The effects of long-term elevation of air temperature and CO on the frost hardiness of Scots pine

The frost hardiness of 20 to 25-year-old Scots pine (Pinus sylvestris L.) saplings was followed for 2 years in an experiment that attempted to simulate the predicted climatic conditions of the future, i.e. increased atmospheric CO₂ concentration and/or elevated air temperature. Frost hardiness was determined by an electrolyte leakage method and visual damage scoring on needles. Elevated temperatures caused needles to harden later and deharden earlier than the controls. In the first year, elevated CO₂ enhanced hardening at elevated temperatures, but this effect disappeared the next year. Dehardening was hastened by elevating CO₂ in both springs. The frost hardiness was high (相似文献   

Single Protein Molecule Mapping with Magnetic Atomic Force Microscopy

Understanding the structural organization and distribution of proteins in biological cells is of fundamental importance in biomedical research. The use of conventional fluorescent microscopy for this purpose is limited due to its relatively low spatial resolution compared to the size of a single protein molecule. Atomic force microscopy (AFM), on the other hand, allows one to achieve single-protein resolution by scanning the cell surface using a specialized ligand-coated AFM tip. However, because this method relies on short-range interactions, it is limited to the detection of binding sites that are directly accessible to the AFM tip. We developed a method based on magnetic (long-range) interactions and applied it to investigate the structural organization and distribution of endothelin receptors on the surface of smooth muscle cells. Endothelin receptors were labeled with 50-nm superparamagnetic microbeads and then imaged with magnetic AFM. Considering its high spatial resolution and ability to “see” magnetically labeled proteins at a distance of up to 150 nm, this approach may become an important tool for investigating the dynamics of individual proteins both on the cell membrane and in the submembrane space.     

Evaluation of the Contribution of Homologous Recombination in DNA Double-Strand Break Repair in Human Fibroblasts after Exposure to Low and Intermediate Doses of X-ray Radiation

Biology Bulletin - Abstract—Studies of the changes in the number of γH2AX foci (a DNA double-strand break protein-marker), and Rad51 foci (a key homologous recombination protein) were...     

New Observations on the Choreotrich Ciliate Strombidinopsis acuminata Fauré-Fremiet 1924, and Comparison with Strombidinopsis jeokjo Jeong et al., 2004

ABSTRACT. A choreotrich ciliate collected in waters off Geoje Island, on the eastern coast of the South Sea of the southern coastal water of Korea was morphologically and biometrically investigated through observations of permanent preparations after protargol impregnations. Morphological data and ciliary patterns indicated that the ciliate should be identified as Strombidinopsis acuminata based on the number of somatic kineties. The vertical distribution of the population abundance was also examined in relation to environmental conditions: higher abundances occurred in surface water with higher temperature (22–23 °C), lower salinity (32 psu), and higher concentration (ca 10 μg/L) of chlorophyll a . The 18S rRNA gene of specimens from clonal cultures isolated from natural assemblages was sequenced. While this isolate of S. acuminata is closer to Strombidinopsis jeokjo (99.6–99.8%) than other isolates of S. acuminata (<99.0%), monophyly of S. acuminata was not rejected by the AU test. We discuss the discordance between morphological and molecular data for Strombidinopsis . In order to confirm the species level of the Strombidinopsis specimens, additional information is required based on genealogical analyses of multiple loci.     

Effect of mutations in Escherichia coli genes PolAm RecA, RecB and RecC on the frequency of genetic recombination in amber-mutants involving the early genes of bacteriophage T4]

Effects of mutations in genes PolA, RecA, RecB and RecC of Escherichia coli on the recombination frequencies between rII markers of T4 have been studied in conditions of partial inhibition of some early functions. It was found that the presence of the mutations in genes PolA or RecA decreased significantly the recombination frequency of phage amber mutant in the gene 43 (DNA polymerase), increased it in the case of amber mutation in the gene 46 (exonuclease) and had no effect on the recombination of amber mutants in genes 30, 32, 33, 41, 42, 45, 44, 52. None of the amber mutants studied changed recombination frequencies in the presence of the mutations in genes RecB or RecC. Possible mechanisms of some of the effects observed are discussed.     

Elbow-joint morphology as a guide to forearm function and foraging behaviour in mammalian carnivores

Among the hunting strategies employed by members of the order Carnivora (Mammalia), two, stalk and ambush and sustained pursuit, are particularly prevalent among larger species of the order. It has been difficult to identify morphological traits that support this distinction and ecological observations have shown that most carnivorans adopt a continuum of strategies, depending on available habitat and prey. In this paper, the shape of the distal humerus articulation is analysed, with the aim of exploring the use of the forelimb in prey procurement, and as a guide to such behaviour among fossil carnivorans. The results suggest that manual manipulation and locomotion are conflicting functions. Elbow‐joint morphology supports a division between grapplers (i.e. ambushers) and nongrapplers (i.e. pursuers). Joints of the former are characterized by being relatively wide and the latter, by being relatively narrow and box‐like with pronounced stabilizing features. At intermediate and large body sizes, carnivorans show a pattern suggesting mutually exclusive feeding strategies that involve either grappling with prey or sustained pursuit. The former allows for large body sizes, such as pantherine felids and ursids; the latter includes species of only moderate size, such as hyenids and canids. Elbow‐joint morphology is closely linked to phylogeny, but the morphology of the cheetah converges with that of nongrapplers, showing that strong selective forces may override the phylogenetic component. Two taxa of giant mustelids from the Miocene were analysed to test whether this sort of analysis is applicable to carnivorans of the past. The African Late Miocene species Ekorus ekakeran has a joint morphology comparable to that of modern‐day nongrapplers. Two joint morphologies were found in the North American Late Oligocene‐Early Miocene Megalictis ferox. The first morphology is comparable to that of modern pantherine cats and the second forms an intermediate between grapplers and nongrapplers that is not present in the modern carnivoran fauna. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 142 , 91–104.     

Functioning of amino acid operons in Escherichia coli strains with an altered transcription and translation apparatus. I. The effect of mutations in gene rpsL coding ribosomal protein S12 on the functioning of the ilv operon

Derepression of the ilv operon in rel strains of Escherichia coli is delayed when cells are transferred from rich to minimal medium and is completely blocked when the mixture of amino acids--serine, methionine and glycine is present in the minimal medium. It is shown that alterations in translation machinery caused by streptomycine resistance mutation can also lead to the delay of the ilv operon derepression in rel+ strains or to its complete inhibition in rel strains of E. coli. The possible mechanisms of high sensitivity of the ilv operon to different alterations in E. coli are discussed.     

Changes in the therapeutic spectrum with respect to the pharmacological and radioprotective activity after O-alkylation of serotonin and 5(2-hydroxyethoxytryptamine)

In experiments with mongrel mice, a study was made of the pharmacological activity of serotonin and its O-alkyl derivatives. It was estimated by the two indices, that is, the radioprotective properties and the influence on a local blood channel in the spleen, the modifying effect of the agents' toxicity being estimated as well. As an O-alkyl group of 5-alkoxytryptamines was elongated from one to three carbon atoms and the toxicity of the substances increased, their radioprotective effect decreased more readily than their effect on the local blood channel. The shortening of the range of the therapeutic action of the agents under study, with regard to the two pharmacological indices mentioned above, the alkyl group being lengthened, followed a logarithmic function which was more pronounced in relation to the radioprotective index (cos alpha 1/cos alpha 2 = 1.58).     

New concepts of microsomal metabolism of the antibiotic adriamycin

Experimental and literary data are presented which are at variance with the known conception of adriamycin (AD) shunting the chain of microsomal electron transfer. AD, carminomycin, rubomycin, mitomycin C, and coenzyme Q9 are shown to interact with NADPH, in the absence of enzymes, with the nucleotide oxidation. A new scheme of AD metabolism is suggested, according to which AD in the hydroquinone form enters the chain of electron transfer in microsomes between NADPH and flavoprotein.