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  • 1
    Electronic Resource
    Electronic Resource
    Comparative genomics identifies genes shared by distantly related insect-transmitted plant pathogenic mollicutes (2004)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 235 (2004), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Phytoplasmas and spiroplasmas are distantly related insect-transmitted plant pathogens within the class Mollicutes. Genome sequencing projects of phytoplasma strain Aster Yellows-Witches' Broom (AY-WB) and Spiroplasma kunkelii are near completion. Complete genome sequences of seven obligate animal and human pathogenic mollicutes (Mycoplasma and Ureaplasma spp.), and OY phytoplasma have been reported. Putative ORFs predicted from the genome sequences of AY-WB and S. kunkelii were compared to those of the completed genomes. This resulted in identification of at least three ORFs present in AY-WB, OY and S. kunkelii but not in the obligate animal and human pathogenic mollicutes. Moreover, we identified ORFs that seemed more closely related between AY-WB and S. kunkelii than to their mycoplasma counterparts. Phylogenetic analyses using parsimony were employed to study the origin of these genes, resulting in identification of one gene that may have undergone horizontal gene transfer. The possible involvement of these genes in plant pathogenicity is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2004.tb09596.x
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  • 2
    Electronic Resource
    Electronic Resource
    The dopamine D1 receptor is a critical mediator for cocaine-induced gene expression (2002)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 82 (2002), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The dopamine D1 receptor plays a major role in mediating behavioral responses to cocaine administration. The time course for the acquisition and the relative stability for the expression of behavioral responses suggest the involvement of enduring neuroadaptations in response to repeated cocaine exposure. Changes in gene expression through the D1 receptors may accompany and mediate the development of such neuroadaptations to repeated cocaine stimulation. To test this possibility, we systematically compared the expression of the fos and Jun family immediate early genes in the nucleus accumbens and caudoputamen in D1 receptor mutant and wild-type control mice after acute and repeated cocaine exposure. Moreover, we compared the expression of three molecules that have been implicated in mediating the actions of cocaine, Gαolf, β-catenin and brain-derived neurotrophic factor, in the two groups of mice before and after cocaine administration. We found that there is a lack of induction of c-Fos, FosB, Fra-2 and JunB by acute cocaine exposure, and of ΔFosB by repeated cocaine administration in both the NAc and CPu of D1 receptor mutant mice compared with wild-type control mice. Moreover, the D1 receptor is differentially required for mediating Gαolf, β-catenin and BDNF expression in the NAc and CPu upon cocaine exposure. These results suggest that the D1 receptor is a critical mediator for cocaine-induced expression of these genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2002.01089.x
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  • 3
    Electronic Resource
    Electronic Resource
    Changes in photosystem II function during senescence of wheat leaves (1998)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 104 (1998), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Analyses of chlorophyll fluorescence were undertaken to investigate the alterations in photosystem II (PSII) function during senescence of wheat (Triticum aestivum L. cv. Shannong 229) leaves. Senescence resulted in a decrease in the apparent quantum yield of photosynthesis and the maximal CO2 assimilation capacity. Analyses of fluorescence quenching under steady-state photosynthesis showed that senescence also resulted in a significant decrease in the efficiency of excitation energy capture by open PSII reaction centers (F'v/F'm) but only a slight decrease in the maximum efficiency of PSII photochemistry (F'v/F'm). At the same time, a significant increase in non-photochemical quenching (qN) and a considerable decrease in photochemical quenching (qP) were observed in senescing leaves. Rapid fluorescence induction kinetics indicated a decrease in the rate of QA reduction and an increase in the proportion of QB-non-reducing PSII reaction during senescence. The decrease in both F'v/F'm and qP explained the decrease in the actual quantum yield of PSII electron transport ((φPSII). We suggest that the modifications in PSII function, which led to the down-regulation of photosynthetic electron transport, would be in concert with the lower demand for ATP and NADPH in the Calvin cycle which is often inhibited in senescing leaves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1998.1040212.x
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  • 4
    Electronic Resource
    Electronic Resource
    Stomatal closure is induced rather by prevailing xylem abscisic acid than by accumulated amount of xylem-derived abscisic acid (1999)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 106 (1999), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We have studied the stomatal response in relation to the xylem-derived abscisic acid (ABA) accumulation in sunflower leaves. When ABA was introduced into detached leaves of the sunflower through xylem flux, stomatal conductance was regulated, water flux was changed as a result and at the same time the xylem-derived ABA was metabolised in the leaves. We computed the xylem-derived ABA accumulation in the leaves as a function of time by taking into account the variation of ABA flux into the leaves (the product of water flux and ABA concentration) and a continuing ABA metabolism. We found that ABA accumulation was rapid during an initial lag phase, much slowed down during the decreasing phase of stomatal conductance, but still substantial when stomatal conductance reached a new stable state. The results show a poor link between the kinetics of ABA-induced stomatal closure and the xylem-derived ABA accumulation. Xylem-derived ABA was metabolised rapidly in the leaves. Tetcyclacis, as an inhibitor, substantially inhibited this process. Two hours after ABA was fed into a leaf, about 70% of the fed ABA was metabolised, but when tetcyclacis was added into the feeding solution, less than 30% of ABA was metabolised, even after 24 h of incubation. The inhibition of ABA metabolism by tetcyclacis did not lead to more stomatal closure, which was still concentration-dependent. Since the accumulation of xylem-derived ABA was enhanced substantially by the presence of tetcyclacis, these results strongly indicate that stomata mainly respond to the prevailing ABA concentration in the xylem stream, rather than to the accumulated amount of xylem-derived ABA in the leaves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1999.106303.x
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  • 5
    Electronic Resource
    Electronic Resource
    Grain sink strength may be related to the poor grain filling of indica-japonica rice (Oryza sativa) hybrids (2001)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 112 (2001), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The physiological and biochemical factors contributing to poor grain filling of indica-japonica rice (Oryza sativa L.) hybrids were studied by analyzing the role of grain sink strength in dry matter accumulation of grains of two types of rice cultivars, Yayou 2 (an indica-japonica hybrid) and Yanjing 2 (a japonica cultivar). Carbon dioxide enrichment and plant hormone application were imposed at anthesis and the number of endosperm cells, dry matter accumulation and the activities of some sugar-metabolizing enzymes of grains were measured during grain filling. In Yayou 2, strong-potential grains (SPGs) accumulated dry weight much earlier than weak-potential grains (WPGs), but this difference was not obvious for Yanjing 2. Carbon dioxide enrichment imposed after heading significantly stimulated dry matter accumulation of WPGs of Yayou 2, but had little influence on WPGs of Yanjing 2 and SPGs of both cultivars. Leaf sheath dry matter decreased steadily in both cultivars during early stages of grain filling and accumulated during the later stages. Carbon dioxide enrichment increased leaf sheath dry matter. Dry matter accumulated by grains was linearly related to the increases in endosperm cell numbers and the activities of sucrose synthase (SS) and ADP-glucose pyrophosphorylase (AGPase) in SPGs and WPGs of both cultivars. Application of either 6-benzyladenine or abscisic acid had no significant influences on both endosperm cell number and grain dry matter accumulation. These results suggest that grain sink strength, determined by both cell numbers, SS and AGPase activities in the endosperm control the dry matter accumulation of grains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2001.1120403.x
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  • 6
    Electronic Resource
    Electronic Resource
    A kinase–cyclin pair in the RNA polymerase II holoenzyme (1995)
    [s.l.] : Nature Publishing Group
    Nature 374 (1995), S. 193-196 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] To identify new components of the RNA polymerase II holoenzyme, we isolated extragenic suppressors of a Saccharomyces cerevisiae RNA polymerase II CTD truncation mutation4. Recessive suppressing mutations were identified in two genes, SRB 10 and SRB 11. Genetic analysis indicated that the CTD and ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/374193a0
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  • 7
    Electronic Resource
    Electronic Resource
    c- fos regulates neuronal excitability and survival (2002)
    [s.l.] : Nature Publishing Group
    Nature genetics 30 (2002), S. 416-420 
    Details
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Excitotoxicity is a process in which glutamate or other excitatory amino acids induce neuronal cell death. Accumulating evidence suggests that excitotoxicity may contribute to human neuronal cell loss caused by acute insults and chronic degeneration in the central nervous system. The immediate ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/ng859
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  • 8
    Electronic Resource
    Electronic Resource
    Differences in phenotypic plasticity between plants from dimorphic seeds of Cakile edentula (1995)
    Springer
    Oecologia 102 (1995), S. 353-360 
    Details
    ISSN: 1432-1939
    Keywords: Plasticity ; Environmental heterogeneity ; Dispersal ; Seed polymorphism ; Cakile edentula
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cakile edentula produces upper and lower dimorphic seeds which disperse long and short distances, respectively, from the parent. Canonical discriminant analysis was used to determine the differences between plants from the two seed morphs in both the amount and direction of their overall plastic responses to major environmental factors. In general, plants from the long-distance dispersal seeds were less plastic than those from the short-distance dispersal seeds in response to soil moisture and sand burial. This is probably a result of broader ecological amplitude of the plants from the long-distance dispersal seeds due to their larger seed masses. Differences in the direction of overall plasticity between plants from the two seed morphs are not likely to be adaptive. However, phenotypic selection may affect the relative contribution of plants from the two seed morphs to the next generation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00329802
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  • 9
    Electronic Resource
    Electronic Resource
    (−)Alprenolol potentiates the disrupting effects of dizocilpine on sensorimotor function in the rat (1997)
    Springer
    Psychopharmacology 132 (1997), S. 281-288 
    Details
    ISSN: 1432-2072
    Keywords: Key words Acoustic startle response ; Prepulse inhibition ; Schizophrenia ; Dopamine ; Serotonin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The β-adrenoceptor antagonist as well as serotonin 5-HT1 receptor antagonist, (−)alprenolol, was found to potentiate the disrupting effect of the non-competitive NMDA receptor antagonist, dizocilpine, on prepulse inhibition (PPI) of the acoustic startle response (ASR) in the rat. The facilitating effect of dizocilpine on ASR amplitude was also potentiated by (−)alprenolol. (−)Alprenolol by itself did not affect either of these measures. These effects did not seem to be related to the unselective β-adrenoceptor antagonist property of (−)alprenolol, since combined pretreatment with the β1- and β2-adrenoceptor antagonists, metoprolol and ICI 118551, did not alter the effects of dizocilpine on startle behaviour. However, a serotonergic influence was suggested by the fact that a facilitating effect of dizocilpine on ASR amplitude was also obtained by pretreatment with the 5-HT precursor, L-5-HTP, in benserazide-pretreated rats. Furthermore, pretreatment with the 5-HT2 selective receptor antagonist, MDL 100907, significantly reduced the (−)alprenolol-induced potentiation of the effects of dizocilpine on startle behaviour, while the 5-HT3 selective receptor antagonist, ondansetron, failed to do that. Finally, the (−)alprenolol-induced potentiation of the effects of dizocilpine was significantly reduced by pretreatment with the atypical antipsychotic, clozapine, and by the potential antipsychotic and selective dopamine D2 receptor antagonist, raclopride. This study suggests that altered 5-HT activity may influence the effects of psychotomimetic drugs such as dizocilpine on sensorimotor function, and this observation may have implications for the pharmacological treatment of schizophrenia in humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050346
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  • 10
    Electronic Resource
    Electronic Resource
    Repeated administration of amphetamine induces sensitisation to its disruptive effect on prepulse inhibition in the rat (1998)
    Springer
    Psychopharmacology 135 (1998), S. 401-406 
    Details
    ISSN: 1432-2072
    Keywords: Key words Acoustic startle response ; Prepulse inhibition ; Schizophrenia ; Sensitisation ; Amphetamine ; Dopamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Male Sprague-Dawley rats were repeatedly treated with amphetamine (AMP, 1 mg/kg, SC) at 3- day intervals for 15 days and tested for prepulse inhibition of acoustic startle after each treatment. This treatment regimen induced sensitisation in the animals as evidenced by a progressive increase in the disruptive effect of AMP on prepulse inhibition. Persistent changes in brain function was indicated, since an increase in disruptive effect was observed in sensitised animals also after a 22-day-long drug- and test-free period. The development of sensitisation was blocked by pretreatment with haloperidol (HPD, 0.1 mg/kg, SC), which suggests that sensitisation to the disruptive effect of AMP was dependent on dopamine (DA) D2 receptor activation. Furthermore, the development of sensitisation was blocked by adrenalectomy, which suggests that sensitisation was dependent also on circulating adrenal hormones. Increased DA-ergic activity has been implicated in the pathophysiology of schizophrenia and AMP-induced sensitisation to the neuronal functions that modulate prepulse inhibition may be an experimental model to investigate this hypothesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050528
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