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Three things are necessary to support a cultural genetics: 1. There must be some process of reproduction and inheritance, in which cultural structures and elements are transmitted from one “generation” to the next. 2. There must be a significant measure of stability in the transmission process, in which the replicators show sufficient copying fidelity to transmit recognizable patterns. 3. There must be some process such as sexuality or mutation that introduces change and variety into the... Read Full Story

Polyamines (PAs) are naturally occurring polycationic aliphatic amines, which due to their ubiquity and versatility are involved in the regulation of various cellular and molecular processes. They are positively charged compounds with their charge distributed along the molecule. The common PAs, spermidine (SPD) and spermine (SPM) and their diamine precursor putrescine (PUT) play a critical role in the normal functioning of all cells. They are involved in the cellular functioning both at the... Read Full Story

Following two basic mechanisms are assumed to contribute to the transport of the DNA into the cell. 1) An active, energy dependent uptake of the transfection complexes by a process called endocytosisd 2) “Passive” membrane fusion and release of DNA into the cytoplasm. The compaction agent used in the first step largely determines which mechanism is more important in a given case. For polycationic molecules, a direct interaction (fusion) with the hydrophobic membranes is not likely. The most... Read Full Story

If a foreign DNA sequence is to be introduced into a cell, it is obviously necessary that the two meet, i.e., that the compacted DNA somehow attaches to the cell surface within and for a reasonable amount of time. Cell membranes consist of a lipid bilayer into which a number of complex (glyco)protein molecules are inserted or anchored. The dominant mechanism for interaction between the DNA complex and the negatively charged cell surface are electrostatic forces. The negative surface charge is... Read Full Story

Pure (“naked”) DNA has little chance to enter a cell. DNA is a huge, negatively charged and hence highly hydrophilic molecule. Cells are surrounded by a hydrophobic plasma membrane and, in addition, bear a negative surface charge. The plasma membrane contains several highly selective transporter units, which allow for the well-controlled introduction and excretion of certain molecules. Foreign DNA is normally not amongst the molecules allowed to enter the cell. The first and best-understood... Read Full Story

DNA, the common carrier of the genetic information for all living entities on this planet, is omnipresent and we are daily exposed to large quantities of foreign DNA (e.g., by food or bacterial infections). Under these circumstances, nature had to provide powerful barriers against the spontaneous insertion of foreign DNA sequences into the genomic DNA of cells. Barriers are the plasma membrane of the cell, the envelope of the cell’s nucleus, but also the possibility for DNA degradation in... Read Full Story

The structure of the large DNA molecule, which was known to be the main material of the chromosomes, remained a mystery until Watson and Crick proposed the double helix structure in 1953.6 Chromosomal (genomic) DNA consists of two complementary polyanionic chains made up of long sequences of four different nucleic bases. Since the four bases are complementary, the double stranded DNA molecule is capable of exact self-replication from either strand. The diameter of the double helix is about 2... Read Full Story

The impact of molecular biology on everyday life has increased enormously over the last two decades. Medical, pharmaceutical and lately even agricultural applications of “gene technology” have become standard, if sometimes controversially viewed procedures. The feasibility of this “revolution” is based on a few biological facts; most importantly the relationship between DNA, RNA and proteins. DNA carries the information for protein production. Basic units of information are called genes... Read Full Story

Today an enormous amount of genetic information is available from databases, which are continuously fed by worldwide genome sequencing programs. Every day, the human genome-sequencing program alone provides new information about human genes with potential therapeutic value. On a diagnostic level, this will allow detecting “genetic defects” and also a prediction as to which amino acid in a given protein is concerned. However, unless the change in amino acids is meaningless or the malformed... Read Full Story

The process of rejection may begin with the diffusion of immunogens from the graft across the membrane barrier. There are several possible sources for these antigens, including molecules shed from the cell surface, protein secreted by live cells and cytoplasmic protein liberated from dead cells. Recognition and display of these antigens by antigen presenting cells initiates the cellular and humoral immune response. The former leads to activation of cytotoxic cells, macrophages and other cells... Read Full Story