Long‐term changes in the impacts of global warming on leaf phenology of four temperate tree species

Contrary to the generally advanced spring leaf unfolding under global warming, the effects of the climate warming on autumn leaf senescence are highly variable with advanced, delayed, and unchanged patterns being all reported. Using one million records of leaf phenology from four dominant temperate species in Europe, we investigated the temperature sensitivities of spring leaf unfolding and autumn leaf senescence (S_T, advanced or delayed days per degree Celsius). The S_T of spring phenology in all of the four examined species showed an increase and decrease during 1951–1980 and 1981–2013, respectively. The decrease in the S_T during 1981–2013 appears to be caused by reduced accumulation of chilling units. As with spring phenology, the S_T of leaf senescence of early successional and exotic species started to decline since 1980. In contrast, for late successional species, the S_T of autumn senescence showed an increase for the entire study period from 1951 to 2013. Moreover, the impacts of rising temperature associated with global warming on spring leaf unfolding were stronger than those on autumn leaf senescence. The timing of leaf senescence was positively correlated with the timing of leaf unfolding during 1951–1980. However, as climate warming continued, the differences in the responses between spring and autumn phenology gradually increased, so that the correlation was no more significant during 1981–2013. Our results further suggest that since 2000, due to the decreased temperature sensitivity of leaf unfolding the length of the growing season has not increased any more. These finding needs to be addressed in vegetation models used for assessing the effects of climate change.     

Sheltered from the storm? Population viability analysis of a rare endemic under periodic catastrophe regimes

Rare species are important targets for biodiversity conservation efforts because rarity often equates to small populations and increased endangerment. Rare species are prone to stochastic extinction events and may be particularly susceptible to catastrophes. Therefore, understanding how rare species respond to disturbances is critical for evaluating extinction risk and guiding conservation managers. Population viability analyses (PVAs) are essential for assessing rare species' status yet they seldom consider catastrophic events. Accordingly, we present a PVA of a rare tropical epiphyte, Lepanthes caritensis (Orchidaceae), under simulated disturbance regimes to evaluate its demographics and extinction risk. We aimed to test how demographic models incorporating catastrophes affect population viability estimates. Our goal was to better guide management of these orchids and other rare plants. Results revealed L. caritensis numbers have declined recently, but projected growth rates indicated that most subpopulations should increase in size if undisturbed. Still, projection models show that moderate catastrophes reduce growth rates, increase stochasticity in subpopulation sizes, and elevate extinction risk. Severe catastrophes had a more pronounced effect in simulations; growth rates fell below replacement level, there was greater variation in projected population sizes, and extinction risk was significantly higher. PVAs incorporating periodic catastrophes indicate that rare species may have greater extinction probabilities than standard models suggest. Thus, precautionary conservation measures should be taken in disturbance prone settings and we encourage careful monitoring after environmental catastrophes. Future rare plant PVAs should incorporate catastrophes and aim to determine if rescue and reintroduction efforts are necessary after disturbances to insure long-term population viability.     

Respiratory distress and neonatal lethality in mice lacking Golgi alpha1,2-mannosidase IB involved in N-glycan maturation

There are three mammalian Golgi alpha1,2-mannosidases, encoded by different genes, that form Man5GlcNAc2 from Man(8-9)GlcNAc2 for the biosynthesis of hybrid and complex N-glycans. Northern blot analysis and in situ hybridization indicate that the three paralogs display distinct developmental and tissue-specific expression. The physiological role of Golgi alpha1,2-mannosidase IB was investigated by targeted gene ablation. The null mice have normal gross appearance at birth, but they display respiratory distress and die within a few hours. Histology of fetal lungs the day before birth indicate some delay in development, whereas neonatal lungs show extensive pulmonary hemorrhage in the alveolar region. No significant histopathological changes occur in other tissues. No remarkable ultrastructural differences are detected between wild type and null lungs. The membranes of a subset of bronchiolar epithelial cells are stained with lectins from Phaseolus vulgaris (leukoagglutinin and erythroagglutinin) and Datura stramonium in wild type lungs, but this staining disappears in lungs from null mice. Mass spectrometry of N-glycans from different tissues shows no significant changes in global N-glycans of null mice. Therefore, only a few glycoproteins required for normal lung function depend on alpha1,2-mannosidase IB for maturation. There are no apparent differences in the expression of several lung epithelial cell and endothelial cell markers between null and wild type mice. The alpha1,2-mannosidase IB null phenotype differs from phenotypes caused by ablation of other enzymes in N-glycan biosynthesis and from other mouse gene disruptions that affect pulmonary development and function.     

Short-term effects of a "health-at-every-size" approach on eating behaviors and appetite ratings

Objective: To assess the effects of a “Health‐At‐Every‐Size” (HAES) intervention on eating behaviors and appetite ratings in 144 premenopausal overweight women. Research Methods and Procedures: Women were randomly assigned to one of the 3 groups: HAES group, social support (SS) group, and control group (N = 48 in each group). Interventions were conducted over a 4‐month period, and measurements were taken before and after this period. Eating behaviors (cognitive dietary restraint, disinhibition, and susceptibility to hunger) were evaluated by the Three‐Factor Eating Questionnaire. Appetite ratings (desire to eat, hunger, fullness, and prospective food consumption) were assessed by visual analogue scales before and after a standardized breakfast. Results: More important decreases in susceptibility to hunger and external hunger were observed in the HAES group when compared with the SS group (p = 0.05, for susceptibility to hunger) and the control group (p = 0.02 and p = 0.005, for susceptibility to hunger and external hunger, respectively). In addition, women from the HAES group had more important decreases in postprandial area under the curve for desire to eat (p = 0.02) and hunger (p = 0.04) when compared with the control group. The change in the desire to eat noted in the HAES group was also different from the one observed in SS group (p = 0.02). Women from the HAES group experienced significant weight loss at 4 months (?1.6 ± 2.5 kg, p < 0.0001), which did not differ significantly from the SS and control groups (p = 0.09). An increase in flexible restraint was significantly related to a greater weight loss in both HAES and SS groups (r = ?0.39, p < 0.01; and r = ?0.37, p < 0.05, respectively). A decrease in habitual susceptibility to disinhibition was also associated with a greater weight loss in HAES and control groups (r = 0.31, p < 0.05; and r = 0.44, p < 0.05, respectively). Discussion: These results suggest that a HAES intervention could have significant effects on eating behaviors and appetite ratings in premenopausal overweight women, when compared with an SS intervention or a control group.     

Speech and non-speech audio-visual illusions: a developmental study

It is well known that simultaneous presentation of incongruent audio and visual stimuli can lead to illusory percepts. Recent data suggest that distinct processes underlie non-specific intersensory speech as opposed to non-speech perception. However, the development of both speech and non-speech intersensory perception across childhood and adolescence remains poorly defined. Thirty-eight observers aged 5 to 19 were tested on the McGurk effect (an audio-visual illusion involving speech), the Illusory Flash effect and the Fusion effect (two audio-visual illusions not involving speech) to investigate the development of audio-visual interactions and contrast speech vs. non-speech developmental patterns. Whereas the strength of audio-visual speech illusions varied as a direct function of maturational level, performance on non-speech illusory tasks appeared to be homogeneous across all ages. These data support the existence of independent maturational processes underlying speech and non-speech audio-visual illusory effects.     

Embryonic death of Mek1-deficient mice reveals a role for this kinase in angiogenesis in the labyrinthine region of the placenta

Mek is a dual-specificity kinase that activates the extracellular-signal-regulated (Erk) mitogen-activated protein (MAP) kinases upon agonist binding to receptors. The Erk MAP kinase cascade is involved in cell-fate determination in many organisms. In mammals, this pathway is proposed to regulate cell growth and differentiation. Genetic studies have shown that although a single mek gene is present in Caenorhabditis elegans, Drosophila and Xenopus, two mek homologs, Mek1 and Mek2, are present in the mammalian cascade. In the present study, we describe a mutant mouse line in which the mek1 gene has been disrupted by insertional mutagenesis. The null mutation was recessive lethal, as the homozygous mutant embryos died at 10.5 days of gestation. Histopathological analyses revealed a reduction in vascularization of the placenta that was due to a marked decrease of vascular endothelial cells in the labyrinthine region. The failure to establish a functional placenta probably explains the death of the mek1-/- embryos. Cell-migration assays indicated that mek1-/- fibroblasts could not be induced to migrate by fibronectin, although the levels of Mek2 protein and Erk activation were normal. Re-expression of Mek1 in the mutant mouse embryonic fibroblasts (MEFs) restored their ability to migrate. Our findings provide genetic evidence that establishes the unique role played by Mek1 in signal transduction. They also suggest that mek1 function is required for normal response to angiogenic signals that might promote vascularization of the labyrinthine region of the placenta.     

Characterization of remnant-like particles isolated by immunoaffinity gel from the plasma of type III and type IV hyperlipoproteinemic patients

Previous studies have investigated the potential atherogenicity and thrombogenicity of triglyceride-rich lipoprotein (TRL) remnants by isolating them from plasma within a remnant-like particle (RLP) fraction, using an immunoaffinity gel containing specific anti-apoB-100 and anti-apoA-I antibodies. In order to characterize lipoproteins in this RLP fraction and to determine to what extent their composition varies from one individual to another, we have used automated gel filtration chromatography to determine the size heterogeneity of RLP isolated from normolipidemic control subjects (n = 8), and from type III (n = 6) and type IV (n = 9) hyperlipoproteinemic patients, who by selection had similarly elevated levels of plasma triglyceride (406 +/- 43 and 397 +/- 35 mg/dl, respectively). Plasma RLP triglyceride, cholesterol, apoB, apoC-III, and apoE concentrations were elevated 2- to 6-fold (P < 0. 05) in hyperlipoproteinemic patients compared to controls. RLP fractions of type III patients were enriched in cholesterol and apoE compared to those of type IV patients, and RLP of type IV patients were enriched in triglyceride and apoC-III relative to those of normolipidemic subjects. In normolipidemic subjects, the majority of RLP had a size similar to LDL or HDL. The RLP of hyperlipoproteinemic patients were, however, larger and were similar in size to TRL, or were intermediate in size (i.e., ISL) between that of TRL and LDL. Compared to controls, ISL in the RLP fraction of type III patients were enriched in apoE relative to apoC-III, whereas in type IV patients they were enriched in apoC-III relative to apoE. These results demonstrate that: 1) RLP are heterogeneous in size and composition in both normolipidemic and hypertriglyceridemic subjects, and 2) the apoE and apoC-III composition of RLP is different in type III compared to type IV hyperlipoproteinemic patients.