Comparison of Cesium-137 and X-ray Irradiators by Using Bone Marrow Transplant Reconstitution in C57BL/6J Mice.

Mice are used extensively in transplantation studies involving bone marrow ablation. Due to the increasing security issues and expenses involved with γ irradiators, self-contained X-ray irradiators have been increasing in popularity. We hypothesized that bone marrow ablation by irradiation of mice with a (137)Cs irradiator would be comparable to that from an X-ray source irradiator. A lethal-dose curve was obtained by irradiating C57BL/6J mice with 500, 700, 900, and 1100 cGy from either source. These data were used to determine the lethal radiation exposure range for a noncompetitive bone marrow engraftment curve for each source. At 90 d after reconstitution, the bone marrow engraftment curves revealed significant differences between the 2 sources in the establishment of B cell, myeloid, and T cell lineages. Murine B cell reconstitution after exposure to a (137)Cs source was greater than that after X-ray exposure at each dose level, whereas the converse was true for myeloid cell reconstitution. At the 1050- and 1100-cGy doses, mice irradiated by using the X-ray source demonstrated higher levels of T cell reconstitution but decreased survival compared with mice irradiated with the (137)Cs source. We concluded that although both sources ablated endogenous bone marrow sufficiently to enable stem cell engraftment, there are distinct physiologic responses that should be considered when choosing the optimal source for use in a study and that irradiation from the (137)Cs source was associated with lower overall morbidity due to opportunistic infection.

Tumor and reproductive traits are linked by RNA metabolism genes in the mouse ovary: a transcriptome-phenotype association analysis.

BACKGROUND: The link between reproductive life history and incidence of ovarian tumors is well known. Periods of reduced ovulations may confer protection against ovarian cancer. Using phenotypic data available for mouse, a possible association between the ovarian transcriptome, reproductive records and spontaneous ovarian tumor rates was investigated in four mouse inbred strains. NIA15k-DNA microarrays were employed to obtain expression profiles of BalbC, C57BL6, FVB and SWR adult ovaries. RESULTS: Linear regression analysis with multiple-test control (adjusted p ≤ 0.05) resulted in ovarian tumor frequency (OTF) and number of litters (NL) as the top-correlated among five tested phenotypes. Moreover, nearly one-hundred genes were coincident between these two traits and were decomposed in 76 OTF(-) NL(+) and 20 OTF(+) NL(-) genes, where the plus/minus signs indicate the direction of correlation. Enriched functional categories were RNA-binding/mRNA-processing and protein folding in the OTF(-) NL(+) and the OTF(+) NL(-) subsets, respectively. In contrast, no associations were detected between OTF and litter size (LS), the latter a measure of ovulation events in a single estrous cycle. CONCLUSION: Literature text-mining pointed to post-transcriptional control of ovarian processes including oocyte maturation, folliculogenesis and angiogenesis as possible causal relationships of observed tumor and reproductive phenotypes. We speculate that repetitive cycling instead of repetitive ovulations represent the actual link between ovarian tumorigenesis and reproductive records.

Identification of a ferrireductase required for efficient transferrin-dependent iron uptake in erythroid cells.

The reduction of iron is an essential step in the transferrin (Tf) cycle, which is the dominant pathway for iron uptake by red blood cell precursors. A deficiency in iron acquisition by red blood cells leads to hypochromic, microcytic anemia. Using a positional cloning strategy, we identified a gene, six-transmembrane epithelial antigen of the prostate 3 (Steap3), responsible for the iron deficiency anemia in the mouse mutant nm1054. Steap3 is expressed highly in hematopoietic tissues, colocalizes with the Tf cycle endosome and facilitates Tf-bound iron uptake. Steap3 shares homology with F(420)H(2):NADP(+) oxidoreductases found in archaea and bacteria, as well as with the yeast FRE family of metalloreductases. Overexpression of Steap3 stimulates the reduction of iron, and mice lacking Steap3 are deficient in erythroid ferrireductase activity. Taken together, these findings indicate that Steap3 is an endosomal ferrireductase required for efficient Tf-dependent iron uptake in erythroid cells.

nm1054: a spontaneous, recessive, hypochromic, microcytic anemia mutation in the mouse.

Hypochromic, microcytic anemias are typically the result of inadequate hemoglobin production because of globin defects or iron deficiency. Here, we describe the phenotypic characteristics and pathogenesis of a new recessive, hypochromic, microcytic anemia mouse mutant, nm1054. Although the mutation nm1054 is pleiotropic, also resulting in sparse hair, male infertility, failure to thrive, and hydrocephaly, the anemia is the focus of this study. Hematologic analysis reveals a moderately severe, congenital, hypochromic, microcytic anemia, with an elevated red cell zinc protoporphyrin, consistent with functional erythroid iron deficiency. However, serum and tissue iron analyses show that nm1054 animals are not systemically iron deficient. From hematopoietic stem cell transplantation and iron uptake studies in nm1054 reticulocytes, we provide evidence that the nm1054 anemia is due to an intrinsic hematopoietic defect resulting in inefficient transferrin-dependent iron uptake by erythroid precursors. Linkage studies demonstrate that nm1054 maps to a genetic locus not previously implicated in microcytic anemia or iron phenotypes.

Frozen sperm as an alternative to shipping live mice.

Dissemination of live mice by air and/or ground shipping is costly and can result in spread of disease between senders' and recipients' colonies. Transporting cryopreserved sperm that can be recovered and used for deriving live mice by using assisted reproductive techniques may be a more economical, efficient, and safer alternative to shipping live animals. In this study, we tested the hypothesis that sperm cryopreserved at one location and then transported transcontinentally via a common package delivery service using both air and ground transport to a second location could be recovered for in vitro fertilization (IVF) to successfully derive liveborn offspring at the second location. Split aliquots of sperm from individual mice were tested at both senders' and recipients' locations by using similar cryopreservation and IVF procedures, in order to control for differences in handling procedures. At both senders' locations, fertilization rates using cryopreserved sperm were lower than those using fresh sperm. However, fertilization rates using sperm recovered after cryopreservation at the senders' locations were not significantly different than those obtained when the same cryopreserved sperm was recovered and used at the recipients' locations. At the one location where tested, the numbers of pups born and subsequently weaned after IVF using either shipped or nonshipped cryopreserved sperm were similar. We conclude that cryopreserved sperm can be transported between different facilities and used for IVF to successfully derive liveborn mice.