scholarly journals Sequential steps for developmental arrest in Arabidopsis seeds

Development ◽  
2001 ◽  
Vol 128 (2) ◽  
pp. 243-252 ◽  
Author(s):  
V. Raz ◽  
J.H. Bergervoet ◽  
M. Koornneef
Keyword(s):  
Cell Division ◽  
Developmental Stages ◽  
Growth Arrest ◽  
Mature Embryo ◽  
Seed Maturation ◽  
Continuous Growth ◽  
Embryo Dormancy ◽  
Embryo Stage ◽  
Plant Embryo ◽  
Premature Germination

The continuous growth of the plant embryo is interrupted during the seed maturation processes which results in a dormant seed. The embryo continues development after germination when it grows into a seedling. The embryo growth phase starts after morphogenesis and ends when the embryo fills the seed sac. Very little is known about the processes regulating this phase. We describe mutants that affect embryo growth in two sequential developmental stages. Firstly, embryo growth arrest is regulated by the FUS3/LEC type genes, as mutations in these genes cause a continuation of growth in immature embryos. Secondly, a later stage of embryo dormancy is regulated by ABI3 and abscisic acid; abi3 and aba1 mutants exhibit premature germination only after embryos mature. Mutations affecting both developmental stages result in an additive phenotype and double mutants are highly viviparous. Embryo growth arrest is regulated by cell division activities in both the embryo and the endosperm, which are gradually switched off at the mature embryo stage. In the fus3/lec mutants, however, cell division in both the embryo and endosperm is not arrested, but rather is prolonged throughout seed maturation. Furthermore ectopic cell division occurs in seedlings. Our results indicate that seed dormancy is secured via at least two sequential developmental processes: embryo growth arrest, which is regulated by cell division and embryo dormancy.

Expression of senescence in Neurospora intermedia

1986 ◽  
Vol 28 (3) ◽  
pp. 459-467 ◽  
Author(s):  
A. J. F. Griffiths ◽  
S. Kraus ◽  
H. Bertrand
Keyword(s):  
Mitochondrial Dna ◽  
Genetic Factors ◽  
Growth Arrest ◽  
Growth Front ◽  
Continuous Growth ◽  
Quiescent Cells ◽  
Neurospora Intermedia ◽  
Aerial Hyphae ◽  
Similar Basis ◽  
Transfer Interval

Kalilo cytoplasms of Neurospora intermedia have been shown to express senescence in two ways. First, by the previously reported way of death in a subculture series, and second, as reported here, by growth cessation in a 50-cm race tube. Only those cultures that are sufficiently far advanced in the development of senescence will stop growth in the length of a race tube. Resumption of growth occurs in most cases of growth arrest in race tubes. Although in subculture series growth resumption is rare, there is probably a similar basis: mitochondrial DNA (mtDNA) studies on one such case showed that growth resumption is associated with a resurgence of normal mtDNA and a decline of abnormal genomes. When senescent cultures in race tubes were sampled by removing mycelial cores, longer grown cultures were shown to be able to support less growth than younger cultures of the same genotype, and the growth front was generally able to support less growth than other regions. Therefore senescence in both transfer series and in race tubes involves the accumulation of genetic factors unable to suppport continuous growth. The expression of senescence is considered to be more efficient in subculture series than in race tubes. In such series, conidia or aerial hyphae work equally well as transfer inocula, but 1-mm hyphal tips cut from growing mycelium do not promote senescence when used as inocula. Furthermore, varying the transfer interval does not affect senescence. It is concluded that there is some feature of the development or germination of quiescent cells that enhances the expression of senescence in Neurospora.Key words: Neurospora, senescence, mitochondria, growth.

scholarly journals Identification of Novel Serine/Threonine Protein Phosphatases inTrypanosoma cruzi: a Potential Role in Control of Cytokinesis and Morphology

2000 ◽  
Vol 68 (3) ◽  
pp. 1350-1358 ◽  
Author(s):  
George A. Orr ◽  
Craig Werner ◽  
Jun Xu ◽  
Marcia Bennett ◽  
Louis M. Weiss ◽  
...  
Keyword(s):  
Cell Division ◽  
Okadaic Acid ◽  
Blot Analysis ◽  
Protein Phosphatase ◽  
Protein Phosphatases ◽  
Growth Arrest ◽  
Human Protein ◽  
Protein Phosphatase 1 ◽  
Calyculin A ◽  
Metacyclic Trypomastigote

ABSTRACT We cloned two novel Trypanosoma cruzi proteins by using degenerate oligonucleotide primers prepared against conserved domains in mammalian serine/threonine protein phosphatases 1, 2A, and 2B. The isolated genes encoded proteins of 323 and 330 amino acids, respectively, that were more homologous to the catalytic subunit of human protein phosphatase 1 than to those of human protein phosphatase 2A or 2B. The proteins encoded by these genes have been tentatively designated TcPP1α and TcPP1β. Northern blot analysis revealed the presence of a major 2.3-kb mRNA transcript hybridizing to each gene in both the epimastigote and metacyclic trypomastigote developmental stages. Southern blot analysis suggests that each protein phosphatase 1 gene is present as a single copy in the T. cruzi genome. The complete coding region for TcPP1β was expressed inEscherichia coli by using a vector, pTACTAC, with thetrp-lac hybrid promoter. The recombinant protein from the TcPP1β construct displayed phosphatase activity toward phosphorylasea, and this activity was preferentially inhibited by calyculin A (50% inhibitory concentration [IC50], ∼2 nM) over okadaic acid (IC50, ∼100 nM). Calyculin A, but not okadaic acid, had profound effects on the in vitro replication and morphology of T. cruzi epimastigotes. Low concentrations of calyculin A (1 to 10 nM) caused growth arrest. Electron microscopic studies of the calyculin A-treated epimastigotes revealed that the organisms underwent duplication of organelles, including the flagellum, kinetoplast, and nucleus, but were incapable of completing cell division. At concentrations higher than 10 nM, or upon prolonged incubation at lower concentrations, the epimastigotes lost their characteristic elongated spindle shape and had a more rounded morphology. Okadaic acid at concentrations up to 1 μM did not result in growth arrest or morphological alterations to T. cruziepimastigotes. Calyculin A, but not okadaic acid, was also a potent inhibitor of the dephosphorylation of 32P-labeled phosphorylase a by T. cruzi epimastigotes and metacyclic trypomastigote extracts. These inhibitor studies suggest that in T. cruzi, type 1 protein phosphatases are important for the completion of cell division and for the maintenance of cell shape.

scholarly journals Gene expression profiling identifies pathways involved in seeds maturation of Jatropha curcas

2019 ◽  
Author(s):  
Fatemeh Maghuly ◽  
Tamas Deak ◽  
Klemens Vierlinger ◽  
Stephan Pabinger ◽  
Hakim Tafer ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Seed Development ◽  
Jatropha Curcas ◽  
Molecular Mechanisms ◽  
Seed Quality ◽  
Developmental Stages ◽  
Seed Maturation ◽  
Nutrient Mobilization ◽  
Starting Point ◽  
Maturation Stages

Abstract Background: Jatropha curcas, a tropical shrub, is a promising biofuel crop, which produces seeds with a high content of oil and protein. To better understand the development of its seeds to improve Jatropha`s agronomic performance, a two-step approach was performed: 1) generation of the entire transcriptome of six different maturation stages of J. curcas seeds using 454-Roche sequencing of a cDNA library, 2) comparison of transcriptional expression levels in six different developmental stages of seeds using a custom Agilent 8x60K oligonucleotide microarray. Results: A total of 793,875 high-quality reads were assembled into 19,841 unique full-length contigs, of which 13,705 could be annotated with Gene Ontology (GO) terms. Microarray data analysis identified 9,111 probes (out of 57,842 probes), which were differentially expressed between the six developmental stages. The expression results were validated for 70 randomly selected putative genes. Result from cluster analyses showed that transcripts related to sucrose, fatty acid, flavonoid, phenylpropanoid, lignin, hormone biosynthesis were over-represented in the early stage, while lipid storage, seed dormancy and maturation in the late stage. Generally, the expression of the most over-represented transcripts decrease in the last stage of seed maturation. Further, expression analyses of different maturation stages of J. curcas seed showed that most changes in transcript abundance occurred between the two last stages, suggesting that the timing of metabolic pathways during seed maturation in J. curcas is in late stages. The co-expression result showed a high degree of connectivity between genes that play essential role in fatty acid biosynthesis and nutrient mobilization. Furthermore, seed development and hormone pathways are significantly well connected. Conclusion: The obtained results revealed DESs regulating important pathways related to seed maturation, which could contribute to understanding the complex regulatory network during seed development. This study provides detailed information on transcription changes during J. curcas seed development and provides a starting point for a genomic survey of seed quality traits. The current results highlighted specific genes and processes relevant to the molecular mechanisms involved in Jatropha seed development, and it is anticipated that this data can be delivered to other Euphorbiaceae species of economic value.

Modeling of plant embryo morphodynamics at early developmental stages

2013 ◽  
Vol 3 (3) ◽  
pp. 176-183
Author(s):  
S. V. Nikolaev ◽  
N. A. Kolchanov ◽  
S. K. Golushko ◽  
J. -C. Palauqui ◽  
A. Urban ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Early Developmental Stages ◽  
Plant Embryo ◽  
Early Developmental

scholarly journals From centriole biogenesis to cellular function: Centrioles are essential for cell division at critical developmental stages

Cell Cycle ◽  
2008 ◽  
Vol 7 (1) ◽  
pp. 11-16 ◽  
Author(s):  
Ana Rodrigues-Martins ◽  
Maria Riparbelli ◽  
Giuliano Callaini ◽  
David M. Glover ◽  
Monica Bettencourt-Dias
Keyword(s):  
Cell Division ◽  
Developmental Stages ◽  
Cellular Function

scholarly journals GROWTH INHIBITION OF MURINE TUMOR CELLS, IN VITRO, BY PUROMYCIN, [6N]O2'-DIBUTYRYL 3',5'-ADENOSINE MONOPHOSPHATE, OR ADENOSINE

1973 ◽  
Vol 57 (2) ◽  
pp. 397-405 ◽  
Author(s):  
D. B. Thomas ◽  
Gay Medley ◽  
C. A. Lingwood
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Cell Growth ◽  
Growth Inhibition ◽  
Tumor Cells ◽  
Growth Arrest ◽  
Adenosine Monophosphate ◽  
Synchronous Cultures ◽  
Murine Tumor Cells

The cytostatic effects of puromycm, [6N]O2'-dibutyryl 3',5'-adenosine monophosphate, and adenosine on asynchronous and synchronous cultures of the murine mastocytoma, P815Y, have been studied. Cell growth was arrested after a minimum of one further division. A model is proposed for the inhibition of cell division in which the periods of inhibition and growth arrest are separated in time by one cell cycle.

scholarly journals Nitrate Induction of Primary Root Growth Requires Cytokinin Signaling in Arabidopsis thaliana

2019 ◽  
Vol 61 (2) ◽  
pp. 342-352 ◽  
Author(s):  
Pamela A Naulin ◽  
Grace I Armijo ◽  
Andrea S Vega ◽  
Karem P Tamayo ◽  
Diana E Gras ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Division ◽  
Root Growth ◽  
Primary Root ◽  
Growth Arrest ◽  
Root Tip ◽  
Wild Type ◽  
Cytokinin Signaling ◽  
Control Growth ◽  
Primary Root Growth

Abstract Nitrate can act as a potent signal to control growth and development in plants. In this study, we show that nitrate is able to stimulate primary root growth via increased meristem activity and cytokinin signaling. Cytokinin perception and biosynthesis mutants displayed shorter roots as compared with wild-type plants when grown with nitrate as the only nitrogen source. Histological analysis of the root tip revealed decreased cell division and elongation in the cytokinin receptor double mutant ahk2/ahk4 as compared with wild-type plants under a sufficient nitrate regime. Interestingly, a nitrate-dependent root growth arrest was observed between days 5 and 6 after sowing. Wild-type plants were able to recover from this growth arrest, while cytokinin signaling or biosynthesis mutants were not. Transcriptome analysis revealed significant changes in gene expression after, but not before, this transition in contrasting genotypes and nitrate regimes. We identified genes involved in both cell division and elongation as potentially important for primary root growth in response to nitrate. Our results provide evidence linking nitrate and cytokinin signaling for the control of primary root growth in Arabidopsis thaliana.

Floral development of Aponogeton natans and A. undulatus

1977 ◽  
Vol 55 (9) ◽  
pp. 1106-1120 ◽  
Author(s):  
V. Singh ◽  
R. Sattler
Keyword(s):  
Cell Division ◽  
Developmental Stage ◽  
Floral Development ◽  
Developmental Stages ◽  
Point Of View ◽  
Stages Of Development ◽  
The Third ◽  
Procambial Strand ◽  
Tunica Layer

The primordia of the floral appendages are initiated in an acropetal succession. Members of the same whorl appear nearly simultaneously. The gynoecial whorl and the two staminal whorls are trimerous, whereas the perianth consists only of two anteriolateral tepals. However, the posterior (adaxial) tepal may be present as an extremely reduced buttress whose growth becomes arrested immediately after its inception. If this somewhat questionable tepal rudiment is included we have a perfectly trimerous and tetracyclic flower with alternation of successive whorls. Subtending bracts of the flowers are completely missing in all developmental stages. While the tepal primordia are dorsiventral from their inception, the stamen and pistil (carpel) primordia originate as hemispherical mounds which become dorsiventral in subsequent stages of development. Each pistil (carpel) primordium becomes horseshoe shaped. As the margins grow up and contact they fuse postgenitally. No cross zone is formed. Placentation is submarginal. In A. natans eight ovules are formed and in A. undulatus only two arise; all ovules are bitegmic. The floral apices have a two-layered tunica up to the stage of pistil formation. The inception of all floral appendages (including the ovules) occurs by periclinal cell division in the second tunica layer. The third layer (corpus) may contribute to the formation of the stamens and pistils. Each appendage primordium receives only one procambial strand which begins to differentiate after the inception of the primordium. The questionable rudimentary tepal buttress lacks a procambial strand. Apparently it does not reach the developmental stage at which procambial induction occurs. From the point of view of floral development, the two species of Aponogeton differ drastically from members of the Alismatales studied so far. Among the Helobiae, the Aponogetonaceae appear to be most closely related to the Scheuchzeriaceae and the Juncaginaceae (Triglochinaceae).

Heteroblastic seedlings of green ash. III. Cell division activity and marginal meristems

1986 ◽  
Vol 64 (11) ◽  
pp. 2662-2668 ◽  
Author(s):  
E. K. Merrill
Keyword(s):  
Cell Division ◽  
Leaf Blade ◽  
Developmental Stages ◽  
Leaf Primordia ◽  
Leaf Margin ◽  
Green Ash ◽  
Histological Differentiation ◽  
Cell Counts ◽  
Histological Criteria ◽  
Early Developmental

The early developmental stages of simple and compound leaves of green ash (50–400 μm long) were used to relate cell division activity (mitotic index) to developing leaf form and histological differentiation. Densely cytoplasmic cells within cross-sectioned leaf primordia have higher mitotic indices than protodermal cells and other internal cells that are more vacuolate. Among densely cytoplasmic cells mitotic indices decrease from the primordial leaf margin toward the procambium. Ground meristem cells within three to five cell widths of the primordial margin had the highest mitotic indices. Actual cell counts indicate that densely cytoplasmic cells increase in number in areas of leaf blade or leaflet initiation more than do vacuolate cells or protodermal cells. It is proposed that marginal meristems defined by spatial and histological criteria are important in producing new cells that are the basis for the generation of simple and compound leaf forms.

scholarly journals Growth-Arrest-Specific Protein 2 Inhibits Cell Division in Xenopus Embryos

PLoS ONE ◽  
2011 ◽  
Vol 6 (9) ◽  
pp. e24698 ◽  
Author(s):  
Tong Zhang ◽  
Bama Dayanandan ◽  
Isabelle Rouiller ◽  
Elizabeth J. Lawrence ◽  
Craig A. Mandato
Keyword(s):  
Cell Division ◽  
Growth Arrest ◽  
Specific Protein ◽  
Xenopus Embryos
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