Combined effect of light and temperature on triacylglycerol accumulation in Dicranum elongatum

In the subarctic moss Dicranum elongatum Schleich & Schwaegr., the level of total lipids and triacylglycerols (TAG) was high in late winter and spring and low in autumn and winter. Four-week exposure of field material to continuous light (135μmol m⁻²s⁻¹) at 1°C resulted in a considerable increase in the amount of TAG in the autumn material acclimated to low temperatures and rhythmic light in the field. In contrast, the same treatment did not cause any increase in TAG in the spring material, acclimated to low temperatures and continuous light in the field. Results from experiments, in which moss cultivated for 4 months at 9°C on 12-h photoperiods (135μmol m⁻²s⁻¹) was kept for 3 weeks at low temperatures (9°C and −3°C) either in continuous light (135 or 70 μmol m⁻²s⁻¹) or with 12-h photoperiods (135 μmol m⁻²s⁻¹), indicated that the TAG level was higher at higher light intensity. At 9°C it was also higher in continuous light of both intensities than in rhythmic light. These results strongly suggest that decreasing irradiance and decreasing daylength limits the accumulation of TAG in D. elongatum during autumn in the subarctic.     

Field test of resource regulation by the bud-galling sawfly, Euura mucronata, on Salix cinerea

The attack by the bud-galling sawfly, Euura mucronata , on its willow host was simulated by removing every other living bud from previous year's shoots in a natural stand of Salix cinerea . The impact of simulated attack on the growth of the willow and the subsequent attack by E. mucronata was estimated after one growing season. Experimental bud-killing resulted in a growth reaction in S. cinerea characterized by significant increase in the length of new shoots produced by the remaining buds Also the number of buds and E. mucronata galls per shoot were significantly higher on bud-removal branches as compared with control branches. The overall survival of E. mucronata larvae was better on long shoots than on short shoots. The result shows that sawfly attack increases the amount of high quality resources for the subsequent generation of the same sawfly as predicted by "resource regulation hypothesis". We conclude that these highly specialized insect herbivores have adapted to utilize and to maintain the willow's juvenile traits. Rapid regrowth of willows after damage may have originally arisen as an adaptation in response to other, less specific pressures such as mammal browsing or snow and ice damage.     

The monoclonal antibodies Trop-4 and 4F2 detect the same membrane antigen that is expressed at an early stage of lymphocyte activation and is retained on secondary lymphocytes

The monoclonal antibodies Trop-4 and 4F2 recognize cell surface antigens present on peripheral blood monocytes, activated lymphocytes, and on continuous cell lines, but not on resting lymphocytes in blood. The membrane antigens detected by antibodies Trop-4 and 4F2 were compared by serial immunoprecipitations from membrane lysates of surface labeled T lymphoid cells and by parallel polyacrylamide gel electrophoretic analysis. It is shown that both to these antibodies recognize the heavy subunit of the heterodimeric membrane complex of an 85,000 m.w. glycoprotein disulphide linked to a light subunit of 41,000 m.w. The kinetics of the expression of the antigen was studied by indirect immunofluorescence on peripheral blood T lymphocytes during blast transformation induced by concanavalin A in vitro and during reversion of the lymphocytes back to small "secondary" lymphocytes. Upon activation of T lymphocytes with concanavalin A, the first blast cells staining with the antibodies appear within 6 hr after the initiation of the culture. After 18 hr, all blast cells displayed strong expression of the antigen. Inhibition of DNA synthesis by hydroxyurea treatment did not affect the early blast transformation and the expression of the antigen. When the mitogen-induced blast cells reverted back to small secondary lymphocytes during prolonged culturing for up to 18 days, these cells retained the expression of the antigen detected by antibodies Trop-4 and 4F2, whereas another membrane marker of activation, the transferrin receptor, rapidly disappeared. These findings demonstrate a phenotypical difference between primed, secondary T lymphocytes and resting, unstimulated cells.     

Production of protoplasts from the fungi Curvularia inaequalis and Trichoderma reesei

Summary Protoplast formation in Curvularia inaequalis was achieved using non-commercial and commercial snail gut enzymes or Trichoderma harzianum enzymes. The cells were grown for enzyme treatment on cellophane sheets or in liquid cultures for varying periods of time. The production of T. harzianum enzymes is discussed. The highest protoplast yields were 2.6x10⁷ protoplasts/ml enzyme solution. Protoplasts were shown to have zero to four nuclei. Protoplast regeneration was succesfully carried out in semisolid agar.     

On the sex chromosome trivalent in some Lepidoptera females

In four of the moth species investigated, viz. Witlesia murana, Scoparia arundinata (Pyraloidea), Bactra furfurana and B. lacteana (Tortricoidea) the metaphase plates of the first meiotic division of their oocytes show a trivalent in addition to the normal bivalents. It evidently has its rise in a transverse break in one of the conjugated chromosomes. Two sex chromatin bodies can be seen in the female somatic cells of three of these species, whereas other species with a normal XY bivalent have only one. These two sex chromatin bodies are unequal in size, and their sizes bear approximately the same relation to each other as do those of the two smaller chromosomes of the trivalent. The broken chromosome is evidently the Y chromosome. The sex chromosome designation for the four above-mentioned species is thus XY₁Y₂ for the females and XX for the males. The sex chromosomes of the four species are among the biggest of the respective complements. This supports the view that the big chromosome to be found in several Lepidoptera species is the sex chromosome. It seems that in animals with holokinetic chromosomes an excessive fragmentation is hindered, at least in the case of the sex chromosomes, by its deleterious effect on the balance of sex-determining genes.Dedicated to Doctor Sally Hughes-Schrader on the occasion of her seventy-fifth birthday.     

Accumulation and Disintegration of Starch in the Chloroplasts of Stellaria media Grown under Constant Illumination

The persent paper contains a study un the starch content of the chloroplasts of the leaves of Stellaria media, performed by hsitochemical methods. Three leaves were collected at short intervals, fixed and cut in 10 μ sections, and stained according to the PAS-procedure. The starch content of single chloroplasts was measured by a microscope photometer. The chemical composition of the stainable material was demonstrated by enzyme specific experiments. At the end of a 12 hours' dark period the chloroplasts contained only traces of starch. Light caused the starch accumulation to begin and after a time chloroplasts seemed to be filled with starch. Subsequently, however, a sudden decrease in the starch content of the chloroplasts took place, in spite of constant illumination. A rather high level of starch content was restored in a few hours. The author puts forward some ideas about the nature of the factors causing the transitory disintegration of starch in illuminated leaves. The induction or the activation of certain enzymes seems to be the most probable explanalion.     

The development of non-separation time-resolved fluoroimmunoassays for the measurement of urinary metabolites

We describe the principles of a new generation of sequential or simultaneous time-resolved fluoroimmunoassays, namely, simple, rapid, liquid-phase non-separation procedures which may be applied to the measurement of urinary steroid and drug metabolites. As an example, a method for the measurement of estrone-3-glucuronide in undiluted urine is reported. This method has a similar sensitivity, specificity and accuracy to a conventional separation fluoroimmunoassay or radioimmunoassay but in terms of speed, convenience, precision, reliability and clinical utility the new method has many advantages. The labelled antigen is a novel fluorescent europium chelate covalently linked to estrone-3-glucuronide. The antibody-binding reaction involves the incubation of the labelled antigen (2ng) with a limited concentration of polyclonal or monoclonal antibodies to estrone-3-glucuronyl-6-BSA and an aliquot of standard or sample (undiluted urine; 10 μl) in microtitre wells. After a 10 min incubation, the fluorescence which emanates from the antibody-free label is measured in a time-resolved fluorometer and is proportional to the concentration of estrone-3-glucuronide in the standard or sample. The method may be applied for the monitoring of ovarian function in women.