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Journal Articles - UP - MSI

Permanent URI for this collectionhttps://repository.unesco.gov.ph/handle/123456789/50

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1996 - 19992

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    Occurrence of closely spaced genes in the nuclear genome of the agarophyte Gracilaria gracilis
    Lluisma, Arturo O.; Ragan, Mark A. (Springer, 1999)
    Little is known about the structure and organisation of nuclear genomes in red algae. In particular, it is not known whether genes are densely or loosely packed, whether gene order is conserved, whether their genes tend to occur in one or multiple copies and whether their nuclear genes tend to be compact or interrupted by numerous introns. Sequencing of cloned genomic DNA from Gracilaria gracilis has begun to provide provisional answers to some of these questions. Four pairs of closely spaced genes have been found in G. gracilis upon sequencing genomic clones that contain genes for UDPglucose pyrophosphorylase, galactose-1-phosphate uridylyltransferase, the β subunit of tryptophan synthetase, and methionine sulphoxide reductase (a fifth pair of closely spaced genes, encoding polyubiquitin and aconitase, was reported earlier). An open reading frame with significant similarity to another known gene occurs close (< 1.7 kbp) to each of these genes. In two pairs the intergenic region is less than 400 bp in length, and for these the location of the putative polyadenylation signals indicates that the gene transcripts, encoded on opposite strands, have overlapping (hence complementary) 3′ regions. These somewhat unexpected findings begin to establish a basis for genome-level characterisation of red algae.
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    Quantification and characterization of nuclear genomes in commercial red seaweeds (Gracilariales) from the Philippines
    Kapraun, Donald F.; Lopez-Bautista, Juan; Trono, Gavino; Bird, Kimon T. (Springer, 1996-03)
    Eight species of Gracilariaceae from the Philippines, representing the genera Gracilaria, Gracilariopsis and Hydropuntia, were investigated to quantify and characterize their nuclear genomes. DNA reassociation kinetics were used to determine nuclear genome organization and complexity in six of these species. Results indicate the presence of three second order components corresponding to fast, intermediate and slow fractions. Repetitive sequences varied from 13–74% and unique DNA ranged from 26–84%. Microspectrophotometry with the DNA-localizing fluorochrome DAPI was used to quantify nuclear DNA contents. Comparisons of mean nuclear DNA (I f ) values to chicken erythrocytes (RBC) resulted in an estimate of 0.38–0.43 pg/2 C genomes for seven of the species investigated. Preliminary analyses of agar content and quality confirm the economic potential of Gracilaria firma, Gracilaria sp. 2 from Sorsogon and Gracilariopsis bailinae. Nuclear genome profiles developed from data for genome size, organization and complexity are compared with data for agar quantity and quality. Gel quality and quantity do not appear to be correlated with either large repetitive fraction DNA or a high degree of genome complexity.