The polymerase chain reaction method (PCR) has been applied to the detection of FMD viral RNA in samples taken from the calf during the clinical stage of FMD. Total RNA was extracted with a guanidinum thiocyanate-phenol-chloroform method and reverse transcribed using AMV-reverse transcriptase. cDNA was used as a template for the amplification by PCR of the 672 bp of the VP1 coding sequence. The amplified fragment of cDNA was cloned in the pBS(+) phagemid-containing sites recognized by Smal endonuclease and expressed in E. coli strain MV1193. The first DNA strand was sequenced and concurrently an amino acid sequence was established. Comparison between VP1 amino acid sequence of FMDV types A and earlier described type O was performed.
In the bovine genome we found two intrachromosomal DNA fragments flanked by inverted telomeric repeats (GenBank Accession Nos. AF136741 and AF136742). The internal parts of the fragments are homologous exclusively to the human sequences and to the consensus sequence of the L1MC4 subfamily of LINE-1 retrotransposons which are widespread among mammalian genomes. We found that distribution of homologous human sequences within our fragments is not random, reflecting a complicated pattern of insertion mechanisms of and maintenance of retrotransposons in mammalian genomes. One of the possible explanations of the origin of LINE-1 truncated elements flanked by inverted telomeric repeats in the bovine genome is that extrachromosomal DNA fragments may be modified by telomerase and subsequently, transferred into chromosomal DNA.
In this study, a novel repetitive sequence pTaq10 was isolated from the Taq I digest of the genomic DNA of the pseudocereal Chenopodium quinoa. Sequence analysis indicated that this 286-bp monomer is not homologous to any known retroelement sequence. FISH and Southern blot analysis showed that this sequence is characterized by an interspersed genomic organization. After FISH, hybridization signals were observed as small dots spread throughout all of the chromosomes. pTaq hybridization signals were excluded from 45S rRNA gene loci, but they partly overlapped with 5S rDNA loci. pTaq10 is not a species-specific sequence, as it was also detected in C. berlandieri.