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Putative Homology (putative + homology)

Distribution by Scientific Domains
Life Sciences100%

Selected Abstracts

Conservation of arthropod midline netrin accumulation revealed with a cross-reactive antibody provides evidence for midline cell homology

EVOLUTION AND DEVELOPMENT, Issue 3 2009
Wendy Simanton
SUMMARY Although many similarities in arthropod CNS development exist, differences in axonogenesis and the formation of midline cells, which regulate axon growth, have been observed. For example, axon growth patterns in the ventral nerve cord of Artemia franciscana differ from that of Drosophila melanogaster. Despite such differences, conserved molecular marker expression at the midline of several arthropod species indicates that midline cells may be homologous in distantly related arthropods. However, data from additional species are needed to test this hypothesis. In this investigation, nerve cord formation and the putative homology of midline cells were examined in distantly related arthropods, including: long- and short-germ insects (D. melanogaster, Aedes aeygypti, and Tribolium castaneum), branchiopod crustaceans (A. franciscana and Triops longicauditus), and malacostracan crustaceans (Porcellio laevis and Parhyale hawaiensis). These comparative analyses were aided by a cross-reactive antibody generated against the Netrin (Net) protein, a midline cell marker and regulator of axonogenesis. The mechanism of nerve cord formation observed in Artemia is found in Triops, another branchiopod, but is not found in the other arthropods examined. Despite divergent mechanisms of midline cell formation and nerve cord development, Net accumulation is detected in a well-conserved subset of midline cells in branchiopod crustaceans, malacostracan crustaceans, and insects. Notably, the Net accumulation pattern is also conserved at the midline of the amphipod P. hawaiensis, which undergoes split germ-band development. Conserved Net accumulation patterns indicate that arthropod midline cells are homologous, and that Nets function to regulate commissure formation during CNS development of Tetraconata. [source]

Analysis of expressed sequence tags for Frankliniella occidentalis, the western flower thrips

INSECT MOLECULAR BIOLOGY, Issue 4 2010
D. Rotenberg
Abstract Thrips are members of the insect order Thysanoptera and Frankliniella occidentalis (the western flower thrips) is the most economically important pest within this order. F. occidentalis is both a direct pest of crops and an efficient vector of plant viruses, including Tomato spotted wilt virus (TSWV). Despite the world-wide importance of thrips in agriculture, there is little knowledge of the F. occidentalis genome or gene functions at this time. A normalized cDNA library was constructed from first instar thrips and 13 839 expressed sequence tags (ESTs) were obtained. Our EST data assembled into 894 contigs and 11 806 singletons (12 700 nonredundant sequences). We found that 31% of these sequences had significant similarity (E, 10,10) to protein sequences in the National Center for Biotechnology Information nonredundant (nr) protein database, and 25% were functionally annotated using Blast 2GO. We identified 74 sequences with putative homology to proteins associated with insect innate immunity. Sixteen sequences had significant similarity to proteins associated with small RNA-mediated gene silencing pathways (RNA interference; RNAi), including the antiviral pathway (short interfering RNA-mediated pathway). Our EST collection provides new sequence resources for characterizing gene functions in F. occidentalis and other thrips species with regards to vital biological processes, studying the mechanism of interactions with the viruses harboured and transmitted by the vector, and identifying new insect gene-centred targets for plant disease and insect control. [source]

Localization and connectivity of the lateral amygdala in anuran amphibians

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 2 2004
Nerea Moreno
Abstract On the basis of chemoarchitecture and gene expression patterns in the amphibian amygdaloid complex, new subdivisions have been proposed and compared with their counterparts in amniotes. Thus, a portion of the ventral pallium of anurans has been tentatively named "lateral amygdala" (LA) and compared with the basolateral complex of mammals. To strengthen the putative homology, we have analyzed the pattern of afferent and efferent connections of the LA in the anurans Rana perezi and Xenopus laevis. Tract-tracing techniques with dextran amines were used under in vivo and in vitro conditions. The results showed important connections with the main olfactory bulb, via the lateral olfactory tract. In addition, abundant intratelencephalic connections, via the rostral branch of the stria terminalis, were revealed, involving mainly the basal ganglia, septal nuclei, bed nucleus of the stria terminalis, and especially other amygdaloid nuclei. Nontelencephalic connections were found from the dorsal thalamus and parabrachial area and, in particular, from the hypothalamus through the caudal branch of the stria terminalis. All these results strongly suggest that the LA in anurans is a multimodal area in the ventral pallium that shares many hodological features with the amygdaloid ventropallial derivatives of the basolateral complex of amniotes. J. Comp. Neurol. 479:130,148, 2004. © 2004 Wiley-Liss, Inc. [source]

Redescription of Dixella humeralis (Tonnoir) with notes on the immature stages (Diptera: Dixidae)

AUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 4 2004
Joshua R Ogawa
Abstract The adult male of Dixella humeralis is redescribed and adult female and immature life stages are described for the first time. Originally described from the Blue Mountains, New South Wales, the current range is extended to include the pasture lands of the Dorrigo Plateau. Larval and pupal chaetotaxy are illustrated and their putative homology with the Culicidae is discussed. Adult and larval characters are presented that separate the known endemic Australian Dixella species. [source]