Learned Recognition of Heterospecific Alarm Signals: The Importance of a Mixed Predator Diet

A wide diversity of aquatic organisms release alarm signals upon being attacked by a predator. Alarm signals may 'warn' nearby individuals of danger. Moreover, the signals may be important in facilitating learned recognition of unknown stimuli. It is common for different prey species to respond to each other's chemical alarm signals. In many cases, the responses are learned but no learning mechanisms have been identified to date. In this study we tested whether prey fish can learn the identity of an unknown alarm signal when they detect it in association with conspecific alarm cues in the diet of a predator. Chemical alarm cues are known to be conserved in the diet of predators. We conditioned fathead minnows ( Pimephales promelas ) with chemical stimuli from predatory yellow perch ( Perca flavescens ) fed a mixed diet of minnows and brook stickleback ( Culaea inconstans ), perch fed a mixed diet of swordtails ( Xiphophorus helleri ) and stickleback or distilled water. Minnows were subsequently exposed to chemical alarm cues of injured stickleback alone. Those minnows previously conditioned with perch fed a mixed diet of minnows and stickleback increased their use of shelter and 'froze' significantly more than minnows previously conditioned with perch fed a diet of swordtails and stickleback or those exposed to distilled water. These data demonstrate a mechanism by which minnows can learn the identity of a heterospecific alarm signal.     

Focus: Health Equity: Meeting Dermatologic Needs in an Uninsured Population: Lessons Learned from a Referrals Cohort at a Student-Run Free Clinic

Unmet dermatologic needs of the uninsured patient population are important to identify and address, especially as the COVID-19 pandemic has introduced additional barriers of access to care. We describe the successful collaboration between a student-run free clinic and dermatology practice since 2012, highlighting excellent time to appointment intervals and resolution rates as well as the associated modest financial cost. We believe that the information provided in our report may serve as a proof of concept and facilitate the implementation of such collaborations throughout the United States.     

Microarray analysis of expressed sequence tags from haustoria of the rust fungus Uromyces fabae

Rust fungi are plant parasites which colonise host tissue with an intercellular mycelium that forms haustoria within living plant cells. To identify genes expressed during biotrophic growth, EST sequencing was performed with a haustorium-specific cDNA library from Uromyces fabae. One thousand seventeen ESTs were generated, which assembled into 530 contigs. Several of the most frequently represented sequences in the EST database were identical to the in planta induced genes (PIGs) identified previously (Hahn, M., Mendgen, K., 1997. Characterisation of in planta-induced rust genes isolated from a haustorium-specific cDNA library, Mol. Plant-Microbe Interact. 10, 427-437). Virus-encoded sequences were identified, providing evidence for two novel RNA mycoviruses in U. fabae. Microarray hybridisation revealed many cDNAs that were significantly activated in rust-infected leaves compared to germinated uredospores. Very strong in planta expression was found for two PIGs encoding putative metallothioneins. Furthermore, several genes involved in ribosome biogenesis and translation, glycolysis, amino acid metabolism, stress response, and detoxification showed an increased expression in the parasitic mycelium. These data indicate a strong shift in gene expression in rust fungi between germination and the biotrophic stage of development.     

Critical role of Cdc42 in mediating endothelial barrier protection in vivo

Activation of the Rho GTPase Cdc42 has been shown in endothelial cell monolayers to prevent disassembly of interendothelial junctions and the increase in endothelial permeability. Here, we addressed the in vivo role of Cdc42 activity in mediating endothelial barrier protection in lungs by generating mice expressing the dominant active mutant V12Cdc42 protein in vascular endothelial cells targeted via the VE-cadherin promoter. These mice developed normally and exhibited constitutively active GTP-bound Cdc42. The increase in lung vascular permeability and gain in tissue water content in response to intraperitoneal lipopolysaccharide challenge (7 mg/kg) were markedly attenuated in the transgenic mice. To address the basis of the protective effect, we observed that expression of V12Cdc42 mutant in endothelial monolayers reduced the decrease in transendothelial electrical resistance, a measure of opening of interendothelial junctions, thus indicating that Cdc42 activity preserved junctional integrity. RhoA activity in V12Cdc42-expressing endothelial monolayers was reduced compared with untransfected cells, suggesting that activated Cdc42 functions by counteracting the canonical RhoA-mediated mechanism of endothelial hyperpermeability. Therefore, Cdc42 activity of microvessel endothelial cells is a critical determinant of junctional barrier restrictiveness and may represent a means of therapeutically modulating increased lung vascular permeability and edema formation.     

CAUT lines: a novel resource for studies of cell autonomy in Arabidopsis

Plant development is critically dependent on the interactions between clonally unrelated cell layers. The cross-talk between layers can be addressed by studies of cell autonomy. Cell autonomy is a property of genetic mosaics composed of cells of differing genotypes. Broadly, if the phenotype of a mutant tissue reflects only its genotype and is unaffected by the presence of wild-type tissue, the trait is cell-autonomous. Conversely, if the phenotype of a mutant tissue reflects that of wild-type tissue in the mosaic, the trait is non-autonomous. Here we report a novel, versatile and robust method for studies of cell autonomy in Arabidopsis. Cell autonomy (CAUT) lines consist of a collection of homozygous stocks, each containing one of 76 mapped T-DNA inserts, each of which corrects the yellow ch-42 mutant to green ( CH-42 ) by complementation. This has the effect of translocating the colour marker to 76 new locations around the genome. X-irradiation of heterozygous CAUT line seeds results in yellow sectors, with loss of the CH-42 transgene and adjacent wild-type genes. This property can be used to remove the wild-type copy of developmental genes in appropriate heterozygotes, resulting in yellow ( ch-42 ) sectors that are hemizygous for the trait of interest. Such sectors can provide insight into cell autonomy. Experiments using the ap1 , ap3 , ag and clv1 mutants show that CAUT lines are useful in the study of cell autonomy.     

Optimization of the Ugi Reaction Using Parallel Synthesis and Automated Liquid Handling

The optimization of a Ugi reaction involving the mixing of furfurylamine, benzaldehyde, boc-glycine and t-butylisocyanide is described. Triplicate runs of 48 parallel experiments are reported, varying concentration, solvent and the excess of some of the reagents. The isolation of the product was achieved by a simple filtration and wash procedure. The highest yield obtained was 66% from 0.4 M methanol with 1.2 eq. of imine. This is significantly above the 49% yield obtained from the initial reaction under equimolar concentration at 0.4 M in methanol. Methanol solutions with reagent concentrations of 0.4M or 0.2M gave superior yields while all solvent systems at 0.07M performed poorly. At 0.2M, methanol and ethanol/methanol (60/40) mixtures were statistically equally good while THF/methanol (60/40) was poor and acetonitrile/methanol (60/40) was intermediate. Good reproducibility of the precipitate yields was obtained in these replicate experiments, allowing for subtle interaction effects to be positively identified. Open in a separate windowClick here to view.^{(50M, flv)}     

Ghrelin is an orexigenic and metabolic signaling peptide in the arcuate and paraventricular nuclei

Ghrelin is a 28-amino acid acylated peptide and is the endogenous ligand for the growth hormone secretagogue receptor (GHS-R). The GHS-R is expressed in hypothalamic nuclei, including the arcuate nucleus (Arc) where it is colocalized with neuropeptide Y (NPY) neurons. In the present study, we examined the effects of ghrelin on feeding and energy substrate utilization (respiratory quotient; RQ) following direct injections into either the arcuate or the paraventricular nucleus (PVN) of the hypothalamus. Ghrelin was administered at the beginning of the dark cycle at doses of 15-60 pmol to male and female rats. In feeding studies, food intake was measured 2 and 4 h postinjection. Separate groups of rats were injected with ghrelin, and the RQ (VCO(2)/VO(2)) was measured using an open circuit calorimeter over a 4-h period. Both Arc and PVN injections of ghrelin increased food intake in male and female rats. Ghrelin also increased RQ, reflecting a shift in energy substrate utilization in favor of carbohydrate oxidation. Because these effects are similar to those observed after PVN injection of NPY, we then assessed the impact of coinjecting ghrelin with NPY into the PVN. When rats were pretreated with very low doses of ghrelin (2.5-10 pmol), NPY's (50 pmol) effects on eating and RQ were potentiated. Overall, these data are in agreement with evidence suggesting that ghrelin functions as a gut-brain endocrine hormone implicated in the regulation of food intake and energy metabolism. Our findings are also consistent with a possible interactive role of hypothalamic ghrelin and NPY systems.     

Variations of femoral condyle shape

The aim of this study is to mathematically approximate the shape of the femoral articulating line and compare radiuses of condylar curves within and between males and females. Ten male and ten female participants were included in the study. Radiuses of medial and lateral condylar curves were calculated from the side view knee X-ray by original mathematical equation. Average radiuses of condylar curves were between 4.5 and 1.7 cm medially, and between 3.2 and 1.8 cm laterally, for 0 degrees and 90 degrees flexion contact point respectively. Males had longer curve radiuses of both condyles (p < 0.05). Differences turned out to be statistically insignificant after adjusting to body height. Even small changes in the joint geometry during lifetime could make a joint susceptible to osteoarthritis or injuries. Approximation of the radiuses of femoral condyle curves is a useful method in anthropometric, radiological and virtual calculations of the knee geometry, and other ellipsoidal structures in human body, like wrist, scull segments, dental arches, etc.     

HLA-A*0201, HLA-A*1101, and HLA-B*0702 transgenic mice recognize numerous poxvirus determinants from a wide variety of viral gene products

In virus models explored in detail in mice, CTL typically focus on a few immunodominant determinants. In this study we use a multipronged approach to understand the diversity of CTL responses to vaccinia virus, a prototypic poxvirus with a genome approximately 20-fold larger than that of the model RNA viruses typically studied in mice. Based on predictive computational algorithms for peptide binding to HLA supertypes, we synthesized a panel of 2889 peptides to begin to create an immunomic map of human CTL responses to poxviruses. Using this panel in conjunction with CTLs from vaccinia virus-infected HLA transgenic mice, we identified 14 HLA-A*0201-, 4 HLA-A*1101-, and 3 HLA-B*0702-restricted CD8(+) T cell determinants distributed over 20 distinct proteins. These peptides were capable of binding one or multiple A2, A3, and B7 supertype molecules with affinities typical of viral determinants. Surprisingly, many of the viral proteins recognized are predicted to be late gene products, in addition to the early intermediate gene products expected. Nearly all of the determinants identified have identical counterparts encoded by modified vaccinia virus Ankara as well as variola virus, the agent of smallpox. These findings have implications for the design of new smallpox vaccines and the understanding of immune responses to large DNA viruses in general.     

Photoautotrophic micropropagation of Russet Burbank Potato

The photoautotrophic micropropagation of potato cv. Russet Burbank was investigated. Single node microcuttings were grown for four weeks on Murashige and Skoog (MS) medium with or without sucrose (30 g l^–1) in the growth room at 21/19 °C day/night temperature, with 16-h photoperiod at 150 mol m^–2 s^–1, with or without supplemental CO₂ at 1500 l l^–1. A 20% increase in the number of nodes per stem (from 7.5 to 9.4) and a 50% increase in stem dry weight were observed in cultures grown on media with sucrose and in CO₂ enriched atmosphere comparing to the conventionally micropropagated cultures or the cultures grown photoautotrophically on media without sucrose but in air supplemented with 1500 l l^–1CO₂. Stems of these cultures (from media with sucrose in CO₂ enriched air) almost doubled in length the stems of cultures from the other two treatments. No significant differences were observed between Control (MS medium supplemented with sucrose, 30 g l^–1) and photoautotrophic cultures coming from MS medium with no sucrose grown under 1500 l l^–1 of CO₂. Photoautotrophic cultures produced stems averaging 43.3 mm, with 7 nodes and weighing 9.2 mg (dry weight), similar to conventionally grown in vitro cultures (47.9 mm with 7.5 nodes, 9.7 mg dry weight). Growers may consider photoautotrophic culturing of potato in areas where the high sterility levels are difficult to maintain. Supplementing air in the growth room with 1500 l l^–1 of CO₂ could be beneficial for potato plantlet production even on media containing sucrose since it significantly improved quality, size and biomass of produced plantlets, speeding up the multiplication.