Innovative approaches to genome editing in avian species.

The tools available for genome engineering have significantly improved over the last 5 years, allowing scientist to make precise edits to the genome. Along with the development of these new genome editing tools has come advancements in technologies used to deliver them. In mammals genome engineering tools are typically delivered into in vitro fertilized single cell embryos which are subsequently cultured and then implanted into a recipient animal.

Advances in genetic engineering of the avian genome: "Realising the promise".

This review provides an historic perspective of the key steps from those reported at the 1st Transgenic Animal Research Conference in 1997 through to the very latest developments in avian transgenesis. Eighteen years later, on the occasion of the 10th conference in this series, we have seen breakthrough advances in the use of viral vectors and transposons to transform the germline via the direct manipulation of the chicken embryo, through to the establishment of PGC cultures allowing in vitro modification, expansion into populations to analyse the genetic modifications and then injection of these cells into embryos to create germline chimeras. We have now reached an unprecedented time in the history of chicken transgenic research where we have the technology to introduce precise, targeted modifications into the chicken genome, ranging from; new transgenes that provide improved phenotypes such as increased resilience to economically important diseases; the targeted disruption of immunoglobulin genes and replacement with human sequences to generate transgenic chickens that express "humanised" antibodies for biopharming; and the deletion of specific nucleotides to generate targeted gene knockout chickens for functional genomics.

The effect of RAFT-derived cationic block copolymer structure on gene silencing efficiency.

In this work a series of ABA tri-block copolymers was prepared from oligo(ethylene glycol) methyl ether methacrylate (OEGMA(475)) and N,N-dimethylaminoethyl methacrylate (DMAEMA) to investigate the effect of polymer composition on cell viability, siRNA uptake, serum stability and gene silencing. Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization was used as the method of polymer synthesis as this technique allows the preparation of well-defined block copolymers with low polydispersity. Eight block copolymers were prepared by systematically varying the central cationic block (DMAEMA) length from 38 to 192 monomer units and the outer hydrophilic block (OEGMA(475)) from 7 to 69 units.

Manipulation of estrogen synthesis alters MIR202* expression in embryonic chicken gonads.

Tissue-specific patterns of microRNA (miRNA) expression contribute to organogenesis during embryonic development. Using the embryonic chicken gonads as a model for vertebrate gonadogenesis, we previously reported that miRNAs are expressed in a sexually dimorphic manner during gonadal sex differentiation. Being male biased, we hypothesised that up-regulation of microRNA 202* (MIR202*) is characteristic of testicular differentiation.

Sexually dimorphic microRNA expression during chicken embryonic gonadal development.

MicroRNAs are a highly conserved class of small RNAs that function in a sequence-specific manner to posttranscriptionally regulate gene expression. Tissue-specific miRNA expression studies have discovered numerous functions for miRNAs in various aspects of embryogenesis, but a role for miRNAs in gonadal development and sex differentiation has not yet been reported. Using the chicken embryo as a model, microarrays were used to profile the expression of chicken miRNAs prior to, during, and after the time of gonadal sex differentiation (Embryonic Day 5.

Recovery of Mycobacterium avium subspecies paratuberculosis from the natural host for the extraction and analysis in vivo-derived RNA.

RNA has been extracted and analysed from in vivo-derived Mycobacterium avium subspecies paratuberculosis recovered from the natural host. The bacteria were selectively extracted from the intestinal tissue of two goats exhibiting clinical signs of Johne's disease. Small intestine was rapidly removed, luminal contents washed away and the mucosa and submucosa harvested.