Unusual conservation of mitochondrial gene order in Crassostrea oysters: evidence for recent speciation in Asia

<p>Abstract</p> <p>Background</p> <p>Oysters are morphologically plastic and hence difficult subjects for taxonomic and evolutionary studies. It is long been suspected, based on the extraordinary species diversity observed, that Asia Pacific is the epicenter of oyster speciation. To understand the species diversity and its evolutionary history, we collected five <it>Crassostrea </it>species from Asia and sequenced their complete mitochondrial (mt) genomes in addition to two newly released Asian oysters (<it>C. iredalei </it>and <it>Saccostrea mordax</it>) for a comprehensive analysis.</p> <p>Results</p> <p>The six Asian <it>Crassostrea </it>mt genomes ranged from 18,226 to 22,446 bp in size, and all coded for 39 genes (12 proteins, 2 rRNAs and 25 tRNAs) on the same strand. Their genomes contained a split of the <it>rrnL </it>gene and duplication of <it>trnM</it>, <it>trnK </it>and <it>trnQ </it>genes. They shared the same gene order that differed from an Atlantic sister species by as many as nine tRNA changes (6 transpositions and 3 duplications) and even differed significantly from <it>S. mordax </it>in protein-coding genes. Phylogenetic analysis indicates that the six Asian <it>Crassostrea </it>species emerged between 3 and 43 Myr ago, while the Atlantic species evolved 83 Myr ago.</p> <p>Conclusions</p> <p>The complete conservation of gene order in the six Asian <it>Crassostrea </it>species over 43 Myr is highly unusual given the remarkable rate of rearrangements in their sister species and other bivalves. It provides strong evidence for the recent speciation of the six <it>Crassostrea </it>species in Asia. It further indicates that changes in mt gene order may not be strictly a function of time but subject to other constraints that are presently not well understood.</p

Sub-inertial characteristics of the surface flow field over the shelf of the central Mid-Atlantic Bight

Observations of surface velocity data from August 2002 to February 2004 were collected by a series of four long-range high-frequency (HF) radars along the coast of New Jersey. The shelf observations of the central Mid-Atlantic Bight (MAB) were compared to historical observations of surface flow characteristics in the area. The time-averaged spatial mean velocity of 4 cm/s in the down-shelf along-shelf direction and 3 cm/s in the offshore across-shelf direction compared very well to historical surface measurements in the study region. However, as the spatial resolution of the data set revealed, this simple measure masked significant spatial variations in the overall and seasonal mean flow structures. Three regions-the south bank of the Hudson Shelf Valley, the southern New Jersey inner shelf (LEO-15) region, and the region offshore of the Delaware Baymouth (southwest corner) - had mean flows that favor offshore transport of surface water. In terms of temporal variability, maps of the principle axes showed that the across-shelf (minor) axis contribution was not in significant in the surface layer ranging from 0.3 to 0.9 of along-shelf (major) axis and that there were seasonal differences in orientation and ellipticity. Analysis of the spatial changes in the temporal and spatial correlation scales over the shelf showed that shelf position, in addition to site separation, contributed to the differences in these properties. Furthermore, observations over the Hudson Shelf Valley region suggested that this was a region of transition in which the orientation of along- and across-shelf components begin to change. (C) 2009 Elsevier Ltd. All rights reserved

A Proposal to Search for Charmed Particle Production Near Threshold

We propose to search for charmed particle production thresholds by looking for anomalies in the ratio of K{sup -}/{pi}{sup -} production at P{sub T} {approx} 1 GeV/c as the incident energy is varied. Any anomalous behavior will be further investigated using a two arm effective mass spectrometer

Properties of inclusive W, Z events in p p collisions at 1. 8 TeV

A preliminary measurement of the properties of W and Z production along with accompanying jets has been made in {anti p}p collisions at 1.8 TeV using the CDF detector at Fermilab. Distributions of jet multiplicity, and boson E{sub T}, with and without selection on jet multiplicity, were obtained. Agreement was found with perturbative QCD predictions