DNA sequence of the skeletal muscle calcium release channel cDNA and verification of the Arg615----Cys615 mutation, associated with porcine malignant hyperthermia, in Norwegian landrace pigs

Isolation and sequencing of porcine lipoprotein lipase cDNA and its use in multiallelic restriction fragment length polymorphism detection

Porcine lipoprotein lipase (LPL) cDNA has been cloned and sequenced. The deduced amino acid sequence shows a high degree of identity to LPL from other species, and contains the Ser/His/Asp triade characteristic of serine proteases and esterases. A repetitive element is present in the 3'-untranslated region of the cDNA. A partial cDNA covering the coding region of LPL detects three restriction fragment length polymorphisms with HindIII. This represents the first marker assigned to porcine chromosome 14.

Identification of a polymorphic ryanodine receptor gene from Heliothis virescens (Lepidoptera: noctuidae)

cDNAs encoding the C-terminal 1172 amino acids of a ryanodine receptor (RyR) from the lepidopteran pest Heliothis virescens (Hv-RyR) have been cloned and characterised. Sequence comparisons, organisational studies on corresponding genomic regions and a genetic segregation analysis provide evidence for two polymorphic alleles of the Hv-RyR locus. Comparison of the Hv-RyR C-terminal amino acid sequence with equivalent regions of other RyRs reveals a high level of overall amino acid homology (74% identity with D. melanogaster and between 47.9 and 50.1% with vertebrate isoforms). Homologies are however not uniformly distributed, though regions of high and low similarity are consistent with patterns in other RyR isoforms. The structural similarity of Hv-RyR with other RyRs is also indicated by comparison of hydropathy profiles and other previously described functional domains. Such results are consistent with this region of Hv-RyR containing the Ca(2+) channel itself and being intimately involved in RyR regulation. Potential uses of the cDNAs described in the discovery and development of novel ryanodine like insecticides are discussed.

The porcine hormone-sensitive lipase gene: sequence, structure, polymorphisms and linkage mapping

The porcine hormone-sensitive lipase gene and its cDNA have been isolated and sequenced. Several putative regulatory sequences have been detected in the promotor region. The deduced amino acid sequence is 85% identical to the corresponding human, mouse and rat sequence. A search for polymorphisms revealed one intronic and one exonic polymorphism, the latter resulting in a conservative amino acid substitution. Linkage mapping located the LIPE gene close to the calcium release channel (CRC) locus on chromosome 6.

Intracellular calcium signalling in striated muscle cells

Calcium signalling in cells is dependent on a communication between channels/ transporters in two membrane structures: the cell membrane and the membranes of endo- and sarcoplasmic reticula (ER/SR). In general, cytosolic Ca2+ can be raised by influx of calcium over the cell membrane through three types of channels: voltage-, receptor-, and store-operated channels (VOCs, ROCs and SOCs). This small Ca2+ influx is most often amplified by a Ca2+ release from the ER/SR through two types of channels: the IP3-receptor and the ryanodine receptor (RyR), which are huge proteins identified and cloned in recent years. We focus on the 'synaptic' connection between VOCs (L-type calcium channels) and RyRs of the SR in heart and skeletal muscle. Depolarization of the cell membrane (an action potential) opens the VOC and moves it in the membrane. One VOC triggers opening of a certain number of underlying RyRs that together release a quantum of calcium from the SR, a calcium spark. The communication between the VOC and RyRs is probably achieved primarily by a mechanical link in skeletal muscle (voltage-controlled calcium release), and by the small inward calcium flux through the VOC in the heart (calcium-induced calcium release, CICR). Conditions as different as heart failure, myasthenia gravis, malignant hyperthermia, and skeletal muscle fatigue, may be examples of deteriorated control or function of the RyR.

The porcine skeletal muscle ryanodine receptor gene structure coding region 1 to 10614 harbouring 71 exons

The skeletal muscle ryanodine receptor (RYR1) belongs to a family of calcium release channels that are expressed in different tissues. The RYR1 gene is one of the largest genes characterized, so far, containing a 15253 nucleotide ORF in swine. To study the genomic organization of the porcine skeletal muscle ryanodine receptor gene we have isolated seven genomic fragments spanning 72.7 kb of chromosomal DNA of chromosome 6q12. This region harbours exons 1 to 71 coding for 3538 amino acids (69.6%) of the ryanodine receptor 1.

Long-range mapping of the calcium release channel and glucosephosphate isomerase loci using pulsed-field gel electrophoresis

Long range restriction maps of the calcium release channel (CRC) and glucosephosphate isomerase (GPI) loci have been constructed using pulsed field electrophoresis, Southern blotting and CRC- and GPI-specific probes. The maps, deduced from the restriction fragments detected by the probes, covered 1.1 and 0.3 Mb respectively and no overlap between the maps of these closely linked loci was detected. The minimal distance between the GPI and CRC loci was estimated to be at least 500 kb.

Isolation of region-specific probes from pig chromosome 6 by coincidence cloning

Coincidence cloning is a technique that permits the isolation of sequences common to two independent sources of complex DNA, and this method has been used to isolate a set of probes from a region of porcine Chromosome (Chr) 6 containing the loci for glucosephosphate isomerase (GPI) and the skeletal muscle calcium release channel (CRC). Porcine DNA was specifically PCR-amplified from a pig x hamster hybrid cell line containing the centromere region (p1.2-q1.2) of pig Chr 6 and other pig chromosome fragments by use of a porcine SINE specific primer with an EcoRI site in the 5'-end. Flow-sorted Chr 6 preparations were amplified with the same SINE primer, but with a SalI site in the 5'-end. The products were digested with EcoRI and SalI respectively, combined, denatured, and reannealed. The heteroduplex molecules, containing both an EcoRI and a SalI cohesive end, were selected by cloning in SalI/EcoRI-digested pUC13. Approximately 40% of the primary clones contained a single SalI/EcoRI-insert, indicating that they are coincidence clones. The average insert size was 1.4 kb. Fluorescence in situ hybridization of a pool of 34 coincidence clones to pig chromosomes showed a preferential labeling of the centromere region and of the q2.5-q2.7 region of pig Chr 6. Nineteen coincidence clones were hybridized to SINE-PCR products from flow-sorted pig Chr 6 and to pig x rodent hybrid cell lines. Eighteen clones gave positive signals correlated with the GPI/CRC content of the source DNAs.

Characterization of a porcine glucosephosphate isomerase-processed pseudogene at chromosome 1q1.6-1.7

A porcine glucosephosphate isomerase-processed pseudogene has been isolated and sequenced. The pseudogene has several base substitutions as well as an insertion and deletions, and is 83% homologous to the corresponding cDNA. It contains an intervening sequence of 565 bp, is truncated at the 3' end, and is flanked by direct repeats of seven nucleotides. Fluorescent in situ hybridization to porcine metaphase chromosomes localized the processed pseudogene to Chromosome (Chr) 1q1.6-1.7. A (GT)14(AT)15 microsatellite was detected close to the processed pseudogene.