Search

Author(s): Federico Tessadori [sup.1] , Dennis E. M. de Bakker [sup.1] , Lindsey Barske [sup.2] [sup.6] [sup.7] , Nellie Nelson [sup.2] , Hermine A. Algra [sup.1] , Sven Willekers [sup.1] [...]

This is the story of a fish that spent years treading water. The first U.S. sales of the AquAdvantage salmon, a faster-growing, genetically engineered fish, have finally begun. The farmed [...]

During the first decade of the new millennium, remarkable advances in technology allowed investigators in all areas of biological research to collect massive amounts of genetic data at an unprecedented [...]

During the first decade of the new millennium, remarkable advances in technology allowed investigators in all areas of biological research to collect massive amounts of genetic data at an unprecedented [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2009.12.040 Byline: Helene Auger (a), Yasunori Sasakura (b), Jean-Stephane Joly (a), William R. Jeffery (c)(d) Keywords: Ascidians; Ciona; Transgenic animals; Regeneration; Oral pigment organs; Polarity; Pattern formation Abstract: Ascidians have powerful capacities for regeneration but the underlying mechanisms are poorly understood. Here we examine oral siphon regeneration in the solitary ascidian Ciona intestinalis. Following amputation, the oral siphon rapidly reforms oral pigment organs (OPO) at its distal margin prior to slower regeneration of proximal siphon parts. The early stages of oral siphon reformation include cell proliferation and re-growth of the siphon nerves, although the neural complex (adult brain and associated organs) is not required for regeneration. Young animals reform OPO more rapidly after amputation than old animals indicating that regeneration is age dependent. UV irradiation, microcautery, and cultured siphon explant experiments indicate that OPOs are replaced as independent units based on local differentiation of progenitor cells within the siphon, rather than by cell migration from a distant source in the body. The typical pattern of eight OPOs and siphon lobes is restored with fidelity after distal amputation of the oral siphon, but as many as 16 OPOs and lobes can be reformed following proximal amputation near the siphon base. Thus, the pattern of OPO regeneration is determined by cues positioned along the proximal distal axis of the oral siphon. A model is presented in which columns of siphon tissue along the proximal-distal axis below pre-existing OPO are responsible for reproducing the normal OPO pattern during regeneration. This study reveals previously unknown principles of oral siphon and OPO regeneration that will be important for developing Ciona as a regeneration model in urochordates, which may be the closest living relatives of vertebrates. Author Affiliation: (a) INRA MSNC Group, DEPSN, Institut A. Fessard, CNRS, 1 Avenue de la Terrasse, 91198 Gif-Sur-Yvette, France (b) Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, Japan (c) Marine Biological Laboratory, Woods Hole, MA 02543, USA (d) Department of Biology, University of Maryland, College Park, MD 20742, USA Article History: Received 20 January 2009; Revised 12 December 2009; Accepted 29 December 2009

Transgenic animal models have provided a vital insight into the pathogenesis of cardiovascular disease, but functional cardiac assessment is often limited by high heart rates and small heart size. We hypothesized that in the presence of concentric left ventricular (LV) hypertrophy (LVH), load-sensitive measures of contractility may be misinterpreted as overestimating global cardiac function, because the normal function of excess sarcomeres may displace a greater volume of blood during contraction. Conductance catheter technology was used to evaluate pressure-volume (P-V) relationships as a load-insensitive method of assessing cardiac function in vivo in 18-wk-old heterozygous (mRen-2)27 transgenic rats (a model of LVH), compared with age-matched Sprague-Dawley (SD) controls. Anesthetized animals underwent echocardiography followed by P-V loop analysis. Blood pressure, body weight, and heart rate were higher in the Ren-2 rats (P < 0.05). Load-sensitive measures of systolic function, including fractional area change, fractional shortening, ejection fraction, and positive peak rate of LV pressure development, were greater in the Ren-2 than control animals (P < 0.05). Load-insensitive measures of systolic function, including the preload recruitable stroke work relationship and the end-systolic P-V relationship, were not different between Ren-2 and SD rats. Regional wall motion assessed by circumferential shortening velocity suggested enhanced circumferential fiber contractility in the Ren-2 rats (P = 0.02), but tissue Doppler imaging, used to assess longitudinal function, was not different between groups. Although conventional measures suggested enhanced systolic function in the Ren-2 rat, load-insensitive measures of contractility were not different between Ren-2 and SD animals. These findings suggest that the normal range of values for load-sensitive indexes of contractility needs to be altered according to the degree of LVH. To accurately identify changes in systolic function, we suggest that a combination of echocardiography with assessment of load-insensitive measures be used routinely. hypertension; conductance catheter; echocardiography; transgenic rat

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2005.11.037 Byline: Lidia Sobkow (a), Hans-Henning Epperlein (b), Stephan Herklotz (a), Werner L. Straube (a), Elly M. Tanaka (a) Keywords: Axolotl; Transgenesis; GFP; ISceI meganuclease; Regeneration; Fin; Blood Abstract: The development of transgenesis in axolotls is crucial for studying development and regeneration as it would allow for long-term cell fate tracing as well as gene expression analysis. We demonstrate here that plasmid injection into the one-cell stage axolotl embryo generates mosaic transgenic animals that display germline transmission of the transgene. The inclusion of SceI meganuclease in the injections (Thermes, V., Grabher, C., Ristoratore, F., Bourrat, F., Choulika, A., Wittbrodt, J., Joly, J.S., 2002. I-SceI meganuclease mediates highly efficient transgenesis in fish. Mech. Dev. 118, 91-98) resulted in a higher percentage of F0 animals displaying strong expression throughout the body. This represents the first demonstration in the axolotl of germline transmission of a transgene. Using this technique we have generated a germline transgenic animal expressing GFP ubiquitously in all tissues examined. We have used this animal to study cell fate in the dorsal fin during development. We have uncovered a contribution of somite cells to dorsal fin mesenchyme in the axolotl, which was previously assumed to derive solely from neural crest. We have also studied the role of blood during tail regeneration by transplanting the ventral blood-forming region from GFP+ embryos into unlabeled hosts. During tail regeneration, we do not observe GFP+ cells contributing to muscle or nerve, suggesting that during tail regeneration blood stem cells do not undergo significant plasticity. Author Affiliation: (a) Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany (b) Department of Anatomy, Fetscherstr. 74, TU Dresden, 01307 Dresden, Germany Article History: Received 14 June 2005; Revised 22 November 2005; Accepted 22 November 2005

Research has been conducted on the exchangeable plasma apolipoprotein C-II (apoC-II). The apoC-II genetic deficiencies and overexpression in transgenic mice have been examined.d

Metamorphosis of anuran tadpoles is controlled by thyroid hormone (TH). Here we demonstrate that transgenic Xenopus laevis tadpoles expressing a dominant negative form of TH receptor-[Alpha] are resistant to a wide variety of the metamorphic changes induced by TH. This result confirms that TH receptors mediate both early and late developmental programs of metamorphosis as diverse as growth in the brain, limb buds, nose and Meckel's cartilage, remodeling of the intestine, and death and resorption of the gills and tail.

Author(s): J. Robert Britton [sup.1] , Rodolphe E. Gozlan [sup.1] [sup.2] Author Affiliations: (1) Bournemouth University, Poole, UK (2) Institut de Recherche pour le Développement (UMR 207), Paris, France As [...]