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341.
F. Vánky Noémi Nagy Christina Hising Kerstin Sjövall Eva Klein 《Cancer immunology, immunotherapy : CII》1997,43(6):317-323
We tested 20 human carcinoma samples for the production of transforming growth factor β (TGFβ) in vitro. Tumour cell suspensions
without obvious contamination with non-malignant cells were kept in culture conditions for 16 h and their supernatants were
added to CCL-64 cells. The proliferation of these cells is inhibited by TGFβ. According to this assay, the supernatants contained
both active and latent TGFβ. In addition, the supernatants were found to suppress the spontaneous cytotoxic function and activation
of T-cell-enriched lymphocyte populations. A specific monoclonal antibody (mAb) counteracted these effects and therefore we
concluded that they were mediated to a large extent by TGFβ. In line with the results obtained with the supernatants, activation
of lymphocytes could also be inhibited by tumour cells and their inhibitory effect was weaker in the presence of the TGFβ-specific
mAb. It is important to note that, when TGFβ-specific mAb was added to autologous mixed lymphocyte/tumour cell cultures, lymphocyte
activation occurred more often. These results thus substantiate the assumption that production of TGFβ may help the survival
of potentially immunogenic tumour cells in immunocompetent patients.
Received: 21 August 1996 / Accepted: 12 November 1996 相似文献
342.
Superoxide dismutase, catalase and nitrogenase activities of symbiotic Frankia (Alnus incana) in response to different oxygen tensions 总被引:2,自引:0,他引:2
Presence and activity of the enzymes superoxide dismutase (SOD) and catalase were studied in Frankia in symbiosis with Alnus incana (L.) Moench. Analysis on native PAGE gels indicated that symbiotic Frankia contained an FeSOD and catalase. The activity of the enzymes was in the same range as reported for cultured Frankia . Attempts to characterize SOD by western blots with antisera from Escherichia coli and Azotobacter vinelandii did not give clear-cut results with the antibodies used. Alnus incana plants were grown with the root system in 5, 10, 21 or 40% O2 for up to 6 days. Nitrogenase activity, measured as ARA (acetylene reducing activity) dropped within 3 h when roots were exposed to low or high oxygen. At 40% O2 ARA was almost completely lost while at 5 and 10% O2 ARA decreased to 69 and 74% of the inital value, respectively, Nitrogenase activity recovered at ail oxygen tensions. Recovery rates resembled the continuous increase in ARA in plants continuosly kept at 21% O2 , and suggests that new vesicles with envelopes of appropriate thickness were formed. The ARA measurements confirm results from an earlier study where nitrogenase activity was measured as H2 evolution. There was a tendency for increased SOD and catalase activities in Frankia from root systems exposed to 40% O2 for 24 h but not earlier or later than this. When data from all experimental times were pooled. SOD activity increased significantly with increased oxygen tension whereas catalase activity decreased. Although ARA per plant varied with oxygen tension, there was no statistically significant correlation between ARA and SOD or between ARA and catalase. It seems that being linked to nitrogenase activity is only one role of SOD and catalase in this symbiotic Frankia . 相似文献
343.
Rabies seems to persist throughout most arctic regions, and the northern parts of Norway, Sweden and Finland, is the only
part of the Arctic where rabies has not been diagnosed in recent time. The arctic fox is the main host, and the same arctic
virus variant seems to infect the arctic fox throughout the range of this species. The epidemiology of rabies seems to have
certain common characteristics in arctic regions, but main questions such as the maintenance and spread of the disease remains
largely unknown. The virus has spread and initiated new epidemics also in other species such as the red fox and the racoon
dog. Large land areas and cold climate complicate the control of the disease, but experimental oral vaccination of arctic
foxes has been successful. This article summarises the current knowledge and the typical characteristics of arctic rabies
including its distribution and epidemiology. 相似文献
344.
Three different strains of Frankia , the pure cultures AvcI1 and CpI1 and a local strain (crushed nodule inoculum), were compared in symbiosis with one clone of Alnus incana (L.) Moench. Hydrogen metabolism, nitrogenase (EC 1.7.99.2) activity and relative efficiency of nitrogenase were studied as well as growth and nitrogen content of the plants. The local Frankia strain showed no measurable hydrogen uptake but high H2 -evolution. No H2 -evolution was detected in Frankia AvcI1 because of its hydrogenase activity. CpI1 also had hydrogenase, although only a very small H2 -evolution was detected at the end of the growth period. Hydrogenase activity was detected both in pure cultures and nodule homogenates of CpI1 and AvcI1. Growth, biomass production and nitrogen content were highest in alders inoculated with Frankia AvcI1 while the lowest values were found for alders living in symbiosis with the local Frankia strain. The presence of hydrogenase in Frankia seemed to be benefical for growth and biomass production in the alders. However, the strains also differed with respect to spore formation. The local strain, but not AvcI1 and CpI1, formed spores in the root nodules. 相似文献
345.
Andrey Tatarenkov Rita B. Jnsson Lena Kautsky Kerstin Johannesson 《Journal of phycology》2007,43(4):675-685
Recent studies showing consequences of species’ genetic diversity on ecosystem performance raise the concern of how key ecosystem species are genetically structured. The bladder wrack Fucus vesiculosus L. is a dominant species of macroalga in the northern Atlantic, and it is particularly important as a habitat‐forming species in the Baltic Sea. We examined the genetic structure of populations of F. vesiculosus with a hierarchical approach from a within‐shore scale (10 m) to a between‐seas scale (Baltic Sea–Skagerrak, 800 km). Analysis of five microsatellite loci showed that population differentiation was generally strong (average FST = 12%), being significant at all spatial scales investigated (101, 103, 104–5, 106 m). Genetic differentiation between seas (Baltic Sea and Skagerrak) was substantial. Nevertheless, the effects of isolation by distance were stronger within seas than between seas. Notably, Baltic summer‐reproducing populations showed a strong within‐sea, between‐area (70 km) genetic structure, while Baltic autumn‐reproducing populations and Skagerrak summer‐reproducing populations revealed most genetic diversity between samples within areas (<1 km). Despite such differences in overall structure, Baltic populations of summer‐ and autumn‐reproducing morphs did not separate in a cluster analysis, indicating minor, if any, barriers to gene flow between them. Our results have important implications for management and conservation of F. vesiculosus, and we raise a number of concerns about how genetic variability should be preserved within this species. 相似文献
346.
Astrid Stumpf Joana Almaca Karl Kunzelmann Kerstin Wenners-Epping Stephan M Huber Johannes Haberle Sabine Falk Angelika Duebbers Mike Walte Hans Oberleithner Hermann Schillers 《Cellular physiology and biochemistry》2006,18(4-5):243-252
DIDS (4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid) is a commonly used blocker of plasma membrane anion channels and transporters. We observed that DIDS undergoes decomposition while stored in DMSO (dimethyl sulfoxide) forming a biologically active compound. One decomposition product, called IADS, was identified and synthesized. Voltage-clamp and patch clamp experiments on Xenopus laevis oocytes and human erythrocytes revealed that IADS is able to activate a plasma membrane cation conductance in both cell types. Furthermore, we found that IADS induces hemolysis in red blood cells of healthy donors but fails to hemolyze erythrocytes of donors with cystic fibrosis. Thus, IADS stimulated activation of a cation conductance could form the basis for a novel diagnostic test of cystic fibrosis. 相似文献
347.
348.
Host caste recognition may be important for the dispersal of phoretic mites associated with social insects. All developmental
stages of the mite Parasitellus fucorum (Acari: Mesostigmata: Parasitidae) live in the nests of bumblebees (Hymenoptera: Apidae: Bombus). Dispersal occurs by specialised phoretic instars, deutonymphs, which attach to adult bumblebees. Since bumblebee colonies
are annual and only young queens overwinter, deutonymphs that are able to discriminate between bumblebee castes and preferentially
attach to queens should be favoured by selection. In the field, deutonymphs of P. fucorum were found to be phoretic on bumblebee workers and queens, and in behavioural experiments all castes proved to be attractive
as carriers for the mites. However, they preferred queens that had hibernated as carriers when they could choose between workers
and queens. In a further experiment, when given a choice, deutonymphs switched from males to young queens but never transferred
from a queen to a male. These results suggest that deutonymphs preferentially attach to queens but may also use other castes
for transport. Those dispersing on workers and males may try to switch to queens later. Host-switching is possible during
copulation and on flowers, where bees of all castes forage.
Received: 14 November 1997 / Accepted: 16 February 1998 相似文献
349.
Physiological and Molecular Biological Characterization of Ammonia Oxidation of the Heterotrophic Nitrifier Pseudomonas putida 总被引:2,自引:0,他引:2
Michael Daum Wolfgang Zimmer Hans Papen Karin Kloos Kerstin Nawrath Hermann Bothe 《Current microbiology》1998,37(4):281-288
The heterotrophic nitrifier Pseudomonas putida aerobically oxidized ammonia to hydroxylamine, nitrite, and nitrate. Product formation was accompanied by a small but significant
release of NO, whereas N2O evolution could not be detected under the assay conditions employed. The isolate reduced nitrate to nitrite and partially
further to NO under anaerobic conditions. Aerobically grown cells utilized γ-aminobutyrate as a carbon source and as a N-source
by ammonification. The physiological experiments, in particular the inhibition pattern by C2H2, indicated that P. putida expressed an ammonia monooxigenase. DNA-hybridization with an amoA gene probe coding for the smaller subunit of the ammonia monooxigenase of Nitrosomonas europaea allowed us to identify, to clone, and to sequence a region with an open reading frame showing distinct sequence similarities
to the amoA gene of autotrophic ammonia oxidizers.
Received: 9 April 1998 / Accepted: 15 May 1998 相似文献
350.
Brigitte Jeschke Kerstin Uhl Bernd Weist Dirk Schröder Thomas Meitinger Christoph Döhlemann H.-P. Vosberg 《Human genetics》1998,102(3):299-304
Hypertrophic cardiomyopathy (HCM) is a genetically and clinically heterogeneous myocardial disease that is in most cases
familial and transmitted in a dominant fashion. The most frequently affected gene codes for the cardiac (ventricular) β-myosin
heavy chain. We have investigated the genetic cause of an isolated case of HCM, which was marked by an extremely severe phenotype
and a very early age of onset. HCM is normally not a disease of small children. The proband was a boy who had suffered cardiac
arrest at the age of 6.5years (resuscitation by cardioconversion). Upon screening of the β-myosin heavy chain gene as a candidate,
two missense mutations, one in exon19 (Arg719Trp) and a second in exon12 (Met349Thr), were identified. The Arg719Trp mutation
was de novo, as it was not found in the parents. In contrast, the Met349Thr mutation was inherited through the maternal grandmother.
Six family members were carriers of this mutation but only the proband was clinically affected. Segregation and molecular
analysis allowed us to assign the Met349Thr mutation to the maternal and the Arg719Trp de novo mutation to the paternal β-myosin
allele. Thus, the patient has no normal myosin. We interpret these findings in terms of compound heterozygosity of a dominant
(Arg719Trp) and a recessive (Met349Thr) mutation. Whereas a single mutated Arg719Trp allele would be sufficient to cause HCM,
the concurrent Met349Thr mutation alone does not apparently induce the disease. Nevertheless, it conceivably contributes to
the particularly severe phenotype.
Received: 15 September 1997 / Accepted: 26 November 1997 相似文献