NEWS AND VIEWS an inversion to determine the variation of Observations of solar internal rotation elusive, for three reasons - the H-Y rotation in the core. However, the authors will soon be extended by the results from response provided a neat illustration have carried out a least-squares fit to the the Global Oscillation Network Group of MHC-restricted antigen recognition data of various simple parametrizations of (GONG) project and the helioseismic and thymic selection; the first MHC­ rotation, in most cases representing angu­ instruments on the Solar and Heliospheric restricted T-cell clone to be isolated was lar velocity as being constant over a few Observatory (SOHO) satellite to be H-Y-specific (and specific for MHC discrete shells and constraining rotation in launched late this year. Furthermore, con­ alloantigens); and, finally, the first mice the outer parts of the Sun to fit the results tinuation of the BiSON observations reported to be transgenic for the such as those shown in the figure. The val­ through at least one solar cycle, to test for T-cell receptor expressed H-Y-specific ues for the angular velocity depend on the the possible time-dependence of rotation, receptors. assumed extent of the shells; but in all would be extremely valuable. The overall The identification by Scott et a/. 1 and cases the results show regions rotating at outcome may well be a significant change Wang et a/.3 of the Smcy gene as the well below the surface rate, confirming the in our understanding of moderate-mass originator of H-Y peptides meets all initial impression (the results in the figure stars. 0 expectations that could be derived from show a similar tendency, albeit with con­ earlier studies of H-Y-specific immune siderable uncertainty). Jorgen Christensen-Dalsgaard is at the responses: the Smcy gene is ubiquitously The physical origin of this behaviour is Theoretical Astrophysics Center, Danish expressed in males onl/ and the male­ unclear. Elsworth et al. point out that be­ National Research Foundation, and Institute specific peptides are encoded in regions of cause the minimum energy state is one of of Physics and Astronomy, University of the Smcy genes that differ in their uniform rotation, the slowly rotating in­ Aarhus, DK-8000 Aarhus C, Denmark. sequence from the Smc.x gene12, which is terior might be a transient state, possibly homologous to Smcy but located on the X changing with solar cycle, or it might be 1. Hartmann. L. W. & Noyes. R. W. A. Rev. Astr. Astrophys. chromosome and ubiquitously expressed 25, 271-301 (1987). caused by stresses resulting from material 2. Elsworth, Y. et al. Nature 376. 669-672 (1995). in both females and males. This explains motion in the core or from magnetic fields. 3. Duvall. T. L. Jr et al. Nature 310. 22-25 (1984). why the XX female can strike against an These possibilities will undoubtedly lead 4. Loudagh, S. et al. Astr. Astrophys. 275, L25-L28 (1993). XY male, but the male cannot recipro­ 5. Tomczyk, S., Schou, J. & Thompson, M. J. Astrophys. J. to extensive theoretical investigations. 448, L57-L60 (1995). cate. It is probably not a mere coincidence IMMUNOGENETICS------that both the suspected murine H-Y pep­ tide and the human peptide are encoded by Smcy, because so far this is the only Female anti-male attack ubiquitously expressed gene to have been identified on the segment of the Y chro­ Harald von Boehmer mosome that controls immunity to H-Y. Other genes identified in that region are THE immune system of females has been could be degradation products of intracel­ the zinc-finger genes ZJY-1 and ZJY-2, as known to respond to male-specific trans­ lular proteins that do not reach the cell well as the Ube1y-1 gene (for a review, see plantation (H-Y) antigens for some forty surface in their entirety. It also became ref. 2), which are exclusively expressed in years, but the gene that encodes them has apparent that H-Y-specific immune the testes. proved elusive. Now, on page 695 of this responses could be generated in some The tracing of H-Y peptides back to the issue, Scott et al. 1 report that the Smcy mouse strains but not others, depending Smcy gene at last satisfactorily demystifies (for selected mouse eDNA on Y chromo­ on whether or not these expressed 'per­ the H-Y-specific transplantation reaction some )2 gene is the origin of H-Y antigen, missive' MHC moleculcs9•10 that could which, in spite of its clinical relevance, a result that was achieved through cosmid present H-Y peptides. This fact, together represents a biologically irrelevant conse­ transfection and sequence analysis. Their with the notion that H-Y antigens are quence of the ubiquitous expression of a conclusions are verified in an independent expressed on many different target cells, gene whose location on the Y chromo­ study by Wang et a/. 3, whose sequence of suggested that there could only be a limit­ some has been conserved over a hundred peptides isolated from class I molecules of ed variety of ubiquitously expressed, million years2. What does remain a mys­ the major histocompatibility complex male-specific peptides. tery, however, is the function of the Smcy (MHC) on the surface of cells from Interestingly, the cytolytic response was gene during very early expression in human males shows that they were not only controlled by permissive class I embryogenesis and later on in a variety of derived from the human homologue of but also by permissive class II MHC tissues including the testes. Given the effi­ Smcy. genes, and it was found that H-Y-specific ciency of transgenesis and gene targeting H-Y antigens were identified as a result class-II-MHC-restricted T-helper cells and in the mouse, this should not remain a of the rejection of male skin grafts by H-Y-specific class-I-restricted cytolytic T mystery for long. 0 female mice from the same inbred mouse cells cooperated in vivo to bring about 11 strain4 • It was argued that genes on the Y an effective immune response • In fact, Harald von Boehmer is at the Basel Insti• chromosome control expression of H-Y H-Y-specific helper and cytolytic T-cell tute for Immunology, Grenzacherstrasse antigens5 and that male-specific surface clones were isolated and used as tools to 487, CH-4005 Basel, Switzerland, and at antigens could have a role in formation of detect the surface expression of H-Y pep­ lnstitut Necker, INSERM Unite 373, rue de the testes6, an intriguing idea that fell tides. It is curious that the origin of male­ Vaugirard 156, F-75730 Paris Cedex 15, down when it was found that mice lacking specific peptides should have remained so France. H-Y antigens still developed testes7• Of course in the early days of H-Y­ 1. Scott. D. M. et al. Nature 376. 695-698 (1995). 7. Burgoyne, P. S., Levy, E. R. & Mclaren. A. Nature 320. 2. Agulnik, A. 1., Mrtchell, M. J.. Lerner, J. L., Woods, 170-172 (1986). specific immunity, the transport of intra­ D. R. & Bishop, C. E. Hum. molec. Genet. 3, 873-878 8. Gordon, R. D .• Simpson, E. & Samelson. L. J. exp. Med. cellular peptides by MHC molecules to (1994). 142, 1108-1120 (1975). the cell surface was unheard of. The fact 3. Wang, W. et al. Science (in the press). 9. Srmpson, E. & Gordon, R. lmmun. Rev. 35, 59-75 (1977). 4. Eichwald, E. J. & Silsmer, C. R. Transplant. Bull. 2, 10. von Boehmer. H .• Fathman. C. G. & Haas. W. Eur. J. established later that cytolytic T cells rec­ 154-155 (1955). lmmun. 7. 443-447 (1977). ognize H-Y antigens in the context of 5. Gasser, D. L. & Srlvers, W. K. Adv. lmmun. 15, 215-24 7 11. von Boehmer. H. & Haas. W. J. exp. Med. 150. (1972). 1134--1142 (1979). MHC moleculesH was then consistent with 6. Wachtel. S., Ohno, S., Koo. G. C. & Boyse, E. A. Nature 12. Agulnik, A. I. eta/. Hum. molec. Genet. 3, 879-884 the suggestion that male-specific peptides 257, 235--236 (1975). (1994). 642 NATURE · VOL 376 · 24 AUGUST 1995