570 Biowissenschaften; Biologie
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Highlights
• Histone modifications alter chromatin structure and gene accessibility, allowing timely stress response, and enhancing tomato's ability to cope with environmental challenges.
• miRNAs and lncRNAs fine-tune gene expression, playing essential roles in stress tolerance, particularly in heat and drought stress responses.
• Leveraging epigenetic modifications can develop tomato varieties that maintain high productivity and quality under adverse environmental conditions.
• Detailed mapping of the tomato epigenome under various stress conditions can identify key regulatory regions and guide targeted breeding programs
Abstract
Climate change poses a major challenge to agriculture, affecting crop production through shifting weather patterns and an increase in extreme conditions such as heat waves, droughts, and floods, all of which are further compounded by biotic stress factors. Tomatoes, a vital dietary staple and significant agricultural product worldwide, are particularly susceptible to these changes. The need for developing climate-resilient tomato varieties is more urgent than ever to ensure food security. Epigenetic modifications, such as DNA methylation and histone modifications, play essential roles in gene expression regulation. These modifications can affect plant traits and responses to environmental stresses, enabling tomatoes to maintain productivity despite variable climates or disease pressures. Tomato, as a model plant, offers valuable insights into the epigenetic mechanisms underlying fruit development and responses to stress. This review provides an overview of key discoveries regarding to tomato response and resilience mechanisms related to epigenetics, highlighting their potential in breeding strategies to enhance tomato resilience against both abiotic and biotic challenges, thereby promoting sustainable agricultural practices in the context of global climate change.
Background: Bacteria of the genus Photorhabdus and Xenorhabdus are motile, Gram-negative bacteria that live in symbiosis with entomopathogenic nematodes. Due to their complex life cycle, they produce a large number of specialized metabolites (natural products) encoded in biosynthetic gene clusters (BGC). Genetic tools for Photorhabdus and Xenorhabdus have been rare and applicable to only a few strains. In the past, several tools have been developed for the activation of BGCs and the deletion of individual genes. However, these often have limited efficiency or are time consuming. Among the limitations, it is essential to have versatile expression systems and genome editing tools that could facilitate the practical work.
Results: In the present study, we developed several expression vectors and a CRISPR-Cpf1 genome editing vector for genetic manipulations in Photorhabdus and Xenorhabdus using SEVA plasmids. The SEVA collection is based on modular vectors that allow exchangeability of different elements (e.g. origin of replication and antibiotic selection markers with the ability to insert desired sequences for different end applications). Initially, we tested different SEVA vectors containing the broad host range origins and three different resistance genes for kanamycin, gentamycin and chloramphenicol, respectively. We demonstrated that these vectors are replicative not only in well-known representatives, e.g. Photorhabdus laumondii TTO1, but also in other rarely described strains like Xenorhabdus sp. TS4. For our CRISPR/Cpf1-based system, we used the pSEVA231 backbone to delete not only small genes but also large parts of BGCs. Furthermore, we were able to activate and refactor BGCs to obtain high production titers of high value compounds such as safracin B, a semisynthetic precursor for the anti-cancer drug ET-743.
Conclusions: The results of this study provide new inducible expression vectors and a CRISPR/CPf1 encoding vector all based on the SEVA (Standard European Vector Architecture) collection, which can improve genetic manipulation and genome editing processes in Photorhabdus and Xenorhabdus.
To understand the function of cells such as neurons within an organism, it can be instrumental to inhibit cellular function, or to remove the cell (type) from the organism, and thus to observe the consequences on organismic and/or circuit function and animal behavior. A range of approaches and tools were developed and used over the past few decades that act either constitutively or acutely and reversibly, in systemic or local fashion. These approaches make use of either drugs or genetically encoded tools. Also, there are acutely acting inhibitory tools that require an exogenous trigger like light. Here, we give an overview of such methods developed and used in the nematode Caenorhabditis elegans.
Highlights
• Different NADPH supply strategies are compared in Saccharomyces cerevisiae.
• Example products are d-xylitol and l-galactonate.
• ZWF1 overexpression is the most robust strategy in the diauxic batch fermentation.
• Carbon source dependencies and interferences of different strategies are explored.
Abstract
Enhancing the supply of the redox cofactor NADPH in metabolically engineered cells is a critical target for optimizing the synthesis of many product classes, such as fatty acids or terpenoids. In S. cerevisiae, several successful approaches have been developed in different experimental contexts. However, their systematic comparison has not been reported. Here, we established the reduction of xylose to xylitol by an NADPH-dependent xylose reductase as a model reaction to compare the efficacy of different NADPH supply strategies in the course of a batch fermentation, in which glucose and ethanol are sequentially used as carbon sources and redox donors. We show that strains overexpressing the glucose-6-phosphate dehydrogenase Zwf1 perform best, producing up to 16.9 g L−1 xylitol from 20 g L−1 xylose in stirred tank bioreactors. The beneficial effect of increased Zwf1 activity is especially pronounced during the ethanol consumption phase. The same notion applies to the deletion of the aldehyde dehydrogenase ALD6 gene, albeit at a quantitatively lower level. Reduced expression of the phosphoglucose isomerase Pgi1 and heterologous expression of the NADP+-dependent glyceraldehyde-3-phosphate dehydrogenase Gdp1 from Kluyveromyces lactis acted synergistically with ZWF1 overexpression in the presence of glucose, but had a detrimental effect after the diauxic shift. Expression of the mitochondrial NADH kinase Pos5 in the cytosol likewise improved the production of xylitol only on glucose, but not in combination with enhanced Zwf1 activity. To demonstrate the generalizability of our observations, we show that the most promising strategies – ZWF1 overexpression and deletion of ALD6 - also improve the production of l-galactonate from d-galacturonic acid. Therefore, we expect that these findings will provide valuable guidelines for engineering not only the production of xylitol but also of diverse other pathways that require NADPH.
Four novel species of subgenus Russula crown clade collected from northwestern China are described based on morphological and phylogenetic evidence. Morphologically, R. griseorosea Y.Song sp. nov. (subsection Puellarinae) is characterized by its brown pileus with a grayish pink tint, basidiospores with warts often connected by fine lines, orthochromatic pileipellis with long terminal cells and septate pileocystidia; R. micangshanensis Y.Song sp. nov. (subsection Olivaceinae) is diagnosed by its large basidia, hymenial cystidia and basidiospores, and spore ornamentations with unequal crests and often twinned warts, which give the spore distinctive appearance; R. minirosea Y.Song sp. nov. (subsection Laricinae) has very small basidiocarp with pileus less than 3.3 cm in diameter, basidiospores with fine reticulum, small basidia, and septate pileocystidia; R. purpureomarginalis F.Li & Y.Song sp. nov. (subsection Xerampelinae) has large basidiospores with often isolated ornamentations, slim basidia and often septate flexuous pileocystidia. Differences between the four novel species and their closely related taxa were analyzed. Phylogenetic analyses based on both ITS and multi-locus (LSU, rpb2 and tef1) were carried out to confirm the distinct taxonomic status of the four novel species.
The expanding field of epitranscriptomics might rival the epigenome in the diversity of biological processes impacted. In recent years, the development of new high-throughput experimental and computational techniques has been a key driving force in discovering the properties of RNA modifications. Machine learning applications, such as for classification, clustering or de novo identification, have been critical in these advances. Nonetheless, various challenges remain before the full potential of machine learning for epitranscriptomics can be leveraged. In this review, we provide a comprehensive survey of machine learning methods to detect RNA modifications using diverse input data sources. We describe strategies to train and test machine learning methods and to encode and interpret features that are relevant for epitranscriptomics. Finally, we identify some of the current challenges and open questions about RNA modification analysis, including the ambiguity in predicting RNA modifications in transcript isoforms or in single nucleotides, or the lack of complete ground truth sets to test RNA modifications. We believe this review will inspire and benefit the rapidly developing field of epitranscriptomics in addressing the current limitations through the effective use of machine learning.
Reactive oxygen species (ROS) are constant by-products of aerobic life. In excess, ROS lead to cytotoxic protein aggregates, which are a hallmark of ageing in animals and linked to age-related pathologies in humans. Acylamino acid-releasing enzymes (AARE) are bifunctional serine proteases, acting on oxidized proteins. AARE are found in all domains of life, albeit under different names, such as acylpeptide hydrolase (APEH/ACPH), acylaminoacyl peptidase (AAP), or oxidized protein hydrolase (OPH). In humans, AARE malfunction is associated with age-related pathologies, while their function in plants is less clear. Here, we provide a detailed analysis of AARE genes in the plant lineage and an in-depth analysis of AARE localization and function in the moss Physcomitrella and the angiosperm Arabidopsis. AARE loss-of-function mutants have not been described for any organism so far. We generated and analysed such mutants and describe a connection between AARE function, aggregation of oxidized proteins and plant ageing, including accelerated developmental progression and reduced life span. Our findings complement similar findings in animals and humans, and suggest a unified concept of ageing may exist in different life forms.
Schülerlabor Künstliche Intelligenz – Verhaltensforschung im Biologieunterricht mit neuen Methoden
(2023)
Die Verhaltensbiologie ist ein wichtiger Inhalt im Biologieunterricht. Das zielgerichtete, forschende Beobachten bereitet den Schüler/-innen jedoch häufg Schwierigkeiten und sollte vor allem praktisch eingeübt werden. Das Schülerlabor KILab bietet dafür eine innovative Möglichkeit.
Manipulation of neuronal or muscular activity by optogenetics or other stimuli can be directly linked to the analysis of Caenorhabditis elegans (C. elegans) body length. Thus, WormRuler was developed as an open-source video analysis toolbox that offers video processing and data analysis in one application. Utilizing this novel tool, the super red-shifted channelrhodopsin variant, ChrimsonSA, was characterized in C. elegans. Expression and activation of ChrimsonSA in GABAergic motor neurons results in their depolarization and therefore elongation of body length, the extent of which providing information about the strength of neuronal transmission.
Cone photoreceptor cells are wavelength-sensitive neurons in the retinas of vertebrate eyes and are responsible for color vision. The spatial distribution of these nerve cells is commonly referred to as the cone photoreceptor mosaic. By applying the principle of maximum entropy, we demonstrate the universality of retinal cone mosaics in vertebrate eyes by examining various species, namely, rodent, dog, monkey, human, fish, and bird. We introduce a parameter called retinal temperature, which is conserved across the retinas of vertebrates. The virial equation of state for two-dimensional cellular networks, known as Lemaître’s law, is also obtained as a special case of our formalism. We investigate the behavior of several artificially generated networks and the natural one of the retina concerning this universal, topological law.