Use of a biomimetic chromatographic stationary phase for study of the interactions occurring between inorganic anions and phosphatidylcholine membranes

A liquid chromatographic method for the study of ion-membrane interactions is reported. A phosphatidylcholine biomimetic stationary phase was established by loading dimyristoylphosphatidylcholine (DMPC) onto a reversed-phase octadecylsilica packed column. This column was then used to study the interaction of some inorganic anions with the stationary phase by UV and conductivity detection. Ten inorganic anions were selected as model ions and were analyzed with the proposed chromatographic system. Anion-DMPC interactions of differing magnitudes were observed for all of the model anions. Perchlorate-DMPC interactions were strongest, followed by thiocyanate-DMPC, iodide-DMPC, chlorate-DMPC, nitrate-DMPC, bromide-DMPC, chloride-DMPC, fluoride-DMPC, and then sulfate-DMPC. Cations in the eluent, especially H(+) ions and divalent cations such as Ca(2+), showed strong effects on anion-DMPC interactions. The chromatographic data suggest that DMPC interacts with both the anions and the cations. Anion-DMPC interactions were dependent on the surface potential of the stationary phase: at low surface potentials anion-DMPC interactions were predominantly solvation dependent in nature whereas at more positive surface potentials anion-DMPC interactions were predominantly electrostatic in nature. Cation-DMPC interactions served to raise the surface potential, causing the anion-DMPC interactions to vary from solvation dependent to electrostatic. The chromatographic data were used to provide quantitative estimates of the enthalpies of the anion-DMPC interactions.     

Characterization of the Selaginella remotifolia MADS-box gene

Recent progress in plant molecular genetics has revealed that floral organ development is regulated by several homeotic selector genes, most of which belong to the MADS-box gene family. Here we report on SrMADS1,a MIKC(c)-type MADS-box gene from Selaginella, a spikemoss belonging to the lycophytes. SrMADS1 phylogenetically forms a monophyletic clade with genes of the LAMB2 group, which are MIKC(c) genes of the clubmoss Lycopodium, and is expressed in whole sporophytic tissues except roots and rhizophores. Our results and the previous report on Lycopodium MIKC(c) genes suggest that the ancestral MIKC(c )gene of primitive dichotomous plants in the early Devonian was involved in the development of basic sporophytic tissues such as shoot, stem, and sporangium.     

Involvement of auxin and a homeodomain-leucine zipper I gene in rhizoid development of the moss Physcomitrella patens

Differentiation of epidermal cells is important for plants because they are in direct contact with the environment. Rhizoids are multicellular filaments that develop from the epidermis in a wide range of plants, including pteridophytes, bryophytes, and green algae; they have similar functions to root hairs in vascular plants in that they support the plant body and are involved in water and nutrient absorption. In this study, we examined mechanisms underlying rhizoid development in the moss, Physcomitrella patens, which is the only land plant in which high-frequency gene targeting is possible. We found that rhizoid development can be split into two processes: determination and differentiation. Two types of rhizoids with distinct developmental patterns (basal and mid-stem rhizoids) were recognized. The development of basal rhizoids from epidermal cells was induced by exogenous auxin, while that of mid-stem rhizoids required an unknown factor in addition to exogenous auxin. Once an epidermal cell had acquired a rhizoid initial cell fate, expression of the homeodomain-leucine zipper I gene Pphb7 was induced. Analysis of Pphb7 disruptant lines showed that Pphb7 affects the induction of pigmentation and the increase in the number and size of chloroplasts, but not the position or number of rhizoids. This is the first report on the involvement of a homeodomain-leucine zipper I gene in epidermal cell differentiation.     

The N-terminal lipopeptide of a 44-kDa membrane-bound lipoprotein of Mycoplasma salivarium is responsible for the expression of intercellular adhesion molecule-1 on the cell surface of normal human gingival fibroblasts

The activities to induce TNF-alpha production by a monocytic cell line, THP-1, and ICAM-1 expression and IL-6 production by human gingival fibroblasts were detected in plural membrane lipoproteins of Mycoplasma salivarium. Although SDS-PAGE of the lipoproteins digested by proteinase K did not reveal any protein bands with molecular masses higher than approximately10 kDa, these activities were detected in the front of the gel. A lipoprotein with a molecular mass of 44 kDa (Lp44) was purified. Proteinase K did not affect the ICAM-1 expression-inducing activity of Lp44, but lipoprotein lipase abrogated the activity. These results suggested that the proteinase K-resistant and low molecular mass entity, possibly the N-terminal lipid moiety, played a key role in the expression of the activity. The N-terminal lipid moiety of Lp44 was purified from Lp44 digested with proteinase K by HPLC. Judging from the structure of microbial lipopeptides as well as the amino acid sequence and infrared spectrum of Lp44, the structure of the N-terminal lipid moiety of Lp44 was speculated to be S-(2, 3-bisacyloxypropyl)-cysteine-GDPKHPKSFTEWV-. Its analogue, S-(2, 3-bispalmitoyloxypropyl)-cysteine-GDPKHPKSF, was synthesized. The lipopeptide was similar to the N-terminal lipid moiety of Lp44 in the infrared spectrum and the ICAM-1 expression-inducing activity. Thus, this study suggested that the active entity of Lp44 was its N-terminal lipopeptide moiety, the structure of which was very similar to S-(2, 3-bispalmitoyloxypropyl)-cysteine-GDPKHPKSF.     

Dorsal specification in blastoderm at the blastula stage in the goldfish, Carassius auratus

The teleost dorsoventral axis cannot be morphologically distinguished before gastrulation. Previous studies by the current authors have shown that localized dorsalizing activity in the yolk cell (YC) induces the dorsal tissues in the overlying blastoderm. In order to examine whether or not dorsal blastomeres are committed to their dorsal fate before the gastrula stage, a variety of transplant operations were performed in goldfish blastoderms at the mid- to late-blastula stages. When the blastoderm was cut from the YC, rotated horizontally at 180°, and recombined with the YC, the blastoderm frequently developed two axes, indicating that dorsal blastomeres of the blastula had already acquired the ability to differentiate into the organizer in the absence of dorsalizing signals from the YC. This result was further confirmed by experiments using ventralized embryos in which no dorsal structures formed: the axis formation was frequently observed in the normal blastoderm combined with the ventralized YC at the blastula stage. However, the axes formed in the absence of dorsal information from the YC exhibited a lower dorso-anterior index. Furthermore, the dorsal specification was not stably maintained when the dorsal cells were located far from the YC. These results suggest that the inductive and permissive influence of the YC may be required for the blastoderm to undergo full dorsal differentiation.     

Fermentation and metabolic characteristics of Gluconacetobacter oboediens for different carbon sources

The metabolism of Gluconacetobacter oboediens was investigated in relation to different carbon sources for the continuous cultures at the dilution rate of 0.05 h⁻¹. The ¹³C-flux result implies the formation of metabolic recycles for the case of using glucose and acetate as carbon sources. When glucose and ethanol were used as carbon sources, the specific ethanol uptake rate and the specific acetate production rate increased as the feed ethanol concentration was increased from 40 to 60 g/l, while the specific CO₂ production rate and the biomass concentration decreased, where the ¹³C-metabolic flux result indicates that the glycolysis, oxidative PP pathway, and the tricarboxylic acid (TCA) cycle were less active, resulting in less biomass concentration. The flux result also implies that oxaloacetate decarboxylase flux became negative, so that oxaloacetate is backed up by this pathway, resulting in less activity of glyoxylate pathway. When gluconate was added for the case of using glucose and ethanol as carbon sources, the acetate and cell concentrations as well as gluconate concentrations increased. The glucose and ethanol concentrations decreased concomitantly with the increased feed gluconate concentration. In accordance with these fermentation characteristics, the enzyme activity result indicates that glucose dehydrogenase and glucose-6-phosphate dehydrogenase pathways became less active, while the glycolysis and the TCA cycle was activated as the feed gluconate concentration was increased.     

Tissue‐dependent induction of apoptosis by matrix metalloproteinase stromelysin‐3 during amphibian metamorphosis

Matrix metalloproteinases (MMPs) are a superfamily of Zn²⁺‐dependent proteases that are capable of cleaving the proteinaceous component of the extracellular matrix (ECM). The ECM is a critical medium for cell–cell interactions and can also directly signal cells through cell surface ECM receptors, such as integrins. In addition, many growth factors and signaling molecules are stored in the ECM. Thus, ECM remodeling and/or degradation by MMPs are expected to affect cell fate and behavior during many developmental and pathological processes. Numerous studies have shown that the expression of MMP mRNAs and proteins associates tightly with diverse developmental and pathological processes, such as tumor metastasis and mammary gland involution. In vivo evidence to support the roles of MMPs in these processes has been much harder to get. Here, we will review some of our studies on MMP11, or stromelysin‐3, during the thyroid hormone‐dependent amphibian metamorphosis, a process that resembles the so‐called postembryonic development in mammals (from a few months before to several months after birth in humans when organ growth and maturation take place). Our investigations demonstrate that stromelysin‐3 controls apoptosis in different tissues via at least two distinct mechanisms. Birth Defects Research (Part C) 90:55–66, 2010. © 2010 Wiley‐Liss, Inc.     

Preparation of girdle lamella-containing chloroplasts from the diatom Phaeodactylum tricornutum

Chloroplasts were isolated from the diatom Phaeodactylum tricornutumby French press treatment and centrifugation. Electron micrographsof the isolated chloroplasts indicated that they lacked mostof the envelope membranes but retained the lamellar structurecharacteristic of the diatom chloroplast; three thylakoids weregrouped to form a band which transversed the chloroplast. Agirdle lamella also composed of three thylakoids surroundedthese transversal lamellae. The isolated chloroplasts were activein photosynthetic electron transport reactions including theHill reaction, the Mehler reaction and the system I reaction. (Received May 18, 1979; )