Herberta borealis,a new species from Scotland and Norway

Abstract

The reproduction of Pohlia nutans (Hedw.) Lindb. and Pleurozium schreberi (Brid.) Mitt. were compared in the surroundings of copper smelters at Harjavalta, Finland. Samples of both species were collected from 16 sample plots, which were situated on a 12-km transect at intervals of half a kilometre from the smelters. As a result of pollution the production of gametangia decreased in P. schreberi, and near the smelters most of the shoots were sterile. The biomass of shoots seems to have an effect on the production of perichaetia; reproducing females were always the largest ones in the colonies. The reproductive strategy of Pohlia nutans also varied. While, in moderately clean areas, colonies reproduced sexually and formed sporophytes, in the vicinity of the smelters caducous shoot apices were produced. The numbers of sporophytes in colonies were highest in moderately polluted areas and decreased further away from the smelters. The numbers of spores per capsule in P. nutans decreased at polluted sites and the proportion of aborted spores increased.     

Kohninia linnaeicola, a new genus and species of the Sclerotiniaceae pathogenic to Linnaea borealis

A new genus and species is described to accommodate a newly discovered fungus pathogenic to Linnaea borealis. The fungus forms true sclerotia on stems and leaves of its host and apothecia arise singly or gregariously on the surface of ripe sclerotia. The new fungus was collected together with a stromatic conidiomal fungus that occurred on the same host. A putative teleomorph-anamorph connection of the observed taxa was ruled out by sequence comparison of the nuclear ribosomal internal transcribed spacer DNA sequences (ITS rDNA). Based on morphology and pathogenicity, the new fungus belongs in the family Sclerotiniaceae, Helotiales, Ascomycota. A phylogenetic analysis of ITS rDNA sequences from 26 taxa of the family Sclerotiniaceae was performed to conclude on the systematic position of the new fungus. The small tuberoid sclerotia, brownish subsessile to substipitate apothecia, four-spored asci, ellipsoid to isthmoid ascospores, inability to grow on PDA culture media and a number of ITS rDNA sequence autapomorphies characterize and distinguish the fungus from other taxa of the Sclerotiniaceae.     

Phytophthora borealis and Phytophthora riparia, new species in Phytophthora ITS Clade 6

Phytophthora borealis and Phytophthora riparia, identified in recent Phytophthora surveys of forest streams in Oregon, California and Alaska, are described as new species in Phytophthora ITS Clade 6. They are similar in growth form and morphology to P. gonapodyides and are predominantly sterile. They present unique DNA sequences, however, and differ in temperature/growth relations and geographic distribution.     

Speciation in the large-spored Metschnikowia clade and establishment of a new species, Metschnikowia borealis comb. nov

The reproductive boundaries among species in the large-spored Metschnikowia clade were studied by prototrophic recombinant selection, electrophoretic karyotyping, mitochondrial DNA restriction analysis, and DNA sequence analysis. Inviable ascospores arose from crosses between the two varieties of Metschnikowia continentalis, indicating that they should be recognized as separate species. Prototrophic recombinants were recovered from crosses between auxotrophic mutants of Metschnikowia borealis, M. continentalis, Metschnikowia lochheadii, Metschnikowia sp. UWO(PS)00-154.1, and Candida ipomoeae, showing that some genetic exchange is possible in spite of the sterility of the asci formed in interspecific crosses. Metschnikowia hawaiiensis, although capable of ascus formation when its h(-) mating type is crossed with the h(+) mating type of the other species, did not give rise to recombinants. In the other species, some recombinants acquired the ability to form asci directly from single cells. These often contained the chromosomes of both parents, suggesting formation of allodiploid hybrids. Other recombinants behaved as haploids and were similar to one parent except for having inherited the selectable wild-type allele from the other parent. In most, but not all cases, inheritance of the mitochondrial genome was uniparental and correlated with the inheritance of the nuclear chromosome complement. In some cases, what appeared to be a recombinant mitochondrial genome was observed. Phylogenies derived from the sequences of various DNA regions were not congruent, indicating that hybridization may have taken place in nature as the large-spored species diverged from their common ancestor. Further evidence that C. ipomoeae arose from a natural recombination event was obtained, but a pair of Metschnikowia species that might represent derived forms of the parents could not be identified conclusively. C. ipomoeae and most of its closely related Metschnikowia species contained a group-II intron in the mitochondrial small-subunit ribosomal gene. The intron was absent in M. borealis, M. hawaiiensis, and other species in the genus Metschnikowia.     

Experimental analysis of lens-forming capacity in Xenopus borealis larvae

Previously, the only anuran amphibians known to have the capacity to regenerate a lens after lentectomy were Xenopus laevis and Xenopus tropicalis. This regeneration process occurs during the larval life through transdifferentiation of the outer cornea promoted by inductive factors produced by the retina and accumulated inside the vitreous chamber. However, the capacity of X. tropicalis to regenerate a lens is much lower than that of X. laevis. This study demonstrates that Xenopus borealis, a species more closely related to X. laevis than to X. tropicalis, is not able to regenerate a lens after lentectomy. Nevertheless, some morphological modifications corresponding to the first stages of lens regeneration in X. laevis were observed in the outer cornea of X. borealis. This suggested that in X borealis the regeneration process was blocked at early stages. Results from histological analysis of X. borealis and X. laevis lentectomized eyes and from implantation of outer cornea fragments into the vitreous and anterior chambers demonstrated that: (i) in X. borealis eye, the lens-forming competence in the outer cornea and inductive factors in the vitreous chamber are both present, (ii) no inhibiting factors are present in the anterior chamber, the environment where lens regeneration begins, (iii) the inability of X. borealis to regenerate a lens after lentectomy is due to an inhibiting action exerted by the inner cornea on the spreading of the retinal factor from the vitreous chamber towards the outer cornea. This mechanical inhibition is assured by two distinctive features of X. borealis eye in comparison with X. laevis eye: (i) a weaker and slower response to the retinal inducer by the outer cornea; (ii) a stronger and faster healing of the inner cornea. Unlike X. tropicalis and similar to X. laevis, in X. borealis the competence to respond to the retinal factor is not restricted to the corneal epithelium but also extends to the pericorneal epidermis.     

Effects of inorganic mercury on the respiration and the swimming activity of shrimp larvae,Pandalus borealis

In order to test the sensitivity of respiration (physiological and potential) to mercury (Hg) contamination, larval shrimp Pandalus borealis were exposed to inorganic Hg (0–160 ppb) for 27 h in the laboratory. Oxygen consumption rates (RO₂), potential respiration (determined by respiratory electron transfer system activity, ETSA), protein content, and swimming activity for zoeae III and zoeae V stages were measured. For both zoeae stages, ETSA and protein content remained constant after 27 h exposure to 160 ppb Hg whereas RO₂ and swimming activity decreased. This study revealed the impact of different Hg levels and different exposure times on RO₂ of shrimp larvae. After 10 h exposure to 160 ppb Hg, the RO₂ decreased by 43 and 49% in zoeae III and zoeae V stages, respectively. Exposure time of 27 h to 80 ppb Hg and higher, induced paralysis in nearly 100% larvae. Surprisingly, the paralysed larvae displayed almost 50% of the control's RO₂. The results showed that Hg disturbs a part of the respiration process without modifying the maximum activity of the enzymes involved in the ETSA assay. Therefore, the ETSA assay can not be used as a sublethal bioanalytic probe to detect Hg in short-term exposures. The decline of the RO₂/ETSA ratios reported here, indicates an inability of contaminated larvae to adapt their metabolism to physiological stress caused by Hg.     

Klastostachys, a new genus of Harpellales in Chironomidae larvae

Klastostachys reflexa, a new genus and species combination in the Harpellales, is established herein based on Stachylina reflexa, which was described in 1988. This gut fungus was found attached to the peritrophic matrix of small bloodworms, Cryptochironomus sp. (Chironomidae), in the Rocky Mountains of Colorado, USA. Klastostachys resembles Stachylina, a genus common in Chironomidae, but the unbranched thalli of Klastostachys disarticulate and disperse with the trichospores remaining attached to their generative cells. This manner of dissemination is unusual among Harpellales, being noted also for Carouxella spp., but members of that genus have zygospores attached at one pole to the zygosporophore (Type IV), whereas Klastostachys zygospores are medially attached to the zygosporophore at right angles (Type I).     

Dacryodiomyces, a new genus of Harpellales in Chironomidae larvae

A new genus of gut fungus in the Harpellales (Trichomycetes) with the type species Dacryodiomyces oklahomensis, found in Chironomidae larvae, is described from northeastern Oklahoma, USA. The most distinguishing characters are the elongate-ovoid zygospores attached to their zygosporophore at one end (Type IV), together with trichospores bearing a collar and a single appendage.     

一株寄生蛴螬的被毛孢新种

【目的】对寄生鞘翅目幼虫蛴螬的虫生真菌标本GZUIFR-lgs-1进行描述和鉴定。【方法】基于形态特征比较结合系统发育分析进行鉴定。【结果】该种通过形态特征产孢细胞单生,透明,多数与营养菌丝成近直角,基部具疣且明显膨大(19-27)μm×(2.7-3.6)μm,颈部长(12.0-14.5)μm,顶端呈螺旋状扭曲,偶有再育;分生孢子透明、光滑,橘瓣状,单生或偶有双生,外具黏液,大小为(4.8-6.0)μm×(2.4-3.6)μm,而与被毛孢属已知种相区别。基于ITS位点的系统发育分析支持形态学鉴定的结果。【结论】综合形态特征比较及系统发育分析结果,该种为被毛孢属的一个新的分类单元,命名为雷公山被毛孢,Hirsutella leigongshanensis。     

Survival of Heleomyza borealis (Diptera, Heleomyzidae) larvae down to − 60°C

Heleomyza borealis Boh. (Diptera, Heleomyzidae) overwinters as larvae in Arctic habitats, where they may experience winter temperatures below ? 15°C. The larvae freeze at c.? 7°C but in acclimation experiments 80% survived when exposed to ? 60°C. Of the larvae exposed to between ? 4 and ? 15°C, only 3% pupated. However, when cooled to ? 20°C this increased to 44%, with 4% emerging as adults. Larvae maintained at 5°C contained low levels of glycerol, sorbitol and trehalose, which did not increase with acclimation to low temperatures. However, levels of fructose increased from 6.1 μg mg^?1 fw in control animals to 17 μg mg^?1 fw when exposed to ? 2°C for 1 week. Larval body water (2.2 ± 0.1 g/g dw, mean ± SD, n = 100) and lipid content (0.22 ± 0.002 g/g fw, mean ± SE) showed no significant change during acclimation to low temperatures. Larvae maintained at a constant 5°C survived for over 18 months with little loss of body mass (from 7.5 ± 1.2 to 7.0 ± 1.2 mg fw, mean ± SD, n = 20), but none pupated. Heleomyza borealis larvae appear to feed and grow until they reach a body mass of about 7.5 mg and then become dormant. They remain in this state until they experience a low temperature stimulus (< ? 15°C) followed by a warm period (≈ 5°C). This ensures that the larvae pupate and adults emerge in early summer, allowing the maximum growing period before the following winter. Heleomyza borealis are adapted to survive long winters in a dormant larval state. They have a low metabolic rate, can conserve body water even at subzero temperatures but do not synthesize large quantities of cryoprotectants.     

Archaeorhizomyces borealis sp. nov. and a sequence-based classification of related soil fungal species

The class Archaeorhizomycetes (Taphrinomycotina, Ascomycota) was introduced to accommodate an ancient lineage of soil-inhabiting fungi found in association with plant roots. Based on environmental sequencing data Archaeorhizomycetes may comprise a significant proportion of the total fungal community in soils. Yet the only species described and cultivated in this class is Archaeorhizomyces finlayi. In this paper, we describe a second species from a pure culture, Archaeorhizomyces borealis NS99-600^T (=CBS138755^ExT) based on morphological, physiological, and multi-locus molecular characterization. Archaeorhizomyces borealis was isolated from a root tip of a Pinus sylvestris seedling grown in a forest nursery in Lithuania. Analysis of Archaeorhizomycete species from environmental samples shows that it has a Eurasian distribution and is the most commonly observed species. Archaeorhizomyces borealis shows slow growth in culture and forms yellowish creamy colonies, characteristics that distinguish A. borealis from its closest relative A. finlayi. Here we also propose a sequence-based taxonomic classification of Archaeorhizomycetes and predict that approximately 500 species in this class remain to be isolated and described.