👤 Jill Marie Ferry

Classification of physical activity (PA) depends on the cut-point method used to allocate PA counts from accelerometer measurements. This study investigates how three validated cut-point methods affect the time spent in various levels of PA and sedentary behaviour (SB), and how they impact toddlers estimated adherence to PA guidelines. PA was assessed using an ActiGraph wGT3X-BT accelerometer in a cohort of 653 two-year-old children participating in the Toddler Milk Intervention study. Children wearing the ActiGraph for at least four days, with a minimum of six hours wear-time per day, were included. Time spent in SB and different activity levels were estimated according to three cut-point methods and were standardized to individual mean wear-time. We used one cut-point method based on the vertical axis (VA) (Trost VA), with an epoch length of 15 s and two cut-point methods based on either the VA (Costa VA) or on the vector magnitude (VM) (Costa VM) with an epoch length of five seconds. Estimates of SB and PA for each method were compared with repeated measures ANOVA. The time toddlers spent in PA was significantly different depending on the cut-point methods. Costa VM classified on average 62 min (95% CI 61, 64] more per day as SB and 57 min (95% CI -58, -56] less per day as LPA compared to Trost VA (both p < 0.0001). For MVPA, the mean difference between Costa VA and Trost VA was 6.8 min (95% CI -7, -6; p < 0.0001). Concurrently, the proportion of children meeting the WHO recommendation of 180 min of total PA differed between cut-point methods, with 86% according to Costa VM and 97% according to Trost VA. The time toddlers engage in different intensities of PA is significantly determined by the selection of cut-point method. Notably, the use of a different cut-point method leads up to a 10% difference in the estimated time spent in LPA and SB, but only a 1% difference of moderate-vigorous PA. These differences change the estimated adherence to recommendations. Future research is needed to standardize the data processing methods for better comparability between studies analysing toddlers' PA. ClinicalTrials.gov, TRN: NCT02907502, Registration Date: 31 August 2016. Show less

Cells have evolved complex regulatory networks that reorganize gene expression patterns in response to changing environmental conditions. These changes often involve redundant mechanisms that affect various levels of gene expression. Here, we examine the consequences of enhanced mRNA degradation in the galactose utilization network of Saccharomyces cerevisiae. We observe that glucose-induced degradation of GAL1 transcripts provides a transient growth advantage to cells upon addition of glucose. We show that the advantage arises from relief of translational competition between GAL1 transcripts and those of cyclin CLN3, a translationally regulated initiator of cell division. This competition creates a translational bottleneck that balances the production of Gal1p and Cln3p and represents a posttranscriptional control mechanism that enhances the cell's ability to adapt to changes in carbon source. We present evidence that the spatial regulation of GAL1 and CLN3 transcripts is what allows growth to be maintained during fluctuations of glucose availability. Our results provide unique insights into how cells optimize energy use during growth in a dynamic environment. Show less

The major tyrosine protein kinase, HPK40, isolated from HL-60, the preparation of which is described elsewhere (Ernould, A.P., Ferry, G., Barret, J.M., Genton, A. and Boutin, J.A., Eur. J. Biochem., 214, 503-514), was investigated as to its specificity on a number of peptides and proteins. It was found that HPK40 can phosphorylate histones (except histone H4), casein, acid-treated enolase, actin and tubulin but not calmodulin. Phosphorylation specificity of HPK40 was investigated using over a hundred peptidic structures. HPK40 is not related to the 'src' family and does not phosphorylate efficiently either the tetrapeptide NEYT derived from the pp60src autophosphorylation domain or the corresponding peptide RRsrc, RRLIED-NEYTARG. VALYDYESR from the SH3 domain of pp60c-src is recognized as a substrate with a high phosphorylation level. DEDYIQD, derived from the phosvitin/casein kinase II, was also highly phosphorylated. In order to determine the minimal recognition sequence of HPK40, the phosphorylation of about 60 dito tetrapeptides was investigated. Some of the tetrapeptides, such as *EEYE and NEYE, were well phosphorylated. Even some tripeptides, such as EYE, DYM, TYS and KYE, were recognized by HPK40, while none of the tested dipeptides was recognized as substrate. Sequences of peptides from DRVYHPF (angiotensin), LEEEEEAYGWMDF (minigastrin) and QEEYSAM (from H-ras1) were examined as substrates. The presence of one or several acidic residues on the N alpha-side of tyrosine residue was identified as the only apparently favorable determinant.(ABSTRACT TRUNCATED AT 250 WORDS) Show less