Structures and dynamic viscoelastic properties of micelles of mixtures of surfactin with cationic surfactant in aqueous solution

Surfactin sodium salt (SFNa) consisting of a long alkyl chain and cyclic peptide is a biosurfactant produced by Bacillus subtilis. SFNa is expected to be a useful material in cosmetics, medical field, and so on because it shows unique surface activities such as significant reduction of surface tension at extremely dilute concentration. In our previous study, we found SF formed monodisperse spherical micelles with low aggregation number in aqueous solution [1]. In addition, the aggregation number of SF micelles was discretely changed with varying salt concentration. However, such small changes of micelle structures cause slight change in viscoelasticity of the micelle solution. In the case that SF is used in detergent, tuning viscoelastic properties of its solution is requested. To tune the viscoelastic properties, tuning the structures of micelles should be important Mixing of anionic and cationic surfactant is one of the effective method to tune the structures of micelles. Therefore, addition of a cationic surfactant to anionic SFNa is expected to cause drastic change in viscoelastic properties owing to structural changes of SF micelles. Thus, in this study, we investigate the structures of micelles consisting of anionic SFNa and cetyltrimethyl ammonium bromide (CTAB) as a cationic surfactant and their viscoelasticity related to the structures of micelles. SFNa was provided by Kaneka Corporation and CTAB was dissolved at desired surfactant concentration, mole fraction of SFNa (XSF) and ratio of cation to anion (C/A) in aqueous NaCl solution. For the resulting SFNa-CTAB micelle solutions, visual observation, small angle X-ray scattering (SAXS) and dynamic viscoelastic analyses measurements were performed. We found that viscosity of aqueous solutions of SFNa-CTAB micelles are increased with increasing SF content in XSF \u3c 0.2 and CTAB content in 0.65 XSF \u3e 0.5. Therefore, it should be considered that structures of mixed micelles in these regions are much different from those of SFNa or CTAB micelles. Figure 1 shows SAXS profiles of SF-CTAB micelles at XSF = 0.1 (Red) and 0.6 (Blue). It could be confirmed scattering intensities in both systems are proportional to q-1 at low q range. Therefore, SF-CTAB mixtures form worm-like micelles at XSF = 0.1 and 0.6. However, SAXS profiles of these micelles are much different in high q region. Consequently, these micelles have different interiors. Thus, to investigate the effect of such structural difference of micelles on viscoelastic properties, dynamic viscoelastic measurements were performed. Figure 2 shows concentration dependences of the terminal relaxation times (τs) of SFNa-CTAB micelles at XSF = 0.1 and 0.6 obtained from the analyses for frequency dependence of storage and loss moduli by using Maxwell model. The τSs of these micelles are almost constant against micelle concentrations. This result means the entanglements of worm-like micelles of SFNa-CTAB mixtures are regarded as transient networks. References 1. Fujii, S. et al., Scientific Reports 2017, 7, 44494. 2. Naruse, K. et al., J. Phys. Chem. B. 2009, 113, 10222-10229 Please click Additional Files below to see the full abstract

Concentric zones, cell migration and neuronal circuits in the Drosophila visual center

金沢大学フロンティアサイエンス機構The Drosophila optic lobe comprises a wide variety of neurons, which form laminar neuropiles with columnar units and topographic projections from the retina. The Drosophila optic lobe shares many structural characteristics with mammalian visual systems. However, little is known about the developmental mechanisms that produce neuronal diversity and organize the circuits in the primary region of the optic lobe, the medulla. Here, we describe the key features of the developing medulla and report novel phenomena that could accelerate our understanding of the Drosophila visual system. The identities of medulla neurons are pre-determined in the larval medulla primordium, which is subdivided into concentric zones characterized by the expression of four transcription factors: Drifter, Runt, Homothorax and Brain-specific homeobox (Bsh). The expression pattern of these factors correlates with the order of neuron production. Once the concentric zones are specified, the distribution of medulla neurons changes rapidly. Each type of medulla neuron exhibits an extensive but defined pattern of migration during pupal development. The results of clonal analysis suggest homothorax is required to specify the neuronal type by regulating various targets including Bsh and cell-adhesion molecules such as N-cadherin, while drifter regulates a subset of morphological features of Drifter-positive neurons. Thus, genes that show the concentric zones may form a genetic hierarchy to establish neuronal circuits in the medulla.出版社許諾要件により、2012年3月より全文公開

Evolutionary activation of acidic chitinase in herbivores through the H128R mutation in ruminant livestock

Summary: Placental mammals' ancestors were insectivores, suggesting that modern mammals may have inherited the ability to digest insects. Acidic chitinase (Chia) is a crucial enzyme hydrolyzing significant component of insects' exoskeleton in many species. On the other hand, herbivorous animal groups, such as cattle, have extremely low chitinase activity compared to omnivorous species, e.g., mice. The low activity of cattle Chia has been attributed to R128H mutation. The presence of either of these amino acids correlates with the feeding behavior of different bovid species with R and H determining the high and low enzymatic activity, respectively. Evolutionary analysis indicated that selective constraints were relaxed in 67 herbivorous Chia in Cetartiodactyla. Despite searching for another Chia paralog that could compensate for the reduced chitinase activity, no active paralogs were found in this order. Herbivorous animals' Chia underwent genetic alterations and evolved into a molecule with low activity due to the chitin-free diet

A case of sialadenitis observed as an irAE of atezolizumab: A case report

Various symptoms emerge as immune-related adverse events of immune checkpoint inhibitor (ICI).A 73-year-old woman, a non-smoker, receiving chemotherapy including atezolizumab for lung adenocarcinoma, presented with fever, bilateral parotid swelling and sicca syndrome after four courses of chemotherapy. Because the lesions were not localized, the diagnosis was ICI-related sialadenitis rather than infectious. Prednisolone improved salivary gland swelling quickly. Six months after the last administration of ICI, there was no obvious progression of lung cancer.To our knowledge, this is the first case of sialadenitis caused by atezolizumab. ICI-related sialadenitis may be a good prognostic marker for lung cancer

Crab-Eating Monkey Acidic Chitinase (CHIA) Efficiently Degrades Chitin and Chitosan under Acidic and High-Temperature Conditions

Chitooligosaccharides, the degradation products of chitin and chitosan, possess anti-bacterial, anti-tumor, and anti-inflammatory activities. The enzymatic production of chitooligosaccharides may increase the interest in their potential biomedical or agricultural usability in terms of the safety and simplicity of the manufacturing process. Crab-eating monkey acidic chitinase (CHIA) is an enzyme with robust activity in various environments. Here, we report the efficient degradation of chitin and chitosan by monkey CHIA under acidic and high-temperature conditions. Monkey CHIA hydrolyzed α-chitin at 50 °C, producing N-acetyl-d-glucosamine (GlcNAc) dimers more efficiently than at 37 °C. Moreover, the degradation rate increased with a longer incubation time (up to 72 h) without the inactivation of the enzyme. Five substrates (α-chitin, colloidal chitin, P-chitin, block-type, and random-type chitosan substrates) were exposed to monkey CHIS at pH 2.0 or pH 5.0 at 50 °C. P-chitin and random-type chitosan appeared to be the best sources of GlcNAc dimers and broad-scale chitooligosaccharides, respectively. In addition, the pattern of the products from the block-type chitosan was different between pH conditions (pH 2.0 and pH 5.0). Thus, monkey CHIA can degrade chitin and chitosan efficiently without inactivation under high-temperature or low pH conditions. Our results show that certain chitooligosaccharides are enriched by using different substrates under different conditions. Therefore, the reaction conditions can be adjusted to obtain desired oligomers. Crab-eating monkey CHIA can potentially become an efficient tool in producing chitooligosaccharide sets for agricultural and biomedical purposes

Induction of Smooth Muscle Cell-Like Phenotype in Marrow-Derived Cells among Regenerating Urinary Bladder Smooth Muscle Cells

Tissue regeneration on acellular matrix grafts has great potential for therapeutic organ reconstruction. However, hollow organs such as the bladder require smooth muscle cell regeneration, the mechanisms of which are not well defined. We investigated the mechanisms by which bone marrow cells participate in smooth muscle formation during urinary bladder regeneration, using in vivo and in vitro model systems. In vivo bone marrow cells expressing green fluorescent protein were transplanted into lethally irradiated rats. Eight weeks following transplantation, bladder domes of the rats were replaced with bladder acellular matrix grafts. Two weeks after operation transplanted marrow cells repopulated the graft, as evidenced by detection of fluorescent staining. By 12 weeks they reconstituted the smooth muscle layer, with native smooth muscle cells (SMC) infiltrating the graft. In vitro, the differential effects of distinct growth factor environments created by either bladder urothelial cells or bladder SMC on phenotypic changes of marrow cells were examined. First, supernatants of cultured bladder cells were used as conditioned media for marrow cells. Second, these conditions were reconstituted with exogenous growth factors. In each case, a growth factor milieu characteristic of SMC induced an SMC-like phenotype in marrow cells, whereas that of urothelial cells failed. These findings suggest that marrow cells differentiate into smooth muscle on acellular matrix grafts in response to the environment created by SMC