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971.
Research has revealed that most chlorophyllous explants/plants in vitro have the ability to grow photoautotrophically (without
sugar in the culture medium), and that the low or negative net photosynthetic rate of plants in vitro is not due to poor photosynthetic
ability, but to the low CO2 concentration in the air-tight culture vessel during the photoperiod. Moreover, numerous studies have been conducted on improving
the in vitro environment and investigating its effects on growth and development of cultures/plantlets on nearly 50 species
since the concept of photoautotrophic micropropagation was developed more than two decades ago. These studies indicate that
the photoautotrophic growth in vitro of many plant species can be significantly promoted by increasing the CO2 concentration and light intensity in the vessel, by decreasing the relative humidity in the vessel, and by using a fibrous
or porous supporting material with high air porosity instead of gelling agents such as agar. This paper reviews the development
and characteristics of photoautotrophic micropropagation systems and the effects of environmental conditions on the growth
and development of the plantlets. The commercial applications and the perspective of photoautotrophic micropropagation systems
are discussed. 相似文献
972.
973.
974.
Hsi-Feng Tu Chung-Ji Liu Che-Lun Chang Pei-Wen Wang Shou-Yen Kao Cheng-Chieh Yang En-Hao Yu Shu-Chun Lin Kuo-Wei Chang 《PloS one》2012,7(12)
MicroRNAs (miRNAs) play important roles in modulating the neoplastic process of cancers including head and neck squamous cell carcinoma (HNSCC). A genetic polymorphism (rs2292832, C>T) has been recently identified in the precursor of miR-149; nevertheless its clinicopathological implications remain obscure. In this study, we showed that miR-149 is down-regulated in HNSCC compared to normal mucosa and this is associated with a poorer patient survival. In addition, HNSCC patients with the T/T genotype have more advanced tumors and a worse prognosis. Multivariate analysis indicated that patients carried the T/T genotype have a 2.81-fold (95% CI: 1.58–4.97) increased risk of nodal metastasis and 1.66-fold (95% CI: 1.05–2.60) increased risk of mortality compared to other groups. T/T genotype also predicted the worse prognosis of buccal mucosa carcinoma subset of HNSCC. In vitro analysis indicated that exogenous miR-149 expression reduces the migration of HNSCC cells. Moreover, HNSCC cell subclones carrying the pri-mir-149 sequence containing the T variant show a low processing efficacy when converting the pre-mir-149 to mature miR-149. These findings suggest that miR-149 suppresses tumor cell mobility, and that the pre-mir-149 polymorphism may affect the processing of miR-149, resulting in a change in the abundance of the mature form miRNA, which, in turn, modulates tumor progression and patient survival. 相似文献
975.
976.
The incertae sedis Carpathoporella Dragastan, 1995, reported from the Lower Cretaceous of the Western Tethyan domain, is usually interpreted as remains of calcareous algae
(Dasycladales or Characeae). New thin-section material from the Aptian of Albania sheds light not only on its biogenic nature
but also on the morphological variability of this taxon. In fact, Carpathoporella represents the debris of colonial, bushy, most likely gorgonid octocorals with tuberculated spheroids that may be fused at
least near the basal root-like holdfast. Colony branching originates from longitudinally grooved calcareous branches or internodes.
Possible relationships to other Upper Cretaceous to Palaeogene genera are discussed and a revised critical inventory of Cretaceous
octocorals is presented. Due to the evidenced morphological features, Carpathoporella could either represent an ancestral isidid octocoral of the order Alcyonacea such as Moltkia Steenstrup or, due to the likely primary aragonitic skeletal mineralogy, a representative of Epiphaxum Lonsdale of the order Helioporacea. Due to morphological analogies, the new combination Carpathoporella elliotti (Radoičić) is proposed. In any case, the Lower Cretaceous record from Tethyan peri-reefal shallow-water carbonates is highlighted
since numerous skeletal findings of fossil gorgonid Octocorallia were so far only known from Upper Cretaceous and younger
strata of outer shelf environments of the boreal realm. The origin of deep-water Upper Cretaceous octocorals from Lower Cretaceous
shallow-water taxa such as Carpathoporella is proposed as a possible further example of onshore/offshore evolutionary pattern. 相似文献
977.
Plasmonic nanorods and their clusters are the fundamental units in plasmonic nanoantenna engineering. A theory that can predict the resonance of single nanorod already exists but is in lack for a heterodimer. Here, we propose a model combining the effective circuit theory for the response of spherical nanoparticles together with standard transmission line theory for hemispherically capped nanorod antennas. The resonances of multiple orders are predictable by defining the reflection phase at the terminals of such antennas, in both symmetric and asymmetric coupled nanorods. The theoretical results compare favorably with full-wave finite element numerical calculations. By the analytical formula, it is easy to control the length of the antennas for regulating the cooperative resonant properties and consequently the radiation characteristics of a nearby electric dipole. Consequently, we obtain both commensurate and incommensurate resonance features in such nanorod-based heterodimer antennas, showing respectively cumulative and selective responses from the individual nanorods. 相似文献
978.
RICHARD M. WEINSHILBOUM RICHARD KVETNANSKY JULIUS AXELROD IRWIN J. KOPIN 《Nature: New biology》1971,230(17):287-288
THE formation of the neurotransmitter noradrenaline from 3,4-dihydroxyphenylethylamine (dopamine) is catalysed by the enzyme dopamine-β-hydroxylase (DBH)1. This enzyme is associated both with the catecholamine-containing chromaffin granules in the adrenal medulla2,3 and with the vesicular structures in sympathetic nerve terminals which contain catecholamines4. Furthermore, DBH activity is released with catecholamines into the perfusate after stimulation of either the isolated perfused adrenal gland5 or the isolated perfused spleen6–8. DBH activity has been reported in the serum of both man and the rat9,10. This activity is similar to adrenal and sympathetic nerve DBH activity with regard to cofactor requirements, oxygen requirement and kinetic characteristics9,10. It has been suggested that serum DBH activity might be present as a result of release of enzyme with catecholamines from the adrenal glands and sympathetic nerves. If this is the case, serum DBH activity might be a useful and convenient index of sympathetic-adrenal activity. The work described here was undertaken to investigate both the source of the serum DBH and the effect on this activity of forced immobilization, a procedure which has been used as a model of stress and which has been shown to release catecholamines from the adrenal gland and increase catecholamine excretion11. 相似文献
979.
Protein is one of the three main storage chemical components in maize grains, and is negatively correlated with starch concentration
(SC). Our objective was to analyse the influence of genetic backgrounds on QTL detection for protein concentration (PC) and
to reveal the molecular genetic associations between PC and both SC and grain weight (GWP). Two hundred and eighty-four (Pop1)
and 265 (Pop2) F2:3 families were developed from two crosses between one high-oil maize inbred GY220 and two normal maize inbreds 8984 and 8622
respectively, and were genotyped with 185 and 173 pairs of SSR markers. PC, SC and GWP were evaluated under two environments.
Composite interval mapping (CIM) and multiple interval mapping (MIM) methods were used to detect single-trait QTL for PC,
and multiple-trait QTL for PC with both SC and GWP. No common QTL were shared between the two populations for their four and
one PC QTL. Common QTL with opposite signs of effects for PC and SC/GWP were detected on three marker intervals at bins 6.07–6.08,
8.03 and 8.03–8.04. Multiple-traits QTL mapping showed that tightly-linked QTL, pleiotropic QTL and QTL having effects with
opposite directions for PC and SC/GWP were all observed in Pop1, while all QTL reflected opposite effects in Pop2. 相似文献
980.