Induced variations in microorganisms

Genetic transfer of markers has been found to occur through a sexual cycle between intact cells in a mixed culture of two different genotypes. When rS (radiosensitive and streptomycin resistant) and Rs (radioresistant and streptomycin sensitive) cells ofRhizobium trifolii were brought into varying periods of cellular contact, the cell mixture yielded RS recombinants. The recombination frequency was higher in young mating cultures than in aged ones. Except for the acquisition of the R and S markers, the recombinants did not differ appreciably from the parental strains in other characters.     

Production technology of Scenedesmus acutus in the Indian context

Summary The West German Dortmund production procedure for the green alga Scenedesmus acutus has been practically evaluated under Indian conditions utilising 179 m² of cultivable area to produce about 26.7 kg of dried algae per week. For a 16 day out-door production schedule, cleaning of cultivation tanks takes 27% of the total man hours required, and indoors inoculum preparation takes 20%. Electrical energy consumption depends mainly on the drying mode used but irrespective of any change in the system the cost structure remains high for Indian contexts.     

Synchronous cell divisions in Anacystis nidulans Richter

Summary The blue-green alga, Anacystis nidulans was successfully synchronized in continuous light (15,000 lux) by a 14 hr cycle, consisting of 8 hrs at 26°C, and 6 hrs at 32°C, coupled with periodic dilution of the algal suspension to a constant cell number at the end of each cycle. The alga continues to grow at the lower temperature, and a division burst begins 2 hrs after transfer to the higher temperature.

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Zusammenfassung Die Cyanophycee Anacystis nidulans wurde in Dauerlicht von 15 000 Lux vollständig synchronisiert. Die Cyclen bestehen aus 8 Std bei 26° C und 6 Std bei 32° C, an ihrem Ende wurde jeweils mit frischer Nährlösung auf die Ausgangszellzahl von 3·10⁷ Zellen/ml verdünnt. Bei beiden Temperaturen kann sich die Alge vermehren, unter den synchronisierenden Bedingungen des Temperaturwechsels beginnt der Teilungsschub (Verdopplung der Zellzahl) bei 32° C nach 2 Std.

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Pringsheim (1968) renamed this alga as Lauterbornia nidulans.     

Radioprotection by N-palmitoylated nonapeptide of human interleukin-1beta

Interleukin-1beta (IL-1beta) is a cytokine involved in homeostatic processes of the immune system and specifically in inflammatory reactions. The nonapeptide of human IL-1beta (VQGEESNDK, position 163-171) has been shown to retain adjuvant and immunostimulatory activities of the native molecule without any inflammatory and pyrogenic properties. A lipophilic derivative of IL-1beta nonapeptide having a palmitoyl residue at the amino terminus was synthesized in order to determine the effects of such structural modification on its bioactivities. The structurally modified peptide derivative, palmitoylated peptide, significantly protected C3H/HeN mice against potentially lethal doses of ionizing radiation. The dose reduction factor was found to be 1.07. Hematological studies show improved recovery of red blood cells and platelets in irradiated and palmitoylated peptide treated mice as compared with the untreated and irradiated group. These results suggest the importance of the derivatization of small peptides of radioprotective, but toxic cytokines in order to enhance radioprotective activity while reducing unwanted toxic side effects.     

Response ofWestiellopsis prolifica andAnabaena sp. to salt stress

Summary The response of a salt-tolerantWestiellopsis prolifica ARM 366 and a sensitiveAnabaena C-10 to NaCl was studied. While the former could tolerate up to 400mm NaCl, the latter was highly sensitive to concentrations above 50mm NaCl. Under salt stress, the tolerantW. prolifica showed an increased nitrogen demand as exemplified by high nitrogenase activity, and growth inhibition at higher concentrations of NaCl did not appear to be a direct consequence of inhibition of nitrogen fixation. One of the striking responses to Na⁺ challenge by the tolerantW. prolifica was the excess production of extracellular polysaccharides which adsorbed the bulk of the Na⁺. The influx of Na⁺ into the cell was comparatively small.

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Resumen Se estudió la respuesta al NaCl deWestiellopsis prolifica ARM 366, organismo tolerante a la sal, y deAnabaena C-10 que es sensible. El primero pudo tolerar concentraciones de hasta 400mm NaCl, sin embargo Anabaena C-10 se mostró extremadament sensible a concentraciones superiores a 50mm de NaCl. Bajo condiciones de estrés salinoW. prolifica mostró un incremento en la demanda de N₂, como se deduce de la elevada actividad nitrogenásica; la inhibición del crecimiento a concentraciones superiores de NaCl no se pudo relacionar directamente con la inhibición de la fijación de nitrógeno. Una de las respuestas más sorprendentes deW. prolifica frente al Na⁺ fue la producción de un exceso de polisaccaridos extracelulares que absorbieron gran parte del Na⁺. El flujo de Na⁺ hacia la célula fue, pues, comparativemente pequeño.

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Résumé On a étudié la réponse au NaCl d'une souche halo-tolérante deWestiellopsis prolifica (ARM 366) et, d'une souche halo-sensible d'Anabaena (C-10). Alors que la première tolère jusqu'a 400mm NaCl, la seconde est hautement sensible aux concentrations supérieures à 50mm. Soumise à un choc de salinité, la souche halo-tolérante deW. prolifica présente une demande d'azote accrue, comme le montre une activité nitrogénase élevée, et l'inhibition de la croissance par une forte concentration en NaCl ne parait pas être la conséquence directe d'une inhibition de la fixation d'azote. Une réponse remarquable deW. prolifica à l'agression par Na⁺ est la production en excès de polysaccharides exo-cellulaires, qui absorbent la plus grande partie du Na⁺. La pénétration de Na⁺ dans la cellule est relativement faible.

     

Measurement of chronic oxidative and inflammatory stress by quantification of isoketal/levuglandin gamma-ketoaldehyde protein adducts using liquid chromatography tandem mass spectrometry

Measurement of F(2)-isoprostanes (F(2)-IsoPs) has been independently verified as one of the most reliable approaches to assess oxidative stress in vivo. However, the rapid clearance of F(2)-IsoPs makes the timing of sample collection critical for short-lived oxidative insults. Isoketals (IsoKs) are gamma-ketoaldehydes formed via the IsoP pathway of lipid peroxidation that rapidly react with lysyl residues of proteins to form stable protein adducts. Oxidative stress can also activate cyclooxygenases to produce prostaglandin H(2), which can form two specific isomers of IsoK-levuglandin (LG) D(2) and E(2). Because adducted proteins are not rapidly cleared, IsoK/LG protein adduct levels can serve as a dosimeter of oxidative and inflammatory damage over prolonged periods of time as well as brief episodes of injury. Quantification of IsoK/LG protein adducts begins with liquid-phase extraction to separate proteins from lipid membranes, allowing measurement of both IsoK/LG protein adducts and F(2)-IsoP from the same sample if desired. IsoK/LG-lysyl-lactam adducts are measured by liquid chromatography tandem mass spectrometry after proteolytic digestion of extracted proteins, solid-phase extraction and preparative HPLC.     

Identification and Characterization of a Compound That Protects Cardiac Tissue from Human Ether-à-go-go-related Gene (hERG)-related Drug-induced Arrhythmias

The human Ether-à-go-go-related gene (hERG)-encoded K⁺ current, I_Kr is essential for cardiac repolarization but is also a source of cardiotoxicity because unintended hERG inhibition by diverse pharmaceuticals can cause arrhythmias and sudden cardiac death. We hypothesized that a small molecule that diminishes I_Kr block by a known hERG antagonist would constitute a first step toward preventing hERG-related arrhythmias and facilitating drug discovery. Using a high-throughput assay, we screened a library of compounds for agents that increase the IC₇₀ of dofetilide, a well characterized hERG blocker. One compound, VU0405601, with the desired activity was further characterized. In isolated, Langendorff-perfused rabbit hearts, optical mapping revealed that dofetilide-induced arrhythmias were reduced after pretreatment with VU0405601. Patch clamp analysis in stable hERG-HEK cells showed effects on current amplitude, inactivation, and deactivation. VU0405601 increased the IC₅₀ of dofetilide from 38.7 to 76.3 nm. VU0405601 mitigates the effects of hERG blockers from the extracellular aspect primarily by reducing inactivation, whereas most clinically relevant hERG inhibitors act at an inner pore site. Structure-activity relationships surrounding VU0405601 identified a 3-pyridiyl and a naphthyridine ring system as key structural components important for preventing hERG inhibition by multiple inhibitors. These findings indicate that small molecules can be designed to reduce the sensitivity of hERG to inhibitors.     

Molecular analysis of gut microbiota in obesity among Indian individuals

Obesity is a consequence of a complex interplay between the host genome and the prevalent obesogenic factors among the modern communities. The role of gut microbiota in the pathogenesis of the disorder was recently discovered; however, 16S-rRNA-based surveys revealed compelling but community-specific data. Considering this, despite unique diets, dietary habits and an uprising trend in obesity, the Indian counterparts are poorly studied. Here, we report a comparative analysis and quantification of dominant gut microbiota of lean, normal, obese and surgically treated obese individuals of Indian origin. Representative gut microbial diversity was assessed by sequencing fecal 16S rRNA libraries for each group (n=5) with a total of over 3000 sequences. We detected no evident trend in the distribution of the predominant bacterial phyla, Bacteroidetes and Firmicutes. At the genus level, the bacteria of genus Bacteroides were prominent among the obese individuals, which was further confirmed by qPCR (P less than 0.05). In addition, a remarkably high archaeal density with elevated fecal SCFA levels was also noted in the obese group. On the contrary, the treated-obese individuals exhibited comparatively reduced Bacteroides and archaeal counts along with reduced fecal SCFAs. In conclusion, the study successfully identified a representative microbial diversity in the Indian subjects and demonstrated the prominence of certain bacterial groups in obese individuals; nevertheless, further studies are essential to understand their role in obesity.