Acanthamoeba programmed cell death

Acanthamoeba is a free-living amoeba, ubiquitously distributed in the natural environment including soil and a plethora of water habitats. It is characterised as an opportunistic parasite that is able to cause several diseases, including life threating granulomatous Acanthamoeba encephalitis and a painful vision-threating keratitis. There is a clear and emerging need to understand how to treat infections caused by this dangerous pathogen, since pharmaceutical approaches have been considered insufficient. The presence and the importance of cell death pathways in unicellular organisms including Acanthamoeba is not yet fully understood and its existence is still debated. This research study presents a set of key characteristics and findings, comprising morphological, biochemical and molecular evidence of Acanthamoeba programmed cell death. Distinctive apoptotic features comprising cell shrinkage, membrane vesiculation and granules appearance which could be easily described as apoptotic like ‘bodies’ formation and nuclear shrinkage, accompanied by large scale chromatin condensation in dense clusters, have been primarily observed. Additionally, mitochondrial dysfunction, characterized by extended mitochondrial outer membrane permeabilization and release of apoptotic factors including cytochrome c, was also noted, indicating a mitochondrially mediated cell death pathway. During the expansion of the aforementioned apoptotic characteristics Acanthamoeba trophozoites were found to maintain their membrane integrity and homeostasis, at least at the early stages of the process. In-depth transcriptomic analysis based on RNA-sequence analysis revealed a plethora of differentially expressed genes between Acanthamoeba undergoing cell death and control trophozoites, indicating the correlation of a more defined and conserved signalling self-destruct program. These discoveries suggest that Acanthamoeba could undergo programmed cell death, which morphologically resembles apoptosis-like cell death, under specific stress conditions. Furthermore, similar characteristics are also found in cell death processes in higher eukaryotes and other unicellular organisms, indicating that biological principles behind this behaviour are widespread and well conserved among species. Identification of Acanthamoeba’s cell death signalling pathways might provide alternatives not only to microorganism’s refractory infection treatment, but also a more extended manipulation might become feasible across other species and systems

Unclassified

background, depth map Abstract: In this report we present an attempt that we made to evaluate the Xetal processor for real time stereo vision process. The main purpose was to develop an algorithm for stereo vision process and implement it in Xetal as embedded software. The original goal was to find an algorithm based on Xetal’s software framework which would be able to give a full depth map from a real world scene, using a binocular camera. The Xetal’s input signal is a merger of the right and left channel of the binocular camera. Finally, we developed an algorithm, the purpose of which is to detect the objects that are located in the foreground of a scene. The output is a two-level depth map. The final depth map needs to be filtered in order to reduce the noise at the background area. Conclusions: This is a first attempt to use the Xetal processor for the real time stereo vision application. The results are quite promising and in a subsequent research we can increase the output quality by improving the input signal

Hop2

An alignment of Hop2 genes from a range of eukaryotic organisms including Acanthamoeba is supplied as a SeaView Version 4 “.nex” file [24]. This alignment was used to generate Figure 1

Data from: “Meiotic genes” are constitutively expressed in an asexual amoeba and are not necessarily involved in sexual reproduction

The amoebae (and many other protists) have traditionally been considered as asexual organisms but suspicion has been growing that these organisms are cryptically sexual or are at least related to sexual lineages. This contention is mainly based on genome studies in which the presence of “meiotic genes” has been discovered. Using RNA-seq (next generation shotgun sequencing, identifying and quantifying the RNA species in a sample), we have found that the entire repertoire of meiotic genes is expressed in exponentially growing Acanthamoeba and we argue that these so called meiotic genes are involved in the related process of homologous recombination in this amoeba. We contend that they are only involved in meiosis in other organisms that indulge in sexual reproduction and that homologous recombination is important in asexual protists as a guard against the accumulation of mutations. We also suggest that asexual reproduction is the ancestral state

Data from: “Meiotic genes” are constitutively expressed in an asexual amoeba and are not necessarily involved in sexual reproduction

The amoebae (and many other protists) have traditionally been considered as asexual organisms but suspicion has been growing that these organisms are cryptically sexual or are at least related to sexual lineages. This contention is mainly based on genome studies in which the presence of “meiotic genes” has been discovered. Using RNA-seq (next generation shotgun sequencing, identifying and quantifying the RNA species in a sample), we have found that the entire repertoire of meiotic genes is expressed in exponentially growing Acanthamoeba and we argue that these so called meiotic genes are involved in the related process of homologous recombination in this amoeba. We contend that they are only involved in meiosis in other organisms that indulge in sexual reproduction and that homologous recombination is important in asexual protists as a guard against the accumulation of mutations. We also suggest that asexual reproduction is the ancestral state.Maciver, Sutherland; Koutsogiannis, Zisis; de Obeso Fernández del Valle, Alvaro (2019), Data from: “Meiotic genes” are constitutively expressed in an asexual amoeba and are not necessarily involved in sexual reproduction, Dryad, Dataset, https://doi.org/10.5061/dryad.8nb5f7