Description of Pyramimonas diskoicola sp. nov. and the importance of the flagellate Pyramimonas (Prasinophyceae) in Greenland sea ice during the winter–spring transition

Pyramimonas Schmarda is a genus of unicellular green flagellates, recorded in marine water and sea ice samples. Pyramimonas is within the prey size range of the most important protozoan grazers in Disko Bay, West Greenland, where this study took place. Despite the potential ecological importance, little is known about the occurrence of the genus. The aim of this study was to explore the biomass of Pyramimonas in developing stages of sea ice and in the water column. Pyramimonas colonized the early stages of sea ice, and the highest percent of Pyramimonas biomass was found in grease ice. The biomass of Pyramimonas was more than a magnitude higher within sea ice compared to the surface water. The results illustrate that Pyramimonas from the ice is an important contributor to the plankton community prior to the spring bloom. An undescribed species, Pyramimonas diskoicola sp. nov., was found. Based on morphology and ultrastructure, combined with molecular phylogeny inferred from the small-subunit SSU rDNA and the large-subunit chloroplast-encoded rbcL, the species was placed in subgenus Vestigifera. The cells possessed four flagella, measured 8.3 ± 2.6 μm in length and 5.1 ± 0.8 μm in width, and were characterized by an uplifted quadrant in the center of the box scales, not seen at any other Pyramimonas species. The phylogenetic analyses indicated P. diskoicola to be closely related to other polar sea ice species of Pyramimonas.     

Summer eczema in exported Icelandic horses: influence of environmental and genetic factors

A cross sectional study was designed to estimate the prevalence of summer eczema (a chronic, recurrent seasonal dermatitis) in exported Icelandic horses and the influence of environmental and genetic factors on the development of the disease.     

Occurrence of haemolytic Mannheimia spp. in apparently healthy sheep in Norway

Background  

The occurrence of Mannheimia species in healthy sheep has only been investigated to a very limited extend since the genus and its five named species were established. The aim of the present study was to evaluate the occurrence of haemolytic Mannheimia species in apparently healthy sheep originating from four sheep flocks in South-Western Norway.     

Phylogenetic relationships of species of Crenicichla (Teleostei: Cichlidae) from southern South America based on the mitochondrial cytochrome b gene

Phylogenetic analysis using Bayesian inference, likelihood and parsimony methods was conducted on 60 complete mitochondrial cytochrome b sequences from 21 species of Crenicichla, including all species known from Uruguay (Crenicichla celidochilus, Crenicichla lepidota Crenicichla minuano, Crenicichla missioneira, Crenicichla punctata, Crenicichla scottii, Crenicichla vittata), Crenicichla compressiceps, Crenicichla empheres, Crenicichla geayi, Crenicichla iguassuensis, Crenicichla macrophthalma, Crenicichla menezesi, Crenicichla notophthalmus, Crenicichla regani, Crenicichla cf. regani, Crenicichla semifasciata, Crenicichla sveni, Crenicichla tendybaguassu, two unidentified species, and also two species of Teleocichla. Bayesian analysis resulted in a trichotomy with three major groups: (1) The C. missioneira species group (C. celidochilus, C. empheres, C. minuano, C. missioneira, C. tendybaguassu, and an undescribed species analyzed); (2) a group of southern species (C. iguassuensis, C. punctata, C. scottii, C. vittata); and (3) a rather heterogeneous group comprising the type species C. macrophthalma, members of the Crenicichla reticulata species group (C. geayi, C. semifasciata), members of the Crenicichla wallacii species group (C. compressiceps, C. notophthalmus, C. regani, C. cf. regani), members of the Crenicichla saxatilis species group (C. lepidota, C. menezesi, C. sveni, C. sp.), and two species of Teleocichla. Parsimony jackknifing resulted in a quadritomy with: (1) C. macrophthalma, (2) Teleocichla, (3) the saxatilis + wallacii group species, and (4) the rest, which include C. geayi and C. semifasciata as sister group to a dichotomy with the C. missioneira group and the remaining southern species. The sequence variation within the C. missioneira group is remarkably minor despite considerable morphological differences, supporting the conclusion that it forms an endemic species flock in the Uruguay River basin. Previously proposed species groups within the speciose genus Crenicichla (more than 90 species known) are partly corroborated. However, C. celidochilus was not previously associated with the C. missioneira species group, and C. vittata has not previously been associated with C. scottii, C. iguassuensis, or C. punctata. Crenicichla lepidota, C. sveni, C. menezesi and C. sp. represent the C. saxatilis group. Species of small size, representing the C. wallacii species group and Teleocichla are characterized by very long branches, and the position of Teleocichla differed considerably between the Bayesian and parsimony trees. This finding does not invalidate Teleocichla but rather suggests that the several monophyletic major clades within Crenicichla may need nominal recognition. A putative hybrid specimen with a morphology combining components from C. vittata and C. scottii, but with a cytochrome b sequence from C. scottii was found in a sample from the Rio Quaraí/Cuareim. Another putative hybrid specimen with a unique morphology but a cytochrome b sequence agreeing with C. scottii was found in a sample from Maldonado, but no other Crenicichla species than C. scottii is known from that locality.     

Extraction of bioactive compounds from Alaria esculenta with pulsed electric field

Journal of Applied Phycology - There is a growing demand for bioactive compounds derived from green extraction methods from the food and cosmetic industries. Pulsed electric field (PEF)-assisted...     

Pseudomonas syringae isolated in lichens for the first time: Unveiling Peltigera genus as the exclusive host

Pseudomonas syringae is a bacterial complex that is widespread through a range of environments, typically associated with plants where it can be pathogenic, but also found in non-plant environments such as clouds, precipitation, and surface waters. Understanding its distribution within the environment, and the habitats it occupies, is important for examining its evolution and understanding behaviours. After a recent study found P. syringae living among a range of vascular plant species in Iceland, we questioned whether lichens could harbour P. syringae. Sixteen different species of lichens were sampled all over Iceland, but only one lichen genus, Peltigera, was found to consistently harbour P. syringae. Phylogenetic analyses of P. syringae from 10 sampling points where lichen, tracheophyte, and/or moss were simultaneously collected showed significant differences between sampling points, but not between different plants and lichens from the same point. Furthermore, while there were similarities in the P. syringae population in tracheophytes and Peltigera, the densities in Peltigera thalli were lower than in moss and tracheophyte samples. This discovery suggests P. syringae strains can localize and survive in organisms beyond higher plants, and thus reveals opportunities for studying their influence on P. syringae evolution.     

Migratory behaviour and survival rates of wild northern Atlantic salmon Salmo salar post‐smolts: effects of environmental factors

To study smolt behaviour and survival of a northern Atlantic salmon Salmo salar population during river descent, sea entry and fjord migration, 120 wild S. salar were tagged with acoustic tags and registered at four automatic listening station arrays in the mouth of the north Norwegian River Alta and throughout the Alta Fjord. An estimated 75% of the post‐smolts survived from the river mouth, through the estuary and the first 17 km of the fjord. Survival rates in the fjord varied with fork length (L_F), and ranged from 97·0 to 99·5% km^?1. On average, the post‐smolts spent 1·5 days (36 h, range 11–365 h) travelling from the river mouth to the last fjord array, 31 km from the river mouth. The migratory speed was slower (1·8 L_F s^?1) in the first 4 km after sea entry compared with the next 27 km (3·0 L_F s^?1). Post‐smolts entered the fjord more often during the high or ebbing tide (70%). There was no clear diurnal migration pattern within the river and fjord, but most of the post‐smolts entered the fjord at night (66%, 2000–0800 hours), despite the 24 h daylight at this latitude. The tidal cycle, wind‐induced currents and the smolts' own movements seemed to influence migratory speeds and routes in different parts of the fjord. A large variation in migration patterns, both in the river and fjord, might indicate that individuals in stochastic estuarine and marine environments are exposed to highly variable selection regimes, resulting in different responses to environmental factors on both temporal and spatial scales. Post‐smolts in the northern Alta Fjord had similar early marine survival rates to those observed previously in southern fjords; however, fjord residency in the north was shorter.     

Erbbiologischer Beitrag zum Nachweis der ektodermalen Herkunft des Musc. sphincter iridis

Ohne Zusammenfassung