Lag-phase and rate of synthesis in light-mediated anthocyanin synthesis

Mustard (Sinapis alba L.) seedlings were irradiated with continuous far-red light either with or without a pretreatment with 3 or 6 h of the same far-red light, separated by a 15 h dark period. The pretreatment increases the initial rate of anthocyanin accumulation — as caused by the 2nd light treatment — at least 6-fold but leads to an earlier cessation of anthocyanin accumulation. Moreover, the pretreatment seems to shorten the apparent lag-phase of anthocyanin accumulation considerably but it does not eliminate the lag. If the pretreatment with far-red light is terminated before the seedling reaches competence (with regard to phytochrome and anthocyanin synthesis) the pretreatment has no effect on the apparent lag-phase even though the future capacity of anthocyanin biogenesis is considerably stimulated by the pretreatment. The time course of induction of anthocyanin and that of phenylalanine ammonia-lyase (PAL) (Acton et al. 1980, Fig. 1) is in line with the concept that induction of PAL by light is a prerequisite for the onset of light-mediated anthocyanin synthesis.Abbreviation PAL phenylalanine ammonia-lyase     

Recent patents on oligonucleotide synthesis and gene synthesis

Gene synthesis is an emerging field which has widespread implications in synthetic biology and molecular biology. The field is constantly evolving which has led to key advances in oligonucleotide synthesis and gene synthesis technologies, with simplicity, cost effectiveness and high throughput. The miniaturization, multiplexing, microfluidic processing and the integrated microchip engineering will drive down cost and increase productivity without compromising DNA synthesis fidelity, whereas the gigantic amount of genome information provides infinite source of DNA elements and genes as raw material for synthetic biology. This article describes some of the recent patents on oligonucleotide synthesis and gene synthesis.     

Anatomy--analysis and synthesis

Scientific knowledge is a continuum, and anatomy is a part of this subject to the same methods, principles, and the need of synthesis, both within anatomy and with other syntheses. Western science is the spearhead of human progress in understanding the universe around us and the world of Earth, from which we cannot escape. Science may also, in its power of synthesis, bringing together not only those who practise it but also uniting the nations. Excellent as are the applications of science in technology, knowledge has its own value in producing a synthesis of human awareness,--and also it may prevent us from ruining the Earth, which is our only possible home.     

An amalgamation of solid phase peptide synthesis and ribosomal peptide synthesis

Expressed protein ligation (EPL) is a protein semisynthesis technique that allows the site-specific introduction of unnatural amino acids and biophysical probes into proteins. In the present study, we illustrate the utility of the approach through the generation of two semisynthetic proteins bearing spectroscopic probes. Dihydrofolate reductase containing a single (13)C probe in an active site loop was generated through the ligation of a synthetic peptide-alpha-thioester to a recombinantly generated fragment containing an N-terminal Cys. Similarly, c-Crk-II was assembled by the sequential ligation of three recombinant polypeptide building blocks, allowing the incorporation of (15)N isotopes in the central domain of the protein. These examples showcase the scope of the protein ligation strategy for selective introduction of isotopic labels into proteins, and the protocols described will be of value to those interested in using EPL on other systems.     

Transformation of type polysaccharide antigen synthesis and hemolysin synthesis in streptococci

Transformation of the ability to synthesize type polysaccharide antigen and beta-hemolysin has been obtained in group F streptococci. Colonies possessing cells transformed to antigen synthesis were detected on the agar surface with fluorescein-labeled anti-type serum. This selection method, in contrast to those with antibiotics, allowed both transformed and nontransformed cells to grow, resulting in sectored colonies. These colonies could be subcultured to further establish the synthesis of antigen. Group F, group A, and group-like z deoxyribonucleic acid (DNA) labeled with type II antigen and hemolysin, and streptomycin resistance transferred each marker to a group F strain lacking a type antigen. DNA from group F and z3 strains labeled with type III antigen, and streptomycin resistance transferred both markers to group F and z3 strains lacking type antigen. A second F strain without type antigen was not transformed with any of these markers. A group H strain was transformed to streptomycin resistance only by the same types of DNA. Transformation to type II antigen synthesis always resulted in the formation of beta-hemolysin. All strains isolated from natural sources contained both markers. A mutant, obtained by nitrosoguanidine treatment of an FII(sr) strain, did not synthesize either the hemolysin or the antigen. This mutant still possessed the group antigen and streptomycin resistance. A close linkage of type II antigen and beta-hemolysin is indicated. The fluorescent-antibody staining of cells containing both group and type antigens showed a more intense ultraviolet adsorption for type than group antigen. A surface location (microcapsular) for the type antigen appeared likely. These results are of interest for studies on antigen biosynthesis, genetics, and classification of the streptococci.     

A convenient one-step synthesis of L-aminotryptophans and improved synthesis of 5-fluorotryptophan

A one-pot biotransformation for the generation of a series of L-aminotryptophans using a readily prepared protein extract containing tryptophan synthase is reported. The extract exhibits remarkable stability upon freeze-drying, and may be stored and used for long periods after its preparation without significant loss of activity.     

alpha-t-butyl- and alpha-i-propyl-ortho-hydroxybenzylamines: racemic synthesis/resolution and asymmetric synthesis

Efficient routes to alpha-tert-butyl- and alpha-iso-propyl-ortho-hydroxybenzylamines 1a and 1b are described. Highly enantioenriched 1a and 1b were obtained by resolution of the methoxy derivatives 2 by recrystallization of the salts formed with mandelic acid followed by Lewis acid mediated demethylation. The chiral 1,3-amino alcohol 1a has also been obtained in an asymmetric synthesis with the key step a diastereoselective alkylation of the imine obtained by condensation of o-anisaldehyde with phenyl glycinol. The absolute stereochemistry of these 1,3-aminophenols was determined by CD spectroscopy of the salicylideneamines 12 and by an X-ray structure analysis of the salt formed between (R)-mandelic acid and (S)-alpha-tert-butyl-ortho-methoxybenzylamine ((S)-2a).     

Design and synthesis of glycodendrimers

Multivalent neoglycoconjugates with well-defined structures have considerable potential as inhibitors of cell surface protein-carbohydrate interactions and as tools for studying such recognition processes in vitro. In this review, we outline strategies and synthetic methods for making one such class of neoglycoconjugates based on dendrimers--the so-called glycodendrimers. Glycodendrimers can be classified as: (i) carbohydrate-coated; (ii) carbohydrate-centered; and (iii) fully carbohydrate-based. Approaches to their construction have included both the modification of commercially available dendrimers and de novo dendrimer synthesis. Examples from the authors' and other laboratories are drawn upon to illustrate design considerations and the application of dendritic synthetic principles--including divergent and convergent syntheses--for making glycodendrimers. Key coupling reactions for the synthesis of glycodendrimers include: amide and thiourea formation; glycosylation; photoaddition to allyl ethers; and reductive amination. The advantages and disadvantages of using protected and unprotected saccharide building blocks and potential applications for glycodendrimers in both biotechnology and materials science are also discussed.     

Enhancement of RNA synthesis, protein synthesis, and abscission by ethylene

Ethylene stimulated RNA and protein synthesis in bean (Phaseolus vulgaris L. var. Red Kidney) abscission zone explants prior to abscission. The effect of ethylene on RNA synthesis and abscission was blocked by actinomycin D. Carbon dioxide, which inhibits the effect of ethylene on abscission, also inhibited the influence of ethylene on protein synthesis. An aging period appears to be essential before bean explants respond to ethylene. Stimulation of protein synthesis by ethylene occurred only in receptive or senescent explants. Treatment of juvenile explants with ethylene, which has no effect on abscission also has no effect on protein synthesis. Evidence in favor of a hormonal role for ethylene during abscission is discussed.     

Glycoconjugate synthesis during early pregnancy: hyaluronate synthesis and function

The synthesis of various glycoconjugate classes by mouse uteri during the pre- and peri-implantation period has been examined using [3H]glucosamine as a metabolic precursor. A unique and dramatic (five- to sixfold) increase was observed in the synthesis of hyaluronate on the day upon which embryo implantation normally occurs. Mated, but nonpregnant mice did not display increased hyaluronate biosynthesis. In contrast to hyaluronate, the synthesis of most other types of glycoconjugates remained fairly constant during the first 5 days of pregnancy. Low (1500-5000)-molecular-weight N-linked oligosaccharides constituted the major class of oligosaccharides synthesized under all conditions. High (greater than 10,000)-molecular-weight glycoconjugates constituted the second most abundant class of glycoconjugates synthesized (20-30%). Most (85%) of the newly synthesized hyaluronate was associated with the nonepithelial cell types of the uterus. Experiments using ovariectomized mice receiving steroid hormones demonstrated that uterine hyaluronate synthesis was induced preferentially by an artificial decidual stimulus and implicated stromal cells as the site of hyaluronate synthesis. In addition, it was demonstrated that tissue culture plates coated with hyaluronate, but not other polysaccharides, support attachment and spreading of a large fraction (60 to 70%) of embryos cultured in serum-free medium. Collectively, these studies indicate that increased hyaluronate biosynthesis accompanies decidual responses in the endometrium and may promote embryo implantation following initial penetration of the uterine epithelium.     

Inhibition by warfarin of prothrombin synthesis and of lipid-saccharide synthesis in rat liver

In vivo and in vitro studies using [³H]glucosamine incorporation into prothrombin and into glycolipids were conducted in rat liver to determine the role of lipid-saccharides in the biosynthesis of prothrombin.In vivo studies demonstrated that 10 mg warfarin/kg inhibited the incorporation of radiolabeled glucosamine into liver prothrombin and glycolipids. This inhibition was similar to the kinetics of inhibition of prothrombin synthesis in the liver.In vitro studies demonstrated a time-dependent increase in the incorporation of radiolabeled glucosamine into lipid-saccharides and prothrombin. This incorporation was inhibited 50% by 5 · 10^?4 M warfarin. Warfarin also inhibited the incorporation of radiolabeled glucosamine into glycolipids in a dose-related manner.In all studies, vitamin K-1 reversed the inhibition of glucosamine incorporation into glycolipids and into prothrombin.     

Inhibition by butylated hydroxytoluene of excision repair synthesis and semiconservative DNA synthesis

Butylated hydroxyutoluene (BHT), a commonly used food antioxidant, inhibited excision repair synthesis in normal human peripheral lymphocytes damaged by uv light. Inhibition increased with increasing drug concentration to give 50% inhibition at approximately 20 μM. The acid, aldehyde, and alcohol derivatives at the 4-methyl position did not inhibit significantly DNA repair synthesis while semiconservative DNA synthesis was inhibited by both BHT and the metabolites. The significance of these findings to the reported biological effects of the antioxidant is unknown.     

The fidelity of DNA synthesis by eukaryotic replicative and translesion synthesis polymerases

In their seminal publication describing the structure of the DNA double helix , Watson and Crick wrote what may be one of the greatest understatements in the scientific literature, namely that ＂It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.＂ Half a century later, we more fully appreciate what a huge challenge it is to replicate six billion nucleotides with the accuracy needed to stably maintain the human genome over many generations. This challenge is perhaps greater than was realized 50 years ago, because subsequent studies have revealed that the genome can be destabilized not only by environmental stresses that generate a large number and variety of potentially cytotoxic and mutagenic lesions in DNA but also by various sequence motifs of normal DNA that present challenges to replication. Towards a better understanding of the many determinants of genome stability, this chapter reviews the fidelity with which undamaged and damaged DNA is copied, with a focus on the eukaryotic B- and Y-family DNA polymerases, and considers how this fidelity is achieved.     

Design and synthesis of simplified sordaricin derivatives as inhibitors of fungal protein synthesis

A reduction of the tetracyclic skeleton of sordarins and sordaricins to a cyclopentane ring bearing the pharmacophore functional groups led to new derivatives retaining part of their in vitro and whole-cell activity.