Search

Cytokinins regulate chloroplast differentiation and functioning, but their targets in plastids are not known. In this connection, the plastid localization of the 70 kDa cytokinin-binding protein (CBP70) was studied immunocytochemically in 4-d-old etiolated maize seedlings (Zea mays L., cv. Elbrus) using monoclonal antibodies (mAbs) against CBP70 recognizing this protein not only in nuclei and cytoplasm, but also in plastids. CBP70 was detected in the amyloplasts of the root cap and etioplasts of the mesocotyl, stem apex, and leaves encircling the stem axis in the node. Immunogold electron microscopy demonstrated CBP70 localization in amyloplasts outside starch grains and revealed a dependence of CBP70 content in etioplasts on the degree of their inner membrane differentiation: the low CBP70 amount in etioplasts at the early stages of membrane development, the high content in etioplasts with actively developing membranes, and a considerable decrease in plastids with the formed prolamellar body. This suggests that CBP70 is involved in etioplast structure development. CBP70 was also observed in chloroplasts of the bundle sheath of green maize leaves. CBP70 purified from etioplasts mediated trans-zeatin-dependent activation of transcription elongation in vitro in the transcription systems of maize etioplasts and barley chloroplasts, suggesting that CBP70 is a plastid transcription elongation factor or a modulator of plastid elongation factor activity. CBP70 involvement in the cytokinin-dependent regulation of plastid transcription elongation could be essential for the cytokinin control of the biogenesis of this organelle.

The distribution pattern of a 70 kDa cytokinin-binding protein (CBP70) was studied in 4-d-old etiolated maize seedlings (Zea mays L., cv. Elbrus). CBP70 was detected in crude protein extracts of all root zones and shoot parts by western blotting and by the sandwich ELISA (enzyme-linked immunosorbent assay) technique, using a pair of monoclonal anti-CBP70 antibodies cross-reacting with non-overlapping protein epitopes. The highest amount of CBP70 was found in the root meristem, which corresponds to the concentration in the meristem of zeatin, its riboside, nucleotide, and 9N-glucoside. CBP70 accumulation was also detected in other zones of cell division: in the root cap, shoot apex, and vascular tissues, suggesting involvement of the protein in the processes related to cell proliferation. This suggestion was also supported by CBP70 distribution in the root meristem: mitotically inactive cells of the quiescent centre did not contain a detectable amount of the protein. Stem cells adjoining the quiescent centre contained less CBP70 than their daughter cells. Using monoclonal antibodies against CBP70 for immunocytochemistry, the presence of the protein in the cytoplasm and its accumulation in nuclei and especially in nucleoli was demonstrated; such a pattern was observed in all cell types of seedlings. The subcellular distribution pattern of CBP70 was analysed by immunogold electron microscopy of the meristem and leaf cells; CBP70 was localized in the cytoplasm and nucleoplasm, and its highest concentration was detected in nucleoli. CBP70 was not detected in the vacuole and cell wall. In the RNA polymerase I model system, purified CBP70 mediated a trans-zeatin-dependent activation of transcription in vitro, and anti-CBP70 monoclonal antibodies blocked this activation. Other natural and synthetic physiologically active cytokinins also activated transcript elongation in the model system in the presence of CBP70. Adenine and inactive analogues of cytokinins had no such effects. These data suggest that CBP70 is a transcript elongation factor or a modulator of elongation factor activity specifically mediating a cytokinin-dependent regulation of transcription.

The following method of examination of patients with chronic primary gastroduodenitis is proposed: 1) clinical examination; 2) roentgen and endoscopic examination; 3) assessment of genetic predisposition to ulcer disease; 4) examination of the acid- and pepsin-forming gastric function; 5) determination of the pepsin aggression ratio; 6) determination of the gastric juice defense ratio; 7) biochemical examination of the amino acid composition of the gastric mucosa; 8) determination of the lipid peroxidation intensity. The obtained data indicate that chronic primary gastroduodenitis is not a pre-disease but an initial stage of ulcer disease.

Electroolfactograms were recorded in isolated olfactory epithelium of pigs, both females and castrated males, of various age. The boar pheromone, 5 alpha-androst-16-en-3-one, elicited negative electrical responses up to 2 mV in many preparations. The threshold response corresponded to as low as 10(-9) g of the pheromone on a filter paper. The specific anosmia to the boar pheromone was discovered in few preparations, where responses to the pheromone were absent and the sensitivity to common odour substances (butyl acetate, camphor, butyric acid, etc.) was unchanged.

In field experiments, studies have been made on sex attractiopn of males in the moth L. pomonella. Cis-8-dodecenyl acetate (DDA) was confirmed to be a potent inhibitor of male attraction to the traps baited with virgin females or to a synthetic sex attractant (sex pheromone) trans-8,10-dodecadienol (DDD). DDA also slightly reduced the mating activity under laboratory conditions. The inhibitory effect of DDA on male sex attraction was studied by means of electroantennogram technique. Male antennae were stimulated by DDD and DDA either separately or in combination, DDA vapours being superimposed on the constant DDD background. DDD evoked always negative (excitatory) EAGs, but DDA elicited complex EAGs including both negative and positive (excitatory) EAGs, but DDA elicited complex EAGs including both negative and positive waves. Experiments with double stimulation showed that DDD and DDA produce excitation in different groups of the olfactory receptor cells. Besides, DDA was found to inhibit the EAG evoked by DDD. This inhibition is presumably due to hyperpolarization of the DDD-sensitive cells. Both physiological effects may be involved into inhibition of behavioural reactions in males. The inhibitory mechanism based on competition between DDA and DDD molecules for common receptor sites, seems to be lessprobable.