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91.
Dagmar Zunner Hans-Christian Kornau 《Biochemical and biophysical research communications》2010,393(2):185-189
GABAB receptors mediate slow inhibitory effects of the neurotransmitter γ-aminobutyric acid (GABA) on synaptic transmission in the central nervous system. They function as heterodimeric G-protein-coupled receptors composed of the seven-transmembrane domain proteins GABAB1 and GABAB2, which are linked through a coiled-coil interaction. The ligand-binding subunit GABAB1 is at first retained in the endoplasmic reticulum and is transported to the cell surface only upon assembly with GABAB2. Here, we report that GABAB1, via the coiled-coil domain, can also bind to soluble proteins of unknown function, that are affected in 22q11 deletion/DiGeorge syndrome and are therefore referred to as DiGeorge critical region 6 (DGCR6). In transfected neurons the GABAB1-DGCR6 association resulted in a redistribution of both proteins into intracellular clusters. Furthermore, the C-terminus of GABAB2 interfered with the novel interaction, consistent with heterodimer formation overriding transient DGCR6-binding to GABAB1. Thus, sequential coiled-coil interactions may direct GABAB1 into functional receptors. 相似文献
92.
Plants cope with cadmium (Cd) stress by complexation with phytochelatins (Pc), metallothioneins and glutathione and sequestration within vacuoles. Especially glutathione was found to play a major role in Cd detoxification as Cd shows a high binding affinity towards thiols and as glutathione is a precursor for Pc synthesis. In the present study, we have used an immunohistochemical approach combined with computer-supported transmission electron microscopy in order to measure changes in the subcellular distribution of glutathione during Cd-stress in mesophyll cells and cells of different glandular trichomes (long and short stalked) of Cucurbita pepo L. subsp. pepo var. styriaca Greb. Even though no ultrastructural alterations were observed in leaf and glandular trichome cells after the treatment of plants with 50 µM cadmium chloride (CdCl2) for 48 h, all cells showed a large decrease in glutathione contents. The strongest decrease was found in nuclei and the cytosol (up to 76%) in glandular trichomes which are considered as a major side of Cd accumulation in leaves. The ratio of glutathione between the cytosol and nuclei and the other cell compartments was strongly decreased only in glandular trichomes (more than 50%) indicating that glutathione in these two cell compartments is especially important for the detoxification of Cd in glandular trichomes. Additionally, these data indicate that large amounts of Cd are withdrawn from nuclei during Cd exposure. The present study gives a detailed insight into the compartment-specific importance of glutathione during Cd exposure in mesophyll cells and glandular trichomes of C. pepo L. plants. 相似文献
93.
Terminal deoxynucleotidyl transferase (TdT) contributes to the junctional diversity of immunoglobulin and T-cell receptors
by incorporating nucleotides in a template-independent manner. A closely related enzyme, polymerase μ (polμ), a template-directed
polymerase, plays a role in general end-joining double-strand break repair. We cloned zebrafish TdT and polμ and found them
to be 43% identical in amino acid sequence. Comparisons with sequences of other species revealed conserved residues typical
for TdT in the zebrafish sequence that support the template independence of this enzyme. Some but not all of these features
were identified in zebrafish polμ. In adult fish, TdT expression was most prominent in thymus, pro- and mesonephros, the primary
lymphoid organs in teleost fish and in spleen, intestine, and the tissue around the intestine. Polμ expression was detected
not only in pro- and mesonephros, the major sites for B-lymphocyte development, but also in ovary and testis and in all tissue
preparations to a low extent. TdT expression starts at 4 dpf and increases thereafter. Polμ is expressed at all times to a
similar extent. In situ studies showed a strong expression of TdT and polμ in the thymic cortex of 8-week-old fish. The characterization
of zebrafish TdT and polμ provide new insights in fish lymphopoiesis and addresses the importance and evolution of TdT and
polμ themselves. 相似文献
94.
Trefzer A Jungmann V Molnár I Botejue A Buckel D Frey G Hill DS Jörg M Ligon JM Mason D Moore D Pachlatko JP Richardson TH Spangenberg P Wall MA Zirkle R Stege JT 《Applied and environmental microbiology》2007,73(13):4317-4325
Discovery of the CYP107Z subfamily of cytochrome P450 oxidases (CYPs) led to an alternative biocatalytic synthesis of 4'-oxo-avermectin, a key intermediate for the commercial production of the semisynthetic insecticide emamectin. However, under industrial process conditions, these wild-type CYPs showed lower yields due to side product formation. Molecular evolution employing GeneReassembly was used to improve the regiospecificity of these enzymes by a combination of random mutagenesis, protein structure-guided site-directed mutagenesis, and recombination of multiple natural and synthetic CYP107Z gene fragments. To assess the specificity of CYP mutants, a miniaturized, whole-cell biocatalytic reaction system that allowed high-throughput screening of large numbers of variants was developed. In an iterative process consisting of four successive rounds of GeneReassembly evolution, enzyme variants with significantly improved specificity for the production of 4'-oxo-avermectin were identified; these variants could be employed for a more economical industrial biocatalytic process to manufacture emamectin. 相似文献
95.
Baculovirus DNA binding protein (DBP) binds preferentially single-stranded DNA in vitro and colocalizes with viral DNA replication sites. Here, its putative role as viral replication factor has been addressed by RNA interference. Silencing of DBP in Autographa californica multiple nucleopolyhedrovirus-infected cells increased expression of LEF-3, LEF-4, and P35. In contrast, expression of the structural genes coding for P39 and polyhedrin was suppressed while expression of genes coding for P10 and GP64 was unaffected. In the absence of DBP, viral DNA replication sites were formed, indicating replication of viral DNA. Electron microscopy studies, however, revealed a loss of formation of polyhedra and virus envelopment, suggesting that the primary role of DBP is viral formation rather than viral DNA replication. 相似文献
96.
In honeybees (Apis mellifera), the biogenic amine octopamine has been shown to play a role in associative and non-associative learning and in the division
of labour in the hive. Immunohistochemical studies indicate that the ventral unpaired median (VUM) neurones in the suboesophageal
ganglion (SOG) are putatively octopaminergic and therefore might be involved in the octopaminergic modulation of behaviour.
In contrast to our knowledge about the behavioural effects of octopamine, only one neurone (VUMmx1) has been related to a
behavioural effect (the reward function during olfactory learning). In this study, we have investigated suboesophageal VUM
neurones with fluorescent dye-tracing techniques and intracellular recordings combined with intracellular staining. Ten different
VUM neurones have been found including six VUM neurones innervating neuropile regions of the brain and the SOG exclusively
(central VUM neurones) and four VUM neurones with axons in peripheral nerves (peripheral VUM neurones). The central VUM neurones
innervate the antennal lobes, the protocerebral lobes (including the lateral horn) and the mushroom body calyces. Of these,
a novel mandibular VUM neurone, VUMmd1, exhibits the same branching pattern in the brain as VUMmx1 and responds to sucrose
and odours in a similar way. The peripheral VUM neurones innervate the antennal and the mandibular nerves. In addition, we
describe one labial unpaired median neurone with a dorsal cell body, DUMlb1. The possible homology between the honeybee VUM
neurones and the unpaired median neurones in other insects is discussed.
This work was supported by the DFG ME 365/24-2. 相似文献
97.
Tropheryma whipplei in the Environment: Survey of Sewage Plant Influxes and Sewage Plant Workers 下载免费PDF全文
Maximilian Schniger-Hekele Dagmar Petermann Beate Weber Christian Müller 《Applied microbiology》2007,73(6):2033-2035
We studied the prevalence of Tropheryma whipplei in influxes to 46 sewage treatment plants and in stool, mouthwash fluids, and dental plaques of 64 healthy workers in those facilities and 146 disease control patients. T. whipplei was found in sewage water, in stool of healthy individuals, and significantly more often in stool of workers exposed to sewage water. 相似文献
98.
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100.
The evolutionary development of mammals involves mutations and fixations of chromosomal types. The Y chromosome polymorphism in cattle is important for the breeding strategy, since chromosomal incompatibilities in crossings result in fertility problems. In bulls of various breeds in Switzerland, data on chromosome status have been collected for over 20 years. Data from 7 years were analysed in this study through chromosome measurements and their normalization. Some highly significant differences were found between the 7 groups of breeds, especially between Holsteins and the original Swiss breeds Braunvieh and Simmental. Fleckvieh (purebred or crossbred) did not differ significantly from Black or Red Holsteins. The results were discussed with respect to fertility problems. The observed Y chromosome polymorphism should be taken into account in breeding, and research in this field should be continued. 相似文献