SD-RLK28 positively regulates pollen hydration on stigmas as a PCP-Bβ receptor in Arabidopsis thaliana

Pollen hydration on dry stigmas is strictly regulated by pollen–stigma interactions in Brassicaceae. Although several related molecular events have been described, the molecular mechanism underlying pollen hydration remains elusive. Multiple B-class pollen coat proteins(PCP-Bs) are involved in pollen hydration. Here, by analyzing the interactions of two PCP-Bs with three Arabidopsis thaliana stigmas strongly expressing S-domain receptor kinase(SD-RLK), we determined that SD-RLK28 directly intera...     

Vanadyl bisacetylacetonate protects β cells from palmitate-induced cell death through the unfolded protein response pathway

Endoplasmic reticulum (ER) stress induced by free fatty acids (FFA) is important to β-cell loss during the development of type 2 diabetes. To test whether vanadium compounds could influence ER stress and the responses in their mechanism of antidiabetic effects, we investigated the effects and the mechanism of vanadyl bisacetylacetonate [VO(acac)₂] on β cells upon treatment with palmitate, a typical saturated FFA. The experimental results showed that VO(acac)₂ could enhance FFA-induced signaling pathways of unfolded protein responses by upregulating the prosurvival chaperone immunoglobulin heavy-chain binding protein/78-kDa glucose-regulated protein and downregulating the expression of apoptotic C/EBP homologous protein, and consequently the reduction of insulin synthesis. VO(acac)₂ also ameliorated FFA-disturbed Ca²⁺ homeostasis in β cells. Overall, VO(acac)₂ enhanced stress adaption, thus protecting β cells from palmitate-induced apoptosis. This study provides some new insights into the mechanisms of antidiabetic vanadium compounds.     

Efficiency Boost in All-Small-Molecule Organic Solar Cells: Insights from the Re-Ordering Kinetics

Achieving high-performance in all-small-molecule organic solar cells (ASM-OSCs) significantly relies on precise nanoscale phase separation through domain size manipulation in the active layer. Nonetheless, for ASM-OSC systems, forging a clear connection between the tuning of domain size and the intricacies of phase separation proves to be a formidable challenge. This study investigates the intricate interplay between domain size adjustment and the creation of optimal phase separation morphology, crucial for ASM-OSCs’ performance. It is demonstrated that exceptional phase separation in ASM-OSCs’ active layer is achieved by meticulously controlling the continuity and uniformity of domains via re-packing process. A series of halogen-substituted solvents (Fluorobenzene, Chlorobenzene, Bromobenzene, and Iodobenzene) is adopted to tune the re-packing kinetics, the ASM-OSCs treated with CB exhibited an impressive 16.2% power conversion efficiency (PCE). The PCE enhancement can be attributed to the gradual crystallization process, promoting a smoothly interconnected and uniformly distributed domain size. This, in turn, leads to a favorable phase separation morphology, enhanced charge transfer, extended carrier lifetime, and consequently, reduced recombination of free charges. The findings emphasize the pivotal role of re-packing kinetics in achieving optimal phase separation in ASM-OSCs, offering valuable insights for designing high-performance ASM-OSCs fabrication strategies.     

Extracellular expression, purification, and characterization of a winter flounder antifreeze polypeptide from Escherichia coli

HPLC6 is the major component of liver-type antifreeze polypeptides (AFPs) from the winter flounder, Pleuronectes americanus. To facilitate mutagenesis studies of this protein, a gene encoding the 37-amino acid mature polypeptide was chemically synthesized and cloned into the Tac cassette immediately after the bacterial ompA leader sequence for direct excretion of the AFP into the culture medium. Escherichia coli transformant with the construct placIQpar8AF was cultured in M9 medium. The recombinant AFP (rAFP) was detected by a competitive enzyme-linked immunosorbent assay (ELISA). After IPTG induction, a biologically active rAFP was expressed. The majority of the rAFP was excreted into the culture medium with only trace amounts trapped in the periplasmic space and cytoplasm. After 18 h of induction, the accumulated rAFP in the culture medium amounted to about 16 mg/L. The excreted AFP was purified from the culture medium by a single-step reverse-phase HPLC. Mass spectrometric and amino acid composition analyses confirmed the identity of the purified product. The rAFP, which lacked amidation at the C-terminal, was about 70% active when compared to the amidated wild-type protein, thus confirming the importance of C-terminal cap structure in protein stability and function.     

Quantitative Förster resonance energy transfer analysis for kinetic determinations of SUMO-specific protease

Förster resonance energy transfer (FRET) technology has been widely used in biological and biomedical research, and it is a very powerful tool for elucidating protein interactions in either dynamic or steady state. SUMOylation (the process of SUMO [small ubiquitin-like modifier] conjugation to substrates) is an important posttranslational protein modification with critical roles in multiple biological processes. Conjugating SUMO to substrates requires an enzymatic cascade. Sentrin/SUMO-specific proteases (SENPs) act as an endopeptidase to process the pre-SUMO or as an isopeptidase to deconjugate SUMO from its substrate. To fully understand the roles of SENPs in the SUMOylation cycle, it is critical to understand their kinetics. Here, we report a novel development of a quantitative FRET-based protease assay for SENP1 kinetic parameter determination. The assay is based on the quantitative analysis of the FRET signal from the total fluorescent signal at acceptor emission wavelength, which consists of three components: donor (CyPet–SUMO1) emission, acceptor (YPet) emission, and FRET signal during the digestion process. Subsequently, we developed novel theoretical and experimental procedures to determine the kinetic parameters, k_cat, K_M, and catalytic efficiency (k_cat/K_M) of catalytic domain SENP1 toward pre-SUMO1. Importantly, the general principles of this quantitative FRET-based protease kinetic determination can be applied to other proteases.     

Developability studies before initiation of process development

Monoclonal antibodies constitute a robust class of therapeutic proteins. Their stability, resistance to stress conditions and high solubility have allowed the successful development and commercialization of over 40 antibody-based drugs. Although mAbs enjoy a relatively high probability of success compared with other therapeutic proteins, examples of projects that are suspended due to the instability of the molecule are not uncommon. Developability assessment studies have therefore been devised to identify early during process development problems associated with stability, solubility that is insufficient to meet expected dosing or sensitivity to stress. This set of experiments includes short-term stability studies at 2−8 þC, 25 þC and 40 þC, freeze-thaw studies, limited forced degradation studies and determination of the viscosity of high concentration samples. We present here three case studies reflecting three typical outcomes: (1) no major or unexpected degradation is found and the study results are used to inform early identification of degradation pathways and potential critical quality attributes within the Quality by Design framework defined by US Food and Drug Administration guidance documents; (2) identification of specific degradation pathway(s) that do not affect potency of the molecule, with subsequent definition of proper process control and formulation strategies; and (3) identification of degradation that affects potency, resulting in program termination and reallocation of resources.     

Research progress on the immune mechanism of the silkworm Bombyx mori

The silkworm Bombyx mori L., representing an important economic insect and one of the best models for studying insect immunity, possesses an efficient and sophisticated innate immune system against invasive microorganisms. The innate immune system basically includes humoural immunity and cellular immunity. The humoural immunity, which functions via molecules including humoural factors, lysozymes, phenoloxidase, hemolin, lectins and, in particular, antimicrobial peptides, plays a central role in eliminating the invading pathogens. The cellular immunity is primarily carried out and mediated by plasmatocytes and granular cells of haemocytes in the haemolymph, usually followed by melanization. Additionally, apoptosis, a primary viral defence for insects lacking adaptive immunity, comprises an important part of the silkworm immune system. Currently, there is still the lack of a comprehensive and systematic understanding of the molecular mechanisms of silkworm immunity. We review the latest research progress on silkworm immune mechanisms, including phenoloxidase‐dependent melanization and apoptosis, which is conducive to improving our understanding of the silkworm immune mechanism, clarifying the relationship of various immune mechanisms, and also providing a theoretical basis and reference for the future research of insect immunity.     

Genetic polymorphism of glutathione S-transferase T1 and the risk of colorectal cancer: A meta-analysis

Background: Studies investigating the association between genetic polymorphism of glutathione S-transferase T1 (GSTT1) and risk of colorectal cancer have reported conflicting results. In order to clarify the effect of GSTT1 polymorphism on the risk of developing colorectal cancer, we carried out a meta-analysis using published data to obtain more precise estimates of risk. Methods: Electronic searches of PubMed and EMBASE were conducted to select studies for this meta-analysis. Papers were included if they were observational studies investigating the association between GSTT1 polymorphism and colorectal cancer risk. The principal outcome measure was the odds ratio (OR) with 95% confidence interval (CI) for the risk of colorectal cancer associated with GSTT1 null genotype. Results: We identified 30 eligible studies, which included 7635 cases and 12,911 controls. The combined results based on all studies showed that there was a statistically significant link between GSTT1 null genotype and colorectal cancer risk (OR = 1.20, 95% CI = 1.03–1.40). In the analysis of ethnic groups, we observed distinct differences associated with GSTT1 null genotype, the pooled odds ratios for the GSTT1 polymorphism were 1.32 in Caucasians (95% CI = 1.09–1.58) and 1.03 in Asians (95% CI = 0.81–1.32). As far as concerned the interaction between GSTT1 genotype and colorectal cancer risk in relation to smoking history, there was no increase in risk for smokers or nonsmokers with the GSTT1 null genotype (smokers: OR = 1.13, 95% CI = 0.80–1.60, nonsmokers: OR = 0.99, 95% CI = 0.71–1.38). When stratifying by the location of colorectal cancer, we found that there was a statistically significant link in rectal cancer (OR = 1.50, 95% CI = 1.09–2.07), but not in colon cancer (OR = 1.33, 95% CI = 0.94–1.88). No associations could be detected between null GSTT1 polymorphism and age, sex, tumor stage and differentiation. Conclusion: Our current study demonstrates that GSTT1 null genotype is associated with an increased risk of colorectal cancer, specifically, among Caucasians.     

蜂毒变应原及蜂毒免疫治疗

膜翅目昆虫种类繁多,其中某些种类昆虫刺蛰后可以导致严重的甚至危及生命的过敏反应。目前,关于膜翅目毒液的成分和变应原的研究越来越广泛和深入。该文主要介绍膜翅目中蜜蜂毒液的主要成分、主要变应原及蜂毒过敏的免疫治疗。