A recently quenched galaxy 700 million years after the Big Bang.

Local and low-redshift (z < 3) galaxies are known to broadly follow a bimodal distribution: actively star-forming galaxies with relatively stable star-formation rates and passive systems. These two populations are connected by galaxies in relatively slow transition. By contrast, theory predicts that star formation was stochastic at early cosmic times and in low-mass systems1-4. These galaxies transitioned rapidly between starburst episodes and phases of suppressed star formation, potentially even causing temporary quiescence-so-called mini-quenching events5,6. However, the regime of star-formation burstiness is observationally highly unconstrained. Directly observing mini-quenched galaxies in the primordial Universe is therefore of utmost importance to constrain models of galaxy formation and transformation7,8. Early quenched galaxies have been identified out to redshift z < 5 (refs. 9-12) and these are all found to be massive (M⋆ > 1010 M⊙) and relatively old. Here we report a (mini-)quenched galaxy at z = 7.3, when the Universe was only 700 Myr old. The JWST/NIRSpec spectrum is very blue (U-V = 0.16 ± 0.03 mag) but exhibits a Balmer break and no nebular emission lines. The galaxy experienced a short starburst followed by rapid quenching; its stellar mass (4-6 × 108 M⊙) falls in a range that is sensitive to various feedback mechanisms, which can result in perhaps only temporary quenching.

A small and vigorous black hole in the early Universe.

Several theories have been proposed to describe the formation of black hole seeds in the early Universe and to explain the emergence of very massive black holes observed in the first thousand million years after the Big Bang1-3. Models consider different seeding and accretion scenarios4-7, which require the detection and characterization of black holes in the first few hundred million years after the Big Bang to be validated. Here we present an extensive analysis of the JWST-NIRSpec spectrum of GN-z11, an exceptionally luminous galaxy at z = 10.6, revealing the detection of the [NeIV]λ2423 and CII*λ1335 transitions (typical of active galactic nuclei), as well as semi-forbidden nebular lines tracing gas densities higher than 109 cm-3, typical of the broad line region of active galactic nuclei. These spectral features indicate that GN-z11 hosts an accreting black hole. The spectrum also reveals a deep and blueshifted CIVλ1549 absorption trough, tracing an outflow with velocity 800-1,000 km s-1, probably driven by the active galactic nucleus. Assuming local virial relations, we derive a black hole mass of log ( M BH / M ⊙ ) = 6.2 ± 0.3 , accreting at about five times the Eddington rate. These properties are consistent with both heavy seeds scenarios and scenarios considering intermediate and light seeds experiencing episodic super-Eddington phases. Our finding explains the high luminosity of GN-z11 and can also provide an explanation for its exceptionally high nitrogen abundance.

Carbonaceous dust grains seen in the first billion years of cosmic time.

Large dust reservoirs (up to approximately 108 M⊙) have been detected1-3 in galaxies out to redshift z ≃ 8, when the age of the Universe was only about 600 Myr. Generating substantial amounts of dust within such a short timescale has proven challenging for theories of dust formation4,5 and has prompted the revision of the modelling of potential sites of dust production6-8, such as the atmospheres of asymptotic giant branch stars in low-metallicity environments, supernova ejecta and the accelerated growth of grains in the interstellar medium. However, degeneracies between different evolutionary pathways remain when the total dust mass of galaxies is the only available observable. Here we report observations of the 2,175 Å dust attenuation feature, which is well known in the Milky Way and galaxies at z ≲ 3 (refs. 9-11), in the near-infrared spectra of galaxies up to z ≃ 7, corresponding to the first billion years of cosmic time. The relatively short timescale implied for the formation of carbonaceous grains giving rise to this feature12 suggests a rapid production process, possibly in Wolf-Rayet stars or supernova ejecta.

Linkage analysis in keratoconus: replication of locus 5q21.2 and identification of other suggestive Loci.

PURPOSE: Keratoconus (KC) is the most common indication for corneal transplantation in the Western world, with etiologic mechanisms still poorly understood. The disease prevalence in the general population is approximately 1:2000, and familial aggregation, together with increased familial risk, suggests important genetic influences on its pathogenesis. To date, several loci for familial keratoconus have been described, without the identification of any responsible gene in the respective mapped intervals. The aim of this study was to identify causative/susceptibility genes for keratoconus. METHODS: A total of 133 individuals (77 affected and 59 unaffected) of 25 families from southern Italy were genotyped using microsatellite markers and included in a genome-wide scan. Nonparametric and parametric analysis using an affected-only strategy were calculated by using genetic algorithm software. RESULTS: The chromosomal regions 5q32-q33, 5q21.2, 14q11.2, 15q2.32 exhibited the strongest evidence of linkage by nonparametric analysis (NPL = 3.22, 2.73, 2.62, and 2.32, respectively). The regions 5q32-q33 and 14q11.2 were also supported by multipoint parametric analysis, for which heterogeneity LOD (HLOD) scores of 2.45 (alpha = 0.54) and 2.09 (alpha = 0.46), respectively, were obtained under an affected-only dominant model. CONCLUSIONS: This study represents the first KC linkage replication study on the chromosomal region 5q21.2 and reports evidence of suggestive linkage in several regions for which suggestive or significant linkage has been previously detected in different populations.

Twenty-four novel mutations identified in a cohort of 85 patients by direct sequencing of the SLC3A1 and SLC7A9 cystinuria genes.

Mutations in the SLC3A1 and SLC7A9 genes cause cystinuria (OMIM 220100), an autosomal recessive disorder of amino acid transport and reabsorption in the proximal renal tubule and in the epithelial cells of the gastrointestinal tract. In an attempt to characterize the molecular defect in the SLC3A1 and SLC7A9 genes, we analyzed a cohort of 85 unrelated subjects clinically diagnosed as affected by cystinuria on the basis of stone formation, prevalently of Italian and Greek origin. Analysis of all coding region and exon-intron junctions of the SLC3A1 and SLC7A9 genes by using direct sequencing method allowed us to identify 62 different mutations in 83 out of 85 patients accounting for 90.5% of all affected chromosomes. Twenty-four out of 62 are novel mutations, 9 in SLC3A1 and 15 in SLC7A9. In conclusion, this report expands the spectrum of SLC3A1 and SLC7A9 mutations and confirms the heterogeneity of this disorder.

Genetic heterogeneity in Italian families with IgA nephropathy: suggestive linkage for two novel IgA nephropathy loci.

IgA nephropathy (IgAN) is the most common glomerulonephritis worldwide, but its etiologic mechanisms are still poorly understood. Different prevalences among ethnic groups and familial aggregation, together with an increased familial risk, suggest important genetic influences on its pathogenesis. A locus for familial IgAN, called "IGAN1," on chromosome 6q22-23 has been described, without the identification of any responsible gene. The partners of the European IgAN Consortium organized a second genomewide scan in 22 new informative Italian multiplex families. A total of 186 subjects (59 affected and 127 unaffected) were genotyped and were included in a two-stage genomewide linkage analysis. The regions 4q26-31 and 17q12-22 exhibited the strongest evidence of linkage by nonparametric analysis (best P=.0025 and .0045, respectively). These localizations were also supported by multipoint parametric analysis, in which peak LOD scores of 1.83 ( alpha =0.50) and 2.56 ( alpha =0.65) were obtained using the affected-only dominant model, and by allowance for the presence of genetic heterogeneity. Our results provide further evidence for genetic heterogeneity among families with IgAN. Evidence of linkage to multiple chromosomal regions is consistent with both an oligo/polygenic and a multiple-susceptibility-gene model for familial IgAN, with small or moderate effects in determining the pathological phenotype. Although we identified new candidate regions, replication studies are required to confirm the genetic contribution to familial IgAN.