Bericht über eine Reise nach der VR Polen 1976 zur Sammlung autochthoner Sippen von Kulturpflanzen     

Peter Hanelt  Karl Hammer 《Genetic Resources and Crop Evolution》1977,25(1):33-44

Ohne ZusammenfassungHerrn Prof. Dr. Drs. h. c.Hans Stubbe zum 75. Geburtstag gewidmet.  相似文献   

Molecular diversity of Omani wheat revealed by microsatellites: I. Tetraploid landraces     

S. Al Khanjari  K. Hammer  A. Buerkert  M. S. Röder 《Genetic Resources and Crop Evolution》2007,54(6):1291-1300

Results of archaeological studies indicate a millennia-old cultivation history for wheat (Triticum spp.) in Oman. However, in spite of numerous collection surveys and efforts for phenotypic characterization of Omani wheat landraces, no attempts have been made using molecular tools to characterize this germplasm. To fill this gap, 29 microsatellite markers revealing 30 loci were used to study the genetic diversity of 38 tetraploid wheat landrace accessions comprising the species T. dicoccon, T. durum and T. aethiopicum. A total of 219 alleles were detected whereby the number of alleles per locus ranged from 2 to 16 with an average number of 7.1 alleles per locus. The highest number of alleles occurred in the B genome with on average 7.9 alleles per locus as compared to the A genome with 6.5 alleles per locus. Heterogeneity was detected for all microsatellites except for GWM 312, GWM 601 and GWM 192B with an average heterogeneity over all primers and lines of 14.4%. Approximately 10% of the accessions contained rare alleles with an average allele frequency <4%. Gene diversity across microsatellite loci ranged from 0.26 to 0.85. The pairwise comparison of genetic similarity ranged from 0.03 to 0.91 with an average of 0.2. Cluster analysis revealed a clear separation of the two species groups T. dicoccon versus T. durum and T. aethiopicum. Within the species clusters regional patterns of subclustering were observed. Overall, this study confirmed the existence of a surprisingly high amount of genetic diversity in Omani wheat landraces as already concluded from previous morphological analyses and showed that SSR markers can be used for landraces’ analysis and a more detailed diversity evaluation.  相似文献   

A neuroligin-3 mutation implicated in autism increases inhibitory synaptic transmission in mice     

Tabuchi K  Blundell J  Etherton MR  Hammer RE  Liu X  Powell CM  Südhof TC 《Science (New York, N.Y.)》2007,318(5847):71-76

Autism spectrum disorders (ASDs) are characterized by impairments in social behaviors that are sometimes coupled to specialized cognitive abilities. A small percentage of ASD patients carry mutations in genes encoding neuroligins, which are postsynaptic cell-adhesion molecules. We introduced one of these mutations into mice: the Arg451-->Cys451 (R451C) substitution in neuroligin-3. R451C mutant mice showed impaired social interactions but enhanced spatial learning abilities. Unexpectedly, these behavioral changes were accompanied by an increase in inhibitory synaptic transmission with no apparent effect on excitatory synapses. Deletion of neuroligin-3, in contrast, did not cause such changes, indicating that the R451C substitution represents a gain-of-function mutation. These data suggest that increased inhibitory synaptic transmission may contribute to human ASDs and that the R451C knockin mice may be a useful model for studying autism-related behaviors.  相似文献   

A chicken transferrin gene in transgenic mice escapes X-chromosome inactivation   总被引：4，自引：0，他引：4  

M A Goldman  K R Stokes  R L Idzerda  G S McKnight  R E Hammer  R L Brinster  S M Gartler 《Science (New York, N.Y.)》1987,236(4801):593-595

Mammalian X-chromosome inactivation involves a coordinate shutting down of physically linked genes. Several proposed models require the presence of specific sequences near genes to permit the spread of inactivation into these regions. If such models are correct, one might predict that heterologous genes transferred onto the X chromosome might lack the appropriate signal sequences and therefore escape inactivation. To determine whether a foreign gene inserted into the X chromosome is subject to inactivation, transgenic mice harboring 11 copies of the complete, 17-kilobase chicken transferrin gene on the X chromosome were used. Male mice hemizygous for this insert were bred with females bearing Searle's translocation, an X-chromosome rearrangement that is always active in heterozygous females (the unrearranged X chromosome is inactive). Female offspring bearing the Searle's translocation and the chicken transferrin gene had the same amount of chicken transferrin messenger RNA in liver as did transgenic male mice or transgenic female mice lacking the Searle's chromosome. This result shows that the inserted gene is not subject to X-chromosome inactivation and suggests that the inactivation process cannot spread over 187 kilobases of DNA in the absence of specific signal sequences required for inactivation.  相似文献   

Diversity of alpha-fetoprotein gene expression in mice is generated by a combination of separate enhancer elements   总被引：74，自引：0，他引：74  

R E Hammer  R Krumlauf  S A Camper  R L Brinster  S M Tilghman 《Science (New York, N.Y.)》1987,235(4784):53-58

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Enhanced bonding of gold nanoparticles on oxidized TiO2(110)     

Matthey D  Wang JG  Wendt S  Matthiesen J  Schaub R  Laegsgaard E  Hammer B  Besenbacher F 《Science (New York, N.Y.)》2007,315(5819):1692-1696

We studied the nucleation of gold clusters on TiO2(110) surfaces in three different oxidation states by high-resolution scanning tunneling microscopy. The three TiO2(110) supports chosen were (i) reduced (having bridging oxygen vacancies), (ii) hydrated (having bridging hydroxyl groups), and (iii) oxidized (having oxygen adatoms). At room temperature, gold nanoclusters nucleate homogeneously on the terraces of the reduced and oxidized supports, whereas on the hydrated TiO2(110) surface, clusters form preferentially at the step edges. From interplay with density functional theory calculations, we identified two different gold-TiO2(110) adhesion mechanisms for the reduced and oxidized supports. The adhesion of gold clusters is strongest on the oxidized support, and the implications of this finding for catalytic applications are discussed.  相似文献   

First detection of Edwardsiella ictaluri (Proteobacteria: Enterobacteriaceae) in wild Australian catfish          下载免费PDF全文

E Kelly  P A J Martin  S Gibson‐Kueh  D L Morgan  B C Ebner  J Donaldson  N Buller  D A Crook  S Brooks  A M Davis  M P Hammer  L Foyle  S Hair  A J Lymbery 《Journal of fish diseases》2018,41(2):199-208

The bacterium Edwardsiella ictaluri is considered to be one of the most significant pathogens of farmed catfish in the United States of America and has also caused mortalities in farmed and wild fishes in many other parts of the world. E. ictaluri is not believed to be present in wild fish populations in Australia, although it has previously been detected in imported ornamental fishes held in quarantine facilities. In an attempt to confirm freedom from the bacterium in Australian native fishes, we undertook a risk‐based survey of wild catfishes from 15 sites across northern Australia. E. ictaluri was detected by selective culturing, followed by DNA testing, in Wet Tropics tandan (Tandanus tropicanus) from the Tully River, at a prevalence of 0.40 (95% CI 0.21–0.61). The bacterium was not found in fishes sampled from any of the other 14 sites. This is the first report of E. ictaluri in wild fishes in Australia.  相似文献