PubMed Health⌕ Search

Biomedical subjects

Ove Nilsson

Publications and source records attributed to Ove Nilsson.

10 recordsLinked to original sources
PubMed2006

GA4 is the active gibberellin in the regulation of LEAFY transcription and Arabidopsis floral initiation.

Flower initiation in Arabidopsis thaliana under noninductive short-day conditions is dependent on the biosynthesis of the plant hormone gibberellin (GA). This dependency can be explained, at least partly, by GA regulation of the flower meristem identity gene LEAFY (LFY) and the flowering time gene SUPPRESSOR OF CONSTANS1. Although it is well established that GA(4) is the active GA in the regulation of Arabidopsis shoot elongation, the identity of the GA responsible for the regulation of Arabidopsis flowering has not been established. Through a combination of GA quantifications and sensitivity assays, we show that GA(4) is the active GA in the regulation of LFY transcription and Arabidopsis flowering time under short-day conditions. The levels of GA(4) and sucrose increase dramatically in the shoot apex shortly before floral initiation, and the regulation of genes involved in GA metabolism suggests that this increase is possibly due to transport of GAs and sucrose from outside sources to the shoot apex. Our results demonstrate that in the dicot Arabidopsis, in contrast with the monocot Lolium temulentum, GA(4) is the active GA in the regulation of both shoot elongation and flower initiation.

Arabidopsis↗
PubMed2006

CO/FT regulatory module controls timing of flowering and seasonal growth cessation in trees.

Forest trees display a perennial growth behavior characterized by a multiple-year delay in flowering and, in temperate regions, an annual cycling between growth and dormancy. We show here that the CO/FT regulatory module, which controls flowering time in response to variations in daylength in annual plants, controls flowering in aspen trees. Unexpectedly, however, it also controls the short-day-induced growth cessation and bud set occurring in the fall. This regulatory mechanism can explain the ecogenetic variation in a highly adaptive trait: the critical daylength for growth cessation displayed by aspen trees sampled across a latitudinal gradient spanning northern Europe.

Adaptation, Physiological↗
PubMed2005

RETRACTED: The mRNA of the Arabidopsis gene FT moves from leaf to shoot apex and induces flowering.

Day length controls flowering time in many plants. The day-length signal is perceived in the leaf, but how this signal is transduced to the shoot apex, where floral initiation occurs, is not known. In Arabidopsis, the day-length response depends on the induction of the FLOWERING LOCUS T (FT) gene. We show here that local induction of FT in a single Arabidopsis leaf is sufficient to trigger flowering. The FT messenger RNA is transported to the shoot apex, where downstream genes are activated. These data suggest that the FT mRNA is an important component of the elusive "florigen" signal that moves from leaf to shoot apex.

Arabidopsis↗
PubMed2005

The BLADE ON PETIOLE genes act redundantly to control the growth and development of lateral organs.

Developmental processes in multicellular organisms involve an intricate balance between mechanisms that promote cell division activity and growth, and others that promote cell differentiation. Leaf development in Arabidopsis thaliana is controlled by genes like BLADE ON PETIOLE1 (BOP1), which prevent the development of ectopic meristematic activity that leads to the formation of new organs, and JAGGED (JAG), which control the proximodistal development of the leaf by regulating cell-division activity. We have isolated and characterized the BOP1 gene together with a functionally redundant close homolog that we name BOP2. The BOP genes are members of a gene family containing ankyrin repeats and a BTB/POZ domain, suggesting a role in protein-protein interaction. We show that the BOP genes are expressed in the proximal parts of plant lateral organs where they repress the transcription not only of class 1 knox genes but also of JAG. We also show that the BOP genes are acting together with the flower meristem identity gene LEAFY in the suppression of bract formation. These findings show that the BOP genes are important regulators of the growth and development of lateral organs.

Amino Acid Sequence↗
PubMed2004

A Populus EST resource for plant functional genomics.

Trees present a life form of paramount importance for terrestrial ecosystems and human societies because of their ecological structure and physiological function and provision of energy and industrial materials. The genus Populus is the internationally accepted model for molecular tree biology. We have analyzed 102,019 Populus ESTs that clustered into 11,885 clusters and 12,759 singletons. We also provide >4,000 assembled full clone sequences to serve as a basis for the upcoming annotation of the Populus genome sequence. A public web-based EST database (POPULUSDB) provides digital expression profiles for 18 tissues that comprise the majority of differentiated organs. The coding content of Populus and Arabidopsis genomes shows very high similarity, indicating that differences between these annual and perennial angiosperm life forms result primarily from differences in gene regulation. The high similarity between Populus and Arabidopsis will allow studies of Populus to directly benefit from the detailed functional genomic information generated for Arabidopsis, enabling detailed insights into tree development and adaptation. These data will also valuable for functional genomic efforts in Arabidopsis.

Ecosystem↗
PubMed2004

A transcriptional timetable of autumn senescence.

BACKGROUND: We have developed genomic tools to allow the genus Populus (aspens and cottonwoods) to be exploited as a full-featured model for investigating fundamental aspects of tree biology. We have undertaken large-scale expressed sequence tag (EST) sequencing programs and created Populus microarrays with significant gene coverage. One of the important aspects of plant biology that cannot be studied in annual plants is the gene activity involved in the induction of autumn leaf senescence. RESULTS: On the basis of 36,354 Populus ESTs, obtained from seven cDNA libraries, we have created a DNA microarray consisting of 13,490 clones, spotted in duplicate. Of these clones, 12,376 (92%) were confirmed by resequencing and all sequences were annotated and functionally classified. Here we have used the microarray to study transcript abundance in leaves of a free-growing aspen tree (Populus tremula) in northern Sweden during natural autumn senescence. Of the 13,490 spotted clones, 3,792 represented genes with significant expression in all leaf samples from the seven studied dates. CONCLUSIONS: We observed a major shift in gene expression, coinciding with massive chlorophyll degradation, that reflected a shift from photosynthetic competence to energy generation by mitochondrial respiration, oxidation of fatty acids and nutrient mobilization. Autumn senescence had much in common with senescence in annual plants; for example many proteases were induced. We also found evidence for increased transcriptional activity before the appearance of visible signs of senescence, presumably preparing the leaf for degradation of its components.

Aging↗
PubMed2003

Characteristics of human prostasomes isolated from three different sources.

BACKGROUND: Prostasomes are organelles secreted by human prostate epithelial cells and appear freely in semen. Most prostasomal functional and biochemical characteristics have been settled on basis of seminal prostasomes (SP). METHODS: Three types of prostasomes, viz., from seminal plasma, prostate gland (native), and prostate cancer bone metastasis, were isolated and compared for their biochemical and functional characteristics. RESULTS: Flow cytometry showed that all three types of prostasomes had a similar size distribution and electrophoresis revealed close similarities in banding pattern. Also, a high cholesterol/phospholipid ratio and some marker enzymes were distinctive common features. The unusual chromogranin B (CgB)/chromogranin A (CgA) ratio with CgB in abundance over CgA, previously found only in SP, was also valid for the native (NP) and metastasis-derived prostasomes (MP). The latter prostasome type contained a 10-fold higher amount of CgA compared to the others. SP and MP showed the same promotive effect on sperm forward motility, whereas NP did not. All three prostasome types exhibited an antibacterial activity against Bacillus megaterium. CONCLUSIONS: Since the three prostasome types were isolated from different environments, our data support the view that the common characteristics were prostasome-genuine.

Aminopeptidases↗
PubMed2003

Out of the woods: forest biotechnology enters the genomic era.

Trees represent a unique life form of upmost importance for mankind, as these organisms have developed a perennial lifestyle that produces the majority of terrestrial biomass. The difference between trees and annual plants is one of the main arguments behind the effort to sequence the entire genome of the poplar tree. This initiative is being backed up with a full-scale functional genomics effort on trees that will set a completely new agenda for forest research.

Agriculture↗
PubMedDate not supplied

Antiprostasome antibody titres in benign and malignant prostate disease.

BACKGROUND: Prostasomes are secretory granules synthesized, stored and secreted by normal and neoplastic human prostate epithelial cells and by prostate cancer metastasis. Prostasomes are postulated to be shed into the blood circulation in prostate cancer patients, where they may cause an immune response. MATERIALS AND METHODS: An antiprostasome antibody ELISA was developed and used to measure serum antibody titres in 81 males with prostate cancer or benign prostate hyperplasia. RESULTS: Patients with biopsy-verified prostate cancer had significantly higher antibody titres [p = 0.019 for the dominant tumour expression (first Gleason parameter) and p = 0.022 for the dominant and non-dominant form (first and second Gleason parameters)] than individuals with benign prostate hyperplasia or other benign prostate disorders. No correlation existed between antibody titres and PSA values. CONCLUSION: These results indicate that the antiprostasome antibody titre in serum may be a novel prostate cancer marker not replacing, but rather supplementing, PSA.

Aged↗