The mitochondrial genomes of soft ticks have an arrangement of genes that has remained unchanged for over 400 million years

There are two major groups of ticks: soft ticks and hard ticks. The hard ticks comprise the prostriate ticks and the metastriate ticks. The mitochondrial (mt) genomes of one species of prostriate tick and two species of metastriate ticks had been sequenced prior to our study. The prostriate tick has the ancestral arrangement of mt genes of arthropods, whereas the two metastriate ticks have rearrangements of eight genes and duplicate control regions. However, the arrangement of genes in the mt genomes of soft ticks had not been studied. We sequenced the mt genomes of two species of soft ticks, Carios capensis and Ornithodoros moubata, and a metastriate tick, Haemaphysalis flava. We found that the soft ticks have the ancestral arrangement of mt genes of arthropods, whereas the metastriate tick, H. flava, shares the rearrangements of mt genes and duplicate control regions with the other two metastriate ticks that have previously been studied. Our study indicates that gene rearrangements and duplicate control regions in mt genomes occurred once in the most recent common ancestor of metastriate ticks, whereas the ancestral arrangement of arthropods has remained unchanged for over 400 million years in the lineages leading to the soft ticks and the prostriate ticks.

Noninvasive localization of petroleum-derived spray oil in plants with chemical shift selective magnetic resonance imaging

Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) were used to detect petroleum-derived spray oils (PDSOs) in citrus seedlings and trees. The NMR spectrum of the phantom containing 10% (v/v) of a nC24 agricultural mineral oil (AMO) showed the resonance of the water protons at delta = 5 ppm, while the resonance of the oil protons at delta = 1.3 to 1.7 ppm. The peak resolution and the chemical shift difference of more than 3.3 ppm between water and oil protons effectively differentiated water and the oil. Chemical shift selective imaging (CSSI) was performed to localize the AMO within the stems of Citrus trifoliata L. seedlings after the application of a 4% (v/v) spray. The chemical shift selective images of the oil were acquired by excitation at delta = 1.5 ppm by averaging over 400 transients in each phase-encoding step. Oil was mainly detected in the outer cortex of stems within 10 d of spray application; some oil was also observed in the inner vascular bundle and pith of the stems at this point. CSSI was also applied to investigate the persistence of oil deposits in sprayed mature Washington navel orange (Citrus x aurantium L.) trees in an orchard. The trees were treated with either fourteen 0.25%, fourteen 0.5%, four 1.75%, or single 7% sprays of a nC23 horticultural mineral oil (HMO) 12 to 16 months before examination of plant tissues by CSSI, and were still showing symptoms of chronic phytotoxicity largely manifested as reduced yield. The oil deposits were detected in stems of sprayed flushes and unsprayed flushes produced 4 to 5 months after the last spray was applied, suggesting a potential movement of the oil via phloem and a correlation of the persistence of oil deposit in plants and the phytotoxicity. The results demonstrate that MRI is an effective method to probe the uptake and localization of PDSOs and other xenobiotics in vivo in plants noninvasively and nondestructively.

Pulsed EPR studies of a bacterial sulfite-oxidizing enzyme with pH-invariant hyperfine interactions from exchangeable protons

Variable-frequency pulsed electron paramagnetic resonance studies of the molybdenum(V) center of sulfite dehydrogenase (SDH) clearly show couplings from nearby exchangeable protons that are assigned to a (MoOHn)-O-v group. The hyperfine parameters for these exchangeable protons of SDH are the same at both low and high pH and similar to those for the high-pH forms of sulfite oxidases (SOs) from eukaryotes. The SDH proton parameters are distinctly different from the low-pH forms of chicken and human so.