NCAM: a surface marker for human small cell lung cancer cells

Immunocytochemical and immunochemical techniques were used to study the expression of the neural cell adhesion molecule (NCAM) by human lung cancer cell lines. Intense surface staining for NCAM was found at light and electron microscopic levels on small cell lung cancer cells. The NCAM polypeptide of Mr 140,000 (NCAM 140) was detected by immunoblotting in all of 7 small cell lung cancer cell lines examined and in one out of two of the closely related large cell cancer cell lines: it was not detected in cell lines obtained from one patient with a mesothelioma, in two cases of adenocarcinoma, nor in two cases of squamous cell cancer. In contrast, neuron-specific enolase was found by immunoblotting in all the lung cancer cell lines tested and synaptophysin in all but the adenocarcinoma cell lines. These antigens were localized intracellularly. The specific expression of NCAM 140 by human small and large cell lung carcinomas suggests its potential as a diagnostic marker.     

Aggregation and dispersity of isolated chromaffin granules studied by intensity fluctuation spectroscopy

The aggregation and dispersity of isolated bovine adrenal secretory vesicles (chromaffin granules) were studied by intensity fluctuation spectroscopy. The degree of dispersity and the Z-average translational diffusion coefficients were calculated from the autocorrelation functions of the intensity fluctuations in lase light scattered from the granules in solution. Granules purified by sedimentation through 0.3 M sucrose/Ficoll/²H₂O showed greater dispersity than granules purified by sedimentation through 1.6 M sucrose. By monitoring the scattered light intensity and the diffusion coefficients of the granules, many of the difficulties encountered in the interpretation of absorbance measurements were avoided. Measurements over a range of granule concentrations in sucrose solutions (10 mM HEPES, pH 7.0), indicated that aggregation of the granules occurred at concentrations above 150 μg protein/ml. At low granule concentrations (15–30 μg protein/ml) Ca²⁺-induced aggregation was detected at a threshold of 2–10 mM calcium.     

Purification and characterization of soluble forms of human and rat stem cell factor recombinantly expressed by Escherichia coli and by Chinese hamster ovary cells.

Stem cell factor (SCF) is a novel, early-acting hematopoietic factor. It was isolated from the medium of a rat cell line in a soluble, processed form (Zsebo et al., 1990, Cell 63, 195). The cloned human and rat genes encode the soluble form plus additional C-terminal amino acids including a hydrophobic transmembrane domain (Martin et al., 1990, Cell 63, 203). We have recombinantly expressed forms of human and rat SCF corresponding to the soluble, processed form in Escherichia coli and in Chinese hamster ovary (CHO) cells. After expression in E. coli, folding and oxidation of the SCF polypeptides are required. The SCFs expressed in CHO cells are secreted into the medium in active state and, like the natural SCF, are glycosylated. Purification of the recombinant SCFs is described. Biological and biochemical characterization includes activity toward responsive human and mouse cell lines, N-terminal amino acid sequences, disulfide bond linkages, and sites of glycosylation.     

Persistent courtship reduces male and female longevity in captive tsetse flies Glossina morsitans morsitans Westwood (Diptera: Glossinidae)

Where males can increase their mating success by harassing femalesuntil they accept copulation, harassing tactics can be expectedto evolve to a point where they have costs to the longevityof both sexes. By experimentally manipulating the sex ratioin captive groups of tsetse flies Glossina morsitans morsitans,we demonstrated that the longevity of females declines wheresex ratios are biased toward males, while the longevity of malesdeclines where the sex ratio is biased toward females. Neitherirradiation of males nor prevention of copulation by blockingor damaging the external male genitalia increased the longevityof females caged with them, suggesting that female longevitywas reduced by the physical aspects of male harassment ratherthan by components of the ejaculate     

Influence of diet composition on feeding and water excretion by the tsetse fly, Glossina morsitans

Adult Glossina morsitans fed on aqueous salt solutions containing phagostimulant ATP in an in vitro feeding system gave an optimal feeding response only over a narrow pH range equivalent to that of vertebrate blood. There was much less discrimination on the basis of molar concentration.The rate and extent of water excretion by the fly was found to depend on the concentration of Na⁺ ions in the food medium: an active transport mechanism is indicated which enables water to pass from the meal through the anterior midgut wall and into the haemocoele. A favourable osmotic gradient assisted water transport in the presence of Na⁺ ions: the system could not operate efficiently in the presence of Na⁺ ions if the osmotic pressure of the food medium was higher than that of vertebrate blood, nor could it operate efficiently in any solution lacking Na⁺ ions.Normal transfer of a meal from the crop to the anterior midgut occurred only when the food medium was isotonic with vertebrate blood or in the presence of Na⁺ ions if hypotonic. Normal transfer of isotonic solutions was prevented in the presence of excess K⁺ ions, and hypertonic solutions were not transferred normally even in the presence of Na⁺ ions. Thus the rate of water excretion was reduced.Tsetse flies fed on blood in an in vitro feeding system excreted water at a significantly lower rate than flies fed on a living animal. Evidence suggests that this is due to a combined effect of changes in viscosity, effective ionic composition, and osmotic pressure, upon the normal rate and extent of food uptake and manipulation of the meal prior to digestion. The implications of this are discussed in terms of future developments of in vitro feeding techniques for haematophagous insects.     

Dynamics of Newly Established Elk Populations

Abstract: The dynamics of newly established elk (Cervus elaphus) populations can provide insights about maximum sustainable rates of reproduction, survival, and increase. However, data used to estimate rates of increase typically have been limited to counts and rarely have included complementary estimates of vital rates. Complexities of population dynamics cannot be understood without considering population processes as well as population states. We estimated pregnancy rates, survival rates, age ratios, and sex ratios for reintroduced elk at Theodore Roosevelt National Park, North Dakota, USA; combined vital rates in a population projection model; and compared model projections with observed elk numbers and population ratios. Pregnancy rates in January (early in the second trimester of pregnancy) averaged 54.1% (SE = 5.4%) for subadults and 91.0% (SE = 1.7%) for adults, and 91.6% of pregnancies resulted in recruitment at 8 months. Annual survival rates of adult females averaged 0.96 (95% CI = 0.94-0.98) with hunting included and 0.99 (95% CI = 0.97-0.99) with hunting excluded from calculations. Our fitted model explained 99.8% of past variation in population estimates and represents a useful new tool for short-term management planning. Although we found no evidence of temporal variation in vital rates, variation in population composition caused substantial variation in projected rates of increase (Λ = 1.20-1.36). Restoring documented hunter harvests and removals of elk by the National Park Service led to a potential rate of Λ = 1.26. Greater rates of increase substantiated elsewhere were within the expected range of chance variation, given our model and estimates of vital rates. Rates of increase realized by small elk populations are too variable to support inferences about habitat quality or density dependence.