Continuous single sensillum recording as a detection method for moth pheromone components in the effluent of a gas chromatograph

ABSTRACT. Single sensillum recordings were made from male antennal pheromone receptors of Agrotis segetum (Schiff.) (Noctuidae) and Adoxophyes orana (F.v.R.) (Tortricidae). A gas chromatograph (GC) was used to prepare and to deliver the odour stimuli. Samples of female abdominal gland extracts were injected into the column of the GC and the responses of the receptor cells to the effluent were recorded continuously. The receptor cells responded with an increase of their action potential frequency during elution of the major pheromone components. The pheromone receptors of Agrotis showed a much higher sensitivity than those of Adoxophyes. In the extract of female glands from Agrotis , compounds were detected which have not been identified in previous studies of the sex pheromone of this species. It is suggested that the combination of GC techniques with direct single sensillum recording may serve as a valuable supplement to electro-antennographic techniques.     

How much air passes through a silkmoth's antenna?

Airflow through an antenna of Actias luna and other saturniid moths is much lower than the speed of the wind to which the antenna is exposed. At wind speeds of 0.75–2.75 m sec^?1, between 8 and 18% of the air directly upwind from an antenna will pass through it. By contrast, about 38% of light striking an antenna passes through, pointing out the effect of viscosity on flow through a fine mesh filter.     

Active antennal movements in Drosophila can tune wind encoding

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Elements of the olfactory signaling pathways in insect antennae

Owing to their enormous ability to recognize airborne molecules, insects have long been used as model systems for studying various aspects of olfaction. Modern biological techniques have opened new avenues for exploring the molecular mechanisms underlying the complex signaling processes in chemosensory neurons. Biochemical and molecular analyses have allowed the identification of molecular elements of the olfactory reaction pathways and have shed light on mechanisms that account for the sensitivity and specificity of the chemosensory system.     

On the Head Morphology and Systematic Position of Helophorus (Coleoptera: Hydrophiloidea: Helophoridae)

External and internal features of the head of adults of Helophorus spp. were examined and described in detail. The 6 species under consideration show very little morphological variation. The only distinctive characters, which characterise groups of species, are the presence or absence of the mandibular retinaculum and the symmetric or asymmetric shape of the ultimate maxillary palpomere. Helophoridae is supported by several autapomorphies, e.g. a group of long hairs on the posterodorsal margin of galeomere II and the distinctly serrate hind margin of the right mola. Characters with a potential phylogenetic relevance are listed, presented as a data matrix and analysed cladistically. The monophyly of Hydrophiloidea + Histeroidea, Hydrophiloidea (excl. Hydraenidae), ((Helophoridae + Hydrochidae) + (Georissidae [+ Epimetopidae?])), Hydrophilidae and Sphaeridiinae was supported in all trees. The position of Spercheus remains ambiguous. It is either the sistergroup of the remaining Hydrophiloidea or of Hydrophilidae. Head structures of adults of Helophoridae and Hydrochidae show a remarkable similarity. The following apomorphic character states are shared by both taxa: dorsal side of labrum divided into 2 areas with different surface structure, mentum with 2 longitudinal ridges. A clade comprising these 2 families + Georissidae (and probably Epimetopidae) is supported by the metallic granulation of the dorsal side of the head capsule and a grooved frontoclypeal suture. The presence of tubular mandibular glands may be a derived groundplan feature of Hydrophiloidea + Histeroidea. The proposed interrelationships are partly in contrast to current hypothesis. The hypothesised character evolution may change, if a more extensive set of taxa (e.g. Horelophinae, Horelophopsinae) and characters, especially larval features are used (e.g. stigmatic atrium). Several derived characteristics of the clades listed above may have been secondarily lost in Hydrophilidae.     

Changes in the Constitution of Thylakoid Membranes in Spruce Needles During an Open-top Chamber Experiment

The goal of the presented paper was to study the emission effects of natural air pollutants on the protein complexes of the thylakoid membrane. The tests were carried out in the frame of a long-term experiment in which spruce trees kept in open-top chambers with unfiltered ambient-air were compared to spruce trees in chambers with purified-air. The reaction centres of photosystem I (P-700), cytochrome f, cytochrome b-563, cytochrome b-559, as well as the oxidation speed of the antennae chlorophylls were quantified. The concentrations of the cytochromes f and b-563 indicate a marked annual rhythm with decreased concentrations during the summer months. The spruce trees in chambers with ambient-air showed a smaller amount of the studied redox components in relation to 1000 molecules of chlorophyll than did the spruce trees in chambers exposed to purified-air. In addition, increased oxidation speed of antennae chlorophylls could be observed on the isolated thylakoid membranes of the spruce trees in chambers with ambient-air conditions. A relationship between the oxidation speed and the ozone concentration of the ambient air could be observed, i.e. with increasing ozone levels the oxidation of the antennae chlorophylls accelerated. However, the damage occurred only with a temporary delay (the so-called memory effect). In case of the cytochromes f and b-563 (components of the cytochrome b₆f-complex), a chamber effect related to changed light conditions became obvious when comparing spruce trees kept in chambers to trees left in their natural surrounding. The reduced photosynthetically active radiation — it is reduced in the chambers by 10 ? 30% — led to a decrease of both cytochromes. In spite of the effects due to the chambers, the results indicate that ozone could be an effective damage factor and this will be of importance with regard to the situation in the low mountain range of Germany.