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71.
Metz SW Feenstra F Villoing S van Hulten MC van Lent JW Koumans J Vlak JM Pijlman GP 《PloS one》2011,6(10):e25816
Pancreas disease (PD) and sleeping disease (SD) are important viral scourges in aquaculture of Atlantic salmon and rainbow trout. The etiological agent of PD and SD is salmonid alphavirus (SAV), an unusual member of the Togaviridae (genus Alphavirus). SAV replicates at lower temperatures in fish. Outbreaks of SAV are associated with large economic losses of ~17 to 50 million $/year. Current control strategies rely on vaccination with inactivated virus formulations that are cumbersome to obtain and have intrinsic safety risks. In this research we were able to obtain non-infectious virus-like particles (VLPs) of SAV via expression of recombinant baculoviruses encoding SAV capsid protein and two major immunodominant viral glycoproteins, E1 and E2 in Spodoptera frugiperda Sf9 insect cells. However, this was only achieved when a temperature shift from 27°C to lower temperatures was applied. At 27°C, precursor E2 (PE2) was misfolded and not processed by host furin into mature E2. Hence, E2 was detected neither on the surface of infected cells nor as VLPs in the culture fluid. However, when temperatures during protein expression were lowered, PE2 was processed into mature E2 in a temperature-dependent manner and VLPs were abundantly produced. So, temperature shift-down during synthesis is a prerequisite for correct SAV glycoprotein processing and recombinant VLP production. 相似文献
72.
Increased sedoheptulose-1,7-bisphosphatase activity in transgenic tobacco plants stimulates photosynthesis and growth from an early stage in development 总被引:14,自引:0,他引:14
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Activity of the Calvin cycle enzyme sedoheptulose-1,7-bisphosphatase (SBPase) was increased by overexpression of an Arabidopsis (Arabidopsis thaliana) cDNA in tobacco (Nicotiana tabacum) plants. In plants with increased SBPase activity, photosynthetic rates were increased, higher levels of Suc and starch accumulated during the photoperiod, and an increase in leaf area and biomass of up to 30% was also evident. Light saturated photosynthesis increased with increasing SBPase activity and analysis of CO2 response curves revealed that this increase in photosynthesis could be attributed to an increase in ribulose 1,5-bisphosphate regenerative capacity. Seedlings with increased SBPase activity had an increased leaf area at the 4 to 5 leaf stage when compared to wild-type plants, and chlorophyll fluorescence imaging of these young plants revealed a higher photosynthetic capacity at the whole plant level. Measurements of photosynthesis, made under growth conditions integrated over the day, showed that mature plants with increased SBPase activity fixed 6% to 12% more carbon than equivalent wild-type leaves, with the young leaves having the highest rates. In this paper, we have shown that photosynthetic capacity per unit area and plant yield can be increased by overexpressing a single native plant enzyme, SBPase, and that this gives an advantage to the growth of these plants from an early phase of vegetative growth. This work has also shown that it is not necessary to bypass the normal regulatory control of SBPase, exerted by conditions in the stroma, to achieve improvements in carbon fixation. 相似文献
73.
Dominique?StrasbergEmail author Mathieu?Rouget David?M.?Richardson Stephane?Baret Joel?Dupont Richard?M.?Cowling 《Biodiversity and Conservation》2005,14(12):3015-3032
Most natural habitat in the Mascarene Islands (Mauritius, La Réunion and Rodrigues) has been transformed. Although urbanisation,
agriculture and alien plant invasions have transformed large areas in La Réunion, the island has by far the greatest area
of intact habitats in the Mascarenes, but remaining natural areas are under threat. We propose a protocol for defining a system
of habitat types and for using these to provide a preliminary assessment of conservation priorities for La Réunion. The protocol
draws on existing data and expert knowledge to map habitat types, assesses the extent of habitat transformation, and quantifies
heterogeneity between habitat types based on climate, topography and geology. The pattern of habitat transformation was uneven
among the nineteen habitat types identified. While three habitats have lost > 95% of their original area, four still retain>
80% of their original extent. Habitat types could be grouped into the following categories: (i) transformed habitats with
low levels of plant endemism, (ii) habitats confined to homogenous geology with high levels of plantendemism, and (iii) species-rich
heterogeneous habitats on diverse geological types. Priority habitats were also identified using municipalities as a basis
for implementation. Urgent action is required for several habitat types where a large part of the original extent has been
transformed. Three municipalities which contain more than 10 habitat types should receive conservation priority. The analysis
provides the basis for setting conservation priorities in La Réunion at the regional and local scale. Implications of the
results are discussed with reference to requirements for finer-scale conservation planning. 相似文献
74.
75.
Stephane?LefrancoisEmail author Maryssa?Canuel Jibin?Zeng Carlos?R.?Morales 《Biological procedures online》2005,7(1):17-25
To assess the role of sortilin in the sorting and trafficking of sphingolipid activator proteins (SAPs) the function of sortilin
was abolished by a dominant-negative mutant and by the use of RNAi. Mutant sortilin lacking the carboxyl-terminal region that
contains the sorting signal abolished the trafficking of SAPs to the lysosomes. Both sortilin and SAPs were retained in the
Golgi apparatus. The use of chemically synthesized siRNA effectively blocked the trafficking of SAPs to the lysosomes as well.
Additionally, we created a stable COS-7 cell line transfected with the pSilencer 3.1 H1 neo vector containing a selected siRNA
template oligonucleotide (small hairpin interference RNA) where the levels of sortilin were greatly suppressed. The elimination
of sortilin by this method will permit to determine whether or not sortilin is involved in a general mechanism of lysosomal
sorting that involves the trafficking of various soluble lysosomal proteins other than SAPs. 相似文献
76.
Herbette S Menn AL Rousselle P Ameglio T Faltin Z Branlard G Eshdat Y Julien JL Drevet JR Roeckel-Drevet P 《Biochimica et biophysica acta》2005,1724(1-2):108-118
To investigate the function of glutathione peroxidase (GPX) in plants, we produced transgenic tomato plants overexpressing an eukaryotic selenium-independent GPX (GPX5). We show here that total GPX activity was increased by 50% in transgenic plants, when compared to control plants transformed with the binary vector without the insert (PZP111). A preliminary two-dimensional electrophoretic protein analysis of the GPX overexpressing plants showed notably a decrease in the accumulation of proteins identified as rubisco small subunit 1 and fructose-1,6-bisphosphate aldolase, two proteins involved in photosynthesis. These observations, together with the fact that in standard culture conditions, GPX-overexpressing plants were not phenotypically distinct from control plants prompted us to challenge the plants with a chilling treatment that is known to affect photosynthesis activity. We found that upon chilling treatment with low light level, photosynthesis was not affected in GPX-overexpressing plants while it was in control plants, as revealed by chlorophyll fluorescence parameters and fructose-1,6-biphosphatase activity. These results suggest that overexpression of a selenium-independent GPX in tomato plants modifies specifically gene expression and leads to modifications of photosynthetic regulation processes. 相似文献
77.
78.
Absence of the RGS9.Gbeta5 GTPase-activating complex in photoreceptors of the R9AP knockout mouse 总被引:1,自引:0,他引:1
Keresztes G Martemyanov KA Krispel CM Mutai H Yoo PJ Maison SF Burns ME Arshavsky VY Heller S 《The Journal of biological chemistry》2004,279(3):1581-1584
Timely termination of the light response in retinal photoreceptors requires rapid inactivation of the G protein transducin. This is achieved through the stimulation of transducin GTPase activity by the complex of the ninth member of the regulator of G protein signaling protein family (RGS9) with type 5 G protein beta subunit (Gbeta5). RGS9.Gbeta5 is anchored to photoreceptor disc membranes by the transmembrane protein, R9AP. In this study, we analyzed visual signaling in the rods of R9AP knockout mice. We found that light responses from R9AP knockout rods were very slow to recover and were indistinguishable from those of RGS9 or Gbeta5 knockout rods. This effect was a consequence of the complete absence of any detectable RGS9 from the retinas of R9AP knockout mice. On the other hand, the level of RGS9 mRNA was not affected by the knockout. These data indicate that in photoreceptors R9AP determines the stability of the RGS9.Gbeta5 complex, and therefore all three proteins, RGS9, Gbeta5 , and R9AP, are obligate members of the regulatory complex that speeds the rate at which transducin hydrolyzes GTP. 相似文献
79.
The supraoptic (SON) and paraventricular (PVN) magnocellular nuclei of the hypothalamus undergo reversible anatomical remodeling under conditions of intense secretion of neurohypophysial hormones, such as lactation and chronic dehydration. This morphological plasticity is characterized by a pronounced reduction in astrocytic coverage of neurons, which results in an increased number and extent of directly juxtaposed somatic and dendritic surfaces. As a consequence, astrocyte-mediated clearance of glutamate from the extracellular space is altered, which causes an increased concentration and range of action of the excitatory amino acid in the extracellular space. This leads to a reduction of synaptic efficacy at excitatory and inhibitory inputs through the activation of presynaptic metabotropic glutamate receptors. By contrast, the action of glio transmitters released from astrocytes and acting on adjacent magnocellular neurons is limited during such anatomical remodeling. This includes glia derived ATP mediating potentiation of glutamatergic transmission, a process compromised by the neuronal-glial reorganization.Together, these studies on hypothalamic magnocellular nuclei provide new insights on the contribution of glial cells on neuronal activity. 相似文献