Current Pharmaceutical Biotechnology - Volume 8, Issue 5, 2007

Adaptation of marine bacteria to the harsh environments has led to a rich biological and genetic diversity. Marine bacteria are attracting attention as new biotechnological resources. These bacteria can be a potential source of new bioactive compounds for industrial, agricultural, environmental, pharmaceutical and medical uses. The present paper reveals the potential of the marine bacteria with biotechnological applications related to antimicrobial drug discovery, environmental remediation, and developing new resources for industrial processes.

Reentries of a single molecule in the confocal, femtoliter-sized probe region (about 10-16 L and less) are significant because during measurement times they give rise to fluctuation phenomena such as molecule number fluctuations at the single-molecule level in solution without immobilization or hydrodynamic focusing. These fluctuations are the fundamental physical process on which, for example, fluorescence correlation spectroscopy and two-color fluorescence cross-correlation spectroscopy are based. The reentries of just one molecule in the confocal probe region are theoretically examined in this original article using a hidden, continuous-time Markov model. The system is not set up to have systemic drift or convection. It is found that the reentries obey certain conditions and analytical expressions for the reentry probabilities are obtained first. In particular, the time constant of the mean value and the variance of the reentry probabilities are obtained. The fractions of non-meaningful reentries and meaningful reentries are found for these experimental situations. Therewith, the concentration dependence of the meaningful time that one can study bimolecular reactions of the selfsame molecule in the confocal probe region is derived for the first time. The meaningful time in the probe volume is proportional to the diffusion time of the selfsame molecule and related inversely to the size of the given confocal probe volume. For small molecules, i.e. small diffusion times at a given size of the confocal probe region, one needs lower concentrations of molecules of the same kind in the bulk phase, whereas large molecules can be studied at higher concentrations. The selfsame molecule scenario is compared with the molecular scenario that a second molecule enters the probe volume at random as a function of the meaningful time. The analytical solutions of the physical reentry model (mechanism) hold for the one-, two- (membrane), or three- (solution, live cell) dimensional Brownian motion.

In the last 20 years the practice of DNA sequence detection has gained more and more importance in a variety of fields like-genetics, food safety, pathology, and criminology. This has been driven by the growing knowledge about the human and other organism's genome. The development of sophisticated technologies for the analysis of DNA makes the analysis of DNA faster and easier to use, and enable numerous researchers to take advantage of these techniques in their scientific work. An interesting alternative for the standard fluorescence labelling of DNA are metal nanoparticles. This paper reviews different detection schemes for using metal nanoparticles, and especially gold nanoparticles, as labels in DNA analysis. It covers various methods for the detection of nanoparticle labels taking advantage of their unique optical properties. Alternative methods are also described using electromechanical, electrochemical and electrical methods for the detection.

Among the methods for single molecule detection in the field of medicinal chemistry, the importance of fluorescence correlation spectroscopy (FCS) is growing. FCS has the advantage of permitting us to determine the number of fluorescent molecules and the diffusion constant dependent on the molecular weight without any physical separation process such as gel electrophoresis. Thus this method is appropriate for studies on the hybridization of fluorescence-labeled oligonucleotides with RNA or DNA as well as gene expression through translation of a target protein linked with green fluorescent protein. Indeed, several groups have employed FCS for evaluation of gene expression in different ways. Many investigators are particularly interested in using FCS to quantitatively analyze mRNA just after transcription in the living cell. Technical advances in FCS have broadened the research spectrum in medicinal chemistry since it can also be used to study SNPs and molecular interactions between transcription factors and promoter sequences, as well as gene expression in living cells.

This review deals with the antisense technology that, together, forms a very powerful tool to inhibit gene expression and may be used for studying gene function (functional genomics) and for therapeutic purpose (antisense gene therapy). Antisense oligonucleotides block translation of target mRNAs in a sequence specific manner, either by steric blocking of translation or by destruction of the bound mRNA via RNase-H enzyme. For proper designing, accessible sites of the target RNA for binding antisense oligonucleotides have to be identified. Whether being used as an experimental reagent or pharmaceuticals, several problems or drawbacks have to be overcome for successful applications. Toward this direction, various modifications of sugar, bases and phosphate backbone of antisense oligonucleotides have been attempted. In recent years valuable progress has been achieved through the development of advanced cellular delivery systems and novel chemically modified nucleotides with improved properties such as enhanced serum stability, higher target affinity and low toxicity. These qualities and the specificity of binding make this technique a potentially powerful therapeutic tool for gene targeting and/ or expression regulation. This review discusses the basis of structural design, mode of action, chemical modification, enhanced cellular uptake, therapeutic application and future possibilities in the field of advanced antisense technology.

Cellular therapies derived from embryonic stem (ES) cells have gained a renewed interest with the experimental demonstration that an embryonic stem cell lines can be established from human blastocyst-stage embryos and prompted to differentiate into almost all types of cells present in the body including hematopoietic cells. Hematopoiesis is a series of cellular processes whereby short-lived mature blood cells are continuously replenished from a pool of rare pluripotential hematopoietic stem cells, in a highly orchestrated process. Aberrances in this intricate process may lead to a malignancy of essential blood-forming organs, causing diseases such as leukemia, aplastic anemia, lymphoma, myelodysplasia and myeloproliferative disorders. Embryonic stem cells show great potential and it may be technologically feasible to transplant differentiated ES cells and to cure various kinds of blood disorders. Understanding the biology of ES cell derived hematopoiesis may lead to the development of co-transplantation protocols that will result in a decreased morbidity and mortality by providing safer and simpler transplantation procedures for patients with malignant and non-malignant conditions. The potential utility of ES cells for gene therapy, tissue engineering and the treatment of a wide variety of currently untreatable diseases is simply too essential to ignore, however, our knowledge and ability to deliver these forms of therapy in a safe and efficient manner requires additional advances in the understanding of the basic biology of ES cells. In this article, we will discuss the factors and methodologies responsible for the differentiation of ES cells into hematopoietic progenitors and their potential to treat different blood related diseases.