Use of melatonin as an inhibitor of apoptotic process for cryopreservation of zebrafish (Danio rerio) embryos / Uso da melatonina como inibidor do processo apoptotico para a criopreservação de embriões de zebrafish (Danio rerio)

This study investigated the use of melatonin to arrest the effects of apoptosis in vitrified zebrafish (D. rerio) embryos. Dechorionated embryos at 22-24 somite-stage were divided (n = 60/treatment) into a non-vitrified (Control Group, 0 M melatonin) and vitrified treatments with 0 M (T1), 1 µM (T2) and 1 mM of melatonin (T3). For vitrified treatments, a solution methanol/propylene glycol based was used and the embryos stored in -196 °C for a week. After thaw, survival rate, scanning electron microscopy, expression of anti (bcl-2) and pro-apoptotic (bax/caspase-3) genes, reactive oxygen species (ROS) formation and DNA fragmentation analyses were performed. No live embryos were obtained from vitrified treatments, observing a rapid degeneration immediately after thawing, with the vitelline layer rupture and leakage of its content, followed by breakdown of epithelial cells and melanisation of the tissue. Regarding the apoptotic process, T3 had the highest relative gene expression, for the three genes (P 0.05). The inclusion of 1 µM of melatonin in the vitrifying solution, countered the effects of apoptotic process in post-thaw embryos, suggesting its utility in cryopreserving fish embryos.

Este estudo investigou o uso da melatonina para conter os efeitos da apoptose em embriões vitrificados de zebrafish (D. rerio). Embriões descorionados no estágio de 22-24 somitos foram divididos (n = 60 / tratamento) em tratamento não vitrificado (Grupo Controle, melatonina 0 M) e tratamentos vitrificados com 0 M (T1), 1 µM (T2) e 1 mM de melatonina (T3). Para os tratamentos vitrificados, utilizou-se uma solução à base de metanol/propilenoglicol e os embriões foram armazenados em -196 °C por uma semana. Após o descongelamento, foram realizadas análises de taxa de sobrevivência, microscopia eletrônica de varredura, expressão dos genes anti (bcl-2) e pró-apoptóticos (bax/caspase-3), formação de espécies reativas de oxigênio (EROS) e análises de fragmentação de DNA. Não foram obtidos embriões vivos a partir dos tratamentos vitrificados, observando uma rápida degeneração imediatamente após o descongelamento, com ruptura da camada vitelina e vazamento de seu conteúdo, seguida de quebra das células epiteliais e melanização do tecido. Em relação ao processo apoptótico. T3 apresentou expressão gênica relativa alta para os três genes (P 0,05). A inclusão de 1 µM de melatonina na solução de vitrificação, contrariou os efeitos do processo apoptótico em embriões pós-descongelamento, sugerindo sua utilidade na criopreservação de embriões de peixes.

BPA toxicity during development of zebrafish embryo / Toxicidade do BPA durante o desenvolvimento de embriões de Zebrafish

Bisphenol A (BPA) is a monomer used in the production of polycarbonate, a polymer commonly found in plastics, epoxy resins and thermal papers. The presence of BPA in food, water, air and dust has been of great concern in recent years not only due to environmental and ecological issues but also because of its supposed risk to public health related to its mutagenic and carcinogenic potential. In this study we evaluated the toxicity of bisphenol A in zebrafish embryos (Danio rerio) and determined the 50% lethal concentration (LC50) of this chemical. BPA was used at concentrations ranging from 1 µM to 100 µM in E3 medium/0.5% dimethylsulfoxide (DMSO) from previously prepared stock solutions in 100% DMSO. Controls included embryos exposed only to E3 medium or supplemented with 0.5% DMSO. Camptothecin (CPT), a known inhibitor of cell proliferation was used as positive control at a concentration of 0.001 µM in E3 medium/0.5% DMSO. Adults zebrafish were placed for breeding a day before the experimental set up, then, viable embryos were collected and selected for use. Experiments were carried out in triplicates, according to specifications from Organization for Economic Cooperation and Development (OECD). One embryo/well (25 embryos per concentration) was distributed in 96 well microplates in presence or absence of the chemicals. The plates were kept in BOD incubators with a controlled temperature of 28.5 ºC and with photoperiod of 14 h light:10 h dark. After 24h, 48h, 72h and 96h exposure, the exposed embryos were evaluated according to the following parameters: mortality, coagulation, rate of heartbeat, hatching and presence of morphological abnormalities. Photography was obtained by photomicroscopy. Apoptosis was evaluated by DNA ladder assay. DNA was extracted by phenol:chloroform method and analyzed by 2% agarose gel electrophoresis. DNA fragments were visualized after ethidium bromide staining in ultraviolet transilluminator. The LC50 determined for BPA was 70 µM after 24 hours, 72 µM after 48 hours, 47 µM after 72 hours and 31 µM after 96 hours exposure. BPA induced morphological and physiological alterations such as yolk sac and pericardial edema, hatching delay or inhibition, spine deformation, decreasing in heartbeat rate and mortality. In conclusion, this study demonstrated that BPA induced marked malformations in zebrafish embryos at concentrations above 25 µM corroborating the current concerns related to the widespread presence of BPA in the air, food and water used by humans as well as in the bodily fluids and tissues.

Bisfenol A (BPA) é um monômero utilizado na produção de policarbonato, um polímero comumente encontrado em plásticos, resinas epóxi e papéis térmicos. A presença de BPA em alimentos, água, ar e poeira tem sido motivo de grande preocupação nos últimos anos, não só devido a questões ambientais e ecológicas, mas também ao suposto risco para a saúde pública relacionado ao seu potencial mutagênico e carcinogênico. Neste estudo avaliamos a toxicidade do bisfenol A em embriões de peixe-zebra (Danio rerio) e determinamos a concentração letal 50% (LC50) deste composto químico. O BPA foi usado na faixa de concentração entre 1 µM e 100µM em meio E3/0,5% de dimetilsulfóxido (DMSO), preparado a partir de soluções estoques em 100% DMSO. Os controles negativos incluíram embriões expostos apenas ao meio E3 ou suplementado com 0,5% DMSO. Camptotecina (CPT), um conhecido inibidor da proliferação celular, foi usado como controle positivo a uma concentração de 0,001 µM em meio E3/0,5% DMSO. Peixes-zebra adultos foram colocados para reprodução um dia antes da montagem experimental, em seguida, embriões viáveis foram coletados e selecionados para uso. Os experimentos foram realizados em triplicata, de acordo com as especificações da Organização para Cooperação e Desenvolvimento Econômico (OCDE). Um embrião/ poço (25 embriões por concentração) foi distribuído em microplacas de 96 poços na presença ou ausência dos compostos químicos. As placas foram mantidas em incubadoras BOD com temperatura controlada de 28,5 ºC e com fotoperíodo de 14h claro:10h escuro. Após 24h, 48h, 72h e 96h, os embriões expostos foram avaliados de acordo com os seguintes parâmetros: mortalidade, presença de coagulação, taxa do batimento cardíaco, eclosão e presença de anormalidades morfológicas. Fotografias foram obtidas por fotomicroscopia. A apoptose foi avaliada pelo ensaio de DNA ladder. O DNA foi extraído pelo método fenol:clorofórmio e analisado por eletroforese em gel de agarose a 2%. Fragmentos de DNA foram visualizadas após coloração com brometo de etídio em um transiluminador ultravioleta. A LC50 determinada para o BPA foi 70 µM após 24 horas, 72 µM após 48 horas, 47 µM após 72 horas e 31 µM após exposição por 96 horas. O BPA induziu alterações morfológicas e fisiológicas como edema de saco vitelino e edema pericárdico, atraso no tempo ou inibição da eclosão, deformação da coluna vertebral, diminuição da taxa de batimentos cardíacos e mortalidade. Em conclusão, este estudo demonstrou que o BPA induziu grande número de malformações em embriões de peixe-zebra em concentrações acima de 25 µM, corroborando as preocupações atuais relacionadas a presença generalizada do BPA no ar, alimento e água usados pelos seres humanos bem como nos fluidos e tecidos corporais.

Efeitos tóxicos dos sedimentos do estuário do rio Capibaribe em embriões de zebrafish (Danio rerio) / Toxic effects of sediments of the Capibaribe estuary on zebrafish embryos (Danio rerio)

O presente estudo utilizou embriões de Danio rerio expostos aos elutriatos dos sedimentos estuarinos do rio Capibaribe, dos períodos chuvoso e seco, e analisou os efeitos letais, teratogênicos, bem como a frequência cardíaca. Os testes de toxicidade com os embriões seguiram as diretrizes da OECD 236. Mediante os resultados obtidos, a frequência cardíaca e a teratogenicidade foram os efeitos mais observados nos animais quando submetidos às amostras. Entre os efeitos teratogênicos, o retardo geral no desenvolvimento dos embriões foi o mais frequente durante as análises. Tais efeitos tóxicos se modificaram entre os pontos e entre os períodos de coleta. Essa variação de toxicidade pode estar relacionada à diversidade de atividades realizadas no entorno desse estuário, a influência do regime de chuvas, marés e correntes, indicando que a análise dos efeitos subletais e da teratogenicidade em embriões de D. rerio constitui bom parâmetro para avaliações de toxicidade de amostras ambientais.(AU)

The present study used Danio rerio embryos exposed to the elutriates of the estuarine sediments of the Rio Capibaribe, from the rainy and dry periods, where the lethal effects, teratogenic and heart rate were analyzed. Embryotoxicity tests followed the guidelines of OECD 236. Based on the results obtained, heart rate and teratogenicity demonstrated higher sensitivity to the samples. Among the teratogenic effects, the general delay in embryo development was the most frequent effect during the analyzes. These toxic effects changed between the points and between the collection periods. This variation of toxicity may be related to the diversity of activities carried out around this estuary, the influence of rainfall, tides, and currents, indicating the analysis of sublethal effects and teratogenicity in the D. rerio embryos are useful parameters for toxic evaluation of environmental samples.(AU)

Is there a relationship between complaints of impaired balance and postural control disorder in community-dwelling elderly women? A cross-sectional study with the use of posturography

Background: Risk of falls increases as age advances. Complaints of impaired balance are very common in the elderly age group. Objectives: The objective of this study was to investigate whether the subjective perception of impaired balance was associated with deficits in postural control (objective analysis) in elderly community-dwelling women. Method: Static posturography was used in two groups: elderly women with (WC group) and without (NC group) complaints of impaired balance. The area, mean sway amplitude and mean speed of the center of pressure (COP) in the anterior-posterior (AP) and medial-lateral (ML) directions were analyzed in three stances: single-leg stance, double-leg stance and tandem stance, with eyes open or closed on two different surfaces: stable (firm) and unstable (foam). A digital chronometer was activated to measure the time limit (Tlimit) in the single-leg stance. Kruskal-Wallis tests followed by Mann-Whitney tests, Friedman analyses followed by post hoc Wilcoxon tests and Bonferroni corrections, and Spearman statistical tests were used in the data analysis. Differences of p<0.05 were considered statistically significant. Results: The results of posturography variables revealed no differences between groups. The timed single-leg stance test revealed a shorter Tlimit in the left single-leg stance (p=0.01) in WC group compared to NC group. A negative correlation between posturography variables and Tlimit was detected. Conclusions: Posturography did not show any differences between the groups; however, the timed single-leg stance allowed the authors to observe differences in postural control performance between elderly women with and those without complaints of impaired balance. .

Preoperative Imaging Modalities to Predict the Risk of Regional Nodal Recurrence in Well-Differentiated Thyroid Cancers

Introduction Thyroid cancer incidence has increased in the previous 2 decades. Preoperative identification of lymph node metastasis is a suggested risk factor associated with recurrence following thyroidectomy. Objectives We aimed to evaluate the accuracy of preoperative radiologic investigations of nodal status in determining the postoperative risk of regional nodal recurrence in cases of well-differentiated thyroid cancer. Methods This is a case series. We retrospectively reviewed data, including preoperative ultrasonography and/or computed tomography results, on patients who underwent total thyroidectomy for thyroid cancer at our hospital between 2006 and 2012. Prognostic factors for predicting recurrence, including age, sex, tumor diameter, and nodal diameter, were evaluated. Results Total thyroidectomy was performed on 24 male and 74 female patients (median age, 43 years). The median follow-up time was 21 months. Sixty-eight patients had papillary thyroid cancer, and 30 had follicular cancer. Nodal recurrence was evident in 30% of patients, and 4% of patients died. Identification of lymph node involvement during preoperative radiologic investigations was strongly prognostic for recurrence: 35.3% of patients with positive preoperative ultrasonography findings and 62.5% of those with positive preoperative computed tomography findings had recurrence (p = 0.01). Conclusions Preoperative identification of lymph node metastasis on radiologic studies was correlated with an increased risk of regional nodal recurrence in well-differentiated thyroid cancer. Computed tomography was superior to ultrasonography in detecting metastatic nodal involvement preoperatively and is therefore recommended for preoperative assessment and postoperative follow-up. .

Glyceollins, a novel class of soybean phytoalexins, inhibit SCF-induced melanogenesis through attenuation of SCF/c-kit downstream signaling pathways

The anti-melanogenesis effect of glyceollins was examined by melanin synthesis, tyrosinase activity assay in zebrafish embryos and in B16F10 melanoma cells. When developing zebrafish embryos were treated with glyceollins, pigmentation of the embryos, melanin synthesis and tyrosinase activity were all decreased compared with control zebrafish embryos. In situ expression of a pigment cell-specific gene, Sox10, was dramatically decreased by glyceollin treatment in the neural tubes of the trunk region of the embryos. Stem cell factor (SCF)/c-kit signaling pathways as well as expression of microphthalmia-associated transcription factor (MITF) were determined by western blot analysis. Glyceollins inhibited melanin synthesis, as well as the expression and activity of tyrosinase induced by SCF, in a dose-dependent manner in B16F10 melanoma cells. Pretreatment of B16F10 cells with glyceollins dose-dependently inhibited SCF-induced c-kit and Akt phosphorylation. Glyceollins significantly impaired the expression and activity of MITF. An additional inhibitory function of glyceollins was to effectively downregulate intracellular cyclic AMP levels stimulated by SCF in B16F10 cells. Glyceollins have a depigmentation/whitening activity in vitro and in vivo, and that this effect may be due to the inhibition of SCF-induced c-kit and tyrosinase activity through the blockade of downstream signaling pathway.

AKAP12 regulates vascular integrity in zebrafish

The integrity of blood vessels controls vascular permeability and extravasation of blood cells, across the endothelium. Thus, the impairment of endothelial integrity leads to hemorrhage, edema, and inflammatory infiltration. However, the molecular mechanism underlying vascular integrity has not been fully understood. Here, we demonstrate an essential role for A-kinase anchoring protein 12 (AKAP12) in the maintenance of endothelial integrity during vascular development. Zebrafish embryos depleted of akap12 (akap12 morphants) exhibited severe hemorrhages. In vivo time-lapse analyses suggested that disorganized interendothelial cell-cell adhesions in akap12 morphants might be the cause of hemorrhage. To clarify the molecular mechanism by which the cell-cell adhesions are impaired, we examined the cell-cell adhesion molecules and their regulators using cultured endothelial cells. The expression of PAK2, an actin cytoskeletal regulator, and AF6, a connector of intercellular adhesion molecules and actin cytoskeleton, was reduced in AKAP12-depleted cells. Depletion of either PAK2 or AF6 phenocopied AKAP12-depleted cells, suggesting the reduction of PAK2 and AF6 results in the loosening of intercellular junctions. Consistent with this, overexpression of PAK2 and AF6 rescued the abnormal hemorrhage in akap12 morphants. We conclude that AKAP12 is essential for integrity of endothelium by maintaining the expression of PAK2 and AF6 during vascular development.

A light- and electron microscopic study of primordial germ cells in the zebra fish (Danio rerio)

In sexually reproducing organisms, primordial germ cells (PGCs) give rise to the cells of the germ line, the gametes. In many animals, PGCs are set apart from somatic cells early during embryogenesis. This study explores the origin of primordial germ cells (PGCs) of the zebra fish and examines their morphology during early development (1st day-15th day). PGCs were selectively stained by the alkaline phosphatase histochemical reaction and viewed by light and electron microscopy from the time they are first detectable in the yolk sac endoderm. PGCs occurred in the subendodermal space on the syncytial periblast; differing from the surrounding endodermal cells. Later the PGCs moved to between the blastoderm and yolk sac and transferred to the dorsal mesentery where they formed gonadal anlage with mesoderm cells. PGCs were easily distinguished from somatic cells by their morphology and low electron density of their nuclei. Under light microscopy, PCGs were rounded with a distinct cytoplasmic membrane.

5-Formylhonokiol exerts anti-angiogenesis activity via inactivating the ERK signaling pathway

Our previous report has demonstrated that 5-formylhonokiol (FH), a derivative of honokiol (HK), exerts more potent anti-proliferative activities than honokiol in several tumor cell lines. In present study, we first explored the antiangiogenic activities of 5-formylhonokiol on proliferation, migration and tube formation of human umbilical vein endothelial cells (HUVECs) for the first time in vitro. Then we investigated the in vivo antiangiogenic effect of 5-formylhonokiol on zebrafish angiogenesis model. In order to clarify the underlying molecular mechanism of 5-formylhonokiol, we investigated the signaling pathway involved in controlling the angiogenesis process by western blotting assay. Wound-healing results showed that 5-formylhonokiol significantly and dose-dependently inhibited migration of cultured human umbilical vein enthothelial cells. The invasiveness of HUVEC cells was also effectively suppressed at a low concentration of 5-formylhonokiol in the transwell assay. Further F-actin imaging revealed that inhibitory effect of 5-formylhonokiol on invasion may partly contribute to the disruption of assembling stress fiber. Tube formation assay, which is associated with endothelial cells migration, further confirmed the anti-angiogenesis effect of 5-formylhonokiol. In in vivo zebrafish angiogenesis model, we found that 5-formylhonokiol dose-dependently inhibited angiogenesis. Furthermore, western blotting showed that 5-formylhonokiol significantly down-regulated extracellular signal-regulated kinase (ERK) expression and inhibited the phosphorylation of ERK but not affecting the total protein kinase B (Akt) expression and related phosphorylation, suggesting that 5-formylhonokiol might exert anti-angiogenesis capacity via down-regulation of the ERK signal pathway. Taken together, these data suggested that 5-formylhonokiol might be a viable drug candidate in antiangiogenesis and anticancer therapies.

Sublethal concentrations of waterborne copper induce cellular stress and cell death in zebrafish embryos and larvae

Copper is an essential ion that forms part of the active sites of many proteins. At the same time, an excess of this metal produces free radicals that are toxic for cells and organisms. Fish have been used extensively to study the effects of metals, including copper, present in food or the environment. It has been shown that different metals induce different adaptive responses in adult fish. However, until now, scant information has been available about the responses that are induced by waterborne copper during early life stages of fish. Here, acute toxicity tests and LC50 curves have been generated for zebrafish larvae exposed to dissolved copper sulphate at different concentrations and for different treatment times. We determined that the larvae incorporate and accumulate copper present in the medium in a concentration-dependent manner, resulting in changes in gene expression. Using a transgenic fish line that expresses enhanced green fluorescent protein (EGFP) under the hsp70 promoter, we monitored tissue-specific stress responses to waterborne copper by following expression of the reporter. Furthermore, TUNEL assays revealed which tissues are more susceptible to cell death after exposure to copper. Our results establish a framework for the analysis of whole-organism management of excess external copper in developing aquatic animals.

The CK1 gene family: expression patterning in zebrafish development

Protein kinase CK1 is a ser/thr protein kinase family which has been identified in the cytosol cell fraction, associated with membranes as well as in the nucleus. Several isoforms of this gene family have been described in various organisms: CK1 , CK1á, CK1δ, CK1å and CK1γ. Over the last decade, several members of this family have been involved in development processes related to wnt and sonic hedgehog signalling pathways. However, there is no detailed temporal information on the CK1 family in embryonic stages, even though orthologous genes have been described in several different vertebrate species. In this study, we describe for the first time the cloning and detailed expression pattern of five CK1 zebrafish genes. Sequence analysis revealed that zebrafish CK1 proteins are highly homologous to other vertebrate orthologues. Zebrafish CK1 genes are expressed throughout development in common and different territories. All the genes studied in development show maternal and zygotic expression with the exception of CK1å. This last gene presents only a zygotic component of expression. In early stages of development CK1 genes are ubiquitously expressed with the exception of CK1å. In later stages the five CK1 genes are expressed in the brain but not in the same way. This observation probably implicates the CK1 family genes in different and also in redundant functions. This is the first time that a detailed comparison of the expression of CK1 family genes is directly assessed in a vertebrate system throughout development.