Acta biologica Academiae Scientiarum Hungaricae最新文献

Neurospora crassa (N. crassa) inositolless (inl) strain gives inositol-independent colonies (inl+) if treated with DNA from wild type N. crassa. There is an increased number of unusual non-Mendelian tetrads (24%) among the progeny. In sexual crosses of these strains with inl alleles ascospores of complete ordered tetrads were isolated. Clones of these aberrant tetrads were examined for the inheritance of the inl+ and inl markers respectively. Several inl+ clones of single ascospores of these tetrads were often pseudowild types. These clones segregate inl+ and inl nuclei if growing on inositol-containing (complete) medium and the inl+ character shows somatic segregation, sometimes disappears very quickly. The transformed inl+ chromosomes is occasionally passed on to the next generation in sexual cross, but the ascospores are of two kinds: inl+ and pseudowild type inl+. The inl+ trait is transmitted to further generations though the ascospores of the next generation have often lower germination rate. The pseudowild types in sexual cross are sterile on minimal medium and segregate very quickly inl nuclei. The mechanism of the origin of pseudowild types is assumed to be diploidization and consequently disomy of chromosome 2.

This paper describes the neurons in different cortical areas and traces their postnatal changes. Rapid Golgi and Golgi--Kopsch impregnation were carried out in 1-day-old and 9-day-old kittens. The maturation of the pyramidal neurons can be observed mainly on their basal dendritic orientation and on development of the dendritic spines. The differentiation of the interneurons (non-pyramidal) also proceeds on the first postnatal days. These, though slightly less mature than the associated pyramidal neurons, are identifiable already on the first postnatal day. It is concluded that there are significant differences in the maturation of the neurons in the various cortical areas.

The ultrastructure of the extracellular matrix of chick limb buds at stages 24--36 was investigated with the electron microscope and with polarization microscopic evaluation of topo-optical reactions. Two types of extracellular matrix structures could be distinguished. In the primary matrix of presumptive cartilaginous areas at developmental stage 25, topo-optical reactions revealed polycarboxylated glycosaminoglycans oriented parallel to the cell surface. With the electron microscope few fine filaments and small matrix granules could be found. In the secondary cartilage matrix, from stage 26 on, topo-optical reactions demonstrated glycosaminoglycans and collagen being predominantly ordered parallel to each other. Their amount and the degree of their orientation gradually increased during the developmental period investigated. Electron microscopy demonstrated collagen filaments and matrix granules in increasing number at stages 26--36. While some parallel ordering of filaments was seen in the electron micrographs, no sign of spatial ordering of glycosaminoglycans could be found with this technique.

The chicken's gland of Harder is characterized by a lymphoepithelial structure and an abundance of plasma cells in the epithelial interstices. Using 3HTdR labelling method, it is revealed that a considerable number of lymphoid cells in the gland of Harder originates from the bursa of Fabricius. However, surgical bursectomy at hatching does not influence the development of the lymphoepithelial structure in the gland of Harder. Testosterone propionate treatment of 3-day-old embryos inhibits the bursal development but not that of the gland of Harder. These findings argue for the relative bursal independence of lymphoid development in the gland of Harder.

The analysis of per cent osteoid tissue, ash content and crystallinity of bone mineral of 67 patients 20--90 years of age, who died suddenly because of various reasons, was performed. Electron spin resonance spectrometry was used for measuring crystallinity. One-way analysis of variation of the results grouped according to sex and age showed no significant differences what concerns the ash content and crystallinity. Percentage of osteoid tissue was higher in the older groups of patients. No differences were found between males and females in the corresponding age groups. The possible mechanism responsible for the slightly higher crystallinity of bone mineral observed in the oldest group is discussed.

The biological, neural, cultural and technical evolutions and their phenomena have been explored, and on the basis of our findings the formation of a general theory of evolution has been undertaken. In each of the systems studied, the presence of structural building units, excitable structures and an energy-flow going through the system can be observed. Under the organizing effect of this energy-flow, the spontaneous generation of the replicative information begins and the structures of the system establish functional relations with each other. It can be demonstrated that the evolution of structures has a replicative character. The evolution goes through a phase of non-identical replication, and reaches the phase of identical replication. The parts of the system become separated, that is, compartments develop within it. The replicative information becomes compartmentalized and it converges. As a consequence of the convergence, the compartments compose new structural units which is tantamount to the development of new evolutional levels. The direction of evolution is determined by the growth of replicative information, and this process is concluded when the total system becomes one replicative unit. In the last part of the paper a few of the basic principles of evolution concerning matter, energy and information are drawn up.

Hybrid cells (HY SS2 and HY SS6) arising from the fusion of diploid cells of the mouse lymphosarcoma LS/BL and L cells resistant to 8-azaguanine (HGPRT-) showed slower growth and a longer generation time than the parent lines. The inter- and intrachromosomal timing and patterns of early chromosome DNA replication of parent cells was preserved in the hybrid genome and was not influenced by loss of telocentric chromosomes from LS/BL or L (HGPRT-) cells. Thus DNA chromosome replication sequences are not dependent on the presence of a complete set of chromosomes of the parent cells and do not therefore seem to be a result of interaction between chromosomes not segregated in the hybrid genome.

There are numerous nerve cells giving rise to solitary cilia of type 9 x 2 + 0, in the hypothalamic areas studied (medial preoptic nucleus, supraoptic and paraventricular nuclei, anterior periventricular nucleus, wavy paraventricular ependyma, and infundibular wall), further in the precentral gyrus and cerebellar flocculus. In the hypothalamic nuclei, the perikarya contained granular vesicles of varying sizes (800 A to 1800 A in diameter). In the supraoptic nucleus, a second neuron type was described among the lateral optic fibres. These nerve cells differ from the main neurosecretory ones by the size of their granular vesicles and their high number of large axo-somatic synapses formed by myelinated axons. In the paraventricular nucleus, axons may terminate on the basal lamina of vessels. A subependymal neuron group was described near the wavy paraventricular ependyma. The subependymal hypothalamic neuropil is characterized by various kinds of synapses including apparent "peptidergic" ones, and by axo-glial synaptic connections. The latter are also present on the apica surface of the ependyma in various regions of the 3rd ventricle. In addition, intraventricular structures (dendrites, axons, neuronal and non-neuronal perikarya, synapses) were studied by scanning (SEM) and transmission electron microscopy (TEM).

Intermediate lobe cells mechanically isolated from adult rat hypophyses were maintained in histiotypic suspension culture. The cells survived as long as six weeks. The proliferation of the connective tissue cells was limited, they did not overgrow the glandular cells. The fine structure of the parenchymal cells in the epithelial spherules of the early cultures was practically identical to that in the intact tissue. The morphological sign of exocytosed secretory material could also be found. In older cultures, cells with light and dark cytoplasm were present. The former gradually degenerated and disappeared, while the latter, forming trabecules, retained their intact fine structure. Immunoactive and bioactive ACTH was detected in the culture medium.