Further data on Prokennalestes (Mammalia, Eutheria inc. sed.) from the Early Cretaceous of Mongolia

Four new incomplete lower jaws of Prokennalestes are described. bringing new data for establishing the primitive cutherian dental formula and its evolution in later placentals, as well as the possible relationships of the genus.     

A comparison of the correcting behaviour exhibited by two milkweed bugs, Oncopeltus fasciatus and Lygaeus kalmii

ABSTRACT. Adults and nymphs of two species of milkweed bugs, Oncopeltus fasciatus and Lygaeus kalmii , were studied with respect to their optomotor responses, as exhibited by the laboratory phenomenon of correcting behaviour on mazes. It was found that the O.fasciatus nymphs failed to correct while the other three groups all exhibited correcting behaviour. The differences in correcting behaviour were attributed to differences in such ecological variables as degree of socialness, nature of food source, and foraging strategies.     

Gradients in the Nitrogenous Constituents of the Sap extracted from Apple Shoots of Different Ages

A comparison was made of the nitrogenous constituents in thesap extracted under vacuum from apple shoots of different ages,as regards changes both with season and in response to fertilizernitrate applied in summer or autumn. Before blossoming the N concentration of the sap changed markedlywith age of shoot, with the values doubling in the samples fromthe proximal half of the 3-year-old wood to the distal 2-year-oldsection, followed by a significant decrease in the 1-year-oldshoot. After blossoming the gradients in sap concentration wereless pronounced but usually the lowest values were found inthe youngest part of the shoot. Fourteen days after a soil application of nitrate in July therewas a marked increase in the concentration of asparagine inthe sap, but only in the 3-year-old section of the shoot. Sevendays later the xylem sap from all parts of the shoot containedincreased levels of asparagine, aspartic acid, and glutamine. No changes in the xylem sap of shoots in response to fertilizerapplied in October were observed until the following April.Then increased amounts of asparagine and glutamine were foundin all sections, with the greatest increase being seen in theyoungest part. It is suggested that this was due to acceleratedmobilization of N reserves into the xylem sap in response togrowth regulators originating in the roots rather than to movementof recently absorbed nutrients.     

Modulation of Biological Functions of Naegleria fowleri Amoebae by Growth Medium

Two strains of Naegleria fowleri amoebae were studied when the amoebae were maintained in the same growth medium or in two different media. A weakly pathogenic strain of N. fowleri , LEE, and a highly pathogenic strain, LEEmpCl, were compared for growth properties, the presence or absence of surface structures termed food cups, cytopathogenicity, cellular locomotion, susceptibility to complement-mediated lysis and immunological relatedness by western immunoblot analysis when grown in Nelson medium or in Cline medium. The two different strains of N. fowleri , LEE and LEEmpCl, were more similar in protein profiles and functional activity when both strains were grown in the same nutritional medium. Differences in growth, proteins synthesized, cytopathogenicity, susceptibility to complement lysis and rate of locomotion were noted when the same strain was grown in different media. Naegleria fowleri grown in Cline medium demonstrated an increased rate of growth, an increase in its rate of locomotion, an increased resistance to complement lysis, and destroyed target nerve cells by contact-dependent lysis. In contrast, the same strain of amoeba grown in Nelson medium showed slower growth, destroyed target cells by trogocytosis, and was less resistant to complement-mediated lysis.