@article{4140, abstract = {Wnt11 is a key signal, determining cell polarization and migration during vertebrate gastrulation. It is known that Wnt11 functionally interacts with several signaling components, the homologues of which control planar cell polarity in Drosophila melanogaster. Although in D. melanogaster these components are thought to polarize cells by asymmetrically localizing at the plasma membrane, it is not yet clear whether their subcellular localization plays a similarly important role in vertebrates. We show that in zebrafish embryonic cells, Wnt11 locally functions at the plasma membrane by accumulating its receptor, Frizzled 7, on adjacent sites of cell contacts. Wnt11-induced Frizzled 7 accumulations recruit the intracellular Wnt signaling mediator Dishevelled, as well as Wnt11 itself, and locally increase cell contact persistence. This increase in cell contact persistence is mediated by the local interaction of Wnt11, Frizzled 7, and the atypical cadherin Flamingo at the plasma membrane, and it does not require the activity of further downstream effectors of Wnt11 signaling, such as RhoA and Rok2. We propose that Wnt11, by interacting with Frizzled 7 and Flamingo, modulates local cell contact persistence to coordinate cell movements during gastrulation.}, author = {Witzel, Sabine and Zimyanin, Vitaly and Carreira Barbosa, Filipa and Tada, Masazumi and Heisenberg, Carl-Philipp J}, journal = {Journal of Cell Biology}, number = {5}, pages = {791 -- 802}, publisher = {Rockefeller University Press}, title = {{Wnt11 controls cell contact persistence by local accumulation of Frizzled 7 at the plasma membrane}}, doi = {10.1083/jcb.200606017}, volume = {175}, year = {2006}, } @article{4145, abstract = {The detection of microRNAs (miRNAs) at single-cell resolution is important for studying the role of these posttranscriptional regulators. Here, we use a dual-fluorescent green fluorescent protein (GFP)-reporter/monomeric red fluorescent protein (mRFP)-sensor (DFRS) plasmid, injected into zebrafish blastomeres or electroporated into defined tissues of mouse embryos in utero or ex utero, to monitor the dynamics of specific miRNAs in individual live cells. This approach reveals, for example, that in the developing mouse central nervous system,, miR-124a is expressed not only in postmitotic neurons but also in neuronal progenitor cells. Collectively, our results demonstrate that acute administration of DFRS plasmids.offers an alternative to previous in situ hybridization and transgenic approaches and allows the monitoring of miRNA appearance and disappearance in defined cell lineages during vertebrate development.}, author = {Tonelli, Davide and Calegari, Frederico and Fei, Ji and Nomura, Tadashi and Osumi, Noriko and Heisenberg, Carl-Philipp J and Huttner, Wieland}, journal = {Biotechniques}, number = {6}, pages = {727 -- 732}, publisher = {Informa Healthcare}, title = {{Single-cell detection of microRNAs in developing vertebrate embryos after acute administration of a dual-fluorescence reporter/sensor plasmid}}, doi = {10.2144/000112296}, volume = {41}, year = {2006}, } @article{4173, abstract = {Background: Zebrafish (D. rerio) has become a powerful and widely used model system for the analysis of vertebrate embryogenesis and organ development. While genetic methods are readily available in zebrafish, protocols for two dimensional (2D) gel electrophoresis and proteomics have yet to be developed. Results: As a prerequisite to carry out proteomic experiments with early zebrafish embryos, we developed a method to efficiently remove the yolk from large batches of embryos. This method enabled high resolution 2D gel electrophoresis and improved Western blotting considerably. Here, we provide detailed protocols for proteomics in zebrafish from sample preparation to mass spectrometry (MS), including a comparison of databases for MS identification of zebrafish proteins. Conclusion: The provided protocols for proteomic analysis of early embryos enable research to be taken in novel directions in embryogenesis.}, author = {Link, Vinzenz and Shevchenko, Andrej and Heisenberg, Carl-Philipp J}, journal = {BMC Developmental Biology}, pages = {1 -- 9}, publisher = {BioMed Central}, title = {{Proteomics of early zebrafish embryos}}, doi = {10.1186/1471-213X-6-1}, volume = {6}, year = {2006}, } @article{4176, abstract = {During vertebrate gastrulation, a well-orchestrated series of morphogenetic changes leads to the formation of the three germ layers: the ectoderm, mesoderm and endoderm. The analysis of gene expression patterns during gastrulation has been central to the identification of genes involved in germ layer formation. However, many proteins are regulated on a translational or post-translational level and are thus undetectable by gene expression analysis. Therefore, we developed a 2D-gel-based comparative proteomic approach to target proteins involved in germ layer morphogenesis during zebrafish gastrulation. Proteomes of ectodermal and mesendodermal progenitor cells were compared and 35 significantly regulated proteins were identified by mass spectrometry, including several proteins with predicted functions in cytoskeletal organization. A comparison of our proteomic results with data obtained in an accompanying microarray-based gene expression analysis revealed no significant overlap, confirming the complementary nature of proteomics and transcriptomics. The regulation of ezrin2, which was identified based on a reduction in spot intensity in mesendodermal cells, was independently validated. Furthermore, we show that ezrin2 is activated by phosphorylation in mesendodermal cells and is required for proper germ layer morphogenesis. We demonstrate the feasibility of proteomics in zebrafish, concluding that proteomics is a valuable tool for analysis of early development.}, author = {Link, Vinzenz and Carvalho, Lara and Castanon, Irinka and Stockinger, Petra and Shevchenko, Andrej and Heisenberg, Carl-Philipp J}, journal = {Journal of Cell Science}, number = {10}, pages = {2073 -- 2083}, publisher = {Company of Biologists}, title = {{Identification of regulators of germ layer morphogenesis using proteomics in zebrafish}}, doi = {10.1242/jcs.02928}, volume = {119}, year = {2006}, } @article{4178, abstract = {Detailed reconstruction of the spatiotemporal history of embryonic cells is key to understanding tissue formation processes but is often complicated by the large number of cells involved, particularly so in vertebrates. Through a combination of high-resolution time-lapse lineage tracing and antibody staining, we have analyzed the movement of mesencephalic and metencephalic cell populations in the early zebrafish embryo. To facilitate the analysis of our cell tracking data, we have created TracePilot, a software tool that allows interactive manipulation and visualization of tracking data. We demonstrate its utility by showing novel visualizations of cell movement in the developing zebrafish brain. TracePilot (http://www.mpi-cbg.de/tracepilot) is Java-based, available free of charge, and has a program structure that allows the incorporation of additional analysis tools.}, author = {Langenberg, Tobias and Dracz, Tadeusz and Oates, Andrew and Heisenberg, Carl-Philipp J and Brand, Michael}, journal = {Developmental Dynamics}, number = {4}, pages = {928 -- 933}, publisher = {Wiley-Blackwell}, title = {{Analysis and visualization of cell movement in the developing zebrafish brain}}, doi = {10.1002/dvdy.20692}, volume = {235}, year = {2006}, } @article{4184, abstract = {Epithelial morphogenesis depends on coordinated changes in cell shape, a process that is still poorly understood. During zebrafish epiboly and Drosophila dorsal closure, cell-shape changes at the epithelial margin are of critical importance. Here evidence is provided for a conserved mechanism of local actin and myosin 2 recruitment during theses events. It was found that during epiboly of the zebrafish embryo, the movement of the outer epithelium (enveloping layer) over the yolk cell surface involves the constriction of marginal cells. This process depends on the recruitment of actin and myosin 2 within the yolk cytoplasm along the margin of the enveloping layer. Actin and myosin 2 recruitment within the yolk cytoplasm requires the Ste20-like kinase Msn1, an orthologue of Drosophila Misshapen. Similarly, in Drosophila, actin and myosin 2 localization and cell constriction at the margin of the epidermis mediate dorsal closure and are controlled by Misshapen. Thus, this study has characterized a conserved mechanism underlying coordinated cell-shape changes during epithelial morphogenesis.}, author = {Köppen, Mathias and Fernández, Beatriz and Carvalho, Lara and Jacinto, António and Heisenberg, Carl-Philipp J}, journal = {Development}, number = {14}, pages = {2671 -- 2681}, publisher = {Company of Biologists}, title = {{Coordinated cell-shape changes control epithelial movement in zebrafish and Drosophila}}, doi = {doi: 10.1242/dev.02439}, volume = {133}, year = {2006}, } @article{4218, abstract = {The molecular and cellular mechanisms governing cell motility and directed migration in response to the chemokine SDF-1 are largely unknown. Here, we demonstrate that zebrafish primordial germ cells whose migration is guided by SDF-1 generate bleb-like protrusions that are powered by cytoplasmic flow. Protrusions are formed at sites of higher levels of free calcium where activation of myosin contraction occurs. Separation of the acto-myosin cortex from the plasma membrane at these sites is followed by a flow of cytoplasm into the forming bleb. We propose that polarized activation of the receptor CXCR4 leads to a rise in free calcium that in turn activates myosin contraction in the part of the cell responding to higher levels of the ligand SDF-1. The biased formation of new protrusions in a particular region of the cell in response to SDF-1 defines the leading edge and the direction of cell migration.}, author = {Blaser, Heiko and Reichman Fried, Michal and Castanon, Irinka and Dumstrei, Karin and Marlow, Florence and Kawakami, Koichi and Solnica Krezel, Lilianna and Heisenberg, Carl-Philipp J and Raz, Erez}, journal = {Developmental Cell}, number = {5}, pages = {613 -- 627}, publisher = {Cell Press}, title = {{Migration of zebrafish primordial germ cells: A role for myosin contraction and cytoplasmic flow}}, doi = {10.1016/j.devcel.2006.09.023}, volume = {11}, year = {2006}, } @article{4235, abstract = {The accompanying letter by H. Ortega addresses some points with respect to our previous article (de Vladar and González, 2004). He begins addressing some arguments about our interpretations of the parameters that are hand-waving rather than scientific. However, he is mostly concerned with the asymptotic behaviour of the tumour-immunity system when therapy is present. Dr. Ortega repeats calculations of our system where he either (i) reaches the same conclusions as we do or (ii) reaches different but mistaken conclusions. In any case, he intends to pose destructive critiques to our paper without providing a real contribution to the field, much less an enrichment to our model.}, author = {Vladar, Harold and González, J.}, journal = {Journal of Theoretical Biology}, number = {1}, pages = {162--163}, publisher = {Elsevier}, title = {{Dynamic response of cancer under the influence of immunological activity and therapy}}, doi = {10.1016/j.jtbi.2005.11.016}, volume = {240}, year = {2006}, } @article{4237, abstract = {The growth function of populations is central in biomathematics. The main dogma is the existence of density-dependence mechanisms, which can be modelled with distinct functional forms that depend on the size of the Population. One important class of regulatory functions is the theta-logistic, which generalizes the logistic equation. Using this model as a motivation, this paper introduces a simple dynamical reformulation that generalizes many growth functions. The reformulation consists of two equations, one for population size, and one for the growth rate. Furthermore, the model shows that although population is density-dependent, the dynamics of the growth rate does not depend either on population size, nor on the carrying capacity. Actually, the growth equation is uncoupled from the population size equation, and the model has only two parameters, a Malthusian parameter rho and a competition coefficient theta. Distinct sign combinations of these parameters reproduce not only the family of theta-logistics, but also the van Bertalanffy, Gompertz and Potential Growth equations, among other possibilities. It is also shown that, except for two critical points, there is a general size-scaling relation that includes those appearing in the most important allometric theories, including the recently proposed Metabolic Theory of Ecology. With this model, several issues of general interest are discussed such as the growth of animal population, extinctions, cell growth and allometry, and the effect of environment over a population. (c) 2005 Elsevier Ltd. All rights reserved.}, author = {de Vladar, Harold}, journal = {Journal of Theoretical Biology}, number = {2}, pages = {245 -- 256}, publisher = {Elsevier}, title = {{Density-dependence as a size-independent regulatory mechanism}}, doi = {10.1016/j.jtbi.2005.05.014}, volume = {238}, year = {2006}, } @article{4248, abstract = {In finite populations, genetic drift generates interference between selected loci, causing advantageous alleles to be found more often on different chromosomes than on the same chromosome, which reduces the rate of adaptation. This “Hill–Robertson effect” generates indirect selection to increase recombination rates. We present a new method to quantify the strength of this selection. Our model represents a new beneficial allele (A) entering a population as a single copy, while another beneficial allele (B) is sweeping at another locus. A third locus affects the recombination rate between selected loci. Using a branching process model, we calculate the probability distribution of the number of copies of A on the different genetic backgrounds, after it is established but while it is still rare. Then, we use a deterministic model to express the change in frequency of the recombination modifier, due to hitchhiking, as A goes to fixation. We show that this method can give good estimates of selection for recombination. Moreover, it shows that recombination is selected through two different effects: it increases the fixation probability of new alleles, and it accelerates selective sweeps. The relative importance of these two effects depends on the relative times of occurrence of the beneficial alleles.}, author = {Roze, Denis and Nicholas Barton}, journal = {Genetics}, number = {3}, pages = {1793 -- 1811}, publisher = {Genetics Society of America}, title = {{The Hill-Robertson effect and the evolution of recombination}}, doi = {10.1534/genetics.106.058586 }, volume = {173}, year = {2006}, } @misc{4250, abstract = {A recent analysis has shown that divergence between human and chimpanzee varies greatly across the genome. Although this is consistent with ‘hybridisation’ between the diverging human and chimp lineages, such observations can be explained more simply by the null model of allopatric speciation.}, author = {Nicholas Barton}, booktitle = {Current Biology}, number = {16}, pages = {647 -- 650}, publisher = {Cell Press}, title = {{Evolutionary Biology: How did the human species form?}}, doi = {10.1016/j.cub.2006.07.032}, volume = {16}, year = {2006}, } @article{1745, abstract = {SiGe islands grown by deposition of 10 monolayers of Ge on Si(0 0 1) at 740 °C were investigated by using a combination of selective wet chemical etching and atomic force microscopy. The used etchant, a solution consisting of ammonium hydroxide and hydrogen peroxide, shows a high selectivity of Ge over SixGe1-x and is characterized by relatively slow etching rates for Si-rich alloys. By performing successive etching experiments on the same sample area, we are able to gain a deeper insight into the lateral displacement the islands undergo during post growth annealing.}, author = {Georgios Katsaros and Rastelli, Armando and Stoffel, Mathieu and Isella, Giovanni and Von Känel, Hans and Bittner, Alexander M and Tersoff, Jerry and Denker, Ulrich and Schmidt, Oliver G and Costantini, Giovanni and Kern, Klaus}, journal = {Surface Science}, number = {12}, pages = {2608 -- 2613}, publisher = {Elsevier}, title = {{Investigating the lateral motion of SiGe islands by selective chemical etching}}, doi = {10.1016/j.susc.2006.04.027}, volume = {600}, year = {2006}, } @article{1746, abstract = {A microscopic picture for the GaAs overgrowth of self-organized InAs/GaAs(001) quantum dots is developed. Scanning tunneling microscopy measurements reveal two capping regimes: the first being characterized by a dot shrinking and a backward pyramid-to-dome shape transition. This regime is governed by fast dynamics resulting in island morphologies close to thermodynamic equilibrium. The second regime is marked by a true overgrowth and is controlled by kinetically limited surface diffusion processes. A simple model is developed to describe the observed structural changes which are rationalized in terms of energetic minimization driven by lattice mismatch and alloying.}, author = {Costantini, Giovanni and Rastelli, Armando and Manzano, Carlos and Acosta-Diaz, P and Songmuang, Rudeeson and Georgios Katsaros and Schmidt, Oliver G and Kern, Klaus}, journal = {Physical Review Letters}, number = {22}, publisher = {American Physical Society}, title = {{Interplay between thermodynamics and kinetics in the capping of InAs/GaAs (001) quantum dots}}, doi = {10.1103/PhysRevLett.96.226106}, volume = {96}, year = {2006}, } @article{1747, abstract = {We report on recent advances in the understanding of surface processes occurring during growth and post-growth annealing of strained islands which may find application as self-assembled quantum dots. We investigate the model system SiGe/Si(0 0 1) by a new approach based on "reading the footprints" which islands leave on the substrate during their growth and evolution. Such footprints consist of trenches carved in the Si substrate. We distinguish between surface footprints and footprints buried below the islands. The former allow us to discriminate islands which are in the process of growing from those which are shrinking. Islands with steep morphologies grow at the expense of smaller and shallower islands, consistent with the kinetics of anomalous coarsening. While shrinking, islands change their shape according to thermodynamic predictions. Buried footprints are investigated by removing the SiGe epilayer by means of selective wet chemical etching. Their reading shows that: (i) during post-growth annealing islands move laterally because of surface-mediated Si-Ge intermixing; (ii) a tree-ring structure of trenches is created by dislocated islands during their "cyclic" growth. This allows us to distinguish coherent from dislocated islands and to establish whether the latter are the result of island coalescence.}, author = {Rastelli, Armando and Stoffel, Mathieu and Georgios Katsaros and Tersoff, Jerry and Denker, Ulrich and Merdzhanova, Tsvetelina and Kar, Gouranga S and Costantini, Giovanni and Kern, Klaus and Von Känel, Hans and Schmidt, Oliver G}, journal = {Microelectronics Journal}, number = {12}, pages = {1471 -- 1476}, publisher = {Elsevier}, title = {{Reading the footprints of strained islands}}, doi = {10.1016/j.mejo.2006.05.029}, volume = {37}, year = {2006}, } @article{1748, abstract = {The authors apply selective wet chemical etching and atomic force microscopy to reveal the three-dimensional shape of SiGeSi (001) islands after capping with Si. Although the "self-assembled quantum dots" remain practically unaffected by capping in the temperature range of 300-450 °C, significant morphological changes take place on the Si surface. At 450 °C, the morphology of the capping layer (Si matrix) evolves toward an intriguing semifacetted structure, which we call a "ziggurat," giving the misleading impression of a stepped SiGe island shape.}, author = {Georgios Katsaros and Rastelli, Armando and Stoffel, Mathieu and Costantini, Giovanni and Schmidt, Oliver G and Kern, Klaus and Tersoff, Jerry and Müller, Elisabeth and Von Känel, Hans}, journal = {Applied Physics Letters}, number = {25}, publisher = {American Institute of Physics}, title = {{Evolution of buried semiconductor nanostructures and origin of stepped surface mounds during capping}}, doi = {10.1063/1.2405876}, volume = {89}, year = {2006}, } @article{17718, abstract = {The reionization history of the intergalactic medium at high redshift (z ≳ 6) was likely strongly shaped by several global feedback processes. Because the earliest ionizing sources formed at the locations of the rare density peaks, their spatial distribution was strongly clustered. Here we demonstrate that this clustering significantly boosts the impact of feedback processes operating at high redshift. We build a semianalytical model to include feedback and clustering simultaneously and apply this model to the suppression of star formation in minihalos due to photoionization. The model is built on the excursion-set-based formalism of Furlanetto, Zaldarriaga, and Hernquist, which incorporates the clustering of ionizing sources and which we here extend to include the suppression of star formation in minihalos. We find that clustering increases the mean H II bubble size by a factor of several, and it dramatically increases the fraction of minihalos that are suppressed by a factor of up to ~60 relative to a randomly distributed population. This enhanced suppression can significantly reduce the electron-scattering optical depth τ, as required by the 3 year data from the Wilkinson Microwave Anisotropy Probe. We argue that source clustering is likely to similarly boost the importance of a variety of other feedback mechanisms.}, author = {Kramer, Roban Hultman and Haiman, Zoltán and Oh, S. Peng}, issn = {0004-637X}, journal = {The Astrophysical Journal}, number = {2}, pages = {570--578}, publisher = {American Astronomical Society}, title = {{Feedback from clustered sources during reionization}}, doi = {10.1086/506906}, volume = {649}, year = {2006}, } @article{17727, abstract = {We report on i-band snapshot observations of 157 Sloan Digital Sky Survey (SDSS) quasars at 4-3.8 (3 sigma), assuming a break in the quasar luminosity function at M*_145=-24.5. This constraint is considerably stronger than the limit of beta>-4.63 obtained from the absence of lensing in four z>5.7 quasars. Such constraints are important for our understanding of the true space density of high-redshift quasars and the ionization state of the early universe.}, author = {Richards, Gordon T. and Haiman, Zoltán and Pindor, Bartosz and Strauss, Michael A. and Fan, Xiaohui and Eisenstein, Daniel and Schneider, Donald P. and Bahcall, Neta A. and Brinkmann, J. and Fukugita, Masataka}, issn = {0004-6256}, journal = {The Astronomical Journal}, number = {1}, pages = {49--54}, publisher = {American Astronomical Society}, title = {{A snapshot survey for gravitational lenses among z ≥ 4.0 quasars. II. Constraints on the 4.0 < z < 5.4 quasar population}}, doi = {10.1086/498063}, volume = {131}, year = {2006}, } @article{17730, abstract = {We model the spectra and surface brightness distributions for the Lyα radiation expected from protogalaxies that are caught in the early stages of their assembly. We use the results of a companion paper to characterize the radiation emerging from spherically collapsing gas clouds. We then modify these spectra to incorporate the effect of subsequent resonant scattering in the IGM. Using these models, we interpret a number of recent observations of extended Lyα blobs (LABs) at high redshift. We suggest, based on the angular size, energetics, relatively shallow surface brightness profiles, and double-peaked spectra, that several of these LABs may be associated with collapsing protogalaxies. We suggest two follow-up observations to diagnose the presence of gas infall. High-S/N spectra of LABs should reveal a preferential flattening of the surface brightness profile at the red side of the line. Complementary imaging of the blobs at redshifted Hα wavelengths should reveal the intrinsic Lyα emissivity and allow its separation from radiative transfer effects. We show that Lyα scattering by infalling gas can reproduce the observed spectrum of the Steidel et al. LAB2 as accurately as a recently proposed outflow model. Finally, we find similar evidence for infall in the spectra of pointlike Lyα emitters. The presence of scattering by the infalling gas implies that the intrinsic Lyα luminosities and derived quantities, such as the star formation rate, in these objects may have been underestimated by about an order of magnitude.}, author = {Dijkstra, Mark and Haiman, Zoltán and Spaans, Marco}, issn = {0004-637X}, journal = {The Astrophysical Journal}, number = {1}, pages = {37--47}, publisher = {American Astronomical Society}, title = {{Lyα radiation from collapsing protogalaxies. II. Observational evidence for gas infall}}, doi = {10.1086/506244}, volume = {649}, year = {2006}, } @article{17733, abstract = {We use three-dimensional hydrodynamic simulations to investigate the effects of a transient photoionizing ultraviolet (UV) flux on the collapse and cooling of pregalactic clouds. These clouds have masses in the range 10^5 -10^7 M_sun, form at high redshifts (z>18), are assumed to lie within the short-lived cosmological HII regions around the first generation of stars. In addition, we study the combined effects of this transient UV flux and a persistent Lyman-Werner (LW) background from distant sources. In the absence of a LW background, we find that a critical specific intensity of J_UV ~ 0.1 x 10^-21 ergs s^-1 cm^-2 Hz^-1 sr^-1 demarcates a transition from net negative to positive feedback for the halo population. A weaker UV flux stimulates subsequent star formation inside the fossil HII regions, by enhancing the H_2 molecule abundance. A stronger UV flux significantly delays star-formation by reducing the gas density, and increasing the cooling time, at the centers of collapsing halos. At a fixed J_UV, the sign of the feedback also depends strongly on the density of the gas at the time of UV illumination. Regardless of the whether the feedback is positive or negative, we find that once the UV flux is turned off, its impact stars to diminish after ~30% of the Hubble time. In the more realistic case when a LW background is present, with J_LW > 0.01 x 10^-21 ergs s^-1 cm^-2 Hz^-1 sr^-1, strong suppression persists down to the lowest redshift (z=18) in our simulations. Finally, we find evidence that heating and photoevaporation by the transient UV flux renders the ~10^6 M_sun halos inside fossil HII regions more vulnerable to subsequent H_2 photo-dissociation by a LW background.}, author = {Mesinger, Andrei and Bryan, Greg L. and Haiman, Zoltán}, issn = {0004-637X}, journal = {The Astrophysical Journal}, number = {2}, pages = {835--851}, publisher = {American Astronomical Society}, title = {{Ultraviolet radiative feedback on high‐redshift protogalaxies}}, doi = {10.1086/506173}, volume = {648}, year = {2006}, } @article{17742, abstract = {The primordial gas in the earliest dark matter halos, collapsing at redshifts around z=20, with masses M_halo=10^6 M_sun, and virial temperatures T_vir<10^4K, relied on the presence of molecules for cooling. Several theoretical studies have suggested that gas contraction and star-formation in these minihalos was suppressed by radiative, chemical, thermal, and dynamical feedback processes. The recent measurement by the Wilkinson Microwave Anisotropy Probe (WMAP) of the optical depth to electron scattering, tau=0.09+/-0.03, provides the first empirical evidence for this suppression. The new WMAP result is consistent with vanilla models of reionization, in which ionizing sources populate cold dark matter (CDM) halos down to a virial temperature of T_vir=10^4K. On the other hand, we show that in order to avoid overproducing the optical depth, the efficiency for the production of ionizing photons in minihalos must have been about an order of magnitude lower than expected and lower than the efficiency in large halos that can cool via atomic hydrogen (T_vir > 10^4K). This conclusion is insensitive to assumptions about the efficiency of ionizing photon production in the large halos, as long as reionization ends by z=6, as required by the spectra of bright quasars at z<6. Our conclusion is strengthened if the clumping of the ionized gas evolves with redshift, as suggested by semi-analytical predictions and three-dimensional numerical simulations.}, author = {Haiman, Zoltán and Bryan, Greg L.}, issn = {0004-637X}, journal = {The Astrophysical Journal}, number = {1}, pages = {7--11}, publisher = {American Astronomical Society}, title = {{Was star formation suppressed in high‐redshift minihalos?}}, doi = {10.1086/506580}, volume = {650}, year = {2006}, }