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.     

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].     

Cosinor analysis of diurnal changes of the reduced glutathione level in the blood, brain, liver and kidneys of mice, induced by ACTH administration

The influence of a single dose of ACTH(100 I.U. /kg body weight) on the diurnal rhythm of reduced glutathione (GSH) was studied in the blood and brain, liver and kidney homogenates of male mice. Cosinor analysis revealed that ACTH induces changes in the mean diurnal amount of GSH in the blood, brain, liver and kidneys. At the same time, GSH amplitudes in the blood and kidneys increased significantly, whereas in the case of brain and liver they decreased markedly. Moreover, it was found that ACTH induces a shift in GSH acrophases in the blood, brain, liver and kidneys as compared with the control values.     

Potentiation of antitumor effects of tumor necrosis factor α and interferon γ by macrophage-colony-stimulating factor in a MmB16 melanoma model in mice

The efficacy of systemic infusion of recombinant human macrophage-colony-stimulating factor (M-CSF) in combination with local treatment with human recombinant tumor necrosis factor (TNF) and mouse recombinant interferon (IFN) was studied in vivo on a subclone of B16 melanoma (MmB16) in mice. Short-term intravenous administration of M-CSF at a dose of 10⁶ units daily had no antitumor effect in vivo. Similarly, local treatment of tumor with TNF (5 g daily) did not produce any therapeutic effect. However, simultaneous administration of the same dose of TNF with IFN (1000 units daily) resulted in a synergistic effects manifested by the retardation of tumor growth. Addition of systemic infusion of M-CSF to the local therapy with TNF and IFN induced further augmentation of antitumor efficacy and delayed progression of MmB16 melanoma. The strengthened antitumor effect of combination therapy including M-CSF, TNF and IFN was most probably due to the increased release of monocytes from the bone marrow, their recruitment into the site of tumor growth and subsequent local stimulation of their antitumor activity.     

Seasonal changes in the number of neurocytes containing lipofuscin pigment in selected areas of the brain of Rana temporaria L

The number of neurocytes containing lipofuscin pigment (LEP) was determined in the nucleus infundibularis dorsalis (NID), the subfornical organ (SFO) and the medulla oblongata (MO) of the brain of sexually mature females and males of Rana temporaria L. approximately identical in length and age. The frogs were captured in their natural habitat in seven periods of the annual cycle. The number of LFP-positive neurocytes shows distinct seasonal variations in the analyzed areas. In general, neurocytes containing LFP were found in higher numbers during the winter months, and their significant drop was observed in summer. The results seem to suggest that cells containing LFP represent a certain kind of dynamic cellular system responding to various internal and/or external factors changing within a year.