Effect of the genelethal (1) myospheroid onDrosophila embryonic cells in vitro

Summary The mutationlethal (1) myospheroid causes death in affectedDrosophila melanogaster embryos. The action of this gene was investigated by culturing normal and mutant embryonic cells in vitro. Under these culture conditions, normal myoblasts and neuro-blasts differentiated to yield myocytes and neurons. The action of the mutant gene was manifested in an altered differentiation of at least two cell types, myocytes and neurons. It prevented differentiation of all myocytes and a fraction of the neurons in vitro. Failure of these cells to differentiate in vitro suggests that the mutation affects the integrity of myocytes and neurons in vivo and contributes to themyospheroid lethal effect. Supported by National Institutes of Health Grants AI05038 and NS09330 to R.L.S.     

The biological function of a fragment of the neurotrophic factor from pigment epithelium: Structural and functional homology with the differentiation factor of the HL-60 cell line

It was shown that the full-size neurotrophic factor from pigment epithelium (PEDF) induces the cell differentiation of the human promyelocyte leukemia cell line HL-60. A structural analysis of PEDF revealed in itsC-terminal region a six-membered peptide fragment PEDF-(352-357) (PEDF-6) whose sequence is highly homologous to the 41–46 fragment of the active site of the human leukocyte differentiation factor HLDF (HLDF-6). The biological effect of PEDF and synthetic peptides PEDF-6 and HLDF-6 on the HL-60 cells and the early gastrula ectoderm ofXenopus laevis embryos was studied. On the basis of the structural and functional homologies of HLDF, PEDF, and their homologous peptides and the computer models of the spatial structures of the full-size PEDF and the PEDF with theC-terminal fragment split off tby the cleavage of the Leu³⁸⁰-Thr³⁸¹ bond in the serpin loop, a hypothesis on the functional role of the serpin loop in PEDF was put forward.     

Closing remarks

Closing remarks to Human genetics - uncertainties and the financial implications ahead. A Discussion held at the Royal Society on 25 and 26 September 1996, and organized and edited by R. M. Anderson. <br>     

Growth plate compressions and altered hematopoiesis in collagen X null mice

A variable skeleto-hematopoietic phenotype was observed in collagen X null mice which mirrored the defects in transgenic (Tg) mice with dominant interference collagen X mutations (Jacenko, O., P. LuValle, and B.R. Olsen. 1993. Nature. 365:56-61). Specifically, perinatal lethality was seen in approximately 10.8% of null mutants at week three after birth, and in another subset by 12 wk. In perinatal lethal mutants, growth plates were compressed, trabecular bone reduced, and hematopoietic aplasia and erythrocyte-filled vascular sinusoids were apparent in marrows. Lymphatic organs, reduced to approximately 80% that of controls, displayed altered architecture and lymphocyte content. In thymuses, a paucity of cortical CD3(+)/CD4(+)/CD8(+) lymphocytes was consistent with the marrow's inability to replenish maturing T cells. In spleens, an unaltered T cell distribution was coupled with diffuse staining for IgD(+)/B220(+) B cells, whose reduction was prominent in poorly organized lymphatic nodules. Disorderly arrays of splenic macrophages surrounding periarteriolar lymphatic sheaths and a red pulp depletion further complemented the Tg perinatal lethal phenotype. Moreover, subtle growth plate compressions and hematopoietic changes were seen in all null mice. Data from Tg and null mice implicate the disruption of collagen X function in the observed skeleto-hematopoietic defects, and suggest that hypertrophic cartilage and endochondral skeletogenesis may contribute to the marrow microenvironment prerequisite for blood cell differentiation.     

Chemistry and structure of skeletal growth rings in the black coral Antipathes fiordensis (Cnidaria,Antipatharia)

The skeleton of the black coral Antipathes fiordensis is a laminar structure displaying major and minor growth rings. The skeleton is composed primarily of protein and chitin organized into successive microlayers. Each microlayer is tightly bound to the next by an organic cement that is periodically opaque in section, and occurs as clusters throughout the skeleton. In contrast, the skeletal microlayers themselves are never opaque. The apposition of multiple, opaque cement lines between skeletal layers is primarily responsible for the growth ring pattern.     

成体干细胞的可塑性研究进展

人们传统观念认为成体干细胞局限于生成它们所在组织的分化细胞类型。但近年来的实验结果表明,从一个组织来的成体干细胞能被诱导分化成另外的一个组织的分化细胞,即成体干细胞具有可塑性。在此,我们对成体干细胞可塑性的证据、几种假设、调控机制和应用前景等方面做一综述。     

Histological changes during development of the cerebellum in the chick embryo exposed to a static magnetic field

Few studies have been performed to evaluate the ultrastructural changes that exposure to static magnetic fields (SMF) can cause to the processes of cell migration and differentiation in the cerebellum during development. Thus, we have studied the development of the cerebellum in the chick embryo (n = 144) under a uniform SMF (20 mT). All of our observations were done on folium VIc of Larsell's classification. The cerebella of chick embryos, which were exposed solely on day 6 of incubation and sacrificed at day 13 of incubation [short exposure (S)1; n = 24], showed an external granular layer (EGL) that was less dense than the EGL in the control group (n = 24). The molecular layer (ML) exhibited a low number of migratory neuroblastic elements. Moreover, the internal granular layer (IGL) was immature, with the cellular elements less abundant and more dispersed than in controls. In chick embryos exposed on day 6 of incubation and sacrificed at day 17 (S2; n = 24), the outstanding feature was the regeneration of the different layers of the cerebellar cortex. The cerebellar cortex of chick embryos exposed continuously to an identical field from the beginning of the incubation up to day 13 [long exposure (L)1; n = 24] or day 17 (L2; n = 24) of incubation showed a higher number of alterations than that of group S1. Electron microscopy confirmed the findings from light microscopy and, at the same time, showed clear signs of cell degeneration and delay in the process of neuronal differentiation. This was more apparent in groups L1 (100%) and L2 (100%) than in groups S1 (95.4%) and S2 (65.2%). In conclusion, the present study showed that SMF can induce irreversible developmental effects on the processes of cell migration and differentiation of the chick cerebellar cortex. Bioelectromagnetics 18:36–46, 1997. © 1997 Wiley-Liss, Inc.     

人羊膜间充质细胞具有向心肌样细胞分化的特性

摘 要 探讨人羊膜间充质细胞（human amniotic mesenchymal cells,hAMCs）向心肌细胞分化的能力。采用胶原酶消化法分离hAMCs,用流式细胞仪进行表型鉴定;用5-氮杂胞苷和碱性成纤维细胞生长因子（basic fibroblast growth factor,bFGF）诱导hAMCs向心肌细胞分化,免疫荧光染色法检测诱导后细胞中特异蛋白结蛋白和α-辅肌动蛋白的表达,RT-PCR检测心肌特异性转录因子Nkx2.5 、GATA-4和心肌特异性收缩蛋白α-肌球蛋白重链（α-myosin heavy chain,α-MHC）mRNA的表达。结果显示：①hAMCs原代培养至第6 d,贴壁细胞汇合度可达80%,呈漩涡状生长。传代后hAMCs增殖迅速,3~4 d细胞汇合度可达100%,细胞呈梭形或多角形。②hAMCs表达CD44和波形蛋白,不表达CK19。③hAMCs经诱导分化8~10 d后细胞排列紧密,多为长梭形。③hAMCs诱导2 w和4 w表达α-辅肌动蛋白和心肌特异性转录因子Nkx2.5。④诱导前后的hAMCs均表达结蛋白和GATA-4,但均未见α-MHC表达。说明hAMCs具有向心肌样细胞分化的能力,可望成为细胞心肌成形术（cellular cardiomyoplasty,CCM）的候选细胞。     

成体干细胞研究进展

近年来由于成体干细胞研究技术的突破 ,成体干细胞的多向分化潜能日益为人们所关注。尤其“横向分化”的发现 ,不仅更新了对成体干细胞的传统认识 ,而且为其临床疾病治疗奠定了基础。介绍了成体干细胞的特点及分化潜能 ,并对其临床应用作了概括性讨论。