Physiological parameters of Piaractus mesopotamicus (Osteichthyes: Characidae) exposed to a biopesticide based on Bacillus thuringiensis.

This study investigated the physiological effects of a pesticide based on Bacillus thuringiensis (Dipel-WP®) added in the water and diet of Piaractus mesopotamicus during 24 and 48 h. It was added 0.13 g of de B. thuringiensis per kg of commercial feed; and for the fish subjected to the biopesticide in the water of the tanks, it was added 0.13 g/L of the biopesticide. Plasma levels of sodium, chloride, potassium, cholesterol, glucose, triglycerides, cortisol, total protein, alanine aminotransferase (ALT), aspartate aminotransferase (AST), hematocrit, hemoglobin, erythrocytes number, mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC), number of thrombocytes and leukocytes were determined. Cortisol, lactate, glucose, total protein, cholesterol, triglycerides, ALT, AST, sodium, potassium, hematocrit, hemoglobin, MCV, number of erythrocytes, leukocytes, lymphocytes, eosinophils and PAS-positive granular leukocytes suffered alterations derived from the addition of B. thuringiensis in water and diet of the fish. The toxicity of the concentrations of biopesticide in short-term exposure in water and diet of the fish led to blood alterations (increase or decrease). Therefore, care must be taken to avoid a possible prolonged contamination in the tanks of fish farming by agricultural pollution based on B. thuringiensis.

Is the flexible GnRH antagonist protocol better suited for fresh eSET cycles?

OBJECTIVE: This study was performed to evaluate the efficacy of the flexible GnRH antagonist protocol in comparison with the long GnRH agonist protocol in elective single embryo transfer (eSET) practice. It was conducted in a publicly funded in vitro fertilization program. METHODS: We performed a prospective cohort analysis of data from a private infertility clinic from August 2010 to August 2011. Three hundred fourteen women with normal ovarian reserve and undergoing fresh eSET cycles were included. Sixty-four women underwent follicular stimulation using a flexible GnRH antagonist protocol, and 250 underwent stimulation with a standard long mid-luteal GnRH agonist protocol. RESULTS: Implantation rates (35.9% in the GnRH antagonist group and 29.6% in the GnRH agonist group, P = 0.5) and ongoing pregnancy rates (32.8% in the GnRH antagonist group and 28.8% in the GnRH agonist group, P = 0.5) were equivalent in both groups. The duration of stimulation (9.8 ± 2 days vs. 10.7 ± 1.8 days, P < 0.001) and total FSH dose required (2044 vs. 2775 IU, P < 0.001) were lower in the GnRH antagonist group than in the GnRH agonist group. The number of mature oocytes (6.0 vs. 10.0, P < 0. 001) and number of embryos (5.0 vs. 7.0, P < 0.001) were also lower in GnRH antagonist group. However, the number of embryos cryopreserved was similar in both groups (median 2.0, P = 0.3). CONCLUSION: In women undergoing in vitro fertilization, the flexible GnRH antagonist protocol yields implantation and ongoing pregnancy rates that are similar to the long GnRH agonist protocol, and requires lower doses of gonadotropins and a shorter duration of treatment. The flexible GnRH antagonist protocol appears to be the protocol of choice for an eSET IVF program.

Objectif : La présente étude visait à évaluer l'efficacité d'un protocole flexible ayant recours à des antagonistes de la GnRH, par comparaison avec celle d'un protocole long ayant recours à des agonistes de la GnRH, relativement au transfert sélectif d'un seul embryon (TsSE). L'étude a été menée dans le cadre d'un programme de fécondation in vitro financé par l'État. Méthodes : Nous avons effectué une analyse de cohorte prospective au moyen de données issues d'une clinique de fertilité privée, pour ce qui est de la période d'août 2010 à août 2011. Trois cent quatorze femmes présentant une réserve ovarienne normale et se soumettant à des cycles de TsSE frais ont été admises à l'étude. Un protocole flexible ayant recours à des antagonistes de la GnRH a été utilisé chez 64 femmes, aux fins de la stimulation folliculaire, tandis qu'un protocole long en phase lutéale standard ayant recours à des agonistes de la GnRH a été utilisé chez 250 autres femmes. Résultats : Les taux d'implantation (35,9 % au sein du groupe « antagonistes de la GnRH ¼ et 29,6 % au sein du groupe « agonistes de la GnRH ¼, P = 0,5) et les taux de grossesse en cours (32,8 % au sein du groupe « antagonistes de la GnRH ¼ et 28,8 % au sein du groupe « agonistes de la GnRH ¼, P = 0,5) étaient équivalents dans les deux groupes. La durée de la stimulation (9,8 jours ± 2 jours vs 10,7 jours ± 1,8 jour, P < 0,001) et la dose totale de FSH requise (2 044 vs 2 775 UI, P < 0,001) étaient moins élevées au sein du groupe « antagonistes de la GnRH ¼, par comparaison avec le groupe « agonistes de la GnRH ¼. Le nombre d'ovocytes matures (6,0 vs 10,0, P < 0,001) et le nombre d'embryons (5,0 vs 7,0, P < 0,001) étaient également moins élevés au sein du groupe « antagonistes de la GnRH ¼. Cependant, le nombre d'embryons cryoconservés était similaire dans les deux groupes (médiane : 2,0, P = 0,3). Conclusion : Chez les femmes qui font appel à la fécondation in vitro, le protocole flexible ayant recours à des antagonistes de la GnRH donne des taux d'implantation et de grossesse en cours similaires à ceux que permet le protocole long standard ayant recours à des agonistes de la GnRH, tout en nécessitant des doses plus faibles de gonadotropines et un traitement de plus courte durée. Le protocole flexible ayant recours à des antagonistes de la GnRH semble être le protocole à privilégier dans le cadre d'un programme de FIV utilisant le TsSE.

Reconstruction of rat retinal progenitor cell lineages in vitro reveals a surprising degree of stochasticity in cell fate decisions.

In vivo cell lineage-tracing studies in the vertebrate retina have revealed that the sizes and cellular compositions of retinal clones are highly variable. It has been challenging to ascertain whether this variability reflects distinct but reproducible lineages among many different retinal progenitor cells (RPCs) or is the product of stochastic fate decisions operating within a population of more equivalent RPCs. To begin to distinguish these possibilities, we developed a method for long-term videomicroscopy to follow the lineages of rat perinatal RPCs cultured at clonal density. In such cultures, cell-cell interactions between two different clones are eliminated and the extracellular environment is kept constant, allowing us to study the cell-intrinsic potential of a given RPC. Quantitative analysis of the reconstructed lineages showed that the mode of division of RPCs is strikingly consistent with a simple stochastic pattern of behavior in which the decision to multiply or differentiate is set by fixed probabilities. The variability seen in the composition and order of cell type genesis within clones is well described by assuming that each of the four different retinal cell types generated at this stage is chosen stochastically by differentiating neurons, with relative probabilities of each type set by their abundance in the mature retina. Although a few of the many possible combinations of cell types within clones occur at frequencies that are incompatible with a fully stochastic model, our results support the notion that stochasticity has a major role during retinal development and therefore possibly in other parts of the central nervous system.

Computational prediction of neural progenitor cell fates.

Understanding how stem and progenitor cells choose between alternative cell fates is a major challenge in developmental biology. Efforts to tackle this problem have been hampered by the scarcity of markers that can be used to predict cell division outcomes. Here we present a computational method, based on algorithmic information theory, to analyze dynamic features of living cells over time. Using this method, we asked whether rat retinal progenitor cells (RPCs) display characteristic phenotypes before undergoing mitosis that could foretell their fate. We predicted whether RPCs will undergo a self-renewing or terminal division with 99% accuracy, or whether they will produce two photoreceptors or another combination of offspring with 87% accuracy. Our implementation can segment, track and generate predictions for 40 cells simultaneously on a standard computer at 5 min per frame. This method could be used to isolate cell populations with specific developmental potential, enabling previously impossible investigations.