The distribution of agglutinins and lytic activity against Trypanosoma rangeli and erythrocytes in Rhodnius prolixus and Triatoma infestans tissue extracts and haemolymph

Haemolymph, heads, salivary glands, crops, midguts, hindguts, and Malpighian tubules from Rhodnius prolixus and Triatoma infestans were extracted in phosphate or Tris buffer saline with calcium, and tested for agglutination and lytic activities by microtitration against both vertebrateerythrocytes and cultured epimatigote forms of Trypanosoma rangeli. Haemagglutination activity against rabbit erythrocytes was found in the crop, midgut and hindgut extracts of T. infestans but only in the haemolymph of R. prolixus. Higher titres of parasite agglutinins were found in R. prolixus haemolymph than T. infestans, whilst the converse occurred for the tissue extracts. In addition, the extracts of T. infestans salivary glands, but not those of R. prolixus, showed a trypanolytic activity that was heat-inactivated and was not abolished by pre-incubation with any of the sugars or glycoproteins tested. T. infestans, which is refractory to infection by T. rangeli, thus appears to contain a much wider distribution of agglutinating and trypanolytic factors in its tissues than the more susceptible species, R. prolixus

Ultramorphology of digestive tract of Anticarsia gemmatalis (Hubner, 1818) (Lepidoptera : Noctuidae) at final larval development

The digestive tract of insects is an important natural, physical, and chemical defense barrier against pathogen invasion. Certain. lepidopteran caterpillars are serious pests of agricultural crops and their biology has received much attention, but little is known about the larval noctuid gut. The morphological analysis of the digestive tract in Anticarsia gemmatalis under scanning electron microscopy (SEM) is a good model for studies about its defense mechanism. The material was fixed (2,5% glutaraldehyde solution; 0.1 M-phosphate buffer, pH 7.3), post-fixed (1% osmium tetroxide in the same buffer), dried at critical point, gold coated and analyzed in a SEM 515-Philips. A. gemmatalis digestive tract consists of a straight duct of varying length and diameter, subdivided in three main regions: the foregut formed by the oral cavity, pharynx, esophagus, and crop; the midgut that is the largest portion of the digestive tract without noticeable morphological differentiation along its length; and the hindgut that is morphologically differentiated in pylorus, ileum, colon, and rectum. Although the general morphology of the A. gemmatalis digestive tract is quite similar to the other Lepidoptera species, the anatomical array of the crop muscular layers is quite different comparing with the description for other larval insect.

Ultrastructural features of the regenerative cells of the bees (Hymenoptera, Apidae) midguts

The epithelium of the bee ventriculus is formed by two cell types: the principal or digestive cells and the regenerative cells. In this article the ultrastructure of the regenerative cells is described, as well as the features of their differentiation into digestive cells during epithelium renewal.

First report of endocytobionts in the digestive tract of ponerine ants

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ultra-structure and histochemistry of digestive cells of Podisus nigrispinus (Hemiptera: Pentatomidae) fed with prey reared on bt-cotton

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Histology and Histochemistry of the Stomach Epithelium of Pachycondyla (= Neoponera) villosa (Formicidae: Ponerinae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Molecular and ultrastructural profiles of the symbionts in Cephalotes ants

The molecular and ultrastructural profiles of the symbionts found in the midgut and ileum of Cephalotes atratus, Cephalotes clypeatus, and Cephalotes pusillus were determined using the V3 region of the bacterial 16S rDNA gene and transmission electron microscopy (T.E.M.). Two samples of C atratus, three of C clypeatus, and six of C. pusillus were analyzed. The coefficients of similarity ranged from 80% to 94% for the samples of symbionts from C. clypeatus and C. atratus, despite being collected in geographically distant sites. The variability within symbionts found in the samples of C. pusillus varied from 29% to 55%, in samples geographically close as well as distant. PCR-DGGE was effective for the purpose of this study and can be considered a versatile tool to analyze gut microbiota. Details of the ultrastructural aspect of these bacteria are presented. (C) 2010 Elsevier Ltd. All rights reserved.

Aspectos da ultra-estrutura dos cecos gástricos da larva de Odontosciara sp. (Diptera: Sciaridae)

Ultrastructural features of the gastric caeca of Odontosciara sp. are reported. The species has 4 lateral caeca connected with the anterior midgut at the level of the foregut junction. The epithelial cell features indicate protein synthesis, digested material absorption from the lumen and haemolymph material absorption. Those functions, however, do not seem to be very intense.

Post-embrionic development of the digestive tube of Dermatobia hominis (Linnaeus) (Diptera, Cuterebridae)

The digestive tube of 2nd and 3rd instar larvae, pupae and newly emerged adults of Dermatobia hominis (Linnaeus, 1781) was studied anatomically. The specimens were dissected in buffer saline under a stereomicroscope, and the digestive tubes were placed on slides and fixed in 10% buffered formalin. Each tube was measured using a micrometric eye piece, and drawings were made with camera lucida. The results showed that the midgut, the hindgut and the Malpighian tubules with their ducts grow gradually during the larval development. The oesophagus and the salivary glands with their ducts grow only during the moult from the 2nd to the 3rd instar. In the pupal period, salivary glands grow gradually but disappeared after the 20th day. After metamorphosis the digestive tube regressed. This is expected since adult D. hominis lives about nine days without feeding. This fly, similar to other calyptratae muscoid flies shows no vestige of a crop during all post-embrionic development, and the adult has no salivary glands.

Desenvolvimento pós-embrionário do intestino anterior de Dermatobia hominis (Linnaeus Jr.) (Diptera, Cuterebridae)

Foregut in D. hominis (Linnaeus Jr., 1781) as the majority of the larval Diptera somatic tissue, is made up of polytenic cells, and grows at the expenses of the polytenization of its nuclei followed by the increase in size of each cell. The oesophagus, of ectodermic origem, is interiorly covered by a chitinous squamous epithelium that rests upon a very thin basal lamina. This sheet is surrounded by thick muscle bundles. The oesophagus intussuscepts the midgut forming the cardia. The cardia, with three epithelial layers: two internal ones, of ectodermal origin and one external of endodermic origin. At the anterior portion of the cardia, between these two types of epithelium, there is a cluster of small, non polytenic cells, forming the imaginal disk of the foregut. Metamoiphosis begins at the end of the larval period with signs of nuclear degeneration of all the polytenic cells, as well as the increase in number of the imaginal disk ones. The oesophagic portion intussuscepted into the cardia, everts; its cells suffer apoptosis and are replaced by the new cells growing from the imaginal disk. The external layer cells also degenerate and are pinched off into the lumen of the very anterior portion of the midgut. The newly formed oesophagus intussuscepts de novo to form the two internal layers of the adult cardia. At the same time the midgut regenerative cells grow anteriorly to form the new external layer of the adult cardia.

Desenvolvimento pós-embrionário do intestino médio de Dermatobia hominis (Linnaeus Jr.) (Diptera, Cuterebridae)

Dermatobia hominis (Linnaeus, 1781) midgut is internally lined by an epithelium of polytenic cells, some low others prismatic with well developed brush border. Their apical portion are enlarged by secretory vesicles, forming button-like structures that are pinched off to the lumen, some accompained by the nucleus characterizing apocrine and holocrine secretions. This epithelium is gradually renewed by small, non polytenic regenerative cells, found scattered at its basal portion. At the end of the third instar the metamorphosis begins. The epithelial cells present signs of degeneration and at the first day of pupation the regenerative cells increase in number. By the 5th day of pupation these regenerative cells, besides being increased in number, differentiate themselves into two layers: one similar to the dense conective tissue that sustainning the larval epithelium is pinched off to the midgut lumen forming the yellow bodies; the other, develops right under it as the imaginal epitelium. The disorganized muscles bundles of the midgut wall, are invaded by phagocytes. At the end of pupation the midgut has a low prismatic epithelium with brush-border. In the adult, the torax portion of the midgut has prismatic homogeneously basophilic epithelium while in the abdominal portion the epithelium is made of high prismatic cells full of small vacuoles. The larval midgut epithelium suffers programmed cell death non compatible with apoptose. During the metamorphosis the midgut lenght diminishes from 31mm in the larva to 14mm in the adult.

Cytoplasmic protrusions from digestive cells of bees

Midgut cells from the honey bee, Apis mellifera, and the stingless bees Scaptotrigona postica and Melipona quadrifasciata anthidioides were examined ultrastructurally and histochemically. Several types of protrusions were evident in the apical surface of the midgut cells. Large apical protrusions formed by the whole apical surface of the cell, whose content had a homogeneous cytoplasmic matrix devoid of organelles and with a different electron density from the subjacent cytoplasm. These protrusions can be cast out to the midgut lumen. A second type of large apical protrusion was produced between the cell microvilli, presenting many ribosomes and polyribosomes. In addition to these large protrusions two other kinds of small ones were observed. One type crowned the cell apex forming small spheres with irregular contours near the cells, and increasing in size further away. The other type was characterized by the microvilli swelling with an electron-lucent content. The Gomori acid phosphatase reaction was positive at the cell apex, in the pinched off protrusions and in the microvilli. These results are discussed in relation to the possible role of cell protrusions in secretory mechanisms.

Ultrastructure of digestive cells in stingless bees of various ages (Hymenoptera, Apidae, Meliponinae)

The ultrastructure of digestive cells of newly emerged, nurse and forager worker bees is described. Newly emerged bees have the endoplasmic reticulum characteristically in whorls and stacks as well as in parallel arrays of smooth endoplasmic reticulum. Nurse bees have spherits, autophagic vacuoles, lysosomes and multivesicular bodies. Forager bees have many cells with disorganized cytoplasm containing vacuoles, lamellated bodies, lipid inclusions, microbodies and intranuclear crystalloid inclusions. The basal cell region stays essentially unchanged. The changes observed are discussed in relation to previous observations on other insect species.

Tracing heme in a living cell: hemoglobin degradation and heme traffic in digest cells of the cattle tick Boophilus microplus

Heme is present in all cells, acting as a cofactor in essential metabolic pathways such as respiration and photosynthesis. Moreover, both heme and its degradation products, CO, iron and biliverdin, have been ascribed important signaling roles. However, limited knowledge is available on the intracellular pathways involved in the flux of heme between different cell compartments. The cattle tick Boophilus microplus ingests 100 times its own mass in blood. The digest cells of the midgut endocytose blood components and huge amounts of heme are released during hemoglobin digestion. Most of this heme is detoxified by accumulation into a specialized organelle, the hemosome.We followed the fate of hemoglobin and albumin in primary cultures of digest cells by incubation with hemoglobin and albumin labeled with rhodamine. Uptake of hemoglobin by digest cells was inhibited by unlabeled globin, suggesting the presence of receptor-mediated endocytosis. After endocytosis, hemoglobin was observed inside large digestive vesicles. Albumin was exclusively associated with a population of small acidic vesicles, and an excess of unlabeled albumin did not inhibit its uptake. The intracellular pathway of the heme moiety of hemoglobin was specifically monitored using Palladium-mesoporphyrin IX (Pd-mP) as a fluorescent heme analog. When pulse and chase experiments were performed using digest cells incubated with Pd-mP bound to globin (Pd-mP-globin), strong yellow fluorescence was found in large digestive vesicles 4 h after the pulse. By 8 h, the emission of Pd-mP was red-shifted and more evident in the cytoplasm, and at 12 h most of the fluorescence was concentrated inside the hemosomes and had turned green. After 48 h, the Pd-mP signal was exclusively found in hemosomes. In methanol, Pd-mP showed maximal emission at 550 nm, exhibiting a red-shift to 665 nm when bound to proteins in vitro.The red emission in the cytosol and at the boundary of hemosomes suggests the presence of heme-binding proteins, probably involved in transport of heme to the hemosome. The existence of an intracellular heme shuttle from the digestive vesicle to the hemosome acting as a detoxification mechanism should be regarded as a major adaptation of ticks to a blood-feeding way of life. To our knowledge, this is the first direct observation of intracellular transport of heme in a living eukaryotic cell. A similar approach, using Pd-mP fluorescence, could be applied to study heme intracellular metabolism in other cell types.

Demographic of short gut syndrome: Increasing demand is not followed by referral of potential candidates for small bowel transplantation

Background. Despite improvements in small bowel transplantation (SBTx), early referral of patients with irreversible intestinal failure (IF) remains a major obstacle. In this study we evaluated the demand for SBTx among seven surgical pediatric centers located at least 200 km from our center.Methods. From 1997 to 2001, 640 patients have been treated for neonatal diseases, including 248 who underwent a minor or major intestinal resection. Twenty-four patients with major resections presented with short gut syndrome, requiring total parenteral nutrition (TPN). The greatest demand was in postsurgical neonates with necrotizing enterocolitis, gastroschiesis, onphalocoeles, or midgut volvulus, and in three adults with postradiotherapy arteritis (n = 2) and mesenteric vein thromboses (n = 1). The median length of residual bowel after resection was 20 to 30 cm, without an ileocecal valve. Four patients were referred for SBTx evaluation; three died while awaiting a donor; 20 were not referred, among whom 14 died of TPN complications.Results. Approximately 62 children per year require nutritional support for IF, most of whom develop complications related to TPN. Because many patients who are TPN-dependent develop complications, we believe that early referral would reduce mortality.Conclusions. Greater medical awareness about the feasibility of SBTx procedures and earlier referral may improve results and quality of life after transplant.