Feeding biology and thermal adaptations of the terrestrial isopod Mesoniscus graniger were studied. M. graniger is a depigmented isopod mainly inhabiting cave systems, although it has also been reported in endogeic (soil) habitats. Physiological adaptations are expected to reflect the unique environmental characteristics of caves, including restricted food sources, and stable microclimate with temperatures not exceeding about 10 °C and high relative humidity. The M. graniger from Domica and Ardovská caves (Slovakian Karst) were investigated. We identified organic deposits with associated microorganisms as sources exploited by M. graniger and assessed how these might supply essential polyunsaturated fatty acids (PUFA) in its nutrition. Algae, fungi and bat guano were found as the most important potential resources of PUFA for isopods. Digestive enzymes amylase, trehalase, saccharase and maltase were confirmed in the whole body homogenates of isopods; neither cellulolytic activity nor activities against xylan, laminaran and lichenan were observed. Amylase, maltase and cellobiase activities were also observed in bacterial strains isolated and cultured from isopod midgut, and may account for the measured whole-animal activities. In an artificial temperature gradient, M. graniger selected temperature 3.5 ± 5.4 °C with lower and upper extremes of –1.5 and 18.5 °C. Respiration, as measured by VO2, was almost independent of temperature between 5 and 10 °C, then increased between 10 and 30 °C. These ecophysiological measures are consistent with adaptation to a stenothermal environment. 相似文献
The Pampa region is the most important agricultural area in Argentina. Although intensive agricultural activity is leading to important levels of soil degradation, studies on the impact on soil fauna are scarce. Despite the environmental importance of collembolans, symphylans and pauropods in soil, information on the influence of land management on their population densities is poor, particularly in Neotropical agroecosystems. The aim of this study was to investigate the effects of different management systems on the density of collembolans, symphylans and pauropods. Population abundance of these arthropods was examined in a natural site and a cattle raising, a mixed and an agricultural management system on a Typic Hapludoll soil in La Colacha, Córdoba, Argentina. All the sites studied had the same land use history until approximately 50 years before sampling and have the same soil type. Total abundance of the studied groups varied in the different management systems. Our results suggest that conventional agricultural management tends to reduce the density of collembolans and pauropods. Our data do not support our hypothesis that the cattle raising management system constitutes an intermediate situation between the natural site and the high-input management systems. We conclude that the reduction of collembolan and pauropod densities in high-input management systems is largely explained by the mechanical and chemical perturbations produced by conventional agricultural management practices and by particular abiotic soil conditions present in the intensively managed sites that are unfavourable for these organisms. Surprisingly, symphylans were more abundant in the mixed management site. The implications of our findings on soil ecosystem functioning are discussed. 相似文献
Symptoms of manganese toxicity in beans (Phaseolus vulgaris L) In water culture experiments with bush bean plants (Phaseolus vulgaris L. var. ?Red Kidney”?) the macro- and micro-symptoms of manganese toxicity had been studied. Typical symptoms of Mn toxicity are small distinct blackish-brown spots, first at the older leaves and at more severe toxicity also at the petals and stems. Using the autoradiographic technique on 54Mn-distribution and comparing this with corresponding light microscopic studies it could be demonstrated that the blackish-brown spots in the leaves resemble Mn-precipitations. These precipitations are Mn-compounds of higher oxidated form and are primarily localized in the walls of cells in vicinity of the vessels. The extend to which these precipitations occur is not only a function of the Mn-content of the leaves but also of their age. At comparable Mn-content the extend of the precipitation increases with the leaf age. As secondary symptom of Mn-toxicity under certain conditions (presence of silicon e.g.) induced Fe deficiency (chlorosis of the youngest leaves) and Ca deficiency (?crinkle leaf”?) may occur. It is assumed that the process of Mn precipitation within the leaves is enzymatically regulated. The severe reduction in the growth of leaf blades at Mn toxicity is presumably related to an interference with the growth hormon balance. 相似文献
Polycyclic Aromatic Hydrocarbons (PAHs) in soils of the Münster (Westfalia) irrigation fields From 1901 to 1975 municipal sewage waters with a daily amount of finally about 40.000 m3 were seeped in the irrigation fields of the city of Münster (Westfalia). Soil samples of former seeped sites and non-seeped neighbour sites have been examined with regard to 6 polycyclic aromatic hydrocarbons (PAHs) of the German “drinking water regulation”. The irrigation caused an enrichment of PAH in the topsoils of the former irrigation basins up to an average concentration of 0,57 mg PAH/kg soil, while the topsoils outside of the irrigation fields show an average concentration of only 0,14 mg PAH/kg soil. Significant correlations between different soil properties, e.g. the organic matter content, and the concentration of PAHs are not evident. After termination the irrigation of sewage water, single irrigation bassins were filled with substratum, which is contaminated with scoriaceous materials. The average PAH concentration of such an area amounts to 7 mg PAH/kg topsoil. The PAH distribution in a soil profile shows a decreasing concentration by depth but a clear enrichment in oxidized gleyic horizons (Go) of different age. Probably the PAHs were leached under recent conditions by chemical bond to dissolved organic carbon (DOC) and finally adsorbed by Fe oxides. Since the end of irrigation Fluoranthene, the most mobile PAH compound, was leached down to 110 cm depth. A contamination of the superficial groundwater at such sites cannot be excluded. 相似文献
Small soil-dwelling annelids (Enchytraeidae, Tubificidae, Aeolosomatidae) were investigated at two sites in the White Carpathians (Czechia), each consisting of one meadow and one cattle pasture. Sampling was conducted on four dates during a 1-year period (2002–2003). Enchytraeid species numbers ranged from 11 to 17, with more species found in the meadows. The most abundant species were Enchytraeusbuchholzi s. l., Fridericiaisseli, Fridericiasemisetosa, Fridericiagalba, Fridericiabulboides, Fridericiabisetosa, Cernosvitoviellaminor (in the meadows), and Achaeta spp. (in one of the pastures). Henlea spp. preferred the pastures. Rhyacodrilusfalciformis was recorded in all plots, Aeolosomahemprichi and A. cf. niveum in one meadow plot. Enchytraeid densities reached up to 13 750 individuals m−2, later drought led to much lower values. Densities were generally higher in meadows than in pastures. The vertical distribution differed between meadows and pastures: higher percentages of individuals were present in the upper 6 cm of pasture soil. 相似文献
Synthethic goethite specimens have been prepared by a variety of experimental methods, and it has been possible to incorporate large quantities of Al ( 30 mol %) into the structure. A range of particle sizes also obtained and these were dependent upon both experimental conditions and the extent of aluminium substitution. Mössbauer spectra have been recorded for a large number of samples and show that high levels of A1-substitution combined with small particle sizes have a dramatic effect on the magnetic properties of the mineral. The application of Mössbauer spectroscopy to the identification of secondary iron oxide phases in soils is thus complicated by aluminium substitution and some of the difficulties are discussed. 相似文献
Genetic diversity of 70 populations of niger (Guizotia abyssinica) representing all its growing regions in Ethiopia was investigated using random amplified polymorphic DNA (RAPD) to reveal
the extent of its populations genetic diversity. Ninety-seven percent of the loci studied was revealed to be polymorphic for
the whole data set. The within population diversity estimated by Shannon diversity index and Nei gene diversity estimates
was revealed to be 0.395 and 0.158, respectively. The extent of genetic variation of populations from major niger producing
regions was significantly lower than that of populations from other regions; however, it is distributed regardless of altitude
of growth. Genetic differentiation between populations was estimated with Shannon index as G′ST (0.432), Nei’s GST (0.242) and AMOVA based FST (0.350) and appears to be equivalent to the average values calculated from various RAPD based studies on outcrossing species.
Higher proportion of the variation detected by AMOVA resided within populations (64.58%) relative to the amount of variation
among populations (35.42%). UPGMA cluster analysis showed that most of the populations were clustered according to their region
of origin. However, some populations were genetically distant from the majority and seem to have unique genetic properties.
It is concluded that the crop has a wide genetic basis that may be used for the improvement of the species through conventional
breeding and/or marker assisted selection. Collection of germplasm from areas not yet covered and/or underrepresented is the
opportunity to broaden the genetic basis of genebank collection. 相似文献
A study was carried out during 2001 on mine tailings in NW Bohemia aimed at describing the spatial patterns of nests distribution and epigeic activity of ants in relation to the vegetation mosaic. Lasius niger was the most abundant species of ant and its nest mounds were significantly more numerous in patches with sparse vegetation than inside dense Calamagrostis epigejos vegetation; this was particularly true for small and medium-sized nests. Small and medium nests also occurred more frequently near the edges of a given patch than in the center. Large and medium nests were randomly distributed in the area, whereas small nests had an aggregated distribution. Pitfall trapping reveal significantly higher activity of L. niger workers in tall and dense vegetation stands in comparison with low and sparse vegetation. This pattern was particularly pronounced during the peak of foraging activity in summer and was not so significant in spring or autumn. We expect that ant preferentially forage in shaded habitats during the summer months when bare soil may be too hot. The results indicated that nesting and foraging may differ in their microclimatic requirements and the formation of vegetation mosaics may be important to changes in the ant population during succession. 相似文献
Jojoba (Simmondsia chinensis (Link) Schneider) is an obligate cross-pollinated shrub native to the Sonora desert. The most valuable product of the jojoba
seeds is the liquid wax or jojoba oil which is marketed extensively in the cosmetic industry. Differing from the most of the
cultivated crop species, jojoba has slow-growing habit, difficulties in the determination of sex at the early seedling stages,
a male-biased ratio and low seed yield. In jojoba, the development of molecular strategies for the identification of sexes
at early stages has been a priority in plantations and breeding programs. Two previous studies reported two candidate male-specific
jojoba DNA markers. However, present study indicated that these markers were not useful in jojoba sex identification. A reliable
gender diagnostic marker for jojoba is, therefore, needed. In the present study a novel jojoba male-specific touch-down polymerase
chain reaction based DNA marker (JMS900) was reported using a total of 120 individual jojoba plants bulked into 16 samples.
This sex specific DNA marker may have considerable theoretical and practical applications in the establishment of jojoba plantation
and breeding studies. 相似文献
Nitrification in soils A literature review is given on the biology of nitrifying organisms, the nitrification process in soil and factors influencing nitrification in soil with special reference to the following aspects:
1 Importance of nitrification in the nitrogen cycle.
2 Biology of nitrifying micro-organisms.
2.1 Chemolithotrophic bacteria and heterotrophic micro-organisms.
2.2 Physiology and biochemistry of nitrifying micro-organisms: gain of energy, specifity and concentration of substrate, influence of soil reaction.
3. Methods for the measuring nitrification in soil.
3.1 Experiments for the determination of nitrification.
3.2 Calculation of the nitrification process.
4. The course of nitrification in different soils.
4.1 Rate of nitrification.
4.2 Influence of various environments: soil reaction, temperature, oxygen and water content.
Genesis of Secondary Al-(Fe-)Chlorites Comparing the results of soil investigations with those obtained from laboratory syntheses it was concluded that secondary Al-Fe-chlorites in soils of moderate cool-warm-humid climates mainly develop through protonisation of Al and Fe in the mineral structure of expanded dioctahedral vermiculites with subsequent hydrolysis in the interlayer space. In this process characteristics of the mineral itself (e.g. layer charge) as well as carbonic acid and soil organic acids (as proton suppliers) are the most important factors. From this, the further conclusion was drawn that in the pH-range 6, 5–6 secondary chlorites begin to develop increasingly until pH5 (development conditions) and in the pH-range 5–4,5“conservation conditions” exist. - At pH<4,5 secondary chlorites are unstable (dissolution conditions) through protonisation of Al-Fe-hydroxy polymers (reverse of hydrolysis) with subsequent solubilization and leaching especially through complexation by soil organic acids. - As remaining minerals in this weathering sequence smectites occur, resulting from the decrease of layer charge in vermiculites through the chloritization process, thus indicating that chloritization may be an important process for the genesis of smectites under acid weathering conditions. 相似文献
The aim of this work was to determine whether the endogeic earthworm Hormogaster elisae [1] is involved in the active or passive predation of microarthropods at El Molar (Madrid, Spain). Different techniques were employed to study the gut content, and the casts of H. elisae earthworms cultivated in the laboratory. The casts consisted mainly of mineral particles and plant remains as well as a few microarthropods, nematodes and their remains. The gut contents were similar in composition, although no microarthropod remains were found, except for a single springtail (order Poduromorpha) in one earthworm's gizzard. The results suggest that H. elisae may accidentally ingest microarthropods along with soil. The microarthropods found in the casts may have colonized them after their deposition since none were found in isolated casts. 相似文献
Selective feeding of the earthworm Hormogaster elisae was investigated by granulometric analysis, chemical fractionation and physical fractionation of the soil in which representatives were cultivated, and of their casts. H. elisae behaved as an endogeic species, mainly consuming soil from which it weakly but positively selected the organic fractions of greatest size (mainly free organic matter) and negatively selected the largest mineral fraction (coarse sand). No significant selection of intermediate size fractions was recorded. The 0–2 μm granulometric fraction (clays) was also selected; the results suggest that some of the organic components of this size fraction can also be used by the species. 相似文献
Bisphenol A (BPA) and reactive black 5 (RB5) dye are among the most persistent and non-biodegradable contaminants in water which require an urgent need for the development of effective removal method. The ubiquitous existence of both contaminants could interfere with the human health and aquatic environmental balance. Photocatalytic process as one of advanced oxidation processes (AOPs) has shown high performance for degradation of organic compounds to the harmless materials under sensible condition. Therefore, this study aims to develop a visible-light-driven photocatalyst that can efficiently degrade BPA and RB5 present in household water. N-doped TiO2 were successfully synthesized via simple and direct sol–gel method. The prepared TiO2 nanoparticles were characterized by field emission scanning microscope (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Brunauere Emmette Teller (BET) analysis. The incorporation of nitrogen in TiO2 lattice exhibited excellent optical responses to visible region as revealed by UV–Vis–NIR spectroscopy absorption capability at 400–600 nm. The photocatalytic activity of the N-doped TiO2 nanoparticles was measured by photocatalytic degradation of BPA and RB5 in an aqueous solution under visible-light irradiations. Degradation of BPA and RB5 was 91.3% and 89.1%, respectively after 360 min illumination. The degradation of BPA and RB5 by N-doped TiO2 was increased up to 89.8% and 88.4%, respectively under visible-light irradiation as compared to commercial TiO2 P25. This finding clearly shows that N-doped TiO2 exhibits excellent photocatalytic degradation of BPA and RB5 under visible irradiation, hence have a promising potential in removing various recalcitrant contaminants for water treatment to fulfill the public need to consume clean water.
Sequence variation of nuclear internal transcribed spacer regions of ribosomal DNA (ITS1, 5.8S rRNA and ITS2) from Chinese
vegetable mustards (AB-genome) and its putative parents Brassica rapa (the A-genome) and Brassica nigra (the B-genome) were used to investigate the molecular phylogeny and the probable evolutional pattern of this amphidiploid
species that uniquely formed in China. Totally, 16 accessions of Chinese vegetable mustard those covering nearly all the diverse
variations were included in this study, and together with three accessions of B. rapa and one accession of B. nigra. The results disclosed two strongly supported clades, one containing four accessions of vegetable mustard which have closer
relationship with B-genome species “B.nigra” lineage and the other containing 12 accessions of B. juncea and three A-genome accessions. This classification was in disagreement with the evidence from chloroplast DNA, mitochondrial
DNA, nuclear DNA restriction fragment length polymorphism (RFLP), which suggested that B. juncea was closely related to the A-genome type. For the incongruence, we speculated that the B. juncea crops derived from Chinese have evolved through different recombined events of the diploid morphutypes and evolved unidirectional
concerted evolution. The traditional phenotypic classification of B. juncea was not wholly supported by ITS results, and hence the phylogenetic relationships among these subspecies need to be reconsidered
on molecular level. 相似文献
Sanchi ginseng (Panax notoginseng (Burkill) F. H. Chen) has been cultivated in China for more than 400 years, whose root is an important traditional Chinese
medicine mainly used to stanch blood, to disperse gore and to reduce pain caused by injury due to falls. The cultivated populations
of this crop are distributed in Wenshan mountain area of Yunnan with a narrow habitat, whose location is around N 23.5°, E
104° and altitude ranges from 1,200 to 2,000 m. Although its wild species has not been found, current cultivated populations
show rich morphological variations in stem, leaf, root, flower and fruit. Recent studies exhibit that Sanchi root has more
active compounds than the roots of P. ginseng and P. quinquefolius. Therefore, this crop needs further utilization. 相似文献
Soil purple phototrophic bacterial (PPB) communities and their responses to elevated atmospheric carbon dioxide (CO2) concentration and nitrogen (N) fertilizer were investigated under a rotation of paddy rice (Oryza sativa L.) and winter wheat (Triticum aestivum L. cv. Yangmai 14) cultivation in a FACE (free‐air CO2 enrichment) system. Community structures and abundances of PPB were determined by denaturing gradient gel electrophoresis (DGGE) and real‐time quantitative PCR respectively, targeting the pufM gene, which encodes a protein in the light reaction centre of PPB. Soil PPB communities were more diverse and larger under rice than under wheat cultivation, which may be attributed to the flooding of the paddy field and soil moisture changes. Elevated atmospheric CO2 concentration significantly increased the abundance and biodiversity of PPB in soils under rice cultivation, while N fertilizer application rate had less effect on the abundance and diversity. Phylogenetic analysis showed that two common dominant DGGE bands belonged to Bradyrhizobium‐ and Rhodopseudomonas palustris‐like PPB in both rice and wheat soils. The results demonstrated a significant shift in soil PPB communities during the rice‐wheat rotation, and a strong positive response of PPB communities to an elevated atmospheric CO2 concentration. Our results also indicated that a diverse and abundant soil PPB community could occur in upland crop fields as well as in aquatic environments and paddy‐rice fields. These findings extend our understanding of the ecological significance of PPB in terrestrial soil environments and their responses to future climate change. 相似文献
The phytotoxicity of tropospheric ozone at elevated concentrations can cause severe effects on plant vegetation. This study analyzed whether ozone-damaged plants transmit signals into the soil and thereby affect the structural diversity of bacteria inhabiting the rhizosphere. To generate highly stressful conditions, Malva sylvestris was raised from seeds under ozone exposure. Additionally, the plant age at the onset of ozone-stress was varied. Rhizosphere bacterial communities were analyzed by single-strand conformation polymorphism (SSCP) of PCR amplified partial 16S ribosomal RNA genes. None of these vigorous stress conditions caused a change in the genetic profiles targeting Bacteria with primers hybridizing to highly conserved regions in the 16S rRNA genes, despite visibly ozone-triggered injuries of the leaves and a reduced root biomass. Differences in the SSCP profiles however were observed between plants of different ages. In a more realistic scenario, plants raised in the greenhouse under normal atmospheric conditions were exposed to ozone episodes as they can occur during summer in industrialized countries of the northern hemisphere. To increase the sensitivity of detection, genetic profiles representing Alphaproteobacteria, Actinobacteria and Pseudomonas were analyzed separately in addition to those of Bacteria. None of the profiles showed any ozone-related alterations. In summary, the results of this study indicated that, even when the plants were visibly injured by ozone, the stress was not transmitted to the soil in a way that affected the structural diversity of the dominant rhizosphere bacterial community. 相似文献
