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The genetic variability of four Colossoma macropomum broodstocks, three from fish farms in different regions and one from the natural environment in Brazil, was analyzed using microsatellite markers. The wild progeny (n = 30) were caught in the Solimões-Amazonas River, at the varzea lakes; this location is used to mature the fish from larvae to juveniles. The three fish farms were selected according to the age of their lineages and broodstock availability: DNOCS (n = 21) is located in the Ceará State, representing the oldest lineage of cultivated tambaqui in Brazil; Balbina (n = 30) is located in the Amazonas State, representing the youngest stocks of tambaqui farmed in Brazil (approximately 15 years); and UFRPE (n = 30) is located in the Pernambuco State and is considered to be a mixed stock formed from the DNOCS and Balbina lineages. The analysis of 13 microsatellite loci indicated the occurrence of a variability reduction in the farmed populations; the UFRPE stock was the population with the highest diversity level. Low values of molecular coancestry were found in these populations. Additionally, significant differences in the RST values among the populations were detected, as was the occurrence of genetic structure. The genetic loss found in these populations may have been influenced by the founder effect. Because no breeding programs were during the entire production period and no pedigree records were kept for these broodstocks, we suggest that a wild population might be used as an important genetic resource to increase the genetic diversity of renewal stock lineages.

This article documents the addition of 238 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Alytes dickhilleni, Arapaima gigas, Austropotamobius italicus, Blumeria graminis f. sp. tritici, Cobitis lutheri, Dendroctonus ponderosae, Glossina morsitans morsitans, Haplophilus subterraneus, Kirengeshoma palmata, Lysimachia japonica, Macrolophus pygmaeus, Microtus cabrerae, Mytilus galloprovincialis, Pallisentis (Neosentis) celatus, Pulmonaria officinalis, Salminus franciscanus, Thais chocolata and Zootoca vivipara. These loci were cross-tested on the following species: Acanthina monodon, Alytes cisternasii, Alytes maurus, Alytes muletensis, Alytes obstetricans almogavarii, Alytes obstetricans boscai, Alytes obstetricans obstetricans, Alytes obstetricans pertinax, Cambarellus montezumae, Cambarellus zempoalensis, Chorus giganteus, Cobitis tetralineata, Glossina fuscipes fuscipes, Glossina pallidipes, Lysimachia japonica var. japonica, Lysimachia japonica var. minutissima, Orconectes virilis, Pacifastacus leniusculus, Procambarus clarkii, Salminus brasiliensis and Salminus hilarii.

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Colossoma macropomum is an endemic species from Amazon basin. It is widely commercialized as food, becoming one of the main items in Amazonian fisheries. Despite its economic importance, genetic information of small captivity populations is not currently available. The present contribution describes 14 new microsatellite loci used to analyze 30 individuals of C. macropomum. The number of alleles for each locus ranged from 4 to 24. The observed (Ho) and expected (H E) heterozygosity values ranged from 0.318 to 1.000 and 0.729 to 0.949, respectively. Out of 14 polymorphic loci, nine did not deviate from Hardy-Weinberg Equilibrium after Bonferroni correction. These new microsatellite loci will contribute towards the genetic of small artificial populations, as well as pedigree control of fish farms of C. macropomum.

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Lepidosiren paradoxa (pirambóia) is the single representative of Dipnoan (lungfish) in South America. This species is considered a living fossil, in spite of some reports describing this fish as having a very specialized life style. It aestivates during the dry season, and has developed metabolic adaptations to cope with both flooding and drought. The literature describing its tissue ultra-structure shows high glycogen stored in the muscle, suggesting a strong dependence on anaerobic glycolysis. The present paper reports tissue enzyme levels of LDH, MDH, and CS, and isozymic tissue distribution of LDH, MDH, ADH, PGI, SOD, and PGM of 7 aestivating specimens from Lago do Canteiro in the Amazonas River. Animals were caught while burrowed in mud during the aestivation period. Our findings reveal high anaerobic capacity of both skeletal and heart muscles, even during the aestivation period, when enzymes showed suppressed levels compared to those of non-aestivating animals (data from the literature). Isozymic patterns suggest loss of duplicate condition in most analyzed loci, a characteristic that occurs mainly in higher vertebrate categories. These data indicate that, compared to the fish group, lungfish may be considered advanced, despite retaining primitive morphological characters.