The polar polysaccharide capsule of Hyphomonas adhaerens MHS-3 has a strong affinity for gold.

Select groups of bacteria, including prothescate species, have an unusual capacity to sequester gold and bioconcentrate it to very high levels. Hyphomonas adhaerens MHS-3 (MHS-3) is one such species, as demonstrated by Energy Dispersive Spectroscopy. Transmission electron microscopy revealed that the binding site was specific on the polar polysaccharide capsule. A capsuleless mutant and periodate-treated wild type did not sequester gold. The gold may interact with the same sites in the capsule that naturally adhere MHS-3 to surfaces in the marine environment.

Spatial and Temporal Deposition of Adhesive Extracellular Polysaccharide Capsule and Fimbriae by Hyphomonas Strain MHS-3.

Hyphomonas strain MHS-3, a member of a genus of primary colonizers of surfaces immersed in marine water, synthesizes two structures that mediate adhesion to solid substrata, namely, capsular exopolysaccharide and fimbriae. Specific stains, gold-labelled lectins, and monoclonal antibodies, along with transmission electron microscopy of synchronized populations, revealed that both structures are polarly and temporally expressed. The timed synthesis and placement of the fimbriae and capsule correlated with the timing and locus of MHS-3 adhesion.

Fine-structure evidence for cell membrane partitioning of the nucleoid and cytoplasm during bud formation in Hyphomonas species.

Hyphomonas spp. reproduce by budding from the tip of the prosthecum, distal to the main body of the reproductive cell; thus, the chromosome must travel through the prosthecum to enter the progeny, the swarm cell. When viewed by electron microscopy, negatively stained whole cells, ultrathin-sectioned cells, and freeze-etched and frozen hydrated cells all had marked swellings of the cytoplasmic membrane (CM) in the prosthecum which are termed pseudovesicles (PV). PV were separated by constrictions in the contiguous CM. In replicating cells, PV housed ribosomes and DNA, which was identified by its fibrillar appearance and by lactoferrin-gold labeling. The micrographs also revealed that the CM bifurcates at the origin of the prosthecum so that one branch partitions the main body of the reproductive cell from the prosthecum and swarm cell. The results of this fine-structure analysis suggest models explaining DNA segregation and the marked asymmetric polarity of the budding reproductive cell.

Upstream sequence of the parahydroxyphenyl-pyruvate dioxygenase (melA) coding region leading to enhanced expression in Shewanella colwelliana.

Hyperexpression of the enzyme, parahydroxyphenylpyruvate dioxygenase (pHPPH; melA), in the tyrosine degradative pathway yields excess homogentisic acid which oxidatively polymerizes to pyomelanin. Depression of melA in Shewanella colwelliana strain D was found to result from a single base pair transition upstream of the promoter. This was the sole lesion detected in pHPPH hyperexpressing strains. It is suggested that a T to C transition alters the mRNA structure, exposing the ribosome binding site, thereby enhancing translational efficiency.

Adhesion of biofilms to inert surfaces: A molecular level approach directed at the marine environment.

Protein/ligand interactions involved in mediating adhesion between microorganisms and biological surfaces have been well-characterized in some cases (e.g. pathogen/host interactions). The strategies microorganisms employ for attachment to inert surfaces have not been so clearly elucidated. An experimental approach is presented which addresses the issues from the point of view of molecular interactions occurring at the interface.

Evidence for the Adhesive Function of the Exopolysaccharide of Hyphomonas Strain MHS-3 in Its Attachment to Surfaces.

Hyphomonas strain MHS-3 (MHS-3) is a marine procaryote with a biphasic life cycle and which has prosthecate stages that adhere to submerged substrata. We found that adherent forms produced an exopolysaccharide (EPS) capsule that bound Glycine max lectin, Arachis hypogaea lectin, and Bauhinia purpurea lectin (BPA), each having affinity for N-acetyl-d-galactosamine. It also bound the dye Calcofluor. BPA and Calcofluor were tested for the ability to hinder MHS-3 adhesion to glass surfaces; they reduced attachment by >50 and >85%, respectively. Periodate treatment also reduced attachment (by >80%), but pronase treatment did not. Furthermore, an EPS(sup-) variant, Hyphomonas strain MHS-3 rad, did not attach well to surfaces. These results suggest that the MHS-3 EPS capsule is an adhesin.

Homogentisic acid is the primary precursor of melanin synthesis in Vibrio cholerae, a Hyphomonas strain, and Shewanella colwelliana.

The enzyme p-hydroxyphenylpyruvate hydroxylase (HPPH) is involved in pigmentation (pyomelanin) via homogentisic acid (HGA). Pyomelanin formation is correlated with HGA production and expression of HPPH in three disparate marine species: Vibrio cholerae, a Hyphomonas strain, and Shewanella colwelliana. Induction of pigmentation in V. cholerae 569B by nutrient limitation also correlated with production of HGA.

A sensitive chromatographic method for the detection of pyruvyl groups in microbial polymers from sediments.

A method was developed for the quantitation of pyruvyl groups in microbial polymers using mild acid hydrolysis, o-phenylenediamine labeling, reversed-phase high-performance liquid chromatography (RP-HPLC), and fluorescence detection. The method was used to determine the pyruvate content of various microbial exopolysaccharides and to estimate the abundance of polymeric pyruvate in freshwater sediments. The results of this method were compared with those of several other pyruvate assays. The detection limit of the method was 1.6 nmol pyruvate. As little as 3.7µg of the bacterial polysaccharide xanthan gum, or from 5 to 22 mg of sediment (depending on polymeric pyruvate content), were needed for detection and quantitation of polymeric pyruvate. The results should be useful in determining the contribution of polymeric pyruvate to total metal-binding ligands in sediments.

The osmotic coefficients of the sodium form of some biopolymers.

The osmotic coefficients phi p,Na of dilute solutions of the sodium form of some weakly acidic polymers are theoretically predicted in this work. Based on the measured value 0.73 of gamma Na, the activity coefficient of free Na+, of the completely ionized humic acid (sodium salt) in a salt-free solution, the effective interligand distance b is calculated to be 11.34 A by using Manning's counterion condensation theory [Manning, G. S. (1969) J. Chem. Phys. 51(3), 924]. The corresponding values of gamma Na (measured experimentally) and b for the completely ionized exopolymer of Pseudomonas atlantica are 0.624 and 7.57 A when cultivated at a dilution rate D = 0.015 h-1, 0.647 and 8.19 A at D = 0.025 h-1, and 0.613 and 7.29 Aat D = 0.06 h-1. For alginic acid (in the completely ionized sodium form), gamma Na = 0.40 and b = 4.71 A. The osmotic coefficients phi p,Na for the partially and the completely ionized polymers are then predicted with Manning's theory as well.

Developmental age trends in crossing the body midline in normal children.

The ability to cross the body midline was assessed in 150 normal children, ages 4 through 8, by observing hand usage during the Space Visualizaion Test of the Southern California Sensory Integration Tests. A Space Visualization Contralateral Use score (SVCU) was computed for each subject and was regarded as a measure of the tendency to spontaneously cross the body midline. This score is based on a ratio of ipsilateral (uncrossed) to contralateral (crossed) responses. The percentage of time a child use the preferred hand to pick up a block was also recorded. Results indicated that spontaneous midline crossing increased with age. Although the percent of preferred hand responses increased with age, there was enough variability at each age that there were no significant differences among age groups. Perceptual, motor, and psychosocial factors that could influence midline behavior were discussed. Based on the data from this study, a preliminary reinterpretaton of the SVCU score is offered.