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Conflicting results in the literature regarding the possible regulatory role of the embryonic axis on reserve mobilization in lipid-rich seeds prompted this study on cucumber ( Cucumis sativus ) seed. Two existing models supporting control by the axis, namely the hormonal control- and source-sink relationship models, were tested by incubating detached cotyledons in plant hormone solutions and axes extracts as well as in the presence of artificial sinks. This approach was an attempt to alleviate any effect that axis removal might have on reserve mobilization in cotyledons measured in terms of changes in fresh and dry weight, respiratory capacity and isocitrate lyase activity. No clear evidence that lipid mobilization in cucumber seeds was controlled by the axis through either a hormonal- or a source-sink mechanism was obtained. However, axis removal prevented the natural shedding of the testa by germinating cucumber seeds resulting in clear differences between intact and detached cotyledons in terms of fresh and dry weight, respiratory and lipid metabolism. Moreover, weakening of the testa on detached cotyledons, by cutting longitudinally, only partially alleviated the inhibitory effect that axis removal had on these metabolic events while total removal alleviated this effect completely. The latter was more pronounced in an elevated oxygen atmosphere indicating that the testa played a more pronounced role in controlling the metabolism of cucumber cotyledons during the post-germinative seedling establishment phase than did the growing axis.

Leaf samples of Euclea crispa subsp. crispa were collected in the Bloemfontein area of the Free State Province as part of a project to screen South African plants for their antimicrobial potential. Crude extracts were obtained with a 95% methanol solution and the aqueous fraction remaining after methanol was removed by distillation, was bioassayed in vitro for its potential to inhibit the growth of eleven human pathogenic bacteria and two human pathogenic fungi. Of all the plant extracts tested, the E. crispa crude leaf extract showed the most promising antimicrobial activity against human pathogenic bacteria and fungi. Subsequently, the crude extract was fractionated by means of liquid-liquid extraction using four different organic solvents in order of increasing polarity. Most of the antibacterial activity was observed in the more polar ethyl acetate fraction. No particular trend of inhibition was observed between the Gram-negative and Grampositive bacteria. Neither the crude extract nor the semipurified fractions inhibited the growth of Haemophilus influenzae, Klebsiella pneumoniae and Streptococcus pneumoniae. The growth of the other eight human pathogenic bacteria was inhibited to different degrees. Both the crude extract as well as all the semi-purified fractions inhibited the growth of two human pathogenic test fungi.