Changes in Aphid Host Plant Diet Influence the Small-RNA Expression Profiles of Its Obligate Nutritional Symbiont, Buchnera.

Plants are a difficult food resource to use, and herbivorous insects have evolved a variety of mechanisms that allow them to fully exploit this poor nutritional resource. One such mechanism is the maintenance of bacterial symbionts that aid in host plant feeding and development. The majority of these intracellular symbionts have highly eroded genomes that lack many key regulatory genes; consequently, it is unclear if these symbionts can respond to changes in the insect's diet to facilitate host plant use. There is emerging evidence that symbionts with highly eroded genomes express small RNAs (sRNAs), some of which potentially regulate gene expression. In this study, we sought to determine if the reduced genome of the nutritional symbiont (Buchnera) in the pea aphid responds to changes in the aphid's host plant diet. Using transcriptome sequencing (RNA-seq), Buchnera sRNA expression profiles were characterized within two Buchnera life stages when pea aphids fed on either alfalfa or fava bean. Overall, this study demonstrates that Buchnera sRNA expression changes not only with life stage but also with changes in aphid host plant diet. Of the 321 sRNAs characterized in this study, 47% were previously identified and 22% showed evidence of conservation in two or more Buchnera taxa. Functionally, 13 differentially expressed sRNAs were predicted to target genes related to pathways involved in essential amino acid biosynthesis. Overall, results from this study reveal that host plant diet influences the expression of conserved and lineage-specific sRNAs in Buchnera and that these sRNAs display distinct host plant-specific expression profiles among biological replicates.IMPORTANCE In general, the genomes of intracellular bacterial symbionts are reduced compared to those of free-living relatives and lack many key regulatory genes. Many of these reduced genomes belong to obligate mutualists of insects that feed on a diet that is deficient in essential nutrients, such as essential amino acids. It is unclear if these symbionts respond with their host to changes in insect diet, because of their reduced regulatory capacity. Emerging evidence suggests that these symbionts express small RNAs (sRNAs) that regulate gene expression at the posttranscriptional level. Therefore, in this study, we sought to determine if the reduced genome of the nutritional symbiont Buchnera in the pea aphid responds to changes in the aphid's host plant diet. This study demonstrates for the first time that Buchnera sRNAs, some conserved in two or more Buchnera lineages, are differentially expressed when aphids feed on different plant species and potentially target genes within essential amino acid biosynthesis pathways

True and False Foodplants of \u3ci\u3eCallosamia Promethea\u3c/i\u3e (Lepidoptera: Saturniidae) in Southern Michigan

A survey in 1980 of the associations of over 400 cocoons of Callosamia promethea Drury in vegetation along and adjacent to southern Michigan roadsides gave evidence for seven species of true larval foodplants (not including two others known in the area from other studies) and 17 species of false foodplants, the latter determined by the (1) rarity of their association with cocoons, (2) only one or two cocoons per plant, and (3) their proximity to a well known true foodplant. Three species, sassafras, black cherry, and buttonbush, are evidently the most important true foodplants in this area. Comparisons are made of the foodplants in terms of past literature, geography, and taxonomic relationships

Partly Occupied Wannier Functions

We introduce a scheme for constructing partly occupied, maximally localized Wannier functions (WFs) for both molecular and periodic systems. Compared to the traditional occupied WFs the partly occupied WFs posses improved symmetry and localization properties achieved through a bonding-antibonding closing procedure. We demonstrate the equivalence between bonding-antibonding closure and the minimization of the average spread of the WFs in the case of a benzene molecule and a linear chain of Pt atoms. The general applicability of the method is demonstrated through the calculation of WFs for a metallic system with an impurity: a Pt wire with a hydrogen molecular bridge.Comment: 5 pages, 4 figure

Atmospheric measurements over kwajalein using falling spheres

Atmosphere measurements using falling spheres tracked by rada

Experimental Comparisons of Derivative Free Optimization Algorithms

In this paper, the performances of the quasi-Newton BFGS algorithm, the NEWUOA derivative free optimizer, the Covariance Matrix Adaptation Evolution Strategy (CMA-ES), the Differential Evolution (DE) algorithm and Particle Swarm Optimizers (PSO) are compared experimentally on benchmark functions reflecting important challenges encountered in real-world optimization problems. Dependence of the performances in the conditioning of the problem and rotational invariance of the algorithms are in particular investigated.Comment: 8th International Symposium on Experimental Algorithms, Dortmund : Germany (2009

Sources of magnetic fields in recurrent interplanetary streams

The sources of magnetic fields in recurrent streams were examined. Most fields and plasmas at 1 AU were related to coronal holes, and the magnetic field lines were open in those holes. Some of the magnetic fields and plasmas were related to open field line regions on the sun which were not associated with known coronal holes, indicating that open field lines are more basic than coronal holes as sources of the solar wind. Magnetic field intensities in five equatorial coronal holes ranged from 2G to 18G. Average measured photospheric magnetic fields along the footprints of the corresponding unipolar fields on circular equatorial arcs at 2.5 solar radii had a similar range and average, but in two cases the intensities were approximately three times higher than the projected intensities. The coronal footprints of the sector boundaries on the source surface at 2.5 solar radii, meandered between -45 deg and +45 deg latitude, and their inclination ranged from near zero to near ninety degrees

Spin Susceptibility of the Topological Superconductor UPt3 from Polarized Neutron Diffraction

Experiment and theory indicate that UPt3 is a topological superconductor in an odd-parity state, based in part from temperature independence of the NMR Knight shift. However, quasiparticle spin-flip scattering near a surface, where the Knight shift is measured, might be responsible. We use polarized neutron scattering to measure the bulk susceptibility with H||c, finding consistency with the Knight shift but inconsistent with theory for this field orientation. We infer that neither spin susceptibility nor Knight shift are a reliable indication of odd-parity