Ultraviolet-sensitive Research Articles

Visual pigments and oil droplets in the retina of a passerine bird, the canary Serinus canaria: microspectrophotometry and opsin sequences

The visual receptors of the passeriform bird Serinus canaria, the canary, have been examined microspectrophotometrically and the sequences of the opsins determined. Rods have a maximum absorbance ( λ max) at 506 nm. Four spectral classes of single cone are present: long-wave-sensitive (LWS) containing a photopigment with λ max at 569 nm, middle-wave-sensitive (MWS) with λ max at 505 nm, short-wave-sensitive (SWS) with λ max at 442 nm, and ultraviolet-sensitive (UVS) with λ max at about 366 nm. Double cones possess the 569-nm pigment in both members. Typical combinations of photopigment and oil droplet occur in most cone classes. An ambiguity exists in the oil droplet of the single LWS cones. In some birds, LWS cones are paired with an R-type droplet, whereas in the majority of canaries the LWS pigment is paired with a droplet similar to the P-type of double cones. Mechanisms of spectral tuning within each opsin class are discussed.

Ultraviolet cues affect the foraging behaviour of blue tits

The function of avian ultraviolet (UV) vision is only just beginning to be understood. One plausible hypothesis is that UV vision enhances the foraging ability of birds. To test this, we carried out behavioural experiments using wild–caught blue tits foraging for cabbage moth and winter moth caterpillars on natural and artificial backgrounds. The light environment in our experiments was manipulated using either UV–blocking or UV–transmitting filters. We found that the blue tits tended to find the first prey item (out of four) more quickly when UV cues were present. This suggests that UV vision offers benefits to birds when searching for cryptic prey, despite the prey and backgrounds reflecting relatively little UV. Although there was no direct effect of UV on the time taken to find all four prey items in a trial, search performance in the absence of UV wavelengths tended to increase over the course of an experiment. This may reflect changes in the search tactics of the birds. To our knowledge, these are the first data to suggest that birds use UV cues to detect cryptic insect prey, and have implications for our understanding of protective coloration.

The Contribution of Ultraviolet and Short-Wavelength Sensitive Cone Mechanisms to Color Vision in Rainbow Trout

Color vision in rainbow trout was studied by characterizing the spectral sensitivity of single units in three areas of visual processing: optic nerve; optic tectum; and torus semicircularis. Sensitivity to medium wavelength stimuli was a common feature of all single units examined. Additionally, long wavelength sensitivity was found in all units that were not medium wavelength-only or monophasic. Ultraviolet and short-wavelength sensitivity was common in small, juvenile trout, with ultraviolet sensitive units found in the optic nerve and torus, and short wavelength sensitivity found in the optic nerve and tectum. The shorter wavelength inputs were excitatory and, if found in the same unit, synergistic. The most common type of unit in the trout tectum and optic nerve is trichromatic, with ON inputs from the long and short cone mechanisms and an OFF input from the medium mechanism. In contrast, goldfish color vision is dominated by L and M opponent units without S input. The segregation of ultraviolet sensitivity in the torus but not in the tectum relates to functional differences of these two areas. While the tectum serves the function of wavelength discrimination, ultraviolet inputs to the torus may contribute to prey detection and orientation.

Photoinactivation of Detergent-Solubilized Plasma Membrane ATPase from Rosa damascena

The photochemistry of vesicular and detergent-solubilized preparations of plasma membrane-associated ATPase was investigated in Rosa damascena. The cholate-solubilized ATPase activity fractionated into two peaks on a Sephadex G-150 column with simple, but different ultraviolet (UV) sensitivities. The larger enzyme was UV sensitive; the smaller enzyme was relatively insensitive. The activity of both ATPase fractions depended on environment: both were inactive in cholate, relatively inactive in phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol, and active in phosphatidylglycerol and phosphatidylserine. The UV sensitivities of both fractions also depended on their environment. For the UV sensitive fraction, the action spectrum differed in the 300 to 400 nanometers range when the fraction was irradiated with and without lipids. For the resistant fraction, UV sensitivity at 290 nanometers differed (up to 6-fold) in different lipids. The resistant fraction solubilized in octylglucoside had an action spectrum very different from that in cholate or in lipid vesicles. The absorption spectra of the different preparations reflected the action spectra. For both UV sensitive and insensitive fractions, the action spectra for photoinactivation had peaks at 290 nanometers, suggesting that the chromophores were tryptophanyl residues. The loss of ATPase activity was strictly correlated with the loss of fluorescence from tryptophan in the partially purified enzymes. Cs(+) protected the UV sensitive activity but not the insensitive one. We propose a model which explains the difference in UV sensitivities based on the positions of the tryptophan residues in the two proteins.

Sensitivity and resistance of human melanoma cells to ultraviolet radiation.

A human melanoma cell line (MM253) was found to be sensitive to ultraviolet (UV) radiation, having a Do of 1.0 J/M2 when cloned on plastic culture dishes and a Do of 2.3 J/m2 when cloned in agar. These figures are much lower than those obtained for all other human melanoma cell lines studied in this laboratory (Do of 32-40 J/m2) and demonstrate that MM253 is unusually UV sensitive. The increased level of UV sensitivity in MM253 is not due to a reduced capacity for excision of pyrimidine dimers, repair of DNA single-strand breaks or elongation of newly-synthesized DNA strands when comparison is made with a UV-resistant melanoma cell line.

Second-site mutations in capR (lon) strains of Escherichia coli K-12 that prevent radiation sensitivity and allow bacteriophage lambda to lysogenize.

capR (lon) mutants of Escherichia coli K-12 are mucoid and sensitive to ultraviolet (UV) and X-ray radiation as well as to nitrofurantoin. The mutants form filaments after exposure to these agents. capR mutants are also conditionally lethal since they die when plated on complex medium even without UV treatment; this phenomenon is designated "complex medium-induced killing". Furthermore, capR mutants are poorly lysogenized by bacteriophage lambda. Second-site revertants were isolated by plating on media containing nitrofurantoin. All 17 of the independent revertants studied were still mucoid but resistant to UV radiation. Sixteen of the 17 revertants contained a mutation, sulA, that cotransduced with pyrD (21 min). A second locus, sulB, was also found that cotransduced with leu (2 min). Studies with partial diploids (F'pyrD+ sulA+/pyrD36 sulA17 capR9 (lon) demonstrated that sulA+ is dominant to sulA; thus the indicated partial diploid is UV sensitive, whereas the haploid parent is UV resistant. Furthermore, two other phenotypic traits of capR (lon) mutants were reversed by the sul mutation:complex medium-induced killing and the inability of lambda phage to efficiently lysogenize capR strains. On the basis of these and other results, the following model is suggested to explain capR (lon) and sul gene interactions. capR (lon) is a regulator gene for the structural genes sulA+ and sulB+. Depression of both sul operons results in UV sensitivity and decreased ability of lambda to lysogenize, whereas inactivation of either sul+ protein by mutation to sul prevents these phenomena.

Genetic analysis of a temperature-resistant revertant of the conditional lethal Escherichia coli double mutant polA12 uvrE502.

Conditional lethality of the Escherichia coli polA12 uvrE502 double mutant may be overcome by a mutation that has been termed polA350. The polA350 mutation restored the polymerizing activity of deoxyribonucleic acid polymerase I at 42 C in the polA12 mutant and partially suppressed ultraviolet (UV) and methylmethane sulfonate sensitivities of the polA12. Mapping experiments have located polA350 between metE and polA12, very close to the latter. The strain carrying polA12 polA350 and recB21 was viable at 42 C. The effects of the recB21 and polA12 polA350 combination on the UV sensitivity were additive. The triple mutant polA12 polA350 uvrE502 was more UV sensitive than the single uvrE502 mutant.

A rapid method for complementation testing of Ultraviolet-Sensitive (UVS) mutants of Streptomyces coelicolor

Seventy-one uvs mutations were isolated and tested for complementation with mutations representing the known closely linked uvsA, C and D loci by a rapid replicaplating technique involving “ultra-fertile” crosses. Most of the mutations were successfully classified by this technique. Of the 71 mutations, 23 were assiggned to uvsA, 15 to uvsC and 28 to uvsD. Four strains may have carried mutations in more than one of the three loci, or conceivably polar mutations. The remaining mutation occurred outside the uvsA,C,D cluster.

Ultraviolet inactivation of murine leukemia and sarcoma viruses.

AbstractThe ultraviolet (UV) sensitivity of Friend leukemia virus and a murine sarcoma virus (MSV) was determined. The inactivation dose D10 was 2,000 to 3,000 ergs/mm2 for both. This value is close to the one obtained with Rous sarcoma virus, 3,000 ergs/mm2 (Goldé et al., 1961). MSV produced by the cells incubated in 5‐fluorouracil (5 × 10−3 M) was significantly more UV sensitive than control MSV, suggesting the sensitization of the viral nucleic acid by the base analogue.The virus surviving UV irradiation showed a prolonged latent period, but it was due to the interference of the inactivated virions with the normal growth of surviving virions.When UV‐irradiated MSV was titrated on the cells previously irradiated with UV, the slope of the inactivation curve was steeper than when the virus was titrated on the normal cells. This may suggest the complementation of the UV‐damaged viral genome by the corresponding homologous host genome.