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131.
Alanentalo T Asayesh A Morrison H Lorén CE Holmberg D Sharpe J Ahlgren U 《Nature methods》2007,4(1):31-33
A convenient technology to quantify three-dimensional (3D) morphological features would have widespread applications in biomedical research. Based on combined improvements in sample preparation, tomographic imaging and computational processing, we present a procedure for high-resolution 3D quantification of structures within intact adult mouse organs. Using the nonobese diabetic (NOD) mouse model, we demonstrate a correlation between total islet beta-cell volume and the onset of type-1 diabetes. 相似文献
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Tindaria kretensis n. sp., a minute deep-water protobranch, is described from Early Pliocene marls cropping out in the Voutes section, northern Crete Island. This is one of the few fossil records of Tindaria from the Mediterranean area, the first well documented for the Neogene. Tindaria is an almost cosmopolitan deep-water genus, absent from the modern Mediterranean. Its occurrence in the Early Pliocene is in agreement with what is known about the past psychrospheric conditions in the Mediterranean. 相似文献
135.
Qiaohan Yang Guangyu Zhou Torben Noto Jessica W. Templer Stephan U. Schuele Joshua M. Rosenow Gregory Lane Christina Zelano 《PLoS biology》2022,20(1)
Studies of neuronal oscillations have contributed substantial insight into the mechanisms of visual, auditory, and somatosensory perception. However, progress in such research in the human olfactory system has lagged behind. As a result, the electrophysiological properties of the human olfactory system are poorly understood, and, in particular, whether stimulus-driven high-frequency oscillations play a role in odor processing is unknown. Here, we used direct intracranial recordings from human piriform cortex during an odor identification task to show that 3 key oscillatory rhythms are an integral part of the human olfactory cortical response to smell: Odor induces theta, beta, and gamma rhythms in human piriform cortex. We further show that these rhythms have distinct relationships with perceptual behavior. Odor-elicited gamma oscillations occur only during trials in which the odor is accurately perceived, and features of gamma oscillations predict odor identification accuracy, suggesting that they are critical for odor identity perception in humans. We also found that the amplitude of high-frequency oscillations is organized by the phase of low-frequency signals shortly following sniff onset, only when odor is present. Our findings reinforce previous work on theta oscillations, suggest that gamma oscillations in human piriform cortex are important for perception of odor identity, and constitute a robust identification of the characteristic electrophysiological response to smell in the human brain. Future work will determine whether the distinct oscillations we identified reflect distinct perceptual features of odor stimuli.Intracranial recordings from human olfactory cortex reveal a characteristic spectrotemporal response to odors, including theta, beta and gamma oscillations, and show that high-frequency responses are critical for accurate perception of odors. 相似文献
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Tobias Ruck Stefanie Bock Steffen Pfeuffer Christina B.Schroeter Derya Cengiz Paul Marciniak Maren Lindner Alexander Herrmann Marie Liebmann Stjepana Kovac Lukas Gola Leoni Rolfes Marc Pawlitzki Nils Opel Tim Hahn Udo Dannlowski Thomas Pap Felix Luessi Julian A.Schreiber Bernhard Wünsch Tanja Kuhlmann Guiscard Seebohm Bjrn Tackenberg Patricia Seja Frank Dring Erhard Wischmeyer Achmet Imam Chasan Johannes Roth Luisa Klotz Gerd Meyer zu Hrste Heinz Wiendl Tobias Marschall Stefan Floess Jochen Huehn Thomas Budde Tobias Bopp Stefan Bittner Sven G.Meuth 《Cell research》2022,32(1):72-88
It remains largely unclear how thymocytes translate relative differences in T cell receptor (TCR) signal strength into distinct developmental programs that driv... 相似文献
138.
The functions of sexually selected traits are particularly sensitive to changes in the environment because the traits have evolved to in-crease mating success u... 相似文献
139.
Ultrastructural effects in potato leaves due to antisense-inhibition of the sucrose transporter indicate an apoplasmic mode of phloem loading 总被引:8,自引:0,他引:8
To study the export of sugars from leaves and their long-distance transport, sucrose-proton/co-transporter activity of potato
was inhibited by antisense repression of StSUT1 under control of either a ubiquitously active (CaMV 35S ) or a companion-cell-specific (rolC) promotor in transgenic plants. Transformants exhibiting reduced levels of the sucrose-transporter mRNA and showing a dramatic
reduction in root and tuber growth, were chosen to investigate the ultrastructure of their source leaves. The transformants
had a regular leaf anatomy with a single-layered palisade parenchyma, and bicollateral minor veins within the spongy parenchyma.
Regardless of the promoter used, source leaves from transformants showed an altered leaf phenotype and a permanent accumulation
of assimilates as indicated by the number and size of starch grains, and by the occurrence of lipid-storing oleosomes. Starch
accumulated throughout the leaf: in epidermis, mesophyll and, to a smaller degree, in phloem parenchyma cells of minor veins.
Oleosomes were observed equally in mesophyll and phloem parenchyma cells. Companion cells were not involved in lipid accmulation
and their chloroplasts developed only small starch grains. The similarity of ultrastructural symptoms under both promotors
corresponds to, rather than contradicts, the hypothesis that assimilates can move symplasmically from mesophyll, via the bundle
sheath, up to the phloem. The microscopical symptoms of a constitutively high sugar level in the transformant leaves were
compared with those in wild-type plants after cold-girdling of the petiole. Inhibition of sugar export, both by a reduction
of sucrose carriers in the sieve element/companion cell complex (se/cc complex), or further downstream by cold-girdling, equally
evokes the accumulation of assimilates in all leaf tissues up to the se/cc complex border. However, microscopy revealed that
antisense inhibition of loading produces a persistently high sugar level throughout the leaf, while cold-girdling leads only
to local patches containing high levels of sugar.
Received: 4 March 1998 / Accepted: 7 April 1998 相似文献
140.