Ontogenetic development of digestive tract and digestive enzymatic activities inSqualiobarbus curriculuslarvae

Abstract

Squaliobarbus curriculus is an economically important freshwater fish. The ontogenetic development of the digestive system of S. curriculus larvae was studied histologically and enzymatically from hatching to 30 days posthatching (DPH). Amylase, lipase, alkaline phosphatase and pepsin activities were detected from the hatching stage, indicating that these enzymes were genetically preprogrammed. Marked increases in intestinal amylase, trypsin and alkaline phosphatase activities between 10 and 20 DPH corresponded to feed acquisition and transformation. Larval development in S. curriculus could be divided into three phases: phase I (endotrophic period): 1-3 DPH; phase II (endo-exotrophic period): 4-5 DPH; and phase III (exclusively exotrophic period): from 6 DPH onward. At hatching, the digestive tract of the larvae was an undifferentiated straight tube. On 3 DPH, the digestive tract differentiated into the mouth cavity, oesophagus and intestine. On 6 DPH, feeding was totally exotrophic and the yolk sac was completely exhausted. During the growth of S. curriculus larvae, the intestinal mucosa formed and the number of goblet cells and microvilli increased, demonstrating maturation of the digestive system.The study about the digestive development of S. curriculus larvae will contribute to better larval-rearing strategies. K E Y W O R D Sdigestive system, enzyme activity, histology, ontogenetic development, Squaliobarbus curriculus

Changes in digestive enzymes activities during the initial ontogeny of wolf cichlid, Parachromis dovii (Perciformes: Cichlidae)

“…The α-amylase activity in P. dovii was founded from 6 DAH (9.49 mm, 168 DD, 0.056 mm.ºC.days), fluctuating with low levels, during ontogeny as found for O. niloticus (Tengjaroenkul et al, 2002). This finding differs from other fish species, especially marine, such as white seabream, Diplodus sargus (Linnaeus), D. labrax, R. kutum, E. coloides, L. erythropterus, C. chitala, A. sapidissima and S. curriculus (Cara et al, 2003;Cahu et al, 2004;Khosravi Bakhtiarvandi, Abedian-Kenari, 2015;Guo et al, 2016;Cui et al, 2017;Mitra et al, 2017;Xiao-Qiang et al, 2017;Shen et al, 2018), in which amylase activity decreased with fish age. In monogastric fish, amylase activity has low impact but in agastric ones it is relevant in carbohydrate digestion, e.g.…”

“…In this context, PUFA's play a key role at cellular membrane, increasing its fluidity, flexibility and permeability, reason to incorporate them in the diets. Their utilization by the fish is modulated by esterases, phospholipases and true lipases (Evans et al, 1998) Mitra et al, 2017;Xiao-Qiang et al, 2017;Shen et al, 2018).…”

“…In the past, several studies characterizing some digestive enzymes has been done with cichlids of commercial importance; Nile tilapia, Oreochromis niloticus (Linnaeus) (Tengjaroenkul et al, 2002), blue disc, Symphysodon aequifasciatus (Pellegrin) (Chong et al, 2002), Mayan cichlid, Mayaheros urophthalmus (Günther) (López-Ramírez et al, 2011), bay snook, Petenia splendida (Günther) , three-spot cichlid, Amphilophus trimaculatus (Günther) (Toledo-Solís et al, 2015), and other fish species such as sobaity sea bream, Sparidentex hasta (Valenciennes) (Nazemroaya et al, 2015), zebrafish, Danio rerio (Hamilton) (Guerrera et al, 2015), Caspian kutum, Rutilus kutum (Kamensky) (Khosravi Bakhtiarvandi, Abedian-Kenari, 2015), golden pompano, Trachinotus ovatus (Linnaeus) , thick-lipped grey mullet, orange-spotted grouper, Epinephelus coioides (Hamilton) (Guo et al, 2016), starry flounder, Platichthys stellatus (Pallas) , Chelon labrosus (Risso) (Pujante et al, 2017), turbot, Scophthalmus maximus (Linnaeus) (Tong et al, 2017), crimson snapper, Lutjanus erythropterus (Bloch) (Cui et al, 2017), American shad, Alosa sapidissima (Wilson) (Xiao-Qiang et al, 2017), clown knifefishChitala chitala (Hamilton) (Mitra et al, 2017), and barbel chub, Squaliobarbus curriculus (Richardson) (Shen et al, 2018).…”

Effects of Feeding Regimens on the Proximate Composition and Condition Indices of Juvenile Koi Cyprinuscarpio Used as Forage

“…This suggests koi have an ontogenetic need for higher‐energy/protein levels in their early juvenile stages. Ontogenetic shifts have been observed in fish digestive enzymes and histology (Guerrera et al 2015; Shen et al 2018). A dietary ontogenetic shift in feed preference also has been observed in Common Carp (Vilizzi 1998; Rahman et al 2009), where larvae transition from feeding primarily on zooplankton to feeding primarily on benthic macro invertebrates when transitioning from their larval to juvenile life stage.…”