BIOSTASIS
in a nutshell....
The current proposal revolves around the dehydration induced stated of latent life, know as anhydrobiosis, found as a survival strategy to severe desiccation among a range of life forms. Notably, anhydrobiosis is defined by the reversible shut-down of metabolism (biostasis) and in metazoans it involves adaptations at all levels of organismic organization. The current project used tardigrades as a model to gain novel insights into this unique biological phenomenon. Several molecules have been implicated in the anhydrobiotic mechanism; however studies so far have been returning contradictory results with respect to differential expression of genes in the pre- and post- anhydrobiotic phases. Preliminary unpublished data (Kamilari et al. under review), suggest that some of those genes are not present in all evolutionary tardigrade lineages, which raises the possibility of lineage specific strategies to anhydrobiosis.
Transcriptome sequencing (RNAseq) and ddPCR (methods that constitute the most important training elements of the project) will be utilized in order to reveal key-player genes and characterize the functional pathways involved during anhydrobiosis stages in tardigrade species from different evolutionary lineages.
Our ambition goal is to try and determine a potential gene signature for anhydrobiosis, establishing a transcription profile that is characteristic of the particular physiological state and that could possibly reflect the phylogenetic position of a taxon.
About tardigrades
Tardigrades (commonly known as "water bears") are a group of small aquatic metazoans that have colonized many different ecosystems worldwide, from mountain-tops to the deep sea and the frozen deserts of the Arctic and Antarctic. They are always found in association with water (in the aquatic benthos, in the interstices of bryophytes, lichens and moss cushions). Depending on whether they live in terrestrial, freshwater or marine and estuarine habitats they are classified as limno-terrestrial, freshwater or marine species, respectively (McInnes 1994; Nelson, 2002). Tardigrades have evolved a range of stress tolerances towards extreme environmental conditions. Some remain active during environmental stressful conditions, while others may enter cryptobiosis.
A number of tardigrade species, along with nematodes and rotifers, exhibit a remarkable tolerance towards physical extremes. Many species are able to enter a latent state, namely cryptobiosis, when environmental conditions become unfavourable. By entering this latent state they are able to withstand several extreme conditions such as low oxygen, salinity variations, desiccation , high levels of environmental toxins, low and high temperatures (ca. –272°C to +151°C), ionizing radiation (up to 6000 Gy), vacuum and high pressure (up to 600 MPa) (Ramløv and Westh, 1992; Westh and Kristensen, 1992; Ramløv and Westh, 2001; Schill et al., 2004; Horikawa et al., 2006; 2008; 2013; Jönsson and Schill, 2007; Hengherr et al., 2009; Halberg et al. 2009; Møbjerg et al. 2011; Claussen et al 2014).
Tardigrades (commonly known as "water bears") are a group of small aquatic metazoans that have colonized many different ecosystems worldwide, from mountain-tops to the deep sea and the frozen deserts of the Arctic and Antarctic. They are always found in association with water (in the aquatic benthos, in the interstices of bryophytes, lichens and moss cushions). Depending on whether they live in terrestrial, freshwater or marine and estuarine habitats they are classified as limno-terrestrial, freshwater or marine species, respectively (McInnes 1994; Nelson, 2002). Tardigrades have evolved a range of stress tolerances towards extreme environmental conditions. Some remain active during environmental stressful conditions, while others may enter cryptobiosis.
A number of tardigrade species, along with nematodes and rotifers, exhibit a remarkable tolerance towards physical extremes. Many species are able to enter a latent state, namely cryptobiosis, when environmental conditions become unfavourable. By entering this latent state they are able to withstand several extreme conditions such as low oxygen, salinity variations, desiccation , high levels of environmental toxins, low and high temperatures (ca. –272°C to +151°C), ionizing radiation (up to 6000 Gy), vacuum and high pressure (up to 600 MPa) (Ramløv and Westh, 1992; Westh and Kristensen, 1992; Ramløv and Westh, 2001; Schill et al., 2004; Horikawa et al., 2006; 2008; 2013; Jönsson and Schill, 2007; Hengherr et al., 2009; Halberg et al. 2009; Møbjerg et al. 2011; Claussen et al 2014).