Search results for "dormancy"
showing 10 items of 39 documents
Genome-based in silico identification of new Mycobacterium tuberculosis antigens activating polyfunctional CD8+ T cells in human tuberculosis.
2011
Although CD8(+) T cells help control Mycobacterium tuberculosis infection, their M. tuberculosis Ag repertoire, in vivo frequency, and functionality in human tuberculosis (TB) remains largely undefined. We have performed genome-based bioinformatics searches to identify new M. tuberculosis epitopes presented by major HLA class I supertypes A2, A3, and B7 (covering 80% of the human population). A total of 432 M. tuberculosis peptides predicted to bind to HLA-A*0201, HLA-A*0301, and HLA-B*0702 (representing the above supertypes) were synthesized and HLA-binding affinities determined. Peptide-specific CD8(+) T cell proliferation assays (CFSE dilution) in 41 M. tuberculosis-responsive donors ide…
Morphology, anatomy and germination response of heteromorphic achenes of Anthemis chrysantha J. Gay (Asteraceae), a critically endangered species
2011
[EN] This study demonstrates that Anthemis chrysantha, a 'Critically Endangered' annual plant, produces two morphs of achenes: white and dark achenes, which differ in size, mass, anatomy and germination behaviour. Fresh white achenes germinated at all temperatures assayed from 10 to 25 degrees C in both continuous darkness and 12-h photoperiod, ranging between 24% at 25 degrees C in darkness and 89% at 12/20 degrees C in light, whereas fresh dark achenes did not germinate under any temperature or light conditions. To identify differences in dormancy type between the two morphs, germination of dry-stored achenes, and achenes stratified at 5 or 25 degrees C for 2 months were tested in both da…
Tumor-Specific Blood Serum Factors as Basis of Tumor Dormancy
2014
In the present review, we focus on the importance of blood serum factors for tumor growth in vivo. Data from mice experiments indicate the existence of serum factors, which decrease the dormancy of Ehrlich carcinoma cells from 85 to 20%. The impaired production of these factors increases the life span of tumor-bearing animals from 14 days to 120 days. Blocking the production of tumor-specific factors causes the complete regression of already developed Ehrlich carcinoma. These serum factors do not affect the malignant carcinoma cells in vitro. We identified serpins as tumor dormancy serum factors. Experimental evidence suggests that serpins are not only essential for tumor growth. Serpins ar…
Hematopoietic Stem Cells Reversibly Switch from Dormancy to Self-Renewal during Homeostasis and Repair
2008
Bone marrow hematopoietic stem cells (HSCs) are crucial to maintain lifelong production of all blood cells. Although HSCs divide infrequently, it is thought that the entire HSC pool turns over every few weeks, suggesting that HSCs regularly enter and exit cell cycle. Here, we combine flow cytometry with label-retaining assays (BrdU and histone H2B-GFP) to identify a population of dormant mouse HSCs (d-HSCs) within the lin(-)Sca1(+)cKit(+)CD150(+)CD48(-)CD34(-) population. Computational modeling suggests that d-HSCs divide about every 145 days, or five times per lifetime. d-HSCs harbor the vast majority of multilineage long-term self-renewal activity. While they form a silent reservoir of th…
Starvation tolerance of rotifers produced from parthenogenetic eggs and from diapausing eggs: a life table approach
2006
Monogonont rotifers have to cope with environmental variation by producing diapausing stages.Cyclically, parthenogenetic rotifers produce females by (i) parthenogenetic eggs and (ii) sexuallyproduced eggs. Parthenogenetic eggs hatch shortly after ovoposition, frequently while they are carriedby their mothers. Sexual eggs go into dormancy and hatch in the sediment, in response to specificenvironmental cues. Therefore, it is expected that post-diapause and parthenogenetic offspring wouldface different environments. Moreover, resource allocation is higher in diapausing eggs than inparthenogenetic eggs. In this study, the response to starvation of females obtained from partheno-genetic eggs and …
Climatic Characterization and Phenology of Local Peach Genotypes in the Udzungwa Uplands of Tanzania
2014
The phenology of two local peach genotypes was studied to verify whether peaches can be produced in the Tanzanian uplands. Observations were conducted on trees of one early- and one late-ripening peach genotype in 2010 and 2011. Temperature trends were reconstructed and three chilling estimation models were tested. The two peach genotypes differed for timing of flower and leaf bud-break. Common symptoms of insufficient chilling (presence of numerous stages at a specific date and about 20% of undeveloped flower buds) were observed in the late genotype. Both Utah and Dynamic models indicated low chilling accumulation, lower than the Mean Temperature model in most cases. This is inconsistent w…
Genecological and isozyme studies in Senecio vernalis Waldst. & Kit. and S. vulgaris L. var. vulgaris (Asteraceae) from Central Europe and Israel
1995
Summary Genecological evidence and evidence obtained from an isozyme survey suggest a considerable amount of intraspecific differentiation in Senecio vernalis . Plants of this species from Israel were found to differ strikingly from those of C European (German) origin in most of the traits investigated, e.g., in the possession of pronounced seed dormancy, which seems to be governed by a single gene, a shorter life cycle, lack of rosette growth correlated with stem elongation prior to budding, a larger number of smaller capitula with fewer (disc) florets, and an ephemeral habit with plants only flowering soon after the first winter rains. Both accessions achieved a similar reproductive poten…
The Genetics of Evolutionary Change in Senecio vulgaris L.: A QTL Mapping Approach
2001
: The cosmopolitan weed Senecio vulgaris var. vulgaris is likely to have originated from the non-weedy S. vulgaris ssp. denticulatus from which it differs by showing no seed dormancy, by completing its life cycle from germination to seed formation much faster and by lacking ray florets. An F2 generation of 120 individuals obtained through selfing of one hybrid individual between var. vulgaris and ssp. denticulatus was used to construct a linkage map based on RAPD polymorphisms and the presence or absence of ray florets. This linkage map was used for a QTL analysis of 12 characters distinguishing the two taxa. For seven of these 12 characters, three significant QTLs could be found. One of th…
Seed cryopreservation of Fraxinus angustifolia Vahl
2016
Fraxinus angustifolia is used for afforestation and for production of both valuable timber and manna , a substance with pharmacological applications. The aim of this research was to establish the optimized condition for cryopreservation of F. angustifolia seeds, in order to protect the germplasm of this species. Germination percentage and mean time of germination of non-treated seeds (control) and liquid nitrogen-treated seeds were established in water or in 10 -6 M gibberellic acid (GA 3 ). The seeds could be cryopreserved with 3% of moisture content (MC) and germinated easily in water (70.0 ± 5.0%), while seeds cryopreserved with 6% MC showed a physiological dormancy. This state could be …
Soil seed bank and among-years genetic diversity in arid populations of Eruca sativa Miller (Brassicaceae)
2013
Abstract Populations of Eruca sativa from arid environments exhibit greater physiological dormancy than those that originated in more favorable ones. We tested the possible relative contribution of the soil seed bank (SSB) to the aboveground cohorts in desert and semiarid populations. Seedlings that emerged from the SSB under controlled irrigation were distinguished from those that emerged after exposure of the remaining ungerminated SSB to gibberellic acid as constituting non-dormant and dormant SSBs, respectively. On average, the total SSB was significantly larger in the semiarid than in the desert population. In both sites, the aboveground and SSB cohorts exhibited closely similar geneti…