Effects of binding three lysine-rich H1-type histones to DNA and poly(dG-dC)

The degree of distortion of the B-form of DNA induced by the binding of the lysine-rich H1 histones is a function of the arginine content of the protein. Lysine-rich H1 histones do not induce the formation of the Z-form of poly(dG-dC) but, when they are bound to this polynucleotide in the B-form, the transition to the Z-form induced by Tb³⁺ is faster.     

Observations on the differentiationin vitro of mouse metanephros

Summary Metanephros of mouse embryos was explanted at the 11th day of gestation and culturedin vitro on the surface of a plasma clot for up to 7 days. Microscopic sections were cut from cultures fixed every day; the differentiation process was followed and compared with development under normal conditions. The ureter branches out and gives rise by means of dichotomous division to straight canals, lined by a light, columnar epithelium, which correspond to collecting ducts. Around the blind ends of their terminal branches, mesenchyme condenses and forms caps, in which the layer of cells in contact with the ducts acquires a palisade-like appearance. Subsequently, vesicles differentiate from the caps, representing the first rudiment of the nephron. The next stage is the change of the vesicle to an S-shaped tubule, the lower end of which becomes crescentic or bowl-shaped and is the first anlage of Bowman's capsule: the upper end connects with the collecting duct.The developmentin vitro goes on at a much slower rate than in normal conditions, and the nephron does not go beyond the stage of S-shaped tubule; however, the general pattern of development is the same in both situations, except for the absence in culture of blood vessels and therefore also of the glomerular anlage. It should be assumed that glomerular vessels are not necessary in order to shape the first anlage of Bowman's capsule. The connection of the nephron with the collecting duct, generally recognized to occur at the S-tubule stage, was sometimes already found at the vesicle stage, both in cultures and in normal development.Dedicated with warm affection to Prof. Antonio Pensa on his 94th birthday — Research done with the help of means provided by the U.S. Atomic Energy Commission (NYO-3355-30), Euratom (043-65-1 BIOI) and the Italian C.N.R. — Thanks are due to Dr. Elena Vivori for her very kind help in revising the English text.     

Membrane molecules involved in adhesion properties of cultured sertoli cells

Membrane components involved in adhesion properties of cultured Sertoli cells have been studied by a combination of immunological and biochemical methods. An antiserum prepared against Sertoli cells induced reversible rounding and detachment of the cells from the culture dishes. The cell surface morphology during detachment was studied by scanning electron microscopy and indirect immunofluorescence. A Triton soluble fraction of crude membrane preparations inhibited the antibody-induced detachment. The antibodies recognized a restricted number of membrane glycoproteins [detectable as prominent bands on Sodium dodecylsulphate polyacrilamide gel electrophoresis (SDS-PAGE), M_r 170, 140, 80, and 48K] both in the Triton soluble fraction of crude membrane preparation and on intact Sertoli cells. The data suggest that the molecules involved in adhesion properties of cultured Sertoli cells are integral membrane glycoproteins exposing antigenic determinants at the cell surface.     

HMG proteins released from the chromatin following incubation of mammalian nuclei with ethidium bromide

The low-molecular-mass high-mobility group (HMG) chromosomal proteins, namely HMG-14, HMG-17, and HMG-I, which have been found in several proliferating tissues, are released following incubation of nuclei isolated from young rat thymus and from human placenta in a low ionic strength medium containing the intercalating agent ethidium bromide. The amount of HMG proteins released is drug concentration-dependent, but at very high concentrations (20-40 mM) other low- and high-molecular-mass proteins, and even histones, are released. These results suggest a very weak interaction of the HMG proteins with DNA, so that they can be easily detached from the chromatin as a consequence of the interaction of DNA with the intercalating agent.     

Modeling the energetics of 100-m running by using speed curves of world champions.

The present study aims to assess energy demand and supply in 100-m sprint running. A mathematical model was used in which supply has two components, aerobic and anaerobic, and demand has three components, energy required to move forward (C), energy required to overcome air resistance (Caero), and energy required to change kinetic energy (Ckin). Supply and demand were equated by using assumed efficiency of converting metabolic to external work. The mathematical model uses instantaneous velocities registered by the 1997 International Association of Athletics Federations world champions at 100 m in men and women. Supply and demand components obtained in the male champion were (in J/kg) aerobic 30 (5%), anaerobic 607 (95%), C 400 (63%), Caero 83 (13%), Ckin 154 (24%). Comparatively, a model that uses the average velocity of the male and female 100-m champions overestimates Ckin by 37 and 44%, respectively, and underestimates Caero by 14%. We argued that such a model is not appropriate because Ckin and Caero are nonlinear functions of velocity. Neither height nor body mass seems to have any advantage in the energetics of sprint running.     

Morphological and biological characterization of cell line developed from bovine <Emphasis Type="Italic">Echinococcus granulosus</Emphasis>

The taeniid tapeworm Echinococcus granulosus is the causative agent of echinococcal disease, a major zoonosis with worldwide distribution. Several efforts to establish an in vitro model of E. granulosus have been undertaken; however, many of them have been designed for Echinococcus multilocularis. In the present study, we have described and characterized a stable cell line obtained from E. granulosus bovine protoscoleces maintained 3 yr in vitro. Growth characterization, morphology by light, fluorescent and electronic microscopy, and karyotyping were carried out. Cell culture origin was confirmed by immunofluorescent detection of AgB4 antigen and by PCR for the mitochondrial cytochrome c-oxidase subunit 1 (DCO1) gene. Cells seeded in agarose biphasic culture resembled a cystic structure, similar to the one formed in secondary hosts. This cell line could be a useful tool to research equinococcal behavior, allowing additional physiological and pharmacological studies, such as the effect of growth factors, nutrients, and antiparasitic drugs on cell viability and growth and on cyst formation.     

Increased cardenolides production by elicitation of Digitalis lanata shoots cultured in temporary immersion systems

Digitalis lanata is an important source of cardenolides such as digoxin and lanatoside C, which have been widely applied in the treatment of cardiac insufficiencies. Elicitation is one of the most effective methods to enhance the biosynthesis of several secondary metabolites in medicinal plants. We studied the effect of elicitation with Chitoplant^?, Silioplant^? and methyl jasmonate on biomass and cardenolides accumulation in shoots of D. lanata cultivated in temporary immersion systems. Morphological response of the shoots was influenced by elicitors. A reduction in length and number of shoots was evident with all MJ concentrations. Regarding biomass production, Chitoplant^? (0.1?g?l^?1) was found to impact significantly on fresh and dry weight of the shoots. HPLC analysis revealed a higher content of lanatoside C compared to digoxin in all treatments. The highest accumulation of lanatoside C was achieved with Chitoplant^? (0.1?g?l^?1), which resulted in 316???g?g-DW^?1 and with Silioplant^? (0.01?g?l^?1; 310???g?g-DW^?1), which accounted for a 2.2-fold increase in lanatoside C content compared to non-elicited shoot cultures. Additionally, elicitation of D. lanata shoots in temporary immersion systems resulted in an oxidative stress characterized by hydrogen peroxide and malondialdehyde accumulation. These observations point to a connection between hydrogen peroxide generation, lipid peroxidation and cardenolide accumulation. The optimization of elicitor treatment and culture conditions for cardenolide production as well as the advantages of TIS for this purpose are discussed.