Role of purine base excretion in regulation of purine pools

Summary The UV induced mutation frequency of a given base pair located at different sites within the CYC1 gene of Saccharomyces cerevisiae was found to vary by more than fifty fold, indicating the existence of hotspots and coldspots typical of those found in other organisms. We were unable, however, to find any feature of the nucleotide sequence at or near the sites of mutation that explains this variability. These and other data suggest that hotspots are not located within regions particularly susceptible to the formation of premutational lesions. More probably the variation in mutability depends on differences in the activity of enzymes responsible for producing mutations, though the reasons for these differences are not understood and may depend on factors not directly related to nucleotide sequence.     

Overview of the advances in plant microbial fuel cell technology for sustainable energy recovery from rhizodeposition

In plant microbial fuel cells (p-MFCs) electrochemically active microbes present around the plant root convert rhizodeposits or the organic matter into electrons, protons, and CO₂. This work covers the increasing trend in research with p-MFCs with their mechanism of operation. Different plant species and their selection criteria are also covered. Furthermore, the long-term evaluation of such systems with its cost effectiveness and commercial and environmental perspectives are also presented. A critical aspect for bioelectricity production is the photosynthetic pathway of the plant. Additionally, the microbial communities and reactor configurations employed across different capacities are also reviewed. The challenges with bioelectricity production and the opportunity for developing p-MFCs in conjunction with traditional MFCs are also covered. These electrogenic reactor systems harness bioelectricity without harvesting the plant and has the capacity to utilize this energy for remote power applications.     

Modeling of Noisy Spindle Dynamics Reveals Separable Contributions to Achieving Correct Orientation

The mechanisms by which the mammalian mitotic spindle is guided to a predefined orientation through microtubule-cortex interactions have recently received considerable interest, but there has been no dynamic model that describes spindle movements toward the preferred axis in human cells. Here, we develop a dynamic model based on stochastic activity of cues anisotropically positioned around the cortex of the mitotic cell and we show that the mitotic spindle does not reach equilibrium before chromosome segregation. Our model successfully captures the characteristic experimental behavior of noisy spindle rotation dynamics in human epithelial cells, including a weak underlying bias in the direction of rotation, suppression of motion close to the alignment axis, and the effect of the aspect ratio of the interphase cell shape in defining the final alignment axis. We predict that the force exerted per cue has a value that minimizes the deviation of the spindle from the predefined axis. The model has allowed us to systematically explore the parameter space around experimentally relevant configurations, and predict the mechanistic function of a number of established regulators of spindle orientation, highlighting how physical modeling of a noisy system can lead to functional biological understanding. We provide key insights into measurable parameters in live cells that can help distinguish between mechanisms of microtubule and cortical-cue interactions that jointly control the final orientation of the spindle.     

Synergistic effect of two β globin gene cluster mutations leading to the hereditary persistence of fetal hemoglobin (HPFH) phenotype

Co-inheritance of gamma and beta globin gene mutations in a compound heterozygous state is rare but of clinical interest as it provides an important data on understanding the HbF expression. Hematological analysis was carried out (Sysmex KX-21). F-cells were enumerated using flow cytometry. Beta globin gene was analysed by CRDB technique and by DNA sequencing. Gamma globin promoter region was sequenced and expression studies were carried out using real time Taqman assay. We report a family, where two inherited defects of the β globin gene cluster segregate. The proband and her sibling were compound heterozygotes for a novel ^Gγ promoter mutation and the 619 bp deletion a common Indian β thalassemia mutation. Molecular characterization revealed that the father (HbA₂ 5.1%, HbF 5.4%), proband (HbA₂ 3.6%, HbF 31.7%) and her brother (HbA₂ 3.9%, HbF 23.6%) were heterozygous for the 619 bp deletion. The mother (HbA₂ 2.1%, HbF 3.4%) had a normal β globin gene. As both the children showed high HbF levels, the γ globin gene work up was carried out. The ^Gγ-globin gene promoter analysis revealed that the mother and the two children were heterozygous for a 5 bp deletion -ATAAG (-533 to -529) that resides in the GATA binding site. These findings suggest that the 5 bp deletion in the ^Gγ globin promoter has a functional role in silencing the γ-globin gene expression in adults by disrupting GATA-1 binding and the associated repressor complex and results in the up-regulation of gamma globin gene expression. When co-inherited with β -thalassemia trait it leads to a phenotype of HPFH.     

Rapid isolation of monosialogangliosides from bovine brain gangliosides by selective-overload chromatography.

A procedure for rapid isolation of monosialogangliosides from purified bovine brain gangliosides has been developed. It utilizes the selective difference in association between monosialogangliosides and polysialogangliosides for the ion-exchange resin Q-Sepharose. When the ion-exchange column is overloaded with a bovine brain ganglioside mixture in the proper ganglioside to column bed-volume ratio, the polysialogangliosides are selectively retained by the column while the monosialogangliosides emerge with the void volume without the use of salt for elution. With the critical ganglioside to bed-volume ratio (1 g:8.32 ml), and an appropriate column bed-height to column radius ratio of 6.9, monosialogangliosides are reproducibly obtained in high purity with greater than 90% yield. The method has been used at both the analytical and preparative scale. We call this separation technique selective-overload chromatography.     

Conservation and Propagation of High Altitude Medicinal and Aromatic Plant: Hedychium spicatum

The micropropagation of H.spicatum, a medicinal and aromatic plant was investigated as an option for conservation and propagation, as wild populations are fast depleting. The source of raw material is rhizomes of plants that are collected from the wild. There is no planned cultivation of the plant. Multiple shoot cultures were established on MS medium supplemented with BAP and IAA from the pre-existing buds on the rhizome. Prolonged cultivation on the same medium or transfer to hormone free medium induced roots/rhizome formation; liquid medium proved more suitable. Greenhouse hardened plants were transferred to field. A successful protocol with 99% root formation and 80–85.5% field survival has been formulated.