Morphological and immunohistochemical study of the midgut and fat body of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: noctuidae) treated with essential oils of the genus Piper

ABSTRACT

Essential oils are a promising alternative to insecticides. We investigated the LD₅₀ of oils extracted from Piper corcovadensis, P. marginatum, and P. arboreum after 48 h topical contact with Spodoptera frugiperda larvae using morphometry, histochemistry and immunohistochemistry of the midgut and fat body. Chromatography revealed that E-caryophyllene was the principal compound common to the Piper species. The essential oils of P. corcovadensis, P. marginatum and P. arboreum caused deleterious changes in the midgut of S. frugiperda larvae. P. corcovadensis oil produced the lowest LD₅₀ and significant histopathological alterations including elongation of the columnar cells, formation of cytoplasmic protrusions, reduction in carbohydrate, increased apoptotic index and decreased cell proliferation. P. arboreum oil caused histopathological alterations similar to P. corcovadensis, but caused the highest rate of cell proliferation and increased regenerative cells, which indicated rapid regeneration of the epithelium. Our findings demonstrated the insecticidal potential of P. corcovadensis for control of S. frugiperda owing to the significant damage it inflicted on S. frugiperda midgut.     

Diet and histophysiology of the alimentary canal of Lumbricillus lineatus (Oligochaeta,Enchytraeidae)

Lumbricillus lineatus selectively ingests masses of organic and inorganic interstitial particles from a sand-clay substratum in the upper littoral zone. Particle-masses are ingested, passed along the esophagus and into the anterior intestine where the pH becomes acid. A- and C-esterases, acid -galactosidase, acid phosphatase and -N-acetylglucosaminidase are present in the epithelium, while the rotating food masses are surrounded by a membrane of sulphated, acid glycoprotein. These enzymes, with the exception of acid phosphatase and the addition of aminopeptidase M, are also present in the epithelia of the mid and posterior intestinal regions where the pH is alkaline. The cells in the ventral wall of the mid intestinal region contain high concentrations of alkaline phosphatase, acid -galactosidase and -N-acetylglucosaminidase. The food consists of absorbed organics and bacteria with absorption and intracellular digestion occurring along the intestine, particularly in the mid ventral region.     

Neurotransplantation of the Biological Clock in Mammals,Importance and Perspectives

The tool of neurotransplantation has been successfully introduced in the chronobiology of mammals. Grafting of the foetal suprachiasmatic nucleus (SCN) in the IIIrd ventricle of the brain of SCN-lesioned arhythmic rodents restored free-running circadian activity patterns. This ultimately proves the SCN to be the central circadian pacemaker system. However, recovery is not seen in all animals with a surviving SCN implant and the rhythm is usually not as robust as seen for the intact system. Moreover, the grafted foetal SCN has a partially deviant development, whereas the structure-function relationship after restoration of circadian rhythm was reported to differ in the various studies. This has led to two possible mechanisms of graft action: the one a circadian humoral signal diffusing into the SCN-lesioned host brain, and the other a neuritic afferent outgrowth into the brain. There is, moreover, doubt about the integration of the ‘new’ SCN in terms of afferent input. Given the fact that the in situ SCN has an extensive efferent and afferent system in the intact brain, the SCN grafting experiments seem to indicate that only limited aspects of the SCN can drive circadian physiological rhythms. However, on the basis of current knowledge on grafting results the present paper recommends performing more sophisticated SCN grafting experiments to contribute to the knowledge on the SCN clock system.     

Identification des cellules hypophysaires sécrétant l'ACTH chez le rat

Résumé Dans le but d'identifier la cellule hypophysaire responsable de la sécrétion d'ACTH chez le rat, des études morphologiques, en microscopie optique et électronique, furent entreprises chez des animaux surrénalectomisés, c'est-à-dire dans des conditions où la sécrétion d'ACTH est spécifiquement augmentée. Le prélèvement des hypophyses fut effectué à des intervalles allant de 1 à 21 jours après surrénalectomie. Des hypophyses d'animaux surrénalectomisés et traités par la dexaméthasone, un inhibiteur de la secrétion d'ACTH, furent également étudiées. Il découle de ces expériences qu'un type cellulaire est stimulé en même temps que la sécrétion d'ACTH augmente. Cette cellule, hypertrophiée après surrénalectomie, possède une forme irrégulière et est très souvent en contact avec les cellules somatotropes; son ergastoplasme peu développé contraste avec un appareil de Golgi très important. Les granules secrétoires corticotropes ont un diamètre d'environ 200 m, sont peu abondants et disposés le long de la membrane cellulaire. Ces granules n'ont cependant pas été caractérisés en microscopie optique. L'administration de dexaméthasone provoque une régression spécifique de la cellule corticotrope ainsi qu'une accumulation des granules sécrétoires dans le cytoplasme. Chez l'animal intact, il devient possible d'identifier la cellule corticotrope qui possède les caractéristiques générales de la cellule stimulée, mais dont le cytoplasme et l'appareil de Golgi sont peu importants.

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Identification of the ACTH secreting cells in the rat pituitary

Summary In order to clarify the identity of the ACTH-secreting cells in the rat pituitary, morphological studies were performed in adrenalectomized rats which have a specific increase in ACTH secretion. Pituitaries were removed and fixed for both light and electron microscopy at different time intervals (1 to 21 days) after adrenalectomy. Pituitaries of adrenalectomized animals which received dexamethasone, a potent inhibitor of ACTH secretion, were also studied. In these experiments, it was found that a specific cell type was stimulated as ACTH secretion was increased. This cell, which became enlarged after adrenalectomy, is characterized by an irregular shape and frequent association with somatotropic cells. The rough endoplasmic reticulum was poorly developed in contrast to a prominent Golgi apparatus. The secretory granules of this corticotropic cell were about 200 m in diameter and located in a single row along the plasma membrane. By light microscopic examination, these secretory granules could not be clearly identified. Dexamethasone administration provoked a specific decrease in size of corticotrophic cells, as well as an accumulation of secretory granules. Identification of corticotrophic cells in control rats was facilitated by comparison with those of adrenalectomized rats. In both cases, the general appearance of this cell type was similar except for size difference. Also in the control animals the Golgi apparatus was less prominent than in adrenalectomized rats.

Boursier du Conseil de la Recherche Médicale du Québec.     

Response of blood glucose,hepatic glycogen and pancreatic islets to treatment of sulphydryl inhibitors inClarias batrachus L.

The correlative effects of the two sulphydryl inhibitors viz., the mono-and dithiol reagent, alloxan and cobalt chloride, were studied in the fresh water air breathing catfish,Clarias batrachus. Alloxan induced a typical mammalian-like triphasic response and necrobiotic changes in the islet Β-cells. Cobalt chloride elicited a discontinuous hyperglycemia with cytopathological changes in Β-cells following nearly the same sequence as those induced by alloxan. However, the α-cells of cobalt-treated fish showed, unlike those after alloxanization, specific degranulation, vacuolization and nuclear enlargement. The changes in the hepatic glycogen content of two experimental groups were observed to be equal. Both the drugs appeared to be detrimental to the normal islet function and were, thus, overtly or potentially diabetogenic agents to the fish. Part of this paper was presented at the Second Congress of the Federation of Asian and Oceanian Biochemists and the Golden Jubilee meeting of the Society of Biological Chemists (India), Bangalore, 14–18 Dec, 1980.     

Histophysiology of digestion and observations on the structure of the alimentary canal in the ectosymbiont Chaetogaster limnaei limnaei Baer, 1827 (Annelida: Oligochaeta)

The naidid oligochaete Chaetogaster limnaei limnaei has an alimentary canal consisting of a mouth, pharynx with a dorsal pharyngeal pad, esophagus, stomach, anterior and posterior intestine, and anus. The diet is omnivorous but limited by particle size. Unattached food organisms are sucked into the pharynx while sessile organisms are plucked from the substratum. Granules of acid mucosubstances that stain purple with neutral red are secreted into the stomach lumen after food enters, rapidly increasing the acidity from pH 3 to 1.5. Acid induced lysis of the organisms initiates autolysis before the food is passed into the alkaline, pH 7 to 8, anterior intestine. Ciliated intestinal cells showed arylamidase, acid phosphatase and C-esterase active granules indicating primary lysosomes with secondary lysosomes being recognized in electron micrographs suggesting intracellular digestion. Arylamidase and alkaline phosphatase activity appears in the intestinal margins during the alkaline phase of digestion. Scattered, pyramidal cells found only in the anterior intestine contain yellow refractile spheres. The spheres stain alcian blue pH 2.5 and bromophenol blue positive and exhibit a strong acid phosphatase activity all the time with A-esterase active granules surrounding them. Glycogen and lipids are stored mainly in the chlorogague cells. Many of the yellow refractile granules in the stomach and intestinal cells are bacteria.