Genetic manipulation of CD74 in mouse strains of different backgrounds can result in opposite responses to central nervous system injury

The ability to recover from CNS injuries is strain dependent. Transgenic mice that weakly express the p41 CD74 isoform (an integral membrane protein functioning as a MHC class II chaperone) on an I-A(b) genetic background have normal CD4(+) T cell populations and normal surface expression of MHC class II, but their B cell development is arrested while the cells are still immature. After a CNS injury, these mice recover better than their matched wild-type controls. We generated p41-transgenic mice on an I-A(d) background (p41-I-A(d) mice), and found that their recovery from CNS injuries was worse than that of controls. A correlative inverse effect was seen with respect to the kinetics of T cell and B cell recruitment to the injured CNS and the expression of insulin-like growth factor at the lesion site. These results, besides verifying previous findings that B cells function in the damaged CNS, demonstrate that the outcome of a particular genetic manipulation may be strain dependent.     

Long-term functional outcomes after 10 years of bilateral cochlear implantat use

The aims were to determine the benefit of bilateral cochlear implantation in a 20 years old patient implanted in Croatia on hearing and speech development. The male patient, after 10 years of deafness, got cochlear implants Med-EL Combi 40+ on both sides in one-stage surgery. The etiology of his deafness was posttraumatic meningitis. Auditory capacity and speech recognition tests were performed for both ears separately and together Average hearing level on the right ear with right cochlear implant switched on started at 62 dB 1 month after the cochlear implantation and was on 55 dB after 10 years. Average hearing level on the left ear with left cochlear implant switched on started at 55 dB 1 month after the cochlear implantation and was on 32 dB after 10 years. Average hearing level on the both ears with 2 cochlear implants switched on started at 35 dB 1 month after the cochlear implantation and was on 27 dB after 10 years. Long-term functional outcomes with bilateral cochlear implantation provides advantages over unilateral implantation including improved hearing level, speech perception in noise and improved sound localization.     

Diverse Lifestyles and Strategies of Plant Pathogenesis Encoded in the Genomes of Eighteen Dothideomycetes Fungi

The class Dothideomycetes is one of the largest groups of fungi with a high level of ecological diversity including many plant pathogens infecting a broad range of hosts. Here, we compare genome features of 18 members of this class, including 6 necrotrophs, 9 (hemi)biotrophs and 3 saprotrophs, to analyze genome structure, evolution, and the diverse strategies of pathogenesis. The Dothideomycetes most likely evolved from a common ancestor more than 280 million years ago. The 18 genome sequences differ dramatically in size due to variation in repetitive content, but show much less variation in number of (core) genes. Gene order appears to have been rearranged mostly within chromosomal boundaries by multiple inversions, in extant genomes frequently demarcated by adjacent simple repeats. Several Dothideomycetes contain one or more gene-poor, transposable element (TE)-rich putatively dispensable chromosomes of unknown function. The 18 Dothideomycetes offer an extensive catalogue of genes involved in cellulose degradation, proteolysis, secondary metabolism, and cysteine-rich small secreted proteins. Ancestors of the two major orders of plant pathogens in the Dothideomycetes, the Capnodiales and Pleosporales, may have had different modes of pathogenesis, with the former having fewer of these genes than the latter. Many of these genes are enriched in proximity to transposable elements, suggesting faster evolution because of the effects of repeat induced point (RIP) mutations. A syntenic block of genes, including oxidoreductases, is conserved in most Dothideomycetes and upregulated during infection in L. maculans, suggesting a possible function in response to oxidative stress.     

Id2 negatively regulates B cell differentiation in the spleen

Early stages of B cell development occur in the bone marrow, resulting in formation of immature B cells. These immature cells migrate to the spleen where they differentiate into mature (B2 or marginal zone (MZ)) cells. This final maturation step is crucial for B cells to become responsive to Ags and to participate in the immune response. Id2 is a helix-loop-helix protein that lacks a DNA-binding region; and therefore, inhibits basic helix-loop-helix functions in a dominant negative manner. In this study, we show that Id2 expression is down-regulated during differentiation of immature B cells into mature B2 and MZ B cells. The high levels of Id2 expressed in the immature B cells result in inhibition of E2A binding activity to an E2 box site. Moreover, mice lacking Id2 show an elevation in the proportion of mature B2 cells in the spleen, while the MZ population in these mice is almost absent. Thus, Id2 acts as a regulator of the differentiation of immature B cells occurring in the spleen, it negatively controls differentiation into mature B2 cells while allowing the commitment to MZ B cells. In the absence of Id2 control, the unregulated differentiation is directed toward the mature B2 population.     

Metal complexes as artificial proteases in proteomics: a palladium(II) complex cleaves various proteins in solutions containing detergents

Most popular agents for site-specific protein cleavage are proteolytic enzymes. Because they become denatured and inactivated by detergents, enzymes are inconvenient for proteomic analysis of hydrophobic proteins which require detergents as solubilizing agents. We used cis-[Pd(en)(H₂O)₂]²⁺ (in which en represents ethylenediamine) as an artificial protease to effect cleavage of three bovine proteins, namely ubiquitin, β-casein, and serum albumin, in separate experiments. Cleavage took place in aqueous solutions containing 1.0% wt./vol. of either 3-[(3-Cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) or Zwittergent 3-14 at 2.5 < pH < 2.9 and 55-60 °C for 3-72 h. Digests were separated by HPLC and analyzed by tandem mass spectrometry. Peptides were identified by de novo sequencing and matched against the bovine genome. Because cleavage by Pd(II) complexes is rather selective and therefore infrequent, 72% of the identified peptides in the digests contained more than 10 amino acid. Palladium(II) complexes hold promise as cleavage agents in proteomics studies of membrane proteins.     

Rhizobacteria associated with Miscanthus x giganteus improve metal accumulation and plant growth in the flotation tailings

Plant and Soil - Flotation tailings represent an extremely unfriendly substrate for plant colonization due to toxic metal concentrations and marked macronutrient deficiencies. The perennial grass...     

Vav1 and Ly-GDI two regulators of Rho GTPases,function cooperatively as signal transducers in T cell antigen receptor-induced pathways

The Rho family GTPases are pivotal for T cell signaling; however, the regulation of these proteins is not fully known. One well studied regulator of Rho GTPases is Vav1; a hematopoietic cell-specific guanine nucleotide exchange factor critical for signaling in T cells, including stimulation of the nuclear factor of activated T cells (NFAT). Surprisingly, Vav1 associates with Ly-GDI, a hematopoietic cell-specific guanine nucleotide dissociation inhibitor of Rac. Here, we studied the functional significance of the interaction between Vav1 and Ly-GDI in T cells. Upon organization of the immunological synapse, both Ly-GDI and Vav1 relocalize to T cell extensions in contact with the antigen-presenting cell. Ly-GDI is phosphorylated on tyrosine residues following T cell receptor stimulation, and it associates with the Src homology 2 region of an adapter protein, Shc. In addition, the interaction between Ly-GDI and Vav1 requires tyrosine phosphorylation. Overexpression of Ly-GDI alone is inhibitory to NFAT stimulation and calcium mobilization. However, when co-expressed with Vav1, Ly-GDI enhances Vav1 induction of NFAT activation, phospholipase Cgamma phosphorylation, and calcium mobilization. Moreover, Ly-GDI does not alter the regulation of these phenomena when coexpressed with oncogenic Vav1. Since oncogenic Vav1 does not bind Ly-GDI, this suggests that the functional cooperativity of Ly-GDI and Vav1 is dependent upon their association. Thus, our data suggest that the interaction of Vav1 and Ly-GDI creates a fine tuning mechanism for the regulation of intracellular signaling pathways leading to NFAT stimulation.     

Preferential Th1 immune response in invariant chain-deficient mice

MHC class II molecules associate with the invariant chain (Ii) molecule during biosynthesis. Ii facilitates the folding of class II molecules, interferes with their peptide association, and is involved in MHC class II transport. In this study, we have investigated the in vitro and in vivo immune response of Ii-deficient mice (Ii(-/-)). Our results have demonstrated that CD4(+) T cells from Ii(-/-) mice proliferate normally in vitro after in vivo immunization with protein Ags. However, cytokine secretion profiles of Ag-primed CD4(+) T cells from Ii(-/-) mice differ from CD4(+) T cells from wild-type mice. Whereas cells from wild-type mice secrete IFN-gamma and IL-4, cells from Ii(-/-) mice secrete mostly IFN-gamma. Moreover, Ii(-/-) mice exhibit a normal Th1 response in the delayed-type hypersensitivity and trinitrobenzene sulfonic acid colitis models; however, these mice lack an in vivo Th2 response, as demonstrated in the asthma model. Therefore, we suggest that defective Ag presentation in Ii(-/-) mice leads selectively to a Th1 effector response.