Growth response to climate and drought change along an aridity gradient in the southernmost Pinus nigra relict forests

Tree populations at the rear edge of species distribution are sensitive to climate stress and drought. However, growth responses of these tree populations to those stressors may vary along climatic gradients. To analyze growth responses to climate and drought using dendrochronology in rear-edge Pinus nigra populations located along an aridity gradient. Tree-ring width chronologies were built for the twentieth century and related to monthly climatic variables, a drought index (Standardized Precipitation-Evapotranspiration Index), and two atmospheric circulation patterns (North Atlantic and Western Mediterranean Oscillations). Growth was enhanced by wet and cold previous autumns and warm late winters before tree-ring formation. The influence of the previous year conditions on growth increased during the past century. Growth was significantly related to North Atlantic and Western Mediterranean Oscillations in two out of five sites. The strongest responses of growth to the drought index were observed in the most xeric sites. Dry conditions before tree-ring formation constrain growth in rear-edge P. nigra populations. The comparisons of climate-growth responses along aridity gradients allow characterizing the sensitivity of relict stands to climate warming.

Site and Age Condition the Growth Responses to Climate and Drought of Relict Pinus nigra subsp. salzmannii Populations in Southern Spain

To assess if tree age may modulate the main climatic drivers of radial growth, two relict Pinus nigra subsp. salzmannii populations (Maria, most xeric site; Magina, least xeric site) were sampled in southern Spain near the limits of the species range. Tree-ring width residual chronologies for two age groups (mature trees, age <= 100 years (minimum 40 years); old trees, age > 100 years) were built to evaluate their responses to climate by relating them to monthly precipitation and temperature and a drought index (DRI) using correlation and response functions. We found that drought is the main driver of growth of relict P. nigra populations, but differences between sites and age classes were also observed. First, growth in the most xeric site depends on the drought severity during the previous autumn and the spring of the year of tree-ring formation, whereas in the relatively more mesic site growth is mainly enhanced by warm and wet conditions in spring. Second, growth of mature trees responded more to drought severity than that of old trees. Our findings indicate that drought severity will mainly affect growth of relict P. nigra populations dominated by mature trees in xeric sites. This conclusion may also apply to similar mountain Mediterranean conifer relicts.

Anti insulin-like growth factor I receptor immunoliposomes: a single formulation combining two anticancer treatments with enhanced therapeutic efficiency

Context: Through overexpression and aberrant activation in many human tumors, the IGF system plays a key role in tumor development and tumor cell proliferation. Different strategies targeting IGF-I receptor (IGFI-R) have been developed, and recent studies demonstrated that combined treatments with cytostatic drugs enhance the potency of anti-IGFI-R therapies. Objective: The objective of the study was to examine the IGFI-R expression status in neuroendocrine tumors of the gastroenteropancreatic system (GEP-NETs) in comparison with healthy tissues and use potential overexpression as a target for novel anti-IGFI-R immunoliposomes. Experimental Design: A human tumor tissue array and samples from different normal tissues were investigated by immunohistochemistry. An IGFI-R antagonistic antibody (1H7) was coupled to the surface of sterically stabilized liposomes loaded with doxorubicin. Cell lines from different tumor entities were investigated for liposomal association studies in vitro. For in vivo experiments, neuroendocrine tumor xenografts were used for evaluation of pharmacokinetic and therapeutic properties of the novel compound. Results: Immunohistochemistry revealed significant IGFI-R overexpression in all investigated GEP-NETs (n = 59; staining index, 229.1 +/- 3.1%) in comparison with normal tissues (115.7 +/- 3.7%). Furthermore, anti-IGFI-R immunoliposomes displayed specific tumor cell association (44.2 +/- 1.6% vs. IgG liposomes, 0.8 +/- 0.3%; P < 0.0001) and internalization in human neuroendocrine tumor cells in vitro and superior antitumor efficacy in vivo (life span 31.5 +/- 2.2 d vs. untreated control, 19 +/- 0.6, P = 0.008). Conclusion: IGFI-R overexpression seems to be a common characteristic of otherwise heterogenous NETs. Novel anti-IGFI-R immunoliposomes have been developed and successfully tested in a preclinical model for human GEP-NETs. Moreover in vitro experiments indicate that usage of this agent could also present a promising approach for other tumor entities.

Autosomal-dominant isolated growth hormone deficiency (IGHD type II) with normal GH-1 gene

BACKGROUND: Autosomal-dominant isolated GH deficiency (IGHD) is a rare disorder that is commonly believed to be due to heterozygous mutations in the GH-1 gene (GH-1). These mutations cause the production of a protein that affects the release of the product of the normal allele. Rarely, heterozygous mutations in the gene encoding for HESX-1 gene (HESX-1) may cause autosomal-dominant IGHD, with penetrance that has been shown to be variable in both humans and mice. SUBJECTS AND METHODS: We have sequenced the whole GH-1 in the index cases of 30 families with autosomal-dominant IGHD. In all the families other possible causes of GH deficiency and other pituitary hormones deficits were excluded. We here describe the clinical, biochemical and radiological picture of the families without GH-1 mutations. In these families, we also sequenced the HESX-1. RESULTS: The index cases of the five families with autosomal-dominant IGHD had normal GH-1, including the intronic sequences. They had no HESX-1 mutations. CONCLUSION: This study shows that GH-1 mutations are absent in 5/30 (16.6%) of the families with autosomal-dominant IGHD and raises the possibility that mutations in other gene(s) may be involved in IGHD with this mode of transmission.

GH mutant (R77C) in a pedigree presenting with the delay of growth and pubertal development: structural analysis of the mutant and evaluation of the biological activity

A heterozygous missense mutation in the GH-1 gene converting codon 77 from arginine (R) to cysteine (C), which was previously reported to have some GH antagonistic effect, was identified in a Syrian family. The index patient, a boy, was referred for assessment of his short stature (-2.5 SDS) at the age of 6 years. His mother and grandfather were also carrying the same mutation, but did not differ in adult height from the other unaffected family members. Hormonal examination in all affected subjects revealed increased basal GH, low IGF-I concentrations, and subnormal IGF-I response in generation test leading to the diagnosis of partial GH insensitivity. However, GH receptor gene (GHR) sequencing demonstrated no abnormalities. As other family members carrying the GH-R77C form showed similar alterations at the hormonal level, but presented with normal final height, no GH therapy was given to the boy, but he was followed through his pubertal development which was delayed. At the age of 20 years he reached his final height, which was normal within his parental target height. Functional characterization of the GH-R77C, assessed through activation of Jak2/Stat5 pathway, revealed no differences in the bioactivity between wild-type-GH (wt-GH) and GH-R77C. Detailed structural analysis indicated that the structure of GH-R77C, in terms of disulfide bond formation, is almost identical to that of the wt-GH despite the introduced mutation (Cys77). Previous studies from our group demonstrated a reduced capability of GH-R77C to induce GHR/GH-binding protein (GHBP) gene transcription rate when compared with wt-GH. Therefore, reduced GHR/GHBP expression might well be the possible cause for the partial GH insensitivity found in our patients. In addition, this group of patients deserve further attention because they could represent a distinct clinical entity underlining that an altered GH peptide may also have a direct impact on GHR/GHBP gene expression causing partial GH insensitivity. This might be responsible for the delay of growth and pubertal development. Finally, we clearly demonstrate that GH-R77C is not invariably associated with short stature, but that great care needs to be taken in ascribing growth failure to various heterozygous mutations affecting the GH-IGF axis and that careful functional studies are mandatory.

Evaluation of the biological activity of a growth hormone (GH) mutant (R77C) and its impact on GH responsiveness and stature

CONTEXT AND OBJECTIVE: A single missense mutation in the GH-1 gene converting codon 77 from arginine (R) to cysteine (C) yields a mutant GH-R77C peptide, which was described as natural GH antagonist. DESIGN, SETTING, AND PATIENTS: Heterozygosity for GH-R77C/wt-GH was identified in a Syrian family. The index patient, a boy, was referred for assessment of his short stature (-2.5 SD score) and partial GH insensitivity was diagnosed. His mother and grandfather were also carrying the same mutation and showed partial GH insensitivity with modest short stature. INTERVENTIONS AND RESULTS: Functional characterization of the GH-R77C was performed through studies of GH receptor binding and activation of Janus kinase 2/Stat5 pathway. No differences in the binding affinity and bioactivity between wt-GH and GH-R77C were found. Similarly, cell viability and proliferation after expression of both GH peptides in AtT-20 cells were identical. Quantitative confocal microscopy analysis revealed no significant difference in the extent of subcellular colocalization between wt-GH and GH-R77C with endoplasmic reticulum, Golgi, or secretory vesicles. Furthermore studies demonstrated a reduced capability of GH-R77C to induce GHR/GHBP gene transcription rate when compared with wt-GH. CONCLUSION: Reduced GH receptor/GH-binding protein expression might be a possible cause for the partial GH insensitivity with delay in growth and pubertal development found in our patients. In addition, this group of patients deserves further attention because they could represent a distinct clinical entity underlining that an altered GH peptide may also have a direct impact on GHR/GHBP gene expression causing partial GH insensitivity.

Myocardial salvage through coronary collateral growth by granulocyte colony-stimulating factor in chronic coronary artery disease: a controlled randomized trial

BACKGROUND: The efficacy of granulocyte colony-stimulating factor (G-CSF) for coronary collateral growth promotion and thus impending myocardial salvage has not been studied so far, to our best knowledge. METHODS AND RESULTS: In 52 patients with chronic stable coronary artery disease, age 62+/-11 years, the effect on a marker of myocardial infarct size (ECG ST segment elevation) and on quantitative collateral function during a 1-minute coronary balloon occlusion was tested in a randomized, placebo-controlled, double-blind fashion. The study protocol before coronary intervention consisted of occlusive surface and intracoronary lead ECG recording as well as collateral flow index (CFI, no unit) measurement in a stenotic and a > or =1 normal coronary artery before and after a 2-week period with subcutaneous G-CSF (10 microg/kg; n=26) or placebo (n=26). The CFI was determined by simultaneous measurement of mean aortic, distal coronary occlusive, and central venous pressure. The ECG ST segment elevation >0.1 mV disappeared significantly more often in response to G-CSF (11/53 vessels; 21%) than to placebo (0/55 vessels; P=0.0005), and simultaneously, CFI changed from 0.121+/-0.087 at baseline to 0.166+/-0.086 at follow-up in the G-CSF group, and from 0.152+/-0.082 to 0.131+/-0.071 in the placebo group (P<0.0001 for interaction of treatment and time). The absolute change in CFI from baseline to follow-up amounted to +0.049+/-0.062 in the G-CSF group and to -0.010+/-0.060 in the placebo group (P<0.0001). CONCLUSIONS: Subcutaneous G-CSF is efficacious during a short-term protocol in improving signs of myocardial salvage by coronary collateral growth promotion.

Mutation analysis of the muscarinic cholinergic receptor genes in isolated growth hormone deficiency type IB

BACKGROUND: Isolated GH deficiency (IGHD) is familial in 5-30% of patients. The most frequent form (IGHD-IB) has autosomal recessive inheritance, and it is known that it can be caused by mutations in the GHRH receptor (GHRHR) gene or in the GH gene. However, most forms of IGHD-IB have an unknown genetic cause. In normal subjects, muscarinic cholinergic stimulation causes an increase in pituitary GH release, whereas its blockade has the opposite effect, suggesting that a muscarinic acetylcholine receptor (mAchR) is involved in stimulating GH secretion. Five types of mAchR (M(1)-M(5)) exist. A transgenic mouse in which the function of the M(3) receptor was selectively ablated in the central nervous system has isolated GH deficiency similar to animals with defective GHRH or GHRHR gene. OBJECTIVE: We hypothesized that mAchR mutations may cause a subset of familial IGHD. PATIENTS/METHODS: After confirming the expression of M(1)-M(5) receptor mRNA in human hypothalamus, we analyzed the index cases of 39 families with IGHD-IB for mutations in the genes encoding for the five receptors. Coding sequences for each of the five mAchRs were subjected to direct sequencing. RESULTS: In one family, an affected member was homozygous for a M(3) change in codon 65 that replaces valine with isoleucine (V65I). The V65I receptor was expressed in CHO cells where it had normal ability to transmit methacholine signaling. CONCLUSION: mAchR mutations are absent or rare (less than 2.6%) in familial IGHD type IB.

Selection and hydroponic growth of bread wheat cultivars for bioregenerative life support systems

As part of the ESA-funded MELiSSA program, the suitability, the growth and the development of four bread wheat cultivars were investigated in hydroponic culture with the aim to incorporate such a cultivation system in an Environmental Control and Life Support System (ECLSS). Wheat plants can fulfill three major functions in space: (a) fixation of CO2 and production of O2, (b) production of grains for human nutrition and (c) production of cleaned water after condensation of the water vapor released from the plants by transpiration. Four spring wheat cultivars (Aletsch, Fiorina, Greina and CH Rubli) were grown hydroponically and compared with respect to growth and grain maturation properties. The height of the plants, the culture duration from germination to harvest, the quantity of water used, the number of fertile and non-fertile tillers as well as the quantity and quality of the grains harvested were considered. Mature grains could be harvested after around 160 days depending on the varieties. It became evident that the nutrient supply is crucial in this context and strongly affects leaf senescence and grain maturation. After a first experiment, the culture conditions were improved for the second experiment (stepwise decrease of EC after flowering, pH adjusted twice a week, less plants per m2) leading to a more favorable harvest (higher grain yield and harvest index). Considerably less green tillers without mature grains were present at harvest time in experiment 2 than in experiment 1. The harvest index for dry matter (including roots) ranged from 0.13 to 0.35 in experiment 1 and from 0.23 to 0.41 in experiment 2 with modified culture conditions. The thousand-grain weight for the four varieties ranged from 30.4 to 36.7 g in experiment 1 and from 33.2 to 39.1 g in experiment 2, while market samples were in the range of 39.4–46.9 g. Calcium levels in grains of the hydroponically grown wheat were similar to those from field-grown wheat, while potassium, magnesium, phosphorus, iron, zinc, copper, manganese and nickel levels tended to be higher in the grains of experimental plants. It remains a challenge for future experiments to further adapt the nutrient supply in order to improve senescence of vegetative plant parts, harvest index and the composition of bread wheat grains.

Relaxation of species-specific neighborhood effects in Bornean rain forest under climatic perturbation

Evidence of negative conspecific density dependence (NDD) operating on seedling survival and sapling recruitment has accumulated recently. In contrast, evidence of NDD operating on growth of trees has been circumstantial at best. Whether or not local NDD at the level of individual trees leads to NDD at the level of the community is still an open question. Moreover, whether and how perturbations interfere with these processes have rarely been investigated. We applied neighborhood models to permanent plot data from a Bornean dipterocarp forest censused over two 10-11 year periods. Although the first period was only lightly perturbed, a moderately strong El Nino event causing severe drought occurred in the first half of the second period. Such events are an important component of the environmental stochasticity affecting the region. We show that local NDD on growth of small-to-medium-sized trees may indeed translate to NDD at the level of the community. This interpretation is based on increasingly negative effects of bigger conspecific neighbors on absolute growth rates of individual trees with increasing basal area across the 18 most abundant overstory species in the first period. However, this relationship was much weaker in the second period. We interpreted this relaxation of local and community-level NDD as a consequence of increased light levels at the forest floor due to temporary leaf and twig loss of large trees in response to the drought event. Mitigation of NDD under climatic perturbation acts to decrease species richness, especially in forest overstory and therefore has an important role in determining species relative abundances at the site.

Current and future variations of nutrient depositions and influences on tree growth

Current nutrient deposition shows episodic variations which likely may impact the local nutrient cycle at the RBSF. Comparing analyses of deposition data during present-day atmospheric circulation and phases of high biomass burning in the Amazon, characteristic relationships between remote emissions and local deposition are determined. By using projections drawn from the special report on emission scenarios (SRES) in combination with a trajectory modeling tool, future nutrient deposition conditions of the mountain ecosystem are assessed. Observations of relations between climatic variables, current time series of nutrient deposition, and tree growth point to an impact of the remote fertilization effect of atmospheric matters, emitted primarily by human activities like biomass burning and agricultural and industrial sources. The increasing emissions in the future may have adverse effects on the ecosystem in the long run.

Tree growth response along an elevational gradient: climate or genetics?

Environment and genetics combine to influence tree growth and should therefore be jointly considered when evaluating forest responses in a warming climate. Here, we combine dendroclimatology and population genetic approaches with the aim of attributing climatic influences on growth of European larch (Larix decidua) and Norway spruce (Picea abies). Increment cores and genomic DNA samples were collected from populations along a ~900-m elevational transect where the air temperature gradient encompasses a ~4 °C temperature difference. We found that low genetic differentiation among populations indicates gene flow is high, suggesting that migration rate is high enough to counteract the selective pressures of local environmental variation. We observed lower growth rates towards higher elevations and a transition from negative to positive correlations with growing season temperature upward along the elevational transect. With increasing elevation there was also a clear increase in the explained variance of growth due to summer temperatures. Comparisons between climate sensitivity patterns observed along this elevational transect with those from Larix and Picea sites distributed across the Alps reveal good agreement, and suggest that tree-ring width (TRW) variations are more climate-driven than genetics-driven at regional and larger scales. We conclude that elevational transects are an extremely valuable platform for understanding climatic-driven changes over time and can be especially powerful when working within an assessed genetic framework.

Declining pine growth in Central Spain coincides with increasing diurnal temperature range since the 1970s

Growing evidence suggests environmental change to be most severe across the semi-arid subtropics, with past, present and projected drying of the Mediterranean Basin posing a key multidisciplinary challenge. Consideration of a single climatic factor, however, often fails to explain spatiotemporal growth dynamics of drought-prone ecosystems. Here, we present annually resolved and absolutely dated ring width measurements of 871 Scots pines (Pinus sylvestris) from 18 individual plot sites in the Central Spanish Pinar Grande forest reserve. Although comprising tree ages from 6 to 175 years, this network correlates surprisingly well with the inverse May–July diurnal temperature range (r = 0.84; p < 0.00011956–2011). Ring width extremes were triggered by pressure anomalies of the North Atlantic Oscillation, and the long-term growth decline coincided with Iberian-wide drying since the mid-1970s. Climate model simulations not only confirm this negative trend over the last decades but also project drought to continuously increase over the 21st century. Associated ecological effects and socio-economic consequences should be considered to improve adaptation strategies of agricultural and forest management, as well as biodiversity conservation and ecosystem service.

Site- and species-specific responses of forest growth to climate across the European continent

Aim To evaluate the climate sensitivity of model-based forest productivity estimates using a continental-scale tree-ring network. Location Europe and North Africa (30–70° N, 10° W–40° E). Methods We compiled close to 1000 annually resolved records of radial tree growth for all major European tree species and quantified changes in growth as a function of historical climatic variation. Sites were grouped using a neural network clustering technique to isolate spatiotemporal and species-specific climate response patterns. The resulting empirical climate sensitivities were compared with the sensitivities of net primary production (NPP) estimates derived from the ORCHIDEE-FM and LPJ-wsl dynamic global vegetation models (DGVMs). Results We found coherent biogeographic patterns in climate response that depend upon (1) phylogenetic controls and (2) ambient environmental conditions delineated by latitudinal/elevational location. Temperature controls dominate forest productivity in high-elevation and high-latitude areas whereas moisture sensitive sites are widespread at low elevation in central and southern Europe. DGVM simulations broadly reproduce the empirical patterns, but show less temperature sensitivity in the boreal zone and stronger precipitation sensitivity towards the mid-latitudes. Main conclusions Large-scale forest productivity is driven by monthly to seasonal climate controls, but our results emphasize species-specific growth patterns under comparable environmental conditions. Furthermore, we demonstrate that carry-over effects from the previous growing season can significantly influence tree growth, particularly in areas with harsh climatic conditions – an element not considered in most current-state DGVMs. Model–data discrepancies suggest that the simulated climate sensitivity of NPP will need refinement before carbon-cycle climate feedbacks can be accurately quantified.