title: Spatial distribution of digestive proteinases in the midgut of the Pacific white shrimp (Litopenaeus vannamei) indicates the existence of endo-ectoperitrophic circulation in Crustacea.
abstract: The effect of dietary protein concentration on the spatial distribution of digestive proteinases in the shrimp Litopenaeus vannamei indicates the existence of endo-ectoperitrophic enzyme circulation in this species. Samples recovered from the midgut gland tissues, stomach contents, three different portions of the midgut and feces were used for quantitative and qualitative analyses of the composition and distribution of the digestive proteinases. Animals were divided into three different groups: (1) animals (controls) fed with a commercial 35% protein diet, (2) animals fed with a commercial diet supplemented with ovalbumin to a final protein concentration of 60%; (3) animals fed with an 80% protein diet. Quantitative determinations using different substrates and zymograms showed that increasing protein concentration in the diet alters the distribution of proteinases along the digestive tract. Composition of proteinases in the midgut gland, stomach contents, midgut sections and feces were similar, but not identical. Chymotrypsin and trypsin paralogues were identified in all enzyme sources in a concentration gradient along the midgut in the control shrimp, the expected distribution supporting the existence of a recycling mechanism. The occurrence of a peritrophic membrane in other Decapoda suggests that endo-ectoperitrophic circulation of digestive enzymes and nutrients may also occur in other crustaceans and also extends beyond the Insecta.
authors.affiliation: Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC, Brazil.
authors.forename: Daniel
authors.initials: D
authors.lastname: Alexandre
authors.affiliation: Laboratório Central de Microscopia Eletrônica, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC, Brazil; Departamento de Aquicultura, Centro de Ciências Agrárias, Universidade Federal de Santa Catarina, 88034-001, Florianópolis, SC, Brazil.
authors.forename: Renata A
authors.initials: RA
authors.lastname: Ozório
authors.affiliation: Departamento de Aquicultura, Centro de Ciências Agrárias, Universidade Federal de Santa Catarina, 88034-001, Florianópolis, SC, Brazil.
authors.forename: Roberto B
authors.initials: RB
authors.lastname: Derner
authors.affiliation: Departamento de Aquicultura, Centro de Ciências Agrárias, Universidade Federal de Santa Catarina, 88034-001, Florianópolis, SC, Brazil.
authors.forename: Débora M
authors.initials: DM
authors.lastname: Fracalossi
authors.affiliation: Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC, Brazil.
authors.forename: Gabriel B
authors.initials: GB
authors.lastname: Oliveira
authors.affiliation: Laboratório de Entomologia e Fitopatologia, Centro de Ciências e Tecnologia Agropecuárias, Universidade Estadual do Norte Fluminense Darcy Ribeiro, 28013-602, Campos dos Goytacazes, RJ, Brazil.
authors.forename: Richard I
authors.initials: RI
authors.lastname: Samuels
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, C.P. 26077, 05513-970, São Paulo, Brazil.
authors.forename: Walter R
authors.initials: WR
authors.lastname: Terra
authors.affiliation: Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC, Brazil. Electronic address: carlos.peres@ufsc.br.
authors.forename: Carlos P
authors.initials: CP
authors.lastname: Silva
mesh_terms: D000818:Animals; D004044:Dietary Proteins / Q000494:pharmacology; D004064:Digestive System / Q000201:enzymology*; D007422:Intestines / Q000201:enzymology; D033561:Penaeidae / Q000201:enzymology / Q000502:physiology*; D010447:Peptide Hydrolases / Q000378:metabolism*
chemical_list: D004044:Dietary Proteins; D010447:Peptide Hydrolases
keywords: Penaeidae; Peritrophic membrane; Protein digestion; Proteinase