A.R. Linde

Micronuclei and fluctuating asymmetry in brown trout (Salmo trutta): complementary methods to biomonitor freshwater ecosystems

In this work we measured both micronuclei number in kidney erythrocytes and fluctuating asymmetry in wild brown trout (Salmo trutta), caught in different fluvial ecosystems of Asturias (northern Spain) characterized by different levels of anthropic influence. Brown trout samples from rivers with high anthropic influence possessed significantly higher averages of both micronuclei and fluctuating asymmetry than brown trout samples from less anthropic-influenced rivers. These findings demonstrated the sensitivity of the micronucleus test in kidney erythrocytes to biomonitor freshwater ecosystems. The positive association found between micronuclei average and fluctuating asymmetry at the populational level suggests that fluctuating asymmetry tests could be potential indicators of environmental threat. Variation of fish asymmetry with ageing indicates that fluctuating asymmetry surveys of wild populations should be carried out in trouts of the same age class.

Learning gains in lab practices: teach science doing science

Introducing research in undergraduate biology studies may contribute to creating research vocations and generate the idea that science may influence all aspects of common life. However, laboratory practices are too often disconnected from current investigations and rarely address real-life questions that are really interesting for students. Teachers may help to solve that problem by designing educational lab practices connected with real problems in order to stimulate learning gains and passion for science. We present here a lab practice on cellular biology based on the analysis of micronuclei in buccal cells as a measure of DNA damage. Methodologically easy and cheap, it may be an excellent opportunity to practice scientific methodology and to initiate students in the process of empirical research while they integrate fundamental knowledge.

Evolution of chromosome polymorphic patterns in salmonids: Within-generation variation with ageing

Abstract Robertsonian polymorphism has been analysed in samples of successive ages of Atlantic salmon ( Salmo salar L.) and brown trout ( Salmo trutta L.). Polymorphism changed significantly with ageing, the standard 2n class increasing for each species (2n = 58 for Atlantic salmon and 2n = 80 for brown trout). No significant within-population changes were found among same-aged samples from different generations. The results support the notion that selection favours a standard karyotype. On the other hand, permanence of polymorphic patterns within age groups in successive generations also was demonstrated.

Genetic detection of Pseudomonas spp. in commercial Amazonian fish.

Brazilian freshwater fish caught from large drainages like the River Amazon represent a million ton market in expansion, which is of enormous importance for export to other continents as exotic seafood. A guarantee of bacteriological safety is required for international exports that comprise a set of different bacteria but not any Pseudomonas. However, diarrhoea, infections and even septicaemia caused by some Pseudomonas species have been reported, especially in immune-depressed patients. In this work we have employed PCR-based methodology for identifying Pseudomonas species in commercial fish caught from two different areas within the Amazon basin. Most fish caught from the downstream tributary River Tapajòs were contaminated by five different Pseudomonas species. All fish samples obtained from the River Negro tributary (Manaus markets) contained Pseudomonas, but a less diverse community with only two species. The most dangerous Pseudomonas species for human health, P. aeruginosa, was not found and consumption of these fish (from their Pseudomonas content) can be considered safe for healthy consumers. As a precautionary approach we suggest considering Pseudomonas in routine bacteriological surveys of imported seafood.

Effect of Parental Numbers on Chromosome Patterns Found in Artificially Produced Atlantic Salmon Stocks

Abstract The number of wild Atlantic salmon Salmo salar that return to Spanish rivers has steadily decreased because of environmental degradation and overfishing. To alleviate this decline, juvenile salmon obtained from adults returning to Asturian rivers are used in a supplementation program. Gametes from no more than 35 adults are used to create groups of juveniles that are released back into the wild. We examined the effect of parental numbers on the chromosomal patterns found in juveniles produced by this protocol. When less than 20 parental fish were used, the chromosomal patterns found in their offspring were significantly different (P < 0.001) from those found in naturally produced fish. Consequently, in supplementation endeavors, at least 20 parents should be used to create groups of juveniles.