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611.
Six species of deep chaetognaths, three planktonic and threebenthoplanktonic, have been taken during seven dives of theUS submersibleAlvin on the Seamount Volcano 7 off Mexico, atdepths between 800 and 3100 m. The most interesting observationsconcern two of the latter,Heterokrohnia heterodonta and Archeterokrohniarubra. Indeed it appears that they have a large foamy collarette,glandular canals on the neck region and an original corona ciliata(posteriorly discontinuous). Although localized, these samplesgive new information on the geographical distribution of threespeaes: Eukrohma macroneura and the two mentioned above 相似文献
612.
A. De Bustos C. Casanova C. Soler N. Jouve 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(1):101-111
The genetic variation of 102 natural populations of wild barley growing in Spain was assessed using RAPDs (random amplified
polymorphic DNA). The plant material included the annual species H. marinum subsp. marinum (22 populations) and subsp. gussoneanum (14), H. murinum subsp. murinum (7) and subsp. leporinum (35), and the perennial species H. bulbosum (17) and H. secalinum (7). Ten of the tested 64 arbitrary 10-mer primers amplified polymorphic DNA in all taxonomic units. Analyses was performed
within and between populations, species and subspecies. The primers gave a total of 250 RAPD products. The level of polymorphism
varied between taxonomic units depending on the primers employed and the plant reproductive system. In general, the most variable
were the allogamous species H. secalinum and H. bulbosum and the autogamous H. marinum subsp. marinum. Among the amplified bands, 69 (27%) were shared by at least two different taxonomic units. The remaining bands were specific.
The results demonstrate differences in the degree of similarity between taxonomic units. Jaccard’s similarity coefficients
for interval measure within and between populations were used to produce a cluster diagram using the unweighted pair-group
method (UPGMA). The different populations of the species and subspecies of Hordeum fell into three groups. The first group contained the populations belonging to both subspecies of H. marinum, plus those of H. secalinum. The populations of H. marinum subsp. gussoneanum were very closely associated. Those of H. marinum subsp. marinum were grouped in a broad cluster. The second group, occupying the innermost position of the tree, was very closely associated
with the populations of both subspecies of H. murinum. The third branch segregated H. bulbosum. A series of RAPD markers were investigated by cleaving the amplified products of the same size with restriction endonucleases
that recognize targets of 4- or 6-bp. The production of equivalent fragments following cleavage by the same enzyme would seem
to demonstrate their homology in samples from different individuals, populations or taxonomic units.
Received: 18 May 1997 / Accepted: 22 August 1997 相似文献
613.
Convection-enhanced delivery (CED) is a technique to bypass the blood-brain barrier and deliver therapeutic agents into the brain. However, animal studies and preliminary clinical trials have reported reduced efficacy to transport drugs in specific regions, attributed mainly to backflow, in which an annular zone is formed outside the catheter and the fluid preferentially flows toward the surface of the brain rather than through the tissue toward the targeted area. In this study, a finite element model of backflow was updated by implementing the pre-stress generated during needle insertion, which allows considering the effect of needle insertion velocity during CED infusions in agarose gel. The nonlinear mechanical properties of the agarose solutions were obtained by fitting experimental data from stress-relaxation tests. Additional experimental measurements of backflow lengths were used to adjust the pre-stress model. The developed model was able to reproduce changes of backflow length under different insertions velocities and flow rates. These findings reveal the relevance of considering the pre-stress in the tissue located around the needle surface during CED infusions into the brain. 相似文献
614.
Cyclins are indispensable elements of the cell cycle and derangement of their function can lead to cancer formation. Recent studies have also revealed more mechanisms through which cyclins can express their oncogenic potential. This review focuses on the aberrant expression of G1/S cyclins and especially cyclin D and cyclin E; the pathways through which they lead to tumour formation and their involvement in different types of cancer. These elements indicate the mechanisms that could act as targets for cancer therapy. 相似文献
615.
Lucie Paloque Nicolas Vidal Magali Casanova Aurélien Dumètre Pierre Verhaeghe Daniel Parzy Nadine Azas 《Journal of microbiological methods》2013
We validated a new method, based on luciferine/luciferase bioluminescence, for drug screening on promastigotes of different Leishmania species. Results obtained with this new, rapid, reproducible, and reliable method are in good accordance with results obtained by the conventional MTT assay. This bioluminescence assay has a lower detection limit. 相似文献