Non-Decarboxylating transformation of indol-3-ylacetic acid in apple seeds

An enzyme extract from apple(Pyrus malus Borb.) seeds which causes the disappearance of free indol-3-ylacetic acid (IAA) requires the presence of oxygen, but is not inhibited by cyanide. Using 1-¹⁴C-IAA it has been demonstrated that the IAA transformation is not accompanied by its decarboxylation. Decarboxylating IAA oxidase is absent during the whole period of apple seed cold stratification. Free IAA has not been detected in dormant apple seeds and in seeds stratified at low temperature. It appears during stratification at 25 °C. Ethyl ester of IAA and indol-3-ylacetyl aspartate have been identified in dormant and after-ripened seeds. Exogenous 1-¹⁴C IAA taken up by apple embryos is converted into conjugates with aspartate and short peptides containing an aspartate moiety.     

Hydrogen cyanide and embryonal dormancy in apple seeds

Embryos of apple ( Malus domestica Borh. cv. Antonówka) were treated with 1 m M gaseous HCN for 6 h and cultured under a 12 h photoperiod. HCN pretreatment stimulated germination, increased the length of hypocotyls, shortened the main root and decreased the percentages of seedlings with asymmetrically grown as well as with asymmetrically greened cotyledons. High activity of β-cyanoalanine synthase (EC 4.4.1.9) and a sharp increase in cyanogen content during embryo culture suggested very low levels of endogenous HCN. despite the activity of HCN releasing enzymes. The obtained data allow us to postulate an important role for cyanide in the regulatory complex controlling dormancy in apple seeds. Experiments with respiratory inhibitors indicated, however, that HCN pretreatment affected neither the alternative electron transport pathway nor residual respiration.     

The effect of fish predation on Cyclops life cycle

Two populations of Cyclops abyssorum tatricus studied in neighbouring alpine lakes in Tatra Mountains (southern Poland) differed in their life cycles. In the lake with planktivorous fishes, Cyclops was typically monocyclic, with highly synchronized reproduction during two winter months, while in the fishless lake its reproduction was asynchronous and continued for six months. Direct and indirect effects of fish predation on Cyclops life cycles are discussed.     

Cytogenetic analysis of peripheral blood lymphocytes in glass workers occupationally exposed to mineral oils

Chromosome aberration tests were carried out in a group of 31 pressed glass makers operating an automatic line of press-and-blow machines known to release mineral oil mists containing relatively high concentrations of the mutagenic chemicals belonging to a class of polycyclic aromatic hydrocarbons (PAH). The workers were exposed to the mineral oil aerosol levels that did not exceed the Czechoslovak maximum allowable concentration limit of 5 mg . m-1 of air. The tests revealed that the frequency of aberrant cells (% AB.C.) and the value of breaks per cell (B/C) ratio found in mineral oil-exposed workers were increased significantly, accounting for 4.65 +/- 0.29% AB.C. (0.0532 B/C) vs. 1.13 +/- 0.19% AB.C. (0.0113 B/C) seen in matching controls. Also, a higher rate of dicentrics, reciprocal translocations and cells with pulverization was observed in this group of glass workers. These finding are considered as evidence suggesting that these workers might experience an increased risk of genetic injury due to exposure to mineral oil mists.     

Cytochromec oxidase fromParacoccus denitrificans in Triton X-100: Aggregation state and kinetics

Cytochromec oxidase fromParacoccus denitrificans was homogenously dispersed in Triton X-100. Using gel exclusion chromatography and sucrose gradient centrifugation analysis a molecular weight of the detergent-protein complex of 155,000 was determined. After subtraction of the bound detergent (111 mol/mol hemeaa ₃) a molecular weight of 85,000 resulted, which agreed well with the model of a monomer containing two subunits. This monomer showed high cytochromec oxidase activity when measured spectrophotometrically in the presence of Triton X-100 (V _max=85 s^–1). The molecular activity, plotted according to Eadie-Hofstee, was monophasic as a function of the cytochromec concentration. AK _m of 3.6×10^–6 M was evaluated, similar to theK _m observed in the presence of dodecyl maltoside [Naeczet al. (1985).Biochim. Biophys. Acta 808, 259–272].     

Contribution to the structural characterization of gamma globulin from pig colostrum

From the results obtained in the present work it is concluded that gamma globulin of the 7 S type (γG) which represents the main immunoglobulin component of pig colostrum, differs from serum γG globulin by the presence of another type of polypeptide chain, designed L₂; the latter was detected after S-sulfonation in starch gel electrophoresis as the fastest moving component and its immunoelectrophoretic pattern shows the presence of two precipitating components. Preparation of soluble heavy and light chains enabled us to study them imunochemically. The heavy chain is represented by two zones; the fainter one was not detected in comparative analysis of the heavy chain of serum γG globulin. The L₁ chain of colostral gamma globulin and the light chain of serum gamma globulin seem to contain three precipitating components, one of which appears due to aging of the chain solution in the presence of glycine. The material from colostrum seems to contain a larger amount of this component than serum. Further it was shown that the component arising in this way is antigenically closely related to the heavy chain.     

Follicular dynamics during the ovulatory season in goats

Growth and regression of ovarian follicles>or=3 mm were studied by transrectal ultrasonography for 4 interovulatory intervals in each of 5 Saanen goats. The observed number of growing identified 4-mm follicles per day differed (P<0.05) from randomness, indicating that follicles, on the average, emerged in groups (waves). Averaged over all interovulatory intervals, the number of 3-mm follicles on each day that later reached >or=6 mm followed a pattern of significant peaks on Days 0 (ovulation), 4,8 and 14. A follicular wave was defined by consecutive days of entry of follicles>or=6 mm into the wave, and the day of emergence was defined as the first day that the >or=6 mm follicles were 3 mm. In 15 of 20 (75%) interovulatory intervals, 1 wave emerged during each of Day -2 to Day 1 (Wave 1); Days 2 to 5 (Wave 2); Days 6 to 9 (Wave 3); and Days 10 to 15 (Wave 4). Ovulation occurred during Wave 4. The mean days of emergence of Waves 1 to 4 were Days -1, 4, 8 and 13, respectively. However, in 5 of these 15 interovulatory intervals, 50% of the apparent waves merged or were continuous so that a distinction could not be made between 2 waves. The largest follicle grew to a larger (P<0.05) maximum diameter for Waves 1 (8.7+/-0.3 mm) and 4 (9.7+/-0.3 mm) than for Waves 2 (7.2+/-0.2 mm) and 3 (7.3+/-0.2 mm). The following observations suggested that the phenomenon of follicular dominance was more common during Waves 1 and 4 than during Waves 2 and 3: 1) the interwave intervals (days) were longer (P<0.05) for Waves 1 (3.4+/-0.2) and 4 (4.3+/-0.6) than for Waves 2 and 3 (2.5+/-0.2 for each wave) and 2) the correlation between maximum diameter of largest follicle and the subsequent interwave interval was significant for Waves 1 and 4 but not for Waves 2 and 3. The 5 remaining interovulatory intervals were irregular and involved more than 4 waves, including 2 interovulatory intervals with prolonged follicular phases (14 and 21) and failures of ovulation. In conclusion, the predominant follicular-wave pattern was 4 waves with ovulation from Wave 4, and apparent follicular dominance was expressed during some follicular waves, especially during Waves 1 and 4.