A Practical and Modular Method for Direct C-H Functionalization of the BODIPY Core via Thianthrenium Salts.

Direct structural modification of small-molecule fluorophores represents a straightforward and appealing strategy for accessing new fluorescent dyes with desired functionalities. We report herein a general and efficient visible-light-mediated method for the direct C-H functionalization of BODIPY, an important fluorescent chromophore, using readily accessible and bench-stable aryl and alkenylthianthrenium salts. This practical approach operates at room temperature with extraordinary site-selectivity, providing a step-economical means to construct various valuable aryl- and alkenyl-substituted BODIPY dyes. Remarkably, this protocol encompasses a broad substrate scope and excellent functional-group tolerance, and allows for the modular synthesis of sophisticated symmetrical and asymmetrical disubstituted BODIPYs by simply employing different combinations of thianthrenium salts. Moreover, the late-stage BODIPY modification of complex drug molecules further highlights the potential of this novel methodology in the synthesis of fluorophore-drug conjugates.

Calcium store refilling and STIM activation in STIM- and Orai-deficient cell lines.

Mediated through the combined action of STIM proteins and Orai channels, store-operated Ca2+ entry (SOCE) functions ubiquitously among different cell types. The existence of multiple STIM and Orai genes has made it difficult to assign specific roles of each STIM and Orai homolog in mediating Ca2+ signals. Using CRISPR/Cas9 gene editing tools, we generated cells with both STIM or all three Orai homologs deleted and directly monitored store Ca2+ and Ca2+ signals. We found that unstimulated, SOCE null KO cells still retain 50~70% of ER Ca2+ stores of wildtype (wt) cells. After brief exposure to store-emptying conditions, acute refilling of ER Ca2+ stores was totally blocked in KO cells. However, after 24 h in culture, stores were eventually refilled. Thus, SOCE is critical for immediate refilling of ER Ca2+ but is dispensable for the maintenance of long-term ER Ca2+ homeostasis. Using the Orai null background triple Orai-KO cells, we examined the plasma membrane translocation properties of a series of truncated STIM1 variants. FRET analysis reveals that, even though PM tethering of STIM1 expedites the activation of STIM1 by facilitating its oligomerization, migration, and accumulation in ER-PM junctions, it is not required for the conformational switch, oligomerization, and clustering of STIM1. Even without overt puncta formation at ER-PM junctions, STIM11-491 and STIM11-666 could still rescue SOCE when expressed in STIM KO cells. Thus, ER-PM trapping and clustering of STIM molecules only facilitates the process of SOCE activation, but is not essential for the activation of Orai channels.

Specific binding of activated Vip3Aa10 to Helicoverpa armigera brush border membrane vesicles results in pore formation.

Helicoverpa armigera is one of the most harmful pests in China. Although it had been successfully controlled by Cry1A toxins, some H. armigera populations are building up resistance to Cry1A toxins in the laboratory. Vip3A, secreted by Bacillus thuringiensis, is another potential toxin against H. armigera. Previous reports showed that activated Vip3A performs its function by inserting into the midgut brush border membrane vesicles (BBMV) of susceptible insects. To further investigate the binding of Vip3A to BBMV of H. armigera, the full-length Vip3Aa10 toxin expressed in Escherichia coli was digested by trypsin or midgut juice extract, respectively. Among the fragments of digested Vip3Aa10, only a 62kDa fragment (Vip3Aa10-T) exhibited binding to BBMV of H. armigera and has insecticidal activity. Moreover, this interaction was specific and was not affected by the presence of Cry1Ab toxin. Binding of Vip3Aa10-T to BBMV resulted in the formation of an ion channel. Unlike Cry1A toxins, Vip3Aa10-T was just slightly associated with lipid rafts of BBMV. These data suggest that although activated Vip3Aa10 specifically interacts with BBMV of H. armigera and forms an ion channel, the mode of action of it may be different from that of Cry1A toxins.

[Effects of cropping patterns on photosynthesis characteristics of summer maize and its utilization of solar and heat resources].

In order to investigate the effects of interplanting and direct seeding on the photosynthesis characteristics of summer maize and its utilization of solar and heat resources, two summer maize cultivars (Zhengdan 958 and Denghai 661) were planted in the farmlands of Denghai Seed Co. Ltd in Laizhou City of Shandong Province, with 67500 plants x hm(-2) and three sowing dates. The above-ground biomass, plant growth rate, leaf area index, and net photosynthetic rate per ear leaf were measured to reveal the photosynthesis characteristics of test cultivars. In the meantime, the characters of grain-filling were simulated by Richards' model, and the solar resource utilization efficiency of the cultivars was calculated, in combining with meteorological data. Comparing with interplanting, direct seeding increased the grain yield by 1.17%-3.33%, but decreased the thousand-grain weight significantly. Growth stages were extended under earlier sowing. The leaf area index and net photosynthetic rate from flowering to 30 d after anthesis were significantly higher under direct seeding than under interplanting, but after then, they decreased faster. Direct seeding induced a higher accumulation of dry matter and a faster plant growth rate before and after flowering. Under direct seeding, the maximum grain-filling rate reached earlier, the starting potential was higher, but the grain-filling period, active grain-filling period, and W(max) were lower, compared with those under interplanting. Also under direct seeding, the total accumulative temperature and solar radiation during growth period decreased by 150-350 degrees C x d and 200-400 MJ x m(-2), respectively, but the solar resource utilization efficiency of grain increased by 10.5%-24.7%. All the results suggested that direct seeding was superior to interplanting for the summer maize production under field condition. In order to enhance solar and heat utilization efficiency and excavate yield potential, it would be essential to improve the leaf photosynthesis efficiency and postpone leaf aging.

[Leaf redundancy of high-yielding maize (Zea may L.) and its effects on maize yield and photosynthesis].

According to the maize yield at plant density of 15000 ind x hm(-2) in 2007, the leaf-redundant type (cultivar Chaoshi 1) and non-redundant type (cultivar Chaoshi 3) at low plant density were selected, and the changes of their above-ground dry matter accumulation and grain yield after cutting all leaves to 1/2 (T1) and 1/4 (T2) at anthesis at the optimal density and under high-yielding condition were analyzed in 2008, aimed to approach whether the leaf redundancy exists in high-yielding maize colonies. The characters of grain-filling were simulated by Richards' model, and the photosynthetic characteristics and chlorophyll fluorescence of the leaves on ear position were determined to reveal the activities of photosynthesis after the removal of redundancy. The results showed that at optimal plant density and under high-yielding condition, both the redundant and non-redundant types had leaf redundancy. The characterization of grain-filling by Richards' model indicated that appropriately removing redundant leaves could increase the net photosynthetic rate and solar energy use efficiency of the leaves on ear position, extend the active period of grain-filling, and enhance the grain yield.

N-[3-Chloro-4-(3-fluoro-benz-yloxy)phen-yl]-6-iodo-quinazolin-4-amine.

In the title mol-ecule, C(21)H(14)ClFIN(3)O, the bicyclic ring system has a twisted conformation; the two fused rings form a dihedral angle of 4.5 (1)°. The dihedral angles between the fused ring system and the benzene rings are 27.3 (6) and 5.3 (5)° while the dihedral angle between the benzene rings is 22.0 (5)°. In the crystal structure, weak inter-molecular N-H⋯N hydrogen bonds link the mol-ecules into chains propagating in [100]. A short inter-molecular distance of 3.806 (3) Šbetween the centroids of the fluorobenzene and iodobenzene rings suggests the existence of π-π stacking inter-actions.

[Dynamic changes of soil microbial populations and enzyme activities in super-high yielding summer maize farmland soil].

To reveal the characteristics of the dynamic changes of soil microbial populations and enzyme activities in super-high yielding ( > 15,000 kg x hm(-2)) summer maize farmland soil, a comparative study was conducted in the experimental fields in National Maize Engineering Research Center (Shandong). On the fields with an annual yield of >15,000 kg x hm(-2) in continuous three years, a plot with the yield of 20 322 kg x hm(-2) (HF) was chosen to make comparison with the conventional farmland (CF) whose maize yield was 8920. 1 kg x hm(-2). The numbers of bacteria, fungi, and actinomycetes as well as the activities of urease and invertase in 0-20 cm soil layer were determined. The results showed that in the growth period of maize, the numbers of bacteria, fungi, and actinomycetes in the two farmland soils increased first and declined then. At the later growth stages of maize, the numbers of soil microbes, especially those of bacteria and actinomycetes, were lower in HF than those in CF. At harvest stage, the ratio of the number of soil bacteria to fungi (B/ F) in HF was 2.03 times higher than that at sowing stage, and 3.02 times higher than that in CF. The B/F in CF had less difference at harvest and sowing stages. The soil urease activity in HF was significantly lower than that in CF at jointing stage, and the invertase activity in HF decreased rapidly after blooming stage, being significantly lower than that in CF.

Overexpression of complexin in PC12 cells inhibits exocytosis by preventing SNARE complex recycling.

Complexin is an important protein that functions during Ca2+-dependent neurotransmitter release. Substantial evidence supports that complexin performs its role through rapid interaction with SNARE complex with high affinity. However, alpha-SNAP/NSF, which can disassemble the cis-SNARE complex in the presence of MgATP, competes with complexin to bind to SNARE complex. In addition, injection of alpha-SNAP into chromaffin cells enhances the size of the readily releasable pool, and mutation disrupting the ATPase activity of NSF results in the accumulation of SNARE complex. Thus, whether high concentrations of complexin could result in a reverse result is unclear. In this paper, we demonstrate that when stably overexpressed in PC12 cells, high levels of complexin result in the accumulation of SNARE complex. This in turn leads to a reduction in the size of the readily releasable pool of large dense core vesicles. These results suggest that high levels of complexin seem to prevent SNARE complex recycling, presumably by displacing NSF and alpha-SNAP from SNARE complex.

The positively charged residues in the fragment 71 - 77 of complexin is required for its binding to SNARE complex.

Complexin is a cytoplasmic protein that plays an important role in the neurotransmitters release triggered by action potential. Previous studies suggested that complexin performs its functions through interaction with the SNARE complex. The crystal structure of complexin/SNARE complex revealed that complexin binds to SNARE core complex in an anti-parallel conformation with its residues 48 - 70. However, the functions of the flanking sequences are unclear. In this paper, we demonstrate that the fragment 71 - 77 of complexin is indispensable for its binding to the SNARE complex. Moreover, this interaction can be impaired by abolishing the positive charges in the fragment 71 - 77, which suggests that the positive charges in the fragment 71 - 77 are important for the interaction between complexin II and the SNARE complex.

Complexin is able to bind to SNARE core complexes in different assembled states with distinct affinity.

The formation of the functional SNARE complex in vivo is central to the fast neurotransmitter release at the neuronal terminal. Numerous studies revealed that this process involves progressive assembly of an alpha-helical bundle and is dynamically reversible. So far many proteins directly or indirectly take part in this process. Complexin, one of such factors, has revealed rapid association with the SNARE complex, however, whether or not complexin can interact with partially assembled SNARE complex is critical and yet unknown. Here, we present evidence that complexin is able to bind to various mutant versions of the SNARE complex mimicking its quaternary structure at different assembly stages. In addition, the affinity of complexin for the SNARE complex is correlated with the extent to which the SNARE complex is assembled. These results suggest that complexin is able to bind to SNARE complex before its complete formation.