Biomedical subjects

David J Wolyn

Publications and source records attributed to David J Wolyn.

4 recordsLinked to original sources

PubMed2006

Petaloid-type cms in carrot is not associated with expression of atp8 (orfB).

Two different atp8 reading frames with divergent C-terminal extensions were identified in a sterility-inducing mitochondrial type (mitotype) of carrot; examination of three fertility-inducing mitotypes revealed atp8 reading frames that were either terminated at a position conserved among other plant atp8 genes or continued with unique C-terminal extensions. Similarities between the C-terminal extensions suggest ancient common ancestry, but the level of sequence divergence implies lack of functional conservation. Northern analysis indicated that the C-terminal extensions are transcribed and are present within the primary atp8 transcripts. Western analysis revealed that the products of the two extended atp8 reading frames encoded by the sterility-inducing mitotype are significantly smaller than those predicted by complete translation of their C-terminal extensions, but are slightly larger than the products from unextended reading frames. No alterations were observed in atp8 transcripts or proteins isolated from flowers of the sterility-inducing mitotype that were phenotypically fertile as a result of segregation for nuclear fertility-restoring Ms or Rf alleles, and thus, there is no evidence that expression of atp8 is directly involved in the petaloid cms phenotype in carrot.

3' Untranslated Regions↗

PubMed2005

A 60 kDa COX1 protein in mitochondria of carrot irrespective of the presence of C-terminal extensions in the cox1 reading frames.

An inverted repeat in the mitochondrial DNA of carrot mitochondrial type (mitotype) SW3 has been sequenced in the context of its up- and downstream genomic environments. The 3,159 bp repeat encodes rps7 and cox1, but the cox1 reading frame does not encode a stop codon at a position predicted by alignment with other plant cox1 genes; cox1 extends into both of the downstream flanking sequences as unique C-terminal extensions of 224 (cox1-1) or 284 (cox1-2) amino acids. Northern and RT-PCR analyses revealed that rps7 and cox1 are co-transcribed and RNA-edited. In three additional mitotypes of carrot, rps7 and cox1 are co-transcribed, but are present as single copies within the genome. In mitotype FG17, the cox1 gene has a C-terminal extension like cox1-1, but in mitotypes FW2 and FW4, the cox1 genes lack C-terminal extensions and have stop codons and 3' UTRs like those of other plant cox1 genes. The C-terminal extensions are transcribed in SW3 and FG17 and result in longer primary transcripts than those from FW2 and FW4. Western immunoblotting of mitochondrial proteins from all mitotypes detected COX1 products of the predicted unextended size in all mitotypes, irrespective of the presence of a C-terminal extension in the reading frame.

3' Untranslated Regions↗

PubMed2004

A mitochondrial plasmid and plasmid-like RNA and DNA polymerases encoded within the mitochondrial genome of carrot (Daucus carota L.).

The mitochondrial genome of mitochondrial type (mitotype) SW3 of carrot (Daucus carota L.) encodes intact reading frames for a RNA polymerase (Rpo) and a DNA polymerase (Dpo) similar to those encoded by linear mitochondrial plasmids from plants. A BLAST search of translated nucleotide sequences in GenBank revealed previously unreported plasmid-like Rpo or Dpo sequence fragments in many plant mitochondrial DNAs. Phylogenetic analyses of the relationships between mitochondrial (mt)DNA-encoded and plasmid-encoded Rpos and Dpos from plants suggest that the mitochondrial sequences were derived from integrated plant plasmid sequences. A linear mitochondrial plasmid was detected in a different mitotype (FG21) of carrot by Southern hybridization of the Rpo and Dpo to undigested mtDNAs. Transcripts of the mtDNA-encoded Rpo and Dpo in mitotype SW3 were detected by RT-PCR.

Amino Acid Sequence↗

PubMed2004

Light-response quantitative trait loci identified with composite interval and eXtreme array mapping in Arabidopsis thaliana.

Genetic analysis of natural variation in ecotypes of Arabidopsis thaliana can facilitate the discovery of new genes or of allelic variants of previously identified genes controlling physiological processes in plants. We mapped quantitative trait loci (QTL) for light response in recombinant inbred lines (RILs) derived from the Columbia and Kashmir accessions via two methods: composite interval mapping and eXtreme array mapping (XAM). After measuring seedling hypocotyl lengths in blue, red, far-red, and white light, and in darkness, eight QTL were identified by composite interval mapping and five localized near photoreceptor loci. Two QTL in blue light were associated with CRY1 and CRY2, two in red light were near PHYB and PHYC, and one in far-red light localized near PHYA. The RED2 and RED5 QTL were verified in segregating lines. XAM was tested for the identification of QTL in red light with pools of RILs selected for extreme phenotypes. Thousands of single feature polymorphisms detected by differential DNA hybridized to high-density oligo-nucleotide arrays were used to estimate allele frequency differences between the pools. The RED2 QTL was identified clearly; differences exceeded a threshold of significance determined by simulations. The sensitivities of XAM to population type and size and genetic models were also determined by simulation analysis.

Arabidopsis↗