Intron-mediated enhancement: A tool for heterologous gene expression in plants?

Many plant promoters were characterized and used for transgene expression in plants. Even though these promoters drive high levels of transgene expression in plants, the expression patterns are rarely constitutive but restricted to some tissues and developmental stages. In terms of crop improvement not only the enhancement of expression per se but, in particular, tissue-specific and spatial expression of genes plays an important role. Introns were used to boost expression in transgenic plants in the field of crop improvement for a long time. However, the mechanism behind this so called intron-mediated enhancement (IME) is still largely unknown. This review highlights the complexity of IME on the levels of its regulation and modes of action and gives an overview on IME methodology, examples in fundamental research and models of proposed mechanisms. In addition, the application of IME in heterologous gene expression is discussed

Construction of Dichotomous Taxonomic Keys for San Francisco Bay Planktonic Diatoms

Planktonic diatoms exhibit high biodiversity in marine systems and make a significant contribution to water column primary productivity. This makes research on planktonic diatoms particularly important in measuring the health of coastal marine ecosystems. At the University of San Francisco (USF), undergraduate research has been conducted since September 2015 to study planktonic diatoms in San Francisco Bay. A previous study by Keith (2018), Planktonic Diatom Species Succession in San Francisco Bay, documented changes in species diversity over time, observing seasonal patterns in species richness as well as the effect of environmental factors such as salinity, temperature, and rainfall on species succession. In her work, an abundance of centric diatoms was present, indicating their essential role in local phytoplankton communities; however, the majority of observed centric taxa could not be identified with light microscopy. The current project was intended to use scanning electron microscopy to examine phenotypic characteristics of cells from field collections of Keith (2018) and clonal cultures to identify the species that make up the assemblage of dominant centric diatoms. Five centric diatom species were identified prior to the COVID-19 pandemic: Coscinodiscus curvatulus, Actinoptychus senarius, Coscinodiscus oculus-iridis, Coscinodiscus lentiginosa, and Thalassiosira nordenskioeldii. However, due to temporary sampling site closures and limited access to laboratories because of stay-at-home orders from the pandemic, the project was modified to be done remotely. The project was modified to analyze and compile present literature on diatom taxonomy based on morphology and develop taxonomic keys specific to diatoms in San Francisco Bay for use by both specialists and non-specialists, including school-aged children. In the construction of the keys, genera and species were considered significant if they were observed in ≥50% of the samples in the study by Keith (2018) from September 2015 - December 2017, including Chaetoceros spp., Ditylum brightwelli, Pseudo-nitzschia spp., Rhizosolenia setigera, Skeletonema costatum, Thalassiosira spp., and Trieres mobiliensis. Here, two keys are constructed – “A Technical Key to Common Planktonic Diatoms in San Francisco Bay” and A Basic Key to Common Phytoplankton in San Francisco Bay” – and the challenges of constructing the keys are discussed. These keys will aid in the assessment of diatom biodiversity in San Francisco Bay. Additionally, open-source diatom taxonomy websites have been collected to further support specialists and non-specialists in their scientific education and study of phytoplankton

Using Scanning Electron Microscopy and Morphologic Characteristics to Identify Centric Diatom Species in San Francisco Bay

Planktonic diatoms exhibit high biodiversity in marine systems and make a significant contribution to water column primary productivity. This makes research on planktonic diatoms particularly important in measuring the health of coastal marine ecosystems. At the University of San Francisco (USF), research has been conducted since September 2015 to study planktonic diatoms in San Francisco Bay. A previous study by Keith (2018), Planktonic Diatom Species Succession in San Francisco Bay, documented changes in species diversity over time, observing seasonal patterns in species richness as well as the effect of environmental factors such as salinity, temperature, and rainfall on species succession. In her work, an abundance of centric diatoms was present, indicating their essential role in local phytoplankton communities; however, the majority of observed centric taxa could not be identified with light microscopy. The current study is using scanning electron microscopy to examine phenotypic characteristics of cells from field collections and clonal cultures to identify the individual species that make up the assemblage of dominant centric diatoms. As of April 2020, five species have been verified: Actinocyclus curvatulus, Actinoptychus undulatus, Coscinodiscus oculus iridis, Thalassiosira lentinginosa and Thalassiosira nordenskjoldii

Evaluating Centric Diatom Diversity in San Francisco Bay with Scanning Electron Microscopy

Since September 2015, research has been conducted at the University of San Francisco (USF) to study planktonic diatoms in San Francisco Bay. Planktonic diatoms are one of the greatest contributors to the biodiversity in estuary systems. Due to their primary position in the food chain, changes in planktonic diatom communities will affect marine organisms at higher trophic levels. Therefore, the abundance and diversity of diatom species allows for the measurement of the health of the marine ecosystem. A previous study by Keith (2018), focused on documenting changes in species diversity over time, observing seasonal patterns in species richness as well as the effect of environmental factors such as salinity on species succession. In her work, an abundance of centric diatoms were observed, indicating their essential role in phytoplankton communities. Unfortunately, the majority of these taxa cannot be identified with light microscopy. Our ongoing study focuses upon understanding which individual species make up this group of centric diatoms. In particular, this study uses scanning electron microscopy to take images, compare and examine phenotypic characteristics between individuals in preserved samples taken from San Francisco Bay in order to distinguish and classify the individuals at a species level as well as determine relative abundance of individual species over time. By doing so, we will also be able to identify unique and new phytoplankton taxa, and contribute to a better understanding of the ecology of San Francisco Bay

Rural Areas on Their Way to a Smart Village - Experiences from Living Labs in Bavaria

This paper presents an overview of the approaches and experiences from existing living labs: german rural villages in which several digital solutions had been developed and implemented. The test villages have been selected based on a competition and are funded by the Bavarian state government in the project Digitales Dorf (Engl. digital village). Started in 2016 several measures had been taken to push digitalization in these rural areas with the goal to create equivalent living conditions to urban areas. The research question is how digitalization enhances the value of rural areas and which methods can be used to overcome the digitalization gap with a transferable and simple approach. This paper focuses on the transformation process rather than digital solutions, and presents requirements and best practices to promote digitalization in rural environments, their municipal processes and traditional approaches in everyday lif

The role of the plant antioxidant system in drought tolerance

Laxa M, Liebthal M, Telman W, Chibani K, Dietz K-J. The role of the plant antioxidant system in drought tolerance. Antioxidants. 2019;8(4): 94.Water deficiency compromises plant performance and yield in many habitats and in agriculture. In addition to survival of the acute drought stress period which depends on plant-genotype-specific characteristics, stress intensity and duration, also the speed and efficiency of recovery determine plant performance. Drought-induced deregulation of metabolism enhances generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) which in turn affect the redox regulatory state of the cell. Strong correlative and analytical evidence assigns a major role in drought tolerance to the redox regulatory and antioxidant system. This review compiles current knowledge on the response and function of superoxide, hydrogen peroxide and nitric oxide under drought stress in various species and drought stress regimes. The meta-analysis of reported changes in transcript and protein amounts, and activities of components of the antioxidant and redox network support the tentative conclusion that drought tolerance is more tightly linked to up-regulated ascorbate-dependent antioxidant activity than to the response of the thiol-redox regulatory network. The significance of the antioxidant system in surviving severe phases of dehydration is further supported by the strong antioxidant system usually encountered in resurrection plants

The Arabidopsis class II sirtuin is a lysine deacetylase and interacts with mitochondrial energy metabolism

The posttranslational regulation of proteins by lysine (Lys) acetylation has recently emerged to occur not only on histones, but also on organellar proteins in plants and animals. In particular, the catalytic activities of metabolic enzymes have been shown to be regulated by Lys acetylation. The Arabidopsis (Arabidopsis thaliana) genome encodes two predicted sirtuin-type Lys deacetylases, of which only Silent Information Regulator2 homolog (SRT2) contains a predicted presequence for mitochondrial targeting. Here, we have investigated the function of SRT2 in Arabidopsis. We demonstrate that SRT2 functions as a Lys deacetylase in vitro and in vivo. We show that SRT2 resides predominantly at the inner mitochondrial membrane and interacts with a small number of protein complexes mainly involved in energy metabolism and metabolite transport. Several of these protein complexes, such as the ATP synthase and the ATP/ADP carriers, show an increase in Lys acetylation in srt2 loss-of-function mutants. The srt2 plants display no growth phenotype but rather a metabolic phenotype with altered levels in sugars, amino acids, and ADP contents. Furthermore, coupling of respiration to ATP synthesis is decreased in these lines, while the ADP uptake into mitochondria is significantly increased. Our results indicate that SRT2 is important in fine-tuning mitochondrial energy metabolism

Eosinophilic Enteritis Confined to an Ileostomy Site

Eosinophilic enteritis is a rather rare condition that can manifest anywhere from esophagus to rectum. Its description in the literature is sparse, but associations have been made with collagen vascular disease, malignancy, food allergy, parasitic or viral infections, inflammatory bowel disease, and drug sensitivity. We present the case of a 41-year-old male diagnosed with ulcerative colitis who underwent proctocolectomy with ileal pouch anal anastomosis and loop ileostomy formation utilizing Seprafilm®, who later developed eosinophilic enteritis of the loop ileostomy site. This is the first report of eosinophilic enteritis and its possible link to the use of bioabsorbable adhesion barriers

Characterization of the Arabidopsis thaliana 2-Cys peroxiredoxin interactome

This document is the Accepted Manuscript of the following article: Delphine Cerveau, et al, ‘Characterization of the Arabidopsis thaliana 2-Cys peroxiredoxin interactome’, Plant Science, Vol. 252, pp. 30-41, July 2016, doi: https://doi.org/10.1016/j.plantsci.2016.07.003. This manuscript version is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License CC BY NC-ND 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way.Peroxiredoxins are ubiquitous thiol-dependent peroxidases for which chaperone and signaling roles havebeen reported in various types of organisms in recent years. In plants, the peroxidase function of thetwo typical plastidial 2-Cys peroxiredoxins (2-Cys PRX A and B) has been highlighted while the otherfunctions, particularly in ROS-dependent signaling pathways, are still elusive notably due to the lack ofknowledge of interacting partners. Using an ex vivo approach based on co-immunoprecipitation of leafextracts from Arabidopsis thaliana wild-type and mutant plants lacking 2-Cys PRX expression followedby mass spectrometry-based proteomics, 158 proteins were found associated with 2-Cys PRXs. Alreadyknown partners like thioredoxin-related electron donors (Chloroplastic Drought-induced Stress Proteinof 32 kDa, Atypical Cysteine Histidine-rich Thioredoxin 2) and enzymes involved in chlorophyll synthe-sis (Protochlorophyllide OxidoReductase B) or carbon metabolism (Fructose-1,6-BisPhosphatase) wereidentified, validating the relevance of the approach. Bioinformatic and bibliographic analyses allowedthe functional classification of the identified proteins and revealed that more than 40% are localized inplastids. The possible roles of plant 2-Cys PRXs in redox signaling pathways are discussed in relation withthe functions of the potential partners notably those involved in redox homeostasis, carbon and aminoacid metabolisms as well as chlorophyll biosynthesis.Peer reviewe

Efficient acclimation of the chloroplast antioxidant defence of Arabidopsis thaliana leaves in response to a 10- or 100-fold light increment and the possible involvement of retrograde signals

Chloroplasts are equipped with a nuclear-encoded antioxidant defence system the components of which are usually expressed at high transcript and activity levels. To significantly challenge the chloroplast antioxidant system, Arabidopsis thaliana plants, acclimated to extremely low light slightly above the light compensation point or to normal growth chamber light, were moved to high light corresponding to a 100- and 10-fold light jump, for 6 h and 24 h in order to observe the responses of the water–water cycle at the transcript, protein, enzyme activity, and metabolite levels. The plants coped efficiently with the high light regime and the photoinhibition was fully reversible. Reactive oxygen species (ROS), glutathione and ascorbate levels as well as redox states, respectively, revealed no particular oxidative stress in low-light-acclimated plants transferred to 100-fold excess light. Strong regulation of the water–water cycle enzymes at the transcript level was only partly reflected at the protein and activity levels. In general, low light plants had higher stromal (sAPX) and thylakoid ascorbate peroxidase (tAPX), dehydroascorbate reductase (DHAR), and CuZn superoxide dismutase (CuZnSOD) protein contents than normal light-grown plants. Mutants defective in components relevant for retrograde signalling, namely stn7, ex1, tpt1, and a mutant expressing E .coli catalase in the chloroplast showed unaltered transcriptional responses of water–water cycle enzymes. These findings, together with the response of marker transcripts, indicate that abscisic acid is not involved and that the plastoquinone redox state and reactive oxygen species do not play a major role in regulating the transcriptional response at t=6 h, while other marker transcripts suggest a major role for reductive power, metabolites, and lipids as signals for the response of the water–water cycle