Mössbauer spectra of nontronites: Structural implications and characterization of associated iron oxides

Mössbauer spectra of three nontronite samples (Garfield H33a and SWa-1 from Washington State, U.S.A., and a sample from Hundsangen, Germany), taken between room temperature and 4.2 K in the velocity range ± 10.5 mm/s, showed between 2.9 and 13% of the total iron to be bound in goethite and not in the nontronite structure. This extraneous iron limits the utility of room temperature spectra for the assignment of structural iron sites in these samples. An adequately good distinction of the contributions of goethite and nontronite was possible in Mössbauer spectra taken at 77 K. The spectral components arising from iron in the nontronite octahedral sheets could be fitted with distributions of quadrupole-split doublets. These distributions indicate the existence of quasi-continuous octahedral site variations rather than two discrete (cis and trans) sites, and thus favour a structural model in which all octahedral iron is in cis coordination.     

Bruise detection in Pacific pink salmon (Oncorhynchus gorbuscha) by visible and short-wavelength near-infrared (SW-NIR) spectroscopy (600-1100 nm)

Visible and short-wavelength near-infrared (SW-NIR) spectroscopy (600-1100 nm) was used to detect bruises in intact, whole Pacific pink salmon (Oncorhynchus gorbuscha). The measurements were performed noninvasively through the skin and scales in the diffuse reflectance mode. Digital images of bruised and nonbruised regions of fish were captured after the fish samples were filleted. Image analysis was conducted using Adobe Photoshop 7.0 with relative gray values used as reference values in a partial least-squares (PLS) model. A PLS cross-validation model using six latent variables yielded a standard error of prediction (SEP = 0.05%, R = 0.83). Approximately 84% of all nonbruised spectra were correctly classified, whereas approximately 81% of all bruised spectra were correctly classified. These results suggest that visible and SW-NIR could be used to control the bruise defect of fish products during processing, thereby improving product consistency and quality.     

Mineralogy and heavy metal contents of soils and stream sediments in a rural region of Western Germany

This paper presents the results of a study of clay mineralogy and Pb, Zn, Cu, Rb, Sr, Y and Zr analyses of soils and stream sediments of the Schwarzach watershed, a drainage system located in a secluded rural region of eastern Bavaria, far removed from major industrial installations.Clay fractions of soils and stream sediments differ significantly in their mineralogy. The soils average 50% secondary chlorite and 40% illite, whereas recent stream sediments average 20% chlorite and 70% illite. These assemblages are possibly interconvertible under the influence, or on withdrawal, of Schwarzach water. Proportions of clay minerals in fossil stream sediments average approximately 30% chlorite, 50% illite, and 20% kaolinite with up to 10% of 10–14 Å interstratified minerals.Surface soil layers have been enriched in Pb, as have recent stream sediments. The latter have also been enriched in Zn and Cu. The increased amounts of Pb plus its close association with organic C indicate atmospheric deposition of Pb and incipient eutrophication of the Schwarzach River.     

Exploitation of the chloroplast trnL (UAA) intron polymorphisms for the authentication of plant oils by means of a lab-on-a-chip capillary electrophoresis system

Methods to discriminate plant oils facilitate the detection of either deliberate or accidental adulteration. To this direction, the variability in length among plant species of the chloroplast trnL intron was exploited for the authentication of edible and cosmetic plant oils, with an extra emphasis on olive oil. The methodology was based on the combinatorial use of a PCR assay with a capillary electrophoresis system such as the lab-on-a-chip technology. Application of the assay on DNA extracted from different oil producing plant species, including olive oil and sesame oil, indicated the ability of the trnL intron to be used as an analytical target. Furthermore, this assay could be used for the detection of adulteration of olive oil with various other plant oils, with the exception of avocado and sesame oil.     

Fitness costs associated with insecticide resistance

Insects are exposed to a variety of stress factors in their environment, and, in many cases for insect pests to agriculture, those factors include toxic chemical insecticides. Coping with the toxicity of insecticides can be costly and requires energy and resource allocation for adaptation and survival. Several behavioural, physiological and genetic mechanisms are used by insects to handle toxic insecticides, sometimes leading to resistance by constitutive overexpression of detoxification enzymes or inducing mutations in the target sites. Such actions are costly and may affect reproduction, impair dispersal ability and have several other effects on the insect's fitness. Fitness costs resulting from resistance to insecticides has been reported in many insects from different orders, and several examples are given in this mini‐review. Copyright © 2012 Society of Chemical Industry     

Is there holocene reddening (hematite formation) in soils of axeric temperate areas?

Alfisols on calcareous glacial gravels in the northern forelands of the Alps, between the Upper Rhine Valley in the west and Eastern Bavaria in the east, show rubified B_t horizons. Their redness decreases from west (2.5 YR) to east (10 YR), paralleling decreasing temperature and increasing rainfall.Detailed mineralogical studies by Mössbauer spectroscopy and differential X-ray diffraction demonstrated the presence of hematite in association with goethite. Concentrations of hematite decrease from west to east with decreasing temperature. No hematite was detected in the non-calcareous residues of calcareous C horizons.Alfisols on silty glacial material in the immediate vicinity of the reddish soils have yellow-brown (10 YR) B_t horizons and are hematite-free. We conclude that rubification (hematite formation) is possible under an axeric climate provided a suitable pedoclimate exists.     

Susceptibility to insecticides in the Q biotype of Bemisia tabaci is correlated with bacterial symbiont densities

BACKGROUND: The presence of symbiotic microorganisms may influence an insect's ability to tolerate natural and artificial stress agents such as insecticides. The authors have previously shown that Rickettsia in the B biotype of the whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) increases this insect's susceptibility to several insecticidal compounds. This communication reports a comparison of the susceptibilities of three isofemale strains of the Q biotype of B. tabaci harbouring different bacterial complements to major insecticides from different chemical groups: one strain harboured only Arsenophonus, one harboured Rickettsia and Arsenophonus and one harboured Arsenophonus and Wolbachia. RESULTS: The presence of different symbiont combinations in the three strains had a significant influence on their susceptibility to most of the insecticides tested. Thiamethoxam, imidacloprid, pyriproxyfen and spiromesifen had a significant influence on strains that had the double infections Rickettsia–Arsenophonus and Wolbachia–Arsenophonus, which also carried higher amounts of symbionts as assessed by quantitative real‐time PCR. No significant differences in mortality rates were observed when the tested strains were treated with diafenthiuron. CONCLUSION: The results suggest a correlation between the presence of high bacterial densities in B. tabaci and the insect's ability to detoxify toxic compounds such as insecticides. Copyright © 2009 Society of Chemical Industry     

Rate of Tomato yellow leaf curl virus Translocation in the Circulative Transmission Pathway of its Vector, the Whitefly Bemisia tabaci

ABSTRACT Whiteflies (Bemisia tabaci, biotype B) were able to transmit Tomato yellow leaf curl virus (TYLCV) 8 h after they were caged with infected tomato plants. The spread of TYLCV during this latent period was followed in organs thought to be involved in the translocation of the virus in B. tabaci. After increasing acquisition access periods (AAPs) on infected tomato plants, the stylets, the head, the midgut, a hemolymph sample, and the salivary glands dissected from individual insects were subjected to polymerase chain reaction (PCR) without any treatment; the presence of TYLCV was assessed with virus-specific primers. TYLCV DNA was first detected in the head of B. tabaci after a 10-min AAP. The virus was present in the midgut after 40 min and was first detected in the hemolymph after 90 min. TYLCV was found in the salivary glands 5.5 h after it was first detected in the hemolymph. Subjecting the insect organs to immunocapture-PCR showed that the virus capsid protein was in the insect organs at the same time as the virus genome, suggesting that at least some TYLCV translocates as virions. Although females are more efficient as vectors than males, TYLCV was detected in the salivary glands of males and of females after approximately the same AAP.