Response of field-grownCasuarina equisetifolia to inoculation withFrankia strain ORS 021001 entrapped in alginate beads

A large scale field experiment (ca 1 ha) was carried out in Senegal, to evaluate the response ofCasuarina equisetifolia to inoculation withFrankia strain ORS 021001 entrapped in alginate beads. Biomasses (expressed as dry weight or total nitrogen) of assimilatory branchlets, wood and roots, and nodules were measured in uninoculated and inoculated trees, randomly sampled 1,2 and 3 years after transplantation in the field. When biomasses were expressed as dry weight, increases due to inoculation were similar at the three sampling dates, 45, 36 and 40%, respectively. When biomasses were expressed as total nitrogen, the response to inoculation with time was much higher in the 2nd year than in the 1st and 3rd year. N₂ fixation, estimated using the difference method reached 2.48, 12.25 and 13.44 g N₂ fixed annually per tree. Correspondingly, nodule dry weights, expressed in g per tree, were 2.5, 12.18 and 22.75 at the end of the 1 st, 2nd and 3rd year, respectively. In spite of the positive response of field-grownCasuarina equisetifolia to inoculation, the decrease of N₂ fixation observed in the third year was probably due to unfavorable climatic conditions coupled with insect attacks at the beginning of the third year.     

Counting viableAzotobacter chroococcum in vertisols

Methods for preparing soil suspensions for countingAzotobacter chroococcum in vertisols by soil dilution and plating were investigated. Mechanical methods to promote disaggregation of soil and Azotobacter microcolonies by shaking soil suspensions with glass beads (10% w/v) or coarse sand (1–2 mm fraction) increased soil dispersion and Azotobacter colony counts. Chemical methods for disaggregation were unsatis-factory. The non-ionic detergent Agral (0.004, 0.02, 0.1, 0.5 and 2.5% w/v) had no significant effect on soil dispersion and Azotobacter count. Both sodium pyrophosphate (0.03, 0.1, 0.3 and 0.9% w/v) and sodium metaphosphate as Calgon (0.022, 0.066, 0.2, 0.6 and 1.8% w/v) increased soil dispersion but were toxic to Azotobacter. Increasing time of shaking soil: distilled water suspensions increased deflocculation of the clay and Azotobacter counts to a maximum after 6–23 hours shaking. Comparable results were obtained within 30–60 minutes of shaking with coarse sand, but shaking with coarse sand beyond 2 hours reduced counts through mechanical damage to cells. Counts from suspensions in physiological saline (0.75% NaCl) and in distilled water were similar. Counts from suspensions in Jensen's mineral base shaken for <3 hrs were lower than from distilled water due to flocculation fo the soil by^Ca2+ ions, but were higher on extended shaking up to 23 hours due to better cell protection. Shaking soil suspensions in distilled water with 10% w/v coarse sand for 30 minutes is recommended when counting Azotobacter in vertisols.     

Spontaneous generation of selectable variation in the brain

Selection models of behavior presuppose selectable variation, diversity in the brain that is stable over time. Diversity can arise spontaneously through the mutual interactions of cell assemblies, which are postulated to align or disalign their neighbors into processing modes conforming to or opposite from their own. These processes are similar to magnetization and crystallization. If aligning and disaligning influences are distributed at random, a state resembling a spin glass can arise, where processing modes are highly varied in space but stable in time. If disalignment occurs regularly at the points of a two-dimensional lattice, and elsewhere the interactions are aligning, a pattern emerges with properties remarkably similar to visual orientation columns. These patterns are maintained dynamically, and emerge statistically without detailed genetic specification.Special issue dedicated to Dr. Eugene Roberts.     

Optimal conditions for production of lactic acid from cheese whey permeate by Ca-alginate-entrapped Lactobacillus helveticus

Whole cells of Lactobacillus helveticus were immobilized in calcium-alginate beads to produce lactic acid from cheese whey ultrafiltrate. Ca-alginate-entrapped cells were characterized by higher fermentation rates and optimum pH than free cells. No difference could be observed in the profile of cell activity against temperature for either type of cells. After a heat treatment, cell activity was higher for free cells than for immobilized cells. Continuous lactic acid fermentation using a packed bed reactor was investigated.     

A simplein situ method for the characterization of porosity in growth media

Summary The method presented was based on a very simple approach of the forces operating in the pores of porous media. The standardized time (t_v) needed to infiltrate a given volume of a liquid into a porous medium in a defined state was throught to be an integrated measure of pore geometry and continuity. The state of the pore system was defined by external suction (S) and medium porosity characterized by the parameters k₁ and k₂ in the equation t_v=k₁+k₂ S^−0.5. The method theory was not rejected by experiments with glass beads and selected peat based growth media. The method ranked the media with respect to the probability for satisfactory gas exchange in the order of peat, peat and 26% perlite, peat and 34% perlite, and peat and 44% mineral wool. This ranking was achieved 95 days after the media were filled in containers and exposed to a daily watering procedure. Before this time, the ranking of the media was slightly different, if at all possible. Five days after the containers were filled, only peat and 44% mineral wood was significantly different from the other media. Judged by the standardized time method, the probability for satisfactory gas exchange decreased significantly during the 95 days experiment. This aggravation was supported by measurements of the volume fraction of pores filled with gas. The changes with time were least marked in the medium containing mineral wool.     

Seasonal changes in ionoregulatory variables of the glass eel Anguilla anguilla following estuarine entry: comparison with resident elvers

In the present study, glass eels Anguilla anguilla in the Minho River estuary (41·5° N, 8·5° W) decreased in size (standard length, L _S and mass, M ) from the beginning (autumn) to the end of the sampling season (summer). On the other hand elvers increased in L _S and M from spring to summer and were significantly larger than glass eels in paired comparisons. Branchial Na⁺/K⁺-ATPase and vacuolar (V-type) proton ATPase ( in vitro activities), two important ion transporting pumps, did not show significant seasonal changes in either glass eels or elvers although in glass eels Na⁺/K⁺-ATPase (activity) expression was significantly higher than in elvers. In a single month comparison Na⁺/K⁺-ATPase branchial mRNA expression was also higher in glass eels as was the protein level expression of both Na⁺/K⁺-ATPase and NKCC (Na⁺:K⁺:2Cl⁻ co-transporter). Immunofluorescence microscopy indicated apical CFTR Cl⁻ channel labelling in Na⁺/K⁺-ATPase positive chloride cell in glass eels which was absent in elvers. Whole body sodium concentration and percentage water did not show significant seasonal differences in either glass eels or elvers although there were significant differences between these two groups during some months.     

Alteration of a Submarine Basaltic Glass under Environmental Conditions Conducive for Microorganisms: Growth Patterns of the Microbial Community and Mechanism of Palagonite Formation

In basaltic glass from the southern Mid-Atlantic-Ridge conducive environmental conditions for biogenic weathering resulted in excellent preserved microbial morphologies on glass surfaces. The distinct glass interface and open spaces between palagonite sheet and glass indicate a dissolution-reprecipitation mechanism of glass alteration potentially supported by microorganisms. On internal fracture surfaces, branching channels with widths at 20–30 μm containing longish structures with targeted dissolution of the glass by growing tips were observed. Alteration resulted in enrichment of Fe, Ti, P, and K in palagonite in amorphous mineral forms.     

Comparative efficacy of two controlled-release gypsy moth mating disruption formulations

The effects of aerial applications of the gypsy moth sex pheromone, disparlure, on mating disruption and suppression of growth of populations of the gypsy moth, Lymantria dispar (L.), were investigated. Two formulations of disparlure, plastic laminate flakes applied in a single application and polymethacrylate beads applied in two applications, were compared in two separate tests conducted in 1993 and 1994. The beads were applied in two applications spaced 2 weeks apart because preliminary tests had indicated that they released pheromone too rapidly to maintain adequate emission rates throughout the period of male flight. In 1993, the flakes were applied at a rate of 50 g a.i./ha, and the beads were applied at a rate of 15 g a.i./ha for each application. In 1994, the flakes were applied at a rate of 75 g a.i./ha and the beads were applied at rates of 32.5 and 42.5 g a.i./ha for the two applications. Beads with larger average particle size were used in 1994 to prolong disparlure release. The treatments applied in 1993 resulted in >97% reduction in mating and >82% suppression of population growth in the following year. Because of a 1995 collapse of gypsy moth populations in the vicinity of the tests, reliable population growth data were not available for the treatments applied in 1994, but significant mating disruption did occur under both treatments. Based on measurements of residual disparlure after field aging, the flakes released 32 and 48% of their disparlure content during the 6 weeks of male moth flight in 1993 and 1994, respectively. The smaller beads used in 1993 released 75% of their disparlure content, and the larger beads used in 1994 released 52% of their disparlure content, during the 6 weeks of male flight. The biological efficacy data suggest that the bead and flake formulations, as applied in these tests, have similar effects on gypsy moth mating disruption and subsequent population growth. Based on the observed release rates from both 1993 and 1994, a single application of the beads would provide emission rates equal to or greater than those provided by the flakes when applied at an equal dose.     

Gravettian tear-drop-shaped beads

The two regions southwestern Germany and southwestern France have yielded Gravettian personal ornaments in form of tear-drop-shaped beads. We present updated numbers of these artefacts, because during the recent excavations since 2002 in Hohle Fels cave near the city of Ulm, Southwest Germany, additional beads were found. The present paper proposes for the first time a typo-technological study of the tear-drop-shaped beads.