Two-dimensional gel studies of genetic variation in the plasma proteins of Amerindians and Japanese

Summary Genetic variation has been studied in plasma samples from 107 Amerindian children and their parents, and 110 Japanese children and their parents by means of two-dimensional polyacrylamide gel electrophoresis. Twenty-three polypeptides were scored; the identity of nine of these is at present still unknown. Genetic variation was encountered in 11 of these polypeptides. We have previously reported that the index of heterozygosity was 6.2±0.7% for 20 randomly selected, silver stained polypeptides scored for genetic variation in Caucasoids (Rosenblum et al. 1983b). For technical reasons only 11 of these 20 polypeptides could be routinely scored in preparations from the Amerindian samples. For these 11 polypeptides, the indices of heterozygosity in the three populations were: Amerindians, 4.5±0.6%; Japanese, 5.7±0.7%; Caucasoids, 8.0±1.1%. Even with these relatively small numbers some striking ethnic differences as regards individual polypeptides are apparent.     

Fluorescent inhibitors of a cell surface protease used to locate leukaemia cells in kidney sections

Guanidinobenzoatase is a trypsin-like protease on the surface of cells capable of migration, for example leukaemia cells. We have used a number of fluorescent probes that are competitive inhibitors of guanidinobenzoatase to locate leukaemia cells in resin sections of kidney tissue obtained from leukaemic rats. We have demonstrated how this competitive inhibition system can be used to direct desired molecules (such as cytotoxic drugs) to these cells and to monitor the arrival of such compounds at the active site of guanidinobenzoatase. The principles developed in this study could equally well be applied to other enzymes on other cells provided suitable competitive inhibitors were designed. The presence of an enzyme on the surface of a cell can be used to direct molecules to that cell provided that these molecules contain a functional group that acts as an inhibitor for the chosen enzyme.     

Interaction of genotype and parental environment in the adaptation of wild House mice Mus musculus to cold

Wild House mice, Mus musculus, were bred in two laboratory environments, one warm (controls) and one cold (Eskimo). At the seventh generation, mice of both stocks were cross-fostered at birth in both environments. In the warm environment, differences in both genotype and nest environment influenced growth: (1) Eskimo reared by Eskimo females were the heaviest of the four classes of fostered young; and (2) control foster parentage retarded growth. There was, however, no good evidence of differences in the reproductive performance of the four classes of fostered mice. In the cold environment, the effects of both genetical differences and of fostering were greater. Both the superior growth of Eskimo reared by Eskimo and the retarding effect of control foster parentage were more marked. Moreover, adult males with control foster parents had less fat than had those with Eskimo foster parents. Reproductive performance was also affected: (1) the young of the pairs with Eskimo genotype were heavier than the young of control pairs; (2) the litters of mice with Eskimo foster parents were larger than those of mice with control foster parents, and their young were heavier. Differences among the young of fostered mice represent a grandmother effect. Evidently, selection in a cold environment had led, not only to adaptive genetical changes in the ability to respond directly to cold, but also to changes in parental performance; and the latter enhanced the fitness, in the cold environment, of their offspring and grandoffspring.     

Influence of malnutrition and alterations in dietary protein on murine rotaviral disease

The possible correlation between malnutrition and degree of severity of rotavirus-associated infantile diarrhea which appears to occur in human populations was studied using a mouse model. To determine the effects of general malnutrition or altered levels of dietary protein, female mice were fed throughout pregnancy and infection periods with diets diluted with 0, 300, or 600 g glucose/kg, designated as normal nutrient to calorie ratio (N/C) diet, 70% N/C diet, or 40% N/C diet or with diets containing 75, 150, or 300 g casein/kg, as low-, normal-, or high-protein diets. Murine rotavirus was given by gavage to the 2-day-old offspring of these dams, and the extent of infection determined. Marked increases in severity of diarrheal disease were seen in the infants from dams receiving the 40 and 70% N/C diets and the low-protein diet. Severity of infection was seen as increased deaths, reduced weight gain, and increased passage of diarrheic feces. Intestinal viral levels and intestinal diarrhea scores did not vary appreciably. Serum interferon remained below detectable limits throughout the studies, but serum antibody was determined in dams 30 days post-virus exposure. The latter titers were lower in the infected mice from dams fed the 40 and 70% N/C diets, but were essentially the same in all the protein diet groups. Cross-fostering was done using the 40 and 100% N/C diets, wherein mice from dams fed either diet were placed on mothers fed the opposite diet. Increased severity of infection was again seen when the virus was given 2 days after the exchange, although the greatest infection occurred in animals from dams fed 40% N/C diet which were then fostered by other similarly fed dams. The increased host sensitivity to the rotaviral infection appeared to be a result of both pre- and postnatal dietary effects.     

Decreased Fc receptor avidity and degradative function of monocytes from patients with systemic lupus erythematosus

We studied the binding and degradation of stable, soluble heat aggregates of 125I-IgG (A-IgG) by monocytes from 30 patients with systemic lupus erythematosus (SLE) and 30 normals. Relative avidities (KE) for Fc receptor (FcR) binding of A-IgG and maximal binding of A-IgG by monocytes were determined from Scatchard plots of binding data obtained at 4 degrees C. Rates of degradation (Vmax) of A-IgG at 37 degrees C were calculated from Lineweaver-Burke plots of the Michaelis-Menton equation. KE were decreased in SLE monocytes (15.5 X 10(-9) L/M) as compared with normals (20.1 X 10(-9) L/M, p less than 0.005) and Vmax were decreased for SLE (0.89 ng/hr) as compared with normals (1.11 ng/hr, p less than 0.005). The maximal FcR binding by SLE monocytes was not statistically different in SLE patients and normals, but monocytes from SLE patients with active disease showed a lower maximal binding capacity for A-IgG (4.9 ng/10(5) cells) than normals (5.4 ng/10(5) cells, p less than 0.05). KE and Vmax in SLE were also lower for patients with active disease than for normal subjects. KE in patients whose anti-ssDNA binding was greater than 20% were lower than for those with DNA binding of less than 20% (p less than 0.005). These data suggest that patients with active SLE have diminished numbers of available FcR on their circulating monocytes, possibly due to interiorization of FcR during endocytosis of endogenous circulating immune complexes.     

Structural requirements for active intestinal transport. Spatial and bonding requirements at C-3 of the sugar

Analogues of d-glucose modified at C-3, and in some cases at a second position, were prepared and tested for active accumulation by everted segments of hamster intestine. Their relative affinity for the sugar carrier was measured by tissue/medium ratio, Michaelis-Menten kinetics and competitive inhibition of d-galactose or methyl alpha-d-glucoside transport. d-Glucose and its 3-deoxy-3-fluoro, 3-chloro-3-deoxy and to a smaller extent its 3-bromo-3-deoxy derivatives, bound and were transported more strongly than 3-deoxy-d-glucose and other sugars not containing an electronegative atom in the gluco configuration at C-3. 3-Deoxy-d-galactose, 3,6-dideoxy-d-glucose and d-gulose, which have two alterations from the d-glucose structure, were not, or only very weakly, transported. The results are interpreted as indicating the presence of a hydrogen bond from the carrier to the hydroxyl group at C-3 of d-glucose. Spatial requirements are also discussed. New syntheses are reported for 3-chloro-3-deoxy- and 3-bromo-3-deoxy-d-glucose and 3,6-dideoxy-d-glucose.