Fusion of two F-prime factors inEscherichia coli studied by electron microscope heteroduplex analysis

Summary A fused F prime factor was obtained from a mating of arecA donor carrying an F' factor containing the genesmetBJF, ppc andargECBH (KLF5) with arecA recipient carrying an F' factor containingatt80, trp andlac (F155). Lysogenization of this fused F-prime factor with cI⁸⁵⁷ h80 phage followed by thermoinduction produced the transducing phages 80dmetBJF and 80dppcargECBH. This kind of fusion provides a general procedure for the construction of transducing phages carrying genes from different regions of theE. coli genome. To understand the mechanism of this fusion, the parental F prime factors (F155 and KLF5) were analyzed by the electron microscope heteroduplex technique.F155 has a length of 176±3 kilobases including two substitutions. The F sequence 0 F-2.8 F has been substituted by 53 kb of chromosomal DNA including thelac operon and the F sequences 8.5 F-16.3 F has been substituted by 27 kb of a chromosomal sequence includingatt80 and thetrp operon.KLF5 contains 221±4 kilobases of DNA (molecular weight, 148 megadaltons). It contains complete F and the segment of theE. coli chromosome frompolA torif. The F sequence 2.8 F-8.5 F known to be involved in F specific recombination inrecA ⁺ andRecA backgrounds occurs twice on KLF5, once at each of the junctions of F DNA with chromosomal DNA. The population of closed circular plasmid molecules extracted from KLF5-containing strains is heterogeneous. It is proposed that this heterogeneity is due to intramolecular recombination events occurring in KLF5 between the duplicated 2.8 F-8.5 F sequences. Such recombination can account for the genetic instability of KLF5 observed in bothrecA ⁺ andrecA hosts. The F sequence 2.8 F-8.5 F (also called ) is one of the characterized integration sequences on F.A model for the fusion of the parental F prime factors is proposed in which recombination between sequences bringsatt80 close to themetBJF genes. This is followed by a deletion of an F'lac factor. The resulting fused F' factor still carries two sequences and is therefore expected to be unstable. The closed circular molecules isolated from the fused F' containing strains show two different sizes of molecules. Genetic and physical analyses of these molecules are in agreement with the predicted instability of the fused F' factor and the existance of the sequence in the 80dmet phages isolated from fused F' and previously analyzed by the electron microscope heteroduplex technique.     

Multi-layered Graphene Silica-Based Tunable Absorber for Infrared Wavelength Based on Circuit Theory Approach

Graphene can be utilized as a tunable material for a wide range of infrared wavelength regions due to its tunable conductivity property. In this paper, we use Y-shaped silver material resonator placed over the top of multiple graphene silica-layered structures to realize the perfect absorption over the infrared wavelength region. We propose four different designs by placing the graphene sheet over silica. The absorption and reflectance performance of the structures have been explored for 1500- to 1600-nm wavelength range. The proposed design also explores the absorption tunability of the structure for the different values of graphene chemical potential. We have reported the negative impedance for the perfect absorption for proposed metamaterial absorber structures. All the metamaterial absorbers have reported 99% of its absorption peaks in the infrared wavelength region. These designs can be used as a tunable absorber for narrowband and wideband applications. The proposed designs will become the basic building block of large photonics design which will be applicable for polariser, sensor, and solar applications.

     

Design of a New Peptide Substrate Probe of the Putative Biomarker Legumain with Potential Application in Prostate Cancer Diagnosis Ex Vivo

International Journal of Peptide Research and Therapeutics - The lysosomal endoprotease legumain (asparaginyl endoprotease) has been proposed as a putative biomarker in prostate tumours, in which...     

In-vivo dose measurements with MOSFET dosimeters during MV portal imaging

BackgroundThe purpose of this study was to investigate the feasibility of MOSFET dosimeter in measuring eye dose during 2D MV portal imaging for setup verification in radiotherapy.Materials and methodsThe in-vivo dose measurements were performed by placing the dosimeters over the eyes of 30 brain patients during the acquisition of portal images in linear accelerator by delivering 1 MU with the field sizes of 10 × 10 cm² and 15 × 15 cm².ResultsThe mean doses received by the left and right eyes of 10 out of 30 patients when both eyes were completely inside the anterior portal field were found to be 2.56 ± 0.2 cGy and 2.75 ± 0.2, respectively. Similarly, for next 10 patients out of the same 30 patients the mean doses to left and right eyes when both eyes were completely out of the anterior portal fields were found to be 0.13 ± 0.02 cGy and 0.17 ± 0.02 cGy, respectively. The mean doses to ipsilateral and contralateral eye for the last 10 patients when one eye was inside the anterior portal field were found to be 3.28 ± 0.2 cGy and 0.36 ± 0.1 cGy, respectively.ConclusionThe promising results obtained during 2D MV portal imaging using MOSFET have shown that this dosimeter is well suitable for assessing low doses during imaging thereby enabling to optimize the imaging procedure using the dosimetric data obtained. In addition, the documentation of the dose received by the patient during imaging procedure is possible with the help of an in-built software in conjunction with the MOSFET reader module.     

On the macro-micro-morphology of organs of host invasion in hemiparasite Helicanthes elasticus (Desv.) Danser

Loranthaceae family includes hemiparasitic members which are seen invading a wide range of commercial crops. Helicanthes elasticus (Desv.) Danser is very common on mango trees. Though parasitic in nature, this mistletoe is also medicinally important as fetoprotective, against vesicular calculi and kidney infections. This study is an attempt to document macro-microscopical features of parasitic root, fruit and host-mistletoe tissue interaction in the haustorium of H. elasticus growing on mango stems. Collection, preservation, sectioning, staining and photomicrography of the root, fruit and host-mistletoe union were done as per standard methodologies of anatomical studies. Though there is resemblance to the normal roots in morphology as well as anatomy, the microscopic finding of large number of branched stone cells in the roots is interesting. The morpho-anatomical features recorded would help in understanding the infection biology of this mistletoe. The eradication during the earlier stages of its establishment from seed or from the root creeping over the surface of the host can help in controlling this parasite infection on commercially important host plants.     

An efficient pipeline for ancient DNA mapping and recovery of endogenous ancient DNA from whole‐genome sequencing data

Ancient DNA research has developed rapidly over the past few decades due to improvements in PCR and next‐generation sequencing (NGS) technologies, but challenges still exist. One major challenge in relation to ancient DNA research is to recover genuine endogenous ancient DNA sequences from raw sequencing data. This is often difficult due to degradation of ancient DNA and high levels of contamination, especially homologous contamination that has extremely similar genetic background with that of the real ancient DNA. In this study, we collected whole‐genome sequencing (WGS) data from 6 ancient samples to compare different mapping algorithms. To further explore more effective methods to separate endogenous DNA from homologous contaminations, we attempted to recover reads based on ancient DNA specific characteristics of deamination, depurination, and DNA fragmentation with different parameters. We propose a quick and improved pipeline for separating endogenous ancient DNA while simultaneously decreasing homologous contaminations to very low proportions. Our goal in this research was to develop useful recommendations for ancient DNA mapping and for separation of endogenous DNA to facilitate future studies of ancient DNA.     

Mercuric chloride-induced Gastrin/Cholecystokinin 8 immunoreactivity in the central nervous system of the terrestrial slug Semperula maculata: an immunohistochemical study

We measured the immunoreactivity of the neuropeptide gastrin cholecystokinin 8 (gastrin/CCK 8) in neurons of the terrestrial slug Semperula maculata following acute treatment with mercuric chloride (HgCl₂). The distribution of gastrin/CCK 8 was analyzed in neurons of different regions, specifically from cerebral ganglia (procerebrum (pro-c), mesocerebrum (meso-c) and metacerebrum (meta-c). In the control group, neurons of pedal, pleural, parietal and visceral ganglia showed positive immunoreactivity using vertebrate antiserum against gastrin/CCK 8. Gastrin/CCK 8 immunoreactivity was also seen in the fibers and neuropil region of all ganglia. In the cerebral ganglion, 10, 12 and 8 % of the neurons from pro-c, meso-c and meta-c, respectively, were stained with the antibody. The immunostaining was increased in neurons (giant, large, medium and small) after HgCl₂ treatment. The treatment greatly increased the mucin content within the neurons. Exposure to HgCl₂ enhanced gastrin immunoreactivity in the neurons and this increased with time. Results are discussed in the context of neuropathology in cerebral ganglia associated with the feeding behavior of Semperula maculata.     

Rapid Identification of Sequences for Orphan Enzymes to Power Accurate Protein Annotation

The power of genome sequencing depends on the ability to understand what those genes and their proteins products actually do. The automated methods used to assign functions to putative proteins in newly sequenced organisms are limited by the size of our library of proteins with both known function and sequence. Unfortunately this library grows slowly, lagging well behind the rapid increase in novel protein sequences produced by modern genome sequencing methods. One potential source for rapidly expanding this functional library is the “back catalog” of enzymology – “orphan enzymes,” those enzymes that have been characterized and yet lack any associated sequence. There are hundreds of orphan enzymes in the Enzyme Commission (EC) database alone. In this study, we demonstrate how this orphan enzyme “back catalog” is a fertile source for rapidly advancing the state of protein annotation. Starting from three orphan enzyme samples, we applied mass-spectrometry based analysis and computational methods (including sequence similarity networks, sequence and structural alignments, and operon context analysis) to rapidly identify the specific sequence for each orphan while avoiding the most time- and labor-intensive aspects of typical sequence identifications. We then used these three new sequences to more accurately predict the catalytic function of 385 previously uncharacterized or misannotated proteins. We expect that this kind of rapid sequence identification could be efficiently applied on a larger scale to make enzymology’s “back catalog” another powerful tool to drive accurate genome annotation.