The paper "Programmed Cell Death in the Unicellular Protozoan Parasite Leishmania by N. Lee" is a delightful example of an article on biology. Leishmania is a protozoan responsible for a number of diseases in humans; lesions in the skin which heal with time and visceral infections that are highly fatal. The life cycle involves a promastigote form which is flagellated & found carried by sand flies (vectors) and amastigote phase present in macrophages of mammals. The differentiation that occurs between the two stages is important in pathogenesis. Further to this, the microbe thrives in hostile environments, therefore, must regulate growth and maintain an infective colony.
PCD or Programmed cell death has roles in the regulation of growth, preventing infection by viruses, and cancer development. Research recently has pointed at PCD existing in unicellular organisms hence the need to understand the type and process as well as the biological importance. PCD has been observed in L. Donovani during death that occurs at the stationary stage in culture and when exposed to antibiotics. It starts with the mitochondrial membrane potential being depolarized then induction of activity similar to that of caspase.
This activity that resembles that of caspace has also been observed L. Donovani fresh isolates from animals infected that are infected as well as in other Leishmania specie. In vitro cultures of L. Donovani promastigotes show exponential growth in numbers during the first three to four days followed by a plateau which represents stationary phase. Fragmentation is seen at this stage and it intensifies later at day ten while day seven shows some sort of nuclear chromatin condensation. Nicking of DNA was also seen under TUNNEL assay hence the inference changes similar to PCD are observed in Leishmania grown in vitro.
In conclusion, the article seeks to demonstrate existence prokaryotes such as Leishmania and this is induced at the stationary phase and when exposed to antibiotics. The evidence is also there for PCD in fresh parasite isolates hence it is not only a phenomenon seen when cells are grown in vitro. The process is thought to preserve the survival of strong parasites through the elimination of unwanted ones. Future studies should focus on understanding the mechanism and characterize pertinent molecules as this will be a huge step towards drug development.