The Spatial Structure of the ACTH-(7–10) Molecule

Biophysics - The spatial structure of the ACTH-(7–10) molecule, a 7–10 fragment of the adrenocorticotropic hormone, with the Phe–Arg–Trp–Gly amino-acid sequence was...     

The evolution of photosynthesis…again?

‘Replaying the tape’ is an intriguing ‘would it happen again?’ exercise. With respect to broad evolutionary innovations, such as photosynthesis, the answers are central to our search for life elsewhere. Photosynthesis permits a large planetary biomass on Earth. Specifically, oxygenic photosynthesis has allowed an oxygenated atmosphere and the evolution of large metabolically demanding creatures, including ourselves. There are at least six prerequisites for the evolution of biological carbon fixation: a carbon-based life form; the presence of inorganic carbon; the availability of reductants; the presence of light; a light-harvesting mechanism to convert the light energy into chemical energy; and carboxylating enzymes. All were present on the early Earth. To provide the evolutionary pressure, organic carbon must be a scarce resource in contrast to inorganic carbon. The probability of evolving a carboxylase is approached by creating an inventory of carbon-fixation enzymes and comparing them, leading to the conclusion that carbon fixation in general is basic to life and has arisen multiple times. Certainly, the evolutionary pressure to evolve new pathways for carbon fixation would have been present early in evolution. From knowledge about planetary systems and extraterrestrial chemistry, if organic carbon-based life occurs elsewhere, photosynthesis—although perhaps not oxygenic photosynthesis—would also have evolved.     

Weather Forecasting: The View from Space…

Findley, James S.; Harris, Arthur H.; Wilson, Don E.; and Jones, Clyde Mammals of New Mexico Albuquerque: The University of New Mexico Press, 1975 360 pp., $8.50 Reviewed by Vagn Flyger

Piers, Helen Grasshopper and Butterfly New York: McGraw-Hill Book Co., 1975 80 pp., $5.95, library edition $5.72 Reviewed by N. N. Raghuvir

Gergely, Tibor Animals: A Picture Book of Facts and Figures New York: McGraw-Hill Book Co., 1975 47 pp., $5.95, library edition $5.72 Reviewed by Theodore W. Munch

Johnsgard, Paul A. Waterfowl of North America Bloomington, Indiana University Press 1975,575 pp. Reviewed by Kate Curry Vahle

Jacobson, Daniel The Fishermen (Indians of North America) New York: Franklin Watts, Inc., 1975 87 pp., $4.90 Reviewed by Robert W. Boenig

Janzen, Daniel H. Ecology of Plants in the Tropics (The Institute of Biology's Studies in Biology, No. 58) London: Edward Arnold (Distributed by Crane, Russak &; Co., New York), 1975 65 pp., $3.75 Reviewed by Rex E. Kerstetter

London, Carolyn The Hospital Doctors, Nurses and Mystery Workers New York: McGraw-Hill Book Co., 1976 86 pp., $5.72 Library Edition Reviewed by Philip C. Anderson

Buxton, Ralph Nature's Gliders Chicago: Children's Press, 1975 32 pp., individuals $6.60, institutions $4.95 Reviewed by Sue Hall

Clarke, H. T. (revised by B. Haynes) A Handbook of Organic Analysis: Qualitative and Quantitative (fifth edition) New York: Crane, Russak &; Co., 1975 291 pp., cloth $35.00, paper $16.00 Reviewed by Lawrence Powell Eblin

Simon, Seymour Discovering What Garter Snakes Do New York: McGraw-Hill Junior Books, 1975 48 pp., $4.72 Reviewed by Carl Gans

Dobbs, Austen, ed. The Birds of Nottinghamshire: Past and Present North Pomfret, Vt.: David &; Charles, 1975 226 pp., $17.00 Reviewed by Gerald R. Rising

Ashworth, J. M., and Dee, Jennifer The Biology of Slime Moulds (The Institute of Biology's Studies in Biology, No. 56) New York: Crane, Russak &; Co., Inc., 1975 67 pp., $3.75 Reviewed by Emanuel D. Rudolph

Exline, Joseph D. Individualized Techniques for Teaching Earth Science West Nyack, N.Y.: Parker Publishing Co., 1975 230 pp., $10.95 Reviewed by Waring B. Hill

Stadtfeld, Curtis K. Whitetail Deer: A Year's Cycle New York: The Dial Press, 1975 163 pp., $7.95 Reviewed by Paul F. Connor

Carrier, Rick Fly: The Complete Book of Sky Sailing New York: McGraw-Hill Book Co., 1975 128 pp., $7.95 Reviewed by A.D. Goddard

Duncan, Wilbur H. Woody Vines of the Southeastern United States Athens: The University of Georgia Press, 1975 76 pp., $2.50 Reviewed by A. J. Sharp

Barnes, R. S. K. Estuarine Biology (The Institute of Biology's Studies in Biology no. 49) New York: Crane, Russak &; Co., 1975 76 pp., $3.25 Reviewed by Brother G. Nicholas

Bendick, Jeanne How Heredity Works: Why Living Things Are As They Are (Finding-out books) New York: Parent's Magazine Press, 1975 64 pp., $4.59 Reviewed by Donald J. Nash     

The Influence of Concentration and Temperature on the Formation of ??-Oryzanol?+???-Sitosterol Tubules in Edible Oil Organogels

The gelation process of mixtures of γ-oryzanol and sitosterol structurants in sunflower oil was studied using light scattering, rheology, and micro-scanning calorimetry (Micro-DSC). The relation between temperature and the critical aggregation concentration (CAC) of tubule formation of γ-oryzanol and sitosterol was determined using these techniques. The temperature dependence of the CAC was used to estimate the binding energy and enthalpic and entropic contribution to the tubular formation process. The binding energy calculated at the corresponding temperatures and CACs were relatively low, in order of 2 RT (4.5 kJ mol⁻¹), which is in accord with the reversibility of the tubular formation process. The formation of the tubules was associated with negative (exothermic) enthalpy change (ΔH ⁰ ) compared with positive entropy term (−T ΔS ⁰ >0), indicating that the aggregation into tubules is an enthalpy-driven process. The oryzanol–sitosterol ratio affected the aggregation process; solutions with ratio of (60 oryzanol–40 sitosterol) started aggregation at higher temperature compared with other ratios.     

The Chemical Molecule B355252 is Neuroprotective in an In Vitro Model of Parkinson’s Disease

6-Hydroxydopamine (6-OHDA) is a neurotoxin frequently used to create in vitro and in vivo experimental models of Parkinson’s disease (PD), a chronic neurodegenerative disorder largely resulting from damage to the nigrostriatal dopaminergic pathway. No effective drugs or therapies have been developed for this devastating disorder, and current regimens of symptomatic therapeutics only alleviate symptoms temporarily. Therefore, effective treatments that reverse or cure this disorder are urgently needed. The aim of the study described in this report was to investigate the therapeutic impact of B355252, an aryl thiophene sulfonamide chemical entity, in the widely recognized in vitro model of PD, and to characterize the molecular signaling pathways. We show here that 6-OHDA-induced cell death in HT22, a murine neuronal cell model, through a pathway that involves the mitochondria by increasing the levels of reactive oxygen species (ROS), raising intracellular calcium ([Ca²⁺]i), enhancing the release of cytochrome c to the cytosol, and promoting activation of stress-activated protein kinase/c-Jun NH₂-terminal kinase (SAPK/JNK) signaling pathway. More importantly, we found that B355252 protected HT22 neurons against 6-OHDA toxin-induced neuronal cell death by significant attenuation of ROS production, blocking of mitochondrial depolarization, inhibition of cytochrome c release, sequestration of [Ca²⁺]i, modulation of JNK cascade, and strong inhibition of caspase 3/7 cleavage. Overall, this study demonstrates that death of neurons under toxic conditions characteristic of PD can be efficiently halted by B355252 and suggests that further development of the molecule could be potentially beneficial as a therapeutic prevention or treatment option for PD.     

Neurulation continues: The parade commander is… apical constriction

Neurulation is traditionally defined as the process of closure of the neural tube. New data have shown that the major driving forces of neurulation continue to operate with the closure of the neural tube, at least until the central canal of the neural tube has formed. Owing to this, the paper proposes to distinguish two periods of neurulation. According to these notions, early neurulation corresponds to the period of closure of the neural tube, and late neurulation corresponds to the period of formation of the central canal. Examples of neural tube defects that affect late neurulation are discussed.     

The Cell Adhesion Molecule “CAR” and Sialic Acid on Human Erythrocytes Influence Adenovirus In Vivo Biodistribution

Although it has been known for 50 years that adenoviruses (Ads) interact with erythrocytes ex vivo, the molecular and structural basis for this interaction, which has been serendipitously exploited for diagnostic tests, is unknown. In this study, we characterized the interaction between erythrocytes and unrelated Ad serotypes, human 5 (HAd5) and 37 (HAd37), and canine 2 (CAV-2). While these serotypes agglutinate human erythrocytes, they use different receptors, have different tropisms and/or infect different species. Using molecular, biochemical, structural and transgenic animal-based analyses, we found that the primary erythrocyte interaction domain for HAd37 is its sialic acid binding site, while CAV-2 binding depends on at least three factors: electrostatic interactions, sialic acid binding and, unexpectedly, binding to the coxsackievirus and adenovirus receptor (CAR) on human erythrocytes. We show that the presence of CAR on erythrocytes leads to prolonged in vivo blood half-life and significantly reduced liver infection when a CAR-tropic Ad is injected intravenously. This study provides i) a molecular and structural rationale for Ad–erythrocyte interactions, ii) a basis to improve vector-mediated gene transfer and iii) a mechanism that may explain the biodistribution and pathogenic inconsistencies found between human and animal models.     

The Small Molecule R-(-)-β-O-Methylsynephrine Binds to Nucleoporin 153 kDa and Inhibits Angiogenesis

R-(-)-β-O-methylsynephrine (OMe-Syn) is a naturally occurring small molecule that was identified in a previous screen as an inhibitor of angiogenesis. In this study, we conducted two animal model experiments to investigate the in vivo antiangiogenic activity of OMe-Syn. OMe-Syn significantly inhibited angiogenesis in a transgenic zebrafish model as well as in a mouse retinopathy model. To elucidate the underlying mechanisms responsible for the antiangiogenic activity of OMe-Syn, we used phage display cloning to isolate potential OMe-Syn binding proteins from human cDNA libraries and identified nucleoporin 153 kDa (NUP153) as a primary binding partner of OMe-Syn. OMe-Syn competitively inhibited mRNA binding to the RNA-binding domain of NUP153. Furthermore, depletion of NUP153 in human cells or zebrafish embryos led to an inhibition of angiogenesis, in a manner similar to that seen in response to OMe-Syn treatment. These data suggest that OMe-Syn is a promising candidate for the development of a novel antiangiogenic agent and that inhibition of NUP153 is possibly responsible for the antiangiogenic activity of OMe-Syn.     

The Nonantibiotic Small Molecule Cyslabdan Enhances the Potency of β-Lactams against MRSA by Inhibiting Pentaglycine Interpeptide Bridge Synthesis

The nonantibiotic small molecule cyslabdan, a labdan-type diterpene produced by Streptomyces sp. K04-0144, markedly potentiated the activity of the β-lactam drug imipenem against methicillin-resistant Staphylococcus aureus (MRSA). To study the mechanism of action of cyslabdan, the proteins that bind to cyslabdan were investigated in an MRSA lysate, which led to the identification of FemA, which is involved in the synthesis of the pentaglycine interpeptide bridge of the peptidoglycan of MRSA. Furthermore, binding assay of cyslabdan to FemB and FemX with the function similar to FemA revealed that cyslabdan had an affinity for FemB but not FemX. In an enzyme-based assay, cyslabdan inhibited FemA activity, where as did not affected FemX and FemB activities. Nonglycyl and monoglycyl murein monomers were accumulated by cyslabdan in the peptidoglycan of MRSA cell walls. These findings indicated that cyslabdan primarily inhibits FemA, thereby suppressing pentaglycine interpeptide bridge synthesis. This protein is a key factor in the determination of β-lactam resistance in MRSA, and our findings provide a new strategy for combating MRSA.     

The role of OH…O and CH…O hydrogen bonds and H…H interactions in ethanol/methanol–water heterohexamers

Bioethanol is one of the world’s most extensively produced biofuels. However, it is difficult to purify due to the formation of the ethanol–water azeotrope. Knowledge of the azeotrope structure at the molecular level can help to improve existing purification methods. In order to achieve a better understanding of this azeotrope structure, the characterization of (ethanol)₅–water heterohexamers was carried out by analyzing the results of electronic structure calculations performed at the B3LYP/6-31+G(d) level. Hexamerization energies were found to range between ?36.8 and ?25.8 kcal/mol. Topological analysis of the electron density confirmed the existence of primary (OH…O) hydrogen bonds (HBs), secondary (CH…O) HBs, and H…H interactions in these clusters. Comparison with three different solvated alcohol systems featuring the same types of atom–atom interactions permitted the following order of stability to be determined: (methanol)₅–water > (methanol)₆ > (ethanol)₅–water > (ethanol)₆. These findings, together with accompanying geometric and spectroscopic analyses, show that similar cooperative effects exist among the primary HBs for structures with the same arrangement of primary HBs, regardless of the nature of the molecules involved. This result provides an indication that the molecular ratio can be considered to determine the unusual behavior of the ethanol–water system. The investigation also highlights the presence of several types of weak interaction in addition to primary HBs.

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Graphical Abstract Water-ethanol clusters exhibit a variety of interaction types between their atoms, such as primary OH...O (blue), secondary CH...O (green) and H...H (yellow) interactions as revealed by Quantum Chemical Topology

     

Structuring Edible Oils with Hydrocolloids: Where Do we Stand?

This brief opinion paper discusses an expert’s viewpoint on the field of oil structuring with specific emphasis on the reported innovative approaches explored so far for using hydrocolloids as the structuring agents.