Thymic cell populations in amphibia: Quantitative study of the growth,stability, and regression of the cell populations in the thymus of the newtPleurodeles waltlii Michah

Summary Twenty days after fertilization (stage 40) the thymus ofPleurodeles waltlii consists of two main cell types: epithelial reticular cells (71%) and lymphoid stem-cells (24%).Between day 20 and day 72 (stage 53) the lymphoid stem-cells differentiate into lymphocytes, via the lymphoblast state. Commencing at day 20, epithelial reticular cells are transformed into epithelial reticular dense cells. Following day 65, other epithelial reticular cells begin to differentiate into epithelial hypertrophic cells, and these subsequently form thymic cysts. During this whole period intense proliferation takes place.The three types of polynuclear cells (neutrophil, eosinophil, and basophil), the macrophages, and the plasmocytes differentiate outside the thymus then migrate into it through the vascular system.Around day 72 (stage 53), the mature thymus consists of two parts: the first is visible as a background or cortex-like area, the second comprises medulla like spots, formed by small numbers of cysts.Around metamorphosis the cell populations reach a stable state.After metamorphosis the relative frequency of the lymphoid cell population progressively decreases, while the proportion of epithelial hypertrophic cells, together with cyst surface area, is increased. Consequently the ratio of cysts/background area increases with age.     

Somatic embryogenesis,regeneration and <Emphasis Type="Italic">in vitro</Emphasis> production of glycyrrhizic acid from root cultures of <Emphasis Type="Italic">Taverniera cuneifolia</Emphasis> (Roth) Arn.

Taverniera cuneifolia (Roth) Arn. or Indian licorice is considered to be a substitute for Glycyrrhiza glabra L. owing to an equivalent content of glycyrrhizic acid (GA). GA recognized as the main active ingredient of T. cuneifolia, GA imparts several medicinal properties to these plants. However, research on this plant is scanty with no published record on tissue culture studies. Present study demonstrates a method for (1) induction and successful development of somatic embryos from the root culture, (2) regeneration of plants, and (3) GA production by root cultures of T. cuneifolia. Shoot initiation frequency of cultured roots ranged from 52.57% to 97.71%. Plant regeneration frequency (germination) from somatic embryos was 88.66% in 1/4-strength Murashige and Skoog (MS) medium supplemented with 2% sucrose, as against 68% in half 1/2-strength MS containing 2% sucrose. Glycyrrhizic acid of 1.32 mg/gm of dry weight was obtained in full-strength MS medium supplemented with 3% sucrose, through high-performance thin layer chromatography analysis with standard GA in root cultures. The present study provides an efficient method for the mass production of plants from a single mother plant as well as the potential root culture system to study the GA production pathways in T. cuneifolia.     

Design,synthesis and anticancer activity of novel pyrimidine and pyrimidine-thiadiazole hybrid glycosides

Abstract

New 1,3,4-thiadiazole thioglycosides linked to substituted pyrimidines were synthesized via glycosylation of 1,3,4-thiadiazole thiol compounds. Also, novel 1,2,3-triazole derivatives linked to carbohydrate units were prepared using the standard click chemistry conditions employing the Cu(I)-catalyzed azide-alkyne cycloaddition of substituted-aryl-azides with a selection of alkyne-functionalized sugars. The chemical structures of the new derivatives were verified using various spectroscopic techniques, such as IR, ¹H NMR, ¹³C NMR and elemental analyses. The cytotoxic activities of the prepared compounds were investigated in vitro against human liver cancer (HepG-2) and human breast adenocarcinoma (MCF7) cell lines. In addition, the biological evaluation of the new compounds involved the investigation of their effects on a human normal retinal pigmented epithelial cell line (RPE1) using the MTT assay.     

What if Fleming had not discovered penicillin?

What would have happened had Alexander Fleming not discovered penicillin in 1928? Perhaps the obvious answer is that, someone else would have discovered penicillin during 1930s and the Oxford group, would still have purified it sometime in the early 1940s. Here, however, in this counterfactual account of the penicillin story, it is argued that without Fleming, penicillin might still be undiscovered and the antibiotic age would never have dawned. As a result, many of the recent developments in medicine, such as organ transplantation, might have been delayed or, at best, made more hazardous. Penicillin might have come onto the scene a few years later but, had Fleming overlooked the discovery, it seems certain that penicillin would not have saved countless Allied lives, during and after D-Day. Instead of having enjoyed fifty and more years of the antibiotic age, it is argued here, that we would have had to rely upon highly developed sulphonamides, so-called “supasulfas”, and other chemically-derived antibacterial drugs. Indeed, it might be the case that, even well into this new millennium, the antibiotic age has yet to dawn, and medicine is still waiting for someone to chance upon penicillin. Here we discuss what might have happened had Fleming not discovered penicillin and come to the conclusion that the medical armoury available today would have been far different and might have relied solely upon highly developed varieties of sulphonamides or similar, synthetic, non-antibiotic antibacterial agents.     

Detection and Capturing of <Superscript>14</Superscript>C Radioactively-Labeled Small Subunit rRNA from Mixed Microbial Communities of a Microbial Mat Using Magnetic Beads

Carbon cycling in the hypersaline microbial mats from Chiprana Lake, Spain is primarily dependent on phototrophic microorganisms with the ability to fix CO₂ into organics that can be further utilized by aerobic as well as anaerobic heterotrophic bacteria. Here, mat pieces were incubated in seawater amended with ¹⁴C sodium bicarbonate and the incorporation of the radiocarbon in the small subunit ribosomal RNA (SSU rRNA) of mat organisms was followed using scintillation counter and autoradiography. Different domains of SSU rRNA were separated from the total RNA by means of streptavidin-coated magnetic beads and biotin-labeled oligonucleotide probes. The ¹⁴C label was detected in isolated RNA by both scintillation counter and autoradiography, however the latter technique was less sensitive. Using scintillation counter, the radiolabel incorporation increased with time with a maximum rate of 0.18 Bq ng⁻¹ detected after 25 days. The bacterial SSU rRNA could be captured using the magnetic beads, however the hybridization efficiency was around 20%. The captured RNA was radioactively labeled, which could be mainly due to the fixation of radiocarbon by phototrophic organisms. In conclusion, the incubation of microbial mats in the presence of radiolabeled bicarbonate leads to the incorporation of the ¹⁴C label into RNA molecules through photosynthesis and this label can be detected using scintillation counter. The used approach could be useful in studying the fate of fixed carbon and its uptake by other microorganisms in complex microbial mats, particularly when species-specific probes are used and the hybridization efficiency and RNA yield are further optimized.