Imprinting fidelity in mouse iPSCs depends on sex of donor cell and medium formulation.

Reprogramming of somatic cells into induced Pluripotent Stem Cells (iPSCs) is a major leap towards personalised approaches to disease modelling and cell-replacement therapies. However, we still lack the ability to fully control the epigenetic status of iPSCs, which is a major hurdle for their downstream applications. Epigenetic fidelity can be tracked by genomic imprinting, a phenomenon dependent on DNA methylation, which is frequently perturbed in iPSCs by yet unknown reasons.

Generation and characterization of induced pluripotent stem cell line (IBBISTi004-A) from an Angelman syndrome patient carrying a class II deletion of the maternal chromosome 15q11.2-q13.

Angelman Syndrome is a rare neurodevelopmental disorder caused by several (epi)genetic alterations. The patients present strong neurological impairment due to the absence of a functional maternal UBE3A gene in neurons. Here, we generated and characterized a new induced pluripotent stem cell (iPSC) line from a female child with Angelman syndrome harbouring a class II deletion.

The glycoproteomics of hawk and caiman tears.

Background: Glycoproteins are important tear components that participate in the stability of the ocular surface. However, the glycopeptides that are present in the tears of wild animals have not yet been described. This work aimed to describe the glycoproteomic profile of roadside hawk (Rupornis magnirostris) and caiman (Caiman latirostris) tears.

The tandem repeat modules of Xist lncRNA: a swiss army knife for the control of X-chromosome inactivation.

X-inactive-specific transcript (Xist) is a long non-coding RNA (lncRNA) essential for X-chromosome inactivation (XCI) in female placental mammals. Thirty years after its discovery, it is still puzzling how this lncRNA triggers major structural and transcriptional changes leading to the stable silencing of an entire chromosome. Recently, a series of studies in mouse cells have uncovered domains of functional specialization within Xist mapping to conserved tandem repeat regions, known as Repeats A-to-F.

Generation and characterization of induced pluripotent stem cells heterozygous for the Portuguese BRCA2 founder mutation.

Women who inherit heterozygous mutations in the BRCA2 gene have an increased risk of developing cancer, mainly breast and ovarian tumors. A particular BRCA2 mutation (c.156_157insAlu) is exclusively found in families of Portuguese ancestry and is present in approximately 30% of all Portuguese families with hereditary breast and ovarian cancers.

Generation and characterization of induced pluripotent stem cells from a family carrying the BRCA1 mutation c.3612delA.

How BRCA1 germline mutations predispose to cancer remains poorly understood. Induced pluripotent stem cells (iPSCs) represent an emerging model to investigate the molecular mechanisms underlying malignant transformation in primary cells from individuals who are carriers of deleterious mutations in the BRCA1 gene. Here we report the generation and characterization of iPSC lines from a female donor harboring a germline c.

H4K20me1 and H3K27me3 are concurrently loaded onto the inactive X chromosome but dispensable for inducing gene silencing.

During X chromosome inactivation (XCI), in female placental mammals, gene silencing is initiated by the Xist long non-coding RNA. Xist accumulation at the X leads to enrichment of specific chromatin marks, including PRC2-dependent H3K27me3 and SETD8-dependent H4K20me1. However, the dynamics of this process in relation to Xist RNA accumulation remains unknown as is the involvement of H4K20me1 in initiating gene silencing.

Atypical ocular Chelonoid herpesvirus manifestations in a captive Loggerhead turtle (Caretta caretta).

A captive loggerhead turtle (Caretta caretta) of unknown sex, 3 years of age, presented with bilateral mucoid secretions, severe chemosis, conjunctival hyperemia, and globe retraction. The animal was evaluated ophthalmologically and systemically, and hematological, microbiological, and conjunctival cytological and biopsy samples were collected for complementary diagnosis. The histopathological examination showed amphophilic intranuclear inclusions associated with severe inflammatory infiltrate.

Ocular ultrasonography of sea turtles.

Background: Environmental changes contribute to the development of ophthalmic diseases in sea turtles, but information on their eye biometrics is scarce. The aim of this study was to describe ophthalmic ultrasonographic features of four different sea turtle species; Caretta caretta (Loggerhead turtle; n = 10), Chelonia mydas (Green turtle; n = 8), Eretmochelys imbricata (Hawksbill turtle; n = 8) and Lepidochelys olivacea (Olive ridley; n = 6) under human care. Corneal thickness, scleral ossicle width and thickness, anterior chamber depth, axial length of the lens, vitreous chamber depth and axial globe length were measured by B-mode sonography with a linear transducer.

Comparative Analysis of Tear Composition in Humans, Domestic Mammals, Reptiles, and Birds.

Tears are an important component of the ocular surface protection mechanism and are in close contact with the corneal epithelium and the environment. Their composition is well-known in humans; however, there are few investigations on the composition and function of tears in reptiles, birds and others mammals, which would elucidate the mechanisms governing the maintenance of ocular homeostasis. In this work, electrophoretic profiles and an evaluation of total protein, albumin, urea, glucose, and cholesterol concentrations in tears of semi-aquatic, terrestrial, and marine reptiles (, and ), birds ( and ), and mammals ( and ) were apresented.

The role of Xist-mediated Polycomb recruitment in the initiation of X-chromosome inactivation.

Xist RNA has been established as the master regulator of X-chromosome inactivation (XCI) in female eutherian mammals, but its mechanism of action remains unclear. By creating novel Xist-inducible mutants at the endogenous locus in male mouse embryonic stem (ES) cells, we dissect the role of the conserved A-B-C-F repeats in the initiation of XCI. We find that transcriptional silencing can be largely uncoupled from Polycomb repressive complex 1 and complex 2 (PRC1/2) recruitment, which requires B and C repeats.

Correction to: Photography-based method for assessing fluorescein clearance test in dogs.

The original article [1] contained an error whereby the respective legends of Figs. 2 and 3 were mistakenly interchanged. This error has now been amended.

Photography-based method for assessing fluorescein clearance test in dogs.

Background: The fluorescein clearance test (FCT) provides insight into the tear film dynamics. The purpose of this study was to describe an inexpensive and practical method for assessing FCT in dogs, using photography and software analysis, and to assess the retention time of 1 vs. 2 eye drops on the canine ocular surface.

Loss of hierarchical imprinting regulation at the Prader-Willi/Angelman syndrome locus in human iPSCs.

The human chr15q11-q13 imprinted cluster is linked to several disorders, including Prader-Willi (PWS) and Angelman (AS) syndromes. Recently, disease modeling approaches based on induced pluripotent stem cells (iPSCs) have been used to study these syndromes. A concern regarding the use of these cells for imprinted disease modeling is the numerous imprinting defects found in many iPSCs.

Evaluation of lacrimal production, osmolarity, crystallization, proteomic profile, and biochemistry of capuchin monkeys' tear film.

Background: To evaluate the composition and characteristics of capuchin monkey (CM) tear film.

Methods: Eleven CM (Sapajus sp.) was evaluated.

CONJUNCTIVAL BACTERIAL FLORA, ANTIBIOGRAM, AND LACRIMAL PRODUCTION TESTS OF COLLARED ANTEATER (TAMANDUA TETRADACTYLA).

The collared anteater ( Tamandua tetradactyla ) is adapted to a variety of habitats. It is a solitary species for which no reference values for ophthalmic tests have been established. Eight animals ranging from 1 to 4 yr of age, two males and six females, were manually restrained for assessment.

SETD2 is required for DNA double-strand break repair and activation of the p53-mediated checkpoint.

Histone modifications establish the chromatin states that coordinate the DNA damage response. In this study, we show that SETD2, the enzyme that trimethylates histone H3 lysine 36 (H3K36me3), is required for ATM activation upon DNA double-strand breaks (DSBs). Moreover, we find that SETD2 is necessary for homologous recombination repair of DSBs by promoting the formation of RAD51 presynaptic filaments.

Histone methyltransferase SETD2 coordinates FACT recruitment with nucleosome dynamics during transcription.

Histone H3 of nucleosomes positioned on active genes is trimethylated at Lys36 (H3K36me3) by the SETD2 (also termed KMT3A/SET2 or HYPB) methyltransferase. Previous studies in yeast indicated that H3K36me3 prevents spurious intragenic transcription initiation through recruitment of a histone deacetylase complex, a mechanism that is not conserved in mammals. Here, we report that downregulation of SETD2 in human cells leads to intragenic transcription initiation in at least 11% of active genes.