The Small Mammals of the Mackenzie Delta Region, Northwest Territories, Canada

The paper reports on 3800 small mammals taken in taiga and tundra east of the Mackenzie River Delta between 1971 and 1974. Local distributions are given for all 100 species of small mammals recorded in the region, plus two accidentals. In addition, abundance, body and cranial measurements, and reproductive information is presented for the 8 species collected during the study. The taxonomic status of Clethrionomys rutilus platycephalus is discussed

Distribution, activity and range use of male caribou in early summer in Northern Yukon, Canada

Males of the Porcupine Caribou Herd separated from females from the onset of spring migration until they joined them on the calving grounds in late June or early July, 4-6 weeks later. From late May to late June males spent an average of 50% of their time feeding and less than 2% standing and trotting/running. Males spent an average of 29% of their time lying and 19% walking, except in mid-June (40% lying, 6% walking). The average lengths of active and resting periods were 112 minutes and 104 minutes, respectively, from late May to mid-June, but decreased sharply in late June to 78 minutes and 69 minutes, respectively. Tussock meadows were selected in late May and early June, wet sedge meadows were avoided until late June, dwarf shrub heaths were avoided after late May, and alluvial willow thickets were avoided in late May and early June but were selected in mid-June and late June. Caribou fed primarily on lichens and Vaccinium in late May, lichens and Eriophorum in early June, Eriophorum in mid-June and Salix in late June

Dual-specificity MAP kinase phosphatases in health and disease

Source at https://doi.org/10.1016/j.bbamcr.2018.09.002.It is well established that a family of dual-specificity MAP kinase phosphatases (MKPs) play key roles in the regulated dephosphorylation and inactivation of MAP kinase isoforms in mammalian cells and tissues. MKPs provide a mechanism of spatiotemporal feedback control of these key signalling pathways, but can also mediate crosstalk between distinct MAP kinase cascades and facilitate interactions between MAP kinase pathways and other key signalling modules. As our knowledge of the regulation, substrate specificity and catalytic mechanisms of MKPs has matured, more recent work using genetic models has revealed key physiological functions for MKPs and also uncovered potentially important roles in regulating the pathophysiological outcome of signalling with relevance to human diseases. These include cancer, diabetes, inflammatory and neurodegenerative disorders. It is hoped that this understanding will reveal novel therapeutic targets and biomarkers for disease, thus contributing to more effective diagnosis and treatment for these debilitating and often fatal conditions

Schiff Bases of Pyridoxal 5\u27-phosphate and 5\u27-deoxypyridoxal with Phenylglycine Derivatives and Their Metal Complexes

Potentiometric p[H] measurements are employed to evaluate protonation constants, metal complex stabilities, and Schiff base (SB) formation constants in solutions containing pyridoxal 5\u27-phosphate (PLP) 5\u27-deoxypyridoxal (DPL), phenylglycine and its derivatives, and divalent transition-metal ions at 25°C and at an ionic strength of 0.100M (KNO3). Protonation constants for phenylglycine (PG), (4-methoxyphenyl)glycine (MPG), and (4-sulfophenyl)glycine (SPG) indicate that these synthetic amino acids are more acidic than glycine and other natural amino acids. Stability constants are reported for 1:1 and 1:2 complexes of Mn2+, Co2+, Ni2+, Cu2+ and Zn2+ with PG, MPG, and SPG. Hydrolysis of these metal ions complicates the study of the nature of the metal complex formed at high p[H]. The vitamin B6 derivatives, pyridoxal 5\u27-phosphate and 5\u27-deoxypyridoxal, were found to form only 1:1 metal complexes. The equilibrium constants for the formation of Schiff bases by PLP and DPL with PG, MPG and SPG are reported. The monoprotonated form of the Schiff base was found to be the most stable species in each of the systems studied. The equilibrium constants are reported for protonated 1:1 Cu(II)-Schiff base complexes, CuSBHxn+ and for 1:1 and 2:1 Schiff base complexes of Mn(II), Co(II), Ni(II), and Zn(II). The formation of a number of hydroxometal Schiff base chelates in alkaline solutions is observed. The equilibrium constants determined are employed to calculate the distribution of complex species as a function of p[H] in solutions containing these ligands and the metal ions identified above

Oxidative Deamination of Amino Acids by Molecular Oxygen with Pyridoxal Derivatives and Metal Ions as Catalysts

The oxidative deamination of (p-sulfophenyl)glycine by Cu2+ and vitamin B6 coenzymes pyridoxal 5\u27-phosphate or 5\u27-deoxypyridoxal to give (p-sulfophenyl)glyoxylic acid is described. The reaction conditions for kinetic measurements and catalysis were selected on the basis of previous equilibrium measurements of complex species present in these reaction systems. The reaction occurs in two modes, stoichiometric and catalytic. The stoichiometric route involves the reaction of the amino acid Schiff base of pyridoxal 5\u27-phosphate or 5\u27-deoxypyridoxal to form the oxime of the coenzyme and the keto acid. The stoichiometric reactions, which occur moderately rapidly at room temperature in aqueous solution, become part of an overall catalytic system in which the amino acid and dioxygen are converted to keto acid and ammonia in the presence of low concentrations of coenzyme and metal ion. Spectrophotometric studies demonstrate the relatively rapid conversion of the Schiff base metal chelate to the oxime complex, which is slowly converted to additional Schiff base complex by reaction with additional amino acid. Hydroxylamine, which is presumably formed in the displacement reaction, is converted to ammonia under the reaction conditions employed. The concentration of the intermediate oxime complex remains relatively constant when the reaction is run in the catalytic mode. Conversion to the final products was followed by isolation of the ammonia and keto acid formed, and by the quantitative estimation of ammonia. A dioxygen-18 tracer study demonstrated that dioxygen is the source of the oxime oxygen, while the oxygen of the keto acid comes from the solvent. Mechanisms previously proposed for Vitamin B6 and metal ion catalyzed amino acid oxidation are discussed, and a selection is made on the basis of 18O2 labeling of the hydroxylation product

Oxidative Deamination of Amino Acids by Molecular Oxygen with Pyridoxal Phosphate and Cu(II) Ion as Catalysts

This paper reports the quantitative oxidation by molecular oxygen of the Cu(II) chelate of the Schiff base formed from vitamin B6 (pyridoxal phosphate, PLP) and p-sulfophenylglycine to the keto acid, p-sulfophenyl-glyoxylic acid, and the Cu(II) chelate of PLP oxime. In the presence of excess amino acid the Cu(II) chelate of the oxime becomes an intermediate in the oxidative deamination of the amino acid to the corresponding keto acid and ammonia, with Cu(II) and PLP as catalysts