Potential efficacy of mitochondrial genes for animal DNA barcoding: a case study using eutherian mammals

<p>Abstract</p> <p>Background</p> <p>A well-informed choice of genetic locus is central to the efficacy of DNA barcoding. Current DNA barcoding in animals involves the use of the 5' half of the mitochondrial cytochrome oxidase 1 gene (<it>CO1</it>) to diagnose and delimit species. However, there is no compelling <it>a priori </it>reason for the exclusive focus on this region, and it has been shown that it performs poorly for certain animal groups. To explore alternative mitochondrial barcoding regions, we compared the efficacy of the universal <it>CO1 </it>barcoding region with the other mitochondrial protein-coding genes in eutherian mammals. Four criteria were used for this comparison: the number of recovered species, sequence variability within and between species, resolution to taxonomic levels above that of species, and the degree of mutational saturation.</p> <p>Results</p> <p>Based on 1,179 mitochondrial genomes of eutherians, we found that the universal <it>CO1 </it>barcoding region is a good representative of mitochondrial genes as a whole because the high species-recovery rate (> 90%) was similar to that of other mitochondrial genes, and there were no significant differences in intra- or interspecific variability among genes. However, an overlap between intra- and interspecific variability was still problematic for all mitochondrial genes. Our results also demonstrated that any choice of mitochondrial gene for DNA barcoding failed to offer significant resolution at higher taxonomic levels.</p> <p>Conclusions</p> <p>We suggest that the <it>CO1 </it>barcoding region, the universal DNA barcode, is preferred among the mitochondrial protein-coding genes as a molecular diagnostic at least for eutherian species identification. Nevertheless, DNA barcoding with this marker may still be problematic for certain eutherian taxa and our approach can be used to test potential barcoding loci for such groups.</p

Brazilian cave heritage under siege

info:eu-repo/semantics/publishe

STUDY OF SLOW MOTION OF WATER MOLECULES IN ROCHELLE SALT AND IN AMMONIUM ROCHELLE SALT BY SPIN-LATTICE RELAXATION OF PROTONS IN ROTATING FRAME

On mesure la dépendance en température et en fréquence du temps de relaxation spin-réseau des protons dans le sel de Rochelle et dans le sel de Rochelle ammonié. On étudie deux groupes de molécules d'eau, appelés par Bjorkstam [l] A, B, C, D et α, β, γ, δ ; on détermine le temps de corrélation τc pour les 2 groupes. On ne trouve pas de contribution des molécules d'eau à la ferroélectricité. Nos conclusions sont confirmées par nos mesures de T1r des protons dans le sel de Rochelle ammonié à 7,8 % molaire. On compare aux mesures diélectriques du sel de Rochelle à 298 °K.Temperature and frequency dependence of spin-lattice relaxation time in rotating frame T1r of protons in Rochelle salt and in ammonium Rochelle salt was measured. Two groups of water molecules, called by Bjorkstam [l] A, B, C, D and α, β, γ, δ water molecules were studied and the correlation time τc was determined for both groups. No direct contribution of water molecules to ferroelectric dipoles was found. Measurements of T1r of protons in 7.8 mol % ammonium Rochelle salt were performed to check our conclusions, obtained for Rochelle salt. Comparison is made with the dielectric measurements on Rochelle salt at 298 °K

Magnetic detection of a single action potential in Chara corallina internodal cells.

The electrical activity that occurs in plants has not yet been detected magnetically. Magnetic detection of electrical activity in some animal as well as in human cells and organs, on the other hand, is an established research method. Our experiments demonstrate the propagation of a single action potential in the internodal cell of the green algae Chara corallina, measured magnetically. The propagation velocity and the intracellular current were determined

NQR study of phase transitions in CH 3\mathsf{_3} HgX (X=Cl, Br, I)

The temperature dependence of halogen nuclear quadrupole resonance (NQR) in the series CH 3HgX (X=Cl, Br, I) is measured with special emphasis on the structural phase transitions at T c =162 K, 310 K, and $\sim$ 400 K, respectively. In the temperature dependences of NQR frequencies similarities are observed and discussed in relation with the structure and thermal vibrations on both sides of the phase transition. On the basis of known data a mechanism for the three analogous phase transitions is proposed. The chlorine spin-lattice relaxation behaviour in CH 3HgCl can be explained by a competition of fast thermal fluctuations of MMX molecules across the high temperature (h.t.) mirror plane and of infrequent transitions to the other equivalent fluctuation mode across the orthogonal h.t. mirror plane. Proton high temperature relaxation is probably dominated by the same slow motion, but at lower temperatures some other mechanism involving magnetic coupling prevails. Copyright Springer-Verlag Berlin/Heidelberg 2003

Magnetic detection of injury-induced ionic currents in bean plants.

A superconducting quantum interference device (SQUID) multichannel magnetometer was used to measure the temporal and spatial evolution of the magnetic field accompanying stimulation by burning and/or cutting of Vicia faba plants. These magnetic fields are caused by ionic currents that appear after injury in different parts of the plant. All measured V. faba plants responded to the burning stimulation with detectable quasi-d.c. magnetic signals. In order to measure these signals, a suitable modulation had to be used. The covariance method was applied to analyse the measured data. The results demonstrate a dipolar-like magnetic signal, exponentially decreasing in time, above the cutting type of injury. After the burning stimulation, the magnetically detected activity was concentrated predominantly above the leaves/petioles and less above the stem. Possible mechanisms for this behaviour are suggested. A comparison with previously known electrical measurements of plant injury is given