Chiroptical Studies on Supramolecular Chirality of Molecular Aggregates

The attempts of applying chiroptical spectroscopy to supramolecular chirality are reviewed with a focus on vibrational circular dichroism (VCD). Examples were taken from gels, solids, and monolayers formed by low‐molecular mass weight chiral gelators. Particular attention was paid to a group of gelators with perfluoroalkyl chains. The effects of the helical conformation of the perfluoroalkyl chains on the formation of chiral architectures are reported. It is described how the conformation of a chiral gelator was determined by comparing the experimental and theoretical VCD spectra together with a model proposed for the molecular aggregation in fibrils. The results demonstrate the potential utility of the chiroptical method in analyzing organized chiral aggregates. Chirality 27:659–666, 2015. © 2015 Wiley Periodicals, Inc.     

The Molecular Architecture of HIV

Assembly of human immunodeficiency virus type 1 is driven by oligomerization of the Gag polyprotein at the plasma membrane of an infected cell, leading to membrane envelopment and budding of an immature virus particle. Proteolytic cleavage of Gag at five positions subsequently causes a dramatic rearrangement of the interior virion organization to form an infectious particle. Within the mature virus, the genome is encased within a conical capsid core. Here, we describe the molecular architecture of the virus assembly site, the immature virus, the maturation intermediates and the mature virus core and highlight recent advances in our understanding of these processes from electron microscopy and X-ray crystallography studies.     

Intrauterine Growth Restriction Alters Mouse Intestinal Architecture during Development

Infants with intrauterine growth restriction (IUGR) are at increased risk for neonatal and lifelong morbidities affecting multiple organ systems including the intestinal tract. The underlying mechanisms for the risk to the intestine remain poorly understood. In this study, we tested the hypothesis that IUGR affects the development of goblet and Paneth cell lineages, thus compromising the innate immunity and barrier functions of the epithelium. Using a mouse model of maternal thromboxane A₂-analog infusion to elicit maternal hypertension and resultant IUGR, we tested whether IUGR alters ileal maturation and specifically disrupts mucus-producing goblet and antimicrobial-secreting Paneth cell development. We measured body weights, ileal weights and ileal lengths from birth to postnatal day (P) 56. We also determined the abundance of goblet and Paneth cells and their mRNA products, localization of cellular tight junctions, cell proliferation, and apoptosis to interrogate cellular homeostasis. Comparison of the murine findings with human IUGR ileum allowed us to verify observed changes in the mouse were relevant to clinical IUGR. At P14 IUGR mice had decreased ileal lengths, fewer goblet and Paneth cells, reductions in Paneth cell specific mRNAs, and decreased cell proliferation. These findings positively correlated with severity of IUGR. Furthermore, the decrease in murine Paneth cells was also seen in human IUGR ileum. IUGR disrupts the normal trajectory of ileal development, particularly affecting the composition and secretory products of the epithelial surface of the intestine. We speculate that this abnormal intestinal development may constitute an inherent “first hit”, rendering IUGR intestine susceptible to further injury, infection, or inflammation.     

Molecular Architecture and Function of Matrix Adhesions

Cell adhesions mediate important bidirectional interactions between cells and the extracellular matrix. They provide an interactive interface between the extracellular chemical and physical environment and the cellular scaffolding and signaling machinery. This dynamic, reciprocal regulation of intracellular processes and the matrix is mediated by membrane receptors such as the integrins, as well as many other components that comprise the adhesome. Adhesome constituents assemble themselves into different types of cell adhesion structures that vary in molecular complexity and change over time. These cell adhesions play crucial roles in cell migration, proliferation, and determination of cell fate.With the emergence of metazoan life approximately 600 million years ago, new biological mechanisms arose during the evolution of multicellular organisms with a defined body plan. These mechanisms of cell adhesion are a fundamental feature of all metazoans, from sponges to humans; they enable cells to attach to each other or to an extracellular matrix (ECM), cementing them together and organizing them into a coherent whole. The formation of adhesions and the regulation of their dynamics are crucial for embryogenesis, immune cell function, and wound repair, but they also contribute to disease, including cancer invasion and metastasis, or immune disorders (Hay 1991; Hynes 2002; Berrier and Yamada 2007; Alberts et al. 2008; Mory et al. 2008; Dubash et al. 2009; Manevich-Mendelson et al. 2009; Svensson et al. 2009; Wolfenson et al. 2009a). Adhesive interactions can occur with remarkable temporal and spatial precision. As illustrated in Figure 1, they not only link cells together into functional tissues and organs, but they also convey to the adhering cells accurate positional information concerning their cellular and extracellular environment. This information can, in turn, affect all facets of the cell’s life—its proliferation, differentiation, and fate. In addition to responding to the matrix, cell adhesions can actively remodel and restructure the ECM, driving a reciprocal, bidirectional interaction between the cell and its surrounding matrix. These two fundamental aspects of cell–ECM adhesion—physical/structural roles and environmental sensing/signaling, as well as the dynamic molecular interrelationships between them—will be the primary subjects of this article.Open in a separate windowFigure 1.Schematic illustration highlighting the dynamic cross talk between cells and the extracellular matrix (ECM). Cells secrete and remodel the ECM, and the ECM contributes to the assembly of individual cells into tissues, affecting this process at both receptor and cytoskeletal levels. Adhesion-mediated signaling, based on the cells’ capacity to sense the chemical and physical properties of the matrix, affects both global cell physiology and local molecular scaffolding of the adhesion sites. The molecular interactions within the adhesion site stimulate, in turn, the signaling process, by clustering together the structural and signaling components of the adhesome.We will also describe the functional molecular architecture of cell–matrix adhesions, highlighting the structure–function relationships between the numerous components of cell adhesions that mediate or modulate numerous cell adhesive, migratory, and regulatory processes. We will discuss the mechanisms underlying the scaffolding and sensing processes generated at integrin-mediated adhesions, considering them along two major multiscale conceptual trajectories: molecular complexity and time—that is, a hierarchy of complexity that spans the range from molecules to multimolecular complexes in mature adhesions, as well as the temporal progression of structures during the assembly and maturation of matrix adhesions, from initial cell–matrix recognition to the formation, maturation, and reorganization of cytoskeleton-associated matrix adhesions.     

The blood oxygen binding properties of hypoxicSalmo gairdneri

Summary The blood oxygen binding properties of rainbow trout responded to environmental hypoxia (the oxygen saturation of water 30% at 11°C) in three ways. The quickest response was a moderate acidosis, leading to slightly lowered blood oxygen loading due to the Bohr effect. The second response, an increase of blood oxygen carrying capacity, was completed with 6 h from the onset of hypoxia. The speed of the response suggests that the formation of new haemoglobin played no practical role, the increase being caused either by a decrease of plasma volume or the liberation of erythrocytes from a storage organ. The slowest response, a 25% increase of the blood oxygen affinity within a week of hypoxia, was probably caused by the concurrent decrease of the erythrocyte ATP concentration from 4.45 to 2.51 mol/ml erythrocytes.     

Eggshell formation during prolonged gravidity of the tuatara Sphenodon punctatus

Scanning electron microscopy (SEM) was used to examine the process of shell formation in tuatara. Tuatara carry eggs in the oviducts for ∼ 7–8 mo before nesting, a period of gravidity more than three times as long as in any other oviparous reptile. Our aim was to determine whether shell formation occurred rapidly after ovulation, or whether it occurred gradually throughout gravidity. Eggs were obtained from females in early gravidity (May, ∼ 1 mo after ovulation), midgravidity (August and September, 4–5 mo after ovulation), and late gravidity, immediately prior to nesting (December, 8 mo after ovulation). The shell membrane (fibrous layer) was well formed by May, but calcification of the outer surface had only just begun. Vertical columns of calcium carbonate were embedded in the shell membrane and appeared to erupt through the outer surface between early and midgravidity. Changes in the appearance of the outer calcareous layer were evident as gravidity progressed. In all shells, calcium carbonate was present as calcite. The appearance of the inner boundary (innermost layer of eggshell) was variable; some shells had a smooth and amorphous inner boundary as previously reported for tuatara and other reptiles, whereas other shells had an inner boundary composed of small spherical granules on the inner surface of which small calcareous spicules were scattered. A previously published model of the process of shell formation in tuatara eggshells is refined in light of our observations. We interpret the ability of female tuatara to shell their eggs gradually during winter as further evidence of their unusual physiological tolerance of cold conditions. © 1996 Wiley-Liss, Inc.     

The Molecular Genetic Architecture of Self-Employment

Economic variables such as income, education, and occupation are known to affect mortality and morbidity, such as cardiovascular disease, and have also been shown to be partly heritable. However, very little is known about which genes influence economic variables, although these genes may have both a direct and an indirect effect on health. We report results from the first large-scale collaboration that studies the molecular genetic architecture of an economic variable–entrepreneurship–that was operationalized using self-employment, a widely-available proxy. Our results suggest that common SNPs when considered jointly explain about half of the narrow-sense heritability of self-employment estimated in twin data (σ_g²/σ_P² = 25%, h² = 55%). However, a meta-analysis of genome-wide association studies across sixteen studies comprising 50,627 participants did not identify genome-wide significant SNPs. 58 SNPs with p<10⁻⁵ were tested in a replication sample (n = 3,271), but none replicated. Furthermore, a gene-based test shows that none of the genes that were previously suggested in the literature to influence entrepreneurship reveal significant associations. Finally, SNP-based genetic scores that use results from the meta-analysis capture less than 0.2% of the variance in self-employment in an independent sample (p≥0.039). Our results are consistent with a highly polygenic molecular genetic architecture of self-employment, with many genetic variants of small effect. Although self-employment is a multi-faceted, heavily environmentally influenced, and biologically distal trait, our results are similar to those for other genetically complex and biologically more proximate outcomes, such as height, intelligence, personality, and several diseases.     

Adherens Junction: Molecular Architecture and Regulation

The adherens junction (AJ) is an element of the cell–cell junction in which cadherin receptors bridge the neighboring plasma membranes via their homophilic interactions. Cadherins associate with cytoplasmic proteins, called catenins, which in turn bind to cytoskeletal components, such as actin filaments and microtubules. These molecular complexes further interact with other proteins, including signaling molecules, rendering the AJs into highly dynamic and regulatable structures. The AJs of such nature contribute to the physical linking of cells, as well as to the regulation of cell–cell contacts, which is essential for morphogenesis and remodeling of tissues and organs. Thus, elucidating the molecular architecture of the AJs and their regulatory mechanisms are crucial for understanding how the multicellular system is organized.The adherens junction (AJ) is a form of cell–cell adhesion structure observed in a variety of cell types, as well as in different animal species. It is characterized by a pair of plasma membranes apposed with a distance of 10–20 nm between them, whose intercellular space is occupied by rod-shaped molecules bridging the membranes (Hirokawa and Heuser 1981; Miyaguchi 2000), and the cytoplasmic side of the AJ is associated with condensed actin filaments. In polarized epithelia of vertebrates, the AJ is part of the tripartite junctional complex localized at the juxta-luminal region, which comprises the tight junction (zonula occludens), AJ, and desmosome (macula adherens) aligned in this order from the apical end of the junction (Farquhar and Palade 1963). In this type of epithelia, the AJ is specifically termed the “zonula adherens” or “adhesion belt,” as it completely encloses the cells along with the F-actin lining, called the circumferential actin belt (Fig. 1). The AJs in other cell types assume different morphologies: For example, the AJs in fibroblastic cells are spotty and discontinuous (Yonemura et al. 1995), and those in neurons are organized into tiny puncta as a constituent of the synaptic junctions (Uchida et al. 1996).Open in a separate windowFigure 1.Morphological variations of the adherens junction. In Caco2 cells (colonic carcinoma line), E-cadherin is localized along the actin circumferential belt to organize the zonula adherens (arrow). At the lateral portions of cell junction (arrowheads), E-cadherin signals are punctate, only occasionally overlapping with actin signals in this specific sample. The lateral patterns of cadherin and actin distribution, however, vary with cellular conditions. In MCF10A cells (mammary epithelial line), spotty adherens junctions are seen, where actin filaments perpendicularly terminate at E-cadherin puncta.A major function of AJs is to maintain the physical association between cells, as disruption of them causes loosening of cell–cell contacts, leading to disorganization of tissue architecture. Calcium chelators such as EDTA and EGTA are widely used as a reagent to promote the dissociation of cells in tissues or monolayer cultures. A major target of these chelators is the AJ, as this is a calcium-sensitive structure; although, calcium removal is generally insufficient for the complete dispersion of cells because of the presence of calcium-independent cell–cell adhesion mechanisms (Takeichi et al. 1977). Early studies to search for the molecules responsible for the calcium-dependent junctions resulted in the identification of a group of type-I transmembrane proteins, and its founding member was termed cadherin (Yoshida and Takeichi 1982; Yoshida-Noro et al. 1984). Related molecules identified were also called by various names, such as uvomorulin (Peyrieras et al. 1983), LCAM (Gallin et al. 1983), and ACAM (Volk and Geiger 1984). Later studies revealed that the cadherins form a superfamily, and therefore, the original cadherins are now called “classic” cadherins.Another series of studies have identified nectins, a family of immunoglobulin-like transmembrane proteins, as an AJ component. Nectins function in a calcium-independent way to promote cell–cell adhesion (Nakanishi and Takai 2004). In this article, we overview the molecular organization of the AJs constructed with these membrane proteins, as well as the regulatory mechanisms that operate to sustain or remodel these junctions, paying much attention to the linkages between the AJ and cytoskeletal or signaling proteins.     

Modeling of Supramolecular Properties of Molecular Tweezers, Clips, and Bowls

The electrostatic potential surface (EPS) is calculated for molecular tweezers, clips, and bowls at different levels of theory (semiempirical AM1, ab initio HF/6-31G*, and density functional theory pBP/DN**). According to these calculations, the molecular electrostatic potential (MEP) on the concave side of the molecular tweezers and clips is suprisingly negative for hydrocarbons. This finding seems to be a general phenomenon in nonconjugated ?-electron systems with concave-convex topology and it explains the receptor properties of the molecular tweezers and clips. Analogous calculations performed for the conjugated aromatic molecular bowls show different results. The DFT calculations predict that in these systems the more negative MEP lies on the concave side similar to the findings for the nonconjugated molecular tweezer- and clip-systems, whereas the AM1 calculation leads to the opposite result that the MEP is more negative on convex side of the bowl-systems.     

The Molecular Architecture of Ribbon Presynaptic Terminals

The primary receptor neurons of the auditory, vestibular, and visual systems encode a broad range of sensory information by modulating the tonic release of the neurotransmitter glutamate in response to graded changes in membrane potential. The output synapses of these neurons are marked by structures called synaptic ribbons, which tether a pool of releasable synaptic vesicles at the active zone where glutamate release occurs in response to calcium influx through L-type channels. Ribbons are composed primarily of the protein, RIBEYE, which is unique to ribbon synapses, but cytomatrix proteins that regulate the vesicle cycle in conventional terminals, such as Piccolo and Bassoon, also are found at ribbons. Conventional and ribbon terminals differ, however, in the size, molecular composition, and mobilization of their synaptic vesicle pools. Calcium-binding proteins and plasma membrane calcium pumps, together with endomembrane pumps and channels, play important roles in calcium handling at ribbon synapses. Taken together, emerging evidence suggests that several molecular and cellular specializations work in concert to support the sustained exocytosis of glutamate that is a hallmark of ribbon synapses. Consistent with its functional importance, abnormalities in a variety of functional aspects of the ribbon presynaptic terminal underlie several forms of auditory neuropathy and retinopathy.     

Axon Regrowth during Development and Regeneration Following Injury Share Molecular Mechanisms

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Highlights? Initial axon outgrowth and regrowth during remodeling are mechanistically distinct ? The nuclear receptor UNF is necessary for axon regrowth but not for initial growth ? TOR is also required for developmental regrowth but not for initial axon outgrowth ? UNF promotes axon regrowth via the TOR pathway and guidance via unknown mechanisms     

Haemodynamic effects of adenosine on gills of the trout (Salmo gairdneri)

Summary The haemodynamic effects of adenosine on gills of the trout (Salmo gairdneri) were studied with in vitro and in vivo preparations.On the isolated head preparation, adenosine induced a decrease of the ventral aortic inflow and of the dorsal aortic outflow. Simultaneously the venous outflow increased. These effects were antagonized by theophylline. Adenosine induced a vasoconstriction in gill arches without filaments perfused by the afferent or the efferent branchial arteries. The efferent vessels were more sensitive to adenosine than afferent vessels. The whole systemic circulation of the isolated trunk did not show any response to adenosine. When adenosine was infused into the ventral aorta of living trout, the gill resistance to blood flow was greatly increased.These results suggest that adenosine is able to control the arterious and venous blood pathways in the trout gills by modulating their vascular resistance.     

Unusual Molecular Architecture of the Machupo Virus Attachment Glycoprotein

New World arenaviruses, which cause severe hemorrhagic fever, rely upon their envelope glycoproteins for attachment and fusion into their host cell. Here we present the crystal structure of the Machupo virus GP1 attachment glycoprotein, which is responsible for high-affinity binding at the cell surface to the transferrin receptor. This first structure of an arenavirus glycoprotein shows that GP1 consists of a novel α/β fold. This provides a blueprint of the New World arenavirus attachment glycoproteins and reveals a new architecture of viral attachment, using a protein fold of unknown origins.Pathogenic human and animal viruses constitute a growing and persistent threat to global health (25). Machupo virus (MACV), responsible for Bolivian hemorrhagic fever (HF), is an apt example, being zoonotic and highly virulent. MACV was first isolated in 1963 and, along with Junín virus (JUNV), Guanarito virus (GTOV), Sabia virus (SABV), and Chapare virus (CAPV), comprises the HF viruses within clade B of the New World arenavirus family (13, 21). Clinical features of MACV infection during initial disease onset generally include fever, malaise, and headaches, developing over 7 to 10 days into severe HF (13). The high fatality rate (∼20%) and potential for global spread of this rodent-borne virus by deliberate dissemination have resulted in its classification by the National Institute for Allergy and Infectious Diseases as a high-priority category A biothreat agent (6).MACV is an ambisense RNA enveloped virus composed of a bisegmented genome. The L (large) segment encodes an RNA-dependent polymerase (L) and a zinc finger matrix protein (Z); the S (small) segment encodes the nucleoprotein (NP) and the viral glycoprotein precursor GPC (9). The L and NP proteins are coded in the conventional sense for a negative-sense RNA virus, while Z and GPC are transcribed in the opposite direction (Fig. ​(Fig.1).1). GPC is cleaved by the cellular proprotein convertase site 1 protease (39) to yield a stable complex composed of a 58-amino-acid signal peptide which is necessary for virus infectivity, a GP1 subunit which is involved in receptor attachment (199 amino acids), and a transmembrane-bound GP2 subunit (249 amino acids) which is putatively classified as a class I fusion protein (23, 38) (Fig. ​(Fig.11).Open in a separate windowFIG. 1.Schematic diagram of the ambisense, bisegmented arenavirus genome and details of the MACV GP1 sequence crystallized and ordered in the crystal structure. Both the L and S segments contain a central noncoding region (NCR). Arrows correspond to the coding directionality of the genes.MACV GP1 maintains low sequence identity with the GP1s of other New World HF arenaviruses (47, 27, 31, and 30% for JUNV, SABV, GTOV, and CAPV, respectively). Nevertheless, recent studies have shown that the transferrin receptor (TfR1) is a common cellular receptor for the GP1s of MACV, JUNV, GTOV, and SABV (24, 35, 36). These studies are an important step toward defining the viral tropism, and this interaction provides a target for the development of antivirals and prophylactic vaccines to prevent New World arenavirus infection. Knowledge of the molecular determinants of arenavirus attachment and fusion is a prerequisite for the rational development of immunotherapeutic and antiviral reagents (analogous to the development of neuraminidase inhibitors for the treatment of influenza [4]). To this end, we have solved the structure of the MACV GP1.The globular domain of MACV GP1 glycoprotein (MACV GP1) responsible for attachment to TfR1 (residues 87 to 257 from the complete mature GP1 which comprises residues 59 to 257; GenBank accession number {"type":"entrez-protein","attrs":{"text":"AAS77647.1","term_id":"45825964","term_text":"AAS77647.1"}}AAS77647.1; cDNA synthesized by Codon Devices; Fig. ​Fig.1)1) was cloned into the pHLsec vector containing the chicken RPTPσ signal sequence (5). This region was selected based on the disorder predictions of RONN (44) and consideration of potential disulfide bond patterns. MACV GP1 was expressed in HEK 293T cells transfected with 2 mg DNA/liter of cell culture in the presence of 5 μM kifunensine, which prevents glycosylation processing, resulting in protein bearing oligomannose-type glycans (12). MACV GP1 protein was purified from the cell supernatant by using immobilized metal affinity followed by size-exclusion chromatography (SEC) using a Superdex 200 10/30 column (Amersham) equilibrated in 150 mM NaCl and 10 mM Tris, pH 8.0 (Fig. 2A and B). Protein yields were ∼2.0 mg MACV GP1/liter of cell culture. The binding activity of MACV GP1 for TfR1 (GenBank NC_BC001188, residues 122 to 760 cloned into the pHLsec vector [5]) was confirmed by coexpression and purification (as described above) of a MACV GP1-TfR1 complex from GlcNAc transferase I (GnTI)-deficient HEK 293S cells (37) (Fig. 2C and D).Open in a separate windowFIG. 2.Purification of MACV GP1 and MACV GP1-TfR1 complex. MACV GP1 and MACV GP1-TfR1 were expressed in HEK 293T (with 5 μM kifunensine) and GnTI-deficient HEK 293S cells, respectively. (A) SEC of MACV GP1 run on an S200 10/30 column. (B) A 4 to 12% gradient morpholineethanesulfonic acid-polyacrylamide gel electrophoresis assay of the resulting MACV GP1 from SEC run under reducing conditions (expected unglycosylated molecular mass, ∼22 kDa). The rightmost lane shows molecular mass markers. (C) SEC of MACV GP1-TfR1 complex run on an S200 10/30 column. Peak 1 corresponds to MACV GP1-TfR1 complex, and peak 2 corresponds to excess, unbound MACV GP1. (D) A 4 to 12% gradient morpholineethanesulfonic acid-polyacrylamide gel electrophoresis assay of the resulting protein from SEC run under reducing conditions. Lanes 1, 2, and 3 are consecutive fractions from peak 1, and lanes 4 and 5 are adjacent fractions from peak 2. The rightmost lane shows molecular mass markers. Note that peak 1 contains both GP1 (expected unglycosylated molecular mass, ∼22 kDa) and TfR1 (expected unglycosylated molecular mass, ∼71 kDa). Also, note that the apparent molecular mass difference observed between MACV GP1 in panel B and that in panel D is due to the different MACV GP1 glycoforms which result from expression in kifunensine-treated HEK 293T cells and GnTI-deficient HEK 293S cells.Purified MACV GP1 (concentrated to 12.5 mg/ml) crystallized from sitting drops of 100 nl plus 100 nl (25% [wt/vol] polyethylene glycol 3350, 0.2 M NaCl, and 0.1 M bis-Tris, pH 5.5) equilibrated against 95-μl reservoirs for 78 days at room temperature (42). Crystals were cryoprotected by immersion in reservoir solution plus 25% (vol/vol) glycerol and cryocooled in a 100 K gaseous nitrogen stream. X-ray diffraction data were recorded at the European Synchrotron Radiation Facility (ESRF), Grenoble, France. For phase determination, a crystal was soaked for 21 h with ∼10 mM potassium tetrachloroplatinate (II) and diffraction data were collected to a resolution of 3.4 Å on BM-14 at λ = 0.886 Å (the L1 edge for platinum), λ = 1.072 Å (inflection of the platinum L3 edge), and λ = 1.180 Å (low-energy remote) and on beamline ID14 EH1 at λ = 0.9334 Å (“high-energy remote” between platinum L1 and L2 edges). High-resolution (1.7-Å) data were recorded from a native crystal on ID14 EH1. Images were indexed, integrated, and scaled using HKL2000 (32). Data collection and crystallographic statistics are presented in Tables ​Tables11 and ​and22.

TABLE 1.

Data collection and phasing statistics for MACV GP1^a,c

Molecular Architecture of Spinal Cord Injury Protein Interaction Network

Spinal cord injury (SCI) is associated with complex pathophysiological processes that follow the primary traumatic event and determine the extent of secondary damage and functional recovery. Numerous reports have used global and hypothesis-driven approaches to identify protein changes that contribute to the overall pathology of SCI in an effort to identify potential therapeutic interventions. In this study, we use a semi-automatic annotation approach to detect terms referring to genes or proteins dysregulated in the SCI literature and develop a curated SCI interactome. Network analysis of the SCI interactome revealed the presence of a rich-club organization corresponding to a “powerhouse” of highly interacting hub-proteins. Studying the modular organization of the network have shown that rich-club proteins cluster into modules that are specifically enriched for biological processes that fall under the categories of cell death, inflammation, injury recognition and systems development. Pathway analysis of the interactome and the rich-club revealed high similarity indicating the role of the rich-club proteins as hubs of the most prominent pathways in disease pathophysiology and illustrating the centrality of pro-and anti-survival signal competition in the pathology of SCI. In addition, evaluation of centrality measures of single nodes within the rich-club have revealed that neuronal growth factor (NGF), caspase 3, and H-Ras are the most central nodes and potentially an interesting targets for therapy. Our integrative approach uncovers the molecular architecture of SCI interactome, and provide an essential resource for evaluating significant therapeutic candidates.     

Effect of the prolactin-inhibiting substances bromocripton and lergotrile on hydromineral regulation in rainbow troutSalmo gairdneri

Summary Plasma Na⁺, K⁺ and osmotic pressure were measured in rainbow trout (Salmo gairdneri) following the administration of the prolactin-inhibiting substances Lergotrile and Bromocripton. Both drugs elicited a significant fall in plasma Na⁺ concentrations although a significant response to Bromocripton was apparent only in trout acclimated to distilled water.The changes in plasma Na⁺ levels and in some cases of plasma osmotic pressure following administration of the prolactin-inhibiting substances were consistent with the hypothesis that prolactin acts to maintain plasma Na⁺ levels in this salmonid species in the same manner as in other teleosts. However, since the changes in plasma ions were small (albeit significant) is is proposed that prolactin may play a less important role in osmotic and/or ionic regulation in this species than it does in other teleostean species. Conversely, it may be that the drugs effects a less complete blockage of prolactin secretion than they appear to do in mammals.Ovine prolactin, administered with the drugs, effected a partial retention of plasma Na⁺ in Lergotrile-injected fish but did not significantly modify the effect of Bromocripton. These findings are discussed in light of the proposed action of the drugs, namely that of inhibiting the release of endogenous prolactin.Both Bromocripton and Lergotrile caused a significant fall in hematocrit values. Since plasma osmotic pressure values and plasma K⁺ concentrations were not markedly affected by the drugs (except for a significant (P<0.01) reduction in plasma osmotic pressure in the Bromocriptons-injected groups maintained in distilled water) it was thought that these changes were due to a reduction in the number of blood cells in the peripheral circulation rather than to an influx of water in response to the inhibition of prolactin.