Genetic and Environmental Influences on Language Ability in Older Adults: Findings from the Older Australian Twins Study

We used a sub-sample from the Older Australian Twins Study to estimate the heritability of performance on three tests of language ability: Boston Naming Test (BNT), Letter/Phonemic Fluency (FAS) and Category/Semantic Fluency (CFT) Tests. After adjusting for age, sex, education, mood, and global cognition (GC), heritability estimates obtained for the three tests were 0.35, 0.59, and 0.20, respectively. Multivariate analyses showed that the genetic correlation were high for BNT and CFT (0.61), but low for BNT and FAS (0.17), and for FAS and CFT (0.28). Genetic modelling with Cholesky decomposition indicated that the covariation between the three measures could be explained by a common genetic factor. Environmental correlations between the language ability measures were low, and there were considerable specific environmental influences for each measure. Future longitudinal studies with language performance and neuroimaging data can further our understanding of genetic and environmental factors involved in the process of cognitive aging.

Species composition of and fumonisin production by the Fusarium fujikuroi species complex isolated from Korean cereals

To assess the risk of fumonisin contamination in Korean cereals, we isolated colonies of the Fusarium fujikuroi species complex (FFSC) from barley, maize, rice and soybean samples from 2011 to 2015. A total of 878 FFSC strains were isolated mostly from maize and rice, and species identity of the isolates were determined using the DNA sequence of the translation elongation factor 1-α (TEF-1α) and RNA polymerase II (RPB2) genes. Fusaria recovered from Korean cereals included F. fujikuroi (317 isolates and a frequency of 36%), F. proliferatum (212 isolates and 24.1%), F. verticillioides (170 isolates and 19.4%), F. concentricum (86 strains and 9.8%), F. andiyazi (56 isolates and 6.4%), F. subglutinans (28 isolates and 3.2%), F. thapsinum (5 isolates and 0.6%), and F. circinatum (2 isolates and 0.2%). The rice samples were dominated by F. fujikuroi (47.4%), F. proliferatum (27.3%), and F. concentricum (15.1%), whereas maize samples were dominated by F. verticillioides (33.9%), F. fujikuroi (25.3%), and F. proliferatum (21.1%). A phylogenetic analysis of 70 representative isolates demonstrated that each species was resolved as genealogically exclusive in the ML tree. Fumonisin production potential was evaluated using a PCR assay for the fumonisin biosynthesis gene, FUM1 in all of the isolates. Most of the isolates tested (94%) were positive for FUM1. All of the isolates assigned to F. fujikuroi, F. proliferatum, F. verticillioides and F. thapsinum were positive for FUM1 irrespective of their host origin. Seventy-seven representative isolates positive for FUM1 were examined for fumonisin production in rice medium. The majority of F. proliferatum (26/27, 96.3%), F. verticillioides (16/17, 94.1%) and F. fujikuroi (19/25, 76.0%) produced both FB₁ and FB₂. Notably, 16 of 19 fumonisin-producing F. fujikuroi produced >1000μg/g of fumonisins (FB₁+FB₂) in rice medium, which is higher than that in previous reports. These results suggest that F. fujikuroi can produce high levels of fumonisins similar to F. verticillioides and F. proliferatum.

Chemosensitization of Fusarium graminearum to Chemical Fungicides Using Cyclic Lipopeptides Produced by Bacillus amyloliquefaciens Strain JCK-12

Fusarium head blight (FHB) caused by infection with Fusarium graminearum leads to enormous losses to crop growers, and may contaminate grains with a number of Fusarium mycotoxins that pose serious risks to human and animal health. Antagonistic bacteria that are used to prevent FHB offer attractive alternatives or supplements to synthetic fungicides for controlling FHB without the negative effects of chemical management. Out of 500 bacterial strains isolated from soil, Bacillus amyloliquefaciens JCK-12 showed strong antifungal activity and was considered a potential source for control strategies to reduce FHB. B. amyloliquefaciens JCK-12 produces several cyclic lipopeptides (CLPs) including iturin A, fengycin, and surfactin. Iturin A inhibits spore germination of F. graminearum. Fengycin or surfactin alone did not display any inhibitory activity against spore germination at concentrations less than 30 μg/ml, but a mixture of iturin A, fengycin, and surfactin showed a remarkable synergistic inhibitory effect on F. graminearum spore germination. The fermentation broth and formulation of B. amyloliquefaciens JCK-12 strain reduced the disease incidence of FHB in wheat. Furthermore, co-application of B. amyloliquefaciens JCK-12 and chemical fungicides resulted in synergistic in vitro antifungal effects and significant disease control efficacy against FHB under greenhouse and field conditions, suggesting that B. amyloliquefaciens JCK-12 has a strong chemosensitizing effect. The synergistic antifungal effect of B. amyloliquefaciens JCK-12 and chemical fungicides in combination may result from the cell wall damage and altered cell membrane permeability in the phytopathogenic fungi caused by the CLP mixtures and subsequent increased sensitivity of F. graminearum to fungicides. In addition, B. amyloliquefaciens JCK-12 showed the potential to reduce trichothecenes mycotoxin production. The results of this study indicate that B. amyloliquefaciens JCK-12 could be used as an available biocontrol agent or as a chemosensitizer to chemical fungicides for controlling FHB disease and as a strategy for preventing the contamination of harvested crops with mycotoxins.

Measurement of the Vector and Tensor Asymmetries at Large Missing Momentum in Quasielastic (e[over →],e^{'}p) Electron Scattering from Deuterium

We report the measurement of the beam-vector and tensor asymmetries A_{ed}^{V} and A_{d}^{T} in quasielastic (e[over →],e^{'}p) electrodisintegration of the deuteron at the MIT-Bates Linear Accelerator Center up to missing momentum of 500  MeV/c. Data were collected simultaneously over a momentum transfer range 0.1<Q^{2}<0.5  (GeV/c)^{2} with the Bates Large Acceptance Spectrometer Toroid using an internal deuterium gas target polarized sequentially in both vector and tensor states. The data are compared with calculations. The beam-vector asymmetry A_{ed}^{V} is found to be directly sensitive to the D-wave component of the deuteron and has a zero crossing at a missing momentum of about 320  MeV/c, as predicted. The tensor asymmetry A_{d}^{T} at large missing momentum is found to be dominated by the influence of the tensor force in the neutron-proton final-state interaction. The new data provide a strong constraint on theoretical models.

Characterization of Bacillus amyloliquefaciens DA12 Showing Potent Antifungal Activity against Mycotoxigenic Fusarium Species

In an attempt to develop a biological control agent against mycotoxigenic Fusarium species, we isolated Bacillus amyloliquefaciens strain DA12 from soil and explored its antimicrobial activities. DA12 was active against the growth of mycotoxigenic F. asiaticum, F. graminearum, F. proliferatum, and F. verticillioides both in vitro and in planta (maize). Further screening using dual culture extended the activity range of strain DA12 against other fungal pathogens including Botrytis cinerea, Colletotrichum coccodes, Endothia parasitica, Fusarium oxysporum, Raffaelea quercus-mongolicae, and Rhizoctonia solani. The butanol extract of the culture filtrate of B. amyloliquefaciens DA12 highly inhibited the germination of F. graminearum macroconidia with inhibition rate 83% at a concentration of 31.3 μg/ml and 100% at a concentration of 250 μg/ml. The antifungal metabolite from the butanol extract was identified as iturin A by thin layer chromatography-bioautography. In addition, volatile organic compounds produced by DA12 were able to inhibit mycelial growth of various phytopathogenic fungi. The volatile compounds were identified as 2-heptanone, 5-methyl heptanone and 6-methyl heptanone by gas chromatography-mass spectrometry (GC-MS) analysis. These results indicate that the antagonistic activity of Bacillus amyloliquefaciens DA12 was attributable to iturin A and volatile heptanones, and the strain could be used as a biocontrol agent to reduce the development of Fusarium diseases and mycotoxin contamination of crops.

Self-fertility in Chromocrea spinulosa is a consequence of direct repeat-mediated loss of MAT1-2, subsequent imbalance of nuclei differing in mating type, and recognition between unlike nuclei in a common cytoplasm

The filamentous fungus Chromocrea spinulosa (Trichoderma spinulosum) exhibits both self-fertile (homothallic) and self-sterile (heterothallic) sexual reproductive behavior. Self-fertile strains produce progeny cohorts that are 50% homothallic, 50% heterothallic. Heterothallic progeny can mate only with homothallic strains, and progeny also segregate 50% homothallic, 50% heterothallic. Sequencing of the mating type (MAT) region of homothallic and heterothallic strains revealed that both carry an intact MAT1-1 locus with three MAT1-1 genes (MAT1-1-1, MAT1-1-2, MAT1-1-3), as previously described for the Sordariomycete group of filamentous fungi. Homothallic strains, however, have a second version of MAT with the MAT1-2 locus genetically linked to MAT1-1. In this version, the MAT1-1-1 open reading frame is split into a large and small fragment and the truncated ends are bordered by 115bp direct repeats (DR). The MAT1-2-1 gene and additional sequences are inserted between the repeats. To understand the mechanism whereby C. spinulosa can exhibit both homothallic and heterothallic behavior, we utilized molecular manipulation to delete one of the DRs from a homothallic strain and insert MAT1-2 into a heterothallic strain. Mating assays indicated that: i) the DRs are key to homothallic behavior, ii) looping out of MAT1-2-1 via intra-molecular homologous recombination between the DRs in self-fertile strains results in two nuclear types in an individual (one carrying both MAT1-1 and MAT1-2 and one carrying MAT1-1 only), iii) self-fertility is achieved by inter-nuclear recognition between these two nuclear types before meiosis, iv) the two types of nuclei are in unequal proportion, v) having both an intact MAT1-1-1 and MAT1-2-1 gene in a single nucleus is not sufficient for self-fertility, and vi) the large truncated MAT1-1-1 fragment is expressed. Comparisons with MAT regions of Trichoderma reesei and Trichoderma virens suggest that several crossovers between misaligned parental MAT chromosomes may have led to the MAT architecture of homothallic C. spinulosa.

Fungi employ one of two mating tactics for sexual reproduction: self-sterile/heterothallic species can mate only with a genetically distinct partner while self-fertile/homothallic species do not require a partner. In ascomycetes, sexual reproduction is controlled by master regulators encoded by the mating-type (MAT) locus. The architecture of MAT differs in heterothallic versus homothallic species; heterothallics carry one of two forms (MAT1-1 or MAT1-2) per nucleus, whereas most homothallics carry both MAT forms in a single nucleus. There are intriguing exceptions. For example, the yeast models, Saccharomyces cerevisiae, and Schizosaccharomyces pombe undergo reversible MAT switching, not demonstrated in filamentous fungi. Here, we describe the mating mechanism in Chromocrea spinulosa (Trichoderma spinulosum), a filamentous ascomycete that exhibits both homothallic and heterothallic behavior. Self-fertile strains produce progeny cohorts that are 50% homothallic, 50% heterothallic. Self-sterile strains can mate only with homothallic strains, and when this occurs, homothallic and heterothallic progeny are also produced in a 1:1 ratio. By MAT sequencing and manipulation, we discovered unique MAT architecture and determined that self-fertility is achieved by deletion of MAT1-2 from most homothallic nuclei and subsequent inter-nuclear recognition between the resulting two, unevenly present, nuclear types in a common cytoplasm.

Circulating tumour cells as a biomarker for diagnosis and staging in pancreatic cancer

BACKGROUND

Current diagnosis and staging of pancreatic ductal adenocarcinoma (PDAC) has important limitations and better biomarkers are needed to guide initial therapy. We investigated the performance of circulating tumour cells (CTCs) as an adjunctive biomarker at the time of disease presentation.

METHODS

Venous blood (VB) was collected prospectively from 100 consecutive, pre-treatment patients with PDAC. Utilising the microfluidic NanoVelcro CTC chip, samples were evaluated for the presence and number of CTCs. KRAS mutation analysis was used to compare the CTCs with primary tumour tissue. CTC enumeration data was then evaluated as a diagnostic and staging biomarker in the setting of PDAC.

RESULTS

We found 100% concordance for KRAS mutation subtype between primary tumour and CTCs in all five patients tested. Evaluation of CTCs as a diagnostic revealed the presence of CTCs in 54/72 patients with confirmed PDAC (sensitivity=75.0%, specificity=96.4%, area under the curve (AUROC)=0.867, 95% CI=0.798-0.935, and P<0.001). Furthermore, a cut-off of ⩾3 CTCs in 4 ml VB was able to discriminate between local/regional and metastatic disease (AUROC=0.885; 95% CI=0.800-0.969; and P<0.001).

CONCLUSION

CTCs appear to function well as a biomarker for diagnosis and staging in PDAC.