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991.
Embryogenic callus in Catharanthus roseus was initiated from hypocotyl on Murashige and Skoog’s (MS) medium supplemented with 1.0–2.0 mg dm−3 of 2,4-dichlorophenoxyacetic acid (2,4-D) or chlorophenoxyacetic acid (CPA). Calli from other sources were non-embryogenic.
Numerous somatic embryos were induced from primary callus on MS medium suplemented with naphthalene acetic acid (NAA) within
two weeks of culture. Embryo proliferation was much faster on medium supplemented with 6-benzylaminopurine (BAP). After transfer
to medium with gibberellic acid (GA3, 1.0 mg dm− 3) mature green embryos were developed and germinated well into plantlets on MS liquid medium supplemented with 0.5 mg dm−3 BAP. Later, embryos with cotyledonary leaves were subjected to different auxins treatments for the development of roots.
Before transfer ex vitro, plantlets were cultivated on half strength MS medium containing 3 % sucrose and 0.5 mg dm−3 BAP for additional 2 weeks. Additionally, the effect of liquid medium has been evaluated at different morphogenetic stages. 相似文献
992.
Vishal Gupta Chitra Natarajan Kanika Kumar Radha Prasanna 《Journal of applied phycology》2011,23(1):73-81
A cyanobacterial strain (Anabaena laxa RPAN8) exhibiting fungicidal activity and β-1,3 and 1,4 endoglucanase activities was selected for identifying the gene(s)
involved. Functional analyses of the genomic library revealed that four clones (8, 64, 116, and 248) of RPAN8 exhibited fungicidal
activity and induced structural deformities in the cell wall of the growing mycelia of Pythium aphanidermatum. Higher expression of fungicidal and β-1,4 endoglucanase activities, along with low expression of β-1,3 endoglucanase activity,
was recorded in two E. coli clones (8 and 64). Clones 8 and 64 exhibited identical sequences while clones 116 and 248 were also similar. Bioinformatic
analyses were undertaken only for the two non-identical clones 8 and 116 which showed open reading frames (ORFs) of 348 (end 1) and 656 amino acid residues (end 2), respectively. The amino acid sequence analyses revealed that the end 1 encoding endoglucanases belonged to peptidase M20 family while end 2 showed significant similarities with several known genes. The putative promoters and ribosomal binding sites were identified
and amino acid exchanges were observed in both end 1 and 2. The presence of signal peptides of 24 and 20 amino acid residues respectively revealed the secretory nature of these
proteins. 相似文献
993.
The Golgi apparatus in plants is organized as a multitude of individual stacks that are motile in the cytoplasm and in close
association with the endoplasmic reticulum (ER) (Boevink et al. in Plant J 15:441–447, 1998). These stacks operate as a sorting centre for cargo molecules, providing modification and redirection to other organelles
as appropriate. In the post-Golgi direction, these include vacuole and plasma membrane, and specialized transport routes to
each are required to prevent mislocalization. Recent evidence in plant cells points to the existence of post-Golgi organelles
that function as intermediate stations for efficient protein traffic, as well as to the influence of small GTPases such as
Rabs and ARFs on post-Golgi trafficking. This review focuses on the latest findings on post-Golgi trafficking routes and on
the involvement of GTPases and their effectors on the trafficking of proteins in the plant secretory pathway.
Sally L. Hanton and Loren A. Matheson have contributed equally to this work. 相似文献
994.
Jianhua Luo Guangchao Liu Youmin Zhong Tianjun Jia Kaiyang Liu Ding Chen Guangming Zhong 《BMC microbiology》2007,7(1):38
Background
Although more than 100 Chlamydia pneumoniae hypothetical proteins have been predicted to be inclusion membrane proteins, only a few have been experimentally demonstrated to be in the inclusion membrane. Using antibodies raised with fusion proteins, we characterized four such hypothetical proteins encoded by two gene clusters (Cpn0146-147 and Cpn0284-285) in the C. pneumoniae genome. 相似文献995.
Eoghan M Cunnane John JE Mulvihill Hilary E Barrett Michael T Walsh 《Biomedical engineering online》2015,14(Z1):S7
Background
Due to the limited number of experimental studies that mechanically characterise human atherosclerotic plaque tissue from the femoral arteries, a recent trend has emerged in current literature whereby one set of material data based on aortic plaque tissue is employed to numerically represent diseased femoral artery tissue. This study aims to generate novel vessel-appropriate material models for femoral plaque tissue and assess the influence of using material models based on experimental data generated from aortic plaque testing to represent diseased femoral arterial tissue.Methods
Novel material models based on experimental data generated from testing of atherosclerotic femoral artery tissue are developed and a computational analysis of the revascularisation of a quarter model idealised diseased femoral artery from a 90% diameter stenosis to a 10% diameter stenosis is performed using these novel material models. The simulation is also performed using material models based on experimental data obtained from aortic plaque testing in order to examine the effect of employing vessel appropriate material models versus those currently employed in literature to represent femoral plaque tissue.Results
Simulations that employ material models based on atherosclerotic aortic tissue exhibit much higher maximum principal stresses within the plaque than simulations that employ material models based on atherosclerotic femoral tissue. Specifically, employing a material model based on calcified aortic tissue, instead of one based on heavily calcified femoral tissue, to represent diseased femoral arterial vessels results in a 487 fold increase in maximum principal stress within the plaque at a depth of 0.8 mm from the lumen.Conclusions
Large differences are induced on numerical results as a consequence of employing material models based on aortic plaque, in place of material models based on femoral plaque, to represent a diseased femoral vessel. Due to these large discrepancies, future studies should seek to employ vessel-appropriate material models to simulate the response of diseased femoral tissue in order to obtain the most accurate numerical results.996.
Above- and belowground biomass allocation not only influences growth of individual plants, but also influences vegetation
structures and functions, and consequently impacts soil carbon input as well as terrestrial ecosystem carbon cycling. However,
due to sampling difficulties, a considerable amount of uncertainty remains about the root: shoot ratio (R/S), a key parameter
for models of terrestrial ecosystem carbon cycling. We investigated biomass allocation patterns across a broad spatial scale.
We collected data on individual plant biomass and systematically sampled along a transect across the temperate grasslands
in Inner Mongolia as well as in the alpine grasslands on the Tibetan Plateau. Our results indicated that the median of R/S
for herbaceous species was 0.78 in China’s grasslands as a whole. R/S was significantly higher in temperate grasslands than
in alpine grasslands (0.84 vs. 0.65). The slope of the allometric relationship between above- and belowground biomass was
steeper for temperate grasslands than for alpine. Our results did not support the hypothesis that aboveground biomass scales
isometrically with belowground biomass. The R/S in China’s grasslands was not significantly correlated with mean annual temperature
(MAT) or mean annual precipitation (MAP). Moreover, comparisons of our results with previous findings indicated a large difference
between R/S data from individual plants and communities. This might be mainly caused by the underestimation of R/S at the
individual level as a result of an inevitable loss of fine roots and the overestimation of R/S in community-level surveys
due to grazing and difficulties in identifying dead roots. Our findings suggest that root biomass in grasslands tended to
have been overestimated in previous reports of R/S. 相似文献
997.
Given immunity’s general role in the organism’s economy—both in terms of its internal environment as well as mediating its external relations—immune theory has expanded its traditional formulation of preserving individual autonomy to one that includes accounting for nutritional processes and symbiotic relationships that require immune tolerance. When such a full ecological alignment is adopted, the immune system becomes the mediator of both defensive and assimilative environmental intercourse, where a balance of immune rejection and tolerance governs the complex interactions of the organism’s ecological relationships. Accordingly, immunology, which historically had affiliated with the biology of individuals, now becomes a science concerned with the biology of communities. With this translocation, the ontological basis of the organism is undergoing a profound change. Indeed, the recent recognition of the ubiquity of symbiosis has challenged the traditional notions of biological individuality and requires a shift in the metaphysics undergirding biology, in which a philosophy of the organism must be characterized by ecological dialectics “all-the-way-down.” 相似文献
998.
Tropospheric O3 and deposition of reactive N threaten the composition and function of natural and semi-natural vegetation even in remote
regions. However, little is known about effects of these pollutants individually or in combination on plant species in alpine
habitats. We analyzed 11 frequent plant species of a subalpine Geo-Montani-Nardetum pasture exposed at 2,000 m a.s.l. in the Swiss Alps during 3 years using a factorial free-air exposure system with three
concentrations of O3 and five rates of N application. The aim was to detect subtle effects on leaf chlorophyll and N concentrations, leaf weight,
specific leaf area (SLA), and δ18O and δ13C as proxies for gas exchange. We expected that the species’ responsiveness to O3 and N would be related to their functional traits and that N-induced changes in these traits would modify the species’ response
to O3 via increased growth and higher leaf conductance (g
s). Most species reacted to N supply with the accumulation of N and chlorophyll, but with no change in SLA, g
s, and growth, except Carex sempervirens which showed increased water use efficiency and leaf weight. Elevated O3 reduced g
s
in most species, but this was not related to a reduction in leaf weight, which was recorded in half of the species. Contrary to our expectation, the magnitude of the response to both O3 and N was not related to species-specific traits such as SLA or g
s. No pronounced O3 × N interactions were observed. In conclusion, since for most species neither N nor gas exchange limited growth, their short-term
response to O3 and N and to their combination was small. O3 × N interactive effects are expected to be more pronounced in habitats where species are more responsive to N due to favorable
growth conditions in terms of nutrient availability and temperature.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
999.
Facultative paedomorphosis is the ability of a salamander to either metamorphose into a terrestrial, metamorphic adult or
retain a larval morphology to become a sexually mature paedomorphic adult. It has been hypothesized that density and initial
body size variation within populations are instrumental in cueing metamorphosis or paedomorphosis in salamanders, yet few
studies have adequately tested these hypotheses in long-term experiments. Beginning in the spring of 2004, 36 experimental
ponds were used to manipulate three body size variation levels (low, medium, high) and two density levels (low, high) of Ambystoma talpoideum larvae. Larvae were individually marked using visible implant elastomers and collected every 2 weeks in order to measure
snout–vent length and mass. Bi-nightly sampling was used to collect new metamorphs as they appeared. Analysis revealed significant
effects of density, size variation and morph on body size of individuals during the summer. Individuals that metamorphosed
during the fall and following spring were significantly larger as larvae than those becoming paedomorphic across all treatments.
These results support the Best-of-a-Bad-Lot hypothesis, which proposes that the largest larvae metamorphose in order to escape
unfavorable aquatic habitats. Large larvae may metamorphose to leave aquatic habitats, regardless of treatment, due to the
colder climate and lower productivity found in Kentucky, which is in the northern-most part of A. talpoideum’s range. By maintaining a long-term experiment, we have provided evidence for the transition of both larvae and paedomorphs
into metamorphs during fall and spring metamorphosis events. Furthermore, the production of similar morphs under different
environmental conditions observed in this research suggests that the ecological mechanisms maintaining polyphenisms may be
more diverse that first suspected.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
1000.
Sodium dodecyl sulfate-polyacrylamide gel protein electrophoresis (SDS-PAGE) was carried out using different bacterial strains
of the photosynthetic sulfur bacteria Chlorobium, Thiocapsa, Thiocystis, and Chromatium cultured in the laboratory, and the natural blooms in two karstic lakes (Lake Cisó and Lake Vilar, NE Spain) where planktonic
photosynthetic bacteria (purple and green sulfur bacteria) massively developed accounting for most of the microbial biomass.
Several extraction, solubilization, and electrophoresis methods were tested to develop an optimal protocol for the best resolution
of the SDS-PAGE. Protein composition from different water depths and at different times of the year was visualized within
a molecular mass range between 100 and 15 kDa yielding up to 20 different protein bands. Protein banding patterns were reproducible
and changed in time and with depth in agreement with changes in photosynthetic bacteria composition. When a taxonomically
stable community was followed in time, differences were observed in the intensity but not in the composition of the SDS-PAGE
banding pattern. Three environmental variables directly related to the activity of sulfur bacteria (light, oxygen, and sulfide
concentrations) had a significant effect on protein banding patterns and explained 33% of the variance. Changes in natural
protein profiles of the bacterial blooms agreed with changes in species composition and in the in situ metabolic state of
the populations. 相似文献