Partially Molten Middle Crust Beneath Southern Tibet: Synthesis of Project INDEPTH Results

INDEPTH geophysical and geological observations imply that a partially molten midcrustal layer exists beneath southern Tibet. This partially molten layer has been produced by crustal thickening and behaves as a fluid on the time scale of Himalayan deformation. It is confined on the south by the structurally imbricated Indian crust underlying the Tethyan and High Himalaya and is underlain, apparently, by a stiff Indian mantle lid. The results suggest that during Neogene time the underthrusting Indian crust has acted as a plunger, displacing the molten middle crust to the north while at the same time contributing to this layer by melting and ductile flow. Viewed broadly, the Neogene evolution of the Himalaya is essentially a record of the southward extrusion of the partially molten middle crust underlying southern Tibet.     

Arginine vasopressin as a thyrotropin-releasing hormone

Although hypothyroidism (with concomitant increased levels of thyroid-stimulating hormone) has been associated with elevated plasma vasopressin, the role that vasopressin plays in controlling thyroid-stimulating hormone secretion from the adenohypophysis is not understood. In two in vitro pituitary cell systems, vasopressin caused a specific and dose-related release of thyroid-stimulating hormone from cells that was equal in potency to that elicited by thyrotropin-releasing hormone, the primary acknowledged regulator of thyroid-stimulating hormone release. When injected into the hypothalamus, however, vasopressin specifically inhibited the release of thyroid-stimulating hormone. Thus, vasopressin may exert differential regulatory effects on thyroid-stimulating hormone secretion in the hypothalamus and pituitary gland.     

DETECTION AND DISCRIMINATION OF NUTRIENT DEFICIENCIES IN SUNFLOWER BY BLUE-GREEN AND CHLOROPHYLL-A FLUORESCENCE IMAGING

Fluorescence imaging was utilized to demonstrate the potential of blue-green fluorescence (BGF) and chlorophyll-a fluorescence (ChlF) to discriminate nitrogen (N), phosphorus (P), and potassium (K) deficiencies in sunflower plant showing similar growth inhibition. Only K-deficient leaves displayed significant increase of the BGF intensity. The epidermal UV-transmittance estimated by the ratio of ChlF intensities induced by UV and blue excitations (ChlF_UV/ChlF_BLUE) markedly decreased in both N- and P-deficient leaves but only in the latter that we observed significant decrease of the ratio of red and far-red ChlF intensities (RF/FRF) (that is inversely related to leaf chlorophyll concentration). The BGF increase in K-deficient was limited at leaf apex and margins and was spatially correlated to localized RF/FRF increases. Images analysis allows a better interpretation of the fluorescence changes by showing the spatial relationships between BGF, the ChlF_UV/ChlF_BLUE and the RF/FRF ratios that are indicative of physiological disturbances occurring in leaves of nutrient deficient plants.     

Detection of potato leafroll virus by visual inspection,direct tissue blotting and ELISA techniques

Greenhouse-grown Russet Burbank and Russet Norkotah plants were tested for potato leafroll virus (PLRV) by visual examination, enzyme-linked immunosorbent assay (ELISA) and direct tissue-blotting assay (DTBA). Visibly infected and healthy plants were obtained from excised eyes of tubers submitted for winter certification tests. Each plant was sectioned into leaf, petiole, stem, root, seed piece, and tuber portions. Tissues were blotted on a nitrocellulose membrane for DTBA and then homogenized for use in a double-antibody sandwich ELISA system. Agreement between the two serological detection methods and with visual readings was high for petioles and stems, but lower for leaf, tuber and root tissues. Comparison of DTBA with ELISA and with visual plant symptoms suggest that DTBA can be used with the same accuracy as ELISA for detecting PLRV in stems and petioles     

Physicochemical control of durum wheat grain filling and glutenin polymer assembly under different temperature regimes

Durum wheat is grown in the Mediterranean area where drought and high temperature frequently prevail and impact grain texture, composition and yield. The purpose of this work was to examine the effect of high temperature on grain development and final composition according to the timing of exposure. High temperature (up to 27.5 °C) was applied either during the linear grain filling or drying phases or during whole grain development. The dynamics of grain dry mass, water, glutenin polymers, and protein bodies during grain development were determined. Irrespective of high temperature timing, the arrest of grain filling was observed at 45.9% grain moisture content. At that point, starch granules included in endosperm cells reached their physical packing limit, limiting further deposits. HT applied before physiological maturity shortened the duration of grain filling and resulted in a significant increase in grain protein concentration and in the proportion of vitreous grain. Late formation of sodium dodecyl sulfate (SDS)-insoluble glutenin polymers below 32% grain moisture content was also favored. The ability of wheat storage protein to form a viscoelastic matrix embedding starch granules at the beginning of grain desiccation is proposed to be mandatory for gaining vitreous grains and a high proportion of SDS-insoluble glutenin polymers.     

Quantifying the influence of geography and environment on the northeast Atlantic mackerel spawning distribution

Mackerel (Scomber scombrus) in the northeast Atlantic have shown changes in distribution at certain times of the year, which have impacted their exploitation and management. In this study, mackerel spawning habitat over 21 recent years was characterised using generalised additive modelling, based on spatial egg density data collected every third year during targeted ichthyoplankton surveys. Mackerel spawning distribution was found to depend primarily on geographical variables (coordinates and bottom depth), with preferred spawning locations on the shelf‐edge from the north of the Iberian peninsula to the west of Scotland, with a maximum west of Ireland. Environmental drivers had a lesser influence on egg distribution. Dome shaped relationships were found with temperature and mixed layer depth, with respective optimum at 13°C and around –300 m. The model was used to reconstruct maps of the potential habitat (areas where conditions were suitable, but not necessarily used, for spawning). Little changes were observed over the years in the potential habitat, suggesting that the expansion of the egg distribution (realised habitat) was not triggered by changes in the environmental variables investigated. Little evidence was found for density‐dependent habitat selection. There was a tendency for mackerel to make more use of areas of lesser suitability in years with large stock size (1992 and 2010). This pattern, however, broke down in 2013, when stock size was the highest, as spawning occurred very south and concentrated in the most suitable habitat.     

Modelling of knots in logs

A geometrical model was derived to describe knots in logs and on the surface of lumber beams sawn from those logs. Each knot is defined by 7 parameters related to the shape and position in the stem. A computer simulation program was written to study knot shapes on a variety of observation planes.An initial investigation on the shape of knots in Scots pine logs and lumber beams suggests that the model is sufficiently accurate to describe knottiness in this species. Potential applications of this model include automated lumber grading, computerized log reconstitution and yield optimization studies.This research was carried out when the author was a Visiting Scientist at the Technical Research Centre of Finland (VTT), Forest Products Laboratory, P.O. Box 207, SF-02151 Espoo, Finland. Technical assistance of U. Saarelainen, A. Usenius and C. O. Sommardahl from VTT is gratefully acknowledged. This work was partially supported by Forestry Canada and the Natural Sciences and Engineering Research Council of Canada     

Contamination of bean seeds by <Emphasis Type="Italic">Xanthomonas axonopodis</Emphasis> pv. <Emphasis Type="Italic">phaseoli</Emphasis> associated with low bacterial densities in the phyllosphere under field and greenhouse conditions

Xanthomonas axonopodis pv. phaseoli and its variant fuscans are the causal agents of common bacterial blight of bean. Production of seeds is recommended in arid climates with the use of pathogen-free seeds. However, contamination of seeds still occurs in these seed production areas. To verify if low contamination levels of sown seeds could explain these field contaminations, we used seeds that were naturally contaminated with CFBP4834-R, a rifamycin-resistant X. axonopodis pv. phaseoli fuscous strain, to contaminate field plots at different rates. We also inoculated seeds to verify some parameters of plant colonization and seed transmission. In growth chambers, seedling contamination was always successful from seeds contaminated with CFBP4834-R having population sizes greater than 1 × 10³ CFU seed⁻¹ and were not successful below 1 × 10² CFU seed⁻¹. In the greenhouse, the efficiency of contamination of seeds was not significantly different between contaminated plants that had a low or a high CFBP4834-R population size and reached between 40% and 52% whatever the origin of the inoculum (aerial or seed-borne). In field experiments, under low relative humidity, plots with 0.1–0.003% contamination rates or plots sown with seeds that were inoculated with low CFBP4834-R population sizes (1 × 10² and 1 × 10⁴ CFU seed⁻¹) led to an asymptomatic colonization of bean during the entire growing season with low CFBP4834-R population sizes. Seeds were contaminated both in primary and secondary foci. The contamination of seeds without symptom expression during the growing season represents a risk for eventual disease outbreaks.