Results
3.1. Biological parameters
In Table 1, length and weight are presented for each species and
sex regardless of depth, site and season. A clear sexual dimorphism
was only seen in A. rostratus whereas in L. lepidion a high proportion
of immature fish was present and no sex-related differences in size
were seen in this species nor in C. mediterraneus. B. mediterraneus is
a hermaphrodite species.
3.2. ChEs characterisation
AChE activity was the dominant cholinesterase in fish muscle,
followed by PrChE while the hydrolysis rate using BTC was practically
immeasurable. Moreover, the lack of enzyme inhibition using
iso-OMPA indicated BuChE was not present in all these deep-sea
fish species. There was a significant correlation (p < 0.01) between
AChE and PrChE in each individual species calculated using
either a subsample: C. mediterraneus and B. mediterraneus
(R ¼ 0.769 and 0.885, n ¼ 10, respectively), A. rostratus (R ¼ 0.953;
n ¼ 38) or the totality of the sample size in L. lepidion (R ¼ 0.762;
n ¼ 129). Hence, only the predominant AChE activity was further
monitored. ChEs characterisation was carried out using three selective
inhibitors, which allow the discrimination between cholinesterases.
Eserine inhibited ChEs at the lowest dose of 0.64 mM
(76e82% inhibition) revealing dominance of true ChEs. The specific
AChE inhibitor BW248c51 caused inhibition ranging from 27%
(A. rostratus) to 68% (L. lepidion) also at the lowest dose of 0.64 mM;
and this inhibition increased in a dose dependent manner (Fig. 2).
The inhibitor iso-OMPA, specific for BuChE, did not affect ChE
activity.