Two modes of cell migration in the ventral horn of the spinal cord in the chick embryo. A Golgi study

The migration process of the ventral horn in chick embryo spinal cord cells has been studied between 2.5 and 5 days of incubation (HH-17, HH-26), using the Golgi technique. Two different migratory modes are observed. Type I--Migration by nucleus translocation. Most of the ventral horn motor neurons migrate by nucleus translocation within the peripheral cylinder of the cytoplasm (migration by nucleus translocation). Type II--Free migration cells. Other cells migrate disconnected from both limiting surfaces (ventricular and pial). On the basis of shape and migratory behaviour they have been identified as smooth cells and multipodial cells.     

Substance P affects the GABAergic system in the hypothalamo-pituitary axis

In the present work we examined the effect of the neutralization of endogenous substance P by the administration of an anti-substance P serum (ASPS) on GABA concentration in the anterior pituitary in hyperprolactinemic conditions induced by 5-hydroxytryptophan or by grafting anterior pituitaries. ASPS reduced the increase in the anterior pituitary GABA concentration induced by hyperprolactinemia. In vitro experiments showed that substance P inhibited K⁺-evoked GABA efflux from hypothalamic fragments and decreased GABA concentration in the anterior pituitary but ASPS increased it. Our results demonstrate that substance P modifies hypothalamic GABA release and anterior pituitary GABA concentration and suggest that an interaction exists between substance P and GABA.     

Ryanodine receptor purified from crayfish skeletal muscle

The ryanodine receptor was isolated from the sarcoplasmic reticulum of crayfish skeletal muscle. Ryanodine binding to the native fraction was measured by Scatchard analysis and values of 60 nmol/l and 9 pmol/mg were obtained for KD and Bmax respectively. The identity of purified receptor was confirmed by electron microscopy, electrophoresis and incorporation into planar lipid bilayers. At least two conductance states (100 pS and 50 pS) were observed in 100 mmol/l NaCl both for native and purified receptor.     

Environmental influences on the sensitization by drugs measured in peripheral blood lymphocyte chromatin

An "allergo-kinetic" method was introduced, which measures early changes of nuclear chromatin structure of lymphocyte subpopulations. The method is used as an in vitro test for drug allergy. The comparison of data from two sampling places (Budapest-Esztergom) shows the following results: The drug allergy scores (obtained from T-cells) may reflect environmental influences on the population under study. During the 13 months period after Atomic Reactor accident in Chernobyl, both the frequency of severe skin manifestations and that of organ manifestations (without skin lesions) increased. The ratio of negative test results decreased in both of drug allergic patient groups (small town = Esztergom, large city = Budapest)--tendency to polysensibilization. The scores obtained in drug related groups of generalized urticaria and Quincke's oedema increased significantly within 13 months after accident followed by a normalization in the subsequent year.     

Multielectrode culture chamber: a device for long-term recording of bioelectric activities in vitro

A multi-microelectrode culture chamber system was constructed for monitoring simultaneously morphological and electrophysiological development of neural cells in vitro. The setup consisted of a pattern of gold conductor lines evaporated onto a glass substrate and insulated with polyamide. The width of each electrode was 10 microns, and the distance between the electrodes was 60 microns. The electrode patterns were constructed and the uncovering of the electrode tips were carried out by photo-etching. This system allowed us to record spontaneous activities in both explant- and primary monolayer cultures of either rat or mouse spinal cords and forebrains, during neuronal regeneration and maturation.     

Ultrastructural localization of silver-staining nuclear proteins at the onset of transcription in early bovine embryos.

Argyrophilic nuclear proteins, known to be functionally associated with ribosomal genes, were localized, in four-, eight-, and 16-cell bovine embryo blastomere nuclei using two different silver-staining procedures. Within the eight-cell cleavage stage by the process of embryonal nucleologenesis in the cow embryo the full-capacity ribosome-producing machinery is established. In the four-cell embryo, many patches and islands of argyrophilic (Ag+) material were detected in the nucleoplasm. The nucleolus-precursor bodies (NPBs), composed uniformly of a homogeneous compact mass, were completely devoid of any silver staining. On the other hand, clear-cut localization of argyrophilic proteins was detected during the eight-cell stage either inside the transforming NPBs or in the close vicinity, or in the already differentiated nucleolus. In compact, nonvacuolated NPB, an intensive Ag+ area was detected, in the form of a lenticle, at the periphery of the NPB. During and following vacuolation of the NPB, no Ag+ was detected inside these vacuoles. It was seen, however, in the dense fibrillar nucleolar component surrounding the smaller vacuoles formed at the time of the establishment of nucleolar structure. Ag+ areas were seen repeatedly in the vicinity of NPBs, probably a part of the nucleolus-associated chromatin or, alternatively, representing the extranucleolar bodies. In blastomere nuclei of 16-cell embryos, already possessing reticulated nucleoli known from intensively synthesizing somatic cells, the silver-staining pattern corresponded to the usual situation in differentiated cells: slight staining of fibrillar centers, heavy labelling in the dense fibrillar component, and absence of silver deposits in the granular component.(ABSTRACT TRUNCATED AT 250 WORDS)     

Planktic coccal and trichal green algae of Lake Volvi,Greece

In the course of three years' investigations (1983–1986) of Lake Volvi, N Greece, 62 species and varieties of chlorococcal algae and 6 species of ulotrichal algae (Chlorophyceae) were found. Although chlorophytes form the largest group of the phytoplankton assemblages of the lake, their biomass is relatively small or even negligeable in some periods of the year in comparison with domination cyanophytes, diatoms and cryptophytes. Morphological variation of diagnostic features is described and documented by original drawings in 53 taxa.     

Ecotoxicological contamination processes: Interaction with vegetation (a review)

Up-to-date crop production concentrates on the maximisation of plant matter production, both by optimum utilization of solar energy by plants and by the application of additional energy. Therefore a natural strategy is being developed aimed at combining the physiological functions of the assimilation organs with their external shaping and strengthening their variety in space and area. As demonstrated by many deposition studies, this effect is contradictory to the factors conditioning the low deposition capacity of plant covers. A high level of particle, gas and solution deposition increases the danger of food chain contamination and has a negative impact on plant production. Data concentrated on transport values of pollutants and their long-term dynamics in stands could be used for the selection of ideal crop types; therefore every effort should be directed towards selection and breeding.