Comparative Genomic Hybridization: It is used for the identification in the increase or decrease of the important chromosomal fragments harboring genes involved in a disease. Gene Discovery: DNA Microarray technology helps in the identification of new genes, know about their functioning and expression levels under different conditions.
Disease Diagnosis: DNA Microarray technology helps researchers learn more about different diseases such as heart diseases, mental illness, infectious disease and especially the study of cancer.
Until recently, different types of cancer have been classified on the basis of the organs in which the tumors develop. Now, with the evolution of microarray technology, it will be possible for the researchers to further classify the types of cancer on the basis of the patterns of gene activity in the tumor cells.
This will tremendously help the pharmaceutical community to develop more effective drugs as the treatment strategies will be targeted directly to the specific type of cancer. Drug Discovery: Microarray technology has extensive application in Pharmacogenomics. Pharmacogenomics is the study of correlations between therapeutic responses to drugs and the genetic profiles of the patients. Comparative analysis of the genes from a diseased and a normal cell will help the identification of the biochemical constitution of the proteins synthesized by the diseased genes.
The researchers can use this information to synthesize drugs which combat with these proteins and reduce their effect. Toxicological Research: Microarray technology provides a robust platform for the research of the impact of toxins on the cells and their passing on to the progeny. Toxicogenomics establishes correlation between responses to toxicants and the changes in the genetic profiles of the cells exposed to such toxicants.
Some companies manufacture microarrays using methods similar to those used to make computer microchips. On the surface, each chip contains thousands of short, synthetic, single-stranded DNA sequences, which together add up to the normal gene in question, and to variants mutations of that gene that have been found in the human population.
When they were first introduced, DNA microarrays were used only as a research tool. Scientists continue today to conduct large-scale population studies - for example, to determine how often individuals with a particular mutation actually develop breast cancer, or to identify the changes in gene sequences that are most often associated with particular diseases.
This has become possible because, just as is the case for computer chips, very large numbers of 'features' can be put on microarray chips, representing a very large portion of the human genome. Microarrays can also be used to study the extent to which certain genes are turned on or off in cells and tissues. The target DNA pieces can be identified by their fluorescence emission by passing a laser beam.
A computer is used to record the pattern of fluorescence emission and DNA identification. This technique of employing DNA chips is very rapid, besides being sensitive and specific for the identification of several DNA fragments simultaneously. TMAs are similar to gene expression microarrays in having samples arrayed in rows and columns on a glass slide; they differ in that each element on the TMA slide corresponds to a single patient sample, allowing multiple patient samples to be assessed for a single molecular marker in one experiment, while gene expression arrays allow assessment of thousands of molecular markers on a single patient sample per experiment.
Tumor formation involves simultaneous changes in hundreds of cells and variations in genes. Microarray can be a boon to researchers as it provides a platform for simultaneous testing of a large set of genetic samples. It helps especially in the identification of single-nucleotide polymorphisms SNPs and mutations, classification of tumors, identification of target genes of tumor suppressors, identification of cancer biomarkers, identification of genes associated with chemoresistance, and drug discovery.
For example, we can compare the different patterns of gene expression levels between a group of cancer patients and a group of normal patients and identify the gene associated with that particular cancer.
Gene microarrays have been used for comparative genomic hybridization. In this technique, genomic DNA is fluorescently labeled and used to determine the presence of gene loss or amplification. The conversion of a non-invasive tumor to an invasive tumor also warrants research. Clark et al. Microarray-based expression profiling allows us to identity families of genes as well as the important molecular and cellular events that might be important in complex processes like metastasis.
Practical applications in future include diagnostic and prognostic management of patients. Clinicians will be able to use microarrays during early clinical trials to confirm the mechanisms of action of drugs and to assess drug sensitivity and toxicity.
They can be used to develop a new molecular taxonomy of cancer, including clustering of cancers according to prognostic groups on the basis of gene expression profiles. Increase in the number of resistant bacteria and superadded infections has led to failure of antibiotics. Virulence of the bacterial strains too affects the outcome of the disease process. In oral cavity where anaerobic bacteria might be the infective agent, they often are not easily culturable, especially organisms such as actinomyces.
DNA microarray analysis helps as the bacterial genomic DNA often outlasts the viability of the bacteria and a diagnosis can be made using a small amount of DNA, as opposed to the large numbers of bacteria needed for culture. In future, an abscess specimen might be sent not for culture and sensitivity testing, but rather for DNA microarray analysis.
Leukoplakia or white lesions of the oral cavity may result from a myriad of reversible conditions. Currently, microscopic examination fails to identify the small subset of these lesions that progress to oral cancer. Recent studies have illustrated the effectiveness of microarrays in oral cancer. Early diagnosis and management of oral cancer is correlated with increased survival. Identification and treatment of premalignant and early cancerous oral lesions may become one of the most valuable services in future performs.
This review has given a small outline of the technique behind microarray and the various steps involved. By identifying which genes in the cancer cells are working abnormally, doctors can better diagnose and treat cancer. One way they do this is to use a DNA microarray to determine the expression levels of genes. Overexpressed genes generate more mRNA than underexpressed genes.
This can be detected on the microarray.
0コメント