[Show abstract][Hide abstract] ABSTRACT: We have used homozygous albumin enhancer/promoter-driven urokinase-type plasminogen activator/severe combined immunodeficient (uPA/SCID) mice as hosts for chimeric mice with humanized livers. However, uPA/SCID mice show four disadvantages: the human hepatocytes (h-heps) replacement index in mouse liver is decreased due to deletion of uPA transgene by homologous recombination, kidney disorders are likely to develop, body size is small, and hemizygotes cannot be used as hosts as more frequent homologous recombination than homozygotes. To solve these disadvantages, we have established a novel host strain that has a transgene containing albumin promoter/enhancer and urokinase-type plasminogen activator cDNA and has a SCID background (cDNA-uPA/SCID). We applied the embryonic stem cell technique to simultaneously generate a number of transgenic lines, and found the line with the most appropriate levels of uPA expression-not detrimental but with a sufficiently damaged liver. We transplanted h-heps into homozygous and hemizygous cDNA-uPA/SCID mice via the spleen, and monitored their human albumin (h-alb) levels and body weight. Blood h-alb levels and body weight gradually increased in the hemizygous cDNA-uPA/SCID mice and were maintained until they were approximately 30 weeks old. By contrast, blood h-alb levels and body weight in uPA/SCID chimeric mice decreased from 16 weeks of age onwards. A similar decrease in body weight was observed in the homozygous cDNA-uPA/SCID genotype, but h-alb levels were maintained until they were approximately 30 weeks old. Microarray analyses revealed identical h-heps gene expression profiles in homozygous and hemizygous cDNA-uPA/SCID mice were identical to that observed in the uPA/SCID mice. Furthermore, like uPA/SCID chimeric mice, homozygous and hemizygous cDNA-uPA/SCID chimeric mice were successfully infected with hepatitis B virus and C virus. These results indicate that hemizygous cDNA-uPA/SCID mice may be novel and useful hosts for producing chimeric mice for use in future long-term studies, including hepatitis virus infection analysis or drug toxicity studies.
[Show abstract][Hide abstract] ABSTRACT: Although excessive fructose intake is epidemiologically linked with dyslipidemia, obesity, and diabetes, the mechanisms regulating plasma fructose are not well known. Cells transfected with sodium/glucose cotransporter 5 (SGLT5), which is expressed exclusively in the kidney, transport fructose in vitro; however, the physiological role of this transporter in fructose metabolism remains unclear. To determine whether SGLT5 functions as a fructose transporter in vivo, we established a line of mice lacking the gene encoding SGLT5. Sodium-dependent fructose uptake disappeared in renal brush border membrane vesicles from SGLT5-deficient mice, and the increased urinary fructose in SGLT5-deficient mice indicated that SGLT5 was the major fructose reabsorption transporter in the kidney. From this, we hypothesized that urinary fructose excretion induced by SGLT5 deficiency would ameliorate fructose-induced hepatic steatosis. To test this hypothesis we compared SGLT5-deficient mice with wild-type mice under conditions of long-term fructose consumption. Paradoxically, however, fructose-induced hepatic steatosis was exacerbated in the SGLT5-deficient mice, and the massive urinary fructose excretion was accompanied by reduced levels of plasma triglycerides and epididymal fat but fasting hyperinsulinemia compared with fructose-fed wild-type mice. There was no difference in food consumption, water intake, or plasma fructose between the two types of mice. No compensatory effect by other transporters reportedly involved in fructose uptake in the liver and kidney were indicated at the mRNA level. These surprising findings indicated a previously unrecognized link through SGLT5 between renal fructose reabsorption and hepatic lipid metabolism.
[Show abstract][Hide abstract] ABSTRACT: For clinical trials of therapeutic monoclonal antibodies (mAbs) to be successful, their efficacy needs to be adequately evaluated in preclinical experiments. However, in many cases it is difficult to evaluate the candidate mAbs using animal disease models because of lower cross-reactivity to the orthologous target molecules. In this study we have established a novel humanized Castleman's disease mouse model, in which the endogenous interleukin-6 receptor gene is successfully replaced by human IL6R, and human IL6 is overexpressed. We have also demonstrated the therapeutic effects of an antibody that neutralizes human IL6R, tocilizumab, on the symptoms in this mouse model. Plasma levels of human soluble IL6R and human IL6 were elevated after 4-week treatment of tocilizumab in this mouse model similarly to the result previously reported in patients treated with tocilizumab. Our mouse model provides us with a novel means of evaluating the in vivo efficacy of human IL6R-specific therapeutic agents.
[Show abstract][Hide abstract] ABSTRACT: Aims Platelet aggregation at the injured surface of blood vessels plays a crucial role in arterial thrombosis. Platelet aggregation in plasma has been analyzed in the presence of calcium chelator to avoid coagulation. Here, we describe a novel mechanism of platelet aggregation that involves calcium-dependent binding between phosphatidylserine (PS) and lectin-like oxidized LDL receptor-1 (LOX-1), and contribution of platelet LOX-1 to arterial thrombosis. Methods and Results In vitro, LOX-1 gene deletion and anti-LOX-1 antibody suppressed the aggregation of platelets from mice and humans, respectively, in the absence of calcium chelating citrate, but not in the presence of citrate. LOX-1 blockade and annexin V, in parallel, suppressed platelet aggregation and shifted the population of aggregates from large to small in size. Simultaneous application of anti-LOX-1 antibody and annexin V did not exert additive suppressive effects on aggregation. On activation, platelets exposed LOX-1 and PS, and bound to PS-coated surface in LOX-1-dependent manner. In vivo, both LOX-1 deletion and anti-LOX-1 antibody significantly suppressed thrombus formation in mice and rats, respectively. Furthermore, platelet transfusion from LOX-1 knockout to wild-type mice still showed the suppressive effects of LOX-1 gene deletion, suggesting that platelet LOX-1 promoted thrombus formation. Conclusion LOX-1 blockade could be a novel approach to prevent platelet aggregation and thrombosis.
Full-text · Article · Aug 2010 · Cardiovascular Research
[Show abstract][Hide abstract] ABSTRACT: C-type natriuretic peptide (CNP) plays a critical role in endochondral ossification through guanylyl cyclase-B (GC-B), a natriuretic peptide receptor subtype. Cartilage-specific overexpression of CNP enhances skeletal growth and rescues the dwarfism in a transgenic achondroplasia model with constitutive active mutation of fibroblast growth factor receptor-3. For future clinical application, the efficacy of CNP administration on skeletal growth must be evaluated. Due to the high clearance of CNP, maintaining a high concentration is technically difficult. However, to model high blood CNP concentration, we established a liver-targeted CNP-overexpressing transgenic mouse (SAP-CNP tgm). SAP-CNP tgm exhibited skeletal overgrowth in proportion to the blood CNP concentration and revealed phenotypes of systemic stimulation of cartilage bones, including limbs, paws, costal bones, spine, and skull. Furthermore, in SAP-CNP tgm, the size of the foramen magnum, the insufficient formation of which results in cervico-medullary compression in achondroplasia, also showed significant increase. CNP primarily activates GC-B, but under high concentrations it cross-reacts with guanylyl cyclase-A (GC-A), a natriuretic peptide receptor subtype of atrial natriuretic peptides (ANP) and brain natriuretic peptides (BNP). Although activation of GC-A could alter cardiovascular homeostasis, leading to hypotension and heart weight reduction, the skeletal overgrowth phenotype in the line of SAP-CNP tgm with mild overexpression of CNP did not accompany decrease of systolic blood pressure or heart weight. These results suggest that CNP administration stimulates skeletal growth without adverse cardiovascular effect, and thus CNP could be a promising remedy targeting achondroplasia.
Preview · Article · Oct 2009 · AJP Endocrinology and Metabolism
[Show abstract][Hide abstract] ABSTRACT: Zona incision using a piezo-micromanipulator (ZIP) has been demonstrated to be effective for in vitro fertilization (IVF) using cryopreserved C57BL/6 spermatozoa. In this study, ZIP oocytes inseminated with frozen-thawed genetically modified C57BL/6J or FVB mice spermatozoa (21 lines) showed fertilization rates of 22-75% and live fetus rates of 8-49%. In 6 of the lines, the fertilization rates for oocytes compared with ZIP (42-75%) were significantly higher than that of nontreated oocytes (0-50%). Using only 90 oocytes for IVF with ZIP, 5 breeding pairs were produced from cryopreserved genetically modified mice spermatozoa. Our results indicate that application of the ZIP technique is effective for IVF using cryopreserved genetically modified mouse spermatozoa.
Preview · Article · Aug 2009 · Experimental Animals
[Show abstract][Hide abstract] ABSTRACT: Angiotensin II via type 1 receptor activation upregulates the expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), and LOX-1 activation, in turn, upregulates angiotensin II type 1 receptor expression. We postulated that interruption of this positive feedback loop might attenuate the genesis of angiotensin II-induced hypertension and subsequent cardiac remodeling. To examine this postulate, LOX-1 knockout and wild-type mice were infused with angiotensin II or norepinephrine (control for angiotensin II) for 4 weeks. Angiotensin II-, but not norepinephrine-, induced hypertension was attenuated in LOX-1 knockout mice. Angiotensin II-induced cardiac remodeling was also attenuated in LOX-1 knockout mice. Importantly, angiotensin II type 1 receptor expression was reduced, and the expression and activity of endothelial NO synthase were preserved in the tissues of LOX-1 knockout mice given angiotensin II. Reactive oxygen species generation, nicotinamide-adenine dinucleotide phosphate oxidase expression, and phosphorylation of p38 and p44/42 mitogen-activated protein kinases were also much less pronounced in the LOX-1 knockout mice given angiotensin II. These alterations in biochemical and structural abnormalities were associated with preservation of cardiac hemodynamics in the LOX-1 knockout mice. To confirm that fibroblast function is modulated in the absence of LOX-1, cardiac fibroblasts from wild-type and LOX-1 knockout mice were treated with angiotensin II. Indeed, LOX-1 knockout mice cardiac fibroblasts revealed an attenuated profibrotic response on treatment with angiotensin II. These observations provide strong evidence that LOX-1 is a key modulator of the development of angiotensin II-induced hypertension and subsequent cardiac remodeling.
[Show abstract][Hide abstract] ABSTRACT: LOX-1 is a newly described lectin-like receptor for oxidized-LDL (ox-LDL), which is over-expressed in the ischemic myocardium. To examine the pathogenic role of LOX-1 in the determination of ischemia-reperfusion (I-R) injury to the heart, we developed LOX-1 knockout (KO) mice, and subjected these mice to 60 min of left coronary artery occlusion followed by 60 min of reperfusion. I-R in the LOX-1 KO mice resulted in a significant reduction in myocardial injury as well as in accumulation of inflammatory cells in the I-R myocardium and lipid peroxidation (P<0.01 vs. wild-type mice). Concomitantly, there was significant preservation of cardiac function in the LOX-1 KO mice despite I-R (P<0.01 vs. the wild-type mice). The phosphorylation of oxidative stress-sensitive mitogen-activated protein kinase (p38MAPK) and protein kinase B/Akt-1, expression of nitrotyrosine and inducible nitric oxide synthase (iNOS), and superoxide dismutase activity were enhanced during I-R in the wild-type mice. These alterations in p38MAPK, Akt-1 and iNOS were much less pronounced in the LOX-1 KO mice. The superoxide dismutase activity increased further in the LOX-1 KO mice. These observations provide compelling evidence that LOX-1 may be a key modulator of myocardial I-R injury, and its effect is mediated by pro-oxidant signals. LOX-1 may be a potential target for therapy of myocardial ischemic injury.
No preview · Article · Jan 2008 · Journal of Molecular and Cellular Cardiology
[Show abstract][Hide abstract] ABSTRACT: Freeze-dried mouse spermatozoa can be used for normal embryonic development after injection into oocytes, thus indicating that freeze-drying is a useful method for the storage and transportation of genetic materials from animals. We recently reported that storage of freeze-dried mouse spermatozoa requires maintenance at temperatures lower than -80 C for long-term preservation and a pressure of 0.37 mbar at primary drying and that these conditions significantly improve the developmental rate to the blastocyst stage. In this study, we examined the influence of transportation and preservation conditions on freeze-dried spermatozoa. Freeze-dried spermatozoa stored for 2 or 2.5 years at 4 or -80 C were transported round trip overland between Shizuoka and Hokkaido prefectures in Japan or by air between Japan and Belgium. The freeze-drying conditions consisted of primary drying at pressures of 0.04, 0.37 and 1.03 mbar and secondary drying at a pressure of 0.001 mbar. Embryos (2-cell stage) from freeze-dried spermatozoa dried at 0.04 mbar and stored at 4 C for 2 years with and without overland transportation did not develop to term. The development rates of embryos from spermatozoa stored at -80 C for up to 2 years and transported overland, by air and without transportation were 8, 1 and 28%, respectively. The development rates of embryos from spermatozoa without transportation were significantly higher than with transportation (P<0.05). These data indicate that freeze-dried spermatozoa stored at -80 C with and without transportation can retain their ability to generate viable offspring after storage for up to 2 years. However, there are limitations to be considered in the transportation of freeze-dried spermatozoa at ambient temperature.
Preview · Article · Dec 2007 · Journal of Reproduction and Development
[Show abstract][Hide abstract] ABSTRACT: Chronic ischemia is associated with alterations in genes that result in myocardial remodeling. An important biochemical basis of cardiac remodeling is generation of reactive oxygen species (ROS). A few studies have suggested that acute ischemia triggers signals for remodeling. We examined the hypothesis that targeted deletion of lectin-like oxidized-LDL receptor (LOX-1) may inhibit signals related to cardiac remodeling.
We generated LOX-1 knockout (KO) mice on C57BL/6 (wild-type mice) background, and subjected wild-type and KO mice to ischemia-reperfusion (I-R). The wild-type mice developed a marked reduction in left ventricular systolic pressure and +/-dp/dt(max) and an increase in left ventricular end-diastolic pressure following I-R, and this change was much less in the LOX-1 KO mice, indicating preservation of left ventricular function with LOX-1 deletion. There was evidence for marked oxidative stress (NADPH oxidase expression, malondialdehyde and 8-isoprostane) following I-R in the wild-type mice, much less so in the LOX-1 KO mice (P<0.01). In concert, collagen deposition (Masson's trichrome and Picro-sirius red staining) increased dramatically in the wild-type mice, but only half as much in the LOX-1 KO mice (P<0.01). Collagen staining data was corroborated with procollagen-I expression. Further, fibronectin and osteopontin expression increased in the wild-type mice, but to a much smaller extent in the LOX-1 KO mice (P<0.01).
These findings provide compelling evidence that LOX-1 is a key modulator of cardiac remodeling which starts immediately following I-R.
Full-text · Article · Nov 2007 · Cardiovascular Research
[Show abstract][Hide abstract] ABSTRACT: Atherosclerosis is associated with oxidative stress and inflammation, and upregulation of LOX-1, an endothelial receptor for oxidized LDL (oxLDL). Here, we describe generation of LOX-1 knockout (KO) mice in which binding of oxLDL to aortic endothelium was reduced and endothelium-dependent vasorelaxation preserved after treatment with oxLDL (P<0.01 versus wild-type mice). To address whether endothelial functional preservation might lead to reduction in atherogenesis, we crossed LOX-1 KO mice with LDLR KO mice and fed these mice 4% cholesterol/10% cocoa butter diet for 18 weeks. Atherosclerosis was found to cover 61+/-2% of aorta in the LDLR KO mice, but only 36+/-3% of aorta in the double KO mice. Luminal obstruction and intima thickness were significantly reduced in the double KO mice (versus LDLR KO mice). Expression of redox-sensitive NF-kappaB and the inflammatory marker CD68 in LDLR KO mice was increased (P<0.01 versus wild-type mice), but not in the double KO mice. On the other hand, antiinflammatory cytokine IL-10 expression and superoxide dismutase activity were low in the LDLR KO mice (P<0.01 versus wild-type mice), but not in the double KO mice. Endothelial nitric oxide synthase expression was also preserved in the double KO mice. The proinflammatory signal MAPK P38 was activated in the LDLR KO mice, and LOX-1 deletion reduced this signal. In conclusion, LOX-1 deletion sustains endothelial function leading to a reduction in atherogenesis in association with reduction in proinflammatory and prooxidant signals.
Full-text · Article · Jul 2007 · Circulation Research
[Show abstract][Hide abstract] ABSTRACT: Freeze-dried spermatozoa are capable of participating in normal embryonic development after injection into oocytes and thus useful for the maintenance of genetic materials. We recently reported that long-term preservation of freeze-dried mouse spermatozoa by conventional methods requires temperatures lower than -80 degrees C. Successful permanent preservation of mouse spermatozoa at much higher temperatures requires thorough investigation of the freeze-drying procedure. Thus, we examined the relationship between the pressure at primary drying and the preservation potential of freeze-dried mouse spermatozoa. Three different primary drying pressures were applied to evaluate the effect of pressure on freeze-dried spermatozoa under varying storage conditions and the rate of development measured. The developmental rate of embryos to the blastocyst stage from intracytoplasmic sperm injection by freeze-dried spermatozoa at pressures of 0.04, 0.37, and 1.03 mbar without storage were 59% (337/576), 71% (132/187), and 33% (99/302) respectively. When stored at 4 degrees C for 6 months, the rate was 13% (48/367), 50% (73/145), and 36% (66/182) respectively. These results show that primary drying pressure is an influential factor in the long-term preservation of freeze-dried mouse spermatozoa.
Preview · Article · May 2007 · Reproduction (Cambridge, England)
[Show abstract][Hide abstract] ABSTRACT: We have been investigating the functional display of multipass membrane protein such as transporter or G-protein coupled receptor on the budded baculovirus (BV). We tested the use of a viral envelope protein gp64 transgenic mouse for the direct immunization of these membrane proteins displayed on BVs. The gp64 transgenic mice showed only a weak response to virus compared to wild type BALB/c mice. Immunizing gp64 transgenic mice with the BV expressing peptide transporter PepT1, we obtained 47 monoclonal antibodies (mAbs). These mAbs were specific to the PepT1 on the pancreatic cancer cells AsPC-1 by fluorocytometric analysis and exhibited antibody-dependent cellular cytotoxicity or complement-dependent cytotoxicity to AsPC-1. We also generated 7 mAbs by immunizing gp64 transgenic mice on a CCR2-deficient background with the BV expressing chemokine receptor CCR2 together with partially purified CCR2. These mAbs possessed specific binding to CCR2 in CHO cells on fluorocytometric analysis, and exhibited neutralizing activities for ligand-dependent inhibition of cyclic AMP production. This method provides a powerful tool for the generation of therapeutic/diagnostic mAbs against membrane proteins.
No preview · Article · May 2007 · Journal of Immunological Methods
[Show abstract][Hide abstract] ABSTRACT: Supernatant protein factor (SPF) is a novel cholesterol biosynthesis-accelerating protein expressed in liver and small intestine. Here, we report on the physiological role of SPF by using Spf-deficient mice. Although plasma cholesterol levels were similar in chow-fed Spf-/- and wild-type (WT) mice, fasting significantly decreased plasma cholesterol levels in Spf-/- mice but not in WT mice. While fasting reduced hepatic cholesterol synthesis rate in WT mice, a more pronounced reduction was observed in Spf-/- mice. The expression of cholesterogenic enzymes was dramatically suppressed by fasting both in WT and Spf-/- mice. In contrast, hepatic SPF expression of WT mice was up-regulated by fasting in peroxisome proliferator-activated receptor alpha (PPAR-alpha)-dependent manner. These results indicate that in WT mice, the decrease of hepatic cholesterol synthesis under fasting conditions is at least in part compensated by SPF up-regulation. Fibrates, which function as a PPAR-alpha agonist and are widely used as hypotriglycemic drugs, reduced hepatic cholesterol synthesis and plasma cholesterol levels by approximately one-half in Spf-/- mice but not in WT mice. These findings suggest that co-administration of fibrates and an SPF inhibitor may reduce not only plasma triglyceride but also cholesterol levels, indicating that SPF is a promising hypocholesterolemic drug target.
Full-text · Article · Jan 2007 · The FASEB Journal
[Show abstract][Hide abstract] ABSTRACT: Acute pharmacological inhibition of cardiac malonyl coenzyme A decarboxylase (MCD) protects the heart from ischemic damage by inhibiting fatty acid oxidation and stimulating glucose oxidation. However, it is unknown whether chronic inhibition of MCD results in altered cardiac function, energy metabolism, or ischemic cardioprotection.
Mcd-deficient mice were produced and assessed for in vivo cardiac function as well as ex vivo cardiac function, energy metabolism, and ischemic tolerance. In vivo and ex vivo cardiac function was similar in wild-type and mcd-/- mice. Ex vivo working hearts from mcd-/- and wild-type mice displayed no significant differences in rates of fatty acid oxidation, glucose oxidation, or glycolysis. However, cardiac deletion of mcd resulted in an increased expression of genes regulating fatty acid utilization that may compensate for the loss of MCD protein and likely contributes to the absence of changes in energy metabolism in the aerobic heart. Despite the lack of changes in fatty acid utilization, hearts from mcd-/- mice displayed a marked preference for glucose utilization after ischemia, which correlated with a significant cardioprotection of ischemic hearts from mcd-/- mice compared with wild-type mice.
Deletion of MCD markedly increases glucose oxidation and improves functional recovery of the heart after ischemia. As a result, chronic pharmacological inhibition of MCD may be a viable approach to treat myocardial ischemia.
[Show abstract][Hide abstract] ABSTRACT: In the present study, we established transgenic mice overexpressing Del1, a ligand of integrins, to examine the effect of overexpression of Del1 on vascular morphogenesis. In the wild-type mouse, mesenteric vessels are shaped like rakes consisting of a long stalk and short branches at the periphery. In contrast, those in transgenic mice showed typical dendritic architecture consisting of a few large primary branches with smaller spreading branches. The phenotype of mice overexpressing Del1 suggests the existence of a tissue-specific mechanism for branching morphogenesis in the mesentery.
Preview · Article · Dec 2005 · The Anatomical Record Part A Discoveries in Molecular Cellular and Evolutionary Biology
[Show abstract][Hide abstract] ABSTRACT: Freeze-dried mouse spermatozoa are capable of participating in normal embryonic development after injection into oocytes. When the freeze-dried spermatozoa are used as a method for storage of genetic materials, however, it is essential to assure the relevance of long-term preservation over several decades or centuries. Thus, we applied the theory of accelerated degradation kinetics to freeze-dried mouse spermatozoa. Thermal denaturation kinetics were determined based on Arrhenius plots derived from transition-state theory analysis at three elevated temperatures: 30, 40, and 50 degrees C. Accelerated degradation kinetics were calculated by extrapolation of Arrhenius plots. This theory also is being applied to the long-term stability of drugs. The estimated rate of development to the blastocyst stage at 3 and 6 mo and at 1, 10, and 100 yr of sperm storage at 4 degrees C were 21.60%, 7.91%, 1.00%, 0%, and 0%, respectively. At -80 degrees C, estimated development rates to the blastocyst stage that would be expected after 100 yr of storage did not decline significantly. In addition, after 3 or 6 mo of storage at 4 or -80 degrees C, preimplantation development of the embryos derived from intracytoplasmic sperm injection (ICSI) was examined. The actual developmental rates to the blastocyst stage from ICSI by freeze-dried sperm stored for 3 mo at 4 and -80 degrees C were 21% and 62%, respectively, and the rates for such sperm stored for 6 mo were 13% and 59%, respectively. These results indicate that the determination of accelerated degradation kinetics can be applied to the preservation of freeze-dried mouse spermatozoa. Furthermore, for long-term preservation, freeze-dried mouse spermatozoa appear to require being kept at lower than -80 degrees C.
No preview · Article · Apr 2005 · Biology of Reproduction
[Show abstract][Hide abstract] ABSTRACT: Cryopreservation of mouse spermatozoa has been widely applied for maintenance of transgenic and knockout lines. However, the fertility of cryopreserved spermatozoa from some inbred strains such as C57BL/6 and BALB/c is extremely poor. We have recently reported that a partial zona-pellucida incision by piezo-micromanipulator (ZIP) significantly improves the fertilization rate and subsequent embryonic development after in vitro fertilization (IVF) using cryopreserved C57BL/6 transgenic mouse spermatozoa and that inbred C57BL/6 mice could be produced by intracytoplasmic sperm injection (ICSI). These findings prompted us to compare the efficiency of fertilization and subsequent embryonic development between ICSI and IVF with ZIP (ZIP/IVF) using cryopreserved spermatozoa. In conventional IVF, BALB/cA, C57BL/6J, and B6C3F1 cryopreserved spermatozoa fertilized 19%, 0%, and 51% of oocytes, respectively. The fertilization rates of manipulated oocytes by ICSI versus ZIP/IVF using cryopreserved BALB/cA spermatozoa were 52% versus 68%, cryopreserved C57BL/6J spermatozoa were 43% versus 63%, and cryopreserved B6C3F1 spermatozoa were 58% versus 82%, respectively. In these strains, fertilization rates for ZIP/IVF were significantly higher (P < 0.05) than for other techniques. However, embryonic development to term for oocytes fertilized by cryopreserved spermatozoa was not significantly different between ZIP/IVF and ICSI in C57BL/6J and B6C3F1. The overall efficiency of mouse production in ZIP/IVF was higher than for ICSI and conventional IVF in C57BL/6J and B6C3F1. Furthermore, ZIP/IVF required approximately 3.3 times less manipulation time than did ICSI. Our results indicate that ZIP is a useful assisted reproductive technique for IVF of ova by cryopreserved spermatozoa and improves production in some mouse strains.
No preview · Article · Jan 2004 · Contemporary topics in laboratory animal science / American Association for Laboratory Animal Science
[Show abstract][Hide abstract] ABSTRACT: Blastocyst implantation and successful establishment of pregnancy require delicate interactions between the embryo and maternal environment. It is believed that the growth of transferred embryos of different ages is synchronized during preimplantation development and that such embryos are implanted in the uterus at the same time. To define the time of synchronization for developing embryos of different ages, embryos at two different stages of development were transferred separately into the oviducts of the same recipient. We then examined the subsequent development of the embryos at various time intervals after transfer. Pronucleus (PN) stage eggs were transferred separately to the right or left oviduct of recipients on Day 0, while eight-cell embryos (8C) were transferred to the other oviduct. For 8C, 5%, 63%, and 74% of transferred embryos were implanted in the uterus at 42, 66, and 90 h posttransfer, respectively. In contrast, none of the transferred PN was implanted until 90 h posttransfer. At 90 h posttransfer, 59% of the PN had successfully implanted. Histological examination revealed that developmental stage of the embryos in both groups synchronized around 162 h posttransfer, even though the implantation was accelerated in 8C compared with PN. Our results indicate that embryos of advanced stage transferred to the oviduct implant in the uterus in advance of younger embryos and that the uterine development is synchronized at the neural plate, presomite stage. Our results strongly suggest that uterine receptivity for implantation is expandable in pseudopregnant mice.
No preview · Article · Oct 2003 · Biology of Reproduction
[Show abstract][Hide abstract] ABSTRACT: Peutz-Jeghers syndrome (PJS) is a dominantly inherited human disorder characterized by gastrointestinal hamartomatous polyposis and mucocutaneous melanin pigmentation. LKB1 (STK11) serine/threonine kinase is the product of the causative gene of PJS, which has been mapped to chromosome 19p13.3. However, several studies have produced results that are not consistent with a link between LKB1 gene mutation and PJS. We constructed a knockout gene mutation of Lkb1 to determine whether it is the causative gene of PJS and to examine the biological role of the Lkb1 gene. Lkb1(-/-) mice died in utero between 8.5 and 9.5 days postcoitum. At 9.0 days postcoitum, Lkb1(-/-) embryos were generally smaller than their age-matched littermates, showed developmental retardation, and did not undergo embryonic turning. Multiple gastric adenomatous polyps were observed in 10- to 14-month-old Lkb1(+/-) mice. Our results indicate that functional Lkb1 is required for normal embryogenesis and that it is related to tumor development. The Lkb1(+/-) mouse is suitable for studying molecular mechanism underlying the development of inherited gastric tumors in PJS.
Full-text · Article · Jul 2002 · Proceedings of the National Academy of Sciences