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1.
Lionfish (Pterois miles) were observed avoiding coral pinnacles inhabited by the moray eels Gymnothorax flavimarginatus and G. javanicus in the northern Red Sea, Egypt. Release of lionfish (Standard Length 93–104 mm) in such coral pinnacles in November 2016 resulted in almost immediate predation by large moray eels (Total Length > 1 m). Predation by moray eels may be the key control mechanism of population growth in the native biogeographical range of Pterois spp. and may indirectly explain the success of the invasive populations. This is the first video-documented record of moray eels feeding on the lionfish P. miles. 相似文献
2.
J. Rodríguez-Calcerrada J. A. Pardos L. Gil I. Aranda 《Trees - Structure and Function》2007,21(1):45-54
Photosynthetic acclimation of two co-occurring deciduous oaks (Quercus petraea and Quercus pyrenaica) to a natural light gradient was studied during one growing season. In the spring of 2003, 90 seedlings per species were
planted along a transect resulting from a dense Pinus sylvestris stand, an adjacent thinned area and a 10-m-wide firebreak (16.5–60.9% Global Site Factor (GSF)). In two dates of the following
summer, we measured leaf gas exchange, carboxylation efficiency (CE), chlorophyll and nitrogen content, light–response curves
of chlorophyll a fluorescence parameters, and leaf mass per area (LMA). Summer was mild, as evidenced by leaf predawn water potential (Ψpd), which reduced the interactive effect of water stress on the response of seedlings to light. Q. pyrenaica had higher LMA, CE, stomatal conductance (g
s max) and photosynthesis per unit area than Q. petraea at all growth irradiances. , LMA, g
s max and electron transport rate (ETR) all increased with light availability (GSF) in a similar fashion in both species. Light
had also a clear effect on the organization of Photosystem II (PS II), as deduced by chlorophyll a fluorescence curves. Chlorophyll concentration (Chlm) decreased with increasing light availability in Q. pyrenaica but it did not in Q. petraea. Seedlings of Q. petraea acclimated to higher irradiances showed a greater non-photochemical quenching (NPQ) than those of Q. pyrenaica. This suggests a higher susceptibility to high light in Q. petraea, which would be consistent with a better adaptation to shade, inferred from the lower LMA or the lower rate of photosynthesis. 相似文献
3.
Feeding ecology of the lionfish (Pterois volitans), an invasive species in the Western North Atlantic, was examined by collecting stomach content data from fishes taken throughout
the Bahamian archipelago. Three relative metrics of prey quantity, including percent number, percent frequency, and percent
volume, were used to compare three indices of dietary importance. Lionfish largely prey upon teleosts (78% volume) and crustaceans
(14% volume). Twenty-one families and 41 species of teleosts were represented in the diet of lionfish; the top 10 families
of dietary importance were Gobiidae, Labridae, Grammatidae, Apogonidae, Pomacentridae, Serranidae, Blenniidae, Atherinidae,
Mullidae, and Monacanthidae. The proportional importance of crustaceans in the diet was inversely related to size with the
largest lionfish preying almost exclusively on teleosts. Lionfish were found to be diurnal feeders with the highest predation
occurring in the morning (08:00–11:00). 相似文献
4.
Jonathan Peake Alex K. Bogdanoff Craig A. Layman Bernard Castillo Kynoch Reale-Munroe Jennifer Chapman Kristen Dahl William F. Patterson III Corey Eddy Robert D. Ellis Meaghan Faletti Nicholas Higgs Michelle A. Johnston Roldan C. Muñoz Vera Sandel Juan Carlos Villasenor-Derbez James A. MorrisJr. 《Biological invasions》2018,20(9):2567-2597
5.
White rot fungi are a promising option to treat recalcitrant organic molecules, such as lignin, polycyclic aromatic hydrocarbons,
and textile dyes, because of the lignin-modifying enzymes (LMEs) they secrete. Because knowledge of the kinetic parameters
is important to better design and operate bioreactors to cultivate these fungi for degradation and/or to produce LME(s), these
parameters were determined using Trametes versicolor ATCC 20869 (ATCC, American Type Culture Collection) in a magnetic stir bar reactor. A complete set of kinetic data has not
been previously published for this culture. Higher than previously reported growth rates with high laccase production of up
to 1,385 U l−1 occurred during growth without or glucose limitation. The maximum specific growth rate averaged 0.94 ± 0.23 day−1, whereas the maximum specific substrate consumption rates for glucose and ammonium were 3.37 ± 1.16 and 0.15 ± 0.04 day−1, respectively. The maximum specific oxygen consumption rate was 1.63 ± 0.36 day−1. 相似文献
6.
An S-adenosylmethionine synthetase gene (metK) from Streptomyces spectabilis was cloned into an expression plasmid under the control of an inducible T7 promoter and introduced into a strain of Escherichia coli (BAP1(pBP130/pBP144)) capable of producing the polyketide product 6-deoxyerythronolide B (6-dEB). The metK coexpression in BAP1(pBP130/pBP144) improved the specific production of 6-dEB from 10.86 to 20.08 mg l−1
. In an effort to probe the reason for this improvement, a series of gene deletion and expression experiments were conducted
based on a metK metabolic pathway that branches between propionyl-CoA (a 6-dEB precursor) and autoinducer compounds. The deletion and expression
studies suggested that the autoinducer pathway had a larger impact on improved 6-dEB biosynthesis. Supporting these results
were experiments demonstrating the positive effect conditioned media (the suspected location of the autoinducer compounds)
had on 6-dEB production. Taken together, the results of this study show an increase in heterologous 6-dEB production concomitant
with heterologous metK gene expression and suggest that the mechanism for this improvement is linked to native autoinducer compounds. 相似文献
7.
Hairy root cultures of Gentiana macrophylla were established by infecting the different explants four Agrobacterium rhizogenes strains namely A4GUS, R1000, LBA 9402 and ATCC11325, and hairy root lines were established with A. rhizogenes strain R1000 in 1/2 MS + B5 medium. Initially, 42 independent hairy root clones were maintained and seven clones belongs to different category were evaluated
for growth, morphology, integration and expression of Ri T-DNA genes, and alkaloid contents in dry root samples. On the basis
of total root elongation, lateral root density and biomass accumulation on solid media, hairy root clones were separated into
three categories. PCR and Southern hybridization analysis revealed both left and right T-DNA integration in the root clones
and RT-PCR analysis confirmed the expression of hairy root inducible gene. GUS assay was also performed to confirm the integration
of left T-DNA. The accumulation of considerable amounts of the root-specific secoiridoid glucosides gentiopicroside was observed
in GM1 ( and ) and the GM2 ( and DNA) type clones in considerably higher amount whether as two but callus-type clones (GM3) accumulated much less or only very negligible amounts of gentiopicroside. Out of four media composition
the 1/2 MS + B5 vitamin media was found most suitable. We found that initial establishment of root cultures largely depends on root:media ratio. Maximum growth rate was recorded in 1:50 root:media ratio. The maximum biomass in terms of fresh weight (33-fold) was achieved in 1/2 MS + B5 media composition after 35 days in comparison to sixfold increase in control. The biomass increase was most abundant maximum
from 15 to 30 days. Influence of A. rhizogenes strains and Ri plasmid of hairy root induction, the possible role of the TL-DNA and TR-DNA genes on growth pattern of hairy root, initial root inoculum:media ratio and effect of media composition is discussed. 相似文献
8.
Kun-dong Bai De-bao Liao De-bing Jiang Kun-fang Cao 《Trees - Structure and Function》2008,22(4):449-462
Photosynthetic induction times and photoinhibition in relation to simulated sunflecks (sudden increase of irradiance from
20 to 1,500 μmol m−2 s−1) were examined in leaves of co-occurring Fagus lucida (a deciduous tree) and Castanopsis lamontii (an evergreen tree) saplings grown either in a beech forest understory or in an adjacent open site during a late rainy season.
Two hypotheses were tested: (1) understory leaves would display faster photosynthetic induction times and greater photoinhibition
than open-grown leaves; and (2) evergreen species would have slower photosynthetic induction times and lighter photoinhibition
than deciduous species. Times to reach 90% of maximal CO2 assimilation rate (t
90%A
) and stomatal conductance
did not differ between species, but showed faster by 3–5 min in open-grown leaves than understory leaves due to higher initial
stomatal conductance (g
s
initial) and induction state 1 min into simulated sunflecks (IS1min) in the former. Our analysis across the published data on photosynthetic induction of 48 broad-leaved woody species again
revealed the negative correlations between t
90%A
and either g
s initial or IS1min, and the similarity of t
90%A
and between evergreen and deciduous species. Measurements of maximum PSII photochemical efficiency (F
v/F
m) indicated that photoinhibition occurred in saplings in any of the growth habitats during sunfleck-induced photosynthetic
induction. Despite no interspecific differences in the degree of photoinhibition, understory leaves of both species suffered
heavier photoinhibition than open-grown leaves, as indicated by a stronger decrease of F
v/F
m in the former. Dynamic changes in the quantum yields of PSII photochemistry and ΔpH- and xanthophyll-regulated thermal dissipation
and adjustments in the partitioning of electron flow between assimilative and non-assimilative processes were functional to
resist photoinhibition. However, such photoinhibition, together with stomatal and biochemical limitations, would decrease
carbon gain during simulated sunflecks, particularly in understory leaves. 相似文献
9.
Vallejo-Becerra V Vásquez-Bahena JM Santiago-Hernández JA Hidalgo-Lara ME 《Journal of industrial microbiology & biotechnology》2008,35(11):1289-1295
The recombinant invertase INVB (re-INVB) from Zymomonas mobilis was immobilized on microbeads of Nylon-6, by means of covalent bonding. The enzyme was strongly and successfully bound to
the support. The activity of the free and immobilized enzyme was determined, using 10% (w/v) sucrose, at a temperature ranging
between 15 and 60 °C and a pH ranging between 3.5 and 7. The optimal pH and temperature for the immobilized enzyme were 5.5
and 25 °C, respectively. Immobilization of re-INVB on Nylon-6 showed no significant change in the optimal pH, but a difference
in the optimal temperature was evident, as that for the free enzyme was shown to be 40 °C. The values for kinetic parameters
were determined as: 984 and 98 mM for of immobilized and free re-INVB, respectively. values for immobilized and free enzymes were 6.1 × 102 and 1.2 × 104 s−1, respectively, and immobilized re-INVB showed of 158.73 μmol h min−1 mg−1. Immobilization of re-INVB on Nylon-6 enhanced the thermostability of the enzyme by 50% at 30 °C and 70% at 40 °C, when compared
to the free enzyme. The immobilization system reported here may have future biotechnological applications, owing to the simplicity
of the immobilization technique, the strong binding of re-INVB to the support and the effective thermostability of the enzyme. 相似文献
10.
Alexis F. L. A. Powell William H. Busby Kelly Kindscher 《Journal of Insect Conservation》2007,11(3):299-308
The Regal Fritillary (Speyeria idalia), which once occupied prairies and meadows in North America from the upper Great Plains to the Atlantic coast, has disappeared
in recent decades from nearly the entirety of the eastern half of its range and has declined westward. In the Great Plains,
where the species is limited to native prairie remnants, several large populations are thought to exist, but patterns of occurrence
and abundance in the region have not been described in detail. We surveyed prairies within a three county area of northeastern
Kansas using distance-sampling along line transects and found Regal Fritillaries present at 70 of 87 sites. Population density
varied considerably among sites but was generally much higher at those that had not been burned in the past year. Despite
the loss of >99% of its original prairie landcover and the small sizes of remnants
we estimate that our study area supports a globally significant population of ∼12,000 adult individuals. Given the rapidity
of decline of Regal Fritillary populations elsewhere, this study establishes important population benchmarks and a practical
protocol for future monitoring efforts. 相似文献
11.
12.
Little information is known on what the magnitude of nitrogen (N) processed by ectomycorrhizal (ECM) fungal species in the
field. In a common garden experiment performed in a northern California oak woodland, we investigated transfer of nitrogen
applied as 15NH4 or 15NO3 from leaves to ectomycorrhizal roots of three oak species, Quercus agrifolia, Q. douglasii, and Q. garryana. Oak seedlings formed five common ectomycorrhizal morphotypes on root tips. Mycorrhizal tips were more enriched in 15N than fine roots. N transfer was greater to the less common morphotypes than to the more common types. 15N transfer from leaves to roots was greater when , not , was supplied. 15N transfer to roots was greater in seedlings of Q. agrifolia than in Q. douglasii and Q. garryana. Differential N transfer to ectomycorrhizal root tips suggests that ectomycorrhizal morphotypes can influence flows of N
from leaves to roots and that mycorrhizal diversity may influence the total N requirement of plants. 相似文献
13.
Effects of electron donors and acceptors on anaerobic reduction of azo dyes by <Emphasis Type="Italic">Shewanella decolorationis</Emphasis> S12 总被引:1,自引:0,他引:1
Shewanella decolorationis S12 was able to reduce various azo dyes in a defined medium with formate, lactate, and pyruvate or H2 as electron donors under anaerobic conditions. Purified membranous, periplasmic, and cytoplasmic fractions from strain S12
analyzed, respectively, only membranous fraction was capable of reducing azo dye in the presence of electron donor, indicating
that the enzyme system for anaerobic azoreduction was located on cellular membrane. Respiratory inhibitor Cu2+, dicumarol, stigmatellin, and metyrapone inhibited anaerobic azoreduction by purified membrane fraction, suggesting that
the bacterial anaerobic azoreduction by strain S12 was a biochemical process that oxidizes the electron donors and transfers
the electrons to the acceptors through a multicompound system related to electron transport chain. Dehydrogenases, cytochromes,
and menaquinones were essential electron transport components for the azoreduction. The electron transport process for azoreduction
was almost fully inhibited by O2, 6 mM of , and 0.9 mM of , but not by 10 mM of Fe3+. The inhibition may be a result from the competition for electrons from electron donors. These findings impact on the understanding
of the mechanism of bacterial anaerobic azoreduction and have implication for improving treatment methods of wastewater contaminated
by azo dyes. 相似文献
14.
The grass shrimp Palaemonetes pugio, a species common to Spartina alterniflora-dominated marshes, may be sensitive to the invasion of the common reed Phragmites australis in northeastern US salt marshes. We examined two questions: (1) Do grass shrimp have a preference for the native plant over the non-native plant? (2) Are grass shrimp more effective foragers on P. australis? We tested the first hypothesis by comparing the amount of time shrimp spend in physical contact with the plant types over a 1-h period. Shrimp were observed under different arrangements of vegetation to control for differences in conspicuous structural features. Additionally, the amount of time shrimp spent foraging on S. alterniflora and P. australis shoots was compared to determine if shrimp graze more often on S. alterniflora. Shrimp spent significantly more time in contact with S. alterniflora only when plant types were grouped at opposite ends of aquaria, but did not exhibit a foraging preference for this plant type. To address our second question, we investigated the effects of shrimp foraging on stem epifauna, an assemblage of semi-aquatic invertebrates associated with macrophyte shoots. Previous research showed that P. australis supports a lower density of stem-dwelling epifauna relative to S. alterniflora. We hypothesized that the primary grazer of this community, P. pugio, can forage on P. australis stems more effectively due to structural differences between the two plants, causing the lower abundance of epifauna through top-down effects. We exposed individual shoots inhabited by epifauna to shrimp and compared faunal densities on exposed shoots to densities on control shoots after 18 h. The reduction of epifauna by predation was proportional on the two plant types. Therefore, top-down effects can be ruled out as an explanation for the patchy distribution of epifauna observed in P. australis–S. alterniflora marshes. 相似文献
15.
Gorka Sancho Peter R. Kingsley-Smith James A. MorrisJr. C. Anna Toline Vanessa McDonough Sarah M. Doty 《Biological invasions》2018,20(9):2343-2361
Indo-Pacific Lionfish (Pterois volitans and P. miles) are venomous marine fishes in the family Scorpaenidae that invaded the Caribbean Sea, Gulf of Mexico, and western North Atlantic Ocean beginning in the mid-1980s. Lionfish are generalist, opportunistic predators that consume a variety of invertebrates and small reef fishes, such that the presence of Lionfish can significantly reduce reef fish abundance, diversity, and recruitment on invaded reefs. This study focused on the feeding ecology of Lionfish in Biscayne National Park (BNP), located in southeast Florida, USA. BNP consists of multiple marine habitats, including mangroves, seagrass beds, coral reefs, and limestone keys that support a diverse array of species resulting in multi-million dollar fishing and tourism industries. These habitats within BNP are at risk from the predatory impacts of invasive Lionfish. Through morphological prey identification of stomach contents, supplemented with DNA barcoding for identification of highly-digested prey items, Lionfish diet was analyzed and compared among fish sizes (immature, transitional and mature), BNP region (bay, shelf, and edge), and seasons (wet and dry). A total of 513 stomachs, containing more than 2600 prey items, were examined. We report that Lionfish in BNP fed predominantly on small reef fishes and small crustaceans, with a dietary shift from crustaceans to fishes occurring with increasing Lionfish size. Diets differed among BNP regions for medium-sized (100–179 mm) transitional Lionfish but not for large-sized (≥?180 mm) mature individuals. Furthermore, dietary differences between seasons were observed in mature Lionfish, but no seasonal differences were detected for smaller Lionfish (i.e., immature and transitional Lionfish). Based on the diet habits observed, Lionfish in BNP could have significant ecological and economic consequences for BNP and south Florida coastal habitats. 相似文献
16.
Raif Musa-Aziz Lihong Jiang Li-Ming Chen Kevin L. Behar Walter F. Boron 《The Journal of membrane biology》2009,228(1):15-31
Others have shown that exposing oocytes to high levels of (10–20 mM) causes a paradoxical fall in intracellular pH (pHi), whereas low levels (e.g., 0.5 mM) cause little pHi change. Here we monitored pHi and extracellular surface pH (pHS) while exposing oocytes to 5 or 0.5 mM NH3/NH4
+. We confirm that 5 mM causes a paradoxical pHi fall (−ΔpHi ≅ 0.2), but also observe an abrupt pHS fall (−ΔpHS ≅ 0.2)—indicative of NH3 influx—followed by a slow decay. Reducing [NH3/NH4
+] to 0.5 mM minimizes pHi changes but maintains pHS changes at a reduced magnitude. Expressing AmtB (bacterial Rh homologue) exaggerates −ΔpHS at both levels. During removal of 0.5 or 5 mM NH3/NH4
+, failure of pHS to markedly overshoot bulk extracellular pH implies little NH3 efflux and, thus, little free cytosolic NH3/NH4
+. A new analysis of the effects of NH3 vs. NH4
+ fluxes on pHS and pHi indicates that (a) NH3 rather than NH4
+ fluxes dominate pHi and pHS changes and (b) oocytes dispose of most incoming NH3. NMR studies of oocytes exposed to 15N-labeled show no significant formation of glutamine but substantial accumulation in what is likely an acid intracellular compartment. In conclusion, parallel measurements of pHi and pHS demonstrate that NH3 flows across the plasma membrane and provide new insights into how a protein molecule in the plasma membrane—AmtB—enhances
the flux of a gas across a biological membrane.
相似文献
Walter F. Boron (Corresponding author)Email: |
17.
Larval duration of the non-native Indo-Pacific lionfish was estimated from samples collected along the Bahamian Archipelago
using sagittal otoliths. Settlement marks, characterized by daily growth increments with reduced coloration, less definitive
margins, and a re-orientation of the growth axes and otolith shape, were determined for 28 individuals. Settlement age was
between 20 and 35 days with a mean of 26.2 days. Comparisons of settlement age to other littoral and reef fish species suggest
that lionfish settlement age is moderate to relatively low. Lionfish pelagic larval duration is apparently sufficient to allow
their rapid establishment and wide geographic range in the western Atlantic and Caribbean. 相似文献
18.
Fujiwara M Sumitani J Koga S Yoshioka I Kouzuma T Imamura S Kawaguchi T Arai M 《Applied microbiology and biotechnology》2007,74(4):813-819
Fructosyl-amino acid oxidase (FOD-F) from Fusarium oxysporum f. sp. raphani (NBRC 9972) is the enzyme catalyzing the oxidative deglycation of fructosyl-amino acids such as -fructosyl -benzyloxycarbonyl-lysine (FZK) and fructosyl valine (FV), which are model compounds of the glycated proteins in blood. Wild-type
FOD-F has high activities toward both substrates. We obtained a mutant FOD-F, which reacts with FZK but not with FV by random
mutagenesis. One amino-acid substitution (K373R) occurred in the mutant FOD-F. In addition to K373R, K373W, K373M, K373T,
and K373V, which were selected for optimization of the substitution at position K373, were purified and characterized. Kinetic
analysis showed that the catalytic turnover for FV greatly decreased, whereas that for FZK did not. In consequence, the specificities
toward FZK were increased in the mutant FOD-Fs. The relation between the substrate specificity of the mutant FOD-Fs and the
position of the carboxyl group of the substrates was demonstrated using a series of the substrates having the carboxyl group
at the different position. The mutant FOD-Fs are attractive candidates for developing an enzymatic measurement method for
glycated proteins such as glycated albumin in serum. This study will be helpful to establish an easier and rapid clinical
assay system of glycated albumin. 相似文献
19.
Nitrate and phosphate removal by<Emphasis Type="Italic"> Spirulina platensis</Emphasis> 总被引:5,自引:0,他引:5
Lodi A Binaghi L Solisio C Converti A Del Borghi M 《Journal of industrial microbiology & biotechnology》2003,30(11):656-660
The cyanobacterium Spirulina platensis was used to verify the possibility of employing microalgal biomass to reduce the contents of nitrate and phosphate in wastewaters. Batch tests were carried out in 0.5 dm3 Erlenmeyer flasks under conditions of light limitation (40 mol quanta m–2 s–1) at a starting biomass level of 0.50 g/dm3 and varying temperature in the range 23–40°C. In this way, the best temperature for the growth of this microalga (30°C) was determined and the related thermodynamic parameters were estimated. All removed nitrate was used for biomass growth (biotic removal), whereas phosphate appeared to be removed mainly by chemical precipitation (abiotic removal). The best results in terms of specific and volumetric growth rates ( =0.044 day–1, Q
x =33.2 mg dm–3 day–1) as well as volumetric rate and final yield of nitrogen removal (
=3.26 mg dm–3 day–1,
=0.739) were obtained at 30°C, whereas phosphorus was more effectively removed at a lower temperature. In order to simulate full-scale studies, batch tests of nitrate and phosphate removal were also performed in 5.0 dm3 vessels (mini-ponds) at the optimum temperature (30°C) but increasing the photon fluence rate to 80 mol quanta m–2 s–1 and varying the initial biomass concentration from 0.25 to 0.86 g/dm3. These additional tests demonstrated that an increase in the inoculum level up to 0.75 g/dm3 enhanced both NO3
– and PO4
3– removal, confirming a strict dependence of these processes on biomass activity. In addition, the larger surface area of the ponds and the higher light intensity improved removal yields and kinetics compared to the flasks, particularly concerning phosphorus removal ( =0.032–0.050 day–1, Q
x =34.7–42.4 mg dm–3 day–1,
=3.24–4.06 mg dm–3 day–1,
=0.750–0.879,
=0.312–0.623 mg dm–3 day–1, and
=0.224–0.440). 相似文献
20.
Calcification, a process common to numerous marine taxa, has traditionally been considered to be a significant source of CO2 in tropical waters only. A number of relatively recent studies, however, have shown that significant amounts of CO2 are also produced in temperate waters, although none of these studies was carried out on rocky shores, which are considered
to be very productive systems. We compared the CO2 fluxes due to respiration and calcification in two temperate species, the cirripedes Chthamalus montagui and Elminius modestus. The population dynamics of both species were estimated at two sites during a 1-year experimental period in order to establish
mean organic (ash-free dry weight) and CaCO3 (dry shell weight) production. Based on these parameters, we estimated the CO2 fluxes due to respiration and calcification. CaCO3 production was estimated to be 481.0 and
at each site, representing 3.4 and respectively, of released CO2. These fluxes represent each 47% of the CO2 released as a result of respiration and calcification. The production of CaCO3 at the high-density site was: (1) among the highest values obtained for temperate organisms, and (2) comparable to the estimated
CO2 fluxes for coral reefs. As calcifying organisms are well represented in temperate ecosystems in terms of both density and
biomass, our results provide clear evidence that calcification of temperate organisms should not be underestimated. Additional
studies on other rocky shore taxa are needed before the relative importance of calcification in rocky intertidal carbon budgets
can be generalized. 相似文献