A calcium‐mediated actin redistribution at egg activation in Drosophila

Egg activation is the essential process in which mature oocytes gain the competency to proceed into embryonic development. Many events of egg activation are conserved, including an initial rise of intracellular calcium. In some species, such as echinoderms and mammals, changes in the actin cytoskeleton occur around the time of fertilization and egg activation. However, the interplay between calcium and actin during egg activation remains unclear. Here, we use imaging, genetics, pharmacological treatment, and physical manipulation to elucidate the relationship between calcium and actin in living Drosophila eggs. We show that, before egg activation, actin is smoothly distributed between ridges in the cortex of the dehydrated mature oocytes. At the onset of egg activation, we observe actin spreading out as the egg swells though the intake of fluid. We show that a relaxed actin cytoskeleton is required for the intracellular rise of calcium to initiate and propagate. Once the swelling is complete and the calcium wave is traversing the egg, it leads to a reorganization of actin in a wavelike manner. After the calcium wave, the actin cytoskeleton has an even distribution of foci at the cortex. Together, our data show that calcium resets the actin cytoskeleton at egg activation, a model that we propose to be likely conserved in other species.     

A review of the botany,traditional uses,phytochemistry and pharmacology of Nepeta tenuifolia Briq.

Phytochemistry Reviews - Nepeta tenuifolia (N. tenuifolia) is a common aromatic herb that is widespread in East Asia. The aerial parts and spikes can be used as the traditional phytomedicines for...     

Characterization of sparstolonin B, a Chinese herb-derived compound, as a selective Toll-like receptor antagonist with potent anti-inflammatory properties

Blockade of excessive Toll-like receptor (TLR) signaling is a therapeutic approach being actively pursued for many inflammatory diseases. Here we report a Chinese herb-derived compound, sparstolonin B (SsnB), which selectively blocks TLR2- and TLR4-mediated inflammatory signaling. SsnB was isolated from a Chinese herb, Spaganium stoloniferum; its structure was determined by NMR spectroscopy and x-ray crystallography. SsnB effectively inhibited inflammatory cytokine expression in mouse macrophages induced by lipopolysaccharide (LPS, a TLR4 ligand), Pam3CSK4 (a TLR1/TLR2 ligand), and Fsl-1 (a TLR2/TLR6 ligand) but not that by poly(I:C) (a TLR3 ligand) or ODN1668 (a TLR9 ligand). It suppressed LPS-induced cytokine secretion from macrophages and diminished phosphorylation of Erk1/2, p38a, IκBα, and JNK in these cells. In THP-1 cells expressing a chimeric receptor CD4-TLR4, which triggers constitutive NF-κB activation, SsnB effectively blunted the NF-κB activity. Co-immunoprecipitation showed that SsnB reduced the association of MyD88 with TLR4 and TLR2, but not that with TLR9, in HEK293T cells and THP-1 cells overexpressing MyD88 and TLRs. Furthermore, administration of SsnB suppressed splenocyte inflammatory cytokine expression in mice challenged with LPS. These results demonstrate that SsnB acts as a selective TLR2 and TLR4 antagonist by blocking the early intracellular events in the TLR2 and TLR4 signaling. Thus, SssB may serve as a promising lead for the development of selective TLR antagonistic agents for inflammatory diseases.     

Identification of genes associated with the biosynthesis of protostane triterpenes based on the transcriptome analysis of Alisma orientale (Sam.) Juz.

Journal of Plant Biochemistry and Biotechnology - Protostane triterpenes in Alisma orientale (Sam.) Juz., because of their unique structural feature, exhibit distinctive pharmacological activities....     

The antitumor molecular mechanism of Alisma orientalis with c-myc DNA: multi-spectroscopic analysis and molecular simulation

Abstract

We prepared extracts of Alisma orientalis from Sichuan and Fujian Province, China. Based on the ratio of alisol B 23-acetate (23B) to alisol A 24-acetate (24A) in two Alisma orientalis extracts, we prepared two mixtures of 24A and 23B (24A:23B?=?1:3 or 1:10). The antitumor molecular mechanism of the monomers 24A and 23B, the two mixtures and the effective components of Alisma orientalis from different habitats were studied. The MTT assay suggested that the difference in the antitumor activity of Alisma orientalis from different habitats was correlated to the ratio of 24A to 23B. The multi-spectroscopic analysis suggested that the effective components, the monomers and mixtures interacted with c-myc DNA in a partial intercalation manner. The binding strength of the alisol acetates to c-myc DNA was consistent with the anticancer activity, indicating that c-myc DNA was the anticancer target. The molecular simulation indicated that the mixtures were all directly bound to different base pairs of c-myc DNA for a superimposed effect, which led to the binding strength of the mixtures to c-myc DNA was stronger than that of the monomers. The molecules in the 1:3 mixture were all bound to different base pairs of c-myc DNA. However, for the 1:10 mixture, seven molecules of 23B bound to the side chain of 24A, resulting in the mixture with a long chain structure which increased the steric hindrance of 24A. As a result, affinity between 24A and c-myc DNA in the 1:10 mixture was weaker than that in the 1:3 mixture.

The antitumor molecular mechanism of the alisol monomers 24A and 23B, the mixtures with different proportions and the effective components of Alisma orientalis from different habitats were studied. The order of the antitumor activity was as follows: Sichuan?>?Fujian, 24A-23B (1:3) > 24A-23B (1:10) > 23B?>?24A. The antitumor activity of Alisma orientalis from different habitats was consistent with the mixtures which were designed according to the contents of the active ingredients of the medicinal materials, indicating that the antitumor activity of Alisma orientalis from Sichuan is better than that from Fujian which is related to the contents of 24A and 23B and the proportion of 1:3 is better than 1:10. The binding strength of the mixtures to c-myc DNA was consistent with the anticancer activity. The mixtures were all directly bound to different base pairs of c-myc DNA for a superimposed effect, which led to the strength of the interaction of the mixtures to c-myc DNA was stronger than that of the monomers. For the 24A-23B (1:3) mixture, the four small molecules bound to c-myc DNA directly and interacted with different base pairs of c-myc DNA. While for the 24A-23B (1:10) mixture, 24A and three 23B molecules interacted with c-myc DNA, the remaining seven 23B molecules bound to the side chain of 24A, which increased the steric hindrance. The binding of the mixture to c-myc DNA was decreased.

Communicated by Ramaswamy H. Sarma     

Transient focal cerebral ischemia/reperfusion induces early and chronic axonal changes in rats: its importance for the risk of Alzheimer's disease

The dementia of Alzheimer's type and brain ischemia are known to increase at comparable rates with age. Recent advances suggest that cerebral ischemia may contribute to the pathogenesis of Alzheimer's disease (AD), however, the neuropathological relationship between these two disorders is largely unclear. It has been demonstrated that axonopathy, mainly manifesting as impairment of axonal transport and swelling of the axon and varicosity, is a prominent feature in AD and may play an important role in the neuropathological mechanisms in AD. In this study, we investigated the early and chronic changes of the axons of neurons in the different brain areas (cortex, hippocampus and striatum) using in vivo tracing technique and grading analysis method in a rat model of transient focal cerebral ischemia/reperfusion (middle cerebral artery occlusion, MCAO). In addition, the relationship between the changes of axons and the expression of β-amyloid 42 (Aβ42) and hyperphosphorylated Tau, which have been considered as the key neuropathological processes of AD, was analyzed by combining tracing technique with immunohistochemistry or western blotting. Subsequently, we found that transient cerebral ischemia/reperfusion produced obvious swelling of the axons and varicosities, from 6 hours after transient cerebral ischemia/reperfusion even up to 4 weeks. We could not observe Aβ plaques or overexpression of Aβ42 in the ischemic brain areas, however, the site-specific hyperphosphorylated Tau could be detected in the ischemic cortex. These results suggest that transient cerebral ischemia/reperfusion induce early and chronic axonal changes, which may be an important mechanism affecting the clinical outcome and possibly contributing to the development of AD after stroke.     

Molecular Structure-Affinity Relationship of Bufadienolides and Human Serum Albumin In Vitro and Molecular Docking Analysis

The development of bufadienolides as anti-tumor agents is limited due to poor pharmacokinetic properties regarding drug half-lives and toxicity in vivo. These serious factors might be improved by increasing the drug/albumin-binding ratio. This study therefore investigated the relationship between the structural properties of nine bufadienolides and their affinities for human serum albumin (HSA) by a fluorescence spectroscopy-based analysis and molecular docking. Fluorescence quenching data showed that the interaction of each bufadienolide with HSA formed a non-fluorescent complex, while thermodynamic parameters revealed negative ΔS and ΔH values, corresponding to changes in enthalpy and entropy, respectively. The structural differences between the various bufadienolides markedly influenced their binding affinity for HSA. With the exception of a C = O bond at the C12 position that decreased the binding affinity for HSA, other polar groups tended to increase the affinity, especially a hydroxyl (OH) group at assorted bufadienolide sites. The rank order of binding affinities for drugs with tri-hydroxyl groups was as follows: 11-OH > 5-OH > 16-OH; in addition, 16-acetoxy (OAc), 10-aldehyde and 14-epoxy constituents notably enhanced the binding affinity. Among these groups, 11-OH and 16-acetyl were especially important for a seamless interaction between the bufadienolides and HSA. Furthermore, molecular docking analysis revealed that either an 11-OH or a 16-OAc group spatially close to a five-membered lactone ring significantly facilitated the anchoring of these compounds within site I of the HSA pocket via hydrogen bonding (H-bonding) with Tyr150 or Lys199, respectively. In summary, bufadienolide structure strongly affects binding with HSA, and 11-OH or 16-OAc groups improve the drug association with key amino acid residues. This information is valuable for the prospective development of bufadienolides with improved pharmacological profiles as novel anti-tumor drugs.     

耐热克鲁维酵母在葡萄酒酿造中的研究进展

耐热克鲁维酵母(Lachancea thermotolerans)是一种具有优良酿造学特性的非酿酒酵母(non-Saccharomyces cevevisiae),近年来由于其对葡萄酒的发酵进程及香气、滋味等感官特性均有着重要影响而受到越来越多的关注。耐热克鲁维酵母突出的特点表现为高产乳酸、甘油、2-苯乙醇及乙酯类香气成分,低产乙醇及挥发酸类物质,并且相关研究显示不同耐热克鲁维酵母发酵对葡萄酒的影响存在明显的菌株特异性。文章围绕耐热克鲁维酵母的菌株多样性、其对葡萄酒质量的影响及在混合发酵中的应用等方面进行综述,以期为本土耐热克鲁维酵母菌株性状的筛选、产酸及产香机制的解析提供参考依据,促进我国酿酒微生物种质资源的良性发展。