In vitro induction of haploid,diploid and triploid plantlets by anther culture of Iochroma warscewiczii Regel

Pollen of Iochroma warscewiczii Regel (Solanaceae) produced embryogenic calli or embryos inside anthers cultured on Nitsch & Nitsch medium. Two distinct pathways could be recognized in this process, one involving mainly the vegetative cell, and the second starting with two equal cells in the pollen grains.In all media tested, androgenesis initiation was highest when anthers contained pollen at the first mitosis, or close to it, at inoculation. High sucrose (7%) and calcium (11.3 mM) concentrations were found to be highly desirable for the induction of androgenesis in this species. Addition of benzylaminopurine (0.5 mg l^–1) to the culture medium seems to slightly improve callus or embryo production. When all three factors were present at optimal concentrations as much as 13.9% of inoculated anthers were found to be embryogenic.Plantlet development from pollen embryos required lower sucrose (3%) and a combination of 0.1 mg l^–1 benzylaminopurine and 0.5 mg l^–1 gibberellic acid in the culture medium. Cytological analysis of 55 regenerated plantlets showed that about 49% were haploids, but diploid (ca. 49%) and triploid (ca. 2%) plants were also obtained.     

CELL SURFACE ALTERATIONS BY TAXOL ASSOCIATED WITH ABNORMAL MORPHOGENESIS IN THE CHICK EMBRYO

The anticancer drug taxol brings about its biological effects by altering the stability of microtubules. We have examined the effects of taxol on early morphogenesis in chick embryos culturedin vitro. Taxol induced various abnormalities in the developing nervous system, heart and somites as well as general retardation of development. SEM studies revealed that taxol treatment leads to dramatic alterations in the embryonic cell surfaces. Time-course experiments demonstrated that the action of taxol is very rapid and becomes evident within a few minutes at the ultrastructural level. Taxol thus throws embryonic cell adhesion and motility out of balance. This appears to be the major cause of abnormal morphogenesis in taxol-treated embryos.     

Chimeric contribution of human extended pluripotent stem cells to monkey embryos ex vivo

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Long term maintenance of an anther-derived haploid callus line of the Asiatic hybrid lily ‘Connecticut King’

A haploid callus line from anther cultures of the Asiatic hybrid lily ‘Connecticut King’ was maintained for a long term. The survival and growth of the haploid calluses were affected by auxins of picloram, α-naphthaleneacetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) and temperatures of 25, 15 and 7 °C during culture. Picloram was more suitable for maintenance of the haploid calluses, whereas NAA and 2,4-D led to root and shoot formation from the haploid calluses. The best temperature for maintenance was 25 °C. About 90% of cells in calluses were maintained in haploid level during 60 weeks of subculture, and about 80% of cells were haploid in the calluses maintained over 2 years with the MS medium containing 4 μM picloram in the dark at 25 °C. This revised version was published online in June 2006 with corrections to the Cover Date.     

The effect of tumor promoters and antagonists on in vitro directional migration of 10T1/2 mouse embryo cells

In vitro directional migration of 10 T1/2 fibroblasts is partially inhibited by TPA but not by its non promoting analogues. Other tumor promoters, e.g., phenobarbital, saccharin, and benzoylperoxide had no measurable effect when added in concentrations known to affect in vitro two-step transformation or intercellular communication. Inhibitors of in vitro transformation do not affect migration, except for dexamethasone, which inhibited it. Hence, there is no evidence for a general correlation between tumor promoting potential and inhibition of in vitro directional migration.Abbreviations DDT 1,1,1-trichloro-2,2-bis(p-cholorophenyl) ethane - DEXA dexamethasone - DMSO dimethylsulfoxide - RA retinylacetate - SD standard deviation - SOD superoxide dismutase - TPA 12-0-tetradecanoylphorbol-13-acetate; 4-0-Me-TPA, 4-0-methyl-TPA     

Serosa membrane plays a key role in transferring vitellin polypeptides to the perivitelline fluid in insect embryos

In mid-embryogenesis, the stick insect Carausius morosus comes to be comprised of three distinct districts: the embryo proper, the yolk sac and the perivitelline fluid. A monolayered epithelium, the so-called serosa membrane, encloses the yolk sac and its content of vitellophages and large yolk granules. During embryonic development, the yolk sac declines gradually in protein concentration due to Vt polypeptides undergoing limited proteolysis to yield a number of Vt cleavage products of lower molecular weights. mAbs 1D1 and 5H11 are monoclonal antibodies raised against some of the Vt cleavage products generated by this process in the yolk sac. At the confocal microscope, antibody fluorescence is initially associated with a few yolk granules, while it is gradually displaced in the cytosolic spaces of the vitellophages. With the proceeding of embryonic development, label appears also in the serosa membrane in the form of clustered dots. At the ultrastructural level, gold particles are initially associated with the vitellophages that are labeled on a few yolk granules and in the cytosolic space flanking the yolk granules. Subsequently, the serosa cells become labeled on vesicles close to the yolk granules or just underneath the plasma membrane. Inside the serosa cells, label is also associated with granules budding from the Golgi apparatus, but never with the intercellular channels percolating the serosa membrane. These observations are interpreted as indicating that Vt cleavage products leak out from the yolk granules into the cytosolic spaces of the vitellophages and are eventually transferred to the perivitelline fluid via transcytosis through the serosa cells.     

Separation of precultured pollen from Nicotiana tabacum by aqueous polymer two-phase partition

Pollen isolated from cold treated and precultivated anthers of tobacco (Nicotiana tabacum L. var. Wisconsin 38) were separated into different fractions with counter-current distribution using an aqueous Dextran-polyethylene glycol two-phase system. It was possible to distinguish among eight pollen classes differing in developmental stage and in partitioning. A part of each fraction was cultivated for analysis of embryo formation. This was highest in a fraction with an intermediate to high partition in the phase system. Enriched in this fraction were also pollen that were fairly well stained with acetocarmine, contained several nuclei and had a relatively low mitochondrial activity. The enrichment of embryogenic pollen offers several advantages especially to physiological studies on embryogenesis.     

The role of FGF signaling in guiding coordinate movement of cell groups: Guidance cue and cell adhesion regulator?

Cell migration influences cell-cell interactions to drive cell differentiation and organogenesis. To support proper development, cell migration must be regulated both temporally and spatially. Mesoderm cell migration in the Drosophila embryo serves as an excellent model system to study how cell migration is controlled and influences organogenesis. First, mesoderm spreading transforms the embryo into a multilayered form during gastrulation and, subsequently, cells originating from the caudal visceral mesoderm (CVM) migrate along the entire length of the gut. Here we review our studies, which have focused on the role of fibroblast growth factor (FGF) signaling, and compare and contrast these two different cell migration processes: mesoderm spreading and CVM migration. In both cases, FGF acts as a chemoattractant to guide cells’ directional movement but is likely not the only signal that serves this role. Furthermore, FGF likely modulates cell adhesion properties since FGF mutant phenotypes share similarities with those of cell adhesion molecules. Our working hypothesis is that levels of FGF signaling differentially influence cells’ response to result in either directional movement or changes in adhesive properties.