Tissue expression pattern of class II and class V genes found in the Adh complex on mouse chromosome 3.

The alcohol dehydrogenase enzymes in mice and humans are encoded by a linked group of genes in the same transcriptional orientation. The enzymes play important roles in alcohol metabolism and retinoid signaling and homeostasis. The expression patterns at the mRNA level of the mouse Adh4 (class II) gene and the recently identified Adh6a and Adh6b genes (class V) are now reported to complete this analysis for the entire family. Adh4 is expressed at high levels in liver and is detectable in small intestine and testes. Adh6b is expressed in liver but Adh6a is not. Adh6a is expressed at high levels in small intestine while Adh6b is not. Adh6a expression is detectable in the female adrenal and not at all in the male adrenal, but Adh6b is expressed at moderate levels in both sexes. Although Adh6a and Adh6b have expression patterns different from each other, neither expresses like any other gene in the complex, suggesting different control mechanisms and possibly different functions.

Distal and proximal cis-linked sequences are needed for the total expression phenotype of the mouse alcohol dehydrogenase 1 (Adh1) gene.

Mouse alcohol dehydrogenase 1 (Adh1) gene expression occurs at high levels in liver and adrenal, moderate levels in kidney and intestine, low levels in a number of other tissues, and is undetectable in thymus, spleen and brain by Northern analysis. In transgenic mice, a minigene construct containing 10 kb of upstream and 1.5 kb of downstream flanking sequence directs expression in kidney, adrenal, lung, epididymis, ovary and skin but promotes ectopic expression in thymus and spleen while failing to control expression in liver, eye, intestine and seminal vesicle. Cosmids containing either 7 kb of upstream and 21 kb of downstream or 12 kb of upstream and 23 kb of downstream sequence flanking genetically marked Adh1 additionally promotes seminal vesicle expression suggesting downstream or intragenic sequence controls expression in this tissue. However, expression in liver, adrenal, or intestine is not promoted. The Adh1(a) allele on the cosmid expresses an enzyme electrophoretically distinct from that of the endogenous Adh1(b) allele, and presence of the heterodimeric enzyme in expressing tissues confirms that transgene activity occurs in the same cell-type as the endogenous gene. Transgene expression levels promoted by cosmids were at physiologically relevant amounts and exhibited greater copy-number dependence than observed with minigenes. Transgene mRNA expression correlated with expression measured at the enzyme level. A bacterial artificial chromosome containing 110 kb of 5'- and 104 kb of 3'-flanking sequence surrounding the Adh1 gene promoted expression in tissues at levels comparable to the endogenous gene most importantly including liver, adrenal and intestinal tissue where high level Adh1 expression occurs. Transgene expression in liver was in the same cell types as promoted by the endogenous gene. Although proximal elements extending 12 kb upstream and 23 kb downstream of the Adh1 gene promote expression at physiologically relevant levels in most tissues, more distal elements are additionally required to promote normal expression levels in liver, adrenal and intestinal tissue where Adh1 is most highly expressed.

Hematologic and serum biochemical values of 4 species of Peromyscus mice and their hybrids.

Deer mice (Peromyscus maniculatus) and congeneric species are used in a wide variety of research applications, particularly studies of developmental, physiologic, and behavioral characteristics associated with habitat adaptation and speciation. Because peromyscine mice readily adapt to colony conditions, animals with traits of interest in the field are moved easily into the laboratory where they can be studied under controlled conditions. The purpose of this study was to determine the serum chemistry and hematologic parameters of 4 frequently used species from the Peromyscus Genetic Stock Center species (P. californicus, P. leucopus, P. maniculatus, and P. polionotus) and to determine quantitative differences in these parameters among species and between sexes. Triglyceride values were substantially higher in female compared with male mice in all 4 species. Similar cross-species differences in MCH were present. Overall there was considerable interspecific variation for most blood parameters, with little evidence for covariation of any 2 or more parameters. Because crosses of P. maniculatus and P. polionotus produce fertile offspring, segregation analyses can be applied to determine the genetic basis of any traits that differ between them, such as their 3.8- and 2.1-fold interspecific differences in cholesterol and triglyceride levels, respectively. The current data provide a set of baseline values useful for subsequent comparative studies of species experiencing different circumstances, whether due to natural variation or anthropogenic environmental degradation. To enable such comparisons, the raw data are downloadable from a site maintained by the Stock Center (http://ww2.biol.sc.edu/∼peromyscus).

Peromyscus (deer mice) as developmental models.

Deer mice (Peromyscus) are the most common native North American mammals, and exhibit great natural genetic variation. Wild-derived stocks from a number of populations are available from the Peromyscus Genetic Stock Center (PGSC). The PGSC also houses a number of natural variants and mutants (many of which appear to differ from Mus). These include metabolic, coat-color/pattern, neurological, and other morphological variants/mutants. Nearly all these mutants are on a common genetic background, the Peromyscus maniculatus BW stock. Peromyscus are also superior behavior models in areas such as repetitive behavior and pair-bonding effects, as multiple species are monogamous. While Peromyscus development generally resembles that of Mus and Rattus, prenatal stages have not been as thoroughly studied, and there appear to be intriguing differences (e.g., longer time spent at the two-cell stage). Development is greatly perturbed in crosses between P. maniculatus (BW) and Peromyscus polionotus (PO). BW females crossed to PO males produce growth-restricted, but otherwise healthy, fertile offspring which allows for genetic analyses of the many traits that differ between these two species. PO females crossed to BW males produce overgrown but severely dysmorphic conceptuses that rarely survive to late gestation. There are likely many more uses for these animals as developmental models than we have described here. Peromyscus models can now be more fully exploited due to the emerging genetic (full linkage map), genomic (genomes of four stocks have been sequenced) and reproductive resources.

Improved technique for induction and monitoring of audiogenic seizure in deer mice.

Epilepsy is a debilitating disease characterized by recurring seizures. Epilepsy can be studied using animal models, such as rodents prone to audiogenic seizure (AGS), which experience generalized seizures (loss of consciousness accompanied by rhythmic muscle spasms and rigid muscle stiffness) after intense sound stimulation. In 1933, a spontaneous mutation resulting in sensitivity to AGS was observed among laboratory stocks of deer mice (Peromyscus maniculatus artemisiae) at the University of Michigan. Since then, AGS-sensitive deer mice have been maintained as a separate stock, currently housed at the Peromyscus Genetic Stock Center. To further characterize AGS, the authors designed reliable and consistent equipment for inducing and monitoring AGS in deer mice.

The biology and methodology of assisted reproduction in deer mice (Peromyscus maniculatus).

Although laboratory-reared species of the genus Peromyscus-including deer mice-are used as model animals in a wide range of research, routine manipulation of Peromyscus embryogenesis and reproduction has been lagging. The objective of the present study was to optimize conditions for oocyte and/or embryo retrieval and for in vitro culturing. On average, 6.4 oocytes per mouse were recovered when two doses of 15 IU of pregnant mare serum gonadotropin (PMSG) were given 24 h apart, followed by 15 IU of hCG 48 h later. Following this hormone priming, females mated overnight with a fertile male yielded an average of 9.1 two-cell stage embryos. Although two-cell stage embryos developed to 8-cell stage in Potassium Simplex Optimized Medium (KSOM; Millipore-Chemicon, Billerica, MA, USA) in vitro, but not further, embryos recovered at the 8- to 16-cell stages developed into fully expanded blastocysts when cultured in M16 media in vitro. These blastocysts had full potential to develop into late stage fetuses and possibly into live pups. As a result of the present work, all stages of Peromyscus preimplantation development are now obtainable in numbers sufficient for molecular or other analyses. These advances provide the opportunity for routine studies involving embryo transfer (e.g., chimeras, transgenics), and preservation of genetic lines by cryopreservation.

Biotransport phenomena in freezing mammalian oocytes.

Water transport across the cell plasma membrane and intracellular ice formation (IIF)-the two biophysical events that may cause cell injury during cryopreservation-were studied by cryomicroscopy and modeling using mammalian (Peromyscus) oocytes. Unusually high activation energy for water transport across the cell plasma membrane was identified indicating that the water transport process is unusually sensitive to temperature (and cooling rate). Although literally all studies on IIF were conducted using protocols with ice-seeding (seeding extracellular ice usually at ≥-7 °C), it is not used for cell cryopreservation by vitrification that is becoming increasingly popular today. In this article, we show that ice-seeding has a significant impact on IIF. With ice-seeding and cooling at 60 °C/min, IIF was observed to occur over a wide range from approximately -8 to -48 °C with a clear change of the ice nucleation mechanism (from surface- to volume-catalyzed nucleation) at approximately -43 °C. On the contrary, without ice-seeding, IIF occurred over a much narrower range from approximately -19 to -27 °C without a noticeable change of the nucleation mechanism. Moreover, the kinetics of IIF without ice-seeding was found to be strongly temperature (and cooling rate) dependent. These findings indicate the importance of quantifying the IIF kinetics in the absence of ice-seeding during cooling for development of optimal vitrification protocols of cell cryopreservation.

Longevity is associated with increased vascular resistance to high glucose-induced oxidative stress and inflammatory gene expression in Peromyscus leucopus.

Vascular aging is characterized by increased oxidative stress and proinflammatory phenotypic alterations. Metabolic stress, such as hyperglycemia in diabetes, is known to increase the production of ROS and promote inflammatory gene expression, accelerating vascular aging. The oxidative stress hypothesis of aging predicts that vascular cells of long-lived species exhibit lower steady-state production of ROS and/or superior resistance to the prooxidant effects of metabolic stress. We tested this hypothesis using two taxonomically related rodents, the white-footed mouse (Peromyscus leucopus) and the house mouse (Mus musculus), which show a more than twofold difference in maximum lifespan potential (8.2 and 3.5 yr, respectively). We compared interspecies differences in steady-state and high glucose (HG; 30 mmol/l)-induced production of O(2)(*-) and H(2)O(2), endothelial function, mitochondrial ROS generation, and inflammatory gene expression in cultured aortic segments. In P. leucopus aortas, steady-state endothelial O(2)(*-) and H(2)O(2) production and ROS generation by mitochondria were less than in M. musculus vessels. Furthermore, vessels of P. leucopus were more resistant to the prooxidant effects of HG. Primary fibroblasts from P. leucopus also exhibited less steady-state and HG-induced ROS production than M. musculus cells. In M. musculus arteries, HG elicited significant upregulation of inflammatory markers (TNF-alpha, IL-6, ICAM-1, VCAM, and monocyte chemoattractant protein-1). In contrast, the proinflammatory effects of HG were blunted in P. leucopus vessels. Thus, increased life span potential in P. leucopus is associated with decreased cellular ROS generation and increased resistance to prooxidant and proinflammatory effects of metabolic stress, which accord with predictions of the oxidative stress hypothesis of aging.