In vivo and in vitro instability of B chromosomes in palmarosa grass (Cymbopogon martinii var. motia)

Genome ◽  
1988 ◽  
Vol 30 (6) ◽  
pp. 966-973 ◽  
Author(s):  
H. L. Sreenath ◽  
K. S. Jagadishchandra
Keyword(s):  
Germ Line ◽  
Chromosome Instability ◽  
Metaphase Plate ◽  
B Chromosome ◽  
B Chromosomes ◽  
Dichlorophenoxyacetic Acid ◽  
Cymbopogon Martinii ◽  
2,4 Dichlorophenoxyacetic Acid

Meiotic and mitotic instability and elimination of B chromosomes was observed in diploid palmarosa (Cymbopogon martinii var. motia) with 2n = 20 + 1–2 B under in vivo and in vitro conditions. Under in vivo conditions B chromosomes were totally absent from the roots but preferentially transmitted in the germ line tissues. When present as a pair, the B chromosomes formed bivalents showing almost regular orientation, congression, and disjunction. When present singly, the B chromosome formed a univalent and did not pair with any of the A chromosomes and showed nonalignment on the metaphase plate during metaphase I. Immature inflorescences of a race of palmarosa with 2n = 20 + 2 B were cultured on Murashige and Skoog's medium containing 1 mg/L of 2,4-dichlorophenoxyacetic acid to produce embryogenic callus. The cytological analysis of the callus revealed only 20 A chromosomes in nearly all the cells, both the B chromosomes being eliminated. From this callus, plantlets without B chromosomes were regenerated on MS medium without growth regulators and established in the soil. The regenerated plants exhibited 20 A chromosomes with normal meiosis.Key words: Cymbopogon martinii, chromosome instability, palmarosa grass, B chromosomes, tissue culture, plant regeneration.

Influence of auxins on somatic embryogenesis and alkaloid accumulation in Leucojum aestivum callus

2013 ◽  
Vol 8 (6) ◽  
pp. 591-599 ◽  
Author(s):  
Agata Ptak ◽  
Anna Tahchy ◽  
Edyta Skrzypek ◽  
Tomasz Wójtowicz ◽  
Dominique Laurain-Mattar
Keyword(s):  
Somatic Embryogenesis ◽  
Somatic Embryo ◽  
Symptomatic Treatment ◽  
Dichlorophenoxyacetic Acid ◽  
Leucojum Aestivum ◽  
Anisic Acid ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Embryogenic Response

AbstractIn vitro cultures of Leucojum aestivum are considered as an alternative for the production of galanthamine, which is used for the symptomatic treatment of Alzheimer’s disease. We studied the effects of auxins 2,4-dichlorophenoxyacetic acid (2,4-D), 4-amino-3,5,6-trichloropicolinic acid (picloram), 3,6-dichloro-o-anisic acid (dicamba) at concentrations of 25 and 50 µM on the induction of embryogenic callus and its capacity to induce somatic embryogenesis and alkaloid accumulation. The embryogenic response of the explants was from 30% for 25 µM of dicamba to 100% for picloram (for both 25 and 50 µM). 2,4-D (50 µM) stimulated greater callus proliferation and somatic embryo induction as compared to the other auxins. Polyethylene glycol (PEG) stimulated somatic embryo maturation. Callus grown on media containing 50 µM of auxins produced fewer phenolic compounds as compared with callus grown on media containing 25 µM of auxins. GC-MS analyses showed seven alkaloids in the in vivo bulbs and two to four in callus culture. Galanthamine was detected in callus cultivated with 2,4-D (25, 50 µM), picloram (25 µM), and dicamba (50 µM). Other alkaloids, trisphaeridine, tazettine, and 11-hydroxyvittatine were accumulated only in callus growing on medium with picloram (50 µM).

Physiologically Based Pharmacokinetic Modeling of Salivary Concentrations for Noninvasive Biomonitoring of 2,4-Dichlorophenoxyacetic Acid (2,4-D)

2019 ◽  
Vol 172 (2) ◽  
pp. 330-343
Author(s):  
Alice A Han ◽  
Charles Timchalk ◽  
Zana A Carver ◽  
Thomas J Weber ◽  
Kimberly J Tyrrell ◽  
...  
Keyword(s):  
Pbpk Model ◽  
Pbpk Modeling ◽  
Dichlorophenoxyacetic Acid ◽  
Diffusion Limited ◽  
Physiologically Based Pharmacokinetic ◽  
Physiologically Based ◽  
Dynamic Time ◽  
2,4 Dichlorophenoxyacetic Acid

Abstract Saliva has become a favorable sample matrix for biomonitoring due to its noninvasive attributes and overall flexibility in collection. To ensure measured salivary concentrations reflect the exposure, a solid understanding of the salivary transport mechanism and relationships between salivary concentrations and other monitored matrices (ie, blood, urine) is needed. Salivary transport of a commonly applied herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), was observed in vitro and in vivo and a physiologically based pharmacokinetic (PBPK) model was developed to translate observations from the cell culture model to those in animal models and further evaluate 2,4-D kinetics in humans. Although apparent differences in experimental in vitro and in vivo saliva:plasma ratios (0.034 and 0.0079) were observed, simulations with the PBPK model demonstrated dynamic time and dose-dependent saliva:plasma ratios, elucidating key mechanisms affecting salivary transport. The model suggested that 2,4-D exhibited diffusion-limited transport to saliva and was additionally impacted by protein binding saturation and permeability across the salivary gland. Consideration of sampling times post-exposure and potential saturation of transport mechanisms are then critical aspects for interpreting salivary 2,4-D biomonitoring observations. This work utilized PBPK modeling in in vitro to in vivo translation to explore benefits and limitations of salivary analysis for occupational biomonitoring.

In Vitro Shoot Regeneration from Callus Derived from Marubakaido Apple Rootstock under Different Aluminium Concentrations

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 460e-460 ◽  
Author(s):  
Marisa F. de Oliveira ◽  
Gerson R. de L. Fortes ◽  
João B. da Silva
Keyword(s):  
Shoot Regeneration ◽  
Dichlorophenoxyacetic Acid ◽  
Apple Rootstock ◽  
Under Five ◽  
Significant Difference ◽  
Previously Treated ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
In Vitro Shoot Regeneration

The aim of this work was to evaluate the organogenesis of Marubakaido apple rootstock under different aluminium concentratons. The explants were calli derived from apple internodes treated with either 2,4-dichlorophenoxyacetic acid or pichloram at 0.5 and 1.0 μM and under five different aluminium concentrations (0, 5, 10, 15, 20 mg/L). These calli were then treated with aluminium at 0, 5, 10, 15, and 20 mg/L. It was observed shoot regeneration only for those calli previously treated with pichloram. There were no significant difference among the aluminium concentrations.

Characterization of the Reproductive Mode in Guayule In Vitro

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 483a-483
Author(s):  
Roy N. Keys ◽  
Dennis T. Ray ◽  
David A. Dierig
Keyword(s):  
Field Experiments ◽  
Reproductive Mode ◽  
Dichlorophenoxyacetic Acid ◽  
Initial Field ◽  
Breeding Lines ◽  
Reproductive Modes ◽  
Desert Southwest ◽  
2,4 Dichlorophenoxyacetic Acid

Guayule (Parthenium argentatum Gray, Asteraceae) is a latex-producing perennial desert shrub that is potentially of economic importance as an industrial crop for the desert Southwest. It is known to possess complex reproductive modes. Diploids are predominantly sexual and self-incompatible, while polyploids show a range of apomictic potential and self-compatibility. This paper describes the development of a relatively rapid and simple technique for characterizing reproductive modes of breeding lines of P. argentatum. Initial field experiments were based on an auxin test used successfully to characterize reproductive mode in the Poaceae. The application of 2,4-dichlorophenoxyacetic acid inhibited embryo formation in P. argentatum, but this was not the case with other auxins tested. Results of field experiments were ambiguous because: 1) the floral structure of P. argentatum is such that auxins might not have penetrated to the ovules, and 2) there was potential self-fertilization by pollen released within isolation bags. Therefore, in vitro culture of flower heads was tested because it provided much better control of environmental conditions, growth regulator application, and pollen release. Auxin alone, or in combination with gibberellic acid or kinetin, inhibited parthenogenesis in vitro. Embryo production did not vary using two substantially different nutrient media. In vitro flower head culture using a (Nitsch and Nitsch) liquid nutrient medium without growth regulators, enabled characterization of the reproductive mode of seven breeding lines, ranging from predominantly sexual to predominantly apomictic. The results of this technique were substantiated using RAPD analyzes of progeny arrays from controlled crosses.

scholarly journals Localization matters: nuclear-trapped Survivin sensitizes glioblastoma cells to temozolomide by elevating cellular senescence and impairing homologous recombination

2021 ◽  
Author(s):  
Thomas R. Reich ◽  
Christian Schwarzenbach ◽  
Juliana Brandstetter Vilar ◽  
Sven Unger ◽  
Fabian Mühlhäusler ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Nuclear Export ◽  
Cell Model ◽  
Chromosome Instability ◽  
Direct Interaction ◽  
High Grade Glioma ◽  
Strand Break ◽  
Γh2ax Foci

AbstractTo clarify whether differential compartmentalization of Survivin impacts temozolomide (TMZ)-triggered end points, we established a well-defined glioblastoma cell model in vitro (LN229 and A172) and in vivo, distinguishing between its nuclear and cytoplasmic localization. Expression of nuclear export sequence (NES)-mutated Survivin (SurvNESmut-GFP) led to impaired colony formation upon TMZ. This was not due to enhanced cell death but rather due to increased senescence. Nuclear-trapped Survivin reduced homologous recombination (HR)-mediated double-strand break (DSB) repair, as evaluated by γH2AX foci formation and qPCR-based HR assay leading to pronounced induction of chromosome aberrations. Opposite, clones, expressing free-shuttling cytoplasmic but not nuclear-trapped Survivin, could repair TMZ-induced DSBs and evaded senescence. Mass spectrometry-based interactomics revealed, however, no direct interaction of Survivin with any of the repair factors. The improved TMZ-triggered HR activity in Surv-GFP was associated with enhanced mRNA and stabilized RAD51 protein expression, opposite to diminished RAD51 expression in SurvNESmut cells. Notably, cytoplasmic Survivin could significantly compensate for the viability under RAD51 knockdown. Differential Survivin localization also resulted in distinctive TMZ-triggered transcriptional pathways, associated with senescence and chromosome instability as shown by global transcriptome analysis. Orthotopic LN229 xenografts, expressing SurvNESmut exhibited diminished growth and increased DNA damage upon TMZ, as manifested by PCNA and γH2AX foci expression, respectively, in brain tissue sections. Consequently, those mice lived longer. Although tumors of high-grade glioma patients expressed majorly nuclear Survivin, they exhibited rarely NES mutations which did not correlate with survival. Based on our in vitro and xenograft data, Survivin nuclear trapping would facilitate glioma response to TMZ.

Parthenogenesis and cytoskeletal organization in ageing mouse eggs

Development ◽  
1986 ◽  
Vol 95 (1) ◽  
pp. 131-145
Author(s):  
Michelle Webb ◽  
Sarah K. Howlett ◽  
Bernard Maro
Keyword(s):  
Critical Concentration ◽  
Metaphase Plate ◽  
Meiotic Spindle ◽  
Cytoskeletal Organization ◽  
Spindle Poles ◽  
Different Types ◽  
Mouse Egg ◽  
Parthenogenetic Embryos

The cytoskeletal organization of the mouse egg changes during ageing in vivo and in vitro. The earliest change observed is the disappearance of the microfilament-rich area overlying the meiotic spindle. This is followed by the migration of the spindle towards the centre of the egg. Finally the spindle breaks down and the chromosomes are no longer organized on a metaphase plate. This spindle disruption may result from changes in the microtubule nucleating material found at the spindle poles and from an increase in the critical concentration for tubulin polymerization. It is possible to correlate the changes in the cytoskeletal organization of the egg occurring during ageing with the different types of parthenogenetic embryos obtained after ethanol activation. These observations strengthen the hypothesis that the actin-rich cortical area that overlies the meiotic spindle forms a domain to which the meiotic cleavage furrow is restricted and provides some insights into the mechanisms by which different types of parthenogenetic embryos are generated.

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