Single amino acid substitutions in EGF-like elements of Notch and Delta modify Drosophila development and affect cell adhesion in vitro.

Notch locus EGF-like element mutations spl, altering eye development, and AxE2, affecting wing and sensilla development, are modified by mutations at Delta. It is shown that two allele-specific suppressors of spl involve single amino acid substitutions in the 4th (Dlsup5) and 9th (Dlsup4) EGF-like elements of the Delta protein. Cultured cells producing spl or AxE2 aggregate with cells producing wild-type Delta or Dlsup5 protein, and Dlsup5-producing cells adhere to cells producing wild-type Notch protein. However, spl,AxE2, and Dlsup5 are each defective in promoting these cell affinities, as none of the mutant proteins can compete with the corresponding wild-type proteins for formation of cell aggregates. Thus, widely separated EGF-like elements of Notch and Delta appear to participate in functional molecular interactions between the proteins. Dlsup5 does not improve adhesiveness of spl in vitro, so suppression in vivo may involve altered developmental signaling by spl-Dlsup5 complexes, rather than modified cell adhesion.

Response to Alpha-Interferon Treatment of the Congenital Dyserythropoietic Anemia type I in Two Sicilian Beta Thalassemia Carriers.

Congenital dyserythropoietic anemia type I (CDAI) is an autosomal recessive inherited haematological disorder associated with moderate-to-severe anemia characterized by ineffective erythropoiesis with distinct morphological abnormalities in erythroid precursors. We present two case of congenital dyserythropoietic anemia type I in two Sicilian patients heterozygous for ß0 39 globin gene cod 39 C > T with marked bone marrow abnormalities, responding to treatment with alpha interferon. The diagnosis was established using routine haematological and biochemical test, light and electron microscopy; molecular analysis of the CDAN1 gene associated to the CDAI disease was performed. The response to the treatment was monitored using the hemoglobin levels, the red cell count, the reticulocyte count and the transfusional requirement. This report points out the usefulness of the treatment with interferon alpha in two Sicilian beta thalassemia carriers, in which the therapy was well tolerated without producing any side effects; in these patients the transfusion requirements after the initiation of interferon therapy decreased.

Antineurogenic phenotypes induced by truncated Notch proteins indicate a role in signal transduction and may point to a novel function for Notch in nuclei.

Loss of any one of several neurogenic genes of Drosophila results in overproduction of embryonic neuroblasts at the expense of epidermoblasts. In this paper a variety of altered Notch proteins are expressed in transgenic flies. Dominant lethal, antineurogenic phenotypes were produced by expression of three classes of mutant proteins: (1) a protein comprised of the cytoplasmic domain of Notch and devoid of sequences permitting membrane association; (2) a transmembrane protein lacking the extracellular, lin12/Notch repeats; and (3) transmembrane proteins carrying amino acid substitutions replacing one or both extracellular cysteines thought to be involved in Notch dimerization. These Notch proteins not only suppress the neural hypertrophy observed in Notch- embryos, but also generate a phenotype in which elements of the embryonic nervous system are underproduced. Action of the intracellular cdc10 repeats appears to be essential for wild-type Notch function or for the antineurogenic activity of these proteins. The activities of the dominant, gain-of-function proteins indicate that Notch functions as a signal transducing receptor during ectoderm development. Production of antineurogenic Notch proteins in embryos deficient for the other neurogenic genes allowed functional dependencies to be established. Delta, mastermind, bigbrain, and neuralized appear to function in elaboration of a signal upstream of Notch. Genes of the Enhancer of split complex act after Notch. The cytoplasmic domain of Notch contains nuclear localization sequences that function in cultured cells, and one of the Notch antineurogenic proteins, the cytoplasmic domain, accumulates in nuclei in vivo.

A role for the Drosophila neurogenic genes in mesoderm differentiation.

The neurogenic genes of Drosophila have long been known to regulate cell fate decisions in the developing ectoderm. In this paper we show that these genes also control mesoderm development. Embryonic cells that express the muscle-specific gene nautilus are overproduced in each of seven neurogenic mutants (Notch, Delta, Enhancer of split, big brain, mastermind, neuralized, and almondex), at the apparent expense of neighboring, nonexpressing mesodermal cells. The mesodermal defect does not appear to be a simple consequence of associated neural hypertrophy, suggesting that the neurogenic genes may function similarly and independently in establishing cell fates in both ectoderm and mesoderm. Altered patterns of beta 3-tubulin and myosin heavy chain gene expression in the mutants indicate a role for the neurogenic genes in development of most visceral and somatic muscles. We propose that the signal produced by the neurogenic genes is a general one, effective in both ectoderm and mesoderm.

Targeted mutation of TNF receptor I rescues the RelA-deficient mouse and reveals a critical role for NF-kappa B in leukocyte recruitment.

NF-kappaB binding sites are present in the promoter regions of many acute phase and inflammatory response genes, suggesting that NF-kappaB plays an important role in the initiation of innate immune responses. However, targeted mutations of the various NF-kappaB family members have yet to identify members responsible for this critical role. RelA-deficient mice die on embryonic day 15 from TNF-alpha-induced liver degeneration. To investigate the importance of RelA in innate immunity, we genetically suppressed this embryonic lethality by breeding the RelA deficiency onto a TNFR type 1 (TNFR1)-deficient background. TNFR1/RelA-deficient mice were born healthy, but were susceptible to bacterial infections and bacteremia and died within a few weeks after birth. Hemopoiesis was intact in TNFR1/RelA-deficient newborns, but neutrophil emigration to alveoli during LPS-induced pneumonia was severely reduced relative to that in wild-type or TNFR1-deficient mice. In contrast, radiation chimeras reconstituted with RelA or TNFR1/RelA-deficient hemopoietic cells were healthy and demonstrated no defect in neutrophil emigration during LPS-induced pneumonia. Analysis of RNA harvested from the lungs of mice 4 h after LPS insufflation revealed that the induction of several genes important for neutrophil recruitment to the lung was significantly reduced in TNFR1/RelA-deficient mice relative to that in wild-type or TNFR1-deficient mice. These results suggest that TNFR1-independent activation of RelA is essential in cells of nonhemopoietic origin during the initiation of an innate immune response.

First trimester fetal blood sampling.

The authors report 8 diagnostic cordocentesis performed at the end of the first trimester. The indication was thalassemia (5 cases) and karyotyping (3 cases). The technique requires that the operator holds both the probe and the needle (25 G X 90 mm); the fetal blood sample ranged between 0.25 and 0.35 cc, sufficient in all cases for the diagnosis. 1 pregnancy was terminated on the basis of the diagnostic result; no complications reported at a 3-weeks follow-up in the remaining 7 patients. The first trimester cordocentesis offers several advantages if compared to CVS, especially for thalassemia prenatal diagnosis; furthermore it opens new perspectives for intrauterine transplantations. More experience is required to assess the safety of the procedure.

Simultaneous detection of fourteen Italian cystic fibrosis mutations in seven exons by reverse dot-blot analysis.

The increasing number of cystic fibrosis (CF) mutations is a great obstacle to the use of DNA procedures in the detection of gene defects. We describe a fast, cheap and non-radioactive procedure, Reverse dot-blot analysis (RDB), for the simultaneous detection of CF mutations in the Italian population. We used this approach to study seven exons of the CF gene for 14 CF gene defects and were able to characterize 222 of 272 CF chromosomes (80%). The cost of the procedure was $25 per sample analysed.

Prenatal diagnosis of haemoglobin disorders by cordocentesis at 12 weeks' gestation.

Prenatal diagnosis of haemoglobin disorders is accepted to be a useful procedure to avoid births of infants with homozygous diseases. Advances in sampling and molecular techniques, such as polymerase chain reaction (PCR) and chorionic villus sampling (CVS), have made earlier and safer first-trimester prenatal diagnosis possible. However, these procedures need previous studies of at-risk couples, which can be very time-consuming when a number of different beta-thalassaemia mutations occur in the region. We describe the possibility of making a first-trimester prenatal diagnosis by cordocentesis and fetal blood analysis at the 12th week of gestation. We found no statistically significant difference (p greater than 0.05) between beta/gamma values in fetuses at the 12th and 18th weeks of gestation. In seven affected fetuses aborted at the 12th week of gestation, the diagnosis was confirmed in all cases by PCR analysis. These findings suggest that early cordocentesis could be an alternative procedure to CVS and PCR analysis.

Analysis of linkage disequilibrium between different cystic fibrosis mutations and three intragenic microsatellites in the Italian population.

Three intragenic microsatellites of the CFTR gene, a TA and a CA repeats, namely IVS17bTA and IVS17bCA, located in intron 17b and a CA repeat (IVS8CA) located in intron 8 of the CFTR gene, were analyzed in a large sample of Italian cystic fibrosis (CF) and normal chromosomes. Linkage disequilibrium was evaluated between each marker and difference CF mutations on a total of 377 CF and 358 normal chromosomes. Our results are consistent with the hypothesis that all delta F508 chromosomes derive from a single mutational event. The same hypothesis is valid for mutations G542X, N1303K, 1717-1G-->A, which might have been originated more recently than delta F508.