Periderm Cells Research Articles

Unveiling the ototoxic effects of paraquat on zebrafish larva

Paraquat is a widely utilized herbicide in agricultural fields posing a significant impact on human health and the environment due to its potent oxidant properties. Rampant paraquat usage leads to serious health hazards to farmers and the ecosystem, particularly the water bodies. Paraquat exposure can damage dopaminergic neurons causing Parkinson's disease in humans and other animal models. Extensive research has been done regarding the mode of action, pathophysiology and molecular mechanisms of paraquat-induced Parkinson's disease. Meanwhile, the ototoxic effect of paraquat remains poorly understood. Potential ototoxins can cause sensorineural hearing loss, one of the most common sensory disabilities in humans. In this study, we investigated the harmful effects of paraquat on neuromast hair cells in zebrafish larvae, a powerful model organism for auditory research. We treated sub-lethal concentrations (125 μM to 1000 μM) of paraquat to 3 and 4 dpf zebrafish larvae to investigate its ototoxic effects via rheotaxis behavioral assay, neuromast staining and scanning electron microscopy. The behavioral assay findings showed a drastic decline in the rheotaxis behavior in all the concentrations of paraquat-treated larvae. Furthermore, DASPEI neuromast vital staining displayed a dose-dependent reduction in the neuromast hair cells as we increased the paraquat concentration. The scanning electron microscope data revealed the significant shortening of kinociliary length, a decrease in stereociliary density and changes in semilunar peridermal cell morphology signifying the damaging effects of paraquat at the cellular level. Collectively, the behavioral, anatomical and morphological studies highlight the potential ototoxic effects of paraquat on zebrafish neuromast hair cells, further signifying its potential role in causing hearing loss in humans.

Plant periderm as a continuum in structural organisation: a tracheophyte-wide survey and hypotheses on evolution.

Periderm is a well-known structural feature with vital roles in protection of inner plant tissues and wound healing. Despite its importance to plant survival, knowledge of periderm occurrences outside the seed plants is limited and the evolutionary origins of periderm remain poorly explored. Here, we review the current knowledge of the taxonomic distribution of periderm in its two main forms - canonical periderm (periderm formed as a typical ontogenetic stage) and wound periderm (periderm produced as a self-repair mechanism) - with a focus on major plant lineages, living and extinct. We supplement the published occurrences with data based on our own observations and experiments. This updated body of data reveals that the distribution of wound periderm is more widespread taxonomically than previously recognized and some living and extinct groups are capable of producing wound periderm, despite canonical periderm being absent from their normal developmental program. A critical review of canonical and wound periderms in extant and fossil lineages indicates that not all periderms are created equal. Their organisation is widely variable and the differences can be characterised in terms of variations in three structural features: (i) the consistency in orientation of periclinal walls within individual files of periderm cells; (ii) the lateral coordination of periclinal walls between adjacent cell files; and (iii) whether a cambial layer and conspicuous layering of inward and outward derivatives can be distinguished. Using a new system of scoring periderm structure based on these criteria, we characterise the level of organisation of canonical and wound periderms in different lineages. Looking at periderms through the lens provided by their level of organisation reveals that the traditional image of periderm as a single generalised feature, is best viewed as a continuum of structural configurations that are all predicated by the same basic process (periclinal divisions), but can fall anywhere between very loosely organized (diffuse periclinal growth) to very tightly coordinated (organized periclinal growth). Overall, wound periderms in both seed plants and seed-free plants have lower degrees of organisation than canonical periderms, which may be due to their initiation in response to inherently disruptive traumatic events. Wound and canonical periderms of seed plants have higher degrees of organisation than those of seed-free plants, possibly due to co-option of the programs responsible for organizing their vascular cambial growth. Given the importance of wound periderm to plant survival, its widespread taxonomic distribution, and its early occurrence in the fossil record, we hypothesise that wound periderm may have had a single origin in euphyllophytes and canonical periderm may have originated separately in different lineages by co-option of the basic regulatory toolkit of wound periderm formation. In one evolutionary scenario, wound periderm regulators activated initially by tissue tearing due to tensional stresses elicited by woody growth underwent heterochronic change that switched their activation trigger from tissue tearing to the tensional stresses that precede it, with corresponding changes in the signalling that triggered the regulatory cascade of periderm development from tearing-induced signals to signalling induced by tension in cells.

Evaluation of Pharmacognostical and Phytochemical Studies for the Development of Quality Control Parameters for Stem Bark of Ximenia americana Linn. (Olacaceae)

Abstract Background: Plants are extremely useful to humankind as medicine, and hence the properties of medicinal plants have to be scientifically evaluated. Aim: The aim of this study is to establish pharmacognostical and phytochemical parameters for stem bark of Ximenia americana Linn. (Olacaceae). Materials and Methods: Macroscopical, microscopical evaluation, powder microscopical studies, quantitative microscopy, physicochemical evaluation, fluorescence analysis, analysis of inorganic elements, and determination of heavy metal contamination were performed as per the World Health Organization guidelines and standard methods. To evaluate various phytoconstituents, phytochemical investigations such as preliminary phytochemical screening, high-performance thin-layer chromatography, and high-performance liquid chromatography were performed. Results: Microscopical studies showed the presence of thick cortex, periderm cells, phloem parenchyma, phloem fibers, sieve elements, prismatic and granular calcium oxalate crystals, and resinous cells. The length and width of fibers, stone cells, and diameter of starch grains were measured. Physicochemical evaluation like ash values has shown total ash – 8.01% ± 0.02% w/w, acid-insoluble ash – 1.53% ± 0.02% w/w, water-soluble ash – 1.54% ± 0.01% w/w, sulfated ash – 12.02% ± 0.07% w/w, water-soluble hot extraction – 26.48 ± 0.02% w/w, cold maceration – 11.76% ± 0.04% w/w, alcohol soluble – 15.69% ± 0.03%w/w, ether soluble – 2.06% ± 0.03% w/w, and loss on drying – 4.88% ± 0.01% w/w. Conclusion: Pharmacognostical study on the stem bark of Ximenia americana may be reported as first. The results of pharmacognostical and phytochemical studies will be helpful for authentication and provide quality control parameters for the stem bark of this plant.

Disruption of fos causes craniofacial anomalies in developing zebrafish.

Craniofacial development is a complex and tightly regulated process and disruptions can lead to structural birth defects, the most common being nonsyndromic cleft lip and palate (NSCLP). Previously, we identified FOS as a candidate regulator of NSCLP through family-based association studies, yet its specific contributions to oral and palatal formation are poorly understood. This study investigated the role of fos during zebrafish craniofacial development through genetic disruption and knockdown approaches. Fos was expressed in the periderm, olfactory epithelium and other cell populations in the head. Genetic perturbation of fos produced an abnormal craniofacial phenotype with a hypoplastic oral cavity that showed significant changes in midface dimensions by quantitative facial morphometric analysis. Loss and knockdown of fos caused increased cell apoptosis in the head, followed by a significant reduction in cranial neural crest cells (CNCCs) populating the upper and lower jaws. These changes resulted in abnormalities of cartilage, bone and pharyngeal teeth formation. Periderm cells surrounding the oral cavity showed altered morphology and a subset of cells in the upper and lower lip showed disrupted Wnt/β-catenin activation, consistent with modified inductive interactions between mesenchymal and epithelial cells. Taken together, these findings demonstrate that perturbation of fos has detrimental effects on oral epithelial and CNCC-derived tissues suggesting that it plays a critical role in zebrafish craniofacial development and a potential role in NSCLP.

The Opto-inflammasome in zebrafish as a tool to study cell and tissue responses to speck formation and cell death

The inflammasome is a conserved structure for the intracellular detection of danger or pathogen signals. As a large intracellular multiprotein signaling platform, it activates downstream effectors that initiate a rapid necrotic programmed cell death (PCD) termed pyroptosis and activation and secretion of pro-inflammatory cytokines to warn and activate surrounding cells. However, inflammasome activation is difficult to control experimentally on a single-cell level using canonical triggers. We constructed Opto-ASC, a light-responsive form of the inflammasome adaptor protein ASC (Apoptosis-Associated Speck-Like Protein Containing a CARD) which allows tight control of inflammasome formation in vivo. We introduced a cassette of this construct under the control of a heat shock element into zebrafish in which we can now induce ASC inflammasome (speck) formation in individual cells of the skin. We find that cell death resulting from ASC speck formation is morphologically distinct from apoptosis in periderm cells but not in basal cells. ASC-induced PCD can lead to apical or basal extrusion from the periderm. The apical extrusion in periderm cells depends on Caspb and triggers a strong Ca2+ signaling response in nearby cells.

Histo-Anatomical Characteristics of Some Endemic Species of Linum (Linaceae)

In this study, endemic two species belonging to the genus Linum and distributed in Türkiye are investigated. The outermost layer of the Linum flavum subsp. scabrinerve (P.H. Davis) P.H. Davis root, according to its cross-section, is covered with epidermis cells. In the stem cross-section, the vascular bundles are in the form of a continuous ring and sclerenchyma cells are determined on it. The lower surface and the upper surfaces of leaf have 88 and 51 stomata respectively. It contains few glandular hairs. The root of Linum hirsutum subsp. pseudoanatolicum P. H. Davis have secondary growth. Periderm cells on the outside are oval or isodiametric in shaped. In the stem cross-section, vascular bundles are in the form of a continuous ring. The cortex layer, consists of oval or rectangular shaped 9-10 rows of parenchymatous cells. The lower surface and the upper surfaces of leaf have 48 and 46 stomata respectively. No glandular or non-glandular hairs are found on the epidermis. As a result, anatomical comparison of two different taxa belonging to the same genus was made with this study. According to the findings, the root structures of the species, the presence of sclerenchyma on the stem, the size of the stomata of the leaf, mesophyll types and the presence of glandular hairs are different from each other.

Periderm Fate during Palatogenesis: TGF-β and Periderm Dedifferentiation

Failure of palatogenesis results in cleft palate, one of the most common congenital disabilities in humans. During the final phases of palatogenesis, the protective function of the peridermal cell layer must be eliminated for the medial edge epithelia to adhere properly, which is a prerequisite for the successful fusion of the secondary palate. However, a deeper understanding of the role and fate of the periderm in palatal adherence and fusion has been hampered due to a lack of appropriate periderm-specific genetic tools to examine this cell type in vivo. Here we used the cytokeratin-6A (Krt-6a) locus to develop both constitutive (Krt6ai-Cre) and inducible (Krt6ai-Cre ERT2 ) periderm-specific Cre driver mouse lines. These novel lines allowed us to achieve both the spatial and temporal control needed to dissect the periderm fate on a cellular resolution during palatogenesis. Our studies suggest that, already before the opposing palatal shelves contact each other, at least some palatal periderm cells start to gradually lose their squamous periderm-like phenotype and dedifferentiate into cuboidal cells, reminiscent of the basal epithelial cells seen in the palatal midline seam. Moreover, we show that transforming growth factor–β (TGF-β) signaling plays a critical periderm-specific role in palatogenesis. Thirty-three percent of embryos lacking a gene encoding the TGF-β type I receptor (Tgfbr1) in the periderm display a complete cleft of the secondary palate. Our subsequent experiments demonstrated that Tgfbr1-deficient periderm fails to undergo appropriate dedifferentiation. These studies define the periderm cell fate during palatogenesis and reveal a novel, critical role for TGF-β signaling in periderm dedifferentiation, which is a prerequisite for appropriate palatal epithelial adhesion and fusion.

Sensory axons induce epithelial lipid microdomain remodeling and determine the distribution of junctions in the epidermis.

Epithelial cell properties are determined by the polarized distribution of membrane lipids, the cytoskeleton, and adhesive junctions. Epithelia are often profusely innervated, but little work has addressed how neurites affect epithelial organization. We previously found that basal keratinocytes in the zebrafish epidermis enclose axons in ensheathment channels sealed by autotypic junctions. Here we characterized how axons remodel cell membranes, the cytoskeleton, and junctions in basal keratinocytes. At the apical surface of basal keratinocytes, axons organized lipid microdomains quantitatively enriched in reporters for PI(4,5)P2 and liquid-ordered (Lo) membranes. Lipid microdomains supported the formation of cadherin-enriched, F-actin protrusions, which wrapped around axons, likely initiating ensheathment. In the absence of axons, cadherin-enriched microdomains formed on basal cells but did not organize into contiguous domains. Instead, these isolated domains formed heterotypic junctions with periderm cells, a distinct epithelial cell type. Thus, axon endings dramatically remodel polarized epithelial components and regulate epidermal adhesion.

Establishment of quality indicators of promising plant raw materials - underground organs of Rumex confertus willd

The aim is to study the morphological and anatomical structure of the underground organs of R. confertus and to establish the type of medicinal plant raw materials, to determine a number of its indicators of quality and quantitative content of some groups of biologically active substances using modern methods of analysis.
 Materials and methods. It was used air-dry and freshly collected raw materials and a microscope Delta optic BioLight 300 (Poland) to study the macro- and microscopic characteristics of the plant raw materials. Determination of amount of hydroxycinnamic acids and total polyphenols was determined spectrophotometrically according to monograph «Nettle leaf» and the method 2.8.14 of the State Pharmacopoeia of Ukraine 2.0 (on a spectrophotometer Optizen POP (Korea)). The study of the component composition of hydroxycinnamic acids was performed by HPLC.
 Results. As a result of research of plant raw materials it was established that the underground organs of Rumex confertus are the roots of annual plants and the rhizomes and roots of two or three annual plants. Diagnostic features: morphological (for the root and rhizome - the nature of the surface and fracture) and anatomical (for the rhizome - aerenchyma in the cortex, the presence and location of scleroids and sclerenchyma in the plant raw materials of two or three annual plants, the presence in the cells of the cortex and pith parenchyma simple starch grains, druses and cells with yellow content in freshly harvested plant raw materials; for the root - the colour of peridermal cells, the degree of development of pith rays, the remainder of the primary xylem; a distinctive feature of the annual root from two or three annuals is the absence of scleroids). It was determined the borderline boundaries of indicators in the series of plant raw materials: loss on drying (not more than 13. 5 %), total ash (not more than 11 %), extractable matter (not less than 33 %) and the quantitative content of amount of hydroxycinnamic acids (not less than 1.3 %) and total polyphenols (not less than 3.5 %). It was identified chlorogenic and neochlorogenic acids.
 Conclusions. It was determined the type of underground organs of Rumex confertus: annuals had only roots (tap root systems), from the second to the third year of life the plants have both rhizomes and tap root system. It was established their morphological and anatomical diagnostic features and determined numerical indicators and the quantitative content of the amount of hydroxycinnamic acids and total polyphenols with using modern methods of analysis and chlorogenic and neochlorogenic acids were identified. The obtained data will be used in further research, including the development of the draft monograph of the State Pharmacopoeia of Ukraine 2.0 or the draft methods of quality control of medicinal plant raw materials Rumex confertus and the creation of herbal medicines

A Collection of Melon (Cucumis melo) Fruit Cultivars with Varied Skin Appearances Provide Insight to the Contribution of Suberin in Periderm Formation and Reticulation.

At times of fruit skin failure, reticulation made of a wound-periderm is formed below the cracked skin in order to seal the damaged tissue. Preceding investigations shed light on the mechanisms underlying the formation of fruit skin reticulation, demonstrating that the walls of periderm cells are heavily suberized and lignified. However, the relative contribution of the suberin pathway to these processes, as well as the association between suberin contents in the periderm tissue and reticulation degree, are largely unknown. To strengthen our understanding on these important physiological and agricultural aspects, we comparatively profiled skin tissues of a collection of smooth- and reticulated-skin melon (Cucumis melo) cultivars for suberin monomer composition via gas chromatography-mass spectrometry (GC-MS). This metabolite profiling approach accompanied by statistical tools highlighted the fundamental chemical differences between the skin of smooth fruit made of a typical cuticle, to the skin of reticulated fruit made of large amounts of archetypal suberin building blocks including hydroxycinnamic acids, very long chain fatty acids, fatty alcohols, α-hydroxyacids, ω-hydroxyacids, and α,ω-diacids. Next, using image analysis we generated ‘reticulation maps’ and calculated the relative densities of reticulation. We then performed correlation assays in order to monitor suberin monomers that specifically correlate well with reticulation degree. Nonetheless, total suberin contents and most suberin building blocks did not show high correlations with reticulation degree, further suggesting that additional factors are likely to influence and regulate these processes. Altogether, the data provided vital information regarding the relative contribution of the suberin pathway to periderm formation and skin reticulation.

Effects of Flooding and Endogenous Hormone on the Formation of Knee Roots in Taxodium ascendens.

Taxodium ascendens is a typical tree species with high flood tolerance, and it can generate knee roots in the wetlands. This study investigated the number and size of knee roots and the soil flooding conditions. Furthermore, we also measured physiology, biochemical responses, and the anatomical structure of knee roots and underground roots at different developmental stages. This study aimed to understand the adaptation mechanism of T. ascendens to flooding stress and the formation mechanism of the knee roots. The results showed that the formation of knee roots was significantly affected by the soil water table (P < 0.05). The middle water table was more conducive to the formation of knee roots. In the middle water table, the 1-aminocyclopropane-1-carboxylic acid (ACC) content and ACC synthase activity were significantly lower in the knee roots than in the underground roots. The knee roots at the young-aged stage showed the highest ACC oxidase activity among the development stages of the knee roots. The ethylene release rate was significantly higher in the knee roots than in the underground roots (P < 0.05). Indole-3-acetic acid (IAA) content first increased, then decreased with knee root development. The periderm cells at the apex of the knee roots were dead and had many intercellular spaces, which was beneficial for the growth of T. ascendens. In conclusion, the middle water table induced the ethylene and IAA production, which promoted the formation of knee roots, which improved roots ventilation and flooding tolerance of T. ascendens. The results obtained can provide information about mechanisms of knee roots formation and provide scientific evidence for the afforestation and management under wetland conditions.

Mouse models in palate development and orofacial cleft research: Understanding the crucial role and regulation of epithelial integrity in facial and palate morphogenesis.

Cleft lip and cleft palate are common birth defects resulting from genetic and/or environmental perturbations of facial development in utero. Facial morphogenesis commences during early embryogenesis, with cranial neural crest cells interacting with the surface ectoderm to form initially partly separate facial primordia consisting of the medial and lateral nasal prominences, and paired maxillary and mandibular processes. As these facial primordia grow around the primitive oral cavity and merge toward the ventral midline, the surface ectoderm undergoes a critical differentiation step to form an outer layer of flattened and tightly connected periderm cells with a non-stick apical surface that prevents epithelial adhesion. Formation of the upper lip and palate requires spatiotemporally regulated inter-epithelial adhesions and subsequent dissolution of the intervening epithelial seam between the maxillary and medial/lateral nasal processes and between the palatal shelves. Proper regulation of epithelial integrity plays a paramount role during human facial development, as mutations in genes encoding epithelial adhesion molecules and their regulators have been associated with syndromic and non-syndromic orofacial clefts. In this chapter, we summarize mouse genetic studies that have been instrumental in unraveling the mechanisms regulating epithelial integrity and periderm differentiation during facial and palate development. Since proper epithelial integrity also plays crucial roles in wound healing and cancer, understanding the mechanisms regulating epithelial integrity during facial development have direct implications for improvement in clinical care of craniofacial patients.

Notch signaling mediates olfactory multiciliated cell specification.

Epithelial multiciliated cells (MCCs) use motile cilia to direct external fluid flow, the disruption of which is associated with human diseases in a broad array of organs such as those in the respiratory, reproductive, and renal systems. While many of the signaling pathways that regulate MCC formation in these organ systems have been identified, similar characterization of MCC differentiation in the developing olfactory system has been lacking. Here, using live cell tracking, targeted cell ablation, and temporally-specific inhibition of the Notch signaling pathway, we identify the earliest time window of zebrafish olfactory MCC (OMCC) differentiation and demonstrate these cells' derivation from peridermal cells. We also describe regionally segregated Notch signaling across time points of rapid OMCC differentiation and show that Notch signaling downregulation yields an increase in OMCCs, suggesting that OMCC fate is normally repressed in a region-specific manner during olfactory development. Finally, we describe Notch signaling's regulation of the differentiation/ciliogenesis-associated genes foxj1a and foxj1b. Taken together, these findings provide new insights into the origins and developmental programming of OMCCs in vivo.

Toxicity of perfluorooctanoic acid on zebrafish early embryonic development determined by single-cell RNA sequencing

The perfluorooctanoic acid (PFOA) poses a high risk for aquatic organisms. Nevertheless, the current toxicity studies rarely report how PFOA affects different cell populations during the embryonic development of fish. Here, the zebrafish embryos at 2–30 hpf were exposed to 1–100 μg/L PFOA. The heartbeat and locomotor behavior were significantly decreased after ≥ 25 μg/L PFOA exposure. The single-cell RNA sequencing showed that PFOA exposure influenced nine cell populations, including heart cells, hatching gland cells, macrophages, lens cells, ionocytes, melanoblasts, optic cup cells, periderm cells, and differentiating neurons cells. Among them, heart cells were the most affected cell population. Functions of cardiac muscle contraction, actin cytoskeleton and oxygen binding were significantly changed in the heart cells, which were involved in the altered expressions of tnni2a.4, acta1a, atp1a1a.2, mylpfa, and so on. Besides, the changes of apoptotic process, innate immune response, and translation in lens cells, hatching gland cells, macrophages and ionocytes should also be of concern. Our study indicates that 2–30 hpf of embryonic development is the sensitivity window for the PFOA exposure. Identification of the target cell population provides clear information of the toxic endpoint of PFOA, which sheds new light on the risk assessment of PFOA on aquatic organisms.

A chemical window into the impact of RNAi silencing of the StNAC103 gene in potato tuber periderms: Soluble metabolites, suberized cell walls, and antibacterial defense

The growth and survival of terrestrial plants require control of their interactions with the environment, e.g., to defend against desiccation and microbial invasion. For major food crops, the protection conferred by the outer skins (periderm in potato) is essential to cultivation, storage, and marketing of the edible tubers and fruits. Potatoes are particularly vulnerable to bacterial infections due to their high content of water and susceptibility to mechanical wounding. Recently, both specific and conserved gene silencing (StNAC103-RNAi and StNAC103-RNAi-c, respectively) were found to increase the load of wax and aliphatic suberin depolymerization products in tuber periderm, implicating this NAC gene as a repressor of the wax and suberin biosynthetic pathways. However, an important gap in our understanding of StNAC103 silencing concerns the metabolites produced in periderm cells as antimicrobial defense agents and potential building blocks of the deposited suberin biopolymer. In the current work, we have expanded prior studies on StNAC103 silenced lines by conducting comprehensive parallel analyses to profile changes in chemical constituents and antibacterial activity. Compositional analysis of the intact suberized cell walls using solid-state 13C NMR (ssNMR) showed that NAC silencing produced an increase in the long-chain aliphatic groups deposited within the periderm cell walls. LC-MS of polar extracts revealed up-regulation of glycoalkaloids in both StNAC103-RNAi and StNAC103-RNAi-c native periderms but down-regulation of a phenolic amine in StNAC103-RNAi-c and a phenolic acid in StNAC103-RNAi native periderms. The nonpolar soluble metabolites identified using GC-MS included notably abundant long-chain alkane metabolites in both silenced samples. By coordinating the differentially accumulated soluble metabolites and the suberin depolymerization products with the ssNMR-based profiles for the periderm polymers, it was possible to obtain a holistic view of the chemical changes that result from StNAC103 gene silencing. Correspondingly, the chemical composition trends served as a backdrop to interpret trends in the chemical barrier defense function of native tuber periderms, which was found to be more robust for the nonpolar extracts.

Root structural plasticity enhances salt tolerance in mature olives

Roots are the first plant organ to encounter, sense, and respond to soil salinity. Like for many moderately salt tolerant species, roots of olive (Olea eurpaea) trees are the principal players in salt tolerance. We studied roots of mature olive trees in order to illuminate the yet vague mechanism(s) of root salt exclusion.Root structural traits were examined in olive trees grown in lysimeters and from a long-term salinity field trial. The distribution of salts was detected in root cross-sections using scanning electron microscopy combined with energy dispersive spectroscopy.Increased soil salinity caused a continuous decline in specific root length and an increase in root diameter, periderm thickness, and specific hydraulic conductivity. While periderm cell number was not modified, cell diameter increased linearly by a total of 50 % as root zone salinity increased nearly eight-fold. Strong compartmentation of Na within the periderm was found, with highest content in the outer periderm layer and lowest content in the stele. Increase in soil salinity was associated with decrease in stele area, yet, hydraulic conductivity was doubled due to higher fraction of large diameter xylem vessels.Our results indicate significant root structural plasticity, which underlies the salt resistance mechanisms. The dominant trait enabling salt tolerance of olive trees is the enlarged periderm serving as an apoplastic barrier that enhances salt compartmentation and exclusion from the vascular tissues.

A Study on Determination of Anatomical and Micromorphological Properties of Capsella bursa-pastoris (L.) Medik. (Brassicaceae) in Turkey

In this study, we aimed to reveal the anatomical features of Capsella bursa-pastoris (L.) Medik., a medicinal plant. Samples of C. pastoris taxon were collected from Tokat and its environs in June 2018. The collected samples were placed in 70% alcohol and fixed. Transversal section sections were taken from the root, stem and petiole of the plant for anatomical research. Both transversal section and superficial sections were taken of the leaves by hand. There were 2-3 rows of periderm cells on the outermost part of the root transversal section section of the plant. In the stem transversal section, the collenchyma was in the form of a continuous ring of 7-8 rows, just below epidermis. Sclerenchyma forms an intervascular ring. The epidermis cells on the lower and upper surfaces of the leaf were single-row. The leaves were bifacial type. Palisade parenchyma cells were in 1-2 rows. The sponge parenchyma was 3-4 stratified The epidermal cell edges of the lower surface of the leaf of C. bursa-pastoris were wavier than the upper surface cell edges. Stomata were anisocytic. The vascular bundle in the petiole mid-vessel region of the taxon was large and 4-5 of them. The vascular bundles were surrounded by a sclerenchymatic scabbard. The petiole epidermis was monolayer and had cuticle on the surfaces. The fruit of the taxon was heart-shaped and had a striate pattern. Seed shape was elliptical, striate- undulate cell shaped, cell wall thickening was very pronounced. Ornamentations were reticulate. Wax was observed on the abaxial and adaxial surface of the leaf. Corolla surface showed very intense longitudinal cuticular folds. Sepal surface had plenty of sail-shaped papillae. As a result, the root, stem, leaf anatomical features, and fruit, seed, leaf sepal and petal micromorphological features of C. bursa-pastoris had been revealed in detail.

Impact of 2,4-D and potato (Solanum tuberosum L.) tuber age on anthocyanin content of skin and phellem anatomy of Red Norland

Attractive appearance is highly desirable for fresh market red-skinned potatoes. Red potatoes derive their skin color from anthocyanins. Some growers attempt to enhance red potato skin color by treating vines with the synthetic auxin 2,4-D. In this study, 2,4-D was applied twice at early bloom stage to ‘Red Norland’ potatoes and tubers were harvested weekly until plants senesced. 2,4-D rapidly increased anthocyanin quantity and altered anthocyanin composition. Average tuber mass at the final harvest was less for the 2,4-D-treatment than untreated controls. Elevated anthocyanin content resulting from 2,4-D persisted through 3 months storage. 2,4-D-treated potatoes did not differ from untreated controls in the number and depth of red pigmented cells in the phellem. Thus, changes in periderm cell division and expansion may not contribute to the 2,4-D response of ‘Red Norland’. Instead, the data suggest that 2,4-D application initiated a rapid change in anthocyanin accumulation that persisted into storage.

Periderm invasion contributes to epithelial formation in the teleost pharynx

The gnathostome pharyngeal cavity functions in food transport and respiration. In amniotes the mouth and nares are the only channels allowing direct contact between internal and external epithelia. In teleost fish, gill slits arise through opening of endodermal pouches and connect the pharynx to the exterior. Using transgenic zebrafish lines, cell tracing, live imaging and different markers, we investigated if pharyngeal openings enable epithelial invasion and how this modifies the pharyngeal epithelium. We conclude that in zebrafish the pharyngeal endoderm becomes overlain by cells with a peridermal phenotype. In a wave starting from pouch 2, peridermal cells from the outer skin layer invade the successive pouches until halfway their depth. Here the peridermal cells connect to a population of cells inside the pharyngeal cavity that express periderm markers, yet do not invade from outside. The latter population expands along the midline from anterior to posterior until the esophagus-gut boundary. Together, our results show a novel role for the periderm as an internal epithelium becomes adapted to function as an external surface.

Functional characterisation of romeharsha and clint1 reaffirms the link between plasma membrane homeostasis, cell size maintenance and tissue homeostasis in developing zebrafish epidermis

In vertebrates, early developing epidermis is a bilayered epithelium consisting of an outer periderm and the underlying basal epidermis. It eventually develops into a multi-layered epithelium. The mechanisms that control the architecture and homeostasis of early developing bilayered epidermis have remained poorly understood. Recently, we have shown that the function of Myosin Vb, an actin based molecular motor, is essential in peridermal cells for maintenance of plasma membrane homeostasis. Furthermore, our analyses of the goosepimples/myosin Vb mutant unravelled a direct link between plasma membrane homeostasis, cell size maintenance and tissue homeostasis in the developing epidermis. However, it remained unclear whether this link is specific to myosin Vb mutant or this is a general principle. Here we have identified two more genetic conditions, romeharsha mutant and clint1 knockdown, in which membrane homeostasis is perturbed, as evident by increased endocytosis and accumulation of lysosomes. As a consequence, peridermal cells exhibit smaller size and increased proliferation. We further show that decreasing endocytosis in romeharsha mutant and clint1 morphants rescues or mitigates the effect on cell size, cell proliferation and morphological phenotype. Our data confirms generality of the principle by reaffirming the causal link between plasma membrane homeostasis, cell size maintenance and tissue homeostasis.