Foraging mode and evolution of strike-induced chemosensory searching in lizards

Strike-induced chemosensory searching (SICS) in lizards and snakes is a means of relocating prey by scent-trailing. The two main components of SICS are an elevated tongue-flick rate for vomerolfactory sampling after biting prey (PETF) and searching movements. In combination, these behaviors permit scent-trailing. Prey chemical discrimination, which is a prerequisite for SICS, is present in active foragers, but not in ambush foragers. Using comparative data, I show that searching movements and SICS have undergone correlated evolution with foraging mode and with prey chemical discrimination in lizards. This suggests that active foraging selects for prey chemical discrimination, which is then employed to search for escaped prey using the typical movements and tongue-flicking behaviors of active foragers. SICS in lizards is simply heightened active foraging after biting prey. In nonvenomous snakes, SICS is similar to that in lizards but is not restricted to active foragers. Only highly venomous snakes voluntarily release dangerous prey upon envenomation, pause to let the venom incapacitate the prey, and then relocate the prey by scent-trailing. PETF was observed in two ambush foragers and is not evolutionarily correlated with foraging mode or searching movements. Because it occurs in species lacking prey chemical discrimination, such PETF may be a response to gustatory cues or to internal chemicals not encountered on surfaces or trails of uninjured prey.     

A High Omega-3 Fatty Acid Diet has Different Effects on Early and Late Stage Myeloid Progenitors

The effects of the polyunsaturated omega-3 (n-3) and omega-6 (n-6) fatty acids (FA) on hematopoiesis are complex in that both FA forms are processed into leukotrienes, eicosanoids, and prostaglandins, which can have independent effects. These FA have antagonistic effects in that n-6 FA prostaglandins tend to be pro-proliferative and pro-inflammatory, while the effects of n-3 FA prostaglandins are the opposite. We have previously shown that diets high in n-3 FA reduce the size of the middle to later stage myeloid progenitor compartment in FVB X sv129 F₁hybrid mice. To assay the effects of high n-3 FA diets on earlier stages of myelopoiesis, we fed C57BL/6J mice diets high in n-3 FA or levels of n-3/n-6 FA similar to western diets and assayed the effects on myelopoiesis with flow cytometry and colony forming cell assays. Results indicate an expansion of the common myeloid progenitor cell compartment in high n-3 FA diets, which does not persist into later stages where the number of progenitor cells is actually lower in high n-3 FA fed animals. Investigations in vitro with the hematopoietic stem cell line EML-clone 1 indicate that cells cultured with eicosapentaenoic acid (n-3 FA) or arachidonic acid (n-6 FA) have no differences in cell viability but that arachidonic acid more rapidly produces progenitors with low levels of the macrophage developmental marker, F4/80.     

Production of Protocatechuic Acid in Bacillus Thuringiensis ATCC33679

Protocatechuic acid, or 3,4-dihydroxybenzoic acid, is produced by both soil and marine bacteria in the free form and as the iron binding component of the siderophore petrobactin. The soil bacterium, Bacillus thuringiensis kurstaki ATCC 33679, contains the asb operon, but does not produce petrobactin. Iron restriction resulted in diminished B. thuringiensis kurstaki ATCC 33679 growth and the production of catechol(s). The gene product responsible for protocatechuic acid (asbF) and its receptor (fatB) were expressed during stationary phase growth. Gene expression varied with growth temperature, with optimum levels occurring well below the Bacillus anthracis virulence temperature of 37 °C. Regulation of protocatechuic acid suggests a possible role for this compound during soil growth cycles.     

Computational experiments with a feature based stereo algorithm

Computational models of the human stereo system can provide insight into general information processing constraints that apply to any stereo system, either artificial or biological. In 1977 Marr and Poggio proposed one such computational model, which was characterized as matching certain feature points in difference-of-Gaussian filtered images and using the information obtained by matching coarser resolution representations to restrict the search space for matching finer resolution representations. An implementation of the algorithm and its testing on a range of images was reported in 1980. Since then a number of psychophysical experiments have suggested possible refinements to the model and modifications to the algorithm. As well, recent computational experiments applying the algorithm to a variety of natural images, especially aerial photographs, have led to a number of modifications. In this paper, we present a version of the Marr-Poggio-Grimson algorithm that embodies these modifications, and we illustrate its performance on a series of natural images.     

Identification of (−)-β-Caryophyllene as a Gender-Specific Terpene Produced by the Multicolored Asian Lady Beetle

This work reports the development and use of techniques for characterizing volatile chemicals emitted by the multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), in an effort to identify the semiochemicals involved in establishment and persistence of overwintering beetle aggregations. Volatiles emitted from live beetles were detected by using whole-air sampling and solid-phase microextraction (SPME). Adsorbed volatiles were thermally desorbed and identified with gas chromatography-mass spectrometry (GC/MS). By comparing the chromatograms of volatiles emitted from live male and female beetles, a sesquiterpene, (−)-β-caryophyllene, was found only in the females. The identity of (−)-β-caryophyllene was confirmed by using NIST Library searches, comparing retention times with those of known standards, and by using higher-resolution GC/MS above bench top capability. Although SPME trapping detected a wider array of compounds compared to whole-air sampling, the latter method is better suited for automation. Unattended automated sampling is required for the continuous measurement of targeted compounds under dynamically changing incubation conditions. These conditions, mimicking natural overwintering conditions, are essential to our long-term goal of using this technology to detect and identify the aggregation pheromone of H. axyridis.The United States Government has the right to retain a nonexclusive, royalty-free license in and to any copyright of this article. This article reports the results of research only. Mention of a commercial or proprietary product does not constitute an endorsement of the product by the USDA.     

Effect of tannins on the in vitro growth of Escherichia coli O157:H7 and in vivo growth of generic Escherichia coli excreted from steers

The effect of commercially available chestnut and mimosa tannins in vitro (experiment 1) or in vivo (experiment 2) on the growth or recovery of Escherichia coli O157:H7 or generic fecal E. coli was evaluated. In experiment 1, the mean growth rate of E. coli O157:H7, determined via the measurement of optical density at 600 nm during anaerobic culture in tryptic soy broth at 37 degrees C, was reduced (P < 0.05) with as little as 400 microg of either tannin extract per ml of culture fluid. The addition of 200, 400, 600, 800, and 1,200 microg of tannins per ml significantly (P < 0.01) reduced the specific bacterial growth rate when compared with the nontannin control. The specific growth rate decreased with increasing dose levels up to 800 microg of tannins per ml. Bacterial growth inhibition effects in chestnut tannins were less pronounced than in mimosa tannins. Chestnut tannin extract addition ranged from 0 to 1,200 microg/ml, and a linear effect (P < 0.05) was observed in cultures incubated for 6 h against the recovery of viable cells, determined via the plating of each strain onto MacConkey agar, of E. coli O157:H7 strains 933 and 86-24, but not against strain 6058. Similar tests with mimosa tannin extract showed a linear effect (P < 0.05) against the recovery of E. coli O157:H7 strain 933 only. The bactericidal effect observed in cultures incubated for 24 h with the tannin preparations was similar, although it was less than that observed from cultures incubated for 6 h. When chestnut tannins (15 g of tannins per day) were infused intraruminally to steers fed a Bermuda grass hay diet in experiment 2, fecal E. coli shedding was lower on days 3 (P < 0.03), 12 (P = 0.08), and 15 (P < 0.001) when compared with animals that were fed a similar diet without tannin supplementation. It was concluded that dietary levels and sources of tannins potentially reduce the shedding of E. coli from the gastrointestinal tract.     

PSE-like turkey breast enhancement through adjunct incorporation in a chunked and formed deli roll

A randomized complete block design with five treatments (100% pale, soft, and exudative-like (PSE-like), 100% PSE-like+1.5% collagen, 100% PSE-like+0.30% κ-/ι-carrageenan, 100% PSE-like+1.5% soy protein concentrate, and 100% Normal) and six replications was utilized to test the effects of meat raw material, turkey collagen (TC), soy protein concentrate (SPC), and carrageenan (CG) on protein functionality in the formulation of chunked and formed turkey breast. Addition of 1.5% SPC and 1.5% TC both decreased (P<0.05) cooking loss and increased (P<0.005) the protein bind of treatments formulated with 100% PSE-like raw material. Purge loss decreased (P<0.05) in PSE-like raw material when 1.5% TC, 1.5% SPC, or 0.30% CG were utilized, and no differences (P>0.05) existed in consumer acceptability among treatments. This research demonstrates the potential to increase the water holding capacity and improve the texture of deli rolls from PSE-like raw material through the incorporation of collagen, soy protein, or carrageenan.     

Chemical and elemental depth profiling of very thin organic layers by constant kinetic energy XPS: a new synchrotron XPS analysis strategy

We present a new synchrotron X-ray photoelectron spectroscopy strategy for surface chemical analysis of materials. Our approach is based on the acquisition of photoelectron spectra at constant kinetic energies with the help of a tunable synchrotron X-radiation source. This ensures both constant and tunable information depth for all elements in a very thin organic layer. Many of the problems known to XPS depth profiling using laboratory equipment are thereby avoided. Using our methodology, the 95% information depth, z(95%), can be tuned down to about 0.7 nm in organic materials. The upper limit in our study at the HE-SGM monochromator dipole magnet beamline at the synchrotron radiation source BESSY II is about 4.3 nm. Elemental quantification is achieved through relative sensitivity factors (RSF) specific to the measurement conditions, determined either with the help of calculated photoionization cross sections and inelastic mean free paths or experimentally. The potential of the technique is demonstrated for the in-depth analysis of plasma deposited nitrogen-rich organic thin films used in biomedical applications.     

Mesoscopic simulations of the phase behavior of aqueous EO19PO29EO19 solutions confined and sheared by hydrophobic and hydrophilic surfaces

The MesoDyn method is used to investigate associative structures in aqueous solution of a nonionic triblock copolymer consisting of poly(propylene oxide) capped on both ends with poly(ethylene oxide) chains. The effect of adsorbing (hydrophobic) and nonadsorbing (hydrophilic) solid surfaces in contact with aqueous solutions of the polymer is elucidated. The macromolecules form self-assembled structures in solution. Confinement under shear forces is investigated in terms of interfacial behavior and association. The formation of micelles under confinement between hydrophilic surfaces occurs faster than in bulk aqueous solution while layered structures assemble when the polymers are confined between hydrophobic surfaces. Micelles are deformed under shear rates of 1 μs(-1) and eventually break to form persistent, adsorbed layered structures. As a result, surface damage under frictional forces is prevented. Overall, this study indicates that aqueous triblock copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) (Pluronics, EO(m)PO(n)EO(m)) act as a boundary lubricant for hydrophobic surfaces but not for hydrophilic ones.