Epidemiology and Prevalence of Blastocystis spp. in North Cyprus

AbstractThis study was conducted to investigate the prevalence of Blastocystis spp. and its subtypes (STs) in North Cyprus; and to evaluate the presence of this parasite and its STs with respect to demographic, socioeconomic, and epidemiological factors, as well as gastrointestinal symptoms. Stool samples were collected from 230 volunteers. Each participant also filled out a questionnaire. The samples were examined microscopically by native-Lugol and trichrome methods and further tested by polymerase chain reaction (PCR) and sequencing. Prevalence of Blastocystis spp. infection was found to be 10.5%, 10.5%, and 27.8%, by direct microscopy, trichrome method, and PCR, respectively. No other parasites were detected in the specimens except Giardia spp. (n = 2; 0.8%) and Entamoeba coli (n = 1; 0.4%). The most common Blastocystis STs were ST3 (20; 31.2%), ST2 (18; 28.2%), ST1 (8; 12.5%), and ST4 (7; 11%); whereas other STs were identified as ST6 (3; 4.7%), ST7 (2; 3.2%), and non-ST (6; 9.4%). Presence of Blastocystis spp. and its STs was not significantly related to any of the demographic, socioeconomic, and epidemiological factors. Furthermore, no significant association of Blastocystis spp. and its STs with gastrointestinal symptoms was found. This study is the first investigation of the epidemiology of Blastocystis spp. in North Cyprus. Distribution of Blastocystis spp. and its STs among demographic, socioeconomic, and epidemiological factors showed complete homogeneity. Presence of the parasite and its STs was not significantly related with the gastrointestinal symptoms among symptomatic and asymptomatic individuals. These findings suggest that Blastocystis spp. may be part of the intestinal flora in humans.

Is "dried stool spots on filter paper method (DSSFP)" more sensitive and effective for detecting Blastocystis spp. and their subtypes by PCR and sequencing?

PCR and DNA sequencing are currently the diagnostic methods of choice for detection of Blastocystis spp. and their suptypes. Fresh or frozen stool samples have disadvantages in terms of several aspects such as transportation, storage, and existence of PCR inhibitors. Filter paper technology may provide a solution to these issues. The aim of the present study was to detect Blastocystis spp. and their subtypes by employing two different preservation methods: conventional frozen stool (FS) and dried stool spots on filter paper (DSSFP). Concentration and purity of DNA, sensitivity of PCR, and DNA sequencing results obtained from the two methods were also compared. A total of 230 fecal samples were included and separated into two parts: one part of the fecal samples were directly frozen and stored at -20 °C. The remaining portion of the specimens were homogenized with saline and spread onto the filter papers as thin layer with a diameter of approximately 3 cm. After air-dried, the filter papers were stored at room temperature. DSSFP samples were collected by scraping from the filter papers. DNA were extracted by EURx Stool DNA Extraction Kit from both samples. Concentration and purity were measured with Nano-Drop, then PCR and sequencing were conducted for detection of Blastocystis spp. and its genotypes. Pure DNA was obtained with a A260/A280 ratio of 1.7-2.2 in both methods. DNA yield from FS was 25-405 ng/μl and average DNA concentration was 151 ng/μl, while these were 7-339 and 122 ng/μl for DSSFP, respectively. No PCR inhibition was observed in two methods. DNA from DSSFP were found to be stable and PCR were reproducible for at least 1 year. FS-PCR- and DSSFP-PCR-positive samples were 49 (21.3 %) and 58 (25.3 %), respectively (p = 0.078). The 43 specimens were concordantly positive by both FS-PCR and DSSFP-PCR. When the microscopy was taken as the gold standard, sensitivity of DSSFP-PCR and FS-PCR was 95.5 and 86.4 %, while specificity of both tests was 99.4 and 98.3 %, respectively. DNA sequencing results of 19 microscopically confirmed cases were strictly identical (concordance 100 %) in both methods, and ST2:6, ST3:8, ST4:3, and ST6:2 were the detected subtypes. Among the 230 fecal samples, the most predominant subtypes were ST3, ST2, ST4, and ST1 by both FS and DSSFP methods. Concordance of DNA sequencing results obtained from the two methods was noted to be 90.7 %. To our knowledge, this is the first study that demonstrates DNA extraction from DSSFP is more sensitive and effective than the FS method for diagnosis of Blastocystis spp. and their subtypes by PCR and DNA sequencing.

Design of fluorescent substrates and potent inhibitors of CYP73As, P450s that catalyze 4-hydroxylation of cinnamic acid in higher plants

CYP73As are the major functional cytochromes P450 in higher plants. Several of them have been shown to catalyze the 4-hydroxylation of cinnamic acid, the first oxidative step in the synthesis of lignin, flavonoids, coumarins, and other phenylpropanoids. The coding sequence for CYP73A1, the enzyme from Helianthus tuberosus, has been isolated and expressed in yeast. Previous studies indicate that the yeast-expressed enzyme is capable of metabolizing cinnamic acid and several small, planar molecules but with low efficiency. Using this we further examined how CYP73A1 could bind and metabolize a set of possible alternate substrates. We show here that naphthalenes, quinolines, and indoles substituted with an aldehyde, a carboxylic, or a sulfonic acid group make good ligands and substrates for CYP73A1. The best ligands are hydroxynaphthoic acids, which show higher affinity than cinnamate. Naphthalene, 2-naphthol, and molecules with two-carbon side chains, such as natural and synthetic auxins, are not substrates of this enzyme. Methyl-2-naphthoate and 2-hydroxy-1-naphthoic acid are strong ligands of CYP73A1 but are not metabolized. Uncoupling and low spin conversion induced by these compounds suggest that their positioning in the heme pocket is inadequate for catalysis. These compounds can act as potent inhibitors of the second step of the phenylpropanoid pathway, the first described so far. The molecule which most closely mimics cinnamic acid, 2-naphthoic acid, is metabolized with a catalytic turnover and efficiency similar to those measured with the physiological substrate. Using this compound we designed a fluorometric assay to measure the catalytic activity of CYP73As. This assay was then used to monitor the CYP73As activity in microsomes from transgenic yeast and several plant species.