Interclonal Variability Research Articles

Genetic structure and identification of Populus deltoides clones based on allozymes

The allelic constitution of 30 Populus deltoides Marsh, clones selected in Canada and United States was determined for 37 allozyme loci coding for 12 enzyme systems in root tips. The enzymes were assayed by horizontal starch gel electrophoresis. One common allele was found at each locus in all clones. The interclonal allozyme variability was controlled by 12 loci. The average proportion of heterozygous loci per clone was 4.7%. There were 23 unique multilocus genotypes among 30 clones. On average, unique genotypes differed from each other at 4.33 loci. Principal-component analysis of clonal genotypes at 12 polymorphic loci indicated 8 loci to be the most differentiating for the clones. The first three principal components accounted for 47.6% of the total variation in 12 polymorphic loci. The ordination and grouping of the clones on principal components 1, 2, and 3 portrayed clonal relationships. Clones from the same small nautral population at Cherry Beach, Ont., and five clones of P. deltoides var. occidentalis were in the same group. There was no separation of clones of two varieties, P. deltoides var. deltoides and P. deltoides var. occidentalis. These results and their usefulness were discussed with reference to identification, certification, registration, and relationships of clones.Key words: Populus deltoides Marsh., allozymes, multilocus genotypes, clone characterization, clonal relationships, poplars.

Multilocus genetic structure, characterization, and relationships of Populus × canadensis cultivars

The genotypes of 21 clones of 18 Populus × canadensis Moench cultivars ('Baden 431', 'Blanc du Poitou', 'Canada Blanc', 'DN44', 'Dorskamp 925', 'Eugenei', 'Gelrica', 'Grandis', 'Heidemij', 'I-55/56', 'I-132/56', 'I-262', 'Jacometti', 'Ostia', 'Regenerata', 'Robusta', 'Steckby', and 'Zurich 03/3') were determined for 31 allozyme loci coding for 9 enzyme systems in root tips. Horizontal starch gel electrophoresis was used to assay the enzymes. All clones had allozyme gene and allele contribution from both P. deltoides Marsh, and P. nigra L. The interclonal allozyme variability was controlled by nine loci. 'Canada Blanc' and 'Ostia' shared the same 31-locus genotypes, whereas each of the remaining 19 clones, including 3 clones of 'Robusta' and 2 clones of 'Jacometti', had unique multilocus genotypes. On average, unique genotypes differed from each other at 3.59 loci. Principal-component analysis of the clonal genotypes at 9 variable loci indicated 4 loci (Idh-2, Idh-3, Mdh-4, and Idh-1) to be the most discriminating among the clones. The first two principal components accounted for 48% of the total variance in the nine loci. Clones on the principal component analysis ordination (principal components 1 and 2) were separated into 3 groups; 14 belonged to one group and 5 to a second group. 'Blanc du Poitou' was widely separated from all others. 'Canada Blanc' and 'Steckby' showed the highest genetic interrelationships. Three 'Robusta' clones and two 'Jacometti' clones were in the same group., The interrelationships among the clones based on allozyme genotypes were in general agreement with their speculated origin and (or) morphology.Key words: Populus × canadensis, allozymes, multilocus genotypes, clone–cultivar identification, clone relationships.

Allozymes as aids for identification and differentiation of some Populus maximowiczii Henry Clonal varieties

Allozyme genotypes of nine Populus maximowiczii clonal varieties originating in China and Japan were determined for 35 loci coding for 12 enzyme systems in root tips. The interclonal variability was controlled by 13 polymorphic loci. Seven unique multilocus genotypes were identified. The unique genotypes differed from each other on an average of 6.73 loci. Principal Component (PC) 1 from the Principal Component Analysis of the clonal allozyme genotype data separated the clones into two distinct groups; one consisting of clones of Chinese and another clones of Japanese origins. Japanese clones of different sources were further differentiated by the PC 2. Allozyme genotypes were found to be useful for identification of clones and differentiation of their geographic origins.

Platelet aggregation in plasm and whole blood and ATP secretion in hypoxic cats

McA-RH 7777 hepatoma cell line has been cloned twice at a week's interval (analytical cloning). Alpha-fetoprotein (AFP) phenotypes of primary and secondary clones from 46 primary clones were analyzed. High interclonal variability exceeded the mutation rate by several orders. The interclonal differences have been also found in the variability rates.

Methylation patterns in the gene for the alpha subunit of chorionic gonadotropin are inherited with variable fidelity in clonal lineages of human fibroblasts.

Cytosine methylation in DNA of an endogenous single-copy gene locus, the alpha-subunit of human chorionic gonadotropin (alpha-hCG), was assessed in a mass culture and individual clonal lineages of human diploid fibroblasts. Progressive hypomethylation at -CCGG- sites in this gene occurred during the replicative lifespan of the mass culture and was shown to arise randomly during clonal expansion. Thus, some clones and subclones lost -CCGG- methylation in the alpha-hCG gene region while others maintained essentially complete methylation. These data indicate significant interclonal variability in the fidelity with which DNA methylation is transmitted in an endogenous gene.

Influence of temperature and cell size on the division rate and chemical content of the diatom Chaetoceros curvisetum Cleve

Cell size and temperature influenced the division rate and chemical content of the diatom Chaetoceros curvisetum Cleve when grown at 15, 20 and 25°C in nutrient replete media. Cell-size dependent trends of division rate in individual clones changed with temperature in a complex fashion. Considerable interclonal variability in division rate within a restricted range of cell sizes was also found. Cellular levels of carbon, nitrogen, protein, chlorophyll a, and silicon were linearly related to cell size. Cellular levels of carbon and chlorophyll per unit volume and silicon per unit surface area changed with temperature. No temperature effect on cellular levels of nitrogen and protein was found.