Project description:BACKGROUND:Differentiation of one life-cycle stage to the next is critical for survival and transmission of apicomplexan parasites. A number of studies have shown that stage differentiation is a stochastic process and is associated with a point that commits the cell to a change over in the pattern of gene expression. Studies on differentiation to merozoite production (merogony) in T. annulata postulated that commitment involves a concentration threshold of DNA binding proteins and an auto-regulatory loop. PRINCIPAL FINDINGS:In this study ApiAP2 DNA binding proteins that show changes in expression level during merogony of T. annulata have been identified. DNA motifs bound by orthologous domains in Plasmodium were found to be enriched in upstream regions of stage-regulated T. annulata genes and validated as targets for the T. annulata AP2 domains by electrophoretic mobility shift assay (EMSA). Two findings were of particular note: the gene in T. annulata encoding the orthologue of the ApiAP2 domain in the AP2-G factor that commits Plasmodium to gametocyte production, has an expression profile indicating involvement in transmission of T. annulata to the tick vector; genes encoding related domains that bind, or are predicted to bind, sequence motifs of the type 5'-(A)CACAC(A) are implicated in differential regulation of gene expression, with one gene (TA11145) likely to be preferentially up-regulated via auto-regulation as the cell progresses to merogony. CONCLUSIONS:We postulate that the Theileria factor possessing the AP2 domain orthologous to that of Plasmodium AP2-G may regulate gametocytogenesis in a similar manner to AP2-G. In addition, paralogous ApiAP2 factors that recognise 5'-(A)CACAC(A) type motifs could operate in a competitive manner to promote reversible progression towards the point that commits the cell to undergo merogony. Factors possessing AP2 domains that bind (or are predicted to bind) this motif are present in the vector-borne genera Theileria, Babesia and Plasmodium, and other Apicomplexa; leading to the proposal that the mechanisms that control stage differentiation will show a degree of conservation.

Project description:Bovine tropical theileriosis is a major haemoprotozoan disease associated with high rates of morbidity and mortality particularly in exotic and crossbred cattle. It is one of the major constraints for of the livestock development programmes in India and southern Asia. Indigenous cattle (Bos indicus) are less affected by this disease than exotic and crossbred cattle. Genetic basis of resistance to tropical theileriosis in indigenous cattle is not well studied. Recent studies gives an idea that differentially genes expressed in exotic and indigenous breeds play an important role in breed specific resistance to tropical theileriosis. The present study was designed to visualize the global gene expression profiling in PBMCs derived from indigenous (Tharparkar) and crossbred cattle with in vitro infection of T. annulata. T. annulata Parbhani strain, originally isolated from Maharashtra (India) and maintained as cryopreserved stabilates of ground-up tick tissue sporozoite (GUTS) of infected H. anatolicum anatolicum was used as infective material. Two separate microarray experiments were carried out using separately each for crossbred and Tharparkar cattle. The crossbred cattle showed 1082 differentially expressed genes (DEGs). Out of total DEGs, 597 genes were downregulated and 485 were upregulated. Their fold change varies from 2283.93 to -4816.02. Tharparkar cattle showed 875 differentially expressed genes. Out of total DEGs in Tharparkar cattle, 451 genes were downregulated and 424 genes were upregulated. Their fold change varies from 94.93 to -19.20. A subset of genes was validated by quantitative RT-PCR and results correlated well with data obtained from the microarrays indicating that the microarray results gave an accurate report of transcript level. Functional annotation study of differentially expressed genes has confirmed their involvement in various pathways including response to oxidative stress, immune system regulation, cell proliferation, cytoskeletal changes, kinases activity and apoptosis. Gene network analysis of these differentially expressed genes provided an effective way to understand the interaction among them. It is therefore, hypothesised that the dissimilar susceptibility to tropical theileriosis exhibited by indigenous and crossbred cattle is due to breed-specific differences in the interaction of infected cells with other immune cells, which ultimately influences the immune response generated against T. annulata infection.

Project description:Bovine tropical theileriosis is a major haemoprotozoan disease associated with high rates of morbidity and mortality particularly in exotic and crossbred cattle. It is one of the major constraints for of the livestock development programmes in India and southern Asia. Indigenous cattle (Bos indicus) are less affected by this disease than exotic and crossbred cattle. Genetic basis of resistance to tropical theileriosis in indigenous cattle is not well studied. Recent studies gives an idea that differentially genes expressed in exotic and indigenous breeds play an important role in breed specific resistance to tropical theileriosis. The present study was designed to visualize the global gene expression profiling in PBMCs derived from indigenous (Tharparkar) and crossbred cattle with in vitro infection of T. annulata. T. annulata Parbhani strain, originally isolated from Maharashtra (India) and maintained as cryopreserved stabilates of ground-up tick tissue sporozoite (GUTS) of infected H. anatolicum anatolicum was used as infective material. Two separate microarray experiments were carried out using separately each for crossbred and Tharparkar cattle. The crossbred cattle showed 1082 differentially expressed genes (DEGs). Out of total DEGs, 597 genes were downregulated and 485 were upregulated. Their fold change varies from 2283.93 to -4816.02. Tharparkar cattle showed 875 differentially expressed genes. Out of total DEGs in Tharparkar cattle, 451 genes were downregulated and 424 genes were upregulated. Their fold change varies from 94.93 to -19.20. A subset of genes was validated by quantitative RT-PCR and results correlated well with data obtained from the microarrays indicating that the microarray results gave an accurate report of transcript level. Functional annotation study of differentially expressed genes has confirmed their involvement in various pathways including response to oxidative stress, immune system regulation, cell proliferation, cytoskeletal changes, kinases activity and apoptosis. Gene network analysis of these differentially expressed genes provided an effective way to understand the interaction among them. It is therefore, hypothesised that the dissimilar susceptibility to tropical theileriosis exhibited by indigenous and crossbred cattle is due to breed-specific differences in the interaction of infected cells with other immune cells, which ultimately influences the immune response generated against T. annulata infection. Global gene expression profiling in PBMCs derived from indigenous (Tharparkar) and crossbred cattle were studied after in vitro infection of T. annulata Parbhani strain at 2h time period. Two separate microarray experiments were carried out using Bovine (V2) Gene Expression Microarray, 4x44K (Agilent). Two biological replicate samples were profiled per condition (i.e. replicates samples each in crossbred and Tharparkar cattle).

Project description:Background: Considerable work has been carried out to understand the biology of the intermediate stages, the tachyzoite and bradyzoite, of Toxoplasma gondii in large part due to the accessible culturing methods for these stages. However, culturing methods for stages beyond the bradyzoite, including the merozoite and sexual stages, have not been developed hindering the ability to study a large portion of the parasite’s life cycle. We begin to unravel the molecular aspects of the merozoite stage focusing on gene expression. Results: To initiate this, we harvested merozoite parasites and hybridized mRNA to the Affymetrix Toxoplasma GeneChip. We analyzed the merozoite data in context of the life cycle by combining it with a previously published study that generated array data for the oocyst, tachyzoite, and bradyzoite stages (Fritz HM et al. PLoS One, 2012). Principal component analysis highlights the unique profile of the merozoite samples, placing them approximately half-way on a continuum between the tachyzoite/bradyzoite and oocyst samples. Prior studies have shown that antibodies to surface antigen p30 (SAG1) and many dense granule proteins do not label merozoites, and our microarray data confirms that these genes are not expressed at this stage. Also, the expression for many rhoptry and microneme proteins is drastically reduced while the expression for many surface antigens is increased at the merozoite stage. Gene Ontology and KEGG analysis reveals that genes involved in transcription/translation and many metabolic pathways are upregulated at the merozoite stage, highlighting unique growth requirements of this stage. We also show that an upstream promoter region of a merozoite specific gene is sufficient to control stage specific expression at the merozoite stage. Conclusion: The merozoite represents the first developmental stage within the gut of the definitive host. Determining the correct conditions that coax the parasite into the merozoite stage in vitro may allow the parasite to complete sexual development. The data presented here describe the global gene expression profile of merozoite stage and the creation of transgenic parasite strains that will be useful in unlocking how the parasite senses and responds to the felid gut environment to initiate coccidian development. The ToxoGeneChip microarray was used to measure both tachyzoite and merozoite mRNA expression in the type II TgNmBr1 strain.

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ApiAP2 Factors as Candidate Regulators of Stochastic Commitment to Merozoite Production in Theileria annulata

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