Histamine H4 receptor agonists

Since its discovery 10 years ago the histamine H(4) receptor (H(4)R) has attracted attention as a potential drug target, for instance, for the treatment of inflammatory and allergic diseases. Potent and selective ligands including agonists are required as pharmacological tools to study the role of the H(4)R in vitro and in vivo. Many H(4)R agonists, which were identified among already known histamine receptor ligands, show only low or insufficient H(4)R selectivity. In addition, the investigation of numerous H(4)R agonists in animal models is hampered by species-dependent discrepancies regarding potencies and histamine receptor selectivities of the available compounds, especially when comparing human and rodent receptors. This article gives an overview about structures, potencies, and selectivities of various compounds showing H(4)R agonistic activity and summarizes the structure-activity relationships of selected compound classes.     

Magnetospirillum bellicus sp. nov., a Novel Dissimilatory Perchlorate-Reducing Alphaproteobacterium Isolated from a Bioelectrical Reactor

Previously isolated dissimilatory perchlorate-reducing bacteria (DPRB) have been primarily affiliated with the Betaproteobacteria. Enrichments from the cathodic chamber of a bioelectrical reactor (BER) inoculated from creek water in Berkeley, CA, yielded a novel organism most closely related to a previously described strain, WD (99% 16S rRNA gene identity). Strain VDY^T has 96% 16S rRNA gene identity to both Magnetospirillum gryphiswaldense and Magnetospirillum magnetotacticum, and along with strain WD, distinguishes a clade of perchlorate-reducing Magnetospirillum species in the Alphaproteobacteria. In spite of the phylogenetic location of VDY^T, attempted PCR for the key magnetosome formation genes mamI and mamL was negative. Strain VDY^T was motile, non-spore forming, and, in addition to perchlorate, could use oxygen, chlorate, nitrate, nitrite, and nitrous oxide as alternative electron acceptors with acetate as the electron donor. Transient chlorate accumulation occurred during respiration of perchlorate. The organism made use of fermentation end products, such as acetate and ethanol, as carbon sources and electron donors for heterotrophic growth, and in addition, strain VDY^T could grow chemolithotrophically with hydrogen serving as the electron donor. VDY^T contains a copy of the RuBisCo cbbM gene, which was expressed under autotrophic but not heterotrophic conditions. DNA-DNA hybridization with strain WD confirmed VDY^T as a separate species (46.2% identity), and the name Magnetospirillum bellicus sp. nov. (DSM 21662, ATCC BAA-1730) is proposed.Dissimilatory perchlorate-reducing bacteria (DPRB) use perchlorate as a terminal electron acceptor during respiration, reducing it completely to chloride. As a consequence, bioremediation of perchlorate has been identified as the most effective means of treating this harmful contaminant (10), which, due to historically unregulated release into the environment, has become widespread (13, 20, 41). Fortunately, DPRB are ubiquitous and can be readily isolated from a variety of environments (1, 10, 11, 39, 44), and a key gene in the pathway, the chlorite dismutase (cld) gene, has been broadly detected (6). Much has been revealed about the biochemistry and genetics of microbial perchlorate reduction through the study of several model organisms, including Dechloromonas aromatica and Dechloromonas agitata, by a variety of groups (5, 6, 8, 9, 17, 28, 29, 34, 35, 38, 47, 51, 56, 57).Less is known about the variation in physiology between these organisms or the evolution of the perchlorate reduction metabolism, highlighting a need for further isolation and characterization of pure cultures. The lack of congruence between phylogenetic trees of cld and the 16S rRNA gene among tested DPRB suggests that the metabolism may be the result of horizontal gene transfer (6). Given that various elements of the pathway may be mobile, it is not unreasonable to expect that organisms with a wide phylogenetic diversity could acquire the ability to reduce perchlorate. As more varied enrichment conditions are tested (2, 39), sometimes as a result of novel bioreactor development for perchlorate treatment (38, 40, 45), the true phylogenetic diversity of DPRB is becoming apparent, supporting the hypothesis that the metabolism may be widespread within the tree of life, similar to other respiratory processes, such as the reduction of sulfate, Fe(III), and nitrate.Although perchlorate has been primarily regarded as an anthropogenic contaminant, a variety of studies have indicated that perchlorate occurs naturally (29-31, 34), which provides a possible explanation for the selective pressure behind the evolution of perchlorate reduction genes. As more is understood about the chlorine redox cycle on earth, knowledge about the diversity of organisms capable of interacting with the various oxyanions of chlorine is becoming more important. Here, we report the characterization of a unique DPRB in the Alphaproteobacteria. Strain VDY^T was isolated from the surface of a working electrode in an active perchlorate-reducing bioelectrical reactor (BER) that was inoculated with water from Strawberry Creek on the University of California, Berkeley, campus (40). This is only the second described DPRB in the Alphaproteobacteria, the other being the closely related strain WD (26), and these strains compose a unique clade of perchlorate-reducing organisms in the genus Magnetospirillum.     

Real‐time monitoring of herbivore induced volatile emissions in the field

When plants are damaged by herbivorous insects they emit a blend of volatile organic compounds (VOCs) which include a range or terpenoids and green leaf volatiles (GLVs) formed via different metabolic pathways. The precise timing of these emissions upon the onset of herbivore feeding has not been fully elucidated, and the information that is available has been mainly obtained through laboratory based studies. We investigated emissions of VOCs from Populus tremula L. ×P. tremuloides Michx. during the first 20 h of feeding by Epirrita autumnata (autumnal moth) larvae in a field site. The study was conducted using Proton Transfer Reaction‐Mass Spectrometry (PTR‐MS) to measure emissions online, with samples collected for subsequent analysis by complementary gas chromatography‐mass spectrometry for purposes of compound identification. GLV emission peaks occurred sporadically from the outset, indicating herbivore activity, while terpene emissions were induced within 16 h. We present data detailing the patterns of monoterpene (MT), GLV and sesquiterpene (SQT) emissions during the early stages of herbivore feeding showing diurnal MT and SQT emission that is correlated more with temperature than light. Peculiarities in the timing of SQT emissions prompted us to conduct a thorough characterization of the equipment used to collect VOCs and thus corroborate the accuracy of results. A laboratory based analysis of the throughput of known GLV, MT and SQT standards at different temperatures was made with PTR‐MS. Enclosure temperatures of 12, 20 and 25°C had little influence on the response time for dynamic measurements of a GLV or MT. However, there was a clear effect on SQT measurements. Elucidation of emission patterns in real‐time is dependent upon the dynamics of cuvettes at different temperatures.     

Environmental scanning electron microscopy (ESEM)—a versatile tool in studying plants

Environmental scanning electron microscopy (ESEM) enables the investigation of hydrated and uncoated plant samples and the in situ observation of dynamic processes. Water vapor in the microscope chamber takes part in secondary electron detection and charge prevention. Two ESEM modes are available and offer a broad spectrum of applications. The environmental or wet mode prevents sample dehydration by the combination of sample cooling (5°C) and a vapor pressure of 4–6 Torr. In the low vacuum mode, the maximum chamber pressure is limited to 1 Torr (corresponding to about 5% relative humidity in the chamber) and allows the simultaneous use of a backscattered electron detector for imaging material contrast. A selection of characteristic plant samples and various applications are presented as a guide to ESEM for plant scientists. Leaf surfaces, trichomes, epicuticular waxes, and inorganic surface layers represent samples being comparatively resistant to dehydration, whereas callus cells and stigmatic tissue are examples for dehydration- and beam-sensitive samples. The potential of investigating dynamic processes in situ is demonstrated by studying anther opening, by tensile testing of leaves, and by performing hydration/dehydration experiments by changing the vapor pressure. Additionally, automated block-face imaging and serial sectioning using in situ ultramicrotomy is presented. The strengths and weaknesses of ESEM are discussed and it is shown that ESEM is a versatile tool in plant science.     

Programed cell death shapes the expression of horns within and between species of horned beetles

Holometabolous insects provide an excellent opportunity to study both the properties of development as well as their evolution and diversification across taxa. Here we investigate the developmental basis and evolutionary diversification of secondary trait loss during development in the expression of beetle horns, a novel and highly diverse class of secondary sexual traits. In many species, horn growth during late larval development is followed by a period of dramatic remodeling during the pupal stage, including the complete resorption of horns in many cases. Here we show that programed cell death plays an important and dynamic role in the secondary resorption of pupal horn primordia during pupal development. Surprisingly, the degree of cell death mediated horn resorption depended on species, sex, and body region, suggesting the existence of regulatory mechanisms that can diversify quickly over short phylogenetic distances. More generally, our results illustrate that secondary, differential loss of structures during development can be a powerful mechanism for generating considerable morphological diversity both within and between species.     

Integrin-linked kinase controls microtubule dynamics required for plasma membrane targeting of caveolae

Caveolae are specialized compartments of the plasma membrane that are involved in signaling, endocytosis, and cholesterol transport. Their formation requires the transport of caveolin-1 to the plasma membrane, but the molecular mechanisms regulating the transport are largely unknown. Here, we?identify a critical role for adhesion-mediated signaling through β1 integrins and integrin-linked kinase (ILK) in caveolae formation. Mice lacking β1 integrins or ILK in keratinocytes have dramatically reduced numbers of plasma membrane caveolae in?vivo, which is due to impaired transport of caveolin-1-containing vesicles along microtubules (MT) to the plasma membrane. Mechanistically, ILK promotes the recruitment of the F-actin binding protein IQGAP1 to the cell cortex, which, in turn, cooperates with its?effector mDia1 to locally stabilize MTs and to allow?stable insertion of caveolae into the plasma membrane. Our results assign an important role to the integrin/ILK complex for caveolar trafficking to the cell surface.     

APC/C-Cdh1: From cell cycle to cellular differentiation and genomic integrity

Anaphase-promoting complex/cyclosome (APC/C) is a multifunctional ubiquitin-protein ligase that targets various substrates for proteolysis inside and outside of the cell cycle. The activation of APC/C is dependent on two WD-40 domain proteins, Cdc20 and Cdh1. While APC/Cdc20 principally regulates mitotic progression, APC/Cdh1 shows a broad spectrum of substrates in and beyond cell cycle. In the past several years, numerous biochemical and mouse genetic studies have greatly attracted our attention to the emerging role of APC/Cdh1 in genomic integrity, cellular differentiation and human diseases. This review will aim to summarize the recently expanded understanding of APC/Cdh1 in regulating biological function and how its dysfunction may lead to diseases.Key words: APC/C, Cdh1, proteolysis, genomic integrity, signal transduction, differentiation, tumorigenesis     

GENETICS OF SEX EXPRESSION IN FRAG ARIA SPECIES

Hermaphroditism is the normal mode of sex expression in diploid species of Fragaria (Rosaceae, 2n = 14, x = 7) with one known exception, gynodioecious F. vesca L. ssp. bracteata. The polyploid species of Fragaria are all trioecious. An extensive study involving appropriate hybridization, testcrossing, selling, and backcrossing revealed that the repression of sporangia and the inhibition of sporogenesis are controlled by a single gene (or a gene complex) with at least three alleles in the sporophytes of trioecious octoploid species (2n = 56, x = 7). A male suppressor (allele F) reduces microsporangia and represses microsporogenesis completely, but it allows normal development of the stigma, style, and ovary. A female suppressor (allele M), in the absence of modifier genes, inhibits megasporogenesis and drastically reduces the number of carpels and size of receptacles. The allele H, conferring perfect flowers at an early stage of flower organogenesis, acts as an inducer of microsporogenesis in females, but leaves both microand megasporangial development intact. At the sex locus, the F allele (femaleness) is dominant to H and M and the H allele (hermaphroditism) is dominant to M (maleness). Females are exclusively heterogametic (F/H or F/M), hermaphrodites may be homo- or heterogametic (H/H or H/M), and males are homogametic (M/M). The sex gene is expressed precisely in the genetic background of octoploid × diploid hybrids of Fragaria and their derivatives and in crosses with closely related hermaphroditic diploid Pontentilla glandulosa L. Gene dosage phenomena are absent. First generation progeny of colchi-decaploids (F/F, –/–) are exclusively female, but all generations thereafter segregate in a normal diploidized manner (1:1). Application of phytohormones alters sex expression to a limited extent.     

Functional analysis of D-alanylation of lipoteichoic acid in the probiotic strain Lactobacillus rhamnosus GG

Lipoteichoic acid (LTA) is a macroamphiphile molecule which performs several functions in gram-positive bacteria, such as maintenance of cell wall homeostasis. D-alanylation of LTA requires the proteins encoded by the dlt operon, and this process is directly related to the charge properties of this polymer strongly contributing to its function. The insertional inactivation of dltD of the probiotic strain Lactobacillus rhamnosus GG (ATCC 53103) resulted in the complete absence of D-alanyl esters in the LTA as confirmed by nuclear magnetic resonance analysis. This was reflected in modifications of the bacterial cell surface properties. The dltD strain showed 2.4-fold-increased cell length, a low survival capacity in response to gastric juice challenge, an increased sensitivity to human beta-defensin-2, an increased rate of autolysis, an increased capacity to initiate growth in the presence of an anionic detergent, and a decreased capacity to initiate growth in the presence of cationic peptides compared to wild-type results. However, in vitro experiments revealed no major differences for adhesion to human intestinal epithelial cells, biofilm formation, and immunomodulation. These properties are considered to be important for probiotics. The role of the dlt operon in lactobacilli is discussed in view of these results.     

Rudist decline in the Maastrichtian Cardenas Formation (East-central Mexico)

Five sections of the Cardenas and Tabaco formations in east-central Mexico have been analyzed by means of bio-, Sr-isotope, and sequence stratigraphy, in order to evaluate their age as well as the timing of rudist decline.Ammonites [Pachydiscus (Pachydiscus) neubergicus (Hauer), Sphenodiscus pleurisepta (Conrad), Coahuilites sheltoni Böse] indicate an early Maastrichtian age for the topmost lower member of the Cardenas Formation and planktic foraminifera [e.g., Globotruncanita stuarti (de Lapparent), Archaeoglobigerina cretacea (d’Orbigny), Globotruncanella petaloidea (Gandolfi), Gansserina gansseri (Bolli), Globotruncana linneiana (d’Orbigny)] a late early Maastrichtian age for the middle member corresponding to the foraminiferal zones CF5 and CF6. Sr-isotope stratigraphic data yield an early late Maastrichtian age (66.93 Ma < 67.98 Ma < 68.96 Ma) for the last rudist assemblage in the topmost upper member of the Cardenas Formation, coinciding with the foraminiferal zone CF4.17 small-scale and 3 large-scale depositional cycles have been identified, which correspond to para- and depositional sequences. The progradational pattern of the large-scale cycles indicates an overall regression trend, which terminated in subaerial exposure of the area, indicated by paleosoils in the red beds of the Tabaco Formation. The correlation of the large-scale cycles with the global sea level charts indicate that eustatic sea level fall caused the regression and led to the exposure during the middle late Maastrichtian. This subaerial exposure resulted in the loss of habitat and thus the disappearance of rudists in east-central Mexico.