Group Lophotrochozoa is subdivided into six subgroups;
(a) Flatworms (Platyhelminthes, which includes turbellarians, trematodes, and cestodes),
(b) Nemerteans (ribbon worms),
© Mollusks (chitons, gastropods such as snails, slugs, nudibranchs, bivalves like clams and oysters, cephalopods like squids and octopus),
(d) Annelids (polychaetes like sandworms and tubeworms, oligochaetes including earthworms and freshwater worms, hirudinids, which includes leeches) ,
(e) Lophophorates (branchipods, phoronids, and bryozoans), and
(f) Rotifera (wheel animals)
lophophorates (Brachiopoda, Phoronida, and Bryozoa) are protostomes and closely related to molluscs and annelids and with flatworms and Rotifera (Aguinaldo et al., 1997).
Rotifers: A model system for aging
- a history of aging research extending back nearly a century;
- asexual propagation of clonal cultures, so that experiments can take place in the same genetic background, without the potential inbreeding depression imposed on isogenic lines;
- sexual and asexual reproduction in the same genetic background;
- haploid males, allowing direct expression of alleles and simplifying crosses in the absence of complex marker chromosomes; 5) production of highly stable diapausing embryos;
- many closely related strains and species that differ in life history traits; and
- a well-developed tool box of genetic resources including partially sequenced genomes and transcriptomes, and a working RNAi protocol.
Factors affecting lifespan of rotifers
Key genes responsible (for ageing) have been identified in several signalling pathways, including the insulin growth factor and insulin-activated pathways, mitogen-activated and stress activated pathways, the DNA damage response, and the FOXO, Sirtuin, TOR, P13-K, and AMPK pathways.(Snell 2014). RNAi knockdown of these genes in rotifers can enable us to throw light on the lifespan manipulation.
Dietary restriction (DR)
remains the most reliable and consistent way to extend lifespan in animals
(Sinclair 2005, Bordone and Guarente 2005, Mair and Dillin 2008).
Merry, 2002 stated the uncertainity of the mechanisms that are involved in life extension through dietary restriction… The hormesis hypothesis (Sinclair 2005) proposed that DR works
in most animals because low caloric intake is mildly stressful and provokes a survival
response based on the up- and down-regulation of particular genes.
Key researchers- K L Kirk, Yoshinaga, Weithoff, Ozdemir, Gribble and Mark Welch
Antioxidants: Antioxidants are compounds that can reduce cellular damage caused by Reactive Oxygen Species(ROS), slowing aging and sometimes producing life extension in experimental animals (Halliwell 2011).
Gender and reproductive mode:
Thus, we can see that rotifers make an ideal model system for the study of ageing, easy to culture and observe the changes it undergoes while doing the experiment.