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Heredity Nov 1999In a comparative study four codominant microsatellite loci and seven allozyme gene loci have been used to investigate the genetic variation and differentiation of two...
In a comparative study four codominant microsatellite loci and seven allozyme gene loci have been used to investigate the genetic variation and differentiation of two pedunculate oak stands in North Germany. Both number and effective number of alleles were five to six times higher and the observed heterozygosity was three times higher for the microsatellite than for the allozyme loci. One stand showed an overall excess of homozygotes. In general the microsatellites were closer to Hardy-Weinberg expectation. The genetic distances between the two stands were distinctly higher for microsatellites. For most parameters microsatellites exhibited smaller interlocus variation than the allozymes. The different impact of population genetic processes on the genetic structure as assessed by microsatellites or allozymes is discussed.
PubMed: 10620033
DOI: 10.1038/sj.hdy.6886220 -
Royal Society Open Science Aug 2023A new arthropod, gen. et sp. nov., is described from the Silurian (Wenlock Series) Herefordshire Konservat-Lagerstätte, UK. The head bears pedunculate eyes and five...
A new arthropod, gen. et sp. nov., is described from the Silurian (Wenlock Series) Herefordshire Konservat-Lagerstätte, UK. The head bears pedunculate eyes and five pairs of appendages. Triflagellate antennae are followed by two pairs of uniramous limbs each with an endopod bearing a pronounced gnathobasic basipod. The posterior two pairs of head limbs and all trunk limbs bear an endopod, exopod and filamentous exite. The trunk consists of 10 appendage-bearing segments followed by an apodous abdomen of four segments. The arthropod resolves as sister taxon to and + Aglaspidida. It is the first representative of Vicissicaudata reported from the Herefordshire Lagerstätte and the first Silurian example with well-preserved appendages. The preservation of a cluster of radiolarians apparently captured by the trunk appendages is the first direct association of predator and prey discovered in the Herefordshire fauna, and suggests that was a nektobenthic form that used its gnathobasic basipods in microdurophagy.
PubMed: 37538743
DOI: 10.1098/rsos.230661 -
Tree Physiology Oct 2005Quercus petraea (Matt.) Liebl. and Q. robur L. hybridize frequently and occupy similar, though distinct, ecological niches. So far, genetic discrimination between these...
Quercus petraea (Matt.) Liebl. and Q. robur L. hybridize frequently and occupy similar, though distinct, ecological niches. So far, genetic discrimination between these species at the molecular level has been based mainly on neutral markers. Because such markers often exhibit low species differentiation because of high genetic compatibility and exchange between Q. robur and Q. petraea at these loci, we used adaptation-related expressed genes as markers. Accordingly, we identified osmotic-stress-induced genes in a Q. petraea cell line grown under moderate osmotic stress conditions. Two subtraction libraries were established from callus cells cultured under hyperosmotic stress for 1 or 48 h. Thirty-three differentially expressed sequence tags (ESTs) (from 70 originally isolated) were classified according to their putative functions. At least five of these gene products may contribute to osmotic-stress tolerance in oak: betaine aldehyde dehydrogenase, two trans-acting transcription factors (one abscsic acid (ABA)-responsive, the other ABA-independent), a glutathione-S- transferase and a heat-shock cognate protein. Seven genes were selected based on their putative function and their expression monitored in vivo. Leaf tissue from Q. petraea and Q. robur plantlets grown hydroponically under hyperosmotic conditions was harvested after 0, 1, 6, 24 or 72 h and analyzed by real-time polymerase chain reaction (PCR). We found indications of osmotic stress adaptation in Q. petraea based on up-regulation of genes related to protective functions, whereas down-regulation of these genes was evident in Q. robur. Thus, genetic markers related to adaptive traits may be useful for differentiating Q. petraea and Q. robur genotypes.
Topics: Adaptation, Physiological; Gene Expression Regulation, Plant; Genes, Plant; Osmotic Pressure; Quercus; RNA, Messenger; Trees
PubMed: 16076780
DOI: 10.1093/treephys/25.10.1317 -
International Journal of Biometeorology Mar 2005Our data, collected in the extreme east of Europe, show that a significant biological effect of climate change has been experienced even in territories where temperature...
Our data, collected in the extreme east of Europe, show that a significant biological effect of climate change has been experienced even in territories where temperature increase has been the lowest. This study documents the climatic response of pedunculate oak (Quercus robur) growing near its north-eastern limits in Europe. It demonstrates the potential of oak trees in old-growth forest to act as proxy climate indicators. Many factors may influence the temporal stability of the growth-climate, acorn crop-climate and first leafing-climate relationships. Climate data, climatic fluctuations, reproduction, genetics and tree-age may relate to this instability. Our results stress that an increase in climate variability or climatic warming resulting from warmer winters or summers could affect the oak population in eastern Europe in a similar way to that in western Europe. These findings, from remnants of oak forest in the middle Volga region of Russia, allow a further understanding of how species could be affected by future climates.
Topics: Acclimatization; Climate; Nuts; Plant Leaves; Quercus; Rain; Russia; Temperature
PubMed: 15538637
DOI: 10.1007/s00484-004-0233-3 -
Tree Physiology Nov 2004Somatic embryos of oak (Quercus robur L.) were matured on P24 media differing in gel strength (0.8, 0.9 and 1.0% (w/v) agar). Viscosity and osmotic potential...
Somatic embryos of oak (Quercus robur L.) were matured on P24 media differing in gel strength (0.8, 0.9 and 1.0% (w/v) agar). Viscosity and osmotic potential (Psipi,medium) of the media were determined. Developing cotyledonary embryos were analyzed at maturity Stages I-III for water content, osmotic potential (Psipi,embryo) and concentrations of abscisic acid (ABA) and proline. Proliferation of embryogenic tissue, germination rates and the number of embryos formed were also determined in order to relate embryo quality to physiological parameters. Viscosity increased with agar concentration, a phenomenon apparently related to water availability. Many Stage III embryos with high germination potentials were obtained on P24 medium containing 1.0% agar. Embryo water content decreased progressively from 94 to 80% during embryo maturation. Stage I and II embryos that matured on media containing 0.8 or 0.9% agar had similar values of Psipi,embryo, whereas Psipi,embryo of Stage III embryos that matured on medium containing 1.0% agar was significantly lower, although Psipi,medium was unaffected by gel strength. Stage III embryos showed a nearly 16-fold increase in proline concentration and a 50% decrease in ABA concentration compared with Stage I embryos. We conclude that tissue water status and a complex relationship between ABA and proline concentrations, modulated by medium gel strength, are important factors in the maturation process and the quality of oak somatic embryos.
Topics: Abscisic Acid; Germination; Proline; Quercus; Seeds; Trees; Water
PubMed: 15339734
DOI: 10.1093/treephys/24.11.1251 -
Integrative and Comparative Biology Nov 2021Many marine invertebrates have complex life histories that begin with a planktonic larval stage. Similar to other plankton, these larval invertebrates often possess...
Many marine invertebrates have complex life histories that begin with a planktonic larval stage. Similar to other plankton, these larval invertebrates often possess protruding body extensions, but their function beyond predator deterrence is not well-documented. For example, the planktonic nauplii of crustaceans have spines. Using the epibiotic pedunculate barnacle Octolasmis spp., we investigated how the dorsal thoracic spine affects swimming and fluid disturbance by comparing nauplii with their spines partially removed against those with intact spines. Our motion analysis showed that amputated Octolasmis spp. swam slower, in jerkier trajectories, and were less efficient per stroke cycle than those with intact spines. Amputees showed alterations in limb beat pattern: larger beat amplitude, increased phase lag, and reduced contralateral symmetry. These changes might partially help increase propulsive force generation and streamline the flow, but were insufficient to restore full function. Particle image velocimetry further showed that amputees had a larger relative area of influence, implying elevated risk by rheotactic predator. Body extensions and their interactions with limb motion play important biomechanical roles in shaping larval performance, which likely influences the evolution of form.
Topics: Animals; Biomechanical Phenomena; Larva; Rheology; Spine; Swimming; Thoracica
PubMed: 33905496
DOI: 10.1093/icb/icab036 -
Il Friuli Medico 1969
Topics: Adult; Female; Fibroma; Humans; Vulvar Neoplasms
PubMed: 5406417
DOI: No ID Found -
Zentralblatt Fur Allgemeine Pathologie... Apr 1951
Topics: Adenoma; Humans; Liver Neoplasms; Neoplasms
PubMed: 14837289
DOI: No ID Found -
Plant Physiology Nov 2022Drought and waterlogging impede tree growth and may even lead to tree death. Oaks, an emblematic group of tree species, have evolved a range of adaptations to cope with...
Drought and waterlogging impede tree growth and may even lead to tree death. Oaks, an emblematic group of tree species, have evolved a range of adaptations to cope with these constraints. The two most widely distributed European species, pedunculate (PO; Quercus robur L.) and sessile oak (SO; Quercus petraea Matt. Lieb), have overlapping ranges, but their respective distribution are highly constrained by local soil conditions. These contrasting ecological preferences between two closely related and frequently hybridizing species constitute a powerful model to explore the functional bases of the adaptive responses in oak. We exposed oak seedlings to waterlogging and drought, conditions typically encountered by the two species in their respective habitats, and studied changes in gene expression in roots using RNA-seq. We identified genes that change in expression between treatments differentially depending on species. These "species × environment"-responsive genes revealed adaptive molecular strategies involving adventitious and lateral root formation, aerenchyma formation in PO, and osmoregulation and ABA regulation in SO. With this experimental design, we also identified genes with different expression between species independently of water conditions imposed. Surprisingly, this category included genes with functions consistent with a role in intrinsic reproductive barriers. Finally, we compared our findings with those for a genome scan of species divergence and found that the expressional candidate genes included numerous highly differentiated genetic markers between the two species. By combining transcriptomic analysis, gene annotation, pathway analyses, as well as genome scan for genetic differentiation among species, we were able to highlight loci likely involved in adaptation of the two species to their respective ecological niches.
Topics: Quercus; Water; Soil; Trees; Gene Expression
PubMed: 36066428
DOI: 10.1093/plphys/kiac420 -
International Journal of Biometeorology Aug 2016Trees are sensitive to extreme weather and environmental conditions. This sensitivity is visible in tree-ring widths and cell structure. In our study, we hypothesized...
Trees are sensitive to extreme weather and environmental conditions. This sensitivity is visible in tree-ring widths and cell structure. In our study, we hypothesized that the sudden frost noted at the beginning of May in both 2007 and 2011 affected cambial activity and, consequently, the number and size of vessels in the tree rings. It was decided to test this hypothesis after damage to leaves was observed. The applied response function model did not show any significant relationships between spring temperature and growth. However, this method uses average values for long periods and sometimes misses the short-term effects. This is why we decided to study each ring separately, comparing them with rings unaffected by the late frost. Our study showed that the short-term effect of sudden frost in late spring did not affect tree rings and selected cell parameters. The most likely reasons for this are (i) cambial activity producing the earlywood vessels before the occurrence of the observed leaf damage, (ii) the forest micro-climate protecting the trees from the harsh frost and (iii) the temperature decline being too short-lived an event to affect the oaks. On the other hand, the visible damage may be occasional and not affect cambium activity and tree vitality at all. We conclude that oak is well-adapted to this phenomenon.
Topics: Cold Temperature; Poland; Quercus; Seasons; Trees
PubMed: 26607274
DOI: 10.1007/s00484-015-1107-6