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Experimental analysis of two mice cell lines, uncoupling protein-diphtheria toxin A-chain (UCP-DTA) and attenuated mutant UCP-176, using immunoblotting techniques and UCP antisera, elucidated the correlation between brown adipose tissue (BAT) ablation and development of obesity in mice with genetically ablated BAT. BAT, which is a center of activity during thermogenesis, controls energy balance in mice and potentiates uncoupled mitochondrial respiration. Brown fat deficiency in mice leads to enhanced metabolic activity and is characterized by progressive obesity in the absence of hyperphagia.

Zhang, Xiaomin, Gohar Azhar, Jianyuan Chai, Pamela Sheridan, Koichiro Nagano, Thomas Brown, Jihong Yang, Konstantin Khrapko, Ana M. Borras, Joel Lawitts, Ravi P. Misra, and Jeanne Y. Wei. Cardiomyopathy in transgenic mice with cardiac-specific overexpression of serum response factor. Am J Physiol Heart Circ Physiol 280: H1782-H1792, 2001.--Serum response factor (SRF), a member of the MCM1, agamous, deficiens, SRF (MADS) family of transcriptional activators, has been implicated in the transcriptional control of a number of cardiac muscle genes, including cardiac [Alpha]-actin, skeletal [Alpha]-actin, [Alpha]-myosin heavy chain ([Alpha]-MHC), and [Beta]-MHC. To better understand the in vivo role of SRF in regulating genes responsible for maintenance of cardiac function, we sought to test the hypothesis that increased cardiac-specific SRF expression might be associated with altered cardiac morphology and function. We generated transgenic mice with cardiac-specific overexpression of the human SRF gene. The transgenic mice developed cardiomyopathy and exhibited increased heart weight-to-body weight ratio, increased heart weight, and four-chamber dilation. Histological examination revealed cardiomyocyte hypertrophy, collagen deposition, and interstitial fibrosis. SRF overexpression altered the expression of SRF-regulated genes and resulted in cardiac muscle dysfunction. Our results demonstrate that sustained overexpression of SRF, in the absence of other stimuli, is sufficient to induce cardiac change and suggest that SRF is likely to be one of the downstream effectors of the signaling pathways involved in mediating cardiac hypertrophy. muscle genes; hypertrophy; transcription; serum response element; signaling

With the fast advancement in the genetics and bio-medical fields, the vast number of valuable transgenic and rare genetic mouse models need to be preserved. Preservation of mouse sperm by convective drying and subsequent storing at above freezing temperatures could dramatically reduce the cost and facilitate shipping. Mouse sperm were convectively dried under nitrogen gas in the Na-EGTA solution containing 100 mmol/L 3-O-methyl-D-glucose and stored in LiCl sorption jars (Relative Humidity, RH, 12%) at 4°C and 22°C for up to one year. The functionality of these sperm samples after storage was tested by intracytoplasmic injection into mouse oocytes. The percentages of blastocysts produced from sperm stored at 4uC for 1, 2, 3, 6, and 12 months were 62.6%, 53.4%, 39.6%, 33.3%, and 30.4%, respectively, while those stored at 22uC for 1, 2, and 3 months were 28.8%, 26.6%, and 12.2%, respectively. Transfer of 38 two- to four-cell embryos from sperm stored at 4°C for 1 year produced two live pups while 59 two- to four-cell embryos from sperm stored at 22°C for 3 months also produced two live pups. Although all the pups looked healthy at 3 weeks of age, normality of offspring produced using convectively dried sperm needs further investigation. The percentages of blastocyst from sperm stored in the higher relative humidity conditions of NaBr and MgCl2 jars and driest condition of P2O5 jars at 4°C and 22°C were all lower. A simple method of mouse sperm preservation is demonstrated. Three-O-methyl-D-glucose, a metabolically inactive derivative of glucose, offers significant protection for dried mouse sperm at above freezing temperatures without the need for poration of cell membrane. [ABSTRACT FROM AUTHOR]

Studies cardiomyopathy in transgenic mice with cardiac-specific overexpression of serum response factor (SRF). Generation of SRF transgenic mice; Measurement of the alteration of gene expression of several cardiac genes; Development of cardiomyopathy.

Genetically altered mice are important research tools for the study of human development and disease. Occasionally, whether or not related to the genetic mutation, mice may become infertile with age and, thus, risk loss of the mutant line. Under conditions in which assisted reproduction techniques (ARTs), such as in vitro fertilization, are unsuccessful, a new strategy, intracytoplasmic sperm injection (ICSI), may be applicable. This technique has been perfected for use in the mouse and is now considered a reliable, effective, and efficient ART. In the study reported here, we "rescued" (i.e., produced offspring, using ICSI from a "last-of-line" mutant male mouse) four lines that otherwise had become infertile and unresponsive to conventional ART's. A total of 26 live pups were produced from eight pregnant recipient foster mothers. Five mutant male mice were derived (one each from three lines, and two from one line), and all survived to adulthood. We found that live born mice could be successfully derived by use of ICSI that subsequently could breed by natural mating to reestablish the mutant line. Because of its effectiveness and reliability under these conditions, ICSI should be considered a powerful addition to the armamentarium of ART's applicable in the genetically-altered mouse, especially when only one male may still be available.