MicroRNAs in equine veterinary science.

MicroRNAs are small noncoding RNAs that play a pivotal role in diverse cellular processes through post-transcriptional regulation of gene expression. The dysregulation of specific microRNAs is associated with disease development and progression. In this review, we summarise how microRNAs modulate gene expression, and explain microRNA nomenclature. We discuss the potential applications of microRNAs in equine disease diagnosis and treatment, in the context of the sum of current knowledge about microRNA expression in normal and diseased equine tissues.

Metastasis-associated microRNA expression in canine uveal melanoma.

BACKGROUND: Uveal melanoma (UM) is the most common primary intraocular tumour in dogs. There is no effective means of predicting whether a tumour will metastasize. microRNA (miRNA) metastasis signatures have been identified for several human cancers, including UM. AIMS: In this study we investigated whether metastasizing and non-metastasizing canine UMs can be distinguished by miRNA expression levels. MATERIALS AND METHODS: miRNA microarray profiling was used to compare miRNA expression in 8 metastasizing and 12 non-metastasizing formalin-fixed, paraffin-embedded (FFPE) primary UM biopsies. RESULTS: Fourteen miRNAs exhibited statistically significant differences in expression between the metastasizing and non-metastasizing tumours. Class prediction analysis pinpointed 9 miRNAs which categorized tumours as metastasizing or non-metastasizing with an accuracy of 89%. Of the discriminating miRNAs, 8 were up-regulated in metastasizing UM, and included 3 miRNAs implicated as potential "metastasis activators" in human cutaneous melanoma. The expression of 4 of the miRNAs was subsequently measured using the quantitative reverse transcription polymerase chain reaction (RT-qPCR), and their up-regulation in metastasizing tumours validated. CONCLUSION: miRNA expression profiles may potentially be used to identify UMs that will metastasize, and miRNAs that are up-regulated in metastasizing tumours may be targets for therapeutic intervention.

Using lymph node fine needle aspirates for gene expression profiling of canine lymphoma.

Conventional classification schemes for canine lymphomas do not discriminate between phenotypically indistinct tumours that may exhibit differences in behaviour. Transcriptional profiling has the potential to afford objective clinically relevant stratification of canine lymphomas, and its sensitivity means that prognostic assays could be performed on tumour needle aspirates collected without anaesthesia. In this pilot study, we compared the expression profiles derived from surgical biopsies and fine needle aspirates of five lymphomas. The aspirates yielded expression profiles of equivalent complexity and strong similarity (median correlation Coefficient = 0.911) to those generated from corresponding surgical biopsies. Differences in gene expression observed between the two tissue sources suggest that the aspirates represent a purer source of lymphocytes. Despite the absence of a standardized sample collection protocol, the aspirates yielded expression profiles of consistently high quality suggesting that they represent a robust source of tumour tissue for a potential transcriptional profile-based prognostic assay for canine lymphomas.

Preliminary analysis of genomic abnormalities in canine meningiomas.

Cytogenetic detection of unbalanced genomic aberrations in tumours is a strategy for the identification of tumour suppressor genes and oncogenes. When considered in concert with clinical data, the approach also represents a means of identifying markers of prognosis. In a preliminary investigation of the molecular basis of canine meningioma tumorigenesis, we profiled three tumours by comparative genomic hybridization. Distinct patterns of sub-chromosomal deletions were identified suggesting alternative mechanisms of tumour initiation. The deleted chromosomal segments encompass two regions (10q23.1 and 17q22-q23) that are syntenic to the chromosomes (22 and 1p) most often deleted in human meningiomas. A number of genes associated with DNA repair, cell cycle progression and apoptosis are located on both the deleted canine chromosomal segments and the syntenic regions deleted in human meningiomas. This study represents the first report of chromosomal copy number abnormalities in non-cultured canine brain tumour tissue.

Reference cDNA library facilities available from European sources.

cDNA libraries are the cornerstone of efforts to identify the relatively small regions of genomes that are responsible for biological effects. Gene hunter seeking candidate genes, via a variety of approaches, ultimately focus on the cloning, sequencing, and expression of cDNAs. Assistance is now available to researchers in the form of genome programs, whose initial goals include assembly of a complete collection of expressed sequences derived from the genome of interest. The concept of reference sets of cDNA libraries is that the aims of genome programs are served most effectively by different laboratories working on a common set of high-quality arrayed cDNA libraries, using different experimental approaches, thereby reducing unnecessary duplication of effort, and maximizing the amount of information that one set of resources can provide.

A simple and efficient method for the isolation of differentially expressed genes.

A simple and reproducible general approach for the isolation of differentially expressed genes is described. Digestion of cDNAs with a class IIs restriction endonuclease produces fragments with every combination of possible bases in the cohesive ends. Under stringent conditions, the specific ligation of adaptors with perfectly complementary overhangs partitions the cDNA fragments into non-overlapping subpopulations. Internal cDNA restriction fragments are exponentially amplified by adaptor primer PCR and visualised by non-denaturing polyacrylamide gel electrophoresis. The power of the technology was demonstrated using a rat model of pressure-induced left-ventricular hypertrophy (LVH). A set of 29 fragments, derived from a sample (6 %) of the possible adaptor pool combinations, displayed apparent differential expression. The differential expression of 19 (66 %) were confirmed by Northern blot analysis. Sequence analysis identified both genes known to be upregulated in LVH, and novel genes. The fidelity of adaptor ligation was demonstrated by the isolation of known gene fragments by appropriate adaptor combinations. The spiking of mRNA populations with known amounts of a synthetic mRNA demonstrated a current sensitivity equivalent to the detection of transcripts expressed at the level of as little as 1 in 10,000 molecules.

The specialisation of oral surgery in general practice.

Much has been written recently on the subject of introducing a specialist title in oral surgery and the establishment of specialist oral surgery practices. The aim of my elective was to conduct a literature review, interview general practitioners involved in oral surgery, and examine the feasibility of undertaking oral surgery in a specialist practice.

Design and use of synthetic oligonucleotide probes in the cloning of delta-endotoxin genes from Bacillus thuringiensis.

A detailed protocol is described for the design and use of synthetic oligonucleotide probes for screening DNA libraries from Bacillus thuringiensis var. kurstaki (strain HD191) for copies of the gene (tox) encoding the insecticidal delta-endotoxin. Two homologous tox genes were identified in this organism; one of these was located on a 75-kb plasmid and the other on a second large plasmid or the bacterial chromosome. A tox gene was isolated as a 6.5-kb HindIII fragment of B. thuringiensis plasmid DNA.