The main actors involved in parasitization of Heliothis virescens larva

At the moment of parasitization by another insect, the host Heliothis larva is able to defend itself by the activation of humoral and cellular defenses characterized by unusual reactions of hemocytes in response to external stimuli. Here, we have combined light and electron microscopy, staining reactions, and immunocytochemical characterization to analyze the activation and deactivation of one of the most important immune responses involved in invertebrates defense, i.e., melanin production and deposition. The insect host/parasitoid system is a good model to study these events. The activated granulocytes of the host insect are a major repository of amyloid fibrils forming a lattice in the cell. Subsequently, the exocytosed amyloid lattice constitutes the template for melanin deposition in the hemocel. Furthermore, cross-talk between immune and neuroendocrine systems mediated by hormones, cytokines, and neuromodulators with the activation of stress-sensoring circuits to produce and release molecules such as adrenocorticotropin hormone, alpha melanocyte-stimulating hormone, and neutral endopeptidase occurs. Thus, parasitization promotes massive morphological and physiological modifications in the host insect hemocytes and mimics general stress conditions in which phenomena such as amyloid fibril formation, melanin polymerization, pro-inflammatory cytokine production, and activation of the adrenocorticotropin hormone system occur. These events observed in invertebrates are also reported in the literature for vertebrates, suggesting that this network of mechanisms and responses is maintained throughout evolution

Autophagy–physiology and pathophysiology

“Autophagy” is a highly conserved pathway for degradation, by which wasted intracellular macromolecules are delivered to lysosomes, where they are degraded into biologically active monomers such as amino acids that are subsequently re-used to maintain cellular metabolic turnover and homeostasis. Recent genetic studies have shown that mice lacking an autophagy-related gene (Atg5 or Atg7) cannot survive longer than 12 h after birth because of nutrient shortage. Moreover, tissue-specific impairment of autophagy in central nervous system tissue causes massive loss of neurons, resulting in neurodegeneration, while impaired autophagy in liver tissue causes accumulation of wasted organelles, leading to hepatomegaly. Although autophagy generally prevents cell death, our recent study using conditional Atg7-deficient mice in CNS tissue has demonstrated the presence of autophagic neuron death in the hippocampus after neonatal hypoxic/ischemic brain injury. Thus, recent genetic studies have shown that autophagy is involved in various cellular functions. In this review, we introduce physiological and pathophysiological roles of autophagy

Population ecology of the sea lamprey (Petromyzon marinus) as an invasive species in the Laurentian Great Lakes and an imperiled species in Europe

The sea lamprey Petromyzon marinus (Linnaeus) is both an invasive non-native species in the Laurentian Great Lakes of North America and an imperiled species in much of its native range in North America and Europe. To compare and contrast how understanding of population ecology is useful for control programs in the Great Lakes and restoration programs in Europe, we review current understanding of the population ecology of the sea lamprey in its native and introduced range. Some attributes of sea lamprey population ecology are particularly useful for both control programs in the Great Lakes and restoration programs in the native range. First, traps within fish ladders are beneficial for removing sea lampreys in Great Lakes streams and passing sea lampreys in the native range. Second, attractants and repellants are suitable for luring sea lampreys into traps for control in the Great Lakes and guiding sea lamprey passage for conservation in the native range. Third, assessment methods used for targeting sea lamprey control in the Great Lakes are useful for targeting habitat protection in the native range. Last, assessment methods used to quantify numbers of all life stages of sea lampreys would be appropriate for measuring success of control in the Great Lakes and success of conservation in the native range

Des forêts sacrées aux cours-jardins dans le sud du Bénin

info:eu-repo/semantics/publishe

Estimation des densités d’anguilles jaunes d’Europe (Anguilla anguilla) en France, basée sur leur diffusion dans les bassins versants : Modèle TABASCO (spaTialized Anguilla BASin COLonisation) : rapport intermédiaire année 2

Les caractéristiques du modèle EDA, et notamment certaines de ses hypothèses, nous ont conduit à proposer une nouvelle modélisation nommée TABASCO pour « spaTialised Anguilla BASin COlonisation assessment model ». TABASCO doit être considéré comme un intermédiaire entre des méthodes strictement statistiques et des modèles mécanistes. Deux approches ont été développées en parallèle. La première repose sur la propagation au travers d’un graphe orienté d’une gaussienne correspondant à la résultante d’une onde de diffusion. La seconde correspond à l’utilisation de matrices de transition pour décrire la dynamique de colonisation des anguilles. La formalisation des calculs a permis d’établir une première version du code informatique. Une phase de correction des erreurs de codage, puis d’amélioration des différentes étapes du calcul a ensuite rendu possible une calibration avec les données de pêche électrique sur un bassin versant de référence (Gironde). Enfin, le code a été adapté pour prendre en compte l’ensemble des bassins versants de France métropolitaine, et tourne actuellement sur 60 bassins versants représentant 70,4 % de la superficie de la France métropolitaine

A new sampling technique for larval lamprey population assessment in small river catchments

Office National de l'Eau et des Milieux AquatiquesLarval lampreys were sampled in a small river using a new method modified from the Surber bottom sampler for invertebrates. This method uses a rectangular dredge to sample a constant and small surface of sediments in soft substrate areas. It was compared to a classical point abundance sampling by electrofishing. Both methods generated large numbers of small samples encompassing the spatial heterogeneity of ammocoete distributions. However, the bottom sampler provided samples with higher abundance and was more efficient for small individuals. Furthermore, the equipment is cheap and the method is cost-effective, since it can be operated by only two people. It could therefore be applied at a large scale to collect information on lamprey populations and contribute to knowledge of their distribution, abundance and, in fine, to devise better conservation measures. (C

l'histoire d'un siècle de croissance d'anguille

International audienceA cooperative effort lead to the collection of a large European length-at-age dataset (N = 43993, 15 countries) for eel, covering almost one century (from 1913 to 2006) and the fitting of a global growth model at the scale of the species distribution area (Lat. 36-61 Long. 10W-27E). The whole dataset was randomly divided into a calibration dataset (two third) and a validation dataset (one third). A Generalized Additive Model was designed to predict eel length as a function of age. A procedure of model selection was applied to select the best predictors among sex, age of the fish, protocol of age estimation, temperature parameters (means, minimums, maximums, cumulated temperatures), habitat parameters (depth, tide, salinity, distance to the sea) and the period of the century. The model predicted eel length with a good accuracy. Sex and habitat had the greatest predictive power in the model, before cumulated temperature and protocol. Growth was faster in habitats close to the sea and in deep habitats. Within the range tested, temperature had a positive effect on eel growth. The investigation of the effect of the period of the century revealed an interesting pattern with an eel growth increase during the 1960-1980 period