Masaru Kono

Bio: Masaru Kono is an academic researcher from University of Tokyo. The author has contributed to research in topics: Earth's magnetic field & Photoinhibition. The author has an hindex of 23, co-authored 53 publications receiving 1813 citations. Previous affiliations of Masaru Kono include Toyo University & Cooperative Institute for Research in Environmental Sciences.

Roles of the cyclic electron flow around PSI (CEF-PSI) and O₂-dependent alternative pathways in regulation of the photosynthetic electron flow in short-term fluctuating light in Arabidopsis thaliana.

Abstract: To assess the roles of the cyclic electron flow around PSI (CEF-PSI) and O2-dependent alternative pathways including the water‐water cycle in fluctuating light, we grew the wild type and pgr5 mutant of Arabidopsis thaliana in constant light, and measured Chl fluorescence and P700 parameters in their leaves in the fluctuating light alternating between 240 (HL) and 30mmol photons m � 2 s � 2 (LL) every 2min. At 20% O2, the photochemical quantum yield of PSII decreased, in particular in the pgr5 plants, soon after the start of the fluctuating light treatment. PSI of the pgr5 plants was markedly photoinhibited by this treatment for 42min. Slight PSI photoinhibition was also observed in the wild type. We measured energy sharing between PSII and PSI and estimated the PSI and PSII electron transport rates (ETRs). pgr5 showed larger energy allocation to PSI. In contrast to the wild type, the ratio of the PSI to the PSII ETR in pgr5 was higher in LL but lower in HL at 20% O2 due to PSI acceptor-side limitation. At 2.7% or 0% O2, the CEF-PSI of the pgr5 plants was enhanced, the acceptor-side limitation of PSI electron flow was released and PSI photoinhibition was not observed. The results suggest that the light fluctuation is a potent stress to PSI and that the CEF-PSI is essential to protect PSI from this stress.

Mountain building in the central Andes

Abstract: The Central Andes is the middle part of the Andean chain between about 13°S and 27°S, characterized by the parallel running high mountain chains (the Western and Eastern Cordilleras) at the edges of high plateaus with a height of about 4000 m and a width of 200 to 450 km (the Altiplano-Puna). From the examination of geophysical and geological data in this area, including earthquakes, deformation, gravity anomaly, volcanism, uplift history, and plate motion, we conclude that the continued plate subduction with domination of compressive stress over the entire arc system is the main cause of the tectonic style of the Central Andes. We propose that the present cycle of mountain building has continued in the Cenozoic with the most active phase since the Miocene, and that the present subduction angle (30°) is not typical in that period but that subduction with more shallowly dipping oceanic lithosphere has prevailed at least since the Miocene, because of the young and buoyant slab involved. This situation is responsible for the production of a broad zone of partial melt in the mantle above the descending slab. Addition of volcanic materials was not restricted to the western edge (where active volcanoes of the Western Cordillera exist) but extended to the western and central portion of the Altiplano-Puna. The western half of the Central Andes is essentially isostatic because the heat transferred with the volcanic activities softened the crust there. In the eastern edge, the thermal effect is small, and the crust is strongly pushed by the westward moving South American plate. This caused the shortening of crustal blocks due to reverse faulting and folding in the Eastern Cordillera and Amazonian foreland. The magmatism and crustal accretion are dominant at the western end of the mountain system and decrease eastward, while the compression and consequent crustal shortening are strongest at the eastern end and wane toward west. These two processes are superposed between the two mountain chains and form high plateaus there: the Altiplano of Bolivia and Peru and the Puna of Argentina. This interpretation is supported by the observation that (1) Neogene sedimentary formations have been uplifted to high elevations without heavy distortion in the Altiplano and the Western Cordillera, (2) no significant reverse fault systems are observed on the Altiplano, (3) Neogene volcanic rocks and volcanic centers since the Miocene are not restricted to the Western Cordillera but are widely distributed over most of the Altiplano, (4) most of the Altiplano is in a zone of high heat flow values, (5) thick Paleozoic rocks are strongly folded and faulted in the Eastern Cordillera with little volcanism and no large-scale plutonism in the Cenozoic age, (6) crustal earthquakes with reverse fault mechanisms are concentrated on the eastern flank of the Eastern Cordillera and Amazonian foreland, and (7) the crustal thickness suddenly decreases at the junction of the Eastern Cordillera and the Amazon Basin, exactly at the place of reverse earthquakes.

Long-term and short-term responses of the photosynthetic electron transport to fluctuating light.

Abstract: Light energy absorbed by chloroplasts drives photosynthesis. When absorbed light is in excess, the thermal dissipation systems of excess energy are induced and the photosynthetic electron flow is regulated, both contributing to suppression of reactive oxygen species production and photodamages. Various regulation mechanisms of the photosynthetic electron flow and energy dissipation systems have been revealed. However, most of such knowledge has been obtained by the experiments conducted under controlled conditions with constant light, whereas natural light condition is drastically fluctuated. To understand photosynthesis in nature, we need to clarify not only the mechanisms that raise photosynthetic efficiency but those for photoprotection in fluctuating light. Although these mechanisms appear to be well balanced, regulatory mechanisms achieving the balance is little understood. Recently, some pioneering studies have provided new insight into the regulatory mechanisms in fluctuating light. In this review, firstly, the possible mechanisms involved in regulation of the photosynthetic electron flow in fluctuating light are presented. Next, we introduce some recent studies focusing on the photosynthetic electron flow in fluctuating light. Finally, we discuss how plants effectively cope with fluctuating light showing our recent results.

Some global features of palaeointensity in geological time

Abstract: SUMMARY A global palaeointensity data base was constructed from all published data from volcanic rocks in geological time older than 0.03 Ma. The data base contains a total of 1123 flow mean data retrieved from 83 original papers. Various features of the Earth's dipole moment were examined from the data which are based on Thellier and Shaw methods. Long-term variation of the Earth's dipole moment seems to have existed in the past 300 Ma with a broad minimum at 120–180 Ma as suggested by Prevot et al. (1990). However, due to limited site distribution we cannot regard this Mesozoic dipole low as being completely established. Precambrian palaeointensity data are still insufficient to conclude any long-term variation in this time range, although the geodynamo processes of moderate magnitude definitely existed in the early time of the Earth's history. The χ2 test was applied to the distribution of the virtual dipole moment for the past 5 Ma in which the transitional data were excluded; the results indicate that the distribution of virtual dipole moment is better represented by a log-normal distribution rather than a normal distribution, and this tendency seems to be true for the past 20 Ma. The relation of mean palaeointensity versus palaeomagnetic colatitude was examined for the past 10 Ma for the data excluding transitions. The relation is concordant with a theoretical curve from a geocentric axial dipole. This reconfirms that the dipole field was dominant in the past geomagnetic field, which is the dipole hypothesis in palaeomagnetism. On the other hand, the virtual dipole moment is much smaller for transitional palaeomagnetic fields, and a virtual geomagnetic pole lower than 45° seems to be a reasonable criterion to be categorized as a transition. The mean dipole moment for the pole latitude of 30°N-50°N band is larger than that for 30°S-50°S, indicating that there might have been a persistent asymmetry of palaeointensity between normal and reversed states, or some kind of geometrical asymmetry between the Northern and Southern Hemispheres.

Cenozoic Tectonics of Asia: Effects of a Continental Collision: Features of recent continental tectonics in Asia can be interpreted as results of the India-Eurasia collision.

Abstract: Stable URL:http://links.jstor.org/sici?sici=0036-8075%2819750808%293%3A189%3A4201%3C419%3ACTOAEO%3E2.0.CO%3B2-NScience is currently published by American Association for the Advancement of Science.Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available athttp://www.jstor.org/about/terms.html. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtainedprior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content inthe JSTOR archive only for your personal, non-commercial use.Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained athttp://www.jstor.org/journals/aaas.html.Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printedpage of such transmission.The JSTOR Archive is a trusted digital repository providing for long-term preservation and access to leading academicjournals and scholarly literature from around the world. The Archive is supported by libraries, scholarly societies, publishers,and foundations. It is an initiative of JSTOR, a not-for-profit organization with a mission to help the scholarly community takeadvantage of advances in technology. For more information regarding JSTOR, please contact support@jstor.org.http://www.jstor.orgFri Jan 25 16:37:09 2008

Magmatism at rift zones: The generation of volcanic continental margins and flood basalts

Abstract: When continents rift to form new ocean basins, the rifting is sometimes accompanied by massive igneous activity. We show that the production of magmatically active rifted margins and the effusion of flood basalts onto the adjacent continents can be explained by a simple model of rifting above a thermal anomaly in the underlying mantle. The igneous rocks are generated by decompression melting of hot asthenospheric mantle as it rises passively beneath the stretched and thinned lithosphere. Mantle plumes generate regions beneath the lithosphere typically 2000 km in diameter with temperatures raised 100–200°C above normal. These relatively small mantle temperature increases are sufficient to cause the generation of huge quantities of melt by decompression: an increase of 100°C above normal doubles the amount of melt whilst a 200°C increase can quadruple it. In the first part of this paper we develop our model to predict the effects of melt generation for varying amounts of stretching with a range of mantle temperatures. The melt generated by decompression migrates rapidly upward, until it is either extruded as basalt flows or intruded into or beneath the crust. Addition of large quantities of new igneous rock to the crust considerably modifies the subsidence in rifted regions. Stretching by a factor of 5 above normal temperature mantle produces immediate subsidence of more than 2 km in order to maintain isostatic equilibrium. If the mantle is 150°C or more hotter than normal, the same amount of stretching results in uplift above sea level. Melt generated from abnormally hot mantle is more magnesian rich than that produced from normal temperature mantle. This causes an increase in seismic velocity of the igneous rocks emplaced in the crust, from typically 6.8 km/s for normal mantle temperatures to 7.2 km/s or higher. There is a concomitant density increase. In the second part of the paper we review volcanic continental margins and flood basalt provinces globally and show that they are always related to the thermal anomaly created by a nearby mantle plume. Our model of melt generation in passively upwelling mantle beneath rifting continental lithosphere can explain all the major rift-related igneous provinces. These include the Tertiary igneous provinces of Britain and Greenland and the associated volcanic continental margins caused by opening of the North Atlantic in the presence of the Iceland plume; the Parana and parts of the Karoo flood basalts together with volcanic continental margins generated when the South Atlantic opened; the Deccan flood basalts of India and the Seychelles-Saya da Malha volcanic province created when the Seychelles split off India above the Reunion hot spot; the Ethiopian and Yemen Traps created by rifting of the Red Sea and Gulf of Aden region above the Afar hot spot; and the oldest and probably originally the largest flood basalt province of the Karoo produced when Gondwana split apart. New continental splits do not always occur above thermal anomalies in the mantle caused by plumes, but when they do, huge quantities of igneous material are added to the continental crust. This is an important method of increasing the volume of the continental crust through geologic time.

Uplift of the Central Andean Plateau and bending of the Bolivian orocline

Abstract: Topographic data are combined with data on structure magmatism, seismicity, and paleomagnetism to support a simple kinematical model for the late Cenozoic evolution of the central Andes. The model interrelates Andean uplift, a changing geometry of the subducted Nazca plate, and a changing outline of the leading edge of the South American plate. It is argued that the late Cenozoic uplift of the Andes is a result of thermal thinning of the lithosphere and crustal thickening produced by crustal shortening.

Generation of sodium-rich magmas from newly underplated basaltic crust

Abstract: SODIUM-RICH rocks of trondhjemite–tonalite–dacite (TTD) or –granodiorite (TTG) suites form much of Precambrian continental crust1. They are thought to have formed by partial melting of subducted oceanic crust2,3—a process that would have been much more widespread early in Earth history than at present, owing to the higher thermal gradients prevailing at that time4. Phanerozoic TTD suites do exist, however, and seem also to relate to subduction zones5. Defant and Drummond6 proposed that these suites form where young (<25 Myr), hot oceanic lithosphere is subducted and melts, thus locally simulating the conditions that led to widespread crustal growth in the Archaean. Here we describe plutonic and volcanic rocks from the Cordillera Blanca complex in Peru, which have characteristics of the high-Al TTD suite but which were produced above a subduction zone containing a 60-Myr-old slab. We present evidence that the complex formed by partial melting of newly underplated basaltic crust, and argue that this mechanism should be considered more generally as an additional way of generating sodium-rich arc magmas.