Characteristics of the nuclear (18S, 5.8S, 28S and 5S) and mitochondrial (12S and 16S) rRNA genes of Apis mellifera (Insecta: Hymenoptera): structure, organization, and retrotransposable elements

As an accompanying manuscript to the release of the honey bee genome, we report the entire sequence of the nuclear (18S, 5.8S, 28S and 5S) and mitochondrial (12S and 16S) ribosomal RNA (rRNA)-encoding gene sequences (rDNA) and related internally and externally transcribed spacer regions of Apis mellifera (Insecta: Hymenoptera: Apocrita). Additionally, we predict secondary structures for the mature rRNA molecules based on comparative sequence analyses with other arthropod taxa and reference to recently published crystal structures of the ribosome. In general, the structures of honey bee rRNAs are in agreement with previously predicted rRNA models from other arthropods in core regions of the rRNA, with little additional expansion in non-conserved regions. Our multiple sequence alignments are made available on several public databases and provide a preliminary establishment of a global structural model of all rRNAs from the insects. Additionally, we provide conserved stretches of sequences flanking the rDNA cistrons that comprise the externally transcribed spacer regions (ETS) and part of the intergenic spacer region (IGS), including several repetitive motifs. Finally, we report the occurrence of retrotransposition in the nuclear large subunit rDNA, as R2 elements are present in the usual insertion points found in other arthropods. Interestingly, functional R1 elements usually present in the genomes of insects were not detected in the honey bee rRNA genes. The reverse transcriptase products of the R2 elements are deduced from their putative open reading frames and structurally aligned with those from another hymenopteran insect, the jewel wasp Nasonia (Pteromalidae). Stretches of conserved amino acids shared between Apis and Nasonia are illustrated and serve as potential sites for primer design, as target amplicons within these R2 elements may serve as novel phylogenetic markers for Hymenoptera. Given the impending completion of the sequencing of the Nasonia genome, we expect our report eventually to shed light on the evolution of the hymenopteran genome within higher insects, particularly regarding the relative maintenance of conserved rDNA genes, related variable spacer regions and retrotransposable elements

Prospects for e+e- physics at Frascati between the phi and the psi

We present a detailed study, done in the framework of the INFN 2006 Roadmap, of the prospects for e+e- physics at the Frascati National Laboratories. The physics case for an e+e- collider running at high luminosity at the phi resonance energy and also reaching a maximum center of mass energy of 2.5 GeV is discussed, together with the specific aspects of a very high luminosity tau-charm factory. Subjects connected to Kaon decay physics are not discussed here, being part of another INFN Roadmap working group. The significance of the project and the impact on INFN are also discussed. All the documentation related to the activities of the working group can be found in http://www.roma1.infn.it/people/bini/roadmap.html.Comment: INFN Roadmap Report: 86 pages, 25 figures, 9 table

The deformation and fracture behaviour of glass-filled ABS

The tensile and fracture characteristics of pigmented ABS containing 30 wt % rubber reinforced with 30 wt % glass fibre have been examined over a range of strain-rates extending from approximately 10−4 to 10−1 sec−1 within the temperature range 293 to 353 K. The glass fibre-reinforced composite had significantly increased fracture strength compared with the base polymer but possessed decreased ductility. The marked yield point which is characteristic of the ABS base polymer was absent from the reinforced material. Two different regions were found to exist on the fracture surfaces of composite specimens. One region possessed the characteristics of a weak interfacial bond while the other showed evidence of strong, interfacial bonding. In both regions extensive fibre pull-out was observed. The variation in fracture strength and morphology with strain-rate and temperature of testing is explained in terms of the properties of an interfacial region adjacent to the fibres which possesses viscoelastic properties different from those of the bulk polymer. The effect of adiabatic heating at the crack tip is also taken into account in the high temperature—high strain rate regime

Registration of a hard red winter wheat genetic stock homozygous for ph1b for facilitating alien introgression for crop improvement

Citation: Friebe, B., Qi, L., Liu, C., Liu, W., & Gill, B. S. (2012). Registration of a hard red winter wheat genetic stock homozygous for ph1b for facilitating alien introgression for crop improvement. Retrieved from http://krex.ksu.eduWild relatives of bread wheat, Triticum aestivum L. are an important source for disease and pest resistance that can be exploited in wheat improvement. However, in wheat/alien species hybrids the pairing homoeologous gene, Ph1, suppresses the pairing and recombination of wheat and alien chromosomes and, thus, no alien genetic transfer can occur. However, in plants nullisomic for the Ph1 gene, and in the ph1b mutant stock, having a large deletion at the Ph1 locus, homoeologous wheat and alien chromosomes can pair and recombine. The original ph1b mutant stock is in Chinese Spring background, which has poor agronomic characteristics and several backcrosses with adapted wheat cultivars are necessary before the agronomic performance of the recombinants can be evaluated. The present report describes the transfer and characterization of the ph1b mutant allele into adapted Kansas winter wheat, which will accelerate the evaluation and utilization of wheat alien recombinants in cultivar improvement