ULTRASTRUCTURE AND DEVELOPMENT OF MESOZOIC POLLEN: CLASSOPOLLIS

Because of its complexity one of the most unusual fossil pollen types is the genus Classopollis. Grains of this broadly defined Mesozoic taxon range from the late Triassic into the Cretaceous (Turonian), and include forms that are spherical with a subequatorial rimula. On the proximal pole is a trilete mark, and on the distal surface a thin area in the sporoderm termed the cryptopore. Ultrastructural studies of Classopollis have been completed on grains extracted from the pollen cone Classostrobus comptonensis collected from the Lower Cretaceous Wealden beds on the Isle of Wight, England. The sporoderm consists of clearly defined nexine and sexine components, with the mature nexine composed of approximately 20 electron dense lamellae, each about 10 nm thick. The sexine consists of four (S_1–4) easily recognizable layers, with the most prominent zone formed of coarse, inwardly-tapering elements. The S₂ layer is uniformly thickened, except in specialized areas (e.g., trilete, rimula, cryptopore) where it becomes thin. The remaining wall layers include spinules that ornament the surface and a uniform series of small lacunae associated with the spinule bases. The presence of orbicules and a complex system of membranes associated with the grains extracted from less mature cones provides an opportunity to trace some developmental stages in Classopollis sporoderm ontogeny, and to compare these stages with those of selected extant pollen types. The functional significance of the infrastructure in Classopollis pollen is discussed.     

The effect of bioturbation by polychaetes (Opheliidae) on benthic foraminiferal assemblages and test preservation

Biological activity such as burrowing can alter benthic foraminiferal shell preservation and may also modify benthic foraminiferal assemblages by vertical mixing, inducing sediment homogenization. Here, we analyse benthic foraminiferal assemblages and taphonomy of upper Miocene marine deposits from Conil de la Frontera (Cádiz, south‐western Spain). The deposits consist of marls displaying a pervasive alternation of intensively bioturbated beds dominated by Macaronichnus segregatis traces (ichnofabric index 4–5) and non‐bioturbated beds. Benthic foraminiferal assemblages are dominated by Cibicidoides mundulus and Cibicides refulgens, indicating that the marls were deposited on an oligotrophic, well‐oxygenated upper slope. The impact of burrowing on the preservation of benthic foraminiferal tests was tested using Q‐mode cluster analysis, which found two well‐differentiated groups of samples, one including the non‐bioturbated beds and the other encompassing the bioturbated ones. Fragmentation and recrystallization account for the differentiation of these groups, both being higher in the bioturbated sediments. Aggressive chemical digestion by the Macaronichnus trace‐makers, assumed to be a polychaete worm of the family Opheliidae, etched the microfossil shells, making them more vulnerable to fragmentation. Intense bioturbation favoured the circulation of pore fluids, encouraging recrystallization. Pervasive burrowing resulted in significant vertical reworking of microfossils. As a consequence, benthic foraminiferal assemblages in the bioturbated beds were homogenized in the mixed layer; that is, the uppermost layer of the substrate totally burrowed. The alternation of bioturbated and non‐bioturbated beds reflects episodic transfer of food particles down slope from shallower parts of the shelf as well as from the continent due to storms under otherwise homogeneous oligotrophic marine conditions.     

STIGMARIAN PETRIFACTIONS FROM THE PENNSYLVANIAN OF COLORADO

The designation Stigmaria ficoides is restricted to casts and impressions. Petrifactions of Stigmaria arnoldii sp. n. occur in Pennsylvanian age strata in Trout Creek Pass, Colorado. The rootlet gaps of this species appear narrow and elongate in both cross and longitudinal sections. Rootlet traces are contiguous with the secondary xylem to its outer margin and are surrounded by a small parenchyma sheath in the middle cortex. The outer cortex consists of an inner layer of primary tissue and a relatively thick zone of periderm. S. arnoldii most closely resembles material described as S. ficoides from England. Various stigmarian characters are evaluated with regard to their systematic or ontogenetic significance.     

Differences in durations of stay for surgery in the NHS and private sector in England and Wales.

Median durations of stay in England and Wales for eight "marker" operations were consistently shorter for patients in pay beds in the National Health Service than for patients in independent acute hospitals or public sector beds. This pattern was seen for both preoperative and postoperative stay and among specific age groups. Differential use of other hospitals for part of the period of care was not a factor, except for patients having hip replacement operations treated in NHS pay beds, one in seven of whom appeared to transfer to public sector care postoperatively. These findings suggest that there is scope for a possible further reduction in durations of stay in public sector beds and, within the private sector, for an assessment of whether spells in independent hospitals need be longer than in NHS pay beds.     

TAXODIACEOUS BARK FROM THE UPPER CRETACEOUS OF ALBERTA

The structure of a piece of silicified bark of Taxodioxylon gypsaceum from near Medicine Hat in Southern Alberta is described. The fossil specimen probably came from Upper Cretaceous beds. The fossil shows affinities with the bark of modern Sequoia. Vectia luccombensis Stopes (1915) from the Lower Greensand (Aptian) of England probably constitutes an isolated piece of taxodiaceous bark, similar to the inner bark of the Alberta specimen.     

Occurrence and host preferences of Anopheles maculipennis group mosquitoes in England and Wales

Mosquitoes of the Anopheles maculipennis Meigen (Diptera: Culicidae) group are of public health concern: five of the 11 morphologically indistinct species have been historically considered as vectors of malaria in Europe. Three members of the An. maculipennis group have been reported in the U.K.: Anopheles atroparvus van Thiel; Anopheles messeae Falleroni, and Anopheles daciae Linton, Nicolescu & Harbach. To study the distribution of the three U.K. species, particularly that of An. daciae, we developed a polymerase chain reaction–Restriction fragment length polymorphism (PCR‐RFLP) assay using the nuclear ribosomal internal transcribed spacer 2 (ITS‐2) gene. Anopheles daciae was found to be widespread, occurring in four of the five counties surveyed in southern England and on the Welsh island of Anglesey, often in sympatry with the closely related species An. messeae. The host preferences of 237 blood‐fed females were determined using either direct sequencing or PCR‐based fragment analysis of the mitochondrial cytochrome oxidase b gene with DNA from females' abdomens. All three species were found to be opportunistic, having fed on at least three different hosts. Seventeen individuals contained multiple bloodmeals, including two An. daciae that had fed on humans and birds. Our results show that An. daciae is widespread in England and Wales, occurs in sympatry with other members of the An. maculipennis group, and feeds on humans, which suggests it is a potential vector of disease in the U.K.     

Biogeographic analysis of the Uhu and LOA elements in the Hawaiian Drosophila

Two transposable elements have been isolated from the Hawaiian Drosophila, the Uhu and LOA elements. The Uhu element has been shown to be present in a group of closely related species, the planitibia subgroup of the picture-winged Drosophila. This study examines the distribution of the Uhu element in several other subgroups of the picture-winged Drosophila, as well as the modified-mouthparts and antopocerus groups of the Hawaiian Drosophila. The LOA element has a much more limited distribution, having only been found in representatives of the planitibia and grimshawi subgroups of the picture-winged Drosophila. For both the Uhu and LOA elements there is an inverse correlation between the copy number of the element and the age of the island on which the species is endemic, i.e., species endemic to the Island of Hawaii, the youngest island, have the highest copy number, while species endemic to Kauai, the oldest island, have the lowest copy number of the element. The correlation suggests there is a relationship between speciation and the activity of transposable elements. Received: 6 January 1997; in revised form: 6 August 1997 / Accepted: 21 August 1997     

Seafloor erosion and sea-level change: Early Jurassic Blue Lias Formation of central England

Minor bedforms within the mudstone-dominated Early Jurassic Hettangian Saltford Shale Member (Liasicus up to Angulata Chronozone) of the Blue Lias Formation in central England, indicate weak seafloor erosion in a mid to outer ramp setting. Distal storm flows below maximum storm wave base are proposed as the most likely generative mechanism for silty scour and gutter casts that enclose concentrations of well-preserved schlotheimiid ammonites and arthropod trace fossils. Within the upper part of the Saltford Shale (probably Angulata Chronozone), a discrete layer of reworked and bioencrusted limestone nodules signifies an episode of more persistent seafloor erosion. The immediately overlying strata, transitional to the Hettangian–Sinemurian Rugby Limestone Member, are relatively bioturbated and feature fossils of macrobenthos, as well as shell concentrations resembling relatively proximal storm beds. This suggests that the reworked nodule horizon marks sea-level fall, rather than stratigraphic condensation associated with sediment starvation. The biostratigraphic evidence raises the possibility that this erosional episode correlates with a mid-Angulata Chronozone hiatus documented from the Wessex Basin, southwest England. Equally however, it could be linked to contemporaneous movement on one or more nearby faults, affecting the southern part of the English East Midlands Shelf.     

Ordovician trimerellacean brachiopod shell beds

The large, thick-shelled, inarticulate brachiopod Eodinobolus forms many conspicuous deposits of shells in the Upper Ordovician limestones of central western New South Wales. Both in situ and reworked shell beds arc preserved at recurrent intervals through the successions, in similar facies of both transgressivc and regressive phases of deposition. In situ shell beds arc best developed in transgressivc sequences, with up to four generations of shells exhibited in the individual in situ beds. These monotypic and very low diversity shell beds are interpreted as having formed in marginal marine, quiet water conditions: (1) on the fringes of an offshore island (in part the Molong High of the Tasman Orogen), with the island still providing a fairly continuous supply of terrigenous material: and, (2) after submergence of the island, on the resulting terrigenous-free, major offshore Bahamas-like platform. This may imply that the shell beds developed in different salinity regimes. Possibly Eodinobolus was capable of tolerating a wider than normal range of salinity, from slightly brackish through normal marine, even to marginally hypersaline. However, in both settings, Eodinobolus, in its role as the dominant member of the respective pioneer community, colonized similar substrates in the low energy mud zone. This appears to suggest depositional environments most directly analogous to those of Palaeozoic virgianid pentamerides, and perhaps also comparable with some modern marginal marine oyster and mussel-bed occurrences. ?Ordovician, Brachiopoda, Eodinobolus, palaeoecology, facies, shell beds. New South Wales.     

Trends in abundance of rocky intertidal seaweeds and filter feeders across gradients of elevation,wave exposure,and ice scour in eastern Canada

On NW Atlantic rocky shores, the main basal organisms in intertidal communities are seaweeds (Ascophyllum nodosum, Fucus spp. and Chondrus crispus) and filter feeders (barnacles, Semibalanus balanoides, and mussels, Mytilus spp.). Their ecology has been extensively studied in New England (United States), but knowledge gaps exist for northern shores, which are subjected to stronger environmental stress. Therefore, we studied the above organisms on Canadian shores. We quantified the summer abundance of these seaweeds and filter feeders across full vertical (intertidal elevation) and horizontal (wave exposure and winter ice scour) environmental gradients on the Gulf of St. Lawrence and open Atlantic coasts of Nova Scotia. At the regional scale along the open Atlantic coast, seaweeds showed similar abundances in Nova Scotia than values reported for New England. However, both filter feeders were considerably less abundant in Nova Scotia. At the local scale in Nova Scotia, intense winter ice scour (which only occurs on the Gulf of St. Lawrence coast) was associated with a very low abundance of all species except barnacles. Spatial trends in Nova Scotia were similar to patterns known for certain species elsewhere, such as A. nodosum being almost restricted to sheltered habitats, regardless of elevation, and C. crispus being almost restricted to low elevations, regardless of exposure. Other trends were, however, characteristic of Nova Scotia, such as C. crispus being frequent at low elevations in exposed habitats, unlike in New England, where mussels often predominate there because of competitive advantages. In Nova Scotia, mussels were always restricted to cracks and crevices, unlike in New England, where they form extensive intertidal beds on exposed shores. The direct effects of increased environmental stress and indirect effects through altered interspecific interactions might explain the regional differences in local species distribution, which will require experimental validation. Handling editor: K. Martens     

Widespread primary,but geographically restricted secondary,human introductions of wall lizards,Podarcis muralis

Establishing the introduction pathways of alien species is a fundamental task in invasion biology. The common wall lizard, Podarcis muralis, has been widely introduced outside of its native range in both Europe and North America, primarily through escaped pets or deliberate release of animals from captive or wild populations. Here, we use Bayesian clustering, approximate Bayesian computation (ABC) methods and network analyses to reconstruct the origin and colonization history of 23 non‐native populations of wall lizards in England. Our analyses show that established populations in southern England originate from at least nine separate sources of animals from native populations in France and Italy. Secondary introductions from previously established non‐native populations were supported for eleven (47%) populations. In contrast to the primary introductions, secondary introductions were highly restricted geographically and appear to have occurred within a limited time frame rather than being increasingly common. Together, these data suggest that extant wall lizard populations in England are the result of isolated accidental and deliberate releases of imported animals since the 1970s, with only local translocation of animals from established non‐native populations. Given that populations introduced as recently as 25 years ago show evidence of having adapted to cool climate, discouraging further translocations may be important to prevent more extensive establishment on the south coast of England.     

First genetic evidence that invasive bullhead (Cottus L. 1758) in Scotland is of English origin and the difficulty of resolving the European Cottus species taxonomy

The European bullhead (Cottus gobio) is widely distributed across Europe, and within the UK is native to England and Wales, where it is protected under the Habitats Directive. In Scotland, however, the species is considered invasive and thriving populations are recorded in the Forth and Clyde river catchments, and the Ale Water in the Scottish Borders. The genetic identity of the Scottish populations has not been established. There is also debate about the status of the European bullhead and its validity as single species, a species complex with several unresolved species, or distinct different species in its European distribution range. There is therefore a need to determine the taxonomy and likely source of the novel Scottish populations. Genetic analyses using cytochrome oxidase 1 (COI) mitochondrial DNA sequences were undertaken on specimens from the Forth and Clyde catchments, and combined with the results of morphological characteristics to provide a comprehensive assessment of the taxonomic classification for Scottish bullheads. There was considerable variation in morphological characteristics between populations within Scotland and a wider range of variability than previously recorded for English populations. Genetically the Scottish populations were very closely related to English specimens, supporting the hypothesis of introduction directly from England to Scotland. In terms of broader relationships, Scottish specimens are genetically more closely related to the ostensible species Chabot fluviatile Cottus perifretum, which has been suggested as one of a complex of species across Europe. Morphologically they exhibit characteristics on the spectrum between C. perifretum and C. gobio. There is an urgent need for the clarification of the taxonomy of Cottus sp(p). to avoid confusion in future publications, legislation and management practices relating to bullheads throughout the UK and Europe.     

STRUCTURALLY PRESERVED LEAVES OF HARRIMANELLA HYPNOIDES (ERICACEAE): PALEOECOLOGY OF A NEW NORTH AMERICAN LATE PLEISTOCENE FOSSIL

Plant macrofossils from the basal inorganic sediments at Tom Swamp, north central Massachusetts, contained leaves, seeds, and fruits of arctic-alpine species, nearly all of which occur at present near the summits of Mt. Washington and Mt. Katahdin (New England) and in other alpine and arctic areas northward in eastern North America. Included were the needle-leaves of the dwarf shrub, Harrimanella hypnoides (L.) Coville, which matched comparative modern leaf samples in all anatomical details. The macrofossil assemblage was deposited before 12,830 ± 120 radiocarbon years ago and prior to the expansion of spruce populations in the region. Fossils of H. hypnoides suggest that snow beds were a regular feature of the summer landscape of southern New England during late glacial time. Calculations using the average lapse rate indicate that the mean annual paleotemperature in the Tom Swamp area may have been depressed 8–9 C below present means.     

Invasive diatom,Cymbella janischii adhering on body surface of native aquatic beetles,Grouvellinus nitidus (Elmidae) and Ectopria opaca (Psephenidae) in Japan

Cymbella janischii, an invasive species of diatom, has been broadening its geographical range in Japan since 2004, flourishing in substantial colonies in river beds. As thick and mucilaginous colonies of this diatom often cover large areas of river beds, this elicits concerns regarding the potential alteration of sedimentary bottom structures and resultant effects on the native ecosystems. The presence of the diatoms growing on the body surface of two aquatic beetles, Grouvellinus nitidus (Elmidae) and Ectopria opaca (Psephenidae) in a Japanese river was confirmed. This constitutes the inaugural documentation of invasive diatoms having a specific relationship with native aquatic insects at an individual level.     

Electron microscope investigation of sieve-element ontogeny and structure inUlmus americana

Summary During advanced stages of sieve-element differentiation inUlmus americana L., dispersal of the P-protein (slime) bodies results in formation of a peripheral network of strands consisting of aggregates of P-protein components having a striated, fibrillar appearance. The tonoplast is present throughout the period of P-protein body dispersal. Perforation of the sieve plates is initiated during early stages of P-protein body dispersal.Small P-protein bodies consist of tubular components, most of which measure about 180 Å in diameter. With increase in size of the P-protein bodies narrower components appear. At the time of initiation of P-protein body dispersal, most of the components comprising the bodies are of relatively narrow diameters (most 130–140 Å) and have a striated, fibrillar appearance. Both wide and narrow P-protein components are present throughout the period of sieve-element differentiation and in the mature cell as well, and a complete intergradation in size and appearance exists between the two extremes. Both extremes of P-protein component have a similar substructure: an electron-transparent lumen and an electronopaque wall composed of subunits, apparently in helical arrangement. The distribution of P protein in mature sieve elements was quite variable.The parietal layer of cytoplasm in matureUlmus sieve elements consists of plasmalemma, endoplasmic reticulum cisternae in two forms (as a complex network closely applied to the plasmalemma and in stacks along the wall), mitochondria, and plastids.     

The microbe–mineral environment and gypsum neogenesis in a weathered polar evaporite

Evaporitic deposits are a globally widespread habitat for micro‐organisms. The microbe–mineral environment in weathered and remobilized gypsum from exposed mid‐Ordovician marine evaporite beds in the polar desert of Devon Island, Nunavut, Canadian High Arctic was examined. The gypsum is characterized by internal green zones of cyanobacterial colonization (dominated by Gloeocapsa/Aphanothece and Chroococcidiopsis spp. morphotypes) and abundant black zones, visible from the surface, that contain pigmented cyanobacteria and fungi. Bioessential elements in the gypsum are primarily provided by allochthonous material from the present‐day polar desert. The disruption, uplift and rotation of the evaporite beds by the Haughton meteorite impact 39 Ma have facilitated gypsum weathering and its accessibility as a habitat. No cultured cyanobacteria, bacteria and fungi were halophilic consistent with the expectation that halophily is not required to persist in gypsum habitats. Heterotrophic bacteria from the evaporite were slightly or moderately halotolerant, as were heterotrophs isolated from soil near the gypsum outcrop showing that halotolerance is common in arctic bacteria in this location. Psychrotolerant Arthrobacter species were isolated. No psychrophilic organisms were isolated. Two Arthrobacter isolates from the evaporite were used to mediate gypsum neogenesis in the laboratory, demonstrating a potential role for microbial biomineralization processes in polar environments.     

Is London overbedded?

OBJECTIVE--To examine whether there are too many hospital beds in London. DESIGN--Analysis of data from the Hospital In-Patient Enquiry, Mental Health Enquiry, health service indicators, and Emergency Bed Service. SETTING--England, London, and inner London. RESULTS--Hospital admission rates for acute plus geriatric services for London residents were very similar to the national values in all age groups. In the special case considered in the Tomlinson report--acute services in inner London--the admission rate was 22% above the value for England. However, the admission rate of inner deprived Londoners was 9% below that of comparable areas outside London. For psychiatry, admission rates in London roughly equalled those in comparable areas. When special health authorities were excluded, in 1990-1 there were 4% more acute plus geriatric beds available per resident in London than in England. Bed provision has been reduced more rapidly in London than nationally. Extrapolating the trend of bed closures forward indicates that beds (all and acute) per resident in London are now at about the national average. Data from the Emergency Bed Service indicate that the pressure on available hospital beds in London has been increasing since 1985. CONCLUSIONS--Data regarding bed provision and utilisation for all specialties by London residents do not provide a case for reducing the total hospital bed stock in London at a rate faster than elsewhere. Bed closures should take account of London''s relatively poorer social and primary health care circumstances, longer hospital waiting lists, poorer provision of residential homes, and evidence from the Emergency Bed Service of increasing pressure on beds. Higher average costs in London, some unavoidable, are forcing hospital beds to be closed at a faster rate in London than nationally.     

Thamnobryum cataractarum,a new species from Yorkshire,with observations on T. angustifolium and T. fernandesii

Abstract

Thamnobryum cataractarum sp. nov. is described from Yorkshire, England. It is most closely related to T. fernandesii from Madeira and is also similar to T. angustifolium from Derbyshire, England. The three species are compared, and the habitat of the new species is described. T. fernandesii and T. cataractarum are retained in Thamnobryum rather than in Crassiphyllum Ochyra.     

Cloning and characterization of piggyBac- like elements in lepidopteran insects

PiggyBac-like elements (PLE) are widespread in variety of organisms, however, few of them are active or have an intact transposon structure. To further define the distribution PLEs in Lepidoptera, where the original active piggyBac IFP2 was discovered, and potentially isolate new functional elements, a survey for PLEs by PCR amplification and Southern dot blots was performed. Two new PLEs, AyPLE and AaPLE, were successfully isolated from the noctuid species, Agrotis ypsilon and Argyrogramma agnate, respectively. These elements were found to be closely related to each other by sequence similarity, and by sharing the same 16 bp inverted terminal repeat sequences. The AyPLE1.1 and AaPLE1.1 elements are structurally intact having characteristic TTAA target site duplications, inverted terminal repeats and intact open reading frames encoding putative transposases with the presumed piggyBac DDD domains, which are features consistent with autonomous functional transposons. Phylogenetic analysis revealed that AyPLE1.1 and AaPLE1.1 cluster with another noctuid species element, HaPLE1.1, suggesting a common ancestor for the three types of PLEs. This contributes to our understanding of the distribution and evolution of piggyBac in Lepidoptera.     

An investigation of habitat occupancy by the nightingale Luscinia megarhynchos with respect to population change at the edge of its range in England

The nightingale Luscinia megarhynchos has undergone population decline and range contraction at the north-western limit of its distribution in England during the last 25 years. We examine patterns of habitat occupancy and habitat availability across sites with a range of population histories to see whether habitat loss is a plausible explanation for these declines. The number of singing males in 1999 correlated with area of primary nightingale habitat in the East Midlands (where the species has declined), but not in East Anglia (where the population has been stable). Change in population size between 1980 and 1999 and current habitat availability were weakly correlated in the East Midlands but not in East Anglia. These results are consistent with habitat loss having contributed to the decline of the nightingale in the East Midlands, but suggest that other, wider-scale, factors may be at least partially responsible for determining the abundance of the species within England as a whole.