scholarly journals Commitment during nematocyte differentiation in Hydra

1981 ◽  
Vol 48 (1) ◽  
pp. 207-222 ◽  
Author(s):  
T. Fujisawa ◽  
C.N. David
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Distal Region ◽  
The Body ◽  
Distal Half ◽  
Proximal Half ◽  
Dissociated Cells ◽  
Time Required ◽  
Kinetics Of ◽  
Body Column

Nematocytes in Hydra differentiate from interstitial stem cells. Desmonemes differentiate mainly in the distal half of the body column while stenoteles differentiate predominantly in the proximal half. This difference was used to determine the timing of nematocyte-type commitment in the differentiation pathway. Cells were transferred from distal or proximal regions to all positions in the body column to test when the proportion of stenotele and desmoneme differentiation changed to reflect the new environment. In the first experiment, the distal region of the body column was isolated and permitted to regenerate a whole Hydra. In the second experiment, dissociated cells from distal or proximal regions were transplanted into regenerating aggregates of Hydra tissue. Both experiments effectively transferred cells from distal or proximal positions to positions throughout the body column. By comparing the kinetics of stenotele and differentiation with the time required for distal or proximal cells to differentiate stenoteles and desmonemes in accord with their new environment, it was possible to conclude that stenotele and desmoneme commitment occurs during the terminal cell cycle prior to nematocyte differentiation and not at the stem cell. Additional experiments indicated that the number of rounds of cell division preceding differentiation is fixed at the time stem cells enter the nematocyte pathway.

scholarly journals Loss of neurogenesis in Hydra leads to compensatory regulation of neurogenic and neurotransmission genes in epithelial cells

2016 ◽  
Vol 371 (1685) ◽  
pp. 20150040 ◽  
Author(s):  
Y. Wenger ◽  
W. Buzgariu ◽  
B. Galliot
Keyword(s):  
Stem Cells ◽  
Nervous System ◽  
G Protein Coupled Receptors ◽  
The Body ◽  
Neurogenic Genes ◽  
Cell Type Specific ◽  
The Impact ◽  
G Protein Coupled ◽  
Body Column ◽  
Compensatory Regulation

Hydra continuously differentiates a sophisticated nervous system made of mechanosensory cells (nematocytes) and sensory–motor and ganglionic neurons from interstitial stem cells. However, this dynamic adult neurogenesis is dispensable for morphogenesis. Indeed animals depleted of their interstitial stem cells and interstitial progenitors lose their active behaviours but maintain their developmental fitness, and regenerate and bud when force-fed. To characterize the impact of the loss of neurogenesis in Hydra , we first performed transcriptomic profiling at five positions along the body axis. We found neurogenic genes predominantly expressed along the central body column, which contains stem cells and progenitors, and neurotransmission genes predominantly expressed at the extremities, where the nervous system is dense. Next, we performed transcriptomics on animals depleted of their interstitial cells by hydroxyurea, colchicine or heat-shock treatment. By crossing these results with cell-type-specific transcriptomics, we identified epithelial genes up-regulated upon loss of neurogenesis: transcription factors ( Dlx , Dlx1 , DMBX1/Manacle , Ets1 , Gli3 , KLF11 , LMX1A , ZNF436 , Shox1 ), epitheliopeptides ( Arminins , PW peptide ), neurosignalling components ( CAMK1D , DDCl2 , Inx1 ), ligand-ion channel receptors ( CHRNA1 , NaC7 ), G-Protein Coupled Receptors and FMRFRL. Hence epitheliomuscular cells seemingly enhance their sensing ability when neurogenesis is compromised. This unsuspected plasticity might reflect the extended multifunctionality of epithelial-like cells in early eumetazoan evolution.

RADIATION-PROTECTIVE AGENT AND ANTI-AGING AGENTS: RANDOM AND PREDICTABLE MATCHES

2020 ◽  
pp. 646-656
Author(s):  
В. Н. Быков ◽  
А. Н. Гребенюк ◽  
И. Б. Ушаков
Keyword(s):  
Cell Cycle ◽  
Ionizing Radiation ◽  
Antioxidant Activities ◽  
Early Stage ◽  
Cellular Level ◽  
The Body ◽  
Protective Agent ◽  
Age Related ◽  
Short Term Exposure ◽  
Time Required

Радиопротекторные и геропротекторные свойства соединений нередко сочетаются, что может быть обусловлено общими механизмами действия: антиоксидантной активностью, повышением устойчивости к клеточному стрессу, ускорением репарации ДНК, предотвращением хронических воспалительных заболеваний и канцерогенеза. В данной работе приведен детальный анализ молекулярнобиологических механизмов действия препаратов, обладающих радиопротекторными и/или геропротекторными свойствами. Описаны общие звенья развития старения и патогенеза заболеваний, связанных с облучением, включающие активацию свободнорадикальных реакций, нарушение регуляции репарации ДНК, клеточного цикла и апоптоза. С одной стороны, на фоне остановки клеточного цикла и блокады апоптоза увеличивается время для репарации ДНК. С другой стороны, активация апоптоза измененных клеток рассматривается как один из механизмов замедления процессов старения и предотвращения отдаленных эффектов воздействия ионизирующих излучений. Выделено две основных группы радиозащитных препаратов: 1) обладающие антиапоптозным свойством и способствующие повышению выживаемости в ранние сроки после после облучения в высокой дозе; 2) способствующие элиминированию поврежденных клеток (сенолитики) и наиболее эффективные при длительном низкодозовом воздействии радиации или фракционированном облучении. Геропротекторная активность описана для препаратов второй группы, к которым относятся мелатонин, метформин, рапамицин и природные полифенольные соединения. Radiation-protective and anti-aging properties are often combined. Combination of this properties is linked to the common mechanisms of action such as direct and indirect antioxidant activities, inhibition of free radicals formation, increase resistance to stress impacts at the cellular level, acceleration of DNA reparation, prevention of chronic diseases linked to abnormalities in regeneration processes, activation of immune inflammatory processes and carcinogenesis. Regulation of cell cycle and apoptosis can often be considered as an implementing driver of radiation-protective and anti-aging activities. On the one hand, against the background of stopping the cell cycle and blockade of apoptosis increases the time required to repair the defects of a DNA. Antiapoptotic effects enhances survival chances at the early stage after irradiation in a particular range of doses. On the other hand, activation of apoptosis of altered cells can be seen as one of the mechanisms to delay aging processes and prevention of isolated effects of exposure to ionizing radiation. Formation of radiation-induced and age-related alterations are characterized by multiple factors and a variety of manifestations. Nevertheless, similarity of individual links of the pathogenesis of disease related to radiation exposure and aging of the body is striking. It could be stated that radiation-protective property defines an increase in life expectancy by short-term exposure in sub-lethal and lethal doses. However anti-aging activities prevent the development of remote effects of ionizing radiation by prolonged low doses or fractionated exposure to radiation.

Developmental sequence of the syncarpous gynoecium of Sarracenia purpurea (Sarraceniaceae) with flattened and broadened carpels and an umbrella-shaped style

Botany ◽  
2020 ◽  
Vol 98 (8) ◽  
pp. 401-423
Author(s):  
Jinyan Guo ◽  
Chad T. Halson
Keyword(s):  
Temporal Pattern ◽  
Distal Region ◽  
Sarracenia Purpurea ◽  
Developmental Sequence ◽  
Abaxial Surface ◽  
Distal Half ◽  
Proximal Half ◽  
Secretory Glands ◽  
Postgenital Fusion ◽  
Marginal Meristem

The umbrella-shaped style of Sarracenia has a flattened and broadened distal half forming an umbrella canopy, and a slender cylindrical proximal half forming an umbrella stalk. The developmental sequence that gives rise to this unique structure has never been studied in detail. Data from light microscopy and scanning electron microscopy showed that the five carpels are initiated as discrete primordia, which then undergo congenital fusion and conduplicate folding and become a pentagonal syncarpous gynoecium. The distal region of the carpel then bends abaxially and undergoes significant expansion via a marginal meristem, forming the umbrella shape. Carpel closure is achieved via postgenital fusion at both transverse and longitudinal slits. Each of the five pollen tube transmitting tracts is enclosed by the adaxial surface of the carpel, and the inner epidermis of the umbrella canopy represents the expanded abaxial surface of the carpels, whereas the outer epidermis represents the expanded distal region of the fused carpellary margins. Epidermal trichomes develop first, then secretory glands and stomata appear later at the same stage on the umbrella canopy. This study provides insights into the evolution of the umbrella-shaped style utilizing both common and specialized carpel developmental programs with a novel spatial and temporal pattern.

scholarly journals Contrasting Effects of Basic Fibroblast Growth Factor and Neurotrophin 3 on Cell Cycle Kinetics of Mouse Cortical Stem Cells

2002 ◽  
Vol 22 (15) ◽  
pp. 6610-6622 ◽  
Author(s):  
Agnès Lukaszewicz ◽  
Pierre Savatier ◽  
Véronique Cortay ◽  
Henry Kennedy ◽  
Colette Dehay
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Basic Fibroblast Growth Factor ◽  
Fibroblast Growth ◽  
Cell Cycle Kinetics ◽  
Neurotrophin 3 ◽  
Kinetics Of

scholarly journals In vivo proliferation and cell cycle kinetics of long-term self-renewing hematopoietic stem cells

1999 ◽  
Vol 96 (6) ◽  
pp. 3120-3125 ◽  
Author(s):  
S. H. Cheshier ◽  
S. J. Morrison ◽  
X. Liao ◽  
I. L. Weissman
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Cell Cycle Kinetics ◽  
Hematopoietic Stem ◽  
Kinetics Of

scholarly journals Distribution and dynamics of nematocyte populations in Hydra attenuata

1976 ◽  
Vol 21 (1) ◽  
pp. 15-34 ◽  
Author(s):  
H.R. Bode ◽  
K.M. Flick
Keyword(s):  
Transit Time ◽  
Reasonable Agreement ◽  
Data Distribution ◽  
Turnover Time ◽  
The Body ◽  
Battery Cell ◽  
Hydra Attenuata ◽  
Time Required ◽  
Body Column ◽  
Battery Cells

The distribution and dynamics of the 4 nematocyte populations of Hydra attenuata were investigated. Ninety-seven per cent of all nematocytes, including all 4 types, are mounted in the battery cells of the tentacles. The remaining 3%, including 2 types (stenoteles and holotrichous isorhizas) are mounted in the ectoderm of the body column. Eight-two per cent of all nematocytes are desmonemes; 11%, atrichous isorhizas; 5%, stenoteles; and 2%, holotrichous isorhizas. The density of each nematocyte population increases along the length of the tentacle towards the tip. The percentages of the total nematocytes per quarter of tentacle for each of the 4 quarters starting at the base is 15, 18, 25 and 42% respectively. The turnover time of the nematocyte populations in the tentacles was measured with 2 methods. First, the transit time for a carbon-marked battery cell from the base to the tip of the tentacle was measured. Secondly, the time required to replace the unlabelled nematocytes in the tentacles with [3H]proline-labelled nematocytes was measured. In both cases the time was 7–9 days. Based on these data (distribution and turnover time) a model was constructed for the dynamics of the nematocyte populations in the tentacles. The numbers of nematocytes produced dialy in the body column as predicted by the model are in reasonable agreement with the measured values.

scholarly journals Gland cells in Hydra: cell cycle kinetics and development

1986 ◽  
Vol 85 (1) ◽  
pp. 197-215
Author(s):  
T. Schmidt ◽  
C.N. David
Keyword(s):  
Cell Cycle ◽  
Nuclear Dna ◽  
The Body ◽  
Proliferating Cells ◽  
Gland Cells ◽  
A Cell ◽  
Different Populations ◽  
Mucus Cells ◽  
Dna Measurements ◽  
Body Column

The proliferative capacity of gland cells in Hydra attenuata was investigated. The results indicate that both gland cell proliferation and interstitial cell differentiation to gland cells contribute to the maintenance of the whole population. On the basis of [3H]thymidine incorporation and nuclear DNA measurements, gland cells consist of at least three different populations. One population consists of rapidly proliferating cells with a cell cycle of about 72 h. These cells are distributed throughout the body column. In the lower gastric region there is a population of non-cycling cells in G2 while in the upper gastric region there is a population of non-cycling cells in G1. About half the G1 population becomes a new antigen, SEC 1, which is typical of mucus cells.

Pattern of differentiated nerve cells in hydra is determined by precursor migration

Development ◽  
1997 ◽  
Vol 124 (2) ◽  
pp. 569-576 ◽  
Author(s):  
G. Hager ◽  
C.N. David
Keyword(s):  
Cell Cycle ◽  
Cell Differentiation ◽  
Nerve Cell ◽  
Nerve Cells ◽  
The Body ◽  
Whole Body ◽  
Continuous Growth ◽  
Body Column ◽  
Nerve Cell Differentiation

The nervous system of the fresh water polyp hydra is built up as a nerve net spread over the whole body, with higher densities in the head and the foot. In adult hydra, as a result of continuous growth, new nerve cell differentiation takes place continuously. The pattern of nerve cell differentiation and the role of nerve cell precursor migration in establishing the pattern have been observed in vivo by vitally labelling precursor cells with DiI. The results indicate that nerve cell precursors arise directly from stem cells, complete a final cell cycle and divide, giving rise to two daughter cells, which differentiate into nerve cells. A subpopulation of the nerve cell precursors are migratory for a brief interval at the onset of the terminal cell cycle, then complete the cell cycle and divide at the site of differentiation. Labelling small patches of tissue in the head, body column and peduncle/foot with DiI indicated that formation of nerve cell precursors was nearly constant at all three positions. However, at least half of the labelled precursors in the body column migrated to the head or foot before differentiating; by contrast, precursors in head and foot differentiated in situ without significant migration. This redistribution leads to a net increase of nerve cell precursors in head and foot compared to body column and thus to the higher density of nerve cells in these regions.

Ethanol alters cell cycle gene expression in human embryonic stem cells

2016 ◽  
Vol 01 (03) ◽  
pp. 201-208 ◽  
Author(s):  
Malini Krishnamoorthy ◽  
Brian Gerwe ◽  
Jamie Heimburg-Molinaro ◽  
Rachel Nash ◽  
Jagan Arumugham ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Human Embryonic Stem Cells ◽  
Embryonic Stem ◽  
Cell Cycle Gene ◽  
Cell Cycle Gene Expression

Prothrombin Evaluation as Obtained by Kinetics Studies of Antigen-Antibody Reaction in a Laser Nephelometer

1984 ◽  
Vol 52 (01) ◽  
pp. 015-018 ◽  
Author(s):  
A Girolami ◽  
A Sticchi ◽  
R Melizzi ◽  
L Saggin ◽  
G Ruzza
Keyword(s):  
Liver Cirrhosis ◽  
Cirrhotic Patient ◽  
Maximum Rate ◽  
Serum Proteins ◽  
Clotting Factors ◽  
Kinetics Studies ◽  
Maximum Value ◽  
Time Required ◽  
Antigen Antibody ◽  
Kinetics Of

SummaryLaser nephelometry is a technique which allows the evaluation of the concentration of several serum proteins and clotting factors. By means of this technique it is also possible to study the kinetics of the reaction between antigen and antibody. We studied the kinetics of the reaction between prothrombin and an antiprothrombin antiserum using several prothrombins namely: Prothrombin Padua, prothrombin Molise, which are two congenital dysprothrombinemias, cirrhotic, coumarin or normal prothrombins. Different behaviors in the kinetics of the reactions were shown even when the concentration of prothrombins was about the same in all plasma tested. These differences were analyzed by means of a computer (Apple II 48 RAM) programmed to solve four unknown equations (Rodbard’s equation). From the data so obtained one can see that when voltages at the beginning and at the end of the reaction are in all cases about the same, a clear difference in the time required to reach half the maximum value of the voltage can still be demonstrated. This parameter, which is expressed in minutes, is longer in coumarin and prothrombin Molise than in controls. On the contrary it is shorter in prothrombin Padua and has about the same value of controls in the cirrhotic patient. Moreover the time at which the maximum rate is obtained is longer in coumarin and prothrombin Molise than in controls and shorter in liver cirrhosis and prothrombin Padua. In conclusion data obtained show that coumarin prothrombin behaves in a different way from cirrhotic prothrombin and also that there is a different behaviour between the two congenital dysprothrombinemias.

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