Division Wall Research Articles

The Diverse Activities and Mechanisms of the Acylphloroglucinol Antibiotic Rhodomyrtone: Antibacterial Activity and Beyond.

Background/Objectives: The rose myrtle Rhodomyrtus tomentosa is a medicinal plant used in traditional Asian medicine. The active compound in R. tomentosa leaf extracts is rhodomyrtone, a chiral acylphloroglucinol. Rhodomyrtone exhibits an impressive breadth of activities, including antibacterial, antiviral, antiplasmodial, immunomodulatory, and anticancer properties. Its antibacterial properties have been extensively studied. Methods: We performed a comprehensive literature review on rhodomyrtone and summarized the current knowledge about this promising acylphloroglucinol antibiotic and its diverse functions in this review. Results: Rhodomyrtone shows nano to micromolar activities against a broad range of Gram-positive pathogens, including multidrug-resistant clinical isolates, and possesses a unique mechanism of action. It increases membrane fluidity and creates hyperfluid domains that attract membrane proteins prior to forming large membrane vesicles, effectively acting as a membrane protein trap. This mechanism affects a multitude of cellular processes, including cell division and cell wall synthesis. Additionally, rhodomyrtone reduces the expression of inflammatory cytokines, such as TNF-α, IL-17A, IL1β, and IL8. Generally showing low toxicity against mammalian cells, rhodomyrtone does inhibit the proliferation of cancer cell lines, such as epidermal carcinoma cells. The primary mechanism behind this activity appears to be the downregulation of adhesion kinases and growth factors. Furthermore, rhodomyrtone has shown antioxidant activity and displays cognitive effects, such as decreasing depressive symptoms in mice. Conclusions: Rhodomyrtone shows great promise as therapeutic agent, mostly for antibacterial but also for diverse other applications. Yet, bottlenecks such as resistance development and a better understanding of mammalian cell toxictiy demand careful assessment.

A network pharmacology-based approach to understand the mechanism of action of anti-mycobacterial activity of Acacia nilotica: a modelling and experimental study.

The rapid rise in drug-resistant tuberculosis poses a serious threat to public health and demands the discovery of new anti-mycobacterial agents. Medicinal plants are a proven potential source of bioactive compounds; however, identifying those responsible for the putative anti-mycobacterial action still remains a challenging task. In this study, we undertook a systematic network pharmacology approach to identify and evaluate anti-mycobacterial compounds from a traditional plant, Acacia nilotica, as a model system. The protein-protein interaction network revealed 17 key pathways in M. tuberculosis encompassing 40 unique druggable targets that are necessary for its growth and survival. The phytochemicals of A. nilotica were preferentially found to interfere with the cell division and cell wall biogenesis proteins, especially FtsZ and Mur. Notably, the compounds epigallocatechin, ellagic acid, chlorogenic acid, and D-pinitol were found to exhibit a potential polypharmacological effect against multiple proteins. Further, in vitro studies confirmed that the selected candidates, chlorogenic acid, and ellagic acid exhibited potent anti-mycobacterial activity (against M. smegmatis) with specific inhibition of purified M.tb FtsZ enzyme. Taken together, the present study demonstrates that network pharmacology combined with molecular docking can be utilized as an efficient approach to identify potential bioactive phytochemicals from natural products along with their mechanism of action. Hence, the compounds identified in this study can be potential lead candidates for developing novel anti-mycobacterial drugs, while the key proteins identified here can be potential drug targets.

Liana attachment to supports leads to profound changes in xylem anatomy and transcriptional profile of cambium and differentiating xylem.

Wood serves crucial functions in plants, yet our understanding of the mechanisms governing the composition, arrangement, and dimensions of its cells remains limited. The abrupt transition from nonlianescent to lianescent xylem in lianas represents an excellent model to address the underlying mechanisms, although consistent triggering factors for this process remain uncertain. In this study we examined how physical support attachment impacts the development of lianescent xylem in Bignonia magnifica (Bignoniaceae), employing a comprehensive approach integrating detailed anatomical analysis with gene expression profiling of cambium and differentiating xylem. Our findings demonstrate that attachment to physical supports triggers the formation of lianescent xylem, leading to increased vessel size, broader vessel distribution, reduced fibre content, and higher potential specific water conductivity than nonlianescent xylem. These shifts in wood anatomy coincide with the downregulation of genes associated with cell division and cell wall biosynthesis, and the upregulation of transcription factors, defense/cell death, and hormone-responsive genes in the lianescent xylem. Our findings provide insights into the regulation of xylem differentiation, driven by response to environmental stimuli. Additionally, they shed light on the mechanisms underlying the adaptation of lianas to climbing.

The Forkhead Box Gene, MaSep1, Negatively Regulates UV- and Thermo-Tolerances and Is Required for Microcycle Conidiation in Metarhizium acridum.

Insect pathogenic fungi have shown great potential in agricultural pest control. Conidiation is crucial for the survival of filamentous fungi, and dispersal occurs through two methods: normal conidiation, where conidia differentiate from mycelium, and microcycle conidiation, which involves conidial budding. The conidiation process is related to cell separation. The forkhead box gene Sep1 in Schizosaccharomyces pombe plays a crucial role in cell separation. Nevertheless, the function of Sep1 has not been clarified in filamentous fungi. Here, MaSep1, the homolog of Sep1 in Metarhizium acridum, was identified and subjected to functional analysis. The findings revealed that conidial germination of the MaSep1-deletion strain (ΔMaSep1) was accelerated and the time for 50% germination rate of conidial was shortened by 1 h, while the conidial production of ΔMaSep1 was considerably reduced. The resistances to heat shock and UV-B irradiation of ΔMaSep1 were enhanced, and the expression of some genes involved in DNA damage repair and heat shock response was significantly increased in ΔMaSep1. The disruption of MaSep1 had no effect on the virulence of M. acridum. Interestingly, ΔMaSep1 conducted the normal conidiation on the microcycle conidiation medium, SYA. Furthermore, 127 DEGs were identified by RNA-Seq between the wild-type and ΔMaSep1 strains during microcycle conidiation, proving that MaSep1 mediated the conidiation pattern shift by governing some genes associated with conidiation, cell division, and cell wall formation.

The impact of drought on phellem development: Identification of novel gene regulators and evidence of photosynthetic activity in cork oak stems

Quercus suber (cork oak) is a sustainably exploited forest resource, producing a unique renewable raw material known as cork. With drought events imposing a negative impact on tree vitality, further research is needed to enhance our understanding of the genetic and environmental factors regulating cork development, to foster the resilience of cork oak ecosystems. We focused on characterizing long-term drought-induced molecular adaptations occurring in stems, and identifying key genetic pathways regulating phellem development. One-year-old cork oak plants were grown for 6 months under well-watered, or water-deficit (WD) conditions and main stems were targeted for histological characterization and transcriptomic analysis. WD treatment reduced meristem activity at both vascular cambium and phellogen, impairing secondary growth. Transcriptional analysis revealed a global downregulation of genes related to cell division, differentiation, and cell wall biogenesis in phellem, inner bark, and xylem under WD conditions. Phellem and inner bark showed upregulation of photosynthesis-related genes, highlighting a determinant role of stem photosynthesis in the adaptation to long-term drought. We show that developing phellem cells contain chloroplasts and their abundance increases under WD. Lastly, we propose new candidate regulatory genes involved in regulating phellogen activity and demonstrate the role of phellem in drought-induced bark photosynthesis in young plants.

The yeast gene ECM9 regulates cell wall maintenance and cell division in stress conditions.

Saccharomyces cerevisiae , Baker's yeast, is a well-studied model eukaryotic organism. Much of our knowledge about eukaryotic cell function comes from yeast studies, though nearly 10% of yeast genes remain uncharacterized. This study focuses on YKR004C, a verified gene of unknown function named ECM9 , predicted to be involved in cell division and cell wall maintenance or composition based on previous studies. We investigated the sensitivity in stress conditions of an ECM9 deletion strain, compared to wild-type, to cell wall integrity. These results suggest that ECM9 is involved in cell wall maintenance and the regulatory pathway determining cell division readiness under stress.

Reassessment of Archaeooides based on new material from the Fortunian (early Cambrian) of China infers algal affinity

Archaeooides originally refers to a group of early Cambrian globular microfossils with regularly arranged nodular surface ornaments, and of a diameter ranging from less than 400 μm to more than 2 mm. The traditional taxonomy assigns all Archaeooides-like microfossils to a single morphotaxon, Archaeooides granulatus, irrespective of their differences in size and surface ornamentation. Archaeooides has been interpreted as a possible diapause embryo because of its inferred palintomical cell division and thick wall with vesicular structures. However, this interpretation needs further testing based on an updated taxonomy and differentiation of taphonomic artifacts from biological structures. Here, we report new, three-dimensionally phosphatized, Archaeooides-like microfossils from the Fortunian of China. In addition to A. granulatus with nodular ornaments, we recognized three new taxa, i.e., Shaanisphaera spinosa gen. et sp. nov. with spine-like ornaments, Qinlingisphaera conica gen. et sp. nov. with cone-like ornaments, and Dahisphaera plana gen. et sp. nov. with oblate ornaments. Each taxon has a wide size interval, ranging continuously from several hundred micrometers to one or two millimeters, which is different from animal eggs that generally have a narrow and conservative size interval. Micro-CT analyses and thin sections reveal that the vesicular structures may be taphonomic in nature, and that the wall thickness is specimen-dependent. Collectively, the evidence at hand does not support an embryo interpretation for Archaeooides. Instead, the wide size interval probably represents ontogenetic variations that are common in many fossil and modern algae, and thus further suggests an algal affinity for Archaeooides as well as the other Archaeooides-like microfossils.

NIR ICG-Enhanced Fluorescence: A Quantitative Evaluation of Bowel Microperfusion and Its Relation to Central Perfusion in Colorectal Surgery

Background: To date, no standardized protocols nor a quantitative assessment of the near-infrared fluorescence angiography with indocyanine green (NIR-ICG) are available. The aim of this study was to evaluate the timing of fluorescence as a reproducible parameter and its efficacy in predicting anastomotic leakage (AL) in colorectal surgery. Methods: A consecutive cohort of 108 patients undergoing minimally invasive elective procedures for colorectal cancer was prospectively enrolled. The difference between macro and microperfusion (ΔT) was obtained by calculating the timing of fluorescence at the level of iliac artery division and colonic wall, respectively. Results: Subjects with a ΔT ≥ 15.5± 0.5 s had a higher tendency to develop an AL (p < 0.01). The ΔT/heart rate interaction was found to predict AL with an odds ratio of 1.02 (p < 0.01); a cut-off threshold of 832 was identified (sensitivity 0.86, specificity 0.77). Perfusion parameters were also associated with a faster bowel motility resumption and a reduced length of hospital stay. Conclusions: The analysis of the timing of fluorescence provides a quantitative, easy evaluation of tissue perfusion. A ΔT/HR interaction ≥832 may be used as a real-time parameter to guide surgical decision making in colorectal surgery.

Ancient origin and constrained evolution of the division and cell wall gene cluster in Bacteria.

The division and cell wall (dcw) gene cluster in Bacteria comprises 17 genes encoding key steps in peptidoglycan synthesis and cytokinesis. To understand the origin and evolution of this cluster, we analysed its presence in over 1,000 bacterial genomes. We show that the dcw gene cluster is strikingly conserved in both gene content and gene order across all Bacteria and has undergone only a few rearrangements in some phyla, potentially linked to cell envelope specificities, but not directly to cell shape. A large concatenation of the 12 most conserved dcw cluster genes produced a robust tree of Bacteria that is largely consistent with recent phylogenies based on frequently used markers. Moreover, evolutionary divergence analyses show that the dcw gene cluster offers advantages in defining high-rank taxonomic boundaries and indicate at least two main phyla in the Candidate Phyla Radiation (CPR) matching a sharp dichotomy in dcw gene cluster arrangement. Our results place the origin of the dcw gene cluster in the Last Bacterial Common Ancestor and show that it has evolved vertically for billions of years, similar to major cellular machineries such as the ribosome. The strong phylogenetic signal, combined with conserved genomic synteny at large evolutionary distances, makes the dcw gene cluster a robust alternative set of markers to resolve the ever-growing tree of Bacteria.

Phenotypic Characterization and Fine Mapping of a Major-Effect Fruit Shape QTL FS5.2 in Cucumber, Cucumis sativus L., with Near-Isogenic Line-Derived Segregating Populations.

Cucumber (Cucumis sativus L.) fruit size/shape (FS) is an important yield and quality trait that is quantitatively inherited. Many quantitative trait loci (QTLs) for fruit size/shape have been identified, but very few have been fine-mapped or cloned. In this study, through marker-assisted foreground and background selections, we developed near-isogenic lines (NILs) for a major-effect fruit size/shape QTL FS5.2 in cucumber. Morphological and microscopic characterization of NILs suggests that the allele of fs5.2 from the semi-wild Xishuangbanna (XIS) cucumber (C. s. var. xishuangbannesis) reduces fruit elongation but promotes radial growth resulting in shorter but wider fruit, which seems to be due to reduced cell length, but increased cellular layers. Consistent with this, the NIL carrying the homozygous XIS allele (fs5.2) had lower auxin/IAA contents in both the ovary and the developing fruit. Fine genetic mapping with NIL-derived segregating populations placed FS5.2 into a 95.5 kb region with 15 predicted genes, and a homolog of the Arabidopsis CRABS CLAW (CsCRC) appeared to be the most possible candidate for FS5.2. Transcriptome profiling of NIL fruits at anthesis identified differentially expressed genes enriched in the auxin biosynthesis and signaling pathways, as well as genes involved in cell cycle, division, and cell wall processes. We conclude that the major-effect QTL FS5.2 controls cucumber fruit size/shape through regulating auxin-mediated cell division and expansion for the lateral and longitudinal fruit growth, respectively. The gibberellic acid (GA) signaling pathway also plays a role in FS5.2-mediated fruit elongation.

Construction of a highly saturated genetic map and identification of quantitative trait loci for leaf traits in jujube.

Chinese jujube (Ziziphus jujuba Mill.), a member of the genus Ziziphus, which comes under the family Rhamnaceae, is the most important species in terms of its economic, ecological, and social benefits. To dissect the loci associated with important phenotypical traits and analyze their genetic and genomic information in jujube, a whole-genome resequencing (WGR) based highly saturated genetic map was constructed using an F1 hybrid population of 140 progeny individuals derived from the cross of ‘JMS2’ × ‘Jiaocheng 5’. The average sequencing depth of the parents was 14.09× and that of the progeny was 2.62×, and the average comparison efficiency between the sample and the reference genome was 97.09%. Three sets of genetic maps were constructed for a female parent, a male parent, and integrated. A total of 8,684 markers, including 8,158 SNP and 526 InDel markers, were evenly distributed across all 12 linkage groups (LGs) in the integrated map, spanning 1,713.22 cM with an average marker interval of 0.2 cM. In terms of marker number and density, this is the most saturated genetic map of jujube to date, nearly doubling that of the best ones previously reported. Based on this genetic map and phenotype data from 2019 to 2021, 31 leaf trait QTLs were identified in the linkage groups (LG1, 15; LG3, 1; LG5, 8; LG7, 4; LG8, 1, and LG11, 2), including 17 major QTLs. There were 4, 8, 14, and 5 QTLs that contributed to leaf length, leaf width, leaf shape index, and leaf area, respectively. Six QTLs clusters were detected on LG1 (8.05 cM–9.52 cM; 13.12 cM–13.99 cM; 123.84 cM–126.09 cM), LG5 (50.58 cM–50.86 cM; 80.10 cM–81.76 cM) and LG11 (35.98 cM–48.62 cM). Eight candidate genes were identified within the QTLs cluster regions. Annotation information showed that 4 genes (LOC107418196, LOC107418241, LOC107417968, and LOC112492570) in these QTLs are related to cell division and cell wall integrity. This research will provide a valuable tool for further QTL analysis, candidate gene identification, map-based gene cloning, comparative mapping, and marker-assisted selection (MAS) in jujube.

Numerical study on dynamic ash deposition and heat transfer characteristics of radiant syngas cooler

Ash deposition greatly influences the performance of Radiant Syngas Cooler (RSC) which plays a pivotal role in the heat recovering process in coal gasification technology. Therefore, a numerical model of ash deposition coupled with heat transfer is established in present study to predict the ash deposition of RSC, and the effects of inlet temperature and division wall structure on deposition characteristics are further discussed. The simulation results indicate that the particle impact mainly occurs in the transition region of the jet flow to plug flow, while the particle deposit mainly occurs in the recirculation region. The deposition of inner wall and division wall shows a malignant growth pattern successively with the width increase of division wall. The division wall of 400 mm width is more conducive to the safe and stable operation of the RSC than those of 250 mm and 650 mm. The deposition becomes heavy with the increase of inlet temperature, and the deposition of division wall belongs to the slow growth, the large-scale detaching and the malignant growth pattern at the inlet temperature of 1573 K, 1673 K and 1773 K, respectively. Present result may provide a reference for the structural design and operational adjustment of RSC.

PagDET2 promotes cambium cell division and xylem differentiation in poplar stem.

Secondary growth of the woody tree stem is governed by meristematic cell division and differentiation in the vascular cambium. Multiple hormonal signals and endogenous developmental programs regulate vascular cambium activity. Brassinosteroids (BRs) significantly promote secondary stem growth and wood formation in poplar trees. However, the underlying regulatory mechanisms of BRs within the vascular tissue remain unclear. Genetic and anatomical approaches were used here to elucidate the role of PagDET2, the rate-limiting enzyme for BRs biosynthesis, in regulating secondary vascular cambium activity in Populus. This study showed that the elevated endogenous castasterone (CS) levels in tree stems through overexpressing PagDET2 could enhance cambium meristem cell activity and xylem (XY) differentiation to promote secondary stem growth. RNA-seq analysis revealed that genes involved in BRs response, vascular cambium cell division, XY differentiation, and secondary cell wall synthesis were up-regulated.

Understanding the adaptive laboratory evolution of multiple stress-resistant yeast strains by genome-scale modeling.

Stress responses triggered by external exposures in adaptive laboratory evolution studies alter the ordinary behavior of cells, and the identification of the differences between the starting and the evolved strains would provide ideal strategies to obtain the desired strains. Metabolic networks are one of the most useful tools to analyze data for this purpose. This study integrates differential expression profiles of multiple Saccharomyces cerevisiae strains that have evolved in eight different stress conditions (ethanol, caffeine, coniferyl aldehyde, iron, nickel, phenylethanol, and silver) and enzyme kinetics into a genome-scale metabolic model of yeast, following a new enhanced method. Flux balance analysis, flux variability analysis, robustness, phenotype phase plane, minimization of metabolic adjustment, survivability, sensitivity analyses, and random sampling are conducted to identify the most common and divergent points within strains. Results were examined both individually and comparatively, and the target reactions, metabolites, and enzymes were identified. Our results showed that the models reconstructed by our methodology were able to simulate experimental conditions where efficient protein allocation was the main goal for survival under stressful conditions, and most of the metabolic changes in the adaptation process mainly arose from the differences in the metabolic reactions of energy maintenance (through coenzyme-A and FAD utilization), cell division (folate requirement of DNA synthesis), and cell wall formation (through sterol and ergosterol biosynthesis).

A Mechanistic Study of the Antibacterial Activity of Phytoconstituents of Pyracantha crenulata by Using Molecular Docking Studies

Background: Bacteria cause various infections and are a threat to the health system. This threat is increased due to the resistance of bacteria towards antibacterial drugs. Plants are an important source of drugs including antibacterial agents. Pyracantha crenulata is one important plant known for its different medicinal uses. It contains different phytoconstituents responsible for its medicinal properties. In cholera, ToxT (PDB ID: 3GBG) regulates the expression of virulence factors in Vibrio cholerae. FtsZ (PDB ID: 6RVN) is a protein involved in cell division and septal wall synthesis in bacteria. MurA (PDB ID: 3SWQ) is critical for the biosynthesis of the bacterial cell wall. Flavin mononucleotide (FMN) (PDB ID: 3F2Q) is involved in the biosynthesis and transport of several protein cofactors. In most of the studies on phytoconstituents, the mechanism of action is not described. Therefore, in this study, the above target proteins were selected and specific target inhibitors were used as standard drugs. In light of the above-mentioned facts, we have proposed a mechanism of antibacterial action of phytoconstituents of Pyracantha crenulata based on molecular docking studies. Objective: To propose a mechanism of antibacterial action of phytoconstituents of Pyracantha crenulata based on molecular docking studies. Methods: Molecular docking studies of phytoconstituents of Pyracantha crenulata were performed using the Maestro 12.8 module of Schrodinger software Results: Molecular docking results indicated that many constituents including rutin and phloridzin had better dock scores than standard drugs against different antibacterial targets. Conclusion: From the molecular docking, different constituents may act as good inhibitors of different proteins like phloridzin may act as potent inhibitors of 3GBG, 6RVN, and 3SWQ, which can be used further for the development of new antibacterial agents

GpsB Coordinates Cell Division and Cell Surface Decoration by Wall Teichoic Acids in Staphylococcus aureus.

ABSTRACTBacterial cell division is a complex and highly regulated process requiring the coordination of many different proteins. Despite substantial work in model organisms, our understanding of the systems regulating cell division in noncanonical organisms, including critical human pathogens, is far from complete. One such organism is Staphylococcus aureus, a spherical bacterium that lacks known cell division regulatory proteins. Recent studies on GpsB, a protein conserved within the Firmicutes phylum, have provided insight into cell division regulation in S. aureus and other related organisms. It has been revealed that GpsB coordinates cell division and cell wall synthesis in multiple species. In S. aureus, we have previously shown that GpsB directly regulates FtsZ polymerization. In this study, using Bacillus subtilis as a tool, we isolated spontaneous suppressors that abrogate the lethality of S. aureus GpsB overproduction in B. subtilis. Through characterization, we identified several residues important for the function of GpsB. Furthermore, we discovered an additional role for GpsB in wall teichoic acid (WTA) biosynthesis in S. aureus. Specifically, we show that GpsB directly interacts with the WTA export protein TarG. We also identified a region in GpsB that is crucial for this interaction. Analysis of TarG localization in S. aureus suggests that WTA machinery is part of the divisome complex. Taken together, this research illustrates how GpsB performs an essential function in S. aureus by directly linking the tightly regulated cell cycle processes of cell division and WTA-mediated cell surface decoration.IMPORTANCE Cytokinesis in bacteria involves an intricate orchestration of several key cell division proteins and other factors involved in building a robust cell envelope. Presence of teichoic acids is a signature characteristic of the Gram-positive cell wall. By characterizing the role of Staphylococcus aureus GpsB, an essential cell division protein in this organism, we have uncovered an additional role for GpsB in wall teichoic acid (WTA) biosynthesis. We show that GpsB directly interacts with TarG of the WTA export complex. We also show that this function of GpsB may be conserved in other GpsB homologs as GpsB and the WTA exporter complex follow similar localization patterns. It has been suggested that WTA acts as a molecular signal to control the activity of autolytic enzymes, especially during the separation of conjoined daughter cells. Thus, our results reveal that GpsB, in addition to playing a role in cell division, may also help coordinate WTA biogenesis.

MaNsdD regulates conidiation negatively by inhibiting the AbaA expression required for normal conidiation in Metarhizium acridum.

Conidiation necessary for filamentous fungal survival and dispersal proceeds in two fashions, namely, normal conidiation through conidiophores differentiated from hyphae and microcycle conidiation through conidial budding. Normal conidiation has been well studied, whereas mechanisms underlying microcycle conidiation are still largely unknown. Here, we report that a gene (MaNsdD) homologous to NsdD in Aspergillus nidulans serves as a suppressor of normal conidiation but a positive regulator of hyphal development in Metarhizium acridum. Disruption of MaNsdD (ΔMaNsdD) resulted in microcycle conidiation and significantly descended in conidial resistance to heat while improved to UV irradiation. Transcriptomic analysis revealed that many genes involved in conidiation, cell division and cell wall formation were differentially expressed in ΔMaNsdD, and likely associated with the conidiation process. We found that a gene (MaAbaA) homologous to the core asexual development regulator AbaA in A. nidulans was negatively controlled by MaNsdD. Disruption of MaAbaA led to the abolition of the conidiation process of M. acridum. These findings unravel a novel regulatory mechanism of microcycle conidiation and add knowledge to the asexual conidiation pathway of filamentous fungi.

SmdA is a Novel Cell Morphology Determinant in Staphylococcus aureus.

ABSTRACTCell division and cell wall synthesis in staphylococci need to be precisely coordinated and controlled to allow the cell to multiply while maintaining its nearly spherical shape. The mechanisms ensuring correct placement of the division plane and synthesis of new cell wall have been studied intensively. However, hitherto unknown factors and proteins are likely to play key roles in this complex interplay. Here, we identified and investigated a protein with a major influence on cell morphology in Staphylococcus aureus. The protein, named SmdA (for staphylococcal morphology determinant A), is a membrane protein with septum-enriched localization. By CRISPRi knockdown and overexpression combined with different microscopy techniques, we demonstrated that proper levels of SmdA were necessary for cell division, including septum formation and cell splitting. We also identified conserved residues in SmdA that were critical for its functionality. Pulldown and bacterial two-hybrid interaction experiments showed that SmdA interacted with several known cell division and cell wall synthesis proteins, including penicillin-binding proteins (PBPs) and EzrA. Notably, SmdA also affected susceptibility to cell wall targeting antibiotics, particularly in methicillin-resistant S. aureus (MRSA). Together, our results showed that S. aureus was dependent on balanced amounts of membrane attached SmdA to carry out proper cell division.

Comparative transcriptome study of the elongating internode in elephant grass (Cenchrus purpureus) seedlings in response to exogenous gibberellin applications

Bioenergy grass provides an important biomass resource for biofuel production worldwide. The internode elongation of grass stems is central to biomass production for biofuels; however, this process is poorly understood in elephant grass because it is a complex trait regulated by many genes. In this study, we adopted phenotypic, histological, transcriptomic, and phytohormone methods to investigate the regulatory mechanisms of internode elongation mediated by gibberellin (GA) in a dwarf cultivar and a standard cultivar. Phenotypic analysis revealed that exogenous GA3 increased plant height by inducing both internode length and internode number in two cultivars with contrasting internode lengths. Histological analysis revealed that the GA3 application increased the internode elongation through inducing both cell division and cell elongation. Phytohormone analysis indicated that exogenous GA3 treatment significantly increased endogenous indole-3-acetic acid (IAA), and zeatin (ZR) contents but decreased abscisic acid (ABA) contents, while the expression levels of genes related to hormone metabolism and signaling were substantially changed. Consistent with the expression pattern, a significant increase in lignin and cellulose content were also observed after GA3 treatment. Genes and transcription factors related to hormone metabolism and signaling, cell division, cell wall biosynthesis, and plant growth were identified as hub genes in the core coexpression network of the response to GA3 application. This study showed that active cell division, cell elongation, and cell wall biosynthesis contribute to internode elongation following exogenous GA3 applications and identified hub genes for these complex regulatory networks. These data elucidate mechanisms governing internode elongation in elephant grass and help breeders to develop elite cultivars with high biomass.

Step‐by‐step protocol for the isolation and transient transformation of hornwort protoplasts

PremiseA detailed protocol for the protoplast transformation of hornwort tissue is not yet available, limiting molecular biological investigations of these plants and comparative analyses with other bryophytes, which display a gametophyte‐dominant life cycle and are critical to understanding the evolution of key land plant traits.Methods and ResultsWe describe a detailed protocol to isolate and transiently transform protoplasts of the model hornwort Anthoceros agrestis. The digestion of liquid cultures with Driselase yields a high number of viable protoplasts suitable for polyethylene glycol (PEG)‐mediated transformation. We also report early signs of protoplast regeneration, such as chloroplast division and cell wall reconstitution.ConclusionsThis protocol represents a straightforward method for isolating and transforming A. agrestis protoplasts that is less laborious than previously described approaches. In combination with the recently developed stable genome transformation technique, this work further expands the prospects of functional studies in this model hornwort.