Introgressing a new source of host-plant resistance to European corn borer into two elite maize inbred lines

Eleven accessions of Peruvian maize were evaluated for mechanisms of resistance to leaf feeding by European corn borer, Ostrinia nubilalis (Hubner). Antibiosis was identified as one mechanism of resistance that operates at a level equivalent to CI31A which is a maize inbred line containing high levels of 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), thus having strong antixenotic and antibiotic properties towards leaf feeding by European corn borer. Antixenosis may be another mechanism of resistance operating in the Peruvian maize but at a level lower than CI31A. The 11 Peruvian maize accessions were used as donor parents in a backcross plant breeding program designed to introgress the European corn borer resistance trait into two elite U.S. Corn Belt adapted inbred lines. Resistance to European corn borer leaf feeding and sheath and collar feeding was recovered in the F1 indicating dominant genetic control. There was no correlation between resistance to European corn borer leaf feeding and sheath and collar feeding, indicating that genetic control of resistance to leaf feeding is independent of that for sheath and collar feeding. Some BC2 S1 x Private Tester hybrids of maize had a mean yield not significantly different than the highest yielding commercial check for each experiment. BC3 experimental lines have been developed which have yield potential plus the unique source of resistance to leaf, sheath, and collar feeding by European corn borer. Fifteen experimental lines of maize derived from the backcross breeding program were evaluated for resistance to the European corn borer, corn earworm (Helicoverpa zea (Boddie)), fall armyworm, (Spodoptera frugiperda (J. E. Smith)), and sugarcane borer, (Diatraea saccharalis (Fabricius)). Experimental lines 100-R-3 and 116-B-10 had varying levels of resistance to all of the insects tested. Experimental line 107-8-7 was identified as being resistant to corn earworm while maintaining low levels of maysin. Experimental line 81-9-B had very high levels of resistance to corn earworm

Analysis of permanent magnets as elasmobranch bycatch reduction devices in hook-and-line and longline trials

Previous studies indicate that elasmobranch fishes (sharks, skates and rays) detect the Earth’s geomagnetic field by indirect magnetoreception through electromagnetic induction, using their ampullae of Lorenzini. Applying this concept, we evaluated the capture of elasmobranchs in the presence of permanent magnets in hook-and-line and inshore longline fishing experiments. Hooks with neodymium-iron-boron magnets significantly reduced the capture of elasmobranchs overall in comparison with control and procedural control hooks in the hook-and-line experiment. Catches of Atlantic sharpnose shark (Rhizoprionodon terraenovae) and smooth dogfish (Mustelus canis) were signif icantly reduced with magnetic hook-and-line treatments, whereas catches of spiny dogfish (Squalus acanthias) and clearnose skate (Raja eglanteria) were not. Longline hooks with barium-ferrite magnets significantly reduced total elasmobranch capture when compared with control hooks. In the longline study, capture of blacktip sharks (Carcharhinus limbatus) and southern stingrays (Dasyatis americana) was reduced on magnetic hooks, whereas capture of sandbar shark (Carcharhinus plumbeus) was not affected. Teleosts, such as red drum (Sciaenops ocellatus), Atlantic croaker (Micropogonias undulatus), oyster toadfish (Opsanus tau), black sea bass (Centropristis striata), and the bluefish (Pomatomas saltatrix), showed no hook preference in either hook-and-line or longline studies. These results indicate that permanent magnets, although eliciting species-specific capture trends, warrant further investigation in commercial longline and recreational fisheries, where bycatch mortality is a leading contributor to declines in elasmobranch populations

Solitonic supersymmetry restoration

Q-balls are a possible feature of any model with a conserved, global U(1) symmetry and no massless, charged scalars. It is shown that for a broad class of models of metastable supersymmetry breaking they are extremely influential on the vacuum lifetime and make seemingly viable vacua catastrophically short lived. A net charge asymmetry is not required as there is often a significant range of parameter space where statistical fluctuations alone are sufficient. This effect is examined for two supersymmetry breaking scenarios. It is found that models of minimal gauge mediation (which necessarily have a messenger number U(1)) undergo a rapid, supersymmetry restoring phase transition unless the messenger mass is greater than 10^8 GeV. Similarly the ISS model, in the context of direct mediation, quickly decays unless the perturbative superpotential coupling is greater than the Standard Model gauge couplings.Comment: 17 pages, 3 figures, minor comments added, accepted for publication in JHE

Metastable supersymmetry breaking without scales

We construct new examples of models of metastable D=4 N=1 supersymmetry breaking in which all scales are generated dynamically. Our models rely on Seiberg duality and on the ISS mechanism of supersymmetry breaking in massive SQCD. Some of the electric quark superfields arise as composites of a strongly coupled gauge sector. This allows us to start with a simple cubic superpotential and an asymptotically free gauge group in the ultraviolet, and end up with an infrared effective theory which breaks supersymmetry dynamically in a metastable state.Comment: 6 pages, 1 figure; v2: journal versio

Can Inflation Induce Supersymmetry Breaking in a Metastable Vacuum?

We argue that fields responsible for inflation and supersymmetry breaking are connected by gravitational couplings. In view of the recent progress in studying supersymmetry breaking in a metastable vacuum, we have shown that in models of supersymmetric hybrid inflation, where R-symmetry plays an important role, the scale of supersymmetry breaking is generated dynamically at the end of inflation and turns out to be consistent with gravity mediation.Comment: 5 pages, Latex, Footnote and references added, Journal versio

Mobilizing the genome of Lepidoptera through novel sequence gains and end creation by non-autonomous Lep1 Helitrons

Transposable elements (TEs) can affect the structure of genomes through their acquisition and transposition of novel DNA sequences. The 134-bp repetitive elements, Lep1, are conserved non-autonomous Helitrons in lepidopteran genomes that have characteristic 5\u27-CT and 3\u27-CTAY nucleotide termini, a 3\u27-terminal hairpin structure, a 5\u27- and 3\u27-subterminal inverted repeat (SIR), and integrations that occur between AT or TT nucleotides. Lep1 Helitrons have acquired and propagated sequences downstream of their 3\u27-CTAY termini that are 57-344-bp in length and have termini composed of a 3\u27-CTRR preceded by a 3\u27-hairpin structure and a region complementary to the 5\u27-SIR (3\u27-SIRb). Features of both the Lep1 Helitron and multiple acquired sequences indicate that secondary structures at the 3\u27-terminus may have a role in rolling circle replication or genome integration mechanisms, and are a prerequisite for novel end creation by Helitron-like TEs. The preferential integration of Lep1 Helitrons in proximity to gene-coding regions results in the creation of genetic novelty that is shown to impact gene structure and function through the introduction of novel exon sequence (exon shuffling). These findings are important in understanding the structural requirements of genomic DNA sequences that are acquired and transposed by Helitron-like TEs

Dynamical Vacuum Selection in String Theory

We study a system of D-branes localized near an intersection of Neveu-Schwarz fivebranes, that is known to exhibit a landscape of supersymmetric and (metastable) supersymmetry breaking vacua. We show that early universe cosmology drives it to a particular long-lived supersymmetry breaking ground state.Comment: 42 pages, 7 figures; references and acknowledgement adde