The uptake of nutrients (glucose, glutamine, and N-acetylglucosamine), the intracellular concentrations of metabolites (glucose-6-phosphate, cyclic AMP, amino acids, trehalose, and glycogen) and cell wall composition were studied in Candida albicans. These analyses were carried out with exponential-phase, stationary-phase, and starved yeast cells, and during germ-tube formation. Germ tubes formed during a 3-h incubation of starved yeast cells (0.8 X 10(8) cells/mL) at 37 degrees C during which time the nutrients glucose plus glutamine or N-acetylglucosamine (2.5 mM of each) were completely utilized. Control incubations with these nutrients at 28 degrees C did not form germ tubes. Uptake of N-acetylglucosamine and glutamine was inhibited by cycloheximide which suggests that de novo protein synthesis was required for the induction of these uptake systems. The glucose-6-phosphate content varied from 0.4 nmol/mg dry weight for starved cells to 2-3 nmol/mg dry weight for growing yeast cells and germ tube forming cells. Trehalose content varied from 85 nmol/mg dry weight (growing yeast cells and germ tube forming cells) to 165 nmol/mg weight (stationary-phase cells). The glycogen content decreased during germ-tube formation (from 800 to 600 nmol glucose equivalent/mg dry weight) but increased (to 1000 nmol glucose equivalent/mg dry weight) in the control incubation of yeast cells. Cyclic AMP remained constant throughout germ-tube formation at 4-6 pmol/mg dry weight. The total amino acid pool was similar in exponential, starved, and germ tube forming cells but there were changes in the amounts of individual amino acids. The overall cell wall composition of yeast cells and germ tube forming cells were similar: lipid (2%, w/w); protein (3-6%), and carbohydrate (77-85%). The total carbohydrates were accounted for as the following fractions: alkali-soluble glucan (3-8%), mannan (20-23%), acid-soluble glucan (24-27%), and acid-insoluble glucan (18-26%). The relative amounts of the alkali-soluble and insoluble glucan changed during starvation of yeast cells, reinitiation of yeast-phase growth, and germ-tube formation. Analysis of the insoluble glucan fraction from cells labelled with [14C]glucose during germ-tube formation showed that the chitin content of the cell wall increased from 0.6% to 2.7% (w/w).

ABSTRAW Mouse monoclonal antibodies have been produced against syncytiotrophoblast plasma membrane preparations isolated from term human placentas. Of 20 positive clones, two antibodies (H309, H318) were directed against the Cy2 domain of IgG, one (H312) was directed against albumin, and another (H303) was directed against a further normal human serum component (not transferrin). One monoclonal antibody (H310) recognized an antigenic epitope restricted to trophoblast and lymphocytes: this antibody did not inhibit mitogenic or allogeneic stimulation of lymphocytes. Two monoclonal antibodies (H315 and H317) reacted with trophoblast-specific antigenic determinants. The H315 antigen was present on first trimester syncytiotrophoblast, unlike the H317 antigen. (Am J Reprod Immunol. 1981; 1:246-254.)

The monoclonal antibodies (mAb) H315, H317, and OKT9 have been used in immunofluorescence to investigate the expression of fetal trophoblast membrane antigens by cells within human term amniochorionic membranes and the marginal area of term placental bed tissue. OKT9 reacted only with trophoblast of placental chorionic villi and did not react with any nonvillous cytotrophoblast population: this mAb is known to identify the cell surface receptor for transferrin. H315 identifies a trophoblast-specific cell-surface antigen and strongly stained both placental villous trophoblast and the cytotrophoblastic layer of amniochorion. This mAb also stained some extravillous cytotrophoblast in the term placental bed, notable interstitial cytotrophoblast within maternal decidua. H317, which identifies placental-type alkaline phosphatase, gave the same distribution pattern as H315.

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