Activation of muscle-specific actin genes in Xenopus development by an induction between animal and vegetal cells of a blastula

Muscle gene expression is induced a few hours after vegetal cells of a Xenopus blastula are placed in contact with animal cells that normally develop into epidermis and nerve cells. We have used a muscle-specific actin gene probe to determine the timing of gene activation in animal-vegetal conjugates. Muscle actin RNA is first transcribed in a minority of animal cells at a stage equivalent to late gastrula. The time of muscle gene activation is determined by the developmental stage of the responding (animal) cells, and not by the time when cells are first placed in contact. The minimal cell contact time required for induction is between 1 1/2 and 2 1/2 hr, and the minimal time for gene activation after induction is 5-7 hr.     

Stage-specific expression of two neighboring Crlz1 and IgJ genes during B cell development is regulated by their chromatin accessibility and histone acetylation

The IgJ gene is expressed in the plasma cell stage. However, its neighboring charged amino acid-rich leucine zipper 1 (Crlz1) gene, which is mapped 30 kb upstream of the IgJ gene in mice, is shown to be expressed in the pre-B cell stage. These stage-specific expressions of two neighboring genes are found to be regulated by their chromatin accessibility and acetylation. Hypersensitive site 1 on the IgJ promoter is opened in the plasma cells, whereas hypersensitive sites 9/10 on the Crlz1 promoter are opened in the pre-B cells. Furthermore, H3 and H4 histones toward the chromatin of the Crlz1 gene are found to be hyperacetylated, especially on H3, in the pre-B cells, whereas those toward the chromatin of the IgJ gene are found to be hyperacetylated in the plasma cells. Consistently, the hyperacetylation of H3 and H4 toward the chromatin of the IgJ gene but not the Crlz1 gene is induced by an IL-2 treatment of BCL1, which is a model cell line for studying the terminal differentiation of B cells.     

小麦HMW-GS1Dx5基因的克隆及其特异性表达

显微切割了普通小麦钢８２－１２２（Ｔｒｉｔｉｃｕｍａｅｓｔｉｖｕｍ２ｎ＝４２）具有１Ｄｘ５＋１Ｄｙ１０亚基的１Ｄ染色体长臂端,利用ＰＣＲ扩增得到了ＨＭＷ－ＧＳ１Ｄｘ５亚基的５（端４００ｂｐ序列片段．以此作为探针从基因的组织特异性和特定发育阶段的表达两个方面研究了ＨＭＷ－ＧＳ１Ｄｘ５基因表达的规律．结果表明,干种子及萌发种子中存在此基因,而在发育的幼苗中此基因未表达．ＨＭＷ－ＧＳ１Ｄｘ５基因可能从开花初期开始表达．ＨＭＷ－ＧＳ１Ｄｘ５基因在籽粒成熟期表达,然而在营养器官如叶片中未表达,其表达存在组织特异性．ＨＭＷ－ＧＳ１Ｄｘ５基因在蜡熟期籽粒表达水平最高,其次是乳熟期籽粒．从开花１５ｄ至蜡熟期籽粒,表达趋于增加．开花１５ｄ其ｍＲＮＡ水平是蜡熟期籽粒ｍＲＮＡ的２８％,灌浆期为４０％、乳熟期为７２％、完熟期为５４％．这为进一步研究其表达调控和改善小麦品质打下基础     

Trophectoderm-specific expression of the X-linked Bex1/Rex3 gene in preimplantation stage mouse embryos

The Bex1/Rex3 gene was recently identified as an X-linked gene that is differentially expressed between parthenogenetic and normal fertilized, preimplantation stage mouse embryos. The Bex1/Rex3 gene appears to be expressed preferentially from the maternal X chromosome in blastocysts, but from either X chromosome in later stage embryonic tissues and adult tissues. To investigate whether differential expression of the Bex1/Rex3 gene between normal and parthenogenetic blastocyst stage embryos reflects genomic imprinting at the Bex1/Rex3 locus itself, or instead is the result of preferential inactivation of the paternal X chromosome or differences in timing of cellular differentiation, we examined in detail the expression pattern of the Bex1/Rex3 mRNA in normal preimplantation stage embryos, and compared its expression between androgenetic, gynogenetic, and normal fertilized embryos. Expression data reveal that the Bex1/Rex3 gene is initially transcribed at the 2-cell stage, transiently induced at the 8-cell stage, and then increases in expression again at the blastocyst stage. Very little expression is observed in isolated inner cell masses, indicating selective expression in the trophectoderm. Comparisons of Bex1/Rex3 mRNA expression between male and female androgenetic and control embryos and gynogenetic embros failed to reveal any significant difference in expression between the different classes of embryos at the 8-cell stage, or the expanding blastocyst stage (121 hr post-hCG). At the late blastocyst stage (141 hr post-hCG), expression was significantly lower in XY control embryos as compared with XX controls. Bex1/Rex3 mRNA expression did not differ between XX and XY androgenones at the blastocyst stage or between gynogenones and XX control embryos. Thus, the Bex1/Rex3 gene does not appear to be regulated directly by genomic imprinting during the preimplantation period, just as it is not regulated by imprinting at later stages. Apparent differences in gene expression may arise through the effects of trophectoderm-specific expression coupled with differences in timing of trophectoderm differentiation between the different classes of embryos and effects of preferential paternal X chromosome inactivation (XCI).     

Localization and enzymatic activity profiles of the proteases responsible for tachykinin-directed oocyte growth in the protochordate, Ciona intestinalis

We previously substantiated that Ci-TK, a tachykinin of the protochordate, Ciona intestinalis (Ci), triggered oocyte growth from the vitellogenic stage (stage II) to the post-vitellogenic stage (stage III) via up-regulation of the gene expression and enzymatic activity of the proteases: cathepsin D, carboxypeptidase B1, and chymotrypsin. In the present study, we have elucidated the localization, gene expression and activation profile of these proteases. In situ hybridization showed that the Ci-cathepsin D mRNA was present exclusively in test cells of the stage II oocytes, whereas the Ci-carboxypeptidase B1 and Ci-chymotrypsin mRNAs were detected in follicular cells of the stage II and stage III oocytes. Double-immunostaining demonstrated that the immunoreactivity of Ci-cathepsin D was largely colocalized with that of the receptor of Ci-TK, Ci-TK-R, in test cells of the stage II oocytes. Ci-cathepsin D gene expression was detected at 2h after treatment with Ci-TK, and elevated for up to 5h, and then slightly decreased. Gene expression of Ci-carboxypeptidase B1 and Ci-chymotrypsin was observed at 5h after treatment with Ci-TK, and then decreased. The enzymatic activities of Ci-cathepsin D, Ci-carboxypeptidase B1, and Ci-chymotrypsin showed similar alterations with 1-h lags. These gene expression and protease activity profiles verified that Ci-cathepsin D is initially activated, which is followed by the activation of Ci-carboxypeptidase B1 and Ci-chymotrypsin. Collectively, the present data suggest that Ci-TK directly induces Ci-cahtepsin D in test cells expressing Ci-TK receptor, leading to the secondary activation of Ci-chymotrypsin and Ci-carboxypeptidase B1 in the follicle in the tachykininergic oocyte growth pathway.