Cell movements, cell division and growth in the hydroid Clytia johnstoni

Development ◽  
1964 ◽  
Vol 12 (3) ◽  
pp. 517-538
Author(s):  
L. J. Hale
Keyword(s):  
Cell Division ◽  
Sea Water ◽  
Normal Growth ◽  
Cell Movements ◽  
Extensive Cell ◽  
Glass Plates ◽  
Living Material

Although there have been a great many studies on the morphogenesis of hydroids, the emphasis has been largely with regeneration and with grafting experiments, and mostly using the hydras, Cordylophora and Tubularia as material. Some of these investigations have made reference to cell movements and cell division, but none have considered both these fundamental morphogenetic processes and their interrelationships in a single hydroid. In this paper the occurrence of cell movements and cell division in normal growth and in the regeneration of Clytia johnstoni is considered. The investigation has revealed extensive cell movements, not only in the coenosarc but also passively by the hydroplasm. Cell division is almost exclusively confined to the ectoderm and rarely occurs in the endoderm. Material and Methods The animal was cultured in the laboratory on glass plates in running sea-water (Hale, 1957, 1960). All the observations (except those on cell division) were made on the living material kept at 18°C. (± 1).

Cell proliferation and morphological patterns in the hydroids Tubularia and Hydractinia

Development ◽  
1967 ◽  
Vol 17 (3) ◽  
pp. 607-616
Author(s):  
Richard D. Campbell
Keyword(s):  
Cell Proliferation ◽  
Cell Division ◽  
Normal Growth ◽  
Tissue Growth ◽  
Body Form ◽  
Tissue Form ◽  
Morphological Patterns

Morphogenesis has been extensively studied in many hydroids, both during normal growth (Kühn, 1914; Berrill, 1961) and during regeneration (Tardent, 1963). Less is known about the patterns of cell proliferation underlying changes in tissue form. In several cases where cell division has been studied, surprisingly little direct correlation was found between areas of apparent morphological growth and patterns of cell proliferation (Overton, 1963; Crowell, Wyttenbach & Suddith, 1965; Shostak, Patel & Burnett, 1965; Wyttenbach, 1965; Campbell, 1967a, b). To explore further the relations between tissue growth and body form, I have examined histologically hydroids of two genera, Tubularia and Hydractinia, each of which has morphological pecularities. Tubularia possesses two whorls of tentacles and one whorl of gonophores, and thus has as many distinct hydranth regions as any hydroid. In the Hydractinia colony, four morphologically distinct polyp types are present.

scholarly journals Planar cell movements and oriented cell division during early primitive streak formation in the mammalian embryo

2011 ◽  
Vol 240 (8) ◽  
pp. 1905-1916 ◽  
Author(s):  
Viktoriya Halacheva ◽  
Mathias Fuchs ◽  
Jürgen Dönitz ◽  
Tobias Reupke ◽  
Bernd Püschel ◽  
...  
Keyword(s):  
Cell Division ◽  
Primitive Streak ◽  
Mammalian Embryo ◽  
Cell Movements ◽  
Oriented Cell Division

The role of F-cadherin in localizing cells during neural tube formation in Xenopus embryos

Development ◽  
1998 ◽  
Vol 125 (2) ◽  
pp. 301-312 ◽  
Author(s):  
A. Espeseth ◽  
G. Marnellos ◽  
C. Kintner
Keyword(s):  
Cell Adhesion ◽  
Neural Tube ◽  
Cell Adhesion Molecule ◽  
Ectopic Expression ◽  
Tube Formation ◽  
Cell Movements ◽  
Xenopus Embryos ◽  
Extensive Cell ◽  
Neural Tube Formation

The cell adhesion molecule F-cadherin is expressed in Xenopus embryos at boundaries that subdivide the neural tube into different regions, including one, the sulcus limitans, which partitions the caudal neural tube into a dorsal and ventral half (alar and basal plate, respectively). Here we examine the role of F-cadherin in positioning cells along the caudal neuraxis during neurulation. First, we show that ectopic expression of F-cadherin restricts passive cell mixing within the ectodermal epithelium. Second, we show that F-cadherin is first expressed at the sulcus limitans prior to the extensive cell movements that accompany neural tube formation, suggesting that it might serve to position cells at the sulcus limitans by counteracting their tendency to disperse during neurulation. We test this idea using an assay that measures changes in cell movements during neurulation in response to differential cell adhesion. Using this assay, we show that cells expressing F-cadherin localize preferentially to the sulcus limitans, but still disperse when located away from the sulcus limitans. In addition, inhibiting cadherin function prevents cells from localizing precisely at the sulcus limitans. These results indicate that positioning of cells at the sulcus limitans is mediated in part by the differential expression of F-cadherin.

scholarly journals FURTHER STUDIES ON CELL DIVISION WITHOUT MITOTIC APPARATUS IN SEA URCHIN EGGS

1965 ◽  
Vol 25 (1) ◽  
pp. 161-167 ◽  
Author(s):  
Y. Hiramoto
Keyword(s):  
Cell Division ◽  
Sea Urchin ◽  
Sea Water ◽  
Sucrose Solution ◽  
Mitotic Apparatus ◽  
Sea Urchin Eggs ◽  
Paraffin Oil

A large quantity of paraffin oil, sucrose solution, or sea water was injected into the eggs of the heart urchin Clypeaster japonicus shortly before the onset of the first cleavage. The injected oil became spherical, pushing the mitotic apparatus aside. The sucrose solution mixed with the protoplasm and caused disintegration of the mitotic apparatus, and the sea water formed a vacuole at the center of the cell. In all these cases, cleavage may take place almost normally in spite of the absence of the mitotic apparatus or its displacement within the cell. In some eggs, furrowing may take place when more than fifty per cent of the endoplasm has been replaced with sea water before onset of cleavage.

An Investigation of Detritus in Southampton Water

1967 ◽  
Vol 47 (3) ◽  
pp. 523-532 ◽  
Author(s):  
Ann Trevallion
Keyword(s):  
Seasonal Variation ◽  
Primary Productivity ◽  
Sea Water ◽  
Superficial Layer ◽  
Organic Content ◽  
Southampton Water ◽  
Carbon And Nitrogen ◽  
Living Material ◽  
Marine Productivity ◽  
Carbon And Nitrogen Content

An apparatus is described which has been used at three sites in Southampton Water for the continuous collection of sedimenting detritus. The collected detritus was removed at monthly intervals for measurement, and for analysis of the organic carbon and nitrogen content.The total quantities of dry detritus varied from 4 mg/cm2/month to 980 mg/cm2/month, and because of the variable collection of resuspended bottom material show no clear seasonal variation. The carbon content was 0.1–7.3% of the total and nitrogen varied from 0.02 to 0.62%. The organic content did show some seasonal variation which tended to follow changes in the abundance of phytoplankton.The amounts of total detritus collected and the organic content are high compared with some other areas and this is thought to be due partly to the high primary productivity of the area and partly to the complex water movements in the estuary.IntroductionThe importance of detritus in suspension in the sea and as a superficial layer on the sediment is well recognized. The quantity of detritus in sea water has been measured (Armstrong & Atkins, 1950; Fox, Isaacs & Corcoran, 1952; Krey, 1950, 1961a, b, 1964; Krey, Banse & Hagmeier, 1957; Hagmeier, 1962) and usually exceeds the amount of living material in suspension by at least a factor of ten. Study of deposited detritus has mainly involved measurement of the amount of organic matter in bottom sediments (Waksman, 1933; Anderson, 1939; Southward, 1952; Morgans, 1956; Sanders, 1960).In studies of marine productivity it is important to know not only the amount of detritus present in the water column, but also its composition and rate of sedimentation.

scholarly journals Mitogen-independent cell cycle progression in B lymphocytes

2019 ◽  
Author(s):  
Amit Singh ◽  
Matthew H. Spitzer ◽  
Jaimy P. Joy ◽  
Mary Kaileh ◽  
Xiang Qiu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Cell Division ◽  
B Lymphocytes ◽  
Cell Cycle Progression ◽  
Adaptive Immune System ◽  
G1 Phase ◽  
Cycle Progression ◽  
Extensive Cell Death ◽  
Extensive Cell

AbstractThe canonical view of the cell cycle posits that G1 progression signals are essential after each mitosis to enter S phase. A subset of tumor cells bypass this requirement and progress to the next cell division in the absence of continued signaling. B and T lymphocytes of the adaptive immune system undergo a proliferative burst, termed clonal expansion, to generate pools of antigen specific cells for effective immunity. There is evidence that rules for lymphocyte cell division digress from the canonical model. Here we show that B lymphocytes sustain several rounds of mitogen-independent cell division following the first mitosis. Such division is driven by unique characteristics of the post mitotic G1 phase and limited by extensive cell death that can be circumvented by appropriate anti-apoptotic signals. An essential component for continued cell division is Birc5 (survivin), a protein associated with chromosome segregation in G2/M. Our observation provides direct evidence for Pardee’s hypothesis that retention of features of G2M in post-mitotic cells could trigger further cell cycle progression. The partially active G1 phase and propensity for apoptosis that is inherited after each division may permit rapid burst of proliferation and cell death that are hallmarks of immune responses.

scholarly journals A molecular framework for control of oriented cell division in the Arabidopsis embryo

2021 ◽  
Author(s):  
Prasad Vaddepalli ◽  
Thijs de Zeeuw ◽  
Sören Strauss ◽  
Katharina Bürstenbinder ◽  
Che-Yang Liao ◽  
...  
Keyword(s):  
Cell Division ◽  
Actin Cytoskeleton ◽  
Plant Development ◽  
Transcriptome Profiling ◽  
Cell Geometry ◽  
Auxin Response ◽  
Division Plane ◽  
Asymmetric Divisions ◽  
Extensive Cell ◽  
Minimal Surface Area

SummaryPremitotic control of cell division orientation is critical for plant development, as cell walls prevent extensive cell remodelling or migration. Whilst many divisions are proliferative and add cells to existing tissues, some divisions are formative, and generate new tissue layers or growth axes. Such formative divisions are often asymmetric in nature, producing daughters with different fates. We have previously shown that in the Arabidopsis thaliana embryo, developmental asymmetry is correlated with geometric asymmetry, creating daughter cells of unequal volume. Such divisions are generated by division planes that deviate from a default “minimal surface area” rule. Inhibition of auxin response leads to reversal to this default, yet the mechanisms underlying division plane choice in the embryo have been unclear. Here we show that auxin-dependent division plane control involves alterations in cell geometry, but not in cell polarity or nuclear position. Through transcriptome profiling, we find that auxin regulates genes controlling cell wall and cytoskeleton properties. We confirm the involvement of microtubule (MT)-binding proteins in embryo division control. Topology of both MT and Actin cytoskeleton depend on auxin response, and genetically controlled MT or Actin depolymerization in embryos leads to disruption of asymmetric divisions, including reversion to the default. Our work shows how auxin-dependent control of MT- and Actin cytoskeleton properties interacts with cell geometry to generate asymmetric divisions during the earliest steps in plant development.

Analysis of embryonic cell division patterns using laser scanning confocal microscopy

1989 ◽  
Vol 47 ◽  
pp. 140-141
Author(s):  
Robert G. Summers ◽  
Ping-chin Cheng
Keyword(s):  
Cell Division ◽  
Confocal Microscopy ◽  
Laser Scanning ◽  
Sea Water ◽  
Sea Urchins ◽  
Laser Scanning Confocal Microscopy ◽  
Cell Number ◽  
Embryonic Cell ◽  
Mitotic Apparatus ◽  
Scanning Confocal Microscopy

As embryogenesis in the sea urchin proceeds, cell number increases and overall synchrony of cell division decreases. Beyond 16 cells, it becomes increasingly more difficult to observe individual cells or populations of cells in whole-mounted embryos because of their thickness (up to 150 μm) and superimposition of nuclei. As a consequence, the patterns of cell division (eg. its timing and synchrony within subpopulations of cells, orientation of the mitotic apparatus relative to axes of embryonic symmetry etc.) in sea urchins and other developing systems remain unclear. Confocal microscopy affords the opportunity to analyze intact embryos and to gain an understanding of the role which cell division plays in morphogenesis of the embryo.Sea urchins (Strongylocentrotus purpuratus) were obtained from Northern California and maintained in artificial sea water. Gametes were obtained and cultures of embryos were prepared in the usual fashion and synchronous cultures of embryos were reared at 15°C. Fixation and Feulgen staining were performed per Nislow and Morill.

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