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Mitra, J., and F. C. Steward. (Cornell U., Ithaca, New York.) Growth induction in cultures of Haplopappus gracilis. II. The behavior of the nucleus. Amer. Jour. Bot. 48(5): 358–368. Illus. 1961.—Cells of Haplopappus, which have been stimulated to grow under the influence of coconut milk and such synergists as naphthalene or 2,4‐dichlorophenoxy acetic acid, can be cultivated as free cells, as small cell clusters, or as peripheral cells on a cultured colony or mass. Such cells display forms and cell lineages, the general pattern of which is reminiscent of those that may occur in early embryogeny. To this extent, Haplopappus resembles what has previously been observed in the growth of free cells of carrot. The form of the normal chromosome of Haplopappus (2n = 4) is described with respect to root tip cells. The range of effects which may be observed in the nuclei of the cultured cell is also described. Such variations as the following were encountered: (1) multinucleate giant cells which may divide by internal segmentation; (2) polyploidy, giving rise to highly polyploid nuclei up to, and even in excess of, 64 chromosomes; (3) somatic pairing; (4) haploidy; (5) pseudochiasmata, with the evident implication of somatic “crossing‐over”; (6) chromosome breaks, reunions and bridges, such as are commonly associated with effects of radiation and with chemical mutagens. Attention is drawn to the usefulness of this material for the further experimental investigation of the biochemical basis for the cytological events which are here described, and, if the variant cells may be cloned, of the relationship between the aberrant nuclear cytology and the ability of the cells or colonies to differentiate or to undergo morphogenesis.

Summary A kindred with Type I protein S deficiency is described in which the index case developed skin necrosis during induction of oral anticoagulant therapy for deep venous thrombosis. Two other family members with protein S deficiency have been detected, and demonstrate the clinical variability of this condition.

Mitra, J., Marion O. Mapes, and F. C. Steward. (Cornell U., Ithaca, New York.) Growth and organized development of cultured cells. IV. The behavior of the nucleus. Amer. Jour. Bot. 47(5) : 357—368. Illus. 1960.–The nuclei and the chromosomes of carrot cells have been examined at various stages throughout the following sequence: (1) growth of a tissue culture from a preformed explant of secondary phloem from the carrot root; (2) growth and multiplication of carrot cells freely suspended in a liquid medium; (3) growth and re‐formation of organs (roots) and whole plants (including flowers) from cells in the freely suspended state. The cells of the carrot are normally diploid (2n = 18), the cells which develop in the explant are also diploid, and the cells of the re‐formed organs, and even the flowers developed upon plants grown from cells, are also normal and diploid; normal meioses also occur. Nevertheless, the wide range in growth and form of the freely suspended cells is accompanied by a rich diversity of cytological conditions; these include tetraploid and highly polyploid nuclei which divide, haploidy and such chromosomal aberrations as di‐ and even tri‐centric bridges. Two division figures showing chromosome numbers at different levels of ploidy were seen within the confines of one large cell, and, in another, 2 adjacent division figures were observed with chromosome numbers lower than diploid. Small thick‐walled, densely protoplasmic cells divide to form bi‐ and tetra‐nucleate conditions, and in a giant cell a highly multinucleate condition has been seen. Despite this, however, all the regenerated roots and plants yet examined are normally diploid. The implications of these events are discussed.

Human tissues contain two isozymes of neutral a-glucosidase, neutral a-glucosidase AB and neutral a-glucosidase C (a-D-glucoside glucohydrolase, EC 3.2.1.20). The two isozymes, initially defined on the basis of differences in electrophoretic mobility in starch gel, have also been shown to have other distinguishing biochemical characteristics including different substrate specificites. Rodent tissues contain apparently homologous isozymes of neutral a-glucosidase. The mouse and human a-glucosidase C isozymes, but not the AB isozyme(s), can be distinguished by the difference in their electrophoretic mobility. This difference has previously enabled us to use human-mouse somatic cell hybrids to assign the structural gene for human a-glucosidase C to chromosome 15. We now report the differentiation of mouse and human neutral a-glucosidase AB isozymes by rocket immunoelectrophoresis, using an antibody raised in mice against purified human placental neutral a-glucosidase AB. This antibody precipitated both the A and B bands of human neutral a-glucosidase AB and did not cross react with mouse enzyme as determined by Ouchterlony double immunodiffusion and by rocket immunoelectrophoresis. Using this antibody, the segregation of human neutral a-glucosidase AB was examined in 41 mouse x human hybrid clones. Thirty-eight hybrid clones, derived from fusions of RAG x seven different human cells, showed 100% concordant segregation of human neutral a-glucosidase AB and the 11. Three additional clones, derived from a fusion of tetraploid murine erythroleukemia cells (2S-MEL) x diploid human fibroblasts carrying a translocation chromosome(s) allowed the regional localization of the gene to the long arm of 11 (11q13→11qter).

Several approaohes wcre employed to study the distribution of hetcrochromatin in root tip chromoson~es of Hnplopnppzu gmczlis. Cold treatment and prerrcahncnt in an aqucous solution of 8-liydrosyquinolinc revealed achromatic paps in metaphase chromosomes. Cold treatment also permitted thc demonstra- 3.tlon of positive heteropycnosis in prophase chrolnosonies. Further support for the identification of hetcrochromatic sxgnents was probided by a study of the localization of chromosome aberrations induced by malelc hydrazide and an analysis of the pattern of D N A synthesis in chromosomes of root tip cells. Seven of the tell regions that were preferentially broltcn by ~naleic hydrazide also reacted differentially to cold treatment or to pretreatment with 8-hydroryquinoline. A good corrclntion was found betwccn regions that completed D N A replication late in the DNA-synahetic pcriod and segments that werc slio\vn t o be hetcrochromatic by the other techniques.