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Physiological Analyses (physiological + analysis)
Selected AbstractsPhysiological Performance of Asymptomatic and Yellow Leaf Syndrome-affected Sugarcanes in VenezuelaJOURNAL OF PHYTOPATHOLOGY, Issue 1 2002M. L. IZAGUIRRE-MAYORAL Serological analyses revealed the presence of the sugarcane yellow leaf virus (ScYLV) in asymptomatic (S,) and symptomatic (S+) yellow leaf syndrome-affected sugarcane plants of the cultivars PR.692176, C.323,68, V.64,10, V.71,47, V.75,6, SP.72,2086, SP.72,1210, SP.74,2005, C.323,68, B.80,549 and B.82,363. Tests for the presence of the sugarcane yellows phytoplasma, carried out by Dr P. Jones (IACR-Rothamsted), gave negative results in all cultivars. Physiological analyses were performed in the top visible dewlap (TVD) leaf of S, and S+ plants of the cultivar PR.692176. All plants were at the second ratoon and flowering. When compared with S, plants, the S+ plants showed: (a) a marked reduction in the area of the leaf and internodes; (b) a high accumulation of total reducing sugars (TRS), glucans and ,-amino-N in the leaf blade and of TRS in the corresponding leaf sheath; (c) a decrease in the chlorophyll, phosphorus and nitrogen content in the leaf; (d) the disappearance of the leaf diurnal fluctuations in TRS accumulation and export as well as the daily oscillations of TRS and glucans between dawn and dusk; and (e) major ultrastructural alterations in the companion cells of the phloem, including the accumulation of ScYLV particles in the cytoplasm. In S, plants, none of the growth and physiological alterations described above were observed, in spite of the high density of ScYLV particles in the cytoplasm. The location of S, and S+ plants close to each other without a discernible pattern of distribution in plots subjected to optimal irrigation and fertilization rule out the possibility that environmental conditions underlay the appearance of symptoms. In plots under severe drought for 3 months, however, all S, plants become S+. Symptom expression did not affect the acid phosphatase activity in the rhizosphere of S+ plants. [source] Over-expression of SOB5 suggests the involvement of a novel plant protein in cytokinin-mediated developmentTHE PLANT JOURNAL, Issue 5 2006Jingyu Zhang Summary Cytokinins are a class of phytohormones that play a critical role in plant growth and development. sob5-D, an activation-tagging mutant, shows phenotypes typical of transgenic plants expressing the Agrobacterium tumefaciens isopentenyltransferase (ipt) gene that encodes the enzyme catalyzing the first step of cytokinin biosynthesis. The sob5-D mutant phenotypes are caused by over-expression of a novel gene, SOB5. Sequence analysis places SOB5 in a previously uncharacterized family of plant-specific proteins. A translational fusion between SOB5 and the green fluorescent protein reporter was localized in the cytoplasm as well as associated with the plasma membrane when transiently expressed in onion epidermal cells. Analysis of transgenic plants harboring an SOB5:SOB5,, -glucuronidase (GUS) translational fusion under the control of the SOB5 promoter region showed GUS activity in vegetative tissues (hydathodes and trichomes of leaves, shoot meristems and roots) as well as in floral tissues (pistil tips, developing anthers and sepal vasculature). Cytokinin quantification analysis revealed that adult sob5-D plants accumulated higher levels of trans -zeatin riboside, trans -zeatin riboside monophosphate and isopentenyladenine 9-glucoside when compared to the wild-type. Consistent with this result, AtIPT3 and AtIPT7 were found to be up-regulated in a tissue-specific manner in sob5-D mutants. Physiological analysis of the sob5-D mutant demonstrated reduced responsiveness to exogenous cytokinin in both root-elongation and callus-formation assays. Taken together, our data suggest a role for the novel gene SOB5 in cytokinin-mediated plant development. [source] Phenotypic, serological and genetic characterization of Flavobacterium psychrophilum strains isolated from salmonids in ChileJOURNAL OF FISH DISEASES, Issue 4 2009S Valdebenito Abstract Characterization of 20 Flavobacterium psychrophilum strains isolated from farmed Atlantic salmon and rainbow trout in Chile was done using phenotypic, antigenic and genetic techniques. Experimental infections were also performed to assess the virulence of two representative isolates and of the type strain. Biochemical and physiological analyses showed that Chilean F. psychrophilum strains, regardless of the host species, constitute a phenotypically very homogeneous group matching with previous descriptions of this pathogen. However, serological assays indicated the existence of antigenic heterogeneity with four patterns of serological reactions. The first group contained most (14 of 20) of the F. psychrophilum isolates showing cross-reaction with the antisera obtained against Atlantic salmon and rainbow trout isolates. Group 2 corresponded to four other rainbow trout isolates (1658, 1731, 1762 and 29009) that did not agglutinate with anti-1150 serum. Two minor serological groups were identified for the remaining isolates (Groups 3 and 4). Marked homogeneity was also revealed by genetic studies including 16S rRNA alleles, random amplified polymorphic DNA and REP-PCR showing that a major genetic group of F. psychrophilum may be dominant in disease outbreaks in farms. Restriction fragment length polymorphism of PCR analysis showed that gyrase genotypes B-S or B-R were found in Chilean isolates from rainbow trout and Atlantic salmon, whereas genotype A was not found. Virulence assays using Atlantic salmon indicated no relationship between the degree of pathogenicity and the host origin of the F. psychrophilum strains. [source] Phenotypic, serological and genetic characterization of Pseudomonas anguilliseptica strains isolated from cod, Gadus morhua L., in northern EuropeJOURNAL OF FISH DISEASES, Issue 11 2007S Balboa Abstract The biochemical, serological and genetic characteristics of six strains of Pseudomonas anguilliseptica isolated from cod, Gadus morhua, in Scotland were compared to well characterized isolates of this same bacterial species but of different origin. Biochemical and physiological analyses showed that this group of isolates was highly homogeneous, their characteristics matching previous descriptions of the pathogen. Similar results were obtained for the six cod isolates in the serological assays, all of them belonging to the serotype O1. Marked homogeneity was observed also in the genetic study, analysed by means of RAPD, ERIC-PCR and REP-PCR procedures, showing that they were similar to isolates from gilthead seabream, Sparus aurata, black spot seabream, Pagellus bogaraveo, and turbot, Psetta maxima. Virulence assays demonstrated that the cod isolates were highly pathogenic for turbot and sole, Solea senegalensis, with LD50 between 7.6 × 104 and 5 × 107 bacterial cells per fish. [source] Biochemical and molecular studies using human autopsy brain tissueJOURNAL OF NEUROCHEMISTRY, Issue 3 2003Matthew R. Hynd Abstract The use of human brain tissue obtained at autopsy for neurochemical, pharmacological and physiological analyses is reviewed. RNA and protein samples have been found suitable for expression profiling by techniques that include RT-PCR, cDNA microarrays, western blotting, immunohistochemistry and proteomics. The rapid development of molecular biological techniques has increased the impetus for this work to be applied to studies of brain disease. It has been shown that most nucleic acids and proteins are reasonably stable post-mortem. However, their abundance and integrity can exhibit marked intra- and intercase variability, making comparisons between case-groups difficult. Variability can reveal important functional and biochemical information. The correct interpretation of neurochemical data must take into account such factors as age, gender, ethnicity, medicative history, immediate ante-mortem status, agonal state and post-mortem and post-autopsy intervals. Here we consider issues associated with the sampling of DNA, RNA and proteins using human autopsy brain tissue in relation to various ante- and post-mortem factors. We conclude that valid and practical measures of a variety of parameters may be made in human brain tissue, provided that specific factors are controlled. [source] Accessory chemosignaling mechanisms in primatesAMERICAN JOURNAL OF PRIMATOLOGY, Issue 6 2006C.S. Evans Abstract Accessory olfaction is defined as the chemoreceptive system that employs the vomeronasal complex (VNC) and its distinct central projections to the accessory olfactory bulb (AOB) and limbic/cortical systems. Comparisons of the structural and functional features of primate accessory olfaction can now be made at many levels. Advances in the understanding of molecular mechanisms of odorant transfer and detection, physiological analyses of signal processing, and appreciation of ontogenetic timetables have clarified the contribution of accessory chemoreception to the sensory map. Two principal functions dominate: the decoding of social information through the uptake of signals (often fluid-borne), and the provision of an essential pathway for the "migration" of presumptive neurocrine (GnRH) cells from the olfactory placode to the hypothalamus. VN "smelling" (vomerolfaction) is now seen to overlap with primary olfaction. Both systems detect signal compounds along the spectrum of volatility/molecular weight, and neither is an exclusive sensor. Both main and accessory chemoreception seem to require collaborative molecular devices to assist in odorant transfer (binding proteins) and (for the VNO) signal recognition (MHC1 proteins). Most adaptive-selective features of primate chemocommunication variously resemble those of other terrestrial mammals. VN function, along with its genome, has been maintained within the Strepsirrhines and tarsiers, reduced in Platyrrhines, and nearly extinguished at the Catarrhine up to hominin levels. It persists as an intriguing ancient sense that retains key features of past evolutionary events. Am. J. Primatol. 68:525,544, 2006.© 2006 Wiley-Liss, Inc. [source] Feeding signals to the hungry mindEXPERIMENTAL PHYSIOLOGY, Issue 8 2009Nina Balthasar Obesity, due to its associated co-morbidities, including type 2 diabetes and cardiovascular disease, is at the forefront of today's health care concerns. Our need for novel, multifaceted approaches to tackle the global increase of waistlines is urgent, and understanding the physiological processes underlying our vulnerability to weight gain is an important one of them. Evidence for considerable heritability of body weight indicates genetic influences in the susceptibility to our obesogenic environment. Here, we will focus on neurons in brain structures such as the hypothalamus, which sense the body's metabolic state and, through an intricate cascade of events, elicit an appropriate response. We will explore the use of genetically modified mouse models in the investigation of physiological functions of genes and pathways in neuronal regulation of metabolic balance. Use of these techniques allows us to make manipulations at the molecular level (e.g. in the neuronal metabolic sensing mechanism) and combine this with systems-level physiological analysis (e.g. body weight). Recent technological advances also enable the investigation of the contributions of genes to the co-morbidities of obesity, such as obesity-induced hypertension. Reviewing examples of improvements as well as large gaps in our knowledge, this lecture aims to incite interest in whole body physiological research. [source] Molecular and physiological analysis of an OxyR-regulated ahpC promoter in Xanthomonas campestris pv. phaseoliMOLECULAR MICROBIOLOGY, Issue 6 2000Suvit Loprasert In Xanthomonas campestris pv. phaseoli, a gene for the alkyl hydroperoxide reductase subunit C (ahpC) had unique patterns of regulation by various forms of OxyR. Reduced OxyR repressed expression of the gene, whereas oxidized OxyR activated its expression. This dual regulation of ahpC is unique and unlike all other OxyR-regulated genes. The ahpC transcription start site was determined. Analysis of the region upstream of the site revealed promoter sequences that had high homology to the Xanthomonas consensus promoter sequence. Data from gel shift experiments indicated that both reduced and oxidized OxyR could bind to the ahpC regulatory region. Moreover, the reduced and the oxidized forms of OxyR gave different DNase I footprint patterns, indicating that they bound to different sites. The oxidized OxyR binding site overlapped the ,35 region of the ahpC promoter by a few bases. This position is consistent with the role of the protein in activating transcription of the gene. Binding of reduced OxyR to the ahpC promoter showed an extended DNase I footprint and DNase I hypersensitive sites, suggesting that binding of the protein caused a shift in the binding site and bending of the target DNA. In addition, binding of reduced OxyR completely blocked the ,35 region of the ahpC promoter and prevented binding of RNA polymerase, leading to repression of the gene. Monitoring of the ahpC promoter activity in vivo confirmed the location of the oxidized OxyR binding site required for activation of the promoter. A mutant that separated OxyR regulation from basal ahpC promoter activity was constructed. The mutant was unable to respond to oxidants by increasing ahpC expression. Physiologically, it had a slower aerobic growth rate and was more sensitive to organic peroxide killing. This indicated that oxidant induction of ahpC has important physiological roles in normal growth and during oxidative stress. [source] | ||||||||||