Helminth parasites of the wild rabbit Oryctolagus cuniculus near Malham Tarn, Yorkshire, UK

Between 1992 and 1996, 95 rabbits from the immediate locality of Malham Tarn, North Yorkshire, UK were examined for the presence of helminth parasites. All the examinations took place in late September or October. Three species of nematodes, Graphidium strigosum, Passalurus ambiguus and Trichostrongylus retortaeformis and two species of cestodes, Taenia pisiformis and Cittotaenia pectinata were identified. There were no associations between helminth species richness and year of sampling, host weight or sex. A logistic model was fitted to the prevalence data from these helminths as was an over-dispersed Poisson model to the worm burden data. Graphidium strigosum was the most frequently identified species with an average prevalence of 78%. The mean prevalence and intensity of Graphidium infection were significantly effected by sampling year. The lower than normal rainfall recorded at the Tarn during the years 1995 and 1996 may have be one reason for this pattern. The worm burden of G. strigosum was significantly positively associated with rabbit body weight. The intensity of infection with P. ambiguus was significantly higher in female rabbits. There was a significant non-linear relationship between P. ambiguus worm burden and rabbit weight (P = 0.002) with worm burdens being highest in the 1000 g to 1499 g weight cohort. Trichostrongylus retortaeformis was only identified in 1994 and male rabbits harboured significantly higher worm burdens than females (48 vs. 7, P = 0.022). Over the five years, the average Taenia pisiformis prevalence was 31% and there was a significant positive association between worm burden and rabbit weight (P = 0.001). Cittotaenia pectinata had a prevalence of 37% over the whole study period with no interactions between prevalence or intensity and body weight, year of sampling or rabbit sex. All five helminths showed an overdispersed distribution with k values less than 1.     

Factors affecting the distribution of some Phryganeaeid (Trichoptera) in Malham Tarn, Yorkshire

This paper describes a distribution problem involving Agrypnetes crassicornis and Phryganea obsoleta (Trichoptera : Phryganeidae) in Malham Tarn, Yorkshire. The only suitable habitat for their larvae is the offshore vegetation, chiefly Chara delicatula, but owing to the specialized egglaying behaviour of this family and the absence of other sites, the eggs of Agrypnetes crassicornis are laid on the exposed rocky shoreline. The situation with Phryganea obsoleta differs in that the emergence of Potamogeton spp. provides new oviposition sites away from the shore. Investigations on both species however have provided further support for an hypothesis which postulates the importance of wind-induced water movements in rapidly dispersing newly hatched insect larvae to the favourable habitats in deep water.     

Hybridization and ecology of Geum rivale L. and Geum urbanum L. (Rosaceae) at Malham Tarn, Yorkshire

Geum urbanum L. (Rosaceae) at Malham Tarn, Yorkshire. A large population of Geum rivale, G. urbanum and their hybrids at Malham Tarn, Yorkshire were examined morphometrically. Principal components analysis and cluster analysis of various floral and vegetative characters scored from 203 individuals completely separated the parent species. A few hybrids were grouped with G. urbanum , and some were grouped separately from either parent species, but many others were grouped with G. rivale. This confirmed subjective visual examination of the population, which suggested that while hybrids remained distinct from G. urbanum , the delimitation of hybrids from G. rivale was difficult and not practical. Measurements of soil water content and of transmitted photosynthetically active radiation (PAR) indicated that the habitat range of G. urbanum at Malham Tarn was limited to well-drained shady sites, while G. rivale occurred in sites with a very varied degree of shading and soil water content. Hybrids were most frequent and most variable in the well-drained and heavily shaded 'urbanum-type' habitats. Hybrids very similar to G. rivale were found in waterlogged sites, but in unshaded sites only G. rivale occurred, with little evidence of hybridization. The availability of intermediate 'hybrid' habitats was not a major factor in determining the pattern of morphological variation in the hybrid population, and a number of alternative hypotheses are suggested.     

Seasonal dynamics of phytoplankton and phytobenthos,and associated chemical interactions,in a shallow upland lake (Malham Tarn,northern England)

Seasonal changes of phytoplankton were followed over 3 years (1985–87) in a shallow, unstratified and calcareous upland lake.The phytoplankton was of low to moderate abundance and generally dominated by phytoflagellates. Seasonality involved a winter minimum of abundance, a spring maximum of diatoms, and often brief increases in summer that included blue-greens, especially the colonial Gloeotrichia echinulata. Some components were of benthic origin. Seasonal growth of the main component of the phytobenthos, Chara globularisvar. virgata, caused a regular summer depletion in lake water of Ca²⁺ and HCO₃ ^- (alkalinity) by associated CaCO₃ deposition, and a more extreme (and unusual) depletion of K⁺. Chemical analysis of Chara biomass and of underlying sediments indicated a large benthic nutrient stock, much surpassing that represented by the phytoplankton. Growth in this biomass, and the magnitude of water-borne inputs, influenced the removals of Ca²⁺, K⁺ and inorganic N. The phytoplankton was probably limited by a low-P medium, to which co-precipitation of phosphate with CaCO₃ may have contributed. A vernal depletion of Si was probably limiting to diatom growth, and appeared to be mainly induced by benthic rather than planktonic diatoms. Examples of long-term change in composition of the phytoplankton and phytobenthos are noted and discussed in relation to the interaction of these components, nutrient enrichment, and possible alternative stable states.     

Stable carbon and oxygen isotopic compositions of recent charophyte oosporangia and water from Malham Tarn,U.K.: palaeontological implications

Charophyte oosporangia and water samples from a highly calcareous lake were measured for stable carbon and oxygen isotopic composition. The time period over which the oosporangia calcify is short, thus any biochemical relationship between the water and oosporangia"s calcite represents only one time window (late Summer in Malham Tam). This important temporal restraint must also apply to interpretations of all fossil material measured. The ¹⁸O_c of the charophyte oosporangia is deduced to be in equilibrium with the ¹⁸O of the water for a given temperature. The ¹³ C_c of the charophyte oosporangia was approximately 2.5 per mil lower than the ¹³C_DIC in the water we measured. With the release Of CO₂ with phosphoric acid from the charophyte oosporangia, there was no significant difference in the ¹⁸O_c values obtained, regardless of whether or not the carbonate was separated from the organic center, however ¹³C_c values were marginally lower for carbonate plus organic center measurements. Our results indicate that fossil charophyte gyrogonites can be used to elucidate the geochemistry of the ancient water body in which they lived.     

Endosymbiotic associations within protists

The establishment of an endosymbiotic relationship typically seems to be driven through complementation of the host''s limited metabolic capabilities by the biochemical versatility of the endosymbiont. The most significant examples of endosymbiosis are represented by the endosymbiotic acquisition of plastids and mitochondria, introducing photosynthesis and respiration to eukaryotes. However, there are numerous other endosymbioses that evolved more recently and repeatedly across the tree of life. Recent advances in genome sequencing technology have led to a better understanding of the physiological basis of many endosymbiotic associations. This review focuses on endosymbionts in protists (unicellular eukaryotes). Selected examples illustrate the incorporation of various new biochemical functions, such as photosynthesis, nitrogen fixation and recycling, and methanogenesis, into protist hosts by prokaryotic endosymbionts. Furthermore, photosynthetic eukaryotic endosymbionts display a great diversity of modes of integration into different protist hosts.In conclusion, endosymbiosis seems to represent a general evolutionary strategy of protists to acquire novel biochemical functions and is thus an important source of genetic innovation.     

Les industries moustériennes de la Rouquette (Puycelci, Tarn, France)

The open-air site la Rouquette, located at the foot of a cliff, was excavated by André Tavoso (1979-1988). The seven Mousterian archaeological levels are all in place, but of different richness. The sedimentological and faunal studies define a series of dates between isotopic stages 4 and 3, maybe even at the end of stage 5 for the lowest levels. The industrial complexes represent three broad types of “Bordian” facies, with technological, typological and lithological evolution. The industries from levels E to B display interesting evolutionary traits in so far as technological and typological behaviour are concerned, in a general Charentian Quina type Mousterian from the south of France continuum. After a “classical” facies in the “western” sense of the term (levels E to C), an atypical form of this facies (levels Bb and B) displays characteristics generally marked in the Quina Mousterian of the Grands Causses in more eastern or Mediterranean Quina Mousterians. Level Bb presents a Mousterian facies with a Ferrassie tendency, characterizing a short-term occupation. Level A contains a Mousterian defined as “non classical denticulates”, in which typical Mousterian and Charentian Mousterian influences are clearly marked.     

Histone-histone associations within chromatin. Cross-linking studies using tetranitromethane.

Treatment of chromatin with the protein cross-linker tetranitromethane (TNM) results in a product identified as an F2a1-F2b dimer. The same product appears after treatment with TNM of HeLa cells growing in culture. Furthermore acid-extracted histones which have been fractionated into the five separate species can be recombined and mixed with DNA to produce a nucleohistone preparation which is also cross-linked by TNM to give the F2a1-F2b dimer. F1 and F3 can be excluded from the reconstitution mixture without effect on the dimer production. In contrast, the presence of F2a2 is essential to the proper reconstitution of F2a1 and F2b with DNA. The specificity of TNM and the characteristics of the reaction suggest that F2a1 and F2b are cross-linked at their specific binding sites. These results provide evidence that F2a1, F2a2, and F2b interact specifically in chromatin.     

Different Genotypes of Anatoxin-Producing Cyanobacteria Coexist in the Tarn River, France

Repeated dog deaths occurred in 2002, 2003, and 2005 after the animals drank water from the shoreline of the Tarn River in southern France. Signs of intoxication indicated acute poisoning due to a neurotoxin. Floating scum and biofilms covering pebbles were collected in the summers of 2005 and 2006 from six different sites along 30 km from the border of this river. The cyanobacterial neurotoxic alkaloid anatoxin-a and/or its methyl homolog, homoanatoxin-a, was detected in the extracts of most samples examined by gas chromatography-mass spectrometry. Fifteen filamentous cyanobacteria of the order Oscillatoriales were isolated and displayed four distinct phenotypes based on morphological characteristics and pigmentation. Three of the phenotypes can be assigned to the genus Oscillatoria or Phormidium, depending on the taxonomic treatises (bacteriological/botanical) employed for identification. The fourth phenotype is typical of the genus Geitlerinema Anagnostidis 1989. Eight strains rendered axenic were analyzed for production of anatoxin-a and homoanatoxin-a, and all strains of Oscillatoria/Phormidium proved to be neurotoxic. The genetic relatedness of the new isolates was evaluated by comparison of the intergenic transcribed spacer sequences with those of six oscillatorian strains from the Pasteur Culture Collection of Cyanobacteria. These analyses showed that the neurotoxic representatives are composed of five different genotypes, three of which correspond to phenotypes isolated in this study. Our findings prove that neurotoxic oscillatorian cyanobacteria exist in the Tarn River and thus were most likely implicated in the reported dog poisonings. Furthermore, they reemphasize the importance of monitoring benthic cyanobacteria in aquatic environments to fully assess the health risks associated with these organisms.     

The record of deposition of radionuclides in the sediments of Ponsonby Tarn,Cumbria

A study has been made of the radionuclide content of sediments from Ponsonby Tarn in Cumbria to examine the pattern of deposition of radiocaesium and actinides upon the catchment. Sediment cores obtained from the tarn in 1986 were dated by core correlation and compared with results obtained from a previous study in 1980 (Eakins & Cambray, 1985).Sediments from the tarn contained actinides derived mainly from discharges to atmosphere. The 1986 cores contain greater quantities of weapons fallout derived caesium than may be accounted for by direct atmospheric input but less attributable to the Chernobyl accident than expected. Diatom analysis together with increased sediment accumulation rates post 1980 suggest that complex patterns of sedimentation have contributed to the changes evident in the sediment.     

Gastropod fauna of the Cameroonian coasts

 Eighteen species of gastropods were encountered living near and within the large coastal swamps, mangrove forests, intertidal flats and the rocky shore of the Cameroonian coast of the Atlantic Ocean. These represent members of the subclasses Neritimorpha, Caenogastropoda, and Heterostropha. Within the Neritimorpha, representatives of the genera Nerita, Neritina, and Neritilia could be distinguished by their radula anatomy and ecology. Within the Caenogastropoda, representatives of the families Potamididae with Tympano-tonos and Planaxidae with Angiola are characterized by their early ontogeny and ecology. The Pachymelaniidae are recognized as an independent group and are introduced as a new family within the Cerithioidea. Littorinimorpha with Littorina, Assiminea and Potamopyrgus as well as Neogastropoda (Thais) and Heterostropha (Melampus and Onchidium) are described and compared with representatives of the Caribbean and Indo-Pacific province. Received: 15 January 1999 / Accepted: 26 July 1999     

Gastropod nacre: structure, properties and growth--biological, chemical and physical basics

The biogenic polymer/mineral composite nacre is a non-brittle biological ceramic, which self-organizes in aqueous environment and under ambient conditions. It is therefore an important model for new sustainable materials. Its highly controlled structural organization of mineral and organic components at all scales down to the nano- and molecular scales is guided by organic molecules. These molecules then get incorporated into the material to be responsible for properties like fracture mechanics, beauty and corrosion resistance. We report here on structure, properties and growth of columnar (gastropod) nacre with emphasis on the genus Haliotis in contrast to sheet nacre of many bivalves.     

Macrophytic vegetation of the River Swale, Yorkshire

SUMMARY. An account is given of the distribution down the River Swale in summer 1976 of 132 species of photosynthetic plants which are recognizable macroscopically. Some environmental data are included. The river may be regarded as falling into three zones, both with regard to its physical features and its type of vegetation. The upper zone has rocky substrata, fast flows and a macrophytic vegetation largely of bryophytes; the middle zone has unconsolidated substrata and the macrophytic vegetation is relatively sparse; the lower zone is silted and the macrophytic vegetation consists largely of angiosperms. The flora of the Swale is compared with that of the Tees, since eventually the former is likely to receive water from the latter as part of a major water transfer scheme. Eleven species of 'river' angiosperm which are present in the Tees above the projected abstraction point are absent from the Swale above the inflow point.     

Observations and experiments on the phytoplankton of Blelham Tarn, English Lake District

Tubes composed of butyl rubber have been placed in a small English lake in an area where the water is 11-12 m deep. Each tube, when fully distended, contains over 18 000 m³ of water. The tubes are anchored to the shore and lake bottom. A boat can be rowed into them over a specially strengthened portion ofthe margin. The first was installed and its water isolated from that in the lake by the end of July 1970 and the second tube at the beginning of October 1970. The installation, maintenance, and performance of the tubes are described; as are suggested improvements. The temperature regime in the tubes closely follows that in the lake. If the chemical conditions are favourable, the seasonal cycle of Melosira in a tube is similar to that n i the lake. Contamination of the water in the tubes by that in the lake is slight and has a negligible effect on chemical conditions within them. Water can be lost from the tubes under certain conditions. The reverse does not happen. The phytoplankton communities in the tubes are similar in quality to those ofthe lake, even after 2-5 years of separation. The evidence suggests that the tubes are suitable for investigations on certain factors determining the abundance and seasonal cycles of algae in lakes and for other limnological studies.     

Evolutionary affiliations within the superfamily of ketosynthases reflect complex pathway associations

Abstract Type I polyketide synthases are known to produce a wide range of medically and industrially important polyketides. The ketosynthase (KS) domain is required for the condensation of an extender unit onto the growing polyketide chain during polyketide biosynthesis. KSs represent a superfamily of complex biosynthetic pathway-associated enzymes found in prokaryotes, fungi, and plants. Although themselves functionally conserved, KSs are involved in the production of a structurally diverse range of metabolites. Degenerate oligonucleotide primers, designed for the amplification of KS domains, amplified KS domains from a range of organisms including cyanobacterial and dinoflagellates. KS domains detected in dinoflagellate cultures appear to have been amplified from the less than 3-μm filtrate of the nonaxenic culture. Phylogenetic analysis of sequences obtained during this study enabled the specific identification of KS domains of hybrid or mixed polyketide synthase/peptide synthetase complexes, required for the condensation of an extender unit onto an amino acid starter unit. The primer sets described in this study were also used for the detection of novel KS domains directly from environmental samples. The ability to predict function based on primary molecular structure will be critical for future discovery and rational engineering of polyketides.