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1.
Christophe Sandt Truis Smith-Palmer Jonathan Comeau David Pink 《Applied microbiology and biotechnology》2009,83(6):1171-1182
The Raman spectra, water content, and biomass density of wild-type (WT) Pseudomonas aeruginosa PAO1, small colony variant (SCV) PAO1, and Pseudoalteromonas sp. NCIMB 2021 biofilms were compared in order to determine their variation with strain and species. Living, fully submerged
biofilms were analyzed in situ by confocal Raman microspectroscopy for up to 2 weeks. Water to biomass ratios (W/BRs), which
are the ratios of the O–H stretching vibration of water at 3,450 cm−1 to the C–H stretching band characteristic of biomass at 2,950 cm−1, were used to estimate the biomass density and cell density by comparison with W/BRs of protein solutions and bacterial suspensions,
respectively, on calibration curves. The hydration within SCV biofilm colonies was extremely heterogeneous whereas W/BRs were
generally constant in young WT biofilm colonies. The mean biomass in biofilm colonies of WT or colony cores of SCV was typically
equivalent to 16% to 27% protein (w/v), but was 10% or less for NCIMB 2021. The corresponding cell densities were 7.5 to >10 × 1010 cfu mL−1 for SCV, while the maximum cell density for NCIMB biofilms was 2.8 × 1010 cfu mL−1. 相似文献
2.
João Costa e Silva Nuno M. G. Borralho José A. Araújo René E. Vaillancourt Brad M. Potts 《Tree Genetics & Genomes》2009,5(2):291-305
Genetic variation and co-variation among the key pulpwood selection traits for Eucalyptus globulus were estimated for a range of sites in Portugal, with the aim of improving genetic parameters used to predict breeding values
and correlated response to selection. The trials comprised clonally replicated full-sib families (eight trials) and unrelated
clones (17 trials), and exhibited varying levels of pedigree connectivity. The traits studied were stem diameter at breast
height, Pilodyn penetration (an indirect measure of wood basic density) and near infrared reflectance predicted pulp yield.
Univariate and multivariate linear mixed models were fitted within and across sites, and estimates of additive genetic, total
genetic, environmental and phenotypic variances and covariances were obtained. All traits studied exhibited significant levels
of additive genetic variation. The average estimated within-site narrow-sense heritability was 0.19 ± 0.03 for diameter and
0.29 ± 0.03 for Pilodyn penetration, and the pooled estimate for predicted pulp yield was 0.42 ± 0.14. When they could be
tested, dominance and epistatic effects were generally not statistically significant, although broad-sense heritability estimates
were slightly higher than narrow-sense heritability estimates. Averaged across trials, positive additive (0.64 ± 0.08), total
genetic (0.58 ± 0.04), environmental (0.38 ± 0.03) and phenotypic (0.43 ± 0.02) correlation estimates were consistently obtained
between diameter and Pilodyn penetration. This data argues for at least some form of pleiotropic relationship between these
two traits and that selection for fast growth will adversely affect wood density in this population. Estimates of the across-site
genetic correlations for diameter and Pilodyn penetration were high, indicating that the genotype by environment interaction
is low across the range of sites tested. This result supports the use of single aggregated selection criteria for growth and
wood density across planting environments in Portugal, as opposed to having to select for performance in different environments. 相似文献
3.
Impact of long-term nitrogen addition on carbon stocks in trees and soils in northern Europe 总被引:4,自引:2,他引:2
The aim of this study was to quantify the effects of fertiliser N on C stocks in trees (stems, stumps, branches, needles,
and coarse roots) and soils (organic layer +0–10 cm mineral soil) by analysing data from 15 long-term (14–30 years) experiments
in Picea abies and Pinus sylvestris stands in Sweden and Finland. Low application rates (30–50 kg N ha−1 year−1) were always more efficient per unit of N than high application rates (50–200 kg N ha−1 year−1). Addition of a cumulative amount of N of 600–1800 kg N ha−1 resulted in a mean increase in tree and soil C stock of 25 and 11 kg (C sequestered) kg−1 (N added) (“N-use efficiency”), respectively. The corresponding estimates for NPK addition were 38 and 11 kg (C) kg−1 (N). N-use efficiency for C sequestration in trees strongly depended on soil N status and increased from close to zero at
C/N 25 in the humus layer up to 40 kg (C) kg−1 (N) at C/N 35 and decreased again to about 20 kg (C) kg−1 (N) at C/N 50 when N only was added. In contrast, addition of NPK resulted in high (40–50 kg (C) kg−1 (N)) N-use efficiency also at N-rich (C/N 25) sites. The great difference in N-use efficiency between addition of NPK and
N at N-rich sites reflects a limitation of P and K for tree growth at these sites. N-use efficiency for soil organic carbon
(SOC) sequestration was, on average, 3–4 times lower than for tree C sequestration. However, SOC sequestration was about twice
as high at P. abies as at P. sylvestris sites and averaged 13 and 7 kg (C) kg−1 (N), respectively. The strong relation between N-use efficiency and humus C/N ratio was used to evaluate the impact of N
deposition on C sequestration. The data imply that the 10 kg N ha−1 year−1 higher deposition in southern Sweden than in northern Sweden for a whole century should have resulted in 2.0 ± 1.0 (95% confidence
interval) kg m−2 more tree C and 1.3 ± 0.5 kg m−2 more SOC at P. abies sites in the south than in the north for a 100-year period. These estimates are consistent with differences between south
and north in tree C and SOC found by other studies, and 70–80% of the difference in SOC can be explained by different N deposition. 相似文献
4.
Dave Parrott Anthony Prickett Stéphane Pietravalle Thomas R. Etherington Mark Fletcher 《European Journal of Wildlife Research》2012,58(1):23-33
Walked spotlight transect surveys with distance sampling were used to estimate regional population densities of badger (Meles meles), fox (Vulpes vulpes) and brown hare (Lepus europaeus) in south-west England (Cornwall, Devon, Gloucestershire, Herefordshire) and Wales (Pembrokeshire, Borders, North Wales).
All regions were surveyed during spring 2006 with English regions re-surveyed in autumn 2006. In each region, surveys were
conducted in a random sample of 19.6 km2 areas (mean areas per region: spring = 19, autumn = 25). Within each survey area, a semi-random transect was established
in each of a random sample of fields (open habitat almost exclusively pasture). Transects were subsequently walked at night
with spotlights (mean transects per survey area: spring = 21, autumn = 21). Each area was surveyed twice during a season.
Total transect length per region ranged from 137 to 193 km in spring and 230 to 250 km in autumn. The mean density of species
per region was: badger 1.5–4.8 km−2, fox 1.0–4.0 km−2, hare 0.4–4.6 km−2. The study has provided baseline estimates of regional densities against which any future equivalent surveys can be compared.
It has also illustrated the practical application of large-scale walked distance sampling to surveys of British mammals. 相似文献
5.
Desmond J. Stackpole René E. Vaillancourt Marcelo de Aguigar Brad M. Potts 《Tree Genetics & Genomes》2010,6(2):179-193
Genetic parameters for stem diameter and wood density were compared at selection (4–5 years) and harvest (16–17 years) age
in an open-pollinated progeny trial of Eucalyptus globulus in Tasmania (Australia). The study examined 514 families collected from 17 subraces of E. globulus. Wood density was assessed on a subsample of trees indirectly using pilodyn penetration at both ages and directly by core
basic density at harvest age. Significant additive genetic variance and narrow-sense heritabilities (
h\textop2 h_{\text{op}}^2 ) were detected for all traits. Univariate and multivariate estimates of heritabilities were similar for each trait except
harvest-age diameter. Comparable univariate estimates of selection- and harvest-age heritabilities for diameter masked changes
in genetic architecture that occurred with stand development, whereby the loss of additive genetic variance through size-dependent
mortality was countered by the accentuation of additive genetic differences among survivors with age. Regardless, the additive
genetic (r
a) and subrace (r
s) correlations across ages were generally high for diameter (0.95 and 0.61, respectively) and pilodyn penetration (0.77 and
0.96), as were the correlations of harvest-age core basic density with selection- and harvest-age pilodyn (r
a −0.83, −0.88; r
s −0.96, −0.83). While r
s between diameter and pilodyn were close to zero at both ages, there was a significant change in r
a from adverse at selection age (0.25) to close to zero (−0.07) at harvest age. We argue that this change in the genetic correlation
reflects a decoupling of the genetic association of growth and wood density with age. This result highlights the need to validate
the use of selection-age genetic parameters for predicting harvest-age breeding values. 相似文献
6.
Soil Inorganic N Leaching in Edges of Different Forest Types Subject to High N Deposition Loads 总被引:2,自引:0,他引:2
Karen Wuyts An De Schrijver Jeroen Staelens Lotte Van Nevel Sandy Adriaenssens Kris Verheyen 《Ecosystems》2011,14(5):818-834
We report on soil leaching of dissolved inorganic nitrogen (DIN) along transects across exposed edges of four coniferous and
four deciduous forest stands. In a 64-m edge zone, DIN leaching below the main rooting zone was enhanced relative to the interior
(at 128 m from the edge) by 21 and 14 kg N ha−1 y−1 in the coniferous and deciduous forest stands, respectively. However, the patterns of DIN leaching did not univocally reflect
those of DIN throughfall deposition. DIN leaching in the first 20 m of the edges was lower than at 32–64 m from the edge (17
vs. 36 kg N ha−1 y−1 and 15 vs. 24 kg N ha−1 y−1 in the coniferous and deciduous forests, respectively). Nitrogen stocks in the mineral topsoil (0–30 cm) were, on average,
943 kg N ha−1 higher at the outer edges than in the interior, indicating that N retention in the soil is probably one of the processes
involved in the relatively low DIN leaching in the outer edges. We suggest that a complex of edge effects on biogeochemical
processes occurs at the forest edges as a result of the interaction between microclimate, tree dynamics (growth and litterfall),
and atmospheric deposition of N and base cations. 相似文献
7.
Specific growth rates of heterotrophic bacterioplankton have been frequently estimated from in situ bacterial production (BP)
to biomass (BB) ratios, using a series of assumptions that may result in serious discrepancies with values obtained from predator-free
cultures. Here, we used both types of approaches together with a comprehensive assessment of single-cell physiological characteristics
(membrane integrity, nucleic acid content, and active respiration) of coastal bacterioplankton during a complete annual cycle
(February 2007–January 2008) in the southern Bay of Biscay off Xixón, Spain. Both leucine and thymidine incorporation rates
were used in conjunction with empirical tracer to carbon or cells conversion factors (eCFs) to accurately derive BP. Leu and
TdR incorporation rates covaried year-round, as did the corresponding eCFs at 0 and 50 m depth. eCFs peaked in autumn, with
mean annual values close to the theoretical ones (3.4 kg C mol Leu−1 and 2.0 × 1018 cells mol TdR−1). Bacterial abundance (0.2–1.5 × 106 cells L−1) showed a bimodal distribution with maxima in May and October and minima in March. Live (membrane-intact) cells dominated
year-round (79–97%), with high nucleic acid cells (42–88%) and actively respiring bacteria (CTC+, 1–16%) showing distinct
surface maxima in April and July, respectively. BB (557–1,558 mg C m−2) and BP (7–139 mg C m−2 day−1) presented two distinct peaks in spring and autumn, both of similar size due to a strong upwelling event observed in September.
Specific growth rates (0.35–3.8 day−1) were one order of magnitude higher in predator-free incubations than bacterial turnover rates derived from integrated BP:BB
ratios (0.01–0.16 and 0.01–0.09 day−1, for Leu and TdR, respectively) and were not correlated, probably due to a significant contribution of low activity cells
to total standing stocks. The Leu:TdR molar ratio averaged for the water column (6.6–25.5) decreased significantly with higher
integrated BB, indicating that low standing stocks tend to present unbalanced growth. Discrepancies about the true magnitude
of specific growth rates must be solved before fully appreciating the role of bacteria in the ocean carbon cycle. 相似文献
8.
Carolyn A. Raymond 《Tree Genetics & Genomes》2011,7(4):819-833
Historical data from 26 progeny trials in the NSW breeding program was analyzed to determine the extent and practical importance
of genotype by environment (G×E) interactions for a range of traits. Significant G×E interaction was present for diameter
(DBH) with 75% of the 35 estimated between-site genetic correlations falling below the threshold value of 0.6 where regionalization
should be considered. Estimated genetic correlations for stem straightness, branch quality, and outerwood density were much
higher, indicating these traits are not as affected by G×E. Levels of G×E for DBH are sufficient to have serious impacts on
the expression of genetic gain in deployed material. For DBH, altitude differences between sites appear to be the key factor
driving the G×E with a difference of greater than 280 m in altitude leading to a breakdown in correlations. Two groups of
sites were identified as having limited G×E within each group: one for sites above 900 m elevation plus a lower-altitude group.
Sites included in the higher-altitude group were located across the entire north–south geographic range of NSW. Equations
for prediction of site mean DBH indicate that altitude, prior land use, and underlying geology are key driving variables.
A more complex model was developed for predicting the between-site genetic correlations for DBH with the model accounting
for approximately 50% of the observed variation. 相似文献
9.
Ecosystem restoration by rewetting of degraded fens led to the new formation of large-scale shallow lakes in the catchment
of the River Peene in NE Germany. We analyzed the biomass and the nutrient stock of the submersed (Ceratophyllum demersum) and the floating macrophytes (Lemna minor and Spirodela polyrhiza) in order to assess their influence on temporal nutrient storage in water bodies compared to other freshwater systems. Ceratophyllum demersum displayed a significantly higher biomass production (0.86–1.19 t DM = dry matter ha−1) than the Lemnaceae (0.64–0.71 t DM ha−1). The nutrient stock of submersed macrophytes ranged between 28–44 kg N ha−1 and 8–12 kg P ha−1 and that of floating macrophytes between 14–19 kg N ha−1 and 4–5 kg P ha−1 which is in the range of waste water treatment plants. We found the N and P stock in the biomass of aquatic macrophytes being
20–900 times and up to eight times higher compared to the nutrient amount of the open water body in the shallow lakes of rewetted
fens (average depth: 0.5 m). Thereafter, submersed and floating macrophytes accumulate substantial amounts of dissolved nutrients
released from highly decomposed surface peat layers, moderating the nutrient load of the shallow lakes during the growing
season from April to October. In addition, the risk of nutrient loss to adjacent surface waters becomes reduced during this
period. The removal of submersed macrophytes in rewetted fens to accelerate the restoration of the low nutrient status is
discussed. 相似文献
10.
Microclimatic parameters influencing nitrogen fixation in the phyllosphere in a Costa Rican premontane rain forest 总被引:1,自引:0,他引:1
Elke Freiberg 《Oecologia》1998,117(1-2):9-18
The acetylene reduction method was used to measure nitrogen fixation in the phyllosphere of attached leaves of different
phorophytes under natural conditions in a premontane rain forest in Costa Rica. Maximum rates of nitrogen fixation (26 ng N · cm−2 leaf area · h−1) – mainly due to the activity of two species of Scytonema (Cyanobacteria) – were measured in the rainy season in bright sunlight. Rates of nitrogen fixation were correlated with the
leaf area covered by Scytonema. In periods without precipitation the fixation activity decreased to zero within 2–3 days. As long as the epiphylls were sufficiently
supplied with water, other microclimatic factors like temperature and light intensity also influenced nitrogen fixation rates,
but to a lesser extent. Relative humidity and species of phorophyte showed no direct influence. It was concluded that the
most important factor for nitrogen fixation in the phyllosphere was the availability of liquid water. Linking these results
to meteorological data, the input of nitrogen by biological nitrogen fixation in the phyllosphere in the investigation area
was estimated to be as much as 1.6 ± 0.8 kg N · ha−1 · year−1 per unit of leaf area index (LAI). For an LAI of 2 for the understory the nitrogen input would vary between 2 and 5 kg N ·
ha−1 · year−1. This work also demonstrates the importance of detailed knowledge of variation in microclimate throughout the year as a basis
for extrapolation of the annual nitrogen input.
Received: 21 December 1997 / Accepted: 14 June 1998 相似文献
11.
Washington J. Gapare Milo? Ivkovi? Gregory W. Dutkowski David J. Spencer Peter Buxton Harry X. Wu 《Tree Genetics & Genomes》2012,8(2):391-407
Growth and form traits data were obtained from eight provenance trials of radiata pine (Pinus radiata D. Don) planted across the radiata pine plantation estate in southeast Australia. The genetic pool included 466 open-pollinated
families collected from A?o Nuevo, Monterey and Cambria provenances on the Californian mainland coast in the USA and from
Guadalupe and Cedros islands off the coast of Baja California in Mexico. Early survival of all provenances was around 90%,
except for Cedros (<60%). Monterey and A?o Nuevo were the best performers at almost all sites. However, good growth performance
of Cambria and good stem straightness of Guadalupe on some sites are important results, because the genetic base of the present
Australian plantations evidently originated from only Monterey and A?o Nuevo. The average estimated single-site heritability
for diameter at breast height was 0.22 and 0.32 at juvenile and mature ages, respectively. Heritability estimates for stem
straightness and branching ranged from 0.23 to 0.55. Genetic correlation estimates between diameter at breast height (DBH)
at juvenile and rotation ages were all >0.80. Estimates of between-site genetic and provenance correlations for DBH were often
low, indicating high genotype by environment interaction across trials, consistent with previous Australian studies. However,
there was minimal G × E among trials on high-altitude high-rainfall sites and among trials on low-altitude, low-rainfall sites. 相似文献
12.
This study evaluated the sources, sinks, and factors controlling net export of nitrogen (N) from watersheds on the west coast
of the US. We calculated input of new N to 22 watersheds for 1992 and 2002. 1992 inputs ranged from 541 to 11,644 kg N km−2 year−1, with an overall area-weighted average of 1,870 kg N km−2 year−1. In 2002, the range of inputs was 490–10,875 kg N km−2 year−1, averaging 2,158 kg N km−2 year−1. Fertilizer was the most important source of new N, averaging 956 (1992) and 1,073 kg N km−2 year−1 (2002). Atmospheric deposition was the next most important input, averaging 833 (1992) and 717 kg N km−2 year−1 (2002), followed by biological N fixation in agricultural lands. Riverine N export, calculated based on measurements taken
at the furthest downstream USGS water quality monitoring station, averaged 165 (1992) and 196 kg N km−2 year−1 (2002), although data were available for only 7 watersheds at the latter time point. Downstream riverine N export was correlated
with variations in streamflow (export = 0.94 × streamflow − 5.65, R
2 = 0.66), with N inputs explaining an additional 16% of the variance (export = 1.06 × streamflow + 0.06 × input − 227.78,
R
2 = 0.82). The percentage of N input that is exported averaged 12%. Percent export was also related to streamflow (%export = 0.05 × streamflow − 2.61,
R
2 = 0.60). The correlations with streamflow are likely a result of its large dynamic range in these systems. However, the processes
that control watershed N export are not yet completely understood. 相似文献
13.
Reina RD Cooper PD 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2000,170(1):27-35
We studied the control of salt gland secretion in hatchling Chelonia mydas. The threshold salt load to activate salt secretion was between 400 μmol NaCl 100 g bodymass (BM)−1 and 600 μmol NaCl 100 g BM−1, which caused an increase in plasma sodium concentration of 13% to 19%. Following a salt load of 2700 μmol NaCl 100 g BM−1, salt gland secretion commenced in 12 ± 1.3 min and reached maximal secretory concentration within 2–7 min. Maximal secretory
rate of a single gland averaged 415 μmol Na 100 g BM−1 h−1. Plasma sodium concentration and total osmotic concentration after salt loading were significantly higher than pretreatment
values within 2 min. Adrenalin (25 μg kg BM−1) and the cholinergic agonist methacholine (1 mg kg BM−1) inhibited salt gland activity. Atropine (10 mg kg BM−1) reversed methacholine inhibition and stimulated salt gland secretion when administered with a subthreshold salt load. Arginine
vasotocin produced a transient reduction in sodium secretion by the active gland, while atrial natriuretic factor, vasoactive
intestinal peptide and neuropeptide Y had no measurable effect on any aspect of salt gland secretion. Our results demonstrated
that secretion of the salt gland in C. mydas can be modified by neural and hormonal chemicals in vivo and that the cholinergic and adrenergic stimulation of an exocrine
gland do not appear to have the typical, antagonist actions on the chelonian salt gland.
Accepted: 28 September 1999 相似文献
14.
Use of Acadian marine plant extract powder from Ascophyllum nodosum in tissue culture of Kappaphycus varieties 总被引:1,自引:0,他引:1
Anicia Q. Hurtado Dianne Aster Yunque Keneth Tibubos Alan T. Critchley 《Journal of applied phycology》2009,21(6):633-639
Three varieties of Kappaphycus alvarezii (Kapilaran, KAP), Tambalang purple (PUR), Adik-adik (AA), and one variety of Kappaphycus striatum var. sacol (green sacol (GS) were used to determine the efficiency of Acadian marine plant extract powder (AMPEP) as a culture medium
at different concentrations, for the regeneration of young plants of Kappaphycus varieties, using tissue culture techniques for the production of seed stock for nursery and outplanting purposes for the
commercial cultivation of carrageenophytes. A shorter duration for shoot formation was observed when the explant was treated
with AMPEP + Plant Growth Regulator (PGR = PAA + zeatin at 1 mg L−1) compared to AMPEP when used singly. However, four explants responded differently to the number of days required for shoot
formation. The KAP variety took 46 days to form shoots at 3–4 mg L−1 AMPEP + PGR; while PUR required 21 days at 3–5 mg L−1 AMPEP and 3–4 mg L−1 AMPEP + PGR. AA required 17 days at 3–5 mg L−1 AMPEP and AMPEP + PGR; and GS 25 days at 1 mg L−1 AMPEP + PGR. It was observed that among the four explants used, PUR and AA initiated shoot formation with the use of AMPEP
only at higher concentrations (3–5 mg L−1) after a shorter period. Only PUR responded positively to ESS/2 for shoot initiation. The use of AMPEP alone and/or in combination
with PGR as a culture medium in the propagation of microplantlets using tissue culture technique is highly encouraging. 相似文献
15.
Nitrite accumulates during biological denitrification processes when carbon sources are insufficient. Acetate, methanol, and
ethanol were investigated as supplementary carbon sources in the nitrite denitrification process using biogranules. Without
supplementary external electron donors (control), the biogranules degraded 200 mg l−1 nitrite at a rate of 0.27 mg NO2–N g−1 VSS h−1. Notably, 1,500 mg l−1 acetate and 700 mg l−1 methanol or ethanol enhanced denitrification rates for 200 mg l−1 nitrite at 2.07, 1.20, and 1.60 mg NO2–N g−1 VSS h−1, respectively; these rates were significantly higher than that of the control. The sodium dodecyl sulfate polyacrylamide
gel electrophoresis of the nitrite reductase (NiR) enzyme identified three prominent bands with molecular weights of 37–41 kDa.
A linear correlation existed between incremental denitrification rates and incremental activity of the NiR enzyme. The NiR
enzyme activity was enhanced by the supplementary carbon sources, thereby increasing the nitrite denitrification rate. The
capacity of supplementary carbon source on enhancing NiR enzyme activity follows: methanol > acetate > ethanol on molar basis
or acetate > ethanol > methanol on an added weight basis. 相似文献
16.
In a declining sugar maple (SM) stand, we tested the hypothesis that an increasing relative abundance of American beech (AB)
and yellow birch (YB) would improve litter quality by providing a higher proportion of litterfall richer in base cations and
lower in acidity. From 1989 to 2006, SM leaf fall diminished from 59% (1,718 kg ha−1 year−1) to 36% (915 kg ha−1 year−1) of the total leaf fall biomass. Overall, the increase in AB and YB litterfall compensated for the SM decrease, resulting
in constant annual leaf litterfall fluxes (2,803 kg ha−1 year−1) over the period studied. However, because the leaf litter for AB and YB had Ca and Mg concentrations 2–3 times higher than
did SM, Ca and Mg concentrations and fluxes in leaf litterfall significantly increased between 1989 and 2006. Leaf litterfall
of AB and YB also has a higher base/acid ratio than SM. Consequently, changes in forest composition following SM decline led
to a clear improvement in litterfall quality in terms of base cations content and fluxes and acid–base properties. 相似文献
17.
The zooxanthellate octocoral Sinularia flexibilis is a producer of potential pharmaceutically important metabolites such as antimicrobial and cytotoxic substances. Controlled
rearing of the coral, as an alternative for commercial exploitation of these compounds, requires the study of species-specific
growth requirements. In this study, phototrophic vs. heterotrophic daily energy demands of S. flexibilis was investigated through light and Artemia feeding trials in the laboratory. Rate of photosynthetic oxygen by zooxanthellae in light (≈200 μmol quanta m−2 s−1) was measured for the coral colonies with and without feeding on Artemia nauplii. Respiratory oxygen was measured in the dark, again with and without Artemia nauplii. Photosynthesis–irradiance curve at light intensities of 0, 50, 100, 200, and 400 μmol quanta m−2 s−1 showed an increase in photosynthetic oxygen production up to a light intensity between 100 and 200 μmol quanta m−2 s−1. The photosynthesis to respiration ratio (P/R > 1) confirmed phototrophy of S. flexibilis. Both fed and non-fed colonies in the light showed high carbon contribution by zooxanthellae to animal (host) respiration
values of 111–127%. Carbon energy equivalents allocated to the coral growth averaged 6–12% of total photosynthesis energy
(mg C g
−
1 buoyant weight day
−
1) and about 0.02% of the total daily radiant energy. “Light utilization efficiency (ε)” estimated an average ε value of 75%
12 h
−
1 for coral practical energetics. This study shows that besides a fundamental role of phototrophy vs. heterotrophy in daily
energy budget of S. flexibilis, an efficient fraction of irradiance is converted to useable energy. 相似文献
18.
A. Q. Hurtado A. T. Critchley A. Trespoey G. Bleicher-Lhonneur 《Journal of applied phycology》2008,20(5):551-555
Kappaphycus striatum var. sacol was grown in two separate studies: (1) at two stocking densities, and (2) at four different depths, each for three different
durations of culture (30, 45 and 60 days) in order to determine the growth rate of the seaweed and evaluate the carrageenan
content and its molecular weight. The results demonstrated that stocking density, duration of culture and depth significantly
(P < 0.01) affected the growth rate, carrageenan content and molecular weight of K. striatum var. sacol. Decreasing growth rate was observed at both stocking densities and at four depths as duration of culture increased. A lower
stocking density (500 g m−1line−1) showed a higher growth rate for the shortest durations, i.e. 30 days, as compared to those grown at a higher density. Likewise,
decreasing growth rate was observed as depth increased, except at 50 cm after 60 days of culture. A 45-day culture period
produced the highest molecular weight at both stocking densities (500 g m−1line−1 = 1,079.5 ± 31.8 kDa, 1,000 g m−1line−1 = 1,167 ± 270.6 kDa). ‘Sacol’ grown for 30 days at 50 cm (1,178 kDa) to 100 cm (1,200 kDa) depth showed the highest values
of molecular weight of carrageenan extracted. The results suggested that K. striatum var. sacol is best grown at a stocking density of 500 g m−1line−1, at a depth of 50–100 cm, and for a duration of 30 days in order to provide the highest growth rate, carrageenan content
and molecular weight. 相似文献
19.
Washington J. Gapare Miloš Ivković Brian S. Baltunis Colin A. Matheson Harry X. Wu 《Tree Genetics & Genomes》2010,6(1):113-125
Genetic variation for wood quality traits and diameter growth for radiata pine (Pinus radiata D. Don) at age 20/21 years was estimated from eight trials in Australia. The traits studied were wood density, acoustic time-of-flight
(an indirect measure of stiffness) and diameter at breast height (DBH). Wood density and DBH exhibited significant additive
genetic variation whereas non-additive effects were not significantly different from zero. Time of flight was also not significantly
different from zero for both additive and non-additive effects, respectively. Average single-site heritability estimates (±SE)
for wood density and DBH were 0.38 ± 0.10 and 0.16 ± 0.08, respectively. Pooled-site heritability estimates for wood density
and DBH were 0.38 ± 0.10 and 0.08 ± 0.10, respectively. For density, there was little evidence of genotype-by-environment
interaction (GEI) across the eight trials at the additive level (type B additive genetic correlation; r
BADD = 0.73 ± 0.08) and type B genetic correlation for full-sib families (r
BFS = 0.64 ± 0.08). In contrast, the type B additive genetic correlation for DBH was lower, (r
BADD = 0.51 ± 0.14), suggesting evidence of GEI. However, type B genetic correlation for full-sib families was moderate (0.63 ± 0.11)
for DBH, suggesting that there may be some stable full-sib families. On the basis of the results of this study, GEI should
be considered in order to optimise deployment of improved germplasm in Australia. 相似文献
20.
In this study, alteration in morphology of submergedly cultured Antrodia camphorata ATCC 200183 including arthroconidia, mycelia, external and internal structures of pellets was investigated. Two optimization
models namely response surface methodology (RSM) and artificial neural network (ANN) were built to optimize the inoculum size
and medium components for intracellular triterpenoid production from A. camphorata. Root mean squares error, R
2, and standard error of prediction given by ANN model were 0.31%, 0.99%, and 0.63%, respectively, while RSM model gave 1.02%,
0.98%, and 2.08%, which indicated that fitness and prediction accuracy of ANN model was higher when compared to RSM model.
Furthermore, using genetic algorithm (GA), the input space of ANN model was optimized, and maximum triterpenoid production
of 62.84 mg l−1 was obtained at the GA-optimized concentrations of arthroconidia (1.78 × 105 ml−1) and medium components (glucose, 25.25 g l−1; peptone, 4.48 g l−1; and soybean flour, 2.74 g l−1). The triterpenoid production experimentally obtained using the ANN–GA designed medium was 64.79 ± 2.32 mg l−1 which was in agreement with the predicted value. The same optimization process may be used to optimize many environmental
and genetic factors such as temperature and agitation that can also affect the triterpenoid production from A. camphorata and to improve the production of bioactive metabolites from potent medicinal fungi by changing the fermentation parameters. 相似文献