MORPHOLOGICAL AND EMBRYOLOGICAL STUDIES ON THE LEMNACEAE. I. THE FLORAL STRUCTURE AND GAMETOPHYTES OF LEMNA PAUCICOSTATA

Maheshwari, Satish C., and R. N. Kapil. (U. Delhi, Delhi, India.) Morphological and embryological studies on the Lemnaceae. I. The floral structure and gametophytes of Lemna paucicostata. Amer. Jour. Bot. 50(7): 677–686. Illus. 1963.—In Lemna paucicostata, a locally occurring member of the Lemnaceae, the plant body is represented by a frond which is devoid of lignified elements. The root shows a winged root sheath but does not have root hairs. There are no distinctive layers like the endodermis and xylem. The male archesporium is hypodermal and differentiates normally as in other angiosperms into parietal and sporogenous layers. The tapetum is single-layered and plasmodial. The partition walls of the anther are not derived by sterilization of the sporogenous cells as believed earlier. The microspore tetrads are isobilateral and decussate, the meiotic divisions being successive. The pollen grains are shed at the 3-celled stage. The ovary contains a single hemianatropous, bitegminal and crassinucellar ovule. The development of the embryo sac conforms to the Allium type.     

Plasmid elimination from clinical isolates of Echerichia coli by ciprofloxacin and other inhibitors of DNA gyrase

Summary The susceptibility of 50 drug resistant strains of Escherichia coli of human gut was determined against ciprofloxacin, acridine orange (AO) and sodium dodecyl sulphate (SDS). Curing efficacy of these agents were worked out at subminimal inhibitory concentrations. Ciprofloaxacin was found a better curing agent for E coli R-plasmids, eliminating R-factors from 48% of the strains followed by SDS and AO which eliminated 24% and 20% of the drug resistance determinants, respectively. Elimination of R-plasmids was found dependent on the concentrations of curing agents and nature of R-plasmids.     

Toddanol and toddanone,two coumarins from Toddalia asiatica

Two new constituents isolated from the roots of Toddalia asiatica and designated as toddanol and toddanone have been characterized as 5,7-dimethoxy-6-(2-hydroxy-3-methylbut-3-enyl)coumarin (1) and 5,7-dimethoxy-6-(3-methyl-2-oxobutanyl)coumarin (3), respectively, by spectral analysis and interconversion experiments.     

New alkaloids from Glycosmis mauritiana

Chemical investigation of the roots of G. mauritiana resulted in the isolation of two new alkaloids; 1-hydroxy-3-methoxy-2-(3-methylbut-2-enyl)-N-methylacridan-9-one (1) and 4,8-dimethoxy-3-(3-methylbut-2-enyl)-N-methyl-2-quinolone (6). The structures of these new bases have been established by chemical and spectroscopic methods and confirmed in the case of 6 by its synthesis. Interestingly, the formic acid-catalysed cyclisation of 1 gave the dealkylated product 3 along with the pyrano-[2, 3-a]-acridine (4).     

Dietary Mannan-oligosaccharides potentiate the beneficial effects of Bifidobacterium bifidum in broiler chicken

This study investigated the effects of dietary Bifidobacterium bifidum (BFD) and mannan-oligosaccharide (MOS), as a synbiotic, on the production performance, gut microbiology, serum biochemistry, antioxidant profile and health indices of broiler chicken. Six dietary treatments were T1 (negative control), T2 (positive control-20 mg antibiotic BMD kg⁻¹ diet; BMD: bacitracin methylene disalicylate), T3 (0·1% MOS + 10⁶ CFU BFD per g feed), T4 (0·1% MOS + 10⁷ CFU BFD per g feed), T5 (0·2% MOS + 10⁶ CFU BFD per g feed) and T6 (0·2% MOS + 10⁷ CFU BFD per g feed). Significantly (P < 0·01) better growth performance and efficiency was observed in birds supplemented with 0·2% MOS along with 10⁶ CFU BFD per g of feed compared to BMD and control birds. Supplementation with 0·2% MOS along with either 10⁶ or 10⁷ CFU BFD per g feed reduced (P < 0·01) the gut coliform, Escherichia coli, total plate count, and Clostridium perfringens count and increased the Lactobacillus and Bifidobacterium count. Significantly (P < 0·01) higher serum and liver antioxidant enzyme pool, serum HDL cholesterol and lower serum glucose, triglyceride, total cholesterol, cardiac risk ratio, atherogenic coefficient and atherogenic index of plasma were observed in birds supplemented with 0·2% MOS along with 10⁶ CFU BFD per g of feed compared to control or BMD supplemented birds. Better production performance, gut microbial composition, serum biochemistry, antioxidant profile and health indices were depicted by broiler chicken supplemented with 0·2% MOS and 10⁶ CFU BFD per g of feed.     

p-Toluenesulfonyl Chloride Catalysed Facile Synthesis of O-benzyl-l-amino Acids and Their In Vitro Evaluation

International Journal of Peptide Research and Therapeutics - Protection and subsequent deprotection of amino acid functional groups play a key role in regioselective peptide synthesis. For...     

The MultiBac Protein Complex Production Platform at the EMBL

Proteomics research revealed the impressive complexity of eukaryotic proteomes in unprecedented detail. It is now a commonly accepted notion that proteins in cells mostly exist not as isolated entities but exert their biological activity in association with many other proteins, in humans ten or more, forming assembly lines in the cell for most if not all vital functions.^1,2 Knowledge of the function and architecture of these multiprotein assemblies requires their provision in superior quality and sufficient quantity for detailed analysis. The paucity of many protein complexes in cells, in particular in eukaryotes, prohibits their extraction from native sources, and necessitates recombinant production. The baculovirus expression vector system (BEVS) has proven to be particularly useful for producing eukaryotic proteins, the activity of which often relies on post-translational processing that other commonly used expression systems often cannot support.³ BEVS use a recombinant baculovirus into which the gene of interest was inserted to infect insect cell cultures which in turn produce the protein of choice. MultiBac is a BEVS that has been particularly tailored for the production of eukaryotic protein complexes that contain many subunits.⁴ A vital prerequisite for efficient production of proteins and their complexes are robust protocols for all steps involved in an expression experiment that ideally can be implemented as standard operating procedures (SOPs) and followed also by non-specialist users with comparative ease. The MultiBac platform at the European Molecular Biology Laboratory (EMBL) uses SOPs for all steps involved in a multiprotein complex expression experiment, starting from insertion of the genes into an engineered baculoviral genome optimized for heterologous protein production properties to small-scale analysis of the protein specimens produced.^5-8 The platform is installed in an open-access mode at EMBL Grenoble and has supported many scientists from academia and industry to accelerate protein complex research projects.     

Seasonal variations in the mating-related traits of Drosophila melanogaster

The Indian subcontinent shows high levels of seasonal weather variation, but the extent to which mating-related traits (mating latency, copulation duration and number of progeny produced) are being affected by such variations in Drosophila species remain poorly understood. In the present study, we analyzed the effects of seasonal change (humidity and temperature) on mating-related traits of Drosophila melanogaster by mimicking natural conditions in the laboratory. The light body color phenotype is collected in large numbers during the rainy season, while the dark phenotype is prevalent in the winter. We found that a short-term stress, in the form of reduced humidity or temperature, causes a strong climatic selection pressure, which leads to assortative mating and longer copulation duration of the dark phenotype. By contrast, the light phenotype shows higher assortative mating and longer copulation duration after short-term high humidity or high temperature stress. Higher assortative mating and increased copulation duration results in high progeny numbers which may be a cause for the high prevalence of the dark phenotype in winter and the light phenotype in the rainy season. Thus, besides plasticity, seasonal changes in mating propensity can be a potential cause of the change in the frequency of the dark and light phenotypes of D. melanogaster during different seasons.     

Understanding the specificity of serpin–protease complexes through interface analysis

Serpins such as antithrombin, heparin cofactor II, plasminogen activator inhibitor, antitrypsin, antichymotrypsin, and neuroserpin are involved in important biological processes by inhibiting specific serine proteases. Initially, the protease recognizes the mobile reactive loop of the serpin eliciting conformational changes, where the cleaved loop together with the protease inserts into β-sheet A, translocating the protease to the opposite side of inhibitor leading to its inactivation. Serpin interaction with proteases is governed mainly by the reactive center loop residues (RCL). However, in some inhibitory serpins, exosite residues apart from RCL have been shown to confer protease specificity. Further, this forms the basis of multi-specificity of some serpins, but the residues and their dimension at interface in serpin-protease complexes remain elusive. Here, we present a comprehensive structural analysis of the serpin-protease interfaces using bio COmplexes COntact MAPS (COCOMAPS), PRotein Interface Conservation and Energetics (PRICE), and ProFace programs. We have carried out interface, burial, and evolutionary analysis of different serpin-protease complexes. Among the studied complexes, non-inhibitory serpins exhibit larger interface region with greater number of residue involvement as compared to the inhibitory serpins. On comparing the multi-specific serpins (antithrombin and antitrypsin), a difference in the interface area and residue number was observed, suggestive of a differential mechanism of action of these serpins in regulating their different target proteases. Further, detailed study of these multi-specific serpins listed few essential residues (common in all the complexes) and certain specificity (unique to each complex) determining residues at their interfaces. Structural mapping of interface residues suggested that individual patches with evolutionary conserved residues in specific serpins determine their specificity towards a particular protease.