Simbiontes do trato digestivo de formigas (Hymenoptera : Formicidae)
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Data
2009-11-30
Autores
Bution, Murillo Lino [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Foram realizados estudos comparados do proventrículo, ventrículo, íleo e túbulos de Malpighi de três espécies pertencentes ao gênero Cephalotes: C. atratus, C. pusillus e C. clypeatus, objetivando buscar relações entre elas, assim como, diferenças histoquímicas e ultra-estruturais tanto da parede como do conteúdo destas porções do trato digestivo, que pudessem ser utilizadas para a melhor compreensão da função intestinal, bem como esclarecer quais e como os recursos alimentares são aproveitados em cada parte do trato digestivo. As características ultra-estruturais do ventrículo de Cephalotes atratus, C. clypeatus e C. pusillus, mostram que o epitélio do ventrículo repousa sobre uma lâmina basal contínua e é formado basicamente por três tipos celulares, sendo estas as células digestivas, as células regenerativas e as goblet cells. Nestas formigas, o retículo endoplasmático rugoso além de atuar na produção de enzimas digestivas também está envolvido na estocagem de íons em vacúolos especializados presentes no ventrículo. Estas concreções são os esferocristais e podem estar contribuindo com a estabilização do pH e permanência das bactérias simbiontes presentes por entre as microvilosidades. Secções realizadas ao longo do íleo revelaram diferenças entre três principais regiões: proximal, mediana e distal. As especializações estruturais presentes no íleo destas três espécies de formigas resultam em implicações especialmente relacionadas com as bactérias simbiontes aí hospedadas. Também foram realizados testes para verificar a diversidade da microbiota intestinal das porções em questão, usando a técnica DGGE. Assim sendo, o perfil molecular dos simbiontes do ventrículo e íleo de Cephalotes atratus, C. clypeatus e C. pusillus foi obtido analisando a região variável V3 do gene 16S do rDNA bacteriano...
This study compared the proventriculus midgut, ileum, and Malpighian tubules of three ants of the genus Cephalotes: C. atratus, C. pusillus, and C. clypeatus, by examining histochemical and ultrastructural differences in the wall and the content of these portions that could be used to better understand the intestinal function, as well as clarify which and how food resources are used in each part of the digestive tract. The ultrastructural analysis of the midgut of Cephalotes atratus, C. clypeatus, and C. pusillus reveled that the epithelium of the midgut lays on a basal lamina and is composed basically of three cell types: digestive cells, generative cells, and goblet cells. In these ants, the rough endoplasmic reticulum, in addition to producing digestive enzymes, is involved in ion storage in specialized vacuoles present in the midgut. These concretions are spherocrystals and may contribute to stabilize the pH and to maintain symbiotic bacteria found in between microvilli. Sections along the ileum revealed differences among the three main regions: proximal, medial, and distal. The structural specializations present in the ileum of these three ants have implications especially to the symbiotic bacteria. The DGGE method was also performed to assess the diversity of the intestinal microbiota of the portions of the digestive tract. The molecular profile of the symbionts of the midgut and ileum of Cephalotes atratus, C. clypeatus, and C. pusillus was obtained using the variable region V3 of the bacterial 16S rDNA gene sequence. Two samples of C. atratus, three of C. clypeatus, and six of C. pusillus were analyzed. The results showed similarity indices from 80% to 94% between the samples of symbionts from C. atratus and C. clypeatus, despite being collected in sites geographically distant. The variability of symbionts found in the samples of C. pusillus ranged from 45%... (Complete abstract click electronic access below)
This study compared the proventriculus midgut, ileum, and Malpighian tubules of three ants of the genus Cephalotes: C. atratus, C. pusillus, and C. clypeatus, by examining histochemical and ultrastructural differences in the wall and the content of these portions that could be used to better understand the intestinal function, as well as clarify which and how food resources are used in each part of the digestive tract. The ultrastructural analysis of the midgut of Cephalotes atratus, C. clypeatus, and C. pusillus reveled that the epithelium of the midgut lays on a basal lamina and is composed basically of three cell types: digestive cells, generative cells, and goblet cells. In these ants, the rough endoplasmic reticulum, in addition to producing digestive enzymes, is involved in ion storage in specialized vacuoles present in the midgut. These concretions are spherocrystals and may contribute to stabilize the pH and to maintain symbiotic bacteria found in between microvilli. Sections along the ileum revealed differences among the three main regions: proximal, medial, and distal. The structural specializations present in the ileum of these three ants have implications especially to the symbiotic bacteria. The DGGE method was also performed to assess the diversity of the intestinal microbiota of the portions of the digestive tract. The molecular profile of the symbionts of the midgut and ileum of Cephalotes atratus, C. clypeatus, and C. pusillus was obtained using the variable region V3 of the bacterial 16S rDNA gene sequence. Two samples of C. atratus, three of C. clypeatus, and six of C. pusillus were analyzed. The results showed similarity indices from 80% to 94% between the samples of symbionts from C. atratus and C. clypeatus, despite being collected in sites geographically distant. The variability of symbionts found in the samples of C. pusillus ranged from 45%... (Complete abstract click electronic access below)
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Palavras-chave
Formiga, Ultraestrutura (Biologia), Histoquimica, Ultra-morfologia, Enzimologia, Ant
Como citar
BUTION, Murillo Lino. Simbiontes do trato digestivo de formigas (Hymenoptera : Formicidae). 2009. 97 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Biociências de Rio Claro, 2009.