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11.
Ott M Prestele M Bauerschmitt H Funes S Bonnefoy N Herrmann JM 《The EMBO journal》2006,25(8):1603-1610
The genome of mitochondria encodes a small number of very hydrophobic polypeptides that are inserted into the inner membrane in a cotranslational reaction. The molecular process by which mitochondrial ribosomes are recruited to the membrane is poorly understood. Here, we show that the inner membrane protein Mba1 binds to the large subunit of mitochondrial ribosomes. It thereby cooperates with the C-terminal ribosome-binding domain of Oxa1, which is a central component of the insertion machinery of the inner membrane. In the absence of both Mba1 and the C-terminus of Oxa1, mitochondrial translation products fail to be properly inserted into the inner membrane and serve as substrates of the matrix chaperone Hsp70. We propose that Mba1 functions as a ribosome receptor that cooperates with Oxa1 in the positioning of the ribosome exit site to the insertion machinery of the inner membrane. 相似文献
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Oaks (Quercus) are major components of temperate forest ecosystems in the Northern Hemisphere where they form intermediate or climax communities. Sessile oak (Quercus petraea) forests represent the climax vegetation in eastern Germany and western Poland. Here, sessile oak forms pure stands or occurs intermixed with Scots Pine (Pinus sylvestris). A large body of research is available on gene flow, reproduction dynamics, and genetic structure in fragmented landscapes and mixed populations. At the same time, our knowledge regarding large, contiguous, and monospecific populations is considerably less well developed. Our study is an attempt to further develop our understanding of the reproduction ecology of sessile oak as an ecologically and economically important forest tree by analyzing mating patterns and genetic structure within adult trees and seedlings originating from one or two reproduction events in an extensive, naturally regenerating sessile oak forest. We detected positive spatial genetic structure up to 30 meters between adult trees and up to 40 meters between seedlings. Seed dispersal distances averaged 8.4 meters. Pollen dispersal distances averaged 22.6 meters. In both cases, the largest proportion of the dispersal occurred over short distances. Dispersal over longer distances was more common for pollen but also appeared regularly for seeds. The reproductive success of individual trees was highly skewed. Only 41 percent of all adult trees produced any offspring while the majority did not participate in reproduction. Among those trees that contributed to the analyzed seedling sample, 80 percent contributed 1–3 gametes. Only 20 percent of all parent trees contributed four or more gametes. However, these relatively few most fertile trees contributed 51 percent of all gametes within the seedling sample. Vitality and growth differed significantly between reproducing and nonreproducing adult trees with reproducing trees being more vital and vigorous than nonreproducing individuals. Our study demonstrates that extensive, apparently homogenous oak forests are far from uniform on the genetic level. On the contrary, they form highly complex mosaics of remarkably small local neighborhoods. This counterbalances the levelling effect of long‐distance dispersal and may increase the species’ adaptive potential. Incorporating these dynamics in the management, conservation, and restoration of oak forests can support the conservation of forest genetic diversity and assist those forests in coping with environmental change. 相似文献
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Dominik Karch Keun-Sun Kim Katarzyna Wochner Heike Philippi Joachim Pietz Hartmut Dickhaus 《Journal of biomechanics》2010,43(9):1844-1848
In motion capture applications using electromagnetic tracking systems the process of anatomical calibration associates the technical frames of sensors attached to the skin with the human anatomy. Joint centers and axes are determined relative to these frames. A change of orientation of the sensor relative to the skin renders this calibration faulty. This sensitivity regarding sensor displacement can turn out to be a serious problem with movement recordings of several minutes duration. We propose the “dislocation distance” as a novel method to quantify sensor displacement and to detect gradual and sudden changes of sensor orientation. Furthermore a method to define a so called fixed technical frame is proposed as a robust reference frame which can adapt to a new sensor orientation on the skin. The proposed methods are applied to quantify the effects of sensor displacement of 120 upper and lower limb movement recordings of newborns revealing the need for a method to compensate for sensor displacement. The reliability of the fixed technical frame is quantified and it is shown that trend and dispersion of the dislocation distance can be significantly reduced. A working example illustrates the consequences of sensor displacement on derived angle time series and how they are avoided using the fixed technical frame. 相似文献
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Purinergic Signalling - 相似文献
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Marion Haensler Heike Schuerer Ulrich Hahn Hans-Dieter Jakubke 《Nucleosides, nucleotides & nucleic acids》2013,32(7):1267-1274
Abstract Synthesis of guanylyl(3′→5′)cytidine catalysed by RNase T1 variants (Tyr42Trp, Tyr24Trp and GluSSAla) was studied in frozen aqueous systems at-10°C and in solution at 0°C. Freezing the reaction mixture resulted in significantly enhanced dinucleoside monophosphate yields independently of the effect of mutation on substrate binding and catalytic mechanism. We assume that the protonation state of the catalytic residues is influenced by freezing, possibly due to conformational changes of the enzyme proteins. 相似文献
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Joanne Van Der Velden Grace Sum Donna Barker Emmanuel Koumoundouros Garry Barcham Heike Wulff Neil Castle Peter Bradding Kenneth Snibson 《PloS one》2013,8(6)