1,301 research outputs found
Un caso de osteomielite num individuo paleo-cristião de Vale do Mouro (Meda, Guarda, Portugal)
X Congreso Nacional de Paleopatología. Univesidad Autónoma de Madrid, septiembre de 200
Microhabitat use by endangered Iberian cyprinids nase Iberochondrostoma almacai and chub Squalius aradensis
Research ArticleOver the last decade there has been a major
rise in the number of attempts at fish conservation and
management as a response to the widespread degradation
of aquatic ecosystems. The assessments involved
are rarely planned and executed with inputs
from the species life history, particularly their microhabitat
use over space and time.The seasonal and sizerelated
microhabitat use of two critically endangered
cyprinids – the Iberian nase Iberochondrostoma
almacai and Iberian chub Squalius aradensis – was
examined at seven sites across four small catchments
in southwest Portugal. Both species displayed nonrandom
microhabitat use. In autumn, nase preferred
more sheltered (>50% cover) habitats with small
substrata (organic cover and silt) than in summer,
while chub were found to occupy significantly fasterflowing
habitats areas (>10 cm/s) with coarser substrata
(>50 mm particle size) in the spring than in the
rest of the year. Size-related analyses indicated that young-of-year (yoy) nase used coarser substrata
(>5 mm particle size) and more exposed habitats
(<50% cover) than adult nase. Adult chub, on the
other hand, occupied coarser substrata (>50 mm
particle size) and faster-flowing areas (>10 cm/s)
than yoy and juveniles. Based on these findings, it
was possible to assign the species to ecological guilds
and to classify them as limnophilic (nase) and
eurytopic and lithophilic (chub). Both species generally
occupied distinct microhabitats, although resource-
use overlap was significant in summer. During
this season, overlap was found between yoy nase and
chub, juvenile nase and juvenile/adult chub, and
between adults of both species. The present study
identified key factors in the species habitat requirements
and helped develop management recommendations
for river restoration that may have a wider
application, particularly for other Mediterraneantype
river
Moderate biomanipulation for eutrophication control in reservoirs using fish captured in angling competitions
Angling competitions are a popular leisure activity in reservoirs of
Southern Portugal. These competitions can gather more than 100 anglers
aiming to catch the maximum fish weight. Groundbaiting and catch-andrelease
angling are two common practices for anglers in competition. In
this study, the loads of nutrients from commercial groundbait powders
used in angling competitions in the Maranhão reservoir and the possible
balance out of those nutrients through a moderate biomanipulation of the
fish biomass caught in competitions were analysed. In order to achieve
this aim, chemical analyses to groundbait powders most purchased by
Portuguese anglers and to fish species most captured in competitions
were made. Mass balances on inputs and outputs of nutrients considering
some biomanipulation scenarios were evaluated. Results demonstrated
that an effective management on angling competitions implementing a
moderate biomanipulation of fish in reservoirs could promote the control
of fish fauna and eutrophication, balancing out nutrients from anglinginfo:eu-repo/semantics/publishedVersio
Fish-based groups for ecological assessment in rivers: the importance of environmental drivers on taxonomic and functional traits of fish Assemblages
The use of river-types is of practical value, serving as groups for which
assessment procedures can be developed and applied. An abiotic typology
was set by the Portuguese Water Agency, mainly based on 6 major
morphoclimatic regions. However, to be biologically meaningful, this typology
should fit the distribution patterns of the biological quality elements
communities proposed in Water Framework Directive under the lowest
possible human pressure. This study aimed to identify and characterize
fish-based geographical groups for continental Portugal and their environmental
and geographical discriptors, using taxonomic and functional
traits. Sampling took place between 2004 and 2006 during Spring. Fish
fauna from 155 reference sites was analysed using a multivariate
approach. Cluster Analysis on fish composition identified 10 fish-groups,
expressing a clear correspondence to the river basin level, due to the
restrict basin distribution of many species. Groups showed a wider aggregation
in 4 regions with a larger geographical correspondence, statistically
supported by Similarity Analysis, both on fish composition and mostly on
fish metrics/guilds. Principal Components Analysis revealed major environmental
drivers associated to fish-groups and fish-regions. Fish-groups
were hierarchically grouped over major and local regions, expressing a
large-scale response to a North-South environmental gradient defined by
temperature, precipitation, mineralization and altitude, and a regional scale
response mainly to drainage area and flow discharge. From North to
South, fish-regions were related to the morphoclimatic regions. Results
contributed to reduce redundance in abiotic river-types and set the final
typology for Portuguese rivers, constituting a fundamental tool for planning
and managing water resources
Identification and Validation of EST-Derived Molecular Markers, TRAP and VNTRs, for Banana Research
The advent of high-throughput sequencing technology has generated abundant information on DNA sequences for the genomes of many plant species. Expressed Sequence Tags (ESTs), which are unique DNA sequences derived from a cDNA library and therefore representing genes transcribed in specific tissues or at some stage of development, are one type of DNA sequences highly available today for many important crop species. Molecular markers are used for bridging DNA sequence information with particular phenotypes and are useful tools for genotyping germplasm collections and also for tagging genes involved in desirable agronomic traits. In this sense, there is always a strong demand for suitable marker techniques to better utilise existing sequence information. A transcriptome database from banana (Musa spp.), DATAMusa, containing 42,724 ESTs from 11 different cDNA libraries and encompassing approximately 24 Mb of DNA sequence, was used in this study for the design of primers to PCR-amplify two types of EST-derived molecular markers, Variable Nucleotide Tandem Repeat (VNTR) and Target Region Amplification Polymorphism (TRAP). These primers were then validated against a panel of 14 diploid Musa genotypes and produced 32 (VNTR) and 119 (TRAP) alleles. Used separately or together, both types of markers were able to discriminate Musa genotypes from different genome background (A or B genomes). The TRAP alleles identified were derived from only one EST, while the VNTR alleles were derived from 12 unigenes. Based on the results of this study, EST-derived markers can be an important source of polymorphism to be used in genetic diversity and gene discovery studies in banan
Monitoring fish passes using infrared beaming: a case study in an Iberian river
An application of a new automated fish counting device – the
Riverwatcher System (RW) – was used to monitor upstream
fish movements in a pool-and-weir fish pass in the River
Zeˆ zere, Portugal, for 141 days from June 2002 to May 2003.
Fish populations were also collected downstream using multimesh
gillnets (5 different mesh sizes ranging from 30 mm to
85 mm knot to knot; ratio between mesh sizes of about 1.30)
and electrofishing for comparison with fish records produced
by the RW. More than 3000 individual Iberian nase Chondrostoma
polylepis ascended the fish pass and moved through the
RW during the study period. However, only 18% of the
records produced by the RW contained silhouettes similar to
fish; no individual smaller than 15 cm TL was recorded by the
counter. Most seasonal movements (73.9%) occurred in spring
and were associated with reproduction. Displacements seemed
to occur independently of time of day. Water temperature
(range: 12–22 C) was the only significant environmental
variable (P < 0.01) influencing upstream movements of this
species. Further development of hardware and software will be
necessary to improve performance of the counter, particularly
in Mediterranean rivers, where more turbid waters and a
greater proportion of small-size species are presen
Headspace solid-phase Microextraction of Volatile and furanic Compounds in Coated Fish Sticks: Effect of the Extraction Temperature
This work evaluated the effect of temperature onheadspace solid-phase microextraction of volatile and furaniccompounds in coated fish sticks. The major goal was the analysis ofthe samples as consumed, to reproduce volatile compounds peoplefeel when consuming those products. Extraction at 37 ºC (the humanbody temperature) throughout the HS-SPME analysis of volatile andfuranic compounds in coated fish was compared with higherextraction temperatures, which are frequently used for this kind ofdeterminations. The profile of volatile compounds found in deepfried(F) and non-fried (NF) coated fish at 37 and 50 ºC was differentfrom that obtained at 80 ºC. Concerning furan and its derivatives, anextra formation of these compounds was observed at higherextraction temperatures. The analysis of volatile and furaniccompounds in fish coated sticks simulating the cooking and eatingconditions can be reliably carried out setting the headspaceabsorption temperature at 37 ºC
Variable number of tandem repeat markers in the genome sequence of Mycosphaerella fijiensis, the causal agent of black leaf streak disease of banana (Musa spp)
ABSTRACT. We searched the genome of Mycosphaerella fijiensis for molecular markers that would allow population genetics analysis of this plant pathogen. M. fijiensis, the causal agent of banana leaf streak disease, also known as black Sigatoka, is the most devastating pathogen attacking bananas (Musa spp). Recently, the entire genome sequence of M. fijiensis became available. We screened this database for VNTR markers. Forty-two primer pairs were selected for validation, based on repeat type and length and the number of repeat units. Five VNTR markers showing multiple alleles were validated with a reference set of isolates from different parts of the world and a population from a banana plantation in Costa Rica. Polymorphism information content values varied from 0.6414 to 0.7544 for the reference set and from 0.0400 and 0.7373 for the population set. Eighty percent of the polymorphism information content values were above 0.60, indicating that the markers are highly informative. These markers allowed robust scoring of agarose gels and proved to be useful for variability and population genetics studies. In conclusion, the strategy we developed to identify and validate VNTR markers is an efficient means to incorporate markers that can be used for fungicide resistance management and to develop breeding strategies to control banana black leaf streak disease. This is the first report of VNTR-minisatellites from the M. fijiensis genome sequence. Key words: Molecular markers; VNTRs; Genetic diversity; Population genetics; Black Sigatok
Some thoughts on neural network modelling of micro-abrasion-corrosion processes
There is increasing interest in the interactions of microabrasion, involving small particles of less than 10 μm in size, with corrosion. This is because such interactions occur in many environments ranging from the offshore to health care sectors. In particular, micro-abrasion-corrosion can occur in oral processing, where the abrasive components of food interacting with the acidic environment, can lead to degradation of the surface dentine of teeth. Artificial neural networks (ANNs) are computing mechanisms based on the biological brain. They are very effective in various areas such as modelling, classification and pattern recognition. They have been successfully applied in almost all areas of engineering and many practical industrial applications. Hence, in this paper an attempt has been made to model the data obtained in microabrasion-corrosion experiments on polymer/steel couple and a ceramic/lasercarb coating couple using ANN. A multilayer perceptron (MLP) neural network is applied and the results obtained from modelling the tribocorrosion processes will be compared with those obtained from a relatively new class of neural networks namely resource allocation network
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