Réseaux trophiques et production piscicole en étangs fertilisés (Dordogne, France)

Des séries de données (physicochimie, plancton, poisson) collectées pendant deux saisons consécutives sur deux groupes d'étangs de pisciculture de Dordogne (Sud-ouest de la France) ont été analysées statistiquement (analyses en composantes principales ACP, analyse des correspondances multiples ACM, tris croisés). Des liens significatifs entre les différents constituants de la chaîne trophique ont été identifiés, et les facteurs clés de la production piscicole mis en évidence. En début de saison, une régulation ascendante oriente la composition et l'abondance de la flore algale, suivant les concentrations de N et PO4 et leurs proportions relatives. L'abondance du zooplancton filtreur est liée à la fois aux ressources trophiques disponibles (cellules algales aisément ingérables) et à la pression de prédation qu'il subit de la part des juvéniles de poissons. La production piscicole de gardon (Rutilus rutilus) et de tanche (Tinca tinca) est plus faible si ces espèces sont associées (compétition alimentaire interspécifique chez les juvéniles) ou produites en présence d'un carnivore. En contre-partie d'une production piscicole plus faible, la stabilité de la structure du réseau trophique est accrue. Les concentrations en P-PO4, la quantité de grands Crustacés planctoniques et une densité de poissons adaptée aux capacités du milieu constituent les facteurs clés de la production piscicole finale.The main parameters (physicochemistry, plankton, fish) of two sets of fish ponds (8 and 9 ponds respectively; area between 0.2 and 1.2 ha; mean depth: 1.5 m) located in south-west of France were monitored during two consecutive seasons (1995, 1996). The benthic macroinvertebrates and the microbial loop were not taken into account for these field studies. No macrophytes were growing into the studied ponds. The multivariate analyses of the two yearly data bases provided informations on the strength of the various links among and between the successive compartments of the food web (physicochemistry of water, phytoplankton, zooplankton and fish) and identified the bottlenecks of the food web to the fish production.Integrated water samples were collected bimonthly (from May to September) for field measurements (T°, pH, dissolved O2, Secchi disc transparency, conductivity) and laboratory analyses ([N.NH4], [N.NO2], [N.NO3], [ortho-P], [Ca] using a HACH spectrophotometer). The groups of planktonic algae (Diatoms, Desmidieae, Dinophyceae, Chlorococcales and Volvocales, Euglenophyceae, Cyanobacteriae) were identified and classified in three categories (dominant, present, rare). Rotifers, Cladocerans and Copepods were numbered (N/litre) into two size classes (large or small, with a threshold at 400 µm). One hundred liters of pond water were filtered through a plankton net (mesh size: 80 µm) and the volume of sedimented zooplankters measured as zooplankton biovolume (mL/100 liters). The total numbers of fish stocked and collected are noted (weight and number of fish/species; age classes). Working on private production ponds, we were not allowed to make catches for stomach contents studies.The data from each season were analysed through PCA, MCA, crosstabs (STATBOX software from GRIMMER); for each species of fish a ratio was computed between the biomass of the collected juveniles and the biomass of the stocked breeders. In the studied fish ponds like in other eutrophic bodies of water, the densities of the planktonic organisms follow a bimodal evolution, with high numbers at the end of spring (June) and the end of summer (August), separated by a phase of more transparent water. During the first phase, Daphnia and large Cladocerans are predominant with Chlorophyceae, replaced later in the season by species of smaller size and shorter life cycle (Bosmina, Ceriodaphnia, Cyclops), associated with Cyanobacteriae, at a time where predation by fish is more intense as their biomass increase. In spring, different algal communities develop with density depending on the initial concentrations of inorganic N and PO4 and the PO4 /N ratio. If the available dissolved N and P are infra-optimal, mixotroph algae (Chrysophyceae, Dinophyceae) and Rotifers predominate. When [N] is not limiting (N/P between 4/1 and 10/1), Chlorophyceae become predominant, but if PO4 is in relative excess, they are replaced by Cyanobacteria. The abundance of grazing Cladocerans is linked to the capacity of the available algal cells to be ingested. Cyanobacteria can already become predominant in May because of the selective grazing by Cladocerans on more readily ingestible phytoplankton taxa. Links among groups of zooplankton are evidenced: small grazers (Rotifers, Cladocera 2 mL/100 L), a water transparency between 0.30 and 0.70 m and are related to a shift from small size species ( 400 µm). In spring numerous small zooplankters facilitate the survival of the fish fry, whose growth is later ensured by high densities of larger Crustaceans.From the fish production data, the ratios between the biomass of collected juveniles and the biomass of stocked breeders were compared under different rearing conditions for the various species. Roach Rutilus rutilus, tench Tinca tinca and gudgeon Gobio gobio have similar production potentials when reared separately (juveniles production in kg is 5 to 7 times the biomass of the breeders). When roach and tench are reared together under the same conditions, the ratio is divided by 2 for each species, but the total net production of fish remains at the same level (500-600 kg/ha). This shows that there is a strong feeding competition on zooplankton between the juveniles of roach and tench. In opposition, there is little feeding competition between roach and gudgeon. When the two benthic species are associated, tench strongly dominates the gudgeon. The addition of a carnivorous species to the association of roach + tench reduces the final total production by 250-300 kg/ha. Between 30 and 40 kg of carnivorous fish (Esox lucius or Stizostedion lucioperca) are produced at the expense of the equivalent of a final biomass of 200 kg/ha of young Cyprinids. The pressure of predation from these two top consumers is 2 to 3 times less intense compared to the predation exerted by the large-mouth bass Micropterus salmoides.As the basic food for juvenile fish, the zooplankton can be considered here as the key element of the food web, between the bottom-up (production) and top-down (predation) effects. The ortho-phosphate concentration is the limiting factor for the ascending regulation of the food web, and the amount of initially stocked fish regulates the top-down effects. The maximum net final fish production reached about 800 kg/ha with roach alone, or in association with tench. In such cases, Cyanobacteria were dominant in the pond with the presence of Chlorophyceae. The low density of zooplankton and the sub-optimal dissolved oxygen concentrations during the day seem to indicate that at such production level, the food chain is near to collapse

Utilisation du phytoplancton pour estimer la production piscicole potentielle des étangs

Pour faciliter la gestion des étangs de pisciculture, il est nécessaire d'avoir un moyen pour estimer en cours de saison si l'objectif de production sera atteint, et éventuellement, intervenir sur la qualité du milieu. Les méthodes d'estimation et de prévision mentionnées dans la littérature ne sont pas applicables aux étangs de pisciculture, milieux fortement anthropisés. A partir de données (physico-chimie, plancton, production piscicole) collectées sur 36 étangs en France, les auteurs proposent une méthode de prévision de la récolte piscicole à partir du phytoplancton (groupe prédominant et teneur en chlorophylle a). A l'usage, cette méthode s'est avérée satisfaisante pour prévoir des productions nettes jusqu'à plus de 500 kg/hectare

Efficacy and safety of vandetanib in progressive and symptomatic medullary thyroid Cancer: Post hoc analysis from the ZETA trial

PURPOSE We conducted a post hoc analysis of the vandetanib phase III trial involving patients with advanced medullary thyroid cancer (MTC) to assess the efficacy and safety of vandetanib in patients with progressive and symptomatic MTC. The primary objective of the analysis was to determine progression-free survival (PFS) of these patients. PATIENTS AND METHODS Eligible patients from the ZETA trial were divided into 4 disease severity subgroups: progression and symptoms, symptoms only, progression only, and no progression and no symptoms assessed at baseline. PFS, determined from objective tumor measurements performed by the local investigator, overall survival (OS), time to worsening of pain (TWP), and objective response rate (ORR) were evaluated. RESULTS Of the 331 patients in this trial, 184 had symptomatic and progressive disease at baseline. In this subgroup, results were similar in magnitude to those observed in the overall trial for PFS (hazard ratio [HR], 0.43; 95% CI, 0.28 to 0.64; P, .0001), OS (HR, 1.08; 95% CI, 0.72 to 1.61; P 5 .71), and TWP (HR, 0.67; 95% CI, 0.43 to 1.04; P 5 .07), and the observed adverse events were consistent with the known safety profile of vandetanib. In this subgroup, the ORR was 37% in the treatment arm versus 2% in the placebo arm. CONCLUSION Vandetanib demonstrated clinical benefit—specifically, increased PFS—in patients with symptomatic and progressive MTC

Correlative analyses of RET and RAS mutations in a phase 3 trial of cabozantinib in patients with progressive, metastatic medullary thyroid cancer

BACKGROUND: Cabozantinib significantly prolonged progression-free survival (PFS) versus a placebo in patients with progressive, metastatic medullary thyroid cancer (MTC; P <.001). An exploratory analysis of phase 3 trial data evaluated the influence of rearranged during transfection (RET) and RAS (HRAS, KRAS, and NRAS) mutations on cabozantinib clinical activity. METHODS: Patients (n = 330) were randomized to cabozantinib (140 mg/day) or a placebo. The primary endpoint was PFS. Additional outcome measures included PFS, objective response rates (ORRs), and adverse events in RET and RAS mutation subgroups. RESULTS: Among all study patients, 51.2% were RET mutation–positive (38.2% with RET M918T), 34.8% were RET mutation–unknown, and 13.9% were RET mutation–negative. Sixteen patients were RAS mutation–positive. Cabozantinib appeared to prolong PFS versus the placebo in the RET mutation–positive subgroup (hazard ratio [HR], 0.23; 95% confidence interval [CI], 0.14-0.38; P <.0001), the RET mutation–unknown subgroup (HR, 0.30; 95% CI, 0.16-0.57; P =.0001), and the RAS mutation–positive subgroup (HR, 0.15; 95% CI, 0.02-1.10; P =.0317). The RET M918T subgroup achieved the greatest observed PFS benefit from cabozantinib versus the placebo (HR, 0.15; 95% CI, 0.08-0.28; P <.0001). The ORRs for RET mutation–positive, RET mutation–negative, and RAS mutation–positive patients were 32%, 22%, and 31%, respectively. No PFS benefit was observed in patients lacking both RET and RAS mutations, although the ORR was 21%. The safety profile for all subgroups was similar to that for the overall cabozantinib arm. CONCLUSIONS: These data suggest that cabozantinib provides the greatest clinical benefit to patients with MTC who have RET M918T or RAS mutations. However, a prospective trial is needed to confirm the relation between genetic variation and the response to cabozantinib. Cancer 2016;122:3856–3864. © 2016 American Cancer Society

Visual impairment from fibrous dysplasia in a middle-aged African man: a case report

<p>Abstract</p> <p>Introduction</p> <p>Fibrous dysplasia is a benign tumour of the bones and is a disease of unknown aetiology. This report discusses a case of proptosis and visual deterioration with associated bony mass involving the right orbit.</p> <p>Case presentation</p> <p>A 32-year-old Nigerian man of Yoruba ethnic origin presented to the eye clinic of our hospital with right-eye proptosis and visual deterioration of 7-year duration. Presentation was preceded by a history of trauma. Proptosis was preceded by trauma but was non-pulsatile with no thrill or bruit but was associated with bony orbital mass. The patient reported no weight loss. Examination of his right eye showed visual acuity of 6/60 with relative afferent pupillary defect. Fundal examination revealed optic atrophy. Computed tomography showed an expansile bony mass involving all the walls of the orbit. The bony orbital mass was diagnosed histologically as fibrous dysplasia. Treatment included orbital exploration and orbital shaping to create room for the globe and relieve pressure on the optic nerve.</p> <p>Conclusion</p> <p>Fibrous dysplasia should be considered in the differential diagnosis of slowly developing proptosis with associated visual loss in young adults.</p

Recovery of NIS expression in thyroid cancer cells by overexpression of Pax8 gene

BACKGROUND: Recovery of iodide uptake in thyroid cancer cells by means of obtaining the functional expression of the sodium/iodide symporter (NIS) represents an innovative strategy for the treatment of poorly differentiated thyroid cancer. However, the NIS gene expression alone is not always sufficient to restore radioiodine concentration ability in these tumour cells. METHODS: In this study, the anaplastic thyroid carcinoma ARO cells were stably transfected with a Pax8 gene expression vector. A quantitative RT-PCR was performed to assess the thyroid specific gene expression in selected clones. The presence of NIS protein was detected by Western blot and localized by immunofluorescence. A iodide uptake assay was also performed to verify the functional effect of NIS induction and differentiation switch. RESULTS: The clones overexpressing Pax8 showed the re-activation of several thyroid specific genes including NIS, Pendrin, Thyroglobulin, TPO and TTF1. In ARO-Pax8 clones NIS protein was also localized both in cell cytoplasm and membrane. Thus, the ability to uptake the radioiodine was partially restored, associated to a high rate of efflux. In addition, ARO cells expressing Pax8 presented a lower rate of cell growth. CONCLUSION: These finding demonstrate that induction of Pax8 expression may determine a re-differentiation of thyroid cancer cells, including a partial recovery of iodide uptake, fundamental requisite for a radioiodine-based therapeutic approach for thyroid tumours

Enhanced CellClassifier: a multi-class classification tool for microscopy images

BACKGROUND: Light microscopy is of central importance in cell biology. The recent introduction of automated high content screening has expanded this technology towards automation of experiments and performing large scale perturbation assays. Nevertheless, evaluation of microscopy data continues to be a bottleneck in many projects. Currently, among open source software, CellProfiler and its extension Analyst are widely used in automated image processing. Even though revolutionizing image analysis in current biology, some routine and many advanced tasks are either not supported or require programming skills of the researcher. This represents a significant obstacle in many biology laboratories. RESULTS: We have developed a tool, Enhanced CellClassifier, which circumvents this obstacle. Enhanced CellClassifier starts from images analyzed by CellProfiler, and allows multi-class classification using a Support Vector Machine algorithm. Training of objects can be done by clicking directly "on the microscopy image" in several intuitive training modes. Many routine tasks like out-of focus exclusion and well summary are also supported. Classification results can be integrated with other object measurements including inter-object relationships. This makes a detailed interpretation of the image possible, allowing the differentiation of many complex phenotypes. For the generation of the output, image, well and plate data are dynamically extracted and summarized. The output can be generated as graphs, Excel-files, images with projections of the final analysis and exported as variables. CONCLUSION: Here we describe Enhanced CellClassifier which allows multiple class classification, elucidating complex phenotypes. Our tool is designed for the biologist who wants both, simple and flexible analysis of images without requiring programming skills. This should facilitate the implementation of automated high-content screening