Morphology, Relative DNA Content and Hypothetical Life Cycle of Phaeocystis Pouchetii (Prymnesiophyceae); with Special Emphasis on the Flagellated Cell Type

Sarsia ◽  
2002 ◽  
Vol 87 (5) ◽  
pp. 338-349 ◽  
Author(s):  
Anita Jacobsen
Keyword(s):  
Life Cycle ◽  
Dna Content ◽  
Cell Type ◽  
Phaeocystis Pouchetii ◽  
Relative Dna Content

scholarly journals Relationships among Morphological Characters, Isozymes Polymorphism and DNA Variability – the Impact on Lactuca Germplasm Taxonomy

2011 ◽  
Vol 39 (No. 2) ◽  
pp. 59-67 ◽  
Author(s):  
I. Doležalová ◽  
A. Lebeda ◽  
M. Dziechciarková ◽  
E. Křístková ◽  
D. Astley ◽  
...  
Keyword(s):  
Dna Content ◽  
Fragment Length Polymorphism ◽  
Morphological Variability ◽  
Morphological Characters ◽  
Aflp Analysis ◽  
Dapi Staining ◽  
Lactuca Species ◽  
Relative Dna Content ◽  
The Impact

Fifty one accessions of nineteen Lactuca species, the hybrid L. serriola × L. sativa and the related species Mycelis muralis were evaluated for morphological variability, esterase (EST) polymorphism, Amplified Fragment Length Polymorphism (AFLP) and relative DNA content. Sixteen Lactuca accessions were classified taxonomically on the basis of morphology, isozyme analysis and AFLP. Twenty-eight bands (isoforms) of EST were recorded allowing 82% of accessions to be distinguished. The relative DNA content, measured using flow-cytometry (DAPI staining), ranged from 2.02 pg in L. capensis to 17.96 pg in L. canadensis. The results from AFLP analysis and the relative DNA content measurement corresponded well with recent taxonomic classification of the genus Lactuca.  

scholarly journals A Two-Component System That Modulates Cyclic di-GMP Metabolism PromotesLegionella pneumophilaDifferentiation and Viability in Low-Nutrient Conditions

2019 ◽  
Vol 201 (17) ◽  
Author(s):  
Elisa D. Hughes ◽  
Brenda G. Byrne ◽  
Michele S. Swanson
Keyword(s):  
Life Cycle ◽  
Lifestyle Changes ◽  
Negative Regulator ◽  
Broth Culture ◽  
Cell Type ◽  
Two Component System ◽  
Term Survival ◽  
Component System ◽  
Content Type ◽  
Two Component

ABSTRACTDuring its life cycle, the environmental pathogenLegionella pneumophilaalternates between a replicative and transmissive cell type when cultured in broth, macrophages, or amoebae. Within a protozoan host,L. pneumophilafurther differentiates into the hardy cell type known as the mature infectious form (MIF). The second messenger cyclic di-GMP coordinates lifestyle changes in many bacterial species, but its role in theL. pneumophilalife cycle is less understood. Using anin vitrobroth culture model that approximates the intracellular transition from the replicative to the transmissive form, here we investigate the contribution toL. pneumophiladifferentiation of a two-component system (TCS) that regulates cyclic di-GMP metabolism. The TCS is encoded bylpg0278-lpg0277and is cotranscribed withlpg0279, which encodes a protein upregulated in MIF cells. The promoter for this operon is RpoS dependent and induced in nutrient-limiting conditions that do not support replication, as demonstrated using agfpreporter and quantitative PCR (qPCR). The response regulator of the TCS (Lpg0277) is a bifunctional enzyme that both synthesizes and degrades cyclic di-GMP. Using a panel of site-directed point mutants, we show that cyclic di-GMP synthesis mediated by a conserved GGDEF domain promotes growth arrest of replicativeL. pneumophila, accumulation of pigment and poly-3-hydroxybutyrate storage granules, and viability in nutrient-limiting conditions. Genetic epistasis tests predict that the MIF protein Lpg0279 acts as a negative regulator of the TCS. Thus,L. pneumophilais equipped with a regulatory network in which cyclic di-GMP stimulates the switch from a replicative to a resilient state equipped to survive in low-nutrient environments.IMPORTANCEAlthough an intracellular pathogen,L. pneumophilahas developed mechanisms to ensure long-term survival in low-nutrient aqueous conditions. Eradication ofL. pneumophilafrom contaminated water supplies has proven challenging, as outbreaks have been traced to previously remediated systems. Understanding the genetic determinants that supportL. pneumophilapersistence in low-nutrient environments can inform design and assessment of remediation strategies. Here we characterize a genetic locus that encodes a two-component signaling system (lpg0278-lpg0277) and a putative regulator protein (lpg0279) that modulates the production of the messenger molecule cyclic di-GMP. We show that this locus promotes bothL. pneumophilacell differentiation and survival in nutrient-limiting conditions, thus advancing the understanding of the mechanisms that contribute toL. pneumophilaenvironmental resilience.

Flow Cytometrically Determined DNA Content of Breast Carcinoma and Benign Lesions: Correlations with Histopathological Parameters

1986 ◽  
Vol 72 (2) ◽  
pp. 171-177 ◽  
Author(s):  
Raffaella Uccelli ◽  
Alberto Calugi ◽  
Donato Forte ◽  
Francesco Mauro ◽  
Paolo Polonio-Balbi ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Dna Content ◽  
Cell Subpopulation ◽  
Aneuploid Cell ◽  
Breast Carcinomas ◽  
Benign Lesions ◽  
Dna Index ◽  
Tissue Samples ◽  
Normal Tissues ◽  
Relative Dna Content

The relative DNA content of cellular samples from 54 patients affected by breast carcinomas and 20 affected by benign breast lesions (including 11 fibroadenomas) was measured by flow cytometry. All normal tissue samples and 17/20 (85%) specimens from benign lesions exhibited a cytometrically diploid DNA distribution, 3/20 (15%) benign lesions an abnormal DNA content, and 35/54 (65%) carcinomas at least one aneuploid cell subpopulation. Furthermore, 9/54 (17%) tumors were characterized by the presence of more than one aneuploid cell subpopulation. The results also indicate that flow cytometry can be used to recognize lymph nodes infiltrated by aneuploid cells. Statistically significant correlations were evidenced between the occurrence of aneuploidy or the ploidy level measured as DNA index and the nodal infiltration status. The percentage of S cells can also be extracted from DNA content distribution histograms. Statistically significant differences (p < 0.01) were also observed for the percentage of S cells between normal tissues (6.2±3.2 SD) and benign lesions (11.1±6.6 SD), normal tissues (6.2 ± 3.2 SD) and aneuploid tumors (19.7 ± 10.3 SD), benign lesions (11.1 ± 6.6 SD) and aneuploid tumors (19.7 ± 10.3 SD), and diploid (7.9 ± 4.0 SD) and aneuploid tumors (19.7 ± 10.3 SD).

scholarly journals УРОВНИ ПЛОИДНОСТИ И ОТНОСИТЕЛЬНОГО СОДЕРЖАНИЯ ДНК В КУЛЬТУРЕ КЛЕТОК И ТКАНЕЙ РАСТЕНИЙ IN VITRO

2016 ◽  
Vol 6 (3) ◽  
pp. 33-38
Author(s):  
M. V. Skaptsov ◽  
M. A. Krasnoborodkina ◽  
M. G. Kutsev ◽  
S. V. Smirnov ◽  
A. I. Shmakov ◽  
...  
Keyword(s):  
Genome Size ◽  
Ploidy Level ◽  
Dna Content ◽  
Nuclear Dna Content ◽  
Callus Cultures ◽  
Plant Genome ◽  
Control Group ◽  
Ms Medium ◽  
Relative Dna Content

<p>We presented results of variations in the ploidy level and the genome size of the <em>R. acetosa</em> regenerants. These regenerants was obtained by indirect and direct morphogenesis in in vitro culture. Explants were prepared from seedlings on the three-leaf stage of plant development. More than 100 explants were used to stimulate the indirect and direct morphogenesis. Mesophilic explants were cultured on the MS nutrient medium containing auxin to callus proliferation (2 mg/L NAA, 1 mg/L BA). Cultivation of the callus was maintained for 4 weeks followed by an indirect morphogenes. Indirect morphogenesis stimulated on the MS medium with cytokinin and gibberellic acid predominance (0.5 mg/L BA, 0.2 mg/L GA3). Direct stimulate morphogenesis from the apical meristem of seedlings on nutrient media with a predominance of cytokinins (1 mg/L BA, 0.25 mg/L NAA). Rhizogenesis have stimulated by transferring of the regenerants to the ½MS medium supplemented with 0.2 mg/L of NAA. Research of a ploidy level and genome size was performed by flow cytometry used propidium iodide staining with <em>Vicia faba</em> cv “Innovec” (2C=26.90 pg) as internal DNA standard. We calculated the relative DNA content (2C) for <em>R. acetosa</em> equal to 6,98 pg. Cytogenetical analisis showed that the maximum genome size variation recorded for regenerants obtained through the indirect morphogenesis. Variations in the genome size of the regenerants obtained by direct morphogenesis deviates from the control group to 0.30 pg (2С=7.28 pg) and after indirect morphogenesis to 1.04 pg (2С=8.2 pg). Cytogenetical analysis of the regenerated plants showed the presence of different somatic chromosome numbers ranging from 2n = 14 to 2n = 28. The relative DNA content of tetraploid forms was 11.87 pg. In our study was shown, that the most effective method of plant conservation in the <em>in vitro</em> culture is a direct morphogenesis. Analysis of the relative nuclear DNA content and chromosome counts of regenerants obtained by indirect morphogenesis from the callus cultures showed significant variations in the DNA content, as well as the appearance of polyploid forms. Therefore, long-term cultivation of callus cultures increases the probability of genomic aberrations, which reduces the stability of the plant genome.</p>

scholarly journals A Two-Component System that Modulates Cyclic-di-GMP Metabolism PromotesLegionella pneumophilaDifferentiation and Viability in Low-Nutrient Conditions

2019 ◽  
Author(s):  
Elisa D. Hughes ◽  
Brenda G. Byrne ◽  
Michele S. Swanson
Keyword(s):  
Life Cycle ◽  
Bacterial Species ◽  
Lifestyle Changes ◽  
Negative Regulator ◽  
Broth Culture ◽  
Cell Type ◽  
Two Component System ◽  
Term Survival ◽  
Component System ◽  
Two Component

ABSTRACTDuring its life cycle, the environmental pathogenLegionella pneumophilaalternates between a replicative and a transmissive cell type when cultured in broth, macrophages, or amoebae. Within a protozoan host,L. pneumophilafurther differentiates into the hardy cell type known as the Mature Infectious Form (MIF). The second messenger cyclic-di-GMP coordinates lifestyle changes in many bacterial species, but its role in theL. pneumophilalife cycle is less understood. Using anin vitrobroth culture model that approximates the intracellular transition from the replicative to transmissive form, here we investigate the contribution toL. pneumophiladifferentiation of a two-component system (TCS) that regulates cyclic-di-GMP metabolism. The TCS is encoded bylpg0278-lpg0277and is co-transcribed withlpg0279, which encodes a protein upregulated in MIF cells. Using agfp-reporter, we demonstrate that the promoter for this operon is RpoS-dependent and induced in nutrient-limiting conditions that do not support replication. The response regulator of the TCS (Lpg0277) is a bifunctional enzyme that both synthesizes and degrades cyclic-di-GMP. Using a panel of site-directed point mutants, we show that cyclic-di-GMP synthesis mediated by a conserved GGDEF domain promotes growth arrest of replicativeL. pneumophila, production of pigment and poly-3-hydroxybutyrate storage granules, and viability in nutrient-limiting conditions. Genetic epistasis tests predict that the MIF protein Lpg0279 acts upstream of the TCS as a negative regulator. Thus,L. pneumophilais equipped with a regulatory network in which cyclic-di-GMP stimulates the switch from a replicative to a resilient state equipped to survive in low-nutrient environments.IMPORTANCEAlthough an intracellular pathogen,L. pneumophilahas developed mechanisms to ensure long-term survival in low-nutrient aqueous conditions. Eradication ofL. pneumophilafrom contaminated water supplies has proven challenging, as outbreaks have been traced to previously remediated systems. Understanding the genetic determinants that supportL. pneumophilapersistence in low-nutrient environments can inform design of remediation methods. Here we characterize a genetic locus that encodes a two-component signaling system (lpg0278-lpg0277) and a putative regulator protein (lpg0279) that modulates production of the messenger molecule cyclic-di-GMP. We show that this locus promotes bothL. pneumophilacell differentiation and survival in nutrient-limiting conditions, thus advancing our understanding of the mechanisms that contribute toL. pneumophilaenvironmental resilience.

Sign in / Sign up

Export Citation Format

Share Document