Ograniczanie wyników

Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 28

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  morphotype
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Ichthyosaurs rapidly diversified and colonised a wide range of ecological niches during the Early and Middle Triassic period, but experienced a major decline in diversity near the end of the Triassic. Timing and causes of this demise and the subsequent rapid radiation of the diverse, but less disparate, parvipelvian ichthyosaurs are still unknown, notably because of inadequate sampling in strata of latest Triassic age. Here, we describe an exceptionally large radius from Lower Jurassic deposits at Penarth near Cardiff, south Wales (UK) the morphology of which places it within the giant Triassic shastasaurids. A tentative total body size estimate, based on a regression analysis of various complete ichthyosaur skeletons, yields a value of 12-15 m. The specimen is substantially younger than any previously reported last known occurrences of shastasaurids and implies a Lazarus range in the lowermost Jurassic for this ichthyosaur morphotype.
A modified method of glutaraldeyde-osmium tetroxide fixation was adjusted to characterize the ultrastructure of Candida albicans pleomorphic forms, using phase-contrast microscopy, scanning electron microscopy and transmission electron microscopy. &e discovered morphological criteria defining the individual morphotypes are discussed in terms of mycological and histopathological diagnostics of candidiasis. &e relations are discussed between fungal pleomorphism, virulence and susceptibility of di!erent morphotypes to fungicides.
Twelve morphometric variables of Cardaminopsis halleri individuals from four sites in upper silesia province were analyzed to establish the pattern of interpopulational relations. Two hundred plants were collected from two very polluted areas (near zinc-lead and zinc smelters) as well as from two other sites in unpolluted areas within the same bioclimatic region. stem size, dimensions of leaves and rosettes, as well as flower and seed numbers and in­dividual dry weights were studied using standard biometric methods. cluster analysis indicated overall differences among populations. Those four populations are different with respect to all variables. Discriminant function analysis confirmed seed number as the most important variable in the evaluation of interpopulational variability.
9
72%
The Galinha tracksite reveals a sequence of Bajocian–Bathonian limestones belonging to the Serra de Aire Formation (West−Central Portugal) and is one of the few sites in the world where Middle Jurassic sauropod dinosaur tracks can be found. This tracksite is characterised by the presence of long, wide gauge sauropod trackways, the Middle Jurassic age of which suggests these dinosaurs were more widely distributed over time than previously thought. Two trackways contain unique pes and manus prints with morphologies that allow a new sauropod ichnotaxon to be described: Polyonyx gomesi igen. et isp. nov. On the basis of different manus/pes prints and trackway features, the proposal is made to subdivide Sauropodomorpha ichno−morphotypes into five groups: Tetrasauropus−like, Otozoum−like, Breviparopus/Parabrontopodus−like; Brontopodus−like, and Polyonyx−like. Polyonyx gomesi igen. et isp. nov. is thought to represent a nonneosauropod eusauropod, with a well developed manus digit I. The posterior orientation of this digit print suggests they were made by a eusauropod dinosaur with a posteriorly rotated pollex. The manus print morphologies observed in two trackways suggest a stage of manus structure intermediate between the primitive non−tubular sauropod manus and the tubular metacarpal arrangement characteristic of more derived sauropods. The low heteropody (manus:pes area ratio 1:2) of the trackway renders it possible they could have been made by eusauropods such as Turiasaurus riodevensis, which has a similar manus:pes area ratio. The Polyonyx igen. nov. trackway was made by non−neosauropod eusauropod, and suggests that wide gauge sauropod trackways were not exclusively made by Titanosauriformes.
Indigenous mycorrhizal colonisation of one (1/0) and two (2/0) year old Scots pine (Pinus sylvestris L.) seedlings from forest nurseries situated in the north-west part of Poland was investigated. Seedlings were fertilized after a schedule designed to satisfy their requirements which resulted from soil analysis of each nursery. In autumn needle nitrogen concentration and mycorrhizal status were estimated. As a rule seedlings 1/0 obtained high doses of fertilizers, and their needle nitrogen concentration highly exceeded the recommended optimal level above which mycorrhiza formation is greatly restricted. Highly negative correlation was found between the nitrogen status of foliage and mycorrhizal quantitative and qualitative colonisation estimated in the abundance class of 0-5. When internal nitrogen level was low, several ectomycorrhizal morphotypes were found on roots of tested plants. Excessive nitrogen fertilization decreased root ramification pattern and along with increased pH promoted ectendomycorrhizal symbiosis. Two-year-old seedlings (2/0) were characterised by significantly lower nitrogen concentration in the needles which resulted in much higher ectomycorrhizal colonisation. Ectendomycorrhizal symbiosis in the case of 2/0 seedlings was scarce. The results indicate that natural colonisation in nurseries is dependent on the soil management practices, especially nitrogen fertilization. Optimalization of nitrogen fertilization may intensify ectomycorrhizal colonisation of the nursery stock from indigenous fungal species and improve the growth of Scots pine seedlings in bare-root nurseries and plantations.
Six well exposed mid−Ludlow stromatoporoid−dominated reef biostromes in four localities from the Hemse Group in southeastern Gotland, Sweden comprise a stromatoporoid assemblage dominated by four species; Clathrodictyon mohicanum, “Stromatopora” bekkeri, Plectostroma scaniense, and Lophiostroma schmidtii. All biostromes investigated in this area (of approximately 30 km²) are interpreted to belong to a single faunal assemblage forming a dense accumulation of fossils that is probably the best exposed stromatoporoid−rich deposit of the Silurian. The results from this comprehensive study strengthen earlier interpretations of a combination of genetic and environmental control on growth−forms of the stromatoporoids. Growth styles are similar for stromatoporoids in all six biostromes. Differences in biostrome fabric are due to variations in the degree of disturbance by storms. The uniformity of facies and the widespread low−diversity fauna support the view that palaeoenvironmental conditions were similar across the area where these biostromes crop out, and promoted the extraordinary growth of stromatoporoids in this shallow shelf area.
Isolated teeth from vertebrate microfossil localities often provide unique information on the biodiversity of ancient ecosystems that might otherwise remain unrecognized. Microfossil sampling is a particularly valuable tool for documenting taxa that are poorly represented in macrofossil surveys due to small body size, fragile skeletal structure, or relatively low ecosystem abundance. Because biodiversity patterns in the late Maastrichtian of North American are the primary data for a broad array of studies regarding non-avian dinosaur extinction in the terminal Cretaceous, intensive sampling on multiple scales is critical to understanding the nature of this event. We address theropod biodiversity in the Maastrichtian by examining teeth collected from the Hell Creek Formation locality that yielded FMNH PR 2081 (the Tyrannosaurus rex specimen “Sue”). Eight morphotypes (three previously undocumented) are identified in the sample, representing Tyrannosauridae, Dromaeosauridae, Troodontidae, and Avialae. Noticeably absent are teeth attributed to the morphotypes Richardoestesia and Paronychodon. Morphometric comparison to dromaeosaurid teeth from multiple Hell Creek and Lance formations microsites reveals two unique dromaeosaurid morphotypes bearing finer distal denticles than present on teeth of similar size, and also differences in crown shape in at least one of these. These findings suggest more dromaeosaurid taxa, and a higher Maastrichtian biodiversity, than previously appreciated.
Seeds of the Andean lupine are characterised by high nutritional value, and the plant could become an important crop in the production of food and forage. This legume continues to attract growing interest around the world. A field experiment was carried out in in Lower Silesia, Poland, in 2011-2012. Two Andean lupine morphotypes (indeterminate and determinate) were analysed. Andean lupine was grown in treatments characterised by different sowing dates and plant density per m2. Seed yield, macronutrient content, protein content and health were evaluated at harvest. Seed yield was determined by the interaction of all experimental factors. The indeterminate form produced a significantly higher yield than the determinate form, regardless of the sowing date. The factors had little influence on the mineral content of seeds and total protein content. Andean lupine seeds were colonised mostly by saprotrophic fungi of the genera Alternaria, Cladosporium, Epicoccum and Rhizopus and pathogenic fungi of the genera Botrytis, Colletotrichum and Fusarium. Delayed sowing contributed to seed colonisation by fungi of the genus Colletotrichum. The determinate form was more susceptible to infection than the indeterminate form. Molecular analysis showed that the Colletotrichum isolates found in the study belong to the Colletotrichum acutatum species complex. The pathogen causing lupine anthracnose, isolated from the seeds of Andean lupine in the present study, was identified as Colletotrichum lupini (within C. acutatum complex) in a molecular analysis, and its DNA sequence was compared with those of the isolates deposited in the GenBank.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.