DNA sequence organisation in relation to genome size in birds

Summary DNA sequence interspersion was investigated in pheasant and pelican nuclear DNA. As is typical for birds, these genomes are organized in a long period pattern. Altogether, 5 bird species with genome sizes between 1.6 and 1.9 pg DNA are compared with regard to the extent of repetitive and single copy sequence interspersion. The result indicates that the average length of interspersed repetitive sequences increases with genome size.Acknowledgment. This work was supported by the Deutsche Forschungsgemeinschaft. Mrs H. Tuczynski and Mr J. S. Jackson are thanked for editorial assistance.     

In vitro esterification of plant sterols by the esterifying enzyme of the small intestine of rat

The in vitro esterification of plant sterols, beta-sitosterol, campesterol and stigmasterol, by the esterifying enzyme of the small intestine of rat was studied in the presence of saturated and unsaturated fatty acids. Campesterol esterification was highest, followed by sitosterol and stigmasterol irrespective of the type of fatty acid. Both campesterol and sitosterol esterification was greater with unsaturated fatty acids than with saturated fatty acids.     

Effect of chronic hypo and hypervitaminosis C on the brush border enzymes and the intestinal uptake of glucose and alanine

Summary Brush border sucrase and alkaline phosphatase activities are considerably enhanced in the intestine of ascorbic acid deficient guinea-pigs. Similar increase in the uptake of D-glucose and L-alanine also occurs in chronic vitamin C deficiency. However the permeability of D-glucose and L-alanine in the intestine of animals fed with large doses of vitamin C is severely depressed, with a reduction in the levels of sucrase and alkaline phosphatase activities.     

Effects of precocene II and juvenile hormone III on the activity of neurosecretory A-cells inOncopeltus fasciatus

Summary Application of precocene II, topically or by contact method, appears to inhibit the synthetic activity of neurosecretory A-cells of the pars intercerebralis ofOncopeltus fasciatus. Treatment of precocene-treated insects with JH III apparently stimulates the secretory activity of these cells.Supported by National Research Council of Canada grant No. A4669.We thank Dr G. B. Staal, Zoecon Corporation, Palo Alto, California, for the gift of precocene II.     

Syntheses of amino acids from unsaturated aliphatic carboxylic acid by contact glow discharge electrolysis

Summary Hydroxy amino acids are synthesized from unsaturated aliphatic carboxylic acid using aqueous ammonia under conditions of contact glow discharge electrolysis.This work was supported partly by a grant from the Ministry of Education.     

Electrical activity of the pectoral muscles during gliding and flapping flight in the herring gull (Larus argentatus)

Summary Electromyographic recording from the pectoral muscles of the herring gull during flight showed that very little muscle activity is associated with gliding flight. However, the integrated gliding potentials could be increased very considerably by loading the bird. The muscle activity during gliding and flapping flight are in accordance with the known energy requirements for these 2 types of flight.This work was supported by NIH Research Grant HL-02228 and NIH Research Career Award 1-K6-GM-21, 522 to Prof. Schmidt-Nielsen. G. Goldspink was in receipt of a Science Research Council (UK) Research Grant.     

HCO 3 − -ATPase activity distribution in rat liver cell fractions prepared by zonal centrifugation

Summary Plasma membrane sheets prepared by zonal centrifugation of a premicrosomal pellet obtained from a rat liver homogenate are devoid of HCO ₃ ^– -ATPase activity. Since the microsomal fraction is also lacking in this ATPase activity, it can be concluded that the HCO ₃ ^– -ATPase is not involved in the secretion of HCO ₃ ^– into bile. Acknowledgments. This investigation was supported in part by grants No. DE-02600 and AM 80686 from the United States Public Health Service. The A-XII zonal rotor is used under subcontract No. 3796 with the Union Carbide Corporation.