Regeneration of protoplasts after somatic hybridisation of <Emphasis Type="Italic">Hydrangea</Emphasis>

Somatic hybridisation of Hydrangea is a promising tool to obtain new basic material for breeding. Viable mesophyll protoplasts were isolated from 21 cultivars and accessions of H. macrophylla, H. paniculata, H. arborescens, H. quercifolia and H. febrifuga. Induction of cell divisions was observed after electromanipulation and fusion by polyethylene glycol. Multi-cellular structures developed in liquid media. Plated microcalli grew on different solid regeneration media. Several phytohormones, their concentration and combination influenced the development of callus and roots. The regular appearance of endophytes challenged successful plant regeneration. As a result of endophytes, the development of microcolonies stopped and they died in liquid protoplast media. Plated microcalli or growing calli turned brown on regeneration medium. Antibiotic Timentin^® inhibited expansion of endophytes for a short time. The addition of ascorbic and citric acid to the regeneration media had inhibiting effect on endophyte growth. Calli showed more vitality and grew faster. The supplement of the regeneration media with karrikinolide, a recently discovered new plant growth regulator, brought contradictory results. After addition of karrikinolide microcolonies looked healthier by their shining green colour in liquid media followed by a severe browning of callus soon afterwards. In the further course, karrikinolide promoted the development of endophytes. Shoot induction and plant regeneration succeeded only once from callus that was a result from H. macrophylla ‘Schneeball’ and H. macrophylla ‘Nachtigall’ fusion.     

Proteins of theXenopus laevis zinc finger multigene family as targets for CK II phosphorylation

Zn finger proteins (ZFPs) of the C₂/H₂ type inXenopus laevis are encoded by a multigene family comprising several hundred members. Based upon conserved sequence features outside the Zn finger region, ZFPs can be subdivided into distinct subfamilies. Two of such subfamilies are characterized by conserved, N-terminal amino acid sequences termed the FAX and the FAR Domain. Here we present data suggesting that the zinc finger proteins of the FAR-ZFP subfamily are targets for CK II mediated phosphorylation. Expression of these proteins during oogenesis coincides with CK II activity in unfertilized eggs. Additionally, we have found that XIcOF 7.1, a member of the FAX-ZFP subfamily, is also phosphorylated by CK II. The target sites forin vitro phosphorylation are localized within the conserved N-terminal domains but not within the Zn finger regions. However, amino acid sequence comparison revealed that individual phosphoacceptor sites are not generally conserved among all members of the respective ZFP subfamilies. The relevance of a potential CK II phosphorylation for the regulation of ZFP activityin vivo is discussed.     

Kinetic measurements of gas exchange in the intact pulmonary microcirculation.

The kinetics of gas exchange are monitored in an isolated perfused lung preparation contained within a plethysmograph. The lungs are perfused with buffer, and there is no gas exchange until a 2.0-ml bolus of reactant is injected into the perfusion system. Subsequent gas exchange produces a pressure transient that is related to the corresponding volume of exchanged gas. The observed rate of volume change is the result of two separate processes: 1) the rate of gas exchange during transit through the capillary bed and 2) the distribution of vascular transit times between the point of injection and the capillary bed. The latter is assessed by a control injection containing a dissolved inert gas that is liberated in the alveoli as the bolus enters the capillary bed. Analysis of the experimental curves permits the separation of these two processes. A model of exchange kinetics indicates that this method has the capability of measuring kinetic events occurring during gas exchange in the microcirculation under physiological conditions.