scholarly journals Roles of neuroepithelial cell rearrangement and division in shaping of the avian neural plate

Development ◽  
1989 ◽  
Vol 106 (3) ◽  
pp. 427-439
Author(s):  
G.C. Schoenwolf ◽  
I.S. Alvarez
Keyword(s):  
Cell Division ◽  
Fold Increase ◽  
Cell Number ◽  
Neural Plate ◽  
Neuroepithelial Cell ◽  
Cell Rearrangement ◽  
Constant Size ◽  
Division Cell ◽  
Longitudinal Cell ◽  
Number Of Cells

Shaping of the neural plate, one of the most striking events of neurulation, involves rapid craniocaudal extension. In this study, we evaluated the roles of two processes in neural plate extension: neuroepithelial cell rearrangement and cell division. Quail epiblast plugs of constant size were grafted either just rostral to Hensen's node or paranodally and the resulting chimeras were examined at selected times postgrafting. By comparing the size of the original plug, the number of cells it contained and the distribution of cells within it to those same features of the grafts in chimeras, we were able to ascertain that, during transformation of the flat neural plate into the closed neural tube (a period requiring 24 h), the graft undergoes a maximum of 3 rounds of craniocaudal extension (each round of craniocaudal extension was defined as a doubling of graft length, so 3 rounds equaled an 8-fold increase in length). Such extension is accompanied by 2 rounds of cell rearrangement and 2–3 rounds of cell division (cell rearrangement occurred mediolaterally, so each round was defined as a halving of the number of cells in the width of the graft and a doubling of the number of cells in its length; each round of cell division was defined as a doubling of graft cell number). Modeling studies demonstrate that these amounts of cell rearrangement and division are sufficient to approximate the shaping of the neural plate that normally ensues during neurulation, provided that some of the cell division occurs within the longitudinal plane of the neural plate and some within its transverse plane: longitudinal cell division results in craniocaudal extension of the neural plate, whereas transverse cell division results in lateral expansion of the neural plate such as that occurring at its cranial end; cell rearrangement results in craniocaudal extension of the neural plate as well as in its narrowing. In conclusion, our results provide evidence that shaping of the neural plate involves mediolateral cell rearrangement and cell division, with the latter occurring within both the longitudinal and transverse planes of the neural plate.

scholarly journals Transcriptome and Metabolome Comparison of Smooth and Rough Citrus limon L. Peels Grown on Same Trees and Harvested in Different Seasons

2021 ◽  
Vol 12 ◽  
Author(s):  
Hong-ming Liu ◽  
Chun-rui Long ◽  
Shao-hua Wang ◽  
Xiao-meng Fu ◽  
Xian-yan Zhou ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Cell Division ◽  
Asymmetric Cell Division ◽  
Cell Number ◽  
Mitogen Activated Protein Kinase ◽  
Citrus Limon ◽  
Hypocotyl Growth ◽  
Different Seasons ◽  
Autumn Flowering ◽  
Division Cell

Background: Farmers harvest two batches fruits of Lemons (Citrus limon L. Burm. f.) i.e., spring flowering fruit and autumn flowering fruit in dry-hot valley in Yunnan, China. Regular lemons harvested in autumn have smooth skin. However, lemons harvested in spring have rough skin, which makes them less attractive to customers. Furthermore, the rough skin causes a reduction in commodity value and economical losses to farmers. This is a preliminary study that investigates the key transcriptomic and metabolomic differences in peels of lemon fruits (variety Yuning no. 1) harvested 30, 60, 90, 120, and 150 days after flowering from the same trees in different seasons.Results: We identified 5,792, 4,001, 3,148, and 5,287 differentially expressed genes (DEGs) between smooth peel (C) and rough peel (D) 60, 90, 120, and 150 days after flowering, respectively. A total of 1,193 metabolites differentially accumulated (DAM) between D and C. The DEGs and DAMs were enriched in the mitogen-activated protein kinase (MAPK) and plant hormone signaling, terpenoid biosynthesis, flavonoid, and phenylalanine biosynthesis, and ribosome pathways. Predominantly, in the early stages, phytohormonal regulation and signaling were the main driving force for changes in peel surface. Changes in the expression of genes associated with asymmetric cell division were also an important observation. The biosynthesis of terpenoids was possibly reduced in rough peels, while the exclusive expression of cell wall synthesis-related genes could be a possible reason for the thick peel of the rough-skinned lemons. Additionally, cell division, cell number, hypocotyl growth, accumulation of fatty acids, lignans and coumarins- related gene expression, and metabolite accumulation changes were major observations.Conclusion: The rough peels fruit (autumn flowering fruit) and smooth peels fruit (spring flowering fruit) matured on the same trees are possibly due to the differential regulation of asymmetric cell division, cell number regulation, and randomization of hypocotyl growth related genes and the accumulation of terpenoids, flavonoids, fatty acids, lignans, and coumarins. The preliminary results of this study are important for increasing the understanding of peel roughness in lemon and other citrus species.

Cell movements driving neuruiation in avian embryos

Development ◽  
1991 ◽  
Vol 113 (Supplement_2) ◽  
pp. 157-168 ◽  
Author(s):  
Gary C. Schoenwolf
Keyword(s):  
Cell Division ◽  
Cell Fate ◽  
Cell Number ◽  
Neural Plate ◽  
Avian Embryos ◽  
Cell Movements ◽  
L Cells ◽  
L Cell ◽  
Cell Position ◽  
Area Pellucida

Neuruiation, formation of the neural tube, a crucial event of early embryogenesis, is believed to be driven by the coordination of a number of diverse morphogenetic cell behaviors. Such behaviors include changes in cell number (division, death), cell shape and size (wedging, palisading and spreading), cell position (rearrangement or intercalation) and cell–cell and cell–matrix associations (including inductive interactions). The focus of this essay is on epiblast cell movements and their role in shaping and bending of the neural plate. Neuruiation is a multifactorial process requiring both intrinsic (within the neural plate) and extrinsic (outside the neural plate) forces. The origin and movements of three populations of epiblast cells have been studied in avian embryos by constructing quail/chick transplantation chimeras and by labeling cells in situ with identifiable, heritable markers. MHP (median hinge-point neurepithelial) cells originate principally from a midline epiblast area rostral to and overlapping Hensen's node. In addition, a few caudal MHP cells originate from paranodal epiblast areas. MHP cells stream down the length of the midline neuraxis in the wake of the regressing Hensen's node. This streaming occurs as a result of cell division (presumably oriented so that daughter cells are placed into the longitudinal plane rather than into the transverse plane) and rearrangement (intercalation), resulting in a narrowing of the width of the MHP region with a concomitant increase in its length. L (lateral neurepithelial) cells originate from paired epiblast areas flanking the rostral portion of the primitive streak, and they stream down the length of the lateral neuraxis concomitant with regression of Hensen's node. They do so both by oriented cell division and by intercalation. SE (surface epithelial) cells originate from the epiblast of the area pellucida, as far lateral as near the area pellucida area opaca border. From this area they stream medially, toward the forming lateral margins of the neural plate. Collectively, movements of the three populations of epiblast cells generate the convergent-extension movements characteristic of the epiblast during neuruiation. Heterotopic grafting has been used to assess the relationship between cell position and cell fate and to determine whether transplanted heterotopic cells can adopt the behaviors typical of the new site. For example, SE cells can replace L cells, changing their fate and adopting L-cell behavior. Similarly, prospective MHP and L cells both can change their fate and adopt the behavior of SE cells. L cells, when placed into prospective MHP-cell territory, move out of this territory by intermingling with adjacent host L cells. Likewise, prospective MHP cells placed into L-cell territory, move out of this territory by intermingling with host MHP cells. Collectively, these results suggest that cell fate is determined principally by the ultimate position of cells, and that adjacent, different cell populations are restricted from intermingling with one another. How positional information is specified, the nature of restriction of intermingling and the guidance cues used for cell navigation during streaming remain to be elucidated.

scholarly journals Sound Waves Promote Arabidopsis thaliana Root Growth by Regulating Root Phytohormone Content

2021 ◽  
Vol 22 (11) ◽  
pp. 5739
Author(s):  
Joo Yeol Kim ◽  
Hyo-Jun Lee ◽  
Jin A Kim ◽  
Mi-Jeong Jeong
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Division ◽  
Root Growth ◽  
Apical Meristem ◽  
Cell Number ◽  
Root Apical Meristem ◽  
Control Group ◽  
Auxin Signaling ◽  
Ethylene Signaling ◽  
Sound Waves

Sound waves affect plants at the biochemical, physical, and genetic levels. However, the mechanisms by which plants respond to sound waves are largely unknown. Therefore, the aim of this study was to examine the effect of sound waves on Arabidopsis thaliana growth. The results of the study showed that Arabidopsis seeds exposed to sound waves (100 and 100 + 9k Hz) for 15 h per day for 3 day had significantly longer root growth than that in the control group. The root length and cell number in the root apical meristem were significantly affected by sound waves. Furthermore, genes involved in cell division were upregulated in seedlings exposed to sound waves. Root development was affected by the concentration and activity of some phytohormones, including cytokinin and auxin. Analysis of the expression levels of genes regulating cytokinin and auxin biosynthesis and signaling showed that cytokinin and ethylene signaling genes were downregulated, while auxin signaling and biosynthesis genes were upregulated in Arabidopsis exposed to sound waves. Additionally, the cytokinin and auxin concentrations of the roots of Arabidopsis plants increased and decreased, respectively, after exposure to sound waves. Our findings suggest that sound waves are potential agricultural tools for improving crop growth performance.

scholarly journals A Fast, Decentralized, Self-Aligned Carrier Method for Multicellular Converters

2020 ◽  
Vol 11 (1) ◽  
pp. 137
Author(s):  
Quoc Dung Phan ◽  
Guillaume Gateau ◽  
Phu Cong Nguyen ◽  
Marc Cousineau ◽  
Huu Phuc To ◽  
...  
Keyword(s):  
Conventional Method ◽  
Pulse Width ◽  
Pulse Width Modulation ◽  
Iteration Process ◽  
Cell Number ◽  
Index Number ◽  
Multilevel Converter ◽  
Start Up ◽  
Multiphase Converters ◽  
Number Of Cells

This paper proposes a fast, decentralized method for self-aligning the carriers of a multiphase/multilevel converter operating on the basis of phase-shifted pulse width modulation or level-shifted pulse width modulation. In the proposed method, each cell of the converter synchronizes and updates simultaneously its own carrier angle or carrier level based on the information shared with its neighboring cell, such as its angle/level, its index number, and the total number of activated cells of the converter. Different from the conventional decentralized method (with basic and modified updating rules), which requires some conditions in terms of cell number and initial carrier angles to start up and operate properly, the proposed method can be applied to the system with any number of cells and does not require special conditions of initial carrier angles. Further, while the conventional method needs an iteration process to adjust the inter-carrier phase-shifts and can be applied only to a multiphase converter which uses phase-shifted pulse width modulation, the proposed method offers an accurate and fast alignment of phases (for phase-shifted pulse width modulation) or levels (for level-shifted pulse width modulation) and thus can be applied to both multiphase and multilevel converter types. The simulations and the experimental results are presented in detail to show the validity and the effectiveness of the proposed methods. Further, thorough simulations on multiphase converters with different number of cells also show that the proposed method is much faster than the conventional method in both configuration and reconfiguration processes, especially in case the system has a large number of cells.

SOME EFFECTS ON FRUIT SIZE OF CHROMOSOME 2 OF THE TOMATO

1965 ◽  
Vol 43 (1) ◽  
pp. 137-146
Author(s):  
L. Butler
Keyword(s):  
Linkage Map ◽  
Fruit Size ◽  
Cell Number ◽  
Major Effect ◽  
Fruit Weight ◽  
Pleiotropic Effects ◽  
Chromosome 2 ◽  
Small Fruit ◽  
Number Of Cells

Fruit weights taken from two F2's of 1500 plants indicated that the genes d p o s Lc dil and suf all affect fruit weight. The recessive alleles, except suf and Lc, were associated with small fruit size. The data were analyzed to determine whether this association was the result of linkage or pleiotropic effects. The major effect occurred in the o region, which is some 44 units from the centromere of chromosome 2. The o gene makes the genes oval or pear-shaped instead of spherical, and it is shown that when the locule wall of a spherical fruit and an oval fruit are composed of the same number of cells, the spherical fruit is always heavier. Since cell number is the inherited unit of fruit size, then o is always associated with small size. A gene controlling number of locules, which affects fruit size, is also located in this section of the chromosome. The genes d and s, which are at opposite ends of the present linkage map, both appear to be linked with fruit size genes. It is suggested that these size genes lie in the hetero-chromatin which is adjacent to both ends of the linkage map. The genes dil and suf, which were produced by radiation of the same variety, appear to have pleiotropic effects on fruit size; suf increasing, and dil decreasing fruit size.

A novel epithelial cell from neonatal rat lung: isolation and differentiated phenotype

1990 ◽  
Vol 259 (6) ◽  
pp. L415-L425 ◽  
Author(s):  
P. E. Roberts ◽  
D. M. Phillips ◽  
J. P. Mather
Keyword(s):  
Epithelial Cell ◽  
Molecular Mechanisms ◽  
Basal Medium ◽  
Fold Increase ◽  
Cell Types ◽  
Cell Number ◽  
Neonatal Rat ◽  
Rat Lung ◽  
Cell Type

A novel epithelial cell from normal neonatal rat lung has been isolated, established, and maintained for multiple passages in the absence of serum, without undergoing crisis or senescence. By careful manipulation of the nutrition/hormonal microenvironment, we have been able to select, from a heterogeneous population, a single epithelial cell type that can maintain highly differentiated features in vitro. This cell type has characteristics of bronchiolar epithelial cells. A clonal line, RL-65, has been selected and observed for greater than 2 yr in continuous culture. It has been characterized by ultrastructural, morphological, and biochemical criteria. The basal medium for this cell line is Ham's F12/Dulbecco's modified Eagle's (DME) medium plus insulin (1 micrograms/ml), human transferrin (10 micrograms/ml), ethanolamine (10(-4) M), phosphoethanolamine (10(-4) M), selenium (2.5 x 10(-8) M), hydrocortisone (2.5 x 10(-7) M), and forskolin (5 microM). The addition of 150 micrograms/ml of bovine pituitary extract to the defined basal medium stimulates a greater than 10-fold increase in cell number and a 50- to 100-fold increase in thymidine incorporation. The addition of retinoic acid results in further enhancement of cell growth and complete inhibition of keratinization. We have demonstrated a strategy that may be applicable to isolating other cell types from the lung and maintaining their differentiated characteristics for long-term culture in vitro. Such a culture system promises to be a useful model in which to study cellular events associated with differentiation and proliferation in the lung and to better understand the molecular mechanisms involved in these events.

scholarly journals Balancing dynamic tradeoffs drives cellular reprogramming

2018 ◽  
Author(s):  
Kimberley N. Babos ◽  
Kate E. Galloway ◽  
Kassandra Kisler ◽  
Madison Zitting ◽  
Yichen Li ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Cell Division ◽  
Motor Neuron ◽  
Molecular Mechanisms ◽  
Cell Types ◽  
Cellular Reprogramming ◽  
Cellular Event ◽  
Chemical Factors ◽  
Number Of Cells ◽  
Transcription And Replication

AbstractAlthough cellular reprogramming continues to generate new cell types, reprogramming remains a rare cellular event. The molecular mechanisms that limit reprogramming, particularly to somatic lineages, remain unclear. By examining fibroblast-to-motor neuron conversion, we identify a previously unappreciated dynamic between transcription and replication that determines reprogramming competency. Transcription factor overexpression forces most cells into states that are refractory to reprogramming and are characterized by either hypertranscription with little cell division, or hyperproliferation with low transcription. We identify genetic and chemical factors that dramatically increase the number of cells capable of both hypertranscription and hyperproliferation. Hypertranscribing, hyperproliferating cells reprogram at 100-fold higher, near-deterministic rates. We demonstrate that elevated topoisomerase expression endows cells with privileged reprogramming capacity, suggesting that biophysical constraints limit cellular reprogramming to rare events.

scholarly journals Rootstock Effects on Growth, Cell Number, and Cell Size of `Gala' Apples

2004 ◽  
Vol 129 (1) ◽  
pp. 37-41 ◽  
Author(s):  
Yahya K. Al-Hinai ◽  
Teryl R. Roper
Keyword(s):  
Cell Division ◽  
Cell Size ◽  
Agricultural Research ◽  
Fruit Size ◽  
Cell Number ◽  
Fruit Growth ◽  
Research Station ◽  
Full Bloom ◽  
Final Size ◽  
Load Effects

The effects of rootstock on growth of fruit cell number and size of `Gala' apple trees (Malus domestica Borkh) were investigated over three consecutive seasons (2000-02) growing on Malling 26 (M.26), Ottawa-3, Pajam-1, and Vineland (V)-605 rootstocks at the Peninsular Agricultural Research Station near Sturgeon Bay, WI. Fruit growth as a function of cell division and expansion was monitored from full bloom until harvest using scanning electron microscopy (SEM). Cell count and cell size measurements showed that rootstock had no affect on fruit growth and final size even when crop load effects were removed. Cell division ceased about 5 to 6 weeks after full bloom (WAFB) followed by cell expansion. Fruit size was positively correlated (r2 = 0.85) with cell size, suggesting that differences in fruit size were primarily a result of changes in cell size rather than cell number or intercellular space (IS).

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