Behavioral and electrophysiological evidence for volatile sex pheromones in Parcoblatta wood cockroaches

Species within the cockroach genus Parcoblatta are sexually dimorphic for wing length; females have reduced wings and are flightless, while males have long wings that are used in flight. We predicted that Parcoblatta females would release a volatile sex pheromone to attract the more mobile males. Nymphs of the broad wood cockroach, P. lata, and the Caudell's wood cockroach, P. caudelli, were collected in forested areas in North Carolina, USA, and reared in the laboratory for observations of sexual behavior and for pheromone analysis. After several days of sexual maturation, virgin females of both species exhibited distinct calling behaviors. In females of P. lata, calling commenced 6 days after adult emergence. Under a light–dark photoperiod regime, calling behavior in both species was restricted to the scotophase. Calling consisted of a repeated pattern of raising and lowering the abdomen with occasional exposure of the genital vestibulum. To test whether calling behavior is associated with the release of pheromone, volatiles from calling and noncalling females were collected on Super-Q and tested by electroantennogram (EAG) and behavioral assays. Volatile collections from calling females elicited higher male-specific EAG responses than collections from noncalling females of the same physiological stage. In an olfactometer choice test (Y-tube), males preferred volatiles from calling females over those from noncalling females. To determine the anatomical source of the pheromone, solvent extracts of various body parts were analyzed by EAG. The first through seventh tergites were the only body parts that elicited male-specific EAG responses in both species. In P. lata, the activity of the extract increased from 1- to 7-day-old females, but was lower in mated than in virgin females of the same age. The putative pheromone gland appears to consist of numerous class-3 secretory units, each composed of a secretory cell connected to a cuticular pore via a tubular duct. We conclude that female P. lata and P. caudelli produce sex-specific volatile pheromones that are emitted during calling behavior.     

Quantitative trait loci and metabolic pathways

The interpretation of quantitative trait locus (QTL) studies is limited by the lack of information on metabolic pathways leading to most economic traits. Inferences about the roles of the underlying genes with a pathway or the nature of their interaction with other loci are generally not possible. An exception is resistance to the corn earworm Helicoverpa zea (Boddie) in maize (Zea mays L.) because of maysin, a C-glycosyl flavone synthesized in silks via a branch of the well characterized flavonoid pathway. Our results using flavone synthesis as a model QTL system indicate: (i) the importance of regulatory loci as QTLs, (ii) the importance of interconnecting biochemical pathways on product levels, (iii) evidence for "channeling" of intermediates, allowing independent synthesis of related compounds, (iv) the utility of QTL analysis in clarifying the role of specific genes in a biochemical pathway, and (v) identification of a previously unknown locus on chromosome 9S affecting flavone level. A greater understanding of the genetic basis of maysin synthesis and associated corn earworm resistance should lead to improved breeding strategies. More broadly, the insights gained in relating a defined genetic and biochemical pathway affecting a quantitative trait should enhance interpretation of the biological basis of variation for other quantitative traits.     

HRMC: Hybrid Reverse Monte Carlo method with silicon and carbon potentials

Fortran 77 code is presented for a hybrid method of the Metropolis Monte Carlo (MMC) and Reverse Monte Carlo (RMC) for the simulation of amorphous silicon and carbon structures. In additional to the usual constraints of the pair correlation functions and average coordination, the code also incorporates an optional energy constraint. This energy constraint is in the form of either the Environment Dependent Interatomic Potential (applicable to silicon and carbon) and the original and modified Stillinger-Weber potentials (applicable to silicon). The code also allows porous systems to be modeled via a constraint on porosity and internal surface area using a novel restriction on the available simulation volume.

Program summary

Program title: HRMC version 1.0Catalogue identifier: AEAO_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAO_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 200 894No. of bytes in distributed program, including test data, etc.: 907 557Distribution format: tar.gzProgramming language: FORTRAN 77Computer: Any computer capable of running executables produced by the g77 Fortran compilerOperating system: Unix, WindowsRAM: Depends on the type of empirical potential use, number of atoms and which constraints are employedClassification: 7.7Nature of problem: Atomic modeling using empirical potentials and experimental dataSolution method: Monte CarloAdditional comments: The code is not standard FORTRAN 77 but includes some additional features and therefore generates errors when compiled using the Nag95 compiler. It does compile successfully with the GNU g77 compiler (http://www.gnu.org/software/fortran/fortran.html).Running time: Depends on the type of empirical potential use, number of atoms and which constraints are employed. The test included in the distribution took 37 minutes on a DEC Alpha PC.     

Are physical activity and symptoms correlates of functional limitations and disability in multiple sclerosis?

Objective: This study examined physical activity and symptoms as correlates of functional limitations and disability among individuals with multiple sclerosis (MS). The authors hypothesized that physical activity and symptoms would be interrelated and that physical activity would be indirectly associated with disability through a pathway that involved functional limitations, whereas symptoms would be directly associated with both functional limitations and disability. Methods: Individuals with MS (N=133) who were recruited through a community organization wore an accelerometer for a 7-day period and completed a paper-and-pencil survey containing the Godin Leisure-Time Exercise Questionnaire (G. Godin & R. J. Shephard, 1985), Symptom Inventory (C. E. Schwartz, T. Vollmer, & H. Lee, 1999), MS-Related Symptom Checklist (E. E. Gulick, 1989), and abbreviated Late-Life Function and Disability Inventory (E. McAuley, J. F. Konopack, R. W. Motl, K. Rosengren, & K. S. Morris, 2005). The data were analyzed using structural equation modeling in AMOS 6.0. Results: The standardized coefficients indicated that (a) physical activity and symptoms were negatively correlated (Φ=-.59); (b) those who were more physically active had better function (γ=.40); (c) those with fewer symptoms had better function (γ=-.46) and less disability (γ=-.29); and (d) those with better function had less disability (β=.63). Conclusion: Findings indicate that physical activity is associated with reduced disability through a pathway that is consistent with S. Z. Nagi's disablement model in individuals with MS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Maximum acceptable forces for repetitive ulnar deviation of the wrist

The purpose of this experiment was to quantify maximum acceptable forces for ulnar deviation motions of the wrist at various repetition rates. Subjects grasped a handle with a power grip and moved it through a 1.40 rad (80 degrees) ulnar deviation wrist motion (similar to a knife cutting task). A psychophysical methodology was used in which the subject adjusted the resistance on the handle and the experiment manipulated or controlled all other variables. Two series of experiments were conducted. Thirteen subjects completed the first series, which investigated repetition rates of 15 and 20 motions per minute. Eleven subjects completed the second series, which investigated 15, 20, and 25 motions per minute. Subjects performed for 7 hours per day, 5 days per week, for 4 weeks in the first series and 5 weeks in the second series. The subjects were instructed to work as if they were on an incentive basis, getting paid for the amount of work they performed. Symptoms were recorded by the subjects during the last 5 minutes of each hour. The results are presented and compared with maximum acceptable forces for wrist flexion and extension.     

Meteorological conditions and self-report of low back pain

STUDY DESIGN: Six months of daily low back pain ratings for 94 individuals were tested for the influence of prevailing weather conditions during the spring, summer, and fall seasons. Intergroup differences were tested for study participants who reported weather sensitivity and for those who did not. OBJECTIVES: To investigate the relation between pain ratings and prevailing weather conditions in a population with chronic or recurrent low back pain. SUMMARY OF BACKGROUND DATA: Weather conditions have been reported to influence pain perception in some disease states, including low back pain. Investigations of this relation in chronic or recurrent low back pain have involved varied methodologies, and conflicting results have been reported. METHODS: The effects of eight weather variables reported to influence musculoskeletal pain were tested on daily pain ratings. A post hoc weather sensitivity questionnaire was used to disperse 73 individuals into groups based on perceived weather sensitivity, and group differences were tested. RESULTS: Significant effects on pain scores were found, most notably for temperature and vapor pressure. The magnitude of the effects were small compared with autocorrelation of an individual's own pain scores. Significant differences were found between the group of individuals who were insensitive to weather conditions and that of individuals with perceived sensitivity to cold temperatures. No significant intergroup differences were found for damp, rainy conditions or changes in barometric pressure. CONCLUSIONS: Weather conditions may influence subjective reporting of low back pain significantly. Although the effects are small in magnitude, they should be considered in clinical treatment of the patient with chronic, nonspecific low back pain. Pain scores may demonstrate greater interaction with certain weather conditions in individuals perceiving sensitivity to those conditions.     

Genetic mechanisms underlying apimaysin and maysin synthesis and corn earworm antibiosis in maize (Zea mays L.)

C-glycosyl flavones in maize silks confer resistance (i.e., antibiosis) to corn earworm (Helicoverpa zea [Boddie]) larvae and are distinguished by their B-ring substitutions, with maysin and apimaysin being the di- and monohydroxy B-ring forms, respectively. Herein, we examine the genetic mechanisms underlying the synthesis of maysin and apimaysin and the corresponding effects on corn earworm larval growth. Using an F2 population, we found a quantitative trait locus (QTL), rem1, which accounted for 55.3% of the phenotypic variance for maysin, and a QTL, pr1, which explained 64.7% of the phenotypic variance for apimaysin. The maysin QTL did not affect apimaysin synthesis, and the apimaysin QTL did not affect maysin synthesis, suggesting that the synthesis of these closely related compounds occurs independently. The two QTLs, rem1 and pr1, were involved in a significant epistatic interaction for total flavones, suggesting that a ceiling exists governing the total possible amount of C-glycosyl flavone. The maysin and apimaysin QTLs were significant QTLs for corn earworm antibiosis, accounting for 14. 1% (rem1) and 14.7% (pr1) of the phenotypic variation. An additional QTL, represented by umc85 on the short arm of chromosome 6, affected antibiosis (R2 = 15.2%), but did not affect the synthesis of the C-glycosyl flavones.     

The structure and function of antiamoebin I, a proline-rich membrane-active polypeptide

BACKGROUND: Antiamoebin is a member of the peptaibol family of polypeptides and has a unique antibiotic activity: it acts as an antiamoebic agent, but does not effectively haemolyze erythrocytes even though it does exhibit membrane-modifying activity. RESULTS: The structure of antiamoebin I has been determined by X-ray crystallography at 1.4 A resolution. The molecule forms a helical structure, which, as a result of the presence of a number of proline and hydroxyproline residues, has a deep bend in the middle. Circular dichroism spectroscopy, single-channel conductance studies and fluorescence diffusion studies suggest a mode of ion transport that is entirely different from that of the other two members of the peptaibol family (alamethicin and zervamicin) whose structures and functions have been examined in detail. CONCLUSIONS: The structure of the polypeptide has been determined and a functional model for its mode of action in membranes is presented. Although under some conditions antiamoebin may form ion channels, unlike the closely related alamethicin and zervamicin polypeptides, its major membrane-modifying activity appears to be as an ion carrier.