15 research outputs found
Sometimes Sperm Whales (Physeter macrocephalus) Cannot Find Their Way Back to the High Seas: A Multidisciplinary Study on a Mass Stranding
BACKGROUND: Mass strandings of sperm whales (Physeter macrocephalus) remain peculiar and rather unexplained events, which rarely occur in the Mediterranean Sea. Solar cycles and related changes in the geomagnetic field, variations in water temperature and weather conditions, coast geographical features and human activities have been proposed as possible causes. In December 2009, a pod of seven male sperm whales stranded along the Adriatic coast of Southern Italy. This is the sixth instance from 1555 in this basin. METHODOLOGY/PRINCIPAL FINDINGS: Complete necropsies were performed on three whales whose bodies were in good condition, carrying out on sampled tissues histopathology, virology, bacteriology, parasitology, and screening of veins looking for gas emboli. Furthermore, samples for age determination, genetic studies, gastric content evaluation, stable isotopes and toxicology were taken from all the seven specimens. The animals were part of the same group and determined by genetic and photo-identification to be part of the Mediterranean population. Causes of death did not include biological agents, or the "gas and fat embolic syndrome", associated with direct sonar exposure. Environmental pollutant tissue concentrations were relatively high, in particular organochlorinated xenobiotics. Gastric content and morphologic tissue examinations showed a prolonged starvation, which likely caused, at its turn, the mobilization of lipophilic contaminants from the adipose tissue. Chemical compounds subsequently entered the blood circulation and may have impaired immune and nervous functions. CONCLUSIONS/SIGNIFICANCE: A multi-factorial cause underlying this sperm whales' mass stranding is proposed herein based upon the results of postmortem investigations as well as of the detailed analyses of the geographical and historical background. The seven sperm whales took the same "wrong way" into the Adriatic Sea, a potentially dangerous trap for Mediterranean sperm whales. Seismic surveys should be also regarded as potential co-factors, even if no evidence of direct impact has been detected
Bidirectional fluxes of spermine across the mitochondrial membrane.
The polyamine spermine is transported into the
mitochondrial matrix by an electrophoretic mechanism
having as driving force the negative electrical membrane
potential (DW). The presence of phosphate increases
spermine uptake by reducingDpH and enhancingDW. The
transport system is a specific uniporter constituted by a
protein channel exhibiting two asymmetric energy barriers
with the spermine binding site located in the energy well
between the two barriers. Although spermine transport is
electrophoretic in origin, its accumulation does not follow
the Nernst equation for the presence of an efflux pathway.
Spermine efflux may be induced by different agents, such as
FCCP, antimycin A and mersalyl, able to completely or
partially reduce theDWvalue and, consequently, suppress
or weaken the force necessary to maintain spermine in the
matrix. However this efflux may also take place in normal
conditions when the electrophoretic accumulation of the
polycationic polyamine induces a sufficient drop inDWable
to trigger the efflux pathway. The release of the polyamine
is most probably electroneutral in origin and can take place
in exchange with protons or in symport with phosphate
anion. The activity of both the uptake and efflux pathways
induces a continuous cycling of spermine across the mitochondrial membrane, the rate of which may be prominent in imposing the concentrations of spermine in the inner and
outer compartment. Thus, this event has a significant role on
mitochondrial permeability transition modulation and consequently on the triggering of intrinsic apoptosis