In this work, we refer several times to studies with C. elegans,
since this model animal is well understood and several recent
studies and reviews indicate that there are many similarities between
the nematode and arthropods in terms of stress response
and lifespan extension (Minois, 2000; Gems and McElwee, 2003;
Schrimpf et al., 2009; Ristow and Schmeisser, 2011). More general,
Schrimpf et al. (2009) found that the abundances of ortholog proteins
from worm and fly correlate well. Hence, it appears justified
to refer to nematode studies in order to create hypotheses on potential
regulatory pathways in arthropods, in general, and Moina
macrocopa, in particular.
For lifespan extension, several pathways are described. For instance,
Murphy et al. (2003) identified a large set of genes whose
activity is linked to lifespan and aging. A prime example of an
interesting gerontogene is daf-16 which encodes the forkhead transcription
factor DAF-16 in C. elegans. Murphy et al. (2003) identified
two classes of genes that are influenced by DAF-16. Class 1
genes are switched on by DAF-16 and are associated with increased
lifespan, whereas class 2 genes are repressed by DAF-16
and are associated with reduced lifespan and increased reproduction.
This means that this regulatory pathway allocates energy
either to body maintenance (growth, longevity) or reproduction.
Since growth, longevity, and reproduction are stimulated simultaneously
in exposed Moina individuals, it is questionable if this or
an equivalent pathway applies.
Almost simultaneously to the emerging hypothesis of DAF-16
being central in lifespan extension, reports showed that this is only
one of several regulatory pathways. For instance, by using a daf-
16(mgDf50) mutant strain of C. elegans, Saul et al. (2008) showed
that exposure to the polyphenol quercetin led to significantly increased
mean lifespans. If components of the leachates trigger a
DAF-16-independent pathway of longevity one may assume that
the choice of body maintenance or reproduction is less strict than
with DAF-16 pathway involved. This assumption is supported by
Kenyon (2010) who reviewed the connection between lifespan,
reproduction, and DAF-16. If a comparable regulatory pathway applies
even to the Moina study is open to future studies