bluuebunny/crossref_metadata_2025_split huggingface dataset:
Insulin and IGF‐I signaling through the insulin receptor substrate 1
Authors: Keller Susanne R. , Lamphere Lou , Lavan Brian E. , Kuhné Michelle R. , Lienhard Gustav E. 
Published: February 2005

AbstractThe insulin and insulin‐like growth factor‐I (IGF‐I) receptors are tyrosine kinases. Consequently, an approach to investigating signaling pathways from these receptors is to characterize proteins rapidly phosphorylated on tyrosine in response to insulin and IGF‐I. In many cell types the most prominent phosphotyrosine (Ptyr) protein, in addition to the receptors themselves, is a protein of ˜160 kD, now known as the insulin receptor substrate 1 (IRS‐1). We have purified IRS‐1 from mouse 3T3‐L1 adipocytes, obtained the sequences of tryptic peptides, and cloned its cDNA based on this information. Mouse IRS‐1 is a protein of 1,231 amino acids. It contains 12 tyrosine residues in sequence contexts typical for tyrosine phosphorylation sites. Six of these begin the sequence motif YMXM and two begin the motif YXXM. Recent studies have shown that the enzyme phosphatidylinositol 3‐kinase (PI 3‐kinase) binds tightly to the activated platelet‐derived growth factor (PDGF) and colony‐stimulating factor‐1 (CSF‐1) receptors, through interaction of the src homology 2 (SH2) domains on the 85 kD subunit of PI 3‐kinase with Ptyr in one of these motifs on the receptors. We have found that, upon insulin treatment of 3T3‐L1 adipocytes, a portion of the Ptyr form of IRS‐1 becomes tightly complexed with PI 3‐kinase. Since IRS‐1 binds to fusion proteins containing the SH2 domains of PI 3‐kinase, association most likely occurs through this domain. The association of IRS‐1 with PI 3‐kinase activates the enzyme about fivefold. Thus, one signaling pathway from the insulin and IGF‐I receptors probably proceeds as follows: tyrosine phosphorylation of IRS‐1, tight association of IRS‐1 with PI 3‐kinase with accompanying activation of the kinase, elevation of the PI 3‐phosphates. © 1993 Wiley‐Liss, Inc.
Gene regulation by IGF‐I
Authors: Baserga Renato 
Published: February 2005

AbstractConstitutive overexpression of the insulin‐like growth factor‐I (IGF‐I) receptor makes 3T3 cells capable of growing in serum‐free medium supplemented solely with IGF‐I to the total exclusion of the platelet‐derived growth factor (PDGF) and epidermal growth factor (EGF) receptors, the other two receptors that are required for the growth of 3T3 cells. Pietrzkowski et al. (Cell Growth Differ 92:199–205, 1992) found that these cells, overex‐pressing the IGF‐I receptor, can also be induced to grow by the addition of EGF. We have ascertained that the mechanism by which EGF induces growth in these cells is through the induction of substantial amounts of IGF‐I RNA and IGF‐I. In 3T3 cells overexpressing the EGF receptor, a functional IGF‐I receptor is still required for growth. We have also found, using a temperature‐sensitive mutant of the SV40 large T antigen, that the levels of IGF‐I mRNA and of IGF‐I secreted in the medium are markedly increased by a functional T antigen. Using an IGF‐I promoter driving a reporter luciferase gene, we have determined that this increase in the expression of IGF‐I by T‐antigen occurs, at least in part, at a transcriptional level. It seems, therefore, that transformation by SV40 reduces the requirement for growth factors by increasing the production of IGF‐I. © 1993 Wiley‐Liss, Inc.
Parental imprinting of anIGF‐2transgene
Authors: Lee Jacqueline E. , Tantravahi Umadevi , Boyle Ann L. , Efstratiadis Argiris 
Published: February 2005

AbstractAs a consequence of parental imprinting in mice, the paternal allele encoding insulin‐like growth factor‐II (IGF‐II) is expressed, whereas the maternal allele is silent in most tissues. To examine whethercis‐acting sequences involved in imprinting are located in the vicinity of thelgf‐2gene, we have constructed mouse transgenic lines and studied the expression of a 30 kb ratlgf‐2transgene, in which the coding region has been replaced with thelacZreporter sequence. Chromatin position effects and/or absence of long‐range regulatory elements seem to have affected tissue‐specific expression in the transgenic mice. However, in one of six expressing lines, staining of embryos for β‐galactosidase activity was detected in a minor subset of tissues normally transcribing the endogenous homolog, but only when the transgene was transmitted paternally. This transgene was integrated into mouse chromosome 19, which is apparently free of imprinted loci. Although the possibility that thelgf‐2transgene was inserted into an as yet unidentified imprinted iocus is discussed, a more likely interpretation of our results is that the transgene carries at least a portion of its own imprinting signal, because it consists of the genomic sequences of a locus already known to be imprinted and maintains the correct imprinting mode. © 1993 Wiley‐Liss, Inc.
Coexpression of gap junction proteins in the cumulus‐oocyte complex
Authors: Valdimarsson Gunnar , De Sousa Paul A. , Kidder Gerald M. 
Published: February 2005

AbstractThe connexins constitute a family of proteins that make up the intercellular membrane channels of gap junctions. We had previously reported the presence of two members of this protein family, connexins 32 and 43, in mouse one‐cell zygotes (Barron et al., Dev Genet 10:318–323, 1989; Valdimarsson et al., Mol Reprod Dev 30:18–26, 1991), implying that both must be present in the mature oocyte and could be involved in mediating the intercellular coupling that occurs between the oocyte and cumulus granulosa during oogenesis. In the present report we provide evidence for this, based on an analysis of the cumulus‐oocyte complex (COC) using reverse transcription‐polymerase chain reaction (RT‐PCR) and immunocytochemistry with a confocal microscope. Transcripts of both connexin32 (Cx32) and connexin43 (Cx43) were detected by RT‐PCR in both components of the COC. Cx32 mRNA in the oocyte declined precipitously following human chorionic gonadotropin (hCG) stimulation of pregnant mare serum gonadotropin (PMSG)‐primed ovaries, whereas there was no obvious change in Cx43 mRNA. Peptide‐specific antibodies against both connexins provided diffuse cytoplasmic staining of oocytes as well as some punctate staining near the oocyte surface, which could not be unequivocally resolved as cumulus‐oocyte gap junctions. However, the two antibodies did provide clear evidence of Cx32 and Cx43 in gap junction‐like structures between cumulus cells. We could find no evidence of the incorporation of the oocyte's store of Cx32 into gap junctions during postfertilization development. These findings make it very likely that intercellular coupling within the COC involves at least three types of gap junction channels (32–32, 32–43, 43–43), only one of which (43–43) is retained by the preimplantation embryo. © 1993 Wiley‐Liss, Inc.
Growth retardation in rats whose growth hormone gene expression was suppressed by antisense RNA transgene
Authors: Matsumoto Kazuya , Kakidani Hitoshi , Takahashi Akio , Nakagata Naomi , Anzai Masayuki , Matsuzaki Yuichi , Takahashi Yumi , Miyata Kenji , Utsumi Kyozo , Iritani Akira 
Published: February 2005

AbstractWe produced four transgenic founder rats (Fo) by introducing into rat embryos a fusion gene, which consisted of rat growth hormone (GH) promoter containing with four copies of thyroid hormone response element (TRE) and antisense cDNA sequences for rat GH. This transgene promoter directed 2.8‐fold stimulation of CAT gene expression in transfected GH3 rat pituitary tumor cells compared with the rat GH promoter alone. Two of four transgenic rats expressed antisense RNA in the pituitary. Transgenic offspring (F1) from each founder rat exhibited dwarfism at as early as 3–4 weeks of age, and they exhibited ≈︁T70–85% reduced growth rate compared with their nontransgenic littermates over 56 weeks of observation. Plasma rat GH concentration was ≈︁T40–50% lower in transgenic F1 rats compared to their nontransgenic littermates. In these experiments, the pituitary hormone expression controlled in a complex manner was shown to be repressed by the antisense RNA transgene. Furthermore, the suppression of gene expression could be achieved by antisense RNA transgene in the rat as well. © 1993 Wiley‐Liss, Inc.
Spermatogenesis in the black porgy, Acanthopagrus schlegeli (teleostei: Perciformes: Sparidae)
Authors: Gwo J.‐C. , Gwo H.‐H. 
Published: February 2005

AbstractThe ultrastructure of spermatogenesis and of the spermatozoon of Acanthopagrus schlegeli (Sparidae) are described. The testis is of the unrestricted type. Germ cells are surrounded by cyst cells. Spermiogenesis involves conspicuous modifications such as intracellular movements (diplosome and mitochondria migration, nuclear rotation, and depression) and structural changes (chromatin condensation, shape of mitochondria, and loss of cytoplasm). The mature spermatozoon has a spherical nucleus with a deep, axial nuclear fossa, and an unusual notch, shaped like a bow tie. The short midpiece contains four spherical mitochondria and encircles the basal body of the flagellum. It is concluded that the A. schlegeli spermatozoon is of a primitive type, but that it is characterized by a unique feature which may provide a useful systematic character. © 1993 Wiley‐Liss, Inc.
Multiple activation of mouse sperm motility
Authors: Si Yuming , Okuno Makoto 
Published: February 2005

AbstractTo investigate the activation mechanism of mouse sperm motility, the intact sperm in various activities were further investigated after demembranation. When dry sperm was diluted into sucrose solution, the sperm exhibited low motility with the swimming velocity of 13.5 ± 3.8 μm/s and the beat frequency of 1.5 ± 0.4 Hz. The demembranated sperm were immotile in the reactivation solution lacking cAMP. Meanwhile, when dry sperm was diluted into the solution containing either high concentration of NaCl or Ca2+, they exhibited the beat frequency of about 9 Hz. The demembranated ones exhibited the intermediate motility in the absence of cAMP. When dry sperm were diluted into the sucrose solution containing HCO3, the sperm exhibited a vigorous motility with the swimming velocity of 181.2 ± 10.1 μm/s and the beat frequency of 11.3 ± 1.2 Hz. The demembranated sperm exhibited the high reactivation motility (90%) and flagellar beat frequency (9 Hz) in the absence of cAMP. These values were almost equivalent to those obtained in the demembranated sperm pretreated with sucrose or Ca2+ or NaCl and reactivated in the presence of cAMP. The activation induced by bicarbonate was considered complete in comparison with the activation by Ca2+ or NaCl. It was likely that the activation of mouse sperm motility took multiple states. © 1993 Wiley‐Liss, Inc.
Pluripotency of cultured rabbit inner cell mass cells detected by isozyme analysis and eye pigmentation of fetuses following injection into blastocysts or morulae
Authors: Giles J. R. , Yang X. , Mark W. , Foote R. H. 
Published: February 2005

AbstractPluripotency of isolated rabbit inner cell masses (ICMs) and cultured (3 days) inner cell mass (ICM) cells was tested by injecting these donor cells into day 3.5 blastocysts (experiment 1) or day 3 morulae (experiment 2) to produce chimeric embryos. Injected (n = 107) and noninjected (n = 103) embryos were transferred to the opposite uterine horns of the same recipient females. Chimerism was determined by adenosine deaminase (ADA) isozyme analysis on fetal tissue and by eye pigmentation at midgestation. In experiment 1, 53% and 64%, respectively, of blastocysts injected with ICMs or cultured ICM cells developed to midgestation, compared with 52% and 48% for controls. Of these fetuses, four (31%) and one (6%), respectively, had ADA chimerism. In experiment 2,38% and 62%, respectively, of the morulae injected with ICMs or cultured ICM cells developed to midgestation, compared with 46% and 56% for control morulae. Six (43%) chimeric fetuses from morulae injected with ICMs were detected by ADA analysis, but 12 (86%) chimeric fetuses were detected by eye pigmentation, indicating that eye pigmentation was a more sensitive marker for chimerism than our ADA assay. None of the 14 fetuses recovered after injecting morulae with cultured ICM cells were chimeric with either marker. No chimeras developed from control embryos. These studies demonstrate (1) that pregnancy rates are not compromised by injection of blastocysts or morulae with ICMs or cultured ICM cells, (2) that chimeric rabbit fetuses can be produced by injecting ICMs into either blastocysts or morulae, and (3) that cultured ICM cells can contribute to embryonic development when injected into blastocysts. © 1993 Wiley‐Liss, Inc.
Alkaline phosphatase staining of pig and sheep epiblast cells in culture
Authors: Talbot Neil C. , Rexroad Caird E. , Pursel Vernon G. , Powell Anne M. 
Published: February 2005

AbstractTo define better the characteristics of pig and sheep epiblast cells in culture, the cells were tested for the presence of alkaline phosphatase (AP), a biochemical marker characteristic of mouse embryonic stem cells. Pig and sheep epiblast cells were positive for AP staining both at isolation from the blastocyst and after primary in vitro culture. The innermost portion of the attendant endoderm surrounding the epiblast was also positive for AP staining during primary culture. AP staining was lost upon differentiation or senescence of the epiblast cells. Also, all differentiated epiblast‐derived cell cultures were negative for AP staining, with the exception of neuron‐like cultures. Epiblast‐like cells were cultured from day 10 (pig) and day 13 (sheep) embryonic discs, and these cells were also AP positive until they differentiated. Trophectoderm‐endoderm‐like cells from embryonic discs were AP negative or weakly positive. AP is a convenient marker for undifferentiated pig and sheep epiblast cells in culture when used in conjunction with cell morphology analysis. © 1993 Wiley‐Liss, Inc.
Evaluation of mouse sperm acrosomal status and viability by flow cytometry
Authors: Tao Jun , Critser Elizabeth S. , Critser John K. 
Published: February 2005

AbstractA procedure was developed to evaluate mouse sperm acrosomal status and viability simultaneously utilizing flow cytometry. Four fluorescein isothiocyanate (FITC)‐conjugated lectins, peanut agglutinin (PNA), concanavalin agglutinin (ConA), Pisum sativum agglutinin (PSA), and soybean agglutinin (SBA), were investigated, with PNA providing the greatest sensitivity and specificity in distinguishing acrosome‐present and acrosome‐absent mouse spermatozoa. To expose lectin binding sites, digitonin (20 μM at room temperature for 10 min) was used to permeabilize sperm plasma membranes. Sperm cell viability was determined by Hoechst 33258 (H258) exclusion. To prevent permeabilized cells from staining with H258, salmon sperm DNA (SS‐DNA) was applied to bind excess dye in the solutions after supravital staining. Calcium ionophore (A23187; 5 or 20 μM) was used to induce acrosome reactions. The results of flow cytometric analyses were compared with epifluorescence microscopic observation and were highly correlated (r = 0.999; P < 0.001). The method developed provides an objective and efficient procedure to estimate simultaneously both acrosomal status and viability of mouse spermatozoa. © 1993 Wiley‐Liss, Inc.
Sex determination of in vitro developed buffalo (Bubalus bubalis) embryos by DNA amplification
Authors: Rao K. B. C. Appa , Pawshe C. H. , Totey S. M. 
Published: February 2005

AbstractThis study was conducted to determine the sex of buffalo embryos produced in vitro by amplifying male specific DNA sequences using the polymerase chain reaction (PCR). This method uses three different pairs of bovine Y‐chromosome specific primers and a pair of bovine satellite specific primers. Buffalo in vitro fertilized embryos at the 4‐cell to blastocyst stage were collected at days 3, 4, 6, and 8 postinsemination, and the sex of each embryo was determined using all three different Y‐chromosome specific primers. The bovine satellite sequence specific primers recognize similar sequences in buffalo and are amplified both in males and in females. Similarly, Y‐chromosome specific primers amplify the similar Y‐chromosome specific sequences in male embryos of buffalo. Upon examining genomic DNA from lymphocytes of adult males and females, and embryos, the results demonstrate the feasibility of embryo sexing in buffaloes. Furthermore, sex determination by PCR was found to be a rapid and accurate method. © 1993 Wiley‐Liss, Inc.
Presence and possible role of C‐ras and nuclear (c‐fos and c‐jun) proto‐oncogene products in preimplantation embryonic development in mice
Authors: Ahmad Khaliq , Naz Rajesh K. 
Published: February 2005

AbstractThe presence and possible role of products of nuclear (c‐fos and c‐jun) and c‐ras proto‐oncogenes were investigated in preimplantation embryonic development in mice. Polyclonal antibodies to c‐fos or c‐jun proto‐oncogene products did not affect development of in vitro‐cultured embryos from two‐cell to morula or from morula to late blastocyst stages. However, v‐H‐ras monoclonal antibody (mAb) to c‐ras protein (p21), although it did not inhibit the development of in vitro‐cultured embryos from two‐cell to morula stages, it significantly (P < .001–.005) inhibited the development of morula to late blastocyst stages in a dose‐dependent manner. The effects of v‐H‐ras mAb were specific, since immunoabsorption with synthetic ras peptide completely blocked inhibitory effects of v‐H‐ras mAb. Neither c‐fos nor c‐jun antibodies reacted with specific proteins corresponding to c‐fos (62 kDa) and c‐jun (39 kDa) products on the Western blots of various murine ova/embryos extracts. However, the c‐fos and c‐jun antibodies reacted with 62 and 39 kDa protein bands, respectively, on the blot of NIH 3T3 cells extract. The v‐H‐ras mAb specifically identified 21 ± 3 kDa protein corresponding to c‐ras p21 on the blots of early as well as late blastocyst extracts. The rat control ascites IgG1 did not react with any protein band on the blots of various ova/embryo extracts. The reactions of v‐H‐ras mAb on the Western blots of blastocyst extracts were specific, since immunoabsorbed antibody was unable to react with any specific band on blots of early or late blastocyst extract. These results were further confirmed by immunoprecipitation procedure utilizing v‐H‐ras mAb. Again, the v‐H‐ras mAb immunoprecipitated a 21 kDa band from early as well as late blastocyst extracts. The rat control ascites IgG1 did not react with any band corresponding to p 21 in the immunoprecipitation procedure. These results suggest that the specific products of nuclear proto‐oncogenes, the c‐fos and c‐jun, are not detected in murine ova and preimplantation embryos, and the respective antibodies do not inhibit embryogenesis, indicating that they may not play a major role in early embryonic development. On the other hand, the product of c‐ras proto‐oncogene is specifically expressed in the blastocyst‐stage embryos and may have a possible role in preimplantation embryonic development in mice. © 1993 Wiley‐Liss, Inc.
Assessment of ram sperm mitochondrial function by quantitative determination of sperm rhodamine 123 accumulation
Authors: Windsor D. P. , White I. G. 
Published: February 2005

AbstractA simple procedure is described for determining the functional state of ram sperm mitochondria by quantitative measurement of sperm rhodamine 123 (R 123) accumulation. Sperm were incubated with 1 μg/ml R 123, and the accumulated R 123 was measured fluorimetrically after release from washed sperm by detergent lysis. Ram sperm R 123 uptake was maximal after 30 min of incubation and responded to changes in both sperm (P < 0.01) and R 123 (P < 0.01) concentration. There was a linear relationship (r = 0.98) between R 123 uptake and the proportion of cold‐shocked sperm present in a sperm sample. R 123 uptake was unaffected by 20 mM 2‐deoxyglucose or by 10 mM malonate (the latter being sufficient to reduce O2 uptake; P < 0.01). R 123 accumulation in ram sperm was reduced by 6 mg/ml sodium pentobarbitone (P 0.05), by 1 μM 2,4‐dinitrophenol (P < 0.01), and by 0.05% Triton X‐100 (P < 0.01). It is concluded that quantitative estimation of R 123 uptake complements oxygen uptake in detecting mitochondrial dysfunction in ram sperm. While it is largely unaffected by inhibition of glycolysis, and is less sensitive than oxygen uptake to trichloroacetic acid cycle inhibition, R 123 uptake is sensitive to factors directly reducing the mitochondrial membrane potential of ram sperm. It may therefore be useful in the evaluation of the effects of such membrane‐mediated injuries as cold shock and freezing damage on ram sperm mitochondria. © 1993 Wiley‐Liss, Inc.
Temperature and androgens regulate the biosynthesis of secretory proteins from rabbit cauda epididymidis
Authors: Regalado Francisco , Esponda Pedro , Nieto Antonio 
Published: February 2005

AbstractWe have compared the biosynthesis of secretory proteins in rabbit cauda epididymidis maintained for 15 days at abdominal temperature with that of the scrotal cauda. Explants from both situations were incubated in vitro in the presence of [35S] methionine, and the labelled proteins released into the incubation medium were analyzed by polyacrylamide gel electrophoresis. Body temperature specifically inhibited the synthesis of at least two polypeptides of 43 kDa and 21 kDa (designated EP21), whereas the synthesis of polypeptides of 80, 39, 31, and 24 kDa was increased. These changes resembled those produced by castration, but androgen treatment was not able to reverse the effect of body temperature. To confirm these observations, poly (A)+ RNA from the scrotal and the abdominal cauda respectively, was translated in vitro and the synthesized products were immunoprecipi‐tated with an antibody against EP21 polypeptide. Both castration and body temperature strongly decreased the concentration of EP21 mRNA. In vivo testosterone administration restored the content of EP21 mRNA in cauda from castrated animals, but not in cauda maintained at body temperature. The changes observed might be related to the adverse effect of body temperature on sperm storage in the cauda epididymidis. © 1993 Wiley‐Liss, Inc.
Temporal pattern of IGF‐I expression during mouse preimplantation embryogenesis
Authors: Doherty Adam S. , Temeles Gretchen L. , Schultz Richard M. 
Published: February 2005

AbstractAlthough mouse preimplantation embryos express transcripts for the insulin‐like growth factor‐I receptor (IGF‐IR), IGF‐I transcripts were not detected by reverse transcription‐PCR (RT‐PCR) at any stage of preimplantation development in a previous study (Rappolee et al., Genes Dev 6:939–952, 1992). We report that IGF‐I transcripts are detected in the preimplantation embryo by RT‐PCR and describe the temporal pattern of expression of this transcript from the oocyte to blastocyst stages; the level declines from the oocyte to 8‐cell embryo and then increases from the 8‐cell to blastocyst stages. An explanation is offered to account for the differences in detecting the IGF‐I transcript, and the results are discussed in the context of an autocrine/paracrine IGF‐I circuit in the preimplantation mouse embryo. © 1994 Wiley‐Liss, Inc.