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Search Results: 1 - 10 of 298 matches for " Yonathan Zohar "
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Molt-inhibiting hormone stimulates vitellogenesis at advanced ovarian developmental stages in the female blue crab, Callinectes sapidus 1: an ovarian stage dependent involvement
Nilli Zmora, John Trant, Yonathan Zohar, J Sook Chung
Aquatic Biosystems , 2009, DOI: 10.1186/1746-1448-5-7
Abstract: It has been proposed in decapod crustaceans that the high energy demanding processes of molting and reproduction are mutually antagonistic and do not occur simultaneously [1]. The antagonism is clearly demonstrated in the female Callinectes sapidus: molting and reproduction occur in two distinctive life phases with molting cycles occurring only in the juvenile phase and ovarian development and spawning cycles occurring only in adulthood.Ovarian development is a major reproductive process, during which oocytes grow as a result of vitellogenin production and its accumulation in the form of yolk protein (vitellin) and other cytoplasmic egg proteins in the oocytes [2]. In C. sapidus, vitellogenesis occurs primarily in the hepatopancreas after terminal/pubertal molt and requires a relatively short duration of 8–12 weeks for completion [3].The phenomenon of reproductive phase accompanied by terminal anecdysis (halt of molting cycles) is found in only a few decapod crustaceans, including Maja squinado, Libinia emarginata, and Chionoecetes bairdi [4-7]. Most of these anecdysial animals are characterized by a degenerated molting gland, the Y-organ (YO), and the resulting low levels of molting hormones (ecdysteroids) in the hemolymph [8]. However, the adult C. sapidus female is distinguished from these animals by having non-degenerated YO's, which retain their normal size and their capability to bind and respond to molt-inhibiting hormone (MIH) by elevation of cyclic GMP (cGMP). Furthermore, eyestalk ablation (the removal of the source for MIH) induces molting in adult C. sapidus females [9], indicating that the YO's also preserve their steroidogenic potential. Taken together, unlike other anecdysial crustacean species, molting cycle in the mature female C. sapidus is temporarily arrested at intermolt stage, in synchrony with the reproductive phase. Since to date the neuroendocrine mechanism underlying these antagonistic processes has not been examined in any crustacean speci
Molt-inhibiting hormone stimulates vitellogenesis at advanced ovarian developmental stages in the female blue crab, Callinectes sapidus 2: novel specific binding sites in hepatopancreas and cAMP as a second messenger
Nilli Zmora, Amir Sagi, Yonathan Zohar, J Sook Chung
Aquatic Biosystems , 2009, DOI: 10.1186/1746-1448-5-6
Abstract: The X-organ in the eyestalks of crustaceans produces a family of crustacean hyperglycemic hormone (CHH) neuropeptides unique to arthropods. The CHH family members in crustaceans (CHH, molt-inhibiting hormone (MIH), mandibular organ-inhibiting hormone (MOIH), and gonad/vitellogenesis-inhibiting hormone (GIH/VIH)), are involved in the regulation of a variety of physiological processes [1-6]. It has been established that individual CHHs are multifunctional, having specific binding sites in multiple target tissues [7,8]. More specifically, in addition to its primary hyperglycemic action [9], CHH inhibits ecdysteroidogenesis [10]; regulates water uptake during ecdysis [6]; and inhibits methionine incorporation in ovarian fragments, in vitro [11]. It was recently demonstrated that in addition to its traditional molt inhibiting role, MIH is also involved in the regulation of vitellogenesis in the mature female Callinectes sapidus [12] and in Metapenaeus ensis [13]. Since specific hormonal functions are accomplished by neuropeptides and their corresponding receptors [14], efforts have been made to identify and characterize the CHH neuropeptides family of receptors by means of binding kinetics [15-18], signal transduction [15,19-27], and cloning studies [28-31]. However, to date, the mechanisms by which the multiple functionality of these neuropeptides is being executed, are not fully understood.MIH exerts its molt inhibiting activity on the Y-organs (YO) through the suppression of ecdysteroid synthesis and secretion [32-36] via the down-regulation of protein synthesis [19,22]. It has been reported that MIH binds exclusively to a YO membrane receptor with high affinity in a specific, displaceable, and saturable manner [16,17]. Attempts to define the mechanism of MIH signaling revealed changes in YO responsiveness throughout a molt cycle [23,37,38]. While MIH titers in the hemolymph and the number of binding sites of MIH in the YO of Carcinus maenas remained unchanged through
Lactobacillus rhamnosus Accelerates Zebrafish Backbone Calcification and Gonadal Differentiation through Effects on the GnRH and IGF Systems
Matteo A. Avella, Allen Place, Shao-Jun Du, Ernest Williams, Stefania Silvi, Yonathan Zohar, Oliana Carnevali
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045572
Abstract: Endogenous microbiota play essential roles in the host’s immune system, physiology, reproduction and nutrient metabolism. We hypothesized that a continuous administration of an exogenous probiotic might also influence the host’s development. Thus, we treated zebrafish from birth to sexual maturation (2-months treatment) with Lactobacillus rhamnosus, a probiotic species intended for human use. We monitored for the presence of L. rhamnosus during the entire treatment. Zebrafish at 6 days post fertilization (dpf) exhibited elevated gene expression levels for Insulin-like growth factors -I and -II, Peroxisome proliferator activated receptors -α and -β, VDR-α and RAR-γ when compared to untreated-10 days old zebrafish. Using a gonadotropin-releasing hormone 3 GFP transgenic zebrafish (GnRH3-GFP), higher GnRH3 expression was found at 6, 8 and 10 dpf upon L. rhamnosus treatment. The same larvae exhibited earlier backbone calcification and gonad maturation. Noteworthy in the gonad development was the presence of first testes differentiation at 3 weeks post fertilization in the treated zebrafish population -which normally occurs at 8 weeks- and a dramatic sex ratio modulation (93% females, 7% males in control vs. 55% females, 45% males in the treated group). We infer that administration of L. rhamnosus stimulated the IGF system, leading to a faster backbone calcification. Moreover we hypothesize a role for administration of L. rhamnosus on GnRH3 modulation during early larval development, which in turn affects gonadal development and sex differentiation. These findings suggest a significant role of the microbiota composition on the host organism development profile and open new perspectives in the study of probiotics usage and application.
A Collaborative Wireless Access to On-Demand Services
Zohar Naor
Advances in Multimedia , 2008, DOI: 10.1155/2008/273187
Abstract: A collaborative access scheme that exploits the broadcast nature of the wireless communication in order to achieve multicast content delivery is presented in this paper. The key idea is that individual clients requesting for the same content can collaborate and share the same data channel. As opposed to broadcasting, this method enables the clients to determine online the delivered content, and thus supports on-demand services. On the other hand, a multicast content delivery is much more efficient than a unicast content distribution, which must use a dedicated data channel per each and every client. This method is particularly suitable for sessions having a long-time duration, for applications in which clients can subscribe to ahead of time, and for applications in which the clients receive the same information simultaneously. A multicast content distribution increases the network service throughput in terms of the expected number of clients served simultaneously, and therefore it offers a reduced waiting time for content delivery at highly loaded time periods. It is shown that the problem of maximizing the efficiency of distributing a content in a wireless network is NP-hard. An approximation algorithm is therefore used, that for any 0<<1 finds an approximation solution with a relative accuracy . The proposed method does not require any hardware modification on the network equipment. Thus, it can be easily implemented.
Domain-Domain Interactions Underlying Herpesvirus-Human Protein-Protein Interaction Networks
Zohar Itzhaki
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0021724
Abstract: Protein-domains play an important role in mediating protein-protein interactions. Furthermore, the same domain-pairs mediate different interactions in different contexts and in various organisms, and therefore domain-pairs are considered as the building blocks of interactome networks. Here we extend these principles to the host-virus interface and find the domain-pairs that potentially mediate human-herpesvirus interactions. Notably, we find that the same domain-pairs used by other organisms for mediating their interactions underlie statistically significant fractions of human-virus protein inter-interaction networks. Our analysis shows that viral domains tend to interact with human domains that are hubs in the human domain-domain interaction network. This may enable the virus to easily interfere with a variety of mechanisms and processes involving various and different human proteins carrying the relevant hub domain. Comparative genomics analysis provides hints at a molecular mechanism by which the virus acquired some of its interacting domains from its human host.
La réception de la littérature hébra que en France The Reception of Israeli Literature in France
Zohar Shavit
Yod : Revue des études Hébra?ques et Juives , 2011, DOI: 10.4000/yod.416
Abstract: La réception de la littérature israélienne en France. Ce papier traite de l’histoire de l’accueil de la littérature israélienne en France de la création de l’état jusqu'à nos jours. Il est basé sur des études statistiques des traductions ainsi que de commentaires et critiques publiés dans des revues fran aises pendant cette période. Le principal événement littéraire étudié est le Salon du livre avec la littérature israélienne comme invitée d'honneur qui a eu lieu à Paris en mars 2008. Z. Shavit prétend que, en dépit de la popularité de certains écrivains d'Isra l en France, comme David Grossman, Amos Oz et AB Yehoshua, le principal intérêt du public et plus encore, des médias, est de nature politique et non pas littéraire. This paper treats the history of Israeli literature's reception in France from the creation of the state until nowadays. It is based on statistical studies of translations as well as reviews and critiques published in French journals during this period. The main literary event examined is the "Salon des livres" with Israeli literature as the guest of honor which took place in Paris on March 2008. Z. Shavit is claiming that in spite of the popularity of certain Israeli writers in France, such as David Grossman, Amos Oz and A. B. Yehoshua, the main interest of the public and even more so, of the media, is of a political nature and not of a literary one. . . 2008 . , . . , .
Rituals of Apology in the Israeli-Palestinian Conflict
Zohar Kampf
Bulletin du Centre de Recherche Fran?ais de Jérusalem , 2012,
Abstract: Ces dernières années, chercheurs, écrivains, journalistes ont affirmé que l’excuse est devenue un genre rhétorique central dans la politique locale et globale. Sur cet arrière-plan, ma présentation pose deux questions. (1) En quoi ceci est-il pertinent dans le conflit israélo-palestinien. (2) Comment les journalistes produisent et gèrent le discours de l’excuse, et à propos de l’excuse. En conclusion, je propose une réflexion sur le r le normatif des journalistes comme relais d’actions symboliques, qui se veulent réparatrices, dans le conflit israélo-palestinien. Against the backdrop of the claim made in recent years by scholars, writers, and journalists, according to which apologies has become a central rhetorical genre in local and global politics, this paper asks (1) how the political fad of beating one’s breast is relevant to the Israeli-Palestinian conflict and, (2) how do journalists generate and manage the discourse of and about apologies. In conclusion, I reflect on the normative role of journalists in mediating corrective, symbolic actions in the context of the Israeli-Palestinian conflict.
Klein spin model ground states on general lattices
Zohar Nussinov
Physics , 2006,
Abstract: We prove that in short range Klein spin models on general lattices, all ground states are of the dimer type- each fundamental plaquette must host at least one singlet. These ground states are known to rigorously exhibit high dimensional fractionalization. When combined with a recent theorem, this establishes that Klein spin models exhibit topological order on the pyrochlore and checkerboard lattices.
Viewpoint on the "Theory of the superglass phase" and a proof of principle of quantum critical jamming and related phases
Zohar Nussinov
Physics , 2012,
Abstract: A viewpoint article on the very interesting work of Biroli, Chamon, and Zamponi on superglasses. I further suggest how additional new superglass and "spin-superglass" phases of matter (the latter phases contain quenched disorder) and general characteristics may be proven as a theoretical proof of concept in various electronic systems. The new phases include: (1) superglasses of Cooper pairs, i.e., glassy superconductors, (2) superglass phases of quantum spins, and (3) superglasses of the electronic orbitals. New general features which may be derived by the same construct include (a) quantum dynamical heterogeneities- a low temperature quantum analogue of dynamical heterogeneities known to exist in classical glasses and spin-glasses wherein the local dynamics and temporal correlations are spatially non-uniform. I also discuss on a new class of quantum critical systems. In particular, I outline (b) the derivation of the quantum analogue of the zero temperature jamming transition that has a non-trivial dynamical exponent. We very briefly comment on (c) quantum liquid crystals.
Exact Solutions to Special High Dimensional O(n) Models, Dimensional Reductions, gauge redundancy, and special Frustrated Spin and Orbital models
Zohar Nussinov
Physics , 2001,
Abstract: This work addresses models (e.g. potential models of directed orbital systems- the manganates) in which an effective reduction dimensionality occurs as a result of a new symmetry which is intermediate between that of global and local gauge symmetry. This path towards dimensional reduction is examined in simple O(n) spin models and lattice gauge theories. A high temperature expansion is employed to map special anisotropic high dimensional models into lower dimensional variants. We show that it is possible to have an effective reduction in the dimension without the need of compactifying some dimensions. These models are frustrated and display a symmetry intermediate between local and global gauge symmetries. Some solutions are presented. Our dimensional reductions are a generlization of the trivial dimensional reduction that occur in pure two dimensional gauge theories. It will be further seen that the absence of a ``phase interference'' effect plays an important role in high dimensional problems. By identifying another (``permutational'') symmetry present in the large n limit, we will further show how to generally map global high dimensional spin systems onto a one dimensional chain and discuss implications.
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