Three-year vegetation change in the Arctic environment as observed in a permanent plot in Ny-Alesund, Svalbard

A permanent plot was established in 1997 to monitor vegetation development in a recently abandoned coal mine in Ny-_lesund, Svalbard. A 1 mx1 m quadrat was set up and further divided into one hundred small 10 cmx10 cm cells. All the vascular plants occurring in the plot were recorded for each of the 100 cells. In 1999, the plot was revisited and examined for occurrences of vascular plants. Further, in 2002, the plot was re-surveyed and all the vascular plants were measured for their coverage. Data were compared and coverage change over the past three years was detected. Vascular plants significantly increased, indicating that the vegetation succession is currently in progress

Vegetation of Alnus sinuata thicket of the Chugach Mountains, southeastern Alaska-Its classification and ecogeographical interpretations

Vegetation of Sitka alder(Alnus sinuata) thickets occurring in the subalpine environment in the Thompson Pass area, the Chugach Mountains, Alaska, was studied. On the southern slopes of the Chugach Mountains facing the Pacific Ocean, the subalpine zone develops in an altitudinal range approximately from 100m up to 800m above sea level. There a complex of shrub thickets of Alnus sinuata and open dwarf shrub meadows best represented the vegetation. A total of 52 releves were established to describe the vegetation structure; 32 releves representing the Alnus sinuata thicket and 20 releves the open dwarf shrub meadow. For each releve, all the vascular plants were listed and their coverage was assessed. Vegetation synthesis tables were constructed. Vegetation was classified according to phytosociological methods. Two plant associations, Calamagrostido canadensis-Alnetum sinuatae and Empetro nigri-Vaccinietum caespitosi, were identified; the former association represented the Alnus sinuata thickets and the latter open dwarf shrub meadow communities. The ecogeographical status of the Alnus sinuata thicket is discussed in relation to other subalpine biomes of the northern Amphi-Pacific region. It is concluded that the Alnus sinuata thicket represents a mild winter but snowy oceanic subalpine environment of the southern slopes of the Chugach Mountains, Alaska

Phytosociological classification and ecological characterization of high arctic vegetation of Canada with some remarks in relation to vegetation of Svalbard

n attempt was made to classify vegetation of the High Arctic of Canada at the higher level of syntaxonomy. Provisionally, one class, two orders and four alliances in addition to unclassified "polar desert complex" were distinguished. They were: the Salicetea arcticae, incorporating the Saxifragetalia oppositifoliae and the Caricetalia stantis. The Saxifragetalia oppositifoliae comprised of three alliances, i.e., Papaverion lapponici, Dryado-Salicion arcticae, and Cassiopion tetragonae, in addition to the "polar desert complex". Under the Caricetalia stantis, one alliance Caricion stantis was recognized. Vegetation of the Canadian High Arctic was compared with that of Svalbard. The most striking difference between the two regions was a presence/absence of Cassiope tetragona in the zonal phytogeocoenoses. The Cassiope-dominating communities are fairly common in Svalbard whereas they are generally limited in the Canadian High Arctic. Such difference was explained primarily by climatic characteristics and concomitant soil properties in such a manner that a highly continental climate of the Canadian High Arctic decelerates the soil leaching and eluviation to maintain generally high base status of soils. On the other hand, a strongly oceanic climate of Svalbard promotes soil leaching to result in a soil acidifi-cation. Cassiope tetragona is known to be acidophilous and thrives better in acidic soils. In the Canadian High Arctic, development of the Cassiope-dominating communities is rather restricted to the areas where soils are generally acidic. Such a climate-soil-vegetation interaction regulates development of zonal phytogeocoenoses to determine biogeoclimatic characteristics of the respective regions

A two-year change of arctic vegetation as observed in a permanent plot established in Ny-Alesund, Svalbard

In 1997,a permanent plot was established in an abandoned coal mine site on the outskirts of Ny-Alesund, Svalbard, to describe the present vegetation structure and to monitor future vegetation change. A 1m×1m quadrat was set up and was further divided into 100 small cells (subquadrats). All the vascular species were listed and their presence was recorded for each of the subquadrats. In 1999,the plot was revisited and all the subquadrats were rechecked for any change of species occurrence. The field data of 1997 and 1999 were compared and change of species occurrences was scrupulously examined for each subquadrat. In general, a considerable increase of occurrences of plants as expressed in the number of subquadrats took place during the two years. This suggested that even during the observation period the vegetation kept changing rapidly along with the progress of vegetation succession

Ecological characterization of some selected vascular species in the Arctic environment of Ny-Alesund, Svalbard, in relation to soil moisture conditions

An attempt has been made to characterize and categorize some selected vascular species in the Ny-Alesund area, Svalbard, in relation to soil moisture conditions. A total of sixty releves were established to describe the floristic structures of plant communities. At each releve site, one soil core sample in a 100ml metal container was collected to determine soil physical properties. Samples were oven-dried for 48 hours at 105℃. Moisture content was measured and soil moisture index was calculated for each releve. Based on the index, sixty releves were divided into five soil moisture classes. Throughout the sixty releves, twenty-five species of vascular plants were recognized. Of them, eleven species were selected for this study. They were Salix polaris, Oxyria digyna, Polygonum viviparum, Cerastium arcticum, C. regelii, Saxifraga caespitosa, S. cernua, S. nivalis, S. oppositifolia, Dryas octopetala, and Cassiope tetragona. These were the species that occurred in more than eleven releves out of the sixty. Their frequencies against the soil moisture classes were counted. Ecological distribution curves were constructed for the species. From the distribution pattern, especially the amplitude and the mode position on the moisture classes, the species were classified into six categories as follows, i. e., euryhygrotopic xerophyte, euryhygrotopic mesophyte, euryhygrotopic hygrophyte, stenohygrotopic xerophyte, stenohygrotopic mesophyte, and stenohygrotopic hygrophyte

Gender variation of Dryas octopetala along snowmelt and latitudinal gradients in the Subarctic and the High Arctic

We describe variations of floral traits of Dryas octopetala L. along a snowmelt gradient within and among three sites : 1) the Subarctic Latnjajaure in northernmost Sweden, 2) the High Arctic Longyearbyen and 3) Ny-Alesund, Svalbard in Norway, also High Arctic. Dryas octopetala had two types of flowers, hermaphrodite flowers and male flowers, lacking any gynoecium. The frequency of male flowers was higher in late snow-melt habitats (i. e. late flowering populations) both at Latnjajaure and Ny-Alesund. Male flowers were significantly lighter in dry weight than hermaphrodite flowers; the difference was larger in the High Arctic than in the Subarctic, suggesting a higher resource limitation in male flowers in the High Arctic. Flower weight also varied among the three sites, and showed a significant difference along the latitudinal gradient both in hermaphrodite and male flowers. In the hermaphrodite flowers, the gynoecium dry weight differed among the three sites, being significantly heavier at Latnjajaure than at Longyearbyen and Ny-Alesund. As a result, the "femaleness" (gynoecium weight/androecium+gynoecium weight) showed significantly higher values at Latnjajaure than at Longyearbyen and Ny-Alesund. Thus, the floral allocation to female function in D. octopetala decreases with an increase in latitude from the Subarctic to the High Arctic. Gender variation of flowers is a size-dependent phenomenon; a positive correlation between flower size and femaleness was observed within each site

An efficient biological pathway layout algorithm combining grid-layout and spring embedder for complicated cellular location information

<p>Abstract</p> <p>Background</p> <p>Graph drawing is one of the important techniques for understanding biological regulations in a cell or among cells at the pathway level. Among many available layout algorithms, the spring embedder algorithm is widely used not only for pathway drawing but also for circuit placement and www visualization and so on because of the harmonized appearance of its results. For pathway drawing, location information is essential for its comprehension. However, complex shapes need to be taken into account when torus-shaped location information such as nuclear inner membrane, nuclear outer membrane, and plasma membrane is considered. Unfortunately, the spring embedder algorithm cannot easily handle such information. In addition, crossings between edges and nodes are usually not considered explicitly.</p> <p>Results</p> <p>We proposed a new grid-layout algorithm based on the spring embedder algorithm that can handle location information and provide layouts with harmonized appearance. In grid-layout algorithms, the mapping of nodes to grid points that minimizes a cost function is searched. By imposing positional constraints on grid points, location information including complex shapes can be easily considered. Our layout algorithm includes the spring embedder cost as a component of the cost function. We further extend the layout algorithm to enable dynamic update of the positions and sizes of compartments at each step.</p> <p>Conclusions</p> <p>The new spring embedder-based grid-layout algorithm and a spring embedder algorithm are applied to three biological pathways; endothelial cell model, Fas-induced apoptosis model, and <it>C. elegans </it>cell fate simulation model. From the positional constraints, all the results of our algorithm satisfy location information, and hence, more comprehensible layouts are obtained as compared to the spring embedder algorithm. From the comparison of the number of crossings, the results of the grid-layout-based algorithm tend to contain more crossings than those of the spring embedder algorithm due to the positional constraints. For a fair comparison, we also apply our proposed method without positional constraints. This comparison shows that these results contain less crossings than those of the spring embedder algorithm. We also compared layouts of the proposed algorithm with and without compartment update and verified that latter can reach better local optima.</p

Relationship between quantity of IFNT estimated by IFN-stimulated gene expression in peripheral blood mononuclear cells and bovine embryonic mortality after AI or ET

<p>Abstract</p> <p>Background</p> <p>Interferon tau (IFNT), which is secreted into the uterine cavity during the maternal recognition period (MRP), is a key factor for establishment of pregnancy. The present study aims to clarify the relationship between the ability of a bovine conceptus to produce IFNT during the MRP and the conceptus's ability to establish pregnancy.</p> <p>Methods</p> <p>In the first experiment, IFNT (0, 500, or 1000 micrograms) was administered into the uterine horn ipsilateral to the CL 16 or 17 d after standing estrus, and mRNA levels of IFN-stimulated gene 15-kDa protein (<it>ISG15</it>) and <it>Mx2 </it>in peripheral blood mononuclear cells (PBMCs) were determined. In the second experiment, we investigated <it>ISG15 </it>mRNA expression in PBMCs during the MRP in cattle after either artificial insemination (AI) or embryo transfer (ET).</p> <p>Results</p> <p>Intrauterine administration of IFNT stimulated <it>ISG15 </it>and <it>Mx2 </it>gene expressions in PBMCs in cattle, and there was a positive correlation between the expressions of peripheral markers and the quantity of IFNT administered. In pregnant and normal interestrous interval (< 25 d) cattle (nIEI cattle), expression levels of the <it>ISG15 </it>gene showed similar patterns after AI and ET, and <it>ISG15 </it>mRNA expression was increased in pregnant cattle but unchanged in nIEI cattle. In contrast, <it>ISG15 </it>gene expression in extended interestrous interval (greater than or equal to 25 d) cattle (eIEI cattle) differed after ET compared with AI. In eIEI cattle after ET, <it>ISG15 </it>gene expression increased, such that the value on day 18 was intermediate between those of pregnant and nIEI cattle. In eIEI cattle after AI, <it>ISG15 </it>gene expression did not increase throughout the observation period.</p> <p>Conclusions</p> <p>The results of the current study indicate that the quantity of conceptus-derived IFNT can be estimated by measuring <it>ISG15 </it>mRNA levels in PBMCs from cattle. Using this approach, we demonstrate that <it>ISG15 </it>gene expression during the MRP in eIEI cattle differed after ET compared with AI. In addition, the modest increase in <it>ISG15 </it>gene expression in eIEI cattle after ET suggests that late embryo losses were due to delayed or insufficient growth of the conceptus during the MRP in cattle.</p