Expression and activity of key lipases during the larval development of walking catfish (Clarias magur)

Abstract

The study was conducted to investigate the expression and activity of key lipolytic enzymes during the ontogenetic development of Clarias magur. After partial characterization, the messenger RNA (mRNA) expression analysis of lipoprotein lipase (LPL), pancreatic triacylglycerol lipase (PL), and bile salt-activated lipase (BAL) genes along with the specific lipase activity were performed in larvae from Day 1 after hatching till 34-day posthatch (dph). Heterogeneous patterns of mRNA expression were shown by the important lipolytic enzymes and were detected before first exogenous feeding during the yolk-sac stage. LPL started increasing from 13 dph and peaked at 16 dph followed by a declining trend till 34 dph. However, the PL observed to be peaking at 9, 22, and 30 dph. Similarly, BAL showed an increasing trend from 11 to 22 dph with a significantly high level of mRNA expression at 16 dph. Later, the specific lipase activity was evaluated which appears at Day 1 after hatching with a progressive increase from 7 to 16 dph and a further declining trend afterwards with a peak at 22 dph. The results indicated the development of exocrine pancreas at 16 dph. Furthermore, the transcript levels and the activity of lipases were regulated with the age. Hence, the present study can be helpful in devising different strategies containing optimum lipid levels at a suitable stage of development for improving the survival during larval rearing. Furthermore, the study could be a baseline for elucidating the optimized dietary lipid levels of this catfish during its larval rearing.

Expression Profiling of Lipolytic and Long-Chain Fatty Acid Biosynthesis Genes in Catfish Larvae Fed With Graded Lipid Levels

“…The temporal variation in expression levels of lipolytic genes was evaluated, and it was found that only LPL displayed significant difference in the relative mRNA levels. The significant decrease in the LPL gene expression can be correlated with the results of our previous study (Mir et al, 2019), where it showed a declining trend after 16 dph. Whether the effect on the lipolytic gene expression was due to age or difference in dietary protein level could not be differentiated as the three time points represent the samples fed with different protein levels.…”

“…During the rearing period, different water quality parameters like dissolved oxygen, temperature, and pH were observed to be in the optimum ranges of 6-8 mg L −1 , 28-30 • C and 7.8-8.2, respectively. The experiment conducted from the 14 dph stage was based on the inference from our previous study (Mir et al, 2019), where the C. magur was found to efficiently utilize dietary lipids from 13 dph onward. Nine experimental diets were prepared with combination of three lipids (8, 10, and 12%) and three protein levels (55, 50, and 45%).…”

Knockdown of RpL36 in testes impairs spermatogenesis in Drosophila melanogaster

“…The alignment of RpL36 amino acid sequences was done by DNAMAN 6.0. The neighbor‐joining (NJ) tree of the RpL36 of D. melanogaster with other species was constructed using MEGA 7.0 (Mir et al, 2019), and bootstrap analysis was performed using 1000 replicates.…”