| 1. |
- Marti Mus, Monica, et al.
(författare)
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A Complete Reconstruction of the Hyolithid Skeleton
- 2014
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Ingår i: Journal of Paleontology. - : Cambridge University Press (CUP). - 0022-3360 .- 1937-2337. ; 88:1, s. 160-170
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Tidskriftsartikel (refereegranskat)abstract
- Hyolithids are a group of Paleozoic lophotrochozoans with a four-pieced skeleton consisting of a conch, an operculum, and a pair of lateral 'spines' named helens. Both the conch and operculum are relatively well known and, to a certain extent, have modern analogues in other lophotrochozoan groups. The helens, on the other hand, are less well known and do not have clear modern analogues. This has hindered the knowledge of the complete morphology of the hyolithid skeleton, as well as other aspects of hyolithid biology, such as the organization of soft parts, and their ability to move. The material studied herein, consisting of disarticulated skeletal elements from the Silurian of Gotland, Sweden, illustrates a complete developmental sequence of a hyolithid species and includes the first complete, three-dimensionally preserved helens. Our material confirms that helens were massive skeletal elements, whose growth started proximally with the deposition of a central, coherent lamella. Further shell accretion took place around this lamella, but followed a particular accretion pattern probably constrained by the presence of marginal muscle attachment sites on the proximal-most portion of the helens. These muscle attachment sites were ideally located to allow a wide range of movements for the helens, suggesting that hyolithids may have been relatively mobile organisms.
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| 2. |
- Yilmaz-Elis, A Seda, et al.
(författare)
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FcγRIIb on myeloid cells rather than on B cells protects from collagen-induced arthritis
- 2014
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 192:12, s. 5540-5547
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Tidskriftsartikel (refereegranskat)abstract
- Extensive analysis of a variety of arthritis models in germline KO mice has revealed that all four receptors for the Fc part of IgG (FcγR) play a role in the disease process. However, their precise cell type-specific contribution is still unclear. In this study, we analyzed the specific role of the inhibiting FcγRIIb on B lymphocytes (using CD19Cre mice) and in the myeloid cell compartment (using C/EBPαCre mice) in the development of arthritis induced by immunization with either bovine or chicken collagen type II. Despite their comparable anti-mouse collagen autoantibody titers, full FcγRIIb knockout (KO), but not B cell-specific FcγRIIb KO, mice showed a significantly increased incidence and severity of disease compared with wild-type control mice when immunized with bovine collagen. When immunized with chicken collagen, disease incidence was significantly increased in pan-myeloid and full FcγRIIb KO mice, but not in B cell-specific KO mice, whereas disease severity was only significantly increased in full FcγRIIb KO mice compared with incidence and severity in wild-type control mice. We conclude that, although anti-mouse collagen autoantibodies are a prerequisite for the development of collagen-induced arthritis, their presence is insufficient for disease development. FcγRIIb on myeloid effector cells, as a modulator of the threshold for downstream Ab effector pathways, plays a dominant role in the susceptibility to collagen-induced arthritis, whereas FcγRIIb on B cells, as a regulator of Ab production, has a minor effect on disease susceptibility.
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