Absract Archive   June - 06 Cationic polyplex nano carriers for enhanced siRNA delivery Introduction DNA, a vital biomolecule of a living organism, contains a set of information coded in the form of nucleotides and is passed from generation to generation, but still no two individuals are alike because this set of information is made from the combination of two different individuals. This type of combination and permutation results in a gene pool and the dominant traits are positively selected by natural selection because of their enhanced capability of surviving, or their competency and favorable environmental conditions. Such dominant characters need not always be beneficial for an individual as they could be problematic too. Mutational events like deletion, insertion, polymorphisms and inversions produce such defective features. They occur during linkage and crossing over of chromosomes and when the cell's machinery is busy in replication processes and making a complement of its DNA sequence. The cell's machinery also has some internal checks and safety mechanisms to counteract such unintentional lethalities, amongst them is the mechanism of RNA interference (RNAi), which is fast gaining prominence for its potential in therapeutic applications. Authors:Meenakshi Malhotra, Khusboo Agarwal, Chandan Mehta, C. K. Jain, Shyam Sunder, Indira P. Sarethy, V. R. Swamy. Plant Secondary Metabolites Plants produce a great variety of organic compounds that are not directly involved in primary metabolic processes of growth and development. The roles of these natural products or secondary metabolites play in plants have only recently come to be appreciated in an analytical context. Natural products appear to function primarily in defense against predators and pathogens and in providing reproductive advantage as attractants of pollinators and seed dispersers. They may also act to create competitive advantage as poisons of rival species. Most natural products can be classified into three major groups: terpenoids, alkaloids, and phenolic compounds (mostly phenylpropanoids). Terpenoids are composed of five-carbon units synthesized by way of the acetate/mevalonate pathway or the glyceraldehyde 3-phosphate/pyruvate pathway. Many plant terpenoids are toxins and feeding deterrents to herbivores or are attractants of various sorts. Alkaloids are synthesized principally from amino acids. These nitrogen-containing compounds protect plants from a variety of herbivorous animals, and many possess pharmacologically important activity. Phenolic compounds, which are synthesized primarily from products of the shikimic acid pathway, have several important roles in plants. Tannins, lignans, flavonoids, and some simple phenolic compounds serve as defenses against herbivores and pathogens. In addition, lignins strengthen cell walls mechanically, and many flavonoid pigments are important attractants for pollinators and seed dispersers. Some phenolic compounds have allelopathic activity and may adversely influence the growth of neighboring plants. Authors:D.Philomina, P.Bharathi, S.Chakkaravarthi