Notes on the sweet basil and its wild relatives (lamiaceae)

Artificial crossing experiments were made with three taxa of Ocimum. Plants ofO. forskolei Benth. andO. basilicum L. var. purpurascens Benth. were found to be interfertile, butO. americanum L. var.pilosum (Willd.) Paton was found to be reproductively isolated from the other two taxa. The new chromosome number 2n = 48 was counted inO. forskolei. These results suggest thatO. forskolei might be the closest relative of the Sweet Basil. The origin of the Sweet Basil is also discussed.     

Effects of food availability on fledging condition and post-fledging survival in king penguin chicks

Effects of summer food shortage on king penguin Aptenodytes patagonicus chicks were studied at South Georgia. Two cohorts were compared, fledging in the austral summers of 1992 (n = 32) and 1994 (n = 33) when availability of food was judged good and poor, respectively. The former cohort had a higher pre-fledging mean mass (12.78 kg vs ≤ 10.03 kg), fledged earlier (median 5 January vs 21 January), and a higher proportion was re-sighted within 2 years of fledging (28% vs 0%). Within 4 years, 47% of the former cohort had been re-sighted (i.e. post-fledge survival); in addition, one was observed at the Falkland Islands, and 22% had bred (i.e. recruitment) in their colony of origin. The re-sighted chicks of the 1992 cohort fledged earlier than those not re-sighted (median 24 December vs 10 January), but it remain unclear if they were heavier at fledging. All chicks in this study (n = 65) were marked with both transponders (subcutaneously implanted) and flipper bands (on one flipper), and no losses of any markings were found (controlled up to 4 years afterwards). Therefore, data on chick post-fledging survival and recruitment were not adjusted for losses of markings, as has been done in other studies. Received: 21 October 1996 / Accepted: 2 February 1997     

Influence of O2- and CO2-concentrations on oscillations in the transpiration rate from oat plants in darkness

The effect of changed O₂- and CO₂-concentrations in air on oscillations in the transpiration rate of young oat plants in darkness has been investigated. Lowering the O₂-concentration to 5% did not affect the oscillations. When the CO₂ in the air was removed, the transpiration rate increased, and the oscillations ceased. When the CO₂-concentration was raised to 0.3 or 3% the transpiration rate temporarily decreased, but the period of the oscillations was not changed. Further increase of the CO₂-concentration caused, after a temporary decrease, an increased transpiration rate, and the oscillations eventually ceased. The period of the oscillations was influenced by the temperature: a lower temperature gave a longer period. It is concluded that substomatal O₂-deficit or high CO₂-concentration do not play a crucial role in the origin of these oscillations.     

Pericarp structure of the Caryopteris group (Lamiaceae subfam. Ajugoideae)

Pericarp and seed structure was investigated in 13 out of the 16 species of the old Caryopteris s.l. and in a few species of the related Rubiteucris , Amethystea , Trichostema and Ajuga . The pericarp structure was found to be very variable, and the variation largely matches the most recent classification where Caryopteris s.l. is divided into six genera: Caryopteris s.s., Discretitheca , Pseudocaryopteris , Rubiteucris , Schnabelia and Tripora . All the six genera but Rubiteucris and Schnabelia can be distinguished from each other by differences in pericarp structure, and Caryopteris s.s. was found to have a particularly divergent structure. Similarities in pericarp structure also suggest that Schnabelia , Rubiteucris and Tripora may be closely related.     

Bacterial and firefly luciferase genes in transgenic plants: Advantages and disadvantages of a reporter gene

Genes encoding light-emitting luciferase were recently isolated from luminous marine bacteria and fireflies. Expression of luciferase genes in diverse organisms is a unique way for studying gene expression by simple and sensitive measurement of light. Recent advances in application of luciferase reporter genes are reviewed and documented by examples of in vivo visualization of their expression in transgenic plants.     

Oxidative stress decreases antioxidant enzyme activities in reaggregation cultures of rat brain cells

The brain has been suggested to be especially sensitive to damage by reactive oxygen species. In this study, we examined the effects of hyperoxic conditions on the activities and mRNA levels of antioxidant enzymes in reaggregation cultures of rat forebrain cells. Cultures were exposed to 80% oxygen for 12–60 h starting on Days 17 and 33 in culture. Superoxide dismutase activities and mRNA levels were not affected by hyperoxia, whereas catalase activity was slightly decreased after 24 h in 80% oxygen at Day 17. Glutathione peroxidase activity was markedly decreased already after 12 h of hyperoxia, and decreased activities of glutathione reductase and glucose-6-phosphate dehydrogenase were also noted. The glutathione peroxidase mRNA levels were increased in hyperoxic cultures at Day 17 but not at Day 33. These results suggest that the enzymatic defense mechanisms against reactive oxygen species in the brain are rather weak and deteriorate during oxidative stress but that a potential for compensatory upregulation exists at least during the first postnatal weeks.     

Recording,processing and analysis of grass root images from a rhizotron

To develop and test a system for computer-assisted image analysis, repeated video recordings of reed canary-grass roots (Phalaris arundinacea L.) were made in an 18-window rhizotron. The images were digitized and processed using a Unix computer and the Khoros software development environment.Two image sizes, 126×95 mm and 61×46 mm, both comprising 650 × 490 pixels, were compared. Among image processing techniques used were median filtering, segmentation and skeletonization. Root area and length in both the topsoil and subsoil were estimated using the two image sizes. The resolution (image size) strongly affected the calculated root lengths. The results were compared with root length measurements obtained manually.Statistically significant differences in root length and area in the topsoil were detected between the sampling dates using the computer-assisted methods. Possible sources of error and methods for reducing them are discussed.