Expression of the human FUSED protein in <Emphasis Type="Italic">Drosophila</Emphasis>

The Drosophila segment polarity gene fused, which encodes a serine threonine kinase, is required to transmit the Hedgehog (Hh) signal in imaginal discs. To explore the functional homology between the human protein FUSED (hFU) and the Drosophila protein fused (dFu), we have subjected hFU to a precise and well-defined Hh signalling assay of Drosophila wing development. In the wildtype, hFU affects the expression of Hh target genes leading thus to defects in adult wings. In fu mutants, overexpression of hFU cannot rescue the fu phenotype. These results suggest that hFU in Drosophila interferes with endogenous Hh signalling probably by competing with endogenous dFu when binding its partners but cannot perform the normal Fu function.Edited by C. Desplan     

Behavioral Sequence Leading to Sexual Isolation Between <Emphasis Type="Italic">Drosophila ananassae</Emphasis> and <Emphasis Type="Italic">D. pallidosa</Emphasis>

Drosophila ananassae and D. pallidosa are closely related, sympatric species that lack postmating isolation. Sexual isolation has been considered important in maintaining them as independent species. To clarify the behavioral processes leading to sexual isolation, we analyzed behavioral sequences and examined the effect of courtship song on mating success and on behaviors of both sexes by surgically removing male wings (song generators), female aristae (song receivers), or female wings (means of fluttering). We found that heterospecific courtship songs evoked female wing fluttering, whereas conspecific courtship song did not. Furthermore, female wing fluttering made courting males discontinue courtship. These findings suggest that strong sexual isolation is achieved through the following behavioral sequence: heterospecific song→female wing fluttering→courtship discontinuation.     

Functional conservation of the human <Emphasis Type="Italic">EXT1</Emphasis> tumor suppressor gene and its <Emphasis Type="Italic">Drosophila</Emphasis> homolog <Emphasis Type="Italic">tout</Emphasis><Emphasis Type="Italic">velu</Emphasis>

Heparan sulfate proteoglycans play a vital role in signaling of various growth factors in both Drosophila and vertebrates. In Drosophila, mutations in the tout velu (ttv) gene, a homolog of the mammalian EXT1 tumor suppressor gene, leads to abrogation of glycosaminoglycan (GAG) biosynthesis. This impairs distribution and signaling activities of various morphogens such as Hedgehog (Hh), Wingless (Wg), and Decapentaplegic (Dpp). Mutations in members of the exostosin (EXT) gene family lead to hereditary multiple exostosis in humans leading to bone outgrowths and tumors. In this study, we provide genetic and biochemical evidence that the human EXT1 (hEXT1) gene is conserved through species and can functionally complement the ttv mutation in Drosophila. The hEXT1 gene was able to rescue a ttv null mutant to adulthood and restore GAG biosynthesis.     

Expression of <Emphasis Type="Italic">defective proventriculus</Emphasis> during head capsule development is conserved in <Emphasis Type="Italic">Drosophila</Emphasis> and stalk-eyed flies (<Emphasis Type="Italic">Diopsidae</Emphasis>)

Hypercephaly, in the form of lateral extensions of the head capsule, is observed in several families of Diptera. A particularly exaggerated form is found in Diopsid stalk-eyed flies, in which both eyes and antennae are laterally displaced at the end of stalks. The processes of early development and specification of the head capsule in stalk-eyed flies are similar to those in Drosophila melanogaster. In Drosophila the homeobox gene ocelliless (oc) shows a mediolateral gradient of expression across the region of the eye-antennal imaginal disc that gives rise to the head capsule and specifies the development of different head structures. The genes and developmental mechanisms that subsequently define head shape in Drosophila and produce hypercephaly in stalk-eyed flies remain unclear. To address this, we performed an enhancer trap screen for Drosophila genes expressed in the same region as oc and identified the homeobox gene defective proventriculus (dve). In the eye-antennal imaginal disc, dve is coexpressed with oc in the region that gives rise to the head capsule and is active along the medial edge of the antennal disc and in the first antennal segment. Analyses of dve expression in mutant eye-antennal discs are consistent with it acting downstream of oc in the development of the head capsule. We confirm that orthologues of dve are present in a diverse panel of five stalk-eyed fly species and analyse patterns of dve sequence variation within the clade. Our results indicate that dve expression and sequence are both highly conserved in stalk-eyed flies.M. Carr and I. Hurley contributed equally to this work.     

<Emphasis Type="Italic">Drosophila</Emphasis><Emphasis Type="Italic">P</Emphasis> transposons of the urochordata <Emphasis Type="Italic">Ciona intestinalis</Emphasis>

P transposons belong to the eukaryotic DNA transposons, which are transposed by a cut and paste mechanism using a P-element-coded transposase. They have been detected in Drosophila, and reside as single copies and stable homologous sequences in many vertebrate species. We present the P elements Pcin1, Pcin2 and Pcin3 from Ciona intestinalis, a species of the most primitive chordates, and compare them with those from Ciona savignyi. They showed typical DNA transposon structures, namely terminal inverted repeats and target site duplications. The coding region of Pcin1 consisted of 13 small exons that could be translated into a P-transposon-homologous protein. C. intestinalis and C. savignyi displayed nearly the same phenotype. However, their P elements were highly divergent and the assumed P transposase from C. intestinalis was more closely related to the transposase from Drosophila melanogaster than to the transposase of C. savignyi. The present study showed that P elements with typical features of transposable DNA elements may be found already at the base of the chordate lineage. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Study of tauopathies by comparing <Emphasis Type="Italic">Drosophila</Emphasis> and human <Emphasis Type="Italic">tau</Emphasis> in <Emphasis Type="Italic">Drosophila</Emphasis>

The microtubule-binding protein tau has been investigated for its contribution to various neurodegenerative disorders. However, the findings from transgenic studies, using the same tau transgene, vary widely among different laboratories. Here, we have investigated the potential mechanisms underlying tauopathies by comparing Drosophila (d-tau) and human (h-tau) tau in a Drosophila model. Overexpression of a single copy of either tau isoform in the retina results in a similar rough eye phenotype. However, co-expression of Par-1 with d-tau leads to lethality, whereas co-expression of Par-1 with h-tau has little effect on the rough eye phenotype. We have found analogous results by comparing larval proteomes. Through genetic screening and proteomic analysis, we have identified some important potential modifiers and tau-associated proteins. These results suggest that the two tau genes differ significantly. This comparison between species-specific isoforms may help to clarify whether the homologous tau genes are conserved. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. This study was supported by the National Science Foundation of China (30270341; 30630028), the Multidisciplinary Program (Brain and Mind) of the Chinese Academy of Sciences, the Major State Basic Research Program (“973 program”; G2000077800; G2006CB806600; 2006CB911003), the Precedent Project of Important Intersectional Disciplines in the Knowledge Innovation Engineering of the Chinese Academy of Sciences (KJCX1-09-03).     

The involvement of <Emphasis Type="Italic">engrailed</Emphasis> and <Emphasis Type="Italic">wingless</Emphasis> during segmentation in the onychophoran <Emphasis Type="Italic">Euperipatoides kanangrensis</Emphasis> (Peripatopsidae: Onychophora) (Reid 1996)

As the putative sister group to the arthropods, onychophorans can provide insight into ancestral developmental mechanisms in the panarthropod clade. Here, we examine the expression during segmentation of orthologues of wingless (Wnt1) and engrailed, two genes that play a key role in defining segment boundaries in Drosophila and that appear to play a role in segmentation in many other arthropods. Both are expressed in segmentally reiterated stripes in all forming segments except the first (brain) segment, which only shows an engrailed stripe. Engrailed is expressed before segments are morphologically visible and is expressed in both mesoderm and ectoderm. Segmental wingless expression is not detectable until after mesodermal somites are clearly distinct. Early engrailed expression lies in and extends to both sides of the furrow that first demarcates segments in the ectoderm, but is largely restricted to the posterior part of somites. Wingless expression lies immediately anterior to engrailed expression, as it does in many arthropods, but there is no precise cellular boundary between the two expression domains analogous to the overt parasegment boundary seen in Drosophila. Engrailed stripes extend along the posterior part of each limb bud, including the antenna, while wingless is restricted to the distal tip of the limbs and the neurectoderm basal to the limbs. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Flavonoids in the leaves of <Emphasis Type="Italic">Oxalis corniculata </Emphasis>and sequestration of the flavonoids in the wing scales of the pale grass blue butterfly, <Emphasis Type="Italic">Pseudozizeeria </Emphasis><Emphasis Type="Italic">maha</Emphasis>

Three C-glycosylflavones in the leaves of Oxalis corniculata, the host plant of the lycaenid butterfly pale grass blue (Pseudozizeeria maha), were identified as 6-C-glucosylluteolin (isoorientin), 6-C-glucosylapigenin (isovitexin) and isovitexin 7-methyl ether (swertisin). Comparative spectral and HPLC analyses between the leaf extract of the host plants and the wings of P. maha showed selective uptake of the host-plant flavonoid isovitexin to the wings of the butterfly.     

<Emphasis Type="Italic">Drosophila melanogaster</Emphasis> gene <Emphasis Type="Italic">Merlin</Emphasis> interacts with the clathrin adaptor protein gene <Emphasis Type="Italic">lap</Emphasis>

The protein Merlin is involved in the regulation of cell proliferation and differentiation in the eyes and wings of Drosophila and is a homolog of the human protein encoded by the Neurofibromatosis 2 (NF2) gene whose mutations cause auricular nerve tumors. Recent studies show that Merlin and Expanded cooperatively regulate the recycling of membrane receptors, such as the epidermal growth factor receptor (EGFR). By performing a search for potential genetic interactions between Merlin (Mer) and the genes important for vesicular trafficking, we found that ectopic expression in the wing pouch of the clathrin adapter protein Lap involved in clathrin-mediated receptor endocytosis resulted in the formation of extra vein materials. On the one hand, coexpression of wild-type Merlin and lap in the wing pouch restored normal venation, while overexpression of a dominant-negative mutant Mer ^DBB together with lap enhanced ectopic vein formation. Using various constructs with Merlin truncated copies, we showed the C-terminal portion of the Merlin protein to be responsible for the Merlin-lap genetic interaction. Furthermore, we showed that the Merlin and Lap proteins colocalized at the cortex of the wing imaginal disc cells.     

The morphology of stipules and inflorescences in <Emphasis Type="Italic">Geissois sensu stricto</Emphasis> (<Emphasis Type="Italic">Cunoniaceae</Emphasis>)

Summary   Geissois sensu stricto (i.e. excluding the Australian species of this genus) has 19 species restricted to islands in the south-west Pacific and is the sole group in Cunoniaceae in which the stipules are intrapetiolar (axillary) in the adult foliage. In apical buds, paired opposite stipules are coherent round their margins and are either clearly intrapetiolar in relation to the most distal pair of developed leaves (Type I, most species), or they appear interpetiolar due to the abortion of the pair of leaves associated with them and the failure of the internode proximal to them to elongate (Type II, a few species). Stipules are often accrescent and the largest in the family occur in this group, reaching 10 cm long in some species. The ornithophilous racemose inflorescences of members of this group normally consist of either axillary triads (G. hirsuta only) or apparently simple, unbranched racemes which are ramiflorous or occasionally axillary. However, bract scars on the axes proximal to the flowers show that both types of inflorescence module usually consist of two metamers. The structure of the inflorescences and stipules in Geissois sensu stricto supports the distinction between this group and the Australian species traditionally included in Geissois sensu lato.     

Evolution of the <Emphasis Type="Italic">Groucho</Emphasis>/<Emphasis Type="Italic">Tle</Emphasis> gene family: gene organization and duplication events

The Groucho/Tle family of corepressor proteins has important roles in development and in adult tissue in both Protostomes and Deuterostomes. In Drosophila, a single member of this family has been identified. Unlike in Protostomes, most Deutrostomes contain more than two full-length Tle genes. In this study, I analyse the genomic organization and phylogenetic relationship between the long and short forms of the Groucho/Tle family members in Chordata. The genomic location and sequence similarities suggest that Aes/Grg5 and Tle6/Grg6 arose from duplication of the Tle2 gene; each evolved independently and acquired new functions as negative regulators of the other Tle proteins. Based on these data, a model for Groucho/Tle gene evolution is proposed. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

<Emphasis Type="Italic">tantalus</Emphasis>, a potential link between <Emphasis Type="Italic">Notch</Emphasis> signalling and chromatin-remodelling complexes

The tantalus (tan) gene encodes a protein that interacts specifically with the Polycomb/trithorax group protein Additional sex combs (ASX). Both loss-of-function and gain-of-function mutations in tan cause tissue-specific defects in the eyes, wing veins and bristles of adult flies. As these defects are also typical for components of the Notch (N) signalling pathway, we wished to determine if TAN interacts with this pathway. Through careful examination of ectopic tan phenotypes, we find that TAN specifically disrupts all three major processes associated with the N signalling pathway (boundary formation, lateral inhibition, and lineage decisions). Furthermore, ectopic tan expression abolishes expression of two N target genes, wingless (wg) and cut, at the dorsal-ventral boundary of the wing. An interaction between tan and N was also observed using a genetic assay that previously detected interactions between tan and Asx. The previously observed ability of TAN to move between the cytoplasm and nucleus, and to associate with DNA, provides a potential mechanism for TAN to respond to N signalling.Edited by P. Simpson     

Evolutionary History and Mode of the <Emphasis Type="Italic">amylase</Emphasis> Multigene Family in <Emphasis Type="Italic">Drosophila</Emphasis>

Previous studies indicate that the tandemly repeated members of the amylase (Amy) gene family evolved in a concerted manner in the melanogaster subgroup and in some other species. In this paper, we analyzed all of the 49 active and complete Amy gene sequences in Drosophila, mostly from subgenus Sophophora. Phylogenetic analysis indicated that the two types of diverged Amy genes in the Drosophila montium subgroup and Drosophila ananassae, which are located in distant chromosomal regions from each other, originated independently in different evolutionary lineages of the melanogaster group after the split of the obscura and melanogaster groups. One of the two clusters was lost after duplication in the melanogaster subgroup. Given the time, 24.9 mya, of divergence between the obscura and the melanogaster groups (Russo et al. 1995), the two duplication events were estimated to occur at about 13.96 ± 1.93 and 12.38 ± 1.76 mya in the montium subgroup and D. ananassae, respectively. An accelerated rate of amino acid changes was not observed in either lineage after these gene duplications. However, the G+C contents at the third codon positions (GC3) decreased significantly along one of the two Amy clusters both in the montium subgroup and in D. ananassae right after gene duplication. Furthermore, one of the two types of the Amy genes with a lower GC3 content has lost a specific regulatory element within the montium subgroup species and D. ananassae. While the tandemly repeated members evolved in a concerted manner, the two types of diverged Amy genes in Drosophila experienced frequent gene duplication, gene loss, and divergent evolution following the model of a birth-and-death process.     

A<Emphasis Type="Italic"> Dickkopf</Emphasis>-<Emphasis Type="Italic">3</Emphasis>-related gene is expressed in differentiating nematocytes in the basal metazoan<Emphasis Type="Italic"> Hydra</Emphasis>

In vertebrate development the Dickkopf protein family carries out multiple functions and is represented by at least four different genes with distinct biological activities. In invertebrates such as Drosophila and Caenorhabditis, Dickkopf genes have so far not been identified. Here we describe the identification and characterization of a Dickkopf gene with a deduced amino acid sequence closely related to that of chicken Dkk-3 in the basal metazoan Hydra. HyDkk-3 appears to be the only Dickkopf gene in Hydra. The gene is expressed in the gastric region in nematocytes at a late differentiation stage. In silico searches of EST and genome databases indicated the absence of Dkk genes from the protostomes Drosophila and Caenorhabditis, whereas within the deuterostomes, a Dkk-3 gene could be identified in the genome of the urochordate Ciona intestinalis. The results indicate that at an early stage of evolution of multicellularity Dickkopf proteins have already played important roles as developmental signals. They also suggest that vertebrate Dkk-1, 2 and 4 may have originated from a common ancestor gene of Dkk-3.H. Fedders and R. Augustin contributed equally to this workEdited by D. Tautz     

Molecular phylogeography of two sibling species of <Emphasis Type="Italic">Eurema</Emphasis> butterflies

The common yellow butterfly Eurema hecabe is widely distributed in East Asia, and is one of the most burdensome species for taxonomists due to the numerous geographic and seasonal wing colour patterns. Moreover, within this species, individuals with a yellow wing fringe that occur in temperate regions of Japan (Y type) proved to be biologically different from others that occur widely in subtropical regions of Japan and all over East Asia (B type). To unveil the genetic variation within and between the two types, a total of 50 butterflies collected at 18 geographic localities in East Asia were examined for nucleotide sequence variation of three mitochondrial regions: cytochrome c oxidase subunit I (COI), cytochrome c oxidase subunit III (COIII) and NADH dehydrogenase subunit 5 (ND5). In addition, they were also examined for infection status with the endosymbiotic bacteria Wolbachia. The three mitochondrial sequences consistently showed that (i) Y type and B type were highly divergent, (ii) nucleotide variation within B type was very small although sampled from a geographically wide range, and (iii) a weak association existed between mitochondrial DNA haplotypes and Wolbachia infection status.     

Larvae and juveniles of the plunderfishes <Emphasis Type="Italic">Artedidraco shackletoni</Emphasis> and <Emphasis Type="Italic">A.</Emphasis><Emphasis Type="Italic">skottsbergi</Emphasis> (Notothenioidei,Artedidraconidae) from the Indian sector of the Southern Ocean

Early life stages of Artedidraco skottsbergi and A. shackletoni were collected off Adélie Land. The morphology and pigmentation pattern of nine larvae and juveniles of A. skottsbergi between 17.2 and 21.4 mm in standard length (SL), and of two juveniles of A. shackletoni measuring 25.1 mm SL were described. A. skottsbergi was characterized by a heavily pigmented body, except for the caudal peduncle, with distinctively dense pigmentation on the ventrolateral half of the body and caudal section (17.2–17.9 mm SL). Furthermore, they had no pigmentation on the pectoral fin base until they attained 21.4 mm SL. Juvenile A. shackletoni had a heavily pigmented body except for the ventral side of the abdomen and the anal fin base. The proximal part of the dorsal fin and most of the anal fin were covered with melanophores. Although knowledge of larval and juvenile Artedidraco species is limited, the distribution of melanophores on the fins, pectoral fin base and caudal peduncle at each developmental stage may be useful for species identification.     

The <Emphasis Type="Italic">Caenorhabditis</Emphasis><Emphasis Type="Italic">briggsae</Emphasis> genome contains active <Emphasis Type="Italic">CbmaT1</Emphasis> and <Emphasis Type="Italic">Tcb1</Emphasis> transposons

The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae.     

Comparison of Defense Body Movements of <Emphasis Type="Italic">Apis laboriosa</Emphasis>, <Emphasis Type="Italic">Apis dorsata dorsata</Emphasis> and <Emphasis Type="Italic">Apis dorsata breviligula</Emphasis> Honey Bees

Defense behavior of three, free living giant (Megapis) honey bee subspecies, Apis laboriosa, A. dorsata dorsata and A. dorsata breviligula, was compared. Disturbed worker bees responded with characteristic dorso-ventral defense body twisting (DBT). Workers of A. laboriosa twisted the thorax by 55°, and the two other A. dorsata subspecies by about 10° more. A. laboriosa workers raised the tip of the abdomen by 90° and workers of the two other bee subspecies by about 20° higher. Differences in those traits were highly significant between A. laboriosa and both A. dorsata subspecies, but were not significant between those two subspecies. The whole cycle of DBT was the most vigorous in A. d. breviligula (0.11 s), and it was twice as vigorous as in A. d. dorsata (0.26 s) and trice as in A. laboriosa (0.32 s). A. laboriosa twisted the body together with wings folded over the abdomen, while the two A. dorsata subspecies raised the abdomen between spread wings. This supports the opinion to treat A. laboriosa as a separate species. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.