Glucocorticoids alter the lipid and protein composition of membrane rafts of a murine T cell hybridoma

Glucocorticoids (GC) are widely used anti-inflammatory agents known to suppress T cell activation by interfering with the TCR activation cascade. The attenuation of early TCR signaling events by these compounds has been recently attributed to a selective displacement of key signaling proteins from membrane lipid rafts. In this study, we demonstrate that GC displace the acyl-bound adaptor proteins linker for activation of T cells and phosphoprotein associated with glycosphingolipid-enriched microdomains from lipid rafts of murine T cell hybridomas, possibly by inhibiting their palmitoylation status. Analysis of the lipid content of the membrane rafts revealed that GC treatment led to a significant decrease in palmitic acid content. Moreover, we found an overall decrease in the proportion of raft-associated saturated fatty acids. These changes were consistent with a decrease in fluorescence anisotropy of isolated lipid rafts, indicating an increase in their fluidity. These findings identify the mechanisms underlying the complex inhibitory effects of glucocorticoids on early TCR signaling and suggest that some of the inhibitory properties of GC on T cell responses may be related to their ability to affect the membrane lipid composition and the palmitoylation status of important signaling molecules.     

Parasite acquisition by the invasive Chinese sleeper (Perccottus glenii Dybowski, 1877) (Gobiiformes: Odontobutidae) in Latvia and Ukraine

The Perccottus glenii is one of the most invasive of European fish species. During August-September 2019, we examined Chinese sleeper from six waterbodies in Latvia and Ukraine for parasites. Seventeen parasite species were registered, including two ciliate species, one coccidia, one monogenean, one cestode, six trematodes, three nematodes, one acanthocephalan, one parasitic copepod, and one bivalve glochidia. Maximum species richness was registered in Ukraine, with eight species at Vylkove and three species at Lake Kartal. Numbers in Latvia were generally lower with three species at Ilgas and just one at Gailezers. The parasite fauna registered in Latvia was poor overall, the richest site being the University pond. Two non-native parasite species were registered, the monogenean Gyrodactylus perccotti and the copepod Neoergasilus japonicus. Gyrodactylus perccotti was observed in Lake Kartal and the Danube delta in Ukraine, but not in Latvia, while N. japonicus only occurred in the University Pond in Latvia. This is the first record of this species in Latvia. Low parasite acquisition by the Chinese sleeper in Latvia may be caused by the release of this fish from aquaria, which is commonly registered in the region. It is likely that such low parasite loads have contributed to the formation of stable populations and the subsequent increase in expansion.     

Naive T cells are resistant to anergy induction by anti-CD3 antibodies

Anti-CD3 mAbs are potent immunosuppressive agents used in clinical transplantation. It has been generally assumed that one of the anti-CD3 mAb-mediated tolerance mechanisms is through the induction of naive T cell unresponsiveness, often referred to as anergy. We demonstrate in this study that naive T cells stimulated by anti-CD3 mAbs both in vivo and in vitro do not respond to the superantigen staphylococcal enterotoxin B nor to soluble forms of anti-CD3 mAbs and APC, but express increased reactivity to plastic-coated forms of the same anti-CD3 mAbs and to their nominal Ag/class II MHC, a finding that is difficult to rationalize with the concept of anergy. Phenotypic and detailed kinetic studies further suggest that a strong signal 1 delivered by anti-CD3 mAbs in the absence of costimulatory molecules does not lead to anergy, but rather induces naive T cells to change their mitogen responsiveness and acquire features of memory T cells. In marked contrast, Ag-experienced T cells are sensitive to anergy induction under the same experimental settings. Collectively, these studies demonstrate that exposure of naive T cells in vivo and in vitro to a strong TCR stimulus does not induce Ag unresponsiveness, indicating that sensitivity to negative signaling through TCR/CD3 triggering is developmentally regulated in CD4(+) T cells.     

Anther culture and Hordeum bulbosum-derived barley doubled haploids mutations and methylation

Anther culture and Hordeum bulbosum-derived doubled haploid (DH) lines of barley (Hordeum vulgare L.) were analyzed for RFLP and RAPD polymorphisms. Polymorphisms were not detected in the anther culture-or H. bulbosum-derived DH lines among 273 RFLP and 89 polymerase chain reaction (PCR)-amplified DNA fragments assayed. It was calculated that base substitution or small deletion/insertion mutations had not been induced among 401 640 by screened. Large deletion/insertion mutations were not observed among 33 Mb screened. Polymorphisms were observed when DNA was digested with the methylation-sensitive restriction enzymes HpaII and MspI: these RFLPs originated primarily from the anther culture-derived doubled haploids. The data indicate that heritable DNA methylation changes had occurred during DH production, particularly with the anther culture method.     

Maintenance of red blood cell integrity by AMP-activated protein kinase α1 catalytic subunit

AMP-activated protein kinase (AMPK) plays a pivotal role in regulating cellular energy metabolism. We previously showed that AMPKα1−/− mice develop moderate anemia associated with splenomegaly and high reticulocytosis. Here, we report that splenectomy of AMPKα1−/− mice worsened anemia supporting evidence that AMPKα1−/− mice developed a compensatory response through extramedullary erythropoiesis in the spleen. Transplantation of bone marrow from AMPKα1−/− mice into wild-type recipients recapitulated the hematologic phenotype. Further, AMPKα1−/− red blood cells (RBC) showed less deformability in response to shear stress limiting their membrane flexibility. Thus, our results highlight the crucial role of AMPK to preserve RBC integrity.     

Male‐Biased Mate Competition in King Penguin Trio Parades

Darwin devised sexual selection theory to explain sexual dimorphisms. Further developments of the theory identified the operational sex‐ratio (OSR) as one of its cornerstones, and it was commonly admitted that an OSR biased toward one sex would lead to stronger selection pressures toward that sex. Recent theoretical developments have challenged this view and showed that the OSR alone does not determine the direction of sexual selection, more particularly in mutually ornamented species exhibiting high and similar parental investment by both sexes. These developments, however, focused on mutual intersexual selection, and little is known about intrasexual selection of both males and females in species exhibiting such characteristics. The first aim of our study was to test the relative involvement of males and females in same‐sex contest over mates in the king penguin, a species exhibiting mutual ornamentation of the sexes, high parental investment by both sexes, and a male‐biased OSR. We investigated the sex composition of trio parades, which are groups of three individuals that compete for mates during pair formation. We found that these trios consist of a female trailed by two fighting males in 19 of 20 cases; the 20th trio was all male. The second aim of our study was to investigate the existence of within‐sex differences in colour ornaments between individuals involved in such trios and individuals already paired. While limited sample sizes precluded detection of statistically significant differences between trios vs. pairs, reflectance measurements suggested that the beak spot of males in trios were more strongly ultraviolet than the beak spot of males in pairs. We concluded that intrasexual selection in our colony follows the typical pattern of mate competition observed in species in which sexual dimorphisms and OSR are male biased, and discussed the ultraviolet difference within the framework of the king penguins' colour perception.     

Permanent Genetic Resources added to Molecular Ecology Resources Database 1 June 2010 - 31 July 2010

This article documents the addition of 205 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Bagassa guianensis, Bulweria bulwerii, Camelus bactrianus, Chaenogobius annularis, Creontiades dilutus, Diachasmimorpha tryoni, Dioscorea alata, Euhrychiopsis lecontei, Gmelina arborea, Haliotis discus hannai, Hirtella physophora, Melanaphis sacchari, Munida isos, Thaumastocoris peregrinus and Tuberolachnus salignus. These loci were cross-tested on the following species: Halobaena caerulea, Procellaria aequinoctialis, Oceanodroma monteiroi, Camelus ferus, Creontiades pacificus, Dioscorea rotundata, Dioscorea praehensilis, Dioscorea abyssinica, Dioscorea nummularia, Dioscorea transversa, Dioscorea esculenta, Dioscorea pentaphylla, Dioscorea trifida, Hirtella bicornis, Hirtella glandulosa, Licania alba, Licania canescens, Licania membranaceae, Couepia guianensis and 7 undescribed Thaumastocoris species.     

Permanent genetic resources added to Molecular Ecology Resources Database 1 February 2012 - 31 March 2012

This article documents the addition of 171 microsatellite marker loci and 27 pairs of single nucleotide polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Bombus pauloensis, Cephalorhynchus heavisidii, Cercospora sojina, Harpyhaliaetus coronatus, Hordeum vulgare, Lachnolaimus maximus, Oceanodroma monteiroi, Puccinia striiformis f. sp. tritici, Rhea americana, Salmo salar, Salmo trutta, Schistocephalus solidus, Sousa plumbea and Tursiops aduncus. These loci were cross-tested on the following species: Aquila heliaca, Bulweria bulwerii, Buteo buteo, Buteo swainsoni, Falco rusticolus, Haliaeetus albicilla, Halobaena caerulea, Hieraaetus fasciatus, Oceanodroma castro, Puccinia graminis f. sp. Tritici, Puccinia triticina, Rhea pennata and Schistocephalus pungitii. This article also documents the addition of 27 sequencing primer pairs for Puffinus baroli and Bulweria bulwerii and cross-testing of these loci in Oceanodroma castro, Pelagodroma marina, Pelecanoides georgicus, Pelecanoides urinatrix, Thalassarche chrysostoma and Thalassarche melanophrys.     

Crystal structure of human gamma-butyrobetaine hydroxylase

Gamma-butyrobetaine hydroxylase (GBBH) is a 2-ketoglutarate-dependent dioxygenase that catalyzes the biosynthesis of l-carnitine by hydroxylation of gamma-butyrobetaine (GBB). l-carnitine is required for the transport of long-chain fatty acids into mitochondria for generating metabolic energy. The only known synthetic inhibitor of GBBH is mildronate (3-(2,2,2-trimethylhydrazinium) propionate dihydrate), which is a non-hydroxylatable analog of GBB.To aid in the discovery of novel GBBH inhibitors by rational drug design, we have solved the three-dimensional structure of recombinant human GBBH at 2.0 Å resolution. The GBBH monomer consists of a catalytic double-stranded β-helix (DBSH) domain, which is found in all 2KG oxygenases, and a smaller N-terminal domain. Extensive interactions between two monomers confirm earlier observations that GBBH is dimeric in its biological state. Although many 2KG oxygenases are multimeric, the dimerization interface of GBBH is very different from that of related enzymes.The N-terminal domain of GBBH has a similar fold to the DUF971 superfamily, which consists of several short bacterial proteins with unknown function. The N-terminal domain has a bound Zn ion, which is coordinated by three cysteines and one histidine. Although several other 2KG oxygenases with known structures have more than one domain, none of them resemble the N-terminal domain of GBBH. The N-terminal domain may facilitate dimer formation, but its precise biological role remains to be discovered.The active site of the catalytic domain of GBBH is similar to that of other 2KG oxygenases, and Fe(II)-binding residues form a conserved His-X-Asp-X_n-His triad, which is found in all related enzymes.