|
| ||
|
|
||
Chromosome Size (chromosome + size)
Selected AbstractsGeneration of a flanking sequence-tag database for activation-tagging lines in japonica riceTHE PLANT JOURNAL, Issue 1 2006Dong-Hoon Jeong Summary We have generated 47 932 T-DNA tag lines in japonica rice using activation-tagging vectors that contain tetramerized 35S enhancer sequences. To facilitate use of those lines, we isolated the genomic sequences flanking the inserted T-DNA via inverse polymerase chain reaction. For most of the lines, we performed four sets of amplifications using two different restriction enzymes toward both directions. In analyzing 41 234 lines, we obtained 27 621 flanking sequence tags (FSTs), among which 12 505 were integrated into genic regions and 15 116 into intergenic regions. Mapping of the FSTs on chromosomes revealed that T-DNA integration frequency was generally proportional to chromosome size. However, T-DNA insertions were non-uniformly distributed on each chromosome: higher at the distal ends and lower in regions close to the centromeres. In addition, several regions showed extreme peaks and valleys of insertion frequency, suggesting hot and cold spots for T-DNA integration. The density of insertion events was somewhat correlated with expressed, rather than predicted, gene density along each chromosome. Analyses of expression patterns near the inserted enhancer showed that at least half the test lines displayed greater expression of the tagged genes. Whereas in most of the increased lines expression patterns after activation were similar to those in the wild type, thereby maintaining the endogenous patterns, the remaining lines showed changes in expression in the activation tagged lines. In this case, ectopic expression was most frequently observed in mature leaves. Currently, the database can be searched with the gene locus number or location on the chromosome at http://www.postech.ac.kr/life/pfg/risd. On request, seeds of the T1 or T2 plants will be provided to the scientific community. [source] Cytology, palynology, and taxonomy of Asteropyrum and four other genera of RanunculaceaeBOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2006QIONG YUAN A karyomorphological study of two species in Asteropyrum (Ranunculaceae) and five in presumably related genera (one each in Caltha, Coptis, and Dichocarpum and two in Thalictrum) reveals close similarities between Asteropyrum and Caltha, but obvious differences between Asteropyrum and Coptis, Dichocarpum, and Thalictrum, in some karyological features, such as the structure of the interphase nuclei, chromosome size, basic chromosome number, and condensation behaviour of chromosomes during the mitotic prophase. The chromosomes of Asteropyrum are categorized as being of the R-type and the basic chromosome number is confirmed as x = 8, indicating a possible close affinity of Asteropyrum to members in the subfamily Helleboroideae, in particular to Caltha and its allies. Asteropyrum peltatum and Asteropyrum cavaleriei are shown to be more or less differentiated from each other in gross morphology and palynology, and somewhat independent in geographical distribution, albeit with intermediate forms occurring where their distribution zones overlap. It seems justifiable to treat them as two subspecies of A. peltatum. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society, 2006, 152, 15,26. [source] Karyotype morphology and cytogeography in Brunnera and Cynoglottis (Boraginaceae)BOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2001MASSIMO BIGAZZI A comparative study of karyotype morphology and heterochromatin patterns in Brunnera and Cynoglottis (Boraginaceae) was carried out with traditional methods and Giemsa C-banding. Two polymorphic species of Cynoglottis, each with two subspecies, and two of Brunnera were investigated using native population samples from the central-eastern Mediterranean and Middle East. Pollen size of these samples was measured to investigate relationships with ploidy level. C. barrelieri subsp. barrelieri and subsp. serpentinicola are characterized by In = 18 and smaller pollen grains in contrast to C. chetikiana subsp. chetikiana and subsp. paphlagonica, which are fundamentally tetraploid with 2n = 36. The occurrence of cytotypes with 2n ,/2 and 2n = 24 in both subspecies of C. chetikiana, however, would suggest x = 6 as the original haploid number and x = 9 as a derived one. Furthermore, the finding of a hypoploid cytotype with 2n = 16 in C. barrelieri ssp. barrelieri was consistent with previous reports and suggested relationships with Anchusa. Karyoevolutionary processes possibly associated with such a wide chromosome variation in Cynoglottis are discussed. Brunnera macrophylla and B. orientalis share a complement of 2n= 12 and an apparently identical karyotype, which differs from Cynoglottis in terms of asymmetry, chromosome size and morphology. A basic C-banding style was present in Brunnera and Cynoglottis, but heterochromatin content increased from the former to the latter. The parallel increase in chromosome number, heterochromatin content and size of the pollen from Brunnera to Cynoglottis may reflect an evolutionary progression, and is consistent with the supposed ancient origin of Brunnera. [source] Phylogeny and Nucleomorph Karyotype Diversity of Chlorarachniophyte AlgaeTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 5 2007TIA D. SILVER ABSTRACT. Chlorarachniophytes are flagellated and/or reticulopod-forming marine algae with chlorophyll a - and b -containing plastids of secondary endosymbiotic origin. They are one of only two algal groups known to possess a "nucleomorph" (i.e. the remnant nucleus of the eukaryotic endosymbiont that donated the plastid). Apart from the recently sequenced nucleomorph genome of Bigelowiella natans, little is known about the size, structure, and composition of chlorarachniophyte nucleomorph genomes. Toward the goal of better understanding nucleomorph genome diversity, as well as establishing a phylogenetic framework with which to interpret variation in chlorarachniophyte morphology, ultrastructure, and life cycle, we are studying a wide range of chlorarachniophyte strains from public culture collections and natural habitats. We have obtained 22 new chlorarachniophyte nuclear and nucleomorph 18S rRNA gene (18S rDNA) sequences and nucleomorph genome size estimates for 14 different strains. Consistent with previous studies, all of the chlorarachniophytes examined appear to possess three nucleomorph chromosomes. However, our results suggest considerable variation in nucleomorph genome size and structure, with individual chromosome sizes ranging from ,90 to ,210 kbp, and total genome sizes between ,330 kbp in Lotharella amoebiformis and ,610 kbp in unidentified chlorarachniophyte strain CCMP622. The significance of these phylogenetic and nucleomorph karyotype data is discussed. [source] | ||||||||||