Seroprevalence of Toxoplasma gondii infection in domestic sheep in Durango State, Mexico

The seroprevalence of Toxoplasma gondii infection in sheep (Ovis aries) in northern Mexico is largely unknown. Antibodies to T. gondii were determined in serum samples from 511 sheep from 8 farms in Durango State, Mexico, using the modified agglutination test (MAT). Sheep were raised in 3 geographical regions, i.e., mountainous (n = 68), semi-desert (n = 132), and valley (n = 311). Overall, T. gondii antibodies were found in 77 (15.1%) of 511 sheep, with MAT titers of 1∶25 in 27, 1∶50 in 10, 1∶100 in 11, 1∶200 in 11, 1∶400 in 8, 1∶800 in 3, 1∶1,600 in 4, and 1∶3,200 in 3. The seroprevalence of T. gondii infection increased significantly with age, indicating post-natal transmission. In contrast, gender, breed, flock size, and geographic region did not significantly influence the seroprevalence. Seropositive sheep were found in 7 of 8 farms sampled. This is the first report of T. gondii infection in sheep in Durango State, Mexico. Results indicate that infected sheep are probably an important source of T. gondii infection for humans in Durango State.     

Nickel and Ultraviolet-B Stresses Induce Differential Growth and Photosynthetic Responses in Pisum sativum L. Seedlings

Enhanced level of UV-B radiation and heavy metals in irrigated soils due to anthropogenic activities are deteriorating the environmental conditions necessary for growth and development of plants. The present study was undertaken to study the individual and interactive effects of heavy metal nickel (NiCl(2)·6H(2)O; 0.01, 0.1, 1.0?mM) and UV-B exposure (0.4 W m(-2); 45?min corresponds to 1.08 KJ m(-2)) on growth performance and photosynthetic activity of pea (Pisum sativum L.) seedlings. Ni treatment at high doses (0.1 and 1.0?mM Ni) and UV-B alone reduced chlorophyll content and photosynthetic activity (oxygen yield, carbon fixation, photorespiration, and PSI, PSII, and whole chain electron transport activities), and declining trends continued with combined doses. In contrast to this, Ni at 0.01?mM appeared to be stimulatory for photosynthetic pigments and photosynthetic activity, thereby enhanced biomass was observed at this concentration. However, combined dose (UV-B + 0.01?mM Ni) caused inhibitory effects. Carotenoids showed different responses to each stress. Nickel at high doses strongly inhibited PSII activity and the inhibition was further intensified when chloroplasts were simultaneously exposed to UV-B radiation. PSI activity appeared to be more resistant to each stress. High doses of Ni (0.1and 1.0?mM) and UV-B alone interrupted electron flow at the oxygen evolving complex. Similar damaging effects were caused by 0.01 and 0.1?mM Ni together with UV-B, but the damage extended to PSII reaction center in case of 1.0?mM Ni in combination with UV-B. In conclusion, the results demonstrate that low dose of Ni stimulated the growth performance of pea seedlings in contrast to its inhibitory role at high doses. However, UV-B alone and together with low as well as high doses of Ni proved to be toxic for P. sativum L.     

ABCB6 mutations cause ocular coloboma

Ocular coloboma is a developmental defect of the eye and is due to abnormal or incomplete closure of the optic fissure. This disorder displays genetic and clinical heterogeneity. Using a positional cloning approach, we identified a mutation in the ATP-binding cassette (ABC) transporter ABCB6 in a Chinese family affected by autosomal-dominant coloboma. The Leu811Val mutation was identified in seven affected members of the family and was absent in six unaffected members from three generations. A LOD score of 3.2 at θ = 0 was calculated for the mutation identified in this family. Sequence analysis was performed on the ABCB6 exons from 116 sporadic cases of microphthalmia with coloboma (MAC), isolated coloboma, and aniridia, and an additional mutation (A57T) was identified in three patients with MAC. These two mutations were not present in the ethnically matched control populations. Immunostaining of transiently transfected, Myc-tagged ABCB6 in retinal pigment epithelial (RPE) cells showed that it localized to the endoplasmic reticulum and Golgi apparatus of RPE cells. RT-PCR of ABCB6 mRNA in human cell lines and tissue indicated that ABCB6 is expressed in the retinae and RPE cells. Using zebrafish, we show that abcb6 is expressed in the eye and CNS. Morpholino knockdown of abcb6 in zebrafish produces a phenotype characteristic of coloboma and replicates the clinical phenotype observed in our index cases. The knockdown phenotype can be corrected with coinjection of the wild-type, but not mutant, ABCB6 mRNA, suggesting that the phenotypes observed in zebrafish are due to insufficient abcb6 function. Our results demonstrate that ABCB6 mutations cause ocular coloboma.     

Biological characterization of lead-enhanced exopolysaccharide produced by a lead resistant Enterobacter cloacae strain P2B

A lead resistant bacterial strain isolated from effluent of lead battery manufacturing company of Goa, India has been identified as Enterobacter cloacae strain P2B based on morphological, biochemical characters, FAME profile and 16S rDNA sequence data. This bacterial strain could resist lead nitrate up to 1.6?mM. Significant increase in exopolysaccharide (EPS) production was observed as the production increased from 28 to 108?mg/L dry weight when exposed to 1.6?mM lead nitrate in Tris buffered minimal medium. Fourier-transformed infrared spectroscopy of this EPS revealed presence of several functional groups involved in metal binding viz. carboxyl, hydroxyl and amide groups along with glucuronic acid. Gas chromatography coupled with mass spectrometry analysis of alditol-acetate derivatives of acid hydrolysed EPS produced in presence of 1.6?mM lead nitrate demonstrated presence of several neutral sugars such as rhamnose, arabinose, xylose, mannose, galactose and glucose, which contribute to lead binding hydroxyl groups. Scanning electron microscope coupled with energy dispersive X-ray spectrometric analysis of this lead resistant strain exposed to 1.6?mM lead nitrate interestingly revealed mucous EPS surrounding bacterial cells which sequestered 17?% lead (as weight %) extracellularly and protected the bacterial cells from toxic effects of lead. This lead resistant strain also showed multidrug resistance. Thus these results significantly contribute to better understanding of structure, function and environmental application of lead-enhanced EPSs produced by bacteria. This lead-enhanced biopolymer can play a very important role in bioremediation of several heavy metals including lead.     

Improvement of tablet coating uniformity using a quality by design approach

A combination of analytical and statistical methods is used to improve a tablet coating process guided by quality by design (QbD) principles. A solid dosage form product was found to intermittently exhibit bad taste. A suspected cause was the variability in coating thickness which could lead to the subject tasting the active ingredient in some tablets. A number of samples were analyzed using a laser-induced breakdown spectroscopy (LIBS)-based analytical method, and it was found that the main variability component was the tablet-to-tablet variability within a lot. Hence, it was inferred that the coating process (performed in a perforated rotating pan) required optimization. A set of designed experiments along with response surface modeling and kriging method were used to arrive at an optimal set of operating conditions. Effects of the amount of coating imparted, spray rate, pan rotation speed, and spray temperature were characterized. The results were quantified in terms of the relative standard deviation of tablet-averaged LIBS score and a coating variability index which was the ratio of the standard deviation of the tablet-averaged LIBS score and the weight gain of the tablets. The data-driven models developed based on the designed experiments predicted that the minimum value of this index would be obtained for a 6% weight gain for a pan operating at the highest speed at the maximum fill level while using the lowest spraying rate and temperature from the chosen parametric space. This systematic application of the QbD-based method resulted in an enhanced process understanding and reducing the coating variability by more than half.     

Extensive genetic diversity, unique population structure and evidence of genetic exchange in the sexually transmitted parasite Trichomonas vaginalis

Background

Trichomonas vaginalis is the causative agent of human trichomoniasis, the most common non-viral sexually transmitted infection world-wide. Despite its prevalence, little is known about the genetic diversity and population structure of this haploid parasite due to the lack of appropriate tools. The development of a panel of microsatellite makers and SNPs from mining the parasite''s genome sequence has paved the way to a global analysis of the genetic structure of the pathogen and association with clinical phenotypes.

Methodology/Principal Findings

Here we utilize a panel of T. vaginalis-specific genetic markers to genotype 235 isolates from Mexico, Chile, India, Australia, Papua New Guinea, Italy, Africa and the United States, including 19 clinical isolates recently collected from 270 women attending New York City sexually transmitted disease clinics. Using population genetic analysis, we show that T. vaginalis is a genetically diverse parasite with a unique population structure consisting of two types present in equal proportions world-wide. Parasites belonging to the two types (type 1 and type 2) differ significantly in the rate at which they harbor the T. vaginalis virus, a dsRNA virus implicated in parasite pathogenesis, and in their sensitivity to the widely-used drug, metronidazole. We also uncover evidence of genetic exchange, indicating a sexual life-cycle of the parasite despite an absence of morphologically-distinct sexual stages.

Conclusions/Significance

Our study represents the first robust and comprehensive evaluation of global T. vaginalis genetic diversity and population structure. Our identification of a unique two-type structure, and the clinically relevant phenotypes associated with them, provides a new dimension for understanding T. vaginalis pathogenesis. In addition, our demonstration of the possibility of genetic exchange in the parasite has important implications for genetic research and control of the disease.     

Seroprevalence of Toxoplasma gondii in equids from Southern Spain

Antibodies to Toxoplasma gondii were determined in serum samples from 616 equids (454 horses, 80 mules and 82 donkeys) in a cross-sectional study of 420 herds in Andalusia (Southern Spain), the region with the highest number of equids in Spain. Antibodies to T. gondii were found in 10.8% horses, 15.0% mules and 25.6% donkeys by using the modified agglutination test (MAT) at a cut-off of 1:25. Herd seroprevalence for horses, mules and donkeys was 14.7% (48/327), 23.9% (11/46) and 34.0% (16/47), respectively, and 75 herds (17.8%) had at least one seropositive animal. Significant differences in T. gondii seroprevalence were observed among species, with donkeys having the highest seroprevalence and horses the lowest (P=0.04). Seroprevalence was significantly higher in herds with presence of domestic ruminants. This study is the first report of the presence of T. gondii antibodies in equine species in Spain and the first reporting T. gondii infection in donkeys in Europe. The presence of antibodies is indication of contact with the parasite and therefore, consumption of equine meat could be a potential source of human infection in Spain.     

Structure prediction and evolution of a halo-acid dehalogenase of Burkholderia mallei

Environmental pollutants containing halogenated organic compounds e.g. haloacid, can cause a plethora of health problems. The structural and functional analyses of the gene responsible of their degradation are an important aspect for environmental studies and are important to human well-being. It has been shown that some haloacids are toxic and mutagenic. Microorganisms capable of degrading these haloacids can be found in the natural environment. One of these, a soil-borne Burkholderia mallei posses the ability to grow on monobromoacetate (MBA). This bacterium produces a haloacid dehalogenase that allows the cell to grow on MBA, a highly toxic and mutagenic environmental pollutant. For the structural and functional analysis, a 346 amino acid encoding protein sequence of haloacid dehalogenase is retrieve from NCBI data base. Primary and secondary structure analysis suggested that the high percentage of helices in the structure makes the protein more flexible for folding, which might increase protein interactions. The consensus protein sub-cellular localization predictions suggest that dehalogenase protein is a periplasmic protein 3D2GO server, suggesting that it is mainly employed in metabolic process followed by hydrolase activity and catalytic activity. The tertiary structure of protein was predicted by homology modeling. The result suggests that the protein is an unstable protein which is also an important characteristic of active enzyme enabling them to bind various cofactors and substrate for proper functioning. Validation of 3D structure was done using Ramachandran plot ProsA-web and RMSD score. This predicted information will help in better understanding of mechanism underlying haloacid dehalogenase encoding protein and its evolutionary relationship.