鸟类起源于基干的初龙类

中亚三叠纪和中国早白垩世的新的重要化石发现或许可以帮助解决有关鸟类起源的争议。鸟类的飞行可能起源于三叠纪一些小型的、四脚滑翔的初龙类。羽毛的起源最初是为了滑翔而不是保温。“手盗龙类”实际上起源于鸟类 ,并至少发育了初级飞羽 ,具备滑翔的能力     

Metabolites of the Free-Living Amoeba Phreatamoeba balamuthi Analyzed by 13C- and 31P-NMR Spectroscopy: Occurrence of Phosphoinositol Diphosphates

ABSTRACT. Phreatamoeba balamuthi is a free-living heterotrophic amoeba that lacks mitochondria. Metabolites of axenically-grown cells were characterized by natural-abundance ¹³C-NMR and ³¹P-NMR spectroscopy on acellular perchloric acid extracts. The amoebae were found to contain glycogen and trehalose as storage carbohydrates, together with putrescine and several amino acids, most prominently proline; we propose that proline and trehalose may serve in osmoregulation. Glycerophosphocholine and glycerophosphoethanolamine were present with their phosphomonoester derivatives, phosphocholine and phosphoethanolamine. Along with inorganic phosphate, inorganic pyrophosphate, nucleoside diphosphates, nucleoside triphosphates and NAD, P. balamuthi amoebae also contained unusual phosphoinositol diphosphates in large quantities (0.5 μmol/g wet cells).     

The fate of beryllium compounds in the rat

Beryllium was injected intravenously into rats. When administered as ionic solution or as citrate complex, nearly half of the injected quantity was excreted and most of the remaining beryllium was retained in the bones.     

Characterization of Two Sibling Species of the Genus Stylonychia (Ciliata,Hypotricha): S. mytilus Ehrenberg, 1838 and S. lemnae n. sp. I. Morphology and Reproductive Behavior1

All Stylonychia mytilus-like ciliates which were collected and sent to us during the last 20 years belonged either to S. mytilus or to a new species, S. lemnae, which is described here. The only morphological differences are the shape and the size. Stylonychia mytilus that have been starved for one day average 300 μm in length, and S. lemnae starved for a day are 230 μm long. The occurrence of mating types is described.     

Why are Biennials so Few?: Hart's Results Revisited

Abstract Hart (1977) constructed a model to explain the rarity of biennials in the North American flora. However, Hart's model is inadequate, because: 1) biennials were not compared with annuals, 2) facultative biennials were not included, and 3) the range of general perennial life histories was not considered. Revision of Hart's model shows that strict and facultative biennials are rare, because they compete most successfully against annuals and general perennial life histories only in a narrow range of juvenile and adult survivorship values.     

Descriptions of two new species of Anomalosiphum (Hemiptera: Aphididae, Greenideinae), including a winged ovipara with pedunculate eggs

Of the Asian aphid genus Anomalosiphum , A. mendeli and A. essigi are described as new. Winged sexual forms of A. mendeli are reported here for the first time for an Anomalosiphum , featuring oviparae bearing pedunculate eggs. A key to the known species of Anomalosiphum is presented. Possible phylogenetic affinities between the Greenideinae, Neophyllaphidinae and Aiceoninae are discussed.  © 2006 Government of Canada, Natural Resources Canada, Zoological Journal of the Linnean Society , 2006, 146 , 239–249.     

The behavioural basis of prey selection by underyearling bream (Abramis brama (L.)) and roach (Rutilus rutilus (L.))

SUMMARY. A clear difference in the ability lo escape from fish predators exists between members of the Cladocera and Copepoda. The results of our laboratory studies have shown that underyearling roach and bream both found copepods more difficult to capture than cladocerans. However, bream were far more efficient than roach at catching the more elusive copepod prey. The basis for this difference was the greater strike ability of bream, most likely related to its more protrusible mouth. In their natural environment the two species of fish exhibited food resource partitioning with planktonic Cladocera predominating in roach guts and copepods and non-planktonic Cladocera composing the vast majority of the gut contents of bream. Differences in diet are partly due to their contrasting attack abilities. Additional variation may arise because of subtle differences in the timing and location of foraging.