Types Of Laminae Research Articles

MMP-9–Positive Neutrophil Infiltration Is Associated to Blood–Brain Barrier Breakdown and Basal Lamina Type IV Collagen Degradation During Hemorrhagic Transformation After Human Ischemic Stroke

An abnormal expression of some matrix metalloproteinases (MMPs) is related with hemorrhagic transformation events after stroke. Our aim was to investigate MMP-2 and MMP-9 in the ischemic brain and its relation with blood-brain barrier breakdown after hemorrhagic transformation in human stroke. We assessed 5 cases of fatal ischemic strokes with hemorrhagic complications; brain samples were obtained from infarct, hemorrhagic, and contralateral tissue. MMP-9 and MMP-2 content was analyzed by zymography and immunohistochemistry was performed to localize MMP-9 and to assess collagen IV integrity in the basal lamina. Laser capture microdissection was performed to isolate blood-brain barrier vessels to study these MMPs. Overall, MMP-9 levels were higher both in hemorrhagic and nonhemorrhagic infarcted tissue compared to contralateral areas (P<0.0001 and P<0.05). Moreover, levels of the cleaved MMP-9 85kDa-form were significantly elevated in the hemorrhagic compared to nonhemorrhagic and contralateral areas (P=0.033 and P<0.0001). No changes were found for MMP-2 content. Immunostaining revealed a strong MMP-9-positive neutrophil infiltration surrounding brain microvessels associated with severe basal lamina type IV collagen degradation and blood extravasation. Microdissection confirmed that content of MMP-9 was similarly high in microvessel endothelium from hemorrhagic and infarcted areas compared to contralateral hemisphere vessels (P<0.05), pointing to neutrophils surrounding dissected microvessels as the main source of MMP-9 in hemorrhagic areas. Our results show a strong neutrophil infiltration in the infarcted and hemorrhagic areas with local high MMP-9 content closely related to basal lamina collagen IV degradation and blood-brain barrier breakdown. Microvessel and inflammatory MMP-9 response are associated with hemorrhagic complications after stroke.

Morphological characterization of spinal cord dorsal horn lamina I neurons projecting to the parabrachial nucleus in the rat

Many Rexed's lamina I neurons are nociceptive and project to the brain. Lamina I projection neurons can be classified as multipolar, fusiform, or pyramidal, based on cell body shape and characteristics of their proximal dendrites in the horizontal plane. There is also evidence that both multipolar and fusiform cells are nociceptive and pyramidal neurons nonnociceptive. In this investigation we identified which types of lamina I neurons belong to the spinoparabrachial tract in the rat and characterized them regarding the presence or absence of neurokinin-1 receptor (NK-1r) immunoreactivity. For this, cholera toxin subunit B (CTb), conjugated to a fluorescent marker was injected unilaterally into the parabrachial nucleus. Sections were additionally stained for the detection of NK-1r immunoreactivity and were examined using fluorescence and confocal microscopy. Serial confocal optical sections and 3D reconstructions were obtained for a considerable number of neurons per animal. Using immunofluorescence, we assessed the proportion of lamina I neurons belonging to the spinoparabrachial (SPB) tract and/or expressing NK-1r. The relative distribution of neurons belonging to the SPB tract was: 38.7% multipolar, 36.8% fusiform, 22.7% pyramidal, and 1.9% unclassified. Most of the SPB neurons expressing NK-1r were either multipolar or fusiform. Pyramidal SPB neurons were seldom immunoreactive for NK-1r, an observation that provides further support to the concept that most lamina I projection neurons of the pyramidal type are nonnociceptive. In addition, our study provides further evidence that these distinct morphological types of neurons differ in their phenotypic properties, but not in their projection patterns.

Post-glacial seasonal diatom record of the Mertz Glacier Polynya, East Antarctica

An ultra-high-resolution post-glacial laminated sediment record from Mertz Ninnis Trough, East Antarctic Margin (EAM), has been analysed using SEM backscattered electron imagery, secondary electron imagery and quantitative diatom abundance. Laminations are classified using visually dominant diatom species and terrigenous content. Four biogenic diatom ooze laminae types, one diatom-bearing terrigenous lamina type and one diatom-bearing terrigenous sub-lamina type have been identified. Diatom ooze lamina types comprise near-monogeneric Hyalochaete Chaetoceros spp. resting spore laminae, laminae characterised by Corethron pennatum, laminae characterised by Rhizosolenia spp. and mixed diatom assemblage laminae. Diatom-bearing terrigenous lamina and sub-lamina types comprise mixed diatom assemblage terrigenous laminae and sub-laminae characterised by Porosira glacialis resting spores. Formation of each of these lamina types is controlled by seasonal changes in nutrients, oceanographic regimes and the Mertz Glacier Polynya dynamics.

Laminae type and possible mechanisms for the formation of laminated sediments in the Shaban Deep, northern Red Sea

Abstract. Laminated sediments in the Shaban Deep, a brine-filled basin in the northern Red Sea, were analyzed with backscattered electron imagery. Here we present possible mechanisms involved in the formation of laminae of various types and homogenous intervals arising from the detailed investigation of multicore GeoB 7805-1 (26°13.9' N and 35°22.6' E; water depth 1447 m) and gravity core GeoB 5836-2 (26°12.61' N, 35°21.56' E; water depth 1475 m). Sediment makeup includes six types: a) a laminated structure with alternating light (mainly coccoliths) and dark (diatom frustules) layers, where the diatom component is indicative of the intra-annual variability between stratification and mixing events; b) a pocket-like structure attributed to the sinking of particles within fecal pellets and aggregates; c) a matrix of tightly packed diatoms that relates to extended stratification/mixing periods of the water column; d) homogenous intervals that result from turbidity deposition; e) silt accumulations which origin may lie in agglutinated foraminifers; and f) pyrite layers with pyrite formation initiated at the seawater-brine interface.

Bryozoans and microbial communities of cool-temperate to subtropical latitudes?paleoecological implications

Laminar bryozoans of shallow marine sites from cool-temperate to subtropical climate in Japan and New Zealand tolerated mainly agglutinated biofilms composed of diatoms, fungi, cyanobacteria and other bacteria as well as debris trapped in slimes. Also monobacterial films were relatively frequent on living bryozoans, while rigid, tangled mats of filamentous cyanobacteria mainly occupied surrounding substrates or dead bryozoan colonies. Three levels of microbial fouling low, medium and high were defined. Low-level fouling was more frequent on bryozoan colonies collected at warm-water settings, while medium levels became more frequent in cooler water. The decrease of microbial fouling towards lower latitudes parallels findings in part one of this study (Kaselowsky et al. 2004, this volume) in which bryozoan lamina types comparatively strong in overgrowth competition increased towards lower latitudes. Such morphological signals of competitive interaction of bryozoans and associated epizoic biofilms are potentially of paleoecologic value. Our collections from two different sampling periods revealed only small changes between seasons which may account for the predominance of oceanographic factors controlling shallow marine sampling sites around Japan and New Zealand coasts.

The deforming bed characteristics of a stratified till assemblage in north East Anglia, UK: investigating controls on sediment rheology and strain signatures

The glacial coastal exposures of north Norfolk are a type site for subglacial glaciotectonic deforming bed sediments. This investigation of the lower stratified diamict within the North Sea Drift at West Runton reveals two distinct lamina types. Type 1 laminae are the product of primary extensional glaciotectonism, with ductile, intergranular pervasive shear predominating over brittle shear. Type 2 laminae also exhibit structures that can be attributed to ductile, intergranular pervasive shear and brittle shear, but the lateral continuity of Type 2 laminae and the presence of dropstone—like structures supports a primary subaqueous origin with secondary subglacial deformation. When coupled with micromorphological analysis, these findings show that ductile, viscous creep mechanisms control sedimentary architecture, and that ‘shear stratification’ in particular, has the potential to affect the rheological properties of the sediment pile and the hydraulic routing of basal water, ultimately influencing critical effective pressure fluctuations and the thresholds controlling the subglacial drainage system.

The deforming bed characteristics of a stratified till assemblage in north East Anglia, UK: investigating controls on sediment rheology and strain signatures

The glacial coastal exposures of north Norfolk are a type site for subglacial glaciotectonic deforming bed sediments. This investigation of the lower stratified diamict within the North Sea Drift at West Runton reveals two distinct lamina types. Type 1 laminae are the product of primary extensional glaciotectonism, with ductile, intergranular pervasive shear predominating over brittle shear. Type 2 laminae also exhibit structures that can be attributed to ductile, intergranular pervasive shear and brittle shear, but the lateral continuity of Type 2 laminae and the presence of dropstone—like structures supports a primary subaqueous origin with secondary subglacial deformation. When coupled with micromorphological analysis, these findings show that ductile, viscous creep mechanisms control sedimentary architecture, and that ‘shear stratification’ in particular, has the potential to affect the rheological properties of the sediment pile and the hydraulic routing of basal water, ultimately influencing critical effective pressure fluctuations and the thresholds controlling the subglacial drainage system.

Association of spinothalamic lamina I neurons and their ascending axons with calbindin-immunoreactivity in monkey and human

The calbindin-immunoreactivity of spinothalamic (STT) lamina I neurons and their ascending axons was examined in two experiments. In the first experiment, lamina I STT neurons in macaque monkeys were double-labeled for calbindin and for retrogradely transported WGA∗HRP following large ( n=2) or small ( n=1) injections that included the posterior thalamus. Most, but not all (78%) of the contralateral retrogradely labeled lamina I STT cells were positive for calbindin. Calbindin-immunoreactivity was not selectively associated with any particular anatomical type of lamina I STT cell; 82% of the fusiform cells, 78% of the pyramidal cells and 67% of the multipolar cells were double-labeled. In the second experiment, oblique transverse sections from upper cervical spinal segments of three macaque monkeys, one squirrel monkey and five humans were stained for calbindin-immunoreactivity. In each case, a distinct bundle of fibers was densely stained in the middle of the lateral funiculus. This matches the location of anterogradely labeled ascending lamina I axons observed in prior work in cats and monkeys, and it matches the location of the classically described ‘lateral spinothalamic tract’ in humans. This bundle had variable shape across cases, an observation that might have clinical significance. These findings support the view that lamina I STT neurons are involved in spinal cordotomies that reduce pain, temperature and itch sensations.

Immunohistochemical profiles of spinal lamina I neurones retrogradely labelled from the nucleus tractus solitarii in rat suggest excitatory projections.

Three morphologically distinct types of lamina I neurones, fusiform, flattened and pyramidal, project from the spinal cord to the caudal part of the nucleus tractus solitarii in the rat, and may represent a pathway whereby peripheral stimuli can modify autonomic functions. The neurochemistry of these three types of projection neurones was investigated using retrograde neuronal tracing with cholera toxin B-subunit combined with dual and triple immunofluorescence labelling for different neuroactive substances. None of the lamina I neurones with immunoreactivity for GABA or glycine were found to project to the nucleus tractus solitarii, whereas high levels of glutamate immunoreactivity, which may indicate a glutamatergic phenotype, were found in 18.4% of fusiform, 9.6% of pyramidal and 2.1% of flattened projection neurones. Immunoreactivity for calbindin-D28K was present in 34.9% of fusiform cells, 18.3% of pyramidal cells and 10.5% of flattened cells, and nitric oxide synthase immunoreactivity was detected in 13.8% of fusiform cells, 1.1% of pyramidal cells and 4.2% of flattened cells that had projections to the nucleus tractus solitarii. Calbindin immunoreactivity was co-localised in major subpopulations of projection neurones of each morphological type that contained glutamate immunoreactivity, whereas co-localisation of nitric oxide synthase immunoreactivity in these neurones was relatively uncommon. The pyramidal cell was the only retrogradely labelled cell type found to be immunoreactive for substance P, but few (<5%) of these neurones were immunolabelled. These data are consistent with the hypothesis that lamina I neurones projecting to the dorsal vagal complex are not inhibitory, and that some of them, belonging mostly to the fusiform and pyramidal types, may exert excitatory, glutamate- or substance P-mediated effects upon inhibitory interneurones in the nucleus tractus solitarii. Such excitatory pathways could be involved in the attenuation of the reflex control of blood pressure by both painful and innocuous peripheral stimuli, such as those arising in injury and exercise.

Microbial–silica interactions in Icelandic hot spring sinter: possible analogues for some Precambrian siliceous stromatolites

Silicified deposits, such as sinters, occur in several modern geothermal environments, but the mechanisms of silicification (and crucially the role of microorganisms in their construction) are still largely unresolved. Detailed examination of siliceous sinter, in particular sections of microstromatolites growing at the Krisuvik hot spring, Iceland, reveals that biomineralization contributes a major component to the overall structure, with approximately half the sinter thickness attributed to silicified microorganisms. Almost all microorganisms observed under the scanning electron microscope (SEM) are mineralized, with epicellular silica ranging in thickness from &lt; 5 μm coatings on individual cells, to regions where entire colonies are cemented together in an amorphous silica matrix tens of micrometres thick. Within the overall profile, there appears to be two very distinct types of laminae that alternate repeatedly throughout the microstromatolite: ‘microbial’ layers are predominantly consisting of filamentous, intact, vertically aligned, biomineralized cyanobacteria, identified as Calothrix and Fischerella sp.; and weakly laminated silica layers which appear to be devoid of any microbial component. The microbial layers commonly have a sharply defined base, overlying the weakly laminated silica, and a gradational upper surface merging into the weakly laminated silica. These cyclic laminations are probably explained by variations in microbial activity. Active growth during spring/summer allows the microorganisms to keep pace with silicification, with the cell surfaces facilitating silicification, while during their natural slow growth phase in the dark autumn/winter months silicification exceeds the bacteria’s ability to compensate (i.e. grow upwards). At this stage, the microbial colony is probably not essential to microstromatolite formation, with silicification presumably occurring abiogenically. When conditions once again become favourable for growth, recolonization of the solid silica surface by free‐living bacteria occurs: cell motility is not responsible for the laminations. We have also observed that microbial populations within the microstromatolite, some several mm in depth, appear viable, i.e. they still have their pigmentation, the trichomes are not collapsed, cell walls are unbroken, cytoplasm is still present and they proved culturable. This suggests that the bulk of silicification occurred rapidly, probably while the cells were still alive. Surprisingly, however, measurements of light transmittance through sections of the microstromatolite revealed that photosynthetically active light (PAL) only transmitted through the uppermost 2 mm. Therefore the ‘deeper’ microbial populations must have either: (i) altered their metabolic pathways; (ii) become metabolically inactive; or (iii) the deeper populations may be dominated by different microbial assemblages from that of the surface. From these collective observations, it now seems unequivocal that microstromatolite formation is intimately linked to microbial activity and that the sinter fabric results from a combination of biomineralization, cell growth and recolonization. Furthermore, the similarities in morphology and microbial component to some Precambrian stromatolites, preserved in primary chert, suggests that we may be witnessing contemporaneous biomineralization processes and growth patterns analogous to those of the early Earth.

Behavior of Adhesively Bonded Concrete-CFRP Joints at Low and High Temperatures

This paper presents an evaluation of the results obtained from an initial study carried out at the IBMB, Technical University of Braunschweig, on the influence of temperature on adhesively bonded plate-concrete joint systems. The results of a theoretical model are also presented. The type of specimen used in this study is a three-point bending beam. The concrete specimens were prismatic in form, 100 × 100 × 700 mm without an internal steel reinforcement, strengthened at the intradoss with two types of UD CFRP lamina 20 mm wide and 590 mm long of thickness 1.4 mm for the E = 300 GPa type and 1.24 mm for the E = 175 GPa type. The plate-bonded specimens were designed to produce bending failure under a load, by not bonding the lamina and the concrete around the midspan of the specimens. The specimens were tested to failure at −100°, −30°, and +40°C after an approximately homogeneous temperature distribution within the concrete specimen has been reached. For comparison only, specimens of the same type were tested to failure at room temperature. The results obtained showed varying behavior of the bonded plate-concrete joint depending on variations in temperature. Furthermore, they showed different failure mechanisms. Greater reductions in the ultimate bond force were recorded for the test specimens strengthened with lamina having a high elastic modulus. A reasonable correlation was found between the experimental and theoretical results.

Ultrastructure of the basal lamina of bovine ovarian follicles and its relationship to the membrana granulosa

Different morphological phenotypes of follicular basal lamina and of membrana granulosa have been observed. Ten preantral follicles (< 0. 1 mm), and 17 healthy and six atretic antral follicles (0.5-12 mm in diameter) were processed for light and electron microscopy to investigate the relationship the between follicular basal lamina and membrana granulosa. Within each antral follicle, the shape of the basal cells of the membrana granulosa was uniform, and either rounded or columnar. There were equal proportions of follicles </= 4 mm in diameter with columnar basal cells and with rounded basal cells. Larger follicles had only rounded basal cells. Conventional basal laminae of a single layer adjacent to the basal granulosa cells were observed in healthy follicles at the preantral and antral stages. However, at the preantral stage, the conventional types of basal lamina were enlarged or even partially laminated. A second type of basal lamina, described as 'loopy', occurred in about half the preantral follicles and in half the antral follicles </= 4 mm diameter. 'Loopy' basal laminae were not observed in larger follicles. 'Loopy' basal laminae were composed of basal laminae aligning the basal surface of basal granulosa cells, but with additional layers or loops often branching from the innermost layer. Each loop was usually < 1 microm long and had vesicles (20-30 nm) attached to the inner aspect. Basal cellular processes were also common, and vesicles could be seen budding off from these processes. In antral follicles, conventional basal laminae occurred in follicles with rounded basal granulosa cells. Other follicles with columnar cells, and atretic follicles, had the 'loopy' basal lamina phenotype. Thus, follicles have different basal laminae that relate to the morphology of the membrana granulosa.

Initial stages of laminar calcrete formation by roots: examples from the Neogene of central Spain

Thin carbonate laminae formed by root activity are common within Miocene detrital deposits of the Duero and Madrid basins. The laminae are about 3 cm thick, extending several metres laterally, and displace the original detrital sediment, which ranges in grain size from fine gravel to sandy clay. The thickness, morphology, microstructure and stable isotope compositions of the laminae indicate that they formed by the activities of roots and associated microorganisms within the soil. The laminae are similar to those commonly recognised in thick laminar calcrete profiles. Three types of laminae are recognised. Differences in the micromorphology of the laminae are explained as reflecting the different organisms involved and whether calcification occurred when the root was alive or decaying. The first type occurs in a profile at Paracuellos the Jarama, where the laminae consist of a mosaic of 20 mm calcite crystals whose arrangement indicates that calcification took place in the medulla of the root and probably occurred while the plant was alive. In a second type in the Villacadima profile, laminae comprise calcified root mats whose formation indicates the interplay of roots and fungi. Calcification of the cell-walls and intracellular spaces took place in the cortices of the roots and not in the medullas as revealed by the presence of central pores in every calcified root. A third type of lamina is recognised in profiles at Vin˜egra de Moran˜a and consists of mucilaginous sheets coated by needle-fibre calcite crystals. The occurrence of associated small root casts indicates that formation of the laminae occurred while the root was decaying and was also influenced by fungal activity. These laminae occur within poorly developed soils and their formation was controlled by the relationship between sedimentation, erosion and soil formation processes. Thus, the occurrence of these laminae interbedded with detrital sediments reflects environments where sedimentation was relatively low and episodic, so after the detrital sediment input surfaces were stable and root mats were able to develop. Renewed sedimentation accounted for the death of the root mats and the development of new ones on the new surfaces. Where the sedimentation rate is lower the laminae tend to amalgamate and thicker laminar calcrete profiles form with little or no interbedded detrital sediment.

NK-1 Receptor Immunoreactivity in Distinct Morphological Types of Lamina I Neurons of the Primate Spinal Cord

In cat and monkey, lamina I cells can be classified into three basic morphological types (fusiform, pyramidal, and multipolar), and recent intracellular labeling evidence in the cat indicates that fusiform and multipolar lamina I cells are two different types of nociceptive cells, whereas pyramidal cells are innocuous thermoreceptive-specific. Because earlier observations indicated that only nociceptive dorsal horn neurons respond to substance P (SP), we examined which morphological types of lamina I neurons express receptors for SP (NK-1r). We categorized NK-1r-immunoreactive (IR) lamina I neurons in serial horizontal sections from the cervical and lumbar enlargements of four monkeys. Consistent results were obtained by two independent teams of observers. Nearly all NK-1r-IR cells were fusiform (42%) or multipolar (43%), but only 6% were pyramidal (with 9% unclassified). We obtained similar findings in three monkeys in which we used double-labeling immunocytochemistry to identify NK-1r-IR and spinothalamic lamina I neurons retrogradely labeled with cholera toxin subunit b from the thalamus; most NK-1r-IR lamina I spinothalamic neurons were fusiform (48%) or multipolar (33%), and only 10% were pyramidal. In contrast, most (approximately 75%) pyramidal and some (approximately 25%) fusiform and multipolar lamina I spinothalamic neurons did not display NK-1r immunoreactivity. These data indicate that most fusiform and multipolar lamina I neurons in the monkey can express NK-1r, consistent with the idea that both types are nociceptive, whereas only a small proportion of lamina I pyramidal cells express this receptor, consistent with the previous finding that they are non-nociceptive. However, these findings also indicate that not all nociceptive lamina I neurons express receptors for SP.

Phénomènes biosédimentaires et genèsedes croûtes et enduits polymétalliques. L'exemple des dépôts hydrogénétiques de la marge ouest africaine et de la Méditerranée

The microstructures observed in the hydrogenetic ferromanganese crusts of neogene age sampled on the West African margin of the Central and Equatorial Atlantic are laminated. Three types of laminae were recognized. Several arguments, in particular TEM observations of ultra-thin sections, indicate that the laminae probably correspond to mineralized microbial films. The study of quaternary to recent ferromanganese coatings sampled in the Atlantic and in the Mediterranean Sea leads to the same conclusion. The mineralization of the biofilm is a step process. The sequestration of Fe and of variable amounts of Si preceeds the Mn scavenging. The type of lamina depends on the general hydrologic conditions of the bottom waters (currents activity, nutriments and Mn availability) but, also, on the microtopography of the sea water-lamina interface, probably because it introduces significant differences about Eh and Mn fluxes. Considering the low accretion rate of this type of deposit, it appears that the biofilm growth may be controled by a self-regulating process: the initial period of active production is followed by a long time interval of low production or of equilibrium between accumulation and removal of slime.

Diatomaceous sediments from the Miocene Monterey Formation, California; a lamina-scale investigation of biological, ecological, and sedimentary processes

Finely laminated diatomaceous sediments from the Miocene Monterey Formation, Lompoc, Santa Barbara County, California, record the mutualistic coupling of life processes and environmental evolution at subannual and subseasonal resolution. In this study we present a new classification of lamina and couplet styles based on couplet bimodality, lamina thickness, compositional domination, lamina spacing, and cyclicity. We also describe five distinct lamina types with emphasis on paleoenvironmental settings, paleoecological associations, and biologically mediated sedimentary/taphonomic processes. Detrital laminae, consisting of silt, clay, and robust diatoms, were deposited from continental runoff during rainy seasons. Thin biosiliceous laminae consist of either moderately preserved high-diversity diatom assemblages, or well-preserved monogeneric phytoplankton assemblages. Most thick, continuous diatomaceous laminae are composed of well-preserved monogeneric and monospecific diatom assemblages that likely experienced biologically induced aggregation and rapid sedimentation without grazing. Thick, discontinuous diatomaceous laminae consist of either Thalassiothrix longissima mats or Chaetoceros setae. Mat laminae reflect stratified water conditions and high biomass conditions developed via vertically migrating diatom mats. Setae laminae are problematic to interpret. Macerated biosilica laminae, consisting of closely packed and highly fragmented biosilica from a variety of taxa, reflect intense zooplankton maceration and dissolution of diverse phytoplankton assemblages. Our results illustrate how different lamina types and associations can be used to proxy specific ecological and oceanographic conditions. This study provides a foundation for developing a high-resolution time series of paleoenvironmental variability recorded by biological event strata in hemipelagic sediments.

Molecular α‐taxonomy of Hymenasplenium obliquissimum Complex (Aspleniaceae) Based on rbcL Sequence Comparisons

Abstract Hymenasplenium obliquissimum (Hayata) Nakaike is easily distinguished from other members of Hymenasplenium by its peculiar thin (two‐cell thick) and translucent laminae with no air spaces, which are adapted to their subaquatic habitat. However, there also exist intermediate forms which are similar to H. obliquissimum in gross morphology but live in drier habitats, having thicker (3–4 cell layers) and opaque laminae with air spaces. The two different laminae forms sometimes grow together and create a complex in southwestern China and northern Thailand. In this work, we determined the rbcL sequences of 21 samples from the complex and conducted molecular phylogenetic analysis. Three major clades were detected; one of them was composed only of specimens with thin forms from various localities, supporting the assertion that species with the thin laminae type (H. obliquissimum) are a different biological unit from those with the thicker laminae type. Two clades were recognized as having the thicker laminae type, but we failed to find any morphological difference between them. In the present study, we found sequence variations of the rbcL gene even in a fern species complex which is morphologically hard to distinguish. Such molecular techniques are useful even for monographic works which try to delimit species, especially of morphologically similar taxa like ferns.

A high resolution biomarker study of different lithofacies of organic sulfur-rich carbonate rocks of a Kimmeridgian lagoon (French southern Jura)

The Upper Jurassic Calcaires en plaquettes Formation (southern Jura, France), which was deposited in a lagoonal setting, reveals three lithofacies: limestones with fine-scale parallel laminations, limestones with undulated (stromatolite-type) laminations and massive limestones. It was examined, at the millimetre scale, if the lithological differences are accompanied by differences in the composition of organic matter (OM), and if microbial mats played a role in the preservation of OM, as suggested previously. Four types of laminae (light/parallel, dark/parallel, light/undulated, dark/undulated), and a massive limestone sample were analysed. The OM in all facies is characterised by a high hydrogen index (870–970) and a variable δ 13C content (−23.5 or to −28.1‰). The molecular composition of OM appeared similar in all samples, e.g.: (i) Extractable biomarkers are dominated by n-alkane and hopanoid carbon skeletons, predominantly in a sulfur-bound form. (ii) Isorenieratene derivatives, indicating anoxic conditions in the photic zone, are present in relatively large amounts. (iii) Kerogen pyrolysates are dominated by organic sulfur compounds. Notwithstanding the overall similarity in OM composition, some significant differences were observed, e.g.: (i) Low-molecular-weight sulfur-bound hopanoids and steroids are relatively more abundant in TOC-lean, light-coloured samples than in TOC-rich, dark-coloured samples. This is probably related to differences in the degree of intermolecular sulfur cross-linking of the OM. (ii) The concentrations and distributions of several biomarkers in the light-coloured, undulated sample differ from those in the other samples. These differences are attributed to the periodic occurrence of microbial mats. Our data indicate that OM in the Calcaires en plaquettes Formation is predominantly composed of sulfur-bound lipids formed at times that bottom waters were euxinic. A periodic deepening of the oxic/anoxic interface, and of the light penetration depth, to below the sediment surface, allowed microbial mats to develop. Organic remains of the mats, however, are swamped by sulfur-bound planktonic lipids.

Leaf anatomy of Raoulia Hook.f. (Compositae, Gnaphalieae)

Leaf anatomy is compared for all species of Raoulia. The species are tabulated according to their lamina structure. Noteworthy anatomical features are lamina type and grade of differentiation, stomatal position, epidermal and cuticle thickness, shape of mesophyll cells, presence or absence of central clear cells, sclerenchyma caps, abaxial collenchyma and protruding midrib. It is shown that leaf anatomy data provide characters which are taxonomically useful in Raoulia. The main subgenera are supported except that the leaf anatomy of R. haastii is anomalous and that of R. youngii is typical of R. subg. Raoulia rather than R. subg. Psychrophyton. The leaf anatomy of R. petriensis is unique in the genus.

Leaf anatomy ofRaouliaHook.f. (Compositae, Gnaphalieae)

Leaf anatomy is compared for all species ofRaoulia.The species are tabulated according to their lamina structure. Noteworthy anatomical features are lamina type and grade of differentiation, stomatal position, epidermal and cuticle thickness, shape of mesophyll cells, presence or absence of central clear cells, sclerenchyma caps, abaxial collenchyma and protruding midrib. It is shown that leaf anatomy data provide characters which are taxonomically useful inRaoulia.The main subgenera are supported except that the leaf anatomy ofR. haastiiis anomalous and that ofR. youngiiis typical ofR.subg.Raouliarather thanR.subg.Psychrophyton.The leaf anatomy ofR. petriensisis unique in the genus.