Feeding preferences and performance of an aquatic lepidopteran on macrophytes: plant hosts as food and habitat

Although host preferences in phytophagous insects may be generated by several factors, few studies have simultaneously examined several potential host choice determinants. In this study we tested the impact of the following potential host choice determinants on host preference of the semi-aquatic lepidopteran Munroessa gyralis (Pyralidae): growth on different host plants; protein content, polyphenolic content, toughness, and chemical extracts of different host plants; prior feeding experience; and predation pressure on the caterpillar by fishes. Two water lilies, Brasenia schreberi and Nymphaea odorata, were preferred in cafeteria-style feeding experiments over 14 other species of vascular plants. The most preferred water lily (Brasenia) also afforded the fastest growth relative to three other species on which growth was measured. Feeding preferences across species were unrelated to protein content, polyphenolic content, or toughness. Domiciles constructed by caterpillars from leaf fragments were protective from field assemblages of fishes, but domiciles made from preferred or unpreferred host species conferred no significant protection from fish in the laboratory. Caterpillars responded positively to chemical cues of water lilies, and prior feeding experience increased preference for an otherwise unpreferred water lily (Nuphar advena) within the life-span of individual caterpillars. M. gyralis is a generalist herbivore exhibiting modest preference induction and preferences for and among members of the family Nymphaeaceae. Our results suggest that relative growth rates, chemical cues, and previous feeding experience are important factors determining feeding preference. Protein content, polyphenolic content, and toughness appear less important, and the importance of fish predators remains in question. As pupation seems to occur exclusively on Nymphaea, we suggest that host use may be restricted due to life-stage-specific developmental constraints that are not apparent from the results of growth or preference assays. It is currently unknown how often specific life-stages may restrict host use, but our work suggests this as a potentially important area of inquiry.     

A high molecular mass cranberry constituent reduces mutans streptococci level in saliva and inhibits in vitro adhesion to hydroxyapatite

Previous investigations showed that a high molecular mass, non-dialyzable material (NDM) from cranberries inhibits the adhesion of a number of bacterial species and prevents the co-aggregation of many oral bacterial pairs. In the present study we determined the effect of mouthwash supplemented with NDM on oral hygiene. Following 6 weeks of daily usage of cranberry-containing mouthwash by an experimental group (n = 29), we found that salivary mutans streptococci count as well as the total bacterial count were reduced significantly (ANOVA, P < 0.01) compared with those of the control (n = 30) using placebo mouthwash. No change in the plaque and gingival indices was observed. In vitro, the cranberry constituent inhibited the adhesion of Streptococcus sobrinus to saliva-coated hydroxyapatite. The data suggest that the ability to reduce mutans streptococci counts in vivo is due to the anti-adhesion activity of the cranberry constituent.     

Utility of different gene enrichment approaches toward identifying and sequencing the maize gene space

Maize (Zea mays) possesses a large, highly repetitive genome, and subsequently a number of reduced-representation sequencing approaches have been used to try and enrich for gene space while eluding difficulties associated with repetitive DNA. This article documents the ability of publicly available maize expressed sequence tag and Genome Survey Sequences (GSSs; many of which were isolated through the use of reduced representation techniques) to recognize and provide coverage of 78 maize full-length cDNAs (FLCs). All 78 FLCs in the dataset were identified by at least three GSSs, indicating that the majority of maize genes have been identified by at least one currently available GSS. Both methyl-filtration and high-Cot enrichment methods provided a 7- to 8-fold increase in gene discovery rates as compared to random sequencing. The available maize GSSs aligned to 75% of the FLC nucleotides used to perform searches, while the expressed sequence tag sequences aligned to 73% of the nucleotides. Our data suggest that at least approximately 95% of maize genes have been tagged by at least one GSS. While the GSSs are very effective for gene identification, relatively few (18%) of the FLCs are completely represented by GSSs. Analysis of the overlap of coverage and bias due to position within a gene suggest that RescueMu, methyl-filtration, and high-Cot methods are at least partially nonredundant.     

Tetrahydroisoquinoline derivatives as melatonin MT2 receptor antagonists

A series of tetrahydroisoquinolines has yielded potent MT(2) receptor antagonists, which are selective versus the MT(1) receptor.     

Molecular signatures of proliferation and quiescence in hematopoietic stem cells

Stem cells resident in adult tissues are principally quiescent, yet harbor enormous capacity for proliferation to achieve self renewal and to replenish their tissue constituents. Although a single hematopoietic stem cell (HSC) can generate sufficient primitive progeny to repopulate many recipients, little is known about the molecular mechanisms that maintain their potency or regulate their self renewal. Here we have examined the gene expression changes that occur over a time course when HSCs are induced to proliferate and return to quiescence in vivo. These data were compared to data representing differences between naturally proliferating fetal HSCs and their quiescent adult counterparts. Bioinformatic strategies were used to group time-ordered gene expression profiles generated from microarrays into signatures of quiescent and dividing stem cells. A novel method for calculating statistically significant enrichments in Gene Ontology groupings for our gene lists revealed elemental subgroups within the signatures that underlie HSC behavior, and allowed us to build a molecular model of the HSC activation cycle. Initially, quiescent HSCs evince a state of readiness. The proliferative signal induces a preparative state, which is followed by active proliferation divisible into early and late phases. Re-induction of quiescence involves changes in migratory molecule expression, prior to reestablishment of homeostasis. We also identified two genes that increase in both gene and protein expression during activation, and potentially represent new markers for proliferating stem cells. These data will be of use in attempts to recapitulate the HSC self renewal process for therapeutic expansion of stem cells, and our model may correlate with acquisition of self renewal characteristics by cancer stem cells.     

Quantitative assessment of hemoglobin-induced endothelial barrier dysfunction.

Hemoglobin (Hb)-based O2 carriers (HBOC) are undergoing extensive development as potential "blood substitutes." A major problem associated with these molecules is an increase in microvascular permeability and peripheral vascular resistance. In this paper, we utilized bovine lung microvascular endothelial cell monolayers and simultaneously measured Hb-induced changes in transendothelial electrical resistance, diffusive albumin permeability, and diffusive Hb permeability (PDH) for three forms of Hb: natural tetrameric human Hb-A and two polymerized recombinant HBOCs containing alpha-human and beta-bovine chains designated Hb-Polytaur (molecular mass: 500 kDa) and Hb-(Polytaur)n (molecular mass: approximately 1,000,000 Da), respectively. Hb-Polytaur and Hb-(Polytaur)n are being evaluated for clinical use as HBOCs. All three Hb molecules induce a rapid decline of transendothelial electrical resistance to 30% of baseline. Diffusive albumin permeabiltiy increases, on average, approximately ninefold (2.78 x 10(-7) vs. 2.47 x 10(-6) cm/s) in response to Hb exposure. All three Hb molecules induce an increase in their own permeability, a process that we have called Hb-induced Hb permeability. The magnitude of change of PDH is also related to Hb size. When PDH is corrected for the diffusive coefficient for each Hb species, no evidence of restricted diffusion is found. Immunofluorescent images demonstrate Hb-induced actin stress fiber formation and large intercellular gaps. These data provide the first quantitative assessment of the effect of polymerized HBOC on their own diffusion rates over time. We discuss the importance of these findings in terms of Hb extravasation rates, molecular sieving, and clinical consequences of HBOC use.     

Dog star rising: the canine genetic system

Purebred dogs are providing invaluable information about morphology, behaviour and complex diseases, both of themselves and humans, by supplying tractable populations in which to map genes that control those processes. The diversification of dog breeds has led to the development of breeds enriched for particular genetic disorders, the mapping and cloning of which have been facilitated by the availability of the canine genome map and sequence. These tools have aided our understanding of canine population genetics, linkage disequilibrium and haplotype sharing in the dog, and have informed ongoing efforts of the need to identify quantitative trait loci that are important in complex traits.     

Feasibility of rapid and automated importation of 3D echocardiographic left ventricular (LV) geometry into a finite element (FEM) analysis model

Background  

Finite element method (FEM) analysis for intraoperative modeling of the left ventricle (LV) is presently not possible. Since 3D structural data of the LV is now obtainable using standard transesophageal echocardiography (TEE) devices intraoperatively, the present study describes a method to transfer this data into a commercially available FEM analysis system: ABAQUS^?.