Bovine leukocyte phagocytosis and bacteria killing monitored by intracellular acridine orange fluorescence and extracellular fluorescence quenching

The time course of phagocytosis and intracellular killing of serum-opsonized Escherichia coli K12 and Staphylococcus aureus SG511 by glass-adherent bovine peripheral blood polymorphonuclear leukocytes (PMNLs) and cultured monocytes (macrophages) was monitored by fluorescence microscopy of single cells using the acridine orange (AO)/crystal violet (CV) technique. After interaction of glass-adherent leukocytes (20, 40, 60 min, 37 degrees C) with opsonized bacteria, cells were stained with the fluorescent dye AO. Living bacteria stained green, dead bacteria stained orange. The addition of CV to AO-stained bacteria quenched the fluorescence of extracellular bacteria only. CV does not penetrate living bovine PMNLs which allows the discrimination of ingested (fluorescent) and extracellular (nonfluorescent) bacteria during attachment and phagocytosis of bacteria by adherent PMNLs. We investigated quantitatively phagocytosis and intracellular killing of serum-opsonized bacteria by bovine PMNLs from 22 bulls of 4 different Swiss dairy breeds. Within 60 min maximum uptake (approximately 12 bacteria/PMNL) and killing (approximately 80%) of serum-opsonized Escherichia coli K12 and Staphylococcus aureus SG511 were achieved. The AO/CV technique was also used to quantify the uptake and intracellular killing of serum-opsonized Escherichia coli K12 by cultured monocytes (macrophages). Within 60 min maximum uptake of bacteria (approximately 16/MO) was achieved; approximately 83% of bacteria were killed.     

Fish diseases in Switzerland. A statistical evaluation of the diagnostic materials of the fish research laboratory from 1979-1988. I. General aspects]

The entire diagnostic material of the Fish Disease Laboratory at the University of Berne from 1979 to 1988, a total of more than 3800 cases, is presented. Not included is material of import controls and material from experimental work. The following criteria were evaluated: fish species, origin and length of fish, season, infectious and noninfectious diseases. Furthermore, the results were investigated for changes of the composition of fish species and number of diseases within the ten-year period and for a seasonal influence on the outbreak of diseases. More than 40% of all fish investigated were rainbow trout, followed by brown trout, omamental fish and cyprinids. Over 40% of fish originated from private fishfarms whereas 20% were of governmental origin (governmental fishfarms, rivers, lakes) and 20% from aquaria. Parasites were present in more than 40% of all cases. Bacterial infections were diagnosed in nearly 30%, viral infections in 6% and fungal diseases in 5% of all cases. 20% of all cases concerning noninfectious diseases were caused by unfavourable environmental conditions whereas the incidence of diseases related to nutrition was less than 10%. The occurrence of the different diseases was waxing and waning over the period of ten years but no definite tendencies could be emphasized. However, most of the diseases investigated demonstrated a significant seasonal influence.     

Simplified performance assessment methodology for addressing soil quality of nature-based solutions

Journal of Soils and Sediments - In urban areas, soil functions are deeply impacted by all human activities, e.g., water infiltration, carbon storage, and chemical substances degradation potential....     

Ocean energy: forms and prospects

The nature and distribution of power sources of the sea other than petroleum are discussed, along with possible entrées for their use. Waves, tides, currents, and salinity and temperature gradients all have the potential to contribute useful power. Submarine geothermal sources, salt domes, ice, and other marine-associated concentrations may be more important. There are opportunities to employ these marine power resources directly rather than for contributions to power grids or power-intensive products. Ancillary employment of the seawater as a coolant and of the sediments below the seabed for the disposal of nuclear wastes may be even more important uses than employment of the power that the sea contains.     

Olfaction: responses of a decapod crustacean are enhanced by flicking

Periodic movements of the olfactory organs, known as "flicking," temporally enhance the response of the olfactory receptors of the spiny lobster to changes in stimulus concentration. This reflex provides the lobster with a physiological mechanism to compensate for the indiscrete temporal nature of chemical stimuli.     

Dislocation-driven nanowire growth and Eshelby twist

Hierarchical nanostructures of lead sulfide nanowires resembling pine trees were synthesized by chemical vapor deposition. Structural characterization revealed a screwlike dislocation in the nanowire trunks with helically rotating epitaxial branch nanowires. It is suggested that the screw component of an axial dislocation provides the self-perpetuating steps to enable one-dimensional crystal growth, in contrast to mechanisms that require metal catalysts. The rotating trunks and branches are the consequence of the Eshelby twist of screw dislocations with a dislocation Burgers vector along the 110 directions having an estimated magnitude of 6 +/- 2 angstroms for the screw component. The results confirm the Eshelby theory of dislocations, and the proposed nanowire growth mechanism could be general to many materials.     

Management of 1,3-dichloropropene in pineapple for efficacy and reduced volatile losses

Two application methods, single- and double-chisel injection of the fumigant nematicide 1,3-dichloropropene (1,3-D) were evaluated for efficacy and environmental fate in pineapple field experiments. The objectives were to compare the 1,3-D soil distribution between injection methods, evaluate volatile losses to the atmosphere, and to determine efficacy with each method. In a small-plot field experiment, 1,3-D (224, 337, and 393 1 ha⁻¹) was manually injected 30 cm deep with fumiguns to simulate the commercial practice of a single- or double-chisel injection per planting bed. 1,3-D concentrations in the soil atmosphere and in soil samples were determined and compared to nematode control. In two large-scale field experiments, 1,3-D (224 1 ha⁻¹) was applied with commercial injection equipment with and without polyethylene mulch. Air monitoring for 1,3-D showed a reduction in 1,3-D air emissions with single-chisel injection compared with double-chisel injection. In all experiments, the two injection methods resulted in equivalent 1,3-D concentrations in the plant line. Single-chisel injection resulted in improved retention of 1,3-D within the planting bed as shown by low 1,3-D soil concentrations in the interbed. Nematode counts and bioassay studies found equivalent nematode control in the planting bed with either injection method. The single-chisel method, however, resulted in reduced nematode control in the interbed region.