Isolation and partial characterization of “galactoprotein a” (LETS) and “galactoprotein b” from hamster embryo fibroblasts

The cell surface glycoproteins of hamster NIL cells, labeled with galactose oxidase and NaB³H4, were selectively solubilized by sequential extraction with Tris buffer containing 1) sucrose-ATP-EDTA, 2) zwitterionic detergent (Empigen BB), and 3) 8 M urea. The previously reported “galactoprotein b” $\text{(Gap b)}$ and “galactoprotein a” ($\text{Gap a}$ or LETS) were isolated by affinity chromatography on insoluble Ricinus communis lectin colums (RCA column) from extracts 2) and 3), respectively. The affinity-purified $\text{Gap a}$ contained an actin-like protein, whereas the other affinity-purified galactoproteins did not contain the actin-like protein. The isolated $\text{Gap b}$ was heterogeneous, and an additional glycoprotein, specific for NILpy cells was copurified on RCA-column with $\text{Gap b}$.     

Isolation of galactoprotein a from hamster embryo fibroblasts and characterization of the carbohydrate unit.

A major cell surface labeled glycoprotein of hamster embryo fibroblasts, with a subunit molecular weight of 230 000, which is deleted on viral transformation [Gahmberg, C. G., & Hakomori, S. (1973) Proc. Natl. Acad. Sci. U.S.A. 70, 3329--3333; Hynes, R. O. (1973) Proc. Natl. Acad. Sci. U.S.A. 70, 3170--3174], was quantitatively extracted and purified on an insolubilized Ricinus communis lectin--poly(acrylhydrazido)agarose column. A glycopeptide with a molecular weight of 2000 was isolated from the glycoprotein after exhaustive digestion with protease of Streptomyces griseus. The carbohydrate structure of the isolated glycopeptide was determined, as seen in Figure 7, by carbohydrate analysis, stepwise degradation by exoglycosidases followed by hydrolysis with endo-beta-N-acetylglucosaminidase of Diplococcus pneumoniae, methylation analysis with gas chromatography--mass spectrometry, and direct probe mass spectrometry of the methylated core oligosaccharide, released by endo-beta-N-acetylglucosaminidase.     

Identification of human galactoprotein b3, an oncogenic transformation-induced membrane glycoprotein, as VLA-3 alpha subunit: the primary structure of human integrin alpha 3.

Galactoprotein b3 is one of the cell membrane glycoproteins of fibroblasts showing enhanced expression in association with oncogenic transformation. Analysis of cDNA for this glycoprotein from hamster fibroblasts indicated that the glycoprotein is a member of the integrin superfamily [Tsuji, T., Yamamoto, F., Miura, Y., Takio, K., Titani, K., Pawar, S., Osawa, T., & hakomori, S. (1990) J. Biol. Chem. 265, 7016-7021]. In the present study, we examined the change in the amounts of mRNA for the mouse and human counterparts in fibroblasts after oncogenic transformation by Northern blot analysis using hamster galactoprotein b3 cDNA as a probe. In both human and murine fibroblasts transformed with SV-40, the homologous mRNA to galactoprotein b3 was also found to increase as compared with the progenitor cells. The human homologue of galactoprotein b3 cDNA was cloned from human bladder carcinoma cell line (T24) cDNA library. The cDNA codes for a single polypeptide of which the N-terminal sequence (21 amino acids) is identical with that of human VLA-3 alpha subunit. Based on this sequence identity and the structural similarities (i.e. the positions of most cysteine residues, the presence of a transmembrane domain near the C-terminus and the presence of metal binding sequences) with other integrins so far cloned, we conclude that human galactoprotein b3 is an integrin alpha 3 subunit. The mature integrin alpha 3 polypeptide was composed of 1,019 amino acid residues, and the overall structure was quite similar to the hamster counterpart.(ABSTRACT TRUNCATED AT 250 WORDS)     

Chinchilla "big" and "little" gastrins

Gastrin heptadecapeptides (gastrins I and II which differ in the presence of sulfate on the tyrosine of the latter) have been purified and sequenced from several mammalian species including pig, dog, cat, sheep, cow, human and rat. A 34 amino acid precursor ("big" gastrin), generally accounting for only 5% of total gastrin immunoreactivity, has been purified and sequenced only from the pig, human, dog and goat. Recently we have demonstrated that guinea pig (GP) "little" gastrin is a hexadecapeptide due to a deletion of a glutamic acid in the region 6-9 from its NH2-terminus and that GP "big" gastrin is a 33 amino acid peptide. The chinchilla, like the GP, is a New World hystricomorph. This report describes the extraction and purification of "little" and "big" gastrins from 31 chinchilla antra. Chinchilla "little" gastrin is a hexadecapeptide with a sequence identical to that of the GP and its "big" gastrin is a 33 amino acid peptide with the following sequence: (See text)     

大熊猫团团圆圆

2008年12月23日,备受关注的大熊猫团团圆圆正式从中国保护大熊猫研究中心（以下简称研究中心）雅安碧峰峡基地出发,前往台北市立动物园定居。从中央政府宣布赠台大熊猫开始,历时3年半,经历了重重考验的团团圆圆终于成行,在2008年岁末之际画上了圆满的句号。     

对"扩散"和"渗透"的讨论

自由扩散和协助扩散都是可自由运动的微粒通过热运动而发生的2种过膜扩散．生物体内的渗透是自由水通过生物膜的协助扩散。     

生态学的“教”与“做”的教学模式探讨

根据高等师范院校培养具有创新知识和创新能力的新型人才的办学宗旨．从本校生态学课程开设理论教学学时数少、实验教学刚起步的实情出发,结合生态学基础性强、研究范围广、应用范围宽的学科特点,阐述了在生态学教学中,为了营造良好的生态学学习情境、激发学生的学习兴趣,教师为“教”所进行的筛选课程内容、改进教学方法和构建新的实验体系与培养学生探究应用能力即“做”的教学模式探讨与体会。     

Distinguishing "or" from "and" and the case for historical identification

The adequacy of a probabilistic interpretation must be judged according to the nature of the event, or thing, being inferred. For example, conditional (frequency) probability is not admissible in the inference of phylogeny, because basic statements of common ancestry do not fulfill the requirements of the relations specified by the probability calculus. The probabilities of the situation peculiar to the time and place of origin of species are unique. Moreover, according to evolutionary theory, an event of species diversification is necessarily unique, because species are parts of a replicator continuum—species arise from ancestral species. Also, these probabilities cannot be ascertained, because the relevant situation cannot be repeated—it is unique. Finally, the applicability of conditional (frequency) probability is denied, because events of common ancestry have already occurred—there is nothing to predict. However, hypotheses of species relationships can be identified objectively according to the degree to which they have survived simultaneous testing with critical evidence, not with generally confirming evidence. The most parsimonious hypothesis of species relationships represents the least disconfirmed, best supported, proposition among the alternatives being compared. That hypothesis does not, however, deserve any special epistemological status beyond serving as the focus of the next round of testing.