MODERN GENETICS JOURNAL (MGJ)
Year:2007 | Volume:- | Issue:6-7|Papers Count:13

Chromosomal DNA in E.coli with about 5 million base pairs, has only more than 1 mm in length so that in comparison with the size of living cells, this molecule has to be intensively compacted. The initial process of bacterial genomic packaging is accomplished by polyamines including spermin and sper-midin. In addition, several bacterial of protein molecules with its small size called histone-like proteins cause folding in the highly compacted structure. Some of the histone-like proteins in bacteria have been known including: HU, IHF, H-NS, HLPI, H and FIS. They have similarity to each other in general but play different roles and different structural criteria. These include their roles in initiation of replication, control and regulation of transcription (as an activator or repressor), and in site-specific recombination.

Determining the roles of carbohydrates in cell biology is hindered by the tremendous efforts that must be taken either to synthesized carbohydrates chemically or to isolated them natural sources. On the other hand, microarray allows rapid and simultaneous detection of thousands of parameters in a single experiment. To facilitate discoveries in the emerging field of glycomics and the role of carbohydrates in post translation modifications of proteins, sensitive screening techniques for probing carbohydrate-protein interactions have been developed. Recent developments in the field of carbohydrate microarray technology facilitate applications for different types of protein-carbohydrate interactions. Several platforms have been developed to study glycobiology. These platforms include the covalent and non-covalent immobilization of carbohydrates on different plates, slides and surfaces. This review aims to introduce and summarize recent progresses in the area of carbochip technology.

To date one of the developing concepts is structural and mechanical devices at the nanometer scale by using molecular recognition properties of biological macromolecules. The formation and assembly of molecular-scale building blocks into well-defined structures is the essence of nanotechnology. Structural and chemical properties of the DNA molecules make it well-suited for making nanostructures. At present, several developments in some of the categories of DNA nanotechnology have been achieved, such as, the use of single-strand DNA to prepare periodic arrays, the design of DNA motor and DNA-based nanofabrication. The first step to prepare periodic arrays is to produce triangle produce from DNA molecules and to join together to creation of two dimensional structures. Other branches of DNA nanotechnology include the DNA nanomotors that could be continuously activated by chemical alterations, well-defined nanopattems with designed DNA structures serving as effective masks to produce metallic nanostructures, which describe well the future of this technology.

Retrotransposons are mobile genetic elements that transpose through reverse transcription of an RNA intermediate. Retrotransposons are ubiquitous in plants and play a major role in plant gene and genome evolution. In many cases, retrotransposons comprise over 50% of nuclear DNA content, a situation that can arise in a few million years. Plant retrotransposons are structur ally and functionally similar to retrotransposons and retroviruses that are found in other eukaryotic organisms. Because of their major share in the genome, retrotransposons can be easily employed as molecular markers. Molecular marker primer for PCR reaction is designed based on conserved regions of mobile element DNA. Here, we describe the background and strategies for four major retrotransposon-based markers: SSAP, IRAP, REMAP, and RBIP.

In 1992, the analysis of PCR kinetics becomes possible by constructing a system that detects PCR products as they accumulate. This "realtime" system includes the intercalator ethidium bromide in each amplification reaction, an adapted thermal cycler to irradiate the samples with ultraviolet light and detection of the resulting fluorescence with a computer-controlled cooled CCD camera. Amplification produces increasing amounts of double-stranded DNA, which binds ethidium bromide, resulting in an increase in fluorescence. By plotting the increase in fluorescence versus cycle number, the system produces amplification plots that provide a more complete picture of the PCR process than assaying product accumulation after a fixed number of cycles. This methodology could be used to quantify population of beneficial soil bacteria and fungi in root or rhizospher of host plant for example ammonia-oxidizing bacteria, siderophore production bacteria and mycorrhiza as well as the investigation of therapeutic effect of different pesticide on the plant tissue, study of expression of different gene under environment stress condition the study of mechanism of resistance plants against plant pathogens, mutation is induced in organism genomes.

Many countries, including Iran face serious drought periods and a continuous deficit of fresh water resources due to reduced rainfall and climate change. This is an alarming situation, because water deficit is the most important abiotic stress that results in lowering crops yield. Quick solutions are, therefore, needed to cope water shortages. It may not be possible to change the drought condition but it is possible to tailor plants in order to improve their stress tolerance. Several genes responsible for different traits associated with a biotic stress resistance in plants have been isolated and characterized. These include major groups encoding enzymes for the biosynthesis of compatible compounds (proline, glycinebetain), heat shock proteins (HSPs), late embryogenic abundant (LEA), non-specific lipid transfer proteins (nsLTPs), transcription factors and so on. Thus, one promising approach is to integrate useful drought tolerance traits through genetic engineering into varieties which are ideally suited for water scarce and drought conditions. A number of transgenic plants have also been produced, covering a wide range of altered characteristics for commercial cultivation.