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1.
Bioinform Adv ; 4(1): vbae074, 2024.
Article En | MEDLINE | ID: mdl-38841126

Motivation: Identifying cis-regulatory elements (CREs) is crucial for analyzing gene regulatory networks. Next generation sequencing methods were developed to identify CREs but represent a considerable expenditure for targeted analysis of few genomic loci. Thus, predicting the outputs of these methods would significantly cut costs and time investment. Results: We present Predmoter, a deep neural network that predicts base-wise Assay for Transposase Accessible Chromatin using sequencing (ATAC-seq) and histone Chromatin immunoprecipitation DNA-sequencing (ChIP-seq) read coverage for plant genomes. Predmoter uses only the DNA sequence as input. We trained our final model on 21 species for 13 of which ATAC-seq data and for 17 of which ChIP-seq data was publicly available. We evaluated our models on Arabidopsis thaliana and Oryza sativa. Our best models showed accurate predictions in peak position and pattern for ATAC- and histone ChIP-seq. Annotating putatively accessible chromatin regions provides valuable input for the identification of CREs. In conjunction with other in silico data, this can significantly reduce the search space for experimentally verifiable DNA-protein interaction pairs. Availability and implementation: The source code for Predmoter is available at: https://github.com/weberlab-hhu/Predmoter. Predmoter takes a fasta file as input and outputs h5, and optionally bigWig and bedGraph files.

2.
Z Orthop Unfall ; 2024 May 27.
Article En, De | MEDLINE | ID: mdl-38802072

Periprosthetic joint infections (PJI) are a serious complication of arthroplasty with high morbidity. With growing bacterial resistance and limited disposability of oral antibiotics with sufficient bioavailability, the need for intravenous antibiotic application is raising. This causes long-term hospital stays and rising costs. In the course of transferring procedures into an outpatient setting as well as coping with pressures on hospital capacity, outpatient parenteral antimicrobial therapy (OPAT) can build a bridge for the treatment of such infections.In a single centre analysis, 47 cases treated with OPAT were studied in relation to pathogen, antimicrobial resistance, indication for OPAT and follow up. Furthermore, the patients received an anonymised questionnaire with 4 clusters of interest in terms of internal quality assessment on the success and evaluation of this therapeutic procedure. Special attention was paid to the descriptive analysis of patients with periprosthetic joint infections (n = 30).Between May 2021 and October 2022 out of 47 patients with OPAT, 30 cases with periprosthetic joint infections were identified. For infected hip- and knee arthroplasties, a remarkable spectrum of pathogens was found. In hip infections highly resistant strains of Staphylococcus epidermidis and Enterococci were detected. In knee infections, the pathogens were more susceptible, but however highly virulent Staphylococcus aureus and Streptococci. Difficult to treat, mixed infections were found in both locations. The indication for OPAT was based in half of the cases on the high level of antimicrobial resistance, with availability of only parenteral applicable antibiotics. Further indications were mixed infections and difficult to treat pathogens, with flucloxacillin therapy as well as OPAT as the last therapeutic option. The questionnaire showed 96% patient satisfaction in terms of organisation and acceptance of this kind of therapy. Complications or unexpected outpatient/ hospital treatments were very rare in connection with OPAT. Two thirds of patients reported completion of the treatment. In the clinical follow up (average of 5.7 months), 96.6% of cases were declared free of infection. In one patient the infection persisted.OPAT is a safe and reliable therapeutic option for outpatients to continue parenteral antimicrobial treatment in joint infections. Due to increasing pressure on hospitals in terms of costs and capacity, this therapy offers an alternative to inpatient treatment. The indication for OPAT should be set individually, risk adjusted and not generalised for all patients. The outpatient sector needs financial and structural support for comprehensive roll-out of this treatment in Germany. A further focus should be on the prevention of periprosthetic joint infections. With the knowledge of the expected pathogens and the surgical resources, the standards should be adapted. The choice of the antibiotic should be specified and the intervals of application be shortened, according to the surgical course, in order to yield high levels of agent concentration in the surgical area. Further investigations are required to test the superiority of OPAT versus the oral administration of antibiotics in long-term observations as well as to define the necessary duration of OPAT.

3.
Plant Cell ; 2024 May 03.
Article En | MEDLINE | ID: mdl-38701340

Improving photosynthesis, the fundamental process by which plants convert light energy into chemical energy, is a key area of research with great potential for enhancing sustainable agricultural productivity and addressing global food security challenges. This perspective delves into the latest advancements and approaches aimed at optimizing photosynthetic efficiency. Our discussion encompasses the entire process, beginning with light harvesting and its regulation and progressing through the bottleneck of electron transfer. We then delve into the carbon reactions of photosynthesis, focusing on strategies targeting the enzymes of the Calvin-Benson-Bassham (CBB) cycle. Additionally, we explore methods to increase CO2 concentration near the Rubisco, the enzyme responsible for the first step of CBB cycle, drawing inspiration from various photosynthetic organisms, and conclude this section by examining ways to enhance CO2 delivery into leaves. Moving beyond individual processes, we discuss two approaches to identifying key targets for photosynthesis improvement: systems modeling and the study of natural variation. Finally, we revisit some of the strategies mentioned above to provide a holistic view of the improvements, analyzing their impact on nitrogen use efficiency and on canopy photosynthesis.

4.
Cancers (Basel) ; 16(4)2024 Feb 06.
Article En | MEDLINE | ID: mdl-38398080

Stimulated Raman Histology (SRH) employs the stimulated Raman scattering (SRS) of photons at biomolecules in tissue samples to generate histological images. Subsequent pathological analysis allows for an intraoperative evaluation without the need for sectioning and staining. The objective of this study was to investigate a deep learning-based classification of oral squamous cell carcinoma (OSCC) and the sub-classification of non-malignant tissue types, as well as to compare the performances of the classifier between SRS and SRH images. Raman shifts were measured at wavenumbers k1 = 2845 cm-1 and k2 = 2930 cm-1. SRS images were transformed into SRH images resembling traditional H&E-stained frozen sections. The annotation of 6 tissue types was performed on images obtained from 80 tissue samples from eight OSCC patients. A VGG19-based convolutional neural network was then trained on 64 SRS images (and corresponding SRH images) and tested on 16. A balanced accuracy of 0.90 (0.87 for SRH images) and F1-scores of 0.91 (0.91 for SRH) for stroma, 0.98 (0.96 for SRH) for adipose tissue, 0.90 (0.87 for SRH) for squamous epithelium, 0.92 (0.76 for SRH) for muscle, 0.87 (0.90 for SRH) for glandular tissue, and 0.88 (0.87 for SRH) for tumor were achieved. The results of this study demonstrate the suitability of deep learning for the intraoperative identification of tissue types directly on SRS and SRH images.

5.
Chemosphere ; 353: 141463, 2024 Apr.
Article En | MEDLINE | ID: mdl-38423146

Amidst the global plastic pollution crisis, the gastrointestinal tract serves as the primary entry point for daily exposure to micro- and nanoplastics. We investigated the complex dynamics between polystyrene micro- and nanoplastics (PS-MNPs) and four distinct human colorectal cancer cell lines (HT29, HCT116, SW480, and SW620). Our findings revealed a significant size- and concentration dependent uptake of 0.25, 1, and 10 µm PS-MNPs across all cell lines, with HCT116 cells exhibiting the highest uptake rates. During cell division, particles were distributed between mother and daughter cells. Interestingly, we observed no signs of elimination from the cells. Short-term exposure to 0.25 µm particles significantly amplified cell migration, potentially leading to pro-metastatic effects. Particles demonstrated high persistence in 2D and 3D cultures, and accumulation in non-proliferating parts of spheroids, without interfering with cell proliferation or division. Our study unveils the disturbing fact of the persistence and bioaccumulation of MNPs in colorectal cancer cell lines, key toxicological traits under REACH (Regulation concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals). Our observations underscore the potential of MNPs as hidden catalysts for tumor progression, particularly through enhancing cell migration and possibly fueling metastasis - a finding that sheds light on a significant and previously underexplored area of concern.


Colorectal Neoplasms , Water Pollutants, Chemical , Humans , Microplastics/metabolism , Plastics/toxicity , Polystyrenes/metabolism , Cell Division , Cell Movement , Water Pollutants, Chemical/metabolism
6.
Mol Biol Evol ; 41(2)2024 Feb 01.
Article En | MEDLINE | ID: mdl-38267085

Cellular and physiological cycles are driven by endogenous pacemakers, the diurnal and circadian rhythms. Key functions such as cell cycle progression and cellular metabolism are under rhythmic regulation, thereby maintaining physiological homeostasis. The photoreceptors phytochrome and cryptochrome, in response to light cues, are central input pathways for physiological cycles in most photosynthetic organisms. However, among Archaeplastida, red algae are the only taxa that lack phytochromes. Current knowledge about oscillatory rhythms is primarily derived from model species such as Arabidopsis thaliana and Chlamydomonas reinhardtii in the Viridiplantae, whereas little is known about these processes in other clades of the Archaeplastida, such as the red algae (Rhodophyta). We used genome-wide expression profiling of the red seaweed Gracilariopsis chorda and identified 3,098 rhythmic genes. Here, we characterized possible cryptochrome-based regulation and photosynthetic/cytosolic carbon metabolism in this species. We found a large family of cryptochrome genes in G. chorda that display rhythmic expression over the diurnal cycle and may compensate for the lack of phytochromes in this species. The input pathway gates regulatory networks of carbon metabolism which results in a compact and efficient energy metabolism during daylight hours. The system in G. chorda is distinct from energy metabolism in most plants, which activates in the dark. The green lineage, in particular, land plants, balance water loss and CO2 capture in terrestrial environments. In contrast, red seaweeds maintain a reduced set of photoreceptors and a compact cytosolic carbon metabolism to thrive in the harsh abiotic conditions typical of intertidal zones.


Arabidopsis , Rhodophyta , Seaweed , Seaweed/genetics , Cryptochromes/metabolism , Rhodophyta/genetics , Circadian Rhythm/genetics , Arabidopsis/genetics
7.
Arch Orthop Trauma Surg ; 144(1): 551-558, 2024 Jan.
Article En | MEDLINE | ID: mdl-38001380

INTRODUCTION: The aim of this study was to investigate the radiological outcomes of proximal closing metacarpal extension osteotomies using patient-specific guides and instruments (PSI) in early-stage trapeziometacarpal osteoarthritis to gain further insight into the joint loading surface and the benefits of the procedure. METHODS: In a prospective observational study, nine patients were included between 11/2020 and 12/2021, undergoing a total of ten proximal metacarpal extension osteotomies for basal thumb osteoarthritis. Computer-assisted surgical planning was performed using computed tomography (CT) and three-dimensional (3D) segmentation, allowing the fabrication of 3D-printed PSIs for surgical treatment. Inclusion criteria were a 1-year follow-up by CT to assess postoperative correction of the positional shift of the first metacarpal (MC1) and the location of peak loads compared with the preoperative situation. RESULTS: Radiographic analysis of the peak loading zone revealed a mean displacement on the articular surface of the trapezius of 0.4 mm ± 1.4 mm to radial and 0.1 mm ± 1.2 mm to palmar, and on the articular surface of the MC1 of 0.4 mm ± 1.4 mm to radial and 0.1 mm ± 1.2 mm to dorsal. CONCLUSION: There were trends indicating that a flatter pressure distribution and a dorsal shift of the peak loading zone may contribute to an improvement in subjective pain and patient satisfaction associated with this surgical procedure. The non-significant radiological results and the minor dorsal-radial shifts in our small study group limit a firm conclusion. LEVEL OF EVIDENCE: III.


Metacarpal Bones , Osteoarthritis , Humans , Metacarpal Bones/diagnostic imaging , Metacarpal Bones/surgery , Thumb/surgery , Osteoarthritis/diagnostic imaging , Osteoarthritis/surgery , Tomography, X-Ray Computed , Osteotomy/methods
9.
J Exp Bot ; 75(6): 1696-1713, 2024 Mar 14.
Article En | MEDLINE | ID: mdl-38158893

Photosynthesis plays a vital role in acclimating to and mitigating climate change, providing food and energy security for a population that is constantly growing, and achieving an economy with zero carbon emissions. A thorough comprehension of the dynamics of photosynthesis, including its molecular regulatory network and limitations, is essential for utilizing it as a tool to boost plant growth, enhance crop yields, and support the production of plant biomass for carbon storage. Photorespiration constrains photosynthetic efficiency and contributes significantly to carbon loss. Therefore, modulating or circumventing photorespiration presents opportunities to enhance photosynthetic efficiency. Over the past eight decades, substantial progress has been made in elucidating the molecular basis of photosynthesis, photorespiration, and the key regulatory mechanisms involved, beginning with the discovery of the canonical Calvin-Benson-Bassham cycle. Advanced chromatographic and mass spectrometric technologies have allowed a comprehensive analysis of the metabolite patterns associated with photosynthesis, contributing to a deeper understanding of its regulation. In this review, we summarize the results of metabolomics studies that shed light on the molecular intricacies of photosynthetic metabolism. We also discuss the methodological requirements essential for effective analysis of photosynthetic metabolism, highlighting the value of this technology in supporting strategies aimed at enhancing photosynthesis.


Metabolomics , Photosynthesis , Biomass , Carbon , Climate Change
10.
Sci Rep ; 13(1): 20466, 2023 11 22.
Article En | MEDLINE | ID: mdl-37993513

Many diseases, including cancer and covid, result in altered mechanical and electric properties of the affected cells. These changes were proposed as disease markers. Current methods to characterize such changes either provide very limited information on many cells or have extremely low throughput. We introduce electro-acoustic spinning (EAS). Cells were found to spin in combined non-rotating AC electric and acoustic fields. The rotation velocity in EAS depends critically on a cell's electrical and mechanical properties. In contrast to existing methods, the rotation is uniform in the field of view and hundreds of cells can be characterized simultaneously. We demonstrate that EAS can distinguish cells with only minor differences in electric and mechanical properties, including differences in age or the number of passages.


Cochlear Implantation , Cochlear Implants , Electricity , Rotation , Acoustics , Acoustic Stimulation , Electric Stimulation
11.
J Hand Surg Am ; 2023 Nov 10.
Article En | MEDLINE | ID: mdl-37952146

PURPOSE: This study aimed to evaluate the risk factors for distal phalanx fracture nonunion. METHODS: We retrospectively reviewed all adult patients treated for distal phalanx fractures at our institution between January 2015 and December 2019 with a minimum one-year follow-up period for potential risk factors. The absence of consolidation signs on follow-up radiographs at least 12 months after trauma was defined as nonunion. RESULTS: This study included 124 patients with 143 fractures available for follow-up. Nonunion was diagnosed in 19 patients, 18 of whom initially presented with an open fracture. On the day of the injury, 17 patients with open fractures presented to the hospital. In 16 nonunion cases, the traumatic mechanism was a crush injury. All nonunions occurred in tuft fractures, and none required revision surgery at the follow-up visit. CONCLUSIONS: Our findings suggest that tuft involvement in open fractures is the main risk factor for nonunion of distal phalangeal fractures. However, after a minimum of 1 year of follow-up, none of the tuft nonunions required revision surgery. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

13.
Front Plant Sci ; 14: 1182105, 2023.
Article En | MEDLINE | ID: mdl-37868318

In this work, we studied castor-oil plant Ricinus communis as a classical system for endosperm reserve breakdown. The seeds of castor beans consist of a centrally located embryo with the two thin cotyledons surrounded by the endosperm. The endosperm functions as major storage tissue and is packed with nutritional reserves, such as oil, proteins, and starch. Upon germination, mobilization of the storage reserves requires inter-organellar interplay of plastids, mitochondria, and peroxisomes to optimize growth for the developing seedling. To understand their metabolic interactions, we performed a large-scale organellar proteomic study on castor bean endosperm. Organelles from endosperm of etiolated seedlings were isolated and subjected to liquid chromatography-tandem mass spectrometry (LC-MS/MS). Computer-assisted deconvolution algorithms were applied to reliably assign the identified proteins to their correct subcellular localization and to determine the abundance of the different organelles in the heterogeneous protein samples. The data obtained were used to build a comprehensive metabolic model for plastids, mitochondria, and peroxisomes during storage reserve mobilization in castor bean endosperm.

14.
Wilderness Environ Med ; 34(4): 562-566, 2023 Dec.
Article En | MEDLINE | ID: mdl-37821298

Stress fractures in the distal phalanx of skeletally immature patients are rare and previously unreported clinical occurrences. We report on 2 adolescent sport climbers with such fractures of the dorsal metaphysis of the distal phalanx at the point where parts of the extensor tendon insert. A conservative treatment approach alone was sufficient in healing this fracture type in both patients after 12 wk. Clinicians should be informed of the existence of this rare clinical phenomenon and counsel patients that a conservative treatment approach may result in complete healing without the need for an invasive procedure.


Finger Injuries , Fractures, Stress , Sports , Adolescent , Humans , Fractures, Stress/diagnostic imaging , Fractures, Stress/etiology , Fractures, Stress/therapy , Finger Injuries/diagnostic imaging , Finger Injuries/etiology , Finger Injuries/therapy , Extremities , Wound Healing
15.
Mol Plant ; 16(10): 1547-1563, 2023 10 02.
Article En | MEDLINE | ID: mdl-37660255

Photosynthesis in crops and natural vegetation allows light energy to be converted into chemical energy and thus forms the foundation for almost all terrestrial trophic networks on Earth. The efficiency of photosynthetic energy conversion plays a crucial role in determining the portion of incident solar radiation that can be used to generate plant biomass throughout a growth season. Consequently, alongside the factors such as resource availability, crop management, crop selection, maintenance costs, and intrinsic yield potential, photosynthetic energy use efficiency significantly influences crop yield. Photosynthetic efficiency is relevant to sustainability and food security because it affects water use efficiency, nutrient use efficiency, and land use efficiency. This review focuses specifically on the potential for improvements in photosynthetic efficiency to drive a sustainable increase in crop yields. We discuss bypassing photorespiration, enhancing light use efficiency, harnessing natural variation in photosynthetic parameters for breeding purposes, and adopting new-to-nature approaches that show promise for achieving unprecedented gains in photosynthetic efficiency.


Photosynthesis , Plant Breeding , Crops, Agricultural , Nutrients , Food Security
16.
Int J Mol Sci ; 24(15)2023 Jul 30.
Article En | MEDLINE | ID: mdl-37569585

In healthy tissues, cells are in mechanical homeostasis. During cancer progression, this equilibrium is disrupted. Cancer cells alter their mechanical phenotype to a softer and more fluid-like one than that of healthy cells. This is connected to cytoskeletal remodeling, changed adhesion properties, faster cell proliferation and increased cell motility. In this work, we investigated the mechanical properties of breast cancer cells representative of different breast cancer subtypes, using MCF-7, tamoxifen-resistant MCF-7, MCF10A and MDA-MB-231 cells. We derived viscoelastic properties from atomic force microscopy force spectroscopy measurements and showed that the mechanical properties of the cells are associated with cancer cell malignancy. MCF10A are the stiffest and least fluid-like cells, while tamoxifen-resistant MCF-7 cells are the softest ones. MCF-7 and MDA-MB-231 show an intermediate mechanical phenotype. Confocal fluorescence microscopy on cytoskeletal elements shows differences in actin network organization, as well as changes in focal adhesion localization. These findings provide further evidence of distinct changes in the mechanical properties of cancer cells compared to healthy cells and add to the present understanding of the complex alterations involved in tumorigenesis.


Breast Neoplasms , Cytoskeleton , Humans , Female , Cell Line, Tumor , Cytoskeleton/metabolism , MCF-7 Cells , Actins/metabolism , Tamoxifen/pharmacology , Tamoxifen/metabolism , Breast Neoplasms/metabolism , Microscopy, Atomic Force/methods
17.
Plant Cell Environ ; 46(11): 3611-3627, 2023 11.
Article En | MEDLINE | ID: mdl-37431820

Research on C4 and C3-C4 photosynthesis has attracted significant attention because the understanding of the genetic underpinnings of these traits will support the introduction of its characteristics into commercially relevant crop species. We used a panel of 19 taxa of 18 Brassiceae species with different photosynthesis characteristics (C3 and C3-C4) with the following objectives: (i) create draft genome assemblies and annotations, (ii) quantify orthology levels using synteny maps between all pairs of taxa, (iii) ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠describe the phylogenetic relatedness across all the species, and (iv) track the evolution of C3-C4 intermediate photosynthesis in the Brassiceae tribe. Our results indicate that the draft de novo genome assemblies are of high quality and cover at least 90% of the gene space. Therewith we more than doubled the sampling depth of genomes of the Brassiceae tribe that comprises commercially important as well as biologically interesting species. The gene annotation generated high-quality gene models, and for most genes extensive upstream sequences are available for all taxa, yielding potential to explore variants in regulatory sequences. The genome-based phylogenetic tree of the Brassiceae contained two main clades and indicated that the C3-C4 intermediate photosynthesis has evolved five times independently. Furthermore, our study provides the first genomic support of the hypothesis that Diplotaxis muralis is a natural hybrid of D. tenuifolia and D. viminea. Altogether, the de novo genome assemblies and the annotations reported in this study are a valuable resource for research on the evolution of C3-C4 intermediate photosynthesis.


Brassicaceae , Photosynthesis , Phylogeny , Photosynthesis/genetics , Brassicaceae/genetics , Genomics
18.
Plant Physiol ; 193(2): 1433-1455, 2023 09 22.
Article En | MEDLINE | ID: mdl-37453131

The identification of factors that regulate C/N utilization in plants can make a substantial contribution to optimization of plant health. Here, we explored the contribution of pyridox(am)ine 5'-phosphate oxidase3 (PDX3), which regulates vitamin B6 homeostasis, in Arabidopsis (Arabidopsis thaliana). Firstly, N fertilization regimes showed that ammonium application rescues the leaf morphological phenotype of pdx3 mutant lines but masks the metabolite perturbance resulting from impairment in utilizing soil nitrate as a source of N. Without fertilization, pdx3 lines suffered a C/N imbalance and accumulated nitrogenous compounds. Surprisingly, exploration of photorespiration as a source of endogenous N driving this metabolic imbalance, by incubation under high CO2, further exacerbated the pdx3 growth phenotype. Interestingly, the amino acid serine, critical for growth and N management, alleviated the growth phenotype of pdx3 plants under high CO2, likely due to the requirement of pyridoxal 5'-phosphate for the phosphorylated pathway of serine biosynthesis under this condition. Triggering of thermomorphogenesis by growth of plants at 28 °C (instead of 22 °C) did not appear to require PDX3 function, and we observed that the consequent drive toward C metabolism counters the C/N imbalance in pdx3. Further, pdx3 lines suffered a salicylic acid-induced defense response, probing of which unraveled that it is a protective strategy mediated by nonexpressor of pathogenesis related1 (NPR1) and improves fitness. Overall, the study demonstrates the importance of vitamin B6 homeostasis as managed by the salvage pathway enzyme PDX3 to growth in diverse environments with varying nutrient availability and insight into how plants reprogram their metabolism under such conditions.


Arabidopsis Proteins , Arabidopsis , Arabidopsis/metabolism , Carbon/metabolism , Phosphates/metabolism , Carbon Dioxide/metabolism , Vitamin B 6 , Pyridoxine/metabolism , Pyridoxal Phosphate/metabolism , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Nitrogen/metabolism
20.
J Exp Bot ; 74(21): 6631-6649, 2023 11 21.
Article En | MEDLINE | ID: mdl-37392176

Carbon-concentrating mechanisms enhance the carboxylase efficiency of Rubisco by providing supra-atmospheric concentrations of CO2 in its surroundings. Beside the C4 photosynthesis pathway, carbon concentration can also be achieved by the photorespiratory glycine shuttle which requires fewer and less complex modifications. Plants displaying CO2 compensation points between 10 ppm and 40 ppm are often considered to utilize such a photorespiratory shuttle and are termed 'C3-C4 intermediates'. In the present study, we perform a physiological, biochemical, and anatomical survey of a large number of Brassicaceae species to better understand the C3-C4 intermediate phenotype, including its basic components and its plasticity. Our phylogenetic analysis suggested that C3-C4 metabolism evolved up to five times independently in the Brassicaceae. The efficiency of the pathway showed considerable variation. Centripetal accumulation of organelles in the bundle sheath was consistently observed in all C3-C4-classified taxa, indicating a crucial role for anatomical features in CO2-concentrating pathways. Leaf metabolite patterns were strongly influenced by the individual species, but accumulation of photorespiratory shuttle metabolites glycine and serine was generally observed. Analysis of phosphoenolpyruvate carboxylase activities suggested that C4-like shuttles have not evolved in the investigated Brassicaceae. Convergent evolution of the photorespiratory shuttle indicates that it represents a distinct photosynthesis type that is beneficial in some environments.


Brassicaceae , Carbon , Phylogeny , Carbon/metabolism , Brassicaceae/genetics , Brassicaceae/metabolism , Carbon Dioxide/metabolism , Photosynthesis/physiology , Glycine/genetics , Glycine/metabolism , Plant Leaves/metabolism
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