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1.
Plant Signal Behav ; 19(1): 2362518, 2024 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-38836385

RESUMO

Cotton is an important agricultural crop to many regions across the globe but is sensitive to low-temperature exposure. The activity of the enzyme SENSITIVE TO FREEZING 2 (SFR2) improves cold tolerance of plants and produces trigalactosylsyldiacylglycerol (TGDG), but its role in cold sensitive plants, such as cotton remains unknown. Recently, it was reported that cotton SFR2 produced very little TGDG under normal and cold conditions. Here, we investigate cotton SFR2 activation and TGDG production. Using multiple approaches in the native system and transformation into Arabidopsis thaliana, as well as heterologous yeast expression, we provide evidence that cotton SFR2 activates differently than previously found among other plant species. We conclude with the hypothesis that SFR2 in cotton is not activated in a similar manner regarding acidification or freezing like Arabidopsis and that other regions of SFR2 protein are critical for activation of the enzyme than previously reported.


Assuntos
Arabidopsis , Temperatura Baixa , Gossypium , Gossypium/genética , Gossypium/metabolismo , Gossypium/fisiologia , Arabidopsis/genética , Arabidopsis/fisiologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Estresse Fisiológico , Resposta ao Choque Frio/fisiologia , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente Modificadas
3.
J Exp Bot ; 2024 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-38808657

RESUMO

Chilling stress threatens plant growth and development, particularly affecting membrane fluidity and cellular integrity. Understanding plant membrane responses to chilling stress is important for unraveling the molecular mechanisms of stress tolerance. Whereas core transcriptional responses to chilling stress and stress tolerance are conserved across species, the associated changes in membrane lipids appear to be less conserved, as which lipids are affected by chilling stress varies by species. Here, we investigated changes in gene expression and membrane lipids in response to chilling stress during one 24 hour cycle in chilling-tolerant foxtail millet (Setaria italica), and chilling-sensitive sorghum (Sorghum bicolor), and Urochloa (browntop signal grass, Urochloa fusca, lipids only), leveraging their evolutionary relatedness and differing levels of chilling-stress tolerance. We show that most chilling-induced lipid changes are conserved across the three species, while we observed distinct, time-specific responses in chilling-tolerant foxtail millet, indicating the presence of a finely orchestrated adaptive mechanism. We detected rhythmicity in lipid responses to chilling stress in the three grasses, which were also present in Arabidopsis (Arabidopsis thaliana), suggesting the conservation of rhythmic patterns across species and highlighting the importance of accounting for time of day. When integrating lipid datasets with gene expression profiles, we identified potential candidate genes that showed corresponding transcriptional changes in response to chilling stress, providing insights into the differences in regulatory mechanisms between chilling-sensitive sorghum and chilling-tolerant foxtail millet.

4.
Plant Physiol ; 195(1): 685-697, 2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38386316

RESUMO

The accumulation of triacylglycerol (TAG) in vegetative tissues is necessary to adapt to changing temperatures. It has been hypothesized that TAG accumulation is required as a storage location for maladaptive membrane lipids. The TAG acyltransferase family has five members (DIACYLGLYCEROL ACYLTRANSFERSE1/2/3 and PHOSPHOLIPID:DIACYLGLYCEROL ACYLTRANSFERASE1/2), and their individual roles during temperature challenges have either been described conflictingly or not at all. Therefore, we used Arabidopsis (Arabidopsis thaliana) loss of function mutants in each acyltransferase to investigate the effects of temperature challenge on TAG accumulation, plasma membrane integrity, and temperature tolerance. All mutants were tested under one high- and two low-temperature regimens, during which we quantified lipids, assessed temperature sensitivity, and measured plasma membrane electrolyte leakage. Our findings revealed reduced effectiveness in TAG production during at least one temperature regimen for all acyltransferase mutants compared to the wild type, resolved conflicting roles of pdat1 and dgat1 by demonstrating their distinct temperature-specific actions, and uncovered that plasma membrane integrity and TAG accumulation do not always coincide, suggesting a multifaceted role of TAG beyond its conventional lipid reservoir function during temperature stress.


Assuntos
Aciltransferases , Proteínas de Arabidopsis , Arabidopsis , Temperatura Baixa , Diacilglicerol O-Aciltransferase , Triglicerídeos , Arabidopsis/genética , Arabidopsis/enzimologia , Diacilglicerol O-Aciltransferase/metabolismo , Diacilglicerol O-Aciltransferase/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Triglicerídeos/metabolismo , Aciltransferases/metabolismo , Aciltransferases/genética , Membrana Celular/metabolismo , Temperatura Alta , Regulação da Expressão Gênica de Plantas , Mutação/genética
5.
Biochem Mol Biol Educ ; 51(6): 685-690, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37681713

RESUMO

Many STEM disciplines are underrepresented to High School students. This is problematic as many students' decisions for college are shaped by their experiences and achievements in high school. Short content-oriented modules have been shown to encourage science identity and otherwise benefit the students' learning. Following the ASBMB's outreach protocol, we developed a short content-oriented module aimed at a high school biology classroom. Students interacted with 3D models of DNA and transcription factors while exploring structure-function relationships and introductory biochemistry topics. The high school teacher was impressed with the students' response to the module, specifically the ease with which students learned, their enthusiasm, and their recall of the experience. We provide all materials necessary to use this module, including student worksheet and printable model coordinates. We encourage both high school instructors and professional biochemists to consider similar module using physical models.


Assuntos
Aprendizagem , Estudantes , Humanos , Instituições Acadêmicas , Universidades , Biologia , Currículo
6.
J Exp Bot ; 74(17): 5405-5417, 2023 09 13.
Artigo em Inglês | MEDLINE | ID: mdl-37357909

RESUMO

Severe cold, defined as a damaging cold beyond acclimation temperatures, has unique responses, but the signaling and evolution of these responses are not well understood. Production of oligogalactolipids, which is triggered by cytosolic acidification in Arabidopsis (Arabidopsis thaliana), contributes to survival in severe cold. Here, we investigated oligogalactolipid production in species from bryophytes to angiosperms. Production of oligogalactolipids differed within each clade, suggesting multiple evolutionary origins of severe cold tolerance. We also observed greater oligogalactolipid production in control samples than in temperature-challenged samples of some species. Further examination of representative species revealed a tight association between temperature, damage, and oligogalactolipid production that scaled with the cold tolerance of each species. Based on oligogalactolipid production and transcript changes, multiple angiosperm species share a signal of oligogalactolipid production initially described in Arabidopsis, namely cytosolic acidification. Together, these data suggest that oligogalactolipid production is a severe cold response that originated from an ancestral damage response that remains in many land plant lineages and that cytosolic acidification may be a common signaling mechanism for its activation.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Magnoliopsida , Arabidopsis/metabolismo , Temperatura Baixa , Proteínas de Arabidopsis/metabolismo , Temperatura , Magnoliopsida/metabolismo , Aclimatação/fisiologia , Regulação da Expressão Gênica de Plantas
8.
Methods Mol Biol ; 2295: 15-27, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34047969

RESUMO

Glycerolipids form the largest fraction of all membrane lipids and their composition changes quickly during plant development, the diurnal cycle, and in response to hormones and biotic or abiotic stress. A challenge to accurate glycerolipid measurement is that lipid-degrading enzymes tend to remain active during extraction, and special care must be taken to ensure their inactivation. Multiple extraction methods have arisen to cope with this challenge but only a few comparative studies are available in the literature. Here we compare three commonly used methods for lipase inactivation and lipid extraction from two different plant tissues. The first method employs formic acid in an organic solvent for inactivation followed by immediate separation of the organic phase, while the second uses the same acidic solvent, but expands the time of lipase inactivation and lipid extraction by incubation at low temperature. The third method includes a boiling step of the tissue in isopropanol for enzyme inactivation. The first method is the fastest for lab conditions with few samples, the second and third are convenient with large sample numbers, including field work. The first two methods are commonly followed by lipid derivatization and gas chromatography, while the third avoids acids and is thus preferable for lipidomics approaches. We directly compare the methods on both Arabidopsis thaliana and Sorghum bicolor leaf tissues and measure the relative abundances of glycerolipid species formed by lipase activity. We conclude that each method provides intact lipid extracts of similar quality, if performed according to the protocols described below.


Assuntos
Lipídeos/isolamento & purificação , Extração Líquido-Líquido/métodos , Plantas/metabolismo , Arabidopsis/metabolismo , Cromatografia Gasosa , Cromatografia Líquida de Alta Pressão/métodos , Glicerol/metabolismo , Lipase/metabolismo , Lipidômica , Lipídeos/análise , Espectrometria de Massas/métodos , Lipídeos de Membrana/química , Membranas/química , Folhas de Planta/química
9.
Proc Natl Acad Sci U S A ; 118(10)2021 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-33658387

RESUMO

Although genome-sequence assemblies are available for a growing number of plant species, gene-expression responses to stimuli have been cataloged for only a subset of these species. Many genes show altered transcription patterns in response to abiotic stresses. However, orthologous genes in related species often exhibit different responses to a given stress. Accordingly, data on the regulation of gene expression in one species are not reliable predictors of orthologous gene responses in a related species. Here, we trained a supervised classification model to identify genes that transcriptionally respond to cold stress. A model trained with only features calculated directly from genome assemblies exhibited only modest decreases in performance relative to models trained by using genomic, chromatin, and evolution/diversity features. Models trained with data from one species successfully predicted which genes would respond to cold stress in other related species. Cross-species predictions remained accurate when training was performed in cold-sensitive species and predictions were performed in cold-tolerant species and vice versa. Models trained with data on gene expression in multiple species provided at least equivalent performance to models trained and tested in a single species and outperformed single-species models in cross-species prediction. These results suggest that classifiers trained on stress data from well-studied species may suffice for predicting gene-expression patterns in related, less-studied species with sequenced genomes.


Assuntos
Resposta ao Choque Frio , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Modelos Genéticos , Poaceae , Transcrição Gênica , Poaceae/genética , Poaceae/metabolismo , Especificidade da Espécie
10.
CBE Life Sci Educ ; 20(1): ar13, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33635127

RESUMO

Understanding metabolic function requires knowledge of the dynamics, interdependence, and regulation of metabolic networks. However, multiple professional societies have recognized that most undergraduate biochemistry students acquire only a surface-level understanding of metabolism. We hypothesized that guiding students through interactive computer simulations of metabolic systems would increase their ability to recognize how individual interactions between components affect the behavior of a system under different conditions. The computer simulations were designed with an interactive activity (i.e., module) that used the predict-observe-explain model of instruction to guide students through a process in which they iteratively predict outcomes, test their predictions, modify the interactions of the system, and then retest the outcomes. We found that biochemistry students using modules performed better on metabolism questions compared with students who did not use the modules. The average learning gain was 8% with modules and 0% without modules, a small to medium effect size. We also confirmed that the modules did not create or reinforce a gender bias. Our modules provide instructors with a dynamic, systems-driven approach to help students learn about metabolic regulation and equip students with important cognitive skills, such as interpreting and analyzing simulation results, and technical skills, such as building and simulating computer-based models.


Assuntos
Sexismo , Estudantes , Bioquímica , Compreensão , Feminino , Humanos , Aprendizagem , Masculino , Ensino
11.
Biochem Mol Biol Educ ; 49(2): 167-188, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-32833339

RESUMO

Our climate is changing due to anthropogenic emissions of greenhouse gases from the production and use of fossil fuels. Present atmospheric levels of CO2 were last seen 3 million years ago, when planetary temperature sustained high Arctic camels. As scientists and educators, we should feel a professional responsibility to discuss major scientific issues like climate change, and its profound consequences for humanity, with students who look up to us for knowledge and leadership, and who will be most affected in the future. We offer simple to complex backgrounds and examples to enable and encourage biochemistry educators to routinely incorporate this most important topic into their classrooms.


Assuntos
Mudança Climática , Currículo , Biologia Molecular/educação , Humanos
13.
Biochem Mol Biol Educ ; 48(4): 356-368, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32590880

RESUMO

Ensuring undergraduate students become proficient in relating protein structure to biological function has important implications. With current two-dimensional (2D) methods of teaching, students frequently develop misconceptions, including that proteins contain a lot of empty space, that bond angles for different amino acids can rotate equally, and that product inhibition is equivalent to allostery. To help students translate 2D images to 3D molecules and assign biochemical meaning to physical structures, we designed three 3D learning modules consisting of interactive activities with 3D printed models for amino acids, proteins, and allosteric regulation with coordinating pre- and post-assessments. Module implementation resulted in normalized learning gains on module-based assessments of 30% compared to 17% in a no-module course and normalized learning gains on a comprehensive assessment of 19% compared to 3% in a no-module course. This suggests that interacting with these modules helps students develop an improved ability to visualize and retain molecular structure and function.


Assuntos
Bases de Dados de Proteínas , Educação de Graduação em Medicina/métodos , Imageamento Tridimensional/métodos , Biologia Molecular/educação , Proteínas/química , Proteínas/metabolismo , Treinamento por Simulação/métodos , Avaliação Educacional , Feminino , Humanos , Masculino , Modelos Anatômicos , Conformação Proteica , Relação Estrutura-Atividade
14.
Plant Signal Behav ; 14(9): 1629270, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31189422

RESUMO

Chloroplasts adapt to freezing and other abiotic stresses in part by modifying their membranes. One key-remodeling enzyme is SENSITIVE TO FREEZING2 (SFR2). SFR2 is unusual because it does not respond to initial cold stress or cold acclimation, instead it responds during freezing conditions in Arabidopsis. This response has been shown to be sensitive to cytosolic acidification. The unique lipid products of SFR2 have also been detected in response to non-freezing stresses, but what causes SFR2 to respond in these stresses is unknown. Here, we investigate protoplast isolation as a representative of wounding stress. We show that SFR2 oligogalactolipid products accumulate during protoplast isolation. Notably, we show that protoplast cytosol is acidified during isolation. Modification of the buffers reduces oligogalactolipid accumulation, while prolonged incubation in the isolated state increases it. We conclude that SFR2 activation during protoplast isolation correlates with cytosolic acidification, implying that all SFR2 activation may be dependent on cytosolic acidification. We also conclude that protoplasts can be more gently isolated, reducing their stress.


Assuntos
Ácidos/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Cloroplastos/metabolismo , Citosol/metabolismo , Protoplastos/metabolismo , Estresse Fisiológico , beta-Glucosidase/metabolismo , Galactolipídeos/metabolismo , Concentração de Íons de Hidrogênio
15.
Plant J ; 99(5): 965-977, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31069858

RESUMO

Artificial selection has produced varieties of domesticated maize that thrive in temperate climates around the world. However, the direct progenitor of maize, teosinte, is indigenous only to a relatively small range of tropical and subtropical latitudes and grows poorly or not at all outside of this region. Tripsacum, a sister genus to maize and teosinte, is naturally endemic to the majority of areas in the western hemisphere where maize is cultivated. A full-length reference transcriptome for Tripsacum dactyloides generated using long-read Iso-Seq data was used to characterize independent adaptation to temperate climates in this clade. Genes related to phospholipid biosynthesis, a critical component of cold acclimation in other cold-adapted plant lineages, were enriched among those genes experiencing more rapid rates of protein sequence evolution in T. dactyloides. In contrast with previous studies of parallel selection, we find that there is a significant overlap between the genes that were targets of artificial selection during the adaptation of maize to temperate climates and those that were targets of natural selection in temperate-adapted T. dactyloides. Genes related to growth, development, response to stimulus, signaling, and organelles were enriched in the set of genes identified as both targets of natural and artificial selection.


Assuntos
Aclimatação/fisiologia , Poaceae/genética , Poaceae/fisiologia , Seleção Genética/fisiologia , Zea mays/genética , Zea mays/fisiologia , Temperatura Baixa , Genes de Plantas/genética , Antígenos HLA-G , Redes e Vias Metabólicas , Proteínas de Plantas/genética , Estresse Fisiológico , Transcriptoma
16.
Biochem Mol Biol Educ ; 47(3): 303-317, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30897273

RESUMO

Understanding the relationship between molecular structure and function represents an important goal of undergraduate life sciences. Although evidence suggests that handling physical models supports gains in student understanding of structure-function relationships, such models have not been widely implemented in biochemistry classrooms. Three-dimensional (3D) printing represents an emerging cost-effective means of producing molecular models to help students investigate structure-function concepts. We developed three interactive learning modules with dynamic 3D printed models to help biochemistry students visualize biomolecular structures and address particular misconceptions. These modules targeted specific learning objectives related to DNA and RNA structure, transcription factor-DNA interactions, and DNA supercoiling dynamics. We also designed accompanying assessments to gauge student learning. Students responded favorably to the modules and showed normalized learning gains of 49% with respect to their ability to understand and relate molecular structures to biochemical functions. By incorporating accurate 3D printed structures, these modules represent a novel advance in instructional design for biomolecular visualization. We provide instructors with the materials necessary to incorporate each module in the classroom, including instructions for acquiring and distributing the models, activities, and assessments. © 2019 International Union of Biochemistry and Molecular Biology, 47(3):303-317, 2019.


Assuntos
Compreensão , DNA/química , DNA/metabolismo , Aprendizagem , Biologia Molecular/educação , Impressão Tridimensional , Humanos , Conformação de Ácido Nucleico , Relação Estrutura-Atividade , Estudantes
19.
Plant Sci ; 276: 73-86, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30348330

RESUMO

Plants' tolerance of low temperatures is an economically and ecologically important limitation on geographic distributions and growing seasons. Tolerance for low temperatures varies significantly across different plant species, and different mechanisms likely act in different species. In order to survive low-temperature stress, plant membranes must maintain their fluidity in increasingly cold and oxidative cellular environments. The responses of different species to low-temperature stress include changes to the types and desaturation levels of membrane lipids, though the precise lipids affected tend to vary by species. Regulation of membrane dynamics and other low-temperature tolerance factors are controlled by both transcriptional and post-transcriptional mechanisms. Here, we review low-temperature induced changes in both membrane lipid composition and gene transcription across multiple related plant species with differing degrees of low-temperature tolerance. We attempt to define a core set of changes for transcripts and lipids across species and treatment variations. Some responses appear to be consistent across all species for which data are available, while many others appear likely to be species or family-specific. Potential rationales are presented, including variance in testing, reporting and the importance of considering the level of stress perceived by the plant.


Assuntos
Embriófitas/fisiologia , Lipídeos de Membrana/química , Transcriptoma , Aclimatação , Temperatura Baixa , Embriófitas/genética , Especificidade da Espécie , Estresse Fisiológico
20.
Photosynth Res ; 138(3): 345-360, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29961189

RESUMO

Photosynthetic membranes provide much of the usable energy for life on earth. To produce photosynthetic membrane lipids, multiple transport steps are required, including fatty acid export from the chloroplast stroma to the endoplasmic reticulum, and lipid transport from the endoplasmic reticulum to the chloroplast envelope membranes. Transport of hydrophobic molecules through aqueous space is energetically unfavorable and must be catalyzed by dedicated enzymes, frequently on specialized membrane structures. Here, we review photosynthetic membrane lipid transport to the chloroplast in the context of photosynthetic membrane lipid synthesis. We independently consider the identity of transported lipids, the proteinaceous transport components, and membrane structures which may allow efficient transport. Recent advances in lipid transport of chloroplasts, bacteria, and other systems strongly suggest that lipid transport is achieved by multiple mechanisms which include membrane contact sites with specialized protein machinery. This machinery is likely to include the TGD1, 2, 3 complex with the TGD5 and TGD4/LPTD1 systems, and may also include a number of proteins with domains similar to other membrane contact site lipid-binding proteins. Importantly, the likelihood of membrane contact sites does not preclude lipid transport by other mechanisms including vectorial acylation and vesicle transport. Substantial progress is needed to fully understand all photosynthetic membrane lipid transport processes and how they are integrated.


Assuntos
Cloroplastos/metabolismo , Membranas Intracelulares/metabolismo , Lipídeos de Membrana/biossíntese , Lipídeos de Membrana/metabolismo , Fotossíntese , Transporte Biológico , Lipídeos de Membrana/química , Açúcares/metabolismo
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