Water clearance efficiency indicates potential filter-feeding interactions between invasive <Emphasis Type="Italic">Sinanodonta woodiana</Emphasis> and native freshwater mussels

The Chinese pond mussel (Sinanodonta woodiana Lea, 1834) is a benthic filter-feeder that prefers soft-bottomed freshwater habitats and has successfully spread into both tropical and temperate water bodies outside its natural Southeast Asian range. Due to its preference for nutrient-rich waters with high levels of suspended food particles, the capacity of S. woodiana to influence natural seston concentrations is thought to be relatively low in comparison to that of other invasive bivalves. The experimental quantification of seston removal efficiency reported here demonstrates that S. woodiana is able to reduce seston loads to levels comparable to those by the control native freshwater mussel species Unio tumidus Philipsson, 1788. Moreover, increasing food depletion did not cause detectable changes in the filtration regime of S. woodiana, although the activity of native U. tumidus was significantly reduced. The seston clearance rate (volume of water cleared of particles per unit time) of S. woodiana averaged 9.3 ± 4.0 mL g^?1 wet mass h^?1, which corresponds to the total daily volume of water filtered being up to several hundreds to thousands L m^?2 at the maximal S. woodiana population densities reported in the literature. The observed filtration capacity of S. woodiana and its current invasional spread into areas inhabited by endangered freshwater mussels call for more careful consideration of filter-feeding interactions with native mussels. The potential impacts of S. woodiana should be studied in more detail with respect to available food resources and long-term nutritional needs of native species and reflected in management strategies in the invaded range.     

Cotton-Grass and Blueberry have Opposite Effect on Peat Characteristics and Nutrient Transformation in Peatland

Peatlands are large repositories of carbon (C). Sphagnum mosses play a key role in C sequestration, whereas the presence of vascular plants is generally thought to stimulate peat decomposition. Recent studies stress the importance of plant species for peat quality and soil microbial activity. Thus, learning about specific plant–microbe–soil relations and their potential feedbacks for C and nutrient cycling are important for a correct understanding of C sequestration in peatlands and its potential shift associated with vegetation change. We studied how the long-term presence of blueberry and cotton-grass, the main vascular dominants of spruce swamp forests, is reflected in the peat characteristics, soil microbial biomass and activities, and the possible implications of their spread for nutrient cycling and C storage in these systems. We showed that the potential effect of vascular plants on ecosystem functioning is species specific and need not necessarily result in increased organic matter decomposition. Although the presence of blueberry enhanced phosphorus availability, soil microbial biomass and the activities of C-acquiring enzymes, cotton-grass strongly depleted phosphorus and nitrogen from the peat. The harsh conditions and prevailing anoxia retarded the decomposition of cotton-grass litter and caused no significant enhancement in microbial biomass and exoenzymatic activity. Therefore, the spread of blueberry in peatlands may stimulate organic matter decomposition and negatively affect the C sequestration process, whereas the potential spread of cotton-grass would not likely change the functioning of peatlands as C sinks.     

Characterization of yeast amylolytic enzymes by HPLC maltooligosaccharides determination

Summary A simple method for determination of starch hydrolysis degree by measurement of maltooligosaccharides using HPLC on SGX C-18 column with deionised water as mobile phase was presented. Separation of seven oligosaccharides in an order from glucose to maltoheptaose illustrated the action of two enzyme systems taking part of starch hydrolysis and following fermentation to ethanol.     

The immune response against Francisella tularensis live vaccine strain in Lpsn and Lpsd mice

Abstract The impact of Lps gene on the course of immune response against subcutaneous infection of mice with Francisella tularensis live vaccine strain was studied. Production and specificity of antibodies, cytotoxic responses of macrophages and NK-cells, spontaneous production ex vivo of cytokines IL-1α, IL-2, IL-4, IL-6, IL-10, IFN-γ, and TNF-α in spleen cell cultures in C3H/HeJ ( Lps ^d) mice in comparison with C3H/HeN ( Lps ^r) mice were tested. The value of LD₅₀ was significantly different in the two strains of mice (8.0 × 10³ cfu for C3H/HeJ versus 4.61 × 10⁵ cfu for C3H/HeN mice after subcutaneous inoculation). The production of NO₂ is also impaired in C3H/HeJ mice in the early intervals after infection. Thus, the defective Lps gene of C3H/HeJ mice influences both the level of innate resistance of mice to F. tularensis live vaccine strain infection and the process of induction and regulation of immune response against this intracellular bacterial pathogen.     

Nursing Synchronization and Milk Ejection Failure as Maternal Strategies to Reduce Allosuckling in Pair-Housed Sows (Sus scrofa domestica)

Non‐offspring nursing (allosuckling) is costly for lactating females. It is reasonable to assume, therefore, that mechanisms have evolved to control the frequency of allosuckling. It is suggested that the synchronization of nursing between females could be such a mechanism. The aim of this study was to investigate whether nursing synchronization is related to the timing of nursing behaviour of paired sows and the behaviour of alien piglets in relation to allosuckling. Specifically, we predicted that: (i) nursing synchronization will increase if there is a real risk of allosuckling compared with a situation where there is none, (ii) nursing synchronization indeed reduces allosuckling and, therefore, those nursings with allosuckling attempts will be less closely synchronized than those without allosuckling attempts and (iii) in non‐synchronized nursings, the sows will more often employ another strategy to reduce allosuckling, namely, they will make the nursings non‐nutritive by not releasing milk. Ten pairs of sows and their litters were used in this study. For each pair, the two sows were housed individually until their litters were weaned; however, their litters had access to both sows from day 11 post‐partum. The behaviour of the 10 pairs of sows with their litters was videotaped for 6 h on days 10, 11, 17 and 24 post‐partum. The frequency of allosuckling attempts, non‐nutritive nursings and allosuckling during milk ejection was analysed for every pair for every day of observation. The observed frequency of nursing synchronization was high. The median interval between the start of a nursing within one pair of sows was 32 s. The first prediction was supported as synchronization became significantly tighter when piglets were given the possibility to allosuckle on day 11 [Cochran–Mantel–Haenszel (CMH) statistics, p < 0.0001]. The second prediction was also supported; the nursings were less closely synchronized when there were allosuckling attempts (CMH statistics, p < 0.05). Of all nursings, 36% had an allosuckling attempt; however, only 17% resulted in real allosuckling. Evidence in favour of the third prediction was also found as non‐nutritive nursings were more frequent in non‐synchronized nursings (CMH statistics, p < 0.05). Finally, real allosuckling during milk ejection was unrelated to the degree of nursing synchronization, as in less synchronized nursings, the sows responded to allosuckling attempts by not releasing milk. Our results suggest that sows are not able to completely suppress allosuckling; however, they can reduce its frequency through nursing synchronization and non‐nutritive nursings.     

Annual and intra-annual growth dynamics of <Emphasis Type="Italic">Myricaria elegans</Emphasis> shrubs in arid Himalaya

Key message

To disentangle complex drivers of Myricaria elegans growth in arid Himalaya, we combined tree-ring analysis with detailed dendrometer records. We found that the combination of winter frost, summer floods, and strong summer diurnal temperature fluctuations control annual and intra-annual growth dynamics. The relative importance of these drivers is, however, changing with ongoing climate change.

Abstract

High-mountain areas are among the most sensitive environments to climate change. Understanding how different organisms cope with ongoing climate change is now a major topic in the ecology of cold environments. Here, we investigate climate drivers of the annual and intra-annual growth dynamics of Myricaria elegans, a 3–6 m tall tree/shrub, in a high-elevation cold desert in Ladakh, a rapidly warming region in the NW Himalayas. As Myricaria forms narrow stands around glacier streams surrounded by the desert, we hypothesized that its growth between 3800 and 4100 m will be primarily limited by low temperatures and summer floods. We found that warmer and less snowy conditions in April and May enhance earlywood production. Latewood formation is mostly driven by the June–July temperatures (T). The positive effect of warmer summers on both annual and intra-annual growth is related to fluctuating daily T (from +30 to 0 °C). In particular, dendrometer measurements over a 2-year period showed that net daily growth increments increased when the summer night T remained above 6 °C. While high night T during generally cold desert nights promoted growth, high daytime T caused water stress and growth inhibition. The growth–temperature dependency has gradually weakened due to accelerated warming since the 1990s. In addition, positive latewood responses to high March precipitation during the colder 1960s–1980s have become negative during the warmer 1990s–2000s, reflecting an intensification of summer floods. Latewood width increased while earlywood width decreased from the 1990s, indicating a prolonged growing season and a higher risk of drought-induced embolism in earlywood vessels. Due to a multiplicity of environmental drivers including winter frost, intensified floods and strong summer diurnal T fluctuations, Myricaria growth is not controlled by a single climate parameter. Similar results are increasingly reported from other Himalayan treelines, showing that ongoing climate change will trigger complex and probably spatially variable responses in tree growth. Our study showed that these complex climatic signals can be disentangled by a combination of long-term data from tree-rings with detailed, but short-term, records from dendrometers.

     

Low Ability of Great Tits to Discriminate Similarly Inconspicuous Edible and Inedible Prey

Numerous studies have shown warning coloration to facilitate the discrimination of edible and inedible prey. However, inedible insect species may possess cryptic coloration as well. It has been shown that some other visual features (especially characteristic body shape) are sufficient for the recognition of some insect taxa (e.g. ladybirds, ants, wasps). We tested the ability of wild‐caught great tits (Parus major) to discriminate between the identically coloured edible (roach – Blaptica dubia) and the inedible (firebug – Pyrrhocoris apterus) as prey according to subtle peripheral visual traits (shape of legs and antennae, body posture, and means of locomotion). Both prey species were offered either simultaneously or alternately. The ability of the birds to learn was tested by means of fourteen trial repetitions in two sessions. In general, great tits were not able to learn to discriminate between firebugs and roaches by subtle shape cues alone during the two sessions. However, multivariate analysis of individual bird behaviour showed that they adopted one of three different attitudes to the presented prey. Most of the birds never attacked any or always attacked both prey. In addition, a small proportion of the birds was able to discriminate between the two prey types and attacked only roaches. Nevertheless, firebugs survived most of the attacks, which suggests that in case of chemically protected prey, the evolution of conspicuous coloration is not always the best/only option.     

Identification of B‐cell epitopes of Borrelia burgdorferi outer surface protein C by screening a phage‐displayed gene fragment library

Outer surface protein C (OspC) of Borrelia stimulates remarkable immune responses during early infection and is therefore currently considered a leading diagnostic and vaccine candidate. The sensitivity and specificity of serological tests based on whole protein OspC for diagnosis of Lyme disease are still unsatisfactory. Minimal B‐cell epitopes are key in the development of reliable immunodiagnostic tools. Using OspC fragments displayed on phage particles (phage library) and anti‐OspC antibodies isolated from sera of naturally infected patients, six OspC epitopes capable of distinguishing between LD patient and healthy control sera were identified. Three of these epitopes are located at the N‐terminus (OspC E1 aa19–27, OspC E2 aa38–53, OspC E3 aa62–66) and three at the C‐terminal end (OspC E4 aa155–163, OspC E5 aa184–190 and OspC E6 aa201–207). OspC E1, E4 and E6 were highly conserved among LD related Borreliae. To our knowledge, epitopes OspC E2, E3 and E5 were identified for the first time in this study. Minimal B‐cell epitopes may provide fundamental data for the development of multi‐epitope‐based diagnostic tools for Lyme disease.     

Forest reclamation of fly ash deposit: a field study on appraisal of mycorrhizal inoculation

An extensive field trial was established on a fly ash deposit (1) to evaluate whether the inoculation with arbuscular mycorrhizal fungi (AMF) and/or ectomycorrhizal fungi (EcMF) improves growth and survival of 13 planted tree species and (2) to trace the inoculated mycorrhizal fungi in tree roots after one growing season. Molecular methods were applied to characterize AMF and EcMF entering the studied system (inocula, native soil, and roots of nursery seedlings). Biometric parameters and mortality of the trees were recorded and the presence of AMF and EcMF in sampled trees was determined both microscopically and genetically. Mycorrhizal inoculation did not improve survival or growth of any tree species. Most AMF‐host and all EcMF‐host seedlings were highly precolonized already from the nursery. An abundant and diverse AMF community was also found in the field soil. The AMF inoculum taxa partially overlapped with AMF in the native soil and in the precolonized roots. After one season, the only two inoculum‐unique AMF taxa were detected in host species non‐precolonized or only partially precolonized from the nursery. The components of EcMF inoculum were not detected in any sampled tree. After the season, the ectomycorrhizal hosts maintained most of their original EcMF taxa gathered in nursery, some tree species were additionally colonized by EcMF probably originating from the soil. Our results show considerable self‐restoration potential of nature on the target site. Mycorrhizal inoculation thus did not bring any conclusive advantage to the planted trees and seems superfluous for reclamation practice on the fly ash deposit.     

Arsenophonus nasoniae and Rickettsiae Infection of Ixodes ricinus Due to Parasitic Wasp Ixodiphagus hookeri

Arsenophonus nasoniae, a male-killing endosymbiont of chalcid wasps, was recently detected in several hard tick species. Following the hypothesis that its presence in ticks may not be linked to the direct occurrence of bacteria in tick''s organs, we identified A. nasoniae in wasps emerging from parasitised nymphs. We confirmed that 28.1% of Ixodiphagus hookeri wasps parasitizing Ixodes ricinus ticks were infected by A. nasoniae. Moreover, in examined I. ricinus nymphs, A. nasoniae was detected only in those, which were parasitized by the wasp. However, in part of the adult wasps as well as in some ticks that contained wasp''s DNA, we did not confirm A. nasoniae. We also found, that in spite of reported male-killing, some newly emerged adult wasp males were also infected by A. nasoniae. Additionally, we amplified the DNA of Rickettsia helvetica and Rickettsia monacensis (known to be Ixodes ricinus-associated bacteria) in adult parasitoid wasps. This may be related either with the digested bacterial DNA in wasp body lumen or with a role of wasps in circulation of rickettsiae among tick vectors.