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Nguyen Hoang Loc Nguyen Van Song Nguyen Quang Duc Tien Tang Thuy Minh Phan Thi Quynh Nga Tae-Geum Kim Moon-Sik Yang 《Plant Cell, Tissue and Organ Culture》2011,105(1):39-45
A gene encoding the B subunit of the enterotoxigenic Escherichia coli heat-labile enterotoxin (LTB) was adapted to the optimized plant coding sequence, and fused to the endoplasmic reticulum
retention signal SEKDEL in order to enhance its expression level and protein assembly in plants. The synthetic LTB (sLTB)
gene was placed into a plant expression vector under the control of the CaMV 35S promoter, and subsequently introduced into
the watercress (Nasturtium officinale L.) plant by the Agrobacterium-mediated transformation method. The integration of the sLTB gene into the genomic DNA of transgenic plants was confirmed
by genomic DNA PCR amplification. The assembly of plant-produced LTB protein was detected by western blot analysis. The highest
amount of LTB protein produced in transgenic watercress leaf tissue was approximately 1.3% of the total soluble plant protein.
GM1-ganglioside enzyme-linked immunosorbent assay indicated that plant-synthesized LTB protein bound specifically to GM1-ganglioside, which is the receptor for biologically active LTB on the cell surface, suggesting that the plant-synthesized
LTB subunits formed biologically active pentamers. 相似文献
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New combinations are proposed in anticipation of the Polygonaceae treatment in the forthcoming volume of Intermountain Flora:
Polygonum kelloggii var. esotericum, P. kelloggii var. watsonii
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Rumex densiflorus var. pycnanthus
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R. salicifolius var. utahensis, and R. occidentalis var. tomentellus. Typifications are proposed to facilitate ongoing studies in Polygonaceae and to maintain current usage. 相似文献
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Escherichia coliL-asparaginase, an antileukaemic agent in man1, inhibits in vitro mitogen or antigen-induced blastogenesis in man2,3 and in animals (M. Bennett, E. G. Mayhew and T. Han, unpublished data) and suppresses bone-marrow derived antibody precursor cells in the mouse4. We now report that another L-asparaginase preparation—from Erwinia carotovora—also possesses antileukaemic activity5,6 and has a more pronounced immunosuppressive effect on in vitro blastogenesis than the E. coli enzyme. 相似文献
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Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes. 相似文献
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Shahriar Saiedian Ezzatollah Keyhani Jacqueline Keyhani 《Acta Physiologiae Plantarum》2007,29(5):463-471
Crocus sativus L., cultivated since ancient times as the source of saffron, is a triploid plant that can be propagated only via its corms
which undergo a period of dormancy. Understanding the processes taking place in the corm is essential to preserve the plant
and improve its quality. Color and taste being of prime importance in the quality of the saffron spice, knowledge on polyphenol
oxidase (PPO) activity in the plant is of particular interest given the role of the enzyme in fruit and vegetable browning
during processing and during the storage of processed food. In this paper, PPO activity was investigated for the first time
in extracts obtained from dormant C. sativus L. corms. PPO activity was detectable using l-DOPA, pyrogallol, catechol or p-cresol as substrate, each being oxidized to its corresponding o-quinone; no activity was detectable with l-tyrosine, tyramine or phenol as substrate. Two pH optima, respectively at 4.5 and 6.7, were observed with all substrates
and a third one, at 8.5, was found with l-DOPA and p-cresol. Kinetics parameters studied at pH 6.7 indicated the highest catalytic efficiency (in units mg−1 prot mM−1) with pyrogallol: 150, then catechol: 39, l-DOPA: 6.4 and p-cresol: 4.6. The enzymatic activity was inhibited by 50% in the presence of 0.22, 0.35, 0.5 and 0.7 mM kojic acid with, respectively,
catechol, pyrogallol, p-cresol and l-DOPA as substrate. When stained for PPO activity, non-denaturing gel electropherograms of extract revealed three distinct
bands, indicating the presence of multiple isoenzymes in dormant C. sativus L. corms. 相似文献
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Martina Beranová Slavomír Rakouský Zuzana Vávrová Tomáš Skalický 《Plant Cell, Tissue and Organ Culture》2008,94(3):253-259
A sonication-assisted, Agrobacterium-mediated, co-cultivation technique was used in an attempt to increase the transformation efficiency of flax. Hypocotyls and
cotyledons excised from about 10-day-old flax seedlings grown in vitro were placed into a 10 mM MgSO4 solution, and inoculated with an A. tumefaciens vector bearing the mgfp5-ER gene driven by the CaMV 35S promoter. The explants were subjected to pulses of ultrasound delivered by a sonicator apparatus
(35 kHz) for 0–150 s and co-cultivated for 2 h at 27°C. The dried hypocotyls and cotyledons were grown on a selective MS medium
to promote shoot regeneration. An electron microscopic study showed that the sonication treatment resulted in thousands of
microwounds on and below the surface of the explants. A stereo microscope Leica MZ 12 equipped with a GFP adaptor was used
to assess the infection and transformation of plant tissues in real time. After only 48 h and for at least 30 days after bacteria
elimination, signs of transgene expression could be seen as a bright fluorescence. Our results show that treatment with ultrasound
facilitates an enhanced uptake of plasmid DNA into the cells of flax hypocotyls and cotyledons and that its efficiency depends
on the duration of the treatment and the frequency used. SAAT could be a promising tool for enhancing transformation efficiency
in flax. 相似文献
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Poulícková A 《Folia microbiologica》2008,53(2):125-129
Single (unpaired) vegetative cells of freshwater pennate diatom Neidium cf. ampliatum differentiated into gametangia and produced a single zygote (auxospore) via a pedogamic process. The gametic nuclei fused after auxospore expansion had begun. The auxospore expanded in parallel to the apical axis of the gametangium. 相似文献
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Karin Sonntag Brigitte Ruge-Wehling Peter Wehling 《Plant Cell, Tissue and Organ Culture》2009,96(3):297-305
A method for isolation and shoot regeneration from electrofused protoplasts of L. angustifolius and L. subcarnosus was developed. Viable protoplasts were isolated from leaves of in-vitro grown seedlings at an average yield of 6 × 105 protoplasts g−1 fresh weight. Liquid and agarose solidified B5 media were used for protoplast culture. In the liquid-culture system, all
tested media, VKM, P1 and KM8p, were applicable for inducing cell division (84% of all tested petri dishes at four weeks)
and colony formation. Media containing additional carbohydrates were suitable to produce compact calli with green and brown
pigmentations in different combinations. Analysis of callus with molecular markers allowed to identify six somatic hybrids.
However, none of the parental-protoplast derived cell colonies could develop shoots. This is the first report on protoplast
fusion of L. angustifolius and L. subcarnosus with subsequent shoot regeneration. 相似文献
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Hugh D. Wilson 《Economic botany》1990,44(3):92
Traditionally viewed as an Andean grain crop,Chenopodium quinoa Willd. includes domesticated populations that are not Andean, and Andean populations that are not domesticated. Comparative analysis of leaf morphology and allozyme frequencies have demonstrated that Andean populations, both domesticated(quinua) and free-living(ajara), represent an exceptionally homogeneous unit that is well differentiated from allied domesticates of coastal Chile(quingua) and freeliving populations of the Argentine lowlands(C. hircinum). This pattern of relationships indicates that Andean populations represent a monophyletic crop/weed system that has possibly developed through cyclic differentiation (natural vs. human selection) and introgressive hybridization. Relative levels of variation suggest that this complex originated in the southern Andes, possibly from wild types allied withC. hircinum, with subsequent dispersal north to Colombia and south to the Chilean coast. Coastal populations were apparently isolated from post-dispersal differentiation and homogenization that occurred in the Andes. Other data point toward a center of origin in the northern Andes with secondary centers of genetic diversity subsequently developing in the southern Andes and the plains of Argentina. Comparative linkage of South American taxa, all tetraploid, with North American tetraploids of the subsection will eventually clarify this problem. While the possibility of a direct phyletic connection betweenC. quinoa and the Mexican domesticate(C. berlandieri subsp. nuttalliae,) cannot be excluded, available evidence indicates that the latter represents an autonomous lineage that is associated with the basal tetraploid, C. b. subsp.berlandieri, through var.sinuatum, whereas South American taxa show possible affinities to either var. zschackei or var.berlandieri. An extinct domesticate of eastern North America,C. b. subsp.jonesianum, represents either another instance of independent domestication, possibly from subsp. b. var.zschackei, or a northeastern outlier of subsp.nuttalliae. 相似文献
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M. E. Cocom Pech W. de J. May-Itzá L. A. Medina Medina J. J. G. Quezada-Euán 《Insectes Sociaux》2008,55(4):428-433
Euglossa viridissima is an orchid bee that forms both solitary and multiple female nests, making it a suitable species for the study of factors
leading to diverse degrees of sociality in Euglossines. We conducted observations in eight reused nests (where a first generation
of bees had been produced) kept in artificial boxes from the Yucatan Peninsula, Mexico. Five nests were reused (reactivated)
by a single female (SFN), two nests reused by a mother and one daughter (MFN1) and one nest reused by the mother and two daughters
(MFN2). No single nest was reactivated by unrelated females. The number of foraging trips, their duration and the duration
of cell provisioning was not different between SFN and MFN. The overall production of cells per female was not different either
between both types of nest. However, in MFN although all females did lay eggs, there was a reproductive skew in favor of the
mother (95 and 45% of the brood produced in MFN1 and MFN2 respectively). She showed reproductive control of her daughters
through oophagy and displaying threatening behavior when the daughters tried to open a cell where she had laid an egg. Brood
losses to parasites (Anthrax sp. (Bom-byliidae) and Hoplostelis bivittata (Megachilidae)) were only found in SFN which possibly reflects and advantage of MFN in this respect. Our results coupled
with other studies in Euglossa, reveal that a wide range of social behaviors occur in this genus, from solitary and communal to primitive reproductive division
of labor. Multiple factors involving different levels of pressure imposed by food availability and parasites may favor such
a diverse range of nesting behaviors. Interestingly, female associations in E. viridissima seem a result of kin selection that is enforced by coercion from mother females on their daughters. More studies are needed
to shed light upon the social organization of Euglossa and other Euglossines and on their phylogenetic relationships in order to trace the origins of eusociality in Apidae.
Received 12 February 2008; revised 25 June 2008; accepted 17 July 2008. 相似文献
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Vornanen M Haverinen J 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2011,181(7):917-926
Seasonal changes in the activity of glycogen phosphorylase (GP), a rate-limiting enzyme of glycogen degradation, were examined
in an anoxia-tolerant fish species, the crucian carp (Carassius carassius L.). In muscle and brain, the activity of GP remained constant throughout the year when tested at 25°C. In contrast, the
activities of liver and heart GP displayed striking increases in summer. When seasonal temperature changes are taken into
account, the activity of GP during the anoxic mid-winter is only 4–6% of its summer time activity in the muscle, heart and
liver, and 13% in brain. In winter-acclimatized fish, experimental anoxia (1–6 weeks) caused sustained depression of the GP
activity in heart and gills. In liver and muscle, a transient depression of GP activity occurred during the first week of
anoxia but later GP activity recovered back to the normoxic level. GP of the brain was completely resistant to anoxia. In
all studied tissues, the constitutive activity of GP is more than sufficient to degrade glycogen deposits during winter anoxia
without anoxia-induced activation of GP. The seemingly paradoxical summer-time increase in the activity of liver and heart
GP could be related to active life-style of the summer-acclimatized fish (growth, reproduction), the increased demand of energy
and molecular precursors of anabolic metabolism being satisfied by preferential degradation of glycogen. The high glycogen
content of winter-acclimatized crucian carp is not associated with the elevated GP activity or anoxic activation of GP. 相似文献
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We have investigated the floral ontogeny of Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis (of the eucalypt group, Myrtaceae) using scanning electron microscopy and light microscopy. Several critical characters for establishing relationships between these genera and to the eucalypts have been determined. The absence of compound petaline primordia in Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis excludes these taxa from the eucalypt clade. Post-anthesis circumscissile abscission of the hypanthium above the ovary in Stockwellia, Eucalyptopsis and Allosyncarpia is evidence that these three taxa form a monophyletic group; undifferentiated perianth parts and elongated fusiform buds are characters that unite Stockwellia and Eucalyptopsis as sister taxa. No floral characters clearly associate Arillastrum with either the eucalypt clade or the clade of Stockwellia, Eucalyptopsis and Allosyncarpia.We gratefully acknowledge Clyde Dunlop and Bob Harwood (Northern Territory Herbarium) for collecting specimens of Allosyncarpia, and Bruce Gray (Atherton) for collecting specimens of Stockwellia. The Australian National Herbarium (CANB) kindly lent herbarium specimens of Eucalyptopsis for examination. This research was supported by a University of Melbourne Research Development Grant to Andrew Drinnan. 相似文献
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Background
Gonadotropin releasing hormone (GnRH) is responsible for stimulation of gonadotropic hormone (GtH) in the hypothalamus-pituitary-gonadal axis (HPG). The regulatory mechanisms responsible for brain specificity make the promoter attractive for in silico analysis and reporter gene studies in zebrafish (Danio rerio).Results
We have characterized a zebrafish [Trp7, Leu8] or salmon (s) GnRH variant, gnrh 3. The gene includes a 1.6 Kb upstream regulatory region and displays the conserved structure of 4 exons and 3 introns, as seen in other species. An in silico defined enhancer at -976 in the zebrafish promoter, containing adjacent binding sites for Oct-1, CREB and Sp1, was predicted in 2 mammalian and 5 teleost GnRH promoters. Reporter gene studies confirmed the importance of this enhancer for cell specific expression in zebrafish. Interestingly the promoter of human GnRH-I, known as mammalian GnRH (mGnRH), was shown capable of driving cell specific reporter gene expression in transgenic zebrafish.Conclusions
The characterized zebrafish Gnrh3 decapeptide exhibits complete homology to the Atlantic salmon (Salmo salar) GnRH-III variant. In silico analysis of mammalian and teleost GnRH promoters revealed a conserved enhancer possessing binding sites for Oct-1, CREB and Sp1. Transgenic and transient reporter gene expression in zebrafish larvae, confirmed the importance of the in silico defined zebrafish enhancer at -976. The capability of the human GnRH-I promoter of directing cell specific reporter gene expression in zebrafish supports orthology between GnRH-I and GnRH-III.20.
Recently, the prenyltransferase SirD was found to be responsible for the O-prenylation of tyrosine in the biosynthesis of sirodesmin PL in Leptosphaeria maculans. In this study, the behavior of SirD towards phenylalanine/tyrosine and tryptophan derivatives was investigated. Product
formation has been observed with 12 of 19 phenylalanine/tyrosine derivatives. It was shown that the alanine structure attached
to the benzene ring and an electron donor, e.g., OH or NH2, at its para-position are essential for the enzyme activity. Modifications were possible both at the side chain and the benzene ring.
Enzyme products from seven phenylalanine/tyrosine derivatives were isolated and characterized by MS and NMR analyses including
HSQC and HMBC and proven to be O- or N-prenylated derivatives at position C4 of the benzene rings. K
M
values of six selected derivatives were found in the range of 0.10–0.68 mM. Catalytic efficiencies (K
cat/K
M
) were determined in the range of 430–1,110 s−1·M−1 with l-tyrosine as the best substrate. In addition, 7 of 14 tested tryptophan analogs were also accepted by SirD and converted to
C7-prenylated derivatives, which was confirmed by comparison with products obtained from enzyme assays using a 7-dimethylallyltryptophan
synthase 7-DMATS from Aspergillus fumigatus. 相似文献