Tissue culture studies of retinal development

Because of a limited number of cell types, a series of well-described cell-type-specific markers and a stereotyped sequence of cell development, the retina has been a valuable model of CNS development. Dissociated and explant cultures have been used to help define some of the requirements for differentiation of each major cell class. In addition to mixed-cell cultures it is now possible to use cell purification or selective growth methods to give cultures of single cell types. Alteration of gene expression by viral infection has proved to be a valuable method to help elucidate developmental pathways.     

Tissue culture studies on species ofPassiflora

The effect of different explant sources, growth regulators and coconut water concentrations and also light radiation on tissue cultures ofPassiflora edulis var.flavicarpa was evaluated.In addition, plant regeneration was obtained from a diversity ofPassiflora germplasm. For shoot morphogenesis either cotyledonary, hypocotyledonary or leaf tissues were used to obtain cultures that formed shoots when placed on Murashige & Skoog basal medium containing 6-benzylaminopurine and coconut water. Direct organogenesis was observed.Apex cultures have been also achieved fromP. edulis var.flavicarpa, P. mollissima, P. giberti, P. maliformis andP. amethystina. Excised explants 5 mm length were placed on half-strength basal medium, free of hormones. Whole plants were recovered.Abbreviations BA 6-benzylaminopurine - CW coconut water - MS Murashige & Skoog (1962) medium - NAA 1-naphthaleneacetic acid     

Tissue culture studies; standardization of techniques for quantitative culturing

Reproducible conditions have been described for quantitative tissue culturing in which all constituents including the tissue itself are added in known quantities to the culture. The conditions for transfer, cutting, and manipulation of tissue are also described. The data show that such culturing can be performed without loss or significant alteration of the nitrogen and phosphorus content of the tissue.     

Polarographic assay of nicotinic acid in the culture liquid]

The method of potarographic assay of nicotinic acid in the culure liquid has been developed. The effect of all the constituents of the culture liquid on the accuracy of measurements has been tested. The analytic scheme which provides elimination of interfering components has been devised. As the polarographic medium 0.1 n HCl was used. The quantity of nicotinic acid was measured with respect to the wave of E1/2 = - 1.18 v. The described method makes it possible to identify nicotinic acid at concentrations of 3.3 X 10(-4) M to 3.3 X 10(-3) M in the culture liquid with an error of not more than +/-5%.     

Tissue culture studies; the relationship of nucleic acid increase to the growth of cells in vitro

The content of ribo- and desoxyribonucleic acids in chick heart cultures at regular intervals after implanting has been determined both with standard culture medium and with Tyrode's solution alone. With an inadequate medium, both nucleic acids dropped in a consistent manner but ribonucleic acid was affected to a much greater extent. When the medium was adequate for growth, both fractions rose smoothly and paralleled each other closely, after an initial drop. The final content of each fraction was markedly higher than the amount present in the original implant. The fundamental definition of growth and the relationship of these data to it are discussed.     

Analogues of mycophenolic acid

Analogues of mycophenolic acid were produced by cultures of Penicillium brevi-compactum fed, respectively, with 4,6-dihydroxycoumaran-3-one, 5,7-dihydroxyindan-1-one, and 2,4-dihydroxyacetophenone.