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.     

Estradiol regulation of secretory component: Expression by rat uterine epithelial cells

Sex hormones are known to play an important role in the regulation of mucosal immunity in the female reproductive tract. The purpose of this study was to examine the effect of estradiol (E₂) on secretory component (SC) expression by epithelial cells in the rat uterus and to determine whether SC mRNA is present in uterine tissues and is under hormonal control. When ovariectomized rats treated with E₂ for 3 days and sacrificed 12 h after the last injection, expression of SC on luminal and glandular epithelial cells, as determined by immunohistochemistry, was elevated when compared to control animals. To determine whether E₂ regulation of SC involves mRNA synthesis, uterine RNA was extracted and analyzed by Northern blot. These experiments demonstrated that SC RNA is present in uteri from intact rats and markedly increased when ovariectomized animals are treated with E₂. In other studies, uterine epithelial cells from adult rats were isolated and grown on permeable membranes for 5 to 10 days. Under these conditions, isolated epithelial cells grow to confluence, form tight junctions, and preferentially secrete SC into the apical medium. These studies identify epithelial cells as a key target cell in the uterus for the regulation of mucosal immunity by E₂, which we postulate will play an important role in studies to prevent and/or control the spread of sexually transmitted diseases.     

Steroid hormone responsiveness of a family of closely related mouse proviral elements

Regulation of the mouse sex-limited protein (Slp) gene is unusual in that hormone response is conferred by the 5′ LTR of an upstream inserted provirus, dubbed the imposon (imp1). In a search for additional genes whose regulation has been affected by retrotransposition events, we isolated two partial proviral elements by stringent screening of a mouse genomic library. One clone (imp2) contained a portion of the envelope gene and a 3′ LTR that was nearly identical to the 3′ LTR of imp1; this similarity extended to insertion into a B1 repetitive element. The second proviral clone (imp3) contained a 5′ LTR and associated coding sequences, but lacked its 3′ LTR; the LTR of imp3 differed by 12% from the imp1 sequence. To assess potential hormone response, proviral enhancer regions cloned into reporter vectors were tested in transfection. The imp2 enhancer was similar in behavior to imp1, conferring both androgen and glucocorticoid induction in one fragment context and an androgen-specific response in another. In contrast, the imp3 enhancer allowed high expression in the absence of hormone and was less responsive to steroids in general and androgen in particular. These three proviral elements define a small family of steroid responsive proviruses in the mouse genome, and at least one member has had a lasting impact on an endogenous gene's regulation. Received: 29 April 1997 / Accepted: 14 July 1997     

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.