Epistatic gene effects on the yield of the parents of F1, F2, BC1 and BC2 progeny

The genetic analysis of 5 tomato hybrids (Danubius F₁, Luna F₁, Lido F₁, Balkan F₁ and Mi-10 F₁) was made. We produced their F₁, F₂, BC₁ and BC₂ generations and analysed their yield (on the first three flower branches) as well as some of the yield components of tomato fruits (mean fruit weight, mean fruit weight on the first flower branch, fruit length, fruit width, and number of locules). In order to estimate the gene effects, we applied the additive-dominance mode with three and six parameters. Epistatic gene effects were estimated by applying the six-parameter mode (Mather and Jinks 1982). As for yield and yield components, there were significant differences between the mean values of parents and their progeny. On the basis of the investigated genetic parameters, the obtained results suggested that the additive and dominance gene effects prevailed in the yield and yield components (Danubius F₁, Luna F₁, Lido F₁, Mi-10 F₁), whereas epistatic gene effects were excluded. As for the hybrid Balkan F₁, we recorded significant gene effects, both the additive and the dominance ones in the yield inheritance: additive x additive and dominance x dominance (with the negative sign). The estimated values of the epistatic gene effects were the most prominent in inheriting the feature average fruit weight on the first flower branch — additive x dominance gene effects. They represented the most frequent type of the interallele interaction recorded in the investigated hybrids.     

Serpentine ecotypic differentiation in a polyploid plant complex: shared tolerance to Mg and Ni stress among di- and tetraploid serpentine populations of <Emphasis Type="Italic">Knautia arvensis</Emphasis> (Dipsacaceae)

Background and aims

Serpentine soils impose limits on plant growth and survival and thus provide an ideal model for studying plant adaptation under environmental stress. Despite the increasing amount of data on serpentine ecotypic differentiation, no study has assessed the potential role of polyploidy. We tested for links between polyploidy and the response to serpentine stress in Knautia arvensis, a diploid-tetraploid, edaphically differentiated complex.

Methods

Variation in growth, biomass yield and tissue Mg and Ni accumulation in response to high Mg and Ni concentrations were experimentally tested using hydroponic cultivation of seedlings from eight populations of different ploidy and edaphic origin.

Results

Regardless of ploidy level, serpentine populations exhibited higher tolerance to both Mg and Ni stress than their non-serpentine counterparts, suggesting an adaptive character of these traits in K. arvensis. The effect of ploidy was rather weak and confined to a slightly better response of serpentine tetraploids to Mg stress and to higher biomass yields in tetraploids from both soil types.

Conclusions

The similar response of diploid and tetraploid serpentine populations to edaphic stress corresponded with their previously described genetic proximity. This suggests that serpentine tolerance might have been transmitted during the local autopolyploid origin of serpentine tetraploids.

     

Binding of ring-substituted indole-3-acetic acids to human serum albumin

The plant hormone, indole-3-acetic acid (IAA), and its ring-substituted derivatives have recently attracted attention as promising pro-drugs in cancer therapy. Here we present relative binding constants to human serum albumin for IAA and 34 of its derivatives, as obtained using the immobilized protein bound to a support suitable for high-performance liquid chromatography. We also report their octanol-water partition coefficients (logK(ow)) computed from retention data on a C(18) coated silica gel column. A four-parameter QSPR (quantitative structure-property relationships) model, based on physico-chemical properties, is put forward, which accounts for more than 96% of the variations in the binding affinities of these compounds. The model confirms the importance of lipophilicity as a global parameter governing interaction with serum albumin, but also assigns significant roles to parameters specifically related to the molecular topology of ring-substituted IAAs. Bulky substituents at ring-position 6 increase affinity, those at position 2 obstruct binding, while no steric effects were noted at other ring-positions. Electron-withdrawing substituents at position 5 enhance binding, but have no obvious effect at other ring positions.     

Structure-based inhibitor discovery against adenylyl cyclase toxins from pathogenic bacteria that cause anthrax and whooping cough

Edema factor (EF) and CyaA are adenylyl cyclase toxins secreted by pathogenic bacteria that cause anthrax and whooping cough, respectively. Using the structure of the catalytic site of EF, we screened a data base of commercially available, small molecular weight chemicals for those that could specifically inhibit adenylyl cyclase activity of EF. From 24 compounds tested, we have identified one quinazoline compound, ethyl 5-aminopyrazolo[1,5-a]quinazoline-3-carboxylate, that specifically inhibits adenylyl cyclase activity of EF and CyaA with approximately 20 microm Ki. This compound neither affects the activity of host resident adenylyl cyclases type I, II, and V nor exhibits promiscuous inhibition. The compound is a competitive inhibitor, consistent with the prediction that it binds to the adenine portion of the ATP binding site on EF. EF is activated by the host calcium sensor, calmodulin. Surface plasmon resonance spectroscopic analysis shows that this compound does not affect the binding of calmodulin to EF. This compound is dissimilar from a previously described, non-nucleoside inhibitor of host adenylyl cyclase. It may serve as a lead to design antitoxins to address the role of adenylyl cyclase toxins in bacterial pathogenesis and to fight against anthrax and whooping cough.     

Transformation of the naturally occurring frog skin peptide, alyteserin-2a into a potent, non-toxic anti-cancer agent

Alyteserin-2a (ILGKLLSTAAGLLSNL.NH₂) is a cationic, amphipathic α-helical cell-penetrating peptide, first isolated from skin secretions of the midwife toad Alytes obstetricans. Structure–activity relationships were investigated by synthesizing analogs of alyteserin-2a in which amino acids on the hydrophobic face of the helix were replaced by l-tryptophan and amino acids on the hydrophilic face were replaced by one or more l-lysine or d-lysine residues. The Trp-containing peptides display increased cytotoxic activity against non-small cell lung adenocarcinoma A549 cells (up to 11-fold), but hemolytic activity against human erythrocytes increases in parallel. The potency of the N15K analog against A549 cells (LC₅₀ = 13 μM) increases sixfold relative to alyteserin-2a and the therapeutic index (ratio of LC₅₀ for erythrocytes and tumor cells) increases twofold. Incorporation of a d-Lys¹¹ residue into the N15K analog generates a peptide that retains potency against A549 cells (LC₅₀ = 15 μM) but whose therapeutic index is 13-fold elevated relative to the native peptide. [G11k, N15K] alyteserin-2a is also active against human hepatocarcinoma HepG2 cells (LC₅₀ = 26 μM), breast adenocarcinoma MDA-MB-231 cells (LC₅₀ = 20 μM), and colorectal adenocarcinoma HT-29 cells (LC₅₀ = 28 μM). [G11k, N15K] alyteserin-2a, in concentrations as low as 1 μg/mL, significantly (P < 0.05) inhibits the release of the immune-suppressive cytokines IL-10 and TGF-β from unstimulated and concanavalin A-stimulated peripheral blood mononuclear cells. The data suggest a strategy of increasing the cationicity while reducing the helicity of naturally occurring amphipathic α-helical peptides to generate analogs with improved cytotoxicity against tumor cells but decreased activity against non-neoplastic cells.     

Multispeed genome diploidization and diversification after an ancient allopolyploidization

Hybridization and genome doubling (allopolyploidy) have led to evolutionary novelties as well as to the origin of new clades and species. Despite the importance of allopolyploidization, the dynamics of postpolyploid diploidization (PPD) at the genome level has been only sparsely studied. The Microlepidieae (MICR) is a crucifer tribe of 17 genera and c. 56 species endemic to Australia and New Zealand. Our phylogenetic and cytogenomic analyses revealed that MICR originated via an intertribal hybridization between ancestors of Crucihimalayeae (n = 8; maternal genome) and Smelowskieae (n = 7; paternal genome), both native to the Northern Hemisphere. The reconstructed ancestral allopolyploid genome (n = 15) originated probably in northeastern Asia or western North America during the Late Miocene (c. 10.6–7 million years ago) and reached the Australian mainland via long‐distance dispersal. In Australia, the allotetraploid genome diverged into at least three main subclades exhibiting different levels of PPD and diversity: 1.25‐fold descending dysploidy (DD) of n = 15 → n = 12 (autopolyploidy → 24) in perennial Arabidella (3 species), 1.5‐fold DD of n = 15 → n = 10 in the perennial Pachycladon (11 spp.) and 2.1–3.75‐fold DD of n = 15 → n = 7–4 in the largely annual crown‐group genera (42 spp. in 15 genera). These results are among the first to demonstrate multispeed genome evolution in taxa descending from a common allopolyploid ancestor. It is suggested that clade‐specific PPD can operate at different rates and efficacies and can be tentatively linked to life histories and the extent of taxonomic diversity.     

Local, among-site, and regional diversity patterns of benthic macroinvertebrates in high altitude waterbodies: do ponds differ from lakes?

In this study we aimed at comparing invertebrate diversity of high altitude lakes and ponds along hierarchical spatial scales. We compared local, among-site, and regional diversity of benthic macroinvertebrates in 25 ponds and 34 lakes in the Tatra Mountains, central Europe. The ponds showed significantly lower local diversity, higher among-site diversity and similar regional diversity than the lakes. The species–area relationships (SAR), habitat heterogeneity, and environmental harshness are assumed as drivers for the local diversity patterns. An ecological threshold separating pond and lake systems emerged at an area of 2 ha, where the SAR pattern changed significantly. Differences in species turnover between these systems were likely driven by greater environmental variability and isolation of the ponds. High altitude ponds neither significantly support greater regional diversity nor higher number of unique taxa than lakes. The higher among-site diversity of ponds relative to lakes highlights the relevance of ponds for regional diversity in mountain areas.     

Cytopathology of Apple stem pitting virus in Nicotiana occidentalis L.

Apple stem pitting virus (ASPV) is a causal agent of stem pitting associated disease in pomes fruit trees. The present report focuses on a cytopathological effect of ASPV infection in a herbaceous host Nicotiana occidentalis ‘37B’. A leaf dip preparation shows predominantly basic virus particles and aggregated particles 800 nm and 3200 nm long respectively. The main cytopathological effect observed in ASPV infected N. occidentalis includes fibrous aggregates of virus particles (massive/or few), formation of membranous vesicles and proliferation of the endoplasmic reticulum.     

Susceptibility of Prussian carp infected by metacercariae of Posthodiplostomum cuticola (v. Nordmann, 1832) to fish predation

The susceptibility of prey fish infected by metacercariae of Posthodiplostomum cuticola (Digenea: Diplostomatidae) to the predation of non-host predators under experimental conditions was investigated. Parasitized young-of-the-year Prussian carp Carassius auratus were consumed significantly more often by perch Perca fluviatilis compared to non-parasitized individuals, independent of Prussian carp density. The proportion of parasitized and non-parasitized fish consumed by the predator remained stable at four different prey densities. The probability of predation did not increase with the intensity of parasite infection. The effect of P. cuticola on the host seems to result mostly from pathological changes (poor condition, black spots). However, our results provide evidence of higher probability of parasitized Prussian carp being consumed by fish predators under experimental conditions.     

An Efficient and Comprehensive Strategy for Genetic Diagnostics of Polycystic Kidney Disease

Renal cysts are clinically and genetically heterogeneous conditions. Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent life-threatening genetic disease and mainly caused by mutations in PKD1. The presence of six PKD1 pseudogenes and tremendous allelic heterogeneity make molecular genetic testing challenging requiring laborious locus-specific amplification. Increasing evidence suggests a major role for PKD1 in early and severe cases of ADPKD and some patients with a recessive form. Furthermore it is becoming obvious that clinical manifestations can be mimicked by mutations in a number of other genes with the necessity for broader genetic testing. We established and validated a sequence capture based NGS testing approach for all genes known for cystic and polycystic kidney disease including PKD1. Thereby, we demonstrate that the applied standard mapping algorithm specifically aligns reads to the PKD1 locus and overcomes the complication of unspecific capture of pseudogenes. Employing careful and experienced assessment of NGS data, the method is shown to be very specific and equally sensitive as established methods. An additional advantage over conventional Sanger sequencing is the detection of copy number variations (CNVs). Sophisticated bioinformatic read simulation increased the high analytical depth of the validation study and further demonstrated the strength of the approach. We further raise some awareness of limitations and pitfalls of common NGS workflows when applied in complex regions like PKD1 demonstrating that quality of NGS needs more than high coverage of the target region. By this, we propose a time- and cost-efficient diagnostic strategy for comprehensive molecular genetic testing of polycystic kidney disease which is highly automatable and will be of particular value when therapeutic options for PKD emerge and genetic testing is needed for larger numbers of patients.