De novo synthesis of d-alanine in germinating Pisum sativum seedlings

The amounts of d-alanine derivatives, γ-l-glutamyl-d-alanine and N-malonyl-d-alanine, increase rapidly during the early growth of pea seeds. Pyruvate-[1?¹⁴C], l-alanine-[U?¹⁴C], d-alanine-[U?¹⁴C], l-alanine-[¹⁵N] and ¹⁵NH₄Cl were therefore fed to the seedlings and the incorporation investigated. Labelling results revealed that pea seedlings can utilize these erogenous compounds to form d-alanine and that labelled l-alanine is effectively converted to the d-enantiomer with retention of ¹⁴C and, largely, ¹⁵N label. Enzyme analyses in vitro provided additional evidence that the extract of pea seedlings catalyzes the direct conversion of l-alanine to d-alanine. The data suggest that the de novo synthesis of d-alanine in pea seedlings occurs by a racemase reaction.     

Infrared analysis of pea stem cell walls and oriented structure of matrix polysaccharides in them

Infrared absorption spectra of film specimens of the epidermaland parenchyma cell walls of the third internode of pea stem,before and after protease treatment and after treatment forremoval of lipid materials, pectic substances and hemicellulose,were recorded, and characteristic bands in the spectrum of thewall were assigned. Polarization spectrum measurements of thewall provided evidence indicating that the non-cellulosic polysaccharidematrix as well as cellulose microfibrils has an oriented structurein the wall which changes during extension growth as well asupon mechanical extension of the walls. (Received March 9, 1978; )     

Effect of auxin on changes in the oriented structure of wall polysaccharides in response to mechanical extension in oat coleoptile cell walls

The increase in the dichroism of the ester-C=O and COO^–bands in response to mechanical extension in oat coleoptilecell walls was much enhanced by IAA pretreatment while the decreasein that of the C-O-C band was not enhanced or even suppressed.The results indicate the importance of the ultrastructure ofnon-cellulosic polysaccharides in controlling auxin-inducedcell elongation. ¹ Present adress: Department of Agricultural Chemistry, KyotoPrefectural University, Shimogamo, Kyoto 606, Japan. (Received May 16, 1978; )     

N-acetyl conjugates of basic amino acids newly identified in rat urine

Ninhydrin-negative conjugates of basic amino acids were isolated from rat urine and were characterized. The following conjugates of basic amino acids are the compounds newly identified in animal urine specimens, N^α-acetyl-N^π-methylhistidine, N^α-(N-acetyl-β-alanyl)histidine (N-acetylcarnosine), N^α-acetyl-N^G,N^′G-dimethylarginine, N^α-acetyl-N^G,N^G-dimethylarginine, and N^α-acetyl-N^?,N^?,N^?-trimethyllysine.     

The mechanism of the movement of leucocytes

In a study of the movement of human leucocytes it was clarified that characteristic contraction waves were observed on the cell surface during movement and an initial morphological change directly related to the appearance of the wave originated in the surface of the granuloplasm and not in the cell membrane. From these findings, together with physicochemical properties of the contractile protein from equine leucocytes, it was proposed that the wave observed in moving leucocytes might be conducted, in some way, by contraction and relaxation of the contractile protein in the cells. Myosin A and actin as constituents of the contractile protein were extracted separately from leucocytes in polymerized form, which resemble myosin aggregate and F-actin from muscle, respectively. The thick and thin filaments of about 150 and 80 Å in diameter were observed in glycerinated leucocytes with electron microscopy. When glycerinated leucocytes were incubated with heavy meromyosin (HMM) from rabbit skeletal myosin A, the thin filaments developed a structure resembling the ‘arrowhead structure’ of the HMM F-actin complex in vitro. The thick filaments seemed to correspond to myosin aggregates and the thin ones to filaments containing F-actin.     

Advancing Aptamers as Molecular Probes for Cancer Theranostic Applications—The Role of Molecular Dynamics Simulation

Theranostics cover emerging technologies for cell biomarking for disease diagnosis and targeted introduction of drug ingredients to specific malignant sites. Theranostics development has become a significant biomedical research endeavor for effective diagnosis and treatment of diseases, especially cancer. An efficient biomarking and targeted delivery strategy for theranostic applications requires effective molecular coupling of binding ligands with high affinities to specific receptors on the cancer cell surface. Bioaffinity offers a unique mechanism to bind specific target and receptor molecules from a range of non‐targets. The binding efficacy depends on the specificity of the affinity ligand toward the target molecule even at low concentrations. Aptamers are fragments of genetic materials, peptides, or oligonucleotides which possess enhanced specificity in targeting desired cell surface receptor molecules. Aptamer–target binding results from several inter‐molecular interactions including hydrogen bond formation, aromatic stacking of flat moieties, hydrophobic interaction, electrostatic, and van der Waals interactions. Advancements in Systematic Evolution of Ligands by Exponential Enrichment (SELEX) assay has created the opportunity to artificially generate aptamers that specifically bind to desired cancer and tumor surface receptors with high affinities. This article discusses the potential application of molecular dynamics (MD) simulation to advance aptamer‐mediated receptor targeting in targeted cancer therapy. MD simulation offers real‐time analysis of the molecular drivers of the aptamer‐receptor binding and generate optimal receptor binding conditions for theranostic applications. The article also provides an overview of different cancer types with focus on receptor biomarking and targeted treatment approaches, conventional molecular probes, and aptamers that have been explored for cancer cells targeting.     

Simulation modeling reveals the evolutionary role of landscape shape and species dispersal on genetic variation within a metapopulation

Different shapes of landscape boundaries can affect the habitat networks within them and consequently the spatial genetic-patterns of a metapopulation. In this study, we used a mechanistic framework to evaluate the effects of landscape shape, through watershed elongation, on genetic divergence among populations at the metapopulation scale. Empirical genetic data from four, sympatric stream-macroinvertebrates having aerial adults were collected from streams in Japan to determine the roles of species-specific dispersal strategies on metapopulation genetics. Simulation results indicated that watershed elongation allows the formation of river networks with fewer branches and larger topographic constraints. This results in decreased interpopulation connectivity but a lower level of spatial isolation of distal populations (e.g. those found in headwaters) occurring in the landscapes examined. Distal populations had higher genetic divergence when their downstream-biased dispersal (relative to upstream- and/or overland-biased dispersal) was high. This underscores the importance of distal populations influencing genetic divergence at the metapopulation scale for species having downstream-biased dispersal. In turn, lower genetic divergence was observed under watershed elongation when the genetic isolation of distal populations was decreased in such species. This strong association between landscape shape and evolutionary processes highlights the importance of natural, spatial architecture in assessing the effectiveness of conservation and management strategies.     

Diversification of CpG-Island Promoters Revealed by Comparative Analysis Between Human and Rhesus Monkey Genomes

Mammalian Genome - While CpG dinucleotides are significantly reduced compared to other dinucleotides in mammalian genomes, they can congregate and form CpG islands, which localize around...     

Novel (p)ppGpp0 suppressor mutations reveal an unexpected link between methionine catabolism and GTP synthesis in Bacillus subtilis

In bacteria, guanosine (penta)tetra-phosphate ([p]ppGpp) is essential for controlling intracellular metabolism that is needed to adapt to environmental changes, such as amino acid starvation. The (p)ppGpp⁰ strain of Bacillus subtilis, which lacks (p)ppGpp synthetase, is unable to form colonies on minimal medium. Here, we found suppressor mutations in the (p)ppGpp⁰ strain, in the purine nucleotide biosynthesis genes, prs, purF and rpoB/C, which encode RNA polymerase core enzymes. In comparing our work with prior studies of ppGpp⁰ suppressors, we discovered that methionine addition masks the suppression on minimal medium, especially of rpoB/C mutations. Furthermore, methionine addition increases intracellular GTP in rpoB suppressor and this effect is decreased by inhibiting GTP biosynthesis, indicating that methionine addition activated GTP biosynthesis and inhibited growth under amino acid starvation conditions in (p)ppGpp⁰ backgrounds. Furthermore, we propose that the increase in intracellular GTP levels induced by methionine is due to methionine derivatives that increase the activity of the de novo GTP biosynthesis enzyme, GuaB. Our study sheds light on the potential relationship between GTP homeostasis and methionine metabolism, which may be the key to adapting to environmental changes.