The determination of dissolved organic nitrogen in sea water

The dissolved organic nitrogen occurring in the sea has so far received the least attention of all the nitrogen-containing fractions. As Krogh (1) has pointed out, it is present in relatively large amounts but is apparently unavailable for use by living organisms. The present investigation was carried out to test the practicability of a more extensive study of the distribution and significance of the dissolved organic N in the sea

Karyotype and C-bands in the annual inca lily Alstroemeria graminea

Alstroemeria graminea Phil. (Taltalia graminea according to BAYER 1998) is the only annual species described within the genus Alstroemeria L. and its cytogenetic relationship with the perennial species have not been described. In this work, an analysis of the karyotype and the C-banding pattern of Alstroemeria graminea are reported. A. graminea, with an asymmetric karyotype 2n = 2x = 16, shows similar chromosome morphology with respect to the perennial Alstroemeria species previously analysed. However, some differences in relative length and position of the C-bands were observed in A. graminea. These differences were the presence of a centromeric band and an interstitial band in the short arm of pair 1 and pericentromeric bands in the long arms of pairs 3 and 7, which have not been observed in the other species. The cytogenetic data of the present study on A. graminea are concurrent with other species within the genus Alstroemeria, and do not justify the separation of this species from the genus Alstroemeria and its inclusion in the new monotypic genus Taltalia

Cell proliferation in the Drosophila adult brain revealed by clonal analysis and bromodeoxyuridine labelling.

BACKGROUND: The production of new neurons during adulthood and their subsequent integration into a mature central nervous system have been shown to occur in all vertebrate species examined to date. However, the situation in insects is less clear and, in particular, it has been reported that there is no proliferation in the Drosophila adult brain. RESULTS: We report here, using clonal analysis and 5'-bromo-2'-deoxyuridine (BrdU) labelling, that cell proliferation does occur in the Drosophila adult brain. The majority of clones cluster on the ventrolateral side of the antennal lobes, as do the BrdU-positive cells. Of the BrdU-labelled cells, 86% express the glial gene reversed polarity (repo), and 14% are repo negative. CONCLUSION: We have observed cell proliferation in the Drosophila adult brain. The dividing cells may be adult stem cells, generating glial and/or non-glial cell types.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are