Age-related changes in midgut ultrastructure and trypsin activity in the honey bee, Apis mellifera

Abstract

Summary — Trypsin-like activity was detected in the epithelial tissue, in the fluid of the ectoperitrophic space, and within the endoperitrophic space of the midgut of adult worker honey bees, Apis mellifera. It was highest in free-flying bees and in caged bees fed pollen. Lower levels occurred in caged bees restricted to sucrose syrup or fed sucrose syrup in addition to either Beltsville Bee Diet or egg albumin. Levels of midgut trypsin activity were dependent on the amount of protein diet consumed. Both diet consumption and trypsin-like activity decreased as the bees aged. Ultrastructural changes in the midgut tissue accompanied this decline in enzymatic activity. In five-day-old pollen-feeding bees, the apical cytoplasm of cells in the posterior midgut contained numerous electronopaque vesicles, and the brush border in the crypts of the distal midgut was composed of short pleomorphic microvilli. Apical discharge from the midgut cells released the opaque vesicles into the midgut lumen. However, in 30-day-old field bees, the number of opaque vesicles and the microvesiculation of the brush border were reduced. Thus, the presence of the endogenously produced endoprotease and the regional variation in cell ultrastructure suggest that the honey bee may rely on countercurrent flow to distribute enzymes and nutrients efficiently throughout the midgut. Apis mellifera— midgut ultrastructure -enzymatic activity -trypsin -age

Expression profile of water-soluble proteinases during ontogenesis of Megachile rotundata: an electrophoretic investigation

“…This hypothesis is in agreement with data concerning the presence of several proteolytic activities with a digestive role at alkaline pH detectable in the midgut of several insects (Purcell et al, 1992;Walker et al, 1998;Jimenez and Gilliam, 1989). These data have been emphasized on the basis of observations concerning the digestion physiology in the bee S. bipunctata that involve aminopeptidase and trypsin enzyme (Schumaker et al, 1993).…”

“…Hunt (1980, 1984) found out that chymotrypsin-like enzymes of young adults of worker honeybees that still feed on pollen followed a seasonal pattern, coinciding with periods of elevated pollen consumption, while the trypsin-like ones decreased with ageing which suggests that these proteinases do not have a digestive role. Indeed, the young adult honeybees still eat pollen for five to ten days after emergence when they are generally considered to be nurse bees (Jimenez and Gilliam, 1989;Crailsheim et al, 1992). Pollen consumption at this age would initiate both digestive enzyme synthesis and hypo-pharyngeal gland development (Brouwers, 1982).…”

Properties and compartmentalization of digestive carbohydrases and proteases in Scaptotrigona bipunctata (Apidae: Meliponinae) larvae

“…Among the Hymenoptera, Apidae is no exception. The properties of some adult Apis mellifera digestive enzymes, such as maltase (Huber, 1975), trypsin, chymotrypsin and 2 other endopeptidases (Giebel et al, 1971;Dahlman et al, 1978), have been studied in some detail, whereas others such as lactase (Peng, 1981) (endoperitrophic) and outside (ectoperitrophic) the peritrophic membrane (Moritz and Crailsheim, 1987;Jimenez and Gilliam, 1989).…”

Peroxisomal enzymes in the honey bee midgut

“…Ten marked bees were chilled at 4°C until immobile and their midguts extirpated into ice cold Apis saline (AS) (Brouwers, 1982). Midgut tissue was separated from the contents of the endoperitrophic space, the Malpighian tubules, and the small intestine as previously described (Jimenez and Gilliam, 1989). The ten isolated midguts were rinsed 3 times in ice cold AS, weighed on filter paper, and homogenized on ice in 1 ml of cold 0.1 M phosphate buffer, pH 7.4, using a glass tissue homogenizer and a Teflon@ pestle driven at 1,000-2,000 rpm.…”