Functional equivalence of the uridine turn and the hairpin as building blocks of tertiary structure in the Neurospora VS ribozyme.

Mutational, kinetic, and chemical modification experiments show that one of the three-way helical junctions in the Neurospora VS ribozyme contains a uridine turn that is important for organizing the functional three-dimensional structure of this junction. Disruption of the uridine turn disrupts the structure of the junction and decreases the self-cleavage activity of the ribozyme; however, substitution of the uridine turn with a variety of different hairpins, thereby transforming the three-way junction into a four-way junction, maintains catalytic activity. Chemical modification structure probing reveals that both the native junction and the hairpin-containing junction support the same tertiary interactions required elsewhere in the ribozyme for catalysis. These observations show that functionally equivalent three-dimensional RNA structures can be built from different secondary structure elements.     

Embryology ofMalaxis saprophyta,with comments on the systematic position ofMalaxis (Orchidaceae)

InMalaxis saprophyta, anther wall development corresponds to the Monocotyledonous type. The uninucleate tapetum is of secretory type and the endothecium develops U- and V-shaped thickenings on the inner tangential and radial walls. Cytokinesis is simultaneous; tetrahedral, isobilateral and T-shaped tetrads are formed which are compactly aggregated in pollinia. At anthesis the microspore tetrads are 2-celled. The ovule is anatropous, bitegmic and both integuments are dermal in origin. A single hypodermal cell develops directly into a megaspore mother cell. Embryo sac development is predominantly monosporic and less often bisporic. Irrespective of the type of development, the mature embryo sac is 6-nucleate. Although double fertilization occurs, the primary endosperm nucleus degenerates. Embryogeny is of the Onagrad type. The mature embryo lacks differentiation into cotyledon, plumule and radicle. The reticulate seed coat is formed entirely by the outer layer of outer integument. There are three sterile and three fertile valves in the ovary. Although initially parenchymatous, the entire three sterile valves in the ovary and the upper half of the three fertile valves become sclerified after fertilization. The embryological characters support the disputed systematic position ofMalaxis within subtribeMalaxidinae ofEpidendreae.     

Metabolism of Monoterpenes : Evidence for the Function of Monoterpene Catabolism in Peppermint (Mentha piperita) Rhizomes

l-Menthone of peppermint leaves is reduced to d-neomenthol which is glucosylated and transported to the rhizome, whereupon the β-d-glucoside is hydrolyzed, the aglycone oxidized back to l-menthone, and this ketone converted to l-3,4-menthone lactone. l-[G-³H]-3,4-Menthone lactone and its labeled progenitors, when incubated with excised mint rhizomes, gave rise to nonvolatile lipids as well as polar metabolites. The lipids thus generated consisted of labeled squalene and phytosterols in the nonsaponifiable fraction and C₁₄-C₂₆ fatty acids in the saponifiable fraction. These results imply degradation of the terpenoid to acetylcoenzyme A and reduced pyridine nucleotide, and reincorporation of label via these products. Starch and soluble carbohydrates were also found to be labeled; however, chemical degradation of the [³H]glucose obtained on hydrolysis of starch indicated the presence of tritium only on interior carbons, suggesting that labeling had occurred via reduced pyridine nucleotides. Analysis of the labeled organic acids revealed the presence of several hydroxy methylacyl intermediates suggesting the operation of a modified β-oxidation pathway in the degradation of the acyclic terpenoid skeleton. The results indicate that monoterpenes transported to the rhizome are oxidized to yield acetyl-coenzyme A and reduced pyridine nucleotides, and suggest that metabolic turnover of monoterpenes in mint represents a mechanism for recycling carbon and energy from foliar terpenes into other metabolites of the rhizome.     

Removal of endotoxin from antibody preparations for clinical use

Cell Biochemistry and Biophysics - Despite attempts to maintain asepsis, good manufacturing practices, and the use of terminal sterilization by millipore filtration, the nuclear practitioner is...     

Passage number of cancer cell lines: Importance,intricacies, and way-forward

Cancer cell lines play a crucial role as invaluable models in cancer research, facilitating the examination of cancer progression as well as the advancement of diagnostics and treatments. While they may not perfectly replicate the original tumor, they generally exhibit similar characteristics. Low-passage cancer cell lines are generally preferred due to their closer resemblance to the original tumor, as long-term culturing can alter the genetic and molecular profiles of a cell line thereby highlighting the importance of monitoring the passage number (PN). Variations in proliferation, migration, gene expression, and drug sensitivity can be linked to PN differences. PN can also influence DNA methylation levels, metabolic profiles, and the expression of genes/or proteins in cancer cell lines. When conducting research on cancer cell lines, it is crucial for researchers to carefully select the appropriate PN to maintain consistency and reliability of results. Moreover, to ensure dependability and replicability, scientists ought to actively track the growth, migration, and gene/or protein profiles of cancer cell lines at specific PNs. This approach enables the identification of the most suitable range of PNs for experiments, guaranteeing consistent and precise results. Additionally, such efforts serve to minimize disparities and uphold the integrity of research. In this review, we have laid out recommendations for laboratories to overcome these PN discrepancies when working with cancer cell lines.     

ABC transporters mined through comparative transcriptomics associate with organ-specific accumulation of picrosides in a medicinal herb,Picrorhiza kurroa

Protoplasma - Picrorhiza kurroa Royle ex Benth is a valuable medicinal herb of North-Western Himalayas due to presence of two major bioactive compounds, picroside-I and picroside-II used in the...     

Haemonchus contortus: The in vitro effects of dl-tetramisole and rafoxanide on glycolytic enzymes

Kaur R. and Sood M. L. 1982. Haemonchus contortus: the in vitro effects of dl-tetramisole and rafoxanide on glycolytic enzymes. International Journal for Parasitology 12: 585–588. Various enzymes of glycolysis (hexokinase, phosphoglucomutase, phosphoglucoisomerase, adolase, glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, phosphoglyceromutase-enolase-pyruvate kinase and lactate dehydrogenase) have been detected in adult Haemonchus contortus. Low pyruvate kinase and lactate dehydrogenase activities suggested an alternate pathway from phosphoenolpyruvate. In vitro incubation had no significant effects on these enzymes and the worm was able to maintain normal metabolism for 12 h. Varying degrees of inhibition of glycolytic enzymes were observed with 50 μg/ml of dl-tetramisole and rafoxanide. The enzymes were inhibited to a greater extent by dl-tetramisole. These effects may block the glycolytic pathway and deprive the parasite of its ATP production.