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Physiological Responses (physiological + response)
Selected AbstractsPhototropism: A "Simple" Physiological Response Modulated by Multiple Interacting Photosensory-response Pathways ,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2000Emmanuel Liscum ABSTRACT Phototropism is the process by which plants reorient growth of various organs, most notably stems, in response to lateral differences in light quantity and/or quality. The ubiquitous nature of the phototropic response in the plant kingdom implies that it provides some adaptive evolutionary advantage. Upon visual inspection it is tempting to surmise that phototropic curvatures result from a relatively simple growth response to a directional stimulus. However, detailed photophysiological, and more recently genetic and molecular, studies have demonstrated that phototropism is in fact regulated by complex interactions among several photosensory systems. At least two receptors, phototropin and a presently unidentified receptor, appear to mediate the primary photoreception of directional blue light cues in dark-grown plants. PhyB may also function as a primary receptor to detect lateral increases in far-red light in neighbor-avoidance responses of light-grown plants. Phytochromes (phyA and phyB at a minimum) also appear to function as secondary receptors to regulate adaptation processes that ultimately modulate the magnitude of curvature induced by primary photoperception. As a result of the interactions of these multiple photosensory systems plants are able to maximize the adaptive advantage of the phototropic response in ever changing light environments. [source] Physiological Responses of Krishum (Iris lactea Pall. var. chinensis Koidz) to Neutral and Alkaline SaltsJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2008Y. Wang Abstract The aims of this study were to compare the physiological responses of krishum (Iris lactea Pall. var. chinensis Koidz) to neutral and alkaline salt stress and identify and examine the mechanisms involved in plant response to salt treatments. In this study, biomass, ion accumulation (Na+, K+, Ca2+, Mg2+), organic solute (proline) concentration, rate of membrane electrolyte leakage (REL) and antioxidase activities including those of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6) and peroxidase (POD, EC 1.11.1.7) were investigated in krishum under different concentrations of NaCl, Na2CO3 and the mixture of the two salts in the same volume. All three treatments caused increases in Na+ concentration, proline content and REL and decreases in root Mg2+ and K+ content. Increased Ca2+ and antioxidase activities were observed at lower external Na+ concentrations. However, at higher external Na+ levels, decreased Ca2+ and antioxidase activities were detected. Alkaline salt resulted in more damage to krishum than neutral salt including lower SOD, POD and CAT activities and decreased proline content, relative to neutral salt. High Na+ and low K+ in krishum intensified ion toxicity under alkaline condition. Alkaline salt caused greater harm to plants than neutral salt, the primary reason of which might be the lower Ca2+ content in the plant under alkaline salt stress. [source] Physiological Responses of Limonium aureum Seeds to Ultra-dryingJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 5 2007Yi Li Abstract The seeds of Limonium aureum (L.) Hill. were dried from 8.92% to 2.88% moisture content in a desiccating container with silica gel. After ultra-drying the seeds were accelerated aged (50 °C, 1 month), and some physiological indices, including the electrical conductivity, dehydrogenase activity, superoxide dismutase (SOD), peroxidase (POD), glutathione reductase (GR), ascorbate peroxidase (APX), catalase (CAT), volatile aldehydes and malondialdehyde (MDA) were tested. The results indicated that dehydrogenase, POD, SOD, GR, APX and CAT activities of the ultra-dry seeds were higher than the control seeds, while volatile aldehydes and malondialdehyde were lower than the control group. The results suggest that ultra-drying is beneficial for maintaining the vigor of L. aureum seeds at a high level. Thus, L. aureum seeds could be stored under ultra-dry conditions. (Handling editor: Jin-Zhong Cui) [source] Physiological Responses of Nile Tilapia, Oreochromis niloticus, Fed Vitamin C- and Lipid-Supplemented Diets and Submitted to Low-Temperature Stress,JOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2007Dario R. Falcon This study evaluated the effects of different levels of vitamin C and lipids on physiological responses of Nile tilapia, Oreochromis niloticus, submitted to temperature stress. There were two phases: Phase I , preparing fish to store vitamin C and lipid at appropriate temperature, and Phase II , evaluating the contributions these reserves make to fish physiology under low-temperature stress. The experiment used a 3 × 2 factorial design with three vitamin C levels (300, 600, and 1200 mg/kg diet) and two lipid levels (8.0 and 12.0%), plus absence of nutrient test and a diet of 6.0% lipids and 125.0 mg/kg vitamin C. In Phase I, 192 fish were kept at 26.0 ± 1.0 C for 112 d, and in Phase II, 48 fish were kept at 18.0 ± 0.5 C for 32 d and at 15.0 ± 0.5 C for 11 d. Fish fed C0L0 diet showed lower erythrocytes values in both phases; higher vitamin C supplement determined higher red blood cell (RBC) number and higher hematocrit (Htc) (Phase II); Htc was significantly lower in Phase II; after temperature stress, fish fed C0L0 diet had higher mean corpuscular volume, lower hemoglobin corpuscular concentration, and significantly lower vitamin C concentration in the liver; and higher supplementation determined a higher concentration in the liver (Phases I and II). Higher plasmatic cortisol concentration was seen in fish fed C0L0 diet. In conclusion, our results show that the absence of vitamin C in diets impairs RBC formation and does not enable fish to cope with stress; excess vitamin C is efficient in mitigating stress and 600 mg/kg diet is economic and physiologically sufficient to prepare fish for coping with low-temperature stress. Lipid supplementation does not determine alterations in stress biochemical parameters. [source] Physiological Responses of Acropora cervicornis to Increased Solar Irradiance,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007Juan L. Torres ABSTRACT The effects of increased UV radiation (UV-B [280,320 nm] + UV-A [320,400 nm]; hereafter UVR) on the growth, production of photosynthetic pigments and photoprotective mycosporine-like amino acids (MAAs) were studied in the threatened Caribbean coral Acropora cervicornis transplanted from 20 to 1 m depth in La Parguera, Puerto Rico. The UVR exposure by the transplanted colonies was significantly higher than that at 20 m, while photosynthetically active radiation (PAR) only increased by 9%. Photosynthetic pigments, quantified with HPLC, as well as linear extension rates and skeletal densities, were significantly reduced 1 month after transplantation to 1 m depth, while MAAs increased significantly despite immediate paling experienced by transplanted colonies. While these colonies showed a significant reduction in photosynthetic pigments, there were no significant reductions in zooxanthellae densities suggesting photoacclimation of the coral's symbionts to the new radiation conditions. The results suggest that while corals might be able to survive sudden increases in UVR and PAR, their skeletal structure can be greatly debilitated due to a reduction in the photosynthetic capacity of their symbionts and a possible relocation of resources. [source] Physiological Responses of Forest Trees to Heat and DroughtPLANT BIOLOGY, Issue 5 2006H. Rennenberg Abstract: The heat wave of summer 2003 was the largest and the most persistent ever experienced in Central Europe and has fuelled concern about the effects of climate change on European ecosystems. Since forests constitute the most important European ecosystems, in this review article we assess current knowledge on the effects of heat and drought on key metabolic processes for growth and productivity of forest trees. In particular, the general consequences of heat and drought on (1) photosynthesis and respiration at the cellular and community level, and (2) on nutrient uptake, partitioning and competition for nutrients are summarized. The latter are a major sink for photosynthetic energy and, therefore, are indirectly but strongly connected to the performance of photosynthesis. In addition, the interaction of heat and drought with stress compensation mechanisms and emission of biogenic volatile organic compounds (BVOC) are discussed, since these processes are directly connected to carbon metabolism. Effects on the emission of BVOC are also included because they constitute an important feedback mechanism on ozone formation and, thus, on atmospheric pollution. As far as available, data collected during the 2003 heat wave are included and discussed. [source] Physiological response to stress in fledgling Lesser Kestrels Falco naumanni: the role of physical condition, sex and individual genetic diversityIBIS, Issue 3 2009JOAQUÍN ORTEGO Exposure to chronic stress early on during development has important deleterious consequences later in life, reducing important components of individual fitness such as survival and future reproduction. In this study, we evaluate the factors associated with physiological response to stress in fledgling Lesser Kestrels Falco naumanni, paying particular attention to the potential role of individual genetic diversity. For this purpose, we used heterophil/lymphocyte ratios (H/L ratio) as a haematological stress indicator and typed the analysed individuals at 11 highly polymorphic microsatellite loci, which allowed us to estimate their genetic diversity. We found that the H/L ratio decreases with fledgling physical condition, suggesting that this parameter is a good indicator of nutritionally based physiological stress. Physiological response to stress was higher in males than in females and this effect was independent of physical condition, suggesting that the observed pattern is due to inherent sexual differences in the factors influencing H/L ratios. Finally, the H/L ratio was positively associated with the genetic diversity of offspring. Previous experimental studies have found that individuals with higher genetic diversity show increased levels of circulating glucocorticoids, which in turn are directly responsible for increasing H/L ratios. On this basis, we suggest that a positive effect of genetic diversity on corticosterone levels may explain the observed association between H/L ratios and individual heterozygosity. Overall, this study highlights the utility of leucocyte profiles to study stress in wild bird populations and poses an interesting question about the effects of individual genetic diversity on haematological response to stress. [source] Physiological responses of Matricaria chamomilla to cadmium and copper excessENVIRONMENTAL TOXICOLOGY, Issue 1 2008Jozef Ková Abstract Physiological responses of Matricaria chamomilla plants exposed to cadmium (Cd) and copper (Cu) excess (3, 60, and 120 ,M for 7 days) with special emphasis on phenolic metabolism were studied. Cu at 120 ,M reduced chamomile growth, especially in the roots where it was more abundant than Cd. Notwithstanding the low leaf Cu amount (37.5 ,g g,1 DW) in comparison with Cd (237.8 ,g g,1 DW) at 120 ,M, it caused reduction of biomass accumulation, Fv/Fm ratio and soluble proteins. In combination with high accumulation of phenolics, strong reduction of proteins and high GPX activity in the roots, this supports severe redox Cu properties. In terms of leaf phenylalanine ammonia-lyase (PAL) activity, it seems that Cd had a stimulatory effect during the course of the experiment, whereas Cu was found to stimulate it after 7-day exposure. The opposite trend was visible in the roots, where Cd had a stimulatory effect at high doses but Cu mainly at the highest dose. This supports the assumption of different PAL time dynamics under Cd and Cu excess. A dose of 60 and 120 ,M Cu led to 2- and 3-times higher root lignin accumulation while the same Cd doses increased it by 33 and 68%, respectively. A Cu dose of 120 ,M can be considered as limiting for chamomile growth under conditions of present research, while resistance to high Cd doses was confirmed. However, PAL and phenolics seemed to play an important role in detoxification of Cd- and Cu-induced oxidative stress. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008. [source] Attenuating effects of natural organic matter on microcystin toxicity in zebra fish (Danio rerio) embryos,benefits and costs of microcystin detoxicationENVIRONMENTAL TOXICOLOGY, Issue 1 2006Jimena Cazenave Abstract To contribute to the understanding of joined factors in the environment, impact of pure microcystins (-RR and -LF) on zebra fish (Danio rerio) embryos were investigated individually and in combination with a natural organic matter (NOM). The applied NOM was a reverse osmosis isolate from Lake Schwarzer See (i.e., Black Lake, BL-NOM). Teratogenic effects were evaluated through changes in embryonic development within 48 h of exposure. Detoxication activities were assessed by the activities of phase II biotransformation enzymes, soluble and microsomal glutathione S -transferase (s, mGST). Oxidative stress was assessed by determining both the production of hydrogen peroxide and by analyzing the activities of the antioxidative enzymes, guajacol peroxidase (POD), catalase (CAT), glutathione peroxidase (GPx), and the glutathione restoring enzyme glutathione reductase (GR). Energetic costs were evaluated by determining contents of fat, carbohydrates, and proteins in both exposed and control embryos. BL-NOM attenuated toxic effects of MC-LF and MC-RR verified by less pronounced teratological effects within 24 h, in particular, as well as less rise in the activity of s-GST, when compared with embryos exposed to either pure toxins or in combination with organic matter. BL-NOM also diminished oxidative effects caused by MC-LF; however, it failed to attenuate oxidative stress caused by MC-RR. Content of lipids was significantly reduced in exposed embryos following a trend similar to that obtained with teratological and enzymatic assays confirming the attenuating effect of BL-NOM. Physiological responses to microcystins and NOM required energetic costs, which were compensated to the expense of the energy resources of the yolk, which in turn might affect the normal development of embryos. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 22,32, 2006. [source] Physiological responses of cork oak and holm oak to infection by fungal pathogens involved in oak declineFOREST PATHOLOGY, Issue 4 2009B. T. Linaldeddu Summary The aim of this research was to study the changes in net photosynthesis and stomatal conductance values in 3-year-old cork oak and holm oak seedlings growing in natural conditions and inoculated with Apiognomonia quercina, Biscogniauxia mediterranea, Botryosphaeria corticola and Pleurophoma cava. Throughout the 4-month experimental period, the evolution of visual external symptoms and the values of physiological variables were periodically recorded. All pathogens caused stem lesions around the infection point; however, the lesions caused by B. corticola were longer in both oak species. On cork oak seedlings, all pathogens induced a significant and gradual reduction in net photosynthesis and stomatal conductance values, whereas other physiological disturbances were induced only by B. corticola infections on holm oak seedlings. [source] Physiological responses of two contrasting desert plant species to precipitation variability are differentially regulated by soil moisture and nitrogen dynamicsGLOBAL CHANGE BIOLOGY, Issue 5 2009LISA D. PATRICK Abstract Alterations in global and regional precipitation patterns are expected to affect plant and ecosystem productivity, especially in water-limited ecosystems. This study examined the effects of natural and supplemental (25% increase) seasonal precipitation on a sotol grassland ecosystem in Big Bend National Park in the Chihuahuan Desert. Physiological responses , leaf photosynthesis at saturating light (Asat), stomatal conductance (gs), and leaf nitrogen [N] , of two species differing in their life form and physiological strategies (Dasylirion leiophyllum, a C3 shrub; Bouteloua curtipendula, a C4 grass) were measured over 3 years (2004,2006) that differed greatly in their annual and seasonal precipitation patterns (2004: wet, 2005: average, 2006: dry). Precipitation inputs are likely to affect leaf-level physiology through the direct effects of altered soil water and soil nitrogen. Thus, the effects of precipitation, watering treatment, soil moisture, and nitrogen were quantified via multivariate hierarchical Bayesian models that explicitly linked the leaf and soil responses. The two species differed in their physiological responses to precipitation and were differentially controlled by soil water vs. soil nitrogen. In the relatively deeply rooted C3 shrub, D. leiophyllum, Asat was highest in moist periods and was primarily regulated by deep (16,30 cm) soil water. In the shallow-rooted C4 grass, B. curtipendula, Asat was only coupled to leaf [N], both of which increased in dry periods when soil [N] was highest. Supplemental watering during the wet year generally decreased Asat and leaf [N] in D. leiophyllum, perhaps due to nutrient limitation, and physiological responses in this species were influenced by the cumulative effects of 5 years of supplemental watering. Both species are common in this ecosystem and responded strongly, yet differently, to soil moisture and nitrogen, suggesting that changes in the timing and magnitude of precipitation may have consequences for plant carbon gain, with the potential to alter community composition. [source] Physiological responses in Nile tilapia exposed to different photoperiod regimesJOURNAL OF FISH BIOLOGY, Issue 3 2004A. K. Biswas After conditioning Nile tilapia Oreochromis niloticus for 2 weeks, the photoperiod regime of 12 tanks of fish was changed to a 6L : 6D photoperiod while 12 further tanks were retained on the conditioning photoperiod regime (12L : 12D). Blood samples were collected 3 days (first sampling) and 3 months (second sampling) after changing the photoperiod regime. Blood was collected at 6 h intervals from both photoperiod regimes (1000, 1600, 2200 and 0400 hours). At the first sampling time, fish in the 6L : 6D had significantly higher cortisol both in the light and dark phases than levels in fish in the 12L : 12D photoperiod. At the second sampling time, the levels were significantly higher only in the light phase. The levels of cortisol, glucose and Cl, in fish exposed to the 6L : 6D photoperiod, however, were far lower than those of acute stress-induced levels observed in fish exposed to a stress experiment. Furthermore, there were no significant differences in overall values of all the variables between the photoperiod regimes at the second sampling time. This indicated that the fish exposed to the 6L : 6D photoperiod were not chronically stressed. Significantly higher blood lymphocyte counts were observed in fish exposed to the 6L : 6D compared to those of the 12L : 12D photoperiod during the light phase at the second sampling time. Other variables (glucose, Cl,, haematocrit and neutrophil) did not show a significant difference between the treatments at either sampling time. These results demonstrated that the artificial photoperiod regime did not cause a significant acute or chronic stress response in Nile tilapia. [source] Physiological and growth responses of the montane bryophyte Racomitrium lanuginosum to atmospheric nitrogen depositionNEW PHYTOLOGIST, Issue 1 2003I. S. K. Pearce Summary ,,The effects of nitrogen (N) deposition on the moss Racomitrium lanuginosum within montane heath in Scotland were investigated over 5 yr. ,,Permanent field plots were sprayed with KNO3 or NH4Cl solutions, at doses equivalent to 10 and 40 kg N ha,1 yr,1, in 3,6 applications each summer. ,,Racomitrium growth and cover were severely reduced by N addition, whilst the proportion of dead shoots greatly increased. N dose decreased inducibility of shoot nitrate reductase activity (NRA), suggesting that N saturation of Racomitrium occurred, and caused an increase in potassium leakage. At high dosage, effects of NH4+ were more detrimental than NO3,. ,,Physiological responses to N indicate that the habitat's critical load (CL) is exceeded by addition of 10 kg N ha,1 yr,1. The differential toxicity of the two forms of N suggests that predominant ion type in deposition should be taken into consideration when CLs are set. In contrast to tissue N, NRA correlated well with shoot growth, and may thus be a useful biological indicator of moss condition. [source] Composite estimates of physiological stress, age, and diabetes in American SamoansAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2007Douglas E. Crews Abstract Composite estimates of physiological stress such as allostatic load (AL) were developed to help assess cumulative impacts of psychosocial and physical stressors on the body. Physiological responses to stress generally accelerate somatic wear-and-tear and chronic degenerative conditions (CDCs). Following McEwen (Neuropsychopharmacology 22 (1999) 108,124) and others, primary physiological mediators of somatic stress responses include glucocorticoids (cortisol), catecholamines (adrenaline and noradrenaline), and serum dihydroepiandosterone-sulfate (DHEA-S). Conversely, blood pressure (BP), serum HDL and total cholesterol, glycated hemoglobin (HbA1c), and waist/hip (w/h) ratio are modulated by such hormones, thereby acting as secondary mediators of stress response. When these risk factors are aggregated into a composite score, higher stress loads are associated with increased risks for days of school/work missed, functional losses, morbidity, and mortality in US samples. To examine stress loads in American Samoans, data on all 6 secondary mediators along with estimates of body habitus (i.e. height, weight, circumferences, skinfolds) and physiology (i.e. fasting insulin, LDLc, triglycerides, fasting glucose) were measured on 273 individuals residing on Tutuila Island in 1992. Four combinations of these physiological factors were used to determine composite estimates of stress. These were then assessed by sex for associations with age and the presence of diabetes. Composite estimates of stress load were higher in Samoan women than men. Associations with age tended to be low and negative in men, but positive in women, appearing to reflect cultural circumstances and population history. Stress load scores also were higher among those with diabetes than those without among both men and women. These results suggest that composite estimates of stress may be useful for assessing future risks of CDC's and the senescent processes that may underlie them in cross-cultural research. Am J Phys Anthropol, 2007. © 2007 Wiley-Liss, Inc. [source] Physiological responses of young cross-bred calves immediately after long-haul road transportation and after one week of habituationANIMAL SCIENCE JOURNAL, Issue 6 2009Katsuji UETAKE ABATRACT We investigated 10 suckling cross-bred calves (Japanese Black (Wagyu) × Holstein) and collected data on the physiological stress responses of the young calves to long-haul road transportation. All calves were male and 21,47 days of age. The calves were obtained at a livestock market and were transported from the market to the university in a commercial livestock vehicle. The total haul distance and time were 306.9 km and 7 h, respectively. The calves were deprived of food and water during transportation. Blood samples, electrocardiograms, and rectal temperatures were collected immediately after transportation and after one week of habituation at the university. Serum pH was significantly lower (P < 0.01), while serum triiodothyronine, aspartate aminotransferase, non-esterified fatty acids (all P < 0.05), and heart rate (P < 0.01) were significantly higher immediately after transportation. The concentrations of blood lactic acid (P = 0.08) and serum alanine aminotransferase (P = 0.06) tended to be higher after transportation. These physiological responses suggest that the stress caused by long-haul transportation causes significant effects on liver function in young calves. [source] Physiological responses of lupin genotypes to terminal drought in a Mediterranean-type environmentANNALS OF APPLIED BIOLOGY, Issue 3 2007J.A. Palta Abstract Field experiments concerning lupin grown in a low-rainfall environment of the Mediterranean climatic region of Western Australia were conducted over three seasons to identify and evaluate the characteristics that maximise yield per unit of rainfall. The characteristics of early flowering and podding, high pod retention, fast rates of seed filling, osmotic adjustment and the degree of dry matter transfer from stem to the seed were studied in 12 lupin genotypes differing in seed yield under conditions of terminal drought. To allow recently released cultivars and advanced breeding lines to be evaluated, five to six genotypes were included in the first and the third year and nine in the second year. The genotypes were grown rainfed until pod set and then under a rainout shelter. Flowering and podding dates, pod retention, seed growth rate and osmotic adjustment were measured in detail, together with leaf water potential, seed yield and its components. The timing and intensity of development of the terminal drought varied from average in 1998 and 1999 to extreme in 2000. In each year, the seed yield under terminal drought showed genotypic differences, which appeared consistent with the timing and intensity of the development of terminal drought. Early flowering and podding were significantly correlated with seed yield. Fast rates of seed growth were highly and significantly correlated with high yields regardless of the intensity of development of terminal drought. Pod retention was highly correlated with yield in seasons in which the intensity of the development of terminal drought was average but not under extreme conditions of terminal drought. This was because the seed number per pod was markedly reduced to compensate for the high number of pods retained. Osmotic adjustment did not occur during the development of terminal drought in any of the genotypes. Dry matter transfer from stems to seeds was insignificant and not related to seed yield, suggesting that it is not a useful characteristic in screening for high yield under terminal drought. [source] Physiological responses of pink abalone Haliotis corrugata (Gray, 1828) exposed to different combinations of temperature and salinityAQUACULTURE RESEARCH, Issue 7 2010Zarina Medina Romo Abstract Physiological responses of pink abalone Haliotis corrugata were determined under different temperature and salinity conditions. Oxygen consumption rate was not affected by temperature and salinity. Ammonium excretion of pink abalone was inversely related to salinity. The O:N ratio indicated that abalone maintained in lower salinities had an interval of 4.9,7.7, which is indicative of a protein-dominated metabolism, whereas the O:N in 35, was 28.8,35.5 for both temperatures, suggesting that carbohydrates were used as energy substrate. Haemolymph osmolality of abalone exposed to 20 and 24 °C was slightly hyperiso-osmoconformic in salinity ranges of 20,35,. The results of this study suggested that for optimized culture, pink abalone should be cultivated at 24 °C at a salinity of 35,. [source] Physiological responses of juvenile wedge sole Dicologoglossa cuneata (Moreau) to high stocking densityAQUACULTURE RESEARCH, Issue 7 2009Marcelino Herrera Abstract Physiological responses to a high stocking density were tested in juvenile wedge sole Dicologoglossa cuneata (Moreau). Fish were kept at low (1 kg m,2), medium (3 kg m,2) and high (9 kg m,2) stocking densities for 22 days. No differences in the weight, length, survival and hepatosomatic index were observed among treatments. Basal plasma cortisol and osmolality were found to be directly and positively related to stocking density. A mild increase in plasma glucose was seen at medium density, and plasma protein was elevated at medium and high densities. The liver glucose and glycogen content was inversely related to stocking density. The liver triglyceride level was significantly elevated at the highest density, and the ,-amino acid content decreased at the highest density. In muscle, glucose levels were significantly higher in fish kept at the lowest density; the ,-amino acid content was elevated in fish kept at high density. In conclusion, plasma cortisol levels indicated an increasing stress level depending on the culture density, but significant changes in energy reserves did not occur in tissue (mainly liver and muscle glycogen and glucose reserves were significantly affected). [source] Lowering of blood pressure during chronic suppression of central sympathetic outflow: Insight from computer simulationsCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 2 2010Radu Iliescu Summary 1. Chronic electrical stimulation of the carotid sinuses has provided unique insight into the mechanisms that cause sustained reductions in blood pressure during chronic suppression of central sympathetic outflow. 2. Because renal denervation does not abolish the sustained fall in arterial pressure in response to baroreflex activation, this observation has seemingly challenged the concept that the kidneys play a critical role in the long-term control of arterial pressure during chronic changes in sympathetic activity. The aim of the present study was to use computer simulations to provide a more comprehensive understanding of physiological mechanisms that mediate sustained reductions in arterial pressure during prolonged baroreflex-mediated suppression of central sympathetic outflow. 3. Physiological responses to baroreflex activation under different conditions were simulated by an established mathematical model of human physiology (QHP2008; see Supporting Information (Appendix S1) provided in the online version of this article and/or http://groups.google.com/group/modelingworkshop). The model closely reproduced empirical data, providing important validation of its accuracy. 4. The simulations indicated that baroreflex-mediated suppression of renal sympathetic nerve activity does chronically increase renal excretory function but that, in addition, hormonal and haemodynamic mechanisms also contribute to this natriuretic response. The contribution of these redundant natriuretic mechanisms to the chronic lowering of blood pressure is of increased importance when suppression of renal adrenergic activity is prevented, such as after renal denervation. Activation of these redundant natriuretic mechanisms occurs at the expense of excessive fluid retention. 5. More broadly, the present study illustrates the value of numerical simulations in elucidating physiological mechanisms that are not obvious intuitively and, in some cases, not readily testable in experimental studies. [source] Differential effects of stress and amphetamine administration on Fos-like protein expression in corticotropin releasing factor-neurons of the rat brainDEVELOPMENTAL NEUROBIOLOGY, Issue 6 2007David Rotllant Abstract Corticotropin releasing factor (CRF) appears to be critical for the control of important aspects of the behavioral and physiological response to stressors and drugs of abuse. However, the extent to which the different brain CRF neuronal populations are similarly activated after stress and drug administration is not known. We then studied, using double immunohistochemistry for CRF and Fos protein, stress and amphetamine-induced activation of CRF neurons in cortex, central amygdala (CeA), medial parvocellular dorsal, and submagnocellular parvocellular regions of the paraventricular nucleus of the hypothalamus (PVNmpd and PVNsm, respectively) and Barrington nucleus (Bar). Neither exposure to a novel environment (hole-board, HB) nor immobilization (IMO) increased Fos-like immunoreactivity (FLI) in the CeA, but they did to the same extent in cortical regions. In other regions only IMO increased FLI. HB and IMO both failed to activate CRF+ neurons in cortical areas, but after IMO, some neurons expressing FLI in the PVNsm and most of them in the PVNmpd and Bar were CRF+. Amphetamine administration increased FLI in cortical areas and CeA (with some CRF+ neurons expressing FLI), whereas the number of CRF+ neurons increased only in the PVNsm, in contrast to the effects of IMO. The present results indicate that stress and amphetamine elicited a distinct pattern of brain Fos-like protein expression and differentially activated some of the brain CRF neuronal populations, despite similar levels of overall FLI in the case of IMO and amphetamine. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007. [source] The bone histology of osteoderms in temnospondyl amphibians and in the chroniosuchian BystrowiellaACTA ZOOLOGICA, Issue 1 2010Florian Witzmann Abstract Witzmann, F. and Soler-Gijón, R. 2010. The bone histology of osteoderms in temnospondyl amphibians and in the chroniosuchian Bystrowiella. ,Acta Zoologica (Stockholm) 91: 96,114 Bone histology of osteoderms in the armoured temnospondyl Peltobatrachus, plagiosaurids (Gerrothorax, Plagiosuchus) and dissorophids (Aspidosaurus, Cacops, Platyhystrix), as well as in the chroniosuchian Bystrowiella, is studied. The massive osteoderms of Peltobatrachus and Gerrothorax consist of homogeneous parallel-fibred bone, whereas in dissorophids, a lightly built, trabecular middle region is mantled by a thin cortex that is composed of a plywood-type structure. In Bystrowiella and Plagiosuchus, the osteoderms consist to a large degree of interwoven primary fibres and have cell lacunae that bear stumpy canaliculi. The differences in the histological structure of dissorophids and plagiosaurids suggest an iterative evolution of osteoderms. Furthermore, histology in Plagiosuchus indicates a metaplastic development of the osteoderms, whereas the osteoderms of Gerrothorax represent periosteal ossifications as in dissorophids. This suggests a convergent origin of osteoderms also within plagiosaurids. The extensive armour in Gerrothorax probably constituted a calcium reservoir, indicated by cyclical resorption events preserved in the external cortex and interpreted as a physiological response to periodic changes in salinity of the aquatic environment. In contrast, the unique osteoderm structure of dissorophids provides maximum stability and minimum bone mass, and is coherent with the interpretation that the osteoderms served to strengthen the vertebral column during terrestrial locomotion. [source] High-dose glucose-insulin-potassium treatment reduces myocardial apoptosis in patients with acute myocardial infarctionEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 3 2005L. Zhang Abstract Background, Several clinical trials have suggested that a metabolic cocktail of glucose-insulin-potassium (GIK) decreases mortality rates in patients with acute myocardial infarction (AMI). It has also been reported that Fas-mediated apoptosis plays an important role in ischaemic/reperfusion injury in the rat model. This study was designed to evaluate the interaction of ischaemic/reperfusion and reperfusion therapy coadministered with high-dose GIK treatment on soluble Fas/APO-1 (sFas) and Fas ligand (sFasL) plasma concentration in patients with AMI. Materials and methods, Seventy-four patients presenting with AMI who underwent reperfusion therapy were randomized into a GIK group (n = 35) receiving high-dose GIK for 24 h or a vehicle group (n = 39). Thirty-four control subjects were also enrolled in the present study. Strepavidin-biotin ELISA was used to determine the soluble sFas and sFasL plasma concentration at baseline, 24 h (h), 3 day (d), 7 d and 14 d. Results, Soluble Fas and sFas-L serum concentrations ([sFas] and [sFas-L]) of patients with AMI were significantly elevated at baseline as compared with normal controls (NCs; P < 0·01 vs. NC). The sFas in the GIK and vehicle groups markedly decreased 24 h after the GIK infusion (10·7,5·9 ng mL,1 and 9·7,6·5 ng mL,1; P < 0·01 vs. baseline) and then increased during the 3,7-d period (5·9,12·1 ng mL,1 and 6·5,11·1 ng mL,1; P < 0·01 vs. 24 h). The GIK group demonstrated reduced sFas (12·1,5·9 ng mL,1) at 14 d (P < 0·01 vs. 7 d), with no concomitant changes in the vehicle group. The sFas-L in the GIK and vehicle groups was not significant different during the 14-d period. Conclusions, These results indicate that the sFas and sFasL in patients with AMI increased significantly compared with NC. Owing to the cardioprotective effects reported here and by others, a high-dose GIK infusion co-administered with the timely re-establishment of nutritive perfusion should be strongly considered as a treatment of choice for AMI. Additionally, sFas may be a valuable marker of the physiological response to ischaemic/reperfusion injury and reperfusion associated with high-dose GIK treatment. [source] Analysis of Usp DNA binding domain targeting reveals critical determinants of the ecdysone receptor complex interaction with the response elementFEBS JOURNAL, Issue 13 2001Iwona Grad The steroid hormone, 20-hydroxyecdysone (20E), directs Drosophila metamorphosis via a heterodimeric receptor formed by two members of the nuclear hormone receptors superfamily, the product of the EcR (EcR) and of the ultraspiracle (Usp) genes. Our previous study [Niedziela-Majka, A., Kochman, M., O,yhar, A. (2000) Eur. J. Biochem.267, 507,519] on EcR and Usp DNA-binding domains (EcRDBD and UspDBD, respectively) suggested that UspDBD may act as a specific anchor that preferentially binds the 5, half-site of the pseudo-palindromic response element from the hsp27 gene promoter and thus locates the heterocomplex in the defined orientation. Here, we analyzed in detail the determinants of the UspDBD interaction with the hsp27 element. The roles of individual amino acids in the putative DNA recognition , helix and the roles of the base pairs of the UspDBD target sequence have been probed by site-directed mutagenesis. The results show how the hsp27 element specifies UspDBD binding and thus the polar assembly of the UspDBD/EcRDBD heterocomplex. It is suggested how possible nucleotide deviations within the 5, half-site of the element may be used for the fine-tuning of the 20E-response element specificity and consequently the physiological response. [source] Diabetes hyperglycemia and recovery from strokeGERIATRICS & GERONTOLOGY INTERNATIONAL, Issue 1-2 2001Christopher S Gray Strokeis a major cause of death and severe disability in older people. Despite the burden of disease, there is still no safe, simple and proven medical therapy for the treatment of acute stroke. Advances in acute stroke treatment have been either consistently disappointing (neuroprotective therapy) or fraught with controversy regarding risk/benefit (thrombolysis), and attention is once again being directed towards physiological variables that may influence outcome. Both insulin-dependent and non-insulin-dependent diabetes mellitus are major risk factors for stroke. Diabetes mellitus has also been shown to be associated with increased mortality and reduced functional outcome after stroke. Hyperglycemia is a frequent finding following stroke and may reflect the metabolic stress of the acute event, so-called stress hyperglycemia, and/or underlying impaired glucose metabolism. Several large clinical studies have now demonstrated a positive association between a raised blood glucose and poor outcome from stroke; greater mortality and reduced functional recovery. What is not clear is to what extent hyperglycemia is a ,normal' physiological response to stroke or whether hyperglycemia per se increases cerebral damage in the acute phase. There are many potential mechanisms by which hyperglycemia can exert a harmful effect upon cerebral tissue and it is probable that an important relationship exists, not only between glucose and stroke outcome, but also between insulin and neuroprotection. It remains to be determined whether lowering and maintaining ,normal' glucose levels in the immediate aftermath of stroke, combined with the administration of insulin as an acute treatment, can modify this outcome. [source] Physiological response to stress in fledgling Lesser Kestrels Falco naumanni: the role of physical condition, sex and individual genetic diversityIBIS, Issue 3 2009JOAQUÍN ORTEGO Exposure to chronic stress early on during development has important deleterious consequences later in life, reducing important components of individual fitness such as survival and future reproduction. In this study, we evaluate the factors associated with physiological response to stress in fledgling Lesser Kestrels Falco naumanni, paying particular attention to the potential role of individual genetic diversity. For this purpose, we used heterophil/lymphocyte ratios (H/L ratio) as a haematological stress indicator and typed the analysed individuals at 11 highly polymorphic microsatellite loci, which allowed us to estimate their genetic diversity. We found that the H/L ratio decreases with fledgling physical condition, suggesting that this parameter is a good indicator of nutritionally based physiological stress. Physiological response to stress was higher in males than in females and this effect was independent of physical condition, suggesting that the observed pattern is due to inherent sexual differences in the factors influencing H/L ratios. Finally, the H/L ratio was positively associated with the genetic diversity of offspring. Previous experimental studies have found that individuals with higher genetic diversity show increased levels of circulating glucocorticoids, which in turn are directly responsible for increasing H/L ratios. On this basis, we suggest that a positive effect of genetic diversity on corticosterone levels may explain the observed association between H/L ratios and individual heterozygosity. Overall, this study highlights the utility of leucocyte profiles to study stress in wild bird populations and poses an interesting question about the effects of individual genetic diversity on haematological response to stress. [source] ORIGINAL ARTICLE: Brain and hypophyseal acetylcholinesterase activity of pubertal boars fed dietary fumonisin B1JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 5 2010F. A. Gbore Summary The effects of dietary fumonisin B1 (FB1) on regional brain and hypophyseal activities of AChE (EC 3117), the enzyme which catalyses the hydrolysis of acetylcholine, were studied using 24 male Large White weanling pigs divided into four groups. Each group received one of the four diets containing 0.2, 5.0, 10.0 and 15.0 mg FB1/kg in a 6-month feeding trial. All animals were slaughtered at the end of the feeding trial; the brains and the hypophyses obtained were carefully dissected out. Significant (p < 0.05) influence of dietary FB1 on regional brain and hypophyseal AChE activities were observed. The AChE activities in the pons, amygdala, hypothalamus and the medulla oblongata declined significantly (p < 0.05) with increased dietary FB1 concentrations. The findings of this study suggest that diets containing 5.0 mg FB1/kg and above significantly (p < 0.05) altered regional brain and hypophyseal AChE activities in the animals. Dietary exposure to FB1 at a concentration of approximately 5.0 mg/kg or more for a 6-month period is a potential health risk that may induce adverse physiological response resulting from altered brain neurochemistry in growing pigs. [source] Effect of induced body condition score differences on physiological response, productive and reproductive performance of Malpura ewes kept in a hot, semi-arid environmentJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 2 2010V. Sejian Summary This study was undertaken to study the influence of induced body condition score (BCS) differences on physiological response, productive and reproductive performance of Malpura ewes to optimise BCS for these ewes for maximising production making it economically viable. The study was conducted for a period of 1 year using thirty healthy Malpura ewes (2,4 year old). The animals were randomly divided and different BCS was induced within three groups named Group I (BCS 2.5; n = 10), Group II (BCS 3.0,3.5; n = 10) and Group III (BCS 4.0; n = 10). The parameters included in the study were allometric measurements, physiological response, wool yield and reproductive performance. BCS had a significant influence on allometric measurements, respiration rate and different reproductive parameters studied, while wool production differed significantly during spring and non-significantly during autumn. The results revealed that the reproductive performance of Malpura ewes with a BCS of 3.0,3.5 was better in comparison with the groups with lower and higher BCS. It may be concluded from this study that an active management of breeding sheep flock to achieve a BCS of 3.0,3.5 may prove to result in an economically viable return from these flocks. [source] Vitamin A nutrition of growing cockatiel chicks (Nymphicus hollandicus)JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 11-12 2005E. A. Koutsos Summary The experiments examined the physiological response of growing cockatiel chicks to varying levels of dietary vitamin A (VA) or , -carotene and the rate of liver VA uptake. Adult cockatiels breeding pairs (n = 10 pairs) were fed a VA-deficient diet for approximately 90 days prior to onset of egg laying. Breeding pairs were then allowed to feed their chicks diets containing either 0 IU VA/kg, 4000 IU VA/kg, or 2.4 mg , -carotene/kg. After 5 weeks, chicks fed 0 IU VA developed poor feathering, facial dermatitis and reduced body weight (p < 0.05). Liver VA was higher in chicks fed 4000 IU VA or 2.4 mg , -carotene vs. those fed 0 IU VA (p < 0.05). Duodenal , -actin and 15,15,-dioxygenase mRNA expression was similar to that of growing chickens, and greatest for cockatiel chicks fed 0 IU VA (p < 0.01). Chicks fed 0 IU VA had keratinization of the bursa and oral mucosa, and reduced bursa development and lymphocyte density (p < 0.05). Finally, when chicks fed 0 IU VA were orally gavaged with 20 IU VA/g body weight, maximal liver retinol uptake occurred between 0 and 24 h and reached a plateau at 36 h. These data demonstrate that VA deficiency can be prevented with 4000 IU VA/kg diet or 2.4 mg , -carotene/kg diet, although , -carotene conversion to VA may be lower in cockatiels than chickens. [source] Hydrocarbon degradation by thermophilic Nocardia otitidiscaviarum strain TSH1: physiological aspectsJOURNAL OF BASIC MICROBIOLOGY, Issue 6 2007Majid Zeinali Abstract Indigenous thermophilic hydrocarbon degraders are of special significance for the bioremediation of oil-contaminated desert soils with ambient temperature of 45,50 °C. The first objective of this study was to demonstrate the hydrocarbon-degrading capability of Nocardia otitidiscaviarum TSH1 (DSM 45036) which grows optimally at 50 °C. Analysis of the metabolic profile of the strain TSH1 showed that it could metabolize phenol, intermediate-chain-length n -alkanes and some polycyclic aromatic hydrocarbons (PAHs) ranging in size from two to four fused rings efficiently, but not toluene and xylene. N. otitidiscaviarum TSH1 was able to survive and grow at phenol concentrations up to 875 mg l,1. For the first time, the physiological response of a thermophilic Nocardia strain to poorly available hydrophobic compounds was also investigated. When grown on a mineral salt medium with hexadecane, N. otitidiscaviarum TSH1 showed very high affinity for the organic phase. Additionally, PAH-grown cells were considerably hydrophobic. The capacity of PAH-utilizing N. otitidiscaviarum TSH1 isolate to produce biosurfactants was also investigated. Fatty acids (C14,C18) were detected by GC-MS analysis during bacterial growth in PAH supplemented mineral media. High cell surface hydrophobicity and capability of N. otitidiscaviarum TSH1 to degrade different hydrocarbons at 50 °C may make it an ideal candidate to treat oil-contaminated desert soils. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Functional and molecular MR imaging of angiogenesis: Seeing the target, seeing it workJOURNAL OF CELLULAR BIOCHEMISTRY, Issue S39 2002Michal NeemanArticle first published online: 16 JAN 200 Abstract Intensive research over the last years led to the discovery of multiple molecular pathways and intricate regulatory network controlling the growth and regression of blood vessels in general and angiogenesis in particular. The difficulties in elucidation of the regulation of angiogenesis, stems from the inherent complexity due to participation of many cell types, under a dominant impact of physiological and environmental effects of flow, perfusion, and oxygenation. Major advances were achieved with the use of sophisticated transgenic mice models engineered so as to provide spatially and temporally controlled expression of specific factors alone or in combination. In vivo analysis of these models frequently requires the use of non-invasive imaging modalities for measurement of functional parameters of the vasculature along with dynamic molecular information. Optical methods are extensively applied for the study of angiogenesis [Brown et al., 2001] but provide very limited tissue penetration. MRI offers the advantage of being non-invasive with uniform and relatively high spatial resolution for deep tissues. Multiple MRI approaches for monitoring angiogenesis were developed over the last years, each looking at a particular step in the process. The aim of this paper is to analyze the clinical, pharmaceutical, and biological needs for imaging of angiogenesis, and to critically evaluate the strengths and weaknesses of functional and molecular imaging for monitoring angiogenesis. The inherent problem of validation of different measures of angiogenesis, and the advantages and limitations associated with application of MRI based methods, as surrogates for other measurements of angiogenesis will be discussed. The terms molecular imaging and functional imaging are frequently loosely defined with a significant overlap between the two. For the sake of this paper we will apply a narrower definition of both terms, where molecular imaging will apply to methods directed towards detection of specific biological molecules that participate directly in (regulation of) a physiological process; while functional imaging will be used to describe those methods that aim to detect the physiological response to a defined (molecular) stimulus. J. Cell. Biochem. Suppl. 39: 11,17, 2002. © 2002 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||||||||||||||||||||