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The known βCephei star HD 180 642 was observed by the CoRoT satellite in 2007. From the very high-precision light curve, its pulsation frequency spectrum could be derived for the first time (Degroote and collaborators). In this paper, we obtain additional constraints for forthcoming asteroseismic modeling of the target. Our results are based on both extensive ground-based multicolour photometry and high-resolution spectroscopy. We determine $T_{\rm eff} = 24\,500\pm 1000$K and $\log g = 3.45\pm 0.15$dex from spectroscopy. The derived chemical abundances are consistent with those for B stars in the solar neighbourhood, except for a mild nitrogen excess. A metallicity $Z =$$0.0099\pm 0.0016$is obtained. Three modes are detected in photometry. The degree $\ell$is unambiguously identified for two of them: $\ell = 0$and $\ell = 3$for the frequencies 5.48694 d-1and 0.30818 d-1, respectively. The radial mode is non-linear and highly dominant with an amplitude in the U-filter about 15 times larger than the strongest of the other modes. For the third frequency of 7.36673 d-1found in photometry, two possibilities remain: $\ell = 0$or 3. In the radial velocities, the dominant radial mode presents a so-called stillstand but no clear evidence of the existence of shocks is observed. Four low-amplitude modes are found in spectroscopy and one of them, with frequency 8.4079 d-1, is identified as $(\ell,m)=(3,2)$. Based on this mode identification, we finally deduce an equatorial rotational velocity of $38\pm 15$km s-1.

Context. We search for new variable B-type pulsators in the CoRoT data assembled primarily for planet detection, as part of CoRoT's additional programme.

Context. γDor stars are excellent targets for asteroseismology since the gravity modes present in these stars probe the deep stellar interiors. Mode identification will improve the knowledge of these stars considerably.

Context. θCarinae belongs to a group of peculiar early-type stars (OBN) with enhanced nitrogen and carbon deficiency. It is also known as a binary system, but it is not clear yet whether the chemical anomalies can be explained by mass transfer between the two components. On the basis of the previously reported spectral variability of a few metal lines it may be expected that θCar possesses a weak magnetic field.

Context.The γDoradus stars are a recent class of variable main sequence F-type stars located on the red edge of the Cepheid instability strip. They pulsate in gravity modes, and this makes them particularly interesting for detailed asteroseismic analysis, which can provide fundamental knowledge of properties near the convective cores of intermediate-mass main sequence stars.

Context.In the H-R diagram, the intersection of the main sequence and the classical Cepheid instability strip corresponds to a domain where a rich variety of atmospheric phenomena are at play (including pulsation, radiative diffusion, convection). Main-sequence A-type stars are among the best candidates to study the complex interplay between these various phenomena.

Aims.We obtained the first long, homogenous time-series of V2104 Cyg, consisting of 679 datapoints, with the $uvby\beta$photometers of the Sierra Nevada and San Pedro Mártir Observatories. Our aim was to detect and subsequently interpret the intrinsic frequencies of this previously unstudied variable star, which turned out to be a Be star. We evaluate its place among the variable B stars on the upper Main Sequence. To obtain additional information on physical parameters we collected a few spectra with the Elodieand FIESinstruments.

Aims.In order to better model massive B-type stars, we need to understand the physical processes taking place in slowly pulsating B (SPB) stars, chemically peculiar Bp stars, and non-pulsating normal B stars co-existing in the same part of the H-R diagram.

Aims.We selected a large sample of O-B stars that were considered as (candidate) slowly pulsating B, βCep, and Maia stars after the analysis of their hipparcosdata. We analysed our new seven passband genevadata collected for these stars during the first three years of scientific operations of the mercatortelescope. We performed a frequency analysis for 28 targets with more than 50 high-quality measurements to improve their variability classification. For the pulsating stars, we tried both to identify the modes and to search for rotationally split modes.

Context.HD 23642 is the only known eclipsing binary in the Pleiades, and therefore of importance in determining the distance to this cluster.

We present the results of a spectroscopic study of 37 southern (candidate) γDoradus stars based on échelle spectra. The observed spectra were cross-correlated with the standard template spectrum of an F0-type star for easier detection of binary and intrinsic variations. We identified 15 objects as spectroscopic binaries, including 7 new ones, while another 3 objects are binary suspects. At least 12 objects show composite spectra. We could determine the orbital parameters for 9 binaries, of which 4 turned out to be ellipsoidal variables. For 6 binaries, we estimated the expected time-base of the orbital variations. Clear profile variations were observed for 17 objects, pointing towards stellar pulsation. For 8 of them, we have evidence that the main spectroscopic and photometric periods coincide. Our results, in combination with prior knowledge from the literature, lead to the classification of 10 objects as new bona fide γDoradus stars, 1 object as a new bona fide δScuti star, and 8 objects as constant stars. Finally, we determined the projected rotational velocity by two independent methods. The resulting $v \sin i$values range from 3 to 135 $\rm{km~s^{-1}}$. For the bona fide γDoradus stars, the majority has $v \sin i$below 60 $\rm{km~s^{-1}}$.

Aims.We made a seismic study of the young massive $\beta\,$Cephei star HD 203664 with the goal of constraining its interior structure.Methods.Our study is based on a time series of 328 new Geneva 7-colour photometric data of the star spread over 496.8 days.Results.The data confirm the frequency of the dominant mode of the star, which we refined to $f_1=6.02885\,$c d-1. The mode has a large amplitude of 37 mmag in Vand is unambiguously identified as a dipole mode ($\ell=2$) from its amplitude ratios and non-adiabatic computations. Besides f1, we discovered two additional new frequencies in the star with amplitudes above $4\sigma$: $f_2=6.82902\,$c d-1and $f_3=4.81543\,$c d-1, or one of their daily aliases. The amplitudes of these two modes are only between 3 and 4 mmag, which explains why they were not detected before. Their amplitude ratios are too uncertain for mode identification. Conclusions.We show that the observed oscillation spectrum of HD 203664 is compatible with standard stellar models but that we have insufficient information for asteroseismic inferences. Among the large-amplitude $\beta\,$Cephei stars, HD 203664 stands out as the only one rotating at a significant fraction of its critical rotation velocity (~$ 40\%$).

A detailed analysis of a large collection of electronic spectra from three observatories, together with radial velocities published earlier, were used to derive a new ephemeris and improved orbital elements for the εPer binary. Observations covering a time interval of about 37 000 days (101.3 years) can be reconciled with a constant orbital period of 14$\fd$06916$\,\pm\,$0$\fd$00004. The high orbital eccentricity of 0.555$\,\pm\,$0.009 was also confirmed. New spectral observations confirm that there is a periodic variation of the systemic velocity. Together with new evidence from astrometric observations (also analyzed here), they confirm the existence of a third body in the system with an orbital period of about 9600 days (26.3 years), rather than 4156 days, as reported earlier. Application of the disentangling technique to the Hαspectra with good $S/N$ratios did not allow detection of spectral lines of either the secondary or tertiary components. For plausible inclinations between 30° and 90°, the observed mass function implies a mass of the secondary $M_2=0.85{-}1.77$$M_{\odot}$, if a primary mass is adopted of 13.5$\,\pm\,$2.0 $M_{\odot}$. Attempts to detect the third body via interferometric observations should continue in spite of this first negative result.

Multi-site and multi-year differential photometry of the triple star DG Leo reveals a complex frequency spectrum that can be modelled as the combination of at least three δScuti type frequencies in the range 11.5–13 c/d (with semi-amplitudes of 2–7 mmag) and a superimposed slow variability of larger amplitude. The period of the slow variation fits very well with half the orbital period of the inner spectroscopic binary indicating the presence of ellipsoidal variations caused by the tidally deformed components in a close configuration. These findings, together with the results of a recent spectroscopic analysis (showing that the system consists of a pair of mild Am stars and one A-type component of normal solar composition), infer that DG Leo is an extremely interesting asteroseismic target. Identification of which component(s) of this multiple system is (or are) pulsating and determination of the excited pulsation modes will both contribute to a much better understanding of the non-trivial link between multiplicity, chemical composition, rotation, and pulsation in the lower part of the classical Cepheid instability strip.

We present the results of the mode identification for a sample of 7 bright southern slowly pulsating B stars showing one pulsation frequency in the $\lambda\lambda$413 nm Si II profiles. We combined the results from (1) the method of photometric amplitudes; (2) the moment method; and (3) the amplitude and phase variation across the profile to search for the $\ell$and mvalues of the modes best fitting the data. It is the first time that the applicability of these techniques is tested to a sample of main-sequence g-mode pulsators. Combining the moment method with the amplitude and phase variations across the observed line profile gives an improvement in spectroscopic identification of low degree $\ell$g-mode pulsations. Using the variations of the higher order even moments ${\langle v^4\rangle}$and ${\langle v^6\rangle}$of the moment method solutions can also help. For HD 181558, HD 24587, HD 140873 and HD 177863, the photometric and spectroscopic results are compatible and point towards $(\ell,m)$= (1, +1) sectoral modes. For HD 215573, HD 53921 and HD 92287, the results are inconclusive. Our proposed methodology for mode identification is also applicable to γDoradus stars.

We present the first results of a 2-year high-resolution spectroscopy campaign of 59 candidate γDoradus stars which were mainly discovered from the HIPPARCOS astrometric mission. More than 60% of the stars present line profile variations which can be interpreted as due to pulsation related to γDoradus stars. For all stars we also derived the projected rotation velocity (up to more than 200 km s-1). The amplitude ratios $2K/\Delta m$for the main HIPPARCOS frequency are in the range 35-96 km s-1mag-1. About 50% of the candidates are possible members of binary systems, with 20 stars being confirmed γDoradus. At least 6 stars present composite spectra, and in all but one case (for which only one spectrum could be obtained), the narrow component shows line profile variations, pointing towards an uncomfortable situation if this narrow component originates from a shell surrounding the star. This paper is the first of a series concerning mode identification using both photometric and spectroscopic methods for the confirmed γDoradus stars of the present sample.

We gathered long-term multicolour Geneva $UB_1BB_2V_1VG$photometric and high-resolution ($R=40\,000$) spectroscopic data of the two $\gamma\,$Doradus stars HD 12901 and HD 48501. The photometry reveals three frequencies for each of the two stars: $f_1=1.21563$c d-1, $f_2=1.39594$c d-1and $f_3=2.18636$c d-1for HD 12901 and $f_1=1.09408$c d-1, $f_2=1.29054$c d-1and $f_3=1.19924$c d-1for HD 48501. The photometric amplitude is each time largest in the Geneva B1filter and the variations in all the different filters are perfectly in phase within the measurement errors. Mode identification points out that the six modes are all $\ell=1$modes and that the non-adiabatic temperature variations are extremely small, in contradiction to current theoretical predictions. Our spectra show that all the observed frequencies are intrinsic to the stars and cannot be due to binarity. We detect clear line-profile variations at low amplitude (${<}1\,$km s-1) due to the oscillations of both targets. The estimated $v\sin\,i$from the spectra are ${\sim}53\,$km s-1for HD 12901 and ${\sim}29\,$km s-1for HD 48501. It is at present unclear if the triplet-like structure for HD 48501 is the consequence of rotational splitting or of the large separation expected for high-order gravity modes in the asymptotic regime.

We present ground-based multi-colour Geneva photometry and high-resolution spectra of four variable B-type stars: HD 105382, HD 131120, HD 138769 and HD 55522. All sets of data reveal monoperiodic stars. A comparison of moment variations of two spectral lines, one silicon line and one helium line, allows us to exclude the pulsation model as being the cause of the observed variability of the four stars. We therefore delete the four stars from the list of candidate slowly pulsating B stars. We attribute the line-profile variations to non-homogeneous distributions of elements on the stellar surface and we derive abundance maps for both elements on the stellar surface by means of the Doppler Imaging technique. We confirm HD 131120 to be a He-weak star and we classify HD 105382, HD 138769 as new He-weak stars. HD 55522 has the solar helium abundance but the mean abundance value of He varies by 0.8 dex during the stellar rotation. For HD 131120 and HD 105382, helium is enhanced in regions of the stellar surface where silicon is depleted and depleted in regions where silicon is enhanced.

We present an improved version of the method of photometric mode identification of Heynderickx et al. ([CITE]). Our new version is based on the inclusion of precise non-adiabatic eigenfunctions determined in the outer stellar atmosphere according to the formalism recently proposed by Dupret et al. ([CITE]). Our improved photometric mode identification technique is therefore no longer dependent on ad hoc parameters for the non-adiabatic effects. It contains the complete physical conditions of the outer atmosphere of the star, provided that rotation does not play a key role. We apply our method to the two slowly pulsating B stars HD 74560 and HD 138764 and to the ßCephei star EN (16) Lac. Besides identifying the degree $\ell$of the pulsating stars, our method is also a tool for improving the knowledge of stellar interiors and atmospheres, by imposing constraints on parameters such as the metallicity and the mixing-length parameter a(a procedure we label non-adiabatic asteroseismology).

We present the results of detailed frequency analyses of a sample of thirteen confirmed slowly pulsating B stars. Our analysis is based on a combination of elaborate photometric and spectroscopic data-sets. The original sample consists of a mixture of five confirmed slowly pulsating B stars and twelve candidate slowly pulsating B stars discovered thanks to the photometric measurements of the HIPPARCOS satellite. HD 55522 and HD 131120 turn out to be chemically peculiar stars. HD 169978 and HD 69144 are two ellipsoidal variables for which no intrinsic variability is found. At least nine of the thirteen studied slowly pulsating B stars are multi-periodic. For HD 74195, HD 85953, HD 123515 and HD 215573, the observed frequency spacings suggest that we are dealing with frequency multiplets. For the apparent mono-periodic binary HD 24587, it is not clear if the observed variations are induced by stellar pulsation and/or by rotation modulation. We highlight the statistical character of the observed pulsational properties of our sample.

We present ground-based multi-colour Geneva photometry and high-resolution spectra of the variable B-type star HD 131120. All sets of data reveal a monoperiodic star with a period of 1.569 days. We compare the variability of the star with a non-radial g-mode pulsation model and with a rotational modulation model. The latter model appears to be the best explanation for the observed line-profile variations of the star. Moreover, contrary to the pulsational model, it is able to reproduce the behaviour of the first three moments of the Si and He lines as well as the large variability of their equivalent width. We therefore remove the star from the list of new Slowly Pulsating B stars found from Hipparcos data.

A one-year follow-up campaign of high-resolution, high-signal-to-noise spectroscopy for 10 candidate slowly pulsating B stars, which were discovered from the HIPPARCOS astrometric mission, shows that all stars exhibit line-profile variability. From our data, and from the HIPPARCOS photometry, we conclude that all but one of the targets provide evidence of multiperiodicity, with periods of the order of days, confirming their pulsational nature. Thus they are confirmed slowly pulsating B stars. We summarize the pulsation periods and Q-values and select the most interesting targets for very-long-term follow-up observations with the goal of performing asteroseismology.

We present a total time series of high signal-to-noise, high-resolution spectra of the SiIII $\lambda 4552.6$, $\lambda 4567.8$and $\lambda 4574.8$Ålines of the fast-rotating, spectroscopic binary and βCephei star κScorpii. Among this data set is a sample of 422 spectra of intensive monitoring during eight subsequent nights in July 1997. We find variability of the line profiles on two time-scales: a variation of several months as a result of the orbital motion and rapid variations of a few hours, which are explained in terms of non-radial pulsation modes. From the total dataset, covering a time span of 9 years, we derive for the first time the orbital parameters of κScorpii and find an orbital period of 195 days. The complex patterns on the grayscale representations of the residual SiIII $\lambda 4552.6$Åprofiles with respect to the average profile point towards more than one (non-axisymmetric) pulsation mode. A frequency analysis of the three normalised velocity moments confirms the main period of 4.80 hours and the second period of 4.93 hours, which were previously derived from photometric data. We attempt an identification of the pulsation modes by means of the moment method and line-profile fitting and find that κScorpii pulsates in a main prograde sectoral mode of degree 1 or 2 and in an additional tesseral mode for which $l = 5$, $m = 1$are the most likely wavenumbers. In the variations of the line profiles we find indications for the presence of additional pulsation modes.

We present ground-based multi-colour Geneva photometry and high-resolution high S/N spectra of the variable B-type star HD 105382. We provide evidence that this star is not a Be star, as indicated in the literature. The monoperiodic variability found in the Hipparcos data is confirmed in our ground-based follow-up observations. All existing data give rise to the detection of the period of 1.295 days. We try to interpret the variability of the star in terms of a non-radial g-mode pulsation model and of a rotational modulation model. None of these two is able to explain the observed line-profile variations in full detail.

In this paper we present a method to assign statistical weights to radial-velocity measurements of a binary system of which one of the components is a variable star. The basic idea of the method is to separate the radial-velocity changes due to the intrinsic variability from those due to the orbital motion. This can be achieved if part of the data set consists of good coverages of the intrinsic variability cycle. These full coverages are used to estimate the variability for the nights on which only one or a few spectra were obtained. Our technique is applicable when the intrinsic variability has a period that is considerably shorter than the orbital period. Once weights have been assigned, existing methods to derive the orbital parameters can be used with better accuracy compared to the case where all data points are treated as if no intrinsic variability were present (equal weights). We illustrate our method and compare the orbital solution obtained with and without assigning weights for three pulsating stars in a binary system: βCru, εPer, and κSco.

Asteroseismology involves probing the interiors of stars and quantifying their global properties, such as radius and age, through observations of normal modes of oscillation. The technical requirements for conducting asteroseismology include ultrahigh precision measured in photometry in parts per million, as well as nearly continuous time series over weeks to years, and cadences rapid enough to sample oscillations with periods as short as a few minutes. We report on results from the first 43 days of observations, in which the unique capabilities of Keplerin providing a revolutionary advance in asteroseismology are already well in evidence. The Keplerasteroseismology program holds intrinsic importance in supporting the core planetary search program through greatly enhanced knowledge of host star properties, and extends well beyond this to rich applications in stellar astrophysics.

We present the results of the continuation of our magnetic survey with FORS 1 at the VLT of a sample of Btype stars consisting of confirmed or candidate βCephei stars and Slowly Pulsating B hereafter SPB stars, along with a small number of normal Btype stars. A weak mean longitudinal magnetic field of the order of a few hundred Gauss was detected in three βCephei stars and two stars suspected to be βCephei stars, in five SPB stars and eight stars suspected to be SPB stars. Additionally, a longitudinal magnetic field at a level larger than 3σhas been diagnosed in two normal Btype stars, the nitrogenrich early Btype star HD 52089 and in the B5 IV star HD 153716. Roughly one third of βCephei stars have detected magnetic fields: Out of 13 βCephei stars studied to date with FORS 1, four stars possess weak magnetic fields, and out of the sample of six suspected βCephei stars two show a weak magnetic field. The fraction of magnetic SPBs and candidate SPBs is found to be higher: Roughly half of the 34 SPB stars have been found to be magnetic and among the 16 candidate SPBs eight stars possess magnetic fields. In an attempt to understand why only a fraction of pulsating stars exhibit magnetic fields, we studied the position of magnetic and nonmagnetic pulsating stars in the HR diagram. We find that their domains in the HR diagram largely overlap, and no clear picture emerges as to the possible evolution of the magnetic field across the main sequence. It is possible that stronger fields tend to be found in stars with lower pulsating frequencies and smaller pulsating amplitudes. A somewhat similar trend is found if we consider a correlation between the field strength and the vsin ivalues, i.e. stronger magnetic fields tend to be found in more slowly rotating stars © 2009 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim

Context. The influence of binarity on the late stages of stellar evolution remains an open issue.Aims. While the first binary post-AGB stars were serendipitously discovered, the distinct characteristics of their spectral energy distribution (SED) allowed us to launch a more systematic search for binaries. We selected post-AGB objects, which exhibit a broad dust excess starting either at H or?K, pointing to the presence of a gravitationally bound dusty disc in the system. We initiated an extensive multiwavelength study of those systems and here report on our radial velocity and photometric monitoring results for six stars of early F?type, which are pulsators of small amplitude.Methods. To determine the radial velocity of low signal-to-noise ratio time-series data, we constructed dedicated autocorrelation masks based on high signal-to-noise ratio spectra, used in our published chemical studies. The radial velocity variations were analysed in detail to differentiate between pulsational variability and variability caused by orbital motion. When available, the photometric monitoring data were used to complement the time series of radial velocity data and to establish the nature of the pulsation. Finally, orbital minimalisation was performed to constrain the orbital elements.Results. All of the six objects are binaries with orbital periods ranging from 120 to 1800?days. Five systems have non-circular orbits. The mass functions range from 0.004 to 0.57?M?and the companions are probably unevolved objects of (very) low initial mass. We argue that these binaries must have evolved through a phase of strong binary interaction when the primary was a cool supergiant. Although the origin of the circumstellar disc is not well understood, the disc is generally believed to have formed during this strong interaction phase. The eccentric orbits of these highly evolved objects remain poorly understood. In one object, the line-of-sight grazes the edge of the puffed-up inner rim of the disc.Conclusions. These results corroborate our earlier statement that evolved objects in binary stars create a Keplerian dusty circumbinary disc. With the measured orbits and mass functions, we conclude that the circumbinary discs seem to have a major impact on the evolution of a significant fraction of binary systems.

We present multi-colour time-series CCD photometry of the solar-age galactic open cluster M?67 (NGC?2682). About 3600?frames spread over 28?nights were obtained with the 1.5?m Russian-Turkish and 1.2?m Mercator telescopes. High-precision observations of the close binary stars AH?Cnc, EV?Cnc, ES?Cnc, the ? Scuti type systems EX?Cnc and EW?Cnc, and some long-period variables belonging to M?67 are presented. Three full multi-colour light curves of the overcontact binary AH?Cnc were obtained during three observing seasons. Likewise we gathered three light curves of EV Cnc, an EB-type binary, and two light curves of ES?Cnc, a blue straggler binary. Parts of the light change of long-term variables S1024, S1040, S1045, S1063, S1242, and S1264 are obtained. Period variation analysis of AH?Cnc, EV?Cnc, and ES?Cnc were done using all times of mid-eclipse available in the literature and those obtained in this study. In addition, we analyzed multi-colour light curves of the close binaries and also determined new frequencies for the ??Scuti systems. The physical parameters of the close binary stars were determined with simultaneous solutions of multi-colour light and radial velocity curves. Finally we determined the distance of M?67 as?857(33) pc via binary star parameters, which is consistent with an independent method from earlier studies.

It is essential for the understanding of stellar structure models of high mass stars to explain why constant stars, nonpulsating chemically peculiar hot Bp stars and pulsating stars co-exist in the slowly pulsating B stars and β Cephei instability strips. We have conducted a search for magnetic fields in the four Bp stars HD55522, HD105382, HD131120, and HD138769 which previously have been wrongly identified as slowly pulsating B stars. A recent study of these stars using the Doppler Imaging technique revealed that the elements He and Si are inhomogeneously distributed on the stellar surface, causing the periodic variability. Using FORS 1 in spectropolarimetric mode at the VLT, we have acquired circular polarisation spectra to test the presence of a magnetic field in these stars. A variable magnetic field is clearly detected in HD55522 and HD105382, but no evidence for the existence of a magnetic field was found in HD131120. The presence of a magnetic field in HD138769 is suggested by one measurement at 3σ level. We discuss the occurrence of magnetic B stars among the confirmed pulsating B stars and find strong magnetic fields of order kG and oscillations to be mutually exclusive. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Glypicans are proteins with very characteristic structures that are substituted with heparan sulfate and that are linked to the cell surface via glycosylphosphatidylinositol. The modular structure of the glypicans has been highly conserved throughout evolution. Six glypicans have been identified so far in vertebrates. Mutations in Drosophila, humans and mice reveal a role for these cell surface molecules in the control of cell growth and differentiation. Their mechanism of action is not yet clear. Most likely, glypicans activate or determine the activity ranges of morphogens and growth factors such as FGFs, BMPs, Wnts, Hhs and IGFs.

The glypicans compose a family of glycosylphosphatidylinositol-anchored heparan sulfate proteoglycans. Mutations in dally, a gene encoding a Drosophilaglypican, and in GPC3, the gene for human glypican-3, implicate glypicans in the control of cell growth and division. So far, five members of the glypican family have been identified in vertebrates. By sequencing expressed sequence tag clones and products of rapid amplifications of cDNA ends, we identified a sixth member of the glypican family. The glypican-6 mRNA encodes a protein of 555 amino acids that is most homologous to glypican-4 (identity of 63%). Expression of this protein in Namalwa cells shows a core protein of ∼60 kDa that is substituted with heparan sulfate only. GPC6,the gene encoding human glypican-6, contains nine exons. Like GPC5, the gene encoding glypican-5, GPC6maps to chromosome 13q32. Clustering of the GPC5/GPC6genes on chromosome 13q32 is strongly reminiscent of the clustering of the GPC3/GPC4genes on chromosome Xq26 and suggests GPCsarose from a series of gene and genome duplications. Based on similarities in sequence and gene organization, glypican-1, glypican-2, glypican-4, and glypican-6 appear to define a subfamily of glypicans, differing from the subfamily comprising so far glypican-3 and glypican-5. Northern blottings indicate that glypican-6 mRNA is widespread, with prominent expressions in human fetal kidney and adult ovary. In situhybridization studies localize glypican-6 to mesenchymal tissues in the developing mouse embryo. High expressions occur in smooth muscle cells lining the aorta and other major blood vessels and in mesenchymal cells of the intestine, kidney, lung, tooth, and gonad. Growth factor signaling in these tissues might in part be regulated by the presence of glypican-6 on the cell surface.

The glypicans compose a family of glycosylphosphatidylinositol-anchored heparan sulfate proteoglycans. Mutations in dally, a gene encoding a Drosophila glypican, and in GPC3, the gene for human glypican-3, implicate glypicans in the control of cell growth and division. So far, five members of the glypican family have been identified in vertebrates. By sequencing expressed sequence tag clones and products of rapid amplifications of cDNA ends, we identified a sixth member of the glypican family. The glypican-6 mRNA encodes a protein of 555 amino acids that is most homologous to glypican-4 (identity of 63%). Expression of this protein in Namalwa cells shows a core protein of approximately 60 kDa that is substituted with heparan sulfate only. GPC6, the gene encoding human glypican-6, contains nine exons. Like GPC5, the gene encoding glypican-5, GPC6 maps to chromosome 13q32. Clustering of the GPC5/GPC6 genes on chromosome 13q32 is strongly reminiscent of the clustering of the GPC3/GPC4 genes on chromosome Xq26 and suggests GPCs arose from a series of gene and genome duplications. Based on similarities in sequence and gene organization, glypican-1, glypican-2, glypican-4, and glypican-6 appear to define a subfamily of glypicans, differing from the subfamily comprising so far glypican-3 and glypican-5. Northern blottings indicate that glypican-6 mRNA is widespread, with prominent expressions in human fetal kidney and adult ovary. In situ hybridization studies localize glypican-6 to mesenchymal tissues in the developing mouse embryo. High expressions occur in smooth muscle cells lining the aorta and other major blood vessels and in mesenchymal cells of the intestine, kidney, lung, tooth, and gonad. Growth factor signaling in these tissues might in part be regulated by the presence of glypican-6 on the cell surface.

Context.The Kepler spacecraft is providing time series of photometric data with micromagnitude precision for hundreds of A-F type stars.