Kinase Signaling in the Spindle Checkpoint

The spindle checkpoint is a cell cycle surveillance system that ensures the fidelity of chromosome segregation. In mitosis, it elicits the “wait anaphase” signal to inhibit the anaphase-promoting complex or cyclosome until all chromosomes achieve bipolar microtubule attachment and align at the metaphase plate. Because a single kinetochore unattached to microtubules activates the checkpoint, the wait anaphase signal is thought to be generated by this kinetochore and is then amplified and distributed throughout the cell to inhibit the anaphase-promoting complex/cyclosome. Several spindle checkpoint kinases participate in the generation and amplification of this signal. Recent studies have begun to reveal the activation mechanisms of these checkpoint kinases. Increasing evidence also indicates that the checkpoint kinases not only help to generate the wait anaphase signal but also actively correct kinetochore-microtubule attachment defects.     

The effects of maturation on self-induced dynamic body sway frequencies of girls performing acrobatics or classical dance

We investigated the effects of maturation on the dynamic body sways of healthy girls. Prepubertal and postpubertal girls practising professional physical activities requiring a good ability to maintain equilibrium (acrobats and dancers) were asked to stand on a free seesaw platform and the results compared to those for untrained age-matched girls. This platform (stabilometer) allows self-induced body sways. Stabilograms were obtained by a double integration of the angular acceleration from the recordings of the platform sways made with an accelerometer. Fast Fourier transform processing of stabilograms allowed spectral frequency analysis. The total spectrum energy and the energies of three frequency bands (0–0.5 Hz, 0.5–2 Hz, 2–20 Hz) were determined. ANOVA showed that, for all groups of different equilibrium activity and independent of visual input, prepubertal girls had higher energy values than postpubertal girls in the 0- to 0.5-Hz band whereas the opposite was true for 0.5- to 2-Hz band. Ballet dancers were more dependent than acrobats on visual inputs for the regulation of their postural control but were less dependent than untrained girls at both ages. Maturation seemed to shift body sways towards higher frequencies and the utilization of the cues of postural control was different according to the type of equilibrium activity practised by the subjects. Accepted: 7 February 1997     

Trichome-borne and artificially applied acylsugars of wild tomato deter feeding and oviposition of the leafminer Liriomyza trifolii

Oviposition and adult feeding of the leafminer Liriomyza trifollii (Burgess) (Diptera, Agromyzidae) on Lycopersicon pennellii (Corr.) D'Arcy and its F₁ hybrid with Lycopersicon esculentum (Mill.) was significantly less than that on the cultivated tomato, L. esculentum. The resistance of L. pennellii and the F₁ was reduced following rinsing of foliage with ethanol. Resistant attributes of L. pennellii were transferred to L. esculentum through appression of L. pennellii foliage to L. esculentum leaflets. Application of purified 2,3,4-tri-O-acylglucoses (the principal component of type IV glandular trichome exudate of L. pennellii) to L. esculentum significantly decreased feeding and oviposition on L. esculentum leaflets by 61–99%. Therefore the principal mechanism of resistance to this leafminer by L. pennellii is the secretion of these acylglucoses. Dose response analysis of acylglucoses applied to L. esculentum shows that dosages as low as 10% those found on L. pennellii provide large reductions (91%) in leaf punctures and mines.     

Dry Heat Inactivation of Bacillus subtilis var. niger Spores as a Function of Relative Humidity

Dry heat sterilization of Bacillus subtilis var. niger spores at 105 C is enhanced in the relative humidity range 0.03 to 0.2%. D-values of 115 and 125 C are predicted by a kinetic model with parameters set from 105 C data. These predictions are compared to observations.     

Testing for Validity and Reliability in Cross-Cultural Research

A set of procedures is offered for assessing interraler reliability and certain aspects of validity of codes in cross-cultural studies. The method assumes that at least two independent raters have coded more than one trait. Each trait coded by one rater is correlated with each trait coded by a second, and all the codings by a single rater are intercorrelated with each other. The results are presented in a multitrait-multi-rater matrix. From this matrix it is possible to determine the interrater reliability and discriminant validity of trails in addition to a higher order concept based on pairs of traits.