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971.
The effects of temperature and nutrient availability on seasonal abundance were compared among Sargassum berberifolium J. Ag., S. polycystum C. Ag., S. siliquosum J. Ag., and S. sandei from a reef in southern Taiwan. Growth temperature limits and optimum were variable between species and between developmental stages. Growth temperature ranges agree with Sargassum periodicity except S. sandei. Sargassum siliquosum can tolerate high temperature as indicated by higher optimum temperature and tolerance limits. Temporal changes in tissue nutrient content and alkaline phosphatase activity and the results from nutrient enrichment bioassay show that S. sandei, S. berberifolium, and S. polycystum are P limited in the early growth period and then N limited, whereas S. siliquosum showed a contrasting trend, reflecting the type of nutrient limitation is variable by time and between species. A smaller nutrient threshold for maximum growth in S. berberifolium, S. polycystum, and S. siliquosum than in S. sandei and higher growth rate in S. berberifolium and S. polycystum indicate the higher growth vigor and nutrient utilization efficiency, the higher abundance. High N reserves in S. berberifolium and S. polycystum exposed to elevated seawater N in the early growth period supported the subsequent growth. The multiple regression analysis indicates that percent cover of S. siliquosum increased with increasing water temperature and dissolved inorganic nitrogen concentrations, whereas that of S. polycystum decreased with increasing water temperature. In conclusion, seasonal dynamics of Sargassum spp. from southern Taiwan are attributable to species and temporal variations in temperature limitation and nutrient utilization strategy. 相似文献
972.
The impact of variation in water temperature and dissolved oxygen on recovery of largemouth bass Micropterus salmoides from exercise was examined. For this, largemouth bass were first exercised and recovered for either 1, 2 or 4 h at ambient water temperatures (25° C) in fully oxygenated water. Results showed that exercise forced fish to utilize anaerobic metabolism to meet energy demands, and resulted in reductions in anaerobic energy stores adenosine triphosphate (ATP), Phosphocreatine (PCr) and glycogen. Exercise also resulted in a seven‐fold increase in lactate within white muscle. After 2 h of recovery in oxygenated water at acclimation temperature, physiological recovery from exercise was under way, and by 4 h most variables examined had returned to control levels. Next, largemouth bass were exercised at ambient temperatures and recovered for 2 h in environments with either elevated temperature (32° C), reduced temperature (14 and 20° C), hypoxia or hyperoxia. Both elevated and reduced temperature impaired recovery of tissue lactate and tissue ATP relative to fish recovered in water at acclimation temperature, while hyperoxic water impaired recovery of tissue ATP. Moderately hypoxic waters impaired the recovery of plasma glucose, plasma lactate and tissue PCr relative to fish recovered in fully oxygenated water. Results from this study are discussed in the context of critical oxygen and temperature guidelines for largemouth bass. In addition, several recommendations are made concerning remedial treatments used in livewells (tanks) during angling tournaments when fish are recovering from exercise associated with angling. 相似文献
973.
L. G. Quintanilla S. Pajarón E. Pangua J. Amigo 《Plant biology (Stuttgart, Germany)》2000,2(6):612-617
Abstract: Spore germination of Culcita macrocarpa C. Presl and Woodwardia radicans (L.) Sm. from nine populations at the northern limit of their distribution, in the northwest Iberian Peninsula, was investigated. In a first experiment, population type and temperature (10, 15, 20, and 25 °C) were both found to affect germination percentage and germination time significantly in both species. There were also significant interactions between the two factors with respect to the percentage germination of C. macrocarpa and the germination time of W. radicans. In C. macrocarpa there was an outstanding increase in germination time at 15 °C and, above all, at 10 °C, whereas in W. radicans the most remarkable result was the existence of two populations with especially low germination percentages. In a second experiment, germination of 20 individuals from each population of W. radicans was compared with similar inter-population differentiation. Although its variability possibly has a genetic basis, these species are able to germinate successfully, and it seems probable that the season in which it occurs depends more on spore release than on thermal conditions in the populations. The effect of temperature on germination in both species does not explain their coastal distribution. Temperature is probably more important in limiting other stages of the life cycle. 相似文献
974.
975.
TIMO DOMISCH LEENA FINÉR SEPPO NEUVONEN PEKKA NIEMELÄ ANITA C. RISCH JOUNI KILPELÄINEN MIZUE OHASHI MARTIN F. JURGENSEN 《Ecological Entomology》2009,34(3):369-377
Abstract 1. We monitored three different‐sized wood ant (Formica aquilonia Yarrow) mounds over a 3‐year period in Finnish boreal forests dominated by Norway spruce (Picea abies Karst.), to assess the seasonal temperature dependency of ant activity. Additionally, we also monitored Norway spruce trees around the mounds for descending honeydew foragers. 2. The amount of collected honeydew and prey and its composition, as well as the carbon (C), nitrogen (N), and phosphorus (P) in honeydew and invertebrate prey was also investigated. 3. The number of warm days (average temperature above 20 °C) and the amount of precipitation differed among the years. Ant activity at the mounds (but not on the trees) was highly correlated with air temperature throughout the ant‐active season (May–September), but ant activity in spring and autumn was lower than in summer at similar temperatures. During all 3 years, honeydew played a major role in wood ant nutrition (78–92% of dry mass). Invertebrate prey was mainly Diptera (on average 26.2%), Coleoptera (12.5%), Aphidina (9.3%), and Arachnoida (8.5%). 4. The total amounts of C, N, and P input brought into the ant mounds in the form of food (both honeydew and prey) on the stand level were 12.6–39.0, 1.6–4.6 and 0.1–0.4 kg ha?1 year?1, respectively, which is equivalent to 2–6%, 12–33% and 27–58% of the fluxes in annual needle litterfall in typical boreal Norway spruce forests. Thus, wood ants can play a significant role in short term and local N and P cycling of boreal forest ecosystems. 相似文献
976.
Takahiro Noda Nisha Sulari Kottearachchi Shogo Tsuda Motoyuki Mori Shigenobu Takigawa Chie Matsuura-Endo Sun-Ju Kim Naoto Hashimoto Hiroaki Yamauchi 《Carbohydrate polymers》2007,68(4):793-796
The research presented herein provides valuable data with respect to the phosphorus content of starches from many potato (Solanum tuberosum L.) cultivars using an energy-dispersive X-ray fluorescence technique. In all starches examined, the phosphorus content ranged from 308 to 1244 ppm. Furthermore, the estimation of the starch characteristics of representative samples differing manifestly in their phosphorus content indicated that enhancing the starch phosphate resulted in significant increases in the swelling power, peak viscosity, and breakdown and significant but small increases in the onset and peak temperatures of gelatinization. Other starch quality parameters, such as the amylose content, median granule size, and the gelatinization enthalpy, did not change significantly due to the degree of phosphate substitution of starch. 相似文献
977.
Legall H Stiel H Beck M Leupold D Gruszecki WI Lokstein H 《Journal of biochemical and biophysical methods》2007,70(3):369-376
Peridinin-chlorophyll a protein (PCP) is a unique water soluble antenna complex that employs the carotenoid peridinin as the main light-harvesting pigment. In the present study the near edge X-ray absorption fine structure (NEXAFS) spectrum of PCP was recorded at the carbon K-edge. Additionally, the NEXAFS spectra of the constituent pigments, chlorophyll a and peridinin, were measured. The energies of the lowest unoccupied molecular levels of these pigments appearing in the carbon NEXAFS spectrum were resolved. Individual contributions of the pigments and the protein to the measured NEXAFS spectrum of PCP were determined using a “building block” approach combining NEXAFS spectra of the pigments and the amino acids constituting the PCP apoprotein. The results suggest that absorption changes of the pigments in the carbon near K-edge region can be resolved following excitation using a suitable visible pump laser pulse. Consequently, it may be possible to study excitation energy transfer processes involving “optically dark” states of carotenoids in pigment-protein complexes by soft X-ray probe optical pump double resonance spectroscopy (XODR). 相似文献
978.
Rudenko NV Sinegina LL Arzhanov MA Ksenzenko VN Ivashina TV Morenkov OS Shaloiko LA Vinokurov LM 《Journal of biochemical and biophysical methods》2007,70(4):605-611
The effective new variant of "sandwich" bioluminescent enzyme immunoassay (BEIA) for the sensitive detection of glycoprotein B (gB) of pseudorabies virus (PrV) was presently developed. The high affinity interaction of barnase-barstar protein pair and photoprotein obelin as bioluminescent marker were for the first time successfully applied to BEIA development. Preliminary the two monoclonal antibodies, 11/5 and 34/2, were raised against gB for ELISA PrV detection. Presently we used the same immuno-"sandwich" principle for BEIA. To do this the two different bioconjugates were elaborated. Recombinant barnase was chemically conjugated with monoclonal anti-PrV's gB IgG, and also barstar was fused in frame to obelin. The characteristics of BEIA method have been compared to ELISA PrV detection. We have shown the proposed here gB-BEIA was 40-fold more sensitive as opposed to gB-ELISA test. The construction might have a broad promise in multiple potential immunological applications. 相似文献
979.
Lambrev PH Tsonev T Velikova V Georgieva K Lambreva MD Yordanov I Kovács L Garab G 《Photosynthesis research》2007,94(2-3):321-332
The kinetics of non-photochemical quenching (NPQ) of chlorophyll fluorescence was studied in pea leaves at different temperatures
between 5 and 25°C and during rapid jumps of the leaf temperature. At 5°C, NPQ relaxed very slowly in the dark and was sustained
for up to 30 min. This was independent of the temperature at which quenching was induced. Upon raising the temperature to
25°C, the quenched state relaxed within 1 min, characteristic for qE, the energy-dependent component of NPQ. Measurements
of the membrane permeability (ΔA515) in dark-adapted and preilluminated leaves and NPQ in the presence of dithiothreitol strongly suggest that the effect of
low temperature on NPQ was not because of limitation by the lumenal pH or the de-epoxidation state of the xanthophylls. These
data are consistent with the notion that the transition from the quenched to the unquenched state and vice versa involves
a structural reorganization in the photosynthetic apparatus. An eight-state reaction scheme for NPQ is proposed, extending
the model of Horton and co-workers (FEBS Lett 579:4201–4206, 2005), and a hypothesis is put forward concerning the nature of conformational changes associated with qE.
Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users. 相似文献
980.
Hunjoong Lee Theodore Diavatis Sanka Tennakoon Peilin Yu Xiaolian Gao 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》2007,1769(1):20-28
Solution structures of DNA/RNA hybrid duplexes, d(GCGCA*AA*ACGCG): r(cgcguuuugcg)d(C) (designated PP57), containing two C8-propynyl 2′-deoxyadenosines (A*) and unmodified hybrid (designated U4A4) are solved. The C8-propynyl groups on 2′-deoxyadenosine perturb the local structure of the hybrid duplex, but overall the structure is similar to that of canonical DNA/RNA hybrid duplex except that Hoogsteen hydrogen bondings between A* and U result in lower thermal stability. RNase H is known to cleave RNA only in DNA/RNA hybrid duplexes. Minor groove widths of hybrid duplexes, sugar puckerings of DNA are reported to be responsible for RNase H mediated cleavage, but structural requirements for RNase H mediated cleavage still remain elusive. Despite the presence of bulky propynyl groups of PP57 in the minor groove and greater flexibility, the PP57 is an RNase H substrate. To provide an insight on the interactions between RNase H and substrates we have modeled Bacillus halodurans RNase H-PP57 complex, our NMR structure and modeling study suggest that the residue Gly(15) and Asn(16) of the loop residues between first β sheet and second β sheet of RNase HI of Escherichia coli might participate in substrate binding. 相似文献