Comparison of the action of pristan and Freund's incomplete adjuvant on the development of ascites in mice--the recipients of hybridoma cells

Production of immunodiagnostic preparations based on monoclonal antibodies requires large amounts of such antibodies. Most frequently preparative quantities of monoclonal antibodies are provided by ascitic fluid from hybridoma-carrying mice. Prior to intraperitoneal administration of hybridoma cells mice are subjected to stimulation with pristan, a mineral oil component. The authors showed that the Freund's incomplete adjuvant (FIA) may be as well used for this purpose. The effect of pristan and the FIA on ascites development in mice with hybridomas producing monoclonal antibodies to the Ia-like antigens of man was studied. The stimulants were administered in amounts of 0.5 ml per a mouse. It was shown that irrespective of the stimulant injection time and the number of the administered hybridoma cells the amount of the ascitic fluid formed in female mice BALB/c stimulated with the FIA was 1.5-3 times higher as that in the animals stimulated with Pristane, the antibody titer in the ascitic fluid being unchanged.     

Precise excision of bacterial transposon Tn5 in yeast

Summary We have demonstrated that precise excision of bacterial transposon Tn5 can occur in the yeast, Saccharomyces cerevisiae. Tn5 insertions in the yeast gene LYS2 were generated by transposon mutagenesis made in Escherichia coli by means of a ::Tn5 vector. Nine insertions of Tn5 into the structural part of the yeast LYS2 gene situated in a shuttle epsiomal plasmid were selected. All the plasmids with a Tn5 insertion were used to transform yeast strains carrying a deletion of the entire LYS2 gene or a deletion of the part of LYS2 overlapping the point of insertion.All insertions inactivated the LYS2 gene and were able to revert with low (about 10^-8) frequencies to lysine prototrophy. Restriction analysis of revertant plasmids revealed them to be indistinguishable from the original plasmid without Tn5 insertion. DNA sequencing of the regions containing the points of insertions, made for two revertants, proved that Tn5 excision was completely precise.     

Mechanism of the cytotoxic action of formaldehyde on cultured mammalian cells

Induction and repair of DNA lesions cell inactivation and repair of potentially lethal damages (PLD) were studied after the treatment of cultured cells with formaldehyde. Formaldehyde induced the appearance of a rapidly sedimentating DNA--membrane complex. This complex may contain up to 50% of choline and no more than 3-5% of leucine or lysine incorporated in the acid insoluble cell fraction, Inhibition of DNA synthesis, induction of single strand DNA breaks and/or alkali-labile sites increased with the raise of formaldehyde concentration. A good correlation is observed between with the raise of formaldehyde concentration. A good correlation is observed between with the raise of formaldehyde concentration. A good correlation is observed between the increasing DNA quantities in the rapid sedimentation complex and the cell lethality.     

ENDOGENOUS CHANGES OF PHOTOCHEMICAL ACTIVITIES OF SPINACH LEAVES

The activities of green cell-free extracts of spinach leavesin performing photochemical transphosphorylation, photosyntheticphosphorylation, the HILL reaction and the light-induced formationof the endogenous reducing substance (ascorbic acid) were followedin parallel during the growth process of the plant. There wasa certain parallelism between the development of the activitiesof photochemical transphosphorylation, of photo-synthetic phosphorylationand of the HILL reaction, activities being low in the earlierstage of growth, reaching a maximum just before efflorescence,and showing thereafter a more or less sharp decline. The activityin the light-induced formation of endogenous reducing substancewas undetectable for the first 35 day-period of growth, reacheda maximum about one week earlier than the other three activities,and again disappeared after 60 days of growth. (Received September 9, 1960; )     

Osmotic water permeability of cell membranes from Mesembryanthemum crystallinum leaves: effects of age and salinity

The osmotic water permeability ( P _os) of cell membranes isolated from leaves of 40-, 50- and 60-day-old Mesembryanthemum crystallinum plants was estimated by measuring light-scattering kinetics using stopped-flow spectrophotometry. The measurements were performed on the plasma membrane (PM), purified tonoplast (TP), and TP-enriched vesicles. The PM and TP-enriched vesicles were obtained by partitioning the microsomal fraction in an aqueous polymer two-phase system, whereas the purified TP vesicles were prepared by microsomal vesicle flotation on a sucrose cushion. The P _os of isolated membranes declined with plant age. The kinetic experiments showed that there was no difference between the P _os of the PM and TP isolated from plants of all ages. A 24-h exposure of plants to 400 m M NaCl caused a decline in the P _os as well. These findings suggest that, during M. crystallinum transition to CAM, which was induced by plant ageing or salinity, plant osmoregulatory responses included changes in the P _os of the leaf-cell membranes. These variations in the P _os are discussed in the context of adaptive mechanisms responsible for the maintenance of the water balance in the common ice plant.     

The quaternary structure of bovine heart mitochondrial creatine kinase

Crosslinking of subunits of the high molecular weight oligomer of bovine heart mitochondrial creatine kinase (CKm) by dimethyl suberimidate and subsequent electrophoresis in the presence of sodium dodecyl sulfate gives eight protein bands. An increase in the time course of the enzyme crosslinking reaction results in the protein accumulation in the high molecular weight bands. Evidence has been obtained suggesting that crosslinking involves only the intraoligomeric contact areas. It is concluded that bovine heart CKm is an octamer. Crosslinking of intersubunit contacts in the octameric form of the enzyme by various diimidates has been carried out. The data obtained suggest that within the octamer the CKm subunits have a quasispherical rather than planar arrangement. This finding is supported by electron microscopy data.     

The Influence of Effectors of the Ca2+ Signaling System and Oligosaccharin OSRG on IAA-Induced Formation of Adventitious Roots on Explants of Buckwheat Hypocotyls

Russian Journal of Plant Physiology - The interplay between different signaling pathways that occurs during the development of a root system is investigated by considering, by way of example, the...     

First data on the age,growth processes,and otoliths of snub-nosed spiny eel <Emphasis Type="Italic">Notacanthus chemnitzii</Emphasis> (Notacanthidae)

This is the first work on the age, developmental stages, and otoliths of snub-nosed spiny eel Notacanthus chemnitzii (Notacanthidae), a rare fish species inhabiting the waters of southwestern Greenland. The mean age of 14 studied fishes (with a length of 36–104 cm and a mass of 74–3834 g) varied in the range from 11 to 26 years. Since the duration of leptocephalus stage is unknown, the real age can be greater. The length of snub-nosed spiny eel can reach 122 cm; thus, its maximal age can be more than 30 years. The minimal length of mature females was 55 cm (18 years); the minimal length of mature males was 66 cm (14 years).     

Scientific Bases for Enuring Productive Longevity of Agrolandscapes in Russia

Biology Bulletin - V.V. Dokuchaev’s ideas are the foundation of modern ideas about rational nature-usage methods in our steppes in order to ensure productive longevity of agro-ecosystems and...