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81.
82.
Frances M. Fox 《Plant and Soil》1983,71(1-3):269-273
Summary Fruitbodies of sheathing mycorrhizal fungi collected under birch (Betula pendula andB. pubescens) were suspended over pots of soil and the resulting spore-supplemented soils were planted with sedlings ofB. pendula. Inocybe lacera, I. lanuginella, Hebeloma sacchariolens andH. leucosarx formed mycorrhizas readily.Lactarius pubescens andLeccinum roseofracta did not form mycorrhizas from basidiospore inocula, even after prolonged periods of seedling growth.Paxillus involutus gave equivocal results, perhaps because the soil was unsuitable for this species. Storage of the basidiospore-supplemented soils for 6 months in outdoor conditions or in a growth room at 18°C did not materially alter the results.The results are discussed in relation to the concept of mycorrhizal succession. 相似文献
83.
Ahmed Landoulsi Patrick Hughes Renee Kern Masamichi Kohiyama 《Molecular & general genetics : MGG》1989,216(2-3):217-223
Summary Plasmid DNA containing the replication origin of the Escherichia coli chromosome (oriC) has been shown to be inefficient as a template for DNA synthesis in vitro when isolated from dam mutants. here, we extend this study to hemimethylated oriC plasmids and to replication in dam-3 mutant enzyme extracts. The results show that: (1) hemimethylated oriC plasmids replicate with the same low efficiency as nonmethylated DNA; (2) DNA synthesis starts at oriC regardless of the methylated state of the template; (3) replication in dam-3 enzyme extracts is inefficient because this strain is deficient in DnaA protein; and (4) consistent with this observation, the copy number of the oriC plasmid pFH271 is reduced in the dam-3 mutant. However, we have found that low DnaA protein levels in dam-3 mutants are not sufficient to explain the reduced transformation efficiency of oriC plasmids. We suggest that there must exist in vivo inhibitory factors not present or present in low quantities in vitro which specifically recognize the hemimethylated or nonmethylated forms of the oric region. 相似文献
84.
Harris HS Facemire P Greig DJ Colegrove KM Ylitalo GM Yanagida GK Nutter FB Fleetwood M Gulland FM 《Journal of wildlife diseases》2011,47(1):246-254
A male neonatal Pacific harbor seal (Phoca vitulina richardsi) stranded off the coast of California, USA, was presented for rehabilitation with numerous partially haired, soft tissue masses around the mouth and in the oropharynx. Because of the extent of the lesions, the seal was humanely euthanized. Histologically, the masses consisted of subepithelial connective tissue and subcutis expanded by a proliferation of streams and bundles of spindle to stellate cells. Morphology of these cells suggested a neural origin, which was confirmed by positive immunohistochemistry for two neural markers, S-100 protein and glial fibrillary acidic protein, so the masses were diagnosed as neuroglial heterotopia. Heterotopic neuroglial tissue is a rare lesion comprised of benign mature neural tissue in an ectopic location with no connection to the central nervous system. Results of polycyclic aromatic hydrocarbon (PAH) metabolite analysis of bile indicated recent exposure to a petroleum source. Although fetal exposure to PAHs in utero can cause neurotoxicity and affect normal embryonic development, it is unknown whether gestational exposure occurred in this case. 相似文献
85.
A synergistic interaction of IL-6 and IL-1 mediates the thymocyte-stimulating activity produced by recombinant IL-1-stimulated fibroblasts 总被引:7,自引:0,他引:7
J A Elias G Trinchieri J M Beck P L Simon P B Sehgal L T May J A Kern 《Journal of immunology (Baltimore, Md. : 1950)》1989,142(2):509-514
We characterized the ability of normal human lung fibroblasts to elaborate thymocyte-stimulating activity, spontaneously, and in response to rIL-1. Supernatants from unstimulated fibroblasts did not contain thymocyte-stimulating activity, whereas supernatants from fibroblasts incubated with rIL-1 alpha or rIL-1 beta contained more thymocyte-stimulating activity than could be accounted for by passively transferred rIL-1 alone. This heightened thymocyte-stimulating activity was mediated by fibroblast-derived IL-6 inasmuch as it was neutralized by anti-serum against human rIL-6, and rIL-1-stimulated fibroblasts to accumulate messenger RNA for IL-6 and produce soluble IL-6 protein. However, IL-6 alone could not account for the intensity of this effect because rIL-6 only weakly stimulated thymocyte proliferation. In addition, antisera against the rIL-1 moiety that was used to prepare the supernatant had different effects on supernatants that contained and did not contain active IL-6. In the presence of IL-6 these antisera caused a greater decrease in thymocyte-stimulating activity than could be accounted for by passively transferred rIL-1 alone. When the IL-6 was neutralized the remaining thymocyte-stimulating activity could be quantitatively accounted for and neutralized by antisera against the rIL-1 that was passively transferred. Furthermore, rIL-6 and rIL-1 (alpha or beta) synergized in stimulating thymocyte proliferation. Thus, rIL-1 stimulates fibroblasts to produce a thymocyte-stimulating activity that is largely mediated by a synergistic interaction of fibroblast-derived IL-6 and IL-1. These findings suggest that fibroblast production of IL-6 may mediate or amplify some of the tissue effects of IL-1. In addition they suggest that biologic effects previously attributed to IL-1 may be due to IL-6 alone or the concerted action of IL-1 and IL-6. 相似文献
86.
Christian Frech Michael Kommenda Viktoria Dorfer Thomas Kern Helmut Hintner Johann W Bauer Kamil ?nder 《BMC bioinformatics》2009,10(1):21
Background
Protein-protein interaction (PPI) data sets generated by high-throughput experiments are contaminated by large numbers of erroneous PPIs. Therefore, computational methods for PPI validation are necessary to improve the quality of such data sets. Against the background of the theory that most extant PPIs arose as a consequence of gene duplication, the sensitive search for homologous PPIs, i.e. for PPIs descending from a common ancestral PPI, should be a successful strategy for PPI validation. 相似文献87.
Wills M Akbar A Beswick M Bosch JA Caruso C Colonna-Romano G Dutta A Franceschi C Fulop T Gkrania-Klotsas E Goronzy J Griffiths SJ Henson S Herndler-Brandstetter D Hill A Kern F Klenerman P Macallan D Macualay R Maier AB Mason G Melzer D Morgan M Moss P Nikolich-Zugich J Pachnio A Riddell N Roberts R Sansoni P Sauce D Sinclair J Solana R Strindhall J Trzonkowski P van Lier R Vescovini R Wang G Westendorp R Pawelec G 《Immunity & ageing : I & A》2011,8(1):10-8
The Second International Workshop on CMV & Immunosenescence was held in Cambridge, UK, 2-4th December, 2010. The presentations covered four separate sessions: cytomegalovirus and T cell phenotypes; T cell memory frequency, inflation and immunosenescence; cytomegalovirus in aging, mortality and disease states; and the immunobiology of cytomegalovirus-specific T cells and effects of the virus on vaccination. This commentary summarizes the major findings of these presentations and references subsequently published work from the presenter laboratory where appropriate and draws together major themes that were subsequently discussed along with new areas of interest that were highlighted by this discussion. 相似文献
88.
Assimilatory and dissimilatory sulphite reductions are key reactions in the biogeochemical sulphur cycle and several distinct sirohaem-containing sulphite reductases have been characterized. Here, we describe that the Epsilonproteobacterium Wolinella succinogenes is able to grow by sulphite respiration (yielding sulphide) with formate as electron donor. Sulphite is reduced by MccA, a prototypical member of an emerging new class of periplasmic cytochrome c sulphite reductases that, phylogenetically, belongs to a multihaem cytochrome c superfamily whose members play crucial roles in the global sulphur and nitrogen cycles. Within this family, MccA represents an unconventional octahaem cytochrome c containing a special haem c group that is bound via two cysteine residues arranged in a unique CX(15)CH haem c binding motif. The phenotypes of numerous W.succinogenes mutants producing MccA variants underlined the structural importance of this motif. Several open reading frames of the mcc gene cluster were individually inactivated and characterization of the corresponding mutants indicated that the predicted iron-sulphur protein MccC, the putative quinol dehydrogenase MccD (a member of the NrfD/PsrC family) as well as a peptidyl-prolyl cis-trans isomerase, MccB, are essential for sulphite respiration. MccA synthesis in W. succinogenes was found to be induced by sulphite (but not by thiosulphate or sulphide) and repressed in the presence of fumarate or nitrate. Based on the results, a sophisticated model of respiratory sulphite reduction by the Mcc system is presented. 相似文献
89.
Frances J. White 《International journal of primatology》1988,9(3):179-193
The pygmy chimpanzee, or bonobo, Pan paniscus,diplays a fission-fusion social organization in which individuals associate in parties that vary in size and composition.
Data from a 2-year field study of nonprovisioned P. paniscusshow that party composition varies with party size. Although females, on average, outnumber males, the proportion of males
in the party increases in larger parties. This effect was not due to the greater number of known females. Both females and
males will join and leave a party in the company of others, but only males appear frequently to join or leave as lone individuals.
All-male parties were not observed, but all-female (nonnursery) parties were relatively common. These trends reflect greater
cohesion among females than observed in P. troglodytes schweinfurthii.Cohesion between males and female P. paniscusmay increase with party size. 相似文献
90.
R. Kern M. Egelhaaf 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2000,186(1):45-55
We have studied freely flying and walking flies as well as flies flying in a flight simulator in order to discover how functionally
blinding one of the eyes affects the fly's ability to move straight. It is hard to tell just by observing the animals' movements
whether they have been deprived of vision in one eye. Statistical analysis is need to show that there are differences in the
locomotory paths of monocular and binocular flies: monocular flies tend to turn slightly towards the side of the seeing eye.
It is possible that the superimposed translational and rotational optic flow fields, generated on the trajectory of monocular
flies, sum to zero net flow. This overall flow over the retina of the open eye might lead to a state of optomotor equilibrium.
Accepted: 11 October 1999 相似文献