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891.
A broad understanding of the relationship between gene activation, pattern formation and morphogenesis will require adequate tools for three-dimensional and, perhaps four-dimensional, representation and analysis of molecular developmental processes. We present a novel, computer-based method for the 3D visualization of embryonic gene expression and morphological structures from serial sections. The information from these automatically aligned 3D reconstructions exceeds that from single-section and whole-mount visualizations of in situ hybridizations. In addition, these 3D models of gene-expression patterns can become a central component of a future developmental database designed for the collection and presentation of digitized, morphological and gene-expression data. This work is accompanied by a web site (http://www.univie.ac.at/GeneEMAC). 相似文献
892.
893.
Ror2, encoding a receptor-like tyrosine kinase, is required for cartilage and growth plate development 总被引:8,自引:0,他引:8
DeChiara TM Kimble RB Poueymirou WT Rojas J Masiakowski P Valenzuela DM Yancopoulos GD 《Nature genetics》2000,24(3):271-274
Receptor tyrosine kinases often have critical roles in particular cell lineages by initiating signalling cascades in those lineages. Examples include the neural-specific TRK receptors, the VEGF and angiopoietin endothelial-specific receptors, and the muscle-specific MUSK receptor. Many lineage-restricted receptor tyrosine kinases were initially identified as 'orphans' homologous to known receptors, and only subsequently used to identify their unknown growth factors. Some receptor-tyrosine-kinase-like orphans still lack identified ligands as well as biological roles. Here we characterize one such orphan, encoded by Ror2 (ref. 12). We report that disruption of mouse Ror2 leads to profound skeletal abnormalities, with essentially all endochondrally derived bones foreshortened or misshapen, albeit to differing degrees. Further, we find that Ror2 is selectively expressed in the chondrocytes of all developing cartilage anlagen, where it essential during initial growth and patterning, as well as subsequently in the proliferating chondrocytes of mature growth plates, where it is required for normal expansion. Thus, Ror2 encodes a receptor-like tyrosine kinase that is selectively expressed in, and particularly important for, the chondrocyte lineage. 相似文献
894.
SHATTERPROOF MADS-box genes control seed dispersal in Arabidopsis 总被引:34,自引:0,他引:34
The fruit, which mediates the maturation and dispersal of seeds, is a complex structure unique to flowering plants. Seed dispersal in plants such as Arabidopsis occurs by a process called fruit dehiscence, or pod shatter. Few studies have focused on identifying genes that regulate this process, in spite of the agronomic value of controlling seed dispersal in crop plants such as canola. Here we show that the closely related SHATTERPROOF (SHP1) and SHATTERPROOF2 (SHP2) MADS-box genes are required for fruit dehiscence in Arabidopsis. Moreover, SHP1 and SHP2 are functionally redundant, as neither single mutant displays a novel phenotype. Our studies of shp1 shp2 fruit, and of plants constitutively expressing SHP1 and SHP2, show that these two genes control dehiscence zone differentiation and promote the lignification of adjacent cells. Our results indicate that further analysis of the molecular events underlying fruit dehiscence may allow genetic manipulation of pod shatter in crop plants. 相似文献
895.
896.
Insurance-based advantage to helpers in a tropical hover wasp 总被引:8,自引:0,他引:8
The origin and maintenance of eusociality is a central problem in evolutionary biology. Eusocial groups contain individuals that forfeit their own reproduction in order to help others reproduce. In facultatively eusocial taxa, offspring can choose whether to found new nests or become helpers in their natal groups. In many facultatively eusocial insects, offspring need continuous care during development, but adult carers have life expectancies shorter than the developmental period. When a lone foundress dies, her partly reared brood are usually doomed. Here, we show that helpers in a tropical hover wasp (Liostenogaster flavolineata) have an insurance-based advantage over lone foundresses because after a helper dies, most of the brood that she has partly reared will be brought to maturity by surviving nest-mates. After some of the helpers are experimentally removed from a multi-female nest, the reduced group is left with more brood than it would normally rear. We found that larger, more valuable extra brood were reared through to maturity, but not smaller, less valuable brood. Smaller brood may be sacrificed to feed larger brood, and reduced groups probably benefited from increased short-term helper recruitment. Rearing extra brood did not increase adult mortality or brood development time. 相似文献
897.
898.
Presenilin-1 mutations in Alzheimer's disease 总被引:10,自引:0,他引:10
Russo C Schettini G Saido TC Hulette C Lippa C Lannfelt L Ghetti B Gambetti P Tabaton M Teller JK 《Nature》2000,405(6786):531-532
899.
Cheating is a potential problem in any social system that depends on cooperation and in which actions that benefit a group are costly to individuals that perform them. Genetic mutants that fail to perform a group-beneficial function but that reap the benefits of belonging to the group should have a within-group selective advantage, provided that the mutants are not too common. Here we show that social cheating exists even among prokaryotes. The bacterium Myxococcus xanthus exhibits several social behaviours, including aggregation of cells into spore-producing fruiting bodies during starvation. We examined a number of M. xanthus genotypes that were defective for fruiting-body development, including several lines that evolved for 1,000 generations under asocial conditions and others carrying defined mutations in developmental pathways, to determine whether they behaved as cheaters when mixed with their developmentally proficient progenitor. Clones from several evolved lines and two defined mutants exhibited cheating during development, being overrepresented among resulting spores relative to their initial frequency in the mixture. The ease of finding anti-social behaviours suggests that cheaters may be common in natural populations of M. xanthus. 相似文献
900.
Genomic rearrangement in NEMO impairs NF-kappaB activation and is a cause of incontinentia pigmenti. The International Incontinentia Pigmenti (IP) Consortium 总被引:12,自引:0,他引:12
Smahi A Courtois G Vabres P Yamaoka S Heuertz S Munnich A Israël A Heiss NS Klauck SM Kioschis P Wiemann S Poustka A Esposito T Bardaro T Gianfrancesco F Ciccodicola A D'Urso M Woffendin H Jakins T Donnai D Stewart H Kenwrick SJ Aradhya S Yamagata T Levy M Lewis RA Nelson DL 《Nature》2000,405(6785):466-472