A comparison of the Giardia lamblia trophozoite and cyst transcriptome using microarrays

<p>Abstract</p> <p>Background</p> <p>Compared with many protists, <it>Giardia lamblia </it>has a simple life cycle alternating between cyst and trophozoite. Most research on the molecular biology of <it>Giardia </it>parasites has focused on trophozoites and the processes of excystation and encystation, whereas cysts have attracted less interest. The striking morphological differences between the dormant cyst and the rapidly dividing and motile trophozoite implies profound changes in the metabolism as the parasite encysts in the host's intestine and excysts upon ingestion by a new host.</p> <p>Results</p> <p>To investigate the magnitude of the transcriptional changes occurring during the <it>G. lamblia </it>life cycle we compared the transcriptome of <it>G. lamblia </it>trophozoites and cysts using single-color oligonucleotide microarrays. Cysts were found to possess a much smaller transcriptome, both in terms of mRNA diversity and abundance. Genes encoding proteins related to ribosomal functions are highly over-represented. The comparison of the transcriptome of cysts generated in culture or extracted from feces revealed little overlap, raising the possibility of significant biological differences between the two types of cysts.</p> <p>Conclusions</p> <p>The comparison of the <it>G. lamblia </it>cyst and trophozoite transcriptome showed that transcripts of most genes are present at a lower level in cysts. This global view of the cyst and trophozoite transcriptome complements studies focused on the expression of selected genes during trophozoite multiplication, encystation and excystation.</p

Suppressing Glucose Transporter Gene Expression in Schistosomes Impairs Parasite Feeding and Decreases Survival in the Mammalian Host

Adult schistosomes live in the host's bloodstream where they import nutrients such as glucose across their body surface (the tegument). The parasite tegument is an unusual structure since it is enclosed not by the typical one but by two closely apposed lipid bilayers. Within the tegument two glucose importing proteins have been identified; these are schistosome glucose transporter (SGTP) 1 and 4. SGTP4 is present in the host interactive, apical tegumental membranes, while SGTP1 is found in the tegumental basal membrane (as well as in internal tissues). The SGTPs act by facilitated diffusion. To examine the importance of these proteins for the parasites, RNAi was employed to knock down expression of both SGTP genes in the schistosomula and adult worm life stages. Both qRT-PCR and western blotting analysis confirmed successful gene suppression. It was found that SGTP1 or SGTP4-suppressed parasites exhibit an impaired ability to import glucose compared to control worms. In addition, parasites with both SGTP1 and SGTP4 simultaneously suppressed showed a further reduction in capacity to import glucose compared to parasites with a single suppressed SGTP gene. Despite this debility, all suppressed parasites exhibited no phenotypic distinction compared to controls when cultured in rich medium. Following prolonged incubation in glucose-depleted medium however, significantly fewer SGTP-suppressed parasites survived. Finally, SGTP-suppressed parasites showed decreased viability in vivo following infection of experimental animals. These findings provide direct evidence for the importance of SGTP1 and SGTP4 for schistosomes in importing exogenous glucose and show that these proteins are important for normal parasite development in the mammalian host

The Tegument of the Human Parasitic Worm Schistosoma mansoni as an Excretory Organ: The Surface Aquaporin SmAQP Is a Lactate Transporter

Adult schistosomes are intravascular parasites that metabolize imported glucose largely via glycolysis. How the parasites get rid of the large amounts of lactic acid this generates is unknown at the molecular level. Here, we report that worms whose aquaporin gene (SmAQP) has been suppressed using RNAi fail to rapidly acidify their culture medium and excrete less lactate compared to controls. Functional expression of SmAQP in Xenopus oocytes demonstrates that this protein can transport lactate following Michaelis-Menten kinetics with low apparent affinity (Km = 41±5. 8 mM) and with a low energy of activation (Ea = 7.18±0.7 kcal/mol). Phloretin, a known inhibitor of lactate release from schistosomes, also inhibits lactate movement in SmAQP-expressing oocytes. In keeping with the substrate promiscuity of other aquaporins, SmAQP is shown here to be also capable of transporting water, mannitol, fructose and alanine but not glucose. Using immunofluorescent and immuno-EM, we confirm that SmAQP is localized in the tegument of adult worms. These findings extend the proposed functions of the schistosome tegument beyond its known capacity as an organ of nutrient uptake to include a role in metabolic waste excretion

A STUDY OF HYDATID CYST CASES IN IRAN, A SYSTEMATIC REVIEW

Hydatid cyst is an infectious disease common between humans and animals which is spread worldwide and has been known to humans since old times. Different accounts have been presented on the individual characteristics of people suffering from hydatid cyst, clinical course, different treatment and diagnosis methods, and its recurrence. The hydatid cyst infection exits in various parts of the world, and Iran is on the endemic belt of the disease, in a way that different rates have been reported in different studies. Depending on climate conditions, social customs, nutritional status, and the amount of contact with canidae animals, incidence rates of up to 10% have been reported in human populations for these diseases. The present research is a systematic review study. In order to find the studies conducted in Iran, the articles in national and international journals and dissertations available on Magiran, Iranmedex, SID, Google-scholar, and PubMed databases were used, and more than 100 articles were found, among which 14 articles related to the topic that met the criteria for entering the study were investigated. The data collected were analyzed by SPSS version 18 through using descriptive-analytical statistics and chi-squared statistical test (X2 test). The results of the study showed that infection rate in the liver of cows to hydatid cyst is 62%, while lung infection in native and hybrid breeds in the city of Baneh is 7.75%. In rural area of Tehran, 437 person, 276 women and 161 men, in the age range of 4-76 years of age were studied, and one person was positive and seven persons were suspected to the disease. The results of the present study showed that, although the infection rate of hydatid cyst in urban and developed parts of Iran is at an acceptable and satisfactory level, the statistics in lesser-developed areas is endemic and alarming and deserves paying more attention and developing organized plans to control the disease. Keywords: Hydatid Cyst, Systematic Review, Iran

THE INCIDENCE OF RABIES IN IRAN- A SYSTEMATIC REVIEW

Information obtained on diseases common between humans and animals has led to significant improvements in the diagnosis and treatment of these diseases. However, this group of diseases infects a large number of animals and, on a smaller scale, humans. Rabies is one of the diseases caused by animal bite and in case of the emergence of clinical sings; it will definitely end in the death of the individual. Therefore, the present study has been conducted in order to investigate the incidence of rabies in Iran over the past few years. Present-researchis-a-systematic-review-study. In order to find the studies conducted in Iran, the articles in national and international journals and dissertations available on Magiran, Iranmedex, SID, Google-scholar, and PubMed databases were used. The data collected were analyzed by SPSS version 19 through using descriptive-analytical statistics and chi-squared statistical test (X2 test). the incidence rate of rabies was 4 cases per year in Ilam province, three of which were caused by dog and one of which was caused by cat bite. 25869 cases of animal bite were reported over five years, the most frequent of which was related to dog bite and was reported in rural areas. One case of a 46 years old patient affected with rabies caused by marten bite was reported in Tabriz. Keywords: Rabies, Systematic Review, Iran

The role of tegumental aquaporin from the human parasitic worm, Schistosoma mansoni, in osmoregulation and drug uptake

Schistosomes are parasitic platyhelminths that constitute an important public health problem globally. Infection is characterized by the presence of adult worms within the vasculature of their hosts, where they can reside for many years. The worms are covered by an unusual dual lipid bilayer through which they import nutrients. How the parasites import other vital molecules, such as water, is not known. Recent proteomic analysis of the schistosome tegumental membranes revealed the presence of an aquaporin homologue at the host-interactive surface whose cDNA we have cloned and characterized. The cDNA encodes a predicted 304-aa protein (SmAQP) that is found largely in the parasite tegument by immunolocalization and is most highly expressed in the intravascular life stages. Treatment of parasites with short interfering RNAs targeting the SmAQP gene results in potent (>90%) suppression. These suppressed parasites resist swelling when placed in hypotonic medium, unlike their control counterparts, which rapidly double in volume. In addition, SmAQP-suppressed parasites, unlike controls, resist shrinkage when incubated in hyperosmotic solution. While suppressed parasites exhibit lower viability in culture relative to controls and exhibit a stunted appearance following prolonged suppression, they are nonetheless more resistant to killing by the drug potassium antimonyl tartrate (PAT). This is likely because SmAQP acts as a conduit for this drug, as is the case for aquaporins in other systems. These experiments reveal a heretofore unrecognized role of the schistosome tegument in controlling water and drug movement into the parasites and highlight the importance of the tegument in parasite osmoregulation and drug uptake.—Faghiri, Z., Skelly, P. J. The role of tegumental aquaporin from the human parasitic worm, Schistosoma mansoni, in osmoregulation and drug uptake

Expression of SGTP1 and SGTP4 (mean ± SE) in schistosomula at different times after treatment with the indicated siRNA.

<p>Parasites were either maintained in culture for 7 days after treatment (white bars) or for 4 week after treatment (grey bars), or were recovered from infected mice 4 weeks after treatment (black bars). A, SGTP1; B, SGTP4.</p

Relative viability of schistosomes treated with SGTP siRNA.

<p>Schistosomula (mean ± SD) were treated with the indicated siRNA and their viability was established following culture for 14 days in RPMI medium either containing high glucose (10 mM, grey bars) or low glucose (0.05 mM, white bars).</p