Biological activity of human alpha-interferons studied using specific antisera

Preparation of highly active rabbit antisera (AS) to human recombinant alpha 2-interferon and their use for studying biological properties of natural and plasmid alpha-interferons are described. By exhaustion of AS by alpha 3-interferon there were prepared practically monospecific AS not reacting with antigenic determinants of alpha 3-interferon. It was found that alpha 3-interferon represented a significant portion of human lymphoblastoid interferons and was included in PH-labile alpha-interferon from serum of patients with Kaposi carcinoma. AS to alpha 2-interferon completely neutralized antiviral and antiproliferative activity of the homologous subtype alpha-interferon and stimulation of cytotoxicity of human natural killer cells induced by it. It neutralized also the same effects of the heterologous subtypes (alpha 3 and alpha F/D) and leukocytic interferon, but the neutralization level was lower. The results of the study confirmed the polyfunctional nature of the interferon molecule.     

Composition and structure of the antibiotic polypeptide 308-I from Actinomadura recticatena

Antibiotic 308-I isolated from Actinomadura recticatena and the products of its degradation were studied with the methods of electron impact mass spectrometry, chemical ionization with ammonia, field desorption and ion extraction from solution under atmospheric pressure. It was shown that by its composition and structure antibiotic 308-I was identical to antibiotic BBM-928 A.     

Sweat glands of the scrotum of the bull

Skin samples were taken post mortem from the scrotum, abdomen and neck of 4 mature bulls. The volume of sweat glands per unit skin surface area of the scrotum was greater than that of other body regions. Within the scrotum there was a gradient in sweat gland volume increasing from proximal through to distal parts of the scrotum. These results suggest a previously unidentified variable cooling capacity of the scrotum depending on testicular descent.     

Platelet-activating factor in the rabbit uterus during early pregnancy

Platelet-activating factor (PAF) concentrations were low in the non-pregnant, oestrous uterus (mean +/- s.e.m.: 2.2 +/- 1.2 pmol/g, n = 3). However, uterine PAF increased dramatically during pregnancy to a maximum of 37.8 +/- 4.90 pmol/g (n = 7) on Day 5. By Day 7, PAF concentrations in the uteri of pregnant rabbits had returned to levels similar to those found at oestrus. In contrast, uterine PAF in pseudopregnant rabbits peaked at 30.6 +/- 2.8 pmol/g (n = 8) on Day 4, declined to 20.5 +/- 2.4 pmol/g (n = 8) on Day 5 and then remained at that concentration through Day 7. Uterine PAF co-migrated with synthetic PAF (1-O-hexadecyl-2-acetyl-sn-glycero-phosphocholine) in both thin-layer and normal-phase high-performance liquid chromatography. PAF activity in the uterus during pregnancy and pseudopregnancy was found almost exclusively in the endometrium; little or no PAF was found in myometrium, uterine flushings or blastocysts. While no PAF was detected in blastocysts on Days 5 and 6 of pregnancy, the presence of the embryo appears to modulate biosynthesis and/or degradation of PAF by the uterus, since PAF decreased significantly in uterine tissue apposed to the implanting embryo (but not in similar areas between such attachment sites). Increased concentrations of PAF in the preimplantation rabbit uterus followed by a dramatic decrease on the day of blastocyst attachment suggest that this potent inflammatory autacoid may play a vital role in implantation.     

Organization of simple sequences in the Drosophilia melanoga ter genome

Fragments of Drosophila melanogaster DNA that intensively hybridize with simple sequences poly[(dG-dT).(dC-dA)], poly[(dA).(dT)] and poly[(dG-dA).(dC-dT)] were cloned. The first two types of simple sequences are organized in these clones as separated stretches of moderate length, repeated many times within 12-15 kb. Each cluster contains only one type of the simple sequences and originates from a unique in the genome. In contrast, poly[(dG-dA).(dC-dT)] occurs in the genome as several isolated motifs.     

A modified method of isolation of "tight" 70S ribosomes from Escherichia coli highly active at different stages of the elongation cycle

The functional activity of the wide-spread "tight" 70S ribosomes is usually equal to 55-80%. We show here that the inactive fraction of this type of ribosomes is virtually blocked by residual endogenous RNA's. These RNA's are shown to be removable by introducing an additional stage in the isolation procedure including: 1. short heating (15 min, 37 degrees C) of "tight" 70S under dissociation conditions, i. e. in a buffer containing 3 mM MgCl2 and 200 mM NH4Cl; 2. washing off endogenous RNA's on a sucrose density gradient in the same buffer; 3. final selection of purified "tight" 70S on the sucrose gradient containing 5 mM MgCl2 and 50 mM NH4Cl. "Tight" 70S ribosomes isolated by such a procedure are 90-100% active with respect to tRNA binding (including the factor-dependent one), peptide bond synthesis and translocation.     

Influence of pH,exchangeable aluminium and 0.02M CaCl2-extractable aluminium on the growth and nitrogen-fixing activity of white clover (Trifolium repens) in some New Zealand soils

The effects of soil acidity on the growth and N₂-fixing activity of white clover in seven acid topsoils and subsoils of New Zealand were investigated using a glasshouse experiment.The application of phosphate (Ca(H₂PO₄)₂) to the soils resulted in very large increases in white clover growth on all soils. The application of phosphate, as well as increasing P supply, also decreased 0.02M CaCl₂-extractable Al levels, but had little effect on exchangeable Al levels.Where adequate phosphate was applied, increasing rates of lime (CaCO₃) resulted in increased plant growth on most soils. N₂[C₂H₂]-fixing activity was increased by the first level of lime for one soil, but generally remained approximately constant or declined slightly at higher rates of lime. Up to the point of maximum yield, white clover top weight was more highly correlated with 0.02M CaCl₂-extractable soil Al than with exchangeable Al or pH. At pH values greater than 5.5, plant yield declined on some soils, apparently because of Zn deficiency. The data suggest that white clover is unlikely to be affected by Al toxicity at 0.02M CaCl₂-extractable Al levels of less than about 3.3 g g^–1. However, there were differences between soils in apparent plant tolerance to 0.02M CaCl₂-extractable Al, which appeared to be caused by differing C levels in the 0.02M CaCl₂ extracts.     

Factors affecting the distribution and dynamics of14C in two soils cropped to barley

The distribution of¹²C and¹⁴C and dynamics of¹⁴C in barley plots were studied after pulse labelling with¹⁴CO₂. Barley was grown in microplots on a Black soil at Ellerslie and a Gray Luvisol at Breton, Alberta and was sampled on four dates between July 31 and October 20. The quantity of¹²C in shoots, microbial biomass, and soil was greater at Ellerslie than Breton. Root¹²C did not differ between sites. There were no significant differences over time in the quantity of¹²C in any of the pools. On the first sampling date 18.59% of the¹⁴C was recovered in the soil-plant system at Ellerslie and 60.82% was recovered at Breton. At Ellerslie 20.35 MBq were recovered in shoots, 0.50 in roots, 0.08 in microbial C and 0.77 in soil while at Breton 27.92 MBq were recovered in shoots, 2.70 in roots, 0.22 in microbial C and 39.3 in soil. The difference between sites in soil¹⁴C was due to higher water filled porosity at Breton than at Ellerslie at the time of labelling. Soluble C (gg^?1 root C), used as a measure of root exuded C, increased above 70% water filled porosity. There were no significant differences over time in the quantity of¹⁴C in any of the pools or in the specific activity of¹⁴CO₂ released from soil during 10-day laboratory incubation. This indicated that the belowground system was in steady state with a continuous input of¹⁴C from labelled root matrial. Differences in specific activity of the various belowground pools revealed that an average of 17% of the microbial C was active at Ellerslie while 43% was active at Breton. Active microbial C (gm^?2) was the same at both sites because total microbial C was lower at Breton than at Ellerslie. At Breton some of the¹⁴C released under conditions of high water filled porosity at the time of labelling appeared to be stabilized against microbial turnover.     

Adaptation of exotic Azolla to tropical environment of Thailand

There are seven known species of Azolla, two of which have been used in cultivated systems, the tropical speciesA. pinnata, and the temperate speciesA. filiculoides. OnlyA. pinnata is indigenous in Thailand. In this study the two exotic species,A. caroliniana andA. microphylla, were evaluated under the various tropical field conditions in Thailand. When compared with seven selected strains ofA. pinnata under three field conditions,A. caroliniana andA. microphylla were similar to the indigenous species, in terms of growth performance, N₂ fixation, and yield. This study suggests thatA. caroliniana andA. microphylla can be successfully cultivated as a nitrogen fixing green manure for rice production in the tropics.     

Structure, Function, and Evolution of Proton-ATPases

Proton-ATPases are among the most important primary ion pumps in nature. There are three classes of these enzymes which are distinguished by their structure, function, mechanism of action, and evolution. They function in ATP formation at the expense of a protonmotive force generated by oxidative and photosynthetic electron transports, maintaining a constant pH in the cytoplasm, and forming acidic spaces in special compartments inside and outside the cell. The three classes of proton-ATPases evolved in a way that prevents functional assembly in the wrong compartment. This was achieved by a triple genetic system located in the nucleus, mitochondria and chloroplast, as well as delicate control of the proton pumping activity of the enzymes.