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1.
Molecular evidence for the early evolution of photosynthesis 总被引：1，自引：0，他引：1
The origin and evolution of photosynthesis have long remained enigmatic due to a lack of sequence information of photosynthesis genes across the entire photosynthetic domain. To probe early evolutionary history of photosynthesis, we obtained new sequence information of a number of photosynthesis genes from the green sulfur bacterium Chlorobium tepidum and the green nonsulfur bacterium Chloroflexus aurantiacus. A total of 31 open reading frames that encode enzymes involved in bacteriochlorophyll/porphyrin biosynthesis, carotenoid biosynthesis, and photosynthetic electron transfer were identified in about 100 kilobase pairs of genomic sequence. Phylogenetic analyses of multiple magnesium-tetrapyrrole biosynthesis genes using a combination of distance, maximum parsimony, and maximum likelihood methods indicate that heliobacteria are closest to the last common ancestor of all oxygenic photosynthetic lineages and that green sulfur bacteria and green nonsulfur bacteria are each other's closest relatives. Parsimony and distance analyses further identify purple bacteria as the earliest emerging photosynthetic lineage. These results challenge previous conclusions based on 16S ribosomal RNA and Hsp60/Hsp70 analyses that green nonsulfur bacteria or heliobacteria are the earliest phototrophs. The overall consensus of our phylogenetic analysis, that bacteriochlorophyll biosynthesis evolved before chlorophyll biosynthesis, also argues against the long-held Granick hypothesis. 相似文献
2.
Brown NJ Newell CA Stanley S Chen JE Perrin AJ Kajala K Hibberd JM 《Science (New York, N.Y.)》2011,331(6023):1436-1439
C? photosynthesis allows increased photosynthetic efficiency because carbon dioxide (CO?) is concentrated around the key enzyme RuBisCO. Leaves of C? plants exhibit modified biochemistry, cell biology, and leaf development, but despite this complexity, C? photosynthesis has evolved independently in at least 45 lineages of plants. We found that two independent lineages of C? plant, whose last common ancestor predates the divergence of monocotyledons and dicotyledons about 180 million years ago, show conserved mechanisms controlling the expression of genes important for release of CO(2) around RuBisCO in bundle sheath (BS) cells. Orthologous genes from monocotyledonous and dicotyledonous C? species also contained conserved regulatory elements that conferred BS specificity when placed into C? species. We conclude that these conserved functional genetic elements likely facilitated the repeated evolution of C? photosynthesis. 相似文献
3.
Raible F Tessmar-Raible K Osoegawa K Wincker P Jubin C Balavoine G Ferrier D Benes V de Jong P Weissenbach J Bork P Arendt D 《Science (New York, N.Y.)》2005,310(5752):1325-1326
Previous genome comparisons have suggested that one important trend in vertebrate evolution has been a sharp rise in intron abundance. By using genomic data and expressed sequence tags from the marine annelid Platynereis dumerilii, we provide direct evidence that about two-thirds of human introns predate the bilaterian radiation but were lost from insect and nematode genomes to a large extent. A comparison of coding exon sequences confirms the ancestral nature of Platynereis and human genes. Thus, the urbilaterian ancestor had complex, intron-rich genes that have been retained in Platynereis and human. 相似文献
4.
质体乙酰辅酶A羧化酶(ACCase)催化长链脂肪酸的合成。编码小麦质体ACCase的基因(Acc-1)已用于一年生小麦的系统与进化研究,但还未有多年生物种相应的研究报道。本研究发现,Elymus wawawaiensis的Acc-1基因第8外显子和第7内含子与其他已知该序列相比除核苷酸替代外,多了176个碱基,从而与现有已知的一年生小麦相应序列有显著差异。在NCBI中对该序列和已报道的Acc-1基因相应序列blast比对后,结果表明与Hordeum vulgare Acc-1具有87.15%的最高相似性。以Panicum virgatum、Zea mays和Lolim rigidum为外类群,最大简约法(MP)和邻接法(NJ)对该基因和已报道的Acc-1基因分别构建系统进化树,其中E.wawawaiensis和H.vulgare形成一个分支,自展支持率100%。研究同时表明该基因在小麦族多年生物种系统与进化研究中有重要的应用前景。 相似文献
5.
Tandem duplication of D-loop and ribosomal RNA sequences in lizard mitochondrial DNA 总被引：18，自引：0，他引：18
Some Cnemidophorus exsanguis have mitochondrial DNA's (mtDNA's) that are 22.2 kilobases (kb) in size, whereas most have mtDNA's of 17.4 kb. Restriction site mapping, DNA transfer hybridization experiments, and electron microscopy show that the size increment stems from the tandem duplication of a 4.8-kb region that includes regulatory sequences and transfer and ribosomal RNA genes. This observation is notable in that sequences outside of the control region are involved in major length variation. Besides revealing a novel form of mtDNA evolution in animals, these duplications provide a useful system for investigating the molecular and evolutionary biology of animal mtDNA. 相似文献
6.
Horizontal gene transfer in metazoans has been documented in only a few species and is usually associated with endosymbiosis or parasitism. By contrast, in bdelloid rotifers we found many genes that appear to have originated in bacteria, fungi, and plants, concentrated in telomeric regions along with diverse mobile genetic elements. Bdelloid proximal gene-rich regions, however, appeared to lack foreign genes, thereby resembling those of model metazoan organisms. Some of the foreign genes were defective, whereas others were intact and transcribed; some of the latter contained functional spliceosomal introns. One such gene, apparently of bacterial origin, was overexpressed in Escherichia coli and yielded an active enzyme. The capture and functional assimilation of exogenous genes may represent an important force in bdelloid evolution. 相似文献
7.
The electron transfer through an organized organic monolayer of alkyl chains adsorbed on a silicon wafer has been studied. The silicon was used as an electrode in a three-electrode electrochemical cell, and the current versus voltage response was measured. The results show that when the chains in the monolayer are in the "all trans" configuration, the charge transfer efficiency is higher than when the chains have a "gauche" configuration. A mechanism rationalizing all the observations is suggested. 相似文献
8.
hyz@sohu.com 《勤云标准版测试》2006,(5)
利用光合细菌与大豆根瘤菌混合菌液处理的大豆,其固氮活性的生理生化指标较它们的纯培养物均有显著提高,说明光合细菌与大豆根瘤菌的固氮活性具有协同作用。主要对光合细菌与根瘤菌协同效应进行研究,包括不同比例的光合细菌与根瘤菌混合施用对大豆根系活力、叶片叶绿素含量和生物学特性的影响。结果证实:光合细菌与根瘤菌混合施用比例不同对大豆根系活力、叶片叶绿素含量和生物学特性提高程度也有所不同。从经济效益等多方面考虑,初步认为光合细菌与根瘤菌施用比例为2:1比较适合。 相似文献
9.
Hutter H Vogel BE Plenefisch JD Norris CR Proenca RB Spieth J Guo C Mastwal S Zhu X Scheel J Hedgecock EM 《Science (New York, N.Y.)》2000,287(5455):989-994
New proteins and modules have been invented throughout evolution. Gene "birth dates" in Caenorhabditis elegans range from the origins of cellular life through adaptation to a soil habitat. Possibly half are "metazoan" genes, having arisen sometime between the yeast-metazoan and nematode-chordate separations. These include basement membrane and cell adhesion molecules implicated in tissue organization. By contrast, epithelial surfaces facing the environment have specialized components invented within the nematode lineage. Moreover, interstitial matrices were likely elaborated within the vertebrate lineage. A strategy for concerted evolution of new gene families, as well as conservation of adaptive genes, may underlie the differences between heterochromatin and euchromatin. 相似文献
10.
对甘薯新品种福薯8号不同生长阶段的地上部、地下部生长发育特性进行了初步探讨。结果表明,福薯8号叶片功能强,茎叶前期生长快,后期不早衰;光合叶面积大、光合能力强、T/R值进展合理、同化物分配到块根的比率高;薯块后期膨大快,最终产量高。 相似文献
11.
Levy O Kaniewska P Alon S Eisenberg E Karako-Lampert S Bay LK Reef R Rodriguez-Lanetty M Miller DJ Hoegh-Guldberg O 《Science (New York, N.Y.)》2011,331(6014):175
Circadian regulation of plant-animal endosymbioses is complicated by a diversity of internal and external cues. Here, we show that stress-related genes in corals are coupled to the circadian clock, anticipating major changes in the intracellular milieu. In this regard, numerous chaperones are "hard-wired" to the clock, effectively preparing the coral for the consequences of oxidative protein damage imposed by symbiont photosynthesis (when O(2) > 250% saturation), including synexpression of antioxidant genes being light-gated. Conversely, central metabolism appears to be regulated by the hypoxia-inducible factor system in coral. These results reveal the complexity of endosymbiosis as well as the plasticity regulation downstream of the circadian clock. 相似文献
12.
A model of the evolution and radiative effects of a debris cloud from a hypothesized impact event at the Cretaceous-Tertiary boundary suggests that the cloud could have reduced the amount of light at the earth's surface below that required for photosynthesis for several months and, for a somewhat shorter interval, even below that needed for many animals to see. For 6 months to 1 year, the surface would cool; the oceans would cool only a few degrees Celsius at most, but the continents might cool a maximum of 40 Kelvin. Extinctions in the ocean may have been caused primarily by the temporary cessation of photosynthesis, but those on land may have been primarily induced by a combination of lowered temperatures and reduced light. 相似文献
13.
St Schell J 《Science (New York, N.Y.)》1987,237(4819):1176-1183
Transgenic plants are generated in nature by Agrobacterium tumefaciens, a pathogen that produces disease through the transfer of some of its own DNA into susceptible plants. The genes are carried on a plasmid. Much has been learned about how the plasmid is transferred, how the plasmid-borne genes are organized, regulated, and expressed, and how the bacteria's pathogenic effects are produced. The A. tumefaciens plasmid has been manipulated for use as a general vector for the transfer of specific segments of foreign DNA of interest (from plants and other sources) into plants; the activities of various genes and their regulation by enhancer and silencer sequences have been assessed. Future uses of the vector (or others like it that have different host ranges) by the agriculture industry are expected to aid in moving into vulnerable plants specific genes that will protect them from such killers as nonselective herbicides, insects, and viruses. 相似文献
14.
为研究人参叶片光合作用及其与某些生理特性的关系,测定了人参叶片的叶绿素含量、比叶重、净光合速率的生育期变化。结果表明:叶绿素含量与净光合速率呈正相关(r=0.77),比叶重与净光合速率呈负相关(r=-0.73)。绿果期是人参生长的关键时期,应采取适当措施促进此期的光合作用,提高人参产量。 相似文献
15.
林木遗传转化及其潜在生态风险研究进展 总被引：1，自引：0，他引：1
林木遗传转化技术近些年来得到了较大的发展,集中表现在转基因技术和目的基因两个方面。前者主要表现为多种措施联合使用,提高了遗传转化率;后者主要表现为应用于林木遗传转化的目的基因数量逐年增多,从原来的抗虫基因发展到现在的多个目的基因:木质素改良基因、花发育相关基因、生长相关基因及抗污染基因等;这些基因在不同的树种均有遗传转化成功的例子。转基因林木潜在生态风险研究主要集中在:基因的水平转移、基因的垂直流动及转基因对昆虫的影响等方面。初步的试验结果和理论分析认为,转基因林木的大田释放具有一定的生态潜在风险,需要对这种风险进行更深入、精确的评估。林木遗传工程及其生态安全性的研究需进一步努力解决的问题包括:1)林木遗传转化效率相对较低,特别是针叶树种,建立转基因体系还比较困难;2)林木树体高大,生长周期很长,外源基因在转基因植株中的时空表达特性还有待继续深入研究;3)比较系统的转基因林木田间释放和生态安全性试验数量还很少。 相似文献
16.
不同光照处理对烤烟光合作用日变化影响 总被引：7，自引：1，他引：6
对不同光照处理进行光合作用日变化研究表明,不同的光照处理对烟田小环境有着明显的影响,对烟叶净光合速率（Pn）、气孔导度（Gs）、胞间CO2浓度（Ci）和蒸腾速率（Tr）及其日变化规律有着较大的影响。不遮阳和65%遮阳处理的净光合速率日变化表现为明显的“双峰型”,而95%遮阳处理则表现为较为平缓的“单峰型”曲线;不同处理气孔导度日变化均表现为先下降后小幅度上升再下降的走势;各处理胞间CO2浓度日变化表现为先下降,到最后有一个比较明显的上升趋势;蒸腾速率日变化曲线与各处理气温日变化曲线基本一致,都呈现先上升后逐渐下降的趋势。另外,对各处理之间光合作用日变化差异做了较为详细的分析。 相似文献
17.
研究了小麦突变体返白系返白现象发生的生理基础及抑制春生分蘖的机制。结果表明，与对照相比，返白系小麦在返白过程中，气孔阻力增大，蒸腾、净光合及呼吸速率下降；叶片可溶性糖及ＡＴＰ含量降低、淀粉含量略有上升；复绿过程中上述变化均可逐渐恢复到对照的水平。分析认为，返白现象发生时，植株的生理活动减弱，有效地限制了春季无效分蘖的发生；复绿过程其生理活动又迅速增强。 相似文献
18.
Wang H Lin S Allen JP Williams JC Blankert S Laser C Woodbury NW 《Science (New York, N.Y.)》2007,316(5825):747-750
The initial electron transfer dynamics during photosynthesis have been studied in Rhodobacter sphaeroides reaction centers from wild type and 14 mutants in which the driving force and the kinetics of charge separation vary over a broad range. Surprisingly, the protein relaxation kinetics, as measured by tryptophan absorbance changes, are invariant in these mutants. By applying a reaction-diffusion model, we can fit the complex electron transfer kinetics of each mutant quantitatively, varying only the driving force. These results indicate that initial photosynthetic charge separation is limited by protein dynamics rather than by a static electron transfer barrier. 相似文献
19.
Berriman M Ghedin E Hertz-Fowler C Blandin G Renauld H Bartholomeu DC Lennard NJ Caler E Hamlin NE Haas B Böhme U Hannick L Aslett MA Shallom J Marcello L Hou L Wickstead B Alsmark UC Arrowsmith C Atkin RJ Barron AJ Bringaud F Brooks K Carrington M Cherevach I Chillingworth TJ Churcher C Clark LN Corton CH Cronin A Davies RM Doggett J Djikeng A Feldblyum T Field MC Fraser A Goodhead I Hance Z Harper D Harris BR Hauser H Hostetler J Ivens A Jagels K Johnson D Johnson J Jones K Kerhornou AX Koo H 《Science (New York, N.Y.)》2005,309(5733):416-422
African trypanosomes cause human sleeping sickness and livestock trypanosomiasis in sub-Saharan Africa. We present the sequence and analysis of the 11 megabase-sized chromosomes of Trypanosoma brucei. The 26-megabase genome contains 9068 predicted genes, including approximately 900 pseudogenes and approximately 1700 T. brucei-specific genes. Large subtelomeric arrays contain an archive of 806 variant surface glycoprotein (VSG) genes used by the parasite to evade the mammalian immune system. Most VSG genes are pseudogenes, which may be used to generate expressed mosaic genes by ectopic recombination. Comparisons of the cytoskeleton and endocytic trafficking systems with those of humans and other eukaryotic organisms reveal major differences. A comparison of metabolic pathways encoded by the genomes of T. brucei, T. cruzi, and Leishmania major reveals the least overall metabolic capability in T. brucei and the greatest in L. major. Horizontal transfer of genes of bacterial origin has contributed to some of the metabolic differences in these parasites, and a number of novel potential drug targets have been identified. 相似文献
20.
Wing polyphenism in ants evolved once, 125 million years ago, and has been a key to their amazing evolutionary success. We characterized the expression of several genes within the network underlying the wing primordia of reproductive (winged) and sterile (wingless) ant castes. We show that the expression of several genes within the network is conserved in the winged castes of four ant species, whereas points of interruption within the network in the wingless castes are evolutionarily labile. The simultaneous evolutionary lability and conservation of the network underlying wing development in ants may have played an important role in the morphological diversification of this group and may be a general feature of polyphenic development and evolution in plants and animals. 相似文献