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1.
Somatic embryogenesis in cultured plant cells is an ideal system for investigating the whole process of differentiation and development from single cells to whole plants, and especially the molecular mechanism of expression of totipotency. This review reports recent progress the studies on somatic embryogenesis. 相似文献
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Silene armeria was cultured on a medium containing 5% sucrose,and subjected to various light conditions. 1. Plants subjected to continuous illumination of far-red radiantenergy exclusive of other spectral regions initiated flowerbuds most readily. Far-red light mixed with other spectral regionswas less effective in promoting flowering than far-red lightalone. 2. The plants subjected to short photoperiods initiated no flowerbuds irrespective of the quality of light in the light period. 3. Red light was more effective in promoting flowering thandaylight fluorescent light but was less effective than the far-redlight. (Received October 8, 1960; ) 相似文献
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Glucose-6-phosphate dehydrogenase (E.C. 1.1.1.49) was partially purified by fractionation with ammonium sulfate and phosphocellulose chromatography. The Km value for glucose-6-phosphate is 1.6 × 10?4 and 6.3 × 10?4M at low (1.0–6.0 × 10?4M) and high (6.0–30.0 × 10?4M) concentrations of the substrate, respectively. The Km value for NADP+ is 1.4 × 10?5M. The enzyme is inhibited by NADPH, 5-phosphoribosyl-1-pyrophosphate, and ATP, and it is activated by Mg2+, and Mn2+. In the presence of NADPH, the plot of activity vs. NADP+ concentration gave a sigmoidal curve. Inhibition of 5-phosphoribosyl-1-pyrophosphate and ATP is reversed by Mg2+ or a high pH. It is suggested that black gram glucose-6-phosphate dehydrogenase is a regulatory enzyme of the pentose phosphate pathway. 相似文献
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A placebo is a substance or intervention believed to be inactive, but is administered by the healthcare professional as if it was an active medication. Unlike standard treatments, clinical use of placebo usually involves deception and is therefore ethically problematic. Our attitudes toward the clinical use of placebo, which inevitably includes deception or withholding information, have a tremendous effect on our practice regarding truth‐telling and informed consent. A casual attitude towards it weakens the current practice based on shared decision‐making and mutual trust between patients and healthcare professionals. Issues concerning the clinical use of placebo are thus intimately related to patient‐provider relationships, the public's trust in medicine, and medical education. A review of recent survey studies suggests that the clinical use of placebo appears to be fairly well accepted among healthcare professionals and is common in clinical settings in various countries. However, we think that an ethical discussion is urgently needed because of its controversial nature. If judged to be ethically wrong, the practice should end. In the present paper, we discuss the ethicality of the clinical use of placebo with deception and argue against it, concluding that it is unethical and should be banned. We will show that most arguments in favor of the clinical use of placebo can be refuted and are therefore incorrect or weak. These arguments will be presented and examined individually. Finally, we will briefly consider issues relevant to the clinical use of placebo without deception. 相似文献
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KEN‐ICHI HARANO SEIJI TANAKA MAKOTO TOKUDA HIROE YASUI SADAO WAKAMURA ATSUSHI NAGAYAMA YASUHIRO HOKAMA NORIO ARAKAKI 《Physiological Entomology》2010,35(3):287-295
The present study investigates the emergence of adult white grub beetles Dasylepida ishigakiensis Niijima et Kinoshita (Coleoptera: Scrabaeidae) from soil as well as their burrowing behaviours. ‘Standby behaviour’ (i.e. adults come to the soil surface where they expose their heads) is shown in the field and, along with emergence behaviour, is entrained by LD photocycles. These 24‐h rhythms persist after transfer to continuous light conditions for 2 days. By contrast, beetles transferred from LD photocycles to continuous dark conditions fail to show standby behaviour; thus, it appears to be manifested only in the presence of illumination. Under dark conditions, beetles emerge completely from the soil directly at the time when standby behaviour is otherwise expected to occur. Emerged adults then burrow back into the soil before dawn. Virgin and mated males, as well as virgin females, which are expected to emerge from the soil for mating on later evenings, burrow to a relatively shallow depth (<2 cm), whereas mated females burrow deeper (2–10 cm). Soil properties such as moisture, grain size, topography and temperature influence the burrowing behaviour and the depths that the beetles reach. 相似文献
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TAKEHIKO Y. ITO AYUMI OKADA BAYARBAATAR BUUVEIBAATAR BADAMJAV LHAGVASUREN SEIKI TAKATSUKI ATSUSHI TSUNEKAWA 《The Journal of wildlife management》2008,72(4):940-943
Abstract: We conducted a carcass census of Mongolian gazelles (Procapra gutturosa) along the Trans-Mongolian railroad in June 2005. We counted 241 gazelles that had died within the previous 12 months. Carcass numbers were greater on the southwestern side in the northern 3 zones, but we found carcasses only on the northeastern side in the southernmost zone. It suggests that impact of the railroad was stronger on one side and that the strength of this impact varied among regions. 相似文献
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It was found that light accelerates the swelling of spinachchloroplasts suspended in a solution containing NaCl and Tris-HCl,and that, in about 60 min, the swollen chloroplasts begin toshrink rapidly. The volume of chloroplasts reached, on swelling,270 per cent of the original volume on the average and thenshrank to 17 per cent. The rate of swelling and the maximumvolume were affected markedly by the tonicity of NaCl. NH4Cldid not affect the volume changes, while phenazine methosulfateaccelerated the swelling remarkably. The relationship betweenphotoshrinkage and this light-induced high-amplitude swellingwas discussed. (Received April 2, 1966; ) 相似文献
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WILHELM E. HAGIWARA NAOHIRO UWATOKO ATSUSHI SASAKI KAZUKI MATSUBARA† HIRONORI NAGANO KAZUMITSU ONISHI YOSHIO SANO 《Molecular ecology》2009,18(7):1537-1549
The complex structure of a single Mendelian factor widespread in the Asian cultivated rice ( Oryza sativa ) and its wild progenitor ( Oryza rufipogon ) that caused diverse phenotypes in the timing of flowering under natural field conditions was investigated in near isogenic lines. These near isogenic lines showed differences in flowering time despite all eight accessions collected from tropical regions possessing a recessive gene allelic to the se-pat gene. Fine mapping in two of these near-isogenic lines revealed that cultivated (Patpaku) and wild (W593) accessions had three and two linked quantitative trait loci (QTL) in the candidate regions, respectively, showing that Patpaku and W593 possessed linked QTLs with different effects in addition to the commonly-observed recessive gene ( se-pat ). Molecular dissection suggested that the tandemly duplicated FT-like genes ( Hd3a and RFT1 ) could be the candidate genes for these QTLs. Interestingly, the linked QTLs differed in their epistases, degree of dominance, and genotype × environment interactions. The nucleotide sequences showed that RFT1 has diverged more rapidly than Hd3a during rice evolution, suggesting phenotypic diversification of the two genes. Phylogenetic analysis implied that the se-pat + alleles might have emerged in different lineages within O. sativa . The present results strongly suggest that nucleotide divergence and shuffling of the linked QTLs by recombination might have created novel Mendelian factors that probably contribute to responding to local environments. 相似文献