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At least 469 records · Page 26Linked to original sources
PubMed1989

Sequence variability in three wheat germ agglutinin isolectins: products of multiple genes in polyploid wheat.

Three highly homologous wheat germ isolectins (95-97%) are distinct gene products in hexaploid wheat. The amino acid sequences of two of these [wheat germ agglutinin 1 (WGA1) and 2 (WGA2)] are compared with sequence data derived from a complementary DNA (cDNA) clone for the third isolectin (WGA3). This comparison includes three corrections to earlier amino acid sequence data of both WGA1 and WGA2 at positions 109 (from Ser to Phe), 134 (from Gly to Lys), and 150 (from Gly to Trp). These reassignments are based on new results from crystal structure refinement and amino acid sequence data of WGA1, as well as the recently determined nucleotide sequence of WGA3. In addition, the C-terminal residue of WGA1 has been revised to Gly171 and now differs from WGA2 (Ala171). Four other positions, Asn9, Ala53, Gly119, and Ser123, at which WGA1 and WGA2 are identical but differ from the DNA sequence of WGA3, were also reinvestigated by amino acid sequencing techniques and confirmed. Variability among the three isolectins is observed at a total of 10 sequence positions: 9, 53, 56, 59, 66, 93, 109, 119, 123, and 171. Pairwise comparisons indicate that WGA3 deviates to a much larger extent from WGA1 (at eight positions) and from WGA2 (at seven positions) than the latter from one another (at five positions). Eight of the 10 mutations are equally distributed between domains B and C, the two interior and more highly conserved of the four WGA domains (A, B, C, D). Correlation of the variable residues with the three-dimensional structure indicates that all except the two previously described B-domain residues, 56 and 59 (Wright and Olafsdottir 1986), are easily accommodated at the dimer surface. WGA3 displays a higher degree of inter-domain similarity than found in WGA1 and WGA2. Of the seven variable positions that are located in the domain core (residues 3-31), five are in perfect agreement with our earlier predicted domain ancestor sequence. This suggests that of the three isolectins WGA3 is most closely related to the common ancestral molecule.

Amino Acid Sequence↗
PubMed1993

Copia-like retrotransposable element evolution in diploid and polyploid cotton (Gossypium L.).

Copia-like retrotransposable elements were identified in allotetraploid cotton, Gossypium hirsutum, and two species representing its diploid progenitors, G. herbaceum and G. raimondii. These elements are present in high copy number in all three species. Because the two diploid genomic groups have been isolated on opposite sides of the world for 6-11 million years, horizontal transfer of elements between these species is highly unlikely. Elements were intensively sampled to generate a model of copia-like retrotransposable element evolution in systems where vertical transmission is the sole probable means of descent. Copia-like retrotransposon diversity is equally great in all three Gossypium species. Despite this high heterogeneity, analysis of 89 partial reverse transcriptase sequences resulted in the recognition of nine sharply differentiated retrotransposon lineages, each containing elements that share high sequence similarity. No evidence of horizontal transfer from other taxa was obtained. Phylogenetic analyses demonstrate that element topologies are incongruent with Gossypium phylogeny. Consideration of processes that obscure phylogenetic reconstruction of multigene families (including sampling error, variable degrees of orthology and paralogy, differential lineage age and lineage loss and/or proliferation) demonstrates that incongruence between organismal and retrotransposon trees is expected under conditions in which vertical processes are the sole means of transmission. Identification of closely related elements between species allowed rates of copia-like retrotransposon sequence evolution to be estimated as approximately 10(-9) nucleotide substitutions/site/year. These rates are consistent with the interpretation that these retrotransposons have been evolving under functional constraints for most of the time frame bracketed by the species studied. Extrapolation of these results to previous studies that sampled from more highly divergent taxa indicates that horizontal transfer need not be invoked to explain observed phylogenetic patterns.

Amino Acid Sequence↗
PubMed2003

Sample size for collecting germplasms--a polyploid model with mixed mating system.

The present paper discusses a general expression for determining the minimum sample size (plants) for a given number of seeds or vice versa for capturing multiple allelic diversity. The model considers sampling from a large 2 k-ploid population under a broad range of mating systems. Numerous expressions/results developed for germplasm collection/regeneration for diploid populations by earlier workers can be directly deduced from our general expression by assigning appropriate values of the corresponding parameters. A seed factor which influences the plant sample size has also been isolated to aid the collectors in selecting the appropriate combination of number of plants and seeds per plant. When genotypic multiplicity of seeds is taken into consideration, a sample size of even less than 172 plants can conserve diversity of 20 alleles from 50,000 polymorphic loci with a very large probability of conservation (0.9999) in most of the cases.

Alleles↗
PubMed2002

Polyploidization and centrosome hyperamplification in inflammatory bronchi.

OBJECTIVE AND DESIGN: Inflammatory and tumorous bronchi were screened in order to obtain new tumor relevant cytogenetic parameters. MATERIAL OR SUBJECTS: Bronchial cells of 32 patients were cultivated by standard cell culture procedures. METHODS: Tetraploidy and aneuploidy was determined by enumeration of chromosome 7 and 8 versus the number of centrosomes. The resulting data were correlated with histopathological data. RESULTS: Tetra- and aneuploidy of epithelial cells were detectable in 76% of tumor cell cultures, 75% of high grade inflammatory tissues and 40% of non- and low grade-inflammatory tissues. Additionally, we observed centrosome hyper-amplification and multipolar mitoses not only in the tumor but also in the early stages of inflammation. CONCLUSION: Inflammatory bronchi already show tumor-specific features and may consequently represent the preliminary genetic stage of cancer development in bronchi.

Adult↗
PubMed2005

Cross-species amplification of microsatellite loci within the dioecious, polyploid genus Actinidia (Actinidiaceae).

Microsatellite marker transfer across species in the dioecious genus Actinidia (kiwifruit) could offer an efficient and time-effective technique for use during trait transfer for vine and fruit improvement in breeding programmes. We evaluated the cross-species amplification of 20 EST-derived microsatellite markers that were fully informative in an Actinidia chinensis mapping family. We tested all 20 markers on 120 genotypes belonging to 21 species, 5 with varieties and/or chromosome races. These 26 taxa included 16 diploids, 7 tetraploids, 2 hexaploids and 1 octaploid, and represented all four taxonomic sections in the genus. All 20 markers showed some level of cross-species amplification. The most successful marker amplified in all genotypes from all species from all sections of the genus, the least successful amplified fragments only in A. chinensis and A. deliciosa. One species, A. glaucophylla, failed to amplify with all but 2 markers. PIC (Polymorphism information content) values were high, with 14 of 17 markers recording values of 0.90 and above. Sequence data demonstrated the presence of the microsatellite in all the amplified products. Sequence homology was less 5' of the microsatellite and increased toward the start codon of the translated region of the EST from which the marker was derived. The data confirm that EST-derived microsatellite markers from Actinidia species show cross-species amplification with high levels of polymorphism which could make them useful markers in breeding programmes.

Actinidiaceae↗
PubMed2006

Genetic mapping in sugarcane, a high polyploid, using bi-parental progeny: identification of a gene controlling stalk colour and a new rust resistance gene.

Modern sugarcane cultivars (Saccharum spp) are highly polyploïd and aneuploid interspecific hybrids (2n = 100-130). Two genetic maps were constructed using a population of 198 progeny from a cross between R570, a modern cultivar, and MQ76-53, an old Australian clone derived from a cross between Trojan (a modern cultivar) and SES528 (a wild Saccharum spontaneum clone). A total of 1,666 polymorphic markers were produced using 37 AFLP primer combinations, 46 SSRs and 9 RFLP probes. Linkage analysis led to the construction of 86 cosegregation groups for R570 and 105 cosegregation groups for MQ76-53 encompassing 424 and 536 single dose markers, respectively. The cumulative length of the R570 map was 3,144 cM, while that of the MQ76-53 map was 4,329 cM. Here, we integrated mapping information obtained on R570 in this study with that derived from a previous map based on a selfed R570 population. Two new genes controlling Mendelian traits were localized on the MQ76-53 map: a gene controlling the red stalk colour was linked at 6.5 cM to an AFLP marker and a new brown rust resistance gene was linked at 23 cM to an AFLP marker. Besides another previously identified brown rust resistance gene (Bru1), these two genes are the only other major genes to be identified in sugarcane so far.

Basidiomycota↗
PubMed2005

Wheat genome structure: translocations during the course of polyploidization.

The genomic organization of Triticum timopheevii (2n=28, AtAtGG) was compared with hexaploid wheat T. aestivum (2n=42, AABBDD) by comparative mapping using microsatellites derived from bread wheat. Genetic maps for the two crosses T. timopheevii var. timopheevii x T. timopheevii var. typica and T. timopheevii K-38555xT. militinae were constructed. On the first population, 121 loci were mapped, and on the second population 103 loci. The transferability of the wheat markers to T. timopheevii was generally better for the A genome-specific markers (76-78% produced amplification products; 26 and 29% were polymorphic) than for B genome-specific markers (54% produced amplification products; 14 and 16% were polymorphic). Of the D genome-specific markers, one third produced amplification products in T. timopheevii, but only 5 and 2% were polymorphic in the corresponding mapping populations. The maps constructed confirmed the previously described translocation between chromosome arms 6AtS and 1GS and revealed at least two yet unknown rearrangements on chromosomes 4At and 6At09. The presence of other translocations and rearrangements between T. timopheevii and T. aestivum was demonstrated by a variety of markers mapping to nonhomoeologous positions.

Chromosome Mapping↗
PubMed1977

Reassociation kinetics of polyploid hepatocyte DNA.

The state of ploidy of 4c hepatocytes is examined by kinetic analysis of DNA reassociation. The nucleotide sequences present in 4c hepatocyte DNA are found to be complementary to, and present in the same relative abundance as, those of the normal diploid genome. Therefore, these experiments indicate that the increased DNA content of 4c hepatocytes is due to the presence of four haploid genomes and not to selective replication of a subfraction of the diploid genome. The concept of ploidy, typically defined in terms of karyotypic and/or DNA content multiples is thus corroborated and extended by these experiments.

Animals↗