Kinetin-treated Flax Seedlings as Models for the Integration of the Plant Body
AMONG the many morphological experiments performed on various seedlings1 a recent experiment indicated in Fig. 1 seems to be particularly suitable to further the understanding of the growth correlations which are responsible for the integration of the plant body. Seedlings of Linum usitatissimum when decapitated above the first leaf pair always replace the lost top, when the cotyledonary buds grow out vigorously and prevent the development of the buds which are above them in the axils of the first two leaves, because the cotyledonary buds exhibit a much more advanced embryonic development because the cotyledons have a larger area than the first leaves. Kinetin immediately applied in 1 per cent lanolin to the bud of the first leaf caused it to expand, as in other cases2–4, but the cotyledonary shoots, even in this case, grew out more strongly and finally inhibited the shoot pretreated with kinetin (Fig. 1a).
The role of roots, cytokinins and apical dominance in the control of lateral shoot form in Solanum andigena
SummaryThe lateral bud of Solanum andigena has the potentiality to develop as a stolon or as a leafy, orthotropic shoot. Natural stolons are normally only produced from underground nodes, but aerial stolons can be induced to form by the application of a combination of indole-3-acetic acid and gibberellic acid (IAA/GA3) paste to the cut surface; under some conditions both natural or induced stolons are converted to upright, leafy shoots. The presence of roots was found to be necessary for the conversion of a natural stolon to a leafy shoot, but this root effect could be replaced by the synthetic cytokinin, 6-benzylaminopurine (BAP). By using α-14C-BAP it was demonstrated that cytokinin accumulates in the tip of an induced stolon, prior to its conversion to a leafy shoot caused by withdrawal of the IAA/GA3 paste. The application of IAA/GA3 to decapitated plants was shown to influence both the distribution and metabolism of the cytokinin. The possibility that the role of auxin in apical dominance, at least in part, is to control the distribution and metabolism of cytokinins is discussed.
Immunization with Brucella melitensis Rev 1 against Brucella ovis infection of rams.
The efficacy of Brucella Melitensis Rev 1 vaccine (Rev 1) for the prophylaxis of Brucella ovis ram epididymitis was evaluated. Twenty-nine 3-month-old rams were vaccinated with 2 X 10(9) Rev 1 and 14 were revaccinated with 5 X 10(8) at 14 months of age. Six rams remained unvaccinated as a control group. All rams were challenged with 5 X 10(8) B. ovis at 21 months of age. Before being slaughtered 8 weeks later, only one vaccinated ram developed epididymitis while four of the six control rams developed testicular alterations. Genital and selected extragenital organs and lymph nodes were removed at slaughter and inoculated on selective media. B. ovis was isolated from 26.6% of the vaccinated rams, 21.4% of the revaccinated rams and 100% of control rams. Portions of epididymis, testes and vesicular glands were also used for pathological studies. More severe lesions were observed in control rams than in vaccinated ones. In conclusion, these results show that vaccination of young lambs, followed or not by revaccination, is a suitable method for the prophylaxis of B. ovis infection of rams.