de Sousa Géssica, Dos Santos Vânia Cristina, de Figueiredo Gontijo Nelder, Constantino Reginaldo, de Oliveira Paiva E Silva Gabriela, Bahia Ana Cristina, Gomes Fabio Mendonça, de Alcantara Machado Ednildo
Laboratório de Bioquímica de Insetos e Parasitos (Labip), Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Cidade Universitária, Prédio do CCS, Bloco D, Sala 13, Rio de Janeiro, RJ, Brazil, 21941-590.
Laboratório de Fisiologia de Insetos Hematófagos, Departamento de Parasitologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
Cell Tissue Res. 2017 Jun;368(3):579-590. doi: 10.1007/s00441-017-2584-1. Epub 2017 Mar 11.
Termites are the major decomposers of lignocellulosic biomass on Earth and are commonly considered as biological reactor models for lignocellulose degradation. Despite their biotechnological potential, few studies have focused on the morphophysiological aspects of the termite digestive system. We therefore analyze the morphology, ultrastructure and gut luminal pH of the digestive system in workers of the litter-feeding termite Cornitermes cumulans (Blattodea: Termitidae). Their digestive system is composed of salivary glands and an alimentary canal with a pH ranging from neutral to alkaline. The salivary glands have an acinar structure and present cells with secretory characteristics. The alimentary canal is differentiated into the foregut, midgut, mixed segment and hindgut, which comprises the ileum (p1), enteric valve (p2), paunch (p3), colon (p4) and rectum (p5) segments. The foregut has a well-developed chewing system. The midgut possesses a tubular peritrophic membrane and two cell types: digestive cells with secretory and absorptive features and several regenerative cells in mitosis, both cell types being organized into regenerative crypts. The mixed segment exhibits cells rich in glycogen granules. Hindgut p1, p4 and p5 segments have flattened cells with a few apical invaginations related to mitochondria and a thick cuticular lining. Conversely, the hindgut p3 segment contains large cuboid cells with extensive apical invaginations associated with numerous mitochondria. These new insights into the morphophysiology of the digestive system of C. cumulans reveal that it mobilizes lignocellulose components as a nutritional source by means of a highly compartmentalized organization with specialized segments and complex microenvironments.
白蚁是地球上木质纤维素生物质的主要分解者，通常被视为木质纤维素降解的生物反应器模型。尽管它们具有生物技术潜力，但很少有研究关注白蚁消化系统的形态生理方面。因此，我们分析了取食落叶的聚生堆砂白蚁（蜚蠊目：白蚁科）工蚁消化系统的形态、超微结构和肠腔pH值。它们的消化系统由唾液腺和一条pH值从中性到碱性的消化道组成。唾液腺具有腺泡结构，并存在具有分泌特征的细胞。消化道分为前肠、中肠、混合段和后肠，后肠包括回肠（p1）、肠瓣（p2）、嗉囊（p3）、结肠（p4）和直肠（p5）段。前肠有一个发育良好的咀嚼系统。中肠有一层管状围食膜和两种细胞类型：具有分泌和吸收特征的消化细胞以及几个处于有丝分裂状态的再生细胞，这两种细胞类型都组织成再生隐窝。混合段有富含糖原颗粒的细胞。后肠的p1、p4和p5段有扁平细胞，其顶端有一些与线粒体相关的内陷以及一层厚厚的角质层内衬。相反，后肠的p3段含有大型立方形细胞，其顶端有广泛的内陷并与大量线粒体相关。这些关于聚生堆砂白蚁消化系统形态生理的新见解表明，它通过具有专门段和复杂微环境的高度分区化组织将木质纤维素成分作为营养源加以利用。
