The measuring of cell features

The usefulness of various feature sets for discriminating between different cell populations cannot be assessed without considering the entire automated cytology system, from specimen preparation through scanning, cell search, cell segmentation, artifact rejection and feature extraction to object classification and multivariate data analysis methods. These different stages in the analysis procedure are discussed in this paper and illustrated by examples from the author's experience of cell analysis studies, ranging from single-cell classification experiments to a test of a complete automated system under realistic conditions on a set of 397 cell specimens.     

Growth and metabolic flexibility in groundwater bacteria

Groundwater bacteria isolated from an oligotrophic-saturated soil showed a mixed strategy of economized metabolism and migration when grown in a continuous-flow column system simulating poor or nutrient-amended growth conditions. The cells were generally <0.5m in diameter in pure groundwater, but doubled in size when the concentration of dissolved organic carbon and phosphate in groundwater was increased 10-fold. The biomass, estimated from analysis of muramic acid (MuAc) in cell wall peptidoglucans, increased at the same time by a factor of 5 when the solid support in the columns was gravel and by a factor of 10 when it was glass beads. Bacteria in pure groundwater stored 10 times more of the energy-rich polysaccharide, poly--hydroxybutyric acid (PHB), than bacteria in enriched groundwater, and those cells that were attached to the gravel stored 10 times as much as cells in the interstitial pore water. Once phosphate was added to groundwater, stored PHB was metabolized. The proportion of free-living to attached bacteria was 2 to 10 times higher in enriched compared with pure groundwater indicating a mass transport of cells as the carrying capacity of their habitat rose.     

Algesia and local responses induced by neurokinin A and substance P in human skin and temporal muscle

Neurokinin A (NKA), substance P (SP) and the two peptides combined (SP + NKA) were injected intracutaneously on the forearm and into the temporal muscle of healthy volunteers. Pain intensity, cutaneous wheal and flare responses and tenderness of the temporal muscle were quantitated. SP but not NKA induced cutaneous pain. This relates the algesic effect of SP to the specific N-terminal amino acid sequence of the peptide, not shared by NKA. NKA, however, potentiated the algesic effect of SP as SP + NKA induced a significantly prolonged cutaneous pain sensation. Both peptides induced wheals, but only SP induced flare. These results confirm previous studies relating wheal formation to the identical C-terminal amino acid sequence of the two peptides and flare reaction to the N-terminal part of SP. Injections into the temporal muscle did not cause pain or tenderness.     

Mitogen Stimulation of Lymphocytes in Pigs with Hereditary Vitamin C Deficiency

Recently an inherited vitamin G deficiency in the pigs presumably based on an autosomal recessive gene was decribed* Homozygotes are in contrast to heterozygotes and normal pigs unable to synthesize ascorbic acid. In an experiment comprising 3 littermate pigs, 2 homozygous and 1 heterozygous for the vitamin C deficiency gene, the influence of ascorbic acid depletion, and repletion on mitogen stimulation of peripheral blood lymphocytes was studied. Ascorbic acid depletion of the vitamin C dependent pigs resulted in a rapid decline in plasma ascorbic acid. Response of lymphocytes to stimular tion with Concanavalin A (Con A) and phytohemagglutinin M (PHA) decreased more slowly reaching a minimum, which coincidedi with the occurrence of the first clinical symptoms of scurvy. Following resupplementation with vitamin C the plasma content of ascorbic acid rapidly returned to normal, while the lymphocyte response to Con A and PHA stimulation only gradually approached the initial values. The repletion with ascorbic acid caused a transitory increase in the response to pokeweed mitogen (PWM) stimulation. The significance of these findings in relation to the cellular immune system in normal pigs is discussed.     

T-DNA presence and opine production in tumors of Picea abies (L.) Karst induced by Agrobacterium tumefaciens A281

The hypervirulent Agrobacterium tumefaciens strain A281 formed frequent tumors (31%) on Picea abies (Norway spruce), an economically important tree species in Swedish forests. Three-month-old seedlings were inoculated and tumors were established that grew hormone-independently in culture. Tumors contained agropine and mannopine/mannopinic acid as determined by acid pH paper electrophoresis. In addition, DNA hybridization studies showed that the DNA from these tumor lines contained sequences homologous to Ti plasmid T-DNA, whereas wild-type spruce seedling DNA did not. These results suggest that Agrobacterium vectors can be used for gene transfer into this important forest species.