Resistance to Bacillus thuringiensis in sugarcane borer, Diatraea saccharalis (F.)

The sugarcane borer, Diatraea saccharalis (F.), is a dominant corn stack boring pest and a major target of Bacillus thuringiensis (Bt)-corn in many areas of the mid-southern region of the United States. A Cry1Ab-resistant strain of D. saccharalis, capable of survival on commercial Bt corn plants, was established using an F2 screening procedure. Larval survival of Cry1Ab-resistant, -susceptible, and -heterozygous genotypes was evaluated on five non-Bt and seven Bt field corn hybrids at two plant stages. During the vegetative stages, all seven Bt corn hybrids were highly efficacious against the three genotypes, while 8-18% of the heterozygous genotype survived on reproductive stage plants for four Bt corn hybrids. Susceptibilities of Cry1Ab-susceptible and -resistant strains were evaluated for four Bt proteins: Cry1Aa, Cry1Ac, Cry1A.105, and Cry2Ab2. LC50 values of the Cry1Ab-resistant strain were \u3e80-, 45-, 4.1-, and -0.5-fold greater than that of the susceptible strain to the four proteins, respectively. Relative fitness on non-toxic diet, diet treated with low concentrations of Cry1Ab toxin, and on conventional corn plants was compared for five genotypes of D. saccharalis. Larvae of Cry1Ab-susceptible and Cry1Ab-resistant strains on both non-toxic diet and non-Bt corn plants developed normally. There were no significant differences between the two strains in all measured biological parameters, suggesting a lack-of-fitness cost of the Cry1Ab resistance in D. saccharalis. Larval development, growth, and survival of the Cry1Ab-susceptible strain were significantly affected on diet treated with low concentrations of Cry1Ab toxin, while the effect to the resistant strains was not/or less significant. Using various genetic crosses, inheritance of Cry1Ab resistance in D. saccharalis was assessed on Bt corn leaf tissue, intact Bt corn plants, and diet containing Cry1Ab toxin. Cry1Ab resistance in D. saccharalis was inherited as a single autosomal gene. The resistance was incompletely or nearly completely recessive on Bt corn leaf tissue and intact Bt corn plants, while the dominance increased as Cry1Ab concentrations decreased when it was tested on Cry1Ab-treated diet. Results generated from this study will provide valuable information in understanding Bt resistance mechanisms and developing effective strategies for managing resistance of D. saccharalis to Bt corn

All-condition pulse detection using a magnetic sensor

A plethora of wearable devices have been developed or commercialized for continuous non-invasive monitoring of physiological signals that are crucial for preventive care and management of chronic conditions. However, most of these devices are either sensitive to skin conditions or its interface with the skin due to the requirement that the external stimuli such as light or electrical excitation must penetrate the skin to detect the pulse. This often results in large motion artefacts and unsuitability for certain skin conditions. Here, we demonstrate a simple fingertip-type device which can detect clear pulse signals under all conditions, including fingers covered by opaque substances such as a plaster or nail polish, or fingers immersed in liquid. The device has a very simple structure, consisting of only a pair of magnets and a magnetic sensor. We show through both experiments and simulations that the detected pulsation signals correspond directly to the magnet vibrations caused by blood circulation, and therefore, in addition to heartrate detection, the proposed device can also be potentially used for blood pressure measurement

A feedback-driven bubble G24.136+00.436: a possible site of triggered star formation

We present a multi-wavelength study of the IR bubble G24.136+00.436. The J=1-0 observations of $^{12}$CO, $^{13}$CO and C$^{18}$O were carried out with the Purple Mountain Observatory 13.7 m telescope. Molecular gas with a velocity of 94.8 km s$^{-1}$ is found prominently in the southeast of the bubble, shaping as a shell with a total mass of $\sim2\times10^{4}$ $M_{\odot}$. It is likely assembled during the expansion of the bubble. The expanding shell consists of six dense cores. Their dense (a few of $10^{3}$ cm$^{-3}$) and massive (a few of $10^{3}$ $M_{\odot}$) characteristics coupled with the broad linewidths ($>$ 2.5 km s$^{-1}$) suggest they are promising sites of forming high-mass stars or clusters. This could be further consolidated by the detection of compact HII regions in Cores A and E. We tentatively identified and classified 63 candidate YSOs based on the \emph{Spitzer} and UKIDSS data. They are found to be dominantly distributed in regions with strong emission of molecular gas, indicative of active star formation especially in the shell. The HII region inside the bubble is mainly ionized by a $\sim$O8V star(s), of the dynamical age $\sim$1.6 Myr. The enhanced number of candidate YSOs and secondary star formation in the shell as well as time scales involved, indicate a possible scenario of triggering star formation, signified by the "collect and collapse" process.Comment: 13 pages, 10 figures, 4 tables, accepted by Ap

Stronger intra-specific competition aggravates negative effects of drought on the growth of Cunninghamia lanceolata

Plant-plant competition is a dynamic and complicated process that is strongly influenced by abiotic conditions. Drought is a critical threat to forests, particularly to young plantation forests. Temporal changes in competition combined with the effects of drought may dramatically influence the physiological traits of plants. Cunninghamia lanceolata plants exposed to intra-specific competition and no-competition conditions were investigated under two soil water levels (well-watered and drought). Changes in plant-plant competition relationships and nitrogen uptake rates were measured at different harvest times. The effects of drought and plant competition on physiological traits, for example, leaf nitrogen allocation, δ13C, and levels of abscisic acid (ABA), indole acetic acid (IAA) and jasmonic acid (JA), were also explored. Our results indicated that C. lanceolata shifted from intense neighbor competition to facilitation under well-watered conditions, whereas under drought neighbor competition became much stronger at the second harvest compared to the first harvest. Strong competition significantly decreased N uptake under drought. Leaf NH4+, NO3- and N allocation to water-soluble proteins increased under drought at the first harvest, but significantly declined under prolonged drought. Leaf, stem and root starch concentrations were enhanced by drought. However, during prolonged drought, the root starch concentrations, leaf δ13C, leaf ABA and starch content of C. lanceolata were much lower under strong neighbor competition than in no-competition conditions, which demonstrated that the combined effects of drought and strong competition were more harmful to plant growth and survival compared to single effects. Our study demonstrated that drought combined with competition strongly affected the N uptake, N allocation and physiological traits of plants. Intense competition imposed by neighbors is a great threat to the growth and survival of young C. lanceolata plantations under prolonged drought.Peer reviewe