Investigating Diet as the Source ofTetrodotoxin in Pleurobranchaea maculata

The origin of tetrodotoxin (TTX) is highly debated; researchers have postulated either an endogenous or exogenous source with the host accumulating TTX symbiotically or via food chain transmission. The aim of this study was to determine whether the grey side-gilled sea slug (Pleurobranchaea maculata) could obtain TTX from a dietary source, and to attempt to identify this source through environmental surveys. Eighteen non-toxic P. maculata were maintained in aquariums and twelve were fed a TTX-containing diet. Three P. maculata were harvested after 1 h, 24 h, 17 days and 39 days and TTX concentrations in their stomach, gonad, mantle and remaining tissue/fluids determined using liquid chromatography-mass spectrometry. Tetrodotoxin was detected in all organs/tissue after 1 h with an average uptake of 32%. This decreased throughout the experiment (21%, 15% and 9%, respectively). Benthic surveys at sites with dense populations of toxic P. maculata detected very low or no TTX in other organisms. This study demonstrates that P. maculata can accumulate TTX through their diet. However, based on the absence of an identifiable TTX source in the environment, in concert with the extremely high TTX concentrations and short life spans of P. maculata, it is unlikely to be the sole TTX source for this species.     

Genetic diversity and changes in phenolic contents and antiradical activity of <Emphasis Type="Italic">Vaccinium myrtillus</Emphasis> berries from its southernmost growing area in Italy

In this study, we evaluated by the RAPD technique the genetic diversity of 42 individual Vaccinium myrtillus L. plant samples, collected from different locations of Tuscan Apennines (Italy), which represent the southernmost growing latitude of this plant. Total polyphenols, total anthocyanins and radical scavenging activity were also determined in two successive harvesting years on bilberry samples obtained from the same individuals characterized by molecular analysis. The RAPD analysis indicated a highly prevalent gamic propagation of bilberry in the investigated area, and, in accordance with genetic findings elsewhere reported for populations of Central and Northern Europe, suggested the presence, from North-to-South Europe, of a clonal-to-gamic genetic gradient of the propagation strategy. In the context of a quite homogeneous panorama of biochemical data, significant variations were occasionally evidenced by comparing closely-located individuals. We tentatively attributed such variations mainly to genetics, due to the very close location of biomes exhibiting different biochemical attributes. However, molecular clustering by RAPD did not show any relationship with biochemical diversity. Strong variations of climatic conditions were probable responsible of the remarkable variability of the investigated biochemical parameters in the two harvesting years.