Mice lacking DNA topoisomerase IIIβ develop to maturity but show a reduced mean lifespan

Targeted gene disruption in the murine TOP3β gene-encoding DNA topoisomerase IIIβ was carried out. In contrast to the embryonic lethality of mutant mice lacking DNA topoisomerase IIIα, top3β−/− nulls are viable and grow to maturity with no apparent defects. Mice lacking DNA topoisomerase IIIβ have a shorter life expectancy than their wild-type littermates, however. The mean lifespan of the top3β−/− mice is about 15 months, whereas that of their wild-type littermates is longer than 2 years. Mortality of the top3β−/− nulls appears to correlate with lesions in multiple organs, including hypertrophy of the spleen and submandibular lymph nodes, glomerulonephritis, and perivascular infiltrates in various organs. Because the DNA topoisomerase III isozymes are likely to interact with helicases of the RecQ family, enzymes that include the determinants of human Bloom, Werner, and Rothmund–Thomson syndromes, the shortened lifespan of top3β−/− mice points to the possibility that the DNA topoisomerase III isozymes might be involved in the pathogenesis of progeroid syndromes caused by defective RecQ helicases.

Adenine phosphoribosyltransferase-deficient mice develop 2,8-dihydroxyadenine nephrolithiasis.

Adenine phosphoribosyltransferase (APRT) deficiency in humans is an autosomal recessive syndrome characterized by the urinary excretion of adenine and the highly insoluble compound 2,8-dihydroxyadenine (DHA) that can produce kidney stones or renal failure. Targeted homologous recombination in embryonic stem cells was used to produce mice that lack APRT. Mice homozygous for a null Aprt allele excrete adenine and DHA crystals in the urine. Renal histopathology showed extensive tubular dilation, inflammation, necrosis, and fibrosis that varied in severity between different mouse backgrounds. Thus, biochemical and histological changes in these mice mimic the human disease and provide a suitable model of human hereditary nephrolithiasis.

Transgenic mice carrying a human mutant superoxide dismutase transgene develop neuronal cytoskeletal pathology resembling human amyotrophic lateral sclerosis lesions.

Mutations in the human Cu,Zn superoxide dismutase gene (SOD1) are found in 20% of kindreds with familial amyotrophic lateral sclerosis. Transgenic mice (line G1H) expressing a human SOD1 containing a mutation of Gly-93 --> Ala (G93A) develop a motor neuron disease similar to familial amyotrophic lateral sclerosis, but transgenic mice (line N1029) expressing a wild-type human SOD1 transgene do not. Because neurofilament (NF)-rich inclusions in spinal motor neurons are characteristic of amyotrophic lateral sclerosis, we asked whether mutant G1H and/or N1029 mice develop similar NF lesions. NF inclusions (i.e., spheroids, Lewy body-like inclusions) were first detected in spinal cord motor neurons of the G1H mice at 82 days of age about the time these mice first showed clinical evidence of disease. Other neuronal intermediate filament proteins (alpha-internexin, peripherin) also accumulated in these spheroids. The onset of accumulations of ubiquitin immunoreactivity in the G1H mice paralleled the emergence of vacuoles and NF-rich spheroids in neurons, but they did not colocalize exclusively with spheroids. In contrast, NF inclusions were not seen in the N1029 mice until they were 132 days old, and ubiquitin immunoreactivity was not increased in the N1029 mice even at 199 days of age. Astrocytosis in spinal cord was associated with a marked increase in glial fibrillary acidic protein immunoreactivity in the G1H mice, but not in the N1029 mice. Finally, comparative studies revealed a striking similarity between the cytoskeletal pathology in the G1H transgenic mice and in patients with amyotrophic lateral sclerosis. These findings link a specific SOD1 mutation with alterations in the neuronal cytoskeleton of patients with amyotrophic lateral sclerosis. Thus, neuronal cytoskeletal abnormalities may be implicated in the pathogenesis of human familial amyotrophic lateral sclerosis.

beta2 knockout mice develop parenchymal iron overload: A putative role for class I genes of the major histocompatibility complex in iron metabolism.

Hemochromatosis (HC) is an inherited disorder of iron absorption, mapping within the human major histocompatibility complex (MHC). We have identified a multigene system in the murine MHC that contains excellent candidates for the murine equivalent of the human HC locus and implicate nonclassical class I genes in the control of iron absorption. This gene system is characterized by multiple copies of two head-to-head genes encoded on opposite strands and driven by one common regulatory motif. This regulatory motif has a striking homology to the promoter region of the beta-globin gene, a gene obviously involved in iron metabolism and hence termed beta-globin analogous promoter (betaGAP). Upstream of the betaGAP sequence are nonclassical class I genes. At least one of these nonclassical class I genes, Q2, is expressed in the gastrointestinal tract, the primary site of iron absorption. Also expressed in the gastrointestinal tract and downstream of the betaGAP motif is a second set of putative genes, termed Hephaestus (HEPH). Based on these observations, we hypothesized that the genes that seem to be controlled by the betaGAP regulatory motifs would be responsible for the control of Fe absorption. As a test of this hypothesis, we predicted that mice which have altered expression of class I gene products, the beta2-microglobulin knockout mice, [beta2m(-/-)], would develop Fe overload. This prediction was confirmed, and these results indicate beta2m-associated proteins are involved in the control of intestinal Fe absorption.

Cyp1a2(-/-) null mutant mice develop normally but show deficient drug metabolism.

Cytochrome P450 1A2 (CYP1A2) is a predominantly hepatic enzyme known to be important in the metabolism of numerous foreign chemicals of pharmacologic, toxicologic, and carcinogenic significance. CYP1A2 substrates include aflatoxin B1, acetaminophen, and a variety of environmental arylamines. To define better the developmental and metabolic functions of this enzyme, we developed a CYP1A2-deficient mouse line by homologous recombination in embryonic stem cells. Mice homozygous for the targeted Cyp1a2 gene, designated Cyp1a2(-/-), are completely viable and fertile; histologic examination of 15-day embryos, newborn pups, and 3-week-old mice revealed no abnormalities. No CYP1A2 mRNA was detected by Northern blot analysis. Moreover, mRNA levels of Cyp1a1, the other gene in the same subfamily, appear unaffected by loss of the Cyp1a2 gene. Because the muscle relaxant zoxazolamine is a known substrate for CYP1A2, we studied the Cyp1a2(-/-) genotype by using the zoxazolamine paralysis test: the Cyp1a2(-/-) mice exhibited dramatically lengthened paralysis times relative to the Cyp1a2(+/+) wild-type animals, and the Cyp1a2(+/-) heterozygotes showed an intermediate effect. Availability of a viable and fertile CYP1A2-deficient mouse line will provide a valuable tool for researchers wishing to define the precise role of CYP1A2 in numerous metabolic and pharmacokinetic processes.

Mice develop normally without the H1(0) linker histone.

H1 histones bind to the linker DNA between nucleosome core particles and facilitate the folding of chromatin into a 30-nm fiber. Mice contain at least seven nonallelic subtypes of H1, including the somatic variants H1a through H1e, the testis-specific variant H1t, and the replacement linker histone H1(0). H1(0) accumulates in terminally differentiating cells from many lineages, at about the time when the cells cease dividing. To investigate the role of H1(0) in development, we have disrupted the single-copy H1(0) gene by homologous recombination in mouse embryonic stem cells. Mice homozygous for the mutation and completely lacking H1(0) mRNA and protein grew and reproduced normally and exhibited no anatomic or histologic abnormalities. Examination of tissues in which H1(0) is normally present at high levels also failed to reveal any abnormality in cell division patterns. Chromatin from H1(0)-deficient animals showed no significant change in the relative proportions of the other H1 subtypes or in the stoichiometry between linker histones and nucleosomes, suggesting that the other H1 histones can compensate for the deficiency in H1(0) by occupying sites that normally contain H1(0). Our results indicate that despite the unique properties and expression pattern of H1(0), its function is dispensable for normal mouse development.

Development of the DORI-TBI: An Investigation to Develop a New Screening Measure to Determine Consultation with a School-Based Brain Injury Resource Team

Brain injury is the leading cause of disability and death in children in the United States. Student re-entry into the school setting following a traumatic brain injury is crucial to student success. Multidisciplinary teams within the school district comprised of individuals with expertise in brain injury are ideal in implementing student specific treatment plans given their specialized training and wide range of expertise addressing student needs. Therefore, the purpose of this study is to develop and initially validate a quantitative instrument that school personnel can use to determine if a student, identified as having a traumatic brain injury, will benefit from district-level consultation from a brain injury team. Three studies were designed to investigate the research questions. In study one, the planning and construction of the DORI-TBI was completed. Study two addressed the content validity of the DORI-TBI through a comparison analysis with other referral forms, content review with experts in the field of TBI, and cognitive interviews with professionals to test the usability of the new screening tool. In study three, a field administration was conducted using vignettes to measure construct validity. Results produced a valid and reliable new screening instrument that can aid school-based teams to more efficiently utilize district level consultation with a brain injury support team.

A proposal for teaching with authentic texts in order to develop social awareness in a language subject in tertiary education

The University of the 21st century has to establish links with society and prepare students for the demands of the working world. Therefore, this article is a contribution to the integral preparation of university students by proposing the use of authentic texts with social content in English lessons so that students acquire emotional and social competencies while still learning content. This article will explain how the choice of texts on global issues such as racism and gender helps students to develop skills such as social awareness and critical thinking to deepen their understanding of discrimination, injustice or gender differences in both oral and written activities. A proposal will be presented which involves using the inauguration speech from Mandela's presidency and texts with photographs of women so that students analyse them whilst utilising linguistic tools that allow them to explore a text's social dimension.

Exploring the use of cooperative activities in a language subject to develop students’ social competences at the University

Cooperative learning has been successfully implemented in the last 60 years for teaching at different educational levels including the Higher Studies due to its solid theoretical foundation, the principles it proposes and its practical applications. The purpose of this article is to offer a proposal for some cooperative activities that allow students to work in small groups in a language subject in order to learn not only contents but also putting into practice what they learn, i.e., they learn by being active. This article discusses how the said activities make it possible for students to work with the main principles of cooperative learning, i.e.: positive interdependence, face-to-face interaction, individual and group accountability, interpersonal and small-group skills and group processing. Moreover, this research will also point out that the proposed activities allow students to acquire some of the social competences required in the labour market such as leadership, conflict solving and cooperation.

HELPING YOUTH WITH AUTISM SPECTRUM DISORDER DEVELOP SOCIAL COMPETENCE IN COMMUNITY-BASED SETTINGS

The purpose of the current dissertation is to identify the features of effective interventions by exploring the experiences of youth with ASD who participate in such interventions, through two intervention studies (Studies 1 and 2) and one interview study (Study 3). Studies 1 and 2 were designed to support the development of social competence of youth with ASD through Structured Play with LEGO TM (Study 1, 12 youths with ASD, ages 7–12) and Minecraft TM (Study 2, 4 youths with ASD, ages 11–13). Over the course of the sessions, the play of the youth developed from parallel play (children playing alone, without interacting) to co-operative play (playing together with shared objectives). The results of Study 2 showed that rates of initiations and levels of engagement increased from the first session to the final session. In Study 3, 12 youths with ASD (ages 10–14) and at least one of their parents were interviewed to explore what children and their parents want from programs designed to improve social competence, which activities and practices were perceived to promote social competence by the participants, and which factors affected their decisions regarding these programs. The adolescents and parents looked for programs that supported social development and emotional wellbeing, but did not always have access to the programs they would have preferred, with factors such as cost and location reducing their options. Three overarching themes emerged through analysis of the three studies: (a) interests of the youth; (b) structure, both through interactions and instruction; and (c) naturalistic settings. Adolescents generally engage more willingly in interventions that incorporate their interests, such as play with Minecraft TM in Study 2. Additionally, Structured Play and structured instruction were crucial components of providing safe and supportive contexts for the development of social competence. Finally, skills learned in naturalistic settings tend to be applied more successfully in everyday situations. The themes are analysed through the lens of Vygotsky’s (1978) perspectives on learning, play, and development. Implications of the results for practitioners and researchers are discussed.

Accords d’association = Association Agreements [to develop relations with a third state]. Research Papers in Law, 1/2004

No abstract.