CLUSTERING POPULATIONS BY MIXED LINEAR MODELS

INTRODUCTIONInevolutionstudiesandplant(oranimal)breedingresearch,clusteranalysesarewidelyusedforgroupingpopulations.Therehavebeenalotofmethodsdevelopedforgroupingpopulations(SneathandSokal,1973;Eve-ritt,1993).Variousmethodsaredifferedinthewaysfordistance(…     

SELECTION ON POLEMONIUM BRANDEGEEI (POLEMONIACEAE) FLOWERS UNDER HUMMINGBIRD POLLINATION: IN OPPOSITION,PARALLEL, OR INDEPENDENT OF SELECTION BY HAWKMOTHS?

Particular floral phenotypes are often associated with specific groups of pollinators. However, flowering plants are often visited, and may be effectively pollinated by more than one type of animal. Therefore, a major outstanding question in floral biology asks: what is the nature of selection on floral traits when pollinators are diverse? This study examined how hummingbirds selected on the floral traits of Polemonium brandegeei, a species pollinated by both hummingbirds and hawkmoths. In array populations of P. brandegeei, we measured pollen movement, and female (seeds set) and male (seeds sired) fitness under hummingbird pollination. We then compared the patterns of selection by hummingbirds with our previous study examining selection by hawkmoths. We documented contrasting selection on sex organ positioning through female function, with hummingbirds selecting for stigmas exserted beyond the anthers and hawkmoths selecting for stigmas recessed below the anthers. Furthermore, hummingbirds selected for longer and wider corolla tubes, and hawkmoths selected for narrower corolla tubes. Therefore, contrasting selection by hawkmoths and hummingbirds may account for variation in sex organ arrangements and corolla dimensions in P. brandegeei. We documented how floral traits under selection by multiple pollinators can result in either an intermediate “compromise” between selective pressures (sex organs) or apparent specialization (corolla tube length) to one pollinator.     

β-GLUCOSIDASE BY THERM OPHILIC AND ANAEROBIC CLOSTRIDIOM THERMOCOPRIAE

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STUDIES ON THE ULTRASTRUCTURE OF THE PREMATURE OVA OF TAENIARHYNCHUS SAGIN ATUS GOEZE,1782.BY SCANNING ELECTRON MICROSCOPE

In this article, we present the observations of the ova of Taenidae whichretain(?), as seen under scanning electron microscope, the premature ova of theTacniarhynchus saginatus. An ovum comprises seven layers, which actually interpenetrate and interplay as a complete system. When the ovum becomes maturethe capsule breaks, the yolk cells and the vitelline membrane undergo degenerative thanges, but the embryophorc and the hexocanth embryo grow into completion.     

CYCLOSPORIN A INHIBITS THE IN VIVO PRODUCTION OF INTERLEUKIN-1β AND TUMOUR NECROSIS FACTOR α, BUT NOT INTERLEUKIN-6, BY A T-CELL-INDEPENDENT MECHANISM

The effect of cyclosporin A (CsA) on cytokine production in the tissue chamber model of acute inflammation was investigated. CsA caused a dose-related inhibition of interleukin 1β (IL-1β) production in both normal and athymic mice, confirming earlier conclusions that this effect is not T cell dependent (ED₅₀s 40 and 53 mg/kg p.o., respectively).Tumour necrosis factor alpha (TNF-α) levels were similarly affected with ED₅₀s of 40 and 58 mg/kg p.o. for normal and athymic mice, respectively. By contrast, CsA inhibited interleukin 6 (IL-6) production only in normal mice (ED₅₀27 mg/kg p.o.)Differences in the absolute production of the three cytokines in normal and athymic mice were also noted. IL-1β and IL-6 levels were two-fold higher in athymic mice, while for TNF-α, there was no difference between the two groups.The present findings support the authors' original hypothesis, that the inhibitory mechanism of CsA on IL-1β is not mediated via T cells. The same mechanism also seems responsible for the inhibition of TNF-α production, but not for IL-6, where inhibition by CsA appears to require the presence of T cells.     

A MODEL FOR A TUMOR ATTACKED BY THE IMMUNE SYSTEM

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GENETIC HARM: BITTEN BY THE BODY THAT KEEPS YOU?

... We must attempt to explain, how, if ever, our existence may harm us. To address this and the other questions raised, I propose to examine what constitutes harm and whether it makes sense to say that our genetic makeup may harm us. To do this I will describe three approaches to the problem of describing the status of negative effects our genes have upon us, which I have named the "technical harm" view, the "constitutive" view, and the "harmful conditions" view. On the technical harm view, the standard definitions of harm are applied to genetic disposition in an attempt to couch genetic defects or flaws in terms of harming. The constitutive view rejects applying the concept of harm to genetic disposition on the grounds that it is impossible to separate genetic disposition from individual identity. Lastly, the harmful conditions view, which I conclude is the most successful of the three, focuses on the tendency of certain genetic dispositions to cause harm in the future and thus avoids what I will argue are the "context" shortcomings of the other two approaches. To conclude the discussion I will very briefly analyze the ramifications of a harmful conditions view for the concept of genetic disease and the prospects for genetic counseling, gene therapy, and reproductive decision making.     

LIPOSOME (LIPODINE™)-MEDIATED DNA VACCINATION BY THE ORAL ROUTE

ABSTRACT

Plasmid DNA pRc/CMV HBS encoding the S (small) region of hepatitis B surface antigen (HBsAg) was incorporated by the dehydration–rehydration method into Lipodine? liposomes composed of 16 µmoles phosphatidylcholine (PC) or distearoyl phosphatidylcholine (DSPC), 8 µmoles of (dioleoyl phosphatidylethanolamine (DOPE) or cholesterol and 4 µmoles of the cationic lipid 1,2-dioleoyl-3-(trimethylammonium propane (DOTAP) (molar ratios 1 : 0.5 : 0.25). Incorporation efficiency was high (89–93% of the amount of DNA used) in all four formulations tested and incorporated DNA was shown to be resistant to displacement in the presence of the competing anionic sodium dodecyl sulphate molecules. This is consistent with the notion that most of the DNA is incorporated within the multilamellar vesicles structure rather than being vesicle surface-complexed. Stability studies performed in simulated intestinal media also demonstrated that dehydration–rehydration vesicles (DRV) incorporating DNA (DRV(DNA)) were able to retain significantly more of their DNA content compared to DNA complexed with preformed small unilamellar vesicles (SUV–DNA) of the same composition. Moreover, after 4h incubation in the media, DNA loss for DSPC DRV(DNA) was only minimal, suggesting this to be the most stable formulation. Oral (intragastric) liposome-mediated DNA immunisation studies employing a variety of DRV(DNA) formulations as well as naked DNA revealed that secreted IgA responses against the encoded HBsAg were (as early as three weeks after the first dose) substantially higher after dosing with 100 µg liposome-entrapped DNA compared to naked DNA. Throughout the fourteen week investigation, IgA responses in mice were consistently higher with the DSPC DRV(DNA) liposomes compared to naked DNA and correlated well with their improved DNA retention when exposed to model intestinal fluids. To investigate gene expression after oral (intragastric) administration, mice were given 100 µg of naked or DSPC DRV liposome-entrapped plasmid DNA expressing the enhanced green fluorescent protein (pCMV.EGFP). Expression of the gene, in terms of fluorescence intensity in the draining mesenteric lymph nodes, was much greater in mice dosed with liposomal DNA than in animals dosed with the naked DNA. These results suggest that DSPC DRV liposomes containing DNA (Lipodine?) may be a useful system for the oral delivery of DNA vaccines.     

β-ADRENOCEPTOR-MEDIATED RELAXATION INHIBITED BY TETRAPENTYLAMMONIUM IONS IN RAT MESENTERIC ARTERY

The aim of this study was to examine the contribution of K⁺ channel activation to β-adrenoceptor-mediated relaxation in rat mesenteric arteries. Isoprenaline and fenoterol concentration-dependently relaxed the phenylephrine-preconstricted endothelium-intact arteries of the rat with EC₅₀ values of 0.26 ± 0.03 μM and 0.87 ± 0.12 μM, respectively. β-Adrenoceptor-mediated relaxation was significantly attenuated upon removal of endothelium. Tetrapentylammonium ions (TPA⁺) at low concentrations (1–5 μM) inhibited relaxations induced by β-adrenoceptor agonists in arteries with and without endothelium, while glibenclamide (3 μM) had no effect. TPA⁺ (5 μM) inhibited isoprenaline-induced relaxation in the presence of either iberiotoxin (100 nM) or glibenclamide (3 μM). TPA⁺ did not alter forskolin-induced relaxation. In the presence of 60 mM extracellular K⁺, the relaxations induced by two agonists were reduced in endothelium-intact arteries and abolished in endothelium-denuded arteries. The present results suggest that the activation of TPA⁺-sensitive K⁺ channels contributes toward the relaxations mediated through β- and β₂-adrenoceptor stimulation in rat mesenteric arteries. © 1998 Elsevier Science Inc.     

Gold for Ubiquitin in Vancouver: FIRST CONFERENCE ON PROTEOMICS OF PROTEIN DEGRADATION AND UBIQUITIN PATHWAYS HELD JUNE 6–8, 2010 IN VANCOUVER,UNIVERSITY OF BRITISH COLUMBIA,ORGANIZED BY LAN HUANG,THIBAULT MAYOR,AND PEIPEI PING*

The rise of proteomics has had tremendous influence on analysis and understanding of the role of post-translational modifications in biological processes. The covalent attachment of small proteins like ubiquitin, SUMO,1 or other ubiquitin-like proteins (Ubls) is one class of post-translational modifications where proteomics has had notable impact. Various proteomics approaches, but in particular mass spectrometry-based analyses, have influenced the field and enabled significant advances over the past few years. The first meeting dedicated to proteomics of protein degradation and ubiquitin pathways showcased these advances and allowed a glimpse at future contributions of proteomics to this field. With its many attractive drug targets, the ubiquitin and proteasome system, as well as other proteolysis pathways, could offer new therapies for various human diseases including cancer and neurodegenerative disorders.The covalent linkage of ubiquitin to other proteins is catalyzed by the E1-E2-E3 cascade of enzymatic reactions whereby the many different E3 ubiquitin ligases provide substrate specificity to the process of protein ubiquitylation (1). Ubiquitylation is best known for targeting proteins for degradation by the proteasome, but other functions for ubiquitylation independent of proteolysis are also known. Likewise, modifications with SUMO or other Ubls generally do not regulate protein degradation but instead control subcellular localization, protein interactions, or change protein conformation and activity (2).The questions addressed by proteomics approaches to ubiquitylation and Ubl modifications are plentiful. They range from very specific, e.g. determination of the modified residue in a substrate protein, to complex, such as protein dynamics in proteome-wide ubiquitin (or Ubl) modification profiles (3). In either case, the rapid technological advancements (particularly in mass spectrometry instrumentation as well as quantitation and separation technologies) have allowed impressive progress, which was evident in the First Conference on Proteomics of Protein Degradation and Ubiquitin Pathways in Vancouver (http://ppdup.org/) (Fig. 1).Open in a separate windowFig. 1.Group picture from First Conference on Proteomics of Protein Degradation and Ubiquitin Pathways held June 6–8, 2010 in Vancouver (http://ppdup.org/).     

ANALYSIS OF LIGAND–RECEPTOR INTERACTIONS IN CELLS BY ATOMIC FORCE MICROSCOPY

ABSTRACT

Atomic force microscopy (AFM) increasingly has been used to analyse “receptor” function, either by using purified proteins (“molecular recognition microscopy”) or, more recently, in situ in living cells. The latter approach has been enabled by the use of a modified commercial AFM, linked to a confocal microscope, which has allowed adhesion forces between ligands and receptors in cells to be measured and mapped, and downstream cellular responses analysed. We review the application of AFM to cell biology and, in particular, to the study of ligand–receptor interactions and draw examples from our own work and that of others to show the utility of AFM, including for the exploration of cell surface functionalities. We also identify shortcomings of AFM in comparison to “standard” methods, such as receptor auto-radiography or immuno-detection, that are widely applied in cell biology and pharmacological analysis.     

DEAGGREGATION OF eIF4E INDUCED BY mRNA 5′ CAP BINDING

All eukaryotic mRNAs contain a 5′ terminal cap structure, which consists of 7-methylguanosine linked by a 5′-5′ triphosphate bridge to the first transcribed nucleoside (m⁷GpppN). Specific recognition of the cap by the eukaryotic initiation factor eIF4E plays a key role in regulation of translation initiation as a rate-limiting step. Using dynamic light scattering (DLS), the apo-form of murine eIF4E (33–217) was shown to aggregate. After addition of m⁷GTP, progressive deaggregation with the time of incubation in the presence of the cap analogue has been observed.     

SPECIFIC STIMULATION OF MIGRATION OF HUMAN KERATINOCYTES BY μ -OPIATE RECEPTOR AGONISTS

ABSTRACT

There are several indications that neuropeptides, especially the opiate receptor agonists, modulate the immune response by stimulating the formation of granulation tissue and enhancing the reepithelialization. We observed that the μ-opiate receptor ligand β-endorphin stimulates the migration of cultured human foreskin keratinocytes. After 1?hour exposure to 1?µM β-endorphin, the keratinocytes experienced an increase of cell diameter by cellular elongation and stimulation of migration. Dynorphin had a lesser effect under the same condition. The opiate receptor antagonist naltrexone significantly reduced the effect of β-endorphin on keratinocyte migration. This migratory effect of μ-opiate receptor agonists in vitro indicates that the opioid peptides, released in wounds, could play a key role in the final reepithelialization and tissue regeneration in wound healing. This new knowledge will help us not only to understand the mechanism of wound healing but also to improve the therapeutic strategy in the healing of painful chronic wounds.