Differences in physical growth of Aymara and Quechua children living at high altitude in Peru

Physical growth of Amerindian children living in two Aymara and three Quechua peasant communities in the Andean highlands of southern Peru (altitude 3,810–3,840 m) was studied, taking into account differences in the microclimate, agronomic situation, and sociodemographic variables. Anthropometric measurements were taken in 395 children aged under 14 years of age in a sample of 151 families in these communities, who were surveyed for sociodemographic variables as well. Data on the land system were available for 77 families. In comparison with reference populations from the United States (NCHS) and The Netherlands, stature, weight, head circumference, and midupper arm circumference (but not weight for stature) in the sample children were reduced. Growth retardation increased after the age of 1 year. Stature and weight in the present sample were very similar compared with previously published data on growth of rural Aymara children living near Lake Titicaca in Bolivia. Head circumference, midupper arm circumference, and weight for stature were significantly larger in Aymara children compared with Quechua children. Land was significantly more fragmented in Aymara compared with Quechua families, but amount of land owned was not different. Perinatal and infant mortality was elevated in Aymara vs. Quechua communities. Most families in Aymara communities used protected drinking water. One Quechua community had a severe microclimate, grim economic outlook, and weak social cohesion. Children in this community showed significant reductions in weight and midupper arm circumference compared with their peers in the other communities. We conclude that (presumably nutritionally mediated) intervillage and Aymara-Quechua differences in childhood physical growth existed in this rural high-altitude population in Peru and were associated with microclimate and the village economy, sociodemographic factors, and differences in the land system. © 1993 Wiley-Liss, Inc.     

Extra- and Intracellular Laccases of the Chestnut Blight Fungus, Cryphonectria parasitica

A double-stranded RNA virus of the chestnut blight pathogen, Cryphonectria parasitica, has been shown previously to reduce accumulation of mRNAs of extracellular laccase (laccase A) produced by this fungus. Both extra- and intracellular laccases have been detected after growth of the fungus in liquid culture. In addition to cellular localization, the two laccases are distinguishable by time of appearance during growth and electrophoretic mobility. Laccase A was purified from the culture filtrate by standard protein purification procedures. The enzyme was characterized as a glycoprotein with a molecular mass of approximately 77 kDa. Both laccase A and laccase B activities were significantly reduced in the hypovirulent (double-stranded RNA-infected) strain UEP1 compared with the isogenic virulent (double-stranded RNA-free) strain EP155/2.     

Metabolic Activity and Population Dynamics of Rhizobia Introduced into Unamended and Bentonite-Amended Loamy Sand

Respiration measurements showed that the cumulative amount of CO₂ respired by rhizobia introduced into sterile bentonite-amended loamy sand was significantly higher than it was in unamended loamy sand. The maintenance respiration of rhizobial cells was not influenced by the presence of bentonite clay. Carbon was used more efficiently during growth in bentonite-amended than in unamended loamy sand. The presence of bentonite clay increased the growth rate of rhizobia introduced into sterile soil. Survival studies performed in nonsterile bentonite-amended loamy sand showed that the use of high (10¹⁰ cells per g of dry soil) rather than lower (10⁴ to 10⁷ cells per g of dry soil) inoculum densities increased the final survival levels of introduced rhizobia. In unamended loamy sand, the application of 10¹⁰ or 10⁷ cells per g of dry soil resulted in similar final survival levels. Pore shape and the continuity of the water-filled pore system were suggested to largely determine the colonization rate of protective microhabitats.     

Isolation and characterization of an extracellular glycosylated protein complex from Clostridium thermosaccharolyticum with pectin methylesterase and polygalacturonate hydrolase activity.

An extracellular protein complex was isolated from the supernatant of a pectin-limited continuous culture of Clostridium thermosaccharolyticum Haren. The complex possessed both pectin methylesterase (EC 3.1.1.11) and exo-poly-alpha-galacturonate hydrolase (EC 3.2.1.82) activity and produced digalacturonate from the nonreducing end of the pectin chain. The protein consisted of 230- and 25-kDa subunits. The large subunit contained 10% (wt/wt) sugars (N-acetylgalactosamine and galactose). Under physiological conditions both activities acted in a coordinated manner: the ratio between methanol and digalacturonate released during degradation was constant and equal to the degree of esterification of the pectin used. Prolonged incubation of the enzyme with pectin led to a nondialyzable fraction that was enriched in neutral sugars, such as arabinose, rhamnose, and galactose; the high rhamnose/galacturonic acid ratio was indicative of hairy region-like structures. The smallest substrate utilized by the hydrolase was a tetragalacturonate. Vmax with oligogalacturonates increased with increasing chain length. The Km and Vmax for the polygalacturonate hydrolase with citrus pectate as a substrate were 0.8 g liter-1 and 180 mumol min-1 mg of protein-1, respectively. The Km and Vmax for the esterase with citrus pectin as a substrate were 1.2 g liter-1 and 440 mumol min-1 mg of protein-1, respectively. The temperature optima for the hydrolase and esterase were 70 and 60 degrees C, respectively. Both enzyme activities were stable for more than 1 h at 70 degrees C. The exo-polygalacturonate hydrolase of Clostridium thermosulfurogenes was partially purified while the methylesterase was also copurified.     

Indigenous Bacteria in Hemolymph and Tissues of Marine Bivalves at Low Temperatures

Hemolymph and soft tissues of Pacific oysters (Crassostrea gigas) kept in sand-filtered seawater at temperatures between 1 and 8°C were normally found to contain bacteria, with viable counts (CFU) in hemolymph in the range 1.4 × 10² to 5.6 × 10² bacteria per ml. Pseudomonas, Alteromonas, Vibrio, and Aeromonas organisms dominated, with a smaller variety of morphologically different unidentified strains. Hemolymph and soft tissues of horse mussels (Modiolus modiolus), locally collected from a 6- to 10-m depth in the sea at temperatures between 4 and 6°C, also contained bacteria. The CFU in horse mussel hemolymph was of the same magnitude as that in oysters (mean, 2.6 × 10⁴), and the bacterial flora was dominated by Pseudomonas (61.3%), Vibrio (27.0%), and Aeromonas (11.7%) organisms. In soft tissues of horse mussels, a mean CFU of 2.9 × 10⁴ bacteria per g was found, with Vibrio (38.5%), Pseudomonas (33.0%), and Aeromonas (28.5%) constituting the major genera. After the challenge of oysters in seawater at 4°C to the psychrotrophic fish pathogen Vibrio salmonicida (strains NCIMB 2245 from Scotland and TEO 84001 from Norway) and a commensal Aeromonas sp. isolated from oysters, the viable count in hemolymph increased 1,000-fold to about 10⁵ bacteria per ml. In soft tissues, about a 1,000-fold increase in CFU to 6 × 10⁷ was observed. V. salmonicida NCIMB 2245 invaded hemolymph and soft tissues after 14 days and dominated these compartments after 41 days, whereas strain TEO 84001 did not invade soft tissues to the same extent. Challenge with V. salmonicida NCIMB 2245 resulted in 100% mortality, whereas about 50% of the oysters survived challenge with the Norwegian strain, TEO 84001. The commensal Aeromonas sp. invaded hemolymph and soft tissues and caused 100% mortality. Oyster hemolymph contained agglutinins for Vibrio anguillarum but not for V. salmonicida, whereas we did not find agglutinins for either of these bacteria in horse mussels. Agglutinins for horse and human erythrocytes were found in hemolymph from both animals. We found no differences in agglutinin titers in oysters from different Norwegian locations, and long-term challenge with bacteria in seawater did not result in changes of agglutinin activity. These studies demonstrate that bacteria exist in hemolymph and soft tissues of marine bivalves at temperatures below 8°C. Increased bacterial numbers in seawater at 4°C result in augmented invasion of bacteria in hemolymph and soft tissues. V. salmonicida, a bacterium pathogenic for fish at low temperatures, invades bivalve hemolymph and soft tissues, and thus bivalves may serve as a reservoir for pathogens of fish at low seawater temperatures.     

Quantitative Determination of the Spatial Distribution of Nitrosomonas europaea and Nitrobacter agilis Cells Immobilized in κ-Carrageenan Gel Beads by a Specific Fluorescent-Antibody Labelling Technique

A novel technique, combining labelling and stereological methods, for the determination of spatial distribution of two microorganisms in a biofilm is presented. Cells of Nitrosomonas europaea (ATCC 19718) and Nitrobacter agilis (ATCC 14123) were homogeneously distributed in a κ-carrageenan gel during immobilization and allowed to grow out to colonies. The gel beads were sliced in thin cross sections after fixation and embedding. A two-step labelling method resulted in green fluorescent colonies of either N. europaea or N. agilis in the respective cross sections. The positions and surface areas of the colonies of each species were determined, and from that a biomass volume distribution for N. europaea and N. agilis in κ-carrageenan gel beads was estimated. This technique will be useful for the validation of biofilm models, which predict such biomass distributions.     

Mobilization of a Recombinant IncQ Plasmid between Bacteria on Agar and in Soil via Cotransfer or Retrotransfer

Mobilization of a genetically engineered IncQ plasmid, pSKTG, was studied in vitro and in sterile and nonsterile soils. In biparental and triparental filter matings, the mobilization frequencies of pSKTG were identical, and the plasmid was mobilized only in the presence of self-transmissible plasmid RP4p. In sterile soil, mobilization was probably limited by reduced cell-to-cell contact, since the frequencies of mobilization were approximately 100-fold lower than the frequencies in the filter matings. The transfer frequency of pSKTG in sterile soil when RP4p was present in the same strain was about 100-fold higher than the transfer frequency when RP4p was present in a separate strain. In studies in natural soil, pSKTG was also found to be transferred to indigenous bacteria. However, natural mobilization by genetic elements present in the indigenous soil microflora could not be detected. In vitro studies of natural transfer suggested that such genetic elements occur in soil bacteria.     

Microgradients of Microbial Oxygen Consumption in a Barley Rhizosphere Model System

A microelectrode technique was used to map the radial distribution of oxygen concentrations and oxygen consumption rates around single roots of 7-day-old barley seedlings. The seedlings were grown in gel-stabilized medium containing a nutrient solution, a soil extract, and an inert polymer. Oxygen consumption by microbial respiration in the rhizosphere (<5 mm from the root) and in bulk medium (>30 mm from the root) was determined by using Fick's laws of diffusion and an analytical approach with curve fitting to measured microprofiles of oxygen concentration. A marked increase of microbial respiration was observed in the inner 0- to 3-mm-thick, concentric zone around the root (rhizosphere). The volume-specific oxygen consumption rate (specific activity) was thus 30 to 60 times higher in the innermost 0 to 0.01 mm (rhizoplane) than in the bulk medium. The oxygen consumption rate in the root tissue was in turn 10 to 30 times higher than that in the rhizoplane. Both microbial respiration and oxygen uptake by the root varied between different roots. This was probably due to a between-root variation of the exudation rate for easily degradable carbon compounds supporting the microbial oxygen consumption.     

Crystal structure,conformational analysis,and molecular dynamics of tetra-O-methyl-(+) -catechin

The structure of tetra-O-methyl- (+) -catechin has been determined in the crystalline state. Two independent molecules, denoted structure A and structure B, exist in the unit cell. Crystals are triclinic, space group P1, a = 4.8125(2) Å, b = 12.9148(8) Å, c = 13.8862(11) Å, α = 86.962(6) °, β = 89.120(5)°, γ = 88.044(5)°, Z = 2, D_c = 1.336 g cm^?3, R = 0.033 for 6830 observations. The heterocyclic rings of the crystal structures are compared to previous results for 8-bromotetra-O-methyl-(+)-catechin, penta-O-acetyl-(+)-catechin, and (?) -epicatechin. One of the two molecules has a heterocyclic ring conformation similar to that observed previously for (?)-epicatechin, and the other has a heterocyclic ring conformation similar to one predicted earlier in a theoretical analysis of dimers of (+)-catechin and (?) -epicatechin. Both structure A and structure B in the crystal have heterocyclic ring conformations that place the dimethoxyphenyl substituent at C(2) in the equatorial position. However, this heterocyclic ring conformation does not explain the proton nmr coupling constant measured in solution. Molecular dynamics simulations show an equatorial ? axial interconversion of the heterocyclic ring, which can explain the nmr results. © 1993 John Wiley & Sons, Inc.