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The bed bug, Cimex lectularius, has re-established itself as a ubiquitous human ectoparasite throughout much of the world during the past two decades. This global resurgence is likely linked to increased international travel and commerce in addition to widespread insecticide resistance. Analyses of the C. lectularius sequenced genome (650 Mb) and 14,220 predicted protein-coding genes provide a comprehensive representation of genes that are linked to traumatic insemination, a reduced chemosensory repertoire of genes related to obligate hematophagy, host-symbiont interactions, and several mechanisms of insecticide resistance. In addition, we document the presence of multiple putative lateral gene transfer events. Genome sequencing and annotation establish a solid foundation for future research on mechanisms of insecticide resistance, human-bed bug and symbiont-bed bug associations, and unique features of bed bug biology that contribute to the unprecedented success of C. lectularius as a human ectoparasite.

Polyamines (PAs) including putrescine (PUT), spermidine (SPD) and spermine (SPM) are small, versatile molecules with two or more positively charged amino groups. Despite their importance for almost all forms of life, their specific roles in molecular and cellular biology remain partly unknown. The molecular structures of PAs suggest two presumable biological functions: (i) as potential buffer systems and (ii) as interactants with poly-negatively charged molecules like nucleic acids. The present report focuses on the question, whether the molecular structures of PAs are essential for such functions, or whether other simple molecules like small peptides with closely spaced positively charged side chains might be suitable as well. Consequently, we created titration curves for PUT, SPD, and SPM, as well as for oligolysines like tri-, tetra-, and penta-lysine. None of the molecules provided substantial buffering capacity at physiological intracellular pH values. Apparently, the most important mechanism for intracellular pH homeostasis in neurons is not a buffer system but is provided by the actions of the sodium-hydrogen and the bicarbonate-chloride antiporters. In a similar approach we investigated the interaction with DNA by following the extinction at 260 nm when titrating DNA with the above molecules. Again, PUT and tri-lysine were not able to interact with herring sperm DNA, while SPD and SPM were. Obviously, the presence of several positively charged groups on its own is not sufficient for the interaction with nucleic acids. Instead, the precise spacing of these groups is necessary for biological activity. [ABSTRACT FROM AUTHOR]

Recently, three proton channels (HV) have been identified and characterized in Aplysia californica (AcHV1‐3). Focusing on AcHV1 and AcHV2, analysis of Transcriptome Shotgun Assembly and genomic databases of 91 molluscs identified HV homologous channels in other molluscs: channels homologous to AcHV1 and to AcHV2 were found in 90 species (56 full‐length sequences) and in 33 species (18 full‐length sequences), respectively. Here, we report the discovery of a fourth distinct proton channel family, HV4. This new family has high homology to AcHV1 and AcHV2 and was identified only in bivalvian molluscs (13 species, 12 full‐length sequences). Typically, these channels possess an extracellular S1–S2 loop of intermediate size (~ 20 amino acids) compared to the shorter loops of molluscan HV1 channels (~ 13 amino acids) and the much larger loops of molluscan HV2 channels (> 65 amino acids). The characteristic voltage‐sensor motif in S4 possesses only two arginine residues with the common third arginine being replaced by a lysine. Moreover, HV4 channels are much smaller with only around 200 amino acids in total length. The smallest functional channel found so far in nature (189 amino acids) is expressed in the pacific oyster Crassostrea gigas (CgHV4) and might be considered an archetypical minimal proton channel. Functional expression and electrophysiological characterization demonstrated that CgHV4 shares distinctive hallmarks of other investigated proton channels as high proton selectivity, slow activation, and pH‐ and voltage‐regulated gating. This work is the first description of a HV4 type channel, adding a new member to the recently expanded family of proton channels. [ABSTRACT FROM AUTHOR]

Voltage‐gated ion channels, whose first identified function was to generate action potentials, are divided into subfamilies with numerous members. The family of voltage‐gated proton channels (HV) is tiny. To date, all species found to express HV have exclusively one gene that codes for this unique ion channel. Here we report the discovery and characterization of three proton channel genes in the classical model system of neural plasticity, Aplysia californica. The three channels (AcHV1, AcHV2, and AcHV3) are distributed throughout the whole animal. Patch‐clamp analysis confirmed proton selectivity of these channels but they all differed markedly in gating. AcHV1 gating resembled HV in mammalian cells where it is responsible for proton extrusion and charge compensation. AcHV2 activates more negatively and conducts extensive inward proton current, properties likely to acidify the cytosol. AcHV3, which differs from AcHV1 and AcHV2 in lacking the first arginine in the S4 helix, exhibits proton selective leak currents and weak voltage dependence. We report the expansion of the proton channel family, demonstrating for the first time the expression of three functionally distinct proton channels in a single species. [ABSTRACT FROM AUTHOR]

ATP-sensitive [K.sup.+] ([K.sub.ATP]) channels are composed of pore-forming Kir6.x subunits and regulatory sulfonylurea receptor (SUR) subunits. SURs are ATP-binding cassette proteins with two nucleotide-binding folds (NBFs) and binding sites for sulfonylureas, like glibenclamide, and for channel openers. Here we report the identification and functional characterization of four novel splice forms of guinea pig SUR1. Three splice forms originate from alternative splicing of the region coding for NBF1 and lack exons 17 (SUR1[DELTA]17), 19 (SUR1[DELTA]19), or both (SUR1[DELTA]17[DELTA]19). The fourth (SUR1C) is a COOH-terminal SUR1-fragment formed by exons 31-39 containing the last two transmembrane segments and the COOH terminus of SUR1. RT-PCR analysis showed that these splice forms are expressed in several tissues with strong expression of SUR1C in cardiomyocytes. Confocal microscopy using enhanced green fluorescent protein-tagged SUR or Kir6.x did not provide any evidence for involvement of these splice forms in the mitochondrial [K.sub.ATP] channel. Only SUR1 and SUR1[DELTA]17 showed high-affinity binding of glibenclamide ([K.sub.d] [approximately equal to] 2 nM in the presence of 1 mM ATP) and formed functional [K.sub.ATP] channels upon coexpression with Kir6.2. ATP-sensitive potassium channel; mitochondria; glibenclamide; meglitinide

A study was conducted to compare the expression of endothelin-1 (ET-1) and troponin T in capillary endothelial cells and cardiomyocytes isolated from guinea pig heart. Guinea pig hearts were isolated and subjected to enzymatic dispersion for the purpose of the experiment. Findings have indicated that troponin T and endothelin-1 were found to be specific markers for guinea-pig cardiac muscle cells and coronary endothelial cells, respectively.