Glycolipids as Potential Energy Molecules during Starvation in Climbing Perch, Anabas testudineus (Bloch)

Glycolipids are membrane lipids which act as cellular markers and also provide energy for the cells. The present study is an attempt to understand whether glycolipids can act as energy sources during fasting. To achieve this, we selected and subjected Anabas testudineus to short-term (15 days) and long-term (60 days) laboratory starvation. We estimated glycolipids biochemically using a standard protocol in six different tissues. Results showed a selective decline in glycolipid concentration in certain tissues, and also an increase was observed in some tissues. Short-term fasting led to a decline in glycolipids in tissues such as brain ( ), accessory respiratory organ ( ), pectoral and lateral line muscle. Liver and kidney ( ) reported an increase. Long term starvation also resulted in a decline in tissues such as liver ( ), kidney ( ), brain, and accessory respiratory organ. Muscle tissue, that is, both the pectoral ( ) and lateral line muscle ( ), showed an increase in the glycolipid fraction. This selective decline in glycolipid content of certain tissues suggests a possible utilization of these lipids during starvation and the significant upsurge observed in certain tissues suggests a simultaneous synthesis occurring along the degradation, probably reducing the oxidative stress created by ROS (reactive oxygen species). 1. Introduction Fish, during their life time, are capable of withstanding prolonged periods of natural starvation caused due to migration, reproduction and also during fish farming [1–3]. There are several instances where certain fish species have been reported to survive without food for several months or even for years as reported in case of silver eels which go without food for even four years [4, 5]. When the animal is in a state of food deprivation there are lines of evidence wherein the animal differentially utilizes proteins, carbohydrates, and lipids. Utilization of energy fuels is not uniform in all fish but is species dependent. In fish like Acipenser oxyrinchus and Oncorhynchus mykiss, parallel to glycogen mobilization, lipids are utilized initially and proteins are utilized as the last reserve [6]. In certain other fish species, liver glycogen stores are preserved and either protein is degraded via gluconeogenesis, or protein and lipid may be mobilized as energy substrates [6–8]. Apart from these regular energy substrates, other energy molecules such as glycolipids, which are membrane lipids which have glucose and galactose attached to the lipid unit [9], may also be considered as potential sources of energy by the starving