Sequence of a complete chicken BG haplotype shows dynamic expansion and contraction of two gene lineages with particular expression patterns.

Many genes important in immunity are found as multigene families. The butyrophilin genes are members of the B7 family, playing diverse roles in co-regulation and perhaps in antigen presentation. In humans, a fixed number of butyrophilin genes are found in and around the major histocompatibility complex (MHC), and show striking association with particular autoimmune diseases. In chickens, BG genes encode homologues with somewhat different domain organisation. Only a few BG genes have been characterised, one involved in actin-myosin interaction in the intestinal brush border, and another implicated in resistance to viral diseases. We characterise all BG genes in B12 chickens, finding a multigene family organised as tandem repeats in the BG region outside the MHC, a single gene in the MHC (the BF-BL region), and another single gene on a different chromosome. There is a precise cell and tissue expression for each gene, but overall there are two kinds, those expressed by haemopoietic cells and those expressed in tissues (presumably non-haemopoietic cells), correlating with two different kinds of promoters and 5' untranslated regions (5'UTR). However, the multigene family in the BG region contains many hybrid genes, suggesting recombination and/or deletion as major evolutionary forces. We identify BG genes in the chicken whole genome shotgun sequence, as well as by comparison to other haplotypes by fibre fluorescence in situ hybridisation, confirming dynamic expansion and contraction within the BG region. Thus, the BG genes in chickens are undergoing much more rapid evolution compared to their homologues in mammals, for reasons yet to be understood.This is the final published version. It was originally published by PLOS in PLOS Genetics here: http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1004417

Potassium Channel and NKCC Cotransporter Involvement in Ocular Refractive Control Mechanisms

Myopia affects well over 30% of adult humans globally. However, the underlying physiological mechanism is little understood. This study tested the hypothesis that ocular growth and refractive compensation to optical defocus can be controlled by manipulation of potassium and chloride ion-driven transretinal fluid movements to the choroid. Chicks were raised with +/−10D or zero power optical defocus rendering the focal plane of the eye in front of, behind, or at the level of the retinal photoreceptors respectively. Intravitreal injections of barium chloride, a non-specific inhibitor of potassium channels in the retina and RPE or bumetanide, a selective inhibitor of the sodium-potassium-chloride cotransporter were made, targeting fluid control mechanisms. Comparison of refractive compensation to 5mM Ba2+ and 10−5 M bumetanide compared with control saline injected eyes shows significant change for both positive and negative lens defocus for Ba2+ but significant change only for negative lens defocus with bumetanide ; ; ; ; ; ). Vitreous chamber depths showed a main effect for drug conditions with less depth change in response to defocus shown for Ba2+ relative to Saline, while bumetanide injected eyes showed a trend to increased depth without a significant interaction with applied defocus. The results indicate that both K channels and the NKCC cotransporter play a role in refractive compensation with NKCC blockade showing far more specificity for negative, compared with positive, lens defocus. Probable sites of action relevant to refractive control include the apical retinal pigment epithelium membrane and the photoreceptor/ON bipolar synapse. The similarities between the biometric effects of NKCC inhibition and biometric reports of the blockade of the retinal ON response, suggest a possible common mechanism. The selective inhibition of refractive compensation to negative lens in chick by loop diuretics such as bumetanide suggests that these drugs may be effective in the therapeutic management of human myopia

High-Resolution Imaging of the Retinal Nerve Fiber Layer in Normal Eyes Using Adaptive Optics Scanning Laser Ophthalmoscopy

To conduct high-resolution imaging of the retinal nerve fiber layer (RNFL) in normal eyes using adaptive optics scanning laser ophthalmoscopy (AO-SLO).AO-SLO images were obtained in 20 normal eyes at multiple locations in the posterior polar area and a circular path with a 3-4-mm diameter around the optic disc. For each eye, images focused on the RNFL were recorded and a montage of AO-SLO images was created.AO-SLO images for all eyes showed many hyperreflective bundles in the RNFL. Hyperreflective bundles above or below the fovea were seen in an arch from the temporal periphery on either side of a horizontal dividing line to the optic disc. The dark lines among the hyperreflective bundles were narrower around the optic disc compared with those in the temporal raphe. The hyperreflective bundles corresponded with the direction of the striations on SLO red-free images. The resolution and contrast of the bundles were much higher in AO-SLO images than in red-free fundus photography or SLO red-free images. The mean hyperreflective bundle width around the optic disc had a double-humped shape; the bundles at the temporal and nasal sides of the optic disc were narrower than those above and below the optic disc (P<0.001). RNFL thickness obtained by optical coherence tomography correlated with the hyperreflective bundle widths on AO-SLO (P<0.001)AO-SLO revealed hyperreflective bundles and dark lines in the RNFL, believed to be retinal nerve fiber bundles and Müller cell septa. The widths of the nerve fiber bundles appear to be proportional to the RNFL thickness at equivalent distances from the optic disc

Age-dependent alteration of TGF-β signalling in osteoarthritis

Osteoarthritis (OA) is a disease of articular cartilage, with aging as the main risk factor. In OA, changes in chondrocytes lead to the autolytic destruction of cartilage. Transforming growth factor-β has recently been demonstrated to signal not only via activin receptor-like kinase 5 (ALK5)-induced Smad2/3 phosphorylation, but also via ALK1-induced Smad1/5/8 phosphorylation in articular cartilage. In aging cartilage and experimental OA, the ratio ALK1/ALK5 has been found to be increased, and the expression of ALK1 is correlated with matrix metalloproteinase-13 expression. The age-dependent shift towards Smad1/5/8 signalling might trigger the differentiation of articular chondrocytes with an autolytic phenotype

What does the structure-function relationship of the HIV-1 Tat protein teach us about developing an AIDS vaccine?

The human immunodeficiency virus type 1 (HIV-1) trans-activator of transcription protein Tat is an important factor in viral pathogenesis. In addition to its function as the key trans-activator of viral transcription, Tat is also secreted by the infected cell and taken up by neighboring cells where it has an effect both on infected and uninfected cells. In this review we will focus on the relationship between the structure of the Tat protein and its function as a secreted factor. To this end we will summarize some of the exogenous functions of Tat that have been implicated in HIV-1 pathogenesis and the impact of structural variations and viral subtype variants of Tat on those functions. Finally, since in some patients the presence of Tat-specific antibodies or CTL frequencies are associated with slow or non-progression to AIDS, we will also discuss the role of Tat as a potential vaccine candidate, the advances made in this field, and the importance of using a Tat protein capable of eliciting a protective or therapeutic immune response to viral challenge

Modulation of murine granulocyte proliferation in diffusion chamber cultures

Normal mouse marrow cells were cultured in Millipore diffusion chambers for long periods of time and at a variety of cell concentrations. All cultures showed a pattern of granulocyte proliferation characterized by logarithmic growth followed by prolonged stabilization of cell number starting a 7 days thereafter. The height of this “plateau” varied in relationship to the level of cell input and characteristically was far lower than the maximum cell density that can be maintained in this culture system. Additional studies showed that the plateau represented a steady state of granulocyte turnover and was not due to alterations in the diffusion chambers or the host mice. Regulatory mechanisms intrinsic to the cultured cell population appeared to play a primary role in maintaining this stable plateau. Modulation of granulocyte proliferation was partly due to increasing cell density; particularly with high input concentrations. In addition, differential cell counts suggested that critical changes in the relationship between immature and mature granulocytes partially accounted for this apparent autoregulation of cell growth. The plateau period in diffusion chamber cultures in many ways resembles granulocyte proliferation in normal mouse bone marrow and is a useful model for the study of regulatory functions in granulocytopoiesis.</jats:p

Modulation of murine granulocyte proliferation in diffusion chamber cultures

Abstract Normal mouse marrow cells were cultured in Millipore diffusion chambers for long periods of time and at a variety of cell concentrations. All cultures showed a pattern of granulocyte proliferation characterized by logarithmic growth followed by prolonged stabilization of cell number starting a 7 days thereafter. The height of this “plateau” varied in relationship to the level of cell input and characteristically was far lower than the maximum cell density that can be maintained in this culture system. Additional studies showed that the plateau represented a steady state of granulocyte turnover and was not due to alterations in the diffusion chambers or the host mice. Regulatory mechanisms intrinsic to the cultured cell population appeared to play a primary role in maintaining this stable plateau. Modulation of granulocyte proliferation was partly due to increasing cell density; particularly with high input concentrations. In addition, differential cell counts suggested that critical changes in the relationship between immature and mature granulocytes partially accounted for this apparent autoregulation of cell growth. The plateau period in diffusion chamber cultures in many ways resembles granulocyte proliferation in normal mouse bone marrow and is a useful model for the study of regulatory functions in granulocytopoiesis.</jats:p

Unregulated growth of murine leukemic cells and suppression of normal granulocyte growth in diffusion chamber cultures

Abstract The patterns of proliferation of C1498 mouse acute leukemic cells have been studied using the diffusion chamber technique of cell culture. These malignant cells grow to the same maximal cell concentration irrespective of initial cell input. Leukemic cells proliferate equally well with or without the stimulus of prior host irradiation. When cells cultured for several days are diluted to the original input concentration and recultured, they rapidly proliferate back to maximal cell number. All of these findings are in sharp contrast to the behavior of granulocytes from normal mouse marrow grown in the same culture system. Co-culutre of equal numbers of normal marrow cells and leukemic cells results in virtually complete inhibition of normal marrow cells and leukemic cells results in virtually complete inhibition of normal granulocyte growth. These experiments provide a means of studying malignant growth of leukemic cells, as compared to the controlled growth and differentiation of normal granulocytes, and mechanisms by which leukemic cells suppress normal granulocyte development.</jats:p