Can differences in phosphorus uptake kinetics explain the distribution of cattail and sawgrass in the Florida Everglades?

<p>Abstract</p> <p>Background</p> <p>Cattail (<it>Typha domingensis</it>) has been spreading in phosphorus (P) enriched areas of the oligotrophic Florida Everglades at the expense of sawgrass (<it>Cladium mariscus </it>spp. <it>jamaicense</it>). Abundant evidence in the literature explains how the opportunistic features of <it>Typha </it>might lead to a complete dominance in P-enriched areas. Less clear is how <it>Typha </it>can grow and acquire P at extremely low P levels, which prevail in the unimpacted areas of the Everglades.</p> <p>Results</p> <p>Apparent P uptake kinetics were measured for intact plants of <it>Cladium </it>and <it>Typha </it>acclimated to low and high P at two levels of oxygen in hydroponic culture. The saturated rate of P uptake was higher in <it>Typha </it>than in <it>Cladium </it>and higher in low-P acclimated plants than in high-P acclimated plants. The affinity for P uptake was two-fold higher in <it>Typha </it>than in <it>Cladium</it>, and two- to three-fold higher for low-P acclimated plants compared to high-P acclimated plants. As <it>Cladium </it>had a greater proportion of its biomass allocated to roots, the overall uptake capacity of the two species at high P did not differ. At low P availability, <it>Typha </it>increased biomass allocation to roots more than <it>Cladium</it>. Both species also adjusted their P uptake kinetics, but <it>Typha </it>more so than <it>Cladium</it>. The adjustment of the P uptake system and increased biomass allocation to roots resulted in a five-fold higher uptake per plant for <it>Cladium </it>and a ten-fold higher uptake for <it>Typha</it>.</p> <p>Conclusions</p> <p>Both <it>Cladium </it>and <it>Typha </it>adjust P uptake kinetics in relation to plant demand when P availability is high. When P concentrations are low, however, <it>Typha </it>adjusts P uptake kinetics and also increases allocation to roots more so than <it>Cladium</it>, thereby improving both efficiency and capacity of P uptake. <it>Cladium </it>has less need to adjust P uptake kinetics because it is already efficient at acquiring P from peat soils (e.g., through secretion of phosphatases, symbiosis with arbuscular mycorrhizal fungi, nutrient conservation growth traits). Thus, although <it>Cladium </it>and <it>Typha </it>have qualitatively similar strategies to improve P-uptake efficiency and capacity under low P-conditions, <it>Typha </it>shows a quantitatively greater response, possibly due to a lesser expression of these mechanisms than <it>Cladium</it>. This difference between the two species helps to explain why an opportunistic species such as <it>Typha </it>is able to grow side by side with <it>Cladium </it>in the P-deficient Everglades.</p

Maternal pre-pregnancy obesity and timing of puberty in sons and daughters: a population-based cohort study.

BackgroundIn many countries, an increased prevalence of obesity in pregnancy has coincided with a declining pubertal age. We aimed to explore the potential effect of maternal pre-pregnancy overweight and obesity on timing of puberty in sons and daughters.MethodsBetween 2012 and 2018, 15 819 of 22 439 invited children from the Danish National Birth Cohort, born 2000-03, provided half-yearly information from the age of 11 years on the pubertal milestones: Tanner stages, voice break, first ejaculation, menarche, acne and axillary hair. We estimated adjusted mean monthly differences (with 95% confidence intervals) in age at attaining the pubertal milestones for children exposed to maternal pre-pregnancy obesity [body mass index (BMI) ≥30.0 kg/m2] or overweight (BMI 25.0 to 29.9 kg/m2) with normal weight (BMI 18.5 to 24.9 kg/m2) as reference. In mediation analysis, we explored whether childhood BMI at age 7 years mediated the associations.ResultsMaternal pre-pregnancy obesity was associated with earlier age at attaining most pubertal milestones in sons, and pre-pregnancy overweight and obesity were associated with earlier age at attaining all pubertal milestones in daughters. When combining all pubertal milestones, pre-pregnancy obesity [sons: -1.5 (-2.5, -0.4) months; daughters: -3.2 (-4.2, -2.1) months] and overweight [daughters only: -2.6 (-3.3, -1.8) months] were associated with earlier timing of puberty. The associations in sons were completely mediated by higher childhood BMI and partly so in daughters.ConclusionsMaternal pre-pregnancy obesity appears to lower timing of puberty through childhood obesity in sons and mainly through other mechanisms in daughters

Animal Models to Translate Phage Therapy to Human Medicine

Phagotherapy, the use of bacteriophages to fight bacterial infections as an alternative to antibiotic treatments, has become of increasing interest in the last years. This is mainly due to the diffusion of multi-drug resistant (MDR) bacterial infections that constitute a serious issue for public health. Phage therapy is gaining favor due to its success in agriculture and veterinary treatments and its extensive utilization for human therapeutic protocols in the Eastern world. In the last decades, some clinical trials and compassionate treatments have also been performed in the Western world, indicating that phage therapy is getting closer to its introduction in standard therapy protocols. However, several questions concerning the use of phages in human therapeutic treatments are still present and need to be addressed. In this review, we illustrate the state of art of phage therapy and examine the role of animal models to translate these treatments to humans

Cooperative Learning Approach to Delivering Professional Modules to Bachelor and Master Students: TPU Experience

Modern tendencies in engineering education set certain requirements on the competences to be obtained. To enable a future engineer to work at a highly competitive level and become an internationally recognized specialist, they must possess advanced English speaking and writing skills. At present most universities introduce educational programs that attract bright domestic and international students to ensure that they are in demand at the global market. The Strategic Program on Competitiveness Enhancement of National Research Tomsk Polytechnic University proposes that modules of professional training should be developed and delivered in English as a language of instruction so that the quality of teaching could be raised. To develop their own approaches to teaching, improve their language proficiency and develop courses and their elements in English, TPU teachers are to meet these challenging requirements and design course documentation and teaching aids, and engage modern teaching approaches in order to ensure high quality work with student groups which are often mixed in their abilities in both professional subjects and language proficiency levels. This paper addresses the course "Professional Training in English" which was developed upon completion of the joint program of TPU and the University of Southampton "Delivering through the Medium of English" and has successfully been delivered to bachelor students with the major "Oil and Gas Engineering" using the cooperative learning approach. The cooperative learning approach has proved to be one of the most successful in terms of teaching professional English to groups of students with mixed abilities

Risk of selection bias due to non-participation in a cohort study on pubertal timing.

BackgroundNon-participation in aetiologic studies of pubertal timing is frequent. However, little effort has been given to explore the risk and potential impact of selection bias in studies of pubertal timing.ObjectiveWe aimed to explore the risk of selection bias due to non-participation in a newly established puberty cohort.MethodsWe evaluated whether three maternal exposures chosen a priori (pre-pregnancy obesity, smoking, and alcohol drinking during pregnancy) were associated with participation, whether pubertal timing was associated with participation, and whether selection bias influenced the associations between these exposures and pubertal timing. In total, 22 439 children from the Danish National Birth Cohort born 2000-2003 were invited to the Puberty Cohort and 15 819 (70%) participated. Exposures were self-reported during pregnancy. Pubertal timing was measured using a previously validated marker, "the height difference in standard deviations" (HD:SDS), which is the difference between pubertal height and adult height, both in standard deviations. For this study, pubertal height at around 13 years in sons and around 11 years in daughters was obtained from an external database, and adult height was predicted based on parental height reported by mothers.ResultsParticipation was associated with most exposures but not with pubertal timing, measured by HD:SDS. The associations between exposures and HD:SDS were comparable for participants only and all invited for participation.ConclusionIn conclusion, the risk of selection bias in aetiologic studies on pubertal timing in the Puberty Cohort appears minimal

Sex differences in cardiovascular responses to orthostatic challenge in healthy older persons: A pilot study

Background Premenopausal women show a higher incidence of orthostatic hypotension than age-matched men, but there are limited data available on sex differences in cardiovascular responses to orthostatic challenge in healthy older persons. We investigated sex differences in hemodynamic and autonomic responses to orthostatic challenge in healthy older males and females. Materials and methods Fourteen older healthy women and 10 age-matched men performed a sit-to-stand test (5 min of sitting followed by 5 min of standing). A Task Force® Monitor continuously measured the following beat-to-beat hemodynamic parameters: heart rate, systolic blood pressure, diastolic blood pressure, mean blood pressure, stroke index, cardiac index, and total peripheral resistance index. Cardiac autonomic activity, low-frequency (LF: 0.04–0.15 Hz) normalized (LFnuRRI) and high-frequency (HF: 0.15–0.4 Hz) normalized (HFnuRRI) components, and the ratio between LF and HF power (LF/HF) were calculated using power spectral analysis of heart rate variability. Results Across all hemodynamic parameters, there were no significant differences between the sexes at baseline and during standing. LFnuRRI (median: 70.2 vs. 52.3, p < 0.05) and LF/HF ratio (median: 2.4 vs. 1.1, p < 0.05) were significantly higher, whereas HFnuRRI (median: 29.8 vs. 47.7, p < 0.05) was lower among women at baseline. All other heart rate variability measures did not differ between the sexes. Conclusions The data indicate that older women showed higher sympathetic and lower parasympathetic activity at rest compared to age-matched men. These results are contradictory to the observations from previous studies, which showed a reduced sympathetic and enhanced parasympathetic activity in women in all ages. Further studies are required to determine the underlying mechanisms contributing to higher incidence of orthostatic hypotension in older females