The ultraviolet receptor of bird retinas

The eyes of 15 species of birds from 10 families have some cones maximally sensitive at 370 nanometers in the near-ultraviolet. Spectral sensitivity was measured by recording extracellularly in opened eyecups , and a maximum in the ultraviolet was revealed by selectively adapting the retina with yellow background lights. The 370-nanometer spectral sensitivity function is attributed to receptors because its spectral position does not vary with the strength of adaptation and because it is present when the receptor potentials are isolated from the contributions of higher order retinal neurons by exposing the retina to sodium aspartate. These measurements demonstrate the basis for the ultraviolet sensitivity of birds that has been seen in behavioral experiments, and they provide further evidence that many vertebrates share with insects vision in the near-ultraviolet.

Appearance of a Purkinje shift in the developing retina of the chick

The development of rod and cone function was studied in late embryonic and posthatch chicks by measuring the spectral sensitivity of the electroretinogram (ERG) of opened eyecups to 100-msec flashes and 25-Hz stimuli. At the time of hatching the ERG is dominated by cone activity: the response-energy curves for different wavelengths are parallel, and the spectral sensitivity of the dark-adapted eye is maximal near 580 nm. During the first week after hatching, rods make a progressively greater contribution to the ERG: the response-energy functions cease to be parallel, and the spectral sensitivity maximum to dim flashes moves to about 510 nm while the maximum for brighter lights remains at 580 nm. Only the cones are able to follow the 25-Hz stimulus. Spectral sensitivity of the eye to 25-Hz stimuli, measured on red- or orange-adapting backgrounds, reveals the presence at the time of hatching of two photopic processes with lambda max at 415 nm and 580 nm, with evidence for a third in the region 470-510 nm.

Enzyme-linked immunoadsorbent assay for detection of colony-stimulating factor (CSF-1)

An enzyme-linked immunoadsorbent assay (ELISA) has been developed for the quantitative measurement of L-cell colony-stimulating factor (CSF-1). According to this method, purified antigen (CSF-1) was allowed to adsorb to polystyrene or polyvinyl microtiter wells, which were then incubated with specific rat anti-CSF-1 antiserum with or without standard antigen or unknown test samples. The amount of antibody bound to the solid phase was then quantitated by enzyme (horseradish peroxidase)-conjugated rabbit anti-rat immunoglobulin antibody. This assay has a sensitivity comparable to that of the bioassay (approximately 5 U) and can be carried out in a single day.

Differentiation of various mononuclear phagocyte colony-forming cells by hypotonic lysis

Various classes of murine mononuclear phagocyte colony-forming cells (CFU) present in peritoneal exudate, alveolar spaces, and blood are capable of extensive proliferation and form colonies in vitro. In this study, the sensitivity to hypotonic lysis of the proliferative capacity of various classes of mononuclear phagocyte CFC as well as three cell lines was investigated. The results showed that alveolar CFC (AL-CFC) and a macrophage cell line J774 are most resistant to hypotonic conditions, and the committed stem cells for both granulocytes and macrophages (GM-CFC) and blood monocytes (BL-CFC) are most sensitive to hypotonic conditions. Within 7 min all GM-CFC and BL-CFC are killed but less than 5% of AL-CFC are killed. Peritoneal exudate CFC (PE-CFC) displayed intermediate sensitivity since 50% of them were killed within 7 min in the hypotonic conditions. These data suggest that various classes of mononuclear phagocyte CFC can be distinguished from each other by their ability to resist hypotonic lysis.

Effects of hydrocortisone acetate on pulmonary alveolar macrophage colony-forming cells

We investigated the effect of prolonged monocytopenia induced by daily injections of hydrocortisone acetate on the number of alveolar cells and alveolar macrophage colony-forming cells (AL-CFC) in mice. We did not observe an appreciable reduction in the number of either alveolar macrophages of AL-CFC under this experimental condition, which markedly inhibited the blood monocyte concentration over 10 days. These results suggest the existence of a mechanism by which the number of alveolar macrophages, including AL-CFC, can be maintained without a continuous migration of blood monocytes into alveolar spaces.

Conversion of monocytes to cells capable of anchorage-independent growth in vitro

We investigated the time-course involved in the conversion of mouse blood monocytes in vitro in cells capable of anchorage-independent growth. Two criteria were used to define when monocytes were fully converted to cells similar to mononuclear phagocytes present in inflammatory exudate, such as thioglycollate medium (TM)-elicited peritoneal exudate. They were the production of high levels of plasminogen activators and an ability to undergo anchorage-independent growth. Resident peritoneal macrophages were used as controls and for comparison. Our studies indicated that monocytes, but not resident peritoneal macrophages, could be converted to cells similar to TM-elicited mononuclear phagocytes after 2 d in culture.

Solution conformation of thymopoietin32-36: a proton nuclear magnetic resonance study

The aqueous solution conformation of Arg-Lys-Asp-Val-Tyr (TP5), corresponding to positions 32-36 of the thymic hormone thymopoietin has been investigated by proton nuclear magnetic resonance (NMR). This pentapeptide fragment retains the biological activity of the parent protein, viz., induction of selective differentiation of T lymphocytes. All the observed NH and CH resonances of TP5 have been assigned, and the solution conformation of this peptide has been investigated by analysis of chemical shift variations with pH, vicinal NH-C alpha H coupling constant data, and amide hydrogen exchange rates. The latter were measured in H2O by using a combination technique consisting of the transfer of solvent saturation and saturation recovery NMR experiments. The data are compatible with the assumption of a highly motile dynamic equilibrium among different conformations for TP5. A comparison of the amide hydrogen exchange rates of the pentapeptide with that of solvated model compounds shows that Val4-NH is significantly shielded from the solvent. In addition, the chemical shift variations with pH suggest that the guanidino-N epsilon H of arginine is associated with one of the carboxylate groups. These observations provide specific boundary conditions for the construction of molecular models of the conformation(s) of TP5 in aqueous solution.

Enhancement of the growth of blood monocytes in agar cultures by haemolysates

Mouse blood monocytes grow well in liquid but poorly in agar medium. In this study the effect of haemolysate on the clonal growth of blood monocytes in agar cultures was investigated. The results suggested that haemolysate from mouse or rat red blood cells contains a factor(s) that can render the murine blood monocytes able to grow well in agar culture (anchorage-independent growth). The mechanism of action of the enhancing factor(s) is discussed.

An analysis of the Co2+-induced nuclear magnetic resonance perturbations of hen egg white lysozyme

A general methodology is presented for analyzing dipolar shifts induced by paramagnetic ions in the nuclear magnetic resonance (NMR) spectra of ligand molecules. The method is applied to the shift perturbations induced by Co2+ in the spectrum of hen egg white lysozyme. A hypothesis testing scheme is employed to evaluate statistically the relative precision with which the axially symmetric and non-axially symmetric forms of the dipolar shift equation fit the observed data. The assumption of axial symmetry for the magnetic susceptibility tensor of Co2+ is rejected at the confidence level of 99%. Since the results presented here are similar to those reached in our analysis of lanthanide-induced shifts, we suggest that the assumption of axial symmetry may, in general, not hold. Similar conclusions have been reached by other investigators in studies of paramagnetic metal binding to model systems. We have included the three Co2+ coordinates in an eight-parameter fit of the Co2+ shift data. The Co2+ position obtained from this fit is in statistical agreement with the position inferred from x-ray data. Thus, the analysis of shift data may furnish a means for determining the site of metal complexation in macromolecules whose structure has been determined by x-ray crystallography.

Some immunological effects of penicillamine

Immunological effects of D- and D,L-penicillamine (PA) were studied in efforts to develop assays for synthetic D or D,L analogs and to contribute to the understanding of the mechanism(s) of action of D-PA in rheumatoid arthritis. At the highest doses tolerated by mice, D,L-PA did not significantly inhibit the development of haemagglutinating antibodies in vivo. In studies in vitro with T lymphocytes, D-PA at 1 mM concentration inhibited both concanavalin A- and phytohaemagglutinin-induced transformation as assayed by [3H]thymidine incorporation, but D-PA concentrations of 5 mM were required to inhibit concanavalin A-induced amino acid uptake. No effect of D-PA was observed either on the induction of cytotoxic T cells or on the attack of specifically sensitized T cells on target cells. It is of interest that D-PA at 1 mM concentration did inhibit lipopolysaccharide-induced transformation, which predominately stimulates B lymphocytes. The effects of PA on the induced transformation of T and B cells deserve further attention for studies with analogs of PA.

Nuclear magnetic resonance studies of the denaturation of ubiquitin

The effects of pH, temperature and guanidine hydrochloride concentration on the structure of ubiquitin, a polypeptide which can activate adenylate cyclase and can mimic thymopoietin induced differentiation of prothymocytes, were monitored using nuclear magnetic resonance spectroscopy. This relatively small polypeptide (molecular weight of 8541) exhibits a remarkable stability towards pH and temperature changes. At 7 M guanidine hydrochloride concentration, the structure of ubiquitin is essentially a random coil.

Proton nuclear magnetic resonances study of bleomycin in aqueous solution. Assignment of resonances

The 1H NMR spectrum of the glycopeptide antineoplastic antibiotic bleomycin has been examined in D2O solution (Fourier transform nuclear magnetic resonance, 270 MHZ) and in H2O solution (correlation nuclear magnetic resonance, 250 MHZ). Resonances have been assigned to specific hydrogens of the two most abundant congeners, bleomycin-A2 (BLM-A2) and bleomycin-B2 (BLM-B2), on the basis of (1) homonuclear spin decoupling, (2) comparison of the spectra of BLM-A2, BLM-B2, fragments of these antibiotics, and the related antibiotic phleomycin, and (3) the pH dependence of chemical shifts. Resonance assignments are presented for all the CH protons of BLM-A2 and BLM-B2 except for the saccharide groups, for which only the anomeric proton assignments are given. All of the NH protons have been identified with specific resonances except for the two primary amide groups, which yield four well-resolved peaks, whose specific assignment was not attempted. This study serves as a basis for future investigations of the conformation of bleomycin and its interaction with metals and nucleic acids.

Effect of serum and serum components on the mitogen-induced proliferation of murine lymphocytes

By increasing the concentration of human serum, the dose-response profile of the Concanavalin A-induced proliferation of murine spleen lymphocytes becomes broader and the optimal cell proliferation takes place at higher concentrations of mitogen. It is shown that this behavior is due to the globulin fraction of serum which greatly decreases the binding of Concanavalin A to lymphocytes. Cohn fractions III and IV have a similar effect. On the other hand, cell proliferation takes place also in the absence of Pooled Human Serum at appropriate concentrations of Concanavalin A and within a very narrow range of cell concentrations. In the presence of the albumin fraction of serum, proliferation takes place over a wider range of mitogen and cell concentrations. As a result of these phenomena, the mitogenic effect of Concanavalin A varies greatly in function of the concentration of serum. Analogous results were obtained with fetal calf serum.

Biosynthesis of Se-methylselenocysteine and S-methylcysteine in Astragalus bisulcatus

Biosynthesis of Se-methylselenocysteine and S-methylcysteine in Astragalus bisulcatus has been investigated using radiotracer methods. The results of feeding L-serine-U-I4C, DL-serine-1-14C, L-cysteine-U-14C, and L-methionine-methyl-14C to 2-month-old seedlings indicate that serine and cysteine are precursors of the three carbon chains, and that methionine methyl group is a precursor of the methyl group of the Se- and S-methylcysteines. It is suggested that in the biosynthesis of Se-methylselenocysteine from serine, Se-cysteine is formed first, and that Se-methylselenocysteine is formed from Se-cysteine by methylation. The incorporation of radioactivity into S-methylcysteine suggests a similar mechanism for its biosynthesis.