Morphological abnormalities, neonatal mortality, and reproductive abnormalities in mice transgenic for diphtheria toxin genes that are driven by the promoter for adipocyte lipid binding protein

Abstract

Transgenic mice were used in an experiment that was designed to serve as a model of a possible approach to reducing the amount of carcass fat in meat animals. The objective was to reduce the number of adipocytes in transgenic mice thereby restricting the capacity to accumulate lipid. Our approach employed the technique of genetic ablation. The promoter for the adipocyte lipid binding protein gene was used in an attempt to direct expression of diphtheria toxin genes specifically to adipocytes. Three diphtheria toxin genes were used; they encode, respectively, an extremely cytotoxic wild type toxin, a less toxic attenuated toxin, and a nonfunctional toxin. While it was not possible to accurately assess effects of the transgenes on lipid accumulation, several informative observations were noted. A large percentage of transgenic founder mice that harbor either wild type or attenuated toxin genes are morphologically abnormal, die as neonates, or exhibit reproductive abnormalities including sterility or failure to transmit the transgene to offspring. In contrast, mice that harbor the nonfunctional toxin gene or are nontransgenic rarely have these same abnormalities. These results suggest that the transgenic mice are expressing the transgenes in cells other than adipocytes and that the aberrant production of functional toxin is responsible for the congenital abnormalities. The production of morphological and reproductive abnormalities in transgenic animals should be useful for investigating normal developmental processes.

Attenuated sensitivity to neuroactive steroids in γ-aminobutyrate type A receptor delta subunit knockout mice

“…Total RNA was isolated from adult mouse brain by using Trizol reagent (Life Technologies, Grand Island, NY). Approximately 10 g of total RNA was electrophoresed in a 1.9% formaldehyde͞1% agarose gel, blotted to Hybond-N (Amersham Pharmacia) and hybridized as described (24). After the membrane was hydridized with probe D, it was rehybridized with a human ␤-actin cDNA probe (CLONTECH) as a control for RNA loading in each lane.…”

Evaluating Birth Frequencies and Embryonic Lethality in Transgenesis Following Pronuclear Injection of HIV DNA

“…Despite the use of very similar HIV DNA sequences, low SI values with the hope of deriving founders at an acceptably low frequency (and perhaps expression), or to alter the transgene construct to reduce the likelihood of toxicity after the analysis of 2-3 days of injections. A lethal effect may be overcome by using alternative pro moters to restrict the expression of a deleterious gene product [11]. These considerations should be particularly helpful for investigators developing animal models of dis ease and studying embryogenesis.…”

Targeted modification of the apolipoprotein B gene results in hypobetalipoproteinemia and developmental abnormalities in mice.

“…Total RNA was prepared, electrophoresed, transferred to Hybond-N (Amersham), and hybridized as described (21). Probes used include probes A, B, C (see Fig.…”