A novel growth-promoting protein in the conditioned media from the rotifer Brachionus plicatilis at an early exponential growth phase

Abstract

We confirmed the existence of growthpromoting substances in the conditioned media (CM) from the rotifer Brachionus plicatilis at an early exponential growth phase and isolated a novel protein with a growth-promoting activity from the crude extract (CE) of rotifer cells. CM was prepared from the culture media where rotifers had been cultured at an early exponential growth phase and filtered through a 0.22-lm filter membrane. The growth-promoting activity was determined using rotifers in CM for 5 days. As a result, the increase of rotifers added with CM was significantly higher than that of the control in artificial seawater (P \ 0.001). Moreover, the growthpromoting activity of CM was dose-dependent and inactivated by heat treatment at 80°C for 60 min. Meanwhile, CM filtered through a \10 kDa ultrafiltration membrane showed a low activity, whereas proteinase K treatment resulted in a complete inactivation. These results suggest that the rotifer secrets growth-promoting proteins into CM. CE also contained a protein with the activity and properties similar to those found in CM. Then, CE was subjected to purification of a growth-promoting protein for convenience using various types of chromatography after fractionation with 30-80% saturated ammonium sulfate. Subsequently, a protein with an approximate molecular weight of 25000 was isolated, and its N-terminal amino acid sequence was determined to be PAVVDFTAVWFGPLQMIKP. An orthologue was found in the EST database of B. plicatilis, the full sequence of which showed about 50% identity to the corresponding regions of thioredoxins from other organisms.

Nutritional effects on the visual system of the rotifer Brachionus plicatilis sensu stricto (Rotifera: Monogononta)

“…The lower population growth of rotifers fed baker's yeast is caused by the deficiency of vitamin A (Satuito and Hirayama, 1986), vitamin B12 (Hirayama and Funamoto, 1983) and fatty acids (Satuito and Hirayama, 1991). Other factors, such as growth promoting substances (Gallardo et al, 1997;Ohmori et al, 2011) and stress resistance (Gallardo et al, 1999;Kaneko et al, 2011) play a role in regulating rotifer population dynamics (Hagiwara et al, 2001). In this study, rotifers cultured with different feeding regimes were illuminated with two different light intensities (0.5 and 6.0 W m -2 ).…”

4. Rotifera

“…Several putative endocrine disruptors, sufficiently similar to hormones that they interfere with normal endocrine signaling in aquatic animals have effects on rotifers (Snell & Joaquim-Justo 2007). Moreover, rotifers indeed produce growth-promoting substances (Ohmori et al 2011).…”

Measurement of Survival Time in <em>Brachionus </em>Rotifers: Synchronization of Maternal Conditions

“…Culture them as a single cohort (density: ~50 individuals/ml) in a 6-well culture plate as described in 2.1–2.3 in a fresh media under ad libitum feeding. Controlling population density is important because the conditioned medium affects reproductive physiology of Brachionus rotifers 32,33 .…”