Toxicity of cryoprotectants on Prochilodus lineatus (Valenciennes, 1837) (curimba) embryos in an experimental incubator (Characiformes: Prochilodontidae)

This paper investigated the effect of cryoprotectant substances on Prochilodus lineatus embryos in an experimental incubator. The prospective study applied combinations of polyvinyl alcohol, hydroxyethyl cellulose, gelatin and fetal bovine serum with dimethyl sulfoxide and ethylene glycol in a new experimental incubator. The morphology of embryos, larval viability and the efficiency of experimental incubators in maintaining the quality of embryos were evaluated. This study demonstrates the efficient association between hydroxyethylcellulose and dimethyl sulfoxide as greater viability (p<0.05) was found for embryos (72.9 ± 23.9%). It should also be noted the permeation of cryoprotectants in embryos through the changes found in chorion diameter, embryo diameter and embryo volume comparing the treatments versus control group (water) (p<0.05), this results can help in future cryopreservation protocols. Although the temperature and oxygenation differed between the usual and experimental incubators (p<0.05), the results showed a high fertilization rate (79.6 ± 13.2%) for experimental incubators (p<0.05) which is sufficient for the maintenance of embryos in a cryoprotective environment and effectively allows experimentation for long periods with cryoprotectant substances. Cryopreservation of fish embryos has not been accomplished yet and new approaches are required for understanding the permeability of teleost embryos, especially in Brazilian native species.

Este trabalho avaliou o efeito de substâncias crioprotetoras sobre embriões de Prochilodus lineatus em uma incubadora experimental. O estudo aplicou combinações de álcool polivinílico, hidroxietilcelulose, gelatina e soro fetal bovino com dimetilosulfóxido e etilenoglicol em uma nova incubadora experimental. Foram avaliadas a morfologia dos embriões, a viabilidade larval e a eficiência das incubadoras experimentais na manutenção da qualidade dos embriões. Este estudo demonstra a associação eficiente entre hidroxietilcelulose e dimetilsulfóxido pela maior viabilidade (p<0,05) encontrada para os embriões (72,9 ± 23,9%). Deve-se notar também a permeação dos crioprotetores nos embriões através das alterações encontradas no diâmetro córion, diâmetro do embrião e no volume do embrião comparando os tratamentos ao grupo controle (água) (p<0,05), estes resultados podem ajudar em futuros protocolos de criopreservação. Embora a temperatura e a oxigenação diferiram entre as incubadoras comuns e as experimentais (p<0,05), os resultados mostraram elevada taxa de fertilização (79,6 ± 13,2%) para incubadoras experimentais (p<0,05), o que é suficiente para a manutenção de embriões em ambiente crioprotetor e permite efetivamente a experimentação por longos períodos com substâncias crioprotetoras. A criopreservação de embriões de peixes ainda não foi realizada e novas abordagens são necessárias para a compreensão da permeabilidade dos embriões de teleósteos, especialmente em espécies nativas brasileiras.

Embryonic development of Bryconamericus caucanus (Characidae: Tetragonpterinae) under laboratory conditions / Desarrollo embrionario de Bryconamericus caucanus (Characidae: Tetragonpterinae) en condiciones de laboratorio

In this study we describe the early stages of development of Bryconamericus caucanus under laboratory conditions. Mature females (mean weight 8.12 g) received two intraperitoneal doses of Carp Pituitary Extract (1st dose of 0.5 mg / kg at time 0 and 2nd dose of 5 mg / kg 12 h later), and mature males received a single dose of 0.5 mg / kg at the time of the 2nd dose to the females. Extrusion of eggs was performed at 152.25 Accumulated Thermal Units. Eggs of B. caucanus were yellow, round shaped, non-adhesive, and the perivitelline space after hydratation was moderate. Hatching occurred 28 h 20 min after fertilization (21C, 594.3 Accumulated Thermal Units). The morphological features of the egg and early embryo of B. caucanus were similar to previous reports in other members of the Tetragonopterinae, but the embryonic development was particularly long in this species.

Se estudian, bajo condiciones de laboratorio, los estadios tempranos de desarrollo en Bryconamericus caucanus. Hembras maduras (peso promedio de 8,12g) recibieron dos dosis intraperitoneales de extracto de hipófisis de carpa (1a dosis de 0,5 mg/Kg en la hora cero y 2 dosis de 5 mg/Kg en la hora 12). Así mismo, los machos maduros recibieron una única dosis de 0.5 mg / kg en la 2 dosis de las hembras. Se llevó a cabo desove en seco a 152,25 grados-hora luego de la aplicación de la 2 dosis hormonal. Los huevos de B. caucanus eran amarillos, redondeados, no adhesivos y el espacio perivitelino luego de la hidratación fue moderado. La eclosión se registró 28 h 20 min después de la fertilización (594,3 grado-horas a 21C). La respuesta positiva a la hipofización y las características morfológicas del huevo y del embrión de B. caucanus fueron similares a los reportes previos en otros miembros de la subfamilia Tetragonopterinae, siendo el desarrollo embrionario de B. caucanus particularmente prolongado.

Heme metabolism enzymes are dynamically expressed during Xenopus embryonic development

As the key component of many hemoproteins (heme-containing proteins), heme is involved in a broad range of biological processes. Enzymes required for heme biosynthesis and degradation pathways are evolutionarily conserved. While heme metabolism has been studied extensively, the expression of heme metabolism enzymes during development has not been described. Here, we report that all heme biosynthases and two heme oxygenases, which initiate heme degradation, are dynamically expressed during Xenopus embryonic development. All heme synthases, with the exception of aminolevulinic acid synthase 2, are maternally expressed. At neurula stage, heme synthases are expressed in the developing neural tissue and in migrating neural crest cells. At the swimming tadpole stage, expression of heme synthases can be detected in multiple lineages, including eyes, neural crest cells, developing central nervous system, ventral blood island, pronephron, and pronephric tubule. Similar to heme synthases, heme oxygenases are expressed maternally. Zygotic expression of heme oxygenases is mainly restricted to the developing neural and neural crest lineages. Unlike heme synthases, heme oxygenases are not expressed in the ventral blood island and are expressed at a very low level in the pronephron and pronephric tubule. This indicates that heme metabolism may play important roles during development.

Ubiquitous overexpression of a transgene encoding the extracellular portion of the Drosophila Roughest-Irregular Chiasm C protein induces early embryonic lethality

The cell adhesion molecule Rst-irreC is a transmembrane glycoprotein of the immunoglobulin superfamily involved in several important developmental processes in Drosophila, including axonal pathfinding in the optic lobe and programmed cell death and pigment cell differentiation in the pupal retina. As an initial step towards the "in vivo" functional analysis of this protein we have generated transgenic fly stocks carrying a truncated cDNA construct encoding only the extracellular domain of Rst-IrreC under the transcriptional control of the heat shock inducible promoter hsp70. We show that heat-shocking embryos bearing the transgene during the first 8hs of development lead to a 3-4 fold reduction in their viability compared to wild type controls. The embryonic lethality can already be produced by applying the heat pulse in the first 3hs of embryonic development, does not seem to be suppressed in the absence of wildtype product and is progressively reduced as the heat treatment is applied later in embryogenesis. These results are compatible with the hypothesis of the lethal phenotype being primarily due to heterophilic interactions between Rst-IrreC extracellular domain and an yet unknown ligand.