Selection of hydroxyproline-resistant proline-accumulating mutants of cauliflower. C.R. Deane, M .P. Fuller' & P.J. Dix

A procedure is described by which hydroxyproline-resistant lines could be selected from regenerating curd tissue of cauliflower. Mutagenesis was by N-nitroso-N-ethylurea, supplied as a drop of 0 .3 mM solution on each 3 mm diameter curd piece. The mutagen generated numerous morphological and pigment mutations without significantly affecting shoot regeneration from explants . Thirty one resistant shoots were recovered from more than six thousand explants mutagenised on regeneration medium supplemented with 3 mM hydroxyproline, while none was obtained from a similar number of non-mutagenised controls . Out of twenty-three resistant shoots which survived subculture, only one showed consistently elevated levels of endogenous proline . During early shoot culture passages, proline levels were 3 .6-4.7 times higher than controls, but this was reduced to 1 .6 times after 10-12 culture passages in the absence of hydroxyproline . Possible reasons for this decline are discussed . Leaf strip assays suggest resistant shoots may be chimeras and current efforts are directed towards regenerating solid mutants from resistant sectors . These will then be evaluated for any alteration in frost tolerance

In vitro strategies for improvement of frost tolerance in cauliflower.

Two in vitro selection strategies were employed in an effort to obtain cauliflower lines with improved cold tolerance

In vitro strategies for improvement of frost tolerance in cauliflower.

Two in vitro selection strategies were employed in an effort to obtain cauliflower lines with improved cold tolerance

Selection of hydroxyproline-resistant proline-accumulating mutants of cauliflower. C.R. Deane, M .P. Fuller' & P.J. Dix

A procedure is described by which hydroxyproline-resistant lines could be selected from regenerating curd tissue of cauliflower. Mutagenesis was by N-nitroso-N-ethylurea, supplied as a drop of 0 .3 mM solution on each 3 mm diameter curd piece. The mutagen generated numerous morphological and pigment mutations without significantly affecting shoot regeneration from explants . Thirty one resistant shoots were recovered from more than six thousand explants mutagenised on regeneration medium supplemented with 3 mM hydroxyproline, while none was obtained from a similar number of non-mutagenised controls . Out of twenty-three resistant shoots which survived subculture, only one showed consistently elevated levels of endogenous proline . During early shoot culture passages, proline levels were 3 .6-4.7 times higher than controls, but this was reduced to 1 .6 times after 10-12 culture passages in the absence of hydroxyproline . Possible reasons for this decline are discussed . Leaf strip assays suggest resistant shoots may be chimeras and current efforts are directed towards regenerating solid mutants from resistant sectors . These will then be evaluated for any alteration in frost tolerance

Growth accounting in economic history:Findings, lessons and new directions

There is now a large volume of growth accounting estimates covering the long run experience of advanced countries. However, most of the studies in economic history are not based on state-of-the-art methods. There is a trade-off between maintaining international comparability and achieving the best results for individual countries. A one-size-fits-all approach will not always do justice to the variety of historical experiences since the conventional assumptions may sometimes be inappropriate. Nevertheless, growth-accounting studies have produced some eye-catching results which provide food for thought both for economic historians and for growth economists. These include (1) the finding that TFP growth was comparatively slow during the First Industrial Revolution, (2) Solow's famous conclusion that TFP growth accounted for 7/8ths of American labour-productivity growth was atypical, (3) the impact of new general-purpose technologies on growth typically takes a long time to materialize, ICT being the notable exception and (4) that capital-deepening was much more important relative to TFP growth in east Asian than in western European catch-up growth. Growth accounting is undoubtedly a valuable item in the cliometrician's toolkit. Nonetheless, we anticipate the introduction of more sophisticated methods and look forward to progress in understanding what explains marked differences in TFP performance

Selection of hydroxyproline-resistant proline-accumulating mutants of cauliflower. C.R. Deane, M .P. Fuller' & P.J. Dix

A procedure is described by which hydroxyproline-resistant lines could be selected from regenerating curd tissue of cauliflower. Mutagenesis was by N-nitroso-N-ethylurea, supplied as a drop of 0 .3 mM solution on each 3 mm diameter curd piece. The mutagen generated numerous morphological and pigment mutations without significantly affecting shoot regeneration from explants . Thirty one resistant shoots were recovered from more than six thousand explants mutagenised on regeneration medium supplemented with 3 mM hydroxyproline, while none was obtained from a similar number of non-mutagenised controls . Out of twenty-three resistant shoots which survived subculture, only one showed consistently elevated levels of endogenous proline . During early shoot culture passages, proline levels were 3 .6-4.7 times higher than controls, but this was reduced to 1 .6 times after 10-12 culture passages in the absence of hydroxyproline . Possible reasons for this decline are discussed . Leaf strip assays suggest resistant shoots may be chimeras and current efforts are directed towards regenerating solid mutants from resistant sectors . These will then be evaluated for any alteration in frost tolerance

Selection of hydroxyproline-resistant proline-accumulating mutants of cauliflower. C.R. Deane, M .P. Fuller' & P.J. Dix

A procedure is described by which hydroxyproline-resistant lines could be selected from regenerating curd tissue of cauliflower. Mutagenesis was by N-nitroso-N-ethylurea, supplied as a drop of 0 .3 mM solution on each 3 mm diameter curd piece. The mutagen generated numerous morphological and pigment mutations without significantly affecting shoot regeneration from explants . Thirty one resistant shoots were recovered from more than six thousand explants mutagenised on regeneration medium supplemented with 3 mM hydroxyproline, while none was obtained from a similar number of non-mutagenised controls . Out of twenty-three resistant shoots which survived subculture, only one showed consistently elevated levels of endogenous proline . During early shoot culture passages, proline levels were 3 .6-4.7 times higher than controls, but this was reduced to 1 .6 times after 10-12 culture passages in the absence of hydroxyproline . Possible reasons for this decline are discussed . Leaf strip assays suggest resistant shoots may be chimeras and current efforts are directed towards regenerating solid mutants from resistant sectors . These will then be evaluated for any alteration in frost tolerance

In vitro strategies for improvement of frost tolerance in cauliflower.

Two in vitro selection strategies were employed in an effort to obtain cauliflower lines with improved cold tolerance

In vitro strategies for improvement of frost tolerance in cauliflower.

Two in vitro selection strategies were employed in an effort to obtain cauliflower lines with improved cold tolerance