Abstract 17379: Relationship Between Myocyte Branching and Location Within Myocardial Sheetlet

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Alexander J Wilson ◽  
Gregory B Sands ◽  
Daniel B Ennis
Keyword(s):  
Cell Layer ◽  
Lower Surface ◽  
Left Ventricular ◽  
Branch Points ◽  
Topological Constraint ◽  
Functional Roles ◽  
Topological Constraints ◽  
Cell Layers ◽  
Confocal Images ◽  
Number Of Branches

Introduction: Cardiomyocytes form a continuously branching syncytium that also form sheetlets four to six cells thick. Myocytes and sheetlets have essential structural and functional roles, but descriptions of their complex branching structure are limited. Herein, we characterize the branching structure of cardiomyocytes within a myocardial sheetlet segment. Hypothesis: Due to topological constraints, cardiomyocytes on the sheetlet surfaces branch within the fiber-sheetlet plane more than myocytes on the interior of the sheetlet. Methods: Rodent myocardium was stained for collagen and the left ventricular free wall was imaged using extended volume confocal microscopy (0.4 μm 3 voxel size), a and sheetlet portion segmented (146 х 214 х 339 μm 3 , approx. 5 by 10 by 3 cells). The centerline of each myocyte was tracked, with branch-points identified where the cell bodies of adjacent cardiomyocytes merge. This produced a connected network (Figure) with five cell-layers along the normal axis: lower surface, lower interior, middle interior, upper interior, and upper surface. Results: The cardiomyocyte branching frequency varied between cell-layers (Figure); the sheetlet-surface cell-layers branched within their own cell-layer more frequently than myocytes in the sheetlet interior (0.28 vs 0.11 branches per 100 μm). Cardiomyocytes on the sheetlet surface also branched less frequently with cardiomyocytes of a different cell-layer, compared with cardiomyocytes in the sheetlet interior (0.31 vs 0.67 branches per 100 μm). Cardiomyocytes in the middle interior cell-layer had the highest number of branches between cell-layers (0.86 per 100 μm), and the lowest number of branches within their own cell-layer (0.03 per 100 μm). Conclusion: Analysis of confocal images revealed differences in cardiomyocyte branching between cell-layers of a sheetlet segment, and confirmed that sheetlet boundaries provide a topological constraint for cardiomyocyte branching.

scholarly journals Induction of myocardial infarcts of a predictable size and location by branch pattern probability-assisted coronary ligation in C57BL/6 mice

2004 ◽  
Vol 286 (3) ◽  
pp. H1201-H1207 ◽  
Author(s):  
Dongchoon Ahn ◽  
Linda Cheng ◽  
Chanil Moon ◽  
Harold Spurgeon ◽  
Edward G. Lakatta ◽  
...  
Keyword(s):  
Heart Disease ◽  
Coronary Artery ◽  
Left Coronary Artery ◽  
Left Ventricular ◽  
Myocardial Infarctions ◽  
Branch Points ◽  
Left Main ◽  
Uniform Size ◽  
Disease Research ◽  
Coronary Ligation

The ability to create experimental myocardial infarctions of reproducible size and location is tantamount to progress in multiple facets of ischemic heart disease research. Branches of the mouse left main descending coronary artery penetrate the myocardium close to their origin and require “blind” ligation. Our objective was to develop a technique for ligation of nonvisible coronary artery branches to permit the reliable creation of infarcts of uniformly small size and location. From latex castings of the left coronary artery of C57BL/6J mice ( n = 53), we calculated the highest probability for the location of branch points of two of three left ventricular (LV) branches distal to the origin of the left main descending artery. On the basis of these anatomic probabilities, we blindly ligated two areas that were likely to be locations of these nonvisible LV branches. We were successful in producing two types of small transmural myocardial infarctions (16.04 ± 3.64 and 4.68 ± 1.47% of the LV) in 57% of attempts. Thus our branch pattern probability-assisted method permits routine creation of small infarcts of uniform size in the mouse.

Regulation of cell proliferation patterns by homeotic genes during Arabidopsis floral development

Development ◽  
2000 ◽  
Vol 127 (6) ◽  
pp. 1267-1276 ◽  
Author(s):  
P.D. Jenik ◽  
V.F. Irish
Keyword(s):  
Cell Proliferation ◽  
Apical Meristem ◽  
Floral Development ◽  
Developmental Process ◽  
Cell Layer ◽  
Homeotic Genes ◽  
Transmitting Tract ◽  
Organ Identity ◽  
Element System ◽  
Cell Layers

The shoot apical meristem of Arabidopsis thaliana consists of three cell layers that proliferate to give rise to the aerial organs of the plant. By labeling cells in each layer using an Ac-based transposable element system, we mapped their contributions to the floral organs, as well as determined the degree of plasticity in this developmental process. We found that each cell layer proliferates to give rise to predictable derivatives: the L1 contributes to the epidermis, the stigma, part of the transmitting tract and the integument of the ovules, while the L2 and L3 contribute, to different degrees, to the mesophyll and other internal tissues. In order to test the roles of the floral homeotic genes in regulating these patterns of cell proliferation, we carried out similar clonal analyses in apetala3-3 and agamous-1 mutant plants. Our results suggest that cell division patterns are regulated differently at different stages of floral development. In early floral stages, the pattern of cell divisions is dependent on position in the floral meristem, and not on future organ identity. Later, during organogenesis, the layer contributions to the organs are controlled by the homeotic genes. We also show that AGAMOUS is required to maintain the layered structure of the meristem prior to organ initiation, as well as having a non-autonomous role in the regulation of the layer contributions to the petals.

Non-cell-autonomous function of the Antirrhinum floral homeotic proteins DEFICIENS and GLOBOSA is exerted by their polar cell-to-cell trafficking

Development ◽  
1996 ◽  
Vol 122 (11) ◽  
pp. 3433-3441 ◽  
Author(s):  
M.C. Perbal ◽  
G. Haughn ◽  
H. Saedler ◽  
Z. Schwarz-Sommer
Keyword(s):  
Cell Layer ◽  
Epidermal Cells ◽  
Molecular Techniques ◽  
Cell Trafficking ◽  
Mads Box ◽  
Organ Identity ◽  
Cell Layers ◽  
Periclinal Chimeras ◽  
The Difference ◽  
Cell Autonomy

In Antirrhinum majus, petal and stamen organ identity is controlled by two MADS-box transcription factors, DEFICIENS and GLOBOSA. Mutations in either of these genes result in the replacement of petals by sepaloid organs and stamens by carpelloid organs. Somatically stable def and glo periclinal chimeras, generated by transposon excision events, were used to study the non-cell-autonomous functions of these two MADS-box proteins. Two morphologically distinct types of chimeras were analysed using genetic, morphological and molecular techniques. Restoration of DEF expression in the L1 cell layer results in the reestablishment of DEF and GLO functions in L1-derived cells only; inner layer cells retain their mutant sepaloid features. Nevertheless, this activity is sufficient to allow the expansion of petal lobes, highlighting the role of DEF in the stimulation of cell proliferation and/or cell shape and elongation when expressed in the L1 layer. Establishment of DEF or GLO expression in L2 and L3 cell layers is accompanied by the recovery of petaloid identity of the epidermal cells but it is insufficient to allow petal lobe expansion. We show by in situ immunolocalisation that the non-cell-autonomy is due to direct trafficking of DEF and GLO proteins from the inner layer to the epidermal cells. At least for DEF, this movement appears to be polar since DEF acts cell-autonomously when expressed in the L1 cell layer. Furthermore, the petaloid revertant sectors observed on second whorl mutant organs and the mutant margins of petals of L2L3 chimeras suggest that DEF and GLO intradermal movement is limited. This restriction may reflect the difference in the regulation of primary plasmodesmata connecting cells from the same layer and secondary plasmodesmata connecting cells from different layers. We propose that control of intradermal trafficking of DEF and GLO could play a role in maintaining of the boundaries of their expression domains.

Phi Thickenings in Fossil Seed Plants from Antarctica

IAWA Journal ◽  
1987 ◽  
Vol 8 (3) ◽  
pp. 191-201 ◽  
Author(s):  
Michael A. Millay ◽  
Thomas N. Taylor ◽  
Edith L. Taylor
Keyword(s):  
Middle Triassic ◽  
Cell Layer ◽  
Vascular Cambium ◽  
Secondary Development ◽  
Water Regulation ◽  
Secondary Phloem ◽  
Primary Xylem ◽  
Sieve Cells ◽  
Ray Parenchyma ◽  
Cell Layers

Primary anatomy and secondary development is described for two root types from the Fremouw Peak locality (Transantarctic Mts, Antarctica) of early to middle Triassic age. Roots of Antarcticycas have a bilayered cortex with thick surface cuticle, diarch xylem, and a clearIy defined endodermis surrounded by a single cell layer possessing phi thickenings. Secondary development begins with phellern and phelloderm production from the out er primary phloem position, and is followed bya bifacial vascular cambium next to the primary xylem that pro duces sieve cells and ray parenchyma to the outside. Young roots of Antarcticoxylon are similar to those of Antarcticycas, but may possess 2-3 cell layers with phi thickenings. Secondary development from a bifacial vascular cambium produces alternating bands of sieve cells and phloem parenchyma cells in the secondary phloem and wood with uniseriate rays and scattered axial parenchyma. The presence of phi thickenings and an epidermal cutieie in both roots suggests environmental stress related to water regulation. The occurrence of phi thickenings in the roots of some conifers, angiosperms, a fossil cycad and a probable seed fern suggests this character is of ecological rather than phylogenetic significance.

Polarized properties of thyroid cells: A study with cultured porcine cells

1987 ◽  
Vol 116 (1_Suppl) ◽  
pp. S220-S224 ◽  
Author(s):  
Jean Mauchamp ◽  
Odile Chabaud ◽  
Marianne Chambard ◽  
Corinne Gerard ◽  
Claude Penel ◽  
...  
Keyword(s):  
Cell Layer ◽  
Culture Conditions ◽  
Thyroid Cell ◽  
Apical Surface ◽  
Cell Plasma Membrane ◽  
Basal Surface ◽  
Thyroid Cells ◽  
Cell Plasma ◽  
Apical Compartment ◽  
Cell Layers

Abstract. In primary culture porcine cells form polarized cell layers. We have designed culture conditions in which we can have access to only one side of the cell layer, either the apical or the basal surface. In addition, using culture chambers with permeable bottom we can have access to either side of the cell layer which separates two compartments. Using these organized systems we have shown that the iodide concentrating mechanism and the TSH-reseptor adenyl cyclase complex are localized on the basolateral domain of the thyroid cell plasma membrane. We also demonstrated the existence on the apical surface of an amiloride sensitive sodium uptake. Finally we observed that about 10% of newly synthesized thyroglobulin appears to be secreted directly into the basal compartment, 90% being secreted in the apical compartment.

scholarly journals Loss of the nodule-specific cysteine rich peptide, NCR169, abolishes symbiotic nitrogen fixation in the Medicago truncatula dnf7 mutant

2015 ◽  
Vol 112 (49) ◽  
pp. 15232-15237 ◽  
Author(s):  
Beatrix Horváth ◽  
Ágota Domonkos ◽  
Attila Kereszt ◽  
Attila Szűcs ◽  
Edit Ábrahám ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Medicago Truncatula ◽  
Symbiotic Nitrogen Fixation ◽  
Root Nodules ◽  
Nitrogen Fixing ◽  
In Planta ◽  
Functional Roles ◽  
Absolute Requirement ◽  
Cell Layers

Host compatible rhizobia induce the formation of legume root nodules, symbiotic organs within which intracellular bacteria are present in plant-derived membrane compartments termed symbiosomes. In Medicago truncatula nodules, the Sinorhizobium microsymbionts undergo an irreversible differentiation process leading to the development of elongated polyploid noncultivable nitrogen fixing bacteroids that convert atmospheric dinitrogen into ammonia. This terminal differentiation is directed by the host plant and involves hundreds of nodule specific cysteine-rich peptides (NCRs). Except for certain in vitro activities of cationic peptides, the functional roles of individual NCR peptides in planta are not known. In this study, we demonstrate that the inability of M. truncatula dnf7 mutants to fix nitrogen is due to inactivation of a single NCR peptide, NCR169. In the absence of NCR169, bacterial differentiation was impaired and was associated with early senescence of the symbiotic cells. Introduction of the NCR169 gene into the dnf7-2/NCR169 deletion mutant restored symbiotic nitrogen fixation. Replacement of any of the cysteine residues in the NCR169 peptide with serine rendered it incapable of complementation, demonstrating an absolute requirement for all cysteines in planta. NCR169 was induced in the cell layers in which bacteroid elongation was most pronounced, and high expression persisted throughout the nitrogen-fixing nodule zone. Our results provide evidence for an essential role of NCR169 in the differentiation and persistence of nitrogen fixing bacteroids in M. truncatula.

Atmung, Glykolyse und Überlebensdauer von Monolayer-Gewebekultur-Zellen nach Verbringen in Suspension

1964 ◽  
Vol 19 (10) ◽  
pp. 916-922 ◽  
Author(s):  
Th. Luthardt ◽  
W. Fischer
Keyword(s):  
Respiratory Rate ◽  
Culture Medium ◽  
Cell Layer ◽  
Intact Cell ◽  
Aerobic Glycolysis ◽  
Cell Suspensions ◽  
Monolayer Cultures ◽  
Cell Layers ◽  
Glycolytic Rate ◽  
Technical Simplification

The suspension of cells from monolayer cultures for manometric measurements provides a technical simplification and has therefore become a frequent manipulation in such studies. In the experiments described respiration, aerobic glycolysis and lifespan of the cells after their transition from the intact cell-layer to the suspension were studied.The glycolytic rate remains unchanged in the suspension, if the culture medium was not changed. Cultures without glycolysis do not glycolyse in the suspension either.The respiratory rate is independant of glycolysis. Under the conditions used it is somewhat accelerated in cell-suspensions. The lifespan of the cells is considerably reduced. After 5 to 10 hrs. a distinct loss of respiratory rate can be noted, which does not take place in cell-layers.The reproducability of the results in cell suspensions is not sufficient.Considered in the light of these findings cell suspensions of monolayer cultures seem only conditionally suitable for manometric measurements and should only be used when measurements with intact cell-layers are not possible.

The Turnover of Collagen in Fibroblast Cultures

1973 ◽  
Vol 12 (1) ◽  
pp. 217-234
Author(s):  
J. STEINBERG
Keyword(s):  
Stationary Phase ◽  
Growth Medium ◽  
Specific Activity ◽  
Cell Layer ◽  
Gel Filtration ◽  
Mouse Fibroblast ◽  
Growth Media ◽  
Precursor Pool ◽  
Fibroblast Cultures ◽  
Cell Layers

Collagen turnover was studied in mouse fibroblast cultures (3T6) by radioactive labelling and compartmental analyses. The incorporation of [14C]proline into protein during continuous labelling rapidly reached a maximum value which was directly proportional to the medium specific activity. Radioactivity appeared more slowly in hydroxyproline, and gradually accumulated as cultures became enriched in collagen and its breakdown products. In relation to total new protein synthesis, the proportional synthesis of collagen, as measured by the formation of [14C]hydroxyproline, was less in logarithmically growing than in stationary-phase cultures, and little was deposited in the cell layer. Newly synthesized hydroxyproline was consistently present in all growth media. In stationary-phase cultures, media contained as much as 60% of the total [14C]hydroxyproline in a form soluble in 0.5 M perchloric acid. Gel filtration chromatography confirmed that this was predominantly free hydroxyproline, only 30% appearing in small peptides whose degree of hydroxylation suggested their origin from larger collagen molecules. This acid-soluble compartment was taken as a convenient index of collagenolysis, which proved to be significant in both growth states, but was proportionately more important throughout logarithmic growth. Reincubation of prelabelled cultures in fresh medium containing an excess of non-radioactive proline (‘chase’ medium) was followed by the degradative loss of labelled cell layer protein. The released radioactivity could be quantitatively recovered in the growth medium for periods up to 6 days; the rate of its appearance was little influenced by the frequency of feeding. Despite extensive dilution of the proline precursor-pool specific activity, synthesis of [14C]hydroxyproline continued in all chase cultures. The increment appeared largely as collagen breakdown products in the growth medium, and probably arose from 2 principal sources: (1) recently deposited collagen, and (2) the hydroxylation of peptidyl-[14C]proline residues in protocollagen. The balance between these contributions seemed to be dependent upon the extent to which ‘ageing’ of the cell layer collagen had occurred prior to initiating the chase. Radioactive hydroxyproline was rapidly lost from briefly prelabelled cell layers, but was well retained in a macromolecular form when the initial labelling period was sufficiently prolonged. It is proposed that the endogenous collagen-degradative apparatus attacks both young collagen and its polypeptide precursor, but that as the lability of the former substrate rapidly declines, enzyme activity continues to operate on protocollagen to yield [14C]hydroxyproline-containing breakdown products which gradually diminish as the latter substrate pool is exhausted.

scholarly journals The instability of gyrotactically trapped cell layers

2019 ◽  
Vol 868 ◽  
Author(s):  
Smitha Maretvadakethope ◽  
Eric E. Keaveny ◽  
Yongyun Hwang
Keyword(s):  
Cell Layer ◽  
Cell Concentration ◽  
Gravitational Instability ◽  
Plane Channel ◽  
Thin Layers ◽  
Relevant Parameter ◽  
Potential Mechanism ◽  
Cell Layers ◽  
Maximum Cell ◽  
Maximum Cell Concentration

Several metres below the coastal ocean surface there are areas of high ecological activity that contain thin layers of concentrated motile phytoplankton. Gyrotactic trapping has been proposed as a potential mechanism for layer formation of bottom-heavy swimming algae cells, especially in flows where the vorticity varies linearly with depth (Durham et al., Science, vol. 323(5917), 2009, pp. 1067–1070). Using a continuum model for dilute microswimmer suspensions, we report that an instability of a gyrotactically trapped cell layer can arise in a pressure-driven plane channel flow. The linear stability analysis reveals that the equilibrium cell-layer solution is hydrodynamically unstable due to negative microswimmer buoyancy (i.e. a gravitational instability) over a range of biologically relevant parameter values. The critical cell concentration for this instability is found to be $N_{c}\simeq 10^{4}~\text{cells}~\text{cm}^{-3}$, a value comparable to the typical maximum cell concentration observed in thin layers. This result indicates that the instability may be a potential mechanism for limiting the layer’s maximum cell concentration, especially in regions where turbulence is weak, and motivates the study of its nonlinear evolution, perhaps, in the presence of turbulence.

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