Miriam Soria Barreto; Joel Paulo Maya
El género Chirostoma es un grupo de peces endémicos de la Mesa Central de México, cuya diversificación se explica tanto por procesos de especiación alopátrica en ambientes lóticos, como por una diversificación intralacustre debida a especiación simpátrica. Tratando de corroborar la segunda hipótesis en especies de Chirostoma en Pátzcuaro, se evaluaron diferencias morfométricas de 11 piezas osteológicas de la región mandibular de C. attenuatum, C. grandocule, C. estor y C. patzcuaro. Con objet...
García-de-León, Francisco J; Juan P. Ramírez-Herrejón; García-Ortega, Rafael; Dean A. Hendrickson
RESUMEN: Los patrones de forrajeo de cuatro especies simpátricas del género Chirostoma (Chirostoma estor, Chirostoma grandocule, Chirostoma attenuatum y Chirostoma patzcuaro) fueron evaluadas en el Lago de Pátzcuaro, para entender la repartición de recursos alimenticios y su coexistencia simpátrica. La abundancia de invertebrados presa fue estimada en distintos hábitat alimenticios y se midieron parámetros físicos y químicos del hábitat en dos sitios de estudio. Los peces fueron recolectados ...
Full Text Available We explore the trophic role that a diverse sympatric group of fishes in the genus Chirostoma play in a large, shallow lake in central Mexico, Lake Chapala. We use δ13C and δ15N stable isotope - based food web analyses to explore how they relate to other components of the Lake Chapala ecosystem. We find five Chirostoma species in top trophic levels of the Chapala food web compared to other fishes, relying on a combination of zooplankton, fish and benthic resources as energy sources. Food web metric analyses showed generally overlapping trophic niches for members of Chirostoma, especially in terms of δ13C. However, C. jordani had lower mean δ15N isotopic values than C. promelas. As a group, "pescados blancos" (C. sphyraena and C. promelas also had higher δ15N signatures than "charales" (C. consocium, C. jordani and C. labarcae reflecting greater piscivory, but these differences were not strong for all food web metrics used. Trophic overlap among species of Chirostoma in Lake Chapala raises questions about the forces that might have led to a morphologically diverse but functionally similar and monophyletic group of species.
Martínez-Chávez, C C; Tello-Ballinas, A; Fonseca-Madrigal, J; Ross, L G; Martínez-Palacios, C A
The effect of photoperiod on growth and survival in early life was determined in the tropical batch spawning atherinopsid, pike silverside Chirostoma estor. The results demonstrate high sensitivity of newly hatched C. estor to photoperiod treatments up to 90 days post hatch shown by improved growth in mass (43%) under continuous illumination. This is accompanied by increased fat deposition, which suggests a critical interaction between different photoperiod-mediated mechanisms. A thorough understanding of these mechanisms can help to optimize the development of aquaculture of C. estor and similar species.
Choudhury, A; Pérez-Ponce de León, G
Spinitectus osorioi (Nematoda: Cystidicolidae) is described from the freshwater atherinids Chirostoma estor and Chirostoma attenuatum from Lake Pátzcuaro in the Mesa Central, Michoacán State, México. This nematode is characterized by a conspicuous protuberance on the ventral surface of the distal end of the long spicule that distinguishes it from its congeners in North America and in the neotropics. In addition, the species can be readily distinguished from 4 of the 5 nominal species of North American freshwater Spinitectus by the absence of either a terminal barb or heel on the short spicule and from Spinitectus mexicanus by the spination. Previous records of Spinitectus carolini from Chirostoma spp. in México (Lakes Pátzcuaro and Zirahuén) refer to S. osorioi, and the species appears to be specific to Chirostoma spp. The geological history of the Mesa Central drainages and the historical biogeography of freshwater atherinids in this region suggest that the origin of S. osorioi may be associated with either the marine history of their hosts or with host-switching from more distantly related freshwater hosts after colonization of freshwater environments by atherinids.
Pohls, P; González-Dávalos, L; Mora, O; Shimada, A; Varela-Echavarria, A; Toledo-Cuevas, E M; Martínez-Palacios, C A
The expression and digestive activity of pike silverside Chirostoma estor endogenous chitinases were analysed in samples from four life stages: whole eggs; larvae; juvenile intestine and hepatopancreas and adult intestine and hepatopancreas. A chitinase cDNA was cloned and partially sequenced (GenBank accession number: FJ785521). It was highly homologous to non-acidic chitinase sequences from other fish species, suggesting that it is a chitotriosidase. Quantitative PCR showed that this chitinase was expressed throughout the life span of C. estor, with maximum expression in the hepatopancreas of juveniles. Chitotriosidase and chitobiosidase activities were found at all life stages, along with a very high level of N-acetyl glucosaminidase (NAGase). The chitotriosidase activity could be encoded by the cloned complementary (c)DNA, although additional chitinase genes may be present. The chitotriosidase activity appeared to be transcriptionally regulated only at the juvenile stage. The expression and activity of chitinases tended to increase from the early to juvenile stages, suggesting that these variables are stimulated by chitin-rich live food. Nevertheless, the feeding of juvenile and adult fish with both live food and a balanced commercial diet seemed to provoke significant reductions in pancreatic NAGase secretion and/or synthesis in the gut. Moreover, all chitinase activities were lower in adults, probably reflecting a higher intake and use of the balanced diet. The observation of chitotriosidase and chitobiosidase activities together with a very high NAGase activity suggest the presence of a complete and compensatory chitinolytic chitinase system that enables this stomachless short-gut fish species to use chitin as an energy substrate. These novel findings suggest that dietary inclusions of chitin-rich ingredients or by-products might reduce the farming costs of C. estor without impairing performance.
Ana Carmen Delgadillo-Calvillo; Carlos Antonio Martínez-Palacios; José Manuel Berruecos-Villalobos; Raúl Ulloa-Arvizu; Reyes López-Ordaz; Carlos Gustavo Vásquez-Peláez
El objetivo del presente estudio fue estimar parámetros de las curvas de crecimiento del peso y la longitud en el pez blanco Chirostoma estor (EE), el pez blanco pico negro Chirostoma promelas (PP) y de sus híbridos recíprocos (EP y PE) hasta los 300 días de edad a partir de un cruzamiento dialélico completo bajo condiciones de cultivo en Morelia, Michoacán, México. La longitud se midió mensualmente desde la eclosión, mientras que el peso se midió mensualmente a partir de los 120 días. Los nú...
Fonseca-Madrigal, Jorge; Navarro, Juan C.; Hontoria, Francisco; Tocher, Douglas R.; Martínez-Palacios, Carlos A.; Monroig, Óscar
Currently existing data show that the capability for long-chain PUFA (LC-PUFA) biosynthesis in teleost fish is more diverse than in other vertebrates. Such diversity has been primarily linked to the subfunctionalization that teleostei fatty acyl desaturase (Fads)2 desaturases have undergone during evolution. We previously showed that Chirostoma estor, one of the few representatives of freshwater atherinopsids, had the ability for LC-PUFA biosynthesis from C18 PUFA precursors, in agreement wit...
Fonseca-Madrigal, J; Pineda-Delgado, D; Martínez-Palacios, C; Rodríguez, C; Tocher, D R
The genus Chirostoma (silversides) belongs to the family Atherinopsidae, which contains around 150 species, most of which are marine. However, Mexican silverside (Chirostoma estor) is one of the few representatives of freshwater atherinopsids and is only found in some lakes of the Mexican Central Plateau. However, studies have shown that C. estor has improved survival, growth, and development when cultured in water conditions with increased salinity. In addition, C. estor displays an unusual fatty acid composition for a freshwater fish with high docosahexaenoic acid (DHA)/ eicosapentaenoic acid (EPA) ratios. Freshwater and marine fish species display very different essential fatty acid metabolism and requirements, and so the present study investigated long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis to determine the capacity of C. estor for endogenous production of EPA and DHA, and the effect that salinity has on these pathways. Briefly, C. estor were maintained at three salinities (0, 5, and 15 ppt), and the metabolism of ¹⁴C-labeled 18:3n-3 was determined in isolated hepatocyte and enterocyte cells. The results showed that C. estor has the capacity for endogenous biosynthesis of LC-PUFA from 18-carbon fatty acid precursors, but that the pathway was essentially only active in saline conditions with virtually no activity in cells isolated from fish grown in freshwater. The activity of the LC-PUFA biosynthesis pathway was also higher in cells isolated from fish at 15 ppt compared with fish at 5 ppt. The activity was around fivefold higher in hepatocytes compared with enterocytes; although the majority of 18:3n-3 was converted to 18:4n-3 and 20:4n-3 in hepatocytes, the proportions of 18:3n-3 converted to EPA and DHA were higher in enterocytes. The data were consistent with the hypothesis that conversion of EPA to DHA could contribute, at least in part, to the generally high DHA/EPA ratios observed in the tissue lipids of C. estor.
María Eugenia Vega; Fernando Díaz; Sonia Espina
En este trabajo se determinó el flujo energético de juveniles de Chirostoma estor estor (Jordan, 1979) de dos diferentes clases de peso (P 0.05). En la Clase A se agruparon los peces de 1.50 ± 0.22 g y en la Clase B los de 3.30 ± 0.29 g. Los peces mantenidos a 20 °C, se alimentaron al 4% del peso corporal, con una dieta balanceada comercial (28% de proteína). Se midieron las respuestas fisiológicas y se integraron en la ecuación del balance energético con el fin de estimar la energía potenci...
Guilgur, Leonardo G; Ortí, Guillermo; Strobl-Mazzulla, Pablo H; Fernandino, Juan I; Miranda, Leandro A; Somoza, Gustavo M
Most vertebrates express two gonadotropin releasing hormone (GnRH) variants in brain tissue but there is an increasing number of fish species for which a third GnRH form has been detected. We characterized the precursors (cDNAs) of all three forms expressed in the brain of the pejerrey (silverside) fish, Odontesthes bonariensis (Atheriniformes): type I (GnRH-I; 440 bp), type II (GnRH-II; 529 bp), and type III (GnRH-III; 515 bp). The expression of these GnRHs precursors was also observed in peripheral tissues related to reproduction (gonads), visual and chemical senses (eye and olfactory epithelium), and osmoregulation (gill), suggesting that in teleost fish and possibly other vertebrates GnRH mediates directly or indirectly many other functions besides reproduction. We also present a comprehensive phylogenetic analysis including representatives of all chordate GnRH precursors characterized to date that supports the idea of two main paralogous GnRH lineages with different function. A "forebrain lineage" separates evolutionarily from the "midbrain lineage" as a result of an ancient duplication (ca. 600 million years ago). A third, fish-only clade of GnRH genes seems to have originated before the divergence of fish and tetrapods but retained only in fish. Phylogenetic analyses of GnRH precursors (DNA and protein sequences) under different optimality criteria converge on this result. Although alternative scenarios could not be statistically rejected in this study due to the relatively short size of the analyzed molecules, this hypothesis also receives support from chromosomal studies of synteny around the GnRH genes in vertebrates.
Vega-López, Armando; Carrillo-Morales, Carla I; Olivares-Rubio, Hugo F; Lilia Domínguez-López, M; García-Latorre, Ethel A
Halomethanes (HMs) are produced autochthonously in water bodies through the action of ultraviolet light in the presence of HM precursors, such as dissolved organic carbon and halogens. In mammals, toxic effects induced by HMs are diverse and include oxidative stress, which is also induced by divalent and polyvalent metals; however, in fish little information is available on HM metabolism and its possible consequences at the population level. In the present study, high CYP 2E1 and GST theta-like activities were found in viscera of the Toluca silverside Chirostoma riojai from Lake Zumpango (LZ; central Mexico). Formaldehyde, one of the HM metabolites, was correlated with CYP 2E1 activity and also induced lipid peroxidation in viscera. Hepatic CYP 2E1 activity was correlated with GST theta-like activity, suggesting the coupling of both pathways of HM bioactivation and its consequent oxidative damage. Sediment metals, among others, were also responsible for oxidative stress, particularly iron, lead, arsenic and manganese. However, under normal environmental conditions, the antioxidant enzymes of this species sustain catalysis adapted to oxidative stress. Findings suggest that this fish species apparently has mechanisms of adaptation and recovery that enable it to confront toxic agents of natural origin, such as metals and other substances formed through natural processes, e.g., HMs. This has allowed C. riojai to colonize LZ despite the high sensitivity of this species to xenobiotics of anthropogenic origin.
Fonseca-Madrigal, Jorge; Navarro, Juan C; Hontoria, Francisco; Tocher, Douglas R; Martínez-Palacios, Carlos A; Monroig, Óscar
Currently existing data show that the capability for long-chain PUFA (LC-PUFA) biosynthesis in teleost fish is more diverse than in other vertebrates. Such diversity has been primarily linked to the subfunctionalization that teleostei fatty acyl desaturase (Fads)2 desaturases have undergone during evolution. We previously showed that Chirostoma estor, one of the few representatives of freshwater atherinopsids, had the ability for LC-PUFA biosynthesis from C18 PUFA precursors, in agreement with this species having unusually high contents of DHA. The particular ancestry and pattern of LC-PUFA biosynthesis activity of C. estor make this species an excellent model for study to gain further insight into LC-PUFA biosynthetic abilities among teleosts. The present study aimed to characterize cDNA sequences encoding fatty acyl elongases and desaturases, key genes involved in the LC-PUFA biosynthesis. Results show that C. estor expresses an elongase of very long-chain FA (Elovl)5 elongase and two Fads2 desaturases displaying Δ4 and Δ6/Δ5 specificities, thus allowing us to conclude that these three genes cover all the enzymatic abilities required for LC-PUFA biosynthesis from C18 PUFA. In addition, the specificities of the C. estor Fads2 enabled us to propose potential evolutionary patterns and mechanisms for subfunctionalization of Fads2 among fish lineages.
Fonseca-Madrigal, Jorge; Navarro, Juan C.; Hontoria, Francisco; Tocher, Douglas R.; Martínez-Palacios, Carlos A.; Monroig, Óscar
Currently existing data show that the capability for long-chain PUFA (LC-PUFA) biosynthesis in teleost fish is more diverse than in other vertebrates. Such diversity has been primarily linked to the subfunctionalization that teleostei fatty acyl desaturase (Fads)2 desaturases have undergone during evolution. We previously showed that Chirostoma estor, one of the few representatives of freshwater atherinopsids, had the ability for LC-PUFA biosynthesis from C18 PUFA precursors, in agreement with this species having unusually high contents of DHA. The particular ancestry and pattern of LC-PUFA biosynthesis activity of C. estor make this species an excellent model for study to gain further insight into LC-PUFA biosynthetic abilities among teleosts. The present study aimed to characterize cDNA sequences encoding fatty acyl elongases and desaturases, key genes involved in the LC-PUFA biosynthesis. Results show that C. estor expresses an elongase of very long-chain FA (Elovl)5 elongase and two Fads2 desaturases displaying Δ4 and Δ6/Δ5 specificities, thus allowing us to conclude that these three genes cover all the enzymatic abilities required for LC-PUFA biosynthesis from C18 PUFA. In addition, the specificities of the C. estor Fads2 enabled us to propose potential evolutionary patterns and mechanisms for subfunctionalization of Fads2 among fish lineages. PMID:24792929
Comparación del efecto anestésico del aceite de clavo, solución salina y solución coloidal en juveniles de Chirostoma jordani (Woolman, 1894 Comparison of anaesthetic effect of clove oil, saline solution and colloidal solution in juvenile Chirostoma jordani (Woolman, 1894
Full Text Available Los peces de la especie Chirostoma jordani presentan un intenso estrés durante las prácticas de manejo, dejándolos susceptibles a enfermedades y a tasas altas de mortalidad. El objetivo del presente estudio fue comparar el efecto anestésico del aceite de clavo, solución salina y una solución coloidal (Pentabiocare en juveniles de Chirostoma jordani. Para cada tratamiento se utilizaron 18 ejemplares de C. jordani de dos meses de edad. Los tratamientos constaron en aceite de clavo (5, 8, 13 y 25 µL/L, solución salina (7 g/L y solución coloidal (5 mL/L. Durante seis horas se registraron, en los peces, las fases de inducción a la anestesia y los tiempos de recuperación. Las concentraciones altas y los tiempos prolongados de exposición al aceite de clavo se asociaron a las fases profundas de la anestesia. La concentración de 25 µL/L de aceite de clavo indujo a los organismos a la fase tres y a partir de la tercer hora de exposición éstos entraron en la fase cinco, mientras que las soluciones salina y coloidal indujeron a los peces a la fase uno de sedación mostrando los lapsos más prolongados (seis horas. El tiempo de recuperación de los juveniles en la concentración de 25 µL/L de aceite de clavo se extendió a 3.006,0 ± 5,3 segundos, mientras que con solución salina y coloidal, la respuesta de los peces a la recuperación del ritmo opercular, reactividad a estímulos externos y natación activa fue entre 60 a 180 segundos. Los resultados de este experimento indicaron que la solución salina y solución coloidal mantuvieron a los juveniles de C. jordani en una sedación ligera durante un lapso de seis horas con tiempos breves de recuperación. El uso de aceite de clavo en dosis de 5 y 13 µL/L indujo a los juveniles a estados de anestesia ligera y profunda respectivamente, con una recuperación de no más de 420 segundos.The fish Chirostoma jordani undergoes intense stress during handling practices, making it susceptible to
Delgadillo Calvillo, Ana Carmen
tesis que para obtener el grado de Doctorado en Ciencias de la Producción de la Salud Animal, presenta Ana Carmen Delgadillo Calvillo ; tutor principal de tesis Carlos Gustavo91 páginas : ilustracionesDoctorado en Ciencias de la Producción de la Salud Animal Universidad Nacional Autónoma de México, 2012 Programa de Posgrado en Ciencias de la Producción y de la Salud Animal
Full Text Available Using biotechnology to increase the growth rates of fish is likely to reduce production costs per unit of food. Among vertebrates, fish appear to occupy a unique position, when growth patterns are considered. With few exceptions, fish species tend to grow indeterminately, implying that size is never fixed. Both hyperplasia and hypertrophy contribute to post-larval muscle growth in fish. Growth hormone (GH - Insulin-like Growth Factor I (IGF-I is the most important growth axis in fish. Our experimental model, the pejerrey, Odontesthes bonariensis (Ateriniformes is a South American inland water fish considered to be a promising species for intensive aquaculture. However, one major drawback to achieve this goal is its slow growth in captivity. In order to understand how growth is regulated in this species, our first objective was to characterized pejerrey GH- IGF-I axis. We first cloned and characterized pejerrey (pj GH, IGF-I and the growth hormone receptors (GHRs I and II. In addition to providing valuable data for evolutionary comparison of GH, investigation of GH action in teleosts is particularly important because of its potential application in aquaculture. GH can not only promote the somatic growth in fish but also lower dietary protein requirements. A prerequisite for providing sufficient amounts of GH for basic research and aquaculture application is a large-scale production of GH. For that purpose, recombinant pjGH was expressed in a bacterial system. Protocols for solubilization and proper folding were achieved. Activity of recombinant pjGH was assessed in fish by measuring the liver IGF-I response to different doses of GH. IGF-I transcript was measured in the liver after pjGHr in vivo stimulation by means of quantitative real-time PCR assays. A dose-dependent response of IGF-I mRNA was observed after pjGHr administration, and reached a 6 fold IGF-I maximum increase over control group when 2.5 µg pjGH /g-body weight were injected. Temporal analysis of hepatic IGF-I mRNA levels showed that administration of a single dose of pjGHr into juvenile pejerrey resulted in a significant increase (P<0.02 9 hours post injection. These results demonstrates that recombinant pjGH could promote a dramatic response in liver, increasing the IGF-I mRNA level. We also study the effect of GH on muscle growth after oral administration. A significant association between GH doses and mean fiber area (MFA was observed even with a caloric restrictive diet. MFA increased 3.7 µm² per each unit of GH supplied indicating that GH promoted white muscle hypertrophy. These preliminary data indicates that GH could be absorbed by the intestine in an active form and promote somatic growth.
Helminth parasites of atherinopsid freshwater fishes (Osteichthyes: Atheriniformes from central Mexico Helmintos parásitos de aterinópsidos de agua dulce (Osteichthyes: Atheriniformes del centro de México
Full Text Available Between May 1997 and September 1998, 270 atherinopsids belonging to 7 fish species were analyzed for helminths in 6 lakes located in central Mexico. In addition, a database with all the available previous records of helminth parasites of atherinopsids was built. Based on both information sources, we analyze the composition of the helminth fauna parasitizing atherinopsid freshwater fishes from central Mexico, in order to determine some general species compositional patterns. The helminth fauna parasitizing this fish family in central Mexico is composed by 10 digeneans, 13 cestodes, 1 acanthocephalan, and 8 nematodes (24 of them as larval stage. Individual species richness ranged from 1 to 22 helminth species. Feeding habits of the hosts are identified as the main factor in determining helminth species composition (22 of them are acquired through ingestion. Helminth species composition of almost all host species was dominated by generalist helminth species. Only 2 specialist species were found: Allocreadium mexicanum and Spinitectus osorioi, representing the core helminth fauna of this group of fishes. These results corroborate the hypothesis that the parasite fauna in freshwater fishes is largely circumscribed by higher levels of monophyletic host taxa.Entre mayo de 1997 y septiembre de 1998, se recolectaron 270 aterinópsidos pertenecientes a 7 especies de peces en busca de helmintos, en 6 lagos del centro de México. Basados en esta información y en los registros previos sobre helmintos en este grupo de hospederos, se construyó una base de datos. El objetivo de este estudio es analizar dicha información, para establecer algunos patrones generales acerca de la composición de los helmintos que los parasitan. Treinta y dos especies de helmintos infectan a los peces de esta familia (10 digéneos, 13 cestodos, 1 acantocefalo y 8 nematodos, 24 de ellas en estado larvario. Los hábitos alimenticios de los aterinópsidos determinan la composición de la fauna helmintológica, ya que 22 especies son adquiridas por los peces vía ingestión. La riqueza por especie de pez varió de 1 a 22 especies de helmintos, predominando las generalistas; sólo 2 especies (Allocreadium mexicanum y Spinitectus osorioi son específicas para esta familia de hospederos, lo que confirma la hipótesis de que la parasitofauna en peces de agua dulce está circunscrita a niveles superiores de taxa monofiléticos.
Marins Luis F.
Full Text Available The GH (growth hormone cDNA sequence of the marine silverside fish Odontesthes argentinensis was obtained using the RACE protocol (Rapid Amplification of cDNA Ends. The marine silverside GH cDNA sequence is 928 nucleotides long and was found to encode a polypeptide of 204 amino acids, including a signal peptide of 17 amino acids. The 5' and 3' untranslated regions of the messenger are 109 and 204 nucleotides long, respectively. The deduced GH amino acid sequence was used to infer a phylogenetic tree with GH amino acid sequences from representative species belonging to the Euteleostei Subdivision using the maximum parsimony method. The topology found is according to the major phylogenetic grouping of euteleosts. The results corroborate the hypothesis that atherinids are not related to paracanthopterygians as previously suggested, and show a lack of solid synapomorphies among most of the Acanthopterygii Orders analysed indicating a complex assemblage of fishes in which the phylogenetic tree remains indeterminable.
Octavio M. Vilchis
Full Text Available Se muestra una propuesta de construcción rápida y confiable de los modelos, a partir de una prueba de bondad de ajuste y una de "G" con el fin de apreciar diferencias significativas. Se analiza un estudio de caso que presenta un patrón ecológico (depredación conocido, entre un pez y sus presas.
Evaluation of Melanotaenia duboulayi (Atheriniformes: Melanotaeniidae), Hypseleotris galli (Perciformes: Eleotridae), and larvicide VectoLex WG (Bacillus sphaericus) for integrated control of Culex annulirostris.
Hurst, Timothy P; Brown, Michael D; Kay, Brian H; Ryan, Peter A
Australian freshwater fish species Melanotaenia duboulayi and Hypseleotris galii were selected for a small plot field evaluation of an integrated pest management strategy using native fish and VectoLex WG (Bacillus sphaericus) for the control of Culex annulirostris Skuse, the principal freshwater vector of arbovirus Ross River virus in Australia. When tested alone, the level of control afforded by M. duboulayi and H. galii was highly dependent on the prerelease density of mosquito larvae; and even when stocking rates as high as 10 g per pond (>30 kg/ha) were used, larval abundance was too high to attain adequate control from fish alone. In contrast, treatment with VectoLex WG at 500 g/ha resulted in 100% mortality of Cx. annulirostris immatures, but no residual activity was evident. The delayed reduction of Cx. annulirostris immatures in ponds stocked with fish alone, and the recolonization by Cx. annulirostris in ponds after treatment with B. sphaericus, did not occur when both treatments were combined.
Aparicio Simón, Benjamín
Para producir larvas de peces con buenos rendimientos, se deben conocer los requerimientos nutricionales de la especie, particularmente en los primeros estadios larvarios. Además, se sabe que la nutrición de los reproductores influye directamente en la calidad de las larvas debido, principalmente, a la cantidad y calidad de lípidos que son transferidos desde la gónada hacia los huevos. El objetivo de este trabajo fue analizar la composición de lípidos en huevos, embriones y larvas de pez blan...
SÁNCHEZ BLANCO, JUDITH
Se evaluó el efecto del uso de la benzocaína e hipotermia y su combinación como sedantes en juveniles de C. estor estor. Se utilizaron once distintas concentraciones de benzocaína: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30 y 40 mg/L; estableciéndose once tratamientos, con tres réplicas cada uno y su testigo sin anestésico, en agua con una salinidad de 5‰. Se realizaron observaciones en el siguiente periodo de tiempo: 1, 2, 4, 8, 16, 32 y 64 minutos para cada tratamiento. El experimen...
Hábito alimentar e osteologia da boca do peixe-rei, Odontesthes humensis de Buen (Atheriniformes, Atherinopsidae na Lagoa Mirim, Rio Grande do Sul, Brasil Feeding habits and mouth osteology of silverside, Odontesthes humensis de Buen (Atheriniformes, Atherinopsidae in the Mirim Lagoon, Rio Grande do Sul, Brazil
Fábio Lameiro Rodrigues
Full Text Available Gut contents of 304 individuals of the silverside Odontesthes humensis de Buen, 1953 were analyzed using frequency of occurrence (FO% and gravimetric (P% methods. A total of 207 individuals (68.1% had some food itens in the gut, while 97 individuals (31.9% had empty guts. The silverside Odontesthes humensis has presented a benthic carnivorous diet, preying mainly on molluscs and arthropods. The molluscs Heleobia sp. (FO = 61.35% and Corbicula fluminea (Müller, 1774 (FO = 57.97% were the most frequent itens, followed by Neocorbicula limosa (Maton, 1811 (FO = 17.39%. Among the arthropods, the coleoptera insects (FO= 18.84% were dominant followed by, insect larvae (FO = 6.76%, the crustacean Palaemonetes argentinus Nobili, 1901 (FO = 1.93% and isopods (FO = 1.45%. Vegetal remains, organic matter and digested fish were grouped due to low frequency (FO = 9.13% being considered occasional. Juvenile fed mainly on insect larvae and moluscs, while the adults preferred molluscs and coleoptera. On the description of its feeding apparatus the importance of a protrusible upper jaw was observed, being important on the capture of prey in inaccessible places. A protrusible mouth and the format of the pharingean plates, are important morphological characters that assist on the capture and handling of prey. The molariform shaped pharingean teeth help break hard food items, as shells and carapaces.
Desarrollo de la sagitta en juveniles y adultos de Odontesthes argentinensis (Valenciennes, 1835 y O. bonariensis (Valenciennes, 1835 de la provincia de Buenos Aires, Argentina (Teleostei: Atheriniformes Development of the sagitta in young and adults of Odontesthes argentinensis (Valenciennes, 1835 and Odontesthes bonariensis (Valenciennes, 1835 from Buenos Aires province, Argentina (Teleostei: Atheriniformes
ANDREA D TOMBARI
Full Text Available Se describió el desarrollo del otolito Sagitta de juveniles y adultos de Odontesthes argentinensis procedentes de Punta Rasa (36°22' S y Miramar (38°16' S y de Odontesthes bonariensis de la Laguna de Chascomús (35° 36' S. Se estudió, la morfología de las sagittae de ambas especies, analizando cuatro grupos morfológicos para O. argentinensis (I: 75-120 mm, II: 130-220 mm, III: 230-270 y IV: 280-320 mm y tres grupos morfológicos para O. bonariensis (I: 80-120 mm, II: 130-220 y III: 230-320 mm. Las características morfológicas comunes a la sagitta, de ambas especies, en los grupos estudiados son: presencia de sulcus, depresión areal dorsal en la cara medial, cara lateral con estrías y la presencia de un punto culminante en el borde dorsal. En la sagitta de O. argentinensis, la depresión areal dorsal se inicia ligada a la cauda, característica que permitió distinguir claramente entre otolitos de juveniles de ambas especies. A partir del estado adulto, la depresión areal dorsal se halla separada de la cauda en las dos especies y el análisis estadístico evidenció un crecimiento discontinuo. Se hallaron diferencias morfológicas entre pares de sagitta de un mismo individuo en cuanto a la forma del ostium, presencia de cisura, rostro y punto culminante, aunque no se halló significancia morfométricaThe development of the otolith sagitta was described in young and adults of two silverside species. Odontesthes argentinensis was collected from Punta Rasa (36°22' S and Miramar (38°16' S and, Odontesthes bonariensis collected from Laguna de Chascomús (35°36' S. Sagitta morphology was studied in both species, analyzing four morphological groups of O. argentinensis (I: 75-120 mm, II: 130-220 mm, III: 230-270 mm and IV: 280-320 mm and three morphological groups of O. bonariensis (I: 80-120 mm, II: 130-220 mm and III: 230-320 mm. The morphological features of the sagitta shared by both species are: sulcus present, dorsal areal depression on the medial face, lateral face with striations and the presence of the culminant point on the dorsal margin. The dorsal areal depression of O. argentinensis begins in contact with the cauda. This feature easily identifies the sagittae of young in both species. The dorsal areal depression is separated from the cauda in adults of both species, and the statistical analysis showed a discontinuous growth. Morphological differences were found between pairs of sagittae of the same specimen relating to the shape of the ostium, presence of an anterior excisure, rostrum and the culminant point, but no significant morphometric difference was found
Estrutura populacional de Poecilia vivípara Bloch & Schneider, 1801 (Atheriniformes, Poeciliidae do rio Ceará-Mirim - Rio Grande do Norte Populational structure of Poecilia vivipara Block & Schneider, 1801 (Atheriniformes, Poeciliidae of Ceará-Mirim river, State of Rio Grande do Norte
Renata Swany Soares Nascimento
Full Text Available Com o propósito de elucidar aspectos da estrutura populacional de Poecilia vivipara do rio Ceará-Mirim, município de Poço Branco, Rio Grande do Norte, foram capturados 3.390 exemplares em coletas mensais, no período de junho de 1995 a maio de 1997, utilizando-se tarrafas e peneiras. A partir dos resultados obtidos, constatou-se que as fêmeas, em relação aos machos, predominaram na proporção de 8:1, considerando-se as análises total e sazonal. No que se refere à distribuição por classes de comprimento para os sexos separados, observou-se uma maior amplitude de comprimento das fêmeas em relação aos machos e ainda uma ausência de diferenças entre as estações chuvosa e seca. De acordo com os valores obtidos para o &Teta; (3,86, verificou-se, para a espécie, um crescimento do tipo alométrico positivo. Quanto à influência dos fatores abióticos, fotoperíodo, pluviosidade, temperatura e nível do rio, relacionados aos aspectos da estrutura populacional, não foram verificados resultados significativos que a confirmassemWith the aim of clarifying aspects of the populational structure of Poecilia vivipara in the Ceará-Mirim river, State of Rio Grande do Norte, a total of 3,390 specimens were captured in monthly collections June 1995 trough May 1997, using nets and sieves. Results showed that females, prevailed in the proportion of 8:1, in the whole period as well as seasonaly. The total length classes distribution for separate sexes indicated that females reaches greatest lengths than males with no difference between dry and rainy seasons. The species growth is of the alometric positive type as suggested by the &Teta; value (3,86. No correlation between abiotic factors (photoperiod duration, rainfall, temperature and river water level and the population structure was found
Records of the bird capillariid nematode Ornithocapillaria appendiculata (Freitas, 1933) n. comb. from freshwater fishes in Mexico, with remarks on Capillaria patzcuarensis Osorio-Sarabia et al., 1986.
Moravec, F; Salgado-Maldonado, G; Osorio-Sarabia, D
Re-examination of capillariid specimens collected from the freshwater fish Chirostoma estor Jordan from Lake Pátzcuaro in 1985-1986 and deposited as paratypes of Capillaria patzcuarensis Osorio-Sarabia, Pérez-Ponce de León & Salgado-Maldonado, 1986 showed that their morphology was in contradiction with the description of this species and, in fact, they could be identified as the species originally described as C. appendiculata Freitas, 1933 from cormorants Phalacrocorax brasilianus (Gm.) in Brazil; conspecific capillariid specimens were later recorded from Chirostoma estor and Cyprinus carpio L. from the same locality. This species and two others are transferred to Ornithocapillaria Barus & Sergeeva, 1990 as O. appendiculata (Freitas, 1933) n. comb., O. carbonis (Dubinin & Dubinina, 1940) n. comb., and O. phalacrocoraxi (Borgarenko, 1975) n. comb. This is the first record of O. appendiculata in Mexico. Its occurrence in fishes suggests that these nematodes may be acquired by their fish hosts accidentally while feeding on cormorant excrement containing mature nematodes. A female capillariid collected from one of 110 Chirostoma estor examined from this locality in April, 1998 was identified as Capillaria patzcuarensis. Both capillariid species are briefly described and illustrated.
Espectro trófico del bagre Ictalurus punctatus (Silurifomes: Ictaluridae, en la presa Lázaro Cárdenas, Indé, Durango, México Trophic spectrum of the catfish Ictalurus punctatus (Siluriformes: Ictaluridae, in the Lázaro Cárdenas reservoir, Indé, Durango, Mexico
Gabriel Fernando Cardoza Martínez
Full Text Available Se analizó el contenido de 240 estómagos de Ictalurus punctatus (Rafinesque, 1818, colectados de 2006 a 2007, con el objetivo de determinar su espectro trófico, su variación por talla y época climática. Los contenidos estomacales se analizaron en laboratorio y los organismos se determinaron hasta nivel de orden. Los datos obtenidos fueron analizados por métodos cuantitativos y cualitativos. Los órdenes más frecuentes fueron Perciformes y Atheriniformes que corresponden a peces forraje, así como algas verdes del orden Charales. Además, se encontraron otros siete órdenes de invertebrados: Schizodonta, Odonata, Himenoptera, Orthoptera, Hemiptera, Homoptera y Scorpionida, además de dos órdenes de plantas: Poales y Fabales. El orden Perciforme constituyó casi la mitad del total del peso del contenido estomacal, seguido por los órdenes Atheriniforme y Charales. En las estaciones de verano e invierno se presentó el mayor número de estómagos vacíos, mientras que en primavera se encontró el mayor número de estómagos llenos. La cantidad de alimento ingerida en la estación de invierno fue significativamente menor que en las demás estaciones. El principal alimento en primavera, verano y otoño, fueron los peces, mientras que en invierno hubo mayor preferencia por las algas.Having the objective of determining their trophic spectrum and their variations within a year, the contents of 240 stomachs of Ictalurus punctatus (Rafinesque, 1818 were analyzed from 2006 to 2007. The items of the stomach contents were determined to the order level. The data was analyzed by different quantitative and qualitative methods. The most frequent orders were Perciforms and Atheriniforms corresponding to forage fish, along with green algae of the Charales order. Also, seven orders of invertebrates were found: Schizodonta, Odonata, Himenoptera, Orthoptera, Hemiptera, Homoptera and Scorpionida, and two orders of plants: Poales and Fabales. The Perciform
Chen, Wei-Jen; Bonillo, Céline; Lecointre, Guillaume
Although much progress has been made recently in teleostean phylogeny, relationships among the main lineages of the higher teleosts (Acanthomorpha), containing more than 60% of all fish species, remain poorly defined. This study represents the most extensive taxonomic sampling effort to date to collect new molecular characters for phylogenetic analysis of acanthomorph fishes. We compiled and analyzed three independent data sets, including: (i) mitochondrial ribosomal fragments from 12S and 16s (814bp for 97 taxa); (ii) nuclear ribosomal 28S sequences (847bp for 74 taxa); and (iii) a nuclear protein-coding gene, rhodopsin (759bp for 86 taxa). Detailed analyses were conducted on each data set separately and the principle of taxonomic congruence without consensus trees was used to assess confidence in the results as follows. Repeatability of clades from separate analyses was considered the primary criterion to establish reliability, rather than bootstrap proportions from a single combined (total evidence) data matrix. The new and reliable clades emerging from this study of the acanthomorph radiation were: Gadiformes (cods) with Zeioids (dories); Beloniformes (needlefishes) with Atheriniformes (silversides); blenioids (blennies) with Gobiesocoidei (clingfishes); Channoidei (snakeheads) with Anabantoidei (climbing gouramies); Mastacembeloidei (spiny eels) with Synbranchioidei (swamp-eels); the last two pairs of taxa grouping together, Syngnathoidei (aulostomids, macroramphosids) with Dactylopteridae (flying gurnards); Scombroidei (mackerels) plus Stromatoidei plus Chiasmodontidae; Ammodytidae (sand lances) with Cheimarrhichthyidae (torrentfish); Zoarcoidei (eelpouts) with Cottoidei; Percidae (perches) with Notothenioidei (Antarctic fishes); and a clade grouping Carangidae (jacks), Echeneidae (remoras), Sphyraenidae (barracudas), Menidae (moonfish), Polynemidae (threadfins), Centropomidae (snooks), and Pleuronectiformes (flatfishes).
Full Text Available Specimens of Spinitectus osorioi Choudhury and Pérez-Ponce de León, an intestinal nematode species previously considered to be specific to Chirostoma spp and endemic to some lakes in the Pacific drainage in Michoacán, were collected from the freshwater fish Atherinella alvarezi (Díaz-Pardo (Atherinopsidae of the Michol River near Palenque, Chiapas, Southern Mexico, which belongs to the Atlantic drainage system. Studies using light and scanning electron microscopy revealed some taxonomically important, previously unreported or erroneously reported features of S. osorioi, such as the location of the vulva, the actual number and distribution of postanal papillae and phasmids and the presence of a short median cuticular ridge anterior to the cloacal opening (in addition to two long subventral ridges. The recorded somewhat shorter spicules (420-465 and 105-111 μm and mostly smaller eggs (33-36 × 18-20 μm as compared to the original species description may be due to a different type of host, geographical region or generally smaller body measurements of these specimens. These biometrical differences are considered to be within the limits of the intraspecific variability of S. osorioi. A key to species of Spinitectus parasitizing freshwater fishes in Mexico is provided.
Hernandez, L Patricia; Gibb, Alice C; Ferry-Graham, Lara
Cyprinodontiforms are a diverse and speciose order that includes topminnows, pupfishes, swordtails, mosquitofishes, guppies, and mollies. Sister group to the Beloniformes and Atheriniformes, Cyprinodontiformes contains approximately twice the number of species of these other two orders combined. Recent studies suggest that this group is well suited to capturing prey by "picking" small items from the water surface, water column, and the substrate. Because picking places unusual performance demands on the feeding apparatus, this mode of prey capture may rely upon novel morphological modifications not found in more widespread ram- or suction-based feeding mechanisms. To assess this evolutionary hypothesis, we describe the trophic anatomy of 16 cyprinodontiform species, selected to broadly represent the order as well as capture intrageneric variation. The group appears to have undergone gradual morphological changes to become increasingly specialized for picking and scraping behaviors. We also identify a suite of functional characters related to the acquisition of a novel and previously undescribed mechanism of premaxillary protrusion and retraction, including: modification of the "premaxillomandibular" ligament (which connects each side of the premaxilla to the ipsilateral mandible, or lower jaw), a novel architecture of the ligaments and bony elements that unite the premaxillae, maxillae and palatine bones, and novel insertions of the adductor muscles onto the jaws. These morphological changes to both the upper and lower jaws suggest an evolutionary trend within this group toward increased reliance on picking individual prey from the water column/substrate or for scraping encrusting material from the substrate. We propose that the suite of morphological characters described here enable a functional innovation, "picking," which leads to novel trophic habits.
Fassett, C. I.; Head, J. W.; Kadish, S. J.; Mazarico, E.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.
Impact basin formation is a fundamental process in the evolution of the Moon and records the history of impactors in the early solar system. In order to assess the stratigraphy, sequence, and ages of impact basins and the impactor population as a function of time, we have used topography from the Lunar Orbiter Laser Altimeter (LOLA) on the Lunar Reconnaissance Orbiter (LRO) to measure the superposed impact crater size-frequency distributions for 30 lunar basins (D = 300 km). These data generally support the widely used Wilhelms sequence of lunar basins, although we find significantly higher densities of superposed craters on many lunar basins than derived by Wilhelms (50% higher densities). Our data also provide new insight into the timing of the transition between distinct crater populations characteristic of ancient and young lunar terrains. The transition from a lunar impact flux dominated by Population 1 to Population 2 occurred before the mid-Nectarian. This is before the end of the period of rapid cratering, and potentially before the end of the hypothesized Late Heavy Bombardment. LOLA-derived crater densities also suggest that many Pre-Nectarian basins, such as South Pole-Aitken, have been cratered to saturation equilibrium. Finally, both crater counts and stratigraphic observations based on LOLA data are applicable to specific basin stratigraphic problems of interest; for example, using these data, we suggest that Serenitatis is older than Nectaris, and Humboldtianum is younger than Crisium. Sample return missions to specific basins can anchor these measurements to a Pre-Imbrian absolute chronology.
Bertaco, Vinicius A; Ferrer, Juliano; Carvalho, Fernando R; Malabarba, Luiz R
We herein analyse the history of the description of the freshwater fish fauna from three drainages in one of the most densely collected areas of Brazil, and possibly of South America, the Rio Grande do Sul State, southern Brazil. An updated inventory of the freshwater fish species from rio Uruguay (partial) in Brazil, Laguna dos Patos (complete) and rio Tramandaí basins (complete) is presented. We found the number of new species described in these drainages increased nearly 56% since 1981, reaching a total of 422 species, but even now 10% of this number still corresponds to undescribed species. This rate of species description suggests that previous estimates of the Neotropical fish fauna are low, and we predict a final number of Neotropical fishes larger than the largest prediction estimate (8,000 species), after other regions of South and Central Americas become densely sampled. We discuss and attempt to demonstrate that species diversity knowledge is historically and strictly related to collecting efforts. We also demonstrate that the ecoregions in eastern South America with the highest density of species per area correspond to the areas more densely sampled in collections, and this may represent a bias in such kinds of analyses. This uneven sampling in Brazilian regions is apparently associated with the uneven distribution of Zoological research centers in different regions of the country. Small-sized species represents an important source of new species, along with little explored regions or little explored habitats, sometimes associated with restricted range species, and species complexes that need revisionary work. In contrast to other Neotropical regions, Atheriniformes are relatively diverse, sharing the fifth place in species richness with Gymnotiformes, and there is a remarkably high number of species of Rivulidae. Eight species are endemic to the rio Tramandaí drainage, 68 to the Laguna dos Patos system, and 78 to the rio Uruguay drainage. Almost 10
Thomsen, D. R.; Lawrence, D. J.; Vaniman, D.; Feldman, W. C.; Elphic, R. C.; Barraclough, B. L.; Maurice, S.; Lucey, P. G.; Binder, A. B.
. Most strikingly, ferroan anorthosite (Th < and = 0.37 micro g/g; Fe (wt%)< and =2.29; Ti (wt%) < and = 0.22), which should appear as an almost black, reddish color, does not appear on the diagram at any noticeable frequency. Based on this analysis, the suggestion of extensive FAN regions on the lunar surface is not strong, especially at the presently accepted values for Fe and Th. However, to make sure this effect is not due to systematic errors, a thorough investigation of the precision, accuracy, and uncertainties of the Fe, Ti, and Th abundances needs to be carried out, especially at low concentrations. A particular region of interest is an area of high Th concentrations relative to Fe and Ti content north and east of Humboldtianum Crater. First observed by Lawrence et al., this region does not coincide with any visible impact structure and comprises one of the closest approximations to pure blue (high Th, very low Ti and Fe) on the lunar surface. Such an elemental composition does not lend itself readily to classification, and presents something of an anomaly. More detailed analysis of this region is needed to understand its structure and origin. There seems to be a longitudinal asymmetry in the Th concentrations of the highlands regolith. High-Th, low-Ti, and Fe regions are located between 135 deg and 180 deg longitude and between -30 deg and +30 deg latitude. While the Th levels are not high enough to attract attention in a single elemental display, the variation in the abundance of Th relative to Fe and Ti abundances can be clearly seen. The composition that these data suggest is not well represented in the sample return suite. In addition, these regions were largely missed by the Apollo orbital ground tracks, which only covered the outer edge of the areas of interest. The LP orbital Th data represent the first information about the Th concentrations in these regions of the highlands. Additional information contained in original.