Optimisation of fungal glucoamylase production by Response Surface Methodology and characterisation of the purified enzyme

A statistical approach was made for the production of glucoamylase by Aspergillus niger using wheat bran and green gram as fermentation medium. Box-Behnken design used to analyse the simultaneous impact of the substrate, hydration, inoculum volume, fermentation time and temperature, using a second-order polynomial. The experimental results were in good agreement with the proposed regression model with R2 = 0.9322 (p<0.05). The maximum yield (313 U/gds against the predicted value of 306 U/gds) was obtained using 12 gm substrate, 55% moisture, 1 gm sucrose and 0.05 gm tryptone. The purification and characterisation of the enzyme were also studied. Optimum thermal and pH stability was 60 °C and 5 respectively

Genetic variability of attachment (G) and Fusion (F) protein genes of human metapneumovirus strains circulating during 2006-2009 in Kolkata, Eastern India

<p>Abstract</p> <p>Background</p> <p>Human metapneumovirus (hMPV) is associated with the acute respiratory tract infection (ARTI) in all the age groups. However, there is limited information on prevalence and genetic diversity of human metapneumovirus (hMPV) strains circulating in India.</p> <p>Objective</p> <p>To study prevalence and genomic diversity of hMPV strains among ARTI patients reporting in outpatient departments of hospitals in Kolkata, Eastern India.</p> <p>Methods</p> <p>Nasal and/or throat swabs from 2309 patients during January 2006 to December 2009, were screened for the presence of hMPV by RT-PCR of nucleocapsid (N) gene. The G and F genes of representative hMPV positive samples were sequenced.</p> <p>Results</p> <p>118 of 2309 (5.11%) clinical samples were positive for hMPV. The majority (≈80%) of the positive cases were detected during July−November all through the study period. Genetic analysis revealed that 77% strains belong to A2 subgroup whereas rest clustered in B1 subgroup. G sequences showed higher diversity at the nucleotide and amino acid level. In contrast, less than 10% variation was observed in F gene of representative strains of all four years. Sequence analysis also revealed changes in the position of stop codon in G protein, which resulted in variable length (217-231 aa) polypeptides.</p> <p>Conclusion</p> <p>The study suggests that approximately 5% of ARTI in the region were caused by hMPV. This is the first report on the genetic variability of G and F gene of hMPV strains from India which clearly shows that the G protein of hMPV is continuously evolving. Though the study partially fulfills lacunae of information, further studies from other regions are necessary for better understanding of prevalence, epidemiology and virus evolution in Indian subcontinent.</p

A Radio Spectral Line Study of the 2-Jy IRAS-NVSS Sample: Part I

We present results from an on-going survey for the HI 21 cm line and the OH 18 cm lines in IR galaxies with the Arecibo 305 m Radio Telescope. The observations of 85 galaxies extracted from the 2 Jy IRAS-NVSS sample in the R.A. (B1950) range 20 h-00 h are reported in this paper. We detected the HI 21 cm line in 82 of these galaxies, with 18 being new detections, and the OH 18 cm lines in 7 galaxies, with 4 being new detections. In some cases, the HI spectra show the classic double-horned or single-peaked emission profiles. However, the majority exhibit distorted HI spectral features indicating that the galaxies are in interacting and/or merging systems. From these HI and OH observations, various properties of the sample are derived and reported.Comment: 38 pages, 7 figures, 9 tables. Accepted for publication in A

Point Source C-Band Mueller Matrices for the Green Bank Telescope

C-Band Mueller matrices for the Green Bank Telescope are presented here which enable on-sky Stokes parameters for point sources at the beam center to be determined. Standard calibrators, 3C138 and 3C286, were observed using the Spider program to steer the telescope across a broad range of Right Ascensions on both sides of the zenith transit. For this analysis, only the observations at the peak of the Spider pattern were used rather than the full sweep of the runs. Therefore, the results presented here only apply to point sources at the beam center. The Mueller matrices are shown to vary with frequency and with use of the Hi-Cal or Lo-Cal noise diodes, due to the relative calibration gain between the X and Y components of the feed. However, the relative calibration gain can be determined from observations of a source with known polarization. Correcting the data for the relative calibration gain prior to data analysis allows for use of a frequency independent Mueller matrix. This generic Mueller matrix is shown to provide reliable C-Band polarization measurements.Comment: Acceptance for publication in The Astronomical Journa

Mueller Matrix Parameters for Radio Telescopes and their Observational Determination

Modern digital crosscorrelators permit the simultaneous measurement of all four Stokes parameters. However, the results must be calibrated to correct for the polarization transfer function of the receiving system. The transfer function for any device can be expressed by its Mueller matrix. We express the matrix elements in terms of fundamental system parameters that describe the voltage transfer functions (known as the Jones matrix) of the various system devices in physical terms and thus provide a means for comparing with engineering calculations and investigating the effects of design changes. We describe how to determine these parameters with astronomical observations. We illustrate the method by applying it to some of the receivers at the Arecibo Observatory.Comment: 23 pages, 2 figures; accepted for PAS

Conjugate 18cm OH Satellite Lines at a Cosmological Distance

We have detected the two 18cm OH satellite lines from the $z \sim 0.247$ source PKS1413+135, the 1720 MHz line in emission and the 1612 MHz line in absorption. The 1720 MHz luminosity is $L_{\rm OH} \sim 354 L_\odot$, more than an order of magnitude larger than that of any other known 1720 MHz maser. The profiles of the two satellite lines are conjugate, implying that they arise in the same gas. This allows us to test for any changes in the values of fundamental constants, without being affected by systematic uncertainties arising from relative motions between the gas clouds in which the different lines arise. Our data constrain changes in $G \equiv g_p [\alpha^2/y]^{1.849}$, where $y \equiv m_e/m_p$; we find $\Delta G/G = 2.2 \pm 3.8 \times 10^{-5}$, consistent with no changes in $\alpha$, $g_p$ and $y$.Comment: 5 pages, 1 figure. Minor changes to match published versio