Agrotis segetum雄蛾触角叶性信息素反应神经元对电刺激触角神经的反应

为探讨电刺激Agrotis segetum雄蛾触角神经是否可以作为MGC中神经元的识别手段,采用细胞内电生理记录方法,共记录34个对性信息素有反应的MGC神经元,并测试了其中12个神经元对性信息素刺激的反应,22个神经元对性信息素刺激和电刺激的反应。结果表明,MGC神经元对性信息素及电刺激的反应模式基本一致,为一种双相反应模式。两种刺激方式均能诱导出兴奋反应,电刺激得到的兴奋反应比由信息素刺激引起的要短;MGC神经元对两种刺激的超极化反应（抑制反应）幅度影响没有显著性差别,在电刺激实验的22个神经元上,超极化反应幅度和抑制时间都与神经元本身放电频率有一定的相关性。超极化反应是在LN参与下一定的神经回路对刺激所产生的反应而形成的。这提示两种刺激所作用的神经回路应是一致的,但从整个实验过程记录到的神经元情况来看,还须进一步结合形态学实验来验证电刺激触角神经作为MGC神经元的识别手段。     

Neurons discovered in male Helicoverpa zea antennae that correlate with pheromone-mediated attraction and interspecific antagonism

Responses of single receptor neurons in the antennae of male Helicoverpa zea to sex pheromone components and to behavioral antagonists were recorded using a cut-sensillum extracellular recording technique. Three types of sensilla were identified from sampling 325 male-specific sensilla trichodea located at the lateral edge of antennomeres. The majority of these sensilla (71%) contained a receptor neuron tuned to the principal sex pheromone component (Z)-11-hexadecenal. A second sensillar type (10%) contained a receptor neuron that responded only to (Z)-9-tetradecenal. A third sensillar type (19%) contained a large-spiking neuron tuned to the secondary pheromone component (Z)-9-hexadecenal, but this neuron also could be stimulated to equivalent spike frequencies by the same emitted amounts of (Z)-9-tetradecenal. A smaller-spiking neuron in this sensillar type responded to two compounds known to act only as behavioral antagonists, (Z)-11-hexadecen-1-ol and (Z)-11-hexadecenyl acetate, and to (Z)-9-tetradecenal. Cross-adaptation studies confirmed the presence of one large- and one small-spiking neuron in the third sensillar type. Dose-response studies correlated to collected stimuli amounts showed that the large-spiking neuron in the third sensillar type was equally tuned to (Z)-9-hexadecenal and (Z)-9-tetradecenal, whereas the smaller-spiking neuron was far more sensitive to (Z)-11-hexadecen-1-ol and to (Z)-11-hexadecenyl acetate than to (Z)-9-tetradecenal. Accepted: 29 September 1997     

Irregular chiasm-C-roughest, a member of the immunoglobulin superfamily, affects sense organ spacing on the Drosophila antenna by influencing the positioning of founder cells on the disc ectoderm

We describe a role for Irregular chiasmC-roughest (IrreC-rst), an immunoglobulin (Ig) superfamily member, in patterning sense organs on the Drosophila antenna. IrreC-rst protein is initially expressed homogeneously on apical profiles of ectodermal cells in regions of the antennal disc. During specification of founder cells (FCs), the intracellular protein distribution changes and becomes concentrated in regions where specific intercellular contacts presumably occur. Loss of function mutations as well as misexpression of irreC-rst results in an altered arrangement of FCs within the disc compared to wildtype. Sense organ development occurs normally, although spacing is affected. Unlike its role in interommatidial spacing, irreC-rst does not affect apoptosis during antennal development. We propose that IrreC-rst affects the spatial relationship between sensory and ectodermal cells during FC delamination. Received: 19 January 1999 / Accepted: 10 May 1999     

Neurosecretory cells in the optic lobes of the brain and activity rhythms in Lycosa tarentula (Araneae: Lycosidae)

Several paired groups of neurosecretory cells (NS) were identified in the dorsal cortical neurons of the optic lobes of the brain of Lycosa tarentula (Araneae). Two large bottle-shaped cells (NS A1, A2) and a cluster of ca. 20 smaller cells (NS B) were found between the lamina and medulla of the anterior median eyes (AM). The forward oriented bundles of NS B axons run alongside large fibres linked to the synaptic zones of the indirect eyes. In front of the arcuate body, an islet of about 10 fusiform cells (NS C1) sends short axons close to the internal cortical border. Other large cells (NS C2, C3) are found from the medulla of the AM to the anterior border of the central body. Their long axons end deeply in the brain neuropil. NS B and C1 function synchronously. The secretory cycles of NS A1 and A2 seem to be in opposition. The activity of these three types of NS depends on the phase of the day. Anatomical relationships of NS A, B and C1 with visual afferent/efferent fibres via synaptic buttons indicate a role of these cells in the modulation of circadian rhythms of visual and locomotor activity. On the other hand, NS C2 and C3, the functioning of which is not synchronous, might be involved in the modulation or control of the elementary movements of L. tarentula when active or at rest.     

Description of the antennal sensilla of <Emphasis Type="Italic">Habrobracon Hebetor</Emphasis>

The morphology of the antennal sensilla of both male and female Habrobracon hebetor (Say) (Hymenoptera: Braconidae) is described using Scanning Electron Microscopy complemented with Transmission Electron Microscopy. Five types of innervated sensilla as well as uninnervated microtrichia were found. These types are: sensilla trichodea; s. chaetica; s. basiconica; s. coeloconica; and s. placodea. No differences in shape, basic structure, and types of antennal sensilla were found between males and females. The types of sensilla of both sexes of H. hebetor were compared with what has been described in other parasitic Hymenoptera, and their putative functions are discussed with reference to their morphology, distribution and ultrastructure.     

Age-dependent plasticity of sex pheromone response in the moth, Agrotis ipsilon: Combined effects of octopamine and juvenile hormone

Male moths use sex pheromones to find their mating partners. In the moth, Agrotis ipsilon, the behavioral response and the neuron sensitivity within the primary olfactory centre, the antennal lobe (AL), to sex pheromone increase with age and juvenile hormone (JH) biosynthesis. By manipulating the JH level, we previously showed that JH controls this age-dependent neuronal plasticity, and that its effects are slow (within 2 days). We hypothesized that the hormonal effect might be indirect, and one neuromodulator candidate, which might serve as a mediator, is octopamine (OA). Here, we studied the effects of OA and an OA receptor antagonist, mianserin, on behavioral and AL neuron responses of mature and immature males during stimulation with sex pheromone. Our results indicate that, although OA injections enhanced the behavioral pheromone response in mature males, OA had no significant effect on behavior in immature males. However, mianserin injections decreased the behavioral response in mature males. AL neuron sensitivity increased after OA treatment in immature males, and decreased after mianserin treatment in mature males. Determination of OA levels in ALs of immature and mature males did not reveal any difference. To study the possible interactive effects of JH and OA, the behavioral pheromone response was analyzed in JH-deprived mature males injected with OA, and in immature males injected with fenoxycarb, a JH agonist, and mianserin. Results show that both JH and OA are necessary to elicit a behavioral response of A. ipsilon males to sex pheromone.     

Three-dimensional antennal lobe atlas of the oriental fruit moth, <Emphasis Type="Italic">Cydia molesta</Emphasis> (Busck) (Lepidoptera: Tortricidae): comparison of male and female glomerular organization

The oriental fruit moth Cydia molesta is an important pest and the behavioural role of olfactory signals such as pheromones and plant volatiles have been studied extensively in both sexes. To understand odour processing further, however, detailed knowledge of the anatomy of the olfactory system is crucial. In the present study, an atlas of the antennal lobe (AL) is presented based on the three-dimensional reconstructions of both ALs of three male and three female brains by means of neuroanatomical and computational approaches. We identified 48–49 "ordinary" glomeruli and one large glomerulus situated at the entrance of the antennal nerve in males, and 49–52 "ordinary" glomeruli and one large glomerulus in the ventro-medial part of the AL in females. Anomalous supernumerary, anomalous missing and sexually dimorphic glomeruli were found in the studied individuals in greater numbers than in other lepidopteran species. Male and female maps were compared with respect to glomerular size and position with 45 glomeruli being matched, indicating a conserved glomerular pattern between the sexes. Three additional glomeruli were sexually dimorphic in size and five male-specific and six female-specific glomeruli were also found. Palp backfills resulted in the staining of a unique glomerulus in both sexes identified as the sexually dimorphic glomerulus 45. This glomerulus was never stained from antennal backfills, which stained the other glomeruli of the AL. The three-dimensional atlas can now be used to elucidate the functional role of individual glomeruli in both sexes of C. molesta. Nélia Varela and Louise Couton contributed equally to this work. This study was supported by research grants from INRA (Projet Jeune Equipe and Projet S.P.E.) to S.A. and J.P.R. and by the Spanish Ministry of Science and Technology (research grant AGL2004-05812/AGR to J.A. and C.G., Spanish Science and Education Department, MEC). N.V. was financed by fellowship no. BES-2005-7605 (MEC, Spain).     

γ-Aminobutyric acid immunostaining in the antennal lobe of the moth <Emphasis Type="Italic">Heliothis virescens</Emphasis> and its colocalization with neuropeptides

The antennal lobe is the primary processing center for olfactory information in insects. To understand further the neural circuitry of this brain area, we have investigated the distribution of γ-aminobutyric acid (GABA) and its colocalization with neuropeptides in the antennal lobe of the noctuid moth Heliothis virescens. Immunocytochemical experiments with an antiserum against GABA showed a large number of labeled somata in the antennal lobe; these somata were located exclusively in the lateral cell cluster. Stained neurites innervating all antennal-lobe glomeruli, including the male-specific macroglomerular complex, suggested a prominent role of GABA in processing olfactory information, including signals from pheromones, interspecifically acting odors, and plant odors. Fibers in two antennocerebral tracts (the middle and dorsal antennocerebral tract) exhibited prominent GABA immunoreactivity. Double-labeling experiments revealed that immunostaining for three neuropeptides, viz., A-type allatostatin, Manduca sexta allatotropin, and FMRFamide-related peptides, was largely colocalized with GABA in cell bodies of the lateral cell cluster. The general absence of peptide immunostaining in the antennocerebral tracts strongly indicated that these peptides were colocalized with GABA in local interneurons of the antennal lobe. In contrast, tachykinin-related peptides occurred in a distinct population of local antennal-lobe neurons that did not exhibit GABA immunostaining. Thus, local interneurons that were not GABAergic were present in the moth antennal lobe. This work was supported by the Norwegian University of Science and Technology (project no. 80902101).     

Effect of explant source and auxins on somatic embryogenesis of selected cassava (Manihot esculenta Crantz) cultivars

Competence for somatic embryogenesis of eight cassava cultivars T200, AR9-18, MTAI16, CR25-4, CM523-7, BRA1183, MCOL2261 and SM707-17 was compared to model cultivar TMS60444 in induction media containing 12 mg/l picloram or 8 mg/l 2,4-dichloro phenoxyacetic acid (2,4-D), using axillary buds (AB) and immature leaf lobes (ILL) as explants. There were significant differences (p < 0.01) among the cassava genotypes for ability to form somatic embryos (SE). In general, AB as the explant and picloram-containing medium had the highest frequency of SE for TMS60444, T200, MTAI16, CR25-4 and CM523-7 while AR9-18 had greater efficiency using ILL on picloram. Cultivars BRA1183, MCOL2261 and SM707-17 produced insignificant amounts of SE; however, loose callus and friable embryogenic callus (FEC) appeared to be the predominant tissue type observed. Five out of the eight cultivars studied showed capability of producing SE although their efficiency for somatic embryogenesis was not as high as the model cultivar TMS60444.     

Age‐dependent and task‐related volume changes in the mushroom bodies of visually guided desert ants,Cataglyphis bicolor

Desert ants of the genus Cataglyphis are skillful long‐distance navigators employing a variety of visual navigational tools such as skylight compasses and landmark guidance mechanisms. However, the time during which this navigational toolkit comes into play is extremely short, as the average lifetime of a Cataglyphis forager lasts for only about 6 days. Here we show, by using immunohistochemistry, confocal microscopy, and three‐dimensional reconstruction software, that even during this short period of adult life, Cataglyphis exhibits a remarkable increase in the size of its mushroom bodies, especially of the visual input region, the collar, if compared to age‐matched dark‐reared animals. This task‐related increase rides on a much smaller age‐dependent increase of the size of the mushroom bodies. Due to the variation in body size exhibited by Cataglyphis workers we use allometric analyses throughout and show that small animals exhibit considerably larger task‐related increases in the sizes of their mushroom bodies than larger animals do. It is as if there were an upper limit of mushroom body size required for accomplishing the ant's navigational tasks. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006