Aspergillus parasiticus communities associated with sugarcane in the Rio Grande Valley of Texas: implications of global transport and host association within Aspergillus section Flavi.

In the Rio Grande Valley of Texas (RGV), values of maize and cottonseed crops are significantly reduced by aflatoxin contamination. Aflatoxin contamination of susceptible crops is the product of communities of aflatoxin producers and the average aflatoxin-producing potentials of these communities influence aflatoxin contamination risk. Cropping pattern influences community composition and, thereby, the epidemiology of aflatoxin contamination. In 2004, Aspergillus parasiticus was isolated from two fields previously cropped to sugarcane but not from 23 fields without recent history of sugarcane cultivation. In 2004 and 2005, A. parasiticus composed 18 to 36% of Aspergillus section Flavi resident in agricultural soils within sugarcane-producing counties. A. parasiticus was not detected in counties that do not produce sugarcane. Aspergillus section Flavi soil communities within sugarcane-producing counties differed significantly dependent on sugarcane cropping history. Fields cropped to sugarcane within the previous 5 years had greater quantities of A. parasiticus (mean = 16 CFU/g) than fields not cropped to sugarcane (mean = 0.1 CFU/g). The percentage of Aspergillus section Flavi composed of A. parasiticus increased to 65% under continuous sugarcane cultivation and remained high the first season of rotation out of sugarcane. Section Flavi communities in fields rotated to non-sugarcane crops for 3 to 5 years were composed of <5% A. parasiticus, and fields with no sugarcane history averaged only 0.2% A. parasiticus. The section Flavi community infecting RGV sugarcane stems ranged from 95% A. parasiticus in billets prepared for commercial planting to 52% A. parasiticus in hand-collected sugarcane stems. Vegetative compatibility assays and multilocus phylogenies verified that aflatoxin contamination of raw sugar was previously attributed to similar A. parasiticus in Japan. Association of closely related A. parasiticus genotypes with sugarcane produced in Japan and RGV, frequent infection of billets by these genotypes, and the ephemeral nature of A. parasiticus in RGV soils suggests global transport with sugarcane planting material.

Blocking of Pseudomonas aeruginosa and Chromobacterium violaceum lectins by diverse mammalian milks.

Pseudomonas aeruginosa and Chromobacterium violaceum morbid and mortal infections are initiated by bacterial adherence to host-cell receptors via their adhesins, including lectins (which also contribute to bacterial biofilm formation). Pseudomonas aeruginosa produces a galactophilic lectin, PA-IL (LecA), and a fucophilic (Lewis-specific) lectin, PA-IIL (LecB), and C. violaceum produces a fucophilic (H-specific) lectin, CV-IIL. The antibiotic resistance of these bacteria prompted the search for glycosylated receptor-mimicking compounds that would function as glycodecoys for blocking lectin attachment to human cell receptors. Lectins PA-IL and PA-IIL have been shown to be useful for such glycodecoy probing, clearly differentiating between human and cow milks. This article describes their usage, together with CV-IIL and the plant lectin concanavalin A, for comparing the anti-lectin-dependent adhesion potential of diverse mammalian milks. The results show that the diverse milks differ in blocking (hemagglutination inhibition) and differential binding (Western blots) of these lectins. Human milk most strongly inhibited the 3 bacterial lectins (with PA-IIL superiority), followed by alpaca, giraffe, and monkey milks, whereas cow milk was a weak inhibitor. Lectin PA-IL was inhibited strongly by human, followed by alpaca, mare, giraffe, buffalo, and monkey milks, weakly by camel milk, and not at all by rabbit milk. Lectins PA-IIL and CV-IIL were also most sensitive to human milk, followed by alpaca, monkey, giraffe, rabbit, and camel milks but negligibly sensitive to buffalo and mare milks. Plant lectin concanavalinA, which was used as the reference, differed from them in that it was much less sensitive to human milk and was equally as sensitive to cow milk. These results have provided important information on the anti-lectin-dependent adhesion potential of the diverse milks examined. They showed that human followed by alpaca, giraffe, and Rhesus monkey milks efficiently blocked the binding of both the galactophilic and fucophilic (>mannophilic) pathogen lectins. The results also proved the advantage of isolated pathogenic bacterial lectins as superb probes for unveiling bacterial adhesion-blocking glycodecoys. The chosen milks or their polymeric glycans might be implicated in blocking lectin-dependent adhesion of antibiotic-resistant pathogens leading to skin, eye, ear, and gastrointestinal infections.

Interactions of the fucose-specific Pseudomonas aeruginosa lectin, PA-IIL, with mammalian glycoconjugates bearing polyvalent Lewis(a) and ABH blood group glycotopes.

Pseudomonas aeruginosa Fuc > Man specific lectin, PA-IIL, is an important microbial agglutinin that might be involved in P. aeruginosa infections in humans. In order to delineate the structures of these lectin receptors, its detailed carbohydrate recognition profile was studied both by microtiter plate biotin/avidin-mediated enzyme-lectin-glycan binding assay (ELLSA) and by inhibition of the lectin-glycan interaction. Among 40 glycans tested for binding, PA-IIL reacted well with all human blood group ABH and Le(a)/Le(b) active glycoproteins (gps), but weakly or not at all with their precursor gps and N-linked gps. Among the sugar ligands tested by the inhibition assay, the Le(a) pentasaccharide lacto-N-fucopentaose II (LNFP II, Galbeta1-3[Fucalpha1-4]GlcNAcbeta1-3Galbeta1-4Glc) was the most potent one, being 10 and 38 times more active than the Le(x) pentasaccharide (LNFP III, Galbeta1-4 [Fucalpha1-3]GlcNAcbeta1-3Galbeta1-4Glc) and sialyl Le(x) (Neu5Acalpha2-3Galbeta1-4[Fucalpha1-3] GlcNAc), respectively. It was 120 times more active than Man, while Gal and GalNAc were inactive. The decreasing order of PA-IIL affinity for the oligosaccharides tested was: Le(a) pentaose > or = sialyl Le(a) tetraose > methyl alphaFuc > Fuc and Fucalpha1-2Gal (H disaccharide)>2'-fucosyllactose (H trisaccharide), Le(x) pentaose, Le(b) hexaose (LNDFH I) and gluco-analogue of Le(y) tetraose (LDFT)>H type I determinant (LNFP I)>Le(x) trisaccharide (Galbeta1-4[Fucalpha1-3]GlcNAc) > sialyl Le(x) trisaccharide >> Man >>> Gal, GalNAc, and Glc (inactive). The results presented here, in accordance with the crystal 3D structural data, imply that the combining site of PA-IIL is a small cavity-type best fitting Fucalpha1- with a specific shallow groove subsite for the remainder part of the Le(a) saccharides, and that polyvalent glycotopes enhance the reactivity. The Fuc > Man Ralstonia solanacearum lectin RSL, which resembles PA-IIL in sugar specificity, differs from it in it's better fit to the B and A followed by H oligosaccharides vs. Fuc, whereas, the second R. solanacearum lectin RS-IIL (the structural homologue of PA-IIL) binds Man > Fuc. These results provide a valuable information on PA-IIL interactions with mammalian glycoforms and the possible spectrum of attachment sites for the homing of this aggressive bacterium onto the target molecules. Such information might be useful for the antiadhesive therapy of P. aeruginosa infections.

H-deficient Bombay and para-Bombay red blood cells are most strongly agglutinated by the galactophilic lectins of Aplysia and Pseudomonas aeruginosa that detect I and P1 antigens.

The galactophilic lectins Aplysia gonad lectin (AGL) and Pseudomonas aeruginosa lectin (PA-IL), which detect human I and P1 RBC antigens, were examined for hemagglutination of H+ (group O and B) and H-deficient (Bombay and para-Bombay phenotype) RBCs. The results were compared with those obtained using two other galactophilic lectins, Maclura pomifera lectin (MPL) and Arachis hypogaea (peanut) agglutinin (PNA), which share T-antigen affinity, and two fucose-binding H-specific lectins, Ulex europaeus (UEA-I) and Pseudomonas aeruginosa lectin (PA-IIL), as well as with those achieved with anti-I serum. The results revealed that, in contrast to UEA-I and PA-IIL, which preferentially agglutinated H+ RBCs, and to MPL and PNA, which similarly agglutinated all examined RBCs, AGL, PA-IL, and the anti-I serum agglutinated the H-deficient RBCs more strongly than did the H+ RBCs. These findings could be attributed to increased levels of I and P1 antigens on those RBCs resulting from the use of the free common H-type 2 precursor for their synthesis. Since both PA-IL and PA-IIL are regarded as potential pathogen adhesins, it would be interesting to statistically compare the sensitivities of individuals of H+ and H-deficient RBC populations to P. aeruginosa infections.

Pseudomonas aeruginosa lectin PA-IIL as a powerful probe for human and bovine milk analysis.

Milk composition exhibits species-specific differences depending on genetic, evolutionary, and environmental factors. In addition, commercial milk preparations are also changed by industrial manipulations, including severe heat processing. Cow milk, used as human food, provides important nutrients but lacks some essential components that are present in raw human milk. The present study, which was aimed at comparing infant breastfeeding to cow-based formula nourishment, shows major differences between the human and the commercial cow milk glycans detectable by the lectins PA-IL (galactose-binding) and PA-IIL (fucose and mannose-binding) isolated from the cells of human pathogen Pseudomonas aeruginosa. More than 40 human milk samples, several cow milks, and bovine milk-based infant formulas, were examined using these two lectins. For purposes of comparison, the plant lectins Concanavalin A (Con A), which binds mannose, and Ulex europaeus 1st lectin (UEA-I), which binds fucose, were also used. The most prominent difference was revealed using PA-IIL, which displayed a unique high sensitivity to the human milk fucosylated compounds. PA-IL and UEA-I also exhibited preferential sensitivity to the human milk but considerably lower than that of PA-IIL. Con A was inhibited by human and the other milk preparations examined to the same extent. These findings indicate the superb applicability of PA-IIL for rapid and reliable comparative investigation of milk glycans from human and cow, indicating which glycans could be added to infant formulas in order to enrich them, as well as for verification and quality control of otherwise improved bovine milk-based infant formulas.

Interaction of Pseudomonas aeruginosa galactophilic lectin PA-IL with pigeon egg white glycoproteins.

Pseudomonas aeruginosa produces a galactophilic lectin, PA-IL, that resembles P-fimbrial adhesins of uropathogenic Escherichia coli strains in binding to human P blood group antigens. We examined, in the present study, its interaction with pigeon egg white glycoproteins carrying N-glycans with terminal Galalpha1-4Gal which inhibit the adhesion of P-fimbriae. For comparison, the lectin concanavalin A (Con A) and additional avian egg whites (of hen and quail) were also examined. The results obtained in both hemagglutination inhibition and Western blot analyses showed that PA-IL, unlike Con A, preferentially reacted with the pigeon egg white glycoproteins. These results, which confirmed PA-IL similarity in sugar specificity to E. coli P-fimbriae, demonstrated the advantage of this purified lectin for representing P-type and additional galactophilic microbial adhesins unavailable in purified stable form, in Western blot analyses.

Usage of Aplysia lectin interactions with T antigen and poly-N-acetyllactosamine for screening of E. coli strains which bear glycoforms cross-reacting with cancer-associated antigens.

Aplysia gonad lectin (AGL), which strongly agglutinates cancer cells, was found, in the present study, to bind to erythrocyte T antigen, in addition to its affinity to Ii system antigens. These antigens were reported to be overexpressed and to contribute to tumor progression and invasion. In healthy human sera, there are antibodies against them, stimulated by the normal intestinal microflora, which bear similar glycoforms. Since the levels of these antibodies were reported to be lower in most cancer patients' sera, we have examined the applicability of AGL to isolation of enteric commensal Escherichia coli strains which bear glycoforms cross-reacting with the cancer-associated antigens. Among 30 E. coli isolates examined, two were agglutinated by AGL. One of them was also agglutinated by certain related galactophilic lectins, which bind to the T and Tn antigens. The agglutination of the two bacteria by healthy human sera, as a group, was stronger than that displayed by the cancer patients' sera. These results indicate that AGL might be useful for identification of the desired bacteria, which could potentially serve for cancer diagnosis and therapy.

Interactions of Pseudomonas aeruginosa PA-IIL lectin with quail egg white glycoproteins.

Pseudomonas aeruginosa produces several lectins, including the galactophilic PA-IL and the fucose- and mannose-binding PA-IIL. The great advantage of these two lectins is their stability in purified preparations. Following observations that pigeon egg white blocks Escherichia coli P-fimbriae and PA-IL, we examined the interactions of diverse avian egg white components with PA-IIL. This lectin may represent both mannose- and fucose-specific microbial adhesins. For comparison, Con A (which also binds mannose) and Ulex europaeus lectin (UEA-I, which binds fucose) were analyzed in parallel. The lectin interactions with chicken, quail, and pigeon egg whites and several purified chicken egg white glycoproteins were examined by a hemagglutination inhibition test and Western blotting. Both analyses showed that like Con A and unlike UEA-I, which was not sensitive to any of these three egg whites, PA-IIL most strongly reacted with the quail egg white. However, in contrast with Con A, its interactions with the chicken egg white components, excluding avidin, were very poor. The results of this study might indicate the possibility that some of the egg white components that interacted with the above two mannose-binding lectins (exhibiting individual heterogeneity) might be associated with the innate immunity against mannose-specific microbial or viral adhesion during the fowl embryonic period.

Binding properties and applications of Aplysia gonad lectin.

Adult Aplysia gonad contains high levels of a galactophilic lectin (MW around 65 kDa; composed of 2 subunits of apparent single species). It binds galactose and various alpha/beta-galactosides (but not N-acetylgalactosamine), in addition to an outstanding high affinity for galacturonic acid. This lectin is relatively resistant to heating up to 70 degrees C and to alkaline pH, but sensitive to proteolysis and low pH. It resembles galectins in binding to poly LacNAc (preferentially branched) complexes at low temperatures (0 degrees-4 degrees C) more avidly than at room temperature or at 37 degrees C, but differs from them in being Ca(2+)-dependent. It agglutinates papain/sialidase-treated erythrocytes more strongly than untreated cells and stimulates mitosis in peripheral human lymphocytes (inducing IL-2 formation). This lectin also enhances neurite outgrowth and increases their viability, while suppressing cell tumorigenicity. It is useful for histochemical/ cytochemical studies of galacturonic acid in plant tissues and fungi and for the study of cell surface composition of various prokaryotic (including halophilic Archaea) and eukaryotic cells and for their typing. It is useful as a reagent for I-antigen detection in adult human erythrocytes (anti-I), exhibiting strongest agglutination of O(h) Bombay-type erythrocytes and also exhibits sensitivity to the T antigen. It binds galactosylated molecules in human body fluids (shown by hemagglutination--inhibition tests), including saliva, seminal fluid and milk (detecting individual divergence) and in fowl egg albumens (exhibiting highest affinity for that of pigeon). Therefore, it might be valuable as a probe and fishhook for fishing compounds exhibiting anti-bacterial/neoplastic cell adhesion activities.

A guide to performing basic manifest refractometry.

Refractometry provides the ophthalmologist with the prescription that has the most plus power with the best vision. This eliminates the need for the patient accommodating to achieve clear vision at distance. Flowcharts, of the refractometry process, help the refractionist use standard procedures to accurately arrive at the correct baseline prescription for the patient's refractive state. By using the patient's history of subjective complaints, past refractive corrections, and present visual needs, the ophthalmologist then can prescribe the final prescription.

Ocular risks from sunlight exposure.

Relinquishing the desire to acquire a tan will be difficult for many people. To many individuals, a tan is a symbol of health, fashion and attractiveness. Even when informed about the risks of sunlight exposure, many people ignore the advice to change their behaviors and decrease their risks. Adoption of safe sunlight precautions depends on individual preference, age, work requirements, gender, and perception of personal risk. Many people selectively adhere to certain protective behaviors which do not conflict with social norms. Reinforcement of how sunlight can damage the eyes and skin needs to be continually provided so that public attitudes can adapt to all the necessary appropriate behaviors. Ophthalmic health care professionals have an important part in public education. They can customize their patient's personal protective requirements to match the type of risks uncovered in the clinical work up. The ocular and social history should include the patient's sunlight exposure risk profile and document pre-existing sunlight damage to the eyes and facial areas. All follow-up visits should reinforce sunlight exposure information and document compliance or non-compliance. Only in this way can the eye care delivery system support preventative measures to decrease ocular injuries from sunlight radiation.

The Pseudomonas aeruginosa lectins PA-IL and PA-IIL are controlled by quorum sensing and by RpoS.

In Pseudomonas aeruginosa, many exoproduct virulence determinants are regulated via a hierarchical quorum-sensing cascade involving the transcriptional regulators LasR and RhlR and their cognate activators, N-(3-oxododecanoyl)-L-homoserine lactone (3O-C12-HSL) and N-butanoyl-L-homoserine lactone (C4-HSL). In this paper, we demonstrate that the cytotoxic lectins PA-IL and PA-IIL are regulated via quorum sensing. Using immunoblot analysis, the production of both lectins was found to be directly dependent on the rhl locus while, in a lasR mutant, the onset of lectin synthesis was delayed but not abolished. The PA-IL structural gene, lecA, was cloned and sequenced. Transcript analysis indicated a monocistronic organization with a transcriptional start site 70 bp upstream of the lecA translational start codon. A lux box-type element together with RpoS (sigma(S)) consensus sequences was identified upstream of the putative promoter region. In Escherichia coli, expression of a lecA::lux reporter fusion was activated by RhlR/C4-HSL, but not by LasR/3O-C12-HSL, confirming direct regulation by RhlR/C4-HSL. Similarly, in P. aeruginosa PAO1, the expression of a chromosomal lecA::lux fusion was enhanced but not advanced by the addition of exogenous C4-HSL but not 3O-C12-HSL. Furthermore, mutation of rpoS abolished lectin synthesis in P. aeruginosa, demonstrating that both RpoS and RhlR/C4-HSL are required. Although the C4-HSL-dependent expression of the lecA::lux reporter in E. coli could be inhibited by the presence of 3O-C12-HSL, this did not occur in P. aeruginosa. This suggests that, in the homologous genetic background, 3O-C12-HSL does not function as a posttranslational regulator of the RhlR/C4-HSL-dependent activation of lecA expression.

Identification and characterization of pseudomonas aeruginosa PA-IIL lectin gene and protein compared to PA-IL.

Using the 33 N-terminal amino acids of the fucose/mannose binding lectin PA-IIL of Pseudomonas aeruginosa ATCC 33347 in a tblastn search of P. aeruginos PAOI genomic sequence in GenBank revealed a single open reading frame encoding a 114-amino acid protein (excluding initiator methionine) perfectly matching that amino acid sequence. Following its stop codon there is a GC-rich sequence having a perfect dyad symmetry promoting formation of a hairpin loop structure, potentially enabling rho-independent transcription termination. Upstream of the putative ribosomal binding site there are sequences resembling Vibrio fischeri luxIbox. consistent with autoinduction of this gene, The predicted PA-IIL molecular mass, confirmed by mass spectrometry, is 11,732 Da. Its pI is 3.88. The C-terminal domain is particularly hydrophobic, implying possible embedding in the cell membrane. PA-IIL is similar to P. aeruginosa PA-IL lectin in some amino acids and potential glycosylation sites but lacks cysteine, methionine and histidine. Despite their relations in functions and regulation.,their genes are widely separated (by about 867.5 kb).

Defining the carbohydrate specificities of aplysia gonad lectin exhibiting a peculiar D-galacturonic acid affinity.

Aplysia gonad lectin (AGL), which has been shown to stimulate mitogenesis in human peripheral lymphocytes, to suppress tumor cells, and to induce neurite outgrowth and improve cell viability in cultured Aplysia neurons, exhibits a peculiar galacturonic acid/galactose specificity. The carbohydrate binding site of this lectin was characterized by enzyme-linked lectino-sorbent assay and by inhibition of AGL-glycan interactions. Examination of the lectin binding with 34 glycans revealed that it reacted strongly with the following glycoforms: most human blood group precursor (equivalent) glycoproteins (gps), two Galalpha1-->4Gal-containing gps, and two d-galacturonic acid (GalUA)-containing polysaccharides (pectins from apple and citrus fruits), but poorly with most human blood group A and H active and sialylated gps. Among the GalUA and mammalian saccharides tested for inhibition of AGL-glycan binding, GalUA mono- to trisaccharides were the most potent ones. They were 8.5 x 10(4) times more active than Gal and about 1.5 x 10(3) more active than the human blood group P(k) active disaccharide (E, Galalpha1-->4Gal). This disaccharide was 6, 28, and 120 times more efficient than Galbeta1-->3GlcNAc(I), Galbeta1-->3GalNAc(T), and Galbeta1--> 4GlcNAc (II), respectively, and 35 and 80 times more active than melibiose (Galalpha1-->6Glc) and human blood group B active disaccharide (Galalpha1-->3Gal), respectively, showing that the decreasing order of the lectin affinity toward alpha-anomers of Gal is alpha1-->4 > alpha1-->6 > alpha1-->3. From the data provided, the carbohydrate specificity of AGL can be defined as GalUAalpha1-->4 trisaccharides to mono GalUA > branched or cluster forms of E, I, and II monomeric E, I, and II, whereas GalNAc is inactive.

Basic manual lensometry: a guide for measuring distance and near glasses.

Manual lensometry is a basic component of ophthalmic clinical care. You will find it necessary to check lens prescriptions manually when the written prescription does not match the results of an automated lensometer or when automated lensometry is not available.

Advanced manual lensometry: a self-learning guide for evaluating multifocal and specialty lenses, progressive lenses, prisms, and rigid contact lenses.

Advanced manual lensometry techniques are required when automated lensometry may not be appropriate for reading special lenses or rigid contact lenses. These advanced techniques are challenging but provide accurate diagnostic and lens verification data. One should never assume that the glasses the patient is wearing match what the doctor prescribed. The prescription should be checked at least once, even when there are no patient complaints. If possible, learn and practice these special procedures under the supervision of an optician or ophthalmic clinical trainer. This will help to verify that you are performing these special techniques correctly.

A comparison of the Aplysia lectin anti-I specificity with human anti-I and several other I-detecting lectins.

BACKGROUND: Lectins displaying blood group specificity are important for blood group typing and antigen recognition. Their use in blood banks is especially widespread in situations where there is a shortage of specific antisera. This report describes the efficiency of Aplysia gonad lectin as a reliable reagent for the detection of I antigen, which is common on adult human cells but reduced in fetal, newborn, and rare adult red cells. STUDY DESIGN AND METHODS: The selective hemagglutinating activity of the Aplysia lectin was compared with that of human anti-I and several I-reactive lectins, including two plant lectins, one galactophilic microbial lectin, and bovine spleen galectin. RESULTS: The comparison has revealed that Aplysia gonad lectin, like human anti-I, strongly agglutinates and adsorbs to adult I-positive red cells, differentiating between them and fetal or rare I-negative adult red cells (although with less of a difference). In contrast to the plant and microbial lectins examined, its I-affinity does not depend on the presence of ABH or P system antigens and it clearly detects higher I antigen expression in Oh red cells. The hemagglutinating activity of Aplysia lectin as that of all the I-detecting proteins is enhanced at 4 degrees C, but unlike the human anti-I Aplysia lectin-induced hemagglutination is stable at room temperature. CONCLUSIONS: The Aplysia lectin is a reliable anti-I reagent, which strongly agglutinates I-positive adult human red cells irrespective of their ABH or P system antigens. This lectin is usable at room temperature.

'Subinhibitory' erythromycin represses production of Pseudomonas aeruginosa lectins, autoinducer and virulence factors.

Pseudomonas aeruginosa infection is preceded by selective adhesion of the bacteria to the host target cells via diverse adhesins, including lectins. This step enables maximal damage to the target host cells by the bacterially secreted injurious toxins and enzymes. The production of both lectins and many of the virulence factors is positively controlled by transcription activators including signaling autoinducers (N-acyl-L-homoserine lactones). We show in this communication that erythromycin at subminimal growth inhibitory concentrations simultaneously suppresses the production of P. aeruginosa hemagglutinins (including lectins), protease, hemolysin and homoserine lactone autoinducers. The antibiotic-treated bacteria also show reduced virulence to mice, endorsing clinical observations that indicate the efficiency of low-dose erythromycin treatment of persistent drug-resistant P. aeruginosa infections.