Exotic Mammals Disperse Exotic Fungi That Promote Invasion by Exotic Trees

Biological invasions are often complex phenomena because many factors influence their outcome. One key aspect is how non-natives interact with the local biota. Interaction with local species may be especially important for exotic species that require an obligatory mutualist, such as Pinaceae species that need ectomycorrhizal (EM) fungi. EM fungi and seeds of Pinaceae disperse independently, so they may use different vectors. We studied the role of exotic mammals as dispersal agents of EM fungi on Isla Victoria, Argentina, where many Pinaceae species have been introduced. Only a few of these tree species have become invasive, and they are found in high densities only near plantations, partly because these Pinaceae trees lack proper EM fungi when their seeds land far from plantations. Native mammals (a dwarf deer and rodents) are rare around plantations and do not appear to play a role in these invasions. With greenhouse experiments using animal feces as inoculum, plus observational and molecular studies, we found that wild boar and deer, both non-native, are dispersing EM fungi. Approximately 30% of the Pinaceae seedlings growing with feces of wild boar and 15% of the seedlings growing with deer feces were colonized by non-native EM fungi. Seedlings growing in control pots were not colonized by EM fungi. We found a low diversity of fungi colonizing the seedlings, with the hypogeous Rhizopogon as the most abundant genus. Wild boar, a recent introduction to the island, appear to be the main animal dispersing the fungi and may be playing a key role in facilitating the invasion of pine trees and even triggering their spread. These results show that interactions among non-natives help explain pine invasions in our study area.     

Screening of different algae for green synthesis of gold nanoparticles

The cyanobacteria Phormidium valderianum, P. tenue and Microcoleus chthonoplastes and the green algae Rhizoclonium fontinale, Ulva intestinalis, Chara zeylanica and Pithophora oedogoniana were exposed to hydrogen tetrachloroaurate solution and were screened for their suitability for producing nano‐gold. All three cyanobacteria genera and two of the green algae (Rhizoclonium fontinale and Ulva intestinalis) produced gold nanoparticles intracellularly, confirmed by purple colouration of the thallus within 72?h of treatment at 20°C. Extracted nanoparticle solutions were examined by UV‐vis spectroscopy, transmission electron microscopy (TEM) and X‐ray diffractometry (XRD). XRD confirmed the reduction of Au (III) to Au (0). UV‐vis spectroscopy and TEM studies indicated the production of nanoparticles having different shapes and sizes. Phormidium valderianum synthesized mostly spherical nanoparticles, along with hexagonal and triangular nanoparticles, at basic and neutral pHs (pH 9 and pH 7, respectively). Medicinally important gold nanorods were synthesized (together with gold nanospheres) only by P. valderianum at acidic pH (pH 5); this was initially determined by two surface plasmon bands in UV‐vis spectroscopy and later confirmed by TEM. Spherical to somewhat irregular particles were produced by P. tenue and Ulva intestinalis (TEM studies). The UV‐vis spectroscopy of the supernatant of other algal extracts indicated the formation of mostly spherical particles. Production of gold nanoparticles by algae is more ecofriendly than purely chemical synthesis. However, the choice of algae is important: Chara zeylanica and Pithophora oedogoniana were found to be unable to produce nanoparticles.     

Ixodes ricinus is the dominant questing tick in forest habitats in Romania: the results from a countrywide dragging campaign

In 2010 and 2011, questing ticks were collected from 188 forested locations in all the 41 counties of Romania using the dragging method. The total of 13,771 ticks collected belonged to eleven species: Ixodes ricinus (86.9?%), Dermacentor marginatus (9.5?%), Haemaphysalis punctata (2.6?%), H. concinna (0.6?%), H. sulcata (0.3?%), H. parva (0.1?%), Hyalomma marginatum (0.02?%), D. reticulatus (0.02?%), I. crenulatus (0.007?%), I. hexagonus (0.007?%) and I. laguri (0.007?%). Ixodes ricinus was present in 97.7?% (n?=?180) of locations, occurring exclusively in 41.7?% of the locations, whereas it was the dominant species in 38.8 % of the other locations, accounting for over 70?% of the total tick community. The following most common questing ticks were D. marginatus, H. punctata and H. concinna. Ixodes ricinus co-occurred with one, two or three sympatric species. The occurrence of D. reticulatus in forested habitats from Romania was found to be accidental.     

The Spinner-IBMM mouse is a new spontaneous mutant in the Tmie gene

A recessively inherited, spontaneous mutation named Spinner-IBMM (SI) was identified in a transgenic mouse colony in our institute. SI mutant mice displayed hyperactivity, including a severe circling behavior, ataxia and inability to swim. Gene mapping revealed that the causative gene was located on a 35 Mb DNA fragment on chromosome 9. Candidate genes sequencing in this DNA fragment identified a new mutant allele in the Tmie gene. The identified mutant is characterized by a nucleotide deletion in exon 5, leading to a frameshift and a premature STOP codon. It has been reported that inactivating mutations in the mouse Tmie gene result in an identical phenotype, probably resulting from defects in the inner ear. However, the exact function of the Tmie protein in the ear and other organs is still unknown. The analysis of this new mouse mutant could contribute to a better understanding of Tmie functions in vivo in the ear and other organs.     

Distribution of individual members of the mosquito Anopheles maculipennis complex in Germany identified by newly developed real‐time PCR assays

Owing to their role as vectors of malaria parasites, species of the Anopheles maculipennis complex (Diptera: Culicidae) Meigen were intensively studied in the past, but with the disappearance of malaria in Germany in the middle of the last century, the interest in this field of research declined. A comprehensive ecological analysis of the current species distribution for Germany is lacking. Between 2010 and 2013, a total of 1445 mosquitoes of the An. maculipennis complex were collected at 72 different sites in Germany. The samples comprise 722 single individuals as well as 723 individuals in 90 pools of up to 25 mosquitoes. All samples were analysed with newly developed species‐specific qPCR assays for the identification of the four German species using nucleotide differences within the internal transcribed spacer 2 (ITS2) ribosomal DNA. All gathered data were used for species distribution modelling. The overall prevalence of An. messeae s.l. was highest with 98.89% of all pools; An. daciae with 6.93% of all individuals and An. messeae s.s. with 69.53%. The prevalence of the other two species was relatively low: An. maculipennis s.s. with 13.30% of all individuals (6.67% of all pools) and An. atroparvus with 1.80% of all individuals (1.11% of all pools).     

Can alien plants support generalist insect herbivores?

Simple rearing experiments were conducted to address two questions relevant to understanding how generalist lepidopteran herbivores interact with alien plants. Yellow-striped armyworm (Spodoptera ornithogalli), luna moth (Actias luna), bagworm (Thyridopteryx ephemeraeformis) and white-marked tussock moth (Orgyia leucostigma) were reared from egg to 5th instar on excised foliage in the laboratory to determine the degree to which highly polyphagous lepidopteran herbivores are physiologically capable of surviving and developing on the suite of alien plants naturalized in the mid-Atlantic. Actias luna larvae from a single population were similarly reared on a representative of each of the 25 native plant genera recorded as hosts for this species to compare the diet breadth of a local population with that listed over the entire geographic range of the species. With few exceptions, all four generalists either quickly starved or grew at an unsustainably low rate on alien foliage. Actias luna larvae survived for 18 days on only 44% of the native plants recorded as hosts over the entire range of this insect and thrived on only 7%. The data suggest that (1) alien plants are unlikely to produce as much generalist insect biomass as the native plants they replace and (2) Lepidoptera that qualify as generalists when host breadth is considered over their entire geographic range may express a far more specialized diet within local populations. Both of these conclusions support the hypothesis that alien plant invasions may seriously disrupt terrestrial food webs by reducing the insect biomass required by insectivores in higher trophic levels.     

Consequences of disperser behaviour for seedling establishment of a mistletoe species

The dispersal process in plants links adults and their offspring. For frugivore‐dispersed plants, animal behaviour can have a strong effect on plant fitness. Many mistletoes are totally dependent on animals that deposit seeds on suitable hosts and particular branch diameters. We characterised the seed dispersal and seedling establishment of the mistletoe Tristerix corymbosus, which at our study site, is exclusively dispersed by the marsupial Dromiciops gliroides. Mistletoes’ fruits have a viscous pulp that remains in the seed even after dispersal. This substance adheres the seed to the host branch. We estimated host branch availability in the forest and seed deposition (faeces) by the marsupial in the study area. Specifically, the branch suitability factors we assessed were host identity, branch status (alive or dead), branch diameter, height, and canopy cover. Lodged faeces were individually marked and the number of seed deposited within these droppings was counted, and we recorded the number of seedlings with true leaves that had established after 1 year to estimate the probability of seedling establishment. Branch diameter and canopy cover had a significant positive effect on seed deposition probability. Seedling establishment probability decreased with the number of seeds deposited per faeces and with canopy cover. In general, the marsupial deposited mistletoe seeds in microsites that increase the chance of seedling establishment. Thus, the movement behaviour of the marsupial has a positive effect on the regeneration process of this mistletoe species.     

Addition of hydrophilic and lipophilic compounds of biological relevance to the monoolein/water system. I. Phase behavior

The solubilization of hydrophilic and lipophilic molecules, with biological relevance, in the monoolein/water (MO/W) system has been investigated for phase behavior. Small angle X-ray scattering (SAXS), nuclear magnetic resonance (NMR) and optical microscopy (OM) have been used to characterize the microstructure of the liquid crystalline phases. Partial phase diagrams of the MO/W system in the presence of sodium decanoate, 1-adamantanamine hydrochloride, decanoic and dodecanoic acids, acetyl salicilic acid and retinol have been determined. The stability of the various phases has been followed for at least eight months. The polarity and the molecular structure of the additive determine whether it is located at the polar interface or in the apolar region of the lipid layer. Therefore, the additive affects the interfacial curvature of the lipid layer differently, which in turn will trigger transition to disparate phases. A cubic-to-reverse hexagonal phase transition has been observed with time for most of the ternary systems, with the exception of 1-adamantanamine hydrochloride and retinol. The release of free glycerol and oleic acid due to MO hydrolysis has been clearly demonstrated by 13C NMR. This would account for the changes in phase behavior observed with time. The released oleic acid, located in the MO acyl chain region, favors the inverse interfacial curvature. The average lipid dimensions in the cubic and in the reverse hexagonal phases have been calculated from SAXS data.     

Evidence of two populations of GABA(A) receptors in cerebellar granule cells in culture: different desensitization kinetics, pharmacology, serine/threonine kinase sensitivity, and localization

GABA(A) receptors of rat cerebellar granule cells in culture have been studied by the whole cell patch clamp technique. The biphasic desensitization kinetic observed could be due either to different desensitization mechanisms of a single receptor population or to different receptor populations. The overall data indicate that the latter hypothesis is most probably the correct one. In fact, the fast desensitizing component was selectively potentiated by a benzodiazepine agonist and preferentially down-regulated by activation of the protein serine/threonine kinases A and G, as a consequence of the latter characteristic that receptor population was preferentially down-regulated by previous activation of N-methyl-d-aspartate glutamate receptors, via production of nitric oxide and PKG activation, most probably in dendrites. The other population is benzodiazepine insensitive and not influenced by activation of PKA or PKG. This slowly desensitizing population may correspond to the extrasynaptic delta subunit containing GABA(A) receptors described by other authors. Instead, the rapidly desensitizing population appears to represent dendritic synaptic GABA(A) receptors.