Pseudodirected variation in the requirement of cultured plant cells for cell-division factors

Development ◽  
1994 ◽  
Vol 120 (5) ◽  
pp. 1163-1168
Author(s):  
F. Meins ◽  
M. Seldran
Keyword(s):  
Cell Division ◽  
Phenotypic Variation ◽  
Quantitative Method ◽  
Somatic Mutations ◽  
Plant Cells ◽  
Tissue Level ◽  
C Cells ◽  
Cytokinin Action ◽  
Selection Of ◽  
Cells Cultured

Cells cultured from explants of tobacco leaf require exogenous cell-division factors such as the cytokinin kinetin for sustained proliferation. When cytokinin-requiring (C-) cells are cultured on medium containing 1/100 the optimum cytokinin concen tration they rapidly give rise to cytokinin-autotrophic (C+) variants. Some of these variants result from a meiotically transmitted change at the Habituated leaf-2 locus. We measured the rate of phenotypic variation by a simple, quantitative method and found that cultured tobacco cells alternate between the C- and C+ states at extremely high rates of approx. 10–2 per cell generation, which is 102- to 103-fold more rapid than most somatic mutations in tobacco. These changes are so rapid that the cla ssical distinction between random and induced events is blurred. Selection of alternate phenotypes arising by rapid, reversible cellular variation results in changes that appear to be directed at the tissue level. This phenomenon, called pseudodirected variation, is of particular interest because it suggests novel stochastic mechanisms of cytokinin action and a plausible explanation for the directed, but plastic nature of development in plants.

Confocal microscopy of the cytoskeleton in living plant cells following microinjection of fluorescent probes

1993 ◽  
Vol 51 ◽  
pp. 130-131
Author(s):  
Ann Cleary
Keyword(s):  
Cell Division ◽  
Fluorescent Probes ◽  
Actin Filaments ◽  
Intracellular Transport ◽  
Cell Structure ◽  
Plant Cells ◽  
Cell Plate ◽  
Cell Cortex ◽  
Living Plant ◽  
Rhodamine Phalloidin

Microinjection of fluorescent probes into living plant cells reveals new aspects of cell structure and function. Microtubules and actin filaments are dynamic components of the cytoskeleton and are involved in cell growth, division and intracellular transport. To date, cytoskeletal probes used in microinjection studies have included rhodamine-phalloidin for labelling actin filaments and fluorescently labelled animal tubulin for incorporation into microtubules. From a recent study of Tradescantia stamen hair cells it appears that actin may have a role in defining the plane of cell division. Unlike microtubules, actin is present in the cell cortex and delimits the division site throughout mitosis. Herein, I shall describe actin, its arrangement and putative role in cell plate placement, in another material, living cells of Tradescantia leaf epidermis.The epidermis is peeled from the abaxial surface of young leaves usually without disruption to cytoplasmic streaming or cell division. The peel is stuck to the base of a well slide using 0.1% polyethylenimine and bathed in a solution of 1% mannitol +/− 1 mM probenecid.

scholarly journals THE SELECTION OF S. CEREVISIAE MUTANTS DEFECTIVE IN THE START EVENT OF CELL DIVISION

Genetics ◽  
1980 ◽  
Vol 95 (3) ◽  
pp. 561-577 ◽  
Author(s):  
Steven I Reed
Keyword(s):  
Cell Division ◽  
Genetic Analysis ◽  
Linkage Map ◽  
Nuclear Genes ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Mating Pheromone ◽  
Preliminary Characterization ◽  
Complementation Groups ◽  
Selection Of

ABSTRACT Thirty-three temperature-sensitive mutations defective in the start event of the cell division cycle of Saccharomyces cereuisiae were isolated and subjected to preliminary characterization. Complementation studies assigned these mutations to four complementation groups, one of which, cdc28, has been described previously. Genetic analysis revealed that these complementation groups define single nuclear genes, unlinked to one another. One of the three newly identified genes, cdc37, has been located in the yeast linkage map on chromosome IV, two meiotic map units distal to hom2.—Each mutation produces stage-specific arrest of cell division at start, the same point where mating pheromone interrupts division. After synchronization at start by incubation at the restrictive temperature, the mutants retain the capacity to enlarge and to conjugate.

scholarly journals Distinct genetic pathways define pre-malignant versus compensatory clonal hematopoiesis in Shwachman-Diamond syndrome

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Alyssa L. Kennedy ◽  
Kasiani C. Myers ◽  
James Bowman ◽  
Christopher J. Gibson ◽  
Nicholas D. Camarda ◽  
...  
Keyword(s):  
Somatic Mutations ◽  
Bone Marrow Failure ◽  
Subsequent Development ◽  
Genetic Constraints ◽  
Clonal Hematopoiesis ◽  
Clinical Surveillance ◽  
Clinical Consequences ◽  
Shwachman Diamond Syndrome ◽  
Mechanistic Basis ◽  
Selection Of

AbstractTo understand the mechanisms that mediate germline genetic leukemia predisposition, we studied the inherited ribosomopathy Shwachman-Diamond syndrome (SDS), a bone marrow failure disorder with high risk of myeloid malignancies at an early age. To define the mechanistic basis of clonal hematopoiesis in SDS, we investigate somatic mutations acquired by patients with SDS followed longitudinally. Here we report that multiple independent somatic hematopoietic clones arise early in life, most commonly harboring heterozygous mutations in EIF6 or TP53. We show that germline SBDS deficiency establishes a fitness constraint that drives selection of somatic clones via two distinct mechanisms with different clinical consequences. EIF6 inactivation mediates a compensatory pathway with limited leukemic potential by ameliorating the underlying SDS ribosome defect and enhancing clone fitness. TP53 mutations define a maladaptive pathway with enhanced leukemic potential by inactivating tumor suppressor checkpoints without correcting the ribosome defect. Subsequent development of leukemia was associated with acquisition of biallelic TP53 alterations. These results mechanistically link leukemia predisposition to germline genetic constraints on cellular fitness, and provide a rational framework for clinical surveillance strategies.

scholarly journals Business analysis of cattle fattening using agribusiness paradigm (case study at Molan beef cattle livestock) in West Binjai Regency, North Sumatera Province

AGRIMOR ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 17-19
Author(s):  
Ruth Dameria Haloho
Keyword(s):  
Beef Cattle ◽  
Quantitative Method ◽  
Fixed Costs ◽  
Paradigm Case ◽  
Business Analysis ◽  
Cattle Farming ◽  
Selection Of

This study aims to determine the Analysis of Molan Cattle Fattening Business Analysis. This research was carried out at the Molan Cattle Fattening Business in Tanjung Jati Village, Binjai District, Binjai City. The research is a case study. The selection of research locations with consideration of the business of Molan Cattle Farming is a profitable business. The data were collected by doing observation and direct interviews. The Data were analysis with descriptive and quantitative method. The results showed the total variable costs incurred 1 409 600 000 IDR, fixed costs amounting to 75,000,000 IDR with 1 950 000 000 IDR in revenues. The profitability value is 31.34%. The results showed the number of cattle fattening as many as 150 heads with income of 465 400 000 IDR. BEP Fattening Molan Cattle Fattening Business is 267,858,142 IDR by maintaining 21 cows. The conclusion of this research is the profitability of Molan Cattle Fattening is 31.34% higher than the interest bank of 6 percent and The Value of BEP as much as 267 858 142 IDR with maintaining 21 tails.

scholarly journals Cell Cycle-Specific Disruption of the Preprophase Band of Microtubules in Fern Protonemata: Effects of Displacement of the Endoplasm by Centrifugation

1992 ◽  
Vol 101 (1) ◽  
pp. 93-98 ◽  
Author(s):  
TAKASHI MURATA ◽  
MASAMITSU WADA
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Plant Cells ◽  
Preprophase Band ◽  
Higher Plant ◽  
The Future ◽  
Prophase Nucleus ◽  
Original Region ◽  
Fern Protonemata

The preprophase band (PPB) of microtubules (MTs), which appears at the future site of cytokinesis prior to cell division in higher plant cells, disappears by metaphase. Recent studies have shown that displacement of the endoplasm from the PPB region by centrifugation delays the disappearance of the PPB. To study the role of the endoplasm in the cell cycle-specific disruption of the PPB, the filamentous protonemal cells of the fern Adiantum capilius-veneris L. were centrifuged twice so that the first centrifugation displaced the endoplasm from the site of the PPB and the second returned it to its original location. The endoplasm, including the nucleus of various stages of mitosis, could be returned by the second centrifugation to the original region of the PPB, which persists during mitosis in the centrifuged cells. When endoplasm with a prophase nucleus was returned to its original location, the PPB was not disrupted. When endoplasm with a prometa-phase telophase nucleus was similarly returned, the PPB was disrupted within 10 min of termination of centrifugation. In protonemal cells of Adiantum, a second PPB is often formed near the displaced nucleus after the first centrifugation. In cells in which the endoplasm was considered to have been returned to its original location at the prophase/prometaphase transition, the second PPB did not disappear even though the initial PPB was disrupted by the endoplasm. These results suggest that cell cycle-specific disruption of the PPB is regulated by some factor(s) in the endoplasm, which appears at prometaphase, i.e. the stage at which the PPB is disrupted in non-centrifuged cells.

scholarly journals Positive selection of skeleton genes during domestication indicates the potential genetic mechanism for loss of flight in ducks

2021 ◽  
Author(s):  
Tao Zhu ◽  
Xin Qi ◽  
Yu Chen ◽  
Liang Wang ◽  
Xueze Lv ◽  
...  
Keyword(s):  
Body Size ◽  
Phenotypic Variation ◽  
Bone Development ◽  
Bird Species ◽  
Genomic Data ◽  
Domestic Animals ◽  
Genetic Mechanism ◽  
Bone Morphology ◽  
Domestic Ducks ◽  
Selection Of

Abstract Background Domestication alters lots of phenotypic, neurologic and physiologic traits between domestic animals and their wild ancestors. Domestic ducks were originated from mallards (Anas platyrhynchos) and some documents also showed that spot-billed ducks (Anas zonorhyncha) could also genetically contribute a small part to the domestication. Compared with the two ancestral species, domestic ducks generally present changes in body size and bone morphology, which is supposed to lead to loss of fight in domestic ducks. In the present study, we performed both genomic and transcriptomic analysis to identify candidate genes in order to elucidate the genetic mechanism underlying the phenotypic variation. Results Our results showed that genes associated with the skeleton systems were positively selected during domestication by Fst analysis between the wild and domestic ducks. We also found that many differentially expressed genes (DEGs) in the breast muscle between the wild and domestic ducks were enriched in the pathway for ossification. Among the genes, FGF14 and EIF2AK3 were also under strong selection by the genomic data, and they were both reported to be associated with limb morphology, bone development and flightlessness in some bird species. Conclusions Our study showed that the skeleton related genes were positively selected in the process of domestication, which could also cause the loss of flight in domestic ducks.

scholarly journals Signs of positive selection of somatic mutations in human cancers detected by EST sequence analysis

BMC Cancer ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Vladimir N Babenko ◽  
Malay K Basu ◽  
Fyodor A Kondrashov ◽  
Igor B Rogozin ◽  
Eugene V Koonin
Keyword(s):  
Sequence Analysis ◽  
Positive Selection ◽  
Somatic Mutations ◽  
Human Cancers ◽  
Est Sequence ◽  
Selection Of
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