Characterization of adhesion associated surface properties of uropathogenicEscherichia coli

Escherichia coli was isolated from the urine of patients with pyelonephritis, with urinary tract infections other than pyelonephritis and with asymptomatic bacteriuria. Surface properties of the strains were analyzed by the salting-out aggregation test (SAT), hydrophobic interaction chromatography (HIC), Congo red binding (Crb), agglutination of erythrocytes (MRHA) and latex particles covered by digalactoside (PF) and by adherence to tissue culture cells. In addition, a DNA probe for thepap gene was used. The DNA probe detected the highest proportion of strains withpap gene in the group of patients with pyelonephritis, lower in the urinary tract infections other than pyelonephritis and the lowest in the group with asymptomatic bacteriuria. Tests for P-fimbriae (PF, MRHA) showed a similar distribution. Hydrophobicity measured by SAT and by HIC did not show differences among the tested groups of strains. The results suggest that factors other than the P-fimbriae and hydrophobicity may contribute to the persistence ofE. coli in the urinary tract.     

Occurrence of genes for P and S fimbriae and hemolysin in urinaryEscherichia coli

Escherichia coli is the common causative agent of urinary tract infections. Sixty-one strains ofE. coli isolated from children with urinary tract infections were tested by colony hybridization for the presence of genes determining P and S fimbriae and hemolysin. Of these strains, 46 possess a gene for hemolysin, 44 for P fimbriae and 28 for S fimbriae. Only 30 strains formed lytic zones around the colonies on plates with sheep erythrocytes. The results indicated that simultaneous occurrence of genes in urinaryE. coli was highest for P fimbriae and hemolysin and lower for other combinations of the tested genes.     

Effects of irradiation on neuropeptide expression in rat salivary gland and spinal cord

Summary It is well-known that a large number of factors can influence the expression of neuropeptides in the nervous system. In the present study, the effects of unilateral and bilateral irradiation to the rat head and neck on the expression of neuropeptides in the innervation of the submandibular gland and in the ganglionic cells of the submandibular ganglion was examined ten days and six months after treatment. Antisera directed against enkephalin and bombesin and immunohistochemical methods were used. The effects of bilateral irradiation on the staining pattern of various neuropeptides in the cervical spinal cord were also studied. In the submandibular gland and in the submandibular ganglionic cells, there was a markedly increased neuropeptide expression ten days after bilateral treatment, as seen after staining with both antisera used, while no changes occurred after unilateral treatment. Six months after treatment, the pattern of neuropeptide expression in the submandibular gland/ganglion corresponded to that seen in controls. Irradiation did not lead to any changes in the staining pattern of neuropeptides in the spinal cord. The observations show that there is a great complexity in the susceptibility of nervous tissues to radiotherapy with respect to influences on the expression of neuropeptides.     

The influence of ammonia on the growth and photosynthesis of Ruppia drepanensis Tineo from Doñana National Park (SW Spain)

In a laboratory experiment, Ruppia drepanensis Tineo seedlings from a brackish marsh in Southern Spain were grown at 20 and 30 °C, at three different nitrogen levels. These levels were obtained by the addition of a slow release fertilizer (23% NH₄NO₃ by weight) to a sediment mixture of sand and clay (3:1). Several morphometric parameters were recorded during the first five weeks of the experiment, and photosynthesis and respiration were measured after 7 weeks of growth. Results showed a significant reduction of growth and development with increasing nitrogen and temperature levels. Dark respiration increased strongly at high nitrogen levels. At the same time, net photosynthesis at 250 and 500 µE m^-2 s^-1, Pm, Km and LCP were not affected by either factor. We attribute these phenomena to ammonia toxicity, since relatively high total ammonia (NH₃ + NH_f4 ^p+) levels were found in the interstitial water.     

Typology of shallow lakes of the Salado River basin (Argentina), based on phytoplankton communities

The phytoplankton communities of eleven shallow lakes from Buenos Aires Province, Argentina, were studied seasonally from 1987 to 1989. Several physical and chemical properties were measured in each lake (pH, temperature, dissolved oxygen, transparency, nutrients), in order to interpret the structural and dynamic traits of the phytoplankton community.Important differences between the lakes studied were put in evidence by means of multivariate techniques (Cluster Analysis and PCA). The shallow lakes densely populated by macrophytes hosted lowest phytoplanktonic densities, with average values ranging from 690 to 16500 algae ml^–1. High species diversities were observed in these lakes (4.0–4.8). Lakes less colonized by macrophytes had higher phytoplankton densities. In some of them important blooms of Cyanophyceae were recorded, with between 60 000 and 179 000 algae ml^–1, and concomitant low diversities.The results of this investigation support the hypothesis that the phytoplankton community is strongly influenced by the macrophytes, by direct competition and/or by competition from periphytic algae associated with higher plants.     

On the evolution of protamines in bony Fish: Alternatives to the “Retroviral horizontal transmission” hypothesis

Fish protamines are highly specialized molecules which are responsible for chromatin condensation during the last stages of spermatogenesis (spermiogenesis). However, not all fish contain protamines in their sperm nuclei; rather, there seems to be a random distribution of protamines within this group. The origin of this sporadic presence of protamines in the sperm and its significance have not yet been precisely determined. In this paper we have conducted an exhaustive survey of the literature available on the different types of nuclear protein composition of the sperm of teleost fish in order to try to correlate these data with what is presently known about the taxonomy of this group. The results of this analysis have allowed us to make the following observations. The divergence between protamines and histones has occurred several times during the evolution of the bony fish. However, the relative frequency of this divergence is almost negligible during the differentiation of genera and species (intrafamily variation) and is very small during the differentiation of families (interfamily variation). Nevertheless, the divergence is very noticeable among the different orders. It is therefore possible to conclude from all this that the sporadic distribution of protamines in bony fish is not a random event as initially believed. Furthermore, such a heterogeneous distribution of protamines cannot be easily accounted for by a mechanism of horizontal retroviral transmission through repeated and independent acquisition of a prot amine gene as has been recently proposed (Jankowski, Stater, Dixon (1986) J Mol Evol 23:1–10). Rather, it could possibly be explained by a repeated and independent loss of the expression of the protamine gene (or loss of the gene itself) which mainly occurred during the diversification of the orders of this group.Correspondence to: J. Ausio     

Crop/Weed gene flow:Cucurbita argyrosperma Huber andC. fraterna L. H. Bailey (Cucurbitaceae)

A mixed population of Cucurbita at Vado El Mow in northern Tamaulipas, Mexico showed an anomalous pattern of fruit bitterness. Some domesticated plants (C. argyrosperma andC. moschata) expressed cucurbitacin bitterness whereas some sympatric free-living plants produced non-bitter fruits. This reversal of typical cucurbitacin expression suggested gene flow between crop and weed at the site. Isozyme analysis provided little insight as to taxa involved in gene exchange, although progeny from a single free-living plant carried IDH allozymes that are associated with Mexican landraces ofC. pepo. Synthetic hybridization revealed that fertile F, hybrids are produced from crosses involvingC. fraterna as the pistillate parent andC. argyrosperma as the staminate parent. Interspecific crop/weed hybrids can produce viable progeny upon self-pollination or backcrossingto either parent, andF₂ families display normal allozyme segregation. Hybrid fertility, as indicated by pollen stainability, increases in progeny produced by backcrossingfrom theC. argyrosperma parent. Interspecific hybridfertility represents a potential for crop/weed gene flow that would be realized under natural conditions if pollen flow occurs betweenC. fraterna andC. argyrosperma in the fields of Tamaulipas. Oligolectic “squash bees” (Teponapis), efficientCucurbita pollen vectors, are present at the site. Thus, it is likely that natural interspecific crop/weed hybridization has occurred at Vado El Moro and this might at least partially explain the anomalous distribution of fruit bitterness among extant populations at the site.     

Traditional production system of the root of jalapa,Ipomoea purga (convolvulaceae), in Central Veracruz,Mexico

We describe the traditional production system of the root of jalapa, Ipomoea purga, in Xico, Veracruz, Mexico. The results are based on open interviews with the producers to gather information on the development of this crop in the area, and observation of the production system. The production cycle is carried out between July and February. We found that seed scarification is the key to the success of the productive system, obtaining a maximum of 95% seed germination in eight days. This activity, as well as seed collection and the driving of stakes into the ground for plant support, requires a considerable input of man-power. It is an intensive farming process, the cultivated area per farmer varies between 300 m² and 1000 m¹, and the yield ranges between 1.5 and 2.7 tons per hectare of fresh roots; when dried they lose up to 75% of their weight. Smoke-dried roots are exported for sale.     

Expression of carbohydrate residues in plasma membrane glycoproteins during the differentiation of amphibian epidermal cells

Summary Expression of various sugar residues on the plasma membrane of frog (Rana perezi) epidermal cells at different stages of differentiation has been monitored with the use of a battery of HRP-conjugated lectins. In paraffin-embedded tissue, mannose residues (stained by Concanavalin A) were detected at the keratinocyte cell surface in all epidermal strata. However,Lens culinaris agglutinin (LCA), also specific for mannose, specifically stained the plasma membrane of cells from the stratum germinativum. Expression of N-acetyl-glucosamine (GlcNAc), labelled with wheat germ agglutinin (WGA), was maximum at the cell surface of basal cells and progressively decreased through the stratum spinosum. Galactose (Gal) and N-acetyl-galactosamine (GalNAc) residues, labelled withGriffonia simplicifolia I (GS I) andGlycine max (SBA) agglutinins, respectively, were expressed according to the degree of differentiation in amphibian epidermal cells. Sialic acid-containing glycoproteins, labelled withLimax flavus agglutinin (LFA), were found in the outermost plasma membrane of the replacement cell layer and stratum corneum. Glycoproteins responsible for the observed lectin-binding patterns have been identified by staining on nitrocellulose filters after electrophoresis of solubilized plasma membrane fractions and Western blotting. Changes at the level of glycosylation of plasma membrane glycoproteins as epidermal cells differentiate are discussed on the basis of a progressive addition of Gal residues. Integral membrane proteins have been solubilized with the non-denaturing detergent CHAPS and glycoproteins containing terminal Gal residues, that are expressed according to the degree of differentiation in frog epidermis, have been partially purified by affinity chromatography on a GS I-Sepharose 4 B column. The purified fraction was composed by four acidic glycoproteins with isoelectric points between 4.6 and 5.2 and, in SDS-gels gave five major protein bands with approximate molecular weights of 148, 140, 102, 60, and 52 kDa in SDS-gels. The 102 and 52 kDa bands correspond to the a and subunits of amphibian epidermal Na⁺,K⁺-ATPase as demonstrated by specific staining with a polyclonal antibody against the catalytic subunit of pig kidney proton pump and staining with lectins GS I, GS II, and WGA. Possible relationships between higher molecular weight proteins and the constituents of intramembranous particles from the outermost plasma membranes of the replacement cell layer and the stratum corneum are also discussed.Abbreviations BSA bovine serum albumin - CHAPS (3-[(cholamidopropyl) dimethyl-ammonio] 1-propanesulfonate) - Con A Canavalia ensiformis agglutinin - DTT dithiothreitol - Gal galactose - GalNAc N-acetyl-D-galactosamine - GlcNAc N-acetyl-D-glucosamine - GS I Griffonia simplicifolia agglutinin I - GS II Griffonia simplicifolia agglutinin II - HRP horseradish peroxidase - LFA Limax flavus agglutinin - LCA Lens culinaris agglutinin - NDPAGIF non-denaturing polyacrylamide gel isoelectric focusing - PAGE polyacrylamide gel electrophoresis - PAP peroxidase-antiperoxidase - PBS phosphate buffered saline - PMSF phenyl methyl sulphonyl fluoride - RCL replacement cell layer - SBA soybean agglutinin (Glycine max) - SB stratum basal - SDS sodium dodecyl sulphate - SG stratum granulosum - SS stratum spinosum - UEA I Ulex europaeus agglutinin I - WGA wheat germ (Triticum vulgaris) agglutinin