Monogonont Rotifer, Brachionus calyciflorus, Possesses Exceptionally Large, Fragmented Mitogenome.

In contrast to the highly conserved mitogenomic structure and organisation in most animals (including rotifers), the two previously sequenced monogonont rotifer mitogenomes were fragmented into two chromosomes similar in size, each of which possessed one major non-coding region (mNCR) of about 4-5 Kbp. To further explore this phenomenon, we have sequenced and analysed the mitogenome of one of the most studied monogonont rotifers, Brachionus calyciflorus. It is also composed of two circular chromosomes, but the chromosome-I is extremely large (27 535 bp; 3 mNCRs), whereas the chromosome-II is relatively small (9 833 bp; 1 mNCR). With the total size of 37 368 bp, it is one of the largest metazoan mitogenomes ever reported. In comparison to other monogononts, gene distribution between the two chromosomes and gene order are different and the number of mNCRs is doubled. Atp8 was not found (common in rotifers), and Cytb was present in two copies (the first report in rotifers). A high number (99) of SNPs indicates fast evolution of the Cytb-1 copy. The four mNCRs (5.3-5.5 Kb) were relatively similar. Publication of this sequence shall contribute to the understanding of the evolutionary history of the unique mitogenomic organisation in this group of rotifers.

[Effects of diets on growth, serum biochemical indices and lipid metabolism in Coilia nasus].

Effects of diets on growth, serum biochemical indices, and enzyme activities related to lipid metabolism in fingerlings Coilia nasus at age of 6 months were investigated during 60-day experiment in this study. Fingerlings with similar body length and mass were fed with one of 3 types of diets (diet 1: soft pellet; diet 2: soft pellet mixed with fish oil; diet 3: slow-sinking hard pellet). Fish fed with diets 2 or 3 had significantly higher total body mass, rate of mass gain, specific growth rate, and fullness coefficient than those fed with diet 1. Fish fed with diet 3 exhibited the lower food coefficient compared to those fed with diets 1 or 2. Growth traits (length, length to mass ratio, length to width ratio, hepatopancreas somatic indices and viscera somatic index) and serum biochemical indices (total protein, albumin, blood glucose, cholesterol and triglycerides) in all three treatments were not significantly different. Fish fed with diet 1 exhibited significantly higher carnitine palmitoyltransferase-I than those fed with diets 2 or 3, while fish fed with diet 2 exhibited significantly lower carnitine palmitoyltransferase-II. However, amylase, pepsin, lipase activity, lipoprotein lipase and acetyl-coa carboxylase had no significant difference in fish body among all groups. Results suggested that fish oil as a diet supplement highly facilitated fish growing. The slow-sinking pellet had the highest utilization efficiency and was suitable to feed fish fingerlings of C. nasus.