Genome relationship betweenPsathyrostachys huashanica andP. fragilis (Poaceae)

Hybrids between the Chinese endemic speciesPsathyrostachys huashanica Keng and the SW. Asian speciesP. fragilis (Boiss.)Nevski (all 2n = 14) developed normally but were completely sterile. Meiotic analyses revealed a high chiasma frequency indicating that the two species as well asP. juncea (Fisch.)Nevski share the same basic genome (called N). The hybrid nature of the plants was established through karyotype analysis and Giemsa C-banding.     

An acetyl esterase of Trichoderma reesei and its role in the hydrolysis of acetyl xylans

Summary An acetyl esterase was purified from Trichoderma reesei by cation and anion exchange chromatography. The enzyme had a molecular weight of 45 000 as determined by SDS-electrophoresis, or 67 000 as determined by gel filtration. In chromatofocusing the enzyme was shown to consist of two isoenzymes with isoelectric points of 6.8 and 6.0. The enzyme showed activity towards naphthyl acetate, triacetin and glucose-and xylose acetates. However, it liberated acetic acid from acetylated xylo-oligomers only to a small extent. The liberation of acetic acid from the oligomeric substrate was enhanced by addition of endoxylanase and -xylosidase.     

Characteristics of the mutagenic and toxic effects of ethylene imine and its oligomers. Comparative study in the automated SOS-chromotest system and in standard bacterial test systems

Raising total positive charge of a chemical mutagen does increase its local concentration in the area of biological target-DNA, and, as a consequence, causes increase in the rate of interaction of a mutagen with the target. Experimental evidence of this idea has been obtained in three test systems: the Ames test, Trp+ reversions in Escherichia coli WP2 and in the automated "SOS-chromotest" system with E. coli PQ 37 ("Labsystems", Finland).     

Spatial patterns and relationships between phytoplankton, zooplankton and water quality in the Saimaa lake system, Finland

The interactions between phytoplankton and zooplankton were studied in two large lakes in the Saimaa lake system, Finland. Both are subjected to substantial waste water loading, and exhibit a clear trophic gradient between the loaded and unloaded areas. The phytoplankton and zooplankton were compared in terms of composition, abundance and biomass at 34–39 stations located in different parts of the lakes. At least four mechanisms were thought to affect the composition of plankton communities: (1) the amount of nutrients (trophic gradient), (2) grazing of algae by herbivores, (3) the effect of the algal species composition on feeding by zooplankters (large, colonial algae in the more loaded parts of the lakes) and (4) the regeneration and reorganization of nutrients.     

Carbohydrate distribution and cellular injuries in acid rain and cold-treated spruce needles

Summary The cellular structures of acid rain-irrigated needles of several provenances of Norway spruce (Picea abies L. Karst) seedlings were studied after winter experimental freezing. Frost injuries and recovery were characterized by visual damage scoring and classification of mesophyll cell alterations, also using histochemical methods for carbohydrate fluorescent staining. The treatment with-30° C during the late dormancy period was sufficient to cause significant injuries and intracellular degradation in the tissues of the green needles. The most affected seedlings in terms of visual injury scoring were found among those treated with clean water or at pH 3, while freezing injury, defined as an occlusion of phenolic substances in the central vacuole of the mesophyll cells, was most abundant in the needles from spruces irrigated either with clean water or at pH 4 or pH 3. Electron microscopy revealed the details of the injury, e. g. thinning out of the cytoplasm and chloroplast stroma, darkening of the chloroplasts and eventually swelling of the chloroplasts and protoplast. PAS and ConA reactions in the needle tissue revealed intense starch accumulation in the mesophyll and transfusion tissues as early as in March, with a tendency to increase, especially in the untreated needles during the recovery period. Plasma membrane disturbances were indicated by histochemical identification of callose deposits in the mesophyll cell walls, these being most abundant in the acid rain-treated needles. All these findings suggest that freezing at –30° C was more deleterious to the seedlings pretreated with acid or clean water than to those not given additional irrigation.     

DDT (dicophane) and postmenopausal breast cancer in Europe: case-control study.

OBJECTIVE: To examine any possible links between exposure to DDE (1,1-dichloro-2,2-bis (p-chlorophenyl)ethylene), the persistent metabolite of the pesticide dicophane (DDT), and breast cancer. DESIGN: Multicentre study of exposure to DDE by measurement of adipose tissue aspirated from the buttocks. Laboratory measurements were conducted in a single laboratory. Additional data on risk factors for breast cancer were obtained by standard questionnaires. SETTING: Centres in Germany, the Netherlands, Northern Ireland, Switzerland, and Spain. SUBJECTS: 265 postmenopausal women with breast cancer and 341 controls matched for age and centre. MAIN OUTCOME MEASURE: Adipose DDE concentrations. RESULTS: Women with breast cancer had adipose DDE concentrations 9.2% lower than control women. No increased risk of breast cancer was found at higher concentrations. The odds ratio of breast cancer, adjusted for age and centre, for the highest versus the lowest fourth of DDE distribution was 0.73 (95% confidence interval 0.44 to 1.21) and decreased to 0.48 (0.25 to 0.95; P for trend = 0.02) after adjustment for body mass index, age at first birth, and current alcohol drinking. Adjustment for other risk factors did not materially affect these estimates. CONCLUSIONS: The lower DDE concentrations observed among the women with breast cancer may be secondary to disease inception. This study does not support the hypothesis that DDE increases risk of breast cancer in postmenopausal women in Europe.     

Expression of genes for plastid membrane proteins in barley under intermittent light conditions

Barley plants grown under intermittent light show a plastid membrane composition intermediate between those of etioplasts and chloroplasts. In particular protochlorophyll reductase disappears from the membranes whereas the 32000 protein, coded for by chloroplast DNA, becomes integrated into the membranes. The light-harvesting chlorophyll a/b protein does not accumulate within the membranes even after 11 d of development, while the corresponding mRNA can already be observed after 4 d and is translated under in vivo conditions.Abbreviations LHCP light-harvesting chlorophyll a/b protein - IL intermittent light - LD light-dark (12-h day) - EGTA ethyleneglycol-bis(oxy-ethylenenitrile)tetraacetic acid