Whole genome assessment of the retinal response to diabetes reveals a progressive neurovascular inflammatory response

<p>Abstract</p> <p>Background</p> <p>Despite advances in the understanding of diabetic retinopathy, the nature and time course of molecular changes in the retina with diabetes are incompletely described. This study characterized the functional and molecular phenotype of the retina with increasing durations of diabetes.</p> <p>Results</p> <p>Using the streptozotocin-induced rat model of diabetes, levels of retinal permeability, caspase activity, and gene expression were examined after 1 and 3 months of diabetes. Gene expression changes were identified by whole genome microarray and confirmed by qPCR in the same set of animals as used in the microarray analyses and subsequently validated in independent sets of animals. Increased levels of vascular permeability and caspase-3 activity were observed at 3 months of diabetes, but not 1 month. Significantly more and larger magnitude gene expression changes were observed after 3 months than after 1 month of diabetes. Quantitative PCR validation of selected genes related to inflammation, microvasculature and neuronal function confirmed gene expression changes in multiple independent sets of animals.</p> <p>Conclusion</p> <p>These changes in permeability, apoptosis, and gene expression provide further evidence of progressive retinal malfunction with increasing duration of diabetes. The specific gene expression changes confirmed in multiple sets of animals indicate that pro-inflammatory, anti-vascular barrier, and neurodegenerative changes occur in tandem with functional increases in apoptosis and vascular permeability. These responses are shared with the clinically documented inflammatory response in diabetic retinopathy suggesting that this model may be used to test anti-inflammatory therapeutics.</p

In Vivo Chromatin Organization of Mouse Rod Photoreceptors Correlates with Histone Modifications

BACKGROUND: The folding of genetic information into chromatin plays important regulatory roles in many nuclear processes and particularly in gene transcription. Post translational histone modifications are associated with specific chromatin condensation states and with distinct transcriptional activities. The peculiar chromatin organization of rod photoreceptor nuclei, with a large central domain of condensed chromatin surrounded by a thin border of extended chromatin was used as a model to correlate in vivo chromatin structure, histone modifications and transcriptional activity. METHODOLOGY: We investigated the functional relationships between chromatin compaction, distribution of histone modifications and location of RNA polymerase II in intact murine rod photoreceptors using cryo-preparation methods, electron tomography and immunogold labeling. Our results show that the characteristic central heterochromatin of rod nuclei is organized into concentric domains characterized by a progressive loosening of the chromatin architecture from inside towards outside and by specific combinations of silencing histone marks. The peripheral heterochromatin is formed by closely packed 30 nm fibers as revealed by a characteristic optical diffraction signal. Unexpectedly, the still highly condensed most external heterochromatin domain contains acetylated histones, which are usually associated with active transcription and decondensed chromatin. Histone acetylation is thus not sufficient in vivo for complete chromatin decondensation. The euchromatin domain contains several degrees of chromatin compaction and the histone tails are hyperacetylated, enriched in H3K4 monomethylation and hypo trimethylated on H3K9, H3K27 and H4K20. The transcriptionally active RNA polymerases II molecules are confined in the euchromatin domain and are preferentially located at the vicinity of the interface with heterochromatin. CONCLUSIONS: Our results show that transcription is located in the most decondensed and highly acetylated chromatin regions, but since acetylation is found associated with compact chromatin it is not sufficient to decondense chromatin in vivo. We also show that a combination of histone marks defines distinct concentric heterochromatin domains

Seasonal-Changes in Testicular Size, Plasma Testosterone Concentration and Body-Weight in Captive Flying Foxes (Pteropus-Poliocephalus and P-Scapulatus)

Adult male flying foxes Pteropus poliocephalus and P. scapulatus were captured in south-east Queensland and kept in outdoor enclosures. Testicular size (TS), plasma testosterone concentrations (PTC) and body weight (BW) were measured over 1-year periods. Testicular recrudescence in P. poliocephalus began before the summer solstice and TS was greatest during mid-March (autumn) and lowest from July to September. Large increases in PTC were observed in all individuals approximately 1 month after the peak in TS. BW also increased around the time of the mating season, changes being correlated significantly with changes in TS. Mating occurred between April and June, and births from late October to late November. In P. scapulatus, TS was greatest in the spring (October) and least in the autumn (February to May); PTC fluctuated throughout the year in this species but, unlike P. poliocephalus, did not show a single large increase in the mating season. BW showed a similar seasonal pattern to that seen in P. poliocephalus, being greatest at the time of greatest TS. Mating occurred in October to November, and births in autumn. In captivity, in outdoor enclosures, these species maintained the seasonal reproductive patterns observed in the wild. The 2 species respond differently to the same environmental cues in terms of regulation of the timing of their breeding seasons

Cycle of the Seminiferous Epithelium in the Gray-Headed Fruit Bat, Pteropus-Poliocephalus

The seminiferous epithelial cycle of wild P. poliocephalus could be divided into eight stages on the basis of cellular associations and nuclear morphology. The relative frequencies of the stages (1–8) were, respectively: 15·8, 20·5, 9·4, 8·9, 11·1, 7·7, 9·8, and 16·8%. The duration of the cycle was determined by intratesticular injection of [Hlthymidine followed by autoradiography and estimated to be 16·0 days. The duration of meiotic prophase and spermiogenesis were both 23·3 days. Spermatocyte DNA synthesis appeared to occur in leptotene primary spermatocytes in stage 2. The duration of spermatogenesis is similar to that in man although the organization of the cycle resembles that of rodents

DNA Methylomes Reveal Biological Networks Involved in Human Eye Development, Functions and Associated Disorders

Abstract This work provides a comprehensive CpG methylation landscape of the different layers of the human eye that unveils the gene networks associated with their biological functions and how these are disrupted in common visual disorders. Herein, we firstly determined the role of CpG methylation in the regulation of ocular tissue-specification and described hypermethylation of retinal transcription factors (i.e., PAX6, RAX, SIX6) in a tissue-dependent manner. Second, we have characterized the DNA methylome of visual disorders linked to internal and external environmental factors. Main conclusions allow certifying that crucial pathways related to Wnt-MAPK signaling pathways or neuroinflammation are epigenetically controlled in the fibrotic disorders involved in retinal detachment, but results also reinforced the contribution of neurovascularization (ETS1, HES5, PRDM16) in diabetic retinopathy. Finally, we had studied the methylome in the most frequent intraocular tumors in adults and children (uveal melanoma and retinoblastoma, respectively). We observed that hypermethylation of tumor suppressor genes is a frequent event in ocular tumors, but also unmethylation is associated with tumorogenesis. Interestingly, unmethylation of the proto-oncogen RAB31 was a predictor of metastasis risk in uveal melanoma. Loss of methylation of the oncogenic mir-17-92 cluster was detected in primary tissues but also in blood from patients