RESUMEN
The giant waterbugs are predators that utilize extra-oral digestion and are known to capture a wide variety of prey. Herein we describe the differences in salivary enzyme composition between large and small species of giant waterbug (Lethocerus uhleri, Lethocerinae and Belostoma lutarium, Belostomatinae, respectively). The saliva of L. uhleri contains 3 proteolytic enzymes and no amylase, while the salivary gland of B. lutarium produces 2 proteolytic enzymes and amylase. This fundamental difference in salivary enzyme composition correlates with the difference in diet preference between the Lethocerinae and Belostomatinae. Furthermore, we describe the ultrastructure of the salivary gland complex of B. lutarium and present data on the division of labor with respect to compartmentalization of enzyme production. Proteolytic enzymes are produced in the accessory salivary gland and amylase is produced in the main salivary gland lobe. This is the first reported evidence of protease production in the accessory salivary gland in the Heteroptera.
Asunto(s)
Heterópteros/enzimología , Glándulas Salivales/enzimología , Amilasas/metabolismo , Animales , Electroforesis en Gel de Poliacrilamida/métodos , Endopeptidasas/metabolismo , Heterópteros/metabolismo , Heterópteros/ultraestructura , Microscopía Electrónica de Transmisión/métodos , Microscopía Fluorescente/métodos , Péptido Hidrolasas/metabolismo , Glándulas Salivales/metabolismo , Glándulas Salivales/ultraestructura , Proteínas y Péptidos Salivales/metabolismo , Almidón/metabolismoRESUMEN
The rostral region of nonpipoid tadpoles has two sets of cartilages, the cornua trabeculae and the suprarostral cartilages, whereas the rostral region in pipoid larvae is occupied by a single and continuous cartilage, the suprarostral plate. The homology of this region in pipoid and nonpipoids tadpoles has been controversial. We examined the early formation and development of the suprarostral plate using serially cross-sectioned specimens of Rhinophrynus, Xenopus, and Hymenochirus. We conclude that the cartilaginous structures present in the rostral area of pipoid and nonpipoid larvae are homologous. Furthermore, we found two different developmental patterns among pipoid larvae. The chondrocranium of Hymenochirus boettgeri is described and illustrated to understand its developmental pattern and because of its uniqueness among pipoid chondrocrania.