Isolation and characterization of a sea urchin hsp 70 gene segment

Three clones containing Paracentrotus lividus sea urchin DNA sequences which cross-hybridize to Drosophila heat shock protein (hsp) 70 gene were isolated. The sequence arrangements in the three cloned DNA inserts were compared by restriction and cross-hybridization analysis. The results showed that they contain four different genes related to one Drosophila hsp 70 gene. One of these genes was subcloned, and two of the isolated fragments were shown to hybridize to genomic DNA and to RNA from heat-treated sea urchin embryo.     

Slow electromagnetic solitons in electron-ion plasmas

A set of nonlinear differential equations that describe moving relativistic solitons is investigated analytically and solved numerically. The influence of the ion motion on the soliton structure is investigated. It is demonstrated that, depending on the propagation velocity, relativistic solitary waves can occur in the form of bright solitons, dark solitons, or collisionless electromagnetic shock waves. In the limit of a low propagation velocity, a dark soliton can trap the ions and accelerate them. In the case of a bright soliton, the effects of ion dynamics limit the soliton amplitude. The constraint on the maximum amplitude is related to either the breaking of ion motion or the intersection of electron trajectories. The soliton breaking provides a new mechanism for ion and electron acceleration in the interaction of high-intensity laser pulses with plasmas.     

Effect of bleomycin on DNA-dependent RNA polymerase purified from normal and neoplastic tissues

The effect of bleomycin was investigated using two forms of DNA-dependent RNA polymerase (A and B) purified from normal tissues and experimental tumours in presence either of Mn2+ or Mg2+ and native or denatured homologous DNA. THe results show that the antibiotic inhibits the enzyme activity of both classes, and the degree of inhibition appears to be influenced by the nature of cation, the highest values being reached with Mg2+. Moreover, the denaturation of DNA modify the bleomycin effect significantly. With regard to cellular damage induced by the drug, the data here reported show that there is not a substantial difference between normal and tumour tissues.     

Defective apoptosis as potential mechanism in the tumorogenesis of myelolipoma.

Apoptosis is considered an important mechanism of selective deletion that occurs during hematopoiesis. Myelolipoma is a rare benign tumor composed of adipose tissue and hematopoietic cells. The pathogenesis of this benign tumor is still unclear. Analysing the structural levels and apoptosis of normal human bone marrow (NHBM) and human myelolipoma (HM), the apoptotic events resulted abundantly present in NHBM compared to HM, which showed a small number of apoptotic cells. By contrast, Fas expression was strongly present both in NHBM and HM. These findings suggest that an altered function of Fas in myelolipoma is not able to trigger the apoptotic machinery. In conclusion, we hypothesize that drastic reduction of apoptosis in myelolipoma can be considered one of the growth regulatory mechanisms.