Change in drivers of mangrove crown displacement along a salinity stress gradient

1. Crown displacement in trees is an adaptive response driven by neighbours that optimizes space use and reduces competition. But it can also be the result of wind force. Although morphological responses to neighbours have been well studied, the interplay between neighbours and wind in driving crown shape, and the implications for plant interactions remain poorly understood. However, it is crucial to predict such changes in vegetation structure and function under the scope of global change. We test the hypothesis that aboveground interactions are reduced with increasing soil stress and that wind becomes the main driver of crown shape in mangrove forests. 2. We investigated the effect of neighbours and wind intensity and direction on crown displacement of mangrove canopy and below canopy trees along a salinity gradient, and assessed crown asymmetry for three mangrove tree species, as well as the contribution of crown displacement on reducing crown‐projected area overlap and thus neighbourhood competition. 3. Results show that crown displacement of canopy trees is strongly influenced by winds at all salinities. At low salinities, competition for space accounted for 48% of crown displacement away from neighbours, compared to 49% found for the synthetized effects of wind and neighbours. While trees below the canopy displace their crowns away from their neighbours, no response to wind could be detected. This can be due to the wind protection conferred by a dense canopy stand related to bigger crowns that effectively reduce wind drag. At higher salinities, there was a reduction in canopy overlap due to crown displacement, which suggests reduced aboveground plant interactions with increasing soil stress. 4. While neighbourhood avoidance is a fundamental strategy for optimal light foraging, this study shows that wind strength and directionality are main drivers of crown shape with increasing stress and highlights their potential influence in plant interactions and forest structure, pointing to an increased susceptibility of trees to disturbances that should be further studied

An Alu Element–Associated Hypermethylation Variant of the POMC Gene Is Associated with Childhood Obesity

The individual risk for common diseases not only depends on genetic but also on epigenetic polymorphisms. To assess the role of epigenetic variations in the individual risk for obesity, we have determined the methylation status of two CpG islands at the POMC locus in obese and normal-weight children. We found a hypermethylation variant targeting individual CpGs at the intron2–exon3 boundary of the POMC gene by bisulphite sequencing that was significantly associated with obesity. POMC exon3 hypermethylation interferes with binding of the transcription enhancer P300 and reduces expression of the POMC transcript. Since intron2 contains Alu elements that are known to influence methylation in their genomic vicinity, the exon3 methylation variant seems to result from an Alu element–triggered default state of methylation boundary definition. Exon3 hypermethylation in the POMC locus represents the first identified DNA methylation variant that is associated with the individual risk for obesity

Global variability in leaf respiration in relation to climate, plant functional types and leaf traits

• Leaf dark respiration (Rdark) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of Rdark and associated leaf traits. • Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed-effects models were used to disentangle sources of variation in Rdark. • Area-based Rdark at the prevailing average daily growth temperature (T) of each site increased only twofold from the Arctic to the tropics, despite a 20°C increase in growing T (8–28°C). By contrast, Rdark at a standard T (25°C, Rdark25) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher Rdark25 at a given photosynthetic capacity (Vcmax25) or leaf nitrogen concentration ([N]) than species at warmer sites. Rdark25 values at any given Vcmax25 or [N] were higher in herbs than in woody plants. • The results highlight variation in Rdark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of Rdark in terrestrial biosphere models (TBMs) and associated land-surface components of Earth system models (ESMs)

Future directions of mangrove modeling: IBMbedding

info:eu-repo/semantics/publishe

Individual-based modeling of mangrove forest growth: MesoFON – Recent calibration and future direction

We introduce individual-based models (IBMs) of mangrove forests and criticize the tasks for their development recommended previously for being mostly related to natural threats. This is contrasted with our perspective that the key research question of today's models should be to mitigate anthropogenic threats. Core objective (1) of this article is to provide a review of mangrove threats prioritizing solution-oriented IBM approaches. Because species-specific calibration of IBMs is time-consuming, efficiency is crucial. Globally, we identify an urgent need to parametrize Asian mangrove species. We suggest IBMs to unveil management scenarios with maximum sustainable timber yield to prevent mangrove conversion and over-exploitation. The key model purpose regarding natural threats is to govern the management of mangrove forest stability for coastal protection using a combination of windthrow models and IBMs. We argue for the embedding of IBMs in ecosystem models to achieve purposes regarding eutrophication and altered hydrology/sedimentation. Core objective (2) is to describe the development of the new IBM mesoFON from a task-to a solution-oriented model. Initially, the interaction of lateral crown displacement and hurricane impacts was examined with mesoFON. Later, we introduced propagule production & local dispersal with the task to close the tree life cycle. Here, we describe the change in purpose of mesoFON accompanying its calibration for Rhizophora apiculata in Malaysia. For this we applied a Genetic Algorithm optimizer, used mesoFON as a “way-back machine”, initialized it with observed tree diameters/positions and shrank the trees backwards in time. Objective(3) is to describe mesoFON's future direction: Embedding in the General Ecosystem Model (Fitz et al. 1996) and targeting the solution of threats at larger spatial scales. Finally, we demonstrate that the new model simulates overland waterflow qualitatively right even in benchmark settings.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

J. Clin. Endocrinol. Metab.

Objective: Congenital hypothyroidism occurs in 1:3500 live births and is therefore the most common congenital endocrine disorder. A spectrum of defective thyroid morphology, termed thyroid dysgenesis (TD), represents 80% of permanent congenital hypothyroidism cases. Although several candidate genes have been implicated in thyroid development, comprehensive screens failed to detect mutation carriers in a significant number of patients with nonsyndromic TD. Due to the sporadic occurrence of TD, de novo chromosomal rearrangements are conceivably representing one of the molecular mechanisms participating in its etiology. Methods: The introduction of array comparative genomic hybridization (CGH) has provided the ability to map DNA copy number variations (CNVs) genome wide with high resolution. We performed an array CGH screen of 80 TD patients to determine the role of CNVs in the etiology of the disease. Results: We identified novel CNVs that have not been described as frequent variations in the healthy population in 8.75% of all patients. These CNVs exclusively affected patients with athyreosis or thyroid hypoplasia and were nonrecurrent, and the regions flanking the CNVs were not enriched for segmental duplications. Conclusions: The high rate of chromosomal changes in TD argues for an involvement of CNVs in the etiology of this disease. Yet the lack of recurrent aberrations suggests that the genetic causes of TD are heterogenous and not restricted to specific genomic hot spots. Thus, future studies may have to shift the focus from singling out specific genes to the identification of deregulated pathways as the underlying cause of the disease

Respiratory alkalosis in children with febrile seizures

Purpose: Febrile seizures (FS) are the most common type of convulsive events in children. FS are suggested to result from a combination of genetic and environmental factors. However, the pathophysiologic mechanisms underlying FS remain unclear. Using an animal model of experimental FS, it was demonstrated that hyperthermia causes respiratory alkalosis with consequent brain alkalosis and seizures. Here we examine the acid-base status of children who were admitted to the hospital for FS. Children who were admitted because of gastroenteritis (GE), a condition known to promote acidosis, were examined to investigate a possible protective effect of acidosis against FS. Methods: We enrolled 433 age-matched children with similar levels of fever from two groups presented to the emergency department. One group was admitted for FS (n = 213) and the other for GE (n = 220). In the FS group, the etiology of fever was respiratory tract infection (74.2%), otitis media (7%), GE (7%), tonsillitis (4.2%), scarlet fever (2.3%) chickenpox (1.4%), urinary tract infection (1.4%), postvaccination reaction (0.9%), or unidentified (1.4%). In all patients, capillary pH and blood Pco(2) were measured immediately on admission to the hospital. Key Findings: Respiratory alkalosis was found in children with FS (pH 7.46 +- 0.04, [mean +- standard deviation] Pco(2) 29.5 +- 5.5 mmHg), whereas a metabolic acidosis was seen in all children admitted for GE (pH 7.31 +- 0.03, Pco(2) 37.7 +- 4.3 mmHg; p < 0.001 for both parameters). No FS were observed in the latter group. A subgroup (n = 15; 7%) of the patients with FS had GE and, notably, their blood pH was more alkaline (pH 7.44 +- 0.04) than in the GE-admitted group. During the enrollment period, eight of the patients were admitted on separate occasions because of FS or GE. Consistent with the view that generation of FS requires a genetic susceptibility in addition to acute seizure triggering factors, each of these patients had an alkalotic blood pH when admitted because of FS, whereas they had an acidotic pH (and no FS) when admitted because of GE (pH 7.47 +- 0.05 vs. pH 7.33 +- 0.03, p < 0.005). Significance: The results show that FS are associated with a systemic respiratory alkalosis, irrespective of the severity of the underlying infection as indicated by the level of fever. The lack of FS in GE patients is attributable to low pH, which also explains the fact that children with a susceptibility to FS do not have seizures when they have GE-induced fever that is associated with acidosis. The present demonstration of a close link between FS and respiratory alkalosis may pave the way for further clinical studies and attempts to design novel therapies for the treatment of FS by controlling the systemic acid-base status

Modelling mangrove-mudflat dynamics with a coupled individual-based-hydro-morphodynamic model

As climate-change-driven extremes potentially make coastal areas more vulnerable, mangroves can help sustainably protect the coasts. There is a substantial understanding of both mangrove dynamics and hydro-morphodynamic processes. However, the knowledge of complex eco-geomorphic interactions with physical-environmental stressors remains lacking. We introduce a novel coupled modelling approach consisting of an individual-based mangrove (mesoFON) and a process-based hydromorphodynamic model (Delft3D-FM). This coupled model is unique because it resolves spatiotemporal processes, including tidal, seasonal, and decadal environmental changes (water level, flow, sediment availability, and salinity) with full life-stages (propagule, seedling, sapling, mature) mangrove interaction. It allows us to mechanistically simulate forest expansion, retreat, and colonisation influenced by and with feedback on physical-environmental drivers. The model is applied in a schematized mixed fluvial-tidal deltaic mangrove forest in dominantly muddy sediment inspired by the prograding delta of Porong, Indonesia. Model results successfully reproduce observed mangrove extent development, age-height relationship, and morphodynamic delta features.Coastal Engineerin

Tree parameters

Tree parameters (stem diameter, height and crown radii in eight cardinal directions) for 12 mangrove forest stands located along a soil salinity gradient within the mangrove forest of the Lagoon of La Mancha, located in the central Gulf Coast of Mexico. The data set was used to study the responses of tree crowns to asymmetric neighbourhood pressure and dominant wind direction. The data set was created in collaboration between The Institute of Ecology (INECOL, Mexico), and the Technische Universitaet Dresden (Dresden, Germany), under the scope of the Coastal Research Network for Environmental Change (CREC), financed by the European Commission