Human carcinoma cell lines xenografted in athymic mice: biological and antigenic characteristics of an intraabdominal model

Summary In order to investigate in vivo clinical applications of murine monoclonal antibodies directed against human ovarian carcinoma a preclinical in vivo model was developed using BALB/c athymic mice. Three human carcinoma cell lines (MCF7, HT29, and SW626) were injected into the peritoneal cavity of pristane-primed animals and the biological and antigenic characteristics of the i.p. grown tumors were studied. The animals were killed when moribund or 6–8 weeks after tumor injection. At autopsy tumor take was observed in 85% of the injected animals, whereas palpable nodules were evident in only 83%. Examination of the peritoneal cavity revealed intraabdominal carcinomatosis with tumor masses varying in size between 0.2 and 0.5 cm in diameter and tumor sheets. The most frequently affected organs were the diaphragm, the liver, and the reproductive system. Ascitic fluid formation was rare and no animal developed tumors outside the peritoneal cavity. To determine whether the in vivo tumors retained the same antigenic characteristics as the in vitro cell lines, four monoclonal antibodies (MBrl, MOv2, MOv8, and MOv15) directed against ovarian carcinoma-associated antigens and two different experimental approaches (immunofluorescence and immunoblotting) were used. Variations at either a quantitative or a qualitative level were observed for some antigens, whereas no evident changes were apparent for others. In particular, the antigens detected by MBr1 and MOv15 on the MCF7 line both maintained high levels of expression and immunoblotting staining pattern, whereas the antigens detected by MOv2 on the HT29 and SW626 lines, although present at a high level, clearly changed their staining pattern. As regards the antigens recognized by MOv8 and MOv15 on the HT29 and SW626 lines, we observed a drastic decrease in the level of their expression and in many cases a drop below the threshold of detectability of the test. The intraabdominal carcinomatosis described partially mimics the growth characteristics of human ovarian cancer and maintains the expression of some antigenic markers associated with epithelial tumors of the ovary and may therefore be useful in devising immunodiagnostic and/or immunotherapeutic strategies for ovarian carcinoma.     

Ultrastructural immuno-localization of tropoelastin in the chick eye

Summary Immuno-gold labeling at the electron-microscopy level was used to investigate the distribution of tropoelastin in the chick eye. Intense staining was found in the amorphous part of mature elastic fibers in different regions of the organ. In elaunin fibers, both the amorphous core and the surrounding microfibrils were clearly labeled. In addition, reactive sites were detected in the oxitalan fibers of the stroma of the cornea and in Descemet's membrane, which showed a gradient of reactive sites increasing from the center toward the periphery. Oxitalan fibers of the stroma often fused with Descemet's membrane; the pattern of immunological staining suggested a continuity between the two structures. In the ciliary zonule, labeling for tropoelastin was observed in discrete areas on the bundles of microfibrils. The results show a complex structural organization of elastic tissue; this may be important in endowing the various parts of the eye with different mechanical properties.     

Response to self-motion in waterstriders: visual discrimination between rotation and translation

Waterstriders (Gerris paludum) often try to maintain a nearly stationary position on a moving water surface. Passive motion is restricted to 3 degrees of freedom: yaw, longitudinal, and transverse displacement. They correct for passive rotation and translation by distinct behavioral sequences. The compensatory behavior is predominantly visually controlled.

Ultrastructural analysis ofErysiphe graminis haustoria and subcuticular stroma ofVenturia inaequalis using cryosubstitution

Summary Cryosubstitution provides an improved ultrastructural preservation of the two plant pathogensVenturia inaequalis andErysiphe graminis when compared to conventional preparation methods. Further, freezing the infected whole leaf material on a copper block cooled with liquid helium gave better results than those observed with the propane plunging method. Novel observations concerning the fungal stroma and haustoria were made which showed ribosomes organized into groups that were evenly distributed throughout the cytoplasm of both fungi. Stretches of rough endoplasmic reticulum were present, and microtubules were seen, sometimes associated with mitochondria. A large number of darkly staining vacuoles were observed in both fungi. The polarity of organelles and microtubules along the longitudinal axis of the haustorial body ofE. gramnis and along the growing direction of subcuticular stroma and runner hypha ofV. inaequalis was evident. InE. graminis filasomes were observed, as were Golgi-like bodies. These new observations, together with the advantages of the cryosubstitution technique, can serve as a basis for further studies in understanding host-parasite interactions.     

Trophic role of rotifers in the plankton of lake Kozjak (Plitvice Lakes)

The trophic role of rotifers in the zooplankton community of dimictic, oligotrophic lake Kozjak, the largest lake of the Plitvice Lakes, NW Dinarid Mountains, is analyzed. Their spatial and temporal biomass distribution in relation to that of protozoans, cladocerans and copepods shows that they form a significant part of the non-predatory zooplankton of this karstic standing water.     

The menotactic orientation of the prosobranch mollusc Littorina littorea

The menotactic orientation of the prosobranch mollusc Littorina littorea to a one stripe pattern (Fig. 2) has been investigated under open-loop and closed-loop conditions. Results: 1) Under open-loop conditions the animals try to compensate for an angular deviation of the pattern from the menotactic angular position by turning movements of, on the average, constant angular velocity (Fig. 4). 2) The angular velocity depends on this deviation according to the -characteristic (Fig. 5). The orientation behaviour under closed-loop conditions can be directly derived from the -characteristic. Within experimental limits the snail does not show an optomotor response. 3) To patterns of wedge-shaped intensity distribution the snails orientate at a small angle relative to the edge of the pattern (Fig. 3). The orientation angle of the animals to this pattern is much less variable than the orientation angle to a single light source. The orientation behaviour shows that the intensity gradient of the pattern is important for the orientation of the animal. 4) A normally distributed noise process is superimposed on the average orientation direction. The variance of this noise process is the same for the orientation under open-loop and under closed-loop conditions (Fig. 7). In both cases the power spectrum of the noise process contains pronounced maxima at equally spaced frequencies (Fig. 8).     

Cellulolytic enzymes for the hydrolysis of leached beet cosette

Summary Cellulolytic fungi were isolated from rotting leaves and tested for extra-cellular cellulase activities (CMCase, avicelase, cellobiase and xylanase). The effect of the proportion of the enzyme activities on the rate of degradation of leached beet cosette was observed using a range of supernatant fluids in appropriate combinations. At low cosette concentrations (1.5–3.0 g/l), avicelase and cellobiase were the rate limiting enzymes; avicelase in the initial stages of reaction and cellobiase after 6–8 hours, when cellobiose inhibition becomes important. A ratio of celiobiase to avicelase of approx 2.0 was established as appropriate. At higher substrate concentrations (10 g/l, 40 g/l) the best cellobiase to avicelase ratio was maintained and up to 40% hydrolysis was obtained in the 10 g/l incubation with 10 Uav/l and 20 Ucellob/l. At 100 g/l cosette concentration, substrate inhibition was observed.