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61.
Maria João Feio Trefor B. Reynoldson Verónica Ferreira Manuel Augusto S. Graça 《Hydrobiologia》2007,579(1):55-68
We sampled macroinvertebrates at 75 locations in the Mondego river catchment, Central Portugal, and developed a predictive
model for water quality assessment of this basin, based on the Reference Condition Approach. Sampling was done from June to
September 2001. Fifty-five sites were identified as “Reference sites” and 20 sites were used as “Test sites” to test the model.
At each site we also measured 40 habitat variables to characterize water physics and chemistry, habitat type, land use, stream
hydrology and geographic location. Macroinvertebrates were generally identified to species or genus level; a total of 207
taxa were found. By Unweighted Pair Group Method with Arithmetic mean (UPGMA) clustering and analysis of species contribution
to similarities percentage (SIMPER), two groups of reference sites were established. Using Discriminant Analysis (stepwise
forward), four variables correctly predicted 78% of the reference sites to the appropriate group: stream order, pool quality,
substrate quality and current velocity. Test sites’ environmental quality was established from their relative distance to
reference sites, in MDS ordination space, using a series of bands (BEAST methodology). The model performed well at upstream
sites, but at downstream sites it was compromised by the lack of reference sites. As with the English RIVPACS predictive model,
the Mondego model should be continually improved with the addition of new reference sites. The adaptation of the Mondego model
methodology to the Water Framework Directive is possible and would consist mainly of the integration of the WFD typology and
increasing the number of ellipses that define quality bands.
Handling editor: K. Martens 相似文献
62.
63.
Charles L. Nunn Peter H. Thrall Kelly Stewart Alexander H. Harcourt 《Evolutionary ecology》2008,22(4):519-543
Emerging infectious diseases threaten a wide diversity of animals, and important questions remain concerning disease emergence
in socially structured populations. We developed a spatially explicit simulation model to investigate whether—and under what
conditions—disease-related mortality can impact rates of pathogen spread in populations of polygynous groups. Specifically,
we investigated whether pathogen-mediated dispersal (PMD) can occur when females disperse after the resident male dies from
disease, thus carrying infections to new groups. We also examined the effects of incubation period and virulence, host mortality
and rates of background dispersal, and we used the model to investigate the spread of the virus responsible for Ebola hemorrhagic
fever, which currently is devastating African ape populations. Output was analyzed using regression trees, which enable exploration
of hierarchical and non-linear relationships. Analyses revealed that the incidence of disease in single-male (polygynous)
groups was significantly greater for those groups containing an average of more than six females, while the total number of
infected hosts in the population was most sensitive to the number of females per group. Thus, as expected, PMD occurs in polygynous
groups and its effects increase as harem size (the number of females) increases. Simulation output further indicated that
population-level effects of Ebola are likely to differ among multi-male–multi-female chimpanzees and polygynous gorillas,
with larger overall numbers of chimpanzees infected, but more gorilla groups becoming infected due to increased dispersal
when the resident male dies. Collectively, our results highlight the importance of social system on the spread of disease
in wild mammals. 相似文献
64.
65.
Haploid plants were regenerated in vitro from unpollinated ovules of niger (Guizotia abyssinica (L. f.) (Cass.) on Murashige and Skoog nutrient medium (MS) supplemented with 10 μM naphthaleneacetic acid or 10 μM NAA +
1.5 μM kinetin and 30 g/l sucrose. Gamborg (B5) medium was the best for plant regeneration (in comparison with MS, Nitsch
and Nitsch (NN), and Chu (N6) media) from cultured ovules, and 6.66 and 7.33 ovules of JNC-6 and Ootacamund cultivars were
involved in direct plant regeneration on this medium. Matured ovules (ovules collected one day before anthesis or on the day
of anthesis) only responded to cultural regimes and involved in direct plantlet development. Cytological preparation of root
tips and chloroplast counts in the guard cells of leaf stomata of regenerated plants confirmed their haploid nature.
This text was submitted by the authors in English. 相似文献
66.
67.
Isolation and screening of potential actinobacteria for rapid composting of rice straw 总被引:2,自引:0,他引:2
Rice straw is produced as a by-product from rice cultivation, which is composed largely of lignocellulosic materials amenable
to general biodegradation. Lignocellulolytic actinobacteria can be used as a potential agent for rapid composting of bulky
rice straw. Twenty-five actinobacteria isolates were isolated from various in situ and in vitro rice straw compost sources.
Isolates A2, A4, A7, A9 and A24 were selected through enzymatic degradation of starch, cellulose and lignin followed by the
screening for their adaptability on rice straw powder amended media. The best adapted isolate (A7) was identified as Micromonospora
carbonacea. It was able to degrade cellulose, hemicelluloses and carbon significantly (P ≤ 0.05) over the control. C/N ratio was reduced to 18.1 from an initial value of 29.3 in 6 weeks of composting thus having
the potential to be used in large scale composting of rice straw. 相似文献
68.
E. P. Isakova Yu. I. Deryabina N. N. Gessler T. A. Belozerskaya Ya. M. Rabinovich 《Applied Biochemistry and Microbiology》2010,46(3):318-323
Cell respiratory activity of protoplasts obtained from the wild type of Neurospora crassa and photoreceptor complex WCC—white collar 1 (wc-1) and white collar 2 (wc-2)—mutants of Neurospora crassa strains was investigated. Respiration inhibition by KCN in the presence of 25 mM succinate was similar in all strains and
did not exceed 83–85% against control. The significant induction of KCN-resistant respiratory pathway occurred under 1% glucose
oxidation in wc-1 and wc-2 mutants if compared with the wild type strains. The inhibitors of the main (cytochrome) pathway of electron transfer in mitochondria—1
mM KCN and antimycin A (4 μg/ml)—blocked the respiration rate of the protoplasts from N. crassa wild type by 75%, while the cell respiration of wc-1 and wc-2 strains was suppressed by approximately 50%. The specific inhibitor of alternative oxidase—10 mM salicylhydroxamic acid (SHAM)—in
combination with the blockers of mitochondrial electron transfer chain caused the total suppression of respiratory activity
of protoplasts in all studied strains. It is supposed that an increase of KCN-resistance in WCC mutants under glucose oxidation
is connected with alternative oxidase activation as the result of failure in reception and signal transduction of active oxygen
species. 相似文献
69.
J. C. O’Hanlon 《Journal of Ethology》2011,29(1):47-54
Tree trunks are spatially separated habitat patches for the tree-running mantid Ciulfina biseriata (Mantodea: Liturgusidae). This paper investigates how intraspecific interactions may affect spacing patterns in C. biseriata. Many mantid species inhabit tree trunk surfaces, but little is known about how they interact with this type of habitat.
Behavioural observations and choice tests investigated the effect of a conspecific on habitat utilisation. Field surveys were
used to investigate patterns of movement in the field. The decision to inhabit a tree trunk may be affected by the presence
of a conspecific. Whereas adult males seek out females when selecting habitat, females will actively avoid males. Habitat
choice decisions are primarily based on aspects of their mating system rather than on competition for space or food resources.
The behavioural interactions of C. biseriata are described, including novel observations of same-sex mating behaviour in adult males. 相似文献
70.
The Kelvin-Helmholtz instability is investigated analytically by using a one-dimensional nonuniform model of the Earth’s magnetosphere
and the adjacent solar wind region. Its properties are shown to be essentially governed by the presence of an MHD cavity that
arises in the magnetosphere because of the non-uniformity of the latter and also because of the jump in the parameters of
the medium at the magnetopause (the outer boundary of the magnetosphere). System oscillations constitute a discrete spectrum
of eigenmodes, which are determined by the wave vector k
t
along the tangential discontinuity and also by the mode number n = 0, 1, 2, …, playing the role of the wavenumber along a coordinate normal to the magnetopause. Analytic expressions are
obtained for the frequency and instability growth rate of each eigenmode and for the functions describing its spatial structure.
All these quantities depend parametrically on the solar wind velocity V
W
, or more precisely, on the Doppler frequency shift ω
W
= k
t
· V
W
. For each eigenmode, there is a lower instability threshold depending on the parameter ω
W
and a sharp maximum in the growth rate at the eigenfrequency of the magnetospheric cavity. For ω
W
values below the threshold, the properties of an eigenmode are highly sensitive to the type of solar wind nonuniformity.
Three cases are considered: a uniform solar wind and solar winds in which the speed of sound increases or decreases away from
the magnetopause. 相似文献