Control of intracellular glutathione and its effect on ultraviolet radiation-induced K+ efflux in cultured rose cells

Abstract Modification of the ‘intracellular concentration of reduced glutathione’ (IC-GSH) affected the response of cultured rose cells (Rosa damascena) to ultraviolet radiation (UV)-induced leakage of K⁺. High IC-GSH induced by incubation of cells in 10 mol m^?3 GSH (IC-GSH increased linearly with time from 20 to about 600 μmol g^?1 in 61.2 ks) caused cells to become significantly less sensitive to UV. Low IC-GSH induced by treatment with 1 mol m^?3 buthionine sulphoximine (BSO) plus 1 mol m^?3 diethylmaleate (DEM) (IC-GSH decreased from 20 to about 3 μg g^?1 in 61.2 ks) reduced, rather than increased, the UV-sensitivity of the cells. However, treatment with DEM also induced a large transient K⁺ leakage; and treatment with BSO induced a slight leakage. The K⁺ leaked was recovered by 3.24 ks. Following K⁺ recovery, the DEM-treated cells showed almost complete insensitivity to UV, and BSO-treated cells showed a slightly reduced sensitivity to UV. These results are in agreement with our previous findings that other treatments (heat, cycloheximide, UV), which also cause a transient leakage of K⁺, also reduce the induction of K⁺ leakage by a subsequent UV treatment. We conclude that high IC-GSH may play a role in protecting plant cells from UV-induced K⁺ leakage. Increased UV-sensitivity with low ICGSH was not observed, we believe, because of the transient K⁺ leakage, though the mechanism of reduced sensitivity to UV induced by transient leakage of K⁺ is not known at this time. Treatment with UV did not reduce the IC-GSH, showing that this is not the mechanism by which UV induces K⁺ leakage.     

The interactions of the non-specific inhibitor of hyaluronidase with hyaluronidase and proteolytic enzymes in vivo

1. Following intravenous administration of testes hyaluronidase in rabbits and dogs, there is a decrease in the level of the non-specific inhibitor of hyaluronidase in serum. 2. If a large amount of hyaluronidase is injected, the inhibitor level is reduced to zero and hyaluronidase may be present in serum for some time after the injection. The hyaluronidase activity of such samples of serum increases when the serum is incubated with papain. 3. Hyaluronidase activity is found in the livers of the injected animals in large amounts and this activity is increased considerably when the homogenate of this tissue is incubated with papain. 4. Intravenous administration of several proteases or venom produces a decrease in the serum inhibitor level. Intravenous administration of streptokinase produces such a decrease in rabbits but not in dogs. 5. There is a correlation between the depletion of the inhibitor from the serum and the occurrence of a slow, persistent depression of blood pressure upon administration of proteolytic enzymes.     

SPERM HARVESTING AND POSTMORTEM FATHERHOOD

The motives and consequences of harvesting sperm from brain dead males for the purpose of effecting post mortem fatherhood are examined. I argue that sperm harvesting and post mortem fatherhood raise no harms of a magnitude that would justify forbidding the practice outright. Dead men are not obviously harmed by the practice; children need not be harmed by this kind of birth; and the practice enlarges rather than diminishes the reproductive choices of surviving partners. Certain ethical and legal issues nevertheless require attention. As a matter of consistency with other harvesting protocols, there ought to be a mechanism for respecting the wishes of men who when alive do not wish to become fathers post mortem. Mechanisms governing entitlement to harvest and use sperm will also be required. I note that the law is unlikely to recognize the paternity of children born from harvested sperm, though there may be reasons to recognize that paternity in some instances.     

Gap junction structures: Analysis of the x-ray diffraction data

Models for the spatial distribution of protein, lipid and water in gap junction structures have been constructed from the results of the analysis of X-ray diffraction data described here and the electron microscope and chemical data presented in the preceding paper (Caspar, D. L. D., D. A. Goodenough, L. Makowski, and W.C. Phillips. 1977. 74:605-628). The continuous intensity distribution on the meridian of the X-ray diffraction pattern was measured, and corrected for the effects of the partially ordered stacking and partial orientation of the junctions in the X-ray specimens. The electron density distribution in the direction perpendicular to the plane of the junction was calculated from the meridional intensity data. Determination of the interference function for the stacking of the junctions improved the accuracy of the electron density profile. The pair-correlation function, which provides information about the packing of junctions in the specimen, was calculated from the interference function. The intensities of the hexagonal lattice reflections on the equator of the X-ray pattern were used in coordination with the electron microscope data to calculate to the two-dimensional electron density projection onto the plane of the membrane. Differences in the structure of the connexons as seen in the meridional profile and equatorial projections were shown to be correlated to changes in lattice constant. The parts of the junction structure which are variable have been distinguished from the invariant parts by comparison of the X-ray data from different specimens. The combination of these results with electron microscope and chemical data provides low resolution three- dimensional representations of the structures of gap junctions.     

Condition and brightness of structural blue‐green: motmot tail‐racket brightness is related to speed of feather growth in males,but not in females

Coloration plays an important role in sexual and social communication, and in many avian species both males and females maintain elaborate colours. Recent research has provided strong support for the hypothesis that elaborate female traits can be maintained by sexual or social selection; however, most research on female ornamentation has focused on pigment‐based colours, and less is known about how structural colours are maintained. Both sexes of the turquoise‐browed motmot (Eumomota superciliosa) have a blue‐green racket‐tipped tail, and it remains unknown if tail coloration serves as a sexual or social signal in one or both sexes. Here, we describe sexual dichromatism in the blue‐green portion of the tail racket, and we test for a relationship between coloration and condition, as indicated by growth bars. Tail colour of both sexes has a similar spectral shape, and there is significant, although moderate, sexual dichromatism: males are brighter than females, and males have marginally greater blue‐green saturation than females. The length of feather grown per day is positively related to overall feather brightness, but this relationship is only present in males. The relationship between male coloration and condition suggests that tail colour has the potential to convey information about individual quality during mate choice or contest competition. The lack of a similar relationship in females suggests that female tail colour does not convey the same condition‐dependent information that we suggest may be reflected by male colour. Female tail colour may therefore reflect other aspects of condition, be involved in other (non‐condition‐dependent) forms of communication, or be expressed as a non‐functional byproduct of genetic correlation between the sexes. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 673–681.     

An Unusual,Fangless Short-tailed Snake(Squamata,Serpentes, Homalopsidae) from Sumatra,Indonesia

Two genera of fangless homalopsid snakes Brachyorrhos and Calamophis from eastern Indonesia have been described as basal members of the clade. A third genus belonging to this group from Sumatra, Indonesia is described here based upon morphology. Fangless homalopsid snakes share 19 dorsal scale rows at mid-body, fused dorsal scales above the cloaca, 5 to 7 upper labials, divided anal plate, divided subcaudals, 15–21 teeth on the dentary, frontal bone about 23% of skull length and other morphological characters that suggest they are related. All the three genera are known only from Indonesia. The new genus and species have a distinctive skull morphology with an absent premaxilla, a more depressed skull, and a larger eye than are present in Brachyorrhos.