18,208 research outputs found
The Douglas-Fir Genome Sequence Reveals Specialization of the Photosynthetic Apparatus in Pinaceae.
A reference genome sequence for Pseudotsuga menziesii var. menziesii (Mirb.) Franco (Coastal Douglas-fir) is reported, thus providing a reference sequence for a third genus of the family Pinaceae. The contiguity and quality of the genome assembly far exceeds that of other conifer reference genome sequences (contig N50 = 44,136 bp and scaffold N50 = 340,704 bp). Incremental improvements in sequencing and assembly technologies are in part responsible for the higher quality reference genome, but it may also be due to a slightly lower exact repeat content in Douglas-fir vs. pine and spruce. Comparative genome annotation with angiosperm species reveals gene-family expansion and contraction in Douglas-fir and other conifers which may account for some of the major morphological and physiological differences between the two major plant groups. Notable differences in the size of the NDH-complex gene family and genes underlying the functional basis of shade tolerance/intolerance were observed. This reference genome sequence not only provides an important resource for Douglas-fir breeders and geneticists but also sheds additional light on the evolutionary processes that have led to the divergence of modern angiosperms from the more ancient gymnosperms
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Roman diet and trade: evidence from organic residues on pottery sherds recovered at the Roman town of Calleva Atrebatum (Silchester Hants.)
The analysis of organic residues from pottery sherds using Gas-Chromatography with mass-spectroscopy (GC-MS) has revealed information about the variety of foods eaten and domestic routine at Silchester between the second and fourth–sixth centuries A.D. Two results are discussed in detail: those of a second-century Gauloise-type amphora and a fourth-century SE Dorset black-burnished ware (BB1) cooking pot, which reveal the use of pine pitch on the inner surface of the amphora and the use of animal fats (ruminant adipose fats) and leafy vegetables in cooking at the Roman town of Silchester, Hants
Palaeoclimate changes in the Afyon province, Sw-Turkey, during the Middle-Late Pleistocene: Signals from calcareous tufa pollen and stable isotope records
The calcareous tufas of Sarikavak located in the northern part of NE-SW trending Acigöl Graben in SW-Turkey are investigated in detail. For this aim, various analyses (stable isotopes, U/Th dating, palynology) have been carried out on samples obtained from both outcrops and drilling logs in and surrounding Sarikavak Village. U/Th dating shows that these carbonates precipitated from 400 ka up to 80 ka. Preliminary pollen data, document climatic variability between MIS 11 and MIS 8 in the studied area. © 2010 AIQUA - Associazione Italiana per lo Studio del Quaternario e EMMEVI - Servizio Congressi SPA
Vegetation cycles in a disturbed sequence around the Cobb-Mountain subchron in Catalonia
A 52 m-long lacustrine sequence has been recovered from the basin of Bòbila-Ordis, near Banyoles (N-E Spain). The presence of Early Biharian rodent teeth (Early Pleistocene) and of a c. 9 ka-long palaeomagnetic reversal (Cobb-Mountain subchron) suggests an age centred on 1.2 Ma, making this sequence one of the very few well-dated terrestrial sequences of that age in Europe. The first 22.5 m (with an interglacial character) are very homogenous owing to sedimentation affected by underwater springs. In the middle part of the sequence, palynological analyses, supported by sediment visual description, ostracod and mollusc assemblages, allow the reconstruction of one glacial-interglacial cycle, with vegetation succession. A second incomplete climatic cycle is recorded in the top part, within a shallower lake. These brief interruptions in the two climatic cycles are possibly linked to lake bank collapse caused by Hippopotamus amphibius or faulting linked to karst. The succession is likely to correlate to MIS 36-33. The Bòbila-Ordis lacustrine series (including two other nested lakes) covers altogether some sections of four glacial and four interglacial periods, not all contiguous
On the vulval morphology of some species of Bursaphelenchus (Nematoda: Parasitaphelenchinae)
The vulval pattern of six species of the genus Bursaphelenchus (B. abruptus, B. conicaudatus, B. fraudulentus,
B. luxuriosae, B. mucronatus and B. xylophilus) was studied using scanning electron microscopy. A terminology for the vulval region
structures observed is proposed herein and illustrated by micrographs and line drawings. It was shown that, of the studied species, only
B. mucronatus and B. xylophilus share an identical morphology of the vulval region, all other species differing significantly from each
other and from both B. mucronatus and B. xylophilus. This study indicates the diagnostic potential for variation in vulval morphology
within Bursaphelenchus and it is recommended that such features are recorded in all future descriptions
Phylogeny and taxonomy of the Ophiostoma piceae complex and the Dutch elm disease fungi
The Ophiostoma piceae complex forms a monophyletic group of insect-dispersed pyrenomycetes with synnemata (Pesotum) and micronematous (Sporothrix) synanamorphs. Other species of Ophios-toma outside of the O. piceae complex that form syn-nemata lack the Sporothrix state. The nine recognized species within the 0. piceae complex are delimited by synnema morphology, growth rate at 32 C, mating reactions and sequences of the internal transcribed spacer (ITS) region of the rDNA operon. Phyloge-netic analysis of the ITS region suggests two major clades in the complex, one that causes bluestain in primarily coniferous hosts and the other on primarily hardwood hosts. In the coniferous group are O. pi-ceae, O. canum, O. floccosum and the recently de-scribed O. setosum (anamorph Pesotum cupulatum sp. nov.). In the hardwood group are O. querci, O. caton-ianum, and the Dutch elm disease fungi: O. ulmi, O. novo-ulmi and O. himal-ulmi. Restriction fragment length polymorphisms of the ITS region are shown to be a convenient diagnostic tool for delimiting these species
Growth response of lutz spruce saplings to the removal of a herbaceous competitor and the application of fertilizer in Southeast Alaska
Thesis (M.S.) University of Alaska Fairbanks, 2014.Herbaceous competitor species such as fireweed can impact future survival and growth of Lutz (Picea x lutzii Little, Pinaceae) spruce saplings. Fertilizer is applied to crop trees in order to supply more nutrients to promote growth. However, fertilizer benefits competitor species as well. Literature regarding the impacts of competition for resources between fireweed and spruce saplings are lacking, but the impacts of resource competition on seedling growth and fireweed are documented as significant. Seedlings are distinguished from saplings by differences in height and/or diameter. In order to test the influence of both competitor species and added fertilizer, we analyzed growth response of Lutz spruce saplings to fireweed removal and applied fertilizer through treatments and controls using a two by two factorial experiment. Results revealed that fireweed removal had a positive effect on sapling growth response, while added fertilizer alone showed no effect on sapling growth response. I found a strong, positive correlation between soil moisture and fireweed cover. I also found a strong, positive relationship between sapling growth and soil moisture as well as sapling growth and fireweed cover. This study demonstrates that spruce saplings positively responded to fireweed removal compared to the application of fertilizer. More importantly, the overall conclusion is that when saplings are not N limited soil, moisture is the driving factor in sapling height growth. The long-term effects of harvesting an efficient nitrogen competitor species are not well known and could be detrimental to future site fertility
Taxonomic differences between Pinus sylvestris and P. uncinata revealed in the stomata and cuticle characters for use in the study of fossil material
Taxonomic differences in the needle epidermis characteristics of Pinus sylvestris L. and Pinus uncinata Ramond ex DC. from two Iberian populations were sought; such information could help identify these species when pollen analysis and the inspection of wood anatomy fails. The features of the cuticle are commonly well preserved in the fossil record. Although the epidermal patterns of the examined taxa were similar, qualitative differences were seen in the subsidiary and guard cells. P. sylvestris showed small subsidiary cells homogenously arranged around the opening of the epistomatal chamber, while P. uncinata showed small, lateral subsidiary cells and non-differentiated subsidiary cells in the polar position. The aperture of the epistomatic chamber of P. uncinata was also larger in diameter (15.1 ± 1.8 µm P. sylvestris; 21.1 ± 2.8 µm P. uncinata). Principal components analysis and discriminant analysis was performed on the features of the guard cells characterising the size and shape of the cuticular thickenings — all the variables analysed can be measured in disperse stomata in microscope preparations for pollen analysis. Significant differences were found in the upper woody lamellae width and the coefficient associated with the shape of the medial lamellae borders (discriminant analysis weighting 0.739 and 0.826 respectively). Other significant parameters included the coefficient associated with the relative size of the medial lamellae border width of the guard cells with respect to the distance between the external limits of the medial lamellae borders, and the length of the upper woody lamella. Different light regimens appeared not to significantly affect the variability of the studied features
Are plants with anti-cancer activity resistant to crown gall? : A test of hypothesis
The Crown gall tumour assay (CGTA) is one of several bench top bioassays recommended for the rapid screening of plants with anti-cancer activity. The rationale for the use of the bioassay is that the tumorogenic mechanism initiated in plant tissues by _Agrobacterium tumefaciens_ is in many ways similar to that of animals. Several plant species with anti-cancer activity have already been discovered using this bioassay. However till date no explicit test of an association between anti-cancer activity of plants and their resistance to crown gall formation has been demonstrated. Demonstration of an association could have exploratory potential when searching for plants with anti-cancer activity. In this paper, we determined whether or not a statistically significant association between crown gall resistance and anti-cancer activity exists in plants found in existing published data sets. Our results indicate that plants with anti-cancer activity have a higher proportion of their species resistant to crown gall formation compared to a random selection of plants. We discuss the implications of our results especially when prospecting for newer sources of anti-cancer activity in plants
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