Improvement of Mueller-Kauffman Tetrathionate-Novobiocin (MKTTn) enrichment medium for the detection of Salmonella enterica by the addition of ex situ-generated tetrathionate

The detection of Salmonella in food is based on the use of a selective enrichment broth such as Muller-Kauffman Tetrathionate-Novobiocin (MKTTn), in which tetrathionate plays a key role by providing Salmonella with a growth advantage. As sodium tetrathionate is unstable, it is generated in situ by the addition of iodine (Lugol's solution) before seeding. This step is cumbersome as the solution is easily spilled, compromising the performance of the medium and hindering the work of technicians. The aim of this study was to optimize MKTTn broth by generating tetrathionate ex situ through an external reaction between iodine and thiosulphate followed by lyophilization. Quality control procedures were performed to compare the modified and original media, testing pure productivity (enrichment with 50-120 CFU of Salmonella Thyphimurim ATCC 14028 and Salmonella Enteritidis ATCC 13076 and plating on Xylose Lysine Deoxycholate agar, XLD), mixed productivity (50-120 CFU of Salmonella strains and Pseudomonas aeruginosa and Escherichia coli at ≥10⁴ CFU and XLD plating) and selectivity (≥10⁴ CFU of P. aeruginosa and Enterococcus faecalis and plating on Tryptone Casein Soy agar, TSA). The modified MKTTn medium (S/L) performed comparably with the original medium in terms of growth of both Salmonella strains (>300 colonies in XLD), alone or with P. aeruginosa and E. coli. Quantitative assays showed no statistically significant differences in the number of colonies grown on XLD after 10^-5 dilution (p = 0.7015 with S. Thyphimurim ATCC 14028 and p = 0.2387 with S. enteritidis ATCC 13076; ANOVA test). MKTTn medium (S/L) was also selective against E. coli (≤100 colonies) and E. faecalis (<10 colonies). These results suggest that adding tetrathionate as a lyophilisate (S/L) is a feasible alternative to the use of Lugol's solution for the preparation of MKTTn enrichment broth and does not affect the properties of the medium.

Cereal cyst nematode resistance conferred by the Cre7 gene from Aegilops triuncialis and its relationship with Cre genes from Australian wheat cultivars

Cereal cyst nematode (CCN; Heterodera avenae Woll.) is a root pathogen of cereal crops that can cause severe yield losses in wheat (Triticum aestivum). Differential host-nematode interactions occur in wheat cultivars carrying different CCN resistance (Cre) genes. The objective of this study was to determine the CCN resistance conferred by the Cre7 gene from Aegilops triuncialis in a 42-chromosome introgression line and to assess the effects of the Cre1, Cre3, Cre4, and Cre8 genes present in Australian wheat lines on Spanish pathotype Ha71. Inhibition of nematode reproduction was rank-ordered as Cre1 >or = Cre4 > or = Cre7 >> Cre8 > Cre3. Lines carrying Cre1, Cre4, or Cre7 exhibited a significantly higher level of resistance than those carrying Cre8 or Cre3. Allelism tests indicated that Cre7 segregated independently of Cre1 on chromosome 2BL and Cre4 on chromosome 2DL, and these genes could consistently be combined in the same genotype, inducing a more durable resistance. Tests to determine the chromosomal location of Cre7 using addition lines were inconclusive.

Modulation of Antigenic Phenotype by IL-1β, IFNγ and TGFβ1 on Cultured Human Decidual Stromal Cells

Decidual stromal cells (DSC) constitute the most abundant population in normal human decidua together with leukocytes. Both populations may be involved in the immunological role of the decidua by favoring gestational functions, participating in physiological mechanisms to eliminate the fetus, or providing local defense against infection. Using flow cytometry, we investigated whether different cytokines modulate the expression on cultured DSC of antigen-presenting molecules. The treatment with IFNγ or IL-1β enhanced the expression of CD54. The percentage of expression of HLA-DR was enhanced by IL-1β treatment but was not modified by IFNγ. The expression of CD80 and CD86 was enhanced by IFNγ treatment but was not modified by IL-1β; the expression of CD86 and HLA-DR was reduced by TGFβ1 treatment. The response of DSC and dendritic cells to these cytokines appears to be similar, suggesting a phenotypic and functional relationship between these cell types.

Biochemical and genetic studies of two Heterodera avenae resistance genes transferred from Aegilops ventricosa to wheat

Two Heterodera avenae resistance genes, Cre2 from Aegilops ventricosa AP-1 and Cre5 from Ae. ventricosa #10, were shown to confer a high level of resistance to the Spanish pathotype Ha71. No susceptible plants were found in the F(2) progeny from the cross between the two accessions of Ae. ventricosa, suggesting that their respective resistance factors were allelic. However, genes Cre2 and Cre5 apparently were transferred to a different chromosomal location in the wheat line H-93-8 and in the 6M(v)(6D) substitution, respectively, as proved by F(2) segregation of their cross progeny. The induction of several defence responses during early infection by the same H. avenae pathotype in resistant lines carrying Cre2 or Cre5 genes was studied. Isoelectrofocusing (IEF) isozyme analysis revealed that peroxidase, esterase and superoxide dismutase activity increased after nematode infection, in roots of resistant lines in comparison with their susceptible parents. Differential induced isoforms were also identified when IEF patterns of resistant lines were compared. A DNA marker, absent in Cre5-carrying genotypes, was found to be linked, thought not very tightly, to the Cre2 gene in the H-93-8 line. The differences observed between the Cre2 and Cre5 genes with respect to their chromosomal location in wheat introgression lines, de-toxificant enzyme induction and behaviour against different pathotypes, suggest they are different H. avenae resistance sources for wheat breeding.

A new Hessian fly resistance gene (H30) transferred from the wild grass Aegilops triuncialis to hexaploid wheat

A new Hessian fly (Mayetiola destructor Say) resistance gene from Aegilops triuncialis and its transfer to hexaploid wheat via interspecific hybridisation is described. The transfer line TR-3531 (42 chromosomes), derived from the cross [(Triticum turgidum x Ae. triuncialis) x Triticum aestivum] and carrying the Heterodera avenae resistance gene Cre7, showed a high level of resistance to the M. destructor biotype prevailing in the SW of Spain. A single dominant gene (H30) seems to determine the Hessian fly resistance in this introgression line, and its linkage with an isozyme marker (Acph-U1) has also been studied. It has been demonstrated that the resistance gene H30 in the TR-3531 line is non-allelic with respect to the genes H3, H6, H9, H11, H12, H13, H18 and H21, present in wheat cultivars from the Uniform Hessian Fly Nursery (UHFN), as well as to H27, carried by the introgression line H-93-33. Advanced lines with the H30 gene were obtained by backcrossing the transfer line and different commercial wheats as recurrent parents. Several of them showed a high yield in tests carried out in the infested field. Electronic Supplementary Material is available if you access this article at http://dx.doi.org/10.1007/s00122-002-1182-z. On that page (frame on the left side), a link takes you directly to the supplementary material.

Secondary metabolites from a Streptomyces strain isolated from Livingston Island, Antarctica

The producing strain Streptomyces sp. 1010 was isolated from a shallow sea sediment from the region of Livingston Island, Antarctica. From the culture broth of this strain naturally active secondary metabolites were isolated identical to phthalic acid diethyl ester (C12H14O4, MW. 222); 1, 3-bis (3-phenoxyphenoxy)benzene (C30H22O4, MW.446); hexanedioic acid dioctyl ester (C22H42O4, MW.370) and the new substance 2-amino- 9, 13 -dimethyl heptadecanoic acid (C19H39NO2, MW.313). These compounds represent diverse classes of chemical structures and provide evidence for the untapped biosynthetic potential of marine bacteria from Antarctica.

CD10 expression in cultured human osteoblast-like cells

Morphological features, bone nodule formation and alkaline phosphatase activity are currently used to identify osteoblasts. CD10 (cALLa antigen) is a glycoprotein with endopeptidase activity and it is present on the surface of many cell types. We have studied the expression of CD10 in osteoblast-like cells by immunocytochemistry and flow cytometry in order to identify other markers of the osteoblast lineage. We isolated osteoblast-like cells from specimens obtained in the course of oral surgery. Expression of the cALLa antigen (CD10) may also be an indicator of the osteoblast phenotype.

Expression of molecules involved in antigen presentation and T cell activation (HLA-DR, CD80, CD86, CD44 and CD54) by cultured human osteoblasts

BACKGROUND

Osteoblasts express the CD44 antigen and HLA class II antigens, molecules which, together with other costimulatory molecules such as CD80, CD86, and CD54, are involved in antigen presentation and T cell activation. The aim of this study was to investigate the expression of these molecules in human osteoblasts.

METHODS

Human osteoblastic cells obtained from samples of normal bone obtained during mandibular osteotomy were isolated, maintained in culture, and characterized. The identity of the cells was confirmed by their alkaline phosphatase activity and their capacity to produce osteocalcin. Flow cytometry was used to examine the expression HLA-DR, CD80, CD86, CD44, and CD54 molecules involved in immune activities.

RESULTS

We detected the expression of CD10, CD44, and HLA-DR antigens, molecules involved in antigen presentation in cultured osteoblastic cells. Although the cells were negative for CD45, the leukocyte common antigen and CD14 (an antigen detected on macrophages), they expressed CD54, CD80, and CD86 antigens, which are also involved in the mechanisms of antigen presentation to and activation of T cells.

CONCLUSIONS

Our results suggest that osteoblastic cells or a subpopulation of these cells may have immune functions in bone. Further studies in which immune functions are assessed will be needed to test this hypothesis.

Atmospheric correction algorithm for hyperspectral remote sensing of ocean color from space

Existing atmospheric correction algorithms for multichannel remote sensing of ocean color from space were designed for retrieving water-leaving radiances in the visible over clear deep ocean areas and cannot easily be modified for retrievals over turbid coastal waters. We have developed an atmospheric correction algorithm for hyperspectral remote sensing of ocean color with the near-future Coastal Ocean Imaging Spectrometer. The algorithm uses look-up tables generated with a vector radiative transfer code. Aerosol parameters are determined by a spectrum-matching technique that uses channels located at wavelengths longer than 0.86 mum. The aerosol information is extracted back to the visible based on aerosol models during the retrieval of water-leaving radiances. Quite reasonable water-leaving radiances have been obtained when our algorithm was applied to process hyperspectral imaging data acquired with an airborne imaging spectrometer.

Effect of Halococcus morrhuae and Halobacterium saccharovorum on the activation of human peripheral blood lymphocytes

The immunomodulator properties of two species of halophilic Archaebacteria, Halobacterium saccharovorum and Halococcus rnorrhuae, were analysed by the study of lymphocyte activation. Two methods were used to detect activation in lymphocytes, namely incorporation of the radioactive nucleotide [3H]-thymidine, and CD25 expression. H. morrhuae had a stimulatory effect on human lymphocytes, but this action was observed only with the [3H]-thymidine uptake method, whereas H. saccharovorum produced no immunomodulator effect.

Human decidual stromal cells express alpha-smooth muscle actin and show ultrastructural similarities with myofibroblasts

Previous reports in human and mouse material demonstrated that decidual stromal cells expressed antigens associated with haematopoietic cells, exerted immune functions, and originated from bone marrow. These findings suggested that these cells belonged to the haematopoietic lineage. We purified and expanded in culture precursors of human decidual stromal cells, and found in electron microscopic images that the ultrastructure of these cells was similar to that of myofibroblasts, which are of mesenchymal origin. The relationship between these two types of cell was confirmed by the detection (by flow cytometry) in the decidual precursors of alpha-smooth muscle actin, a contractile microfilament expressed solely by smooth muscle cells, myofibroblasts and related cells. This filament was also detected in decidual stromal cells decidualized in vitro by the effect of progesterone. We also found vimentin in decidual precursors and decidualized cells. This intermediate filament has been previously reported to be expressed by all decidual stromal cells and also by myofibroblasts. Desmin, another intermediate filament expressed by myofibroblasts, was not detected in the decidual precursors; however, this filament was observed in decidualized cells. The expression of alpha-smooth muscle actin by decidual stromal cells was also found by immunostaining in cryostat sections of early decidua. Our results suggest that decidual stromal cells are related to myofibroblasts.

Polyphasic taxonomy of a novel yeast isolated from antarctic environment; description of Cryptococcus victoriae sp. nov

In 1992 some samples of mosses, lichens and soils were collected from Botany Bay, Southern Victoria Land (77 degrees 01' S 162 degrees 32' E) and, as a result of a routine screening programme some yeasts were isolated. One of them, designated as strain G5, showed marked differences when compared to other antarctic yeasts. According to morphological and physiological characteristics, we were able to identify the strain G5 as a yeast belonging to the genus Cryptococcus. Some characteristics of this genus are the growth response to myo-inositol, celobiose, raffinose and D-glucuronate, no-fermentation, the absence of mycelium and pseudomycelium, asexual reproduction, Diazolium blue B test (DBB) and urea hydrolisis positive and the growth without vitamines. This strain (G5) formed cream colonies of slimy appearance with cells of 3 x 2 microns in size, that grew between 4 degrees C and 20 degrees C. The G + C content of strain G5 was 50.3 mol%. The molecular characterization by whole-cell proteins and RFLP analysis of the 5.8S rRNA gene and the two ribosomal internal transcribed spacers (5.85-ITS region), revealed that this strain was different from other antarctic species of this genus. The phylogenetic tree deduced from the 5.8S rRNA gene sequence showed the strain G5 as a member of the genus Cryptococcus, clearly separated from other basidiomycetous yeasts. On the basis of the physiological, genotypical and phylogenetical data, the new isolate G5 was described as Cryptococcus victoriae, sp. nov., with the type strain G5 (= CECT 11114).

Cultured human decidual stromal cells express B7-1 (CD80) and B7-2 (CD86) and stimulate allogeneic T cells

The origin and function of decidual stromal cells (DSC), the main cellular component of the decidua, are uncertain. Although the general consensus is that they are fibroblastic cells involved in fetal trophoblast nutrition, several authors have demonstrated that these cells can carry out immunological functions and that at least a subpopulation of them may be of hematopoietic origin. Human DSC precursors or predecidual cells (preDSC) purified by expansion in culture express a surface phenotype recalling that of dendritic cells. In the present study, we show by flow cytometry that these cells also express B7-1 (CD80) and B7-2 (CD86), two antigens involved in the costimulation of T cells by antigen-presenting cells. Cultured DSC were also able to stimulate allogenic T cells in vitro. Using an immunohistochemical technique, we found that in cryostatic sections of early human decidua, CD80 and CD86 were expressed mainly by DSC located around the decidual vessels, a location compatible with preDSC rather than fully differentiated DSC. Our results suggest that preDSC are involved in antigen presentation.

Phagocytosis by fresh and cultured human decidual stromal cells: opposite effects of interleukin-1 alpha and progesterone

Flow cytometry and transmission electron microscopy have been employed to show that a proportion of fresh and cultured human decidual stromal cells phagocytose latex particles. Phagocytosis of Escherichia coli by cultured decidual stromal cells was, however, very low. Stimulation of cultured decidual stromal cells with interleukin-1 alpha enhanced phagocytosis of both latex particles and E. coli. In contrast, when decidual stromal cells were cultured with progesterone under decidualizing conditions, phagocytic activity was reduced. These results suggest the existence of an immune-endocrine circuit involving decidual stromal cells.

Immune phenotype and cytotoxic activity of lymphocytes from human term decidua against trophoblast

Flow cytometric data were used to compare the phenotype of term decidual lymphocytes and peripheral blood lymphocytes. Unlike peripheral blood lymphocytes, a significant percentage of CD3+, CD4+, CD8+ and CD16+ term decidual lymphocyte populations expressed the CD69 activation marker. The relative proportions of CD38 in CD3+, CD4+ and CD8+ populations were more than twice as large in term decidual lymphocytes as in peripheral blood lymphocytes. As reported for early decidual lymphocytes, the expression of CD38 and CD69 by term decidual lymphocytes suggests that these cells are also regionally activated. However, term decidual lymphocytes showed no spontaneous cytotoxicity against normal trophoblast or its tumoral counterpart, JEG cells. After stimulation with interleukin-2, these lymphocytes became cytotoxic, as did peripheral blood lymphocytes. The relevance of this latter result to the immune control of the physiological and pathological invasion of the decidua by the trophoblast is discussed.

Cultured human decidual stromal cells express antigens associated with hematopoietic cells

Although decidual stromal cells (DSC) have classically been considered to play a nutritional role during pregnancy, several reports have demonstrated that they can also exert different immune activities. Furthermore, some authors have occasionally found antigens on DSC normally expressed by immune cells. In this study, we isolated and cultured 12 human DSC lines and studied them with immunocytochemistry and flow cytometry using monoclonal antibodies against antigens associated with hematopoietic cells. Decidual stromal cells exhibited a constant phenotype: they were CALLA (CD10)-positive and DR-positive, although the expression of CD45, the leukocyte common antigen, was found to be very weak or negative. We also detected myelomonocytic antigens CD11b (CR3), CD13, CD16 (Fc gamma RIII) and CD36, although DSC lacked CD14, CD15 and CD33. B cell antigens CD20, CD21 (CR3), CD23 (Fc epsilon RII) and CD24 were expressed. DRC-1, an antigen detected on follicular dendritic cells (FDC), was also observed on DSC. When these cells were cultured in the presence of progesterone, they expressed desmin and prolactin (PRL), findings that confirmed their identity as DSC. The phenotype described, together with the immune activities reportedly carried out by DSC, suggest that DSC may play a role in the maternal-fetal immune relationship.

Constitutive secretion of interleukin-6 by human decidual stromal cells in culture. Regulatory effect of progesterone

PROBLEM

Although several studies have demonstrated that decidual stromal cells (DSC) can secrete cytokines in culture, none of these studies documented the purity of the cultures. Since other cells of the decidua, such as macrophages and epithelial cells, also produce cytokines, it is important to ensure purity of the culture so that cytokine production can be ascribed with confidence to DSC.

METHOD

DSC from early human pregnancies were highly purified and maintained in culture. Basal secretion by these cells of IL-6, together with other cytokines considered critical for pregnancy (IL-1 beta, TNF alpha and IFN gamma), was measured with immunological techniques.

RESULTS

We found that DSC in culture produce insignificant quantities of IL-1 beta, TNF alpha and IFN gamma, but appreciable amounts of IL-6. The production of this later cytokine was, however, inhibited by the effect of progesterone.

CONCLUSIONS

Basal production of IL-6 by DSC may be involved in physiological functions at the maternal-fetal interface. Nevertheless, the secretion of this cytokine is regulated by progesterone, probably to prevent excessive production of this cytokine from triggering an inflammatory response that might compromise pregnancy.

Evaluation of phagocytic capacity with a modified flow cytometry technique

Phagocytic capacity was determined in human polymorphonuclear leukocytes with a modified flow cytometry technique. The advantages of this method include simplified sample preparation--the assay is done using whole blood--and quantification of phagocytosis with a phagocytic index obtained by comparison with controls, which obviates errors arising from non-specific adherence.

Expression of adhesion molecules by endothelial cells of early human decidua

The expression of adhesion molecules by endothelial cells (EC) of early human decidua was studied with monoclonal antibodies and the immunoperoxidase technique. Although E-selectin, INCAM-110 and VCAM-1 were poorly detected on decidual EC, ICAM-1, P-selectin and DR antigens were highly expressed by these cells, some of which showed high endothelial venule-like morphology. Our results suggest that decidual EC are activated, and are probably involved in the active recruitment of leucocytes.

Application of flow cytometry to the study of antiphagocytic properties of Klebsiella pneumoniae capsular polysaccharide

We used flow cytometry to compare the effects of whole cells and capsular polysaccharides of Klebsiella pneumoniae on the phagocytic ability ot polymorphonuclear leukocytes. Our results showed a light decrease in phagocytic activity in the presence of capsular polysaccharides, but a marked decrease with whole cells. Our findings suggest that the resistance to phagocytosis in these microorganisms is not due exclusively to their capsule, as claimed by other authors.

Comparison of the proportions of leukocytes in early and term human decidua

The percentages of cells expressing immune markers were determined with immunohistochemistry and flow cytometry in early and term human decidua. Although we found no variation in the proportion of cells of bone marrow origin (CD45+), the percentages of T cells and CD16+ lymphocytes were significantly higher in term decidua. On the contrary, CD56+ lymphocytes, the most abundant leukocyte type in early decidua, decreased at term. These variations may reflex the immunological adaptations of decidua during pregnancy.

Expression of class II HLA molecules by endothelial cells of human decidua

Many authors have documented a high level of expression of class II HLA molecules by decidua. Although macrophages appear to be responsible for this, we show in this article that endothelial cells (EC) of the venules and capillaries of human decidua also strongly express class II molecules, whereas EC of chorionic villi do not. We discuss this finding in the context of the maternal-fetal immune interaction.

Evaluation of lymphocyte activation by flow cytometric determination of interleukin-2 (CD25) receptor

Lymphocyte response to mitogens is a habitually-used test in the evaluation of the immune system. The usual method with [3H]thymidine yields results which are difficult to interpret. In our search for an alternative, we examined the feasibility of determining T lymphocyte activation by measuring interleukin-2 receptor (CD25) expression with flow cytometry. We found a good correlation between CD25 molecule expression and the dose of phytohemagglutinin, however, there was no correlation between disintegrations per minute produced by [3H]thymidine uptake and the percentage of CD25 expressed by cells.

[Porphyrin excretion in normal (author's transl)]

Porphyrin excretion in normal subjects was studied by solvent extraction procedures and by thin-layer chromatography of their methyl-esters. The mean value of the urinary coproporphyrin fraction was significantly higher in males than in females. Taking age also into account this difference was not significant in subjects under 20 years of age. Within the same sex, age did not have any influence on this coproporphyrin fraction. Neither of these two factors, i.e. sex and age modified the mean values of uroporphyrin fraction. Males and females showed similar amounts of fecal copro and protoporphyrin fractions. The thin-layer chromatographic urinary pattern revealed a minor porcentual value of octo-carboxylic-porphyrin in males, due mainly to a lower amount of porphyrin in the 20-40 year, period, when males also showed a decreased value of heptacarboxylic-porphyrin. Neither sex nor age modified the fecal chromatographic porphyrin pattern. Di-carboxylic porphyrins were always predominant, but theri appraisal was very frequently interfered by the presence in feces of fluorescent substances with a Rf similar to tri-carboxylic-porphyrin but with a pheophytinlike spectra.