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L E Mobraaten

Publications and source records attributed to L E Mobraaten.

At least 19 recordsLinked to original sources
PubMed2001

Availability and characterization of transgenic and knockout mice with behavioral manifestations: where to look and what to search for.

Mice altered by transgenesis or gene targeting ("knockouts") have increasingly been employed as alternative effective tools in elucidating the genetic basis of neurophysiology and behavior. Standardization of specific behavioral paradigms and phenotyping strategies will ensure that these behavioral mouse mutants offer robust models for evaluating the efficacy of novel therapeutics in the treatment of hereditary neurological disorders. The Induced Mutant Resource (IMR) at The Jackson Laboratory (Bar Harbor, Maine, USA) imports, cryopreserves, develops, maintains, and distributes to the research community biomedically valuable stocks of transgenic and targeted mutant mice. Information on behavioral and neurological strains-including a phenotypic synopsis, husbandry requirements, strain availability, and genetic typing protocols-is available through the IMR database (http://www.jax.org/resources/documents/imr/). A current catalog of available strains is readily accessible via the JAX Mice Web site at http://jaxmice.jax.org/index.shtml. In addition, The Jackson Laboratory is now home to TBASE (http://tbase.jax.org/), a comprehensive, community database whose primary focus is on mouse knockouts. TBASE accommodates an exhaustive bibliographical resource for transgenic and knockout mice and provides a detailed phenotypic characterization of numerous behavioral knockouts that is primarily extracted from the literature. Concerted efforts to merge the two resources into a new, schematically reformed database are underway.

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PubMed2001

Effects of ectopias and their cortical location on several measures of learning in BXSB mice.

About half of BXSB/MpJ-Yaa mice have ectopias, which are misplaced clusters of neurons located in layer I of cortex. This study replicated several previous findings showing that there are learning differences between mice with ectopias and those without. In addition, we had sufficient numbers of ectopic mice to investigate if ectopics learned differently depending on the cortical location of the ectopia(s). Mice with at least one ectopia located in prefrontal cortex were initially impaired in learning the Morris maze, as well as relearning the Lashley maze when it was inverted, but learned better in the radial-arm maze when compared to ectopic mice with ectopias located in nonprefrontal regions of cortex. Mice with at least one ectopia in motor cortex learned the Lashley maze better than mice with ectopias located outside motor cortex. In sum, the cortical location of the ectopia(s) affected learning performance in certain tasks within the ectopic group, but regardless of the cortical location of the ectopia(s), ectopics still learned differently than nonectopics in several tasks.

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PubMed2001

Effects of the uterine environment and neocortical ectopias upon behavior of BXSB-Yaa+ mice.

Between 40-60% of BXSB-Yaa+mice have neocortical ectopias, a genetically based brain anomaly. The presence of ectopias is known to affect several cognitive measures. A second way to affect cognition is by transferring embryos into foreign uteri. These variables were jointly investigated in three experiments. BXSB-Yaa+mouse embryos were transferred into same-strain uteri, or into uteri of hybrid mice. At birth, pups were cross-fostered to hybrid mothers or were reared by their birth mothers. When adult, the mice were given a series of behavioral tests with primary emphasis upon cognitive competence. Across all three studies, mice transferred into hybrid uteri were superior in the Morris maze and the Lashley III maze, and performed more effectively in shuttlebox avoidance learning. They were less effective in the simple water escape task, and the uterus groups did not differ in discrimination learning. Thus, development within a foreign uterus enhanced spatial learning and fear-based conditioning. Ectopic mice were superior to non-ectopics in learning the Morris maze, a finding consistent with prior research using the congenic BXSB-Yaa strain. There were Uterus x Ectopia interactions on a few measures, indicating that, under certain condition, whether the presence of ectopias is beneficial or detrimental is contingent upon the uterine environment within which the organism develops.

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PubMed2001

Comparison of permeating and nonpermeating cryoprotectants for mouse sperm cryopreservation.

Mouse sperm has proven to be more difficult to cryopreserve than sperm of other mammalian species. Published reports show that only three cryoprotectant agents (CPAs), alone or combined, have been studied: glycerol and dimethyl sulfoxide (DMSO), as permeating agents, and raffinose, as a nonpermeating agent. To date, the most consistent results for mouse sperm cryopreservation have been achieved by use of raffinose/skim milk as cryoprotectant with rapid cooling at 20 degrees C per minute. In this study, we compared the cryoprotection provided by permeating (glycerol, formamide, propanediol, DMSO, adonitol) or nonpermeating (lactose, raffinose, sucrose, trehalose, d-mannitol) compounds for freezing mouse sperm. Different solutions were made using 3% skim milk solution as the buffer or extender in which all different cryoprotectant agents were dissolved at a concentration of 0.3 M, with a final osmolality of approx. 400 mOsm. Sperm samples from CB6F1 (hybrid) and C57BL/6J (inbred) mice collected directly into each CPA were frozen/thawed under identical conditions. After thawing and CPA elimination (centrifugation) raffinose (59%), trehalose (61%), and sucrose (61%) sustained the best motility (P = < 0.1) of the nonpermeating agents, whereas the best of the permeating agents was DMSO (42%). Membrane integrity was analyzed and showed that the simple exposure (prefreeze) to sugars was less harmful than the exposure to glycols. Coincidentally, sperm frozen in trehalose (41%), raffinose (40.5%), and sucrose (37.5%) were the samples less injured among all different postthawed CPA tested. The in vitro fertilization results demonstrated that hybrid mouse spermatozoa frozen with sugars (lactose 80%, raffinose 80%, trehalose 79% of two-cell embryos production) were more fertile than those frozen with glycols (glycerol 11%).

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PubMed2001

Transgenic and knockout databases: behavioral profiles of mouse mutants.

Genetically engineered strains of mice, modified by transgenesis or gene targeting ("knockouts") are being generated at an impressive rate and used, among other areas, as premiere research tools in deciphering the genetic basis of behavior. As behavioral phenotyping strategies continue to evolve, characterization of these "designer" mice will provide models to evaluate the efficacy of new pharmacological and gene therapy treatments in human hereditary diseases. Reported behavioral profiles include aberrant social, reproductive, and parental behaviors, learning and memory deficits, feeding disorders, aggression, anxiety-related behaviors, pain/analgesia, and altered responses to antidepressants, antipsychotics, ethanol, and psychostimulant drugs of abuse. The Induced Mutant Resource (IMR) at The Jackson Laboratory (TJL, Bar Harbor, ME, USA) imports, cryopreserves, develops, maintains, and distributes biomedically important stocks of transgenic and targeted mutant mice to the research community. Information on neurological/behavioral strains--including behavioral performance, husbandry requirements, strain availability, and genetic typing protocols--is provided through the IMR database (http://www.jax.org/resources/documents/imr/). A catalog of available strains is readily accessible via the JAX Mice website at http://jaxmice.jax.org/index.shtml. In addition, TJL is now host to TBASE (http://tbase.jax.org/), a comprehensive, public-domain database with primary emphasis on mouse knockouts. TBASE contains an exhaustive list of knockout-related citations and provides an extensive phenotypic characterization of numerous behavioral mutants that is extracted directly from the literature. Present efforts to merge the two resources into a novel, schematically enhanced database, provisionally named Transgenic and Targeted Mutation Database (TTMD), will be briefly discussed.

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PubMed2000

Rescue of oocytes from antral follicles of cryopreserved mouse ovaries: competence to undergo maturation, embryogenesis, and development to term.

Only primordial and primary follicles of frozen-thawed mouse ovaries survive after grafting to the ovarian bursa; large secondary follicles and antral follicles together with the oocytes contained in them degenerate. This study was undertaken to determine whether fully grown oocytes isolated from the antral follicles of frozen-thawed mouse ovaries are viable and can be rescued to undergo maturation, fertilization, and embryo development in vitro. Ovaries were cryopreserved after removal from 22-day-old (C57BL/6J x SJL/J)F(1) mice, with or without prior priming with equine chorionic gonadotrophin, and fresh non-frozen ovaries were used as controls. Only cumulus cell-denuded oocytes were recovered from frozen unprimed ovaries while both cumulus cell-enclosed and denuded oocytes were retrieved from frozen primed ovaries. Oocytes from both groups of frozen-thawed ovaries were able to undergo maturation, fertilization, and development to the blastocyst stage in vitro, though at lower percentages than oocytes from control unfrozen ovaries. Moreover, 19% of 2-cell stage embryos derived from frozen-thawed primed ovaries, compared with 42% of embryos derived from control primed ovaries, developed to term after transfer to pseudopregnant foster mothers (not significantly different). Therefore, fully grown oocytes in antral follicles survive the cryopreservation protocol, as demonstrated by maturation, fertilization and embryo development in vitro, and development to term after embryo transfer.

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PubMed2000

Cryopreservation of murine spermatozoa.

Cryopreservation of mouse sperm provides an economic option for preserving the large number of mouse strains now being generated by transgenic and targeted mutation methodologies. The ability of a spermatozoan cell to survive cryobiological preservation depends on general biophysical constraints that apply to all cells, such as the avoidance or minimization of the formation of intracellular ice during cooling. This action is typically achieved by use of cryoprotectant substances and by controlled, slow rates of cooling. Superimposed on those general constraints may be special characteristics of mouse spermatozoa, such as more narrow, osmotically driven volume tolerance limits and the fact that relatively successful freezing can be obtained without the use of a permeating cryoprotective agent. The lack of important information regarding sperm cells fundamental cryobiological properties, including their osmotic and membrane permeability characteristics, has hindered progress in developing anything but empirically derived methods. Genetic differences between inbred mouse strains are reflected in motility and fertility characteristics of mouse sperm and contribute to the difficulty of developing successful cryopreservation methods. Recovery of live young from frozen sperm has been much more successful with sperm from hybrid mice than from most inbred strains. There have been no published reports of successful cryopreservation of rat sperm. Nevertheless, in mice, success in deriving live young from intracytoplasmic sperm injection using sperm frozen under suboptimal conditions raises the possibility of using this technique for the ultimate rescue of sperm regardless of the success of cryopreservation. This technique, however, requires additional development and verification of its efficacy before it will be suitable for general laboratory use. Although cryopreservation of mouse sperm is not yet universally successful, it can be used reliably to supplement cryopreservation of embryos and other germline cells or tissues for preserving biomedically important strains of mice for research.

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PubMed2000

In vitro fertilization with cryopreserved inbred mouse sperm.

Sperm from C57BL/6J, DBA/2J, BALB/cJ, 129S3/SvImJ, and FVB/NJ inbred mice were cryopreserved in 3% skim milk/18% raffinose cryoprotectant solution. The post-thaw sperm from all strains were evaluated for their viability and fertility by comparing them against B6D2F1 sperm used as a control. The protocol used for freezing mouse sperm was effective in different strains, because the motility was decreased by 50% after cryopreservation similar to other mammalian sperm. However, the progressive motility and the fertility of each inbred strain were affected differently. The C57BL/6J, BALB/cJ, and 129S3/SvImJ strains were the most affected; their fertility (two-cell cleavage) decreased from 70%, 34%, and 84% when using freshly collected sperm to 6%, 12%, and 6% when using frozen/thawed sperm, respectively. Live newborns derived from frozen/thawed sperm were obtained from all strains in the study. These results corroborate the genetic variation among strains with regard to fertility and susceptibility to cryopreservation.

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PubMed1998

The uterine environment enhances cognitive competence.

Genetically identical mouse embryos were transferred into same-strain uteri (transfer controls) or into hybrid uteri. A third group was not transferred. When adult, the mice were given a series of behavioral tests. In-strain transfer controls differed from non-transfer mice only on two activity measures, and did not differ on any cognitive variable. In contrast, mice reared in hybrid uteri were found to be superior to in-strain transfer mice on discrimination learning. Lashley maze learning and Morris maze learning; they also showed better adaptation in an avoidance learning shuttlebox. To our knowledge this is the first study showing that the uterine environment can have a general enhancing effect upon cognitive competence across a broad range of behaviors.

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PubMed1998

The uterine environment enhances cognitive competence.

Genetically identical mouse embryos were transferred into same-strain uteri (transfer controls) or into hybrid uteri. A third group was not transferred. When adult, the mice were given a series of behavioral tests. In-strain transfer controls differed from non-transfer mice only on two activity measures, and did not differ on any cognitive variable. In contrast, mice reared in hybrid uteri were found to be superior to in-strain transfer mice on discrimination learning, Lashley maze learning and Morris maze learning; they also showed better adaptation in an avoidance learning shuttlebox. To our knowledge this is the first study showing that the uterine environment can have a general enhancing effect upon cognitive competence across a broad range of behaviors.

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PubMed1997

Motility of cryopreserved mouse spermatozoa affected by temperature of collection and rate of thawing.

In an attempt to optimize a method of cryopreserving spermazoa from mice bearing mutations, we investigated the effect on motility of temperature for the collection of mouse sperm and the rate of thawing after freezing. Comparison among samples of sperm collected from both the caudae epididymides and vas deferens placed directly in a cryoprotectant of 3% skim milk and 18% raffinose equilibrated at 37, 23, and 3 degrees C showed no difference in the number of viable sperm harvested. Concentration and motility was highest after collection at 37 degrees C (22.3 x 10(6) sperm/ml with 80% motility) combined with rapid thawing at 37 degrees C (2.9 x 10(6) sperm/ml with 84% motility in the swim-up fraction). The fertilization capacity of sperm collected and thawed at 37 degrees C was analyzed in vitro and no difference was observed between the cryopreserved sperm and the control (91 and 89%, respectively). Transfer of in vitro fertilized embryos to pseudopregnant recipients resulted in 37% implantation at Day 10 of pregnancy and 38% live births at term.

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PubMed1997

Genetic variation among 129 substrains and its importance for targeted mutagenesis in mice.

Targeted mutagenesis in mice, a powerful tool for the analysis of gene function and human disease, makes extensive use of 129 mouse substrains. Although all are named 129, we document that outcrossing of these substrains, both deliberate and accidental, has lead to extensive genetic variability among substrains and embryonic stem cells derived from them. This clearer understanding of 129 substrain variability allows consideration of its negative impact on targeting technology, including: homologous recombination frequencies, preparation of inbred animals, and availability of appropriate controls. Based on these considerations we suggest a number of recommendations for future experimental design.

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PubMed1997

Inter-strain graft-vs.-host disease T-cell responses to immunodominant minor histocompatibility antigens.

Immunodominance affects the in vitro generation of cytotoxic T lymphocytes (CTL) specific for minor histocompatibility antigens (miHA), as exemplified in the C57BL/6By (B6) anti-BALB.B H2b-matched strain combination. Despite the potential of responding to numerous individual miHA on BALB.B antigen presenting cells, the focus of the CTL response is largely directed to only a limited number of target antigens. These miHA are differentially expressed by the CXBE, CXBG, CXBI, CXBJ, and CXBK recombinant inbred (RI) strains, all of which also express the H2b MHC haplotype. Immunodominance also plays a role in the development of lethal graft-vs.-host disease (GVHD) directed to miHA, by which B6 T cells were transplanted along with T-cell depleted bone marrow to irradiated (825 cGy) recipients of either the BALB.B or CXB RI strains. The hierarchy of immunodominance differed in GVHD from that predicted from the in vitro CTL studies; i.e., GVHD was observed in BALB.B, CXBE, CXBI, and CXBJ recipients, but not in CXBG and CXBK recipients, despite the latter two strains expressing immunodominant antigens for CTL generation. Interpretation of these results was complicated by the finding that potent GVHD could be obtained with the transfer of CXBE T cells and ATBM to irradiated CXBG recipients. To clarify the scope of the inter-strain immunodominant interactions involved in GVHD in these strain combinations and to estimate the minimum number of miHA that could be responsible for GVHD, a full panel of GVHD responses was analyzed. The GVHD potential was evaluated for donor T cells derived from both parental RI strains as well as for (B6 x RI)F1 hybrids to restrict responses to only those miHA originating from BALB.B origin. The results were consistent with the minimal involvement of two distinct immunodominant miHA in the B6-->BALB.B lethal GVHD response. One immunodominant miHA (GVH-1) appeared to be shared by the CXBE, CXBI, and CXBJ RI strains, while the second antigen (GVH-2) was uniquely expressed by the parental BALB.B strain.

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PubMed1996

Effects of embryo transfer and cortical ectopias upon the behavior of BXSB-Yaa and BXSB-Yaa + mice.

The BXSB-Yaa and BXSB-Yaa + inbred strains of mice differ primarily with respect to the Y chromosome, although there is evidence that they differ on several autosomal genes as well. Each strain has ectopic collections of neurons in neocortical layer I (ectopias), with a higher occurrence in males (58%) than females (42%). Conventionally reared mice from these strains were compared to mice that were transferred, as 8-cell embryos, into the uteri of non-autoimmune recipients, who gave birth to and reared the offspring. The transfer procedure did not change the incidence of ectopias in either sex. There were, however, major differences in behavior. Compared to conventionally reared controls, embryo transfer mice had greater behavioral asymmetry, poorer performance in a black-white discrimination, poorer Morris maze learning, better Lashley maze learning, and better performance in a two-way shuttlebox. Within the transfer groups, females differed as much as males, confirming our prior findings and supporting our thesis that the two strains differ on several autosomal genes in addition to the Y chromosome. These findings show that the intra-uterine environment can powerfully and selectively affect later behavior. When ectopic and non-ectopic mice were compared, BXSB-Yaa mice with neocortical ectopias were better able to learn the Morris spatial maze than non-ectopic controls; this was true whether the mice were conventionally reared or embryo transferred. In contrast, BXSB-Yaa + ectopic mice did not differ from their controls if conventionally reared, but were much worse than controls if embryo transferred.

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PubMed1993

The functional basis of minor histocompatibility loci.

This work addresses the functional basis of classical minor histocompatibility (H) loci. We focus on the H-3 locus, which is actually a complex genetic unit to which the phenotypic trait of tissue rejection, genes whose products stimulate specific subsets of T cells, and Ir genes have been mapped. To clarify how these genes relate to one another and to the trait of tissue rejection, strains of intra-H-3 recombinant mice were produced and analyzed. These mice allowed us to selectively elicit immune responses to Ag (referred to as type I Ag) that stimulate MHC class I-restricted CTL, or Ag (referred to as type II Ag) that stimulate MHC class II-restricted Th. The splitting of H-3 in this manner resulted in a dramatic diminution of the skin allograft response, and with rare exception, an elimination of the CTL response after spleen cell immunization. A selective response to type I Ag resulted in slow, incomplete skin allograft rejection that demonstrated both CD4+ cell-dependent and -independent components. A selective response to the type II Ag failed to result in allograft rejection. The type II Ag did, however, act as an Ir gene that determined whether responses to type I Ag could occur. Altogether, the results indicate that the trait of tissue rejection associated with H-3 is a consequence of the strongly synergistic effects of Th-CTL collaboration induced by products of type I and type II genes. Moreover, the results suggest a genetic explanation for some of the Ir gene effects associated with H-3.

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