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951.
952.
The Arabidopsis thylakoid transporter PHT4;1 influences phosphate availability for ATP synthesis and plant growth
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Hugues Nziengui Sonia Irigoyen Renáta Ünnep Ottó Zsiros Gergely Nagy Győző Garab Henrik Aronsson Wayne K. Versaw Cornelia Spetea 《The Plant journal : for cell and molecular biology》2015,84(1):99-110
The Arabidopsis phosphate transporter PHT4;1 was previously localized to the chloroplast thylakoid membrane. Here we investigated the physiological consequences of the absence of PHT4;1 for photosynthesis and plant growth. In standard growth conditions, two independent Arabidopsis knockout mutant lines displayed significantly reduced leaf size and biomass but normal phosphorus content. When mutants were grown in high‐phosphate conditions, the leaf phosphorus levels increased and the growth phenotype was suppressed. Photosynthetic measurements indicated that in the absence of PHT4;1 stromal phosphate was reduced to levels that limited ATP synthase activity. This resulted in reduced CO2 fixation and accumulation of soluble sugars, limiting plant growth. The mutants also displayed faster induction of non‐photochemical quenching than the wild type, in line with the increased contribution of ΔpH to the proton‐motive force across thylakoids. Small‐angle neutron scattering showed a smaller lamellar repeat distance, whereas circular dichroism spectroscopy indicated a perturbed long‐range order of photosystem II (PSII) complexes in the mutant thylakoids. The absence of PHT4;1 did not alter the PSII repair cycle, as indicated by wild‐type levels of phosphorylation of PSII proteins, inactivation and D1 protein degradation. Interestingly, the expression of genes for several thylakoid proteins was downregulated in the mutants, but the relative levels of the corresponding proteins were either not affected or could not be discerned. Based on these data, we propose that PHT4;1 plays an important role in chloroplast phosphate compartmentation and ATP synthesis, which affect plant growth. It also maintains the ionic environment of thylakoids, which affects the macro‐organization of complexes and induction of photoprotective mechanisms. 相似文献
953.
Christian Bech Christensen Henrik Lauridsen Jakob Christensen-Dalsgaard Michael Pedersen Peter Teglberg Madsen 《Proceedings. Biological sciences / The Royal Society》2015,282(1802)
Early tetrapods faced an auditory challenge from the impedance mismatch between air and tissue in the transition from aquatic to terrestrial lifestyles during the Early Carboniferous (350 Ma). Consequently, tetrapods may have been deaf to airborne sounds for up to 100 Myr until tympanic middle ears evolved during the Triassic. The middle ear morphology of recent urodeles is similar to that of early ‘lepospondyl’ microsaur tetrapods, and experimental studies on their hearing capabilities are therefore useful to understand the evolutionary and functional drivers behind the shift from aquatic to aerial hearing in early tetrapods. Here, we combine imaging techniques with neurophysiological measurements to resolve how the change from aquatic larvae to terrestrial adult affects the ear morphology and sensory capabilities of salamanders. We show that air-induced pressure detection enhances underwater hearing sensitivity of salamanders at frequencies above 120 Hz, and that both terrestrial adults and fully aquatic juvenile salamanders can detect airborne sound. Collectively, these findings suggest that early atympanic tetrapods may have been pre-equipped to aerial hearing and are able to hear airborne sound better than fish on land. When selected for, this rudimentary hearing could have led to the evolution of tympanic middle ears. 相似文献
954.
955.
Ann?BrinkmalmEmail author Gunnar?Brinkmalm William?G?Honer Lutz?Fr?lich Lucrezia?Hausner Lennart?Minthon Oskar?Hansson Anders?Wallin Henrik?Zetterberg Kaj?Blennow Annika??hrfelt 《Molecular neurodegeneration》2014,9(1):53
Background
Synaptic degeneration is an early pathogenic event in Alzheimer’s disease, associated with cognitive impairment and disease progression. Cerebrospinal fluid biomarkers reflecting synaptic integrity would be highly valuable tools to monitor synaptic degeneration directly in patients. We previously showed that synaptic proteins such as synaptotagmin and synaptosomal-associated protein 25 (SNAP-25) could be detected in pooled samples of cerebrospinal fluid, however these assays were not sensitive enough for individual samples.Results
We report a new strategy to study synaptic pathology by using affinity purification and mass spectrometry to measure the levels of the presynaptic protein SNAP-25 in cerebrospinal fluid. By applying this novel affinity mass spectrometry strategy on three separate cohorts of patients, the value of SNAP-25 as a cerebrospinal fluid biomarker for synaptic integrity in Alzheimer’s disease was assessed for the first time. We found significantly higher levels of cerebrospinal fluid SNAP-25 fragments in Alzheimer’s disease, even in the very early stages, in three separate cohorts. Cerebrospinal fluid SNAP-25 differentiated Alzheimer’s disease from controls with area under the curve of 0.901 (P?<?0.0001).Conclusions
We developed a sensitive method to analyze SNAP-25 levels in individual CSF samples that to our knowledge was not possible previously. Our results support the notion that synaptic biomarkers may be important tools for early diagnosis, assessment of disease progression, and to monitor drug effects in treatment trials.956.
Cajsa Älgenäs Charlotta Agaton Linn Fagerberg Anna Asplund Lisa Björling Erik Björling Caroline Kampf Emma Lundberg Peter Nilsson Anja Persson Kenneth Wester Fredrik Pontén Henrik Wernérus Mathias Uhlén Jenny Ottosson Takanen Sophia Hober 《Biotechnology journal》2014,9(3):435-445
An important concern for the use of antibodies in various applications, such as western blot (WB) or immunohistochemistry (IHC), is specificity. This calls for systematic validations using well‐designed conditions. Here, we have analyzed 13 000 antibodies using western blot with lysates from human cell lines, tissues, and plasma. Standardized stratification showed that 45% of the antibodies yielded supportive staining, and the rest either no staining (12%) or protein bands of wrong size (43%). A comparative study of WB and IHC showed that the performance of antibodies is application‐specific, although a correlation between no WB staining and weak IHC staining could be seen. To investigate the influence of protein abundance on the apparent specificity of the antibody, new WB analyses were performed for 1369 genes that gave unsupportive WBs in the initial screening using cell lysates with overexpressed full‐length proteins. Then, more than 82% of the antibodies yielded a specific band corresponding to the full‐length protein. Hence, the vast majority of the antibodies (90%) used in this study specifically recognize the target protein when present at sufficiently high levels. This demonstrates the context‐ and application‐dependence of antibody validation and emphasizes that caution is needed when annotating binding reagents as specific or cross‐reactive. WB is one of the most commonly used methods for validation of antibodies. Our data implicate that solely using one platform for antibody validation might give misleading information and therefore at least one additional method should be used to verify the achieved data. 相似文献
957.
958.
Metodi Dimitrov Metodiev Henrik Sp?hr Paola Loguercio Polosa Caroline Meharg Christian Becker Janine Altmueller Bianca Habermann Nils-G?ran Larsson Benedetta Ruzzenente 《PLoS genetics》2014,10(2)
Biogenesis of mammalian mitochondrial ribosomes requires a concerted maturation of both the small (SSU) and large subunit (LSU). We demonstrate here that the m5C methyltransferase NSUN4, which forms a complex with MTERF4, is essential in mitochondrial ribosomal biogenesis as mitochondrial translation is abolished in conditional Nsun4 mouse knockouts. Deep sequencing of bisulfite-treated RNA shows that NSUN4 methylates cytosine 911 in 12S rRNA (m5C911) of the SSU. Surprisingly, NSUN4 does not need MTERF4 to generate this modification. Instead, the NSUN4/MTERF4 complex is required to assemble the SSU and LSU to form a monosome. NSUN4 is thus a dual function protein, which on the one hand is needed for 12S rRNA methylation and, on the other hand interacts with MTERF4 to facilitate monosome assembly. The presented data suggest that NSUN4 has a key role in controlling a final step in ribosome biogenesis to ensure that only the mature SSU and LSU are assembled. 相似文献
959.
We recently showed that a Rab protein, CPRabA5e (CP = chloroplast localized), is located in chloroplasts of Arabidopsis thaliana where it is involved in various processes, such as thylakoid biogenesis and vesicle transport. Using a yeast two-hybrid method, CPRabA5e was shown to interact with a number of chloroplast proteins, including the CURVATURE THYLAKOID 1A (CURT1A) protein and the light-harvesting chlorophyll a/b binding protein (LHCB1.5). CURT1A has recently been shown to modify thylakoid architecture by inducing membrane curvature in grana, whereas LHCB1.5 is a protein of PSII (Photosystem II) facilitating light capture. LHCB1.5 is imported to chloroplasts and transported to thylakoid membranes using the post-translational Signal Recognition Particle (SRP) pathway. With this information as starting point, we here discuss their subsequent protein-protein interactions, given by the literature and Interactome 3D. CURT1A itself and several of the proteins interacting with CURT1A and LHCB1.5 have relations to vesicle transport and thylakoid morphology, which are also characteristics of cprabA5e mutants. This highlights the previous hypothesis of an alternative thylakoid targeting pathway for LHC proteins using vesicles, in addition to the SRP pathway. 相似文献