , Estructura Molecular , Raíces de Plantas/química
13.
Chin J Nat Med ; 20(7): 527-536, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35907651

RESUMEN

Phenylalanine ammonia-lyase (PAL), which catalyzes the conversion from L-phenylalanine to trans-cinnamic acid, is a well-known key enzyme and a connecting step between primary and secondary metabolisms in the phenylpropanoid biosynthetic pathway of plants and microbes. Schisandra chinensis, a woody vine plant belonging to the family of Magnoliaceae, is a rich source of dibenzocyclooctadiene lignans exhibiting potent activity. However, the functional role of PAL in the biosynthesis of lignan is relatively limited, compared with those in lignin and flavonoids biosynthesis. Therefore, it is essential to clone and characterize the PAL genes from this valuable medicinal plant. In this study, molecular cloning and characterization of three PAL genes (ScPAL1-3) from S. chinensis was carried out. ScPALs were cloned using RACE PCR. The sequence analysis of the three ScPALs was carried out to give basic characteristics followed by docking analysis. In order to determine their catalytic activity, recombinant protein was obtained by heterologous expression in pCold-TF vector in Escherichia coli (BL21-DE3), followed by Ni-affinity purification. The catalytic product of the purified recombinant proteins was verified using RP-HPLC through comparing with standard compounds. The optimal temperature, pH value and effects of different metal ions were determined. Vmax, Kcat and Km values were determined under the optimal conditions. The expression of three ScPALs in different tissues was also determined. Our work provided essential information for the function of ScPALs.


Asunto(s)
Fenilanina Amoníaco-Liasa , Schisandra , Clonación Molecular , Escherichia coli/genética , Escherichia coli/metabolismo , Fenilalanina/genética , Fenilalanina/metabolismo , Fenilanina Amoníaco-Liasa/química , Proteínas Recombinantes , Schisandra/genética
14.
Zhongguo Zhong Yao Za Zhi ; 47(6): 1582-1586, 2022 Mar.
Artículo en Chino | MEDLINE | ID: mdl-35347956

RESUMEN

This study investigated the chemical components from the leaves and stems of Schisandra chinensis. Three norsesquiterpenoids were isolated from S. chinensis by various column chromatographies(silica gel, Sephadex LH-20, and MCI), reversed-phase medium-pressure preparative, and semi-preparative high-performance liquid chromatography(HPLC). Their structures were identified based on physicochemical properties, mass spectrometry(MS), nuclear magnetic resonance(NMR), ultraviolet(UV), and electro-nic circular dichroism(ECD) as(3R,4R,5R,6S,7E)-3,4,5,6-tetrahydroxy-7-megastigmen-9-one(1),(3S,5R,6R,7E)-3,5,6-trihydroxy-7-megastigmen-9-one(2), and(3S,4R,9R)-3,4,9-trihydroxymegastigman-5-ene(3). Compound 1 was a new compound, and its absolute configuration was determined by ECD. Compounds 2 and 3 were isolated from the Schisandra plant for the first time.


Asunto(s)
Schisandra , Cromatografía Líquida de Alta Presión , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Hojas de la Planta/química
15.
J Asian Nat Prod Res ; 24(3): 245-251, 2022 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33871298

RESUMEN

Two novel polyketones, along with four known compounds, were isolated from the leaves and twigs of Clerodendrum trichotomum. Their structures were determined to be clerodendruketone A (1), clerodendruketone B (2), ecdysanols E (3), ecdysanols D (4), 5,5'-dimethoxy-7-oxolariciresinol (5), and (-)-(7'S,8S,8'R)-4,4'-dihydroxy-3,3',5,5'-tetramethoxy-7',9-epoxy-lignan-9'-ol-7-one (6) through the methods of NMR, HRESIMS and ECD data analyses. The antioxidant effects against free radical were tested by DPPH assay. The antibacterial activity against Escherichia coli and Staphylococcus aureus were tested by turbidimetry assay. The results demonstrated that compounds 1 and 2 had significative antibacterial activity, and compound 3 had moderate antioxidant activity.


Asunto(s)
Clerodendrum , Lignanos , Antioxidantes , Estructura Molecular , Hojas de la Planta
16.
Bioorg Chem ; 116: 105395, 2021 11.
Artículo en Inglés | MEDLINE | ID: mdl-34628224

RESUMEN

Seven new triterpenoids including two cycloartanes (1-2), a lanostane (3), a tirucallane (4), a dammarane (5), an ursane (6), and an oleanane (7), along with nineteen known triterpenoids (8-26), have been obtained from the roots of Euphorbia fischeriana. Their structures were established by NMR, HRESIMS, single-crystal X-ray diffraction analysis, Mosher's method, NMR calculations, ECD analysis, and comparison with structurally related known analogues. Among them, compounds 1 and 8 were a pair of cycloartane-type triterpenoids epimers. Our bioassays have established that compounds 1-5 and 10 displayed moderate cytotoxic effects, and the structure-activity relationships of cycloartane-type triterpenoids (CTTs) were further examined. Notably, some triterpenoids displayed moderate inhibitory effects against AChE by an in vitro screened experiment. Triterpenoid 7 (Euphorfistrine G, ETG) displayed the potent inhibitory effect with IC50 = 2.45 and Ki = 2.30 µM (inhibition kinetic). And, in silico docking analyses have been performed to investigate the inhibitory mechanism of compound 7.


Asunto(s)
Acetilcolinesterasa/metabolismo , Antineoplásicos Fitogénicos/farmacología , Inhibidores de la Colinesterasa/farmacología , Euphorbia/química , Triterpenos/farmacología , Antineoplásicos Fitogénicos/química , Antineoplásicos Fitogénicos/aislamiento & purificación , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Inhibidores de la Colinesterasa/química , Inhibidores de la Colinesterasa/aislamiento & purificación , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Modelos Moleculares , Estructura Molecular , Relación Estructura-Actividad , Triterpenos/química , Triterpenos/aislamiento & purificación
17.
Phytochemistry ; 190: 112867, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34304117

RESUMEN

Eight undescribed diterpenoids, euphorfinoids E-L, together with twelve known analogues, were isolated from the roots of wild Euphorbia fischeriana. Their structures and absolute configurations were elucidated by a combination of NMR, MS, ECD, and X-ray diffraction analyses. The plausible biosynthetic pathway of 1 was also proposed. The isolated compounds displayed moderate inhibitory activity against acetylcholinesterase (AChE) with 50% inhibiting concentration (IC50) values of 6.23-192.38 µM.


Asunto(s)
Antineoplásicos Fitogénicos , Inhibidores de la Colinesterasa , Diterpenos , Euphorbia , Acetilcolinesterasa , Inhibidores de la Colinesterasa/farmacología , Diterpenos/farmacología , Estructura Molecular , Raíces de Plantas
18.
J Fungi (Basel) ; 8(1)2021 Dec 21.
Artículo en Inglés | MEDLINE | ID: mdl-35049942

RESUMEN

We employed a molecular phylogenetic approach using five markers (ITS, nuSSU, nuLSU, TEF1-α, and RPB2) to assess potential cryptic speciation in foliicolous members of Strigula s.lat. (Strigulaceae), including the recently segregated genera Phylloporis, Puiggariella, Raciborskiella, Racoplaca, and Serusiauxiella, from tropical areas in Asia, with selected materials from the Neotropics as reference. On the basis of combined molecular and phenotypic datasets, two new species of Racoplaca and 10 new species of Strigula s.str. are described: Racoplaca macrospora sp. nov., R. maculatoides sp. nov., Strigula guangdongensis sp. nov., S. intermedia sp. nov., S. laevis sp. nov., S. microcarpa sp. nov., S. pseudoantillarum sp. nov., S. pseudosubtilissima sp. nov., S. pycnoradians sp. nov., S. sinoconcreta sp. nov., S. stenoloba sp. nov., and S. subtilissimoides sp. nov. In addition, we propose the new combination Phylloporis palmae comb. nov. (≡ =Manaustrum palmae) and we validate the earlier combination Racoplaca melanobapha comb. nov. (≡ Verrucaria melanobapha; Strigula melanobapha). Our data clearly indicate a considerable degree of cryptic diversification in foliicolous representatives of Strigula s.lat., particularly in the presumably widespread taxa Strigula antillarum, S. concreta, S. nitidula, and S. smaragdula. Given that these phylogenetic revisions are thus far limited to few regions, we predict that our findings only represent the proverbial tip of the iceberg in this group of lichenized fungi.

19.
Front Mol Biosci ; 8: 806412, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-35059437

RESUMEN

Ovarian reserve is a key factor in the reproductive function of the ovaries. Ovarian aging is characterized by a gradual decline in the quantity and quality of follicles. The underlying mechanism of ovarian aging is complex and age-related oxidative stress is considered one of the most likely factors. Secoisolariciresinol diglucoside (SDG) has been shown to have good scavenging ability against reactive oxygen species (ROS) which slowly accumulates in ovarian tissues. However, it is unknown whether SDG had beneficial effects on aging ovaries. In this study, we used 37-week-old female C57BL/6J mouse as a natural reproductive aging model to evaluate the role of SDG in ovarian aging. SDG (7 and 70 mg/kg) intragastric administration was performed in the mice daily. After 8 weeks, the effects of SDG on aging ovaries were evaluated by counting the number of follicles and the expression of follicle-stimulating hormone receptors (FSHR) in the ovary. The mechanism of SDG on the aging ovaries was further explored through ovarian metabolomics. It was found that SDG can effectively increase the number of growing follicles and increase the expression of the FSHR protein. The metabolomics results showed that the ovaries in the SDG intervention group achieved better uptake and transport of nutrients, including amino acids and glucose that are necessary for the development of oocytes. At the same time, the ovaries of the SDG intervention group showed that the drug reduced ROS generation. Additionally, we found that ovarian telomere length and ovarian mitochondrial DNA copy number that are highly susceptible to ROS damage and are also related to aging. The results showed that SDG can significantly increase mitochondrial DNA copy number and slow down the process of telomere shortening. These data indicate that SDG improves ovarian reserve by inhibiting oxidative stress.

20.
Proc Natl Acad Sci U S A ; 117(38): 23847-23858, 2020 09 22.
Artículo en Inglés | MEDLINE | ID: mdl-32873646

RESUMEN

Umbilicaria muhlenbergii is the only known dimorphic lichenized fungus that grows in the hyphal form in lichen thalli but as yeast cells in axenic cultures. However, the regulation of yeast-to-hypha transition and its relationship to the establishment of symbiosis are not clear. In this study, we show that nutrient limitation and hyperosmotic stress trigger the dimorphic change in U. muhlenbergii Contact with algal cells of its photobiont Trebouxia jamesii induced pseudohyphal growth. Treatments with the cAMP diphosphoesterase inhibitor IBMX (3-isobutyl-1-methylxanthine) induced pseudohyphal/hyphal growth and resulted in the differentiation of heavily melanized, lichen cortex-like structures in culture, indicating the role of cAMP signaling in regulating dimorphism. To confirm this observation, we identified and characterized two Gα subunits UmGPA2 and UmGPA3 Whereas deletion of UmGPA2 had only a minor effect on pseudohyphal growth, the ΔUmgpa3 mutant was defective in yeast-to-pseudohypha transition induced by hyperosmotic stress or T. jamesii cells. IBMX treatment suppressed the defect of ΔUmgpa3 in pseudohyphal growth. Transformants expressing the UmGPA3G45V or UmGPA3Q208L dominant active allele were enhanced in the yeast-to-pseudohypha transition and developed pseudohyphae under conditions noninducible to the wild type. Interestingly, T. jamesii cells in close contact with pseudohyphae of UmGPA3G45V and UmGPA3Q208L transformants often collapsed and died after coincubation for over 72 h, indicating that improperly regulated pseudohyphal growth due to dominant active mutations may disrupt the initial establishment of symbiotic interaction between the photobiont and mycobiont. Taken together, these results show that the cAMP-PKA pathway plays a critical role in regulating dimorphism and symbiosis in U. muhlenbergii.


Asunto(s)
Ascomicetos , AMP Cíclico/metabolismo , Líquenes , Simbiosis/fisiología , Chlorophyta/metabolismo , Chlorophyta/fisiología , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Hifa/citología , Hifa/metabolismo , Transducción de Señal/fisiología
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