Frond architecture of the rootless duckweed Wolffia globosa

Abstract Background The plant body in duckweed species has undergone reduction and simplification from the ancient Spirodela species towards more derived Wolffia species. Among the five duckweed genera, Wolffia members are rootless and represent the smallest and most reduced species. A better understanding of Wolffia frond architecture is necessary to fully explore duckweed evolution. Results We conducted a comprehensive study of the morphology and anatomy of Wolffia globosa, the only Wolffia species in China. We first used X-ray microtomography imaging to reveal the three-dimensional and internal structure of the W. globosa frond. This showed that new fronds rapidly budded from the hollow reproductive pocket of the mother fronds and that several generations at various developmental stages could coexist in a single W. globosa frond. Using light microscopy, we observed that the meristem area of the W. globosa frond was located at the base of the reproductive pocket and composed of undifferentiated cells that continued to produce new buds. A single epidermal layer surrounded the W. globosa frond, and the mesophyll cells varied from small and dense palisade-like parenchyma cells to large, vacuolated cells from the ventral to the dorsal part. Furthermore, W. globosa fronds contained all the same organelles as other angiosperms; the most prominent organelles were chloroplasts with abundant starch grains. Conclusions Our study revealed that the reproductive strategy of W. globosa plants enables the rapid accumulation of biomass and the wide distribution of this species in various habitats. The reduced body plan and size of Wolffia are consistent with our observation that relatively few cell types are present in these plants. We also propose that W. globosa plants are not only suitable for the study of structural reduction in higher plants, but also an ideal system to explore fundamental developmental processes of higher plants that cannot be addressed using other model plants.

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Frond Architecture of The Rootless Duckweed Wolffia Globosa

10.21203/rs.3.rs-151190/v1 ◽

2021 ◽

Author(s):

Jingjing Yang ◽

Xuyao Zhao ◽

Gaojie Li ◽

Shiqi Hu ◽

Hongwei Hou

Keyword(s):

Developmental Stages ◽

Higher Plants ◽

Three Dimensional ◽

Wide Distribution ◽

Detailed Knowledge ◽

Mesophyll Cells ◽

Reduced Body ◽

Ideal System ◽

Undifferentiated Cells ◽

Vacuolated Cells

Abstract Background: The plant body of duckweed species has undergone reduction and simplification from the ancient Spirodela species towards more-derived Wolffia species. Among the five duckweed genera, Wolffia members are rootless and represent the smallest and most-reduced species. However, we lack detailed knowledge about their structure. Results: We conducted a comprehensive study of the morphology and anatomy of Wolffia globosa, the only Wolffia species in China. We first used X-ray microtomography imaging to reveal the three-dimensional and internal structure of the W. globosa frond. This showed that new fronds rapidly budded from the hollow reproductive pocket of the mother fronds and that several generations at various developmental stages could coexist in a single W. globosa frond. Using light microscopy, we observed that the meristem area of the W. globosa frond was located at the base of the reproductive pocket and composed of undifferentiated cells that continued to produce new buds. A single epidermal layer surrounded the W. globosa frond, and the mesophyll cells varied from small and dense palisade-like parenchyma cells to large, vacuolated cells from the ventral to the dorsal part. Furthermore, W. globosa fronds contained all the same organelles as other angiosperms; the most prominent organelles were chloroplasts with abundant starch grains. Conclusions: Our study revealed that the reproductive strategy of W. globosa plants enables the rapid accumulation of biomass and the wide distribution of this species in various habitats. Despite their reduced body plan and size, the simplicity of the W. globosa frond might be overestimated. We propose that W. globosa plants are not only suitable for the study of structural reduction in higher plants, but also an ideal system to explore fundamental developmental processes of higher plants that cannot be addressed using other model plants.

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Taiji: System-level identification of key transcription factors reveals transcriptional waves in mouse embryonic development

Science Advances ◽

10.1126/sciadv.aav3262 ◽

2019 ◽

Vol 5 (3) ◽

pp. eaav3262 ◽

Cited By ~ 7

Author(s):

Kai Zhang ◽

Mengchi Wang ◽

Ying Zhao ◽

Wei Wang

Keyword(s):

Transcription Factors ◽

Embryonic Development ◽

Regulatory Networks ◽

Target Genes ◽

Developmental Stages ◽

Three Dimensional ◽

Cell Types ◽

System Level ◽

Transcriptional Regulatory Networks ◽

Developmental Progress

Transcriptional regulation is pivotal to the specification of distinct cell types during embryonic development. However, it still lacks a systematic way to identify key transcription factors (TFs) orchestrating the temporal and tissue specificity of gene expression. Here, we integrated epigenomic and transcriptomic data to reveal key regulators from two cells to postnatal day 0 in mouse embryogenesis. We predicted three-dimensional chromatin interactions in 12 tissues across eight developmental stages, which facilitates linking TFs to their target genes for constructing transcriptional regulatory networks. To identify driver TFs, we developed a new algorithm, dubbed Taiji, to assess the global influence of each TF and systematically uncovered TFs critical for lineage-specific and stage-dependent tissue specification. We have also identified TF combinations that function in spatiotemporal order to form transcriptional waves regulating developmental progress. Furthermore, lacking stage-specific TF combinations suggests a distributed timing strategy to orchestrate the coordination between tissues during embryonic development.

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Plastid tubules of higher plants are tissue-specific and developmentally regulated

Journal of Cell Science ◽

10.1242/jcs.113.1.81 ◽

2000 ◽

Vol 113 (1) ◽

pp. 81-89 ◽

Cited By ~ 2

Author(s):

R.H. Kohler ◽

M.R. Hanson

Keyword(s):

Laser Scanning ◽

Fluorescent Protein ◽

Higher Plants ◽

Cell Types ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Suspension Cells ◽

Developmentally Regulated ◽

Mesophyll Cells ◽

Green Fluorescent

Green fluorescent stroma filled tubules (stromules) emanating from the plastid surface were observed in transgenic plants containing plastid-localized green fluorescent protein (GFP). These transgenic tobacco plants were further investigated by epifluorescence and confocal laser scanning microscopy (CSLM) to identify developmental and/or cell type specific differences in the abundance and appearance of stromules and of plastids. Stromules are rarely seen on chlorophyll-containing plastids in cell types such as trichomes, guard cells or mesophyll cells of leaves. In contrast, they are abundant in tissues that contain chlorophyll-free plastids, such as petal and root. The morphology of plastids in roots and petals is highly dynamic, and plastids are often elongated and irregular. The shapes, size, and position of plastids vary in particular developmental zones of the root. Furthermore, suspension cells of tobacco exhibit stromules on virtually every plastid with two major forms of appearance. The majority of cells show a novel striking ‘octopus- or millipede-like’ structure with plastid bodies clustered around the nucleus and with long thin stromules of up to at least 40 (micro)m length stretching into distant areas of the cell. The remaining cells have plastid bodies distributed throughout the cell with short stromules. Photobleaching experiments indicated that GFP can flow through stromules and that the technique can be used to distinguish interconnected plastids from independent plastids.

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Single nuclei transcriptome of the Lesser Duckweed Lemna minuta reveals cell trajectories for an entire plant

10.1101/2021.06.03.446947 ◽

2021 ◽

Author(s):

Bradley W Abramson ◽

Mark Novotny ◽

Nolan T Hartwick ◽

Kelly Colt ◽

Brian D Aevermann ◽

...

Keyword(s):

Cell Types ◽

Cell Number ◽

Model Organisms ◽

Developmental Cycle ◽

Mesophyll Cells ◽

Root Cells ◽

Reduced Body ◽

Entire Plant ◽

Model Plant Arabidopsis Thaliana ◽

Cell Trajectory

The ability to trace every cell in some model organisms has led to the fundamental understanding of development and cellular function. However, in plants the complexity of cell number, organ size and developmental times makes this a challenge even in the diminutive model plant Arabidopsis thaliana. Here we develop the Lesser Duckweed Lemna minuta as a model with a reduced body plan, small genome size and clonal growth pattern that enables simultaneous tracing of cells from the entire plant over the complete developmental cycle. We generated a chromosome-resolved genome for the 360 megabase genome and defined the growth trajectory of the entire plant with single nuclei RNA sequencing. The L. minuta gene complement represents a primarily non-redundant set with only the ancient tau whole genome duplication shared with all monocots, and paralog expansion as a result of tandem duplications related to phytoremediation. Thirteen distinct cell types representing meristem, the leaf-stem fusion called a frond, and root-like tissues were defined using gene orthology with single cell expression from model plants, gene ontology categories, and cell trajectory analysis. Dividing meristem cells give rise to two main branches of root-transition and mesophyll cells, which then give rise to terminally differentiated parenchyma, epidermal and root cells. Mesophyll tissues express high levels of elemental transport genes consistent with this tissue playing a role in L. minuta wastewater detoxification. The L. minuta genome and cell map provide a paradigm to decipher developmental genes and pathways for an entire plant.

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SEM of Hepatocytes and Biliary Passages in Goldfish Liver

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080213 ◽

1977 ◽

Vol 35 ◽

pp. 556-557

Author(s):

Waykin Nopanitaya ◽

Joe W. Grisham ◽

Johnny L. Carson

Keyword(s):

Carassius Auratus ◽

Cell Layer ◽

Three Dimensional ◽

Cell Types ◽

Biliary System ◽

Fish Food ◽

Commercial Fish ◽

Goldfish Carassius Auratus ◽

Commercial Fish Food

An interesting feature of the goldfish liver is the morphology of the hepatic plate, which is always formed by a two-cell layer of hepatocytes. Hepatic plates of the goldfish liver contain an infrequently seen second type of cell, in the centers of plates between two hepatocytes. A TEH study by Yamamoto (1) demonstrated ultrastructural differences between hepatocytes and centrally located cells in hepatic plates; the latter were classified as ductule cells of the biliary system. None of the previous studies clearly showed a three-dimensional organization of the two cell types described. In the present investigation we utilize SEM to elucidate the arrangement of hepatocytes and bile ductular cells in intralobular plates of goldfish liver.Livers from young goldfish (Carassius auratus), about 6-10 cm, fed commercial fish food were used for this study. Hepatic samples were fixed in 4% buffered paraformaldehyde, cut into pieces, fractured, osmicated, CPD, mounted Au-Pd coated, and viewed by SEM at 17-20 kV. Our observations were confined to the ultrastructure of biliary passages within intralobular plates, ductule cells, and hepatocytes.

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Correlated Studies of Cellular Interactions Using TEM, Freeze Etching, and SEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010005161x ◽

1974 ◽

Vol 32 ◽

pp. 320-321

Author(s):

J. P. Revel

Keyword(s):

Developmental Stages ◽

Three Dimensional ◽

Cell Movement ◽

Cellular Interactions ◽

Serial Sections ◽

Cell Sheets ◽

Freeze Etching ◽

Early Developmental

Movement of individual cells or of cell sheets and complex patterns of folding play a prominent role in the early developmental stages of the embryo. Our understanding of these processes is based on three- dimensional reconstructions laboriously prepared from serial sections, and from autoradiographic and other studies. Many concepts have also evolved from extrapolation of investigations of cell movement carried out in vitro. The scanning electron microscope now allows us to examine some of these events in situ. It is possible to prepare dissections of embryos and even of tissues of adult animals which reveal existing relationships between various structures more readily than used to be possible vithout an SEM.

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In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100083035 ◽

1978 ◽

Vol 36 (2) ◽

pp. 434-435

Author(s):

D. Reis ◽

B. Vian ◽

J. C. Roland

Keyword(s):

Cell Wall ◽

Self Assembly ◽

Plant Cell Wall ◽

Higher Plants ◽

Three Dimensional ◽

Cytochemical Study ◽

Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

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Epithelial Organotypic Cultures: A Viable Model to Address Mechanisms of Carcinogenesis by Epitheliotropic Viruses

Current Topics in Medicinal Chemistry ◽

10.2174/1568026618666180410125850 ◽

2018 ◽

Vol 18 (4) ◽

pp. 246-255 ◽

Cited By ~ 1

Author(s):

Lara Termini ◽

Enrique Boccardo

Keyword(s):

Three Dimensional ◽

Cell Types ◽

Experimental Models ◽

Biological Research ◽

Specific Gene ◽

Specific Cell ◽

Organotypic Cultures ◽

Skin Physiology

In vitro culture of primary or established cell lines is one of the leading techniques in many areas of basic biological research. The use of pure or highly enriched cultures of specific cell types obtained from different tissues and genetics backgrounds has greatly contributed to our current understanding of normal and pathological cellular processes. Cells in culture are easily propagated generating an almost endless source of material for experimentation. Besides, they can be manipulated to achieve gene silencing, gene overexpression and genome editing turning possible the dissection of specific gene functions and signaling pathways. However, monolayer and suspension cultures of cells do not reproduce the cell type diversity, cell-cell contacts, cell-matrix interactions and differentiation pathways typical of the three-dimensional environment of tissues and organs from where they were originated. Therefore, different experimental animal models have been developed and applied to address these and other complex issues in vivo. However, these systems are costly and time consuming. Most importantly the use of animals in scientific research poses moral and ethical concerns facing a steadily increasing opposition from different sectors of the society. Therefore, there is an urgent need for the development of alternative in vitro experimental models that accurately reproduce the events observed in vivo to reduce the use of animals. Organotypic cultures combine the flexibility of traditional culture systems with the possibility of culturing different cell types in a 3D environment that reproduces both the structure and the physiology of the parental organ. Here we present a summarized description of the use of epithelial organotypic for the study of skin physiology, human papillomavirus biology and associated tumorigenesis.

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Four Mutant Alleles Elucidate the Role of the G2 Protein in the Development of C4 and C3 Photosynthesizing Maize Tissues

Genetics ◽

10.1093/genetics/159.2.787 ◽

2001 ◽

Vol 159 (2) ◽

pp. 787-797

Author(s):

Lizzie Cribb ◽

Lisa N Hall ◽

Jane A Langdale

Keyword(s):

Cell Types ◽

Bundle Sheath ◽

Primary Role ◽

Ribulose Bisphosphate Carboxylase ◽

Sheath Cell ◽

Mesophyll Cells ◽

Phenotypic Data ◽

Bisphosphate Carboxylase ◽

Bundle Sheath Cell

Abstract Maize leaf blades differentiate dimorphic photosynthetic cell types, the bundle sheath and mesophyll, between which the reactions of C4 photosynthesis are partitioned. Leaf-like organs of maize such as husk leaves, however, develop a C3 pattern of differentiation whereby ribulose bisphosphate carboxylase (RuBPCase) accumulates in all photosynthetic cell types. The Golden2 (G2) gene has previously been shown to play a role in bundle sheath cell differentiation in C4 leaf blades and to play a less well-defined role in C3 maize tissues. To further analyze G2 gene function in maize, four g2 mutations have been characterized. Three of these mutations were induced by the transposable element Spm. In g2-bsd1-m1 and g2-bsd1-s1, the element is inserted in the second intron and in g2-pg14 the element is inserted in the promoter. In the fourth case, g2-R, four amino acid changes and premature polyadenylation of the G2 transcript are observed. The phenotypes conditioned by these four mutations demonstrate that the primary role of G2 in C4 leaf blades is to promote bundle sheath cell chloroplast development. C4 photosynthetic enzymes can accumulate in both bundle sheath and mesophyll cells in the absence of G2. In C3 tissue, however, G2 influences both chloroplast differentiation and photosynthetic enzyme accumulation patterns. On the basis of the phenotypic data obtained, a model that postulates how G2 acts to facilitate C4 and C3 patterns of tissue development is proposed.

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Zika Virus Infection Leads to Demyelination and Axonal Injury in Mature CNS Cultures

Viruses ◽

10.3390/v13010091 ◽

2021 ◽

Vol 13 (1) ◽

pp. 91

Author(s):

Verena Schultz ◽

Stephanie L. Cumberworth ◽

Quan Gu ◽

Natasha Johnson ◽

Claire L. Donald ◽

...

Keyword(s):

Nervous System ◽

Neural Development ◽

Zika Virus ◽

Developmental Stages ◽

Cell Types ◽

Neural Cells ◽

Zikv Infection ◽

Axonal Pathology ◽

Time Frames

Understanding how Zika virus (Flaviviridae; ZIKV) affects neural cells is paramount in comprehending pathologies associated with infection. Whilst the effects of ZIKV in neural development are well documented, impact on the adult nervous system remains obscure. Here, we investigated the effects of ZIKV infection in established mature myelinated central nervous system (CNS) cultures. Infection incurred damage to myelinated fibers, with ZIKV-positive cells appearing when myelin damage was first detected as well as axonal pathology, suggesting the latter was a consequence of oligodendroglia infection. Transcriptome analysis revealed host factors that were upregulated during ZIKV infection. One such factor, CCL5, was validated in vitro as inhibiting myelination. Transferred UV-inactivated media from infected cultures did not damage myelin and axons, suggesting that viral replication is necessary to induce the observed effects. These data show that ZIKV infection affects CNS cells even after myelination—which is critical for saltatory conduction and neuronal function—has taken place. Understanding the targets of this virus across developmental stages including the mature CNS, and the subsequent effects of infection of cell types, is necessary to understand effective time frames for therapeutic intervention.

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