Widespread generalist clones are associated with range and niche expansion in allopolyploids of Pacific Northwest Hawthorns (Crataegus L.).

Range and niche expansion are commonly associated with transitions to asexuality, polyploidy and hybridity (allopolyploidy) in plants. The ability of asexual polyploids to colonize novel habitats may be due to widespread generalist clones, multiple ecologically specialized clones, or may be a neutral by-product of multiple, independent origins of asexual polyploids throughout the range. We have quantified niche size and divergence for hawthorns of the Pacific Northwest using data from herbarium vouchers with known cytotypes. We find that all polyploid niches diverge from that of the diploid range, and allopolyploids have the broadest niches. Allotetraploids have the largest niche and the widest geographic distribution. We then assessed the genetic mechanism of range expansion by surveying the ecological and geographic distribution of genotypes within each cytotype from sites in which fine-scale habitat assessments were completed. We find no isolation by either geographic or ecological distance in allopolyploids, suggesting high dispersal and colonization ability. In contrast, autotriploids and diploids show patterns of isolation by geographic distance. We also compared the geographic and ecological distributions of clonal genotypes with those of randomly drawn sites of the most widespread cytotype. We found that most clones are geographically widespread and occur in a variety of habitats. We interpret these findings to suggest that patterns of range and niche expansion in Pacific Northwest Hawthorns may stem from these widespread, ecologically generalist clones of hybrid origin.

Reticulate evolution in North American black-fruited hawthorns (Crataegus section Douglasia; Rosaceae): evidence from nuclear ITS2 and plastid sequences.

BACKGROUND AND AIMS: The taxonomic complexity of Crataegus (hawthorn; Rosaceae, Maleae), especially in North America, has been attributed by some to hybridization in combination with gametophytic apomixis and polyploidization, whereas others have considered the roles of hybridization and apomixis to be minimal. Study of the chemical composition and therapeutic value of hawthorn extracts requires reproducible differentiation of entities that may be difficult to distinguish by morphology alone. This study sought to address this by using the nuclear ribosomal spacer region ITS2 as a supplementary DNA barcode; however, a lack of success prompted an investigation to discover why this locus gave unsatisfactory results. METHODS: ITS2 was extensively cloned so as to document inter- and intraindividual variation in this locus, using hawthorns of western North America where the genus Crataegus is represented by only two widely divergent groups, the red-fruited section Coccineae and the black-fruited section Douglasia. Additional sequence data from selected loci on the plastid genome were obtained to enhance further the interpretation of the ITS2 results. KEY RESULTS: In the ITS2 gene tree, ribotypes from western North American hawthorns are found in two clades. Ribotypes from diploid members of section Douglasia occur in one clade (with representatives of the east-Asian section Sanguineae). The other clade comprises those from diploid and polyploid members of section Coccineae. Both clades contribute ribotypes to polyploid Douglasia. Data from four plastid-derived intergenic spacers demonstrate the maternal parentage of these allopolyploids. CONCLUSIONS: Repeated hybridization between species of section Douglasia and western North American members of section Coccineae involving the fertilization of unreduced female gametes explains the observed distribution of ribotypes and accounts for the phenetic intermediacy of many members of section Douglasia.

A subgeneric classification of the genus Vaccinium and the metamorphosis of V. section Bracteata Nakai: more terrestrial and less epiphytic in habit, more continental and less insular in distribution.

The taxonomic integrity of Vaccinium section Bracteata sensu Sleumer was assessed using a variety of numerical measures on a data matrix created from 46 OTUs scored for 65 descriptors. These analyses supported a much restricted ambit for section Bracteata and the concomitant resurrection of section Nesococcus and section Euepigynium, a more cosmopolitan interpretation for section Eococcus and section Pyxothamnus as well as a new taxon, Vaccinium section Baccula-nigra Kloet, sect. nov. to accommodate V. fragile Franch. and its conspecifics. A key to all the sections as well as a brief description for each section is also provided.

The granule-bound starch synthase (GBSSI) gene in the Rosaceae: multiple loci and phylogenetic utility.

We sampled the 5' end of the granule-bound starch synthase gene (GBSSI or waxy) in Rosaceae, sequencing 108 clones from 18 species in 14 genera representing all four subfamilies (Amygdaloideae, Maloideae, Rosoideae, and Spiraeoideae), as well as four clones from Rhamnus catharticus (Rhamnaceae). This is the first phylogenetic study to use the 5' portion of this nuclear gene. Parsimony and maximum-likelihood analyses of 941 bases from seven complete and two partial exons demonstrate the presence of two loci (GBSSI-1 and GBSSI-2) in the Rosaceae. Southern hybridization analyses with locus-specific probes confirm that all four Rosaceae subfamilies have at least two GBSSI loci, even though only one locus has been reported in all previously studied diploid flowering plants. Phylogenetic analyses also identify four clades representing four loci in the Maloideae. Phylogenetic relationships inferred from GBSSI sequences are largely compatible with those from chloroplast (cpDNA: ndhF, rbcL) and nuclear ribosomal internal transcribed spacer (nrITS) DNA. Large clades are marked by significant intron variation: a long first intron plus no sixth intron in Maloideae GBSSI-1, a long fourth intron in Rosoideae GBSSI-1, and a GT to GC mutation in the 5' splice site of the fourth intron in all GBSSI-2 sequences. Our data do not support the long-held hypothesis that Maloideae originated from an ancient hybridization between amygdaloid and spiraeoid ancestors. Instead, Spiraeoideae genera (Kageneckia and Vauquelinia) are their closest relatives in all four GBSSI clades.

Convergent, self-encoded bead sensor arrays in the design of an artificial nose.

We report a new approach to designing an artificial nose based on high-density optical arrays that directly incorporate a number of structural and operational features of the olfactory system. The arrays are comprised of thousands of microsphere (bead) sensors, each belonging to a discrete class, randomly dispersed across the face of an etched optical imaging fiber. Beads are recognized and classified after array assembly by their unique, "self-encoded" response pattern to a selected vapor pulse. The high degree of redundancy built into the array parallels that found in nature and affords new opportunities for chemical-sensor signal amplification. Since each bead is independently addressable through its own light channel, it is possible to combine responses from same-type beads randomly distributed throughout the array in a manner reminiscent of the sensory-neuron convergence observed in the mammalian olfactory system. Signal-to-noise improvements of approximately n1/2 have been achieved using this method.

An olfactory neuronal network for vapor recognition in an artificial nose.

Odorant sensitivity and discrimination in the olfactory system appear to involve extensive neural processing of the primary sensory inputs from the olfactory epithelium. To test formally the functional consequences of such processing, we implemented in an artificial chemosensing system a new analytical approach that is based directly on neural circuits of the vertebrate olfactory system. An array of fiber-optic chemosensors, constructed with response properties similar to those of olfactory sensory neurons, provide time-varying inputs to a computer simulation of the olfactory bulb (OB). The OB simulation produces spatiotemporal patterns of neuronal firing that vary with vapor type. These patterns are then recognized by a delay line neural network (DLNN). In the final output of these two processing steps, vapor identity is encoded by the spatial patterning of activity across units in the DLNN, and vapor intensity is encoded by response latency. The OB-DLNN combination thus separates identity and intensity information into two distinct codes carried by the same output units, enabling discrimination among organic vapors over a range of input signal intensities. In addition to providing a well-defined system for investigating olfactory information processing, this biologically based neuronal network performs better than standard feed-forward neural networks in discriminating vapors when small amounts of training data are used.

Current trends in 'artificial-nose' technology.

Basic principles derived from biological olfaction, such as combining semiselective sensor arrays with pattern recognition, have been used to develop instrumentation capable of broad-band chemical detection and quantification. Commercially available instruments are useful in areas including quality control in the food, beverage and fragrance industries, environmental monitoring, chemical-purity and -mixture analysis, and medical diagnostics. Ongoing research is aimed at the development of more-advanced instruments that are smaller, cheaper, faster and more stable and reliable. These second-generation instruments are likely to find an increasing number of applications, including the on-line monitoring of fermentation and other bioprocesses.

Generating Sensor Diversity through Combinatorial Polymer Synthesis.

A new approach for rapid, simple generation of uniquely responding sensors for use in polymer-based sensor arrays has been developed. Polymerization reactions between different combinations of two starting materials have been found to lead to many new, unique sensors with responses not simply related to the proportion of the starting materials. This approach is demonstrated in two ways: (a) the use of discrete polymer sensing cones each comprised of a specific monomer combination and (b) the fabrication of a gradient sensor, containing all combinations between the starting and ending monomer concentrations. Gradient sensors were fabricated using two different binary monomer systems, with both systems showing regions of broadly diverse fluorescence responses to organic vapor pulses.

A chemical-detecting system based on a cross-reactive optical sensor array.

The vertebrate olfactory system has long been recognized for its extraordinary sensitivity and selectivity for odours. Chemical sensors have been developed recently that are based on analogous distributed sensing properties, but although an association between artificial devices and the olfactory system has been made explicit in some previous studies, none has incorporated comparable mechanisms into the mode of detection. Here we describe a multi-analyte fibre-optic sensor modelled directly on the olfactory system, in the sense that complex, time-dependent signals from an array of sensors provide a 'signature' of each analyte. In our system, polymer-immobilized dye molecules on the fibre tips give different fluorescent response patterns (including spectral shifts, intensity changes, spectral shape variations and temporal responses) on exposure to organic vapours, depending on the physical and chemical nature (for example, polarity, shape and size) of both the vapour and the polymer. We use video images of temporal responses of the multi-fibre tip as the input signals to train a neural network for vapour recognition. The system is able to identify individual vapours at different concentrations with great accuracy. 'Artificial noses' such as this should have wide potential application, most notably in environmental and medical monitoring.

Rapid analyte recognition in a device based on optical sensors and the olfactory system.

We report here the development of a new vapor sensing device that is designed as an array of optically based chemosensors providing input to a pattern recognition system incorporating artificial neural networks. Distributed sensors providing inputs to an integrative circuit is a principle derived from studies of the vertebrate olfactory system. In the present device, primary chemosensing input is provided by an array of fiber-optic sensors. The individual fiber sensors, which are broadly yet differentially responsive, were constructed by immobilizing molecules of the fluorescent indicator dye Nile Red in polymer matrices of varying polarity, hydrophobicity, pore size, elasticity, and swelling tendency, creating unique sensing regions that interact differently with vapor molecules. The fluorescent signals obtained from each fiber sensor in response to 2-s applications of different analyte vapors have unique temporal characteristics. Using signals from the fiber array as inputs, artificial neural networks were trained to identify both single analytes and binary mixtures, as well as relative concentrations. Networks trained with integrated response data from the array or with temporal data from a single fiber made numerous errors in analyte identification across concentrations. However, when trained with temporal information from the fiber array, networks using "name" or "characteristic" output codes performed well in identifying test analytes.

Mechanism of inhibition of human leucocyte elastase by beta-lactams. 3. Use of electrospray ionization mass spectrometry and two-dimensional NMR techniques to identify beta-lactam-derived E-I complexes.

A combination of NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS) was used to probe the identity of beta-lactam-derived complexes with serine proteases. The carbon and proton NMR chemical shifts of the human leucocyte elastase (HLE)-inhibitor complex derived from [4-13C]-L-680,833, [S-(R*,S*)]-4-[(1-(((1-(4- methylphenyl)butyl)amino)carbonyl)-3,3-diethyl-2-oxo-4- azetidinyl)oxy]benzeneacetic acid, were consistent with an sp3 hybridized carbon. The ESI-MS spectrum of the L-680,833-derived HLE-I complex indicated an increase of 333 Da over the mass of the free enzyme. The data are consistent with acylation of the active site serine, loss of p-hydroxybenzeneacetic acid, and formation of a carbinolamine at the carbon deriving from C-4 of the lactam ring. The complexes produced from HLE and the diastereomers of L-680,833 display identical masses. Since the 4R-isomers produce more stable complexes [Green et al. (1995) Biochemistry 34, 14331-14343], these data suggest that these complexes differ in their stereochemistry or conformation. The structural model of the HLE-I complexes derived from the diastereomers predicts that the hydroxyl of the carbinolamine derives from a structurally observed water molecule yielding S-stereochemistry in all cases. In this model, the 4S- and 4R-diastereomers produce complexes that differ by the location of the side chain of a phenylalanine residue. The mass of HLE was increased by that of L-684,481, (R)-1-(((1-(4-methylphenyl)butyl)amino)carbonyl)-3,3-diethyl-2-azetidino ne, which lacks a leaving group at C-4 in the complex derived from this compound. L-691,886, [S-(R*,S*)]-4-[(1-(((1-(4-ethoxyphenyl)butyl)amino)carbonyl)- 3,3-diethyl-4-oxo-2-azetidinyl)-oxy]benzeneacetic acid, produces two complexes of different mass that reactivate with different rates. The mass of the less stable complex is consistent with the acyl-enzyme of 2,2-ethyl-3-oxopropanoic acid while the mass of the more stable complex is analogous to the carbinolamine observed during L-680,833 inactivation. Porcine pancreatic elastase (PPE) produces a complex with a mass consistent with replacement of the C-4 leaving group by water to produce a carbinolamine from L-684,248, [S-(R*,S*)]-4-[(1-(((1-(4-methylphenyl)butyl)amino)carbonyl)-3,3-dimethy l - 2-oxo-4-azetidinyl)oxy]benzoic acid. The C-4 diastereomer, L-684,249, produces two PPE-I complexes with different masses. One of these complexes has a mass identical to the mass of the complex derived from L-684,248 while the mass of the other complex indicates the presence of the entire inhibitor molecule.(ABSTRACT TRUNCATED AT 400 WORDS)

A comparison of the benefits of roller pump versus constrained vortex pump in adult open-heart operations utilizing outcomes research.

The purpose of this study was to compare roller pump and centrifugal pump technologies in routine adult open-heart operations to demonstrate the usefulness of applying a proven method of uniform risk stratification (outcomes research). Objective and readily available preoperative patient data was collected retrospectively on 102 non-randomized and consecutive adult open-heart operations. Group 1 consisted of 51 adult open-heart operations utilizing a roller pump for arterial blood perfusion. Group 2 consisted of 51 adult open-heart procedures utilizing a constrained vortex pump for arterial blood perfusion. A comparison between the frequency of occurrence of 53 different preoperative risk factors in the roller pump group and the centrifugal pump group found no statistically significant differences (p < 0.05). Outcome data for the roller pump and centrifugal pump groups included such data comparisons as intensive care unit length of stay (LOS), post operative LOS, total LOS, total patient charge, reimbursement, morbidity, and mortality, which revealed no statistically significant differences (p < 0.05). Further comparison studies of roller pumps versus centrifugal pumps for arterial blood perfusion should incorporate this kind of comprehensive data comparison and analysis to reasonably assure that both pump groups are very similar before outcomes research is performed.

How to do it: utilizing risk stratification to evaluate outcomes in adult open-heart operations.

The purpose of this study is to demonstrate that by using a proven method of stratifying open-heart operations into levels of predicted mortality, hospitals can closely monitor trends of their open-heart programs and possibly improve the health planning decisions for their institution. A proven method of uniform risk stratification utilizing objective and readily available preoperative patient data was implemented at our institution for a 12 month period (September 1, 1991 through August 31, 1992). A total of 367 patients were included in this study. The patients were categorized into four risk ranges (0 to 4% good risk, 5 to 9% fair risk, 10 to 14% poor risk, and greater than or equal to 15% high risk) indicating a predictive percent probability of operative mortality. The number of patients categorized as either 0 to 4% good risk, 5 to 9% fair risk, 10 to 14% poor risk, and greater than or equal to 15% high risk were 46, 74, 84 and 163, respectively. The patient's average post-operative length of stay in each risk category was 7.6 days, 8.2 days, 10 days, and 12 days, respectively. The patient's average total hospital charges in each risk category were $48,241, $53,531, $60,416 and $75,555, respectively. This information has helped our hospital administration make relevant and objective decisions concerning our open-heart program. Uniform risk stratification (outcomes research) should be incorporated into all adult open-heart surgery programs because it is simple, inexpensive, and can evaluate the outcomes and cost of open-heart surgery.

Peptides presented to the immune system by the murine class II major histocompatibility complex molecule I-Ad.

Between 650 and 2000 different peptides are associated with the major histocompatibility complex class II molecule I-Ad. Sequences for nine of these were obtained by a combination of automated Edman degradation and tandem mass spectrometry. All of the peptides are derived from secretory or integral membrane proteins that are synthesized by the antigen-presenting cell itself. Peptides were 16 to 18 residues long, had ragged NH2-and COOH-termini, and contained a six-residue binding motif that was variably placed within the peptide chain. Binding data on truncated peptides suggest that the peptide binding groove on class II molecules can be open at both ends.

STUDIES IN CRATAEGUS (ROSACEAE: MALOIDEAE) XIV. THE BREEDING SYSTEM OF CRATAEGUS CRUS-GALLI SENSU LATO IN ONTARIO.

Crataegus crus-galli L. sensu lato in southern Ontario is a complex of taxa, two of which appear to consist exclusively of both triploid and tetraploid individuals. While pollen fertility is reduced in triploids, both ploidy levels are characterized by production of eight nucleate aposporous embryo-sacs and hence remain seed-fertile; in addition, single, apparently sexual, embryo-sacs are found in the ovules of tetraploids. Agamospermy is shown experimentally to be pseudogamous. Polyploidy in C. crus-galli s.l. is accompanied by self-compatibility, in contrast to the self-incompatibility of diploid Crataegus species such as C. punctata, with which comparison is made. The weediness of the component taxa of C. crus-galli s.l., in general, and their tendency toward uniparental reproduction, in particular, may explain the homogeneity of their topodemes, and the way in which these topodemes may be markedly differentiated from one another even within a single taxon.

Benign (solitary) ulcer of the rectum -- another cause for rectal stricture.

Benign rectal ulcer syndrome is an uncommon cause of lower gastrointestinal bleeding. Patients may present with mild, often recurrent, rectal bleeding frequently ascribed to hemorrhoids. Barium enema may be normal during the early, nonulcerative phase of proctitis. Single (or multiple) ulcers with or without rectal stricture are the hallmarks of the radiographic diagnosis. Radiologic demonstration of the ulcer(s) is not required, however, for the diagnosis. Benign rectal ulcer should be included in the differential diagnosis of benign-appearing rectal strictures.