Distribution of picophytoplankton communities from brackish to hypersaline waters in a South Australian coastal lagoon

Background Picophytoplankton (i.e. cyanobacteria and pico-eukaryotes) are abundant and ecologically critical components of the autotrophic communities in the pelagic realm. These micro-organisms colonized a variety of extreme environments including high salinity waters. However, the distribution of these organisms along strong salinity gradient has barely been investigated. The abundance and community structure of cyanobacteria and pico-eukaryotes were investigated along a natural continuous salinity gradient (1.8% to 15.5%) using flow cytometry. Results Highest picophytoplankton abundances were recorded under salinity conditions ranging between 8.0% and 11.0% (1.3 × 106 to 1.4 × 106 cells ml-1). Two populations of picocyanobacteria (likely Synechococcus and Prochlorococcus) and 5 distinct populations of pico-eukaryotes were identified along the salinity gradient. The picophytoplankton cytometric-richness decreased with salinity and the most cytometrically diversified community (4 to 7 populations) was observed in the brackish-marine part of the lagoon (i.e. salinity below 3.5%). One population of pico-eukaryote dominated the community throughout the salinity gradient and was responsible for the bloom observed between 8.0% and 11.0%. Finally only this halotolerant population and Prochlorococcus-like picocyanobacteria were identified in hypersaline waters (i.e. above 14.0%). Salinity was identified as the main factor structuring the distribution of picophytoplankton along the lagoon. However, nutritive conditions, viral lysis and microzooplankton grazing are also suggested as potentially important players in controlling the abundance and diversity of picophytoplankton along the lagoon. Conclusions The complex patterns described here represent the first observation of picophytoplankton dynamics along a continuous gradient where salinity increases from 1.8% to 15.5%. This result provides new insight into the distribution of pico-autotrophic organisms along strong salinity gradients and allows for a better understanding of the overall pelagic functioning in saline systems which is critical for the management of these precious and climatically-stress ecosystems

Prokaryotic aminopeptidase activity along a continuous salinity gradient in a hypersaline coastal lagoon (the Coorong, South Australia)

The distribution and aminopeptidase activity of prokaryotes were investigated along a natural continuous salinity gradient in a hypersaline coastal lagoon, the Coorong, South Australia. The abundance of prokaryotes significantly increased from brackish to hypersaline waters and different sub-populations, defined by flow cytometry, were observed along the salinity gradient. While four sub-populations were found at each station, three additional ones were observed for 8.3% and 13.4%, suggesting a potential modification in the composition of the prokaryotic communities and/or a variation of their activity level along the salinity gradient. The aminopeptidase activity highly increased along the gradient and salinity appeared as the main factor favouring this enzymatic activity. However, while the aminopeptidase activity was dominated by free enzymes for salinities ranging from 2.6% to 13.4%, cell-attached aminopeptidase activity was predominant in more saline waters (i.e. 15.4%). Changes in substrate structure and availability, strongly related to salinity, might (i) modify patterns of both aminopeptidase activities (free and cell-associated enzymes) and (ii) obligate the prokaryotic communities to modulate rapidly their aminopeptidase activity according to the nutritive conditions available along the gradient

A two-phase model for smoothly joining disparate growth phases in the macropodid Thylogale billardierii

Generally, sigmoid curves are used to describe the growth of animals over their lifetime. However, because growth rates often differ over an animal's lifetime a single curve may not accurately capture the growth. Broken-stick models constrained to pass through a common point have been proposed to describe the different growth phases, but these are often unsatisfactory because essentially there are still two functions that describe the lifetime growth. To provide a single, converged model to age animals with disparate growth phases we developed a smoothly joining two-phase nonlinear function (SJ2P), tailored to provide a more accurate description of lifetime growth of the macropod, the Tasmanian pademelon Thylogale billardierii. The model consists of the Verhulst logistic function, which describes pouch-phase growth--joining smoothly to the Brody function, which describes post-pouch growth. Results from the model demonstrate that male pademelons grew faster and bigger than females. Our approach provides a practical means of ageing wild pademelons for life history studies but given the high variability of the data used to parametrise the second growth phase of the model, the accuracy of ageing of post-weaned animals is low: accuracy might be improved with collection of longitudinal growth data. This study provides a unique, first robust method that can be used to characterise growth over the lifespan of pademelons. The development of this method is relevant to collecting age-specific vital rates from commonly used wildlife management practices to provide crucial insights into the demographic behaviour of animal populations.Financial support was provided by the Tasmanian Community Forest Agreement: Alternatives to 1080 Programme. In-kind support was provided by the University of Tasmania

Reliability and validity of a life course passive smoke exposure questionnaire in an australian cohort from childhood to adulthood

Objectives:Life course exposure to passive smoke may predict health, but there are few validated measures. We tested the reliability and validity of a retrospective life course passive smoking questionnaire. Methods:Participants from the third follow-up of the Childhood Determinants of Adult Health study (2014-2019, ages 36-49 years) retrospectively reported mother/father/other household member smoking when living at home during childhood, including duration (years) and smoking location (never/sometimes/always inside house). The severity of exposure index (SEI; sum of mother/father/other years smoked multiplied by smoking location), cumulative years of exposure (CYE; sum of mother/father/other years), and total household smokers (THS) were derived. The reliability of retrospective passive smoking reports was examined with intraclass correlation coefficients (ICCs) using household smoking reported 34 years earlier in 1985 by participants when aged 7-15 years. Construct validity was examined by correlating retrospective passive smoking with participants’ smoking in adulthood and lung function in childhood and adulthood. Results:Among 2082 participants (mean±standard deviation [SD], 45.0±2.5 years; 55.2% females), THS ranged from 0 to 5 (mean± SD, 0.9±1.0), CYE ranged from 0 to 106 (mean±SD, 10.5±13.9), and SEI ranged from 0 to 318 (mean±SD, 24.4±36.0). Retrospective measures showed moderate agreement with total household smokers reported in childhood (ICC, 0.58 to 0.62). The retrospective measures were weakly but significantly (pConclusions:The retrospective passive smoking questionnaire showed reasonable reliability and validity. This measure may be useful for epidemiological studies.</p

The Association Between Grip Strength Measured in Childhood, Young- and Mid-adulthood and Prediabetes or Type 2 Diabetes in Mid-adulthood

Background Although low child and adult grip strength is associated with adverse cardiometabolic health, how grip strength across the life course associates with type 2 diabetes is unknown. This study identified the relative contribution of grip strength measured at specific life stages (childhood, young adulthood, mid-adulthood) with prediabetes or type 2 diabetes in mid-adulthood.Methods Between 1985 and 2019, 263 participants had their grip strength measured using an isometric dynamometer in childhood (9-15 years), young adulthood (28-36 years) and mid-adulthood (38-49 years). In mid-adulthood, a fasting blood sample was collected and tested for glucose and glycated haemoglobin (HbA1c). Participants were categorized as having prediabetes or type 2 diabetes if fasting glucose levels were >= 5.6 mmol or if HbA1c levels were >= 5.7% (>= 39 mmol/mol). A Bayesian relevant life course exposure model examined the association between lifelong grip strength and prediabetes or type 2 diabetes.Results Grip strength at each time point was equally associated with prediabetes or type 2 diabetes in mid-adulthood (childhood: 37%, young adulthood: 36%, mid-adulthood: 28%). A one standard deviation increase in cumulative grip strength was associated with 34% reduced odds of prediabetes or type 2 diabetes in mid-adulthood (OR 0.66, 95% credible interval 0.40, 0.98).Conclusions Greater grip strength across the life course could protect against the development of prediabetes and type 2 diabetes. Strategies aimed at increasing muscular strength in childhood and maintaining behaviours to improve strength into adulthood could improve future cardiometabolic health.</div

Muscular strength across the life course: The tracking and trajectory patterns of muscular strength between childhood and mid-adulthood in an Australian cohort

ObjectivesLow muscular strength is a risk factor for current and future adverse health outcomes. However, whether levels of muscular strength persist, or track, and if there are distinct muscular strength trajectories across the life course is unclear. This study aimed to explore muscular strength trajectories between childhood and mid-adulthood.DesignProspective longitudinal study.MethodsChildhood Determinants of Adult Health Study participants had their muscular strength (right and left handgrip, shoulder extension and flexion, and leg strength measured by hand-held, shoulder and leg-back dynamometers, and a combined strength score) assessed in childhood, young adulthood and mid-adulthood. The tracking of muscular strength was quantified between childhood and mid-adulthood (n = 385) and young- and mid-adulthood (n = 822). Muscular strength trajectory patterns were identified for participants who had their muscular strength assessed at least twice across the life course (n = 1280).ResultsLevels of muscular strength were persistent between childhood and mid-adulthood and between young- and mid-adulthood, with the highest tracking correlations observed for the combined strength score (childhood to mid-adulthood: r = 0.47, p ConclusionsWeak children are likely to become weak adults in midlife unless strategies aimed at increasing muscular strength levels are introduced. Whether interventions aimed at increasing muscular strength could be implemented in childhood to help establish favourable muscular strength trajectories across the life course and in turn, better future health, warrant further attention.</p

A Two-Phase Model for Smoothly Joining Disparate Growth Phases in the Macropodid Thylogale billardierii

Generally, sigmoid curves are used to describe the growth of animals over their lifetime. However, because growth ratesoften differ over an animal&rsquo;s lifetime a single curve may not accurately capture the growth. Broken-stick models constrainedto pass through a common point have been proposed to describe the different growth phases, but these are oftenunsatisfactory because essentially there are still two functions that describe the lifetime growth. To provide a single,converged model to age animals with disparate growth phases we developed a smoothly joining two-phase nonlinearfunction (SJ2P), tailored to provide a more accurate description of lifetime growth of the macropod, the Tasmanianpademelon Thylogale billardierii. The model consists of the Verhulst logistic function, which describes pouch-phase growth&ndash; joining smoothly to the Brody function, which describes post-pouch growth. Results from the model demonstrate thatmale pademelons grew faster and bigger than females. Our approach provides a practical means of ageing wildpademelons for life history studies but given the high variability of the data used to parametrise the second growth phaseof the model, the accuracy of ageing of post-weaned animals is low: accuracy might be improved with collection oflongitudinal growth data. This study provides a unique, first robust method that can be used to characterise growth overthe lifespan of pademelons. The development of this method is relevant to collecting age-specific vital rates fromcommonly used wildlife management practices to provide crucial insights into the demographic behaviour of animalpopulations

Impact of within-visit systolic blood pressure change patterns on blood pressure classification : the Cardiovascular Risk in Young Finns Study

AIMS: Most international guidelines recommend that repeat blood pressure (BP) readings are required for BP classification. Two international guidelines diverge from this by recommending that no further BP measurements are required if the first clinic BP is below a hypertension threshold. The extent to which within-visit BP variability patterns change over time, and whether this could impact BP classification is unknown. We sought to examine this. METHODS AND RESULTS: Data were from the Cardiovascular Risk in Young Finns Study, a prospective cohort study. Up to 2799 participants were followed from childhood (9-15 years) to adulthood (18-49 years) over up to six visits. Patterns of within-visit systolic BP (SBP) variability were defined as no-change, decrease, increase between consecutive readings (with 5 mmHg change thresholds). Classification of SBP (normal, high-normal, hypertension) using the first reading was compared with repeat readings. On average, SBP decreased with subsequent measures, but with major individual variability (no-change: 56.9-62.7%; decrease: 24.1-31.6%; increase: 11.5-16.8%). Patterns of SBP variability were broadly similar from childhood to adulthood, with the highest prevalence of an increase among participants categorized with normal SBP (12.6-20.3%). The highest prevalence of SBP reclassification occurred among participants with hypertension (28.9-45.3% reclassified as normal or high-normal). The prevalence of reclassification increased with the magnitude of change between readings. CONCLUSION: There is a major individual variation of within-visit SBP change in childhood and adulthood and can influence BP classification. This highlights the importance of consistency among guidelines recommending that repeat BP measurements are needed for BP classification.publishedVersionPeer reviewe

Within-visit SBP variability from childhood to adulthood and markers of cardiovascular end-organ damage in mid-life

Background: Within-visit SBP variability is associated with age and SBP, but its long-term clinical significance is unknown. We examined the association between child, adult, and life-time within-visit SBP variability with markers of end-organ damage using data from a 31-year longitudinal study.Methods: Within-visit SBP variability was calculated as the standard deviation of three sitting SBP readings among up to 3010 participants aged 6-18 years (childhood) who were re-measured up to seven times to mid-adulthood. Markers of cardiovascular end-organ damage in adulthood were carotid intima-media thickness, brachial flow-mediated dilatation, carotid distensibility, pulse wave velocity, left ventricular mass index, carotid plaque, and coronary artery calcification.Results: The mean (standard deviation) cumulative within-visit SBP variability was 2.7 (1.5) mmHg in childhood, 3.9 (1.9) mmHg in adulthood and 3.7 (1.5) mmHg across the observed life-time. Childhood within-visit SBP variability was not correlated with its subsequent values measured from 3 to 31 years later. With adjustment for age, sex, cumulative SBP, BMI and serum lipids, neither child, adult, or life-time cumulative within-visit SBP variability associated with markers of cardiovascular end-organ damage. However, higher child, adult, and life-time cumulative SBP significantly associated with higher carotid intima-media thickness, higher pulse wave velocity, lower brachial flow-mediated dilatation, lower carotid distensibility in adulthood.Conclusion: Within-visit SBP variability from childhood to adulthood does not provide additional predictive utility over SBP over the same period of the life course.</p

Age-Specific Estimates and Comparisons of Youth Tri-Ponderal Mass Index and Body Mass Index in Predicting Adult Obesity-Related Outcomes

ObjectivesTo estimate and compare tri-ponderal mass index (TMI) and body mass index (BMI) at each age from childhood to young adulthood in the prediction of adulthood obesity-related outcomes.Study designParticipants of this observational study (n = 432) were from a 20-year infancy-onset randomized atherosclerosis prevention trial. BMI and TMI were calculated using weight and height measured annually from participants between ages 2 and 20 years. Outcomes were aortic intima-media thickness (at the age of 15, 17, or 19 years), impaired fasting glucose and elevated insulin levels, homeostasis model assessment of insulin resistance index, serum lipids, and hypertension at the age of 20 years. Poisson regressions, Pearson correlation, logistic regression, and area under the curve (AUC) were used to estimate and/or compare associations and predictive utilities between BMI and TMI with all outcomes.ResultsThe associations and predictive utilities of BMI and TMI with all outcomes were stronger at older ages. BMI had significantly stronger correlations than TMI with insulin (at age 16 years), systolic blood pressure (age 5-20 years), and triglycerides (age 18 years). BMI had significantly greater predictive utilities than TMI for insulin resistance (at age 14-16 years; difference in AUC = 0.018-0.024), elevated insulin levels (age 14-16 years; difference in AUC = 0.018 and 0.025), and hypertension (age 16 to 20 years; difference in AUC = 0.017-0.022) but they were similar for other outcomes.ConclusionsTMI is not superior to BMI at any ages from childhood to young adulthood in the prediction of obesity-related outcomes in young adulthood.</p