The cell cycle and seed germination

2003 ◽  
Vol 13 (2) ◽  
pp. 113-130 ◽  
Author(s):  
Jorge M. Vázquez-Ramos ◽  
María de la Paz Sánchez
Keyword(s):  
Cell Cycle ◽  
Seed Germination ◽  
Protein Modification ◽  
De Novo ◽  
Cell Structure ◽  
Seed Storage ◽  
Control Mechanisms ◽  
Checkpoint Control ◽  
Cell Cycle Proteins ◽  
Regulatory Pathways

AbstractThe cell cycle is the series of molecular events that allows cells to duplicate and segregate their chromosomes to form new cells. The finding that a protein kinase, the product of the yeastcdc2gene, was fundamental in the regulation of the G2/M and G1/S transitions, associated with unstable proteins named cyclins, opened a very exciting and dynamic research area. The number of gene products that participate in the development and regulation of the cell cycle may be in the hundreds, and there is a high degree of conservation in protein sequences and regulatory pathways among eukaryotes. Although there are clear differences between plants and animals in cell structure, organization, growth, development and differentiation, the same types of proteins and very similar regulatory pathways seem to exist. Seed germination appears to be an excellent model system for studying the cell cycle in plants. Imbibition will reactivate meristematic cells – most initially with a G1DNA content – into the cell cycle in preparation for seedling establishment. Early events include a thorough survey of DNA status, since the drying process and seed storage conditions reduce chromosomal integrity. The initiation of cell cycle events leading to G1and S phases, and of the germination process itself, may depend on a G1checkpoint control. Most, if not all, cell cycle proteins appear to be already present in unimbibed embryos, although there is evidence of protein turnover in the early hours, suggesting the need forde novoprotein synthesis. Regulation also may occur at the level of protein modification, because existing G1, S and G2cell cycle proteins appear to be activated at precise times during germination. Thus, cell cycle control during seed germination may be exerted at multiple levels; however, knowledge of cell cycle events and their importance for germination is still scarce and fragmentary, and different species may have developed unique control mechanisms, more suited to specific germination characteristics and habitat.

scholarly journals Seed research for improved technologies

1998 ◽  
Vol 55 (spe) ◽  
pp. 19-26 ◽  
Author(s):  
R.J. Bino ◽  
H. Jalink ◽  
M.O. Oluoch ◽  
S.P.C. Groot
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Quality Assurance ◽  
Seed Germination ◽  
Seed Quality ◽  
Molecular Level ◽  
Control Mechanisms ◽  
High Quality ◽  
Production Chain ◽  
High Quality Seed

The production of high-quality seed is the basis for a durable a profitable agriculture. After production, seed is processed, conditioned, stored, shipped and germinated. For quality assurance, seed quality has to be controlled at all steps of the production chain. Seed functioning is accompanied by programmed transitions from cell proliferation to quiescence upon maturation and from quiescence to reinitiation of cellular metabolism upon imbibition. Despite the obvious importance of these control mechanisms, very little information is available at the molecular level concerning those elements that regulate seed germination. In the present study, the induction of cell cycle activity and the regulation of ß-tubulin expression is related to the water content and other physical properties of the seed.

scholarly journals Intrinsic S phase checkpoint enforced by an antiproliferative oncosuppressor cytokine

2021 ◽  
Author(s):  
Livio Mallucci ◽  
Valerie Wells
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Self Regulation ◽  
Cyclin A ◽  
S Phase ◽  
Cycle Phase ◽  
Control Mechanisms ◽  
Checkpoint Control ◽  
Normal Cells ◽  
Orderly Transition

AbstractThe cell cycle is strictly programmed with control mechanisms that dictate order in cell cycle progression to ensure faithful DNA replication, whose deviance may lead to cancer. Checkpoint control at the G1/S, S/G2 and G2/M portals have been defined but no statutory time-programmed control for securing orderly transition through S phase has so far been identified. Here we report that in normal cells DNA synthesis is controlled by a checkpoint sited within the early part of S phase, enforced by the βGBP cytokine an antiproliferative molecule otherwise known for its oncosuppressor properties that normal cells constitutively produce for self-regulation. Suppression of active Ras and active MAPK, block of cyclin A gene expression and suppression of CDK2-cyclin A activity are events which while specific to the control of a cell cycle phase in normal cells are part of the apoptotic network in cancer cells.

Human cyclin D1 encodes a labile nuclear protein whose synthesis is directly induced by growth factors and suppressed by cyclic AMP

1993 ◽  
Vol 104 (2) ◽  
pp. 545-555 ◽  
Author(s):  
A. Sewing ◽  
C. Burger ◽  
S. Brusselbach ◽  
C. Schalk ◽  
F.C. Lucibello ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Growth Factors ◽  
Cyclin D1 ◽  
Growth Control ◽  
D1 Protein ◽  
Control Mechanisms ◽  
Cell Fractionation ◽  
Regulatory Pathways ◽  
Human Diploid Fibroblasts ◽  
Serum Stimulation

We show that the cyclin D1 gene is regulated by a variety of growth factors in human diploid fibroblasts (WI-38). Expression of cyclin D1 mRNA is low in quiescent WI-38 cells and reaches a maximum around 10 hours after serum stimulation, i.e. approximately 8 hours prior to the onset of DNA synthesis. A cyclin D1-specific antiserum raised against a bacterially expressed fusion protein detected a 39 kDa polypeptide in WI-38 cells. In agreement with the RNA expression data, cyclin D1 protein synthesis is also serum-inducible, reaching a maximum around 9 hours post-stimulation. The results obtained by pulse-chase experiments, cell fractionation and immunostaining techniques strongly suggest that cyclin D1 is a labile protein (t1/2 approximately 38 min), which is located in the nucleus. Cyclin D1 is directly induced by growth factors, i.e. in the presence of cycloheximide, and its expression does not significantly fluctuate during the cell cycle in synchronized cells. Cyclin D1 therefore fundamentally differs from “classical” cyclins, such as the mitotic cyclin B, whose expression is clearly cell cycle-dependent. Cyclin D1 may rather establish a direct link between growth control mechanisms and the cell cycle. Interestingly, cyclin D1 expression is stimulated by the protein kinase C activator TPA, but suppressed by dibutyryl-cAMP and the adenylate cyclase inducer forskolin, pointing to multiple regulatory pathways controlling cyclin D1 expression.

Cell cycle proteins as molecular markers of malignant change in vulvar lichen sclerosus

2001 ◽  
Vol 11 (2) ◽  
pp. 113-118 ◽  
Author(s):  
K. J. Rolfe ◽  
L. J. Eva ◽  
A. B. Maclean ◽  
J. C. Crow ◽  
C. W. Perrett ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Molecular Markers ◽  
Lichen Sclerosus ◽  
Malignant Change ◽  
Cell Cycle Proteins ◽  
Vulvar Lichen Sclerosus

Ethylisopropylamiloride-sensitive pH control mechanisms modulate vascular smooth muscle cell growth

1991 ◽  
Vol 260 (3) ◽  
pp. C581-C588 ◽  
Author(s):  
A. Bobik ◽  
A. Grooms ◽  
P. J. Little ◽  
E. J. Cragoe ◽  
S. Grinpukel
Keyword(s):  
Cell Cycle ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Mitotic Cell ◽  
Ph Control ◽  
S Phase ◽  
Control Mechanisms ◽  
Aortic Smooth Muscle ◽  
Exchange Activity

The reported effects of alterations in Na-H exchange activity on mitogenesis are variable and appear dependent on the cell type examined. We examined the effects of reductions in ethylisopropylamiloride (EIPA)-sensitive pH-regulating mechanisms including Na-H exchange and alterations in intracellular pH (pHi) on the growth characteristics of rat aortic smooth muscle cells (RASM) cultured in serum-containing bicarbonate-buffered medium. Exposure of RASM replicating in bicarbonate-containing medium to the Na-H exchange inhibitors EIPA, dimethylamiloride (DMA), or amiloride (A) attenuated their replication rate. The order of potency of the inhibitors (EIPA greater than DMA much greater than A) was similar to their documented effects on Na-H exchange activity and to their order of potency for inhibiting recovery from CO2-induced acidosis in these cells. Reductions in pHi induced by lowering extracellular pH also attenuated the incorporation of [3H]-thymidine into DNA, while increases in pHi were associated with an acceleration in the rate of incorporation of [3H]thymidine into DNA. The effects of the Na-H exchange inhibitors on RASM replication were due to a reduction in the ability of the smooth muscle cells to enter the S phase of the mitotic cell cycle. This appeared predominantly the consequence of effects late within the G1 phase of the cell cycle. Concentrations of EIPA that markedly reduced the ability of RASM to enter S phase and to replicate also attenuated the increase in protein synthesis occurring 6-8 h after exposure to serum.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Transcriptome analysis of Cinnamomum migao seed germination in medicinal plants of Southwest China

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xiaolong Huang ◽  
Tian Tian ◽  
Jingzhong Chen ◽  
Deng Wang ◽  
Bingli Tong ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Seed Germination ◽  
Transcriptome Analysis ◽  
Energy Supply ◽  
Tricarboxylic Acid Cycle ◽  
Cell Structure ◽  
Seed Vigor ◽  
Differentially Expressed ◽  
Oil Bodies ◽  
Physiological Indexes

Abstract Background Cinnamomum migao is an endangered evergreen woody plant species endemic to China. Its fruit is used as a traditional medicine by the Miao nationality of China and has a high commercial value. However, its seed germination rate is extremely low under natural and artificial conditions. As the foundation of plant propagation, seed germination involves a series of physiological, cellular, and molecular changes; however, the molecular events and systematic changes occurring during C. migao seed germination remain unclear. Results In this study, combined with the changes in physiological indexes and transcription levels, we revealed the regulation characteristics of cell structures, storage substances, and antioxidant capacity during seed germination. Electron microscopy analysis revealed that abundant smooth and full oil bodies were present in the cotyledons of the seeds. With seed germination, oil bodies and other substances gradually degraded to supply energy; this was consistent with the content of storage substances. In parallel to electron microscopy and physiological analyses, transcriptome analysis showed that 80–90 % of differentially expressed genes (DEGs) appeared after seed imbibition, reflecting important development and physiological changes. The unigenes involved in material metabolism (glycerolipid metabolism, fatty acid degradation, and starch and sucrose metabolism) and energy supply pathways (pentose phosphate pathway, glycolysis pathway, pyruvate metabolism, tricarboxylic acid cycle, and oxidative phosphorylation) were differentially expressed in the four germination stages. Among these DEGs, a small number of genes in the energy supply pathway at the initial stage of germination maintained high level of expression to maintain seed vigor and germination ability. Genes involved in lipid metabolism were firstly activated at a large scale in the LK (seed coat fissure) stage, and then genes involved in carbohydrates (CHO) metabolism were activated, which had their own species specificity. Conclusions Our study revealed the transcriptional levels of genes and the sequence of their corresponding metabolic pathways during seed germination. The changes in cell structure and physiological indexes also confirmed these events. Our findings provide a foundation for determining the molecular mechanisms underlying seed germination.

scholarly journals Expression Signatures of microRNAs and Their Targeted Pathways in the Adipose Tissue of Chickens during the Transition from Embryonic to Post-Hatch Development

Genes ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 196
Author(s):  
Julie A. Hicks ◽  
Hsiao-Ching Liu
Keyword(s):  
Energy Source ◽  
Adipose Tissue ◽  
De Novo ◽  
Lipid Storage ◽  
Storage Site ◽  
Metabolic Processes ◽  
Metabolic Switch ◽  
Regulatory Pathways ◽  
Main Site ◽  
Real Time Quantitative Pcr

As the chick transitions from embryonic to post-hatching life, its metabolism must quickly undergo a dramatic switch in its major energy source. The chick embryo derives most of its energy from the yolk, a lipid-rich/carbohydrate-poor source. Upon hatching, the chick’s metabolism must then be able to utilize a lipid-poor/carbohydrate-rich source (feed) as its main form of energy. We recently found that a number of hepatically-expressed microRNAs (miRNAs) help facilitate this shift in metabolic processes in the chick liver, the main site of lipogenesis. While adipose tissue was initially thought to mainly serve as a lipid storage site, it is now known to carry many metabolic, endocrine, and immunological functions. Therefore, it would be expected that adipose tissue is also an important factor in the metabolic switch. To that end, we used next generation sequencing (NGS) and real-time quantitative PCR (RT-qPCR) to generate miRNome and transcriptome signatures of the adipose tissue during the transition from late embryonic to early post-hatch development. As adipose tissue is well known to produce inflammatory and other immune factors, we used SPF white leghorns to generate the initial miRNome and transcriptome signatures to minimize complications from external factors (e.g., pathogenic infections) and ensure the identification of bona fide switch-associated miRNAs and transcripts. We then examined their expression signatures in the adipose tissue of broilers (Ross 708). Using E18 embryos as representative of pre-switching metabolism and D3 chicks as a representative of post-switching metabolism, we identified a group of miRNAs which work concordantly to regulate a diverse but interconnected group of developmental, immune and metabolic processes in the adipose tissue during the metabolic switch. Network mapping suggests that during the first days post-hatch, despite the consumption of feed, the chick is still heavily reliant upon adipose tissue lipid stores for energy production, and is not yet efficiently using their new energy source for de novo lipid storage. A number of core master regulatory pathways including, circadian rhythm transcriptional regulation and growth hormone (GH) signaling, likely work in concert with miRNAs to maintain an essential balance between adipogenic, lipolytic, developmental, and immunological processes in the adipose tissue during the metabolic switch.

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