Clonal Variation (clonal + variation)

Distribution by Scientific Domains


Selected Abstracts


Osmoprotective Effect of Glycine Betaine on Thrombopoietin Production in Hyperosmotic Chinese Hamster Ovary Cell Culture: Clonal Variations

BIOTECHNOLOGY PROGRESS, Issue 5 2000
Tae Kyung Kim
When 23 recombinant Chinese hamster ovary (rCHO) cell clones were cultivated in hyperosmolar medium resulting from NaCl addition (533 mOsm/kg), their specific thrombopoietin (TPO) productivity (qTPO) was increased. However, due to depressed cell growth at elevated osmolality, no enhancement in the maximum TPO titer was made in batch cultures of all 23 clones. To test the feasibility of using glycine betaine, known as a strong osmoprotective compound, for improved TPO production in hyperosmotic rCHO cell cultures, hyperosmotic batch cultures of 23 clones were performed in the presence of 15 mM glycine betaine. Glycine betaine was found to have a strong osmoprotective effect on all 23 clones. Inclusion of 15 mM glycine betaine in hyperosmolar medium enabled 22 clones to grow at 542 mOsm/kg, where most clones could not grow in the absence of glycine betaine, but at a cost of reduced qTPO. However, the relative decrease in qTPO varied significantly among clones. Thus, efficacy of the simultaneous use of hyperosmotic pressure and glycine betaine as a means to improve foreign protein production was variable among clones. Six out of 23 clones displayed more than a 40% increase in the maximum TPO titer in the hyperosmolar medium containing glycine betaine, compared with that in the standard medium with a physiological osmolality. Taken together, the results obtained here emphasize the importance of selection of clones for the successful use of hyperosmotic pressure and glycine betaine as an economical means to improve TPO production. [source]


Clonal variation in morphological and physiological responses to irradiance and photoperiod for the aquatic angiosperm Potamogeton pectinatus

JOURNAL OF ECOLOGY, Issue 5 2002
Jörn Pilon
Summary 1Widely distributed plants are exposed to contrasting gradients in irradiance and photoperiod across latitude. We investigated the relative contribution of local specialization and phenotypic plasticity to variation in plant growth for three clones of the aquatic angiosperm Potamogeton pectinatus L., originating from 42.5 to 68° N. Plants were grown at a factorial combination of two irradiances (50 and 350 µmol m,2 s,1) and three photoperiods (13, 16 and 22 h) and morphology, gas-exchange rate and biomass accumulation were recorded. 2The overall response to variation in irradiance and photoperiod was similar for all three clones. 3Differences in irradiance resulted in strong acclimative changes in morphological and physiological characteristics. At low irradiance, pronounced vertical shoot extension compensated for the limited plasticity in leaf area production, while photosynthetic capacity, apparent quantum yield and total chlorophyll concentration increased. As a result, biomass yield at the end of the experimental period was similar in both treatments. 4A decrease in photoperiod also resulted in plastic changes in morphology (increase of leaf biomass per unit plant biomass) and physiology (increase of photosynthetic capacity). However, these acclimative responses did not fully compensate for differences in photoperiod, since biomass was significantly lower under 13 and 16 h photoperiods than at 22 h. 5P. pectinatus is therefore phenotypically plastic, rather than locally specialized to differences in irradiance and photoperiod. [source]


Population Genetic Structure of the Medicinal Plant Vitex rotundifolia in China: Implications for its Use and Conservation

JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 9 2008
Yuan Hu
Abstract Vitex rotundifolia L. is an important plant species used in traditional Chinese medicine. For its efficient use and conservation, genetic diversity and clonal variation of V. rotundifolia populations in China were investigated using inter-simple sequence repeat markers. Fourteen natural populations were included to estimate genetic diversity, and a large population with 135 individuals was used to analyze clonal variation and fine-scale spatial genetic structure. The overall genetic diversity (GD) of V. rotundifolia populations in China was moderate (GD = 0.190), with about 40% within-population variation. Across all populations surveyed, the average within-population diversity was moderate (P = 22.6%; GD = 0.086). A relatively high genetic differentiation (Gst = 0.587) among populations was detected based on the analysis of molecular variance data. Such characteristics of V. rotundifolia are likely attributed to its sexual/asexual reproduction and limited gene flow. The genotypic diversity (D = 0.992) was greater than the average values of a clonal plant, indicating its significant reproduction through seedlings. Spatial autocorrelation analysis showed a clear within-population structure with gene clusters of approximately 20 m. Genetic diversity patterns of V. rotundifolia in China provide a useful guide for its efficient use and conservation by selecting particular populations displaying greater variation that may contain required medicinal compounds, and by sampling individuals in a population at >20 m spatial intervals to avoid collecting individuals with identical or similar genotypes. [source]


Variation of linalool and geraniol content within two pairs of aromatic and non-aromatic grapevine clones

AUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 2 2009
E. DUCHÊNE
Abstract Backgrounds and Aims:, In order to assess the suitability of some genotypes for functional genomics studies on terpenol synthesis in grapevine, two pairs of cultivars differing in their aromatic pattern were compared: Gewurztraminer and Savagnin Rose and two clones of Chardonnay (76 and 809). Methods and Results:, The genetic analysis based on microsatellite markers showed that Gewurztraminer and Savagnin Rose were clones derived from a single mother plant. The same result was found for Chardonnay clones 76 and 809. Analyses of wines, musts and berries showed that linalool and geraniol were present only at very low concentrations in Savagnin Rose and Chardonnay 76, both considered as non-aromatic cultivars. On the contrary, Gewurztraminer was characterised by a high geraniol content and Chardonnay 809 by a profile where linalool was predominant. Results obtained in the vineyard were consistent with data on fruiting cuttings in the greenhouse. Analyses of the terpenol content of berries from self-progenies plants of Gewurztraminer and Chardonnay 809 showed that this trait was heritable. Conclusions:, We provide evidence that clonal variation, through somatic mutations, can modify the aromatic profile of fruits. Significance of the Study:, We have characterised grapevine clones consistently differing in the terpenol content of both grapes and wines. Such plant material is appropriate for functional genomics studies. [source]


Insecticide resistance in the aphid Myzus persicae (Sulzer): chromosome location and epigenetic effects on esterase gene expression in clonal lineages

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2003
LINDA M. FIELD
Insecticide treatment of the aphid Myzus persicae (Sulzer) has led to the evolution of several insecticide resistance mechanisms, including the detoxification of insecticides by elevated esterases. This results from amplification of one of two closely related esterase genes (E4 or FE4) with up to 80 copies in the most resistant aphids. The amplified E4 genes are at a single site linked to a chromosomal translocation and resistance can be unstable. Individuals within a clone lose their elevated esterase and resistant phenotype, a good example of ,clonal variation'. This loss of esterase is accompanied by a loss of the corresponding mRNA but the amplified genes are retained with no detectable sequence differences. However, the expressed E4 genes contain 5-methylcytosine, which is lost at the same time as the genes are turned off. This is in direct contrast with vertebrate genes where DNA methylation causes gene silencing, but it does suggest that the resistant phenotype in M. persicae is under epigenetic control. One hypothesis is that 5-methylcytosine in E4 genes facilitates expression by preventing the production of incorrectly initiated transcripts. It is interesting that we have never detected silencing of amplified FE4 genes, possibly because they are at multiple loci and therefore less likely to be subject to synchronous control. © 2003 The Linnean Society of London. Biological Journal of the Linnean Society, 2003, 79, 107,113. [source]


Limited genetic diversity of Candida albicans in fecal flora of healthy volunteers and inpatients: a proposed basis for strain homogeneity in clinical isolates

MYCOSES, Issue 9-10 2002
R. Khatib
Candida albicans; Gastrointestinalflora; Molekulare Typisierung Summary. Molecular analysis of Candida albicans isolates from individual patients often yields a single strain at multiple sites. Whether this strain-limitation is due to virulence factors favoring the invasive strain or to lack of genetic diversity in the gastrointestinal reservoir is uncertain. We elected to study C. albicans genotypes in the fecal flora among healthy volunteers and inpatients. Self-obtained stool swabs or stool samples were cultured on inhibitory mold agar. From each subject with C. albicans, nine colonies were randomly selected, individually propagated, and typed utilizing random amplified polymorphic DNA. Colonies were considered identical (all bands matched), related variants (one to three unique bands), or distinct strains (more than three unique bands). Analysis showed a single clone in 33/43 (76.7%) volunteers and 6/18 (33.3%) inpatients (P = 0.018), two to four related variants in eight (18.6%) volunteers and 10 (55.6%) inpatients, and two distinct strains in two volunteers (4.6%) and two inpatients (11.1%). Strain variation was more common in females (33.5 versus 5.6%; P = 0.04) and tended to increase with age (r = 0.245, P = 0.06). These findings illustrate that most healthy subjects harbor a single strain of C. albicans in the fecal flora. This strain may undergo genetic evolution leading to minor clonal variations. The mechanisms for strain selection, maintenance and possible evolution remain to be delineated. Zusammenfassung. Molekularanalysen von Candida albicans -Isolaten von individuellen Patienten zeigen oft einen individuellen Stamm an mehreren Lokalisationen. Ob diese Beschränkung auf einer Förderung durch Virulenzfaktoren des beherbergten Stammes oder auf einem Mangel an genetischer Diversität im Gastrointestinaltrakt beruht, ist unbekannt. Wir untersuchten daher die C. albicans Genotypen in der Fäkalflora von Gesunden und von Krankenhauspatienten. Selbstgewonnene Stuhlabstriche und Stuhlproben wurden auf einem schimmelpilzhemmenden Nährmedium kultiviert. Von jedem Probanden wurden 9 Kolonien randomisiert ausgewählt, individuell subkultiviert und RAPD-typisiert. Die Kolonien wurden wie folgt bewertet: klonal identisch: sämtliche Banden identisch; klonal verwandt: 1,3 Banden nicht identisch; klonal unterschiedlich: >,3 Banden nicht identisch. Die Analyse zeigte Klonidentität bei 33/43 (77%) Gesunden und 6/18 (33%) bei Hospitalisierten (P = 0.018); Klonverwandtschaft wurde bei 8 (19%) Gesunden und 10 (56%) Hospitalisierten gefunden und zwei Hospitalisierten (11%). Klonvariation war häufiger bei Frauen (33.5 vs. 5.6%; P = 0.04) und nahm mit dem Lebensalter zu (r = 0.245, P = 0.06). Diese Resultate belegen, dass die Mehrzahl Gesunder jeweils nur einen Stamm in der Fäkalflora beherbergt. Dieser kann genetisch geringgradig klonal variieren. Die hierbei wirksamen Mechanismen bedürfen noch der Aufklärung. [source]