Sleep time following anesthesia in mouse lines selected for resistance or susceptibility to fescue toxicosis

In previous work, a mouse line selected for resistance (R) to fescue toxicosis had higher activities of two hepatic Phase II detoxification enzymes than a mouse line selected for fescue toxicosis susceptibility (S). The primary objective of the present study was to determine whether those same lines also differed in hepatic Phase I enzyme activity, estimated from sleep time (ST) following sodium pentobarbital anesthesia. Additional objectives were to determine whether ST differences between lines were modulated by endophyte-infected fescue in the diet (with or without an enzyme inducer) and whether ST of individual mice was correlated with the effect of a toxin-containing diet on the postweaning growth of those mice. In Exp. I, 24 males from each line were randomly assigned to each of five diets: control (commercial rodent food meal); E+ (50% endophyte-infected fescue seed, 50% control); E+P (the E+ diet supplemented with 1,000 ppm phenobarbital); E- (50% endophyte-free fescue seed, 50% control); and E-P (the E- diet supplemented with 1,000 ppm phenobarbital). After 4 wk on these diets, ST was measured on all the mice. A second ST was recorded on each mouse by randomly sampling one-fourth of the population after 1, 2, 3, or 4 wk on a pelleted rodent food diet. Regardless of diet, R mice had shorter first and second ST than S mice (P < 0.01), suggesting higher hepatic Phase I microsomal enzyme activity. Mice on both phenobarbital-supplemented diets had shorter first ST than mice whose diets did not include that microsomal enzyme inducer (P < 0.01). In Exp. II, ST was measured on male and female R and S mice (n = 280) after they had been fed the E- diet for 2 wk, then the E+ diet for 2 wk, and then a pelleted rodent food diet for 2 wk. Growth response to the E+ diet was the percentage of reduction in gain on the E+ diet compared to gain on the E- diet the previous 2 wk. As in Exp. I, S mice slept longer than R mice (P < 0.01). The residual correlation between ST and gain reduction associated with the E+ diet equaled 0.04. Thus, an animal's apparent Phase I enzyme activity did not predict its growth rate depression on the toxin-containing diet. Based on these and previous studies, divergent selection for toxicosis response in mice was successful partially by causing divergence in activities of hepatic Phase I and II detoxification enzymes.     

Wie werden Wachstumsparameter von Gehölzen auf unterschiedlichen Standorten durch das Verschulen beeinflusst?

The influence of transplanting on height, root neck diameter, and grading was investigated for Carpinus betulus, Quercus robur, and Euonymus europaeus on three sites with different climate and soil properties. Additionally, plant growth was characterized by the shoot-to-root ratio, height-to-root neck diameter, and proportions of coarse and fine roots. The significance of the growth parameters as criteria for survival is discussed. Transplanting influenced shoot growth more than root growth. The growth of the plants was highly site-dependent. Transplanting increased growth most on the site with the best conditions for water and N supply. Transplanting had no effect on grading for the site with the worst water supply.     

Changes in abundance and infectivity of powdery mildew conidia from cucumber plants treated systemically with lithium chloride

Systemic treatment of cucumber plants with lithium chloride reduced the numbers of conidia produced by colonies of powdery mildew, Sphaerotheca fuliginea , growing on leaves, and lowered the infectivity of conidia produced from those leaves when they were applied to leaves of untreated plants. Production of conidiophores was lower in both lithium-treated and calcium-deprived plants, and lithium slightly decreased the calcium content of leaves. When the lithium-containing growth medium was supplemented with phosphate, conidiophore production was still markedly reduced, although leaves had normal levels of calcium. Fungal development was not correlated with either the calcium or phosphorus content of leaves. It is concluded that, although severe calcium deficiency can inhibit fungal development, the inhibitory effects of lithium are not mediated through alterations in calcium or phosphorus uptake by host tissues.     

Plant-parasitic nematodes of Croatia1

Investigations on the distribution of nematodes were carried out mostly in the northern and eastern parts of Croatia up to 1991. Sampling was performed in the following crops: maize, wheat, barley, sugarbeet, soybean, sunflower, rape, tobacco, potato, alfalfa, blackberry, onion, carrot, cucumber, lettuce, tomato, capsicum, oak, chrysanthemum, tulip, rose, grapevine, peach, apple, plum, pear, cherry, poplar, willow, clover, nettle, grass, meadow, woodland, many species of weeds, various glasshouse crops and vegetation in a nature reserve. 63 genera of nematodes with 81 species were detected. The most numerous representatives of plant parasitic nematodes were: Anguina, Aphelenchoides, Aphelenchus, Criconemoides, Ditylenchus, Gracilacus, Helicotylenchus, Hemicycliophora, Heterodera, Longidorus, Macroposthonia, Meloidogyne, Paratylenchus, Pratylenchus, Rotylenchulus, Rotylenchus, Trichodorus, Tylenchorhynchus, Tylenchus and Xiphinema.     

Revised methodology for a blood-clotting response test for identification of warfarin-resistant Norway rats (Rattus norvegicus)

A blood-clotting response test for warfarin resistance in Norway rats ( Rattus norvegicus ) was developed by our laboratory in the late 1970s, based on knowledge of biochemical mechanisms available at that time. That test used warfarin, its the free base which is not watersoluble, and vitamin K₁ 2,3-epoxide as an antidote for warfarin-resistant rats only. We have modified the above test to use a water-soluble salt of vitamin K₃ (1 mg kgg⁻¹ body weight), which is an antidote in a wider range of warfarin-resistant rat strains than vitamin K₁ 2,3- epoxide, and a water-soluble salt of warfarin (5.4 mg kg⁻¹ body weight). Sodium warfarin and vitamin K₃ are administered by oral gavage, and the blood-clotting response measured 24 h later. In a series of validation tests there were no significant differences between results obtained by either method. The new method, however, uses materials which are commercially available, and eliminates the possibility of misclassifying warfarin-resistant rats as susceptible because vitamin K₁ 2,3-epoxide was not an antidote in those strains. We also present evidence that measuring blood-clotting response to feeding on a vitamin K-free diet for 4 days is not a reliable method for determining the genotype of warfarin-resistant rats.     

Soybean yield and yield components as influenced by canopy heights and duration of competition of velvetleaf (Abutilon theophrasti Medik.)*

Soybean yields, pod and branch numbers were inversely related to the height of velvetleaf (Abutilon theophrasti). This effect was attributed to increasing interception of light with increasing height of A. theophrasti. Reduction; in soybean yield and yield components were greater if A. theophrasti was maintained at various heights for only 3 weeks rather than 6 weeks following soybean emergence. This effect was attributed to a longer duration of light competition by the weed. Even when the A. theophrasti canopy was kept 25% below that of soybean for 4 weeks, soybean yields, pod and branch numbers decreased when the weed was allowed to regrow during the remainder of the season, but not if the weed was removed after the initial 4-week clipping period. No reduction in seed yields, pod and branch numbers was noted if A. theophrasti plants 25% shorter than soybeans were removed or allowed to resume growth after the initial 6 or 8 weeks of clipping. Soybean seed size was slightly affected by A. theophrasti canopy height and duration of competition.