THE EFFECT OF HDAC INHIBITORS ON RETINAL DEVELOPMENT OF CHICK EMBRYO

poster abstractIntroduction: Gene expression is regulated by the accessibility of regulatory cis-acting DNA elements as well as availability of transcription factors. Histone deacetylase (HDAC) can regulate gene expression by deacetylating histone tails, which leads to a closed conformation of the DNA/histone complex and generally a reduction in expression. HDACs have been proposed to play a key role in cell survival, proliferation and differentiation; however, fewer studies have been focusing on the role of HDACs in the developing vertebrate retina. Methods: Chick retinal explants were treated with vehicle (dimethyl sulphoxide(DMSO)) or 1.0 M Trichstatin A (TSA), a known inhibitor of class 1 and 2 HDACs. Immunohistochemistry (IHC) was performed to analyze the levels of cleaved caspase 3, a protein activated during apoptosis, phospho-histone 3 (pH3) marker for mitotic phase, SOX2 which marks progenitor cells, and Islet-1 which marks differentiated cells. Digital images were analyzed using Image J/FIJI software for numbers of labeled cells. Results: After treatment with control or TSA, numbers of progenitor and differentiating cells were quantified. TSA-treated samples showed a statistically significant increase in SOX2+ (progenitors) and an increase in islet-1+ (differentiating) cells. To assess if any differences in proliferation and/or cell death that might lead to an increase in the number of progenitor and differentiating cells, samples were labeled for pH3 or cleaved caspase 3. Treatment with TSA led to increases in cells positive for pH3 and a statistically significant increase in cells positive for cleaved caspase 3 compared to controls. Conclusions: HDAC inhibitor, TSA, increased the number of progenitor and differentiating cells by increasing proliferation within the developing retina. However, there was also an increase in the number of cells undergoing apoptosis. Ongoing studies will determine which HDACs may be responsible for these results

Microglia activation is essential for BMP7-mediated retinal reactive gliosis

Our previous studies have shown that BMP7 is able to trigger activation of retinal macroglia. However, these studies showed the responsiveness of Müller glial cells and retinal astrocytes in vitro was attenuated in comparison to those in vivo, indicating other retinal cell types may be mediating the response of the macroglial cells to BMP7. In this study, we test the hypothesis that BMP7-mediated gliosis is the result of inflammatory signaling from retinal microglia

Differential Prox-1 and CD 31 expression in mucousae, cutaneous and soft tissue vascular lesions and tumors

The study of lymphatic vessels and lymphatic tumors has been hampered with difficulty due to the overlapping morphological features between blood and lymphatic endothelial cells, as well as to the lack of specific lymphatic endothelial markers. Over the last few years, lymphatic vessels and lymphangiogenesis have received great attention owing to their putative implications in terms of metastatic dissemination and the promise of targets for lymphangiogenic therapy. Prox-1 is a nuclear transcription factor that plays a major role during embryonic lymphangiogenesis and is deemed to be a useful marker for differentiating lymphatic endothelial cells from the other blood vessels endothelial cells. Here, we describe a double-immunostaining strategy for formalin-fixed, paraffinembedded tissues that aims at evaluating the distribution of Prox-1 and CD 31 – a cytoplasmic pan-endothelial marker -in a series of 28 mucousae, cutaneous and soft tissue vascular lesions and tumors, including hemangiomas, lymphangiomas, lymphangiectasia, and Kaposi’s sarcomas. Our results showed that in non-lesional mucousae and skin, Prox-1 decorated exclusively the nuclei of endothelial cells in lymphatic vessels. Prox-1 stained almost all the benign lymphatic vascular lesions/tumors (91%) and was absent or only focally positive in 75% of blood vascular tumors. CD 31 stained endothelial cells of blood vessels of superficial and deep dermal plexuses, lymphatics, and all blood vascular lesions/tumors. Kaposi’s sarcomas were all positive for both CD 31 and Prox-1 markers. In conclusion, although Prox-1 expression in vascular lesions/tumors was not entirely restricted to tumors with known lymphatic differentiation, CD 31/Prox-1 double-immunolabeling can be used as an adjunct marker to identify lymphatic vessels in routinely processed formalin-fixed, paraffin-embedded samples

Ranger perceptions of, and engagement with, monitoring of elephant poaching

Ranger‐based monitoring has enormous potential to inform conservation globally, with hundreds of thousands of rangers patrolling extensive areas and recording observations of illegal activities and biodiversity. Much quantitative research has demonstrated the pitfalls and potential of data collection by rangers, but little work has considered its human dimensions. Yet poor engagement with, and ownership of, monitoring by those undertaking it may compromise data quality and thereby limit evidence‐based conservation. We interviewed rangers and supervisors involved in a programme for monitoring and managing elephant poaching in the Zambezi Valley, Zimbabwe. We assess the importance that rangers ascribed to data collection within their broader occupation, and their level of engagement with data management and use. We found that rangers saw the collection of biodiversity data as a routine duty that helped guide patrol strategy. Reporting these data was perceived as a primary way of demonstrating fulfilled responsibilities to their supervisors. Rangers did not, however, engage actively with data management and use. Ranger sentiment was evenly divided between those who said feedback on how the data they collected were used would motivate more engaged data collection, and those who said they would continue collecting data regardless, out of duty. Three elements of the occupational culture of rangers at our site—a strong sense of duty, deference to authority and knowing their defined responsibilities within the organizational hierarchy—were identified as key drivers of their engagement with monitoring. Building on these findings, we develop a theory of change to develop more meaningful engagement of rangers with monitoring. We argue that more effective and sustainable monitoring can be achieved by building on existing ranger culture while also fostering rangers' appreciation of data collection and utilization. Addressing key challenges around ranger well‐being, and resource and capacity needs, is also essential

Progenitor cells of the rod-free area centralis originate in the anterior dorsal optic vesicle

<p>Abstract</p> <p>Background</p> <p>Nervous system development is dependent on early regional specification to create functionally distinct tissues within an initially undifferentiated zone. Within the retina, photoreceptors are topographically organized with rod free area centrales faithfully generated at the centre of gaze. How does the developing eye regulate this placement? Conventional wisdom indicates that the distal tip of the growing optic vesicle (OV) gives rise to the area centralis/fovea. Ectopic expression and ablation studies do not fully support this view, creating a controversy as to the origin of this region. In this study, the lineage of cells in the chicken OV was traced using DiI. The location of labelled cells was mapped onto the retina in relation to the rod-free zone at embryonic (E) 7 and E17.5. The ability to regenerate a rod free area after OV ablation was determined in conjunction with lineage tracing.</p> <p>Results</p> <p>Anterior OV gave rise to cells in nasal retina and posterior OV became temporal retina. The OV distal tip gave rise to cells above the optic nerve head. A dorsal and anterior region of the OV correlated with cells in the developing rod free area centralis. Only ablations including the dorsal anterior region gave rise to a retina lacking a rod free zone. DiI application after ablation indicated that cells movements were greater along the anterior/posterior axis compared with the dorsal/ventral axis.</p> <p>Conclusion</p> <p>Our data support the idea that the chicken rod free area centralis originates from cells located near, but not at the distal tip of the developing OV. Therefore, the hypothesis that the area centralis is derived from cells at the distal tip of the OV is not supported; rather, a region anterior and dorsal to the distal tip gives rise to the rod free region. When compared with other studies of retinal development, our results are supported on molecular, morphological and functional levels. Our data will lead to a better understanding of the mechanisms underlying the topographic organization of the retina, the origin of the rod free zone, and the general issue of compartmentalization of neural tissue before any indication of morphological differentiation.</p

Genetics and evidence for balancing selection of a sex-linked colour polymorphism in a songbird

Colour polymorphisms play a key role in sexual selection and speciation, yet the mechanisms that generate and maintain them are not fully understood. Here, we use genomic and transcriptomic tools to identify the precise genetic architecture and evolutionary history of a sex-linked colour polymorphism in the Gouldian finch Erythrura gouldiae that is also accompanied by remarkable differences in behaviour and physiology. We find that differences in colour are associated with an ~72-kbp region of the Z chromosome in a putative regulatory region for follistatin, an antagonist of the TGF-β superfamily genes. The region is highly differentiated between morphs, unlike the rest of the genome, yet we find no evidence that an inversion is involved in maintaining the distinct haplotypes. Coalescent simulations confirm that there is elevated nucleotide diversity and an excess of intermediate frequency alleles at this locus. We conclude that this pleiotropic colour polymorphism is most probably maintained by balancing selection

Setting and implementing standards for management of wild tigers

Tiger numbers have collapsed so dramatically that conservationists are adopting a strategy of securing populations in priority conservation landscapes. This includes improving management effectiveness in these sites. The Conservation Assured|Tiger Standards (CA|TS) are designed to help ensure effectiveness and provide a benchmark against which to measure progress. CA|TS is a distillation of best practice and a roadmap to management effectiveness, linking management to expert-driven standards covering all aspects of management, including those which are tiger-specific (monitoring, maintenance of prey, control of poaching). Sites are audited against a set of standards and if met, are accredited as CA|TS Approved. We describe CA|TS in the context of tiger conservation, describe the evolution and philosophy of the system and consider its application across the tiger range, before drawing on lessons learned from 5 years of development. Important benefits include the independence of CA|TS from existing governmental or NGO institutions, the emphasis on regional governance and the existence of active support groups. Conversely, the participatory approach has slowed implementation. CA|TS remains more attractive to well managed sites than to sites that are struggling, although building capacity in the latter is its key aim. The close connections between people working on tiger conservation make some aspects of independent assessment challenging. Finally, if CA|TS is to succeed in its long term aims, it needs to go hand in hand with secure and adequate funding to increase management capacity in many tiger conservation areas