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Trends in Plant Science Apr 2024The concept of the meristem was introduced in 1858 to characterize multicellular, formative, and proliferative tissues that give rise to the entire plant body, based on... (Review)
Review
The concept of the meristem was introduced in 1858 to characterize multicellular, formative, and proliferative tissues that give rise to the entire plant body, based on observations of vascular plants. Although its original definition did not encompass bryophytes, this concept has been used and continuously refined over the past 165 years to describe the diverse apices of all land plants. Here, we re-examine this matter in light of recent evo-devo research and show that, despite displaying high anatomical diversity, land plant meristems are unified by shared genetic control. We also propose a modular view of meristem function and highlight multiple evolutionary mechanisms that are likely to have contributed to the assembly and diversification of the varied meristems during the course of plant evolution.
Topics: Meristem; Plant Proteins; Plants
PubMed: 38040554
DOI: 10.1016/j.tplants.2023.11.003 -
Brazilian Dental Journal 2023This case series included a tomographic, microbiological, and histopathological description of 15 secondary apical periodontitis (SAP) lesions obtained by apical...
This case series included a tomographic, microbiological, and histopathological description of 15 secondary apical periodontitis (SAP) lesions obtained by apical microsurgery performed in 10 patients to better understand the etiology and pathogenesis of SAP. Preoperative tomographic analyses were performed through Cone beam computerized tomography - Periapical index (CBCT-PAI), and apical microsurgeries were then carried out. The removed apices were used for microbial culturing and for molecular identification using PCR for the detection of 5 strict anaerobic bacteria (P. gingivalis, P. intermedia, P. nigrescens, T. forsythia, and T.denticola) and 3 viruses Herpes simplex viruses (HSV), Cytomegalovirus (CMG) and Epstein-Barr Virus (EBV) by nested PCR. The removed apical lesions were histologically described. Univariate statistical analyses were performed by using STATA MP/16 (StataCorp LLC, College Station, TX, United States). CBCT-PAI analyses revealed PAI 4 and PAI 5 score lesions that involved cortical plate destruction. Eight SAPs were positive by culture, while nine SAP lesions were positive by PCR. Fusobacterium species were the most frequently cultured organisms in 7 SAP lesions, followed by D. pneumosintes in 3. In contrast, by single PCR, T. forsythia and P. nigrescens were detected in 5 lesions, T. denticola in 4 lesions, and P. gingivalis in 2 lesions. Twelve periapical lesions were granulomas, and the remaining three SAP lesions were radicular cysts. In conclusion, this case series study revealed that secondary apical lesions presented tomographic involvement of PAI 3 to 5, and that most SAP lesions were apical granulomas containing anaerobic and facultative microorganisms.
Topics: Humans; Epstein-Barr Virus Infections; Herpesvirus 4, Human; Periapical Periodontitis; Cytomegalovirus; Polymerase Chain Reaction
PubMed: 36888839
DOI: 10.1590/0103-6440202304590 -
IScience Jul 2023Although the formin-nucleated actomyosin cortex has been shown to drive the changes in cell shape that accompany animal cell division in both symmetric and asymmetric...
Although the formin-nucleated actomyosin cortex has been shown to drive the changes in cell shape that accompany animal cell division in both symmetric and asymmetric cell divisions, the mitotic role of cortical Arp2/3-nucleated actin networks remain unclear. Here using asymmetrically dividing neural stem cells as a model system, we identify a pool of membrane protrusions that form at the apical cortex of neuroblasts as they enter mitosis. Strikingly, these apically localized protrusions are enriched in SCAR, and depend on SCAR and Arp2/3 complexes for their formation. Because compromising SCAR or the Arp2/3 complex delays the apical clearance of Myosin II at the onset of anaphase and induces cortical instability at cytokinesis, these data point to a role for an apical branched actin filament network in fine-tuning the actomyosin cortex to enable the precise control of cell shape changes during an asymmetric cell division.
PubMed: 37434695
DOI: 10.1016/j.isci.2023.107129 -
The Journal of Cell Biology Jul 2022Border cells are an in vivo model for collective cell migration. Here, we identify the gene cactin as essential for border cell cluster organization, delamination, and...
Border cells are an in vivo model for collective cell migration. Here, we identify the gene cactin as essential for border cell cluster organization, delamination, and migration. In Cactin-depleted cells, the apical proteins aPKC and Crumbs (Crb) become abnormally concentrated, and overall cluster polarity is lost. Apically tethering excess aPKC is sufficient to cause delamination defects, and relocalizing apical aPKC partially rescues delamination. Cactin is conserved from yeast to humans and has been implicated in diverse processes. In border cells, Cactin's evolutionarily conserved spliceosome function is required. Whole transcriptome analysis revealed alterations in isoform expression in Cactin-depleted cells. Mutations in two affected genes, Sec23 and Sec24CD, which traffic Crb to the apical cell surface, partially rescue border cell cluster organization and migration. Overexpression of Rab5 or Rab11, which promote Crb and aPKC recycling, similarly rescues. Thus, a general splicing factor is specifically required for coordination of cluster polarity and migration, and migrating border cells are particularly sensitive to splicing and cell polarity disruptions.
Topics: Animals; Carrier Proteins; Cell Movement; Cell Polarity; Drosophila Proteins; Drosophila melanogaster; Epithelial Cells; Membrane Proteins; Spliceosomes; Transcriptome
PubMed: 35612426
DOI: 10.1083/jcb.202202146 -
Nature Communications Dec 2022Morphogenesis of many protozoans depends on a polarized establishment of cortical cytoskeleton containing the subpellicular microtubules (SPMTs), which are apically...
Morphogenesis of many protozoans depends on a polarized establishment of cortical cytoskeleton containing the subpellicular microtubules (SPMTs), which are apically nucleated and anchored by the apical polar ring (APR). In malaria parasite Plasmodium, APR emerges in the host-invading stages, including the ookinete for mosquito infection. So far, the fine structure and molecular components of APR as well as the underlying mechanism of APR-mediated apical positioning of SPMTs are largely unknown. Here, we resolve an unprecedented APR structure composed of a top ring plus approximate 60 radiating spines. We report an APR-localizing and SPMT-binding protein APR2. APR2 disruption impairs ookinete morphogenesis and gliding motility, leading to Plasmodium transmission failure in mosquitoes. The APR2-deficient ookinetes display defective apical anchorage of APR and SPMT due to the impaired integrity of APR. Using protein proximity labeling, we obtain a Plasmodium ookinete APR proteome and validate ten undescribed APR proteins. Among them, APRp2 and APRp4 directly interact with APR2 and also mediate the apical anchorage of SPMTs. This study sheds light on the molecular basis of APR in the organization of Plasmodium ookinete SPMTs.
Topics: Animals; Culicidae; Cytoskeleton; Malaria; Microtubules
PubMed: 36463257
DOI: 10.1038/s41467-022-35270-w -
Journal of Veterinary Dentistry Dec 2023Data on the age of apical closure in felines is limited. Moreover, differences in age of apical closure between male and female cats have not been studied. The aim of...
Data on the age of apical closure in felines is limited. Moreover, differences in age of apical closure between male and female cats have not been studied. The aim of this study was to determine the timing of apical closure in cats and determine if sex or position in the dental arch affected closure. In this retrospective descriptive study, intraoral radiographs were obtained at monthly or multiple-monthly intervals for 18 cats. Nine were intact females and 9 were neutered males, ranging from 6 to 9.4 months of age at the start of the study which ranged over an 8-month period. Radiographs were evaluated to establish age of apical closure for all canine teeth as well as the mandibular premolar and molar teeth. Mandibular canine tooth apices closed between 10 and 12 months of age and maxillary canine tooth apices closed between 12 and 14 months of age. The mesial and distal root apices of both the mandibular third and fourth premolar teeth closed between 8 and 9 months. The mandibular first molar tooth mesial and distal root apices closed between 8 and 8.5 months. Root apices of canine teeth closed earlier in female cats than in male cats with mandibular canine tooth root apices closing significantly earlier than maxillary canine tooth roots in both sexes. These findings suggest that there are notable differences in age of apical closure between male and female cats and discernible trends in timing of apical closure among teeth in the dental arcade.
PubMed: 38115724
DOI: 10.1177/08987564231220682 -
Frontiers in Physiology 2022Inflammation is central to the mechanisms of parturition, but the lack of understanding of how it is controlled in normal parturition hampers our ability to understand...
Inflammation is central to the mechanisms of parturition, but the lack of understanding of how it is controlled in normal parturition hampers our ability to understand how it may diverge resulting in preterm birth. Cell-free fetal DNA is found in the amniotic fluid, and it is thought to be able to activate inflammation as a danger-associated molecular pattern. Although its levels increases with gestational age, its effect has not been studied on the human fetal membranes. Thus, the aim of this study was to determine if the fetal DNA can trigger inflammation in the human fetal membranes and, thus, potentially contribute to the inflammatory load. Isolated human amniotic epithelial cells and fetal membrane explants were treated apically with fetal DNA causing the translocation of NF-KB into the nucleus of cells and throughout the cells of the explant layers with time. Fetal membrane explants were treated apically with either small or larger fragments of fetal DNA. IL-6, TNFα, and GM-CSF secretion was measured by ELISA, and pro-MMP2 and pro-MMP9 activity was measured by zymography from apical and basal media. Increased apical IL-6 secretion and basal pro-MMP2 activity was seen with small fragments of fetal DNA. When the data were disaggregated based on fetal sex, males had significant increases in IL-6 secretion and basal increased activity in pro-MMP2 and 9, whereas females had significantly increased basal secretion of TNFα. This was caused by the smaller fragments of fetal DNA, whereas the larger fragments did not cause any significant increases. Male fetal DNA had significantly lower percentages of methylation than females. Thus, when the cytokine and pro-MMP activity data were correlated with methylation percentage, IL-6 secretion significantly correlated negatively, whereas GM-CSF secretion positively correlated. These data support the role of fetal DNA as an inflammatory stimulus in the FM, as measured by increased NF-κB translocation, cytokine secretion, and increased pro-MMP activity. However, the data also suggested that the responses are different from FM tissues of male and female fetuses, and both the fragment size and methylation status of the fetal DNA can influence the magnitude and type of molecule secreted.
PubMed: 35812324
DOI: 10.3389/fphys.2022.901726 -
Frontiers in Cell and Developmental... 2022The folding of two-dimensional epithelial sheets into specific three-dimensional structures is a fundamental tissue construction mechanism in animal development. A...
The folding of two-dimensional epithelial sheets into specific three-dimensional structures is a fundamental tissue construction mechanism in animal development. A common mechanism that mediates epithelial folding is apical constriction, the active shrinking of cell apices driven by actomyosin contractions. It remains unclear whether cells outside of the constriction domain also contribute to folding. During mesoderm invagination, ventrally localized mesoderm epithelium undergoes apical constriction and subsequently folds into a furrow. While the critical role of apical constriction in ventral furrow formation has been well demonstrated, it remains unclear whether, and if so, how the laterally localized ectodermal tissue adjacent to the mesoderm contributes to furrow invagination. In this study, we combine experimental and computational approaches to test the potential function of the ectoderm in mesoderm invagination. Through laser-mediated, targeted disruption of cell formation prior to gastrulation, we found that the presence of intact lateral ectoderm is important for the effective transition between apical constriction and furrow invagination in the mesoderm. In addition, using a laser-ablation approach widely used for probing tissue tension, we found that the lateral ectodermal tissues exhibit signatures of tissue compression when ablation was performed shortly before the onset of mesoderm invagination. These observations led to the hypothesis that in-plane compression from the surrounding ectoderm facilitates mesoderm invagination by triggering buckling of the mesoderm epithelium. In support of this notion, we show that the dynamics of tissue flow during mesoderm invagination displays characteristic of elastic buckling, and this tissue dynamics can be recapitulated by combining local apical constriction and global compression in a simulated elastic monolayer. We propose that mesoderm invagination is achieved through epithelial buckling jointly mediated by apical constriction in the mesoderm and compression from the neighboring ectoderm.
PubMed: 35547820
DOI: 10.3389/fcell.2022.867438 -
BMC Oral Health Nov 2021The present study aims to evaluate the effectiveness of mineral trioxide aggregate (MTA) application in treating dens evaginatus affected teeth with apical lesions and...
BACKGROUND
The present study aims to evaluate the effectiveness of mineral trioxide aggregate (MTA) application in treating dens evaginatus affected teeth with apical lesions and open apices using haemostatic collagen membrane to prevent the apical extrusion of MTA.
METHODS
Twelve patients with 14 dens evaginatus affected teeth with apical lesions and open apices were treated with MTA apical plug and haemostatic collagen membrane. Clinical symptoms of subjective pain, pain of palpation, percussion, sinus tract, and the apical lesions' radiographic parameter were recorded at every 3-month interval up to 9 months after treatment. Paired t-test or Wilcoxon signed-rank test was used for statistical analysis with P < 0.05 as the threshold for considering results to be statistically significant.
RESULTS
No patient experienced clinical symptoms 3 months after endodontic treatment. In addition, there was a significant difference in the dimensions of the apical lesions' before compared to 3 months after endodontic treatment.
CONCLUSIONS
The combination of MTA apical plug and haemostatic collagen membrane effectively treated dens evaginatus affected teeth with apical lesions, and open apices.
Topics: Aluminum Compounds; Calcium Compounds; Drug Combinations; Humans; Oxides; Root Canal Filling Materials; Silicates; Tooth Apex
PubMed: 34749689
DOI: 10.1186/s12903-021-01920-6 -
Brazilian Oral Research 2020The present study investigated the intracanal decontamination and apical extrusion of bacteria and debris from root canals instrumented with rotary and reciprocating... (Randomized Controlled Trial)
Randomized Controlled Trial
The present study investigated the intracanal decontamination and apical extrusion of bacteria and debris from root canals instrumented with rotary and reciprocating systems (ProDesign Logic or ProDesign R), with different file diameters and using conventional syringe irrigation (CSI) or passive ultrasonic irrigation (PUI). Eighty extracted mandibular premolars were contaminated with Enterococcus faecalis and randomly assigned to eight experimental groups according to the root canal instrumentation and irrigation technique employed (n = 10): G1: Prodesign Logic 25.06; G2: Prodesign R 25.06; G3 and G4 were instrumented with the same single-file systems, respectively, using 35.05 diameters and CSI. G5, G6, G7, and G8 were instrumented like the previous groups, but with PUI. Apically extruded debris during instrumentation was collected into pre-weighed microtubes. The weight of the empty microtube was subtracted from the final weight to establish the amount of extruded debris. Bacteria from root canals and extruded debris were collected for a microbiological evaluation of colony forming units (CFU/mL). For statistical analyses, the Mann-Whitney and Kruskal-Wallis followed by the Dunn's tests were used (α = 0.05). All instruments caused extrusion of debris. For irrigation techniques, PUI promoted greater debris and bacterial extrusion (p < 0.05). The CFU/mL count indicated that the instrumentation of the experimental groups were equally effective in the decontamination of the root canal (p > 0.05). The systems tested (regarding file diameter and kinematics) were associated with similar amounts of apically extruded debris and root canal decontamination. PUI was associated with greater debris and bacterial extrusion.
Topics: Biomechanical Phenomena; Decontamination; Dental Pulp Cavity; Humans; Root Canal Preparation; Tooth Apex; Ultrasonics
PubMed: 33206776
DOI: 10.1590/1807-3107bor-2021.vol35.0003