The Prevalence and Implications of Human–Animal Co-Sleeping in an Australian Sample

Sleep research is characterized by an interest in humans, with the realm of animal sleep left largely to ethologists and animal scientists. However, the lives of sleep-study participants and those with sleep problems frequently involve animals. For the majority of the population in developed countries who own pets, their waking lives are impacted by the duties of animal care and ownership. For many, their sleeping lives are also impacted through sharing their bedrooms or their beds with pets. Yet, little is known about the prevalence of human–animal co-sleeping relationships or their impact on sleep. The aim of this study was to determine the prevalence and implications of human–animal co-sleeping in an Australian sample. The study uses data collected from the 2012 Sealy Sleep Census, a national online survey of sleep wellness that included a sample of 10,128 after data cleaning. The population of respondents (aged 18–74) who co-slept with pets (n = 1,018 or 10% of the sample) was then matched to a sample of respondents who did not co-sleep with pets, according to gender and age. Those who co-slept with pets took longer to fall asleep (p = 0.029), were more likely to wake up tired (p = 0.025), and although they were not more likely to wake up due to a disturbance, those who did had a greater chance of being disturbed by dog barking/animals making noises (p < 0.001). However, there were no significant differences found in total self-reported sleep length or feelings of tiredness during the day. The continued practice of co-sleeping with pets suggests that there may be some benefits such as social support and social interaction, and increased feelings of personal security. The survey provides a preliminary understanding of the prevalence and implications of human–animal co-sleeping, and highlights areas for further examination of its implications on sleep research and clinical practice.     

A base-centred explanation of the B-to-A transition in DNA

In the traditional view, the bistable feature responsible for the switch between the B and A forms of DNA was the sugar-phosphate backbone. Several recent assays of the sequence-dependent structure of DNA are not compatible with that hypothesis. Here we show that certain kinds of base-pair step, mainly those of the pyrimidine-purine variety, can stack in a “bistable” fashion so as to produce one of two overall helix shapes A or B. Further, we suggest that the passive, elastic stiffness of the backbone is responsible for communicating the stacking configuration from bistable steps to their “neutral” neighbours. The role of water molecules, in stabilizing the B form of DNA over the A, may simply be to form hydrogen-bonded bridges with the minor-groove edges of neutral steps in the B configuration.     

Characterization of a membrane-associated protein kinase of multidrug-resistant HL60 cells which phosphorylates P-glycoprotein

Cells containing increased levels of the membrane phosphoprotein P-glycoprotein exhibit a multidrug-resistant phenotype. In the present study we have analyzed protein kinases capable of phosphorylating P-glycoprotein in membranes of HL60 cells isolated for resistance to vincristine. Analysis of this system demonstrates that in isolated membranes the protein kinase inhibitor staurosporine greatly reduces P-glycoprotein phosphorylation. In contrast, the kinase inhibitor H-7 does not affect this reaction. Fractionation of solubilized membrane proteins from sensitive and resistant cells on DEAE-cellulose reveals a major protein kinase (PK-1) which exhibits optimal activity in the presence of Mn2+ and histone H1. This enzyme fraction does not contain detectable levels of protein kinase C or cAMP-dependent protein kinase. PK-1 phosphorylation of two endogenous proteins is, however, greatly enhanced in the presence of phosphatidylserine or phosphatidyl-inositol. In reaction mixtures containing Mg2+ or Mn2+ in the absence of phospholipid, PK-1 from resistant cells phosphorylates an endogenous protein of 180 kilodaltons (P180), which exhibits an electrophoretic mobility identical to P-glycoprotein. In parallel experiments with PK-1 from sensitive cells there is no detectable phosphorylation of a P180 protein. P180 phosphorylated by PK-1 from resistant cells is immunoprecipitated by antibody against P-glycoprotein. Additional studies demonstrate that PK-1 is capable of phosphorylating specific synthetic peptides which correspond to the sequence of P-glycoprotein. Peptide phosphorylation occurs at both serine and threonine residues. These studies thus identify a novel membrane-associated protein kinase in HL60 cells which is capable of phosphorylating P-glycoprotein. This enzyme may have an important role in regulating levels of multidrug resistance.     

Luminescence Resonance Energy Transfer to Study Conformational Changes in Membrane Proteins Expressed in Mammalian Cells

Luminescence Resonance Energy Transfer, or LRET, is a powerful technique used to measure distances between two sites in proteins within the distance range of 10-100 Å. By measuring the distances under various ligated conditions, conformational changes of the protein can be easily assessed. With LRET, a lanthanide, most often chelated terbium, is used as the donor fluorophore, affording advantages such as a longer donor-only emission lifetime, the flexibility to use multiple acceptor fluorophores, and the opportunity to detect sensitized acceptor emission as an easy way to measure energy transfer without the risk of also detecting donor-only signal. Here, we describe a method to use LRET on membrane proteins expressed and assayed on the surface of intact mammalian cells. We introduce a protease cleavage site between the LRET fluorophore pair. After obtaining the original LRET signal, cleavage at that site removes the specific LRET signal from the protein of interest allowing us to quantitatively subtract the background signal that remains after cleavage. This method allows for more physiologically relevant measurements to be made without the need for purification of protein.