Limits to growth of forest biomass carbon sink under climate change.

Widely recognized as a significant carbon sink, North American forests have experienced a history of recovery and are facing an uncertain future. This growing carbon sink is dictated by recovery from land-use change, with growth trajectory modified by environmental change. To address both processes, we compiled a forest inventory dataset from North America to quantify aboveground biomass growth with stand age across forest types and climate gradients. Here we show, the biomass grows from 90 Mg ha-1 (2000-2016) to 105 Mg ha-1 (2020 s), 128 Mg ha-1 (2050 s), and 146 Mg ha-1 (2080 s) under climate change scenarios with no further disturbances. Climate change modifies the forest recovery trajectory to some extent, but the overall growth is limited, showing signs of biomass saturation. The future (2080s) biomass will only sequester at most 22% more carbon than the current level. Given such a strong sink has limited growth potential, our ground-based analysis suggests policy changes to sustain the carbon sink

PSR J1926-0652: A Pulsar with Interesting Emission Properties Discovered at FAST

We describe PSR J1926-0652, a pulsar recently discovered with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Using sensitive single-pulse detections from FAST and long-term timing observations from the Parkes 64-m radio telescope, we probed phenomena on both long and short time scales. The FAST observations covered a wide frequency range from 270 to 800 MHz, enabling individual pulses to be studied in detail. The pulsar exhibits at least four profile components, short-term nulling lasting from 4 to 450 pulses, complex subpulse drifting behaviours and intermittency on scales of tens of minutes. While the average band spacing P3 is relatively constant across different bursts and components, significant variations in the separation of adjacent bands are seen, especially near the beginning and end of a burst. Band shapes and slopes are quite variable, especially for the trailing components and for the shorter bursts. We show that for each burst the last detectable pulse prior to emission ceasing has different properties compared to other pulses. These complexities pose challenges for the classic carousel-type models.Comment: 13pages with 12 figure

Low temperature, mechanical wound, and exogenous salicylic acid (SA) can stimulate the SA signaling molecule as well as its downstream pathway and the formation of fruiting bodies in Flammulina filiformis

Low temperature (LT) and mechanical wound (MW), as two common physics methods, have been empirically used in production to stimulate the primordia formation of Flammulina filiformis, which is typically produced using the industrial production mode. However, the detailed effect on the fruiting body formation and important endogenous hormones and signaling pathways in this process is poorly understood. In this study, LT, MW, their combination, i.e., MW + LT, and low concentration of SA (0.1 mM SA) treatments were applied to the physiologically mature mycelia of F. filiformis. The results showed that the primordia under the four treatments began to appear on the 5th−6th days compared with the 12th day in the control (no treatment). The MW + LT treatment produced the largest number of primordia (1,859 per bottle), followed by MW (757), SA (141), and LT (22), compared with 47 per bottle in the control. The HPLC results showed that the average contents of endogenous SA were significantly increased by 1.3 to 2.6 times under four treatments. A total of 11 SA signaling genes were identified in the F. filiformis genome, including 4 NPR genes (FfNpr1-4), 5 TGA genes (FfTga1-5), and 2 PR genes (FfPr1-2). FfNpr3 with complete conserved domains (ANK and BTB/POZ) showed significantly upregulated expression under all four above treatments, while FfNpr1/2/4 with one domain showed significantly upregulated response expression under the partial treatment of all four treatments. FfTga1-5 and FfPr1-2 showed 1.6-fold to 8.5-fold significant upregulation with varying degrees in response to four treatments. The results suggested that there was a correlation between “low temperature/mechanical wound—SA signal—fruiting body formation”, and it will help researchers to understand the role of SA hormone and SA signaling pathway genes in the formation of fruiting bodies in fungi

Direct and indirect effects of climate on richness drive the latitudinal diversity gradient in forest trees

Data accessibility statement: Full census data are available upon reasonable request from the ForestGEO data portal, http://ctfs.si.edu/datarequest/ We thank Margie Mayfield, three anonymous reviewers and Jacob Weiner for constructive comments on the manuscript. This study was financially supported by the National Key R&D Program of China (2017YFC0506100), the National Natural Science Foundation of China (31622014 and 31570426), and the Fundamental Research Funds for the Central Universities (17lgzd24) to CC. XW was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB3103). DS was supported by the Czech Science Foundation (grant no. 16-26369S). Yves Rosseel provided us valuable suggestions on using the lavaan package conducting SEM analyses. Funding and citation information for each forest plot is available in the Supplementary Information Text 1.Peer reviewedPostprin

Études structurales et biochimiques sur les complexes d'élongation de l'ARN polymérase liés aux facteurs de transcription NusG et NusA

The RNAP (RNA polymerase) is the key enzyme in transcription. RNAP is tightly regulated by factors during transcriptional cycle. Two speed control transcriptional factors (TF) NusA and NusG have the opposite effect on transcriptional pausing. The aim of my work is to use single particle Cryo-EM combine with biochemistry analysis to bring out the regulation of NusA and NusG, and both TFs together on the RNAP. We demonstrate here that RNAP itsself has a constant dynamic movement – non-swiveled to swiveled conformation. NusA stabilized the RNAP to a swiveled conformation which close to the paused state, however NusG enhance the RNAP to an non-swiveled state. NusG-CTD compete with NusA on a same binding site, the Flap-Tip-Helix (FTH) module of RNAP. The biochemistry results showed that these two FT NusA and NusG, compensate the effect of each other and modulate the transcriptional rate in different transcriptional pausing context (class I and class II pausing). However at the termination rho-dependent context, NusA and NusG together could increase the termination efficiency at the terminator I site.L'ARN-polymérase (ARNP) est l'enzyme clé de la transcription. Elle est étroitement régulée par des facteurs au cours du cycle de la transcription. Les deux facteurs NusA et NusG, ont un effet opposé sur la pause transcriptionnelle. Le but de ma thèse est d'utiliser la cryo-EM en analyse de particules isolées combinée à des analyses biochimiques pour mettre en évidence la régulation de l'ARNP par NusA et NusG, et ces deux facteurs ensemble. Nous démontrons que l'ARNP elle-même a un mouvement dynamique constant entre conformation non-pivotante et pivotante. NusA stabilise l'ARNP dans une conformation pivotante qui est proche de l'état de pause, alors que NusG favorise un état non-pivotant de l'ARNP. NusG-CTD est en compétition avec NusA sur un même site de liaison, le module Flap-Tip-Helix de l'ARNP. Les résultats biochimiques ont montré que NusA et NusG, compensent leurs effets et modulent la vitesse de transcription. Cependant, dans le contexte de la terminaison, rho-dépendante, NusA et NusG, ensemble pourraient augmenter l'efficacité de la terminaison précoce

Études structurales et biochimiques sur les complexes d'élongation de l'ARN polymérase liés aux facteurs de transcription NusG et NusA

L'ARN-polymérase (ARNP) est l'enzyme clé de la transcription. Elle est étroitement régulée par des facteurs au cours du cycle de la transcription. Les deux facteurs NusA et NusG, ont un effet opposé sur la pause transcriptionnelle. Le but de ma thèse est d'utiliser la cryo-EM en analyse de particules isolées combinée à des analyses biochimiques pour mettre en évidence la régulation de l'ARNP par NusA et NusG, et ces deux facteurs ensemble. Nous démontrons que l'ARNP elle-même a un mouvement dynamique constant entre conformation non-pivotante et pivotante. NusA stabilise l'ARNP dans une conformation pivotante qui est proche de l'état de pause, alors que NusG favorise un état non-pivotant de l'ARNP. NusG-CTD est en compétition avec NusA sur un même site de liaison, le module Flap-Tip-Helix de l'ARNP. Les résultats biochimiques ont montré que NusA et NusG, compensent leurs effets et modulent la vitesse de transcription. Cependant, dans le contexte de la terminaison, rho-dépendante, NusA et NusG, ensemble pourraient augmenter l'efficacité de la terminaison précoce.The RNAP (RNA polymerase) is the key enzyme in transcription. RNAP is tightly regulated by factors during transcriptional cycle. Two speed control transcriptional factors (TF) NusA and NusG have the opposite effect on transcriptional pausing. The aim of my work is to use single particle Cryo-EM combine with biochemistry analysis to bring out the regulation of NusA and NusG, and both TFs together on the RNAP. We demonstrate here that RNAP itsself has a constant dynamic movement – non-swiveled to swiveled conformation. NusA stabilized the RNAP to a swiveled conformation which close to the paused state, however NusG enhance the RNAP to an non-swiveled state. NusG-CTD compete with NusA on a same binding site, the Flap-Tip-Helix (FTH) module of RNAP. The biochemistry results showed that these two FT NusA and NusG, compensate the effect of each other and modulate the transcriptional rate in different transcriptional pausing context (class I and class II pausing). However at the termination rho-dependent context, NusA and NusG together could increase the termination efficiency at the terminator I site

Études structurales et biochimiques sur les complexes d'élongation de l'ARN polymérase liés aux facteurs de transcription NusG et NusA

The RNAP (RNA polymerase) is the key enzyme in transcription. RNAP is tightly regulated by factors during transcriptional cycle. Two speed control transcriptional factors (TF) NusA and NusG have the opposite effect on transcriptional pausing. The aim of my work is to use single particle Cryo-EM combine with biochemistry analysis to bring out the regulation of NusA and NusG, and both TFs together on the RNAP. We demonstrate here that RNAP itsself has a constant dynamic movement – non-swiveled to swiveled conformation. NusA stabilized the RNAP to a swiveled conformation which close to the paused state, however NusG enhance the RNAP to an non-swiveled state. NusG-CTD compete with NusA on a same binding site, the Flap-Tip-Helix (FTH) module of RNAP. The biochemistry results showed that these two FT NusA and NusG, compensate the effect of each other and modulate the transcriptional rate in different transcriptional pausing context (class I and class II pausing). However at the termination rho-dependent context, NusA and NusG together could increase the termination efficiency at the terminator I site.L'ARN-polymérase (ARNP) est l'enzyme clé de la transcription. Elle est étroitement régulée par des facteurs au cours du cycle de la transcription. Les deux facteurs NusA et NusG, ont un effet opposé sur la pause transcriptionnelle. Le but de ma thèse est d'utiliser la cryo-EM en analyse de particules isolées combinée à des analyses biochimiques pour mettre en évidence la régulation de l'ARNP par NusA et NusG, et ces deux facteurs ensemble. Nous démontrons que l'ARNP elle-même a un mouvement dynamique constant entre conformation non-pivotante et pivotante. NusA stabilise l'ARNP dans une conformation pivotante qui est proche de l'état de pause, alors que NusG favorise un état non-pivotant de l'ARNP. NusG-CTD est en compétition avec NusA sur un même site de liaison, le module Flap-Tip-Helix de l'ARNP. Les résultats biochimiques ont montré que NusA et NusG, compensent leurs effets et modulent la vitesse de transcription. Cependant, dans le contexte de la terminaison, rho-dépendante, NusA et NusG, ensemble pourraient augmenter l'efficacité de la terminaison précoce