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Similar Variations (similar + variation)
Selected AbstractsImpact of Soil Tillage and Crop Rotation on Barley (Hordeum vulgare) and Weeds in a Semi-arid EnvironmentJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2004H. Z. Ghosheh Abstract Experiments were conducted to evaluate the effect of mouldboard- or chisel-ploughing and rotations on barley crops and associated weeds in a semi-arid location. Two primary soil tillage operations and eight crop rotation-tillage operation combinations were evaluated over two successive seasons. Drought conditions prevailed (<152 mm annual precipitation) and affected the measured parameters. Barley grown in mouldboard-ploughed plots had higher biomass compared with chisel-ploughed plots. Barley grain yield was greater in mouldboard-ploughed plots in a fallow-fallow-barley rotation. Weed species densities varied between tillage systems and rotations. Density of Hordeum marinum, for example, was high in fallow-barley-fallow in chisel-ploughed plots, and was high under more continuous fallow in mouldboard-ploughed plots. Similar variations were also observed in weed fresh weights and in numbers of seed produced. The results describe the productivity of barley under extremely dry conditions, where an advantage for mouldboard ploughing was observed. The results also indicate the complexity of weed communities in their response towards different tillage-rotation combinations. [source] Hypothalamic-Pituitary-Adrenal Axis Abnormalities in Response to Deletion of 11,-HSD1 is Strain-DependentJOURNAL OF NEUROENDOCRINOLOGY, Issue 11 2009R. N. Carter Inter-individual differences in hypothalamic-pituitary-adrenal (HPA) axis activity underlie differential vulnerability to neuropsychiatric and metabolic disorders, although the basis of this variation is poorly understood. 11,-Hydroxysteroid dehydrogenase type 1 (11,-HSD1) has previously been shown to influence HPA axis activity. 129/MF1 mice null for 11,-HSD1 (129/MF1 HSD1,/,) have greatly increased adrenal gland size and altered HPA activity, consistent with reduced glucocorticoid negative feedback. On this background, concentrations of plasma corticosterone and adrenocorticotrophic hormone (ACTH) were elevated in unstressed mice, and showed a delayed return to baseline after stress in HSD1-null mice with reduced sensitivity to exogenous glucocorticoid feedback compared to same-background genetic controls. In the present study, we report that the genetic background can dramatically alter this pattern. By contrast to HSD1,/, mice on a 129/MF1 background, HSD1,/, mice congenic on a C57Bl/6J background have normal basal plasma corticosterone and ACTH concentrations and exhibit normal return to baseline of plasma corticosterone and ACTH concentrations after stress. Furthermore, in contrast to 129/MF1 HSD1,/, mice, C57Bl/6J HSD1,/, mice have increased glucocorticoid receptor expression in areas of the brain involved in glucocorticoid negative feedback (hippocampus and paraventricular nucleus), suggesting this may be a compensatory response to normalise feedback control of the HPA axis. In support of this hypothesis, C57Bl/6J HSD1,/, mice show increased sensitivity to dexamethasone-mediated suppression of peak corticosterone. Thus, although 11,-HSD1 appears to contribute to regulation of the HPA axis, the genetic background is crucial in governing the response to (and hence the consequences of) its loss. Similar variations in plasticity may underpin inter-individual differences in vulnerability to disorders associated with HPA axis dysregulation. They also indicate that 11,-HSD1 inhibition does not inevitably activate the HPA axis. [source] Vibrational spectroscopic studies, conformations and quantum chemical calculations of 3,3,3-trifluoropropyl- silane and 3,3,3-trifluoropropylsilane- d3,JOURNAL OF RAMAN SPECTROSCOPY, Issue 1-3 2006Peter Klaeboe Abstract Infrared spectra of 3,3,3-trifluoropropylsilane (CF3CH2CH2SiH3) and 3,3,3-trifluoropropylsilane- d3 (CF3 CH2CH2SiD3) were obtained in the vapour, liquid, and crystalline solid phases in the range 4000,50 cm,1. Additional spectra in argon matrices at 5 K were recorded before and after annealing to temperatures 20,34 K. Raman spectra of the compounds as liquids were recorded at various temperatures between 296 and 183 K and spectra of the amorphous and crystalline solids were obtained. The spectra revealed the existence of two conformers (anti and gauche) in the fluid phases and in the matrices. When the two vapours were shock-frozen on a cold finger at 78 K, they turned partly crystalline immediately. After subsequent annealing to 140,150 K, ca 7,9 Raman bands of both molecules present in the liquids vanished in the crystal. Similar variations in intensity were observed in the corresponding infrared spectra before and after annealing. The spectra revealed the existence of one conformer (anti) in the crystal. From Raman intensity variations of three independent pairs of anti and gauche bands between 298 and 173 K for the parent compound, and 298 and 183 K for the deuterated analogue, the values ,confHo(gauche,anti) = 4.1 ± 0.3 kJ mol,1 for the parent compound and the same value for the deuterated species were obtained in the liquid state. Annealing experiments in the matrices show that the gauche bands vanish after annealing, demonstrating that the anti conformer also has the lower energy here and that the barrier to gauche , anti inter-conversion is around 5,6 kJ mol,1. The spectra of both conformers have been interpreted in detail. Ab initio and DFT calculations at the HF/6,311G**, B3LYP/6,311 G** and MP2/6,311 G** levels gave optimized geometries, infrared and Raman intensities and vibrational wavenumbers for the anti and gauche conformers. The conformational enthalpy difference derived from the calculations was between 6.0 and 4.1 kJ mol,1 with anti being the low energy conformer. Copyright © 2006 John Wiley & Sons, Ltd. [source] Effect of dietary protein and energy levels on growth, oxygen consumption, haemolymph and digestive gland carbohydrates, nitrogen excretion and osmotic pressure of Litopenaeus vannamei (Boone) and L. setiferus (Linne) juveniles (Crustacea, Decapoda; Penaeidae)AQUACULTURE RESEARCH, Issue 7 2001C Rosas Abstract The influence of protein and energy levels on growth rate, survival, pre- and post-prandial oxygen consumption, ammonia excretion, haemolymph glucose (HG), glycogen in digestive gland and osmotic pressure (OP) in white shrimp Litopenaeus vannamei (Boone) and L. setiferus (Linne) juveniles was studied. Diets containing a high-quality protein at a protein/energy (P/E) ratio of 16, 26, 31 and 36 mg kJ,1 were fed at 20% of shrimp body weight of two sizes: < 1 g and >,1 g. Both species showed a optimum P/E ratio of 36 mg kJ,1 (33,44% protein and 6,23% carbohydrate) in juveniles <,1 g. For shrimp >,1 g, L. setiferus showed a higher growth rate in the diet with 16 mg kJ,1 (27% protein; 32% carbohydrate) and L. vannamei between 26 and 36 mg kJ,1 (33,44% protein and 6,23% carbohydrate). In both experiments, the growth rate of L. vannamei was 2,3 times that observed in L. setiferus. Routine oxygen consumption and apparent heat increment (AHI) of L. setiferus juveniles was two times higher than that observed in L. vannamei juveniles, which could indicate that L. setiferus has a higher metabolic rate. The O/N ratio varied according to protein level, with higher values (O/N = 180) with a 16-mg kJ,1 diet and lower values (O/N = 73) with a 36-mg kJ,1 diet in L. setiferus juveniles. A similar variation in O/N ratio was obtained in L. vannamei fed with all diets with an interval between 22 and 50. An inverse relation between ammonia excretion and HG, and digestive gland glycogen (DGG) in relation to an increase in the P/E ratio indicate that both shrimp species are well adapted to use carbohydrates and/or proteins from their diet. The higher values of hyper-osmotic capacity (hyper-OC) were observed in L. setiferus <,1 g fed with 36 mg kJ,1 and the lowest in L. vannamei <,1 g fed with 31 mg kJ,1. Intermediate values of hyper-OC were observed in both species fed all diets indicating that osmotic factors of juveniles <,1 g of both species are more affected by the P/E ratio than juveniles >,1 g. All results showed that juveniles >,1 g of both species are less dependent of P/E ratio than juveniles <,1 g. Litopenaeus vannamei is a most tolerant shrimp species with a high capacity to use a wide range of dietary P/E ratios for growth, which may be due to its lower energy requirements. Litopenaeus setiferus showed a lower capacity to accept different P/E ratios but the optimum P/E ratio obtained with this species shows that L. setiferus accept diets with a high carbohydrate level as well. These results demonstrate that there are nutritional and physiological differences that explain the differences that have been observed when both species were cultured in commercial ponds. [source] Ecological correlates of body size in relation to cell size and cell number: patterns in flies, fish, fruits and foliageBIOLOGICAL REVIEWS, Issue 2 2007Jeff Arendt Abstract Body size is important to most aspects of biology and is also one of the most labile traits. Despite its importance we know remarkably little about the proximate (developmental) factors that determine body size under different circumstances. Here, I review what is known about how cell size and number contribute to phenetic and genetic variation in body size in Drosophila melanogaster, several fish, and fruits and leaves of some angiosperms. Variation in resources influences size primarily through changes in cell number while temperature acts through cell size. The difference in cellular mechanism may also explain the differences in growth trajectories resulting from food and temperature manipulations. There is, however, a poorly recognized interaction between food and temperature effects that needs further study. In addition, flies show a sexual dimorphism in temperature effects with the larger sex responding by changes in cell size and the smaller sex showing changes in both cell size and number. Leaf size is more variable than other organs, but there appears to be a consistent difference between how shade-tolerant and shade-intolerant species respond to light level. The former have larger leaves via cell size under shade, the latter via cell number in light conditions. Genetic differences, primarily from comparisons of D. melanogaster, show similar variation. Direct selection on body size alters cell number only, while temperature selection results in increased cell size and decreased cell number. Population comparisons along latitudinal clines show that larger flies have both larger cells and more cells. Use of these proximate patterns can give clues as to how selection acts in the wild. For example, the latitudinal pattern in D. melanogaster is usually assumed to be due to temperature, but the cellular pattern does not match that seen in laboratory selection at different temperatures. [source] The Dual Mode Microwave Afterglow Apparatus for Measuring the Electron Temperature Dependence of the Electron-Ion RecombinationCONTRIBUTIONS TO PLASMA PHYSICS, Issue 4 2008O. Miku Abstract Three dual mode microwave apparatus (one using S -band and two using X -band) have been developed to determine ambipolar diffusion and electron-ion recombination rates under conditions such that Tgas = 300K and Te is varied from 300 K to 6300 K, in the afterglow period of the dc glow discharge. TheTM010 cylindrical cavity (in S -band) and TM011 open cylindrical cavity (X -band) are used to determine the electron density during the afterglow period and a non-resonant waveguide mode is used to apply a constant microwave heating field to the electrons. To test the properties of the apparatus the neon afterglow plasma has been investigated. At Te = 300 K a value of , (Ne+2) = (1.7± 0.2) × 10,7cm3/s is obtained which is in good agreement with values of other investigators. Also similar variations of , as T,0.4e (S -band) and as T,0.42e (X -band) obeyed over the range 300 , Te , 6300K are in good agreement with some other previous measurements. The simplicity of the X-band microwave apparatus also allows the measurements of the gas temperature dependency and the study of electron attachment and may be used simultaneously with optical or mass spectrometry investigations. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Petrography and provenance of Laecanius Amphorae from Istria, northern Adriatic region, CroatiaGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 5 2006Maria A. Mange Amphorae sherds from the Laecanius workshop of Roman Istria (10,5 B.C. and 78 A.D.), Croatia, were studied by integrating archaeological and geological techniques including fabric analysis, thin-section petrography, X-ray diffractometry (XRD), and heavy mineral analysis. The fabric of the sherds showed distinctive characteristics, permitting their classification and allocation into nine fabric groupss. Petrography revealed that quartz is the dominant clastic component, whereas carbonate is common as temper; XRD provided information on firing temperatures that ranged between 750 and 900°C. The sherds contain diverse heavy mineral suites with generally high epidote and garnet proportions; zircon is occasionally important. Garnet/epidote ratios and the presence of diagnostic species (pyroxene, hornblende) showed systematic variations that coincided with similar variations in fabric characteristics. Heavy mineral signatures of amphorae produced in other workshops proved essential in differentiating them from Laecanius sherds. A comparative heavy mineral analysis of terra rossa samples from the vicinity of the workshop indicated that terra rossa was the major source for the paste. Differences observed in the heavy mineral composition of the sherds and terra rossa were interpreted by the spatial heterogeneity of the latter and the mixing of the paste with sandy temper. Fresh Adriatic sponge spicules in the majority of Laecanius sherds and the temper-derived, generally immature heavy mineral assemblages suggest that sandy deposits from the Adriatic were used for the clastic temper. © 2006 Wiley Periodicals, Inc. [source] Nerve regeneration along bioengineered scaffoldsMICROSURGERY, Issue 5 2007S. Geuna M.D. Tissue engineering has recently seen great advancements in many medical fields, including peripheral nerve reconstruction. In the rat median nerve model, we investigated nerve repair by means of bioengineered tissue scaffolds (muscle-vein-combined tubes) focusing on changes in the neuregulin-1/ErbB-receptor system which represents one of the main regulatory systems of axo-glial interaction in peripheral nerves. Repaired nerves were withdrawn at 5, 15, and 30 days postoperative and processed for morphological and retro-transcriptase polymerase chain reaction (RT-PCR) analysis. Results revealed an early and progressive increase in the expression of NRG1, isoform only, while the appearance of the , isoform of NRG1, which is normally present in peripheral nerves, was delayed. In regards to ErbB2 and ErbB3 receptors, their expression increased progressively inside the muscle-vein-combined scaffolds, though with different kinetics. Taken together, these results suggest that variations in neuregulin-1/ErbB system activation play a key role in peripheral nerve regeneration along bioengineered muscle-vein-combined scaffolds. Since similar variations are also detectable in denervated skeletal muscles, it can be hypothesized that the existence of a NRG1's autocrine/paracrine trophic loop shared by both glial and muscle fibers could be responsible for the effectiveness of muscle-vein-combined conduits for repairing nerve defects. © 2007 Wiley-Liss, Inc. Microsurgery, 2007. [source] Modified expression of cytoplasmic isocitrate dehydrogenase electrophoretic isoforms in seminal plasma of men with sertoli-cell-only syndrome and seminomaMOLECULAR CARCINOGENESIS, Issue 6 2008Mireille Starita-Geribaldi Abstract Two isoforms of human cytoplasmic isocitrate dehydrogenase (IDPc) of close molecular weights and different isoelectric points were identified in human seminal plasma (SP) by two-dimensional gel electrophoresis (2-DE) followed by mass spectrometry (MS). These two isoforms were detected in the normospermic men SP and their expressions were markedly altered in patients with testicular seminoma, the most frequent testicular germ cell cancer (TGCC): increase of the more acidic spot and decrease of the more basic one. Since oligospermia has been considered as a high risk pathological condition for developing a testicular cancer, the two IDPc isoforms were analyzed in SP of a group of secretory azoospermic patients. In this group the two spots displayed similar variations of expression to those observed in testicular seminoma. These results propose IDPc as a promising SP biomarker of testicular seminoma. Whether IDPc alteration in secretory azoospermia is predictive of testicular seminoma remains to be elucidated. © 2007 Wiley-Liss, Inc. [source] Growth performance, survival and maturation of Litopenaeus vannamei (Boone) in an inland CRS with no water repositionAQUACULTURE RESEARCH, Issue 12 2009Abundio González-González Abstract Closed recirculation systems (CRS) present an alternative for providing organisms to the aquaculture. A CRS with zero water exchange was used in the present study; the CRS consisted of a culture and maturation facility, biofilter system and reservoirs tanks. During two consecutive trials, the CRS efficiency was evaluated by assessing the growth, survival and maturation of juveniles into adults Litopenaeus vannamei (Boone). Throughout the study, water quality parameters (temperature, pH, salinity, NH3, NO2 and NO3) and ion concentration were monitored. Most parameters showed fluctuations without significant differences. However, a decrease in pH was observed during the maturation phase, and an increase in phosphorus was detected, in both the trials, compared with that in initial seawater. Growth and survival for juvenile and pre-adult shrimps presented similar variations without significant differences. Female gonadal maturation and spawning rate were not significantly different between trials. Unfortunately, shrimp eggs underwent lysis 6 h after spawning. These results show that the growth, survival and maturation obtained under CRS conditions are reproducible, and suggest the possibility of using these systems for biosecure shrimp culture, protected against eventual diseases outbreaks. The results of this study also suggest the importance of future studies addressing ion concentration changes in a CRS with zero water exchange. [source] | |||||||||||||