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Biomedical subjects

G Ghersi

Publications and source records attributed to G Ghersi.

12 recordsLinked to original sources
PubMed1994

Spatial distribution of two maternal messengers in Paracentrotus lividus during oogenesis and embryogenesis.

We demonstrated that two mRNAs that are synthesized during the vitellogenic period of oogenesis and that code for cell surface proteins are asymmetrically distributed in the unfertilized egg of Paracentrotus lividus. At fertilization, these RNAs rapidly localize in the cortical zone at the animal pole of the egg. They are then detected in the mesomeres and the macromeres, but not in the micromeres, and thereafter are found in the ectoderm but not in the vegetal plate, mesenchyme cells, or early intestine. They disappear in late gastrula. The proteins synthesized by these mRNAs show the same territorial location during the period examined here, which included the unfertilized egg and the 16-blastomere stage. These conclusions were reached on the basis of in situ hybridization and immunostaining experiments, as well as Northern and Western blot analyses of isolated blastomeres. The possible significance of this asymmetric distribution of these two mRNAs and proteins in the establishment of the animal/vegetal axis is discussed.

Animals↗
PubMed1994

Human breast carcinoma cells cultured in the presence of serum shed membrane vesicles rich in gelatinolytic activities.

Human breast carcinoma cell lines, 8701-BC and MCF-7, in culture shed membrane vesicles with similar morphology. Vesicles shed in the presence of serum were rich in gelatinolytic activities, but not those obtained in the absence of serum. Zymographic analyses of the vesicles from 8701-BC and MCF-7, using gelatin as substrate, showed three predominant activities at 68-kDa, 97-kDa, and above 200-kDa. The ratio of the three activities was similar in the vesicles recovered from the two cell lines, but the vesicles from 8701-BC cells contained greater amounts of activities than those from MCF-7 cells. Optimal pH and sensitivity to protease inhibitors suggest that all gelatinolytic activities detected in vesicles are metalloproteinases. Treatment of the vesicles extracts with 4-aminophenylmercuric acetate and comparison with the purified enzyme indicate that 97-kDa gelatinase is the precursor of matrix metalloproteinase-9 (gelatinase B). These results support the early hypothesis that vesicle shedding from the plasma membrane may participate in metastatic cascade of cancer cells.

Blood Proteins↗
PubMed1994

Identification of a protein encoded by a mouse simple repeated sequence.

In order to study the possibility that a mouse repeated 'simple sequence', containing an ORF, could encode a protein, we inserted a fragment of a cDNA clone into the expression vector pEX31C. The fragment containing the short sequence 'CAGAGAGG' was expressed as MS2 polymerase fusion protein in Escherichia coli. This fusion protein (H5fp) was injected subcutaneously into rabbit and the corresponding polyclonal antibodies generated. Western blot analysis of proteins extracted from different mouse tissues established that anti H5fp antibodies recognized, in vivo, an antigen of 28 KDa. Immunolocalization with anti H5fp antibodies showed the presence of the related antigen in the cytoplasm of the examined sections. An hypothetical secondary structure for the protein was predicted by the Chou and Fasman method.

Amino Acid Sequence↗
PubMed1994

An epidemic of tuberculosis in an elementary school, Sanremo, Italy, 1993.

In late 1992, three cases of tuberculosis were identified in school children attending a small elementary school in Sanremo, Italy. In order to identify further cases and determine the source, an epidemiologic investigation was undertaken. Tine test and X rays were performed on all students and school personnel. A total of 80% of the 59 students in the school had positive tine test reactions, as did 100% of the 12 teachers. All but one of the positive students had converted since last tested, as had the nine teachers who had been previously negative. The source of the outbreak was a teacher who had been in direct classroom contact with two of the five classes and had worked closely with the rest in building of a Christmas creche for the school. This outbreak suggests that increasing attention should be paid to school as potential foci for the spread of tuberculosis and that greater attention be paid to teacher screening, particularly in areas of higher tuberculosis prevalence.

Adult↗
PubMed1993

Differential expression and function of cadherin-like proteins in the sea urchin embryo.

Cadherins are Ca(+2)-dependent cell surface proteins involved in the specification of the adhesive properties of cells. They are supposed to play a critical role in morphogenesis and pattern formation. In this paper we show that in the sea urchin embryo there are at least two different cadherins of relative molecular masses 140 and 125 kDa. The 140 kDa cadherin is already present in the fertilized egg and is the sea urchin equivalent of E-cadherin. The 125 kDa cadherin, which can be detected using a broad-spectrum anti-cadherin antibody, appears only at later stages of development. In later embryos these two molecules are distributed differently: E-cadherin is present predominantly in the invaginating endoderm of the gastrula while the 125 kDa protein is present on the cell surface of most epithelia. Consistently with the observed differences in expression and in distribution, antibodies directed against these two cadherins differently perturb sea urchin development. For example, when these antibodies are added to early gastrulas only the antibodies against the 125 kDa component can induce a complete disaggregation of the ectoderm, while anti E-cadherin antibodies induce an abnormal development of the endoderm while the embryo maintains its basic integrity. These results are discussed in view of the need for multiple adhesion receptors during pattern formation and embryogenesis.

Animals↗
PubMed1992

An acid extract from dissociation medium of sea urchin embryos, induces mesenchyme differentiation.

When material extracted by 1 M acetic acid from the dissociation medium of sea urchin embryos is added at low concentrations to isolated primary mesenchyme cells, it induces skeletogenesis. The same material added to dissociated blastula cells, or to embryos at the blastula stage, stimulates skeleton formation and pigment cell differentiation. On dissociated cells, it also increases cell reaggregation, thymidine incorporation and survival. On embryos, it induces exogastrulation and appearance of extraembryonic pigment cells. The activity of the extract is resistant to raised temperatures and partially to tryptic digestion but is abolished by trypsin treatment followed by heating. The active fraction does not readily filter through Amicon XM-50 and is retarded by column chromatography on Bio-Gel P-60.

Animals↗
PubMed1992

Characterization of bep1 and bep4 antigens involved in cell interactions during Paracentrotus lividus development.

We have identified and partially characterised two antigens, extracted with 3% butanol, from Paracentrotus lividus embryos dissociated at the blastula stage, and encoded by the cDNA clones previously described as bep1 and bep4 (bep-butanol extracted proteins). The cDNA fragments containing the specific central portions of bep1 and bep4 were expressed as MS2 polymerase fusion proteins in Escherichia coli. These two fusion proteins, called 1C1 (bep1) and 4A1 (bep4), were injected subcutaneously into rabbits and the corresponding polyclonal antibodies generated. Western blot analysis of proteins, extracted with 3% butanol, from sea urchin embryos at the blastula stage (b.e.p.), established that both antibodies recognize two 33 KDa proteins. Reducing and non-reducing electrophoretic conditions show that both antibodies against bep1 and bep4 related proteins react also with a protein band of a molecular weight 66 KDa, indicating that these two antigens probably exist as dimers. Immunolocalization with anti 1C1 and 4A1 antibodies shows the presence of the related antigens also on the cell surface. Fab fragments of the polyclonal antibodies against 1C1 and 4A1 inhibited reaggregation of sea urchin embryonic cells, dissociated from blastula stage embryos. This prevention of reaggregation indicates that these proteins probably play a role in cell interaction during sea urchin embryonic development.

Animals↗
PubMed1990

Immunological evidence for the presence in sea urchin embryos of a cell adhesion protein similar to mouse uvomorulin (E-cadherin).

A tryptic fragment (88 kDa), obtained from external digestion of sea urchin embryos carried out in the presence of calcium, shows immunological cross-reactivity with polyclonal and monoclonal antibodies (DECMA-1) against mouse teratocarcinoma uvomorulin. Fab fragments obtained from anti-mouse terato-carcinoma uvomorulin mono- and polyclonal antibodies, and from polyclonal antibodies against the partially purified 88-kDa tryptic fragment, decompact early sea urchin embryos and block reaggregation of dissociated sea urchin blastula cells. These data indicate the presence of an uvomorulin-like protein in sea urchin embryos and suggest an important role for this protein in embryonic development.

Animals↗
PubMed1989

Direct adhesion to type I and homotrimer collagens by breast carcinoma and embryonic epithelial cells in culture: a comparative study.

A continuous cell line of neoplastic cells derived from ductal infiltrating carcinoma of the human breast (8701-BC), was assayed for its ability to adhere to collagen substrates. The collagens used were regular type I and type I homotrimer isolated from primary breast carcinomas. Comparative studies were performed using an embryonic epithelial cell line derived from human intestine (Int. 407). The neoplastic cells adhere equally well to both collagens, while the embryonic epithelial cells recognized only the homotrimer. Some receptor diversity was recognized in the adhesion of the two cell lines to homotrimer collagen. The data demonstrate a functional difference between type I and homotrimer collagen with regard to cellular recognition and attachment. In addition, the data suggest that oncogenic transformation of breast epithelial cells promotes their adhesive properties to interstitial collagens and that this may be relevant to their increased potential to invade host tissue.

Breast Neoplasms↗