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Sexual reproduction results in the development of haploid and diploid cell states during the life cycle. In bryophytes, the dominant multicellular haploid phase produces motile sperm that swim through water to the egg to effect fertilization from which a relatively small diploid phase develops. In angiosperms, the reduced multicellular haploid phase produces non-motile sperm that is delivered to the egg through a pollen tube to effect fertilization from which the dominant diploid phase develops. These different life cycle characteristics are likely to impact the distribution of genetic variation among populations. However, little is known about the distribution of genetic variation among wild populations of bryophytes. To investigate how genetic variation is distributed among populations of a bryophyte and to establish the foundation for population genetics research in bryophytes, we described the genetic diversity of collections of Marchantia polymorpha subsp. ruderalis, a cosmopolitan ruderal liverwort. We identified 78 genetically unique (non-clonal) from a total of 209 sequenced accessions collected from 37 sites in Europe and Japan. There was no detectable population structure among European populations but significant genetic differentiation between Japanese and European populations. By associating genetic variation across the genome with global climate data, we showed that temperature and precipitation influence the frequency of potentially adaptive alleles. This collection establishes the core of an experimental platform that exploits natural genetic variation to answer diverse questions in biology., Competing Interests: Declaration of interests L.D. is a co-founder, shareholder, and board member of MoA Technology., (Copyright © 2025 The Authors. Published by Elsevier Inc. All rights reserved.)

Meristems are three-dimensional (3D) generative structures that contain stem cells and produce new organs and tissues. Meristems develop in all land plants; however we know little about the spatial and temporal regulation of meristem structure in lineages such as bryophytes. Here, we describe the 3D meristem anatomy during the development of the liverwort Marchantia polymorpha. We show that the apical stem cell of the mature meristem is sub-apical, ventral, and in the outer cell layer. Mature meristem anatomy is therefore asymmetrical in the dorsoventral axis, which is reflected by the domain-specific protein localisation of Class III and Class IV Homeodomain-Leucine-Zippers (MpC3HDZ and MpC4HDZ), and by the promoter activity of MpYUCCA2. The dorsoventral asymmetry that defines the mature meristem is absent in the juvenile meristems of asexual propagules known as gemmae. We discovered that anatomical dorsoventral asymmetry of the meristem forms after 1 to 2 days of gemmaling growth, and is accompanied by expression of the dorsal identity reporter MpC3HDZ. We conclude that the gemma meristem has arrested development and undergoes anatomical rearrangement to develop the 3D meristem structure of the mature plant., Competing Interests: Competing interests L.D. is a founder of MoA Technology. He is also a member of the company's board and its scientific advisory board., (© 2024. Published by The Company of Biologists Ltd.)

The shape of modular organisms depends on the branching architecture, which in plants is determined by the fates of generative centers called meristems. The branches of the liverwort Marchantia polymorpha are derived from two adjacent meristems that develop at thallus apices. These meristems may be active and develop branches or may be dormant and do not form branches. The relative number and position of active and dormant meristems define the overall shape and form of the thallus. We show that the clade III SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factor MpSPL1 is required for meristem dormancy. The activity of MpSPL1 is regulated by the liverwort-specific Mpo-MR13 miRNA, which, in turn, is regulated by PIF-mediated signaling. An unrelated PIF-regulated miRNA, MIR156, represses a different SPL gene (belonging to clade IV) that inhibits branching during the shade avoidance response in Arabidopsis thaliana. This suggests that a conserved light signaling mechanism modulates branching architecture in liverworts and angiosperms and therefore is likely operated in the last common ancestor. However, PIF-mediated signaling represses the expression of different miRNA genes with different SPL targets during dichotomous, apical branching in liverworts and during lateral, subapical branching in angiosperms. We speculate that the mechanism that acts downstream of light and regulates meristem dormancy evolved independently in liverworts and angiosperms., Competing Interests: Declaration of interests L.D. is a co-founder of MoA Technology Ltd., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Herbicide resistance in weeds is a growing threat to global crop production. Non-target site resistance is problematic because a single resistance allele can confer tolerance to many herbicides (cross resistance), and it is often a polygenic trait so it can be difficult to identify the molecular mechanisms involved. Most characterized molecular mechanisms of non-target site resistance are caused by gain-of-function mutations in genes from a few key gene families-the mechanisms of resistance caused by loss-of-function mutations remain unclear. In this study, we first show that the mechanism of non-target site resistance to the herbicide thaxtomin A conferred by loss-of-function of the gene PAM16 is conserved in Marchantia polymorpha, validating its use as a model species with which to study non-target site resistance. To identify mechanisms of non-target site resistance caused by loss-of-function mutations, we generated 107 UV-B mutagenized M. polymorpha spores and screened for resistance to the herbicide thaxtomin A. We isolated 13 thaxtomin A-resistant mutants and found that 3 mutants carried candidate resistance-conferring SNPs in the MpRTN4IP1L gene. Mprtn4ip1l mutants are defective in coenzyme Q biosynthesis and accumulate higher levels of reactive oxygen species (ROS) than wild-type plants. Mutants are weakly resistant to thaxtomin A and cross resistant to isoxaben, suggesting that loss of MpRTN4IP1L function confers non-target site resistance. Mutants are also defective in thaxtomin A metabolism. We conclude that loss of MpRTN4IP1L function is a novel mechanism of non-target site herbicide resistance and propose that other mutations that increase ROS levels or decrease thaxtomin A metabolism could contribute to thaxtomin A resistance in the field., Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: L.D. and Cl. Ch. are co-founders of MoA Technology Ltd., (Copyright: © 2023 Casey et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Thlaspi arvense (field pennycress) is being domesticated as a winter annual oilseed crop capable of improving ecosystems and intensifying agricultural productivity without increasing land use. It is a selfing diploid with a short life cycle and is amenable to genetic manipulations, making it an accessible field-based model species for genetics and epigenetics. The availability of a high-quality reference genome is vital for understanding pennycress physiology and for clarifying its evolutionary history within the Brassicaceae. Here, we present a chromosome-level genome assembly of var. MN106-Ref with improved gene annotation and use it to investigate gene structure differences between two accessions (MN108 and Spring32-10) that are highly amenable to genetic transformation. We describe non-coding RNAs, pseudogenes and transposable elements, and highlight tissue-specific expression and methylation patterns. Resequencing of forty wild accessions provided insights into genome-wide genetic variation, and QTL regions were identified for a seedling colour phenotype. Altogether, these data will serve as a tool for pennycress improvement in general and for translational research across the Brassicaceae., (© 2022 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.)

Linking plant phenotype to genotype is a common goal to both plant breeders and geneticists. However, collecting phenotypic data for large numbers of plants remain a bottleneck. Plant phenotyping is mostly image based and therefore requires rapid and robust extraction of phenotypic measurements from image data. However, because segmentation tools usually rely on color information, they are sensitive to background or plant color deviations. We have developed a versatile, fully open-source pipeline to extract phenotypic measurements from plant images in an unsupervised manner. ARADEEPOPSIS (https://github.com/Gregor-Mendel-Institute/aradeepopsis) uses semantic segmentation of top-view images to classify leaf tissue into three categories: healthy, anthocyanin rich, and senescent. This makes it particularly powerful at quantitative phenotyping of different developmental stages, mutants with aberrant leaf color and/or phenotype, and plants growing in stressful conditions. On a panel of 210 natural Arabidopsis ( Arabidopsis thaliana ) accessions, we were able to not only accurately segment images of phenotypically diverse genotypes but also to identify known loci related to anthocyanin production and early necrosis in genome-wide association analyses. Our pipeline accurately processed images of diverse origin, quality, and background composition, and of a distantly related Brassicaceae. ARADEEPOPSIS is deployable on most operating systems and high-performance computing environments and can be used independently of bioinformatics expertise and resources., (© 2020 American Society of Plant Biologists. All rights reserved.)

From the cellular perspective, organ growth is determined by production and growth of cells. Uncovering how these two processes are coordinated is essential for understanding organogenesis and regulation of organ growth. We utilized phenotypic and genetic variation of 252 natural accessions of Arabidopsis thaliana to conduct genome-wide association studies (GWAS) for identifying genes underlying root growth variation; using a T-DNA line candidate approach, we identified one gene involved in root growth control and characterized its function using microscopy, root growth kinematics, G2/M phase cell count, ploidy levels and ribosome polysome profiles. We identified a factor contributing to root growth control: Arabidopsis Adenylate Kinase 6 (AAK6). AAK6 is required for normal cell production and normal cell elongation, and its natural genetic variation is involved in determining root growth differences between Arabidopsis accessions. A lack of AAK6 reduces cell production in the aak6 root apex, but this is partially compensated for by longer mature root cells. Thereby, aak6 mutants exhibit compensatory cell enlargement, a phenomenon unexpected in roots. Moreover, aak6 plants accumulate 80S ribosomes while the polysome profile remains unchanged, consistent with a phenotype of perturbed ribosome biogenesis. In conclusion, AAK6 impacts ribosome abundance, cell production and thereby root growth., (© 2019 The Authors. New Phytologist © 2019 New Phytologist Trust.)

To adapt to an ever-changing environment, animals consolidate some, but not all, learning experiences to long-term memory. In mammals, long-term memory consolidation often involves neural pathway reactivation hours after memory acquisition. It is not known whether this delayed-reactivation schema is common across the animal kingdom or how information is stored during the delay period. Here, we show that, during courtship suppression learning, Drosophila exhibits delayed long-term memory consolidation. We also show that the same class of dopaminergic neurons engaged earlier in memory acquisition is also both necessary and sufficient for delayed long-term memory consolidation. Furthermore, we present evidence that, during learning, the translational regulator Orb2A tags specific synapses of mushroom body neurons for later consolidation. Consolidation involves the subsequent recruitment of Orb2B and the activity-dependent synthesis of CaMKII. Thus, our results provide evidence for the role of a neuromodulated, synapse-restricted molecule bridging memory acquisition and long-term memory consolidation in a learning animal., (Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.)

Angiotensin II and endothelin-1 are potent vasoconstrictors that appear to play a role in retinal blood flow regulation. In the present study, we investigated the possible role of the angiotensin and the endothelin system in the regulation of retinal vessel diameters during isometric exercise in healthy humans. The study design was randomized, double-masked, placebo-controlled, and three-way cross over. Twelve healthy subjects performed squatting exercises for 6 min during infusion of either an angiotensin-converting enzyme inhibitor (enalapril), an ET(A)-receptor antagonist (BQ-123), or placebo. Retinal vessel diameters were measured continuously with the Zeiss retinal vessel analyzer. Systemic hemodynamics were assessed noninvasively, and intraocular pressure was measured with applanation tonometry. Squatting induced a significant increase in blood pressure and pulse rate, which was paralleled by a vasoconstriction in retinal arteries and veins. Intraocular pressure was only slightly increased during the squatting periods. BQ-123 significantly blunted the exercise-induced decrease in venous (P < 0.01) and arterial (P < 0.02, ANOVA) vessel diameters but had no effect on basal retinal diameters. By contrast, enalapril did neither influence vessel diameter at baseline conditions nor in response to isometric exercise. The data of the present study indicate that retinal vasoconstriction during isometric exercise is modified by ET(A)-receptor blockade, whereas it is not altered by angiotensin-converting enzyme inhibition. Hence, the present data indicate that endothelin-1, but not angiotensin II, is involved in retinal blood flow regulation during isometric exercise.

Background: We evaluated the validity of calculations for refractive outcome in cataract surgery in silicone oil-filled eyes. The retrosilicone space (RSS) was included in these calculations., Methods: In a prospective study the axial length (AL) of silicone oil-filled eyes was measured. with standardized A-scan echography (SAE) and partial coherence interferometry (PCI). Meldrum's formula was used to transform the velocity of ultrasound within the vitreous cavity. To investigate whether refractive outcome can be calculated accurately, we assessed the difference between precalculated and final refractive outcome. Furthermore, we determined the advantages and disadvantages of SAE and PCI. A minor aim was to assess whether the AL of the two eyes differed significantly., Results: In 85% of 117 eyes the difference between precalculated and postsurgical refraction was smaller than 1 diopter spherical and statistically not significant (p>0.2). The mean AL was 24.1 mm (range 20.0-31.4 mm). The difference in outcome between the two methods was without statistical significance: the AL difference was 0.4 (+/-2.6) mm on measurement with SAE and 0.04 (+/-0.46) mm with PCI. PCI has the advantage that it can be performed more easily, without contact, while echography is advantageous in the presence of advanced cataracts. In supine position an oil-free fluid space behind the silicone oil was detected with echography. The mean dimension of this space was 1.9 (+/-0.67) mm and it was taken into consideration for IOL calculation. The mean AL difference between the two eyes was 0.4 mm, but the difference was greater than 1 mm in 26% of the patients., Conclusion: The AL of eyes filled with silicone oil can be measured reliably with SAE and PCI. In supine position the RSS has to be considered to obtain more accurate IOL calculations.

There is evidence from in vitro and animal studies that endothelin is a major regulator of retinal blood flow. We set out to characterize the role of the endothelin-system in the blood flow control of the human retina. Two studies in healthy subjects were performed. The study design was randomized, placebo-controlled, double-masked, balanced, two-way crossover in protocol A and three way-way crossover in protocol B. In protocol A 18 healthy male subjects received intravenous endothelin-1 (ET-1) in a dose of 2.5 ng kg (-1)min(-1) for 30 min or placebo on two different study days and retinal vessel diameters were measured. In protocol B 12 healthy male subjects received ET-1 in stepwise increasing doses of 0, 1.25, 2.5 and 5 ng kg (-1)min(-1) (each infusion step over 20 min) in co-infusion with the specific ET(A)-receptor antagonist BQ123 (60 microg min (-1)) or placebo or BQ123 alone investigating retinal vessel diameters, retinal blood velocity and retinal blood flow. Measurements of retinal vessel size were done with the Zeiss retinal vessel analyzer. Measurements of blood velocities were done with bi-directional laser Doppler velocimetry. From these measurements retinal blood flow was calculated. In protocol A exogenous ET-1 tended to decrease retinal arterial diameter, but this effect was not significant versus placebo. No effect on retinal venous diameter was seen. In protocol B retinal venous blood velocity and retinal blood flow was significantly reduced after administration of exogenous ET-1. These effects were significantly blunted when BQ-123 was co-administered. By contrast, BQ-123 alone had no effect on retinal hemodynamic parameters. Concluding, BQ123 antagonizes the effects of exogenously administered ET-1 on retinal blood flow in healthy subjects. In addition, the results of the present study are compatible with the hypothesis that ET-1 exerts its vasoconstrictor effects in the retina mainly on the microvessels.

Purpose: A solar eclipse occurred in central Europe on August 11th, 1999. Following the eclipse, patients with ocular symptoms were investigated. Gazing at the sun without protection is liable to damage the retina. Our attention was focused on changes of the ocular surface and the tear film., Methods: Forty-three patients were investigated within one week after the solar eclipse as baseline. 33 of them were followed up one year later. Visual acuity and the central visual-field were measured, and the ocular surface and the fundus were examined using a slit lamp. The quality of the lacrimal tear film was examined using Schirmer's test for the aqueous layer, break-up time for the mucous layer and interference observation for the lipid layer, measured by a slit lamp and a tearoscope., Results: At the baseline 19 patients had non-specific visual problems. Pathological alterations of the tear film were seen in all three tear-film layers: Schirmer's test was pathological in 87%, break-up time decreased in 85%, the interference pattern of the lipid layer changed in 67% and there were changes in 87% using the tearoscope. One year later the non specific visual disorders had disappeared. Schirmer's test did not reveal much change from the baseline: 51% pathological, 24% remained pathological in break-up-time and the lipid layer was normalized except in 9%. Using the tearoscope, lipids were better than grade 3 in all patients., Conclusion: After gazing at a solar eclipse the ocular surface and tear film changed. While the aqueous layer remained pathological in many patients, the lipid layer and the mucous layer recovered spontaneously.

Background: The breakdown of the blood-retina barrier in diabetic patients is correlated with a dysfunction of the blood-aqueous barrier. In our study, we wanted to investigate the effect of grid photocoagulation in diabetic macular edema on the aqueous flare., Methods: Modified grid pattern photocoagulation was performed on 20 patients with diabetic macular edema. The aqueous flare intensity was measured by the laser flare cell meter before and 4 months after laser treatment., Results: The mean flare value was 9.8 +/- 4.7 photons/ms before laser treatment. After grid photocoagulation, the flare value was 7.1 +/- 3.6 photons/ms. Flare values were significantly decreased after laser treatment., Conclusion: Our results suggest a correlation between the effect of grid photocoagulation on the blood-retina barrier and the permeability of the blood-aqueous barrier. The laser flare intensity seems to be a quantitative indicator for the diabetic dysfunction of the blood-retina barrier., (Copyright 2003 S. Karger AG, Basel)

Background: Compared to non-diabetic patients, outcome after cataract surgery was reported to be worse in diabetic patients--especially in those with diabetic retinopathy. This prospective study was planned to evaluate visual outcome, progression of diabetic retinopathy, and incidence of clinically significant macular oedema (CSME) in a homogenous group of patients with non-proliferative diabetic retinopathy (NPDR) without CSME at baseline 1 year after cataract surgery., Methods: Over a period of 18 months, all consecutive patients with mild-to-moderate diabetic retinopathy who had cataract surgery with phacoemulsification and posterior chamber lens implantation were prospectively followed up. Outcomes were assessed 1 year postoperatively and included visual acuity (VA), progression of retinopathy, and incidence of CSME. Progression of retinopathy and incidence of CSME were compared to the non-operated fellow eyes., Results: Of 50 patients included, 42 completed the 1-year follow-up. VA improved in 85% of patients, and was better than 0,5 in 71%. Progression of retinopathy occurred in 12% of eyes after cataract surgery and in 10.8% of non-operated fellow eyes. No patient developed proliferative diabetic retinopathy in the operated eye. CSME occurred in 13 operated eyes (31%), five of them with retinal ischemia, and in five non-operated eyes (13.5%). Patients with ischemic macular oedema had the worst prognosis regarding VA., Conclusion: Modern cataract surgery seems to have no influence on the progression of diabetic retinopathy. A visual improvement is achieved in the majority of patients with NPDR, but poorer visual outcome is observed in patients developing macular oedema.

Purpose: To gain insight into the role of circulating catecholamines on retinal blood flow in vivo., Design: Nonrandomized, open, crossover design., Participants: In 10 healthy male subjects, tyramine and noradrenaline were administered in stepwise increasing doses. These doses were selected to induce comparable changes in systemic blood pressure., Methods: During each infusion step, retinal vessel diameter and retinal venous blood speed were measured with the Zeiss retinal vessel analyzer (Zeiss, Jena, Germany) and laser Doppler velocimetry, respectively., Main Outcome Measures: Retinal blood flow through a major temporal vein was calculated., Results: As expected, tyramine and noradrenaline induced a systemic hypertensive response. Tyramine caused a moderate increase in noradrenaline plasma levels, whereas exogenous noradrenaline increased noradrenaline plasma levels more than 10-fold. Nevertheless, neither tyramine nor noradrenaline induced any effect on retinal hemodynamic parameters., Conclusions: These data indicate that even high levels of circulating noradrenaline have little impact on retinal vascular tone and retinal blood flow. Hence, the adrenergic system appears not to play a major role in retinal blood flow regulation.

Pain that does not respond to conventional treatment procedures makes it necessary to look for alternative methods. Acupuncture is an ancient procedure with empirical effects on pain. Previous studies established the increased output of messengers at neuronal junctions in spinal cord and hypothalamic locations, especially of endorphins which inhibit the perception of pain. We treated several painful symptoms with acupuncture and evaluated the outcome of the treatment. Patients with various kinds of therapy-refractory pain and patients in whom conventional treatment methods could not be applied were included in the study. The diagnoses included glaucoma. Tolosa-Hunt-Syndrome, ophthalmic migraine, blepharospasm, and dry eyes. In one case acupuncture was used for analgesia during surgery. Acupuncture was performed with sterile disposable needles, at points known to have an empirical analgesic effect. The stimulation was adapted to the patient's individual needs. VAS assessments before and after acupuncture were compared. The t-test was used for statistical evaluation. Acupuncture had no side effects, but reduced pain to a variable extent. Especially in cases of severe pain and in surgery, very effective pain reduction was achieved. In general, pain was significantly reduced in all patients by the use of acupuncture. A statistically significant effect was noted (p < 0.05). Further studies should be conducted to demonstrate the specific effect in larger patient populations. Monitoring neurotransmitter activity will possibly help to illustrate the effect.

This study was performed to test viscoelastic artificial tears (VAT) based on both subjective and clinical parameters in patients with keratoconjunctivitis sicca (KCS). Twenty-eight patients were evaluated in a randomized double-blind study. Sodium hyaluronate was used in two different concentrations (0.4%, 0.25%) and in combination with chondroitin sulfate. Each preparation was used for one week preceded by another weekly cycle using a sodium chloride solution. Before and after each cycle, clinical examinations were performed: tear film break-up time, Schirmer's test, lipid-layer thickness and fluorescein staining. Patients kept a record of the drop-frequency, subjective response and side effects. After the study, they were asked to give a rating of the various preparations. The severity of KCS was expressed based on a sicca score and correlated with response to viscoelastic treatment. Both the subjective and the clinical parameters revealed no statistically significant differences between the various viscoelastic agents or between the viscoelastics and the sodium chloride solutions. Severe side effects did not occur. There was a positive correlation of response to viscoelastic treatment with severe KCS (+ 0.36) but not with mild KCS (-0.07). The VAT seems to be indicated in severe cases of dry-eye syndrome. Sodium chloride solutions may be a useful short-term alternative to other tear formulations.

Purpose: There is controversy regarding the nervous control of retinal blood vessels in humans. Most in vitro studies indicate that the intraocular part of the central retinal artery lacks autonomic innervation. We investigated the response of retinal vessels to isometric exercise during blockade of beta-receptors (propranolol) or muscarinic receptors (atropine)., Methods: Twelve healthy subjects performed squatting for 6 min during infusion of either propranolol atropine or placebo. Blood pressure and pulse rate were measured non-invasively. Retinal vessel diameters were measured continuously using the Zeiss Retinal Vessel Analyser., Results: Squatting induced a significant increase in blood pressure and pulse rate, which was paralleled by a decrease in retinal vein and artery diameters. Atropine did not change the retinal vessel response to isometric exercise. Propranolol significantly blunted the exercise-induced vasoconstriction in retinal arteries., Conclusion: This result likely indicates propranolol-evoked vasoconstriction in the extraocular parts of the central retinal artery during isometric exercise., (Copyright 2001 S. Karger AG, Basel)

Background: The treatment of pterygia often results in irregular astigmatism. Corneal smoothing at the end of surgery plays a major role in the development of astigmatism. The aim of our study was to compare the efficiency of corneal smoothing performed by phototherapeutic keratectomy compared with the conventional method performed by a diamond fraise. The effect of postoperative excimer laser smoothing on refraction, visual acuity and irregular astigmatism was investigated., Patients and Methods: 32 eyes underwent pterygium excision using a standardized surgical procedure. In addition 9 eyes underwent postoperative phototherapeutic keratectomy of the wound region with an excimer laser, 23 eyes were treated with a diamond fraise for corneal smoothing. The postoperative examination was performed 7, 14 and 30 days after surgery. Corneal topography was performed by a computer-assisted videokeratoscope (TMS-1). The results were evaluated by the Fourier transform analysis., Results: Both methods showed similar results concerning refraction and visual acuity postoperatively. Preoperatively all patients had an irregular flattening of the corneal topography in the area of the pterygium. Postoperatively a small irregular flattening was left in eyes treated with a diamond fraise. In the excimer laser treated group a steepening in the corneal topography could be observed., Conclusions: The phototherapeutic keratectomy with excimer laser in the treatment of pterygia suggests to be a gentle alternative creating a smooth wound surface. Despite of this advantage the treatment with the excimer laser effects a remarkable increase in administration and expense.