No abstract

To investigate the impact of different dietary lipid sources on fillet composition and lipid transport, we conducted a feeding trial and evaluated the proximate composition of muscle tissue, fatty acid profiles, total cholesterol (in muscle and plasma), triglycerides, and lipoprotein concentrations in Nile tilapia, Oreochromis niloticus. Five semi‐purified diets, containing different oils (soybean – SO, corn – CO, linseed – LO, fish – FO, and olive – OO), were supplied to tilapia for 160 d. Fish fed with LO and FO diets had a lower percentage of total lipids in muscle compared with the others (P < 0.05). The highest percentage of protein was found in fish fed with FO diet (P < 0.05). The muscle fatty acid profile was influenced differently by diets (P < 0.05). The group supplemented with SO and CO had a higher concentration of 18:2n‐6, whereas the fish fed with LO diet had a higher level of 18:3n‐3 and those that received the FO diet had more 22:6n‐3 in comparison with those supplemented with vegetable oils. Plasma lipid transport was also affected by the diets: the fish fed with FO diet had higher total cholesterol and high‐density lipoprotein and lower very‐low‐density lipoprotein concentrations (P < 0.05).

We analyzed one Bunocephalus coracoideus population from the Negro River basin using cytogenetic techniques. The results showed a diploid number of 42 chromosomes in both sexes, with the karyotypic formula 4m + 14sm + 24a and fundamental number (FN) = 60 for females and the formula 5m + 14sm + 23a and FN = 61 for males, constituting an XXXX/XYXY multiple sex chromosome system. The constitutive heterochromatin is distributed in the pericentromeric regions of most of the chromosomes, except for the sex chromosomes, of which the X, X, and Y chromosomes were euchromatic and the Y chromosome was partially heterochromatic. 18S rDNA mapping confirmed the presence of nucleolar organizer regions on the short arms of the fifth chromosomal pair for both sexes. The 5S rDNA is present in the terminal regions of the short arms on the 2nd, 10th, and 12th pairs and on the X chromosome of both sexes; however, we observed variations in the presence of these ribosomal cistrons on the Y chromosome, on which the cistrons are pericentromeric, and on the Y chromosome, on which these cistrons are present in the terminal portions of the short and long arms. Telomeric sequences are located in the terminal regions of all of the chromosomes, particularly conspicuous blocks on the 10th and 12th pairs and internal telomeric sequences in the centromeric regions of the 1st, 6th, and 9th pairs for both sexes. This work describes an new sex chromosomes system for the Siluriformes and increases our genetic knowledge of the Aspredinidae family.

The effect of different dietary oil sources on the innate immunity and resistance of Nile tilapia, Oreochromis niloticus, to Streptococcus agalactiae infection were evaluated. Fish were fed with diets containing different lipid sources (soybean oil [SO], corn oil, linseed oil [LO], fish oil [FO], and olive oil [OO]). Fish fed SO presented the highest (P < 0.05) hematocrit and serum protein. LO and FO diets increased (P < 0.05) the erythrocyte resistance to osmotic lysis in comparison with other treatments. Fish fed OO showed the highest (P < 0.05) iron-binding capacity and the lowest serum lysozyme and bactericidal activities (P < 0.05). No difference (P > 0.05) was found between diets in alternative complement activity. Fish fed the SO diet had the highest (P < 0.05) survival rate against S. agalactiae challenge. In conclusion, diets with LO oil and FO, rich in -3 fatty acids, and OO, rich in -9 fatty acids, have an immunomodulatory effect in Nile tilapia juveniles. The use of SO in the Nile tilapia diet improved immune function and resistance against S. agalactiae.

Farlowella is one of the most diverse genera of the Loricariinae, restricted to South America rivers. The taxonomic and phylogenetic relationships among its species are contentious and, while genetic studies would contribute to the understanding of their relationships, the only available datum refer to the karyotype description of only one species. In the present study two Amazonian species, Farlowella cf. amazonum and F. schreitmuelleri, were analyzed using conventional and molecular cytogenetic procedures. Both species had diploid chromosome number 58, but different fundamental numbers (NF) 116 and 112, respectively, indicative of chromosomal rearrangements. C-banding is almost poor, especially in F. cf. amazonum, and occurs predominantly in the centromeric and in some telomeric regions, although genome of F. schreitmuelleri possessed a much larger heterochromatin amount then those of F. cf. amazonum. The chromosomes bearing the NOR sites were likely the same for both species, corresponding to the 1st metacentric pair in F. cf. amazonum and to the 28th acrocentric in F. schreitmuelleri. The location of the 5S rDNA was species-specific marker. This study expanded the available cytogenetic data for Farlowella species and pointed the remarkable karyotype diversity among species/populations, indicating a possible species complex within genus.

RESUMONo presente trabalho foi avaliado o efeito de métodos de cocção na composição química, teor de colesterol e totais de ácidos graxos de filés de Tilápias do Nilo. Os tratamentos foram cozimento em água (CA), fritura em óleo de soja (FO), assado em forno elétrico (FE), assado em forno microondas (MO), e um grupo testemunha (filés crus). O delineamento foi inteiramente casualizado, cada tratamento com 7 peixes e a unidade experimental foi um peixe (2 filés -1 para CA, FE, FO e MO, respectivamente) com relação aos crus (33,00 mg/100g). Os filés FO (P<0,05) apresentaram menores totais de ácidos graxos saturados e monoinsaturados e mostraram maior percentual de ácidos graxos poliinsaturados, quando comparados aos demais grupos. O cozimento aumenta a matéria seca, resultado da perda de água dos filés e aumento na concentração dos demais constituintes. O tratamento frito em óleo causa uma incorporação do meio (óleo de fritura) aos filés e aumenta os lipídeos totais, alterando o perfil de ácidos graxos dos filés de peixes fritos.Termos para indexação: Peixe, ácidos graxos, colesterol. ABSTRACTIn this work, the effects of different cooking methods of Nile tilapia fillets on their chemical composition, cholesterol content and total fatty acids, were studied. Cooking methods evaluated were water boiling (WB), frying in soybean oil (SO), broiling in an electric oven (EO), cooking in a microwave oven (MO) and a control group (raw fillets). The experiment was conducted as a completely randomized design, with the fish (two fillets/fish) considered as the experimental unit, and seven experimental units were used per treatment. Dry matter increased (P<0.05) in cooked fillets (23.27 % WB, 25.44 % EO, 31.93 % MO and 33.44 % SO) when compared with raw fillets (20.61 %). Total lipids were higher (P<0.05) in SO fillets (17.36 %), than in all the other treatments (6.94 % WB, 9.80 % EO, 8.66 % MO and 5.92 % raw fillets). All cooking methods increased (P<0.05) cholesterol content of the fillets (46.89 mg/100g WB, 46.46 mg/100g EO, 54.78 mg/100g SO and 57.28 mg 100g -1 MO) when compared with raw fillets (33.00 mg/100 g). Relative to all the other treatments, FO fillets had (P<0.05) lower values for saturated and monounsaturated fatty acids, and a higher percentage of polyunsaturated fatty acids. Overall, water boiling results in an increase in dry matter due to water loss in the cooking process, with higher concentration of the remaining constituents. Cooking by oil frying leads to the incorporation of oil in the fillets, with an increase in total lipids and a change of the fatty acid profile in fried fish.

Bunocephalus is the most species-rich Aspredinidae genus, corresponding to a monophyletic clade with 13 valid species. However, many species have their classification put in question. Here, we analyzed individuals from four Amazonian populations of Bunocephalus coracoideus by cytogenetic and molecular procedures. The geographic distribution, genetic distances and karyotype data indicate that each population represents an Evolutionary Significant Unit (ESU). Cytogenetic markers showed distinct 2n and karyotype formulas, as well as different numbers and locations of the rDNA sites among ESUs. One of such populations (ESU-D) highlighted an extensive polymorphic condition, with several cytotypes probably due to chromosomal rearrangements and meiotic non-disjunctions. This resulted in several aneuploid karyotypes, which was also supported by the mapping of telomeric sequences. Phylograms based on Maximum Likelihood (ML) and Neighbor Joining (NJ) analyses grouped each ESU on particular highly supported clades, with the estimation of evolutionary divergence indicating values being higher than 3.8–12.3% among them. Our study reveals a huge degree of chromosomal and genetic diversity in B. coracoideus and highly points to the existence of four ESUs in allopatric and sympatric speciation processes. In fact, the high divergences found among the ESUs allowed us to delimitate lineages with taxonomic uncertainties in this nominal species.

The genus Colomesus is the sole representative of the family Tetraodontidae in the Amazon region. Here, Colomesus asellus was analyzed using conventional and molecular cytogenetic protocols. Its diploid chromosome number is 2n = 46 with 12 meta-, 10 submeta-, 16 subtelo-, and 8 acrocentric chromosomes and a fundamental number of FN = 84. An XX/XY sex chromosome system was identified. Mapping of 18S rDNA correlated with the nucleolus organizer regions (Ag-NORs) in the short arms of the 2 X chromosomes in females and in the Y chromosome in males. C-banding revealed heterochromatin in the centromeric regions of all chromosomes, except for pair 3. Prominent sex chromosome-specific heterochromatin amplification was observed, covering the short arms of the Y chromosome almost entirely. FISH with telomeric and tropomyosin (tpm1) sequences, respectively, revealed terminal signals in all chromosomes. The analysis of extended DNA fibers confirmed the colocalization and the interspersed pattern of the telomeric and tpm1 sequences. Thus, this study highlights the remarkable evolutionary dynamism presented by the Amazonian puffer fish regarding the differentiation of a heteromorphic XY sex chromosome system and a particular sex-specific amplification of rDNA sites. This is the first record of such an association in the Tetraodontidae family.