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281.
Ninety-one lakes distributed along the Tatra Mountains (most of lakes > 1 ha and 65% of lakes > 0.01 ha) were sampled and analysed for ionic and nutrient composition in September 2004 (15 years after reduction in acid deposition). Eighty-one lakes were in alpine zone and ten lakes in Norway spruce forest. The results were compared to similar lake surveys from 1994 (the beginning of water recovery from acidification) and 1984 (maximum acidification). Atmospheric deposition of SO 4 2? and inorganic N decreased 57% and 35%, respectively, in this region from the late 1980s to 2000. Lake water concentrations of SO 4 2? and NO 3 ? have decreased both by ~50% on average (to 23 and 19 μmol L?1, respectively, in 2004) since 1984. While the decrease in SO 4 2? concentrations was stable throughout 1984–2004, most of the NO 3 ? decrease occurred from 1994 to 2004. The declines in SO 4 2? and NO 3 ? concentrations depended on catchment coverage with vegetation, being most rapid for SO 4 2? in forest lakes and for NO 3 ? in rocky lakes. Concentrations of the sum of base cations (dominated by Ca2+) significantly decreased between 1984 and 2004, with the highest change in rocky lakes. Most of this decline occurred between 1994 and 2004. Acid neutralising capacity (ANC) did not change in the 1984–1994 period, but increased on average by 29 μmol L?1 between 1994 and 2004, with the highest change in rocky lakes. Over the last decade, the proportion of lakes with ANC > 150 μmol L?1 increased from 15% to 21% and that of ANC < 20 μmol L?1 decreased from 37% to 20%. The highest decline in H+ and Al concentrations occurred in the most acid lakes. On a regional basis, no significant change was observed for total phosphorus, total organic nitrogen, and dissolved organic carbon (DOC) in the 1994–2004 period. However, these parameters increased in forest lakes, which exhibited an increasing trend in DOC concentrations, inversely related (P < 0.001) to their decreasing ionic strength (30% on average in 1994–2004). 相似文献
282.
Laura Bedin Denardi Jéssica Tairine Keller Vanessa Oliveira Débora Alves Nunes Mario Janio Morais Santurio Sydney Hartz Alves 《Mycopathologia》2017,182(9-10):819-828
In this study, we evaluated the in vitro activity of echinocandins, azoles, and amphotericin B alone and in combination against echinocandin/azole-sensitive and echinocandin/azole-resistant Candida glabrata isolates. Susceptibility tests were performed using the broth microdilution method in accordance with the Clinical and Laboratory Standards Institute document M27-A3. The checkerboard method was used to evaluate the fractional inhibitory concentration index of the interactions. Cross-resistance was observed among echinocandins; 15% of the isolates resistant to caspofungin were also resistant to anidulafungin and micafungin. Synergistic activity was observed in 70% of resistant C. glabrata when anidulafungin was combined with voriconazole or posaconazole. Higher (85%) synergism was found in the combination of caspofungin and voriconazole. The combinations of caspofungin with fluconazole, posaconazole and amphotericin B, micafungin with fluconazole, posaconazole and voriconazole, and anidulafungin with amphotericin B showed indifferent activities for the majority of the isolates. Anidulafungin combined with fluconazole showed the same percentage of synergism and indifference (45%). Antagonism was detected in 50% of isolates when micafungin was combined with amphotericin B. Combinations of echinocandins and antifungal azoles have great potential for in vivo assays which are required to evaluate the efficacy of these combinations against multidrug-resistant C. glabrata strains. 相似文献
283.
A β-glucosidase effectively releasing diosgenin from spirostanosides of Dioscorea zingiberensis C. H. Wright (DZW), named AfG, was purified from a strain of Aspergillus fumigates. The molecular weight of AfG was 113 kDa. Analysis of protein fragments by ESI-Q-TOF indicated that AfG was a β-glucosidase.
The circular dichroism spectrum suggested that the main secondary structure of AfG in Milli-Q water was α-helixes. Atomic
force microscopy revealed that it was a globular protein. AfG maintained high activity from pH 3.6 to 5.0 and from 50 to 90°C.
With the strong heat stability, AfG retained 55% of its original activity at 65°C for 120 h. AfG utilized muti-3-O-glycosides
of various steroidal saponins from DZW as substrate, such as trillin, diosgenin diglucoside, dioscin, deltonin and gracillin,
to yield diosgenin, suggesting the possibility of producing diosgenin from total saponins of DZW using a single enzyme. 相似文献
284.
Xiaolian Gu Ping Zhuang Feng Zhao Xiaotao Shi Xiaorong Huang Guangpeng Feng Tao Zhang Jianyi Liu Longzhen Zhang Boyd Kynard 《Environmental Biology of Fishes》2017,100(1):27-33
Experiments were conducted in artificial stream tanks with juvenile Chinese sturgeon, Acipenser sinensis, captured in the Yangtze Estuary to test two null hypotheses (1) juveniles have no preference for white or black substrates, and (2) white or black substrate color has no effect on juvenile feeding efficiency on the barcheek goby,Rhinogobius giurinus, a dark-colored prey of wild juveniles. Juveniles strongly preferred white substrate. However, in feeding tests, feeding efficiency by juveniles was similar on white or black substrates. Thus, substrate color had no effect on feeding efficiency. Results suggest the innate preference for white substrate is not a visual adaptation for capturing prey on a contrasting background, but is an adaptation predisposing juveniles to seek light-colored sandy substrate where forage abundance is greatest. 相似文献
285.
Jesús Díez 《Biological invasions》2005,7(1):3-15
In the last two centuries, several species of Australian eucalypts (e.g. Eucalyptus camaldulensis and E.␣globulus) were introduced into the Iberian Peninsula for the production of paper pulp. The effects of the introduction of exotic root-symbitotic
fungi together with the eucalypts have received little attention. During the past years, we have investigated the biology
of ectomycorrhizal fungi in eucalypt plantations in the Iberian Peninsula. In the plantations studied, we found fruit bodies
of several Australian ectomycorrhizal fungi and identified their ectomycorrhizas with DNA molecular markers. The most frequent
species were Hydnangium carneum, Hymenogaster albus, Hysterangium inflatum, Labyrinthomyces donkii, Laccaria fraterna, Pisolithus albus, P. microcarpus, Rhulandiella berolinensis, Setchelliogaster rheophyllus, and Tricholoma eucalypticum. These fungi were likely brought from Australia together with the eucalypts, and they seem to have facilitated the establishment
of eucalypt plantations and their naturalization. The dispersion of Australian fungal propagules may be facilitating the spread
of eucalypts along watercourses in semiarid regions increasing the water lost. Because ectomycorrhizal fungi are obligate
symbionts, their capacity to persist after eradication of eucalypt stands, and/or to extend beyond forest plantations, would
rely on the possibility to find compatible native host trees, and to outcompete the native ectomycorrhizal fungi. Here we
illustrate the case of the Australasian species Laccaria fraterna, which fruits in Mediterranean shrublands of ectomycorrhizal species of Cistus (rockroses). We need to know which other Australasian fungi extend to the native ecosystems, if we are to predict environmental␣risks
associated with the introduction of Australasian ectomycorrhizal fungi into the Iberian Peninsula.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
286.
287.
Ettinger-Epstein P Tapiolas DM Motti CA Wright AD Battershill CN de Nys R 《Marine biotechnology (New York, N.Y.)》2008,10(1):64-74
The Great Barrier Reef sponge Luffariella variabilis (Poléjaeff 1884) produces a range of potent anti-inflammatory compounds as its major metabolites. These major metabolites—manoalide
monoacetate, manoalide, luffariellin A and seco-manoalide—were monitored temporally and spatially to quantify the potential
yield from wild harvest or aquaculture. Production of the major metabolites was hardwired at the population level with little
variation in space and time over meters to tens of kilometers in the Palm Islands, Queensland, Australia. Manoalide monoacetate
(35 to 70 mg g−1 dry weight of sponge) was consistently the most abundant compound followed by manoalide (15 to 20 mg g−1 dry weight). Luffariellin A and seco-manoalide were 10 to 70 times less abundant and varied between 0 and 3 mg g−1 dry weight. On a larger spatial scale, L. variabilis from Davies Reef and Magnetic Island contained the same rank order and yields of compounds as the Palm Islands, indicating
a generality of pattern over at least 100 km. The “hardwiring” of metabolite production at the population level by L. variabilis was also reflected in the lack of any inductive effect on metabolite production. In addition, individually monitored sponges
produced fixed ratios of the major metabolites over time (years). However, these ratios varied between individuals, with some
individuals consistently producing high levels of manoalide and manoalide monoacetate, providing the potential for selection
of high-yielding stocks. 相似文献
288.
Yoshiaki Tsuda Madoka Kimura Shuri Kato Toshio Katsuki Yuzuru Mukai Yoshihiko Tsumura 《Journal of plant research》2009,122(4):367-375
The genetic resources of a particular species of flowering cherry, Cerasus jamasakura, have high conservation priority because of its cultural, ecological and economic value in Japan. Therefore, the genetic
structures of 12 natural populations of C. jamasakura were assessed using ten nuclear SSR loci. The population differentiation was relatively low (F
ST, 0.043), reflecting long-distance dispersal of seeds by animals and historical human activities. However, a neighbor-joining
tree derived from the acquired data, spatial analysis of molecular variance and STRUCTURE analysis revealed that the populations
could be divided into two groups: one located on Kyusyu Island and one on Honshu Island. Genetic diversity parameters such
as allelic richness and gene diversity were significantly lower in the Kyushu group than the Honshu group. Furthermore, STRUCTURE
analysis revealed that the two lineages were admixed in the western part of Honshu Island. Thus, although the phylogeographical
structure of the species and hybridization dynamics among related species need to be evaluated in detail using several marker
systems, the Kyusyu Island and Honshu Island populations should be considered as different conservation units, and the islands
should be regarded as distinct seed transfer zones for C. jamasakura, especially when rapid assessments are required. 相似文献
289.
Suk Young Oh Chun Hua Wu Elena Popova Eun Joo Hahn Kee Yoeup Paek 《Journal of Plant Biology》2009,52(4):348-354
We tested desiccation and/or vitrification procedures to cryopreserve the adventitious roots of Panax ginseng, the source of commercially produced ginsenosides. When only desiccation was applied, the post-freeze survival of 3- to 4-mm
root tips was <14% regardless of the composition of the preculture medium or the explant origin. Callus formation was frequently
observed after cryopreservation. In contrast, 90% survival and 32.5% root formation efficiency were achieved after cryopreservation
when a vitrification protocol was followed. Adventitious root cultures in flasks and bioreactors were reestablished from root
tips cryopreserved by vitrification. A prolonged lag-phase and lower biomass production were recorded in post-freeze-regenerated
cultures compared with control roots that were subcultured four times in flasks. However, biomass accumulations did not differ
between control and regenerated roots at the end of the sixth subculturing period. After 40 days of culture in bioreactors,
a mean value of 12.5 g dw L−1 was recorded for post-freeze-regenerated cultures versus 9.1 g dw L−1 for the control roots. Production of triol and diol ginsenosides in our bioreactor cultures also was enhanced after cryopreservation,
by 41.0% and 89.8%, respectively. These results suggest that the vitrification method is successful for cryopreservation of
P. ginseng adventitious roots. 相似文献
290.
We present a model of tunnel excavation by termites that requires no pheromone labeling of soil or work sites, but instead
relies on tactile interactions and individuals who actively orient their movement. Potential termite excavators moved from
the tunnel origin towards the distal end of the tunnel and formed a queue behind those termites at the digging face. Delayed
termites excavated soil laterally from the tunnel wall at a position governed by their position in the queue of termites.
By examining excavation under artificially induced conditions of longer and shorter queues of termites at the tunnel end,
we showed that tunnel width increased with increased queue size and the rate of lateral excavation in a process we termed
“digging pressure.” 相似文献