SUMMARY Members of the genus Panagrolaimus are bacterial-feeding nematodes that occupy a diversity of niches ranging from Antarctic and temperate soils to terrestrial mosses. Some members of this genus are able to survive extreme desiccation by entering into a state of suspended animation known as anhydrobiosis. We have assembled a collection of Panagrolaimusspecies and strains and have investigated their anhydrobiotic phenotypes. Our data show that within the genus Panagrolaimus there is a continuum of strains ranging from those unable to survive exposure to low relative humidity(RH) without prior preconditioning at high RH (slow desiccation strategists),through strains that have limited ability to survive rapid desiccation but whose anhydrobiotic ability improves upon preconditioning, to strains such as P. superbus that can readily survive immediate exposure to severe desiccation (fast desiccation strategists). Using this panel of nematodes we investigated the effect of preincubation at high RH on the accumulation of trehalose and on the nematodes' anhydrobiotic potential. We found that there is a strong correlation between trehalose induction and anhydrobiotic survival in Panagrolaimus. Furthermore, the high trehalose levels observed in fully hydrated P. superbus (10% dry mass) suggest that constitutive expression of trehalose pre-adapts this fast dehydration strategist to combat desiccation. All the strains observed, regardless of survival rates, undertook both coiling and clumping, which has the effect of reducing surface area and slowing the rate of water loss during desiccation. Phylogenetic analyses were carried out to investigate whether the observed anhydrobiotic phenotypes were the result of convergent evolution or represented a single phylogenetic lineage. These analyses, derived from alignments of the rDNA ITS and D3 sequences, indicate that the strongly anhydrobiotic strains of Panagrolaimus form a single phylogenetic lineage, which is separate from the weakly anhydrobiotic strains. The weakly anhydrobiotic strains are also phylogenetically divergent from each other. Our data indicate that Panagrolaimus has the potential to be an excellent model system for the investigation of molecular aspects of nematode anhydrobiosis.
Background: Gene silencing by RNA interference (RNAi) is a powerful tool for functional genomics. Although RNAi was first described in Caenorhabditis elegans, several nematode species are unable to mount an RNAi response when exposed to exogenous double stranded RNA (dsRNA). These include the satellite model organisms Pristionchus pacificus and Oscheius tipulae. Available data also suggest that the RNAi pathway targeting exogenous dsRNA may not be fully functional in some animal parasitic nematodes. The genus Panagrolaimus contains bacterial feeding nematodes which occupy a diversity of niches ranging from polar, temperate and semi-arid soils to terrestrial mosses. Thus many Panagrolaimus species are adapted to tolerate freezing and desiccation and are excellent systems to study the molecular basis of environmental stress tolerance. We investigated whether Panagrolaimus is susceptible to RNAi to determine whether this nematode could be used in large scale RNAi studies in functional genomics.
Highlights 17 In contrast to equines, canine sport science has been poorly studied. 18 As the distance between consecutive upright hurdles increases, so do the take-off and 19 landing distances. 20 Take-off and landing distances further alter with the dog's skill level. 21 There are greater differences in jump kinematics when the distances between 22 consecutive hurdles are shorter. speeds differed for hurdle distances (P < 0.001) and level of skill (P < 0.001). There were 40 significant differences in apparent neck angle during take-off and landing (P < 0.001), lumbar 41 spine angles during take-off, bascule and landing (P < 0.01), and in shoulder angles during 42 the bascule phase (P < 0.05). The results indicate that agility dogs alter their jumping 43 patterns to accommodate the spacing between hurdles, which ultimately may impact long 44 term health and welfare due to altered kinematics.
12Research examining kinematic parameters of the canine athlete is markedly behind 13 equivalent human and equine research. With increasing participation and popularity, canine 14 sports science needs to bridge this gap with comparable equine research. The aim of this 15 study was to examine changes to specific kinematic parameters as hurdle height increases. 16Twenty border collies and border collie crosses were analysed jumping over a single hurdle at 17 increasing heights, starting with a pole on the floor and increasing to a maximum height of
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