PDC and the protozaon parasite (original) (raw)
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Programmed cell death: beyond the frontiers of science
Biotecnología …, 2004
Programmed Cell Death (PCD) is an emerging topic contributing actively to basic biology, and in the near future, we could expect practical applications improving human health and the productivity of our crops. Current results relate this complex and paradoxical process with the physiological development, stress response and diseases of plants and animals. With the aim of improving the exchange as a starting point to future cooperation in the field of PCD, the International Cell Death Society (ICDS) and the European Cell Death Organization (ECDO) organized in Havana on February 24th the International Seminar Programmed Cell Death in Plants: a challenge to the new millennium, sponsored by the Tobacco Research Institute of Havana. To this historical meeting, the first co-organized by the two most important organizations on PCD, were invited recognized scientists from Italy, USA, France, Belgium, Switzerland, Czech Republic and Cuba. Although the seminar was organized to deal with the basic aspects of cell death in plants, speeches referred frequently to animal models. Session chairs, Mauro Piacentini and Zahra Zakeri, presidents of ECDO and ICDS, respectively, guided thirty minute speeches of ten speakers. The opening words of Vladimir Andino, head of the Tobacco Research Institute of Havana, and Mauro Piacentini, were followed by the speech of Richard A Lockshin from the Department of Biological Science of St. John's University, USA. He dealt with the historical origins of PCD research [1]. According with his speech, cell death as a normal, physiological process was recognized in the 19 th Century. One hundred years later, many of these deaths (in animals) were described as programmed, deriving from the recognition that, in embryonic development and metamorphosis, cells died at predictable times and places. Thus the assumption was that cell death was genetic in origin, and not a random loss of control. Later, Kerr, Wyllie, and Currie [2] called attention to a common morphology of many cell deaths and coined the term "apoptosis" in order to assert its importance in homeostasis as opposite and equal to mitosis (Figure 1). Shortly thereafter, a group of researchers ultimately led by Horvitz [3] proved the existence of genes that controlled all cell deaths in the embryo of the nematode Caenorhabditis elegans. Their research led rapidly to the identification of these genes. These included genes that could turn on or off the activation of death, genes that produced products that could kill cells, inhibitors of those products-activation of death often consisted of release from inhibition of death-and genes involved in the scavenging of the remnants of the dead cells. Two profound arguments developed from these discoveries: First, that all cells carried within them
Programmed cell death: a missing link is found
Trends in Cell Biology, 1997
The evolutionary conservation of programmed cell death (PCD) in animals has meant that genetic studies in worms can illuminate PCD in higher organisms. Genetic analysis in the nematode worm C. elegans has provided a conceptual framework involving, at its heart, three genes: two of these, ced-3 and ced-4, are both required for PCD in the worm, whereas another, ced-9, inhibits the action of ced-3 and ced-4 in surviving cells 1. Mammalian homologues have been identified for ced-3, which encodes a caspase, and for ced-9, which is related to the cell-death suppressor bcl-2, but, until now, no vertebrate homologue had been found for ced-4. Unfortunately, the sequence of CED-4
A comparison of programmed cell death between species
Genome biology, 2000
Key components of the programmed cell death pathway are conserved between Caenorhabditis elegans, Drosophila melanogaster and humans. The search for additional homologs has been facilitated by the availability of the entire genomic sequence for each of these organisms.
Programmed Cell Death in Animal Development
Cell, 1997
condense, and the organelles and plasma membrane retain their integrity in a process Kerr and his colleagues and Martin C. Raff Developmental Neurobiology Programme named apoptosis. The dead cells or their fragments are rapidly phagocytosed by neighboring cells or macro-MRC Laboratory for Molecular Cell Biology University College London phages before there is any leakage of the contents of the cells, and thus they do not induce an inflammatory London, WC1E 6BT United Kingdom response. Apoptotic cells in developing tissues are almost always inside other cells (Figures 1A-1C), suggesting that dying cells are usually phagocytosed before they display the morphological changes of apoptosis. Programmed cell death (PCD) occurs during the devel-Because apoptotic cell deaths usually look so similar opment of all animals that have been studied, but only from tissue to tissue and animal to animal (Figures 1Arecently has its molecular basis been discovered. In this 1C), Kerr and his colleagues proposed that these deaths review, we briefly consider some of the main events reflect the operation of an active, intracellular death proin the history of PCD in animal development. We then gram that can be activated or inhibited by a variety of summarize what has been learned about the molecular physiological or pathological environmental stimuli. mechanism of PCD and some of the intracellular pro-It took almost another 20 years, however, before the teins that control it. We next discuss the functions of idea that animal cells have a built-in death, or suicide, PCD in development and how PCD is regulated during program became generally accepted, largely through development by signals from other cells. Finally, we genetic studies in the nematode Caenorhabditis elegans consider what the evolutionary origins of PCD may have that identified genes that seem dedicated to the death been. program and its control (Horvitz et al., 1982; Ellis and Horvitz, 1986), and then through the finding that some Some History of these genes were homologous to mammalian genes Soon after it was recognized in the middle of the last
Molecular Mechanisms of Programmed Cell Death
2003
Programmed cell death and apoptosis have now been recognised as biological phenomena which are of fundamental importance to the integrity of organisms. What may have evolved as an altruistic defence against pathogen invasion in simple organisms is now a major regulatory mechanism in the development and maintenance of multi-cellular organisms. The classically defined morphological characteristics of apoptosis are now accompanied by a plethora of information regarding common biochemical and genetic mediators of programmed cell death. It is apparent that life and death decisions are taken by individual cells based on their interpretation of physiological signals, or their own self-assessment of internal damage. The knowledge that cell death is a genetically regulated process has highlighted an inherent potential for manipulation and offered new avenues for research into several diseases, and also productivity improvements in the biotechnology industry. This relatively "new frontier" in cell science has undoubtedly widened our perspectives and may provide novel strategies to expedite both medical and biotechnological research.
Journal of Cell Death
Programmed cell death (PCD) is genetically regulated phenomenon of selective elimination of target cells that are either under pathological conditions or unwanted for organism’s normal growth and development due to other reasons. The process although being genetically controlled is physiological in nature that renders some hallmarks like blebs in the cell membrane, lobe formation in nuclear membrane, DNA nicks resulting to DNA ladder of 200 bp, and downstream activation of caspases. Moreover, as the process refers to the death of “targeted cell”, the term is exclusively suitable for multicellular organisms. Number of reports advocate similar type of cell death process in unicellular organisms. As cell death in unicellular organisms is also reflected by the signature of PCD obtained in metazoans, such cell death has been grouped under the broad category of PCD. It is pertinent to mention that by definition a unicellular organism is made of a single cell wherein it carries out all of ...