In vitro heterologous cytotoxicity by T effector cells from mice immunized with Sindbis virus.

An in vitro correlate of cell-mediated cross-protection among alpha-viruses was demonstrated by cytotoxicity of Sindbis-immune spleen cells from mice to both Sindbis and Semliki Forest virus (SFV)-infected target cells. This cytotoxicity was shown to be mediated by the T cell population of the spleen and was independent of the presence of macrophages or B cells. The time when the level of the lymphocyte-mediated cytotoxicity (LMC) to SFV-infected cells was maximal coincides with the time when immunity to SFV is maximal in vivo, as reported previously, and when adoptive immunity to SFV can be transferred. After one i.p. injection of Sindbis virus, the level of homologous LMC was higher than the level of heterologous LMC. However, following a second injection of Sindbis virus as immunogen, at a time when the mice are cross-protected to SFV, the heterologous LMC was considerably higher than homologous LMC. We propose that there is suppression of the effector T cells specific for Sindbis-infected cells after the second immunizing injection, probably by homologous antibody. In contrast, there appears to be an anamnestic cell-mediated response to SFV.     

Sézary's syndrome and generalized plane xanthoma.

The first case of Sézary''s syndrome associated with generalized plane xanthoma is reported, thereby extending the association of lymphoreticular proliferative disorders with plane xanthomatosis. The association of Sézary''s syndrome with plane xanthomatosis may be an in vivo example of defective cell regulation involving the major cellular components of the immune response.     

Chemical composition and ultrastructure of the epicuticular wax in three lines of Brassica napus (L)

The epicuticular wax in three lines of Brassica napus (rape) has been investigated and the detailed chemistry and ultrastructure of the waxes examined. A distinct chemical make-up has been found for all three waxes which is correlated with three distinct crystallite structures. A tentative scheme for classification of Brassica wax mutants is described in which the two newly analysed rape mutants can be placed. Mass spectral analysis of all wax components confirms and extends previous ideas about the chemistry of Brassica waxes.     

Fungal rhodopsins and opsin-related proteins: eukaryotic homologues of bacteriorhodopsin with unknown functions.

In the last decade, several genome sequencing projects revealed the existence of previously unknown photoreceptors. Among those are eukaryotic rhodopsins of haloarchaeal type, mostly represented by fungal sequences. We have classified and analyzed seventy-seven of these fungal proteins, which show a high similarity of their putative transmembrane regions to those of bacteriorhodopsin. Those sequences can be divided into the two subgroups, fungal rhodopsins (RDs) and opsin-related proteins (ORPs), the latter lacking the lysine residue necessary for retinal binding. We have analyzed the conservation pattern of the residues known to have functional or structural importance in bacteriorhodopsin and discussed dramatic differences in the conservation between RDs and ORPs. We found many cases of multiple forms of RDs and/or ORPs and examined possible reasons for such multiplicity. For some species the reason may lie in functional photobiological diversification, while for the others it follows the pattern of evolutionary recent genome duplication and possible functional redundancy.     

SEASONAL VARIATION IN SEXUAL SELECTION IN THE MOTTLED SCULPIN

Seasonal variation in sexual and natural selection in male mottled sculpins (Cottus bairdi) can be evaluated by calculating selection differentials, which measure the magnitude of phenotypic change resulting from selection, and by calculating indices of the opportunity for selection, which indicate the potential for phenotypic selection in a given interval. Selection differentials are high at the beginning of the breeding season and decline throughout the breeding season. The magnitude and direction of selection differentials depend on when spawning occurs and are independent of the size or age of the females that spawn. Annual selection differentials due to differences in mating success (female choice) are nearly constant between years. Annual selection differentials associated with hatching success are variable. Opportunities for selection (I = fitness variance/[mean fitness]²) show clear seasonal patterns. They are highest at the beginning and at the end of the spawning season. However, this variation is dependent on the mean used to calculate I, and hence variation in I values does not indicate a significant change in the variance of male fitness.     

Copper resistance determinants in bacteria.

Copper is an essential trace element that is utilized in a number of oxygenases and electron transport proteins, but it is also a highly toxic heavy metal, against which all organisms must protect themselves. Known bacterial determinants of copper resistance are plasmid-encoded. The mechanisms which confer resistance must be integrated with the normal metabolism of copper. Different bacteria have adopted diverse strategies for copper resistance, and this review outlines what is known about bacterial copper resistance mechanisms and their genetic regulation.     

Flow cytometric analysis and sorting of plant chromosomes from Petunia hybrida protoplasts

A method to obtain a high metaphase index and thereafter a plant chromosome suspension is described for Petunia hybrida (2n = 14). Mesophyll protoplast cultures have been used, giving easily disrupted cell walls and a high percentage of dividing cells after 42 h. On 2.5 mM colchicine-treated cells, metaphase indexes reaching 10% were routinely obtained. The lysis medium in which the protoplast-derived cells were disrupted was a simplified culture medium. After chromosome release, samples were stained with Hoechst 33342 dye and analysed by flow cytofluorometry. The histogram of fluorescence intensities included three peaks of metaphase chromosomes and a duplication of this flow karyotype provoked by "monochromatid chromosome." This interpretation was established after flow sorting; micronuclei could also be observed and sorted. Of the 7 chromosomes, only the largest formed a distinct peak while the others were incompletely resolved, due to the similar DNA content of various chromosomes. Model distributions of Petunia hybrida chromosomes have been computed according to the relative chromosome length. The theoretical histograms indicated that low variability is indispensable for resolving distinctive chromosome peaks. The experimental flow karyotype was consistent with one of the models having CV of 2.5%.     

Measurement of plasma adenosine concentration: methodological and physiological considerations

This study tested the hypothesis that measurements of plasma adenosine concentration made on samples of blood obtained in dipyridamole and EHNA (i.e., "stopping solution") may be falsely elevated as a result of ongoing in vitro production and accumulation of adenosine during sample processing. Studies were performed with samples of anticoagulated blood obtained from anesthesized domestic swine. Adenosine concentration of ultra filtrated plasma was determined by high-pressure liquid chromatography (HPLC). The following parameters were evaluated: (i) rate of clearance of [3H]adenosine added to plasma, (ii) endogenous adenosine concentration of matched blood samples obtained in "stopping solution" alone, "stopping solution" plus EDTA, and perchloric acid (PCA), (iii) plasma and erythrocyte endogenous adenosine concentration in nonhemolyzed samples, and (iv) plasma adenosine concentration of samples hemolyzed in the presence of "stopping solution" alone or "stopping solution" plus EDTA. We observed that (i) greater than or equal to 95% of [3H]adenosine added to plasma is removed from it by formed elements of the blood in less than 20 s, (ii) plasma adenosine concentration of samples obtained in "stopping solution" alone is generally 10-fold greater than that of matched samples obtained in "stopping solution" plus EDTA, (iii) deliberate mechanical hemolysis of blood samples obtained in "stopping solution" alone resulted in substantial augmentation of plasma adenosine levels in comparison with matched nonhemolyzed specimens--addition of EDTA to "stopping solution" prevented this, and (iv) adenosine content of blood samples obtained in PCA agreed closely with the sum of plasma and erythrocyte adenosine content of samples obtained in "stopping solution" plus EDTA. The data obtained demonstrate that (i) plasma adenosine concentrations are falsely elevated in samples of blood obtained in "stopping solution" alone, and (ii) addition of EDTA to "stopping solution" blocks in vitro production and accumulation of adenosine. Finally, rapid removal of adenosine from plasma by formed elements of blood may make it difficult to employ measurements of plasma adenosine concentration to assess physiological processes even in the absence of in vitro production of the nucleoside.