A transgenic pig model expressing a CMV-ZsGreen1 reporter across an extensive array of tissues

Role of gonadotropin-releasing hormone-II and its receptor in swine reproduction

The pig represents the only livestock mammal capable of producing a functional protein for the second mammalian form of gonadotropin-releasing hormone (GnRH-II) and its receptor (GnRHR-II). To examine the role of GnRH-II and its receptor in pig reproduction, we produced a unique swine line with ubiquitous knockdown of endogenous GnRHR-II levels (GnRHR-II knockdown [KD]), which is largely the focus of this review. In mature GnRHR-II KD males, circulating testosterone concentrations were 82% lower than littermate control boars, despite similar luteinizing hormone (LH) levels. In addition, nine other gonadal steroids were reduced in the serum of GnRHR-II KD boars, whereas adrenal steroids (except 11-deoxycortisol) did not differ between lines. Interestingly, testes from GnRHR-II KD males had fewer, hypertrophic Leydig cells and fewer, enlarged seminiferous tubules than control testes. As expected, downstream reproductive traits such as androgen-dependent organ weights and semen characteristics were also significantly reduced in GnRHR-II KD versus control boars. Next, we explored the importance of this novel ligand/receptor complex in female reproduction. Transgenic gilts had fewer, but heavier, corpora lutea with smaller luteal cells than littermate control females. Although the number of antral follicles were similar between lines, the diameter of antral follicles tended to be larger in GnRHR-II KD females. In regard to steroidogenesis, circulating concentrations of progesterone and 17β-estradiol were lower in transgenic compared to control gilts, even though serum levels of follicle-stimulating hormone and LH were similar. Thus, GnRH-II and GnRHR-II represent a potential avenue to enhance fertility and promote the profitability of pork producers.

Comparative Evaluation of Inducible Cre Mouse Models for Fibroblast Targeting in the Healthy and Infarcted Myocardium

Several Cre recombinase transgenic mouse models have been generated for cardiac fibroblast (CF) tracking and heart regulation. However, there is still no consensus on the ideal mouse model to optimally identify and/or regulate these cells. Here, a comparative evaluation of the efficiency and specificity of the indirect reporter Cre-loxP system was carried out in three of the most commonly used fibroblast reporter transgenic mice (Pdgfra-CreERT2, Col1a1-CreERT2 and PostnMCM) under healthy and ischemic conditions, to determine their suitability in in vivo studies of cardiac fibrosis. We demonstrate optimal Cre recombinase activity in CF (but also, although moderate, in endothelial cells (ECs)) derived from healthy and infarcted hearts in the PDGFRa-creERT2 mouse strain. In contrast, no positive reporter signal was found in CF derived from the Col1a1-CreERT2 mice. Finally, in the PostnMCM line, fluorescent reporter expression was specifically detected in activated CF but not in EC, which leads us to conclude that it may be the most reliable model for future studies on cardiovascular disease. Importantly, no lethality or cardiac fibrosis were induced after tamoxifen administration at the established doses, either in healthy or infarcted mice of the three fibroblast reporter lineages. This study lays the groundwork for future efficient in vivo CF tracking and functional analyses.