| 1. |
- Dunham, I, et al.
(författare)
-
The DNA sequence of human chromosome 22
- 1999
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 402:6761, s. 489-495
-
Tidskriftsartikel (refereegranskat)
|
|
| 2. |
- Zhang, Qian, et al.
(författare)
-
Crustacean hyperglycaemic hormone in the nervous system of the primitive crustacean species Daphnia magna and Artemia salina (Crustacea: Branchiopoda)
- 1997
-
Ingår i: Cell and Tissue Research. - 0302-766X .- 1432-0878. ; 287:3, s. 565-576
-
Tidskriftsartikel (refereegranskat)abstract
- Crustacean hyperglycaemic hormone-immunoreactive neuronal systems are detected in the central and peripheral nervous systems of two entomostracan crustaceans, Daphnia magna and Artemia salina, by immunocytochemistry using specific antisera against crustacean hyperglycaemic hormones of the decapod crustaceans Orconectes limosus and Carcinus maenas. In D. magna, four small putative interneurones are detected in the brain. In the thorax, ten bipolar peripheral neurones are stained by both antisera. They are obviously segmental homologues with centrally projecting axons that form interdigitating varicose fibres and terminals in putative neurohaemal areas next to the surface of the anterior part of the thoracic ganglia. Similar immunopositive neurones occur both in the central and peripheral nervous systems of A. salina. A total of five groups of neurones occur in the protocerebrum, the deutocerebrum and the mandibular ganglion. Some of the protocerebral neurones are bipolar and project to the dorsal frontal organ. A single pair of peripheral multipolar neurones in the maxillary segment projects centrally into the ventral nerve cord and innervates unidentified somatic muscles and tissues in the maxillary and the first appendage segments. None of the brain neurones in both species show similarities to decapod X-organ sinus gland neurosecretory neurones. Chromatography of brain extracts of D. magna combined with immunodot blotting revealed two strongly immunoreactive fractions at retention times close to that of the crustacean hyperglycaemic hormone of crayfish. Moreover, preabsorption controls suggest that the cross-reacting peptides of D. magna and A. salina are structurally closely related to those of decapods.
|
|
| 3. |
- Zhang, Qian-Jin
(författare)
-
Influence of MHC class I peptide interaction on antigen presentation in normal and malignant cells
- 1996
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The presentation of MHC class I peptide complexes in normal and malignant cells was studied. An HLA A11 binding motif was defined by comparing synthetic peptide analogues of a known cytotoxic T Iymphocyte (CTL) target epitope for induction of surface A11 expression and triggering of cytotoxic activity. The motif predicts the presence of hydrophobic aminoacids in position 2 (P2), small amino acids in P3 and P6 and Lys in P9. The off-rates of P2 analogues discriminated between "apparent" and "true" binders that formed complexes with a half life longer than 72 hours. The persistence of MHC-peptide complexes the surface of antigen presenting cells was shown to correlate with the immunogenicity two A11-restricted epitopes of the Epstein-Barr virus (EBV) nuclear antigen (EBNA) 4 (designated IVT and AVF, respectively). Molecular modeling and alanine scanning mutagenesis of the IVT and AVF peptides demonstrated that solvent exposed peptide side chains affect CTL recognition as well as antibody binding suggesting that allospecific antibodies recognize the complexes in a fashion similar to T cell receptors. Class I molecules are important for target recognition by T cells as well as natural killer (NK) cells. Overexpression of the c-myc oncogene increased the sensitivity of EBV transformed Iymphoblastoid cell lines (LCLs) to NK lysis. The reactivity with allospecific antibodies was significantly reduced suggesting that a different set of antigenic peptides may occupy the class I groove, resulting in inability to deliver a negative regulatory signal to NK cells. Defective presentation of endogenously expressed EBNA4 was demonstrated in A11 positive Burkitt's Iymphoma (BL) lines. The defect was not overcome by cytosolic expression of the preformed epitope. The tumor cell expressed low levels of the transporter associated with antigen processing (TAP) and behaved poorly in a streptolysin-O mediated peptide translocation assay but presentation was not restored by upregulation TAP activity following treatment with IFN-y. Efficient maturation of class I molecules to Endo H resistant species was demonstrated in pulse-chase experiments. The results localize the defect to functions downstream of the generation of antigenic peptides but upstream of TAP-dependent peptide transport and class I assembly and maturation.
|
|
