Airborne ethylene may alter antioxidant protection and reduce tolerance of holm oak to heat and drought stress

Plant-emitted ethylene has received considerable attention as a stress hormone and is considered to play a major role at low concentrations in the tolerance of several species to biotic and abiotic stresses. However, airborne ethylene at high concentrations, such as those found in polluted areas (20-100 nL L(-1)) for several days, has received far less attention in studies of plant stress tolerance, though it has been shown to alter photosynthesis and reproductive stages (seed germination, flowering, and fruit ripening) in some species. To assess the potential effects of airborne ethylene on plant stress tolerance in polluted areas, the extent of oxidative stress, photo- and antioxidant protection, and visual leaf area damage were evaluated in ethylene-treated (approximately 100 nL L(-1) in air) and control (without ethylene fumigation) holm oak (Quercus ilex) plants exposed to heat stress or to a combination of heat and drought stress. Control plants displayed tolerance to temperatures as high as 50 degrees C, which might be attributed, at least in part, to enhanced xanthophyll de-epoxidation and 2-fold increases in alpha-tocopherol, and they suffered oxidative stress only when water deficit was superimposed on temperatures above 45 degrees C. By contrast, ethylene-treated plants showed symptoms of oxidative stress at lower temperatures (35 degrees C) than the controls in drought, as indicated by enhanced malondialdehyde levels, lower alpha-tocopherol and ascorbate concentrations, and a shift of the redox state of ascorbate to its oxidized form. In addition, ethylene-treated plants showed higher visual leaf area damage and greater reductions in the maximum efficiency of the PSII photochemistry than controls in response to heat stress or to a combination of heat and drought stress. These results demonstrate for the first time that airborne ethylene at concentrations similar to those found in polluted areas may reduce plant stress tolerance by altering, among other possible mechanisms, antioxidant defenses.     

Mutations in the DLG3 gene cause nonsyndromic X-linked mental retardation

We have identified truncating mutations in the human DLG3 (neuroendocrine dlg) gene in 4 of 329 families with moderate to severe X-linked mental retardation. DLG3 encodes synapse-associated protein 102 (SAP102), a member of the membrane-associated guanylate kinase protein family. Neuronal SAP102 is expressed during early brain development and is localized to the postsynaptic density of excitatory synapses. It is composed of three amino-terminal PDZ domains, an src homology domain, and a carboxyl-terminal guanylate kinase domain. The PDZ domains interact directly with the NR2 subunits of the NMDA glutamate receptor and with other proteins responsible for NMDA receptor localization, immobilization, and signaling. The mutations identified in this study all introduce premature stop codons within or before the third PDZ domain, and it is likely that this impairs the ability of SAP102 to interact with the NMDA receptor and/or other proteins involved in downstream NMDA receptor signaling pathways. NMDA receptors have been implicated in the induction of certain forms of synaptic plasticity, such as long-term potentiation and long-term depression, and these changes in synaptic efficacy have been proposed as neural mechanisms underlying memory and learning. The disruption of NMDA receptor targeting or signaling, as a result of the loss of SAP102, may lead to altered synaptic plasticity and may explain the intellectual impairment observed in individuals with DLG3 mutations.     

Use of mixed infections to study cell invasion and intracellular proliferation of Salmonella enterica in eukaryotic cell cultures

Epithelial cell lines are widely used as an in vitro model to study cell invasion by Salmonella. In turn, phagocytic cell lines are used to study Salmonella intracellular survival and proliferation. We describe a novel method, derived from the classical mixed infection procedure, to quantify invasion and proliferation defects in Salmonella enterica serovar Typhimurium. A eukaryotic cell culture is infected with two strains (e.g., a mutant and the wild-type). After infection, bacterial cells that remain extracellular are eliminated with gentamicin. At the end of the trial, intracellular bacteria are recovered and plated. Colonies from each strain are then counted for the calculation of a competitive index. Strain discrimination can be achieved either with antibiotic resistance markers or using plasmids encoding color markers (e.g., fluorescent proteins). Because both strains are exposed to the same conditions throughout the process, the procedure decreases the variability between independent trials and allows a direct measurement of the impairment of the mutant in invasion or intracellular proliferation.     

Plant VOC emissions: making use of the unavoidable

All plants emit substantial amounts of phytogenic volatile organic compounds (PVOCs), which include alkanes, alkenes, alcohols, aldehydes, eters, esters and carboxylic acids. Defence, communication and/or protection against extreme conditions have been proposed as reasons for these emissions. However, Rosenstiel and colleagues have recently proposed that emission of PVOCs represents a metabolic 'safety valve' by preventing the unnecessary sequestration of phosphates. Additionally, Niinemets and colleagues suggest that the emission rates of some PVOCs are determined by the principal physicochemical characteristics of the emitted compounds, such as their solubility, volatility and diffusivity, rather than by physiological mechanisms, such as their synthesis rates. These two new studies lead to the hypothesis that there is not necessarily a specific role for every PVOC emitted, given that their emission is unavoidable as result of their volatility. However, in some cases, natural selection has worked to take advantage of this volatility.     

Use of gesture sequences in chimpanzees

Gestural communication in a group of 19 captive chimpanzees (Pan troglodytes) was observed, with particular attention paid to gesture sequences (combinations). A complete inventory of gesture sequences is reported. The majority of these sequences were repetitions of the same gestures, which were often tactile gestures and often occurred in play contexts. Other sequences combined gestures within a modality (visual, auditory, or tactile) or across modalities. The emergence of gesture sequences was ascribed to a recipient's lack of responsiveness rather than a premeditated combination of gestures to increase the efficiency of particular gestures. In terms of audience effects, the chimpanzees were sensitive to the attentional state of the recipient, and therefore used visually-based gestures mostly when others were already attending, as opposed to tactile gestures, which were used regardless of whether the recipient was attending or not. However, the chimpanzees did not use gesture sequences in which the first gesture served to attract the recipient's visual attention before they produced a second gesture that was visually-based. Instead, they used other strategies, such as locomoting in front of the recipient, before they produced a visually-based gesture.     

Real-time quantitative PCR-based system for determining transgene copy number in transgenic animals

In this paper, we describe a rapid and accurate real-time quantitative PCR-based system to determine transgene copy number in transgenic animals. We used the 2(-deltadeltaCt) method to analyze different transgenic lines without the requirement of a control sample previously determined by Southern blot analysis. To determine the transgene copy number in several mouse lines carrying a goat beta-Lactoglobulin transgene, we developed a TaqMan assay in which a goat genomic DNA sample was used as a calibrator. Moreover, we used the glucagon gene as a reference control because this gene is highly conserved between species and amplifies with the same efficiency and sensitivity in goat as in mouse. With this assay, we provide an alternative simple method to determine the transgene copy number, avoiding the traditional and tedious blotting techniques. The assay's discrimination ability from our results is of at least six copies and, similar to the limitations of the blotting techniques, the accuracy of the quantification diminishes when the transgene copy number is high.     

The capacity for thermal protection of photosynthetic electron transport varies for different monoterpenes in Quercus ilex

Heat stress resistance of foliar photosynthetic apparatus was investigated in the Mediterranean monoterpene-emitting evergreen sclerophyll species Quercus ilex. Leaf feeding with fosmidomycin, which is a specific inhibitor of the chloroplastic isoprenoid synthesis pathway, essentially stopped monoterpene emission and resulted in the decrease of the optimum temperature of photosynthetic electron transport from approximately 38 degrees C to approximately 30 degrees C. The heat stress resistance was partly restored by fumigation with 4 to 5 nmol mol(-1) air concentrations of monoterpene alpha-pinene but not with fumigations with monoterpene alcohol alpha-terpineol. Analyses of monoterpene physicochemical characteristics demonstrated that alpha-pinene was primarily distributed to leaf gas and lipid phases, while alpha-terpineol was primarily distributed to leaf aqueous phase. Thus, for a common monoterpene uptake rate, alpha-terpineol is less efficient in stabilizing membrane liquid-crystalline structure and as an antioxidant in plant membranes. Furthermore, alpha-terpineol uptake rate (U) strongly decreased with increasing temperature, while the uptake rates of alpha-pinene increased with increasing temperature, providing a further explanation of the lower efficiency of thermal protection by alpha-terpineol. The temperature-dependent decrease of alpha-terpineol uptake was both due to decreases in stomatal conductance, g(w), and increased volatility of alpha-terpineol at higher temperature that decreased the monoterpene diffusion gradient between the ambient air (F(A)) and leaf (F(I); U = g(w)[F(A) - F(I)]). Model analyses suggested that alpha-pinene reacted within the leaf at higher temperatures, possibly within the lipid phase, thereby avoiding the decrease in diffusion gradient, F(A) - F(I). Thus, these data contribute to the hypothesis of the antioxidative protection of leaf membranes during heat stress by monoterpenes. These data further suggest that fumigation with the relatively low atmospheric concentrations of monoterpenes that are occasionally observed during warm windless days in the Mediterranean canopies may significantly improve the heat tolerance of nonemitting vegetation that grows intermixed with emitting species.     

Associations between epicardial adipose tissue,subclinical atherosclerosis and high-density lipoprotein composition in type 1 diabetes

Background

The pathophysiology of cardiovascular complications in people with type 1 diabetes (T1DM) remains unclear. An increase in epicardial adipose tissue (EAT) and alterations in the composition of high-density lipoprotein (HDL) are associated with coronary artery disease, but information on its relationship in T1DM is very limited. Our aim was to determine the association between EAT volume, subclinical atherosclerosis, and HDL composition in type 1 diabetes.

Methods

Seventy-two long-term patients with T1DM without clinical atherosclerosis were analyzed. EAT volume and subclinical atherosclerosis were measured using cardiac computed tomography angiography. EAT was adjusted according to body surface to obtain an EAT index (iEAT). HDL composition was determined.

Results

The mean iEAT was 40.47?±?22.18 cc/m². The bivariate analysis showed positive associations of the iEAT with gender, age, hypertension, dyslipidemia, smoking, body mass index, waist circumference, insulin dose, and triglyceride (P?<?0.05). The iEAT correlated positively with small HDL, increased content of apolipoprotein (apo)A-II and apoC-III, and decreased content of apoE and free cholesterol. Multiple linear regression showed that age, apoA-II content in HDL, and waist circumference were independently associated with the iEAT. Fifty percent of the patients presented subclinical atherosclerotic lesions. These patients had a higher iEAT, and their HDL contained less cholesterol and more apoA-II and lipoprotein-associated phospholipase A2 than patients without subclinical atherosclerosis.

Conclusion

Alterations in the composition of HDL in TIDM are associated with increased iEAT and the presence of subclinical atherosclerosis. We propose that these abnormalities of HDL composition could be useful to identify T1DM patients at highest cardiovascular risk.

     

Melanocortin 1 receptor (MC1R) polymorphisms’ influence on size and dermoscopic features of nevi

The melanocortin 1 receptor (MC1R) is a highly polymorphic gene. The loss‐of‐function MC1R variants (“R”) have been strongly associated with red hair color phenotype and an increased melanoma risk. We sequenced the MC1R gene in 175 healthy individuals to assess the influence of MC1R on nevus phenotype. We identified that MC1R variant carriers had larger nevi both on the back [p‐value = .016, adjusted for multiple parameters (adj. p‐value)] and on the upper limbs (adj. p‐value = .007). Specifically, we identified a positive association between the “R” MC1R variants and visible vessels in nevi [p‐value = .033, corrected using the FDR method for multiple comparisons (corrected p‐value)], dots and globules in nevi (corrected p‐value = .033), nevi with eccentric hyperpigmentation (corrected p‐value = .033), a high degree of freckling (adj. p‐value = .019), and an associative trend with presence of blue nevi (corrected p‐value = .120). In conclusion, the MC1R gene appears to influence the nevus phenotype.