An old taxonomic dilemma: the identity of the western south Atlantic lebranche mullet (Teleostei: Perciformes: Mugilidae)

The identification of the lebranche mullet in the western south Atlantic has long been problematical. In most recent works either Mugil liza Valenciennes and M. platanus Gunther, 1880 or M. liza and M. cephalus Linnaeus, 1758 were recognized from the region and more rarely the occurrence of only one species has been proposed but without sufficient morphological, biochemical or molecular data to allow the designation of the taxonomically appropriate name. Analysis of meristic and morphometric data taken from samples collected from Venezuela to Argentina, clearly indicates that there is only one species of lebranche mullet in the Caribbean Sea region and the Atlantic coast of South America and that Mugil liza is the appropriate name. The comparison of the combined data from all the samples of M. liza with the data taken from one sample of M. cephalus that originated in the Mediterranean, the possible locality from which type specimens were collected (Eschmeyer and Fricke, 2009), revealed significant differences indicating that they are different species. It is also suggested that individuals from the western north Atlantic identified as M. cephalus might represent a population of M. liza in this region.

Seminal analysis, cryogenic preservation, and fertility in matrinxã fish, Brycon cephalus (Günther, 1869)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito do resfriamento sobre a textura post-mortem da carne do peixe matrinxã Brycon cephalus

Os mecanismos que causam o amolecimento e a perda na textura post-mortem da carne de matrinxã foram determinados por meio das mudanças na microestrutura do músculo, imediatamente após a morte e depois de 12 horas de estocagem a -3°C. As observações na microestrutura, realizadas com microscópio eletrônico de transmissão, foram semelhantes aos resultados obtidos na força de ruptura do músculo medidos com o texturômetro. Os valores da força da ruptura foram menores para a carne após o resfriamento. Observou-se que as fibras do colágeno do tecido conectivo pericelular se desintegraram e que as do colágeno do tecido conectivo do miocommata conservaram sua arquitetura e integridade. Houve pouca degradação da linha Z. Isso sugere que o amolecimento post-mortem da carne de mantrinxã, durante a estocagem a -3°C, é causado pela degradação do tecido conectivo pericelular.

Influência do formato do aquário na sobrevivência e no desenvolvimento de larvas de matrinxã Brycon cephalus (Osteichthyes, Characidae)

Neste experimento, utilizaram-se cinco aquários cilíndricos com relevo no fundo (em forma de anel) e cinco retangulares com fundo liso para estudo da influência do formato do aquário na sobrevivência e no desenvolvimento de larvas de matrinxã Brycon cephalus. Observou-se melhor eficiência dos aquários retangulares, confirmada pela maior sobrevivência e biomassa. Os valores de temperatura, pH, condutividade e oxigênio dissolvido foram similares entre os tipos de aquários, sugerindo que esses parâmetros não influenciaram os resultados. O relevo no fundo dos aquários cilíndricos afetou negativamente o cultivo de larvas de matrinxã, pela criação de zonas com pequena capacidade da água em suspender partículas, o que resultou em acúmulo de dejetos, predadores, competidores e alimento. Aquários retangulares com fundo liso são mais adequados ao cultivo de larvas de matrinxã, por promover melhor circulação da água.

Comparative cytogenetic and allozyme analysis of Mugil rubrioculus and M. curema (Teleostei : Mugilidae) from Venezuela

A comparative cytogenetic and allozyme analysis of sympatric specimens of Mugil rubrioculus and M. curema from Venezuela is reported. Specimens of M. rubrioculus exhibit a 2n=48 karyotype with exclusively acrocentric (NF=48) chromosomes, one pair of NORs interstitially located on chromosome pair number 8 and constitutive heterochromatin distributed in pericentromeric position of all chromosomes. Specimens of M. curema show cytogenetic features significantly different in comparison to M. rubrioculus in terms of chromosome number and morphology (2n=24 biarmed chromosomes, NF=48) and NORs location (telomeric region of the largest metacentric pair). Starch gel electrophoresis analysis at 20 presumptive loci reveals a reduced genetic difterentiation between the two species. In fact, though a total of ten private alleles are identified; all loci share alleles between the two species and the obtained Nei's genetic distance (D= 0.060) is lower than the values obtained between other congeneric mullet species. Thus, the cytogenetic and allozyme data sets indicate quite different degrees of genetic divergence between M. rubrioculus and M. curema. This could either reflect an underestimate of molecular divergence owing to cryptic variation or different rates of molecular/chromosomal evolution. Whatever the explanation, this study confirms the power of karyological data in discriminating species of Mugilidae.

Crystallization, preliminary X-ray analysis and molecular-replacement solution of the carboxy form of haemoglobin I from the fish Brycon cephalus

Haemoglobin, the 'honorary enzyme' [Brunori (1999), Trends Biochem. Sci. 24, 158-161], constitutes a prime prototype for allosteric models. Here, the crystallization and preliminary X-ray analysis of haemoglobin I from the South American fish Brycon cephalus are reported. X-ray diffraction data have been collected to 2.5 Angstrom resolution using synchrotron radiation (LNLS). Crystals were determined to belong to the space group P6(1)22 and preliminary structural analysis revealed the presence of one dimer (alpha beta) in the asymmetric unit. The structure was determined using standard molecular-replacement techniques.

Physiological responses associated with capture and crowding stress in matrinxã Brycon cephalus (Gunther, 1869)

The dynamics of plasma cortisol, blood glucose, plasma chloride and liver glycogen were investigated in matrinxã (Brycon cephalus) submitted to capture and various periods of crowding. A total of 400 fish (700 ± 22 g weight) were distributed in four ponds divided into four 50-m2 squares (25 fish/square, 350 gL-1), where they were acclimated for 30 days. On the sampling day, after 24 h without food, all fish from three squares were transferred to the fourth square. Six fish were sampled before the procedure (control group, zero time) and 1, 3, 6 and 24 h after the capture and crowding. Each sampling was performed in a different pond to prevent additional stress. Fish were anaesthetized and blood and liver collected for biochemical analysis. Water temperature, pH, dissolved oxygen, alkalinity, ammonia and nitrite levels were within acceptable levels for matrinxã rearing. Slight but not significant increases were verified in plasma cortisol and blood glucose levels, as were decreases in plasma chloride and liver glycogen levels. The results suggest that matrinxã is highly tolerant to the procedures of capture and short-term crowding.

Schooling behavior of Mugil curema (Perciformes: Mugilidae) in an estuary in southeastern Brazil

Schools of mullets, Mugilidae, are abundant in estuaries and shallow marine waters. We report on the schooling behavior of juvenile white mullet, Mugil curema, in the estuary of the Canto da Paciência stream, in Ubatuba, southeastern Brazil. Schools of small fish (15 to 35 mm TL) were composed of a larger number of individuals (up to a hundred individuals), and were found feeding mainly in shallow nearshore waters, whereas schools of larger fish (40 to 100 mm TL) were observed only in deeper waters. Three patterns of swimming were observed for the schools: stationary feeding, slow movement while searching for food, and rapid displacement. The variations observed in school structure and behavior seem to be related to the balance between predation risk and increasing food intake. Copyright © 2007 Sociedade Brasileira de Ictiologia.

Indução a espermiação e criopreservação espermática de Brycon cephalus (Gunther, 1869) (teleostei: characidae)

Pós-graduação em Ciência e Tecnologia Animal - FEIS

Estocagem tecidual e utilização de lipídeos em Matrinxã, Brycon cephalus (Günther, 1869)

Lipids have important biological functions, suchas membrane constituents, hormone precursors, and are efficient energy reserves, due to thers high caloric content. In fish, but not in mammals, lipid storage patterns are quite diverse. The aim of this study was to determine lipid distribution in somatic and reproductive tissues of matrinxã, Brycon cephalus, both male and female, highlighting somatic indices related to lipid dynamics. From Oct 98 to Jan 99, a total of 174 fish (8-12 each month) were sampled. After fish anesthesia, heparinized blood was collected for plasma triacylglycerol determination. Fish were individually weighed and measured, and liver, gonads and visceral fat were collected and weighed for HSI (hepatosomatic index), GSI (gonad somatic index) and MFI (mesenteric fat index) calculation. The highest values of total lipids were found in red muscle (about 18%), liver and gonads (about 16.5%). The white muscle had a lower concentration (2.5%). Analyses of variance of HSI and MFI showed fluctuations along the experimental period with lowest concentrations in the periods of highest temperatures. Matrinxã store lipids in several body tissues, including mesenteric fat, liver, muscles and gonads.

Taxonomic review of the species of Mugil (Teleostei: Perciformes: Mugilidae) from the Atlantic South Caribbean and South America, with integration of morphological, cytogenetic and molecular data

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Molecular identification of mullet species of the Atlantic South Caribbean and South America and the phylogeographic analysis of mugil liza

Fundacao de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Hormonal induction of Brycon cephalus (Characiformes, Characidae) to spermiation using D-ala6, pro9net-mGnRH + metoclopramide

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of hot and cold smoking processes on organoleptic properties, yield and composition of matrinxa fillet

Foi avaliado o efeito do processo de defumação a quente (45-90ºC/5 horas) e a frio (27-45ºC/10 horas) nas propriedades organolépticas, no rendimento e na composição dos filés de matrinxã (Brycon cephalus). Não houve diferença significativa no rendimento de filés defumados e não-defumados. As perdas no processo de defumação foram significativamente maiores para defumação a quente (19,37%) em comparação à defumação a frio (17,08%). O processo de defumação reduziu a umidade (in natura = 72,91%; defumado a quente = 58,51%; e defumado a frio = 59,68%) e aumentou os teores de proteína bruta, lipídios e cinzas. Houve diferença significativa somente nos teores de proteína no defumado a quente (28,07%) e defumado a frio (27,14%). O processo a frio resultou em melhor aparência e cor de filé, enquanto o processo a quente melhorou o sabor, o teor de sal e a aparência geral. O aroma e a textura não diferiram significativamente entre os processos. O processo de defumação a quente melhora as propriedades organolépticas e os níveis de proteína do filé de matrinxã.

Fauna parasitária de peixes oriundos de pesque-pague do município de Franca, São Paulo, Brasil. I. Protozoários

The present work studied protozoan parasites of cultivated fishes (N = 433) from two feefishing farm situated in Franca, São Paulo, Brazil, during a period of April 1997 through March 1999. Specimens of piauçú Leporinus macrocephalus Garavello & Britski, 1988 (Anostomidae), pacu Piaractus mesopotamicus Holmberg, 1887 (Characidae) carp Cyprinus carpio Linnaeus, 1758 (Cyprinidae), Tillapia rendalli Boulenger, 1896 (Cichlidae), nile-tilapia Oreochromis niloticus Linnaeus, 1758 (Cichlidae), matrinxã Brycon cephalus Günther, 1869 (Characidae) and tambacu hybrid (male of P. mesopotamicus x female of Colossoma macropomum Cuvier, 1818) were collected. The fishes were parasitized with protozoans Ichthyophthirius multifiliis Fouquet, 1876 (Protozoa), Trichodina sp. and Piscinoodinium pillulare (Schaperclaus, 1954), Lom, 1981 (Protozoa). In the cold season (autumn and/or winter) all species of fish were infected with I. multifiliis. Higher susceptibility to Trichodina sp. was observed in L. macrocephalus, C. carpio and P. mesopotamicus compared to tambacu, B. cephalus, T. rendalli and 0. niloticus. It was not observed significant difference (P > 0.05) in the seasonal variation of Trichodina sp. and P. pillulare infection of all species. A great number of P. pillulare without significant difference (P > 0.05) was reported to L. macrocephalus, P. mesopotamicus and tambacu.