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1.
A. Q. Hurtado A. T. Critchley A. Trespoey G. Bleicher-Lhonneur 《Journal of applied phycology》2008,20(5):551-555
Kappaphycus striatum var. sacol was grown in two separate studies: (1) at two stocking densities, and (2) at four different depths, each for three different
durations of culture (30, 45 and 60 days) in order to determine the growth rate of the seaweed and evaluate the carrageenan
content and its molecular weight. The results demonstrated that stocking density, duration of culture and depth significantly
(P < 0.01) affected the growth rate, carrageenan content and molecular weight of K. striatum var. sacol. Decreasing growth rate was observed at both stocking densities and at four depths as duration of culture increased. A lower
stocking density (500 g m−1line−1) showed a higher growth rate for the shortest durations, i.e. 30 days, as compared to those grown at a higher density. Likewise,
decreasing growth rate was observed as depth increased, except at 50 cm after 60 days of culture. A 45-day culture period
produced the highest molecular weight at both stocking densities (500 g m−1line−1 = 1,079.5 ± 31.8 kDa, 1,000 g m−1line−1 = 1,167 ± 270.6 kDa). ‘Sacol’ grown for 30 days at 50 cm (1,178 kDa) to 100 cm (1,200 kDa) depth showed the highest values
of molecular weight of carrageenan extracted. The results suggested that K. striatum var. sacol is best grown at a stocking density of 500 g m−1line−1, at a depth of 50–100 cm, and for a duration of 30 days in order to provide the highest growth rate, carrageenan content
and molecular weight. 相似文献
2.
An in vitro method for propagation of Holarrhena antidysenterica Wall. has been developed using nodal explants from mature trees growing in the field. Irrespective of concentrations and
combinations of growth regulators used, the axillary and terminal buds sprouted and elongated when inoculated on Murashige
and Skoog (MS) medium. The highest numbers of shoots were formed when sprouted shoots were subcultured from MS basal medium
onto MS medium containing 2 mg dm−3 N6-benzyladenine (BA) and 0.5 mg dm−3 α-naphthalene acetic acid (NAA). The shoot number further increased upon subculture on MS medium containing 0.5 mg dm−3 BA. By repeated sub-culturing of shoots derived from nodal axillary buds, a high frequency multiplication rate was established.
The elongated shoots were excised and rooted in auxin free MS basal medium. Ex vitro rooting of in vitro formed shoots was achieved upon dipping the microshoots for 2 min in 2 mg dm−3 of indole-3-butyric acid solution. Successful field establishment and high (80–90 %) survival of plants was observed. 相似文献
3.
In the wild type strain (stock no. 1227) of Thermoactinomyces vulgaris, as reported earlier [Sinha and Singh (1980) Biochem. J. 190, 457–460], all phosphatase isoenzymes (three alkaline — AlpI,
AlpII and AlpIII, and one acidic — Acp) are present. However, the auxotrophic mutants, the strains 1286 (thi
−), 1279 (nic
−, ura
−) and 1278 (thi
−, ura
−) exhibited two alkaline phosphatase isoenzymes (AlpII and AlpIII), but AlpI was lacking. In the strain 1261 (nic
−, thi
−), only AlpIII was expressed, and AlpI and AlpII isoenzymes were missing. The results suggest that the strains, which require
either thiamine (1286 and 1278) or nicotinamide (1279) for their growth, were AlpI
− mutants; and the strain (1261), which requires both thiamine and nicotinamide for its growth, was AlpI
−/AlpII
− double mutant. There was no direct correlation between uracil auxotrophy and the expression of phosphatases. The uniform
expression of AlpIII and Acp in all the strains, irrespective of their nutrient requirements, suggest that these constitutive
phosphatases are species-specific. The specific activities of the thermophilic acid and alkaline phosphatases were maximum
in the wild type strain (1227) of T. vulgaris. The next in phosphatase activity was the strain 1279 (an AlpI
− mutant), followed by their decrease, in order, in the strains 1286 and 1278 (which were also AlpI
− mutants); while least activity of these enzymes was observed in the obligate thermophile strain 1261 (AlpI
−/AlpII
− double mutant). 相似文献
4.
A general in vitro cloning system was established for four Helleborus species: H. argutifolius, H. foetidus, H. niger and H. orientalis. The plant material was introduced in vitro from axillary buds. A Murashige and Skoog (MS)—based medium (Murashige and Skoog
1962) was used supplemented with 2% (w/v) sucrose, 2-isopentenyladenine (2-iP) and 6-benzylaminopurine (BA). Multiplication
rates depended on the genotype and varied from 1.3 for H. foetidus till 3.8 for H. niger. The first results showed that the rooting phase could be done ex vitro. Rooting was induced by a drench for one week in
a solution of indole-3-butyric acid (IBA -3 mg l−1) and 1-naphthaleneacetic acid (NAA-1 mg l−1) at 5°C. 相似文献
5.
John A. Macdonald 《Polar Biology》2007,30(6):797-807
As a part of the ICEFISH04 project on the RVIB Nathaniel B. Palmer, miniature end plate currents (MEPCs) were recorded from the extraocular muscles of Notothenia rossii captured at King Edward Point, South Georgia. A total of 1,176 MEPCs were recorded from the inferior oblique extraocular
muscles of four specimens, over a temperature range of 1–12°C. The MEPCs were normal in form, with a rapid quasi-linear increase
in inward current (typically <500 μs), followed by a slower exponential decay of the inward current to baseline. Exponential
decay rates were calculated for individual MEPCs by linear regression of the log-transformed data, and converted to exponential
time constants (τ). Only those MEPCs that fit the exponential model well, with r
2 ≥ 0.95 (or in some cases r
2 ≥ 0.99) were used for further calculations. At temperatures between 1 and 2°C, τ ranged from about 2,000 to 4,000 μs, similar to values extrapolated for temperate teleosts at the same temperature, but significantly
longer than τ from MEPCs of high-latitude Antarctic nototheniids. Between 11 and 12°C, τ values for the N. rossii MEPCS were mainly between 1,100 and 1,700 μs, giving a Q
10 of 2.05. An Arrhenius plot and linear regression were used to describe the effect of changing temperature on the decay phase
of the N. rossii MEPCs: −ln τ = 27.887−6078/K, yielding an Arrhenius temperature coefficient (μ or apparent E
a) of −50.5 ± 2.9 (95% CL) kJ mol−1 deg−1. When compared with other nototheniids, these results showed that the neuromuscular junctions of N. rossii are compensated for low temperature, but not to the same degree as those of high Antarctic species.
The ICEFISH Cruise (International Collaborative Expedition to collect and study Fish Indigenous to Sub-antarctic Habitats)
was conducted on board the RVIB Nathaniel B. Palmer in May to July 2004. For further information, please visit . 相似文献
6.
Qingxin Zhao Sheng Yuan Yuling Zhang Hong Zhu Chuanchao Dai Fang Yang Fengmin Han 《World journal of microbiology & biotechnology》2007,23(8):1057-1064
Pectate lyase A (PelA) of Aspergillus nidulans was successfully expressed in Escherichia coli and effectively purified using a Ni2+-nitrilotriacetate-agarose column. Enzyme activity of the recombinant PelA could reach 360 U ml−1 medium. The expressed PelA exhibited its optimum level of activity over the range of pH 7.5–10 at 50°C. Mn2+, Ca2+, Fe2+, Mg2+ and Fe3+ ions stimulated the pectate lyase activity, but Cu2+ and Zn2+ inhibited it. The recombinant PelA had a V
max of 77 μmol min−1 mg−1 and an apparent K
m of 0.50 mg ml−1 for polygalacturonic acid. Low-esterified pectin was the optimum substrate for the PelA, whereas higher-esterified pectin
was hardly cleaved by it. PelA efficiently macerated mung bean hypocotyls and potato tuber tissues into single cells. 相似文献
7.
Sadanand D. Sontakke Govindaswamy Umapathy Manoj S. Patil Sisinthy Shivaji 《European Journal of Wildlife Research》2009,55(4):357-361
Seventy-seven anaesthetic events were carried out in 22 captive adult Black bucks (Antilope cervicapra) of either sex with a combination of 2 mg kg−1 ketamine hydrochloride with 0.25 mg kg−1 xylazine hydrochloride using a dart delivered from a blowpipe. Randomised anaesthetised animals received an intravenous injection
of either yohimbine hydrochloride (0.125 or 0.25 mg kg−1) or tolazoline hydrochloride (1 or 2 mg kg−1) after 30–40 min of anaesthesia to antagonise the anaesthetic effects. Ketamine–xylazine induced smooth, rapid and reliable
anaesthesia within 5–7 min of darting with no clinical adverse effects and causalities during or post-anaesthesia. Yohimbine
failed to antagonise the anaesthetic effects of ketamine–xylazine in the Black buck. On the other hand, tolazoline was found
to be very effective in hastening recovery in dose-dependent manner within 0.5–1.5 min. This study documents the first report
of ketamine–xylazine anaesthesia and its antagonism by tolazoline in captive Black buck. 相似文献
8.
Two oligosaccharides, a heptasaccharide (HS) and an octasaccharide (OS), isolated from Paris polyphylla var. yunnanensis, stimulated the growth and saponin accumulation of Panax ginseng hairy roots at 5–30 mg l−1. HS and OS at 30 mg l−1, fed separately to hairy root cultures at 10 days post-inoculation, increased the root biomass dry weight by more than 70%
to ∼20 g l−1 from 13 g l−1 and the total saponin content of roots by more than 1-fold to ∼3.5% from 1.6% (w/w). The results suggest that the two oligosaccharides
may have plant growth-regulatory activity in plant tissue cultures. 相似文献
9.
Kameshnee Naidoo Manimaran Ayyachamy Kugen Permaul Suren Singh 《Bioprocess and biosystems engineering》2009,32(5):689-695
Xanthomonas campestris pv phaseoli produced an extracellular endoinulinase (9.24 ± 0.03 U mL−1) in an optimized medium comprising of 3% sucrose and 2.5% tryptone. X. campestris pv. phaseoli was further subjected to ethylmethanesulfonate mutagenesis and the resulting mutant, X. campestris pv. phaseoli KM 24 demonstrated inulinase production of 22.09 ± 0.03 U mL−1 after 18 h, which was 2.4-fold higher than that of the wild type. Inulinase production by this mutant was scaled up using
sucrose as a carbon source in a 5-L fermenter yielding maximum volumetric (21,865 U L−1 h−1) and specific (119,025 U g−1 h−1) productivities of inulinase after 18 h with an inulinase/invertase ratio of 2.6. A maximum FOS production of 11.9 g L−1 h−1 and specific productivity of 72 g g−1 h−1 FOS from inulin were observed in a fermenter, when the mutant was grown on medium containing 3% inulin and 2.5% tryptone.
The detection of mono- and oligosaccharides in inulin hydrolysates by TLC analysis indicated the presence of an endoinulinase.
This mutant has potential for large-scale production of inulinase and fructooligosaccharides. 相似文献
10.
V. D. Kreslavski I. R. Fomina A. A. Ivanov N. P. Tatarinzev A. A. Kosobryukhov K. Y. Biel S. K. Herbert 《Biophysics》2010,55(2):215-220
The joint effects of 0.5 M NaCl and light of different intensities on the activity of the photosynthetic apparatus and ATP
content in cells of the katG
− mutant of cyanobacterium Synechocystis sp. PCC 6803 have been studied. The mutant demonstrated a higher photoinhibition rate and a slower rate of recovery compared
with the wild type, as shown by measurements of the CO2-dependent O2 production and delayed fluorescence of Chl a. The presence of 0.5 M NaCl in the incubation medium caused equal photoinhibition of the photosynthetic apparatus at I = 1200 μE m−2 s−1 in the mutant and wild-type cells. At I = 2400 μE m−2 s−1, we observed stronger inhibition and slower recovery of the photosynthetic apparatus in the katG
− mutant than in wild-type cells. The data obtained evidence an important role of catalase-peroxidase in the system of reparation
of the photosynthetic apparatus damaged by high-intensity light, especially at the background of NaCl stress. 相似文献
11.
12.
The influence of sugars and growth regulators on shoot and root growth of Dactylorhiza species was studied under in vitro conditions. The seedling development was stimulated with the application of glucose and sucrose at concentration of 10 g
dm−3 each. The improvement of shoot growth rate and shoot length was enhanced by cytokinins N
6-(2-isopentenyl)adenine or N
6-benzyladenine and their combination with auxin indolebutyric acid (IBA). The root growth rate and root length of seedlings
increased in the presence of IBA and α-naphthaleneacetic acid. Individual Dactylorhiza species showed statistically significant differences in shoot and root development depending on sugar and growth regulator
combinations. 相似文献
13.
T. Zhang 《In vitro cellular & developmental biology. Plant》2007,43(2):91-94
This study investigated the factors affecting in vitro flowering of Perilla frutescens. The shoots regenerated from cotyledonary and hypocotyl explants cultured on Murashige and Skoog (MS) medium supplemented
with benzyladenine (BA) and indole-3-acetic acid, each at 0.5 mg l−1, were excised and transferred to MS medium containing 30 g l−1 of sucrose, 8.25 g l−1 of ammonium nitrate, and 1.0 mg l−1 of BA. After 40 d of culture, 86.2% of shoots flowered and most of which self-fertilized in vitro and produced mature fruits with viable seeds. These seeds were germinated and plants were grown to maturity and flowered
in soil under greenhouse conditions. The in vitro flowering system reported in this study may facilitate rapid breeding of P. frutescens and offers a model system for studying the physiological mechanism of flowering. 相似文献
14.
A high-frequency and simple procedure for Agrobacterium tumefaciens-mediated genetic transformation of the medicinal plant Salvia miltiorrhiza was developed. Leaf discs were pre-cultured on MS medium supplemented with 6.6 μmol l−1 BAP and 0.5 μmol l−1 NAA for one day, then co-cultured with A. tumefaciens strain EHA105 harboring the plasmid pCAMBIA 2301 for three days on the same medium. Regenerated buds were obtained on selection
medium (co-culture medium supplemented with 60 mg l−1 kanamycin and 200 mg l−1 cefotaxime) after two cycles’ culture of 10 days each and then transferred to fresh MS medium with 60 mg l−1 kanamycin for rooting. Fifteen days later, the rooted plantlets were obtained and then successfully transplanted to soil.
The transgenic nature of the regenerated plants was confirmed by PCR, Southern hybridization analysis and GUS histochemical
assay. Averagely, 1.1 independent verified transgenics per explant plated were obtained through this protocol. Adopting this
procedure, positive transformed plants could be obtained within 2–3 months from mature seeds germination to transplant to
soil, and more than 1,000 transgenic plants with several engineered constructs encoding different genes of interest were produced
in our lab in the past two years. 相似文献
15.
Anber Hassanein Latifa Hamama Karine Loridon Noëlle Dorion 《Plant cell reports》2009,28(10):1521-1530
Direct genetic transformation of mesophyll protoplasts was studied in Pelargonium × hortorum. Calcein and green-fluorescent protein (GFP) gene were used to set up the process. Electroporation (three electric pulses
from a 33-μF capacitor in a 250-V cm−1 electric field) was more efficient than PEG 6000 for membrane permeation, protoplast survival and cell division. Transient
expression of GFP was detected in 33–36% of electroporated protoplasts after 2 days and further in colonies. A protoplast
suspension conductivity of >1,500 μS cm−1 allowed high colony formation and plant regeneration. Stable transformation was obtained using the plasmid FAJ3000 containing
uidA and nptII genes. When selection (50 mg l−1 kanamycin) was achieved 6 weeks after electroporation, regenerated shoots were able to grow and root on 100 mg l−1 kanamycin. The maximum transformation efficiency was 4.5%, based on the number of colonies producing kanamycin-resistant
rooted plants or 0.7% based on the number of cultured protoplasts. Polymerase chain reaction (PCR) analysis on in vitro micropropagated
plants showed that 18 clones out of 20 contained the nptII gene, while the uidA gene was absent. These results were confirmed after PCR analyses of five glasshouse-acclimatized clones. 相似文献
16.
Four temperature treatments were studied in the climate controlled growth chambers of the Georgia Envirotron: 25/20, 30/25,
35/30, and 40/35 °C during 14/10 h light/dark cycle. For the first growth stage (V3-5), the highest net photosynthetic rate
(P
N) of sweet corn was found for the lowest temperature of 28–34 μmol m−2 s−1 while the P
N for the highest temperature treatment was 50–60 % lower. We detected a gradual decline of about 1 P
N unit per 1 °C increase in temperature. Maximum transpiration rate (E) fluctuated between 0.36 and 0.54 mm h−1 (≈5.0–6.5 mm d−1) for the high temperature treatment and the minimum E fluctuated between 0.25 and 0.36 mm h−1 (≈3.5–5.0 mm d−1) for the low temperature treatment. Cumulative CO2 fixation of the 40/35 °C treatment was 33.7 g m−2 d−1 and it increased by about 50 % as temperature declined. The corresponding water use efficiency (WUE) decreased from 14 to
5 g(CO2) kg−1(H2O) for the lowest and highest temperature treatments, respectively. Three main factors affected WUE, P
N, and E of Zea: the high temperature which reduced P
N, vapor pressure deficit (VPD) that was directly related to E but did not affect P
N, and quasi stem conductance (QC) that was directly related to P
N but did not affect E. As a result, WUE of the 25/20 °C temperature treatment was almost three times larger than that of 40/35 °C temperature treatment. 相似文献
17.
Single-culture aerobic granules with <Emphasis Type="Italic">Acinetobacter calcoaceticus</Emphasis> 总被引:1,自引:0,他引:1
Aerobic granules are cultivated by a single bacterial strain, Acinetobacter calcoaceticus, in a sequencing batch reactor (SBR). This strain presents as a good phenol reducer and an efficient auto coagulator in the
presence of phenol, mediated by heat-sensitive adhesins proteins. Stable 2.3-mm granules were formed in the SBR following
a 7-week cultivation. These granules exhibit excellent settling attributes and degrade phenol efficiently at concentrations
of 250–2,000 mg l−1. The corresponding phenol degradation rate reached 993.6 mg phenol g−1 volatile suspended solids (VSS) day−1 at 250 mg l−1 phenol and 519.3 mg phenol g−1 VSS day−1 at 2,000 mg l−1 phenol concentration. Meanwhile, free A. calcoaceticus cells were fully inhibited at phenol >1,500 mg l−1. Denaturing gradient gel electrophoresis fingerprint profile demonstrated no genetic modification in the strain during aerobic
granulation. The present single-strain granules showed long-term structural stability and performed high phenol degrading
capacity and high phenol tolerance. The confocal laser scanning microscopic test revealed that live A. calcoaceticus cells principally distributed at 200–250 μm beneath the outer surface, with an extracellular polymeric substance layer covering
them to defend phenol toxicity. Autoaggregation assay tests demonstrated the possibly significant role of secreted proteins
on the formation of single-culture A. calcoaceticus granules. 相似文献
18.
The pre-steady states of Pseudomonas species lipase inhibitions by p-nitrophenyl-N-substituted carbamates (1–6) are composed of two steps: (1) formation of the non-covalent enzyme–inhibitor complex (E:I) from the inhibitor and the enzyme
and (2) formation of the tetrahedral enzyme–inhibitor adduct (E–I) from the E:I complex. From a stopped-flow apparatus, the
dissociation constant for the E:I complex, KS, and the rate constant for formation of the tetrahedral E–I adduct from the E:I complex, k2 are obtained from the non-linear least-squares of curve fittings of first-order rate constant (kobs) versus inhibition concentration ([I]) plot against kobs=k2+k2[I]/(KS+[I]). Values of pKS, and log k2 are linearly correlated with the σ* values with the ρ* values of −2.0 and 0.36, respectively. Therefore, the E:I complexes are more positive charges than the inhibitors due to
the ρ* value of −2.0. The tetrahedral E–I adducts on the other hand are more negative charges than the E:I complexes due to the
ρ* value of 0.36. Formation of the E:I complex from the inhibitor and the enzyme are further divided into two steps: (1) the
pre-equilibrium protonation of the inhibitor and (2) formation of the E:I complex from the protonated inhibitor and the enzyme. 相似文献
19.
Indeok Hwang Dilli Prasad Paudyal Seong-Ki Kim Hyeonsook Cheong 《Biotechnology and Bioprocess Engineering》2007,12(2):157-164
Inhibitors are very important in the study of hormone function. Brasinazole (Brz) is a specific inhibitor of brassinosteroids
(BRs) biosynthesis. To expand our knowledge of the molecular mechanisms of plant steroid signaling, we performed genetic screening
using medium containing Brz under dark conditions. Mutants insensitive to Brz developlonger hypocotyls than their wild type
counterparts. We isolatedabz453 as a Brz insensitive mutant. TAIL-PCR and the segregation ratio of T2 plants indicated a single T-DNA insertion at the 24-Sterol
C-methyltransferase (SMT2) gene in theabz453 mutant. Recapitulation for putative FCP serine phosphatase (FSP), the gene neighboringSMT2, indicated no significant phenotypes, but theSMT2 anti-sense (SMT2-AS) line developed longer hypocotyls than the wild type in medium containing Brz. Additionally, theSMT2-AS line displayed similar phenotypes to theabz453 line in soil including enhanced growth and smaller silique. Theabz453 andSMT2-AS mutants showed phenotypes similar to those of wild type in medium containing benzylaminopurine, pacrobutrazol and ACC (precursor
for ethylene) under dark conditions. However, when brassinolide (BL) dose response was observed, theabz453 andSMT2-AS lines showed higher sensitivity than wild type. Theabz453/det2 andabz453/bri1-119 double mutants showed enhanced growth compared to thedet2 andbri1-119 line under both dark and light conditions. Specially, in dark conditions double mutants displayed nearly 2- and 1.5-fold
longer hypocotyls thandet2 andbri1-119 plants. Brz insensitivity to theSMT2 knock-out mutant and phenotypes of double mutants indicate that not only do BRI1 and DET2 influence the BRs response, as
evidenced by hypocotyl elongation, but another sterol derived signals may also be affected in mutants, suggesting that another
pathway is involved in hypocotyl elongation due to SMT2. 相似文献
20.
Meiru Li Hongqing Li Huawu Jiang Xiaoping Pan Guojiang Wu 《Plant Cell, Tissue and Organ Culture》2008,92(2):173-181
Jatropha curcas contains high amounts of oil in its seed and has been considered for bio-diesel production. A transformation procedure for
J. curcas has been established for the first time via
Agrobacterium tumefaciens infection of cotyledon disc explants. The results indicated that the efficiency of transformation using the strain LBA4404
and phosphinothricin for selection was an improvement over that with the strain EHA105 and hygromycin. About 55% of the cotyledon
explants produced phosphinothricin-resistant calluses on Murashige and Skoog (MS) medium supplemented with 1.5 mg l−1 benzyladenine (BA), 0.05 mg l−1 3–indolebutyric acid (IBA), 1 mg l−1 phosphinothricin and 500 mg l−1 cefotaxime after 4 weeks. Shoots were regenerated following transfer of the resistant calli to shoot induction medium containing
1.5 mg l−1 BA, 0.05 mg l−1 IBA, 0.5 mg l−1 gibberellic acid (GA3), 1 mg l−1 phosphinothricin and 250 mg l−1 cefotaxime, and about 33% of the resistant calli differentiated into shoots. Finally, the resistant shoots were rooted on
1/2 MS media supplemented with 0.3 mg l−1 IBA at a rate of 78%. The transgenic nature of the transformants was demonstrated by the detection of β-glucuronidase activity
in the primary transformants and by PCR and Southern hybridization analysis. 13% of the total inoculated explants produced
transgenic plants after approximately 4 months. The procedure described will be useful for both, the introduction of desired
genes into J. curcas and the molecular analysis of gene function. 相似文献