Pin nematodes of the genus Paratylenchus are widely distributed across the world and associated with many plant species. Morphological identification of Paratylenchus species is a difficult task because it relies on many characters with a wide range of intraspecific variation. In this study we provide morphological and molecular characterisation of several pin nematodes: Paratylenchus aquaticus, P. dianthus, P. hamatus, P. nanus and P. straeleni, collected in different states of the USA and South Africa. Paratylenchus aquaticus is reported from South Africa and Hawaii and P. nanus is found from South Africa for the first time. Morphological descriptions, morphometrics, hght and scanning electron microscopic photos and drawings are given for these species. Molecular characterisation of nematodes using the D2-D3 of 28S rRNA and ITS rRNA gene sequence revealed that samples morphologically identified as P. aquaticus, P. hamatus and P. nanus indeed represent species complexes containing several species. Sequences of the rRNA genes are also provided for several unidentified Paratylenchus. Phylogenetic relationships within the genus Paratylenchus are given as inferred from the analyses of the D2-D3 of 28S rRNA and ITS rRNA gene sequences. We present here the most complete phylogenetic analysis of the genus.The pin nematodes of the genus Paratylenchus Micoletzky, 1922 are characterised by their small body size with length varying from 0.2 to 0.6 mm. They are widely distributed across the world and associated with many plant species. Paratylenchus contains more than 120 nominal species (Siddiqi, 2000). Morphological identification of some species of Paratylenchus is rather difficult and relies on many characters. Most species share very similar diagnostic characters, which are very difficult to separate. Some characters have broad, overlapping ranges and show high levels of intra-specific variability. Many environmental and other factors (such as temperature, host, population size, etc.) might also have an influence on the variations in characters (Fisher, 1965).Phylogenetic and sequence analysis of rRNA and other genes provides attractive solutions to resolve some of the difficulties in species identification and understanding of relationships between species. Subbotin et al. (2005), Chen et al. (2008, 2009) and van Megen et al. (2009 gave molecular characterisation of Paratylenchus species using the D2-D3 expansion segments of 28S rRNA, ITS rRNA and 18S rRNA gene sequences, respectively. However, because only a few species were analysed in those studies.
In patients with atherosclerotic coronary artery disease, cigarette smoking increases myocardial oxygen demand but may cause an inappropriate decrease in coronary blood flow and myocardial oxgyen supply. This study was performed to explore the mechanism of smoking-induced coronary vasoconstriction and, specifically, to determine if smoking causes an ct-adrenergically mediated increase in coronary artery tone. In 36 chronic smokers with coronary artery disease (27 men and nine women, 50 9 [mean + SD] years old), heart rate-systolic arterial pressure double product and coronary sinus blood flow (by thermodilution) were measured before and during smoking both before and after (1) normal saline (n = 5, control subjects), (2)
The visible absorption of bacteriorhodopsin (bR) is highly sensitive to pH, the maximum shifting from 568 nm (pH 7) to approximately 600 nm (pH 2) and back to 565 nm (pH 0) as the pH is decreased further with HCl. Blue membrane (lambda max greater than 600 nm) is also formed by deionization of neutral purple membrane suspensions. Low-temperature, magic angle spinning 13C and 15N NMR was used to investigate the transitions to the blue and acid purple states. The 15N NMR studies involved [epsilon-15N]lysine bR, allowing a detailed investigation of effects at the Schiff base nitrogen. The 15N resonance shifts approximately 16 ppm upfield in the neutral purple to blue transition and returns to its original value in the blue to acid purple transition. Thus, the 15N shift correlates directly with the color changes, suggesting an important contribution of the Schiff base counterion to the "opsin shift". The results indicate weaker hydrogen bonding in the blue form than in the two purple forms and permit a determination of the contribution of the weak hydrogen bonding to the opsin shift at a neutral pH of approximately 2000 cm-1. An explanation of the mechanism of the purple to blue to purple transition is given in terms of the complex counterion model. The 13C NMR experiments were performed on samples specifically 13C labeled at the C-5, C-12, C-13, C-14, or C-15 positions in the retinylidene chromophore. The effects of the purple to blue to purple transitions on the isotropic chemical shifts for the various 13C resonances are relatively small. It appears that bR600 consists of at least four different species. The data confirm the presence of 13-cis- and all-trans-retinal in the blue form, as in neutral purple dark-adapted bR. All spectra of the blue and acid purple bR show substantial inhomogeneous broadening which indicates additional irregular distortions of the protein lattice. The amount of distortion correlates with the variation of the pH, and not with the color change.
Solid-state 13C NMR spectra of the M photocycle intermediate of bacteriorhodopsin (bR) have been obtained from purple membrane regenerated with retinal specifically 13C labeled at positions 5, 12, 13, 14, and 15. The M intermediate was trapped at -40 degrees C and pH = 9.5-10.0 in either 100 mM NaCl [M (NaCl)] or 500 mM guanidine hydrochloride [M (Gdn-HCl)]. The 13C-12 chemical shift at 125.8 ppm in M (NaCl) and 128.1 ppm in M (Gdn-HCl) indicates that the C13 = C14 double bond has a cis configuration, while the 13C-13 chemical shift at 146.7 ppm in M (NaCl) and 145.7 ppm in M (Gdn-HCl) demonstrates that the Schiff base is unprotonated. The principal values of the chemical shift tensor of the 13C-5 resonance in both M (NaCl) and M (Gdn-HCl) are consistent with a 6-s-trans structure and a negative protein charge localized near C-5 as was observed in dark-adapted bR. The approximately 5 ppm upfield shift of the 13C-5 M resonance (approximately 140 ppm) relative to 13C-5 bR568 and bR548 (approximately 145 ppm) is attributed to an unprotonated Schiff base in the M chromophore. Of particular interest in this study were the results obtained from 13C-14 M. In M (NaCl), a dramatic upfield shift was observed for the 13C-14 resonance (115.2 ppm) relative to unprotonated Schiff base model compounds (approximately 128 ppm). In contrast, in M (Gdn-HCl) the 13C-14 resonance was observed at 125.7 ppm. The different 13C-14 chemical shifts in these two M preparations may be explained by different C = N configurations of the retinal-lysine Schiff base linkage, namely, syn in NaCl and anti in guanidine hydrochloride.
We here theoretically outline and experimentally demonstrate that polarization spectroscopy can be combined with cavity ring down ͑CRD͒ spectroscopy, thereby retaining the specific advantages of both techniques. The b 1 ⌺ g ϩ (vЈϭ2)←X 3 ⌺ g Ϫ (vЉϭ0) transition of molecular oxygen around 628 nm is used to demonstrate the possibility to selectively measure either the polarization-dependent absorption or the resonant magneto-optical rotation of gas-phase molecules in the appropriate setup. Just as in CRD absorption spectroscopy, where the rate of absorption is measured, in the here presented polarization-dependent CRD ͑PDCRD͒ detection scheme the rate of polarization rotation is measured, which enables the polarization rotation to be quantitatively determined. Apart from studying electro-optic and magneto-optic phenomena on gas-phase species, the PDCRD detection scheme is demonstrated to be applicable to the study of magneto-optical rotation in transparent solid samples as well.
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