The landscape of transcription factor promoter activity during vegetative development in Marchantia.

Transcription factors (TFs) are essential for the regulation of gene expression and cell fate determination. Characterizing the transcriptional activity of TF genes in space and time is a critical step toward understanding complex biological systems. The vegetative gametophyte meristems of bryophytes share some characteristics with the shoot apical meristems of flowering plants. However, the identity and expression profiles of TFs associated with gametophyte organization are largely unknown. With only ∼450 putative TF genes, Marchantia (Marchantia polymorpha) is an outstanding model system for plant systems biology. We have generated a near-complete collection of promoter elements derived from Marchantia TF genes. We experimentally tested reporter fusions for all the TF promoters in the collection and systematically analyzed expression patterns in Marchantia gemmae. This allowed us to build a map of expression domains in early vegetative development and identify a set of TF-derived promoters that are active in the stem-cell zone. The cell markers provide additional tools and insight into the dynamic regulation of the gametophytic meristem and its evolution. In addition, we provide an online database of expression patterns for all promoters in the collection. We expect that these promoter elements will be useful for cell-type-specific expression, synthetic biology applications, and functional genomics.

Stenotrophomonas maltophilia in people with Cystic Fibrosis: a systematic review of prevalence, risk factors and management.

To summarize the current knowledge of the clinical impact of Stenotrophomonas maltophilia (SM) in cystic fibrosis (CF) patients. A systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guideline recommendations, was performed through searches in PubMed and EMBASE databases, and CF National and International Registries websites from 2000 to 2022. Overall, 184 articles were initially retrieved, out of which 15 were selected and included in the review. Data form 6 Registries and 9 pertinent articles from the references of the studies selected were also considered, resulting in 30 studies in total. The prevalence of SM in patients with CF is increasing in Europe while it is declining in North America. The role of chronic colonization of SM on lung function and clinical status in CF patients is still under debate. The most recent studies suggested a pathogenic role of SM chronic infections in CF patients with an acceleration in lung function decline, an increase in hospitalization rates and an association with co-infection. Reflecting the uncertainty about the role of SM in CF, little is available about antibiotic therapeutic strategies for both acute exacerbations and chronic infections. Antimicrobial therapy should be performed in the acute exacerbations, while it may be reasonable to attempt eradication when the first colonization is identified. Nevertheless, it is not established which antibiotic regimen should be preferred, and overtreatment could contribute to the selection of antimicrobial-resistant strains. Further studies are warranted in this regard.

An enhancer trap system to track developmental dynamics in Marchantia polymorpha.

A combination of streamlined genetics, experimental tractability and relative morphological simplicity compared to vascular plants makes the liverwort Marchantia polymorpha an ideal model system for studying many aspects of plant biology. Here we describe a transformation vector combining a constitutive fluorescent membrane marker with a nuclear marker that is regulated by nearby enhancer elements and use this to produce a library of enhancer trap lines for Marchantia. Screening gemmae from these lines allowed the identification and characterization of novel marker lines, including markers for rhizoids and oil cells. The library allowed the identification of a margin tissue running around the thallus edge, highlighted during thallus development. The expression of this marker is correlated with auxin levels. We generated multiple markers for the meristematic apical notch region, which have different spatial expression patterns, reappear at different times during meristem regeneration following apical notch excision and have varying responses to auxin supplementation or inhibition. This reveals that there are proximodistal substructures within the apical notch that could not be observed otherwise. We employed our markers to study Marchantia sporeling development, observing meristem emergence as defining the protonema-to-prothallus stage transition, and subsequent production of margin tissue during the prothallus stage. Exogenous auxin treatment stalls meristem emergence at the protonema stage but does not inhibit cell division, resulting in callus-like sporelings with many rhizoids, whereas pharmacologically inhibiting auxin synthesis and transport does not prevent meristem emergence. This enhancer trap system presents a useful resource for the community and will contribute to future Marchantia research.

Anti-IL17 treatment in childhood chronic rheumatic diseases.

INTRODUCTION: Interleukin-17 (IL-17) is a family of cytokines that plays a key role in several rheumatic diseases in both adults and children. In the last few years, several drugs targeting IL-17 have been developed. AREAS COVERED: We present a review on the current state of the art regarding the use of anti-IL17 in childhood chronic rheumatic diseases. To date, the available evidence is limited and mainly focuses on juvenile idiopathic arthritis (JIA) and a specific autoinflammatory disease called deficiency of IL-36 receptor antagonist (DITRA). Recently, a randomized controlled trial resulted in the approval of secukinumab (an anti-IL17 monoclonal antibody) for JIA, due to its demonstrated efficacy and safety. Promising and potential uses of anti-IL17 in Behçet's syndrome and synovitis acne pustulosis hyperostosis osteitis (SAPHO) syndrome have also been described. EXPERT OPINION: Increasing knowledge about the pathogenetic mechanisms underlying rheumatic diseases is leading to an improvement in the care of several chronic autoimmune diseases. In this scenario, anti-IL17 therapies (such as secukinumab and ixekizumab) might be an optimal choice. Recent data on the use of secukinumab in juvenile spondyloarthropathies can be a starting point for future treatment strategies in other pediatric rheumatic diseases, such as Behçet's syndrome and the chronic non-bacterial osteomyelitis disease spectrum, particularly SAPHO syndrome.

Does mild intrahepatic cholestasis of pregnancy require an aggressive management? Evidence from a prospective observational study focused on adverse perinatal outcomes and pathological placental findings.

OBJECTIVE: To ascertain the most effective approach in pregnancies complicated by mild intrahepatic cholestasis of pregnancy (mICP) by evaluating rates of adverse perinatal outcomes (APOs) and pathological placental findings. METHODS: A total of 89 pregnancies complicated by mICP (defined as total serum bile acids (TSBAs) levels <40 µmol/L) were included. One-drug (ursodeoxycholic acid [UDCA]) (n = 49, 55.1%) and combined (UDCA plus S-adenosyl methionine (SAMe)) (n = 40, 44.9%) therapies were compared. RESULTS: No differences were found in demographic, obstetric, and placental characteristics. In UDCA plus SAMe group, premature delivery was a common clinical decision (14.3 versus 25%, p-value = .201), with increased rates of instrumental vaginal delivery (VD; 28.6 versus 40%, p-value = .522), but similar cesarean section (CS) rates (26.5 versus 25%, p-value = .498). Mean placental weight was comparable (UDCA, mean 595.7 g, SD 213.1 g versus UDCA plus SAMe, mean 586.4 g, SD 102.9 g, p-value = .875). A total of 110 lesions were identified, 64 in 25 placentas of patients assigned to the UDCA and 46 in 15 placentas of patients managed by UDCA plus SAMe. Placental findings attributable to maternal malperfusion were found in 41/25 and 32/15 cases treated by UCDA and UDCA plus SAMe (165 versus 213%, p-value = .774), pathological fetal vascular supply in 17/25 and 8/15 placentas (68 versus 53%, p-value = .777), and inflammatory lesions in 6/25 and 6/15 cases (24 versus 40%, p-value = .757). CONCLUSIONS: Pregnancies complicated by mICP and managed by UDCA alone present similar APO rates and placental histopathology if compared with those treated by UDCA plus SAMe, failing to recognize advantages in the combined therapy. Further prospective studies and data sharing from ongoing RTCs could drive changes in therapeutic plan.

The hornworts: morphology, evolution and development.

Extant land plants consist of two deeply divergent groups, tracheophytes and bryophytes, which shared a common ancestor some 500 million years ago. While information about vascular plants and the two of the three lineages of bryophytes, the mosses and liverworts, is steadily accumulating, the biology of hornworts remains poorly explored. Yet, as the sister group to liverworts and mosses, hornworts are critical in understanding the evolution of key land plant traits. Until recently, there was no hornwort model species amenable to systematic experimental investigation, which hampered detailed insight into the molecular biology and genetics of this unique group of land plants. The emerging hornwort model species, Anthoceros agrestis, is instrumental in our efforts to better understand not only hornwort biology but also fundamental questions of land plant evolution. To this end, here we provide an overview of hornwort biology and current research on the model plant A. agrestis to highlight its potential in answering key questions of land plant biology and evolution.

Systematic Tools for Reprogramming Plant Gene Expression in a Simple Model, Marchantia polymorpha.

We present the OpenPlant toolkit, a set of interlinked resources and techniques to develop Marchantia as testbed for bioengineering in plants. Marchantia is a liverwort, a simple plant with an open form of development that allows direct visualization of gene expression and dynamics of cellular growth in living tissues. We describe new techniques for simple and efficient axenic propagation and maintenance of Marchantia lines with no requirement for glasshouse facilities. Marchantia plants spontaneously produce clonal propagules within a few weeks of regeneration, and lines can be amplified million-fold in a single generation by induction of the sexual phase of growth, crossing, and harvesting of progeny spores. The plant has a simple morphology and genome with reduced gene redundancy, and the dominant phase of its life cycle is haploid, making genetic analysis easier. We have built robust Loop assembly vector systems for nuclear and chloroplast transformation and genome editing. These have provided the basis for building and testing a modular library of standardized DNA elements with highly desirable properties. We have screened transcriptomic data to identify a range of candidate genes, extracted putative promoter sequences, and tested them in vivo to identify new constitutive promoter elements. The resources have been combined into a toolkit for plant bioengineering that is accessible for laboratories without access to traditional facilities for plant biology research. The toolkit is being made available under the terms of the OpenMTA and will facilitate the establishment of common standards and the use of this simple plant as testbed for synthetic biology.

Phytophthora palmivora establishes tissue-specific intracellular infection structures in the earliest divergent land plant lineage.

The expansion of plants onto land was a formative event that brought forth profound changes to the earth's geochemistry and biota. Filamentous eukaryotic microbes developed the ability to colonize plant tissues early during the evolution of land plants, as demonstrated by intimate, symbiosis-like associations in >400 million-year-old fossils. However, the degree to which filamentous microbes establish pathogenic interactions with early divergent land plants is unclear. Here, we demonstrate that the broad host-range oomycete pathogen Phytophthora palmivora colonizes liverworts, the earliest divergent land plant lineage. We show that P. palmivora establishes a complex tissue-specific interaction with Marchantia polymorpha, where it completes a full infection cycle within air chambers of the dorsal photosynthetic layer. Remarkably, P. palmivora invaginates M. polymorpha cells with haustoria-like structures that accumulate host cellular trafficking machinery and the membrane syntaxin MpSYP13B, but not the related MpSYP13A. Our results indicate that the intracellular accommodation of filamentous microbes is an ancient plant trait that is successfully exploited by pathogens like P. palmivora.