The phylogeny of Myxosporea (Myxozoa) based on small subunit ribosomal RNA gene analysis

The phylogeny of the Myxosporea was studied using the small-subunit ribosomal RNA gene sequences. Maximum parsimony and Bayesian inference were used to determine myxosporean phylogenetic relationships. The analysis included 120 myxosporean sequences retrieved from GenBank and 21 newly obtained sequences of myxosporeans representing nine genera. Members of the genera Palliatus and Auerbachia were sequenced for the first time. The phylogenetic analysis supported a split of myxosporeans into two main lineages separating most of freshwater species from marine ones as described by previous authors. In addition to the two main lineages, a third lineage consisting of three species was found (Sphaerospora truttae, Sphaerospora elegans and Leptotheca ranae) and additional exceptions to the marine/freshwater myxosporean split were recognised (Sphaeromyxa hellandi, Sphaeromyxa longa and Myxidium coryphaenoideum). All three myxosporean lineages were characterised by specific lengths of SSU rDNA sequences. The lineage of marine myxosporeans split into five well-defined clades. They consisted of species with a similar site of infection and spore morphology and were referred as the Parvicapsula clade, the Enteromyxum clade, the Ceratomyxa clade, the marine Myxidium clade and the Kudoa clade, respectively. The inner topology of the freshwater clade was more complex but the trend to branch according to site of infection was observed in this clade as well. Due to the number of sequences available, a histozoic (Myxobolus clade) predominated. Interestingly, five morphologically different species infecting urinary bladder clustered within the histozoic (Myxobolus) clade. The phylogenetic trees derived from this study differ in a number of respects from the current taxonomy of the myxosporeans, which suggests that several currently utilised characters may be homoplasious or that reliance on a single gene tree may not adequately reflect the phylogeny of the group.     

Reevaluating the classification of Halobacteroides and Haloanaerobacter species based on sequence comparisons of the 16S ribosomal RNA gene

Abstract The 16S rRNA gene (rDNA) sequence analysis of four halophilic anaerobes: Halobacteroides halobius, H. lacunaris, Haloanaerobacter (Hb.) chitinovorans and H. acetoethylicus confirmed that they were all members of the family Haloanaerobiaceae. H. lacunaris and H. halobius were found to be more closely related to each other and were distantly related to Sporohalobacter lortetti and the members of the genera Haloanaerobium and Halothermothrix . These data are in agreement with their assignment to the genus Halobacteroides . Further analysis indicated that Hb. chitinovorans was closely affiliated to members of the genus Halobacteroides , and therefore we propose to transfer it to the genus Halobacteroides as H. chitinovorans comb. nov. This transfer would invalidate the genus Haloanaerobacter , as Hb. chitinovorans is the only member of this genus. The 16S rDNA sequence analysis of H. acetoethylicum indicated that it was very closely related to members of the genus Haloanaerobium , viz. Haloanaerobium (Ha.) praevalens, Ha. salsugo , and Ha. alcaliphilum , and hence we propose to transfer it to the genus Haloanaerobium as Ha. acetoethylicus comb. nov.     

Phenotype variability of identical genotypes: the need for a combined approach in cyanobacterial taxonomy demonstrated on Merismopedia-like isolates

Five Merismopedia-like cyanobacterial strains were collected from microbial mats at Norderney Island, subcultured in the laboratory, and finally grown as unicyanobacterial cultures. As a sixth strain, Merismopedia glauca from the ?Sammlung von Algenkulturen“ at Göttingen (SAG) was used for comparisons. According to morphological and physiological characteristics initially observed in the field and during initial subculturing, the five strains were assigned to the species Merismopedia glauca, Merismopedia punctata, or Merismopedia elegans. However, after prolonged maintenance under laboratory conditions, the formation of platelet-like colonies stopped, whereas cell sizes, production of extracellular polymeric substances, and division patterns were stably maintained. These physiological and morphological parameters allowed us to divide the six strains into two clusters. This division was further supported by the profiling of total cell protein and phycobilisomes using SDS-PAGE. The nearly complete 16S rDNA sequence of three of the six isolates was determined. The comparative sequencing analysis revealed an almost 100% identity of these three Merismopedia-like strains. The evolutionary distance dendrogram constructed placed this Merismopedia cluster into a common line of descent with Synechocystis sp. strain PCC6906. Based on the analysis of common stretches of 1,050 nucleotides, the overall similarity between the sequence types of ?Merismopedia“ and ?Synechocystis“ is 96–97%. The values of the different methods for taxonomic classification of unicyanobacterial strains, the relationship of the cyanobacterial genera Merismopedia, Synechococcus, Synechocystis, and Eucapsis sp., and the functional role of different Merismopedia morphologies within microbial mats are discussed. It is suggested that all analyzed Merismopedia strains be combined into one species, namely Merismopedia punctata Meyen (1839).     

Superoxide dismutase production by Isaria fumosorosea on metals and its role in stress tolerance and fungal virulence

Superoxide dismutase (SOD) is an anti-oxidant enzyme which also plays a role in fungal virulence. The present study was conducted to elucidate its role in fungal infection and stress tolerance of entomopathogenic fungi, Isaria fumosorosea. SOD activity of I. fumosorosea conidia differed significantly on the growth medium supplemented with different metal compounds. The use of Cu + Zn proved to be the most active inducer of SOD activity. Cu + Zn treatment enhanced the fungal tolerance to oxidative stress generated by menadione in the medium (0–3 mM) as evaluated by colony growth. The conidial tolerance to UV-B radiation and heat was evaluated by assays of spore germination. Conidia produced on cultures with Cu + Zn were more tolerant to UV-B and thermal stress as well as exhibiting a higher rate of virulence against P. xylostella larvae. Our study highlights that SOD contributes significantly to the virulence and stress tolerance of I. fumosorosea and reveals possible means to improving field persistence and efficacy of a fungal formulation by manipulating the antioxidant enzymes of fungal pathogens.     

Inhibitory effects of superoxide dismutase 3 on IgE production in B cells

Immunoglobulin E (IgE) functions as a first-line defense against parasitic infections. However, aberrant production of IgE is known to be associated with various life-threatening allergic diseases. Superoxide dismutase 3 (SOD3) has been found to suppress IgE in various allergic diseases such as allergic conjunctivitis, ovalbumin-induced allergic asthma, and dust mite-induced atopic dermatitis-like skin inflammation. However, the role of SOD3 in the regulation of IgE production in B cells remains elusive. In this study, we investigated the effect of SOD3 on LPS/IL-4 and anti-CD40/IL-4-mediated secretion of IgE in murine B cells. Our data showed that SOD3 can suppress both LPS/IL-4 and antiCD40/IL-7-induced IgE secretion in B cells isolated from both wild-type (SOD3^+/+) and SOD3 knock-out (SOD3^?/?) mice. Interestingly, B cells isolated from SOD3^?/? mice showed higher secretion of IgE, whereas, the use of DETCA, a known inhibitor of SOD3 activity, reversed the inhibitory effect of SOD3 on IgE production. Similarly, SOD3 was found to reduce the proliferation, IgE isotype switch, ROS level, and CCL17 and CCL22 productions in B cells. Furthermore, SOD3 was found to suppress both LPS/IL-4 and anti-CD40/IL-4-mediated activation of downstream signaling such as JAK1/JAK3, STAT6, NF-κB, p38, and JNK in B cells. Taken together, our data showed that SOD3 can be used as an alternative therapy to restrict IgE-mediated allergic diseases.     

Heavy metal pollution improves allelopathic effects of Canada goldenrod on lettuce germination

• Large amounts of heavy metals have been released into the environment. Thus, the allelopathic effects of invasive alien species on the germination performance of co-occurring indigenous species may be altered or even heightened with the rapid growth in heavy metal pollution.
• This study evaluated the impacts of Canada goldenrod (Solidago canadensis L.) leaf extracts at concentrations of 0, 10 or 20 gl 1 on the germination of lettuce under different forms of heavy metal pollution (Cu²⁺, Pb²⁺ or a combination of Cu²⁺ and Pb²⁺; 35 mgl 1) during incubation in Petri dishes for 10 days.
• Goldenrod leaf extracts (high concentration) reduced growth of aboveground and belowground parts of lettuce as well as competition for light and soil nutrients. However, low concentrations of goldenrod leaf extracts dramatically improved growth of lettuce roots, competition for light, soil nutrient availability, leaf photosynthetic area and growth competitiveness. The combination of goldenrod leaf extracts and heavy metal pollution was synergistic on most lettuce germination parameters, probably because high concentrations of goldenrod leaf extracts together with heavy metal pollution had a synergistic negative impact on lettuce germination.
• Consequently, increased levels of heavy metal pollution may favour invasion of invasive alien species while largely suppressing germination of indigenous species.

     

Morphology, toxin composition and LSU rDNA phylogeny of Alexandrium minutum (Dinophyceae) from Denmark, with some morphological observations on other European strains

The morphology of Alexandrium minutum Halim from Denmark was studied and compared to the morphology of material from Portugal, Spain, France and Ireland. Strains from Denmark and the French coast of the English Channel differed from the typical minutum morphotype by the absence of a ventral pore. Cells without a pore also dominated field material from Ireland but a small fraction (6%) did have a pore. Many cells had a heavily areolated theca. In the exponential growth phase, the PSP-toxin profile of the Danish strain of A. minutum was dominated by C1 and C2 (up to 70%), whereas GTX2 and 3 made up more than 17%, and STX almost 13%. Cells entering the stationary phase contained 30% STX with a concomitant decrease of the other toxins. Partial large subunit rDNA sequences (664 bp) confirmed that the Danish A. minutum strain clusters together with other European strains of this species, and a strain from Australia. However, sequencing of this part of the gene did not resolve intraspecific relationships and could not differentiate populations with or without pore and/ or different toxin signatures. A strain from New Zealand had a remarkably high sequence divergence (up to 6%) compared to the other strains of A. minutum and its identity should be further investigated. A distribution map of A. minutum has been compiled and it is suggested that A. minutum and A. angustitabulatum Taylor are conspecific.     

A comparative study of the effects of laser and light-emitting diode radiation on superoxide dismutase activity and nitric oxide production in rat wound fluid

The effect of laser and light-emitting diode radiation in the visible region of the spectrum on the content of reactive nitrogen species and superoxide dismutase activity in rat wound fluid was studied. The efficiency of action of coherent laser radiation and incoherent light-emitting diode radiation in the red region of the spectrum on the parameters analyzed was compared. The study was performed using the model of cut aseptic wounds proposed by L.I. Slutskii. A He-Ne laser (632 nm) or an U-332B light-emitting diode (630 nm) was used as the source of radiation. It was shown that (1) exposure of wounds to visible light of both laser and light-emitting diode causes dose-dependent changes in superoxide dismutase activity and nitrite production and that (2) radiation coherence does not play a significant role in the changes in superoxide dismutase activity or nitric oxide production by wound fluid phagocytes.     

河南南阳不同生境土壤重金属含量及其对拟水狼蛛生物学特性的影响

为了探明重金属含量对拟水狼蛛Pirata subpiraticus生物学特性的影响, 本研究于2008年7月在河南南阳地区5种不同生境下, 共采集50份土壤样本和150头拟水狼蛛样本, 采用原子吸收光谱法测定了5种不同生境下雌拟水狼蛛体内重金属含量, 并测定了雌蛛头胸甲宽、体重、卵袋重量、卵数目和卵体积等生物学指标。结果表明：不同样点拟水狼蛛重金属含量与土壤重金属含量显著正相关, 4个重金属污染区与宝天曼自然保护区（Baotianman, BTM）拟水狼蛛体内Cd、Cu和Zn的含量差异极显著(P<0.001), 桐柏铜矿（Tongbai Tongkuang, TBTK）和南阳油田(Nanyang Youtian, NYYT) 的Pb含量与BTM的差异极显著(P<0.001), 主成分分析表明Cd、Cu和Zn是反应重金属污染的主要指标。在重金属胁迫下, 4个重金属污染区与保护区的拟水狼蛛头胸甲宽、雌体重量、卵袋重量、卵数目和卵体积差异均达到极显著（P<0.001）或显著水平（P<0.05）, 主成分分析表明背胸甲宽、卵袋重量和卵体积是重要生物学指标。 拟水狼蛛的背胸甲宽、卵袋重量和卵的体积与重金属含量显著相关, 重金属含量高的地方拟水狼蛛背胸甲宽较小, 雌性体重、卵袋重量和卵数目较小, 卵的体积大, 因此说明拟水狼蛛处在逆环境中时, 动物为保持总的繁殖力不变的前提下, 后代个体的大小与数目间满足某种平衡, 即达到协同进化的目的, 拟水狼蛛可以作为重金属污染的监测指示生物。