Comparative ontogeny of the digestive tract ofOncorhynchus mykiss♀ xSalmo trutta caspius♂ triploid hybrids to their parental species

Abstract

Hybridization or the crossing of individuals from the same species (crossbreeding) or different species (interspecific) offers the possibility of improving traits that benefit aquaculture. Hybridization in salmonids has been used to improve disease resistance, growth rates, manipulate sex ratios and to produce sterile fish (Bartley et al., 2000). For example, Salmo trutta x Salvelinus fontinalis hybrids are sterile (Scheerer & Thorgaard, 1983). The hybrids of Salvelinus namaycush x S. fontinalis (maintained at low pH, 5.5-7.2) and Salmo labrax x Oncorhynchus mykiss have increased growth rates relative to the parental species by day 200 post-hatch (Akhan et al., 2011), while O. mykiss x Salvelinus sp. and S. trutta x S. salar hybrids have increased disease resistance (Maynard et al., 2016). Despite the potential advantages of the salmonid hybrids, their exploitation for aquaculture is uncommon due to high mortality during embryonic stages and up until external feeding (Bartley et al., 2000). Nonetheless, there are some reports that triploidization can increase the viability of salmonid hybrids (Blanc & Maunas, 2005; Blanc et al., 2000; Scheerer & Thorgaard, 1983). One potential reason for high mortalities during the larval stage may be abnormalities in digestive tract function and for this reason characterization of gastrointestinal tract development and the nutritional physiology of fish larvae can contribute to overcome such problems (Rønnestad et al., 2013). Caspian brown trout, CBT, Salmo trutta caspius is one of the native cold water species with high potential for aquaculture in the

Transcriptome datasets and histological profiles of critical larval stages in gilthead seabream

“…Serial sagittal and transverse sections (10 µm thick) of paraffin wax embedded larvae (flexion= 23-25 dph, mid-metamorphosis = 50-56 dph) were prepared using a manual rotary microtome (Leica RM 2135, Germany). The morphological characteristics of organs during early development were characterized by staining sections with haematoxylin and eosin (H&E) using the method described in Najafpour et al [ 5 ]. For detection of lipids, frozen sections were used and stained with Oil Red O using an adaptation of the methods reported in [ 3 , 8 ].…”

“…Larvae at flexion and mid-metamorphosis had an approximate age of 24 and 51 dph, respectively. The sections (10 µm thick) were stained using the haematoxylin and eosin (H&E) method [ 5 ]. Developmental changes in internal organs and tissues such as the heart, brain, stomach, intestine, kidney, swim bladder, gill, eye, vertebral column, liver, and skeletal muscle are obvious during the transition from flexion to mid-metamorphosis.…”