Technion – Israel Institute of Technology

About: Technion – Israel Institute of Technology is a education organization based out in Haifa, Israel. It is known for research contribution in the topics: Population & Upper and lower bounds. The organization has 31714 authors who have published 79377 publications receiving 2603976 citations. The organization is also known as: Technion Israel Institute of Technology & Ṭekhniyon, Makhon ṭekhnologi le-Yiśraʼel.

The methodology of experimentally induced diffuse noxious inhibitory control (DNIC)-like effect in humans.

Abstract: The exploration of endogenous analgesia (EA) via descending pain-modulatory systems started about three decades ago. The generation of analgesia in the rat by periaquaductal grey (PAG) stimulation was the first evidence for the existence of endogenous analgesic capabilities as a normal function of the central nervous system, exerting both inhibitory and facilatory effects (for review, see [5]). Consequent evidence demonstrated an important final common descending modulatory site in the brainstem, the rostral ventromedial medulla (RVM), which receives signals directly from the PAG, with both bearing opioid receptors. Subsequently, the RVM forwards signals downward to the spinal cord (for review, see [11]). This dorsolateral funiculus descending inhibitory pain pathway, consisting of serotonergic and noradrenergic neurons, is under ‘top-down’ cerebral control, mediating modulation of pain perception by emotional, motivational, and cognitive factors [5,11]. Further important evidence in this regard came in the late 1970s from Le Bars and his colleagues [21,22], who were the first to associate the effectiveness of the commonly known ‘pain-inhibits-pain’ counter-irritation phenomena with this EA mechanism. They reported that activity in the dorsal horn and trigeminal nuclei is inhibited by the application of noxious electrical stimuli to remote body areas in anaesthetized rats [21,22]. This phenomenon was termed ‘diffuse noxious inhibitory controls’ (DNICs). Both electrophysiological and anatomical data support the involvement of the subnucleus reticularis dorsalis (SRD) in the caudal medulla in spino-bulbo-spinal loops that are exclusively activated by neurons with a ‘whole-body receptive field’ [23]. Their descending projections pass through the dorsolateral funiculus and terminate in the dorsal horn at all levels of the spinal cord. Thus, DNIC is a ‘bottom-up’ activation of the pain-modulatory mechanism, as part of the descending endogenous analgesia (EA) system. In recent years, a DNIC-like effect, also commonly termed HNCS (heterotopic noxious conditioning stimulation), has been identified as an advanced psychophysical measure with high clinical relevancy in the characterization of one’s capacity to modulate pain and consequently one’s susceptibility to acquire pain disorders.

A method for detecting modules in quantitative bipartite networks

Abstract: Summary Ecological networks are often composed of different subcommunities (often referred to as modules). Identifying such modules has the potential to develop a better understanding of the assembly of ecological communities and to investigate functional overlap or specialization. The most informative form of networks are quantitative or weighted networks. Here, we introduce an algorithm to identify modules in quantitative bipartite (or two-mode) networks. It is based on the hierarchical random graphs concept of Clauset et al. (2008 Nature 453: 98–101) and is extended to include quantitative information and adapted to work with bipartite graphs. We define the algorithm, which we call QuanBiMo, sketch its performance on simulated data and illustrate its potential usefulness with a case study. Modules are detected with a higher accuracy in simulated quantitative networks than in their binary counterparts. Even at high levels of noise, QuanBiMo still classifies 70% of links correctly as within- or between-modules. Recursively applying the algorithm results in additional information of within-module organization of the network. The algorithm introduced here must be seen as a considerable improvement over the current standard of algorithms for binary networks. Due to its higher sensitivity, it is likely to lead to be useful for detecting modules in the typically noisy data of ecological networks.

Unsuspected diversity among marine aerobic anoxygenic phototrophs.

Abstract: Aerobic, anoxygenic, phototrophic bacteria containing bacteriochlorophyll a (Bchla) require oxygen for both growth and Bchla synthesis1,2,3,4,5,6. Recent reports suggest that these bacteria are widely distributed in marine plankton, and that they may account for up to 5% of surface ocean photosynthetic electron transport7 and 11% of the total microbial community8. Known planktonic anoxygenic phototrophs belong to only a few restricted groups within the Proteobacteria α-subclass. Here we report genomic analyses of the photosynthetic gene content and operon organization in naturally occurring marine bacteria. These photosynthetic gene clusters included some that most closely resembled those of Proteobacteria from the β-subclass, which have never before been observed in marine environments. Furthermore, these photosynthetic genes were broadly distributed in marine plankton, and actively expressed in neritic bacterioplankton assemblages, indicating that the newly identified phototrophs were photosynthetically competent. Our data demonstrate that planktonic bacterial assemblages are not simply composed of one uniform, widespread class of anoxygenic phototrophs, as previously proposed8; rather, these assemblages contain multiple, distantly related, photosynthetically active bacterial groups, including some unrelated to known and cultivated types.

Photoinhibition – a historical perspective

Abstract: Photoinhibition is a state of physiological stress that occurs in all oxygen evolving photosynthetic organisms exposed to light. The primary damage occurs within the reaction center of Photosystem II (PS II). While irreversible photoinduced damage to PS II occurs at all light intensities, the efficiency of photosynthetic electron transfer decreases markedly only when the rate of damage exceeds the rate of its repair, which requires de novo PS II protein synthesis. Photoinhibition has been studied for over a century using a large variety of biochemical, biophysical and genetic methodologies. The discovery of the light induced turnover of a protein, encoded by the plastid psbA gene (the D1 protein), later identified as one of the photochemical reaction center II proteins, has led to the elucidation of the underlying mechanism of photoinhibition and to a deeper understanding of the PS II ‘life cycle.’