“…5 ). It is assumed that tomont cells under a different physiological condition would require different ribosomal proteins for the synthesis of a different set of proteins, and that these ribosomal proteins can also play various roles such as transcription, signal recognition, apoptosis and nuclear transport protein synthesis [ 18 , 31 ]. Fig.…”
BackgroundCryptocaryon irritans, a species of obligatory ciliate ectoparasite, can infect various species of marine teleost fish. Cryptocaryon irritans that fall to the seabed or aquarium bottom in winter can form “dormant tomonts” and wake up when the temperature rises the next year. Abundant studies and analyses on the dormant tomonts were carried out at the transcriptome level, in order to investigate the molecular mechanism of C. irritans tomonts entering the dormant state under low-temperature conditions.MethodsThe paired-end sequencing strategy was used to better assemble the entire transcriptome de novo. All clean sequencing reads from each of the three libraries (Group A: untreated blank control; Group B: treated for 24 h at 12 °C; and Group C: developed for 24 h at 25 °C) were respectively mapped back to the transcriptome assembly using the bioinformatics software.ResultsIn this study, 25,695,034, 21,944,467, and 28,722,875 paired-end clean reads were obtained respectively from the three cDNA libraries of the C. irritans tomont by Illumina paired-end sequencing technology. A total of 25,925 unique transcript fragments (unigenes) were assembled, with an average length of 839 bp. Differentially expressed genes (DEGs) were scrutinized; in Group B/A pairwise comparison, 343 genes presented differential expression, including 265 up-regulated genes and 78 down-regulated genes in Group B; in Group C/A pairwise comparison, there were 567 DEGs, including 548 up-regulated genes and 19 down-regulated genes in Group C; and in Group B/C pairwise comparison, 185 genes showed differential expression, including 145 up-regulated genes and 40 down-regulated genes in Group B.ConclusionsThis is the first transcriptomic analytical study of the C. irritans tomonts under low temperature. It can be concluded that most of the genes required for its cell survival under low temperature, or for cell entry into a deeper dormancy state were discovered, and that they might be considered as candidate genes to develop the diagnostic and control measures for cryptocaryoniasis.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1550-1) contains supplementary material, which is available to authorized users.
“…5 ). It is assumed that tomont cells under a different physiological condition would require different ribosomal proteins for the synthesis of a different set of proteins, and that these ribosomal proteins can also play various roles such as transcription, signal recognition, apoptosis and nuclear transport protein synthesis [ 18 , 31 ]. Fig.…”
BackgroundCryptocaryon irritans, a species of obligatory ciliate ectoparasite, can infect various species of marine teleost fish. Cryptocaryon irritans that fall to the seabed or aquarium bottom in winter can form “dormant tomonts” and wake up when the temperature rises the next year. Abundant studies and analyses on the dormant tomonts were carried out at the transcriptome level, in order to investigate the molecular mechanism of C. irritans tomonts entering the dormant state under low-temperature conditions.MethodsThe paired-end sequencing strategy was used to better assemble the entire transcriptome de novo. All clean sequencing reads from each of the three libraries (Group A: untreated blank control; Group B: treated for 24 h at 12 °C; and Group C: developed for 24 h at 25 °C) were respectively mapped back to the transcriptome assembly using the bioinformatics software.ResultsIn this study, 25,695,034, 21,944,467, and 28,722,875 paired-end clean reads were obtained respectively from the three cDNA libraries of the C. irritans tomont by Illumina paired-end sequencing technology. A total of 25,925 unique transcript fragments (unigenes) were assembled, with an average length of 839 bp. Differentially expressed genes (DEGs) were scrutinized; in Group B/A pairwise comparison, 343 genes presented differential expression, including 265 up-regulated genes and 78 down-regulated genes in Group B; in Group C/A pairwise comparison, there were 567 DEGs, including 548 up-regulated genes and 19 down-regulated genes in Group C; and in Group B/C pairwise comparison, 185 genes showed differential expression, including 145 up-regulated genes and 40 down-regulated genes in Group B.ConclusionsThis is the first transcriptomic analytical study of the C. irritans tomonts under low temperature. It can be concluded that most of the genes required for its cell survival under low temperature, or for cell entry into a deeper dormancy state were discovered, and that they might be considered as candidate genes to develop the diagnostic and control measures for cryptocaryoniasis.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1550-1) contains supplementary material, which is available to authorized users.
“…However, as these small RNAs are largely in the sense orientation, they are likely to be degradation products. Transcription of rRNA has been previously shown to fluctuate during encystation [ 35 ], slowing during early encystation but rising to trophozoite levels in mature cysts; the reduction in ribosomal derived small RNAs likely reflects these changes.…”
The human parasite Entamoeba histolytica has an active RNA interference (RNAi) pathway with an extensive repertoire of 27nt small RNAs that silence genes. However the role of this pathway in regulating amebic biology remains unknown. In this study, we address whether silencing via 27nt small RNAs may be a mechanism for controlling gene expression changes during conversion between the trophozoite and cyst stages of the parasite. We sequenced small RNA libraries generated from trophozoites, early cysts, mature cysts, and excysting cells and mapped them to the E. invadens genome. Our results show that, as in E. histolytica, small RNAs in E. invadens are largely ~27nt in length, have an unusual 5'-polyphosphate structure and mediate gene silencing. However, when comparing the libraries from each developmental time-point we found few changes in the composition of the small RNA populations. Furthermore, genes targeted by small RNAs were permanently silenced with no changes in transcript abundance during development. Thus, the E. invadens 27nt small RNA population does not mediate gene expression changes during development. In order to assess the generalizability of our observations, we examined whether small RNAs may be regulating gene expression changes during stress response in E. histolytica. Comparison of the 27nt small RNA populations from E. histolytica trophozoites from basal conditions, or after heat shock or exposure to oxidative stress showed few differences. Similar to data in E. invadens development, genes targeted by small RNAs were consistently silenced and did not change expression under tested stress conditions. Thus, the biological roles of the 27nt small RNA population in Entamoeba remain elusive. However, as the first characterization of the RNAi pathway in E. invadens these data serve as a useful resource for the study of Entamoeba development and open the door to the development of RNAi-based gene silencing tools in E. invadens.
“…The processes governing transcription and gene expression in
Entamoeba remain poorly understood. Recent efforts have elucidated mechanisms for stabilizing ribosomal RNA during encystation
24 as well as under stress conditions
25 . Forward-genetic screens have helped determine the target genes regulated by specific signaling transduction pathways
26 .…”
In recent years, substantial progress has been made in understanding the molecular and cell biology of the human parasite
Entamoeba histolytica, an important pathogen with significant global impact. This review outlines some recent advances in the
Entamoeba field in the last five years, focusing on areas that have not recently been discussed in detail: (i) molecular mechanisms regulating parasite gene expression, (ii) new efforts at drug discovery using high-throughput drug screens, and (iii) the effect of gut microbiota on amoebiasis.
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