The wing-scale morphologies of the pierid butterflies Pieris rapae (small white) and Delias nigrina (common jezabel), and the heliconine Heliconius melpomene are compared and related to the wing-reflectance spectra. Light scattering at the wing scales determines the wing reflectance, but when the scales contain an absorbing pigment, reflectance is suppressed in the absorption wavelength range of the pigment. The reflectance of the white wing areas of P. rapae, where the scales are studded with beads, is considerably higher than that of the white wing areas of H. melpomene, which has scales lacking beads. The beads presumably cause the distinct matt-white colour of the wings of pierids and function to increase the reflectance amplitude. This will improve the visual discrimination between conspecific males and females.

Neuroanatomical studies have demonstrated that the architecture and organization among neuropils are highly conserved within any order of arthropods. The shapes of nerve cells and their neuropilar arrangements provide robust characters for phylogenetic analyses. Such analyses so far have agreed with molecular phylogenies in demonstrating that entomostracansCmalacostracans belong to a clade (Tetraconata) that includes the hexapods. However, relationships among what are considered to be paraphyletic groups or among the stem arthropods have not yet been satisfactorily resolved. The present parsimony analyses of independent neuroarchitectural characters from 27 arthropods and lobopods demonstrate relationships that are congruent with phylogenies derived from molecular studies, except for the status of the Onychophora. The present account describes the brain of the onychophoran Euperipatoides rowelli, demonstrating that the structure and arrangements of its neurons, cerebral neuropils and sensory centres are distinct from arrangements in the brains of mandibulates. Neuroanatomical evidence suggests that the organization of the onychophoran brain is similar to that of the brains of chelicerates.

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The interaction between the moth, Cactoblastis cactorum, and the cactus, Opuntia stricta, is used as a model to examine the question of whether the CO sense of a herbivorous insect can detect the CO gradients associated with a plant's metabolic activity. Both the anatomical and the electrophysiological characteristics of CO-sensitive receptor neurons in C. cactorum indicate an adaptation to the detection of small fluctuations around the atmospheric background. Evidence is provided that further rises in background will impair the function of the sensory organ. In the habitat of the plant, during the diurnal window of the moth's activity, two types of CO gradients occur that are detectable by the moth's sensors. The first gradient, associated with soil respiration, is vertical and extends from the soil surface to an altitude of approximately 1 m. Its magnitude is well above the detectability limit of the sensors. The notion that this gradient provides, to a flying insect, a cue for the maintenance of a flight altitude favourable for host detection is supported by field observations of behaviour. The second gradient, associated with CO fixation by the plant, extends from the surfaces of photosynthetic organs (cladodes) over a boundary layer distance of approximately 5 mm. Again, its magnitude is well above the detectability limit. The notion that this gradient provides, to a walking insect, a cue to the physiological condition of the plant is supported by the observation that females of C. cactorum, prior to oviposition, actively probe the plant surface with their CO sensors. In a simulation of probing, pronounced responses of the sensors to the CO-fixing capacity of O. stricta are observed. We propose that by probing the boundary layer, females of C. cactorum can detect the healthiest, most active O. stricta cladodes, accounting for earlier observations that the most vigorous plants attract the greatest density of egg sticks.

Mineral trioxide aggregate (MTA) is widely used for different perforation repairs, root-end filling, pulp capping and many other endodontic procedures. Because of potential discoloration effect of gray MTA, white MTA has been introduced into endodontic treatment for the same purposes. This study examined the dental pulp responses in dogs to both types of MTA used as a pulp-capping agent. The pulps of 24 teeth of four male dogs were exposed with a No.1 round bur and capped with either gray or white MTA. Histologic analysis was performed one and 2 weeks after treatment. Calcified bridge could be seen 1 week after treatment with both types of MTA, with no significant differences between the two treatments.

Mineral trioxide aggregate (MTA) is used in endodontics as a filling and sealant material. An earlier commercial formulation Grey MTA (GMTA) was liable to became progressively discoloured, and a whiter version (WMTA) has been introduced for cosmetic reasons. This study compares the composition and particle size distribution of the two formulations using energy dispersive X-ray analysis in a scanning electron microscope. Particle size is smaller in WMTA. X-ray analysis reveals similar major peaks (calcium, silicon and bismuth) but those of the minor elements aluminium, magnesium and particularly iron are considerably less in WMTA, which may account for the colour difference. Neither contains phosphorus, a major constituent of the original formulation.

Large areas of photoreceptor membrane are synthesized in the retinula cells of the crab Leptograpsus variegatus at dusk. Initially, new membrane differentiates from rough endoplasmic reticulum (ER) as large tubules of smooth ER. These tubules transform to concentric ellipsoids of closely apposed pairs of membranes ("doublet ER"), sometimes passing through an intervening crenate form. The new membrane is transported through bridges of cytoplasm that cross the palisade to the rhabdom region, from which the remains of the rhabdomeres that were built during the previous dusk have been dissolved. The degradation of the old microvilli of one rhabdomere is acomplished without affecting neighbouring rhabdomeres of other cells. New microvilli are assembled in situ from sheets of doublet ER, which are converted to tubules oriented in the same direction as the future microvilli. The cytoplasmic face of the ER remains the cytoplasmic face of the tubules, which become progressively narrower, partly by further longitudinal division, until the final diameter of the microvillus is reached. A central core is often seen in transverse sections of mature microvilli. It may be involved in the final consolidation, but rhabdomeric microvilli are not formed in the same manner as those of intestinal brush border cells. There is no evidence that new membrane passes through the Golgi compartment before incorporation into the rhabdom, as is the case for rod outer segment membrane in vertebrate photoreceptors.