Frequency of hybridization between Ostrinia nubilalis E‐and Z‐pheromone races in regions of sympatry within the United States

Female European corn borer, Ostrinia nubilalis, produce and males respond to sex pheromone blends with either E‐ or Z‐Δ11‐tetradecenyl acetate as the major component. E‐ and Z‐race populations are sympatric in the Eastern United States, Southeastern Canada, and the Mediterranean region of Europe. The E‐ and Z‐pheromone races of O. nubilalis are models for incipient species formation, but hybridization frequencies within natural populations remain obscure due to lack of a high‐throughput phenotyping method. Lassance et al. previously identified a pheromone gland‐expressed fatty‐acyl reductase gene (pgfar) that controls the ratio of Δ11‐tetradecenyl acetate stereoisomers. We identified three single nucleotide polymorphism (SNP) markers within pgfar that are differentially fixed between E‐ and Z‐race females, and that are ≥98.2% correlated with female pheromone ratios measured by gas chromatography. Genotypic data from locations in the United States demonstrated that pgfar‐z alleles were fixed within historically allopatric Z‐pheromone race populations in the Midwest, and that hybrid frequency ranged from 0.00 to 0.42 within 11 sympatric sites where the two races co‐occur in the Eastern United States (mean hybridization frequency or heterozygosity (H_O) = 0.226 ± 0.279). Estimates of hybridization between the E‐ and Z‐races are important for understanding the dynamics involved in maintaining race integrity, and are consistent with previous estimates of low levels of genetic divergence between E‐ and Z‐races and the presence of weak prezygotic mating barriers.     

Species patterns in foliar nitrogen concentration, nitrogen content and 13C abundance for understory saplings across light gradients

Soil nitrogen (N) supply and uptake by regenerating trees is an important ecosystem attribute but difficult to quantify in partial-cut forests where light availability varies. The foliar attributes of N concentration (N_%) and N per unit area (N_a) may help characterize the influence of soil nutrition, but ideally the relationship between soils and foliage would be tested separately by species across well-defined light gradients. To do this, we examined foliar attributes of four tree species across gradients of light availability in 12 year-old partially-cut forests in northwest British Columbia, Canada. There were no differences in forest floor or mineral soil N mineralization rates across the light gradients, and for western hemlock (Tsuga heterophylla) and hybrid white spruce (Picea glauca x sitchensis), this consistent level of soil N supply corresponded with unchanging foliar N_%. In contrast, foliar N_% of Betula papyrifera (paper birch) and Thuja plicata (western redcedar) declined with shading, perhaps due to shifts in root-shoot biomass allocation for B. papyrifera, and climatic constraints on shade tolerance for T. plicata. Leaf δ¹³C approached an asymptote at approx. 40% full light for the coniferous species, but increased linearly with light for B. papyrifera. Foliar N_a was linearly correlated with leaf δ¹³C for three species, reflecting the dual effect of light and nutrition on photosynthesis processes, and suggesting that foliar N_a may be a simple parameter to integrate both resource constraints on regenerating saplings. These results demonstrate both support for and limits to foliar attributes among species in isolating soil N effects against light constraints in partial-cut forests.     

Combinations of β-Lactam or Aminoglycoside Antibiotics with Plectasin Are Synergistic against Methicillin-Sensitive and Methicillin-Resistant Staphylococcus aureus

Bacterial infections remain the leading killer worldwide which is worsened by the continuous emergence of antibiotic resistance. In particular, methicillin-sensitive (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) are prevalent and the latter can be difficult to treat. The traditional strategy of novel therapeutic drug development inevitably leads to emergence of resistant strains, rendering the new drugs ineffective. Therefore, rejuvenating the therapeutic potentials of existing antibiotics offers an attractive novel strategy. Plectasin, a defensin antimicrobial peptide, potentiates the activities of other antibiotics such as β-lactams, aminoglycosides and glycopeptides against MSSA and MRSA. We performed in vitro and in vivo investigations to test against genetically diverse clinical isolates of MSSA (n = 101) and MRSA (n = 115). Minimum inhibitory concentrations (MIC) were determined by the broth microdilution method. The effects of combining plectasin with β-lactams, aminoglycosides and glycopeptides were examined using the chequerboard method and time kill curves. A murine neutropenic thigh model and a murine peritoneal infection model were used to test the effect of combination in vivo. Determined by factional inhibitory concentration index (FICI), plectasin in combination with aminoglycosides (gentamicin, neomycin or amikacin) displayed synergistic effects in 76-78% of MSSA and MRSA. A similar synergistic response was observed when plectasin was combined with β-lactams (penicillin, amoxicillin or flucloxacillin) in 87–89% of MSSA and MRSA. Interestingly, no such interaction was observed when plectasin was paired with vancomycin. Time kill analysis also demonstrated significant synergistic activities when plectasin was combined with amoxicillin, gentamicin or neomycin. In the murine models, plectasin at doses as low as 8 mg/kg augmented the activities of amoxicillin and gentamicin in successful treatment of MSSA and MRSA infections. We demonstrated that plectasin strongly rejuvenates the therapeutic potencies of existing antibiotics in vitro and in vivo. This is a novel strategy that can have major clinical implications in our fight against bacterial infections.     

Phylogeography and population differentiation in terrestrial island populations of Banksia arborea (Proteaceae)

The Banded Iron Formations (BIFs) of south‐western Australia are terrestrial islands characterized by high species richness and endemism. Regional endemics occur across multiple formations without inhabiting the intervening landscape matrix. We investigated whether the occurrence on BIF terrestrial islands has led to genetic differentiation among the eight known populations of the regional endemic, Banksia arborea. Genetic structure was assessed using three chloroplast DNA sequence markers and 11 nuclear microsatellite loci. Phylogenetic relationships were assessed with statistical parsimony and Bayesian methods. Dates of haplotype divergence were estimated using the time to most recent common ancestor of B. arborea and Banksia purdieana, as well as a conservative angiosperm chloroplast (cp)DNA mutation rate. Population genetic diversity and structure was assessed amongst and within populations by genotyping 24 geographically clustered individuals from each BIF and three subpopulations within the Die Hardy Range BIF. Indirect gene flow estimates were determined using a method based on the frequency of private alleles. Banksia arborea showed low genetic diversity in (cp)DNA and a complex structural pattern, with genetic differentiation of some BIF populations and an absence of differentiation amongst others, reflecting either retention of ancestral polymorphism across northern BIF populations or more recent connectivity of these populations. There was little evidence of pollen dispersal both between BIFs and within the large BIF known as Die Hardy Range. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 860–872.     

Molecular cloning of ATR5(Emoy2) from Hyaloperonospora arabidopsidis, an avirulence determinant that triggers RPP5-mediated defense in Arabidopsis

RPP5 is the seminal example of a cytoplasmic NB-LRR receptor-like protein that confers downy mildew resistance in Arabidopsis thaliana. In this study, we describe the cloning and molecular characterization of the gene encoding ATR5(Emoy2), an avirulence protein from the downy mildew pathogen Hyaloperonospora arabidopsidis isolate Emoy2. ATR5(Emoy2) triggers defense response in host lines expressing the functional RPP5 allele from Landsberg erecta (Ler-0). ATR5(Emoy2) is embedded in a cluster with two additional ATR5-like (ATR5L) genes, most likely resulting from gene duplications. ATR5L proteins do not trigger RPP5-mediated resistance and the copy number of ATR5L genes varies among H. arabidopsidis isolates. ATR5(Emoy2) and ATR5L proteins contain a signal peptide, canonical EER motif, and an RGD motif. However, they lack the canonical translocation motif RXLR, which characterizes most oomycete effectors identified so far. The signal peptide and the N-terminal regions including the EER motif of ATR5(Emoy2) are not required to trigger an RPP5-dependent immune response. Bioinformatics screen of H. arabidopsidis Emoy2 genome revealed the presence of 173 open reading frames that potentially encode for secreted proteins similar to ATR5(Emoy2), in which they share some motifs such as EER but there is no canonical RXLR motif.     

Fossil juvenile coelacanths from the Devonian of South Africa shed light on the order of character acquisition in actinistians

A new coelacanth genus from the Famennian (Upper Devonian) of South Africa is described, principally from presumed juveniles. S erenichthys kowiensis gen. et sp. nov. uniquely shares with Diplocercides a ventral expansion of the elbow‐like lachrymojugal, as well as a symmetrical diphycercal tail supported by expanded neural and haemal spines and radials. Serenichthys is distinguished from Diplocercides by a number of derived characters, including possession of longer anterior parietals, a more crescent‐shaped postorbital with a more anteriorly positioned infraorbital canal, and a far smaller squamosal, which is well separated from the skull roof. By contrast, Serenichthys appears to lacks a second dorsal fin lobe, a derived feature present in Diplocercides. Most specimens of Serenichthys are between 3 and 6 cm in length. They have large eyes, and dermal bones of the skull ornamented with long wavy ridges, similar to the dermal ornament of other Devonian coelacanths such as Gavinia. Larger isolated operculae also collected from the Waterloo Farm locality and attributed to Serenichthys indicate that with growth the ridges on the dermal bones transformed into elongate tubercles, reminiscent of those of Diplocercides and Carboniferous taxa. Phylogenetic analysis resolves Serenichthys as the sister group of Holopterygius and all known post‐Devonian coelacanths. The clade including the unusual leaf‐shaped coelacanths, the Devonian Holopterygius and Carboniferous Allenypterus, branches from the coelacanth lineage immediately crownward of Serenichthys. The presence of abundant juveniles within an estuarine setting strongly parallels the discovery of similarly sized juveniles of Rhabdoderma exiguus together with eggs and yolk‐sack larvae in the Upper Carboniferous Mazon Creek biota. It is therefore argued that Serenichthys, like Rhabdoderma, was using the sheltered estuarine environment as a nursery. © 2015 The Linnean Society of London     

Oligochaetes (Naididae,Tubificidae, Enchytraeidae and Alluroididae) of Guyana,Peru and Ecuador

More than 41 species in 23 genera of the microdrile oligochaete families Tubificidae, Naididae, Opistocystidae, and Enchytraeidae and the freshwater megadrile family Alluroididae have been identified in recent collections made in Peru, Guyana and Ecuador. Just less than 70% of our species records are new for one or more of these countries and one is a new, albeit tentative, generic record for the South American continent. About 16 species new to science remain to be described. One of these is only the second reported species of Brinkhurstia (Alluroididae) and possesses unusual, single, very elongate penial setae. All of our species records are pertinent to tests of different hypotheses about historical and phylogenetic relationships among organisms of northern and southern South America and North America. The species, including new ones, with limited distributions are of particular significance to such hypotheses.     

Identification and characterization of 10 polymorphic microsatellite loci in the German cockroach,Blattella germanica

Primer sequences and initial characterization are presented for 10 microsatellite loci isolated from the German cockroach, Blattella germanica. In a sample of 30 individuals from a single population sample, all loci were polymorphic with two to 12 alleles segregating per locus and levels of observed heterozygosity ranging from 0.27 to 0.92. One locus showed a deficit of heterozygotes. Experimental conditions are described for polymerase chain reaction multiplexing, which enables the genotyping of eight loci in three electrophoretic runs consisting of one set of three and two sets of two markers. Seven primer sets cross‐amplify in the related Blattella asahinai.     

The effect of concentrated smoke products on the restoration of highly disturbed mineral sands in southeast Victoria

Summary Recent studies have recognized the potential of broad‐scale surface application of smoke compounds for enhancing germination from the soil seed‐bank in fire‐prone vegetation communities. Results suggest that smoke technology may play, in the future, a significant role in the restoration and management of areas supporting indigenous vegetation. An important step in the development of smoke‐based restoration tools is the conduct of in situ field trials in a range of geographical locations and environmental conditions. However, most of the published work on the effectiveness of smoke products in promoting seedbank germination has been conducted at sites in southwestern Australia. The present study examines the effect of commercially available smoke‐water products on the regeneration of a highly disturbed former mine‐site at the Royal Botanic Gardens Cranbourne, in southeastern Victoria. Various combinations of concentrated smoke products and topsoil harvested from a nearby heathy woodland community were applied to exposed, uniform mineral sands to test their effect on seedling density and species richness of regrowth. The trials showed that after 12 months a number of common, herbaceous species including Austrodanthonia setacea, Opercularia varia and Platysace heterophylla were recorded in significantly higher numbers in areas treated with a commercial smoke‐water. However, there was no overall improvement in the density of seedlings or the richness of species as a result of the application of the smoke products. Similarly, total seedling density and species richness were not affected by the addition of topsoil, either alone or in combination with smoke products.     

Cloning, heterologous expression, and functional characterization of 5-epi-aristolochene-1,3-dihydroxylase from tobacco (Nicotiana tabacum)

Capsidiol is a bicyclic, dihydroxylated sesquiterpene produced by several solanaceous species in response to a variety of environmental stimuli. It is the primary antimicrobial compound produced by Nicotiana tabacum in response to fungal elicitation, and it is formed via the isoprenoid pathway from 5-epi-aristolochene. Much of the biosynthetic pathway for the formation of this compound has been elucidated, except for the enzyme(s) responsible for the conversion of 5-epi-aristolochene to its dihydroxylated form, capsidiol. Biochemical evidence from previous studies with N. tabacum (Whitehead, I. M., Threlfall, D. R., and Ewing, D. F., 1989, Phytochemistry 28, 775-779) and Capsicum annuum Hoshino, T., Yamaura, T., Imaishi, H., Chida, M., Yoshizawa, Y., Higashi, K., Ohkawa, H., Mizutani, J., 1995, Phytochemistry 38, 609-613. suggested that the oxidation of 5-epi-aristolochene to capsidiol was mediated by at least one elicitor-inducible cytochrome P450 hydroxylase. In extending these observations, we developed an in vivo assay for 5-epi-aristolochene hydroxylase activity and used it to demonstrate a dose-dependent inhibition of activity by ancymidol and ketoconazole, two well characterized inhibitors of cytochrome P450 enzymes. Using degenerate oligonucleotide primers designed to the well conserved domains found within most P450 enzymes, including the heme binding domain, cDNA fragments representing four distinct P450 families (CYP71, CYP73, CYP82, and CYP92) were amplified from a cDNA library prepared against mRNA from elicitor-treated cells using PCR. The PCR fragments were subsequently used to isolate full-length cDNAs (CYP71D20 and D21, CYP73A27 and A28, CYP82E1 and CYP92A5), and these in turn were used to demonstrate that the corresponding mRNAs were all induced in elicitor-treated cells, albeit with different induction patterns. Representative, full-length cDNAs for each of the P450s were engineered into a yeast expression system, and the recombinant yeast assessed for functional expression of P450 protein by measuring the CO difference spectra of the yeast microsomes. Only microsomal preparations from yeast expressing the CYP71D20 and CYP92A5 cDNAs exhibited significant CO difference absorbance spectra at 450 nm and were thus tested for their ability to hydroxylate 5-epi-aristolochene and 1-deoxycapsidiol, a putative mono-hydroxylated intermediate in capsidiol biosynthesis. Interestingly, the CYP71D20-encoded enzyme activity was capable of converting both 5-epi-aristolochene and 1-deoxycapsidiol to capsidiol in vitro, consistent with the notion that this P450 enzyme catalyzes both hydroxylations of its hydrocarbon substrate.