Fine structure of the ventral organ of the house fly larva,Musca domestica L.

Summary The ventral organs of the cephalic lobes of the house fly larvae, Musca domestica L., were studied by scanning and transmission electron microscopy. Four sensilla were found. Three of them are each innervated by a single dendrite whose ending possesses a tubular body and communicates to the exterior through an opening. These sensilla are assumed to be mechanoreceptors. The 4th sensillum is supplied by 2 bipolar neurons with the unbranched dendritic tips (without tubular bodies) exposed to the exterior through a single opening and is probably a contact chemoreceptor.This research was supported in part by the Office of Naval Research and NIH Training Grant ES-00069. Paper no. 3724 of the North Carolina State University Agricultural Experiment Station journal series.     

New damsel-dragonflies with “calopterygid”-like wing shape from the Middle Jurassic of China (Odonata: Isophlebioidea: Campterophlebiidae)

The new damsel-dragonflies Zygokaratawia incompleta nov. sp. and Parazygokaratawia azari nov. gen., nov. sp., closely related to the campterophlebiid genus Zygokaratawia, are described from the Middle Jurassic locality of the Daohugou and Chentaizi villages, respectively (Ningcheng County, Inner Mongolia, NE China). Parazygokaratawia nov. gen. and Zygokaratawia share a narrowly reduced cubito-anal area, unique synapomorphy in the Isophlebioptera. Campterophlebiids with this character are only known from the Daohugou biota.     

First description of axymyiid fossils (Insecta: Diptera: Axymyiidae)

Two species of fossil insects from the Daohugou Formation of Chifeng City in Nei Monggol Autonomous Region, northeastern China are described, and recognized as Psocites pectinatus (Hong, 1983) nov. emend., nov. transl. and P. fossilis nov. sp. They are the oldest representatives of the family Callovian or Axymyiidae, and first described of this family in the Mesozoic. Although early the age of the fly-bearing beds is controversial, it is probably Oxfordian or Kimmeridgian (Late Jurassic) rather than Early Cretaceous or Middle Jurassic.     

陕西中三叠世中蝎蛉科两新属和新种(昆虫纲,长翅目)

记述中蝎蛉科Mesopanorpodidae 2新属、新种：Triassochoristites jinsuoguanensis gen．et sp．nov．,Forcinerva tongchuanensis gen．et sp．nov．化石标本采自陕西铜川中三叠世铜川组下段上部的灰绿色泥岩和页岩。这些新属、种系陕西昆虫群(陕西生物群的一个类别)铜川昆虫组合的新成员。铜川组的时代相当于欧洲拉丁尼期(Ladinian Stagc)。     

The mitochondrial genome of <Emphasis Type="Italic">Protohermes concolorus</Emphasis> Yang et Yang 1988 (Insecta: Megaloptera: Corydalidae)

The first complete mitochondrial genome of dobsonfly Protohermes concolorus Yang et Yang, 1988 (Megaloptera: Corydalidae) was sequenced in this study. The genome was a circular molecule of 15,851 bp containing the typical 37 genes that arranged in the same order as that of the putative ancestor of hexapods. Sequences overlaps were observed between several neighbor genes, which made the genome relatively compact. The tRNA-Ser (GCT) could not be folded into typical secondary structure because its DHU arm was replaced with a simple loop. Six of the 13 protein genes were terminated with a single T adjacent to a downstream tRNA gene in the same strand. The variation of GC content caused the different nucleotide substitution patterns of the protein genes. The genome was AT-biased with a total A + T content of 75.83% which was also demonstrated by the codon usage. The control region was the most AT-rich region with a sub-region of even higher A + T content. Protein genes of two strands presented opposite CG-skew trends which was also reflected by the codon usage. For most of the amino acids, the protein coding sequences did not prefer to use the cognate codons of corresponding tRNAs and the codon usage of the protein genes was not random. The variation of nucleotide substitution patterns of protein genes was significantly correlated with the GC content. The phylogenetic analyses based on all the 13 protein genes showed that Megaloptera was the sister group of other holometabolous insects except Coleoptera.     

<Emphasis Type="Italic">Rab11</Emphasis> is required for myoblast fusion in <Emphasis Type="Italic">Drosophila</Emphasis>

Rab11, an evolutionarily conserved, ubiquitously expressed subfamily of small monomeric Rab GTPases, has been implicated in regulating vesicular trafficking through the recycling of endosomal compartment. In order to gain an insight into the role of this gene in myogenesis during embryonic development, we have studied the expression pattern of Rab11 in mesoderm during muscle differentiation in Drosophila embryo. When dominant-negative or constitutively active Drosophila Rab11 proteins are expressed or Rab11 is reduced via double-stranded RNA in muscle precursors, they cause partial failure of myoblast fusion and show anomalies in the shape of the muscle fibres. Our results suggest that Rab11 plays no role in cell fate specification in muscle precursors but is required late in the process of myoblast fusion. This work was supported by grants from the DST (to J.K.R.) and SRF from ICMR, New Delhi (to T.B.).     

Cloning and expression pattern of a putative octopamine/tyramine receptor in antennae of the noctuid moth <Emphasis Type="Italic">Mamestra brassicae</Emphasis>

In insects, biogenic amines have been shown to play an important role in olfactory plasticity. In a first attempt to decipher the underlying molecular mechanisms, we report the molecular cloning and precise expression pattern of a newly identified octopamine/tyramine-receptor-encoding gene in the antennae of the noctuid moth Mamestra brassicae (MbraOAR/TAR). A full-length cDNA has been obtained through homology cloning in combination with rapid amplification of cDNA ends/polymerase chain reaction; the deduced protein exhibits high identities with previously identified octopamine/tyramine receptors in other moths. In situ hybridization within the antennae has revealed that MbraOAR/TAR is expressed at the bases of both pheromone-sensitive and non-sensitive olfactory sensilla and in cells with a neurone-like shape. In accordance with previous physiological studies that have revealed a role of biogenic amines in the electrical activity of the receptor neurones, our results suggest that biogenic amines (either octopamine or tyramine) target olfactory receptor neurones to modulate olfactory coding as early as the antennal level.     

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).     

Peritrophic matrix of Phlebotomus duboscqi and its kinetics during Leishmania major development

Light microscopy of native preparations, histology, and electron microscopy have revealed that Phlebotomus duboscqi belongs to a class of sand fly species with prompt development of the peritrophic matrix (PM). Secretion of electron-lucent fibrils, presumably chitin, starts immediately after the ingestion of a blood meal and, about 6 h later, is followed by secretion of amorphous electron-dense components, presumably proteins and glycoproteins. The PM matures in less than 12 h and consists of a thin laminar outer layer and a thick amorphous inner layer. No differences have been found in the timing of the disintegration of the PM in females infected with Leishmania major. In both groups of females (infected and uninfected), the disintegration of the PM is initiated at the posterior end. Although parasites are present at high densities in the anterior part of the blood meal bolus, they escape from the PM at the posterior end only. These results suggest that L. major chitinase does not have an important role in parasite escape from the PM. Promastigotes remain in the intraperitrophic space until the PM is broken down by sand-fly-derived chitinases and only then migrate anteriorly. Disintegration of the PM occurs simultaneously with the morphological transformation of parasites from procyclic forms to long nectomonads. A novel role is ascribed to the anterior plug, a component of the PM secreted by the thoracic midgut; this plug functions as a temporary barrier to stop the forward migration of nectomonads to the thoracic midgut. This work was supported by the Ministry of Education of the Czech Republic (projects MSM0021620828 and LC06009).