S3 S4 Research Articles

Molecular Interactions between Tarantula Toxins and Low-Voltage-Activated Calcium Channels.

Few gating-modifier toxins have been reported to target low-voltage-activated (LVA) calcium channels, and the structural basis of toxin sensitivity remains incompletely understood. Studies of voltage-gated potassium (Kv) channels have identified the S3b–S4 “paddle motif,” which moves at the protein-lipid interface to drive channel opening, as the target for these amphipathic neurotoxins. Voltage-gated calcium (Cav) channels contain four homologous voltage sensor domains, suggesting multiple toxin binding sites. We show here that the S3–S4 segments within Cav3.1 can be transplanted into Kv2.1 to examine their individual contributions to voltage sensing and pharmacology. With these results, we now have a more complete picture of the conserved nature of the paddle motif in all three major voltage-gated ion channel types (Kv, Nav, and Cav). When screened with tarantula toxins, the four paddle sequences display distinct toxin binding properties, demonstrating that gating-modifier toxins can bind to Cav channels in a domain specific fashion. Domain III was the most commonly and strongly targeted, and mutagenesis revealed an acidic residue that is important for toxin binding. We also measured the lipid partitioning strength of all toxins tested and observed a positive correlation with their inhibition of Cav3.1, suggesting a key role for membrane partitioning.

Human beta-defensin 1, a new animal toxin-like blocker of potassium channel

The discovery of human β-defensin 2 (hBD2), as a Kv1.3 channel inhibitor with the unique molecular mechanism and novel immune modulatory function, suggests that human β-defensins are a novel class of channel ligands. Here, the function and mechanism of the human β-defensin 1 (hBD1) binding to potassium channels was investigated. Based on the structural similarity between hBD1 and Kv1.3 channel-sensitive hBD2, hBD1 was found to selectively inhibit human and mouse Kv1.3 channels with IC50 values of 11.8 ± 3.1 μM and 13.2 ± 4.0 μM, respectively. Different from hBD2 modifying Kv1.3 channel activation and increasing activation time constant, hBD1 did not affect the activation feature of both human and mouse Kv1.3 channels. In comparison with hBD2 simultaneously interacting with the extracellular S1–S2 linker and pore region of Kv1.3 channel, the chimeric channel and mutagenesis experiments showed that hBD1 only bound to the extracellular pore region of Kv1.3 channel instead of extracellular S1–S2 linker or S3–S4 linker. Together, these findings enhance knowledge of hBD1 as a new immune-related Kv1.3 channel blocker and highlight the major functional differences between hBD1 and hBD2 to explore in future research.

Description of Carbon Dioxide Adsorption and Desorption onto Malaysian Coals under Subcritical Condition

Coal bed seams have been considered as promising sequestration reservoirs for CO2 disposal to mitigate the green house gas emissions. The CO2 adsorption and desorption attributes of CO2 on dry Malaysian coals (Sarawak, volatile bituminous) were performed using a sorptomat apparatus (ASAP 2010, Micromeritics, USA) and BELSORP-mini II machine (BEL Japan, Inc.) at 273K, 298K and pressure up to 1bar. The CO2 adsorption was favourable at low temperature and dry coal conditions. However, S3 and S4 coals have the highest adsorption capacity by 0.71 and 0.73 mmol/g respectively. According to IUPAC classification of adsorption isotherms, CO2 adsorption isotherm of all coal samples follow type I which most probably describe the adsorption limited to a few molecular layers (micropores). The results of adsorption and desorption isotherm demonstrate a positive hysteresis in all coal samples. The S1 coal and S2 coal have the highest hysteresis between adsorption and desorption isotherm compared to S3 coal and S4 coal. According to hysteresis classifications, the hysteresis during CO2 adsorption and desorption process for all coal samples follows type H3 which describes micropores and mesopores. The evaluation of the equilibrium adsorption data where fitted using by Langmuir, Freundlich, Redlich-Peterson, Koble-Corrigan, Toth and Sips models. Toth model provided the best fit for all adsorption experimental data that predicting all coals having heterogeneous surface properties.

Conformational changes of an ion-channel during gating and emerging electrophysiologic properties: Application of a computational approach to cardiac Kv7.1

Ion channels are the “building blocks” of the excitation process in excitable tissues. Despite advances in determining their molecular structure, understanding the relationship between channel protein structure and electrical excitation remains a challenge. The Kv7.1 potassium channel is an important determinant of the cardiac action potential and its adaptation to rate changes. It is subject to beta adrenergic regulation, and many mutations in the channel protein are associated with the arrhythmic long QT syndrome. In this theoretical study, we use a novel computational approach to simulate the conformational changes that Kv7.1 undergoes during activation gating and compute the resulting electrophysiologic function in terms of single-channel and macroscopic currents. We generated all possible conformations of the S4–S5 linker that couples the S3–S4 complex (voltage sensor domain, VSD) to the pore, and all associated conformations of VSD and the pore (S6). Analysis of these conformations revealed that VSD-to-pore mechanical coupling during activation gating involves outward translation of the voltage sensor, accompanied by a translation away from the pore and clockwise twist. These motions cause pore opening by moving the S4–S5 linker upward and away from the pore, providing space for the S6 tails to move away from each other. Single channel records, computed from the simulated motion trajectories during gating, have stochastic properties similar to experimentally recorded traces. Macroscopic current through an ensemble of channels displays two key properties of Kv7.1: an initial delay of activation and fast inactivation. The simulations suggest a molecular mechanism for fast inactivation; a large twist of the VSD following its outward translation results in movement of the base of the S4–S5 linker toward the pore, eliminating open pore conformations to cause inactivation.

Molecular determinant for the tarantula toxin Jingzhaotoxin-I slowing the fast inactivation of voltage-gated sodium channels

Peptide toxins often have divergent pharmacological functions and are powerful tools for a deep review on the current understanding of the structure-function relationships of voltage-gated sodium channels (VGSCs). However, knowing about the interaction of site 3 toxins from tarantula venoms with VGSCs is not sufficient. In the present study, using whole-cell patch clamp technique, we determined the effects of Jingzhaotoxin-I (JZTX-I) on five VGSC subtypes expressed in HEK293 cells. The results showed that JZTX-I could inhibit the inactivation of rNav1.2, rNav1.3, rNav1.4, hNav1.5 and hNav1.7 channels with the IC50 of 870 ± 8 nM, 845 ± 4 nM, 339 ± 5 nM, 335 ± 9 nM, and 348 ± 6 nM, respectively. The affinity of the toxin interaction with subtypes (rNav1.4, hNav1.5, and hNav1.7) was only 2-fold higher than that for subtypes (rNav1.2 and rNav1.3). The toxin delayed the inactivation of VGSCs without affecting the activation and steady-state inactivation kinetics in the physiological range of voltages. Site-directed mutagenesis indicated that the toxin interacted with site 3 located at the extracellular S3–S4 linker of domain IV, and the acidic residue Asp at the position1609 in hNav1.5 was crucial for JZTX-I activity. Our results provide new insights in single key residue that allows toxins to recognize distinct ion channels with similar potency and enhance our understanding of the structure-function relationships of toxin-channel interactions.

Kv3.1 uses a timely resurgent K(+) current to secure action potential repolarization.

High-frequency action potential (AP) transmission is essential for rapid information processing in the central nervous system. Voltage-dependent Kv3 channels play an important role in this process thanks to their high activation threshold and fast closure kinetics, which reduce the neuron's refractory period. However, premature Kv3 channel closure leads to incomplete membrane repolarization, preventing sustainable AP propagation. Here, we demonstrate that Kv3.1b channels solve this problem by producing resurgent K+ currents during repolarization, thus ensuring enough repolarizing power to terminate each AP. Unlike previously described resurgent Na+ and K+ currents, Kv3.1b's resurgent current does not originate from recovery of channel block or inactivation but results from a unique combination of steep voltage-dependent gating kinetics and ultra-fast voltage-sensor relaxation. These distinct properties are readily transferrable onto an orthologue Kv channel by transplanting the voltage-sensor's S3–S4 loop, providing molecular insights into the mechanism by which Kv3 channels contribute to high-frequency AP transmission.

On implementing signature-based Gröbner basis algorithms using linear algebraic routines from M4RI

On implementing signature-based Gröbner basis algorithms using linear algebraic routines from M4RI

Empirical and Theoretical Validity of Hersey-Blanchard's Contingency Model: A Critical Analysis

For some time it has been commonplace to claim that Hersey and Blanchard's Situational Leadership Theory (SLT), despite its popularity among practitioners, lacks empirical support (Goodson et al. 1989; Blank et al. 1990; Graeff 1997). This criticism was echoed by several studies addressing various aspects of leadership (see e.g. Avolio et al. 2003; Aldoory & Toth 2004; Derue et al. 2011). Objective analysis shows that as more studies on the subject appear this argument becomes less persuasive-there is certain empirical and theoretical evidence of the validity of the SLT model. The goal of this study is to undertake a comprehensive analysis of both the model itself and its theoretical and empirical criticism, and to provide empirical evidence of the model's validity. The structure of the paper is the following: First we give a concise description of the SLT theory. Second, we analyze empirical findings in regards to the model. Third, we analyze theoretical arguments against SLT. Fourth, we address the issue of external validity of the model and its overlap with other theoretical constructs. Finally we formulate and test hypotheses in regards to empirical validation of discussed theoretical concepts.The Hersey-Blanchard Situational ModelThe initial version of Hersey-Blanchard's normative model stipulated that leadership styles should match the followers' maturity (Hersey & Blanchard, 1977). In their later version maturity was replaced with the more specific term (Hersey et al., 1996, 2013). Since both terms are used in theoretical discussion in the literature, in this paper these two notions are used interchangeably. Readiness includes the willingness and abilities of followers. Four levels of readiness require using four different styles-S1 Telling; S2 Selling; S3 Participating and S4 Delegating. These styles are based on the combination of two dimensions, task orientation and people (relationship) orientation. Followers at the lowest level of readiness, R1, are not willing and not able to perform a task. In this case leaders have to use the S1 Telling style, which involves high task and low people orientation. Its essence is creating a structure, i.e., providing specific and explicit directions on what tasks should be carried out (Hersey et al., 2013, p. 125). Moderate level of readiness, R2, involves high willingness and low abilities. The right style for this level is S2 Selling, which reflects high focus on both task and relationship. Applying this style, leaders use persuasion, explain the rationale of assignments to followers, and show consideration so as to maintain followers' motivation (ibid., p. 126).When employees reach R3, high level of readiness, leaders need to gain followers' participation in decision-making. S3 Participating style involves low level of task focus and high level of people focus (ibid., p. 127). Followers are knowledgeable enough so as to provide valuable input in solving problems, so they do not need much structuring, like in previous cases. The majority of the leader's effort and attention should be directed towards relationships rather than task dimensions. Followers at the highest level of readiness, R4, are experts in their field; they are motivated and capable of doing the job autonomously. The behavior which fits these circumstances is the S4 Delegating style. It includes a low focus on both task and relationship dimensions (ibid., p. 128). A leader delegates authority and responsibility to followers, who make their own decisions.Empirical evidence and criticismHambleton and Gumbert (1982), using the Leader Behavior Analysis (LDA) instrument, found a positive relationship between situational leadership styles and managers' perceptions of followers' performance. They argued that in situations where the SLT model was used appropriately, subordinates' performance was significantly higher (ibid., p. 240). At the same time the authors cautioned against generalization of the results due to the problems with self-assessments of managerial style and with the representativeness of the managers sample. …

Solvothermal synthesis of Cu2Zn(Sn1−xGex)S4 and Cu2(Sn1−xGex)S3 nanoparticles with tunable band gap energies

The performance of Cu2ZnSnS4 based thin film solar cells can be efficiently improved by proper elemental substitution. This paper describes a facile and cost-efficient solvothermal route to synthesize Cu2(Sn1−xGex)S3 and Cu2Zn(Sn1−xGex)S4 (0⩽x⩽1) nanoparticles, using elemental sulfur, GeCl4 and other metal salts as the precursors. To avoid the instability of pure CeCl4 toward the moisture and protic solvents, its acetone solution was prepared to use in the synthesis. The resulting Cu2Zn(Sn1−xGex)S4 and Cu2(Sn1−xGex)S3 materials show tunable Ge/Sn ratios through simply adjusting the amount of metal salts in the starting materials, subsequently leading to composition-dependent band gap engineering. The Hall measurement and photoelectrochemical studies reveal that the synthesized Cu2Zn(Sn1−xGex)S4 and Cu2(Sn1−xGex)S3 materials are p-type semiconductor, and the electrical and photoelectrical properties indicate their application potential in thin film solar cells.

Molecular basis of the inhibition of the fast inactivation of voltage-gated sodium channel Nav1.5 by tarantula toxin Jingzhaotoxin-II

Jingzhaotoxin-II (JZTX-II) is a 32-residue peptide from the Chinese tarantula Chilobrachys jingzhao venom, and preferentially inhibits the fast inactivation of the voltage-gated sodium channels (VGSCs) in rat cardiac myocytes. In the present study, we elucidated the action mechanism of JZTX-II inhibiting hNav1.5, a VGSC subtype mainly distributed in human cardiac myocytes. Among the four VGSC subtypes tested, hNav1.5 was the most sensitive to JZTX-II (EC50=125±4nM). Although JZTX-II had little or no effect on steady-state inactivation of the residual currents conducted by hNav1.5, it caused a 10mV hyperpolarized shift of activation. Moreover, JZTX-II increased the recovery rate of hNav1.5 channels, which should lead to a shorter transition from the inactivation to closed state. JZTX-II dissociated from toxin–channel complex via extreme depolarization and subsequently rebound to the channel upon repolarization. Mutagenesis analyses showed that the domain IV (DIV) voltage-sensor domain (VSD) was critical for JZTX-II binding to hNav1.5 and some mutations located in S1–S2 and S3–S4 extracellular loops of hNav1.5 DIV additively reduced the toxin sensitivity of hNav1.5. Our data identified the mechanism underlying JZTX-II inhibiting hNav1.5, similar to scorpion α-toxins, involving binding to neurotoxin receptor site 3.

Pulsed radiofrequency and coccygodynia

signals via a pathway involving c-Fos, which indicates the inhibition of excitatory C fibers and long-term depression. It has also been suggested to alter gene expression in neurons by means of neuromodulation. Another popular theory is the stimulation of the serotonergic and noradrenergic system and induction of descending pathways. In our clinical practice, we introduce the RF cannula between the S3–S4 foramina as has been previously described. We use this method for the treatment of coccygodynia and chronic orchialgia in our pain clinic and long-term follow-up results are satisfactory (1,2).

The specificity of Av3 sea anemone toxin for arthropods is determined at linker DI/SS2–S6 in the pore module of target sodium channels

Av3 is a peptide neurotoxin from the sea anemone Anemonia viridis that shows specificity for arthropod voltage-gated sodium channels (Navs). Interestingly, Av3 competes with a scorpion α-toxin on binding to insect Navs and similarly inhibits the inactivation process, and thus has been classified as 'receptor site-3 toxin', although the two peptides are structurally unrelated. This raises questions as to commonalities and differences in the way both toxins interact with Navs. Recently, site-3 was partly resolved for scorpion α-toxins highlighting S1-S2 and S3-S4 external linkers at the DIV voltage-sensor module and the juxtaposed external linkers at the DI pore module. To uncover channel determinants involved in Av3 specificity for arthropods, the toxin was examined on channel chimaeras constructed with the external linkers of the mammalian brain Nav1.2a, which is insensitive to Av3, in the background of the Drosophila DmNav1. This approach highlighted the role of linker DI/SS2-S6, adjacent to the channel pore, in determining Av3 specificity. Point mutagenesis at DI/SS2-S6 accompanied by functional assays highlighted Trp404 and His405 as a putative point of Av3 interaction with DmNav1. His405 conservation in arthropod Navs compared with tyrosine in vertebrate Navs may represent an ancient substitution that explains the contemporary selectivity of Av3. Trp404 and His405 localization near the membrane surface and the hydrophobic bioactive surface of Av3 suggest that the toxin possibly binds at a cleft by DI/S6. A partial overlap in receptor site-3 of both toxins nearby DI/S6 may explain their binding competition capabilities.

Mapping the interaction site for the tarantula toxin hainantoxin-IV (β-TRTX-Hn2a) in the voltage sensor module of domain II of voltage-gated sodium channels

Peptide toxins often have pharmacological applications and are powerful tools for investigating the structure–function relationships of voltage-gated sodium channels (VGSCs). Although a group of potential VGSC inhibitors have been reported from tarantula venoms, little is known about the mechanism of their interaction with VGSCs. In this study, we showed that hainantoxin-IV (β-TRTX-Hn2a, HNTX-IV in brief), a 35-residue peptide from Ornithoctonus hainana venom, preferentially inhibited rNav1.2, rNav1.3 and hNav1.7 compared with rNav1.4 and hNav1.5. hNav1.7 was the most sensitive to HNTX-IV (IC50∼21nM). In contrast to many other tarantula toxins that affect VGSCs, HNTX-IV at subsaturating concentrations did not alter activation and inactivation kinetics in the physiological range of voltages, while very large depolarization above +70mV could partially activate toxin-bound hNav1.7 channel, indicating that HNTX-IV acts as a gating modifier rather than a pore blocker. Site-directed mutagenesis indicated that the toxin bound to site 4, which was located on the extracellular S3–S4 linker of hNav1.7 domain II. Mutants E753Q, D816N and E818Q of hNav1.7 decreased toxin affinity for hNav1.7 by 2.0-, 3.3- and 130-fold, respectively. In silico docking indicated that a three-toed claw substructure formed by residues with close contacts in the interface between HNTX-IV and hNav1.7 domain II stabilized the toxin–channel complex, impeding movement of the domain II voltage sensor and inhibiting hNav1.7 activation. Our data provide structural details for structure-based drug design and a useful template for the design of highly selective inhibitors of a specific subtype of VGSCs.

Endogenous cytokinin dynamics in micropropagated tulips during bulb formation process influenced by TDZ and iP pretreatment

There are substantial variations in bulbing (bulb formation) efficiency among micropropagated tulip cultivars. The mechanisms involved are poorly understood, but presumably involve cytokinins (CKs) for several reasons. Therefore, we explored CK profiles and dynamics in ‘Blue Parrot’ and ‘Prominence’ cultivars (which have low and high bulbing efficiency, respectively) during the in vitro propagation stages: the last shoot multiplication subculture extended to 14 weeks (S1–S2), the shoot cooling at 5 °C for induction of bulb formation (S3–S4) and the bulb growth initiation after the end of cooling (S5–S6). The CK thidiazuron (TDZ) is routinely used in tulip micropropagation at the shoot multiplication stage, but replacing it with isopentenyladenine (iP) during the last multiplication subculture substantially changed CK dynamics in later stages, and significantly increased bulb formation rates in both cultivars. Generally, the most abundant CKs in both cultivars were the isoprenoid CK types, trans-zeatin (tZ), iP, cis-zeatin and dihydrozeatin. However, ‘Prominence’ shoots had much lower cis- to trans-Z-type CK ratios than ‘Blue Parrot’ shoots, and generally higher levels of physiologically active CKs (free bases tZ, iP and their ribosides) until the last phase of bulb formation, S6 (bulb growth initiation, i.e. swelling of shoot bases), 6 weeks after the end of cold treatment. In this phase total active CK and O-glucoside contents sharply declined in ‘Prominence’ shoots, but not in ‘Blue Parrot’ shoots pretreated with iP. In contrast, the low bulbing ability observed in ‘Prominence’ shoots pretreated with TDZ and ‘Blue Parrot’ shoots pretreated with either TDZ or iP was associated with a gradual rise in active CK and O-glucoside contents after the end of cooling. The results suggest that low bulbing efficiency may be related to down-regulation of tZ biosynthesis, and high bulbing efficiency to a transient increase in active CK forms (mainly tZs) in response to cold treatment during the bulb induction phase, S4 (at the end of cold treatment), followed by a rapid decrease during bulb formation, S6 (6 weeks after the end of cooling).

Osteoblastoma of the Sacrum

Retrospective case series. (1) To analyze clinical and radiographical characteristics, treatment, and outcome in patients with sacral osteoblastoma, (2) to evaluate progression-free survival and local recurrence rate, and (3) to identify prognostic factors. Osteoblastoma is a rare tumor that has been reported to affect the sacrum from 7% to 17%. Symptoms are various and the diagnosis is often delayed. From 1980 to 2010, 18 patients with sacral osteoblastoma (16 males and 2 females) were treated at Rizzoli Institute. Lesion involved S1 (2 cases), S1-S2 (3 cases), S2 (1 case), S2-S3 (1 case), S2-S4 (1 case), S3 (2 cases), S3-S4 (5 cases), S4 (1 case), and almost the entire sacrum in 2 cases. According to Enneking classification for benign bone tumors, 13 (72%) were diagnosed at stage 2 and 5 (28%) at stage 3. Mean tumor volume was 64 cm (range, 2-441 cm). Nine patients had preoperative magnetic resonance imaging. Five patients had a previous inadequate intralesional surgery elsewhere. Treatment consisted in intralesional surgery (16 cases), intralesional surgery and radiotherapy (1 case), and wide resection (1 case). Local adjuvants used were phenol (7 patients), cryocoagulation with "iceball" technique (1 case). Embolizations were performed in 7 patients. At a mean of 8.4 years (range, 1-28 yr), 15 patients (83%) remained continuously disease free, whereas 3 patients had local recurrence (17%). Progression-free survival was 87% at 5 years and 74% at 10 years. No statistical difference was found between patients who received or not local adjuvants (P = 1.254), older or younger than 20 years (P = 0.970), at stage 2 or 3 (P = 0.826), evaluated preoperatively with or without magnetic resonance imaging (P = 0.160), primarily treated versus patients with previous intralesional surgery elsewhere (P = 0.131). In our series, curettage was successful in most of the patients. Local adjuvants did not seem to reduce the risk of local recurrence when combined with intralesional surgery. 4.

Divalent cations activate TRPV1 through promoting conformational change of the extracellular region

Divalent cations Mg2+ and Ba2+ selectively and directly potentiate transient receptor potential vanilloid type 1 heat activation by lowering the activation threshold into the room temperature range. We found that Mg2+ potentiates channel activation only from the extracellular side; on the intracellular side, Mg2+ inhibits channel current. By dividing the extracellularly accessible region of the channel protein into small segments and perturbing the structure of each segment with sequence replacement mutations, we observed that the S1–S2 linker, the S3–S4 linker, and the pore turret are all required for Mg2+ potentiation. Sequence replacements at these regions substantially reduced or eliminated Mg2+-induced activation at room temperature while sparing capsaicin activation. Heat activation was affected by many, but not all, of these structural alternations. These observations indicate that extracellular linkers and the turret may interact with each other. Site-directed fluorescence resonance energy transfer measurements further revealed that, like heat, Mg2+ also induces structural changes in the pore turret. Interestingly, turret movement induced by Mg2+ precedes channel activation, suggesting that Mg2+-induced conformational change in the extracellular region most likely serves as the cause of channel activation instead of a coincidental or accommodating structural adjustment.

Transmembrane Segments Form Tertiary Hairpins in the Folding Vestibule of the Ribosome

Folding of membrane proteins begins in the ribosome as the peptide is elongated. During this process, the nascent peptide navigates along 100Å of tunnel from the peptidyltransferase center to the exit port. Proximal to the exit port is a “folding vestibule” that permits the nascent peptide to compact and explore conformational space for potential tertiary folding partners. The latter occurs for cytosolic subdomains but has not yet been shown for transmembrane segments. We now demonstrate, using an accessibility assay and an improved intramolecular crosslinking assay, that the helical transmembrane S3b–S4 hairpin (“paddle”) of a voltage-gated potassium (Kv) channel, a critical region of the Kv voltage sensor, forms in the vestibule. S3–S4 hairpin interactions are detected at an early stage of Kv biogenesis. Moreover, this vestibule hairpin is consistent with a closed-state conformation of the Kv channel in the plasma membrane.

Synthesis and biological characterization of synthetic analogs of Huwentoxin-IV (Mu-theraphotoxin-Hh2a), a neuronal tetrodotoxin-sensitive sodium channel inhibitor

Huwentoxin-IV (HWTX-IV, also named Mu-theraphotoxin-Hh2a) is a typical inhibitor cystine knot peptide isolated from the venom of Chinese tarantula Ornithoctonus huwena and is found to inhibit tetrodotoxin-sensitive (TTX-S) sodium channels from mammalian sensory neurons. This peptide binds to neurotoxin receptor site 4 located at the extracellular S3–S4 linker of domain II in neuronal sodium channels. However, the molecular surface of HWTX-IV interaction with sodium channels remains unknown. In this study, we synthesized HWTX-IV and three mutants (T28D, R29A and Q34D) and characterized their functions on TTX-S sodium channels from adult rat dorsal root ganglion (DRG) neurons. Analysis of liquid chromatography, mass spectrometry and circular dichroism spectrum indicated that all four synthetic peptides are properly folded. Synthetic HWTX-IV exhibited the same activity as native HWTX-IV, while three mutations reduced toxin binding affinities by 10–200 fold, indicating that the basic or vicinal polar residues Thr28, Arg29, and Gln34 in C-terminus might play critical roles in the interaction of HWTX-IV with TTX-S sodium channels.

Serum proteomic MRM identify peptide ions of transferrin as new fibrosis markers in chronic hepatitis B

Background and aimBecause of the limitations of liver biopsy, reliable non-invasive serum biomarkers of liver fibrosis are needed. The aim of this study was to identify such markers by the use of serum proteomics in chronic hepatitis B (CHB). MethodsTwo-dimensional gel electrophoresis (2-DE) was used to identify differentially expressed protein spots in sera from 40 CHB patients [20 with mild fibrosis (S0–S1) and 20 with severe fibrosis (S3–S4)]. Mass spectrometry (MS) based multiple reaction monitoring (MRM) was used to quantify peptide ions of differential protein spots in another set of sera from 86 CHB patients with different liver fibrosis (S0–S4). ResultsSeven differentially expressed protein spots were found by 2-DE. Fourteen peptide ions of seven target protein spots were quantified by MS-based MRM. Summed peak areas ratio (SPAR) values of peptide ions from protein spot 1, 4 and 8, identified as apo serum transferrin, complement component C3c and transferrin, were significantly different from non-fibrosis (S0) to fibrosis stage 4. AUROCs of models established by peptide ions (protein spot 1, 4, 8) and model consisting of a combination of all ions were 0.848∼0.966 (S2–S4 versus S0–S1) and 0.785∼0.875 (S3–S4 versus S0–S2). Only the peptide ions model of transferrin had better sensitivity and specificity for predicting fibrosis stages than did aspartate aminotransferase-to-platelet ratio index (APRI), FIB-4 and Forn's index. ConclusionsSerum peptide ions of transferrin, detected by proteomic MRM, are new and promising biomarkers for staging liver fibrosis in CHB patients.

Evaluation of LISS-III Sensor Data of IRS-P6 Satellite for Detection Saline Soils (Case Study: Najmabad Region)

Soil Salinity has been a large problem in arid and semi arid regions. Preparation of such maps is useful for Natural resource managers. Old methods of preparing such maps require a lot of time and cost. Multi-spectral remotely sensed dates due to the broad vision and repeating of these imageries is suitable for provide saline soil maps. This investigation is conducted to provide saline soil maps with sensor LISS-III of IRS-P6 satellite data, in Najmabad of Savojbolagh. Satellite images belonging to 25 June 2006. For enhancement of images, salt Indices, Digital Elevation Model (DEM), False Color Composite imageries (FCC) and Principal Component Analysis (PCA), were used. Supervised classification method includes Box classifier, Minimum Distance, Minimum Mahalanobis Distance and Maximum Likelihood classifier, DEM, PCA1, PCA4 and Saline Indices (SI) were used. After classification, the class map salinity S0, S1, S2, S3 S4, were prepared. The results shows highest overall accuracy and kappa coefficient for the maximum Likelihood classifier estimate, respectively 99% and 97% and the lowest overall accuracy and kappa coefficient for PCA1 estimate, respectively 1% and 0% were obtained. Using Digital Elevation Model (DEM) also due to the difference in height position to the separation of saline lands is usefully. Most spectral interference relatedto non-saline soils and low saline soil. From among indices INT2 and PVI greatest ability to segregate is salty soils(especially classes S0 and S1).