The foreign antigen binding site and T cell recognition regions of class I histocompatibility antigens

Most of the polymorphic amino acids of the class I histocompatibility antigen, HLA-A2, are clustered on top of the molecule in a large groove identified as the recognition site for processed foreign antigens. Many residues critical for T-cell recognition of HLA are located in this site, in positions allowing them to serve as ligands to processed antigens. These findings have implications for how the products of the major histocompatibility complex (MHC) recognize foreign antigens.     

Mice lacking the folic acid-binding protein Folbp1 are defective in early embryonic development.

Periconceptional folic acid supplementation reduces the occurrence of several human congenital malformations, including craniofacial, heart and neural tube defects. Although the underlying mechanism is unknown, there may be a maternal-to-fetal folate-transport defect or an inherent fetal biochemical disorder that is neutralized by supplementation. Previous experiments have identified a folate-binding protein (Folbp1) that functions as a membrane receptor to mediate the high-affinity internalization and delivery of folate to the cytoplasm of the cell. In vitro, this receptor facilitates the accumulation of cellular folate a thousand-fold relative to the media, suggesting that it may be essential in cytoplasmic folate delivery in vivo. The importance of an adequate intracellular folate pool for normal embryogenesis has long been recognized in humans and experimental animals. To determine whether Folbp1 is involved in maternal-to-fetal folate transport, we inactivated Folbp1 in mice. We also produced mice lacking Folbp2, another member of the folate receptor family that is GPI anchored but binds folate poorly. Folbp2-/- embryos developed normally, but Folbp1-/- embryos had severe morphogenetic abnormalities and died in utero by embryonic day (E) 10. Supplementing pregnant Folbp1+/- dams with folinic acid reversed this phenotype in nullizygous pups. Our results suggest that Folbp1 has a critical role in folate homeostasis during development, and that functional defects in the human homologue (FOLR1) of Folbp1 may contribute to similar defects in humans.     

Structure of the human class I histocompatibility antigen, HLA-A2

The class I histocompatibility antigen from human cell membranes has two structural motifs: the membrane-proximal end of the glycoprotein contains two domains with immunoglobulin-folds that are paired in a novel manner, and the region distal from the membrane is a platform of eight antiparallel beta-strands topped by alpha-helices. A large groove between the alpha-helices provides a binding site for processed foreign antigens. An unknown 'antigen' is found in this site in crystals of purified HLA-A2.     

Partial revision of the Indo-Australian braconine wasp genus Gammabracon Quicke (Hymenoptera: Braconidae) with descriptions of new species from Indonesia (Mollucas), Malaysia,Philippines and Thailand

Ten distinctive new species of the taxonomically difficult braconine wasp genus Gammabracon Quicke, 1984 are described: G. apicoluteus sp. nov. from Malaysia (Negri); G. curticornis sp. nov. from Malaysia (Negri); G. philippinensis sp. nov. from the Philippines; G. siamensis sp. nov. from Thailand; G. striatus sp. nov. from West Malaysia; G. strandorum sp. nov. from Indonesia (Java), G. subvena sp. nov. from Malaysia (Negri and Sabah); G. townesorum sp. nov. from the Philippines; G. variipennis sp. nov. from Thailand; and G. wegeneri sp. nov. from Indonesia. Myosoma forticarinata Cameron, 1902 is transferred to Gammabracon, hence Gammabracon forticarinata comb. nov. A lectotype is designated for Gammabracon erythroura (Cameron). The status of Cratobracon strandiellus (Cameron) is discussed and a new combination proposed, Shelfordia strandiellus Cameron, 1910 comb. nov. (=Bracon strandiellus Cameron). Paucity of discrete morphological variation makes separation of most of the species with orange-red mesosoma, black metasoma and conspicuous back setae currently unrealistic and it may be that there is a single widespread and morphologically variable species.

http://zoobank.org/urn:lsid:zoobank.org:pub:56B8884E-99C8-4B53-9747-D011F552312D