Cystic fibrosis typing with DNA probes: experience of a screening laboratory

Summary A sample of 125 individuals from 37 British cystic fibrosis (CF) families with at least one living affected child were typed with probes for restriction fragment length polymorphisms (RFLPs) known to be linked to the CF gene. These probes were MetD, MetH, pJ3.11 and 7C22. Using this combination of probes, 30 out of the 37 families were sufficiently informative to enable prenatal diagnosis of the disease. Linkage analysis has also proved to be useful in excluding CF in two cases where diagnosis of the disease was equivocal in the sibling of an affected child.     

Oat Bran as a Cholesterol-Reducing Dietary Adjunct in a Young,Healthy Population

In a study to examine the effects of dietary oat bran on serum lipids, subjects who ate two oat bran muffins a day for 28 days showed a 5.3% reduction in serum total cholesterol and an 8.7% reduction in low-density-lipoprotein-cholesterol levels, while no changes were noted in subjects consuming wheat or mixed wheat and oat bran muffins. Similarly, those who ingested oat bran muffins showed an 8.3% reduction in serum triglyceride values as contrasted with an overall increase of 6.4% in the other groups combined. These findings suggest that oat bran taken daily can significantly lower serum cholesterol and triglyceride levels in a young, healthy population.     

Utilization of the Synthetic Phosphagen Cyclocreatine Phosphate by a Simple Brain Model During Stimulation by Neuroexcitatory Amino Acids

The ability of 1-carboxymethyl-2-imino-3-phosphonoimidazolidine (cyclocreatine-P), accumulated by a simple brain model, to function as a supplemental synthetic phosphagen and respond to the decreases in cytosolic ATP/free ADP ratios that occur during prolonged stimulation by various excitatory amino acids was investigated. Suspensions of chopped whole brain from 11- to 14-day-old chick embryos were incubated with 30 mM cyclocreatine for 90 min, resulting in accumulation of 100 mumol/g dry weight of cyclocreatine-P, and then incubated for up to 1 h with a series of excitatory amino acids of widely differing potencies. Under these conditions net utilization of cyclocreatine-P was detected in response to stimulation by the following neuroexcitatory compounds at the indicated threshold concentrations: kainate (20 microM), N-methyl-DL-aspartate (20 microM), L-homocysteate (20 microM), L-glutamate (200 microM), D-glutamate (200 microM), L-aspartate (2 mM), DL-2-amino-3-phosphonopropionate (2 mM), and DL-2-amino-4-phosphonobutyrate (2 mM). Significant increases in water content of chick embryo brain minces accompanied stimulation by excitatory amino acids. It is suggested that changes in water content or cyclocreatine-P levels in this sensitive brain model might be utilized in automatable screening procedures for detecting novel antagonists and/or new agonists of excitatory amino acids.     

Oxidative Damage to DNA and Deoxyribose by β-Lactam Antibiotics in the Presence of Iron and Copper Salts

β-lactam antibiotics in the presence of certain metal ions damage deoxyribose and DNA with the release of thiobarbituric acid-reactive material. This damage can be substantially prevented by catalase, metal chelators and some scavengers of the hydroxyl radical. Ferric salts in the presence of certain β-lactam antibiotics were effective in degrading deoxyribose but they did not appear to damage DNA. In contrast copper salts and p-lactam antibiotics were extremely effective in damaging both DNA and deoxyribose.     

Effects of exercise training and diabetes on cardiac myosin heavy chain composition

This study determined whether the beneficial effects of exercise training on the diabetic heart previously observed are associated with alterations in ventricular myosin heavy chain (MHC) isoform composition. Diabetes was induced in rats by i.v. streptozotocin. Trained rats were run on a treadmill for 60 min/day, 27 m/min, 10% grade. After 10 wks, ventricular MHC isoenzyme protein composition was analyzed for MHC composition using gel electrophoresis. -MHC and -MHC mRNA were determined by Northern and slot blot hybridization techniques. Both protein and mRNA analyses indicated that sedentary control rats exhibited a predominance of -MHC. Sedentary diabetics exhibited a shift to -MHC. Exercise trained diabetic rats showed a predominance of -MHC. The results indicate that treadmill exercise training of diabetic rat does not prevent the diabetes-induced shift in MHC composition towards the -MHC isoform, thus it is unlikely that the beneficial effects of exercise training on the diabetic heart, previously shown, are due to a normalization of the myosin isoform composition.     

Oxidation of exogenous carbohydrate during prolonged exercise: the effects of the carbohydrate type and its concentration.

We studied rates of exogenous carbohydrate (CHO) oxidation during 90 min of cycling exercise in trained cyclists exercising at 70% of maximal oxygen consumption (VO2max) when they ingested glucose, sucrose, or glucose polymer solutions at concentrations of 7.5%, 10% or 15%. Drinks were labelled with [U-14C]glucose or sucrose and were ingested at a rate of 100 ml.10 min-1. Rates of oxidation of the ingested CHO were calculated from the specific radio-activity of the labelled CHO, expired 14CO2 and carbon dioxide output (VCO2). Total CHO oxidation, determined from oxygen consumption and VCO2 was not influenced by CHO type or concentration. Gastric emptying (P = 0.01) and the rate of exogenous CHO oxidation (P = 0.028) was greatest for the glucose polymer solutions, and least for glucose. Although gastric emptying (P = 0.006) decreased with increasing CHO concentration, CHO delivery to the intestine and exogenous CHO oxidation increased linearly with increasing CHO concentration. The percentage of the CHO delivered to the intestine that was oxidized ranged from 30.0% for 7.5% CHO to 38.1% for 15% CHO. Our results indicated that the rate of gastric emptying for CHO was not controlled to provide a constant rate of energy delivery as is commonly believed and that factors subsequent to gastric emptying limit the rate of exogenous CHO oxidation from the ingested solution.     

Primer protein of bacteriophage M2 exposes the RGD receptor site upon linking the first deoxynucleotide

Summary Using electroporation with the phage PRD1 genome, we set up a high-frequency DNA transfer system for a linear dsDNA molecule with 5-covalently linked terminal proteins. The transfer was saturated when more than 100 ng of PRD1 genome was used. Electroporation efficiency was about four orders of magnitude higher than that obtained with transfection. Removal of the terminal protein abolished plaque formation, which could not be rescued by supplying the terminal protein or phage DNA polymerase or both in trans.     

The influence of snow on lynx and coyote movements: does morphology affect behavior?

Summary We studied sympatric lynx (Lynx canadensis) and coyotes (Canis latrans) to assess how morphological disadvantages to locomotion over snow affected movement patterns. Both species are of similar size and mass, but the feet of lynx are much larger, and coyotes were found to have 4.1–8.8 times the foot-load (ratio of body mass to foot area) of lynx. This resulted in greater mean sinking depths of coyote limbs, although the magnitude of the difference was less than that in foot-load. Coyotes exhibited stronger use of behavioral patterns that reduced negative effects of snow on movements. Coyotes were most abundant at low elevations where snow was shallow, whereas lynx were mostly at higher elevations. Coyotes also used areas at both elevations where snow was shallower than average, while lynx used areas where snow was deeper. further, both species used travel routes where snow was shallower than it was near the track. Coyotes traveled on harder snow and used trails more frequently, thereby tending to reduce sinking depths to those similar to lynx. The behavioral repertoire of coyotes reduced the morphological advantage of large feet possessed by lynx; however, overall sinking depths were still greater in coyotes. Snowshoe hares (Lepus americanus) were the main prey of both species, and their foot-load was less than that of either predator. Hare kills by coyotes occurred after fewer bounds than did those by lynx, and the large difference between foot-loads of both species of predators may have forced coyotes to ambush rather than chase hares, as did lynx.     

Artificial Induction and Evaluation of a Mild Isolate of Tomato Spotted Wilt Virus

A severe isolate (BL) of tomato spotted wilt virus (TSWV) that originated from Hawaii was treated with nitrous acid in an effort to obtain mild mutants. The standardized procedure used in mutation experiments was: extracting infected Gomphrena globosa L. leaf tissue in 0.01 M Na₂SO₃, 0.125 M sodium acetate and 0.4 M sodium nitrite at pH 5.5 and incubating the extract for 20 min at room temperature. The extract was inoculated to tobacco (Nicotiana tabacum L. cv. Havana 423) and local lesions were subsequently transferred to lettuce (Lactuca sativa L. cv. Minetto). One isolate (R27G) that incited mild symptoms in lettuce was obtained out of 868 local-lesion-transfers. Under greenhouse conditions, the isolate induced mild symptoms on tomato (Lycopersicon esculentum Mill.) but was severe on peppers (Capsicum annuum L.). The effect of the R27G isolate on growth of potted tomatoes kept outdoors was variable. In one trial, only 15 % of the fruit had symptoms versus 67 % in another trial. R27G fully protected Datura stramonium L. plants that were challenge inoculated with the severe parent BL isolate. Less effective cross protection was observed against a severe isolate from Oklahoma.     

Mouse Chromosome 13

Chair of Committee for Mouse Chromosome 13