A new genus and two new species of melicharid mites (Acari: Mesostigmata) associated with wood-decaying fungi and mycophagous erotylid beetles (Coleoptera: Erotylidae) in Europe

We describe a new genus in the mite family Melicharidae, Mycomelichares Mašán & Joharchi gen. nov., to accommodate two new species, Mycomelichares polypori Mašán & Joharchi sp. nov. and Mycomelichares reductus Mašán & Joharchi sp. nov. on the basis of specimens collected on wood-decaying fungi and/or mycophagous beetles of the genera Triplax Herbst and Tritoma Fabricius (Coleoptera: Erotylidae) in Slovakia and European part of Russia, respectively. Moreover, two previously described Proctolaelaps species—P. cyllodi Samšiňák, 1960 and P. slovacus Mašán, 1998 are transferred to the newly established genus. The new genus is characterized by specific characters in tritosternum (enlarged and brush-shaped, having their laciniae thickened, basaly fused and distally densely pilose), chelicerae (slightly dish-shaped digits with long, narrow and sharp denticles), ventral hypostome (setae h1 enlarged, thickened and distally flattened), setation (tendency towards placement of R series setae on soft integument, and reduction of some setae on idiosoma and legs), and unusual ecological specialisation on fungal substrates. Mycomelichares polypori sp. nov. is adapted to the life in sporophores of the basidiomycete bracket fungus, Polyporus squamosus (Polyporaceae). Mites of this species can be abundantly found on the lower fertile surface of the fungus, including large spore-bearing pores. Furthermore, keys to the melicharid genera reported from Palaearct, and the species of the genus are provided.

Complete Genome Sequence of Bacillus megaterium Podophage Pavlov

Bacillus megaterium is a large spore-forming bacterium found widely in the environment. Phages infecting B. megaterium can be used as genetic tools to expand the array of uses of B. megaterium in research and industry. Here, we present the complete genome of Pavlov, a podophage infecting B. megaterium.

Evaluation of a Stochastic Inactivation Model for Heat-Activated Spores of Bacillus spp.

ABSTRACT Heat activates the dormant spores of certain Bacillus spp., which is reflected in the “activation shoulder” in their survival curves. At the same time, heat also inactivates the already active and just activated spores, as well as those still dormant. A stochastic model based on progressively changing probabilities of activation and inactivation can describe this phenomenon. The model is presented in a fully probabilistic discrete form for individual and small groups of spores and as a semicontinuous deterministic model for large spore populations. The same underlying algorithm applies to both isothermal and dynamic heat treatments. Its construction does not require the assumption of the activation and inactivation kinetics or knowledge of their biophysical and biochemical mechanisms. A simplified version of the semicontinuous model was used to simulate survival curves with the activation shoulder that are reminiscent of experimental curves reported in the literature. The model is not intended to replace current models to predict dynamic inactivation but only to offer a conceptual alternative to their interpretation. Nevertheless, by linking the survival curve's shape to probabilities of events at the individual spore level, the model explains, and can be used to simulate, the irregular activation and survival patterns of individual and small groups of spores, which might be involved in food poisoning and spoilage.

Fern spores in a grassland soil

Large numbers of fern spores germinated in soil samples from a grassland trail. The trail was established in central Sweden 35 years ago to study the effect of different treatments on grassland vegetation. The density of prothallia varied between 57 000 and 170 000 m−2 in the different treatments. There were no ferns in the treatment plots, and none of the three fern species identified from the spore bank were found in the surrounding area. This suggests that the large spore bank has accumulated over a long period of time and that fern spores are capable of remaining viable in the soil for several years. A large spore bank can enhance the chance for intergametophytic crossing in fern species. Key words: fern, grassland, Pteridophyta, soil seed bank, spore bank.

Cell patterning in migrating slugs of Dictyostelium discoideum

When front quarters of migrating slugs of Dictyostelium discoideum are isolated by surgery and induced to fruit immediately they produce fruiting bodies with disproportionately large stalks (Raper, 1940). The data in this communication show that the ‘stalky’ character of fruits derived from front quarters persists even if the cells of the front quarters are disaggregated and hence have to reaggregate before fruiting. The data also demonstrate that fruits derived from rear quarters of slugs have disproportionately large spore heads, and that this effect becomes more pronounced with increasing age of the slugs. These observations support the view that the cells of the front and rear of migrating slugs are to some extent committed to different fates.

Muds of the Clyde Sea Area. II. Bacterial Content

1. The bacterial content of mud deposits in the Clyde Sea Area has been investigated.2. The number of bacteria is found to decrease from the surface downwards.3. The numbers fluctuate very much in the top mud layers, and there is some evidence of bacterial zonation.4. In the deeper mud layers the bacterial content for any given station is fairly constant.5. The predominant organisms were found to be water bacteria of the Achromobacter and Chromobacterium type, and large spore-forming bacilli similar to common soil bacteria.6. The factors affecting the bacterial content of the muds are discussed.