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21.
T. K. Golovko I. V. Dalke I. G. Zakhozhiy O. V. Dymova G. N. Tabalenkova 《Russian Journal of Plant Physiology》2011,58(4):549-559
Morphological and functional characteristics of Plantago media L. leaves were compared for plants growing at different light regimes on limestone outcrops in Southern Timan (62°45′N, 55°49′E).
The plants grown in open areas under exposure to full sunlight had small leaves with low pigment content and high specific
leaf weight; these leaves exhibited high photosynthetic capacity and elevated water use efficiency at high irradiance. The
maximum photochemical activity of photosystem II (F
v/F
m) in leaves of sun plants remained at the level of about 0.8 throughout the day. The photosynthetic apparatus of sun plants
was resistant to excess photosynthetically active radiation, mostly due to non-photochemical quenching of chlorophyll fluorescence
(qN). This quenching was promoted by elevated deepoxiation of violaxanthin cycle pigments. Accumulation of zeaxanthin, a photoprotective
pigment in sun plant leaves was observed already in the morning hours. The plant leaves grown in the shade of dense herbage
were significantly larger than the sun leaves, with pigment content 1.5–2.0 times greater than in sun leaves; these leaves
had low qN values and did not need extensive deepoxidation of violaxanthin cycle pigments. The data reveal the morphophysiological
plasticity of plantain plants in relation to lighting regime. Environmental conditions can facilitate the formation of the
ecotype with photosynthetic apparatus resistant to photoinhibition. Owing to this adjustment, hoary plantain plants are capable
of surviving in ecotopes with high insolation. 相似文献
22.
Golovko T. K. Dymova O. V. Tabalenkova G. N. 《Russian Journal of Plant Physiology》2004,51(5):604-608
A quantitative approach to the evaluation of source–sink relations in Ajuga reptans plants grown under the forest canopy (shade plants) and on an open plot (sun plants) was worked out in terms of growth characteristics, CO2 exchange, and carbon balance. Shade plants developed leaves with the relative and specific areas twice exceeding those of sun plants. Sun plants assimilated more carbon, using a significant part of it for the development of numerous runners. During a day, shade and sun plants produced 0.03 and 0.67 g of substrate, respectively. At the same time, forest (shade) plants spent 48% of assimilates for the respiration, in comparison with plants from the open plot that spent almost 70% of assimilates for respiration as they were greater in size. It was concluded, that light controls source–sink relations, which is a way of realization of the life strategy and a coordination mechanism of functional integrity of the plant organism. Light not only controls photosynthesis (source activity) but morphophysiological characteristics of plants with their hierarchical structure of sinks too. 相似文献
23.
24.
YURENA YANES ADAM TOMAŠOVÝCH MICHAŁ KOWALEWSKI CAROLINA CASTILLO JULIO AGUIRRE MARÍA R. ALONSO MIGUEL IBÁÑEZ 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2008,41(3):235-256
Quaternary aeolian deposits of the Canary Islands contain well‐preserved terrestrial gastropods, providing a suitable setting for assessing the taphonomy and compositional fidelity of their fossil record over ~13 kyr. Nine beds (12, 513 shells) have been analysed in terms of multivariate taphonomic and palaeoecological variables, taxonomic composition, and the stratigraphic and palaeontological context. Shells are affected by carbonate coatings, colour loss and fragmentation. Shell preservation is size‐specific: juveniles are less fragmented and show colour preservation more commonly than adults. In palaeosols, the adult shell density correlates negatively with the proportion of fragmented adults, negatively with the proportion of juveniles, and positively with the proportion of adults with coatings. High bioturbation intensity in palaeosols is associated with low shell fragmentation and high proportion of shells with coatings. These relationships imply that high adult density in palaeosols was driven by an increase in shell production rate (related to a decrease in predation rates on adults and a decrease in juvenile mortality) and a decrease in shell destruction rate (related to an increase in durability enhanced by carbonate precipitation). In dunes, the relationships between taphonomic alteration, shell density and bioturbation are insignificant. However, dune assemblages are characterized by a lower frequency of shells with coatings and higher rates of colour loss, indicating lower shell durability in dunes than in palaeosols. Additionally, non‐random differences in the coating proportion among palaeosols imply substantial temporal variation in the rate of carbonate crust formation, reflecting long‐term changes in bioturbation intensity that covaries positively with shell preservation. Dunes and palaeosols do not differ in species abundances despite differences in the degree of shell alteration, suggesting that both weakly and strongly altered assemblages offer data with a high compositional fidelity. Carbonate‐rich terrestrial deposits originating in arid conditions can enhance the preservation of gastropods and result in fossil assemblages that are suitable for palaeoecological and palaeoenvironmental studies of terrestrial ecosystems. 相似文献
25.
Applications of nanoparticles in biology and medicine 总被引:1,自引:0,他引:1
Salata O 《Journal of nanobiotechnology》2004,2(1):3
Nanomaterials are at the leading edge of the rapidly developing field of nanotechnology. Their unique size-dependent properties
make these materials superior and indispensable in many areas of human activity. This brief review tries to summarise the
most recent developments in the field of applied nanomaterials, in particular their application in biology and medicine, and
discusses their commercialisation prospects. 相似文献
26.
Russian Journal of Plant Physiology - The content and composition of photosynthetic pigments in 160 plant species representing the native flora of the taiga zone in European Northeast Russia were... 相似文献
27.
Mechanisms of adaptation of the photosynthetic apparatus at the level of pigment complex in a shade-tolerant bugle plant (Ajuga reptans L.) grown at full solar irradiation in an open plot were studied. In “sun” plants, the content of photosynthetic pigments decreased markedly as compared to “shade” plants grown under a forest canopy at 5–10% of the full solar irradiation. In leaves of sun plants, the portion of β-carotene and lutein in the carotenoid spectrum was higher than in shade plant leaves, antheraxanthin and zeaxanthin were present, and de-epoxidation of violaxanthin was by an order of magnitude higher in sun plant leaves reaching 40%. The data obtained indicate the role of the violaxanthin cycle in the protection of photosynthetic apparatus in a shade-tolerant plant against destruction under excessive irradiation. 相似文献
28.
ANDREA BEDNÁŘOVÁ NATRAJ KRISHNAN I‐CHENG CHENG JOSEF VEČEŘA HOW‐JING LEE DALIBOR KODRÍK 《Physiological Entomology》2013,38(1):54-62
The role of adipokinetic hormone (AKH) in counteracting oxidative stress elicited in the insect body is studied in response to exogenously applied hydrogen peroxide, an important metabolite of oxidative processes. In vivo experiments reveal that the injection of hydrogen peroxide (8 µmol) into the haemocoel of the firebug, Pyrrhocoris apterus L. (Heteroptera: Pyrrhocoridae) increases the level of AKH by 2.8‐fold in the central nervous system (CNS) and by 3.8‐fold in the haemolymph. The injection of hydrogen peroxide also increases the mortality of experimental insects, whereas co‐injection of hydrogen peroxide with Pyrap‐AKH (40 pmol) reduces mortality to almost control levels. Importantly, an increase in haemolymph protein carbonyl levels (i.e. an oxidative stress biomarker) elicited by hydrogen peroxide is decreased by 3.6‐fold to control levels when hydrogen peroxide is co‐injected with Pyrap‐AKH. Similar results are obtained using in vitro experiments. Oxidative stress biomarkers such as malondialdehyde and protein carbonyls are significantly enhanced upon exposure of the isolated CNS to hydrogen peroxide in vitro, whereas co‐treatment of the CNS with hydrogen peroxide and Pyrap‐AKH reduces levels significantly. Moreover, a marked decrease in catalase activity compared with controls is recorded when the CNS is incubated with hydrogen peroxide. Incubation of the CNS with hydrogen peroxide and Pyrap‐AKH together curbs the negative effect on catalase activity. Taken together, the results of the present study provide strong support for the recently published data on the feedback regulation between oxidative stressors and AKH action, and implicate AKH in counteracting oxidative stress. The in vitro experiments should facilitate research on the mode of action of AKH in relation to oxidative stress, and could help clarify the key pathways involved in this process. 相似文献
29.
O. A. Rozentsvet T. K. Golovko E. S. Bogdanova G. N. Tabalenkova V. N. Nesterov O. V. Dymova 《Biology Bulletin》2013,40(2):138-145
Polar glycerolipids and photosynthetic pigments of Plantago media L. plants, growing on limestone outcrops of the Southern Timan, have been studied. Leaves of plants growing on well insolated and heated slopes are characterized by an intensive lipoperoxidation; the accumulation of chlorophylls and carotenoids in these plants is 1.5–2 times less and the content of polar lipids is 15–20% less than in plants growing in dense grass at the bottom of slopes. The accumulation of some classes of glycerolipids in leaves in the daytime provides for stabilization of photosystem complexes and the formation of the pool of zeaxanthin, a protective xanthophyll. Changes in the content and ratio of lipids represent an important part of the adaptive reorganizations of the photosynthetic apparatus caused by excess radiation under natural conditions. 相似文献
30.
OI Klychnikov AV Drabkin OV Vasilenko YS Pavlov MS Trofimova IN Smolenskaya AA Rozenkranz AS Sobolev AV Babakov 《Biochemistry. Biokhimii?a》1998,63(9):1083-1089
Higher plant plasma membranes carry receptors of different affinity for the phytotoxin fusicoccin. Reception of fusicoccin involves proteins belonging to the highly conserved 14-3-3 family, but the complete structure of the fusicoccin receptor (FCR) is unknown. Using radiation inactivation analysis, we estimated the molecular masses of low-affinity and high-affinity FCR at 63 +/- 7 and 130 +/- 15 kD, respectively. The dose dependences of receptor inactivation indicate that microsomal specimens contain "silent" FCRs of 420 +/- 90 kD in amounts commensurate with that of the active FCRs. Both low- and high-affinity FCRs are inactivated by hydrolytic enzymes from the outer surface of the plasma membrane, and impairment of protoplast integrity causes an irreversible transition of the low-affinity binding site into the high-affinity one. A scheme is proposed for the organization of different types of FCR in the plasma membrane, implying that the membrane affinity for fusicoccin reflects the interaction between proteins in the FCR complex. 相似文献