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61.
Beatriz Rumeu Manuel Nogales Rui B. Elias David P. Padilla Tiago Resendes Airam Rodríguez Francisco Valdés Eduardo Dias 《European Journal of Forest Research》2009,128(6):567-574
Phenology and female cone characteristics of the two endemic cedars (Juniperus cedrus and J. brevifolia) from the Macaronesian islands were studied. Despite their closely taxonomic affinity and their evolution under insular conditions,
different trends were recorded. Mature J. cedrus female cones were present throughout the year, while those from J. brevifolia were only present in summer and autumn. J. cedrus female cone size was significantly larger than that of J. brevifolia, a trend consistent with the presence of larger vertebrates (lizards and birds) in the Canary Islands. However, water content
was four times higher in J. brevifolia female cones, which can be related with the higher rainfall existing in the Azores. J. cedrus has two or three seeds per cone, whereas J. brevifolia frequently had three. Seeds from J. cedrus were clearly larger and heavier, coinciding with the female cone size trend. However, tetrazolium tests revealed higher viability
values in J. brevifolia. The relatively low percentage of filled seeds in J. cedrus could be a consequence of the climatic stress and limits to pollination due to fragmented populations as described for other
Juniperus species. In summary, our results reveal that some environmental factors such as the harsh conditions, high population fragmentation
and the dependence on large dispersers have compromised the fitness of J. cedrus in the Canary Islands. 相似文献
62.
Maria Isabel Ferreira José Silvestre Nuno Concei??o Aureliano C. Malheiro 《Irrigation Science》2012,30(5):433-447
Projected climate changes and expansion of viticulture to drier regions justify the installation and management of deficit irrigation (DI) strategies. Contradictory results on the effect of DI on crops may be ascribed to the incorrect application of these techniques. The lack of discrimination between basal crop (K cb) and stress coefficients (K s) can be an obstacle to proper irrigation management. A sap flow (SF) technique associated with microlysimeters and eddy covariance (EC) methods was applied to five commercial vineyards, aiming to discriminate those coefficients, during the driest period of the vegetative cycle. A comparative analysis of the coefficients, in relation to measured vegetation parameters (for K cb) and plant water status (for K s) is presented. K cb, ranging from about 0.35 to 0.75, was highly correlated with leaf area index at stand level. K s, which decreased till 0.2 in the most stressed vineyard, was well correlated to plant water status (K s function), represented by predawn leaf water potential. K s functions for the different experiments exhibited falling slopes with decreasing water status, with variable trends depending on the rates of maximal crop transpiration (T m). These experimental results show that specific parameters for K s functions, necessary to estimate water use and irrigation depths, in order to control the stress levels in DI scheduling, are also dependent on T m. 相似文献
63.
Ruihua Li Kohji Takahashi Tomohiko Hori Akane Torita Yasushi Hasegawa 《Fisheries Science》2012,78(6):1315-1320
Elastomeric proteins occur in the shell ligament of bivalve molluscan shellfish. A newly identified protein named ligament protein-1, with a molecular mass of approximately 12 kDa, was extracted from the shell ligament of the scallop, Patinopecten yessoensis, with 70 % formic acid, and purified by gel filtration column chromatography and reverse-phase C18 column chromatography. Although the amino acid composition of this protein differs from that of the known shell ligament protein abductin, the partial amino acid sequences are similar to those of abductin. CD spectra and FT–IR spectra analyses showed that ligament protein-1 retains its secondary structures of α-helix, β-turn, and β-sheets. To the best of our knowledge, this is the first study on protein purification from the shell ligament of a bivalve molluscan shell. 相似文献
64.
Kiyoshi Sakuragi Chiaki Hori Kiyohiko Igarashi Masahiro Samejima 《Journal of Wood Science》2018,64(6):845-853
Ammonia pretreatment is a promising technique for enhancing enzymatic saccharification of lignocellulosic biomass. However, an enzymatic cocktail suitable for the breakdown of pretreated biomass samples is still being developed. The basidiomycete Phanerochaete chrysosporium is a well-studied fungus with regard to bioconversion of lignocellulosic biomass. In the present work, we analyzed proteins secreted by P. chrysosporium grown on untreated and ammonia-treated birch wood meal. Fungal growth, xylanase activity, and extracellular protease activity increased in the media containing the ammonia-treated biomass; however, cellulase production decreased compared to that observed in the untreated biomass. Secreted extracellular proteins were separated by two-dimensional electrophoresis and identified by liquid chromatography ion–trap mass spectrometry. Fifty-five spots corresponding to secreted proteins were chosen for further analysis. In the culture with ammonia-treated biomass, the relative concentration of a xylanase belonging to glycoside hydrolase (GH) family 11 increased, while acetyl xylan esterases belonging to carbohydrate esterase family 1 decreased. Moreover, GH family 10 xylanases were promoted proteolysis in the culture of ammonia-treated biomass, leading to the loss of family 1 carbohydrate-binding modules. These results indicated that P. chrysosporium produced enzymes related to the recognition of structural changes on xylan with de-acetylation and introduction of nitrogen by ammonia pretreatment of birch wood meal. 相似文献
65.
In this study, sperms collected from the right and left cauda epididymis were grouped into having canine prostatic fluid (PF) sensitization or not diluted with egg yolk Tris–fructose citrate extender, and stored at 4°C. The necessity of canine PF in cooled preservation was determined by elucidating the sperm quality after the storage. As a result, while there was no difference among all groups up to 48 hr of storage, after storage for 96 hr and more, a significantly lower sperm motility was observed in the group without being sensitized to PF than the groups with being sensitized to PF (p < .05, p < .01). Although sperm abnormality increased in all groups with increased storage time, the group without being sensitized to PF showed significantly higher sperm abnormality than did the groups with being sensitized to PF after storage for 24 hr and more (p < .01). From these findings, we concluded that PF was necessary for the cooled preservation of the canine sperm because these sperms were protected from any effects of low temperatures by being sensitized to PF. 相似文献
66.
J. S. Penha A. C. A. Lopes R. L. F. Gomes J. B. Pinheiro J. R. Assunção Filho E. A. Silvestre J. P. G. Viana J. Martínez-Castillo 《Genetic Resources and Crop Evolution》2017,64(6):1355-1364
Lima bean (Phaseolus lunatus L.) is an important food source in Brazil, especially in the northeast region, where its production and consumption are high. The goals of the present study were to estimate natural outcrossing rates and genetic diversity levels of Lima bean from Brazil, using ten microsatellite loci to obtain information for their conservation and breeding. Fourteen accessions were selected from an experiment in field with open-pollinated and with the presence of pollinating insects. Twelve seeds of each of the 14 selected accessions were grown in screenhouse for tissue harvest and DNA extraction. The multilocus model was used to determine the reproductive system. The outcrossing rate was 38.1 % (tm = 0.381; ts = 0.078), and the results indicated a mixed mating system with a predominance of selfing (1 ? tm = 61.9 %). The biparental inbreeding rate was high (t m ? t s = 0.303) and the multilocus correlated paternity was quite high (r p(m) = 0.889), indicating that the progeny was mostly composed of full sibs. The average effective number of pollen donors per maternal plant (N ep ) was low (1.12), and the fixation index for maternal genotypes (F m ) was 0.945, indicating that most genitors resulted from inbreeding. The studied families presented considerable genetic variability: A = 6.10; %P = 30; H e = 0.60 and H o = 0.077. Total diversity was high (H T = 0.596), and a portion was distributed within families (H S = 0.058). In addition, diversity was higher between families (D ST = 0.538), and genetic differentiation was high (G ST = 0.902). The results presented here can be used in the implementation of Lima bean conservation and breeding programs in Brazil. 相似文献
67.
Tiago Natal-da-Luz Serena Tidona Bruno Jesus Paula V. Morais José P. Sousa 《Journal of Soils and Sediments》2009,9(3):246-260
Background, aim, and scope Sewage sludge use in agriculture should be limited by the presence of metals and other persistent environmental pollutants.
The present study aims to contribute for the definition of a test battery of ecotoxicological assays that allows a proper
ecotoxicological characterization of sludges, providing information on their potential hazard and identified “safe” application
levels.
Materials and methods Three sludges from distinct sources (urban, olive-processing, and electroplating industries) were tested using avoidance and
reproduction tests with earthworms (Eisenia andrei) and springtails (Folsomia candida) and plant growth tests with turnips (Brassica rapa) and oats (Avena sativa). Different soil–sludge mixture concentrations mimicking recommended/realistic field dosages were tested.
Results Only the sludge from the electroplating industry induced an avoidance response from the earthworms (EC50 = 0.4 t/ha) and collembolans (no observed effect concentration (NOEC) = 15 t/ha). This sludge was the only sludge responsible
for any effect on the reproductive output of the earthworms (EC50 = 7.74 t/ha). Regarding collembolans, none of the sludges tested caused any significant decrease in reproduction. In higher
plant tests, the two industrial sludges were toxic, causing a decrease growth in both species. The EC20 values determined for B. rapa were 20.3 and 24.2 t/ha and for A. sativa 14.7 and 16.2 t/ha for sludges from olive-processing and electroplating industries, respectively.
Discussion The metal loadings of the different test sludges could partially explain the results obtained. The toxicity of the test sludge
from electroplating industry observed on the tested invertebrates and plants could be explained by the high amount of total
chromium from which 22.3% was in the most toxic oxidation state—Cr(VI). However, the toxicity caused by the sludge from the
olive-processing industry in the test plants could be attributed to the presence of other compounds (not measured in this
study) since the metal content was not high enough to induce such an effect. The absence of toxicity showed by the urban test
sludge was in agreement with its low levels of metals.
Conclusions The response of the different test organisms and end points varied according to the sludge type. The urban sludge was non-toxic
whereas the sludge from the electroplating industry caused a toxic effect on almost all parameters measured (avoidance behavior
of both test organisms, reproduction of earthworms, and growth of both plant species). Sludge from the olive-processing industry
only caused a toxic effect on growth of both plant species. By analyzing the sensitivity of the different parameters for the
most toxic sludge, it was found that avoidance and reproduction were more sensitive than plant growth, whereas plant seed
germination was not sensitive at all.
Recommendations and perspectives The ecotoxicological evaluation of wastes can be used as an environmental safety control of sludge use in agriculture. A tiered
approach could be adopted for this purpose, incorporating avoidance tests in the first tier (screening level) and reproduction
and plant growth tests in a second tier. But more evidence aiming to define the most suitable ecotoxicological test battery
for specific sludges with a different contamination profile is still needed. 相似文献
68.
Andrés Pérez-Figueroa Rick L. Wallen Tiago Antao Jason A. Coombs Michael K. Schwartz P.J. White Gordon Luikart 《Biological conservation》2012,150(1):159-166
Loss of genetic variation through genetic drift can reduce population viability. However, relatively little is known about loss of variation caused by the combination of fluctuating population size and variance in reproductive success in age structured populations. We built an individual-based computer simulation model to examine how actual culling and hunting strategies influence the effective population size (Ne) and allelic diversity in Yellowstone bison over 200 years (~28 generations). The Ne for simulated populations ranged from 746 in stable populations of size 2000 up to 1165 in fluctuating populations whose census size fluctuates between 3000 and 3500 individuals. Simulations suggested that ~93% of allelic diversity, for loci with five alleles will be maintained over 200 years if the population census size remains well above ~2000 bison (and if variance in male reproductive success is high). However for loci with 20 alleles, only 83% of allelic diversity will be maintained over 200 years. Removal of only juveniles (calves and yearlings) resulted in longer generation intervals which led to higher maintenance of allelic diversity (96%) after 200 years compared to the culling of adults (94%) when the mean census size was 3250 (for loci with five alleles). These simulations suggest that fluctuations in population census size do not necessarily accelerate the loss of genetic variation, at least for the relatively large census size and growing populations such as in Yellowstone bison. They also suggest that the conservation of high allelic diversity (>95%) at loci with many alleles (e.g., ?5) will require maintenance of a populations size greater than approximately 3250 and removal of mainly or only juveniles. 相似文献
69.
Muhammad Shahid Camille Dumat Bertrand Pourrut Jérôme Silvestre Christophe Laplanche Eric Pinelli 《Journal of Soils and Sediments》2014,14(4):835-843
Purpose
In spite of substantial advancement in recent past, the role of metal speciation in assessing biogeochemical behaviour of Pb is still topical. Organic ligands are capable to modify Pb speciation in nutrient/soil solution and in turn its soil–plant transfer and toxicity. In this sense, the main objective of this study was to evaluate the effect of organic ligands on Pb-induced oxidative stress to Vicia faba roots.Materials and methods
V. faba seedlings grown to controlled hydroponic system were treated with 5 μM Pb as lead nitrate in the presence and absence of organic ligands viz ethylenediaminetetraacetic acid (EDTA) and citric acid (CA) for 1, 4, 8, 12, and 24 h. The chemical speciation of Pb (percent free and chelated Pb) in nutrient solution in the presence and absence of organic ligands was calculated using Visual Minteq speciation model. The effect of chemical speciation on Pb-induced oxidative stress to V. faba roots was investigated using plant enzymatic antioxidative system [superoxide dismutases (SOD), guaiacol peroxidise (GPX), ascorbate peroxidase (APX), glutathione reductase (GR), and catalase (CAT)]. The antioxidant enzymes activities were determined using ultraviolet spectrophotometer.Results and discussion
The activities of SOD, GPX, APX, and GR significantly increased whereas that of CAT decreased in V. faba roots under Pb alone treatment. Lead-induced increase/decrease in antioxidant enzymes activities was not linear but varies with treatment exposure time. EDTA dose dependently inhibited Pb-induced changes in antioxidant enzymes activities. However, CA did not cause any significant change in Pb-induced variation in antioxidant enzymes activities, but delayed or slightly reduced the Pb effect.Conclusions
The present study suggested that physiological responses of V. faba roots to Pb toxicity vary with applied Pb form and duration of exposure. EDTA can inhibit Pb-induced toxicity to V. faba seedlings by forming stable Pb-EDTA complexes due to its high binding strength for Pb. However, CA had no effect on Pb-induced toxicity to V. faba roots due to weak complexation with Pb. 相似文献70.