Key Insights from the 11th Transgenic Technology Meeting
February 2013 | Guangzhou, China
In February 2013, a significant milestone in the field of genetic engineering occurred—the 11th Transgenic Technology (TT2013) meeting was held in Guangzhou, China, marking the first time this prestigious conference had visited Asia 3 . Over 340 scientists from 29 countries gathered at the Baiyun International Convention Center, situated in the shadow of White Cloud Mountain, to share groundbreaking research 3 .
This gathering came at a pivotal moment, as revolutionary new technologies like targeted nucleases were beginning to transform how researchers create and study transgenic animals—organisms whose genomes have been altered to carry genes from other species 2 9 . The conference showcased an enormous progress and investment in animal transgenesis, particularly from Chinese researchers, heralding what one presenter termed "a new era for mutagenesis in China" 3 .
A transgenic animal is one whose genome has been deliberately altered to carry genes from another species or to have specific genes modified or "knocked out" 2 9 . The first successful transgenic animal was a mouse, followed soon after by pigs, sheep, cattle, and rabbits 2 .
This was the most common method used for decades, involving the microinjection of foreign DNA directly into the pronuclei of fertilized zygotes 2 .
This approach involves inserting foreign DNA into embryonic stem cells cultured in vitro, then using these cells to create transgenic chimeric mice 2 .
A surprisingly efficient technique where sperm cells are incubated with foreign DNA before fertilization 2 .
Using engineered viruses like retroviruses, adeno-associated viruses (AAV), and adenoviruses to deliver genetic material into cells 2 .
A major theme throughout TT2013 was the growing impact of targeted nucleases—revolutionary tools that allow precise editing of specific genes rather than random insertion of foreign DNA 3 . While the now-famous CRISPR-Cas9 system was only beginning to emerge in 2013, earlier technologies like zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs) were already making waves by dramatically improving the efficiency of creating genetic modifications 3 .
Demonstrated how ZFNs could make precise modifications to the promoter of the Zbtb7b gene in mice, a transcription factor critical for helper T cell development 3 .
Discussed the relative ease of designing and generating TALENs and illustrated their use in creating heritable gene targets and large deletions in zebrafish genomes 3 .
Presented work using ZFNs to generate a PPAR-g gene knockout in pigs, creating heterozygous animals through nuclear transfer after modifying genes in fibroblasts 3 .
Among the many innovations presented at TT2013, one standout example of the advanced tools being developed was a transgenic toolkit for visualizing and perturbing microtubules in living organisms. Microtubules are essential components of cellular architecture, but their functions in differentiated cells within intact tissues were poorly understood due to technical limitations 7 .
Scientists generated a transgenic mouse containing a cassette encoding a GFP-tagged copy of EB1, a microtubule plus-tip tracking protein, under control of a tetracycline-responsive element (TRE) promoter 7 .
The system was designed so EB1-GFP expression could be controlled temporally through doxycycline exposure and spatially through cell- or tissue-specific tTA/rtTA lines or tissue-specific Cre lines paired with the Rosa-rtTA line 7 .
Researchers created TRE-spastin mice expressing a highly active M85 spastin isoform with an N-terminal HA tag under the TRE promoter. Spastin is a microtubule-severing protein whose overexpression dramatically perturbs microtubule organization 7 .
The system was validated first in keratinocytes transfected with K14-rtTA and TRE-spastin plasmids, then in CMV-rtTA; TRE-spastin mice where doxycycline administration induced spastin expression 7 .
When researchers compared microtubule dynamics in intact embryos versus cultured primary keratinocytes, they found dramatically increased polymerization rates in isolated cells, suggesting that microtubule dynamics are altered as primary cells initiate a wound-healing response in culture 7 .
The experimental results revealed fascinating insights into microtubule behavior during cellular differentiation:
| Cell Type | Mean Growth Speed (µm/min) | Standard Deviation |
|---|---|---|
| Basal cells | 11.1 | ± 3.1 |
| Spinous cells | 12.2 | ± 3.3 |
| Granular cells | 7.1 | ± 3.7 |
The data revealed that microtubule dynamics are strongly suppressed in differentiated keratinocytes in two distinct steps 7 . The first change occurred as basal cells differentiated into spinous cells, with a minor increase in growth speed but significantly shorter growth duration. The second, more dramatic change happened as spinous cells matured into granular cells, where microtubule polymerization rates were strongly suppressed and the occurrence of very slow-growing microtubules increased significantly 7 .
When spastin was overexpressed to disrupt microtubules in post-mitotic keratinocytes, researchers observed profound consequences on epidermal morphogenesis, uncovering both cell-autonomous roles in cell flattening and non-cell-autonomous requirements for microtubules in regulating proliferation, differentiation, and tissue architecture 7 .
The field of transgenics relies on specialized reagents and tools that enable precise genetic manipulation. The following table outlines key components mentioned in the TT2013 research:
| Reagent/Tool | Function | Example from Research |
|---|---|---|
| TRE-EB1-GFP | Visualizes microtubule dynamics in live cells | TRE-EB1 mouse line allows quantification of microtubule behavior during differentiation 7 |
| TRE-spastin | Genetically perturbs microtubule organization | TRE-spastin mouse line enables microtubule disruption in specific cell types 7 |
| TALENs | Enables precise genome editing | Used for heritable gene targeting in zebrafish and creating large deletions 3 |
| ZFNs | Facilitates targeted gene modifications | Applied to modify promoter regions in mice and create gene knockouts in pigs 3 |
| Embryonic Stem (ES) Cells | Allows genetic manipulation prior to embryo formation | Used with 2i culture medium containing Map2k1 and Gsk3b inhibitors to maintain pluripotency 3 |
| Sperm-Mediated Gene Transfer | Simple method for mass transgenesis | Used to introduce growth hormone genes in sheep to enhance growth rates 2 |
The TT2013 meeting also honored pioneers in the field, most notably Allan Bradley of the Wellcome Trust Sanger Institute, who received the 9th International Society of Transgenic Technologies Prize for his outstanding contributions 3 .
In his prize lecture, Bradley recounted his personal journey in developing embryonic stem cell technologies, from "not even knowing what a stem cell was" to developing techniques and reagents that revolutionized functional genomics in mice 3 . His work helped facilitate the extraordinary achievement of targeting the vast majority of genes in mouse embryonic stem cells—a resource that allows the study of gene function in ways that were "virtually unthinkable, even a few years ago" 3 .
The conference also featured practical sessions on running transgenic facilities, with discussions on troubleshooting common techniques like superovulation, rederivation and DNA preparation, and developing cutting-edge technologies while maintaining essential services 3 .
Recipient of the 9th International Society of Transgenic Technologies Prize
Wellcome Trust Sanger Institute
The 11th Transgenic Technology Meeting in Guangzhou captured a field at a pivotal moment of transformation. While established techniques like pronuclear microinjection and embryonic stem cell manipulation remained important, new technologies like ZFNs and TALENs were dramatically accelerating and refining the process of creating transgenic animals 3 .
The innovative tools presented, such as the microtubule visualization toolkit, demonstrated how increasingly sophisticated genetic manipulations were enabling researchers to address fundamental biological questions with unprecedented precision 7 .
The progress showcased at TT2013 laid essential groundwork for the CRISPR revolution that would soon follow, setting the stage for today's era of precise, accessible, and efficient genetic engineering across virtually all animal species. As these technologies continue to evolve, they promise to further accelerate our understanding of gene function and our ability to develop new treatments for human diseases—fulfilling the promise so palpable at that landmark meeting in Guangzhou.