Surface air temperature outputs from 16 global climate models participating in the sixth phase of the coupled model intercomparison project (CMIP6) were used to evaluate agreement with observations over the global land surface for the period 1901–2014. Projections of multi-model mean under four different shared socioeconomic pathways were also examined. The results reveal that the majority of models reasonably capture the dominant features of the spatial variations in observed temperature with a pattern correlation typically greater than 0.98, but with large variability across models and regions. In addition, the CMIP6 mean can capture the trends of global surface temperatures shown by the observational data during 1901–1940 (warming), 1941–1970 (cooling) and 1971–2014 (rapid warming). By the end of the 21st century, the global temperature under different scenarios is projected to increase by 1.18 °C/100 yr (SSP1-2.6), 3.22 °C/100 yr (SSP2-4.5), 5.50 °C/100 yr (SSP3-7.0) and 7.20 °C/100 yr (SSP5-8.5), with greater warming projected over the high latitudes of the northern hemisphere and weaker warming over the tropics and the southern hemisphere. Results of probability density distributions further indicate that large increases in the frequency and magnitude of warm extremes over the global land may occur in the future.

Arp2/3 complex initiates the growth of branched actin‐filament networks by inducing actin polymerization from the sides of pre‐existing filaments. Nucleation promoting factors (NPFs) are essential for the branching reaction through interactions with the Arp2/3 complex prior to branch formation. The modes by which NPFs bind Arp2/3 complex and associated conformational changes have remained elusive. Here, we used electron microscopy to determine three‐dimensional structures at ∼2 nm resolution of Arp2/3 complex with three different bound NPFs: N‐WASp, Scar‐VCA and cortactin. All of these structures adopt a conformation with the two actin‐related proteins in an actin‐filament‐like dimer and the NPF bound to the pointed end. Distance constraints derived by fluorescence resonance energy transfer independently verified the NPF location. Furthermore, all bound NPFs partially occlude the actin‐filament binding site, suggesting that additional local structural rearrangements are required in the pathway of Arp2/3 complex activation to allow branch formation.

It is well known that a tip-focused intracellular Ca 21 gradient and the meshwork of short actin filaments at the tip region are necessary for pollen tube growth. However, little is known about the connections between the two factors. Here, a novel Ca 21 -dependent actin-binding protein with molecular mass of 41 kD from lily (Lilium davidii) pollen (LdABP41) was isolated and purified with DNase I chromatography. Our purification procedure yielded about 0.6 mg of LdABP41 with .98% purity from 10 g of lily pollen. At least two isoforms with isoelectric points of 5.8 and 6.0 were detected on two-dimensional gels. The results of N-terminal sequencing and mass-spectrometry analysis of LdABP41 showed that both isoforms shared substantial similarity with trumpet lily (Lilium longiflorum) villin and other members of the gelsolin superfamily. Negative-stained electron microscope images showed that LdABP41 severed in vitro-polymerized lily pollen F-actin into short actin filaments in a Ca 21 -sensitive manner. Microinjection of the anti-LdABP41 antibody into germinated lily pollen demonstrated that the protein was required for pollen tube growth. The results of immunolocalization of the protein showed that it existed in the cytoplasm of the pollen tube, especially focused in the tip region. Our results suggest that LdABP41 belongs to the gelsolin superfamily and may play an important role in controlling actin organization in the pollen tube tip by responding to the oscillatory, tip-focused Ca 21 gradient.Pollen tube growth is a key process in the sexual reproduction of higher plants. It is highly polarized and requires both spatial and temporal coordination of many cellular functions, including ion fluxes, cytoskeleton organization and dynamics, vesicular trafficking, exocytosis, endocytosis, and cell wall synthesis (for review, see Taylor and Hepler, 1997;Franklin-Tong, 1999). It is widely accepted that the actin cytoskeleton plays a major role in modulation of pollen tube growth. Actin filaments, together with myosin, are a crucial element to support intracellular trafficking of organelles and secretory vesicles along actin cables that are oriented axially throughout the shank of elongating pollen tubes (Cai et al., 1997;Vidali and Hepler, 2000;Hepler et al., 2001). Although the presence and exact distribution of F-actin in the pollen tube apex has been somewhat controversial, accumulating evidence indicates that a highly dynamic array of actin filaments in the tip region may play a primary role in polarized growth. Early studies using chemically fixed cells and fluorescent-phalloidin staining indicate that there is a dense actin network at the extreme apex of pollen tubes (Pierson, 1988;Derksen et al., 1995). However, investigations with rapid freezing, freeze substitution microscopy techniques suggest that the extreme apex of pollen tubes contains little F-actin, but only occasional sparse or fine actin filaments at the extreme apex (Doris and Steer, 1996). Results obtained by microinjection of trumpet lily (Lilium lo...

Simulations from the models participating in the sixth phase of the Coupled Model Intercomparison Project (CMIP6), which represent the most recent generation of climate models, are now available. Understanding the performance of these models in simulating historical climate extremes can provide a basis for producing reliable future climate projections. Here, we assess the simulation of 16 indices of temperature extremes defined by the Expert Team on Climate Change Detection and Indices using results from 24 CMIP6 models as compared with results from CMIP5. Comparisons with observations and reanalyses indicate that the CMIP6 models could capture the spatial patterns and temporal variations of the observed temperature extremes well for some indices, although less well for others. Based on spatial and temporal skill scores, CMIP6 ensemble means were more skillful in simulating absolute and threshold indices of extreme temperature than CMIP5 ensemble means were, but the performances of both the CMIP5 and CMIP6 ensemble means in simulating the spatial patterns for duration and percentile indices were relatively unsatisfactory (spatial skill scores S < 0.3). Furthermore, our results suggest that there have been improvements in spatial pattern skill scores in some individual CMIP6 models relative to CMIP5 model scores for summer days, tropical nights, cold spell duration, and diurnal temperature range.

A metal (Co)-Organic Framework (Co-MOF) was first found to catalyze the chemiluminescence (CL) of luminol. On the basis of X-ray photoelectron spectroscopy, powder X-ray diffraction, CL spectral, UV-visible absorption spectral, and electron spin resonance (ESR) spectral studies, as well as the research of the influence of various free radical scavengers, a possible CL mechanism was proposed. The enhanced CL might be attributed to the formation of a peroxide analogous complex between the oxygen-related radicals and the active metal site of the Co-MOF material. The established Co-MOF-luminol CL system was successfully applied to determine L-cysteine (CySH), based on the selective and sensitive enhancing effect of CySH on this CL system. Under the optimized conditions, CySH was selectively detected in the range 0.1-10 μM with a detection limit of 18 nM. This novel CL system obviously gives impetus to the new research field of metal-organic frameworks (MOFs) in chemiluminescence.

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Schematic illustration for the preparation of g-CNQDs though a thermal condensation process and CL of the g-CNQDs–K3[Fe(CN)6] system.

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