The expression pattern of dormancy-associated genes in multiple life-history stages in the rotifer Brachionus plicatilis

Abstract

Rotifer resting eggs retain their viability for several decades in a non-desiccated form and are of interest in discerning the processes associated with dormancy, since in most organisms this phenomenon is linked with desiccation. The expression pattern of candidate genes with biological functions associated with dormancy in several other organisms was examined in rotifers. High-throughput transcriptome profiling revealed three patterns of gene expression in resting eggs: (1) relatively highly expressed genes coding for LEA proteins and putative paralogs of the small heat shock protein family (shsp); (2) genes coding for ferritin (ferr), glutathione-6-transferase (gts) and HSP70, where some of the putative gene paralogs of these families show relatively high expression levels and other putative paralogs show relatively low expression levels in resting eggs; and (3) genes with relatively low expression levels in resting eggs, for trehalose-6-phosphate synthase (tps), fatty-acid binding proteins (fab) and of lipoprotein lipase (lpl) and the aquaporins gene family (aqp). Changes in the expression pattern of some members of putative gene families occurred during the obligatory dormant period of resting eggs. A transition was observed from an expression pattern of diapausing embryos to an expression pattern of amictic females, during hatching. Differences were also found in the expression pattern in the different types of females, especially in those carrying resting eggs, and in males compared with females. These results suggest putative functional significance to genes associated with dormancy in non-desiccated resting eggs. It could also be proposed that their occurrence in resting eggs is developmentally programmed to facilitate survival in case of desiccation.

Rotifers of temporary waters

“…Smith et al review existing knowledge on the hsp stress proteins and using a variety of molecular tools show that stress proteins hsp 40 , 60 , and 70 are required for thermal tolerance in Brachionus manjavacas . Further, Denekamp et al note that diapausing embryos express genes for low molecular weight hsps . Unlike in other species that enter anhydrobiosis, desiccation tolerance in bdelloid rotifers is not dependent on production of the stabilizing sugar trehalose , and in fact several species lack the genes encoding these sugars .…”

“…Unlike in other species that enter anhydrobiosis, desiccation tolerance in bdelloid rotifers is not dependent on production of the stabilizing sugar trehalose , and in fact several species lack the genes encoding these sugars . Late embryogenesis abundant (LEA) proteins and multiple copies of alpha tubulin appear to be important in desiccation tolerance. In addition, ability to recover from anhydrobiosis is dependent on time and other environmental conditions.…”

Dormancy in Embryos: Insight from Hydrated Encysted Embryos of an Aquatic Invertebrate

“…The ecological significance of dormancy in rotifers has been extensively reviewed (36 -41) and molecular information was published in recent years (42)(43)(44)(45)(46)(47)(48)(49)(50)(51). Including, the expression patterns in amictic and resting eggs of genes encoding proteins with putative functions in dormancy (52,53; e.g. small heat-shock proteins, ferritin, glutathione-S-transferase, and trehalose-6-phosphate synthase).…”

A Simple Method for the Decapsulation of Dormant Resting Eggs for Nuclear Staining in the Monogonont Rotifer, Brachionus plicatilis Muller

“…Real time RT-PCR showed that LEA proteins and small heat shock proteins (sHSP) were upregulated in both resting eggs and females producing resting eggs in comparison to amictic eggs and females producing amictic eggs, respectively [6]. High-throughput Illumina sequencing data in concurrence to RT-PCR analysis showed higher expression of LEAs, glutathione-S-trasnferases, HSPs, and downregulation in trehalose metabolism, aquaporins transcription during early RE dormancy and the respective expression pattern for the aforementioned genes in females carrying REs versus amictic correlated with the types of eggs they produced [7]. Highthroughput Illumina sequencing was also used to show that for resting eggs, genes associated with cellular maintenance and survival were upregulated such as antioxidants, oxidoreductases, and protein chaperone genes; in comparison to amictic eggs, genes associated with cellular and organismic development such as cell cycle and cytoskeletal genes [8].…”