鼠尾胶原蛋白提取、分离、纯化方法的建立及鉴定

目的建立一种高效提取、分离、纯化鼠尾胶原蛋白的方法。方法通过对鼠尾进行剥离获得鼠尾腱,用Tris-HCl缓冲液、胃蛋白酶处理获得鼠尾胶原蛋白原液、反复使用氯化钠溶液进行分级盐析、醋酸溶液复溶进行鼠尾胶原蛋白的纯化。超纯水透析除去无机盐类获得纯化的鼠尾胶原蛋白。通过SDS-PAGE蛋白质电泳、氨基酸含量分析等技术手段鉴定。结果本研究建立的方法可以获得高纯度的鼠尾胶原蛋白,纯度达到电泳纯。与国外进口的商业化鼠尾胶原蛋白产品相比无差异。研究了提取、分离、纯化参数对得率、纯度的影响,建立了最优的鼠尾胶原蛋白提取条件,胃蛋白酶用量：1∶500,酶解时间：72 h,盐析浓度：2 mol/L,提取所用酸溶液：0.05mol/L醋酸溶液。结论为鼠尾胶原蛋白的扩大化生产提供了合适的工艺参数,为大量获得鼠尾胶原蛋白并进行更深层次的功效方面研究提供了理论支持和实践基础。     

Preparation of Rat Serum Suitable for Mammalian Whole Embryo Culture

Mammalian whole embryo culture (WEC) is a widely used technique for examining pharmacological toxicity in developing mouse and rat embryos and for investigating the mechanisms of developmental processes. Immediately centrifuged (IC) rat serum is commonly used for WEC and is essential for the growth and development of cultured mouse and rat embryos ex vivo. For the culture of midgestation embryos (i.e., E8.0-12.5 for the mouse, and E10.0-14.5 for the rat), 100% rat serum is the best media for supporting the growth of the embryo ex vivo. To prepare rat serum suitable for WEC, the collected blood should be centrifuged immediately to separate the blood cells from the plasma fraction. After centrifugation, the fibrin clot forms in the upper layer; this clot should be squeezed gently using a pair of sterile forceps and subsequently centrifuged to completely separate the blood cells from the serum. In this video article, we demonstrate our standard protocol for the preparation of optimal IC rat serum, including blood collection from the abdominal aorta of male rats and extraction of the serum by centrifugation.     

改良皮下种植法建立大鼠子宫内膜异位症模型

目的:采用改进的皮下种植法建立大鼠子宫内膜异位症的疾病模型,在保证成模的前提下,使皮下种植法建立大鼠子宫内膜异位症模型更加简单易操作,且成模效果更明显,术后易寻找病灶。方法:取性成熟期雌性SD大鼠10只,体重约250±5 g,术前五日连续给予苯甲酸雌二醇注射0.04 mg/每天,然后采用改良的皮下种植法建立大鼠子宫内膜异位症模型,既将大鼠自体双侧子宫切下,取其中一侧子宫种植至皮下血供较丰富处,术后第十日起连续五日给予苯甲酸雌二醇注射,于术后四周可观察腹部皮下病灶。结果:造模四周后见皮下种植的皮肤处有明显的圆形突起,切开皮肤可见种植的一侧子宫完整成活,与周围界限清晰,病灶明显易见,血运丰富。结论:实验结果证明此种方法较文献提供的皮下种植法更为简单易操作,省去了分离子宫内膜与肌层的步骤,且有病灶明显术后易寻找病灶的优点。     

Analysis of the cellular interactions involved in the regulation of induced erythrocyte autoantibodies

When normal mice are immunised with rat red blood cells (RBC) they produce autoantibodies against their own red blood cells as well as antibodies against determinants on rat RBC non-cross-reacting with self-RBC. Spleen cells from mice primed with rat RBC specifically suppress the subsequent induction of autoantibody in normal mice. The response to non-cross-reacting determinants on rat RBC is not affected. The results presented here indicate that either T cells or a thymus have to be present in the recipient for suppression to be manifest. It may therefore be the case that suppression is in fact induced in the recipient by the primed T cells.     

A commercially available assay kit for determining aldosterone concentration in non-extracted rat serum

A commercially available assay for aldosterone that requires no extraction was found to be valid without modification for rat serum. The assay was performed in duplicate on as little as 0.5 cc of rat serum and gave linear results from 5 ng/dl to 500 ng/dl, (i.e., the physiological range of the rat). Samples above 150 ng/dl had to be diluted in this assay. The cost per sample if performed in duplicate and in batches was approximately one dollar. We found that this assay, which was developed for and is marketed for determining aldosterone concentration in human samples, offered a cost effective assay for aldosterone determination in the rat.     

Secretory proteins of the lung in rodents: immunocytochemistry

The reactivity of rabbit antisera to rat lung secretory proteins with other rodent species was evaluated by immunocytochemistry. Rabbit anti-rat surfactant apoprotein antiserum reacts with the cytoplasm of rat, mouse, and hamster type II pneumocytes and is specific for these cells. Rabbit antiserum to rat Clara cell secretory proteins stains rat, mouse, and hamster Clara cells. Rabbit antisera specific to the two antigenic types of rat Clara cell antigens were also both reactive with rat, mouse, and hamster Clara cells. An antiserum to the non-serum proteins of hamster lung lavage was also prepared and shown to be specifically reactive with hamster Clara cells. The availability of specific reagents for secretory proteins of rodent lungs is expected to facilitate studies of the respective cell types in various pathologic states.     

Amino acid sequence of rat apolipoprotein A-II deduced from the nucleotide sequence of cloned cDNA

A rat apolipoprotein A-II cDNA clone was isolated from a rat liver cDNA library by in situ hybridization of bacteriophage plaques using a 32P-labeled human apoA-II cDNA as a probe. The cDNA insert from this clone was characterized by DNA sequencing. The amino acid composition derived from the DNA sequence data matched well with that of rat apoA-II reported earlier (Herbert et al. 1974. J. Biol Chem. 249: 5718-5724), indicating that the cDNA insert coded for rat apoA-II. Further evidence was provided by a comparison of the amino acid sequence of rat apoA-II obtained here with that of human apoA-II (Brewer et al. 1972. Proc. Natl. Acad. Sci. USA. 69: 1304-1308). While the rat apoA-II cDNA insert did not code for the entire presegment, it had the same COOH-terminal residues of the presegment as well as the same prosegment (Ala-Leu-Val-Arg-Arg) as in human preproapoA-II, suggesting that rat apoA-II was also synthesized initially as preproapoA-II. Mature rat apoA-II contains 79 amino acids. Residue 6 of mature rat apoA-II is Asp, while it is Cys in human apoA-II, and this would account for the absence of dimeric forms of rat apoA-II in plasma. While the overall amino acid sequence homology between rat and human apoA-II is about 50%, the amphipathic alpha-helical structures, which are responsible for lipid-binding, seem to be conserved in the two proteins. The size of rat apoA-II mRNA was estimated to be about 600 nucleotides.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of the steroidogenic and melanotropic activities of corticotropin, alpha-melanotropin and analogs with their lipolytic activities in rat and rabbit adipocytes.

The ability of alpha-melanotropin and a series of synthetic peptides related to adrenocorticotropin (ACTH) to stimulate steroidogenesis in isolated rat adrenal cells, melanin dispersion in frog melanophores and lipolysis in rat and rabbit fat cells have been studied. It was found that the steroidogenic activity closely paralleled the lipolytic activity of these peptides in rat fat cells, whereas the melanocyte stimulating activity paralleled the lipolytic activity in rabbit fat cells. These results indicate that the structural requirements for stimulating steroidogenesis in isolated rat adrenal cells and lipolysis in isolated rat fat cells are quite similar. The structural features required for eliciting lipolysis in rabbit fat cells appear to be very similar to those necessary for stimulating frog melanophores. The possibility that regulation of lipid metabolism in the rabbit may be a new function acquired by melanotropin is discussed.     

Generation of Transgenic Rats through Induced Pluripotent Stem Cells

The rat is an important animal model for human disease research. Using inhibitors of glycogen synthase kinase 3 and MAPK signaling pathways, rat embryonic stem cells and rat induced pluripotent stem cells (riPSCs) have been derived. However, unlike rat embryonic stem cells, germ line competent riPSCs have only been derived from Wistar rats at low efficiency. Here, we found that an optimized induction medium containing knock-out serum replacement and vitamin C improved the rate and efficiency of riPSCs generation from Dark Agouti rat fibroblasts and Sertoli cells. riPSCs maintained an undifferentiated status for >30 passages and could differentiate into various cells types including germ cells when injected into rat blastocysts. Moreover, transgenic riPSCs could be generated through the PiggyBac transposon, which could be used to generate transgenic rats through germ line transmission. riPSCs can be used as a novel tool in genetic and genomic studies of the rat.     

Isolation and properties of plasma membrane from smooth muscle

A generalized approach to obtain relatively pure fractions of plasma membrane from smooth muscle tissues for studying calcium transport is described. The use of various markers for cellular membranes to establish the purity of various fractions is critically considered. Plasma membranes from rat myometrium have been isolated in a purity estimated to be 95-99%. Plasma membrane purifications to 70-80% have been achieved from rat mesenteric arteries and veins, canine tracheal smooth muscle, rabbit intestinal muscle, rat vas deferens, rat fundus, and dog gastric corpus. The ATP-dependent transport of Ca is correlated with the distribution of plasma membrane markers. Ca gradient of greater than 1000-fold have been achieved. ATP-dependent active Ca transport by plasma membranes could sometimes be stimulated by oxalate or phosphate. Anion activation of Ca active transport is not a marker for endoplasmic reticulum. In some smooth muscles (e.g., rat vas deferens) ATP-dependent Ca uptake did not correlate exclusively with the distribution of plasma membrane markers. Instead, the correlation seemed to be with NADPH-cytochrome reductase EC 1.6.2.5 activity (putative endoplasmic reticulum marker) as well as with plasma membrane markers. In all smooth muscles, active Ca transport appears to be a property of the plasma membrane; in some it may also be a property of the endoplasmic reticulum. Mitochondria actively transport Ca, but in most systems studied to date, the Km for Ca2+ for this transport is higher than that for plasma membrane. Thus the plasma membrane may be the major physiological mechanism of active transport for Ca out of cytoplasm of smooth muscle cells. In two plasma membrane fractions (from rat myometrium and mesenteric arteries) it has been possible to demonstrate the existence of an Na-Ca exchange system. Its contribution to lowering cytoplasmic Ca is unknown.     

Rat tumour necrosis factor-alpha: expression in recombinant Pichia pastoris, purification, characterization and development of a novel ELISA.

Tumour necrosis factor-alpha is a pro-inflammatory cytokine involved in many aspects of acute phase and immune responses. Species specificity in the biological action and receptor binding of TNF-alpha make it desirable to use homologous reagents in experimental models, both in vivo and in vitro. As the rat is the model of choice in many investigations on fever, trauma and pathology, there is a need for specific rat reagents. In this paper, we describe the production of recombinant rat TNF-alpha in milligram quantities, using a methylotrophic yeast expression system, Pichia pastoris. Recombinant TNF-alpha was produced intracellularly in a soluble form, cells were lysed and the protein purified by ammonium sulphate precipitation, Sephadex G75 fractionation and finally, ion-exchange chromatography. The purified recombinant rat TNF-alpha had a molecular mass of 17401.38 +/- 0.38 Da, which is within 1 Da of the value predicted by the sequence data, taking into account N-acetylation of the initial methionine residue and a single disulphide bridge between amino acids 70 and 101. Recombinant rat TNF-alpha was shown to be 20 x fold more biologically active in the WEHI cytotoxicity assay, than the human standard preparation. Polyclonal antibodies were raised against purified recombinant rat TNF-alpha, these reagents were used to develop a novel enzyme-linked immunosorbant assay (ELISA). The ELISA was sensitive to 10 pg.ml- 1 rat TNF-alpha and was specific for TNF-alpha, showing no cross-reactivity with rat IL-1alpha, rat IL-1beta, rat IL-1Ra or rat IL-6. The ELISA was used to measure TNF-alpha in the plasma of rats injected with bacterial endotoxin and in cultures of rat white blood cells. The ELISA was shown to be a robust method suitable for use in assaying samples generated in both in vivo or in vitro experiments.     

Urethral catheterization of the female rat

Urinary tract catheterization of the rat may be required for a variety of clinical and experimental reasons. The external urinary orifice is easily visualized and rests anterior to the vaginal opening, making urinary tract catheterization easier in the female rat than in other species. This column describes a technique for short-term urethral catheterization in the adult female rat.     

Rat platelets contain growth factor(s) distinct from PDGF which stimulate DNA synthesis in primary adult rat hepatocyte cultures

Adult rat hepatocytes in primary cultures are stimulated to synthesize DNA in response to rat serum, whereas rat plasma is considerably less active. Biological activity is present in rat platelets and is secreted during aggregation in response to thrombin. The material secreted by rat platelets is heat labile and is sensitive to digestion with trypsin, suggesting that it is a protein. When assayed on 3T3 cells this material also stimulates DNA synthesis; however, the trypsin-sensitive activity is heat stable (100 degrees C, 10 min). These results indicate that rat platelets contain hepatotrophic activities which by virtue of their heat sensitivity are distinct from heat-stable platelet-derived growth factor (PDGF)-like mitogenic activities required by 3T3 cells for growth. It is possible that hepatotrophic platelet factors might be involved in mediating liver regeneration in the rat after partial hepatectomy.     

Rat sulfite oxidase antibodies cross-react with two gene family-related proteins: albumin and vitamin D-binding protein.

Screening lambda cDNA libraries from rat liver with antibody to native rat liver sulfite oxidase (RLSO) showed cross-reaction with two proteins that belong to the same gene family: serum albumin and vitamin D-binding protein. Antibodies raised against native RLSO or sodium dodecyl sulfate-denatured protein cross-reacted with these proteins by Western blot analysis. The relative effectiveness of RLSO antibody binding was estimated to be 1/5 for rat serum albumin and 1/10 for rat vitamin D-binding protein. This result was not caused by contaminating proteins in the RLSO used for immunization as the RLSO preparation did not react with rat serum albumin antibody. RLSO antibodies, selected for their ability to bind rat serum albumin immobilized on nitrocellulose, recognized both rat serum albumin and RLSO. RLSO antibody, with albumin-reactive antibody removed, still recognized vitamin D-binding protein, suggesting that multiple determinants specific to each protein are involved in the cross-reaction. Comparison of RLSO antibody binding to the rat and human proteins indicated that the determinants were species-specific. cDNA clones identified by screening cDNA libraries with RLSO antibody demonstrated that these determinants reside in the C-terminal domain of these proteins. These results suggest that these proteins contain some common immunological features and may be evolutionarily related.     

Comparison of the steroidogenic and melanotropic activities of corticotropin, α-melanotropin and analogs with their lipolytic activities in rat and rabbit adipocytes

The ability of α-melanotropin and a series of synthetic peptides related to adrenocorticotropin (ACTH) to stimulate steroidogenesis in isolated rat adrenal cells, melanin dispersion in frog melanophores and lipolysis in rat and rabbit fat cells have been studied. It was found that the steroidogenic activity closely paralleled the lipolytic activity of these peptides in rat fat cells, whereas the melanocyte stimulating activity paralleled the lipolytic activity in rabbit fat cells. These results indicate that the structural requirements for stimulating steroidogenesis in isolated rat adrenal cells and lipolysis in isolated rat fat cells are quite similar. The structural features required for wliciting lipolysis in rabbit fat cells appear to be very similar to those necessary for stimulating frog melanophores. The possibility that regulation of lipid metabolism in the rabbit may be a new function acquired ny melanotropin is discussed.     

6-Phosphofructo-1-kinase isoenzymes of the jejunal mucosa of rabbit, rat and mouse

1. 6-Phosphofructo-1-kinase (PFK) isoenzymes were studied in the jejunal mucosa of rabbit, rat and mouse. 2. The rat mucosal enzyme was found to be very similar to, although not identical with, the mouse mucosal enzyme, as the physical and regulatory properties of these two enzymes were nearly similar except that the immunological studies were dissimilar. 3. PFK prepared from rabbit mucosa showed different and distinct properties from the rat and mouse mucosal PFK when studied by (NH4)2SO4-precipitation, polyacrylamide gel electrophoresis, immunological cross-reactivity and regulatory properties. 4. The difference between the rabbit enzyme and the rat or mouse enzymes is suggested to be due to the lower rate of glycolysis observed in the rabbit jejunal mucosa as the total enzyme activities of the rabbit were found to be less than half of those activities of the rat and mouse mucosa. 5. The dissimilarities among the species in mucosal isoenzymes obtained in the present study are rather expected since the term isoenzyme is now properly reserved for forms that have been shown to be genetically distinct as shown for different tissues in the same species. Such multigenic control does not appear to have been established for the same tissue in different species.     

Establishment of a set of combined immunodeficient DA/Slc-Foxn1(rnu) Lyst(bg) congenic rat strains.

The congenitally athymic nude rat is used for studying cancer and transplantation owing to its hairlessness and T-cell defective function caused by the Foxn1(rnu) gene. However, NK cell activity of the nude rat is markedly increased. It is known that NK cells play a major role in rejection of xenografts and in cytotoxicity against tumor cells. Thus, the athymic nude rat with impaired NK cell activity should be a useful model for extensive studies. The DA-Lyst(bg)/Lyst(bg) rat, a model for human Chediak-Higashi syndrome (CHS) is characterized by diluted-coat color and impairment of NK cell activity. We planned to establish a combined immunodeficient double mutant rat introgressed with the Foxn1(rnu) and Lyst(bg) genes and a set of congenic strains having an identical genetic backgrounds simultaneously. Based on the phenotypic and genetic characteristics of the parental rat strains, the new strains were produced using continuous backcross and diagnosis with molecular genetic techniques. Each disease gene was diagnosed with PCR-RFLP or the long-nested PCR method. Furthermore, we used a marker-assisted congenic strategy based on scanning the genetic backgrounds of the parental rats with 461 rat microsatellite markers. We think that the newly established DA/Slc-Foxn1(rnu)/Foxn1(rnu) Lyst(bg)/Lyst(bg) double mutant will be useful as a severe disease model for human CHS, and the set of DA/Slc-Foxn1(rnu) Lyst(bg) congenic strains which have impaired NK cell activity and/or defective T cell function should be useful for studying in cancer research, xenotransplantation, immune function and other wide-ranging studies.     

Evidence for a dimeric structure of rat liver serine dehydratase

Rat liver serine dehydratase (SDH) is known to be involved in gluconeogenesis. It has long been believed to be a dimeric protein with the subunit molecular weight (M(r)) of 34,000. Recently, sheep liver SDH was reported to be a monomer with a M(r) of 38,000. The native M(r) of rat SDH was only determined by the ultracentrifugation method more than three decades ago, and that of sheep SDH was done by the method of gel chromatography. The primary to quaternary structures of a given enzyme in a specific mammalian organ are usually conserved among various species. The aim of the present investigation is to clarify the structural differences between rat and sheep SDHs. First, we found that the amino acid composition reported for sheep SDH was statistically similar to that of rat SDH. Second, immunoblot analysis using anti-rat SDH IgG as the probe showed the size of sheep SDH to be a M(r) of 30,500, whereas that of SDH was about M(r) of 35,000. On the other hand, the native size of rat SDH was assessed by two methods: (1) the laser light scattering method demonstrated that rat SDH had a M(r) of 66,800, consistent with the previous value (M(r)=64,000); (2) cross-linking experiments of the purified rat SDH with dimethyl suberimidate revealed the existence of a dimeric form by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The present results clearly confirm that rat SDH is a dimer, and suggest that sheep SDH is similar to rat SDH immunologically, but with a molecular weight 7500 smaller than reported previously.     

Detection of estrogen receptor (ER) in the rat brain using rat anti-ER monoclonal IgG with the unlabeled antibody method

Application of Sternberger's unlabeled antibody enzyme method for detection of the estrogen receptor (ER) using a rat primary antibody with rat tissues has been discouraged, presumably because nonspecific staining of endogenous IgG was expected with the required anti-rat IgG bridging antibody. Because the blood-brain barrier greatly reduces immunoglobulin infiltration into the brain, we hypothesized that rat brain tissue could be specifically immunostained using rat IgG primary antibodies. A rat monoclonal anti-ER antibody (H222) specifically stained ERs in the brains of ovariectomized but not in ovariectomized estrogen-treated rats. In contrast, the uterus, a well-perfused target organ stained intensely in a nonspecific fashion. Dense populations of estrogen receptors were observed in the medial preoptic area, the bed nucleus of the stria terminalis, and the arcuate and ventromedial nuclei of the hypothalamus. A monoclonal rat IgG directed against alpha-tubulin labeled primarily cortical dendrites quite distinct from the neuronal nuclei that are the primary antigenic sites for the estrogen receptor antibody. These results confirm that the sensitive unlabeled antibody method can be applied to rat brain tissues, even when the primary antibody is rat IgG and that labeling of endogenous IgG may be used as a simple method to evaluate the integrity of the blood brain barrier.     

Detection of estrogen receptor (ER) in the rat brain using rat anti-ER monoclonal IgG with the unlabeled antibody method

Summary Application of Sternberger's unlabeled antibody enzyme method for detection of the estrogen receptor (ER) using a rat primary antibody with rat tissues has been discouraged, presumably because nonspecific staining of endogenous IgG was expected with the required anti-rat IgG bridging antibody. Because the blood-brain barrier greatly reduces immunoglobulin infiltration into the brain, we hypothesized that rat brain tissue could be specifically immunostained using rat IgG primary antibodies. A rat monoclonal anti-ER antibody (H222) specifically stained ERs in the brains of ovariectomized but not in ovariectomized estrogen-treated rats. In contrast, the uterus, a well-perfused target organ stained intensely in a nonspecific fashion. Dense populations of estrogen receptors were observed in the medial preoptic area, the bed nucleus of the stria terminalis, and the arcuate and ventromedial nuclei of the hypothalamus. A monoclonal rat IgG directed against alpha-tubulin labeled primarily cortical dendrites quite distinct from the neuronal nuclei that are the primary antigenic sites for the estrogen receptor antibody. These results confirm that the sensitive unlabeled antibody method can be applied to rat brain tissues, even when the primary antibody is rat IgG and that labeling of endogenous IgG may be used as a simple method to evaluate the integrity of the blood brain barrier.