Food of larval tui chubs, Gila bicolor, in Pyramid Lake, Nevada

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Predation of artificial Sage Grouse nests in treated and untreated sagebrush

We measured predation on 120 artificial Sage Grouse ( Centrarcus urophasianus ) nests in montane sagebrush grassland in northern Utah. We examined nests in areas that had been chained and seeded 25 years previously (treated areas) and in areas that were untreated. Predation rates of artificial nests were higher in areas of untreated sagebrush, even though these areas had greater sagebrush cover, taller shrubs, and greater horizontal plant cover. These results differ from those previously hypothesized for treated sagebrush habitat and may reflect a greater abundance of other potential prey species, especially lagomorphs, in untreated areas that attracted greater densities of predators. In addition, over 80% of nests were depredated by mammals, which hunt using olfaction and are less likely than avian predators to be affected by nest cover. We conclude that, after treated sagebrush has recovered to some degree, predation rates of Sage Grouse nests may be lower in treated sagebrush. Consequently, factors other than nest predation (e.g., winter food, thermal cover, insects, perennial forb abundance) may be more important reasons for preserving mature sagebrush stands for Sage Grouse.     

New species of Astragalus (Leguminosae) from Mesa County, Colorado

Named and described is Astragalus debequaeus Welsh from Mesa County, Colorado.         

New American bark beetles (Coleoptera: Scolytidae), with two recently introduced species

Species named as new to science include: Conophthorus michoacanae, C. teocotum, Hylesinus aztecus (Mexico), Phloeocleptus punctatus (Costa Rica), Pseudothysanoes atomus (Venezuela), P. leechi (California), Pityogenes mexicanus, Araptus speciosus, Amphicranus spectus (Mexico), and Xyleborus praestans (Panama). Also reported are the first records of the notorious Xylosandrus compactus (Eichhoff) from South America (Brazil), and the first American records of Xyleborus fornicatus Eichhoff (Panama) and X. validus Eichhoff (New York and Pennsylvania).     

乘法扰动下广义极分解的扰动恒等式

设A是m×n(m≥n)且秩为r的复矩阵.存在m×n次酉矩阵Q和n×n半正定矩阵H使得A=QH,此分解称为A的广义极分解.运用奇异值分解,给出了乘法扰动下,矩阵的广义极分解在任意酉不变范数下的扰动恒等式.     

New insights into copper monooxygenases and peptide amidation: structure, mechanism and function

Many bioactive peptides must be amidated at their carboxy terminus to exhibit full activity. Surprisingly, the amides are not generated by a transamidation reaction. Instead, the hormones are synthesized from glycine-extended intermediates that are transformed into active amidated hormones by oxidative cleavage of the glycine N-C alpha bond. In higher organisms, this reaction is catalyzed by a single bifunctional enzyme, peptidylglycine alpha-amidating monooxygenase (PAM). The PAM gene encodes one polypeptide with two enzymes that catalyze the two sequential reactions required for amidation. Peptidylglycine alpha-hydroxylating monooxygenase (PHM; EC 1.14.17.3) catalyzes the stereospecific hydroxylation of the glycine alpha-carbon of all the peptidylglycine substrates. The second enzyme, peptidyl-alpha-hydroxyglycine alpha-amidating lyase (PAL; EC 4.3.2.5), generates alpha-amidated peptide product and glyoxylate. PHM contains two redox-active copper atoms that, after reduction by ascorbate, catalyze the reduction of molecular oxygen for the hydroxylation of glycine-extended substrates. The structure of the catalytic core of rat PHM at atomic resolution provides a framework for understanding the broad substrate specificity of PHM, identifying residues critical for PHM activity, and proposing mechanisms for the chemical and electron-transfer steps in catalysis. Since PHM is homologous in sequence and mechanism to dopamine beta-monooxygenase (DBM; EC 1.14.17.1), the enzyme that converts dopamine to norepinephrine during catecholamine biosynthesis, these structural and mechanistic insights are extended to DBM.     

Induction of anti-Treponema pallidum antibodies in normal rabbits by RNA-immuno-carrier extracted from serum of syphilitic rabbits

Zusammenfassung Es wird bestätigt, dass die i.v. Injektion von RNA aus dem Serum Syphilis-infizierter Kaninchen in gesunde Kaninchen die Bildung der Abwehrstoffe gegenT. pallidum verursacht.     

Lactic dehydrogenase isoenzymes in various cell types of mouse liver

Zusammenfassung Mit einer einfachen Methode wird demonstriert, dass Lebergewebe von Mäusen in 2 Fraktionen verschiedener Menge an Bindegewebe zu trennen ist. Die an Bindegewebe reiche Fraktion zeigt Enzymaktivität in LDH 1, 2, 3, 4 und 5. Nach Entfernung des Bindegewebes wird die Aktivität der LDH 1, 2, 3 und 4 Isoenzyme des restierenden Lebergewebes reduziert.