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Feeding behavior is a complex process that depends on the ability of the brain to integrate hormonal and nutritional signals, such as glucose. One glucosensing mechanism relies on the glucose transporter 2 (GLUT2) in the hypothalamus, especially in radial glia-like cells called tanycytes. Here, we analyzed whether a GLUT2-dependent glucosensing mechanism is required for the normal regulation of feeding behavior in GFAP-positive tanycytes. Genetic inactivation of Glut2 in GFAP-expressing tanycytes was performed using Cre/Lox technology. The efficiency of GFAP-tanycyte targeting was analyzed in the anteroposterior and dorsoventral axes by evaluating GFP fluorescence. Feeding behavior, hormonal levels, neuronal activity using c-Fos, and neuropeptide expression were also analyzed in the fasting-to-refeeding transition. In basal conditions, Glut2-inactivated mice had normal food intake and meal patterns. Implementation of a preceeding fasting period led to decreased total food intake and a delay in meal initiation during refeeding. Additionally, Glut2 inactivation increased the number of c-Fos-positive cells in the ventromedial nucleus in response to fasting and a deregulation of Pomc expression in the fasting-to-refeeding transition. Thus, a GLUT2-dependent glucose-sensing mechanism in GFAP-tanycytes is required to control food consumption and promote meal initiation after a fasting period.

Genetic differences between strains of a baculovirus are often limited to some restriction sites, short DNA deletions or absence of some nonessential genes. The recently coined bro gene family, represents a new major source of intraspecific variability. A comparison between two bro gene sets of Bombyx mori nucleopolyhedroviruses (NPV) shows that bro genes are distributed in three regions for the -T3 and -SC7 virus strains. In BmNPV T3, five bro genes are distributed in three genome locations, whereas the BmNPV SC7 strain possess a single bro copy in each region. In addition, each of the BmNPV SC7 bro genes belongs to one of the three subfamilies present in BmNPV T3. Analysis of bro copy sequences and of adjacent sequences suggests an active redistribution of sequences due to intraspecific recombination. The maintenance of one allele of each subfamily suggests that they play different roles in the viral cycle, and that they are essential.

The nucleotide sequence of two cloned restriction fragments encompassing the granulin genes from the granuloviruses of the potato tuber moth, Phthorimaea operculella, PhopGV, and the Egyptian cotton leaf worm, Spodoptera littoralis, SpliGV, have been determined. Although both viruses are able to infect the same Ph. operculella cell line, their granulins do not cluster in the same phylogenetic branches. PhopGV ganulin is closely related to Cydia pomonella GV (CpGV) and Cryptophlebia leucotreta GV (ClGV) (95.2 and 94% identity at the aminoacid level), while SpliGV granulin falls close to Trichoplusia ni GV and Xestia c-nigrum GV (91.6 and 92.0% respectively). The gene organization around the granulins reflects this clustering. Upstream the PhopGV granulin, an ORF belonging to the ME53 gene family (as ORF 124R of CpGV and 909 of ClGV) is present, while no equivalent ORF is found in this region in SpliGV. Downstream the granulin, both viruses present a gene homologous to the Autographa californica nucleopolyhedrovirus (AcMNPV) ORF 9 followed by a Protein Kinase (AcMNPV ORF10). The structure of this region seems thus conserved not only among nucleopolyhedroviruses but also in at least some granuloviruses.

A cell line from the main insect pest of potatoes in tropical and subtropical areas, Phthorimaea operculella (Zeller), was obtained from embryoculture. These cells were cultured in Grace's modified medium. The cell line, designated ORS-Pop-93, had a heterogeneous population consisting of spherical and spindle cells with great capacity to adhere and a doubling time of 40 h. They were subcultured for more than 60 passages. Their polypeptidic profile was different from profiles of other lepidopteran cell lines. The cell line supports the multiplication of the Autographa californica nuclear polyhedrosis virus.

Sequence studies of the N-terminal halves of the lysozymes isolated from Bombyx mori, Gallera mellonella and Spodoptera littoralis (Lepidoptera) allow us to classify these enzymes among the c (chicken) type lysozymes.

Trois isolats de polyedres nucleaires deSpodoptera littoralisBoisduval (isolats Egypte, Maroc et Lyon) sont compares entre eux et avec des preparations de polyedres nucleaires des lepidopteresBombyx mori L.,Galleria mellonella L.,Lymantria dispar L. etAutographa californicaSpeyer. L'analyse porte a la fois sur la composition peptidique des virions, sur le poids moleclaire des proteines des polyedres et sur les parentes antigeniques entre ces proteines.

Le poids moleculaire de la proteine constituant la trame des corps d'inclusion des Baculovirus a ete estime pour 33 virus affectant trois ordres differents d'Insectes. Ce poids varie entre 25.100 et 31.360 daltons.

L’introduction de corps etrangers dans les larves de lepidopteres entraine une augmentation parfois considerable du taux de lysozyme dans l’hemolymphe. L’efficacite inductrice de diverses substances varie dans de larges mesures. L’action de l’Actinomycine D et de la Cycloheximide sur la production du lysozyme induit a ete recherchee chez des larves deGalleria mellonella L. recevant un stimulus peu specifique (chlorure de sodium) ou plus specifique (Micrococcus luteus vivants). L’action de ces inhibiteurs sur la quantite de lysozyme presente dans l’hemolymphe 24 h apres induction, indique que les variations du taux de l’enzyme sont sous le controle d’un mecanisme unique independant de la specificite des stimuli inducteurs. L’augmentation du taux de lysozyme chez les larves deG. mellonella induites, fait suite a une synthese proteique et non a la liberation d’enzyme preforme.

Une polyedrose nucleaire de la tordeuse de la pelure,Pandemis heparanaDenis & Schiffermuller (Lep.: Tortricidae) due a un baculovirus isole dans un verger de pommiers en France est etudiee. Le baculovirus, uniquement actif sur les larves nouvelles nees, induit un arret de developpement des larves au stade L3 et une mortalite ulterieue des larves aux stades L5 et L6. L'etude en microscopie optique et en microscopie electronique des larves L5 et L6 presentant des symptomes tres prononces de la viroise (debut de paralysie et couleur blanchâtre des segments abdominaux) montre que c'est essentiellement le tissu adipeux et accessoirement certains hemocytes et quelques cellules de l'hypoderme qui sont le siege de la multiplication virale. La morphogenese virale dans les cellules du tissu adipeux est decrite en detail. Certains aspects de l'etude ultrastructurale lies a la forme en massue des virions, au processus de cristallisation des polyedres et a l'accumulation de masses fibrillaires viro-induites sont discutes.

L'etude des proteines des granules dePieris brassicae L. et des polyedres nucleaires deBombyx mori L. par les techniques de filtration sur gel, d'electrophorese et d'immunodiffusion revele de nombreuses ressemblances. La comparaison des proteines des corps d'inclusion engendres par lesBaculovirus des Lepidopteres contribue a montrer l'homogeneite de ce groupe.

Trois Baculovirus isoles de larves deSpodoptera littoralis atteintes de polyedroses nucleaires au Maroc, en Egypte et dans un elevage a Lyon ont ete compares par analyse de leurs genomes avec des enzymes de restriction. Les variants genetiques contenus dans les populations virales sont obtenus apres isolement de clones en culture cellulaire. Sur 27 clones analyses par les endonucleases on observe 11 variants avecEco RI, 3 variants avecBam HI et avecSac I et un type unique avecHin dIII. Les 3 virus Maroc, Egypte et Lyon sont differents, mais appartiennent a l'espece B definie parCherry & Summers (1985).

Guidelines for testing the safety of insect viruses for use as insecticides have been formulated in the light of the recent decade's experience and accumulation of knowledge. In the familyBaculoviridae, the nuclear polyhedrosis and granulosis viruses of Lepidoptera and sawflies (Hymenoptera) are a particularly homogeneous group which have been tested very extensively, without any evidence of hazard to man and vertebrates. It is considered, therefore, that data for viruses already tested can be used as evidence for the safety of a new virus in this group, so that only a limited series of mandatory tests are necessary on the new virus product itself. Other viruses may require the full range of tests, which include data on the identification of the virus; nature of the formulation; biological properties; manufacture; quality control; application; efficacy; residues; infectivity, toxicity and allergenicity in mammals (involving short, intermediate and long term application to various mammalian species by a variety of routes, and observation of humans who have handled the virus) and on wildlife (bees, important predators and parasites of target species, earthworms, fish and birds). It is recommended that additional non-mandatory research should be undertaken on subjects such as the behaviour of the viral genome, improved methods of identifying viruses and of testing safety.

Les consequences possibles sur le profil des motifs de recherches afferents auxBaculovirus sont evoquees, en faisant etat de la mise en evidence et de la caracterisation deBaculovirus dans des ordres d'insectes non encore concernes, notamment les homopteres ainsi que chez les arachnides et les crustaces. En dehors de l'accroissement d'interet en virologie comparee a cause de la diversification des types, sont soulignes: la possibilite de l'extension de l'application de la lutte virologique a des ravageurs non encore concernes et a des insectes vecteurs, l'etude de la coexistence de virus transmis avec des infections virales propres aux vecteurs, les nouvelles precautions a prendre en matiere d'innocuite et de diagnostic et l'evolution de l'importance economique en epizootiologie des invertebres utiles en milieu marin.

L’etude immunochimique des corps d’inclusion formes par lesBaculovirus de Lepidopteres est entreprise en vue de differencier ces viroses. Le travail relate decrit l’influence de differents solutes sur l’extraction des proteines des granules de la granulose dePieris brassicae. L’interet de l’emploi d’agents reducteurs tels que l’acide thioglycolique ou le mercaptoethanol pour la solubilisation des granules est mis en evidence.

Les relations antigeniques entre einq rickettsies pathogenes aux Invertebres sont etudiees par agglutination.

Le virus de la densonucleose est thermoresistant. Il n'est pas inactive apres traitement avec des solvants de lipides. Aucun pouvoir hemagglutinant n'a ete mis en evidence avec des erythrocytes d'especes variees. Ces proprietes sont comparees a celles desParvovirus.

The haemolymph proteinogram ofGalleria mellonella larvae in the L3 stage is formed by 8 or 9 zones according to the larvae. The relative importance of various proteins shows only some slight individual differences. However, 3 distinct types of proteinogram relating to the presence or absence of near zones 3 R and 3L are noted. The genetic analysis shows that these 3 phenotypes are induced by 2 codominant autosomal allelic genes. This work reveals the occurrence of blood groups in an experimental strain of Lepidoptera.