Proteomic profile of stress granules by high-resolution mass spectrometry.

Ribonucleoprotein granules are bio-condensates that form a diverse group of dynamic membrane-less organelles implicated in several cellular functions, including stress response and cellular survival. In , a type of bio-condensates referred to as stress granules (SGs) are formed prior to the parasites' egress from the host cell and are implicated in the survival and invasion competency of extracellular tachyzoites. We used paraformaldehyde to fix and cross-link SG proteins to allow purification by centrifugation and analysis by mass spectrometry.

Formation of mRNP granules in Toxoplasma gondii during the lytic cycle.

Two poly(A) binding proteins (PABPs) of Toxoplasma gondii, were identified and characterized. They were named TgPABPC and TgPABPN as they were found to localize in the cytoplasm and nucleus respectively. TgPABPC, which colocalizes with mRNA granules, is therefore used as a cellular marker of mRNP granules.

Characterization of natural antisense transcripts arisen from the locus encoding Toxoplasma gondii ubiquitin-like protease.

Natural antisense transcripts (NATs) are non-protein coding RNAs that could play an important role in regulating the expression of their counterpart protein encoding sense transcript. Although NATs are widespread in most eukaryotic genomes, very little is known about their functions. This study focuses on gaining a better understanding of the function of NATs in Toxoplasma gondii, a pathogenic unicellular eukaryote.

Sensory cutaneous papillae in the sea lamprey (Petromyzon marinus L.): II. Ontogeny and immunocytochemical characterization of solitary chemosensory cells.

Solitary chemosensory cells (SCCs) and their innervating fibers are located in the respiratory system of many vertebrates, including papillae on lamprey gill pores. In order to gain stronger insight for the role of these chemosensory cells, we examined immunocytochemical and innervation characteristics, as well as abundance at the different stages of the lamprey life cycle. The SCCs were distinguished from the surrounding epithelial cells by calretinin and phospholipase C140 immunoreactivity.

Toxoplasma ubiquitin-like protease 1, a key enzyme in sumoylation and desumoylation pathways, is under the control of non-coding RNAs.

Sumoylation and desumoylation are reversible pathways responsible for modification of protein structures and functions by the reversible covalent attachment of a small ubiquitin-like modifier (SUMO) peptide. These pathways are important for a wide range of cellular processes and require a steady supply of SUMO, which is generated by an enzymatic reaction catalysed by the ubiquitin-like protease (Ulp) family. Here we show by functional complementation analysis that the Ulp1 of Toxoplasma gondii (TgUlp1) can rescue a growth-deficient phenotype of a yeast-Ulp1 knockout.

Toxoplasma gondii infection induces the formation of host's nuclear granules containing poly(A)-binding proteins.

To study the mechanism by which human host cells respond to an infection of Toxoplasma gondii, we monitored the level of poly(A)-binding protein (PABP), an indicator of translation. Here, we report an observation of the relocalization of PABPs in human host cells upon T. gondii infection.

Antisense technologies in the studying of Toxoplasma gondii.

This review covers a brief history of antisense RNAs and its applications, and summarizes the current stage of antisense technologies used in Toxoplasma gondii, a fascinating model organism with a unique characteristic blend of genetic regulatory systems normally found in plants or animals. Based on the current knowledge of regulatory RNAs and non-coding RNA (ncRNA), the antisense technologies are reviewed according to the classification of ncRNAs, which are roughly categorized into small, ranging from ~20-200 nucleotides in length, and long >200 nucleotides. Techniques utilizing small regulatory RNAs such as siRNA, miRNA, antagomirs, ribozymes and morpholino oligomers are discussed along with long non-coding RNA (lncRNA) including antisense and double stranded.

Utilization of inherent miRNAs in functional analyses of Toxoplasma gondii genes.

MicroRNAs (miRNAs) are crucial genetic effectors partaking in numerous mechanisms of gene regulation in eukaryotic organisms. Recent discoveries of miRNA in Toxoplasma gondii, an intracellular obligate parasite of the phylum Apicomplexa, suggested possible roles of T. gondii miRNAs (Tg-miRNAs) in the post-transcriptional gene regulation and in the cell biology of the parasite.

Sustained translational repression of lactate dehydrogenase 1 in Toxoplasma gondii bradyzoites is conferred by a small regulatory RNA hairpin.

In response to environmental stresses, Toxoplasma gondii induces a global translational repression which allows for the remodeling of its transcriptome. While some transcripts are preferentially translated, another subset is translationally repressed and maintained in bradyzoites. Although little is known of how transcripts are targeted for sustained translational repression, the targeting probably operates through an RNA-centric mechanism relying on the recognition of cis-acting elements.

The potential of quinoline derivatives for the treatment of Toxoplasma gondii infection.

Here we reported our investigation, as part of our drug repositioning effort, on anti-Toxoplasma properties of newly synthesized quinoline compounds. A collection of 4-aminoquinoline and 4-piperazinylquinoline analogs have recently been synthesized for use in cancer chemotherapy. Some analogs were able to outperform chloroquine, a quinoline derivative drug which is commonly used in the treatment of malaria and other parasitic infections.

Characterization of a homolog of DEAD-box RNA helicases in Toxoplasma gondii as a marker of cytoplasmic mRNP stress granules.

Toxoplasma gondii is an obligate intracellular protozoan which infects one-third of the human population. Due to its high infection prevalence, Toxoplasma offers an ideal system for the study of host-parasite interaction. Similar to other eukaryotes, Toxoplasma maintains levels and localization of cytoplasmic mRNAs throughout its life cycle as part of a gene regulation network to meet all cellular and biochemical requirements.

Endoplasmic reticulum stress-mediated inhibition of NSMase2 elevates plasma membrane cholesterol and attenuates NO production in endothelial cells.

Chronic exposure of blood vessels to cardiovascular risk factors such as free fatty acids, LDL-cholesterol, homocysteine and hyperglycemia can give rise to endothelial dysfunction, partially due to decreased synthesis and bioavailability of nitric oxide (NO). Many of these same risk factors have been shown to induce endoplasmic reticulum (ER) stress in endothelial cells. The objective of this study was to examine the mechanisms responsible for endothelial dysfunction mediated by ER stress.

Evidence for behavioral preference toward environmental concentrations of urban-use herbicides in a model adult fish.

Fish live in waters of contaminant flux. In three urban, fish-bearing waterways of British Columbia, Canada, we found the active ingredients of WeedEx, KillEx, and Roundup herbicide formulations (2,4-D, dicamba, glyphosate, and mecoprop) at low to high ng/L concentrations (0.26 to 309 ng/L) in routine conditions, i.

Toxoplasma gondii: inhibitory activity and encystation effect of securinine and pyrrolidine derivatives on Toxoplasma growth.

Securinine, an alkaloid originally isolated from Securinega suffruticosa, exhibits a wide range of biological activities, including anti-malarial activity. Along with securinine, 10 pyrrolidine derivatives, generated via the retrosynthesis of (-)-securinine, were selected and tested for their inhibitory activity against Toxoplasma gondii growth in vitro. Anti-Toxoplasma activity correlated to hydrophobicity of the tested compounds.

Silencing of tachyzoite enolase 2 alters nuclear targeting of bradyzoite enolase 1 in Toxoplasma gondii.

In Toxoplasma gondii, an intracellular parasite of the phylum Apicomplexa, two isoforms of enolase (ENO1 and ENO2) are expressed in stage-specific manner. ENO2 is expressed only in rapidly growing tachyzoites, while ENO1 is in slowly growing bradyzoites. Interestingly, the localization of ENO1 and ENO2 in the nuclear compartment has suggested possible roles of the proteins in gene regulation and/or cell cycle.

Toxoplasma gondii: over-expression of lactate dehydrogenase enhances differentiation under alkaline conditions.

Toxoplasma gondii, an intracellular parasite, has two distinctive growth stages, namely rapidly growing tachyzoites and slowly growing bradyzoites. Here we report a unique physiological function of the last committed glycolytic enzyme of T. gondii, lactate dehydrogenase (TgLDH), which is present in two isoforms and expressed in a stage-specific manner.

Plasma membrane cholesterol content affects nitric oxide diffusion dynamics and signaling.

Nitric oxide (NO) signaling is inextricably linked to both its physical and chemical properties. Due to its preferentially hydrophobic solubility, NO molecules tend to partition from the aqueous milieu into biological membranes. We hypothesized that plasma membrane ordering provided by cholesterol further couples the physics of NO diffusion with cellular signaling.

Density functional theory investigation on the mechanism of the hepatitis delta virus ribozyme.

Density functional theory methods have been used to investigate the hepatitis delta virus (HDV) ribozyme and its catalyzed phosphodiester cleavage. In particular, the effects of the environment's polarity and/or specific hydrogen-bond interactions on the proton affinity of the active site cytosine's N3 ring center have been considered. In addition, the basicities of possible hydrated Mg2+ ion species were also examined.

Single argonaute protein from Toxoplasma gondii is involved in the double-stranded RNA induced gene silencing.

Here, we report the characterization of the argonaute protein from Toxoplasma gondii. This is the first report on the function of an argonaute protein with structural features overlapping between argonaute proteins of archaeal bacteria and eukaryotes. The full-length cDNA clone has an open reading frame of 1575 bp, which encodes a 524 amino acid protein with a calculated molecular weight of 58.

The expression of lactate dehydrogenase is important for the cell cycle of Toxoplasma gondii.

In Toxoplasma gondii, lactate dehydrogenase is encoded by two independent and developmentally regulated genes LDH1 and LDH2. These genes and their products have been implicated in the control of a metabolic flux during parasite differentiation. To investigate the significance of LDH1 and LDH2 in this process, we generated stable transgenic parasite lines in which the expression of these two expressed isoforms of lactate dehydrogenase was knocked down in a stage-specific manner.

Double-stranded RNA can mediate the suppression of uracil phosphoribosyltransferase expression in Toxoplasma gondii.

Double-stranded RNA (dsRNA) homologous to the Toxoplasma gondii uracil phosphoribosyltransferase (TgUPRT) gene is able to modulate the UPRT gene expression in T. gondii. The dsRNA, which was produced either from a constructed plasmid or from an in vitro transcription reaction, was capable of down-regulating the expression of TgUPRT.

Comparative analysis of antisense RNA, double-stranded RNA, and delta ribozyme-mediated gene regulation in Toxoplasma gondii.

RNA tools, namely, antisense RNA, double-stranded RNA (dsRNA), and delta ribozyme, were comparatively analyzed for the development of effective RNA-based gene modulators. The gene encoding uracil phosphoribosyltransferase (UPRT) of Toxoplasma gondii was used as a target and a negative selectable marker. Using plasmid transformation and drug selection assays, we obtained T.