Protozoa genetics

Felleisen, R.S.J. (1998) Comparative genetic analysis of trichomonadid protozoa by the random amplified polymorphic DNA technique. Parasitobgy Research 84, 153-156. 

The most notable medical application of IFN-y relates to the treatment of CGD, a rare genetic condition with a population incidence of between 1 in 250 00 and 1 in 1 000 000. Phagocytic cells of patients suffering from CGD are poorly capable/incapable of ingesting or destroying infectious agents such as bacteria or protozoa. As a result, patients suffer from repeated infections (Table 8.10), many of which can be life threatening. 

C, G or T. This is not sufficient to encode the 20 possible amino acids. In triplets of 3 positions, there are 64 possible combinations. Hence, the system uses triplets, called codons. The code for each protein starts with an ATG (start codon) and ends with a TAA, TAG or a TGA (stop codons). The code is almost universal only mitochondria and ciliated protozoa have a different genetic code. 

As often happens, a well-established conclusion may have to be modified. There are exceptions to the universal genetic code in mitochondrial DNA and in some protozoa (Chapter 5).45... 

Kelly, J.M. (1 997) Genetic transformation of parasitic protozoa. Advances in Parasitology 39, 227-270. 

The genetic code is not universal but is the same in most organisms. Exceptions are found in mitochondrial genomes where some codons specify different amino acids to that normally encoded by nuclear genes. In mitochondria, the UGA codon does not specify termination of translation but instead encodes for tryptophan. Similarly, in certain protozoa UAA and UAG encode glutamic acid instead of acting as termination codons. 

The code appears to be universal to the extent that synthetic polyribonucleotides seem to code in the same way in mammals, bacteria, and other species, and components of the protein-synthesizing system of various species can operate with components from certain others. Mitochondria and ciliated protozoa have genetic codes slightly different from the standard. For example, in human mitochondria, UGA codes for tryptophan instead of as a termination signal, AUA codes for methionine rather than isoleucine, and AGA and AGG are termination signals rather than coding for arginine. 

The long molecules of DNA occur within the nucleus of individual cells. It is thought that each DNA molecule corresponds to a single chromosome. There are a characteristic number of chromosomes for individual species. These carry the hereditary information of the individual on a series of shorter sections of the nucleic acid known as genes. The nucleic acid within the nucleus of most cells, such as bacteria and protozoa, is composed of double-stranded DNA. DNA contains the information necessary for the synthesis of ribosomal, transfer, and messenger RNA, which are responsible for synthesis of enzymes, which drive metabolic processes within the cell. The genetic material of viruses may either be DNA or RNA and can be single- or double-stranded (3). 

Eukaryotic cell This subclass is indented tmder subclass 93.2. Subject matter involving a eukaryotic cell, such as an animal cell, plant cell, fungus, protozoa, or higher algae, which has been genetically modified. (1) Note. A eukaryotic cell has a nucleus defined by a nuclear membrane wherein the nucleus contains chromosomes that comprise the genome of the cell. 

Since Leishmania can be cultured easily, this genus has served as an in vitro prototype for investigating drug resistance in parasitic protozoa. Two classes of drug-resistant Leishmania have been generated and characterized. The first is that in which a genetic lesion leads to impaired transport or metabolic function. Mutations in transport pathways (51) and in metabolic enzymes (52) have provided considerable insight into the avenues by which certain nutrients are metabolized in Leishmania. 

---