Detection of Giardia duodenalis antigen in human fecal eluates by enzyme-linked immunosorbent assay using polyclonal antibodies

The present study developed and standardized an enzime-linked immunosorbent assay (ELISA) to detect Giardia antigen in feces using rabbit polyclonal antibodies. Giardia cysts were purified from human fecal samples by sucrose and percoll gradients. Gerbils (Meriones unguiculatus) were infected to obtain trophozoites. Rabbits were inoculated with either cyst or trophozoite antigens of 14 Colombian Giardia isolates to develop antibodies against the respective stages. The IgG anti-Giardia were purified by sequential caprylic acid and ammonium sulfate precipitation. A portion of these polyclonal antibodies was linked to alkaline phosphatase (conjugate). One hundred and ninety six samples of human feces, from different patients, were tested by parasitologic diagnosis: 69 were positive for Giardia cysts, 56 had no Giardia parasites, and 71 revealed parasites other than Giardia. The optimal concentration of polyclonal antibodies for antigen capture was 40 g/ml and the optimal conjugate dilution was 1:100. The absorbance cut-off value was 0.24. The parameters of the ELISA test for Giardia antigen detection were: sensitivity, 100% (95% CI: 93.4-100%); specificity, 95% (95% CI: 88.6-97.6%); positive predictive value, 91% (95% CI: 81.4-95.9%); and negative predictive value, 100% (95% CI: 96.1-100%). This ELISA will improve the diagnosis of Giardia infections in Colombia and will be useful in following patients after treatment.     

First recovery of Schistosoma mansoni eggs from a latrine in Europe (15-16th centuries)

Schistosoma mansoni eggs were found in a latrine dated AD 1450-1550 in Montbéliard, France. This is the first record of intestinal schistosomiasis in archaeological material. Because the parasite has an African origin, its presence in Europe at that time may be due to African slaves. However, intestinal schistosomiasis has never been established in Europe.     

Species of Malassezia associated with various dermatoses and healthy skin in the Mexican population

At the present, eight Malassezia species have been described and their distribution in normal skin and in several skin diseases appears variable. The aim of the present study was to determine the frequency and distribution of Malassezia species in patients with psoriasis, seborrhoeic dermatitis and pityriasis versicolor attended in a Hospital from Mexico City, in addition to a healthy individual group. Scales of abnormal and healthy skin were grown in modified Dixon agar and the species identification was performed by macroscopic and microscopic features; by catalase and urease reaction; growth at 32, 37 and 40 degrees C; and Tween 20, 40, 60 and 80 assimilation. The cultures from 63 persons were included: forty six patients (20 psoriasis, 15 seborrhoeic dermatitis, 11 pityriasis versicolor) and 17 healthy individuals (external auditory canal). A total of 96 isolates were obtained. The more frequently isolated species were: M. sympodialis (38.2%) and M. furfur (26.5%) in psoriasis; M. sympodialis (38.5%) and M. slooffiae (34.6%) in seborrhoeic dermatitis; M. globosa (46.7%) and M. sympodialis (26.7%) in pityriasis versicolor; and M. restricta (47.6%) and M. globosa (23.8%) in normal skin. The number of isolates, the species diversity and association were higher in the patients group than in the healthy individuals group.     

Stress proteins of<Emphasis Type="Italic"> Clostridium perfringens</Emphasis> type A immunoreact with antiserum from rabbits infected with gas gangrene

Various stressors were used to induce stress proteins in Clostridium perfringens. Cultures of C. perfringens FD-1041 were subjected to cold shock (28°C for 1 h), acid shock (pH 4.5 for 30 min), or heat shock (50°C for 30 min). Cells were lysed and protein samples were analyzed by immunoblotting with antiserum derived from rabbits suffering from gas gangrene. Eight cold shock proteins (approximate M_r 101, 82, 70, 37, 22, 12, 10 and 6 kDa) and also eight heat shock proteins (approximate M_r 101, 82, 70, 27, 22, 16, 12 and 10 kDa) were immunoreactive with the serum. No immunoreactive proteins were detected in samples subjected to acid shock proteins and purified DnaK protein was also non-immunoreactive with the serum. These immunogenic stress proteins may be important in regulating diseases caused by C. perfringens. Such proteins could be involved in cell survival mechanisms, serve as targets during infection, or play a role in recognition of the bacteria by the host.     

A set of simple-sequence repeat (SSR) markers covering the Prunus genome

A set of 109 microsatellite primer pairs recently developed for peach and cherry have been studied in the almond x peach F(2) progeny previously used to construct a saturated Prunus map containing mainly restriction fragment length polymorphism markers. All but one gave amplification products, and 87 (80%) segregated in the progeny and detected 96 loci. The resulting Prunus map contains a total of 342 markers covering a total distance of 522 cM. The approximate position of nine additional simple sequence repeats (SSRs) was established by comparison with other almond and peach maps. SSRs were placed in all the eight linkage groups of this map, and their distribution was relatively even, providing a genome-wide coverage with an average density of 5.4 cM/SSR. Twenty-four single-locus SSRs, highly polymorphic in peach, and each falling within 24 evenly spaced approximately 25-cM regions covering the whole Prunus genome, are proposed as a 'genotyping set' useful as a reference for fingerprinting, pedigree and genetic analysis of this species.     

Plant genome archaeology: evidence for conserved ancestral chromosome segments in dicotyledonous plant species

We have developed genetic maps, based on expressed sequence tags (ESTs) that are homologous to Arabidopsis genes, in four dicotyledonous crop plant species from different families. A comparison of these maps with the physical map of Arabidopsis reveals common genome segments that appear to have been conserved throughout the evolution of the dicots. In the four crop species analysed these segments comprise between 16 and 33% of the Arabidopsis genome. Our findings extend the synteny patterns previously observed only within plant families, and indicate that structural and functional information from the model species will be, at least in part, applicable in crop plants with large genomes.     

Lactose utilization by Saccharomyces cerevisiae strains expressing Kluyveromyces lactis LAC genes

Whey generated in cheese manufacture continues being an industrial problem without a satisfactory solution. Genetic modification of the yeast S. cerevisiae to obtain strains able to utilize lactose, is a prerequisite for the utilization of this yeast to convert cheese whey into useful fermentation products (i.e. biomass, heterologous protein and other recombinant products). Although the construction of S. cerevisiae Lac(+) strains has been achieved by different strategies, most of these strains have unsuitable characteristics, such as genetic instability of the Lac phenotype or diauxic growth. In previous communications we have described the construction of genetically stable strains of S. cerevisiae that assimilate lactose with a high efficiency. These strains carry multiple copies of Kluyveromyces lactis LAC4 and LAC12 genes, which code for a beta-galactosidase and a lactose permease, respectively. In this work we report additional results about the effect of gene dosage, and analyze the performance of a selected strain in the bioconversion of cheese whey. Additionally, we describe the construction of a new strain, which combines the Lac(+) phenotype with additional properties of biotechnological interest: flocculence, and the ability to hydrolyze starch.