The pH sensing receptor AopalH plays important roles in the nematophagous fungus Arthrobotrys oligospora

There is well-conserved PacC/Rim101 signaling among ascomycete fungi to mediate environmental pH sensing. For pathogenic fungi, this pathway not only enables fungi to grow over a wide pH range, but it also determines whether these fungi can successfully colonize and invade the targeted host. Within the pal/PacC pathway, palH is a putative ambient pH sensor with a seven-transmembrane domain. To characterize the function of a palH homolog, AopalH, in the nematophagous fungus Arthrobotrys oligospora, we knocked out the encoding gene of AopalH through homologous recombination, and the transformants exhibited slower growth rates, greater sensitivities to cationic and hyperoxidation stresses, as well as reduced conidiation and reduced trap formation, suggesting that the pH regulatory system has critical functions in nematophagous fungi. Our results provide novel insights into the mechanisms of pH response and regulation in fungi.     

Amyloid Fibrils Trigger the Release of Neutrophil Extracellular Traps (NETs), Causing Fibril Fragmentation by NET-associated Elastase

The accumulation of amyloid fibrils is a feature of amyloid diseases, where cell toxicity is due to soluble oligomeric species that precede fibril formation or are formed by fibril fragmentation, but the mechanism(s) of fragmentation is still unclear. Neutrophil-derived elastase and histones were found in amyloid deposits from patients with different systemic amyloidoses. Neutrophil extracellular traps (NETs) are key players in a death mechanism in which neutrophils release DNA traps decorated with proteins such as elastase and histones to entangle pathogens. Here, we asked whether NETs are triggered by amyloid fibrils, reasoning that because proteases are present in NETs, protease digestion of amyloid may generate soluble, cytotoxic species. We show that amyloid fibrils from three different sources (α-synuclein, Sup35, and transthyretin) induced NADPH oxidase-dependent NETs in vitro from human neutrophils. Surprisingly, NET-associated elastase digested amyloid fibrils into short species that were cytotoxic for BHK-21 and HepG2 cells. In tissue sections from patients with primary amyloidosis, we also observed the co-localization of NETs with amyloid deposits as well as with oligomers, which are probably derived from elastase-induced fibril degradation (amyloidolysis). These data reveal that release of NETs, so far described to be elicited by pathogens, can also be triggered by amyloid fibrils. Moreover, the involvement of NETs in amyloidoses might be crucial for the production of toxic species derived from fibril fragmentation.     

Settling flux and sinking velocity of Seston in Lago di Mergozzo (Northern Italy) and influence of microbial activity on the decomposition of entrapped organic material

Settling flux and velocity of seston, Particulate Organic Carbon (POC) and chlorophyll a were measured at three depths during 8 seven-day exposure periods in Lago di Mergozzo (Northern Italy). Sedimentation rates of seston varied from 250 to 1200 mg m^–2 d^–1 with a prevalence of the inorganic fraction (130–900 mg m^–2 d^–1) over the organic (160–320 mg m^–2 d^–1).The percentage of organic fraction inside the traps was always lower than outside. The comparison of preserved and unpreserved traps showed no significant difference in both organic matter content and bacterial numbers. We inferred from this result that bacterial activity in the traps did not cause a measurable POC loss during the seven day exposures. Therefore, the higher settling velocity of the inorganic particles was responsible for the higher percentage of this fraction in the traps. The settling velocity of sestonic particles increased, during the stratification period, with increasing depth and reached a maximum value of 2.5 m d^–1.     

不同微生物的单光束激光陷阱操纵

本文报导了分别采用Ｈｅ－Ｎｅ和Ａｒ＾＋激光器与光不显微镜构成的单光束激光陷阱操纵酵母菌、青霉等不同微生物的实验观察结果,讨论了操纵条件。研究表明：用单光束高会聚激光产生的梯度力操纵微生物体,其有效作用力的大小不仅与激光功率、波长、束腰半径和光束会聚角有关,还与微生物的大小、吸收系数、菌龄及培养方法等因素有关。     

Trap architecture in carnivorous Utricularia (Lentibulariaceae)

Within carnivorous plants, the bladderworts (Utricularia) possess the most complicated traps whose mechanisms are not yet completely understood. For the first time, a representative survey of different traps from both subgenera (Utricularia and Polypompholyx) is presented.

Based on scanning- and transmission electron microscopy, traps of 14 species of Utricularia (out of 215 species) representing 11 sections (out of 35 sections) and including all life forms (aquatic, epiphytic, and terrestrial) were investigated. Additionally, it was tested whether life forms correlate with trapping mechanisms. Most morphological and anatomical features of the traps vary considerably between the different life forms, e.g. position of trap and trap entrance as well as form and position of trap appendages. Morphological data support the basal position of subgenus Polypompholyx within the genus. Some characteristics of the traps of terrestrial Utricularia multifida (subgenus Polypompholyx) differ remarkably from traps of the other species, e.g. trap-door anatomy and trap walls. This might be an indication for a primordial (non-suction) trapping mechanism in the former species, similar to that of the eel-traps of the closely related genus Genlisea.     

Improvements to a passive trap for quantifying barnacle larval supply to semi-exposed rocky shores

Planktonic cyprid larvae of the intertidal barnacle, Semibalanus balanoides (L.) and the infralittoral/sublittoral Balanus crenatus Brug., are readily captured in small, chambered, passive traps deployed on rocky shores. Several structural developments of a previous trap design improved urea (killing solution) retention and capture of cyprids of both species. The design adopted for assessment of the larval supply/settlement relationship of the focal species, S. balanoides, included additional internal baffles and the replacement of the cylindrical trap opening with a coned aperture. Three sizes of cone aperture area were compared, with the intermediate size (1 cm²) being optimal for measuring larval supply over the full range of wave action on local shores. Most daily catches included larvae that were recognizable as having been dead before they were trapped, and had recently passed through the guts of grazing limpets (Patella vulgata L.). One site showed that ∼32% of trapped S. balanoides were so-called ‘faecal’ cyprids. An inability to distinguish these in trap samples would lead to a significant over-estimation of larval supply. Preliminary data indicated that S. balanoides larval supply to the intertidal is enhanced by onshore winds (or perhaps increased wave turbulence), whereas B. crenatus supply was positively correlated with offshore winds (or decreased turbulence). A clear ‘supply/settlement’ relationship for S. balanoides at six sites along ∼40 km of coastline was derived from 1 cm² coned trap catches and daily counts of settlement on ceramic tiles. There were no instances of disproportionately high settlement in relation to larval supply, but at five sites there were days when settlement apparently failed. The identification and explanation of settlement success and failure is fundamental to understanding the importance of larval supply in structuring marine benthic populations and communities.     

Dynamics of an enclosed population of pine mice,Microtus pinetorum

Enclosed populations of pine mice were studied over a 28-month period and compared with populations in surrounding natural areas. The enclosed populations reached densities far greater than any observed in surrounding natural areas. It is suggested that the restriction placed on dispersal by the enclosure walls and the addition of food in the form of trap bait could have allowed the enclosed populations to reach higher densities than normally observed at SRP.     

Assessment of a silhouette trap for sampling zoophilic blackflies (Diptera: Simuliidae)

A collapsible animal-type silhouette trap was designed to catch zoophilic female blackflies (Diptera: Simuliidae) which feed on the head or ventral surface of cattle. The trap was assessed for its ability to sample attacking blackflies by comparison with simultaneous manual catches from a bait cow, in an enzootic bovine onchocerciasis area in North Wales. In thirteen 1-hour collections, the trap provided a representative sample of the blackfly population in terms of the relative abundance of species. There was a strong correlation between the catch sizes from both methods (r = +0.73), and the body site feeding preferences for all species were similar with both trap and cow. There was no significant difference between the Onchocerca spp. infection rates of flies caught by either method.     

Population studies ofBrevicoryne brassicae (L.), its parasites and hyperparasites in England

Studies on populations of Brevicoryne brassicae (L.), its parasites and hyperparasites were carried out by actual counting in the sprouts field and by sticky and water traps. B. brassicae was found to be attacked by one primary parasite, Diaretiella rapae (McIntosh ), which in turn is parasitized by Alloxysta brassicae (Ashm. ),Asaphes vulgarisWalker ,A. suspensus (Nees ),Pachyneuron minutissimum (Förster ) and Dendrocerus carpenterii (Curtis ). The aphid population in the field was started by immigrant alates which were found flying too early to be synchronized with the sprouts plants. Similarly D. rapae was not synchronized with the aphids although many individuals could have been carried into a plot through parasitized immigrant alates, of which less than 30% were found parasitized. Because of high hyperparasitism (especially by A. brassicae)D. rapae was not able to maintain a high rate of parasitism to curb the aphid population growth. The maximum percentage mummies being 27.8%, while the maximum, percentage parasitism being 56.6% recorded only during the early 1974 season (mean=12.9%). The decline of aphid population from September onwards was largely due to the cold weather, Syrphid predation and occasionally fungal attack. The high rate of hyperparasitism by A. brassicae is attributed to its better synchronization with D. rapae. The mean percentage of parasite that emerged from mummies collected during 1973–74 were D. rapae 31.3%,A. brassicae 64.3%,A. vulgaris and A. suspensus 4.3%,D. carpenterii 0.2% and P. minutissimum 0.1%.