[³H]Fructose and [³H]glucose transport weredetermined in brush-border membrane vesicles (BBMV), basolateral membranevesicles (BLMV) and isolated cells (E, R, F, B) of H. americanus(Atlantic lobster) hepatopancreas. Glucose transport in BBMV was equilibrativein the absence of sodium and concentrative in the presence of sodium.Sodium-dependent glucose transport by BBMV was not inhibited by a tenfoldmolar excess of fructose. Glucose transport by BLMV was equilibrative andsodium independent. Fructose uptake by BBMV and BLMV was equilibrative in theabsence of sodium and concentrative in the presence of sodium. Thisenhancement was not affected by a tenfold molar excess of glucose in thepresence of sodium. E-, F- and B-cells showed sodium-dependent uptake offructose, while R-cells did not. Sodium-dependent fructose uptake by E-cellswas not inhibited by a tenfold molar excess of glucose or mannose. Westernblot analysis of BBMV, BLMV and E-, R-, F- and B-cells using rabbit polyclonalantibodies directed against epitopes of mammalian GLUT2, GLUT5, SGLT1 andSGLT4 indicated the...]]> Journal of Experimental Biology recent issues http://www.springerlink.com/content/n41h5u1ux445q483/ <p class="abstract"><div class="Abstract"><a name="Abs1"></a><span class="AbstractHeading">Abstract&nbsp;&nbsp;</span>Lane snappers (<i>Lutjanus synagris</i>), sampled from eight localities in the northern Gulf of Mexico (Gulf) and one locality along the Atlantic coast of Florida, were assayed for allelic variation at 14 nuclear-encoded microsatellites and for sequence variation in a 590 base-pair fragment of the mitochondrially encoded ND-4 gene (mtDNA). Significant heterogeneity among the nine localities in both microsatellite allele and genotype distributions and mtDNA haplotype distributions was indicated by exact tests and by analysis of molecular variance (AMOVA). Exact tests between pairs of localities and spatial analysis of molecular variance (SAMOVA) for both microsatellites and mtDNA revealed two genetically distinct groups: a Western Group that included six localities from the northwestern and northcentral Gulf and an Eastern Group that included three localities, one from the west coast of Florida, one from the Florida Keys, and one from the east (Atlantic) coast of Florida. The between-groups component of molecular variance was significant for both microsatellites (<i>Φ</i> _CT&nbsp;=&nbsp;0.016, <i>P</i>&nbsp;=&nbsp;0.009) and mtDNA (<i>Φ</i> _CT&nbsp;=&nbsp;0.208, <i>P</i>&nbsp;=&nbsp;0.010). Exact tests between pairs of localities within each group and spatial autocorrelation analysis did not reveal genetic heterogeneity or an isolation-by-distance effect among localities within either group. MtDNA haplotype diversity was significantly less (<i>P</i>&nbsp;&lt;&nbsp;0.0001) in the Western Group than in the Eastern Group; microsatellite allelic richness and gene diversity also were significantly less in the Western Group (<i>P</i>&nbsp;=&nbsp;0.015 and 0.013, respectively). The difference in genetic variability between the two groups may reflect reduced effective population size in the Western Group and/or asymmetric rates of genetic migration. The relative difference in variability between the two groups was substantially greater in mtDNA and may reflect one or more mtDNA selective sweeps; tests of neutrality of the mtDNA data were consistent with this possibility. Bayesian analysis of genetic demography indicated that both groups have experienced a historical decline in effective population size, with the decline being greater in the Western Group. Maximum-likelihood analysis of microsatellite data indicated significant asymmetry in average, long-term migration rates between the two groups, with roughly twofold greater migration from the Western Group to the Eastern Group. The difference in mtDNA variability and the order-of-magnitude difference in genetic divergence between mtDNA and microsatellites may reflect different demographic events affecting mtDNA disproportionately and/or a sexual and/or spatial bias in gene flow and dispersal. The spatial discontinuity among lane snappers in the region corresponds to a known zone of vicariance in other marine species. The evidence of two genetically distinct groupings (stocks) has implications for management of lane snapper resources in the northern Gulf. </div></p><ul><li><span class="labelName">Content Type </span><span class="labelValue">Journal Article</span></li><li>Category Original Paper</li><li>DOI 10.1007/s00227-009-1217-y</li><li><span class="labelName">Authors</span><ul><li>S. Karlsson, Texas A&M University Center for Biosystematics and Biodiversity College Station TX 77843-2258 USA</li><li>E. Saillant, Texas A&M University Center for Biosystematics and Biodiversity College Station TX 77843-2258 USA</li><li>J. R. Gold, Texas A&M University Center for Biosystematics and Biodiversity College Station TX 77843-2258 USA</li></ul></li></ul><ul class="parents"><ul class="details"><li><span class="header labelName">Journal </span><span class="labelValue"><a href="http://www.springerlink.com/content/100441/">Marine Biology</a></span></li><li><span class="labelName">Online ISSN </span><span class="labelValue">1432-1793</span></li><li><span class="labelName">Print ISSN </span><span class="labelValue">0025-3162</span></li></ul></ul> Marine Biology http://www.bioone.org/doi/abs/10.1562/2006-01-14-RA-775?ai=vj&af=R Photochemistry and Photobiology, Volume 82, Issue 6, Page 1468-1474, November 2006. <br/> BioOne: Photochemistry and Photobiology http://www.sciencedirect.com/science?_ob=GatewayURL&_origin=IRSSSEARCH&_method=citationSearch&_piikey=S0012160609005648&_version=1&md5=a9194f1e578bc4409abd536f45be1bd8 Publication year: 2009<br><b>Source:</b> Developmental Biology, In Press, Accepted Manuscript, Available online 8 May 2009<br>Patrick, Lemaire<br><br>Ascidians were historically the first metazoans in which experimental embryology was carried out. These early works by Chabry and Conklin, in particular, led to the idea that the developmental programme of these animals was driven by the cell autonomous inheritance of localised maternal determinants, rendered precise by the stereotyped pattern of invariant cell cleavages. Work in the past 20 years indeed identified several localised maternal determinants of the position of cleavage planes or of some early cell fates. The overwhelming majority of cells in the three germ layers, however, do not follow a cell-autonomous differentiation program. Instead, they respond to... ScienceDirect Search: species http://www.eurekalert.org/pub_releases/2009-05/cp-gm043009.php By lending them a gene normally reserved for other classes of animals, researchers have shown they can rescue flies from their Parkinson's-like symptoms, including movement defects and excess free radicals produced in power-generating cellular components called mitochondria. The gene swap also protects healthy flies' mitochondria, and to a large extent the flies themselves, from the damaging effects of cyanide and other toxins. EurekAlert! - Breaking News http://www.springerlink.com/content/gnw168075626n4p2/ <p class="abstract"><div class="Abstract"><a name="Abs1"></a><span class="AbstractHeading">Abstract&nbsp;&nbsp;</span>Although individuals in many fish species move to shallow waters to spawn, the California grunion (<i>Leuresthes tenuis)</i> is almost unique in its constitutive display of synchronous full-emergence beach spawning. During a spawning event, fish ride large waves onshore to spawn on beach land, where their eggs incubate terrestrially. Here, we employ molecular markers to ascertain how this unusual reproductive behavior impacts genetic parentage. We developed and utilized four highly polymorphic microsatellite markers to assess maternal and paternal contributions in a total of 682 progeny from 17 nests of a natural population of <i>L. tenuis</i>. Alleles deduced to be of paternal origin in progeny were used to determine the minimum number of sires per nest and to estimate the true number of sires per nest via Bayesian analysis. We document the following: (a) no instances of multiple maternity for progeny within a nest; (b) a high frequency of nests (88%) with multiple paternity; and (c) an appreciable fraction of nests (18%) in which the estimated number of genetic sires (as many as nine) proved to be greater than the observed number of male attendants, thus implicating occasional extra-group fertilization events. From these and other observations, we also conclude that spawning behavior in grunions may involve site choice but not explicit mate choice. In addition to providing the first analysis of molecular parentage in a beach-spawning fish, we compare our findings to those reported previously for a beach-spawning arthropod, and we discuss the forces that may be maintaining this peculiar reproductive behavior. </div></p><ul><li><span class="labelName">Content Type </span><span class="labelValue">Journal Article</span></li><li>Category Original Paper</li><li>DOI 10.1007/s00227-009-1203-4</li><li><span class="labelName">Authors</span><ul><li>Rosemary J. Byrne, University of California, Irvine Department of Ecology and Evolutionary Biology 321 Steinhaus Hall Irvine CA 92697-2525 USA</li><li>John C. Avise, University of California, Irvine Department of Ecology and Evolutionary Biology 321 Steinhaus Hall Irvine CA 92697-2525 USA</li></ul></li></ul><ul class="parents"><ul class="details"><li><span class="header labelName">Journal </span><span class="labelValue"><a href="http://www.springerlink.com/content/100441/">Marine Biology</a></span></li><li><span class="labelName">Online ISSN </span><span class="labelValue">1432-1793</span></li><li><span class="labelName">Print ISSN </span><span class="labelValue">0025-3162</span></li></ul></ul> Marine Biology http://www.sciencedirect.com/science?_ob=GatewayURL&_origin=IRSSSEARCH&_method=citationSearch&_piikey=S0022098109001373&_version=1&md5=4450927a5a729d1ad1a06a3a85b244f2 Publication year: 2009<br><b>Source:</b> Journal of Experimental Marine Biology and Ecology, In Press, Corrected Proof, Available online 1 May 2009<br>Evie A., Wieters , Emilie, Salles , Stella M., Januario , Sergio A., Navarrete<br><br>Many invertebrates avoid predation risk by seeking and defending refuges that can be in limited supply, producing strong intra- and inter-specific interference competition. Previous experimental studies in central Chile demonstrated that interference competition for refuges is the primary factor driving habitat segregation between the predatory crabs Acanthocyclus gayi and A. hassleri, with the latter species monopolizing galleries inside mussel beds in the mid intertidal zone and limiting A. gayi to rock crevices. Yet, habitat partitioning between rival species can result from differences in habitat preferences and not solely from interference interactions. Moreover, since A. gayi is also known to shelter... ScienceDirect Search: species http://www.springerlink.com/content/d567620372163712/ <p class="abstract"><div class="Abstract"><a name="Abs1"></a><span class="AbstractHeading">Abstract&nbsp;&nbsp;</span>The energetic cost of spawning and the endogenous factors that modulate spawning could modify escape response performance, leading to a conflict between the requirements of two fundamental components of fitness: reproduction and survival. We examined whether spawning changed force production during escape responses by the functionally hermaphroditic scallop, <i>Argopecten purpuratus,</i> and whether the response of smooth (tonic) and striated (phasic) muscles differed. Force production during escape responses by mature scallops was compared before induction of spawning, during spawning and after completion of spawning. Maximum tonic force and the area under the force curve (total force recorded) were diminished during gamete release, whereas phasic force production (maximum and mean force) increased after spawning was completed. The number and frequency of phasic contractions did not change during the spawning process, suggesting that spawning did not limit fuel availability for phasic contractions. The decrease in tonic force during spawning and the increased phasic force production after spawning may reflect changes in monoamine levels during gamete release. Whereas the spawning process modified force production during escape responses, the changes would, if anything, enhance escape performance during an initial encounter between a scallop and a predatory sea star. </div></p><ul><li><span class="labelName">Content Type </span><span class="labelValue">Journal Article</span></li><li>Category Original Paper</li><li>DOI 10.1007/s00227-009-1194-1</li><li><span class="labelName">Authors</span><ul><li>Hernan Mauricio Pérez, Université Laval Département de Biologie Québec QC G1K 7P4 Canada</li><li>Katherina B. Brokordt, Universidad Católica del Norte Center for Advanced Studies in Arid Zones (CEAZA), Facultad de Ciencias del Mar Larrondo 1281 Coquimbo Chile</li><li>Gloria Martínez, Universidad Católica del Norte Departamento de Biología Marina Larrondo 1281 Coquimbo Chile</li><li>Helga Guderley, Université Laval Département de Biologie Québec QC G1K 7P4 Canada</li></ul></li></ul><ul class="parents"><ul class="details"><li><span class="header labelName">Journal </span><span class="labelValue"><a href="http://www.springerlink.com/content/100441/">Marine Biology</a></span></li><li><span class="labelName">Online ISSN </span><span class="labelValue">1432-1793</span></li><li><span class="labelName">Print ISSN </span><span class="labelValue">0025-3162</span></li></ul></ul> Marine Biology http://www.sciencedirect.com/science?_ob=GatewayURL&_origin=IRSSCONTENT&_method=citationSearch&_piikey=S0168159109000999&_version=1&md5=71682b798549efeb2d837fa0919d5907 Publication year: 2009<br><b>Source:</b> Applied Animal Behaviour Science, In Press, Corrected Proof, Available online 9 April 2009<br>Sandie, Millot , Marie-Laure, Bégout , Béatrice, Chatain<br><br>Domestication and selection may affect fish behaviour, sometime as soon as at the first generation of domestication. However, knowledge about how both processes impact on fish spatial exploration and swimming activity still is to be improved. The objective of this experiment was (i) to evaluate spatial exploration behaviour and swimming activities of three sea bass strains having different domestication and selection levels and (ii) to analyse their responses to an acute stress. Sea bass exploration and swimming activities were studied before, during and 40min after a stimulation (standardized fall of an object). The experimental tank was divided in to four... ScienceDirect Publication: Applied Animal Behaviour Science http://www.ingentaconnect.com/content/bsc/ejb/2009/00000276/00000009/art00010 European Journal of Biochemistry http://www.sciencedirect.com/science?_ob=GatewayURL&_origin=IRSSCONTENT&_method=citationSearch&_piikey=S104996440900084X&_version=1&md5=713fc75ef1523c9a21765f7387fcf974 Publication year: 2009<br><b>Source:</b> Biological Control, In Press, Accepted Manuscript, Available online 31 March 2009<br>Cheryl L., Lennox , John H., Hoffmann , Teresa A., Coutinho , Alain, Roques<br><br>Biological control of invasive pine trees in South Africa was first mooted in 1977. Preliminary investigations, starting in 1997, identified two priority target species, Pinus pinaster and P.halepensis, which are not commercially important forestry species in South Africa, thus diminishing prospects for conflict of interests. Both targets are native to Europe where, until recently, pitch canker (Fusarium circinatum), was known not to occur. From the outset, cone- or seed-destroying insects were preferred as agents because, if successful, they could reduce the fecundity, density and aggressiveness (spread) of the invasive pines while not reducing their commercial value. From several potential species... ScienceDirect Publication: Biological Control http://www.sciencedirect.com/science?_ob=GatewayURL&_origin=IRSSCONTENT&_method=citationSearch&_piikey=S0044848609002786&_version=1&md5=b1c9f0c46afa5cc1bda23da162214ff5 Publication year: 2009<br><b>Source:</b> Aquaculture, In Press, Accepted Manuscript, Available online 31 March 2009<br>Victoria K., Gibbs , Stephen A., Watts , Addison L., Lawrence , John M., Lawrence<br><br>To facilitate sea urchin aquaculture, nutritionally-complete feeds are being developed for a number of species. In this study, the effects of dietary phospholipids from soy lecithin on weight gain and production were investigated to ascertain a potential dietary requirement for small juvenile sea urchins, Lytechinus variegatus. Laboratory-produced juvenile L. variegatus (n=16 per treatment, average 0.091 g±0.01 SE wet weight and 5.80 mm±0.09 SE diameter) were fed semi-purified formulated diets supplemented with 1, 2.5, 4, 5.2, 6.4, 7.6, or 8.8% phospholipids (as fed) from soy lecithin for 12 weeks. Under the conditions of this study, a negative correlation between dietary phospholipid level and weight... ScienceDirect Publication: Aquaculture http://www.sciencedirect.com/science?_ob=GatewayURL&_origin=IRSSCONTENT&_method=citationSearch&_piikey=S0044848609002762&_version=1&md5=4dcdd0ed8a5c00287bdba10ffbd76bd2 Publication year: 2009<br><b>Source:</b> Aquaculture, In Press, Accepted Manuscript, Available online 31 March 2009<br>C.P., Dumont , J.D., Urriago , A., Abarca , C.F., Gaymer , M., Thiel<br><br>Scallop aquaculture in Chile suffers from intense fouling on culture facilities by invasive species such as the ascidian Ciona intestinalis and the bryozoan Bugula neritina. We examined the grazing effect of the rock shrimp Rhynchocinetes typus on fouling species, which colonize scallop pearl nets. We placed different densities of shrimp (0, 2, 5 and 10 individuals) in pearl nets with juvenile scallops (mean shell height 4.9 cm) at Tongoy Bay in northern-central Chile. We sampled the nets after four months (January – May 2007) and recovered 35 to 50% of the shrimp from the different treatments. The nets with 10 initial... ScienceDirect Publication: Aquaculture http://jeb.biologists.org/cgi/content/short/212/8/1140?rss=1 Patsy S. Dickinson, Teerawat Wiwatpanit, Emily R. Gabranski, Rachel J. Ackerman, Jake S. Stevens, Christopher R. Cashman, Elizabeth A. Stemmler, and Andrew E. Christie

The allatostatins comprise three structurally distinct peptide familiesthat regulate juvenile hormone production by the insect corpora allata. A-typefamily members contain the C-terminal motif –YXFGLamide andhave been found in species from numerous arthropod taxa. Members of the B-typefamily exhibit a –WX₆Wamide C-terminus and, like theA-type peptides, appear to be broadly conserved within the Arthropoda. Bycontrast, members of the C-type family, typified by the unblocked C-terminus–PISCF, a pyroglutamine blocked N-terminus, and a disulfide bridgebetween two internal Cys residues, have only been found in holometabolousinsects, i.e. lepidopterans and dipterans. Here, using transcriptomics, wehave identified SYWKQCAFNAVSCFamide (disulfide bridging predicted between thetwo Cys residues), a known honeybee and water flea C-type-like peptide, fromthe American lobster Homarus americanus (infraorder Astacidea). Usingmatrix assisted laser desorption/ionization Fourier transform massspectrometry (MALDI-FTMS), a mass corresponding to that of SYWKQCAFNAVSCFamidewas detected in the H. americanus brain, supporting the existence ofthis peptide and its theorized structure. Furthermore, SYWKQCAFNAVSCFamide wasdetected by MALDI-FTMS in...]]> Journal of Experimental Biology recent issues http://www.springerlink.com/content/ljx1jxl857580221/ <p class="abstract"><div class="Abstract"><a name="Abs1"></a><span class="AbstractHeading">Abstract&nbsp;&nbsp;</span>Eye development, optical properties and photomechanical responses were examined in embryos and hatchlings of the southern calamary, <i>Sepioteuthis australis</i>. This species occurs in shallow coastal waters in Australia and New Zealand, and the egg masses were collected in October and December 2004 from Great Oyster Bay, Tasmania. At the earliest developmental stage the eye of the squid was comprised of a hemispherical cup of undifferentiated neural retina, while presumptive iris cell layers and lentigenic precursor cells enclosed a posterior eye chamber. Differentiation of the proximal and distal processes was observed in correspondence with the cornea development and lens crystallization, and occurred before differentiation of the neural retina, which was complete prior to hatching. Longer photoreceptor distal processes were first observed just prior to hatching in the dorsal-posterior retina. After hatching, this difference was much more evident and higher photoreceptor density was found in the central retina. This indicates that the eye of <i>S. australis</i> at this age uses different retina areas for different visual tasks. Optical sensitivity and resolution suggest that juvenile <i>S. australis</i> are diurnal. This study also found functional photomechanical responses of visual screening pigment migration and pupil constriction in <i>S. australis</i> embryos, although complete functionality of the pupil at this stage was uncertain. However, the pupils of squid aged 2&nbsp;days closed almost completely under bright conditions, showing that photomechanical responses were highly developed in the juvenile squid. These findings indicate that squid embryos are able to perceive visual stimulation, suggesting an early reliance on vision for survival after hatching. </div></p><ul><li><span class="labelName">Content Type </span><span class="labelValue">Journal Article</span></li><li>Category Original Paper</li><li>DOI 10.1007/s00227-009-1177-2</li><li><span class="labelName">Authors</span><ul><li>Anna Bozzano, Institut de Ciències del Mar (CSIC) Passeig Marítim de la Barceloneta 37-49 08003 Barcelona Spain</li><li>Patricia M. Pankhurst, James Cook University School of Marine and Tropical Biology Townsville QLD 4811 Australia</li><li>Natalie A. Moltschaniwskyj, University of Tasmania National Centre for Marine Conservation and Resource Sustainability, Australian Maritime College Locked Bag 1370 Launceston TAS 7250 Australia</li><li>Roger Villanueva, Institut de Ciències del Mar (CSIC) Passeig Marítim de la Barceloneta 37-49 08003 Barcelona Spain</li></ul></li></ul><ul class="parents"><ul class="details"><li><span class="header labelName">Journal </span><span class="labelValue"><a href="http://www.springerlink.com/content/100441/">Marine Biology</a></span></li><li><span class="labelName">Online ISSN </span><span class="labelValue">1432-1793</span></li><li><span class="labelName">Print ISSN </span><span class="labelValue">0025-3162</span></li></ul></ul> Marine Biology http://www.sciencedirect.com/science?_ob=GatewayURL&_origin=IRSSSEARCH&_method=citationSearch&_piikey=S001664800900118X&_version=1&md5=24931e1ccdd519d8b2dcc4074ba4f9a9 Publication year: 2009<br><b>Source:</b> General and Comparative Endocrinology, In Press, Accepted Manuscript, Available online 28 March 2009<br>By J. Sook, Chung , Sarah, Bembe , Sherry, Tamone , Ebony, Andrews , Heidy, Thomas<br><br>Crustacean hyperglycemic hormone (CHH) secreted from sinus glands primarily elicits hyperglycemia in crustaceans. CHH is particularly important for energy metabolism during environmental and physiological stress as animals switch to anaerobiosis. CHH has been purified from multiple brachyuran crab species to date, but not from the cold water Tanner crab, Chionoecetes bairdi, a species found in Alaskan coastal waters. The purpose of molecular cloning the C. bairdi CHH precursor and identification of its neuropeptide form in sinus glands is to establish tools to further study cold water crab metabolic physiology. Cold water crabs such as those in the genus Chionoecetes are... ScienceDirect Search: species http://www.sciencedirect.com/science?_ob=GatewayURL&_origin=IRSSCONTENT&_method=citationSearch&_piikey=S0003347209001067&_version=1&md5=7b2d9141dd502c2d897a84b47f20b166 Publication year: 2009<br><b>Source:</b> Animal Behaviour, In Press, Corrected Proof, Available online 27 March 2009<br>Gareth, Arnott , Robert W., Elwood<br><br>Selection should favour accurate information gathering regarding the likely costs and benefits of continued conflict. Here we consider how variation in the abilities of contestants to assess resource-holding potential (RHP) influences fights. This has been examined in various game theory models. However, discriminating between assessment strategies has proven difficult and has resulted in confusion. To add clarity, we group existing models into three main types that differ in the information about RHP that contestants are presumed to gather: (1) pure self-assessment, (2) cumulative assessment and (3) mutual assessment. Within this framework we outline methods advocated to discriminate successfully between the... ScienceDirect Publication: Animal Behaviour http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?tmpl=NoSidebarfile&db=PubMed&cmd=Retrieve&list_uids=19088089&dopt=Abstract&itool=rss Related Articles

Gene regulatory networks underlying the compartmentalization of the Ciona central nervous system.

Development. 2009 Jan;136(2):285-93

Authors: Imai KS, Stolfi A, Levine M, Satou Y

The tripartite organization of the central nervous system (CNS) may be an ancient character of the bilaterians. However, the elaboration of the more complex vertebrate brain depends on the midbrain-hindbrain boundary (MHB) organizer, which is absent in invertebrates such as Drosophila. The Fgf8 signaling molecule expressed in the MHB organizer plays a key role in delineating separate mesencephalon and metencephalon compartments in the vertebrate CNS. Here, we present evidence that an Fgf8 ortholog establishes sequential patterns of regulatory gene expression in the developing posterior sensory vesicle, and the interleaved ;neck' region located between the sensory vesicle and visceral ganglion of the simple chordate Ciona intestinalis. The detailed characterization of gene networks in the developing CNS led to new insights into the mechanisms by which Fgf8/17/18 patterns the chordate brain. The precise positioning of this Fgf signaling activity depends on an unusual AND/OR network motif that regulates Snail, which encodes a threshold repressor of Fgf8 expression. Nodal is sufficient to activate low levels of the Snail repressor within the neural plate, while the combination of Nodal and Neurogenin produces high levels of Snail in neighboring domains of the CNS. The loss of Fgf8 patterning activity results in the transformation of hindbrain structures into an expanded mesencephalon in both ascidians and vertebrates, suggesting that the primitive MHB-like activity predates the vertebrate CNS.

PMID: 19088089 [PubMed - indexed for MEDLINE]

The complete mitochondrial genome of the house dust mite, Dermatophagoides pteronyssinus (Trouessart): a novel gene arrangement among arthropods.

BMC Genomics. 2009 Mar 13;10(1):107

Authors: Dermauw W, Van Leeuwen T, Vanholme B, Tirry L

ABSTRACT: BACKGROUND: The apparent scarcity of available sequence data has greatly impeded evolutionary studies in Acari (mites and ticks). This subclass encompasses over 48,000 species and forms the largest group within the Arachnida. Although mitochondrial genomes are widely utilised for phylogenetic and population genetic studies, only 20 mitochondrial genomes of Acari have been determined, of which only one belongs to the diverse order of the Sarcoptiformes. In this study, we describe the mitochondrial genome of the European house dust mite Dermatophagoides pteronyssinus, the most important member of this largely neglected group. RESULTS: The mitochondrial genome of D. pteronyssinus is a circular DNA molecule of 14,203bp. It contains the complete set of 37 genes (13 protein coding genes, 2 rRNA genes and 22 tRNA genes), usually present in metazoan mitochondrial genomes. The mitochondrial gene order differs considerably from that of other Acari mitochondrial genomes. Compared to the mitochondrial genome of Limulus polyphemus, considered as the ancestral arthropod pattern, only 11 of the 38 gene boundaries are conserved. The majority strand has a 72.6% AT-content but a GC-skew of 0.194. This skew is the reverse of that normally observed for typical animal mitochondrial genomes. A microsatellite was detected in a large non-coding region (286bp), which probably functions as the control region. Almost all tRNA genes lack a T-arm, provoking the formation of canonical cloverleaf tRNA-structures, and both rRNA genes are considerably reduced in size. Finally, the genomic sequence was used to perform a phylogenetic study. Both maximum likelihood and Bayesian inference analysis clustered D. pteronyssinus with Steganacarus magnus, forming a sistergroup of the Trombidiformes. CONCLUSIONS: Although the mitochondrial genome of D. pteronyssinus shares different features with previously characterised Acari mitochondrial genomes, it is unique in many ways. Gene order is extremely rearranged and represents a new pattern within the Acari. Both tRNAs and rRNAs are truncated, corroborating the theory of the functional co-evolution of these molecules. Furthermore, the strong and reversed GC- and AT-skews suggest the inversion of the control region as an evolutionary event. Finally, phylogenetic analysis using concatenated mt gene sequences succeeded in recovering Acari relationships concordant with traditional views of phylogeny of Acari.

PMID: 19284646 [PubMed - as supplied by publisher]

Phylogenetic conservation of cytostatic factor related genes in the ascidian Ciona intestinalis.

Gene. 2009 Jan 15;429(1-2):104-11

Authors: Russo GL, Bilotto S, Ciarcia G, Tosti E

In all vertebrates, mature oocytes arrest at the metaphase of the II meiotic division, while some invertebrates arrest at metaphase-I, others at prophase-I. Fertilization induces completion of meiosis and entry into the first mitotic division. Several experimental models have been considered from both vertebrates and invertebrates in order to shed light on the peculiar aspects of meiotic division, such as the regulation of the cytostatic factor (CSF) and the maturation promoting factor (MPF) in metaphase I or II. Recently, we proposed the oocytes of ascidian Ciona intestinalis as a new model to study the meiotic division. Here, taking advantage of the recent publication of the C. intestinalis genome, we presented a phylogenetic analysis of key molecular components of the CSF-related machinery. We showed that the Mos/MAP kinase pathway is perfectly conserved in ascidians. We demonstrated the presence of a CSF-like activity in metaphase-I arrested C. intestinalis oocytes able to block cell division in two-cell embryos. We further investigated the regulation of CSF by demonstrating that both CSF and MPF inactivation, at the exit of metaphase-I, are independent from protein synthesis, indicating the absence of short-lived factors that regulate metaphase stability, as in other invertebrate species. The results obtained suggest that meiotic regulation in C. intestinalis resembles that of vertebrates, such as Xenopus accordingly to the position of this organism in the evolutionary tree.

PMID: 18977421 [PubMed - indexed for MEDLINE]