Landscape context modulates alien plant invasion in Mediterranean forest edges

Natural habitats in human-altered landscapes are especially vulnerable to biological invasions, especially in their edges. We aim to understand the influence of landscape and local characteristics on biological invasions by exploring the level of plant invasion and alien species traits in forest edges in highly urbanized landscapes. We identified all plant species in 73 paired plots in the edge and 50 m towards the interior of the forest. We explored the association between alien species richness and similarity in species composition between edge and interior plots with landscape and local variables, using generalized linear models and variance partitioning techniques. Then, we performed Fourth-corner analyses to explore the association between alien plant traits and local and landscape variables. In contrast to native species richness, alien species richness was more affected by the surrounding landscape than by the local characteristics of the edge. Road proximity was positively associated with alien species richness and proportion and was its most important correlate, whereas disturbance was negatively associated with native species richness and was its most influential factor. Alien plant traits were also primarily associated with landscape characteristics. For instance, species of Mediterranean origin and introduced for agriculture were associated with higher agriculture use in the landscape. Our findings suggest that risk analyses of habitat vulnerability to invasion must consider the landscape context in order to successfully predict highly invaded areas and identify potentially successful invaders.     

Learned helplessness: unique features and translational value of a cognitive depression model

The concept of learned helplessness defines an escape or avoidance deficit after uncontrollable stress and is regarded as a depression-like coping deficit in aversive but avoidable situations. Based on a psychological construct, it ideally complements other stress-induced or genetic animal models for major depression. Because of excellent face, construct, and predictive validity, it has contributed to the elaboration of several pathophysiological concepts and has brought forward new treatment targets. Whereas learned helplessness can be modeled not only in a broad variety of mammals, but also in fish and Drosophila, we will focus here on the use of this model in rats and mice, which are today the most common species for preclinical in vivo research in psychiatry.     

Autonomic Dysregulation in Headache Patients

To analyze autonomic nervous system activity in headache subjects, measurements of heart rate variability (HRV), skin temperature, skin conductance, and respiration were compared to a matched control group. HRV data were recorded in time and frequency domains. Subjects also completed self-report questionnaires assessing psychological distress, fatigue, and sleep dysfunction. Twenty-one headache and nineteen control subjects participated. In the time domain, the number of consecutive R-to-R intervals that varied by more than 50 ms and the standard deviation of the normalized R-to-R intervals, both indices of parasympathetic nervous system activity, were significantly lower in the headache group than the control group. Groups did not differ statistically on HRV measures in the frequency domain. Self-report measures showed significantly increased somatization, hostility, anxiety, symptom distress, fatigue, and sleep problems in the headache group. The results suggest headache subjects have increased sympathetic nervous system activity and decreased parasympathetic activity compared to non-headache control subjects. Headaches subjects also showed greater emotional distress, fatigue, and sleep problems. The results indicate an association between headaches and cardiovascular functioning suggestive of sympathetic nervous system activation in this sample of mixed migraine and tension-type headache sufferers.     

Local deformation of human red blood cells in high frequency electric field

A method of local and general deformation of single erythrocytes by external forces in high-frequency electric field is described. The method allows the avoidance of any mechanical contact of the cell with electrodes. Under the action of the forces applied human erythrocytes change their shape and produce various membrane structures: long filopodia-like processes, retraction fibers and lamella-like structures. These structures are never formed by erythrocytes under normal conditions, but are typical for fibroblasts, macrophages and epithelium cells. By the method developed the elastic properties of spicules on the membranes of echinocytes were also studied. Deformation of echinocyte in high-frequency electric field leads to the smoothing out of spicules. However, after the electric field is turned off, echinocyte restores its initial forms including the number and localization of all initial spicules on the cell surface.     

Facilitated c-Fos Induction in Mice Deficient for the AMPA Receptor-Associated Protein Ckamp44

The recently identified Cystine-knot containing AMPAR-associated protein (Ckamp44) represents a novel AMPAR-related protein that critically controls AMPAR-mediated currents and short-term plasticity. However, the effects of the lack of this protein at network level are not entirely understood. Here we used c-Fos brain mapping to analyse whether the excitatory/inhibitory balance is altered in the absence of the Ckamp44. We found that Ckamp44^?/? mice treated with an NMDAR antagonist exhibited a very robust c-Fos expression pattern, similar with that seen in mice lacking the GluN2A subunit of NMDAR treated with the same compound. This finding is unexpected, in particular, since Ckamp44 expression is strongest in dentate gyrus granule cells and less abundant in the rest of the brain.     

Interaction of L- and D-3-amino-1-chloro-2-pentanone with gamma-glutamylcysteine synthetase

The optical isomers of 3-amino-1-chloro-2-pentanone, which are the alpha-chloroketone analogs of L- and D-alpha-aminobutyrate, were synthesized and found to be highly potent irreversible inactivators of gamma-glutamylcysteine synthetase. These chloroketones are 20 to 30 times more active than L-2-amino-4-oxo-5-chlorpentanoate. L- and D-Glutamate, in the presence of Mg2+ or Mn2+, protect the enzyme against inactivation. The enzyme is almost completely inhibited by cystamine under conditions in which 0.5 mol of this compound is bound/mol of enzyme. Treatment of the enzyme with cystamne, which produces inhibition that is reversible by dithiothreitol, prevents the interaction of the new chloroketones, L-2-amino-4-oxo-5-chloropentanoate and methionine sulfoximine with the enzyme. The findings suggest that a sulfhydryl group at the active site interacts with the chloroketones and with cystamine and that the chloroketone inhibitors and cystamine bind to the enzyme as glutamine analogs. The data also suggest that a gamma-glutamyl-S-enzyme intermediate may be formed in the reaction catalyzed by this enzyme.     

Regulation by Fc fragments of the secretion of collagenase, PGE2, and lysozyme by mouse peritoneal macrophages

Fc fragments of human IgG can stimulate resident mouse macrophages in culture to secret collagenase, to increase PGE2 secretion, and to decrease the secretion of lysozyme. Active synthesis and secretion were shown by the progressive accumulation of these products in the extracellular medium and inhibition of secretion by cycloheximide. A dose-dependent effect of Fc fragments was demonstrable. Brief exposure of cells to Fc fragments was sufficient to cause the macrophages to secrete collagenase and large amounts of PGE2 for prolonged periods of time, suggesting that a sustained activation rather than temporary modulation of the cells had occurred. Con A had similar effects on macrophage secretory activity. These findings indicate that proteins that bind to specific macrophage plasma membrane receptors may stimulate the secretion of products that promote the inflammatory response.     

游仆虫信息素Er-1和Er-2对四膜虫的种间作用

信息素是生物体向外释放的化学物质,在细胞及生物体中具有种内信息传递的生理学功能。信息素这一类分子广泛分布于系统发生史中,它们的特异活性在单细胞生物、昆虫以及脊椎动物中均有报道。脊椎动物中信息素的信号传输已被证实是一嗅觉依赖过程,7TM-受体被认为是信号传输过程中的信号转换器。在低等单细胞生物(例如:来可夫游仆虫)的细胞膜上存在有信息素异构体,作为信息素分子的有效结合位点而行使其功能。本研究主要探讨单细胞的信息素(Er-1和Er-2)的基础细胞生理学作用是仅限于产生该信息素的物种,还是对其它的原生动物(例如:四膜虫)或对系统发育中分类地位较高的细胞(例如:MRC5成纤维细胞或J774巨噬细胞)均具有调节活性。研究结果表明,游仆虫的两种信息素对梨形四膜虫GL的生长调节有显著不同的作用:当信息素浓度为10-11M时,Er-1具有正调控作用,而Er-2具有抑制剂的作用。这两种配体的趋化作用也有很不同:Er-1具有一种广范的化学排斥特性,而Er-2具有一个双峰的化学吸引剂的性质。计算机检测发现,与Er-2的作用不同,Er-1可略微降低被测细胞的游动速率。趋化现象的选择特性表明Er-2信息素的受体有一种“短期”的特性;而Er-1是不能选择任何亚种群的,这也支持了我们先前的研究数据,即这两种信息素在四膜虫GL内产生两种不同的信号。四膜虫对信息素特异性的反应表明四膜虫能辨别非常近似但带有微小差异的配体(如Er-1和Er-2的电荷差异)。