Molecular genetics hybridization

The hybridization of DNA strands from different sources forms the basis for a powerful set of techniques essential to the practice of modem molecular genetics. A specific DNA sequence or gene can be detected in the presence of many other sequences, if one already has an appropriate complementary DNA strand (usually labeled in some way) to hybridize with it (Chapter 9). The complementary DNA can be from a different species or from the same species, or it can be synthesized chemically in the laboratory using techniques described later... 

To be sure, molecular genetics suffers from limitations. Many of its methods cannot be used without the availability of at least one known amino acid sequence. Thus, peptide isolation remains a critical need. Oligonucleotide probes can be too short, leading to useless or "false positive" hybridizations. Also, an appropriate bioassay is required to assess the authenticity of any product of molecular biology. However, the use of molecular genetic techniques will cause an explosion of information on insect neuropeptides and their sequences within the very near future. 

The causes of these differences lie on the physicochemical reactivity properties inherent to each probe sequence. For example, a broadly used parameter in molecular genetics for its essential role in primer affinity is the guanine-cytosine percentage (i.e., GC content) of the oligonucleotide. Another cause, in this case associated to the probe-mapping locus, is the distance to the 3 -end of the gene. This was primarily reported by the 3 -IVT designs of Ajfymetrix microarrays. The 3 -poly-A amplification performed before the hybridization in these devices can considerably bias the abundance measures detected,... 

A powerful molecular genetic method called the yeast two-hybrid system exploits the flexibility in activator structures to identify genes whose products bind to a specific protein of interest. Because of the importance of protein-protein interactions in virtually every biological process, the yeast two-hybrid system is used widely in biological research. 

Pelletier, G., C. Primard, F. Vendel, P. Chetrit, P. Rouselle, and M. Renard. 1983. Intergeneric cytoplasmic hybridization in Cmciferae by protoplast fusion. Molecular Genetics 191 244-250. 

The pharmaceutical industry, once a rather specialized hybrid between the chemical industry and the clinical research laboratory, has also taken on a new dimension - also exploiting the remarkable advances in both molecular genetics and cell biology. It is not the case that the rise of biotechnology has brought about an unprecedented clash between corporate and scholarly values. First, while there is clearly a conceptual distinction between the profit motive and the search for the truth, these values etre not, in any significant way, in conflict. Second, the academic-corporate connection has existed for many years in many areas. It is novel only to certain areas of biological research. 

The 3- and/or 4"-0-acyl derivatives of several tylosin-related macrolides have also been prepared by analogous bioconversion methods the 3-0-acetyl-4"-0-isovaleryl derivative of macrocin (3" -0-demethyltylosin) had properties similar to those of the corresponding ester of tylosin [90]. This research has now been further extended with the reported cloning of a gene encoding the 4"-0-isovaleryl acylase enzyme and its expression by formation of a new hybrid macrolide, 4"-0-isovalerylspiramycin [91]. These results indicate that future contributions can be anticipated from the area of molecular genetics on biochemical processes involved in macrolide biosynthesis, with the promise of production of novel hybrid macrolide structures. 

Levy B, Mukherjee T, Hirschhorn K (2000) Molecular cytogenetic analysis of uterine leiomyoma and leiomyosarcoma by comparative genomic hybridization. Cancer Genet Cytogenet 121 1-8... 

Chr. Lengauer et al., "Chromosomal Barcodes produced by Multifluorescence in situ Hybridization with Multiple YAG Clones and Whole Chromosomes painting probes, in Human Molecular Genetics. 5th ed.. vol. 2. Oxford University Press, pp. 505 - 512. 

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