Phylogeny of Greya (Lepidoptera: Prodoxidae), based on nucleotide sequence variation in mitochondrial cytochrome oxidase I and II: congruence with morphological data

The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from nucleotide sequence variation across a 765-bp region in the cytochrome oxidase I and II genes of the mitochondrial genome. Most parsimonious relationships of 25 haplotypes from 16 Greya species and two outgroup genera (Tetragma and Prodoxus) showed substantial congruence with the species relationships indicated by morphological variation. Differences between mitochondrial and morphological trees were found primarily in the positions of two species, G. variabilis and G. pectinifera, and in the branching order of the three major species groups in the genus. Conflicts between the data sets were examined by comparing levels of homoplasy in characters supporting alternative hypotheses. The phylogeny of Greya species suggests that host-plant association at the family level and larval feeding mode are conservative characters. Transition/transversion ratios estimated by reconstruction of nucleotide substitutions on the phylogeny had a range of 2.0-9.3, when different subsets of the phylogeny were used. The decline of this ratio with the increase in maximum sequence divergence among taxa indicates that transitions are masked by transversions along deeper internodes or long branches of the phylogeny. Among transitions, substitutions of A-->G and T-->C outnumbered their reciprocal substitutions by 2-6 times, presumably because of the approximately 4:1 (77%) A+T-bias in nucleotide base composition. Of all transversions, 73%-80% were A<-->T substitutions, 85% of which occurred at third positions of codons; these estimates did not decrease with an increase in maximum sequence divergence of taxa included in the analysis. The high frequency of A<-->T substitutions is either a reflection or an explanation of the 92% A+T bias at third codon positions.      

Effects of artificial shade on attack by the mahogany shoot borer, Hypsipyla robusta (Moore)

Abstract

• 1 Swietenia macrophylla King (Meliaceae: Swietenioideae) provides one of the premier timbers of the world. The mahogany shoot borer Hypsipyla robusta Moore (Lepidoptera: Pyralidae) is an economically important pest of S. macrophylla throughout Asia, Africa and the Pacific. No viable method of controlling this pest is known. Previous observations have suggested that the presence of overhead shade may reduce attack by H. robusta, but this has not been investigated experimentally. This research was therefore designed to assess the influence of light availability on shoot‐borer attack on S. macrophylla, by establishing seedlings under three different artificial shade regimes, then using these seedlings to test oviposition preference of adult moths, neonate larval survival and growth and development of shoot borer larvae.
• 2 Oviposition preference of shoot borer moths was tested on leaves from seedlings grown under artificial shade for 63 weeks. A significant difference in choice was recorded between treatments, with 27.4 ± 1.5 eggs laid under high shade and 87.1 ± 1.8 under low shade.
• 3 Neonate larval survival on early flushing leaflets of S. macrophylla did not differ significantly between shade treatments. Larval growth rate, estimated by measuring daily frass width, was significantly higher for those larvae fed on seedlings from the high and medium shade treatments (0.1 mm/day), than the low shade treatment (0.06 mm/day). In laboratory‐reared larvae, the total mass of frass produced was significantly higher in the high shade treatment (0.4 g) than under the low shade treatment (0.2 g).
• 4 Longer tunnel lengths were bored by larvae in plants grown under high shade (12.0 ± 2.4 cm) than under low shade (7.07 ± 1.9 cm). However, pupal mass under low shade was 48% higher than that under the high shade treatment, suggesting that plants grown under high shade were of lower nutritional quality for shoot borer larvae.
• 5 These results indicate that shading of mahogany seedlings may reduce the incidence of shoot borer attack, by influencing both oviposition and larval development. The establishment of mahogany under suitable shade regimes may therefore provide a basis for controlling shoot borer attack using silvicultural approaches.

     

Analysis of plastid DNA-like sequences within the nuclear genomes of higher plants

A wide-ranging examination of plastid (pt)DNA sequence homologies within higher plant nuclear genomes (promiscuous DNA) was undertaken. Digestion with methylation-sensitive restriction enzymes and Southern analysis was used to distinguish plastid and nuclear DNA in order to assess the extent of variability of promiscuous sequences within and between plant species. Some species, such as Gossypium hirsutum (cotton), Nicotiana tabacum (tobacco), and Chenopodium quinoa, showed homogenity of these sequences, while intraspecific sequence variation was observed among different cultivars of Pisum sativum (pea), Hordeum vulgare (barley), and Triticum aestivum (wheat). Hypervariability of plastid sequence homologies was identified in the nuclear genomes of Spinacea oleracea (spinach) and Beta vulgaris (beet), in which individual plants were shown to possess a unique spectrum of nuclear sequences with ptDNA homology. This hypervariability apparently extended to somatic variation in B. vulgaris. No sequences with ptDNA homology were identified by this method in the nuclear genome of Arabidopsis thaliana.      

Raloxifene and desmethylarzoxifene block estrogen-induced malignant transformation of human breast epithelial cells

There is association between exposure to estrogens and the development and progression of hormone-dependent gynecological cancers. Chemical carcinogenesis by catechol estrogens derived from oxidative metabolism is thought to contribute to breast cancer, yet exact mechanisms remain elusive. Malignant transformation was studied in MCF-10A human mammary epithelial cells, since estrogens are not proliferative in this cell line. The human and equine estrogen components of estrogen replacement therapy (ERT) and their catechol metabolites were studied, along with the influence of co-administration of selective estrogen receptor modulators (SERMs), raloxifene and desmethyl-arzoxifene (DMA), and histone deacetylase inhibitors. Transformation was induced by human estrogens, and selectively by the 4-OH catechol metabolite, and to a lesser extent by an equine estrogen metabolite. The observed estrogen-induced upregulation of CYP450 1B1 in estrogen receptor negative MCF-10A cells, was compatible with a causal role for 4-OH catechol estrogens, as was attenuated transformation by CYP450 inhibitors. Estrogen-induced malignant transformation was blocked by SERMs correlating with a reduction in formation of nucleobase catechol estrogen (NCE) adducts and formation of 8-oxo-dG. NCE adducts can be formed consequent to DNA abasic site formation, but NCE adducts were also observed on incubation of estrogen quinones with free nucleotides. These results suggest that NCE adducts may be a biomarker for cellular electrophilic stress, which together with 8-oxo-dG as a biomarker of oxidative stress correlate with malignant transformation induced by estrogen oxidative metabolites. The observed attenuation of transformation by SERMs correlated with these biomarkers and may also be of clinical significance in breast cancer chemoprevention.     

Click synthesis of estradiol–cyclodextrin conjugates as cell compartment selective estrogens

Cyclodextrin (CD) is a well known drug carrier and excipient for enhancing aqueous solubility. CDs themselves are anticipated to have low membrane permeability because of relatively high hydrophilicity and molecular weight. CD derivatization with 17-beta estradiol (E₂) was explored extensively using a number of different click chemistries and the cell membrane permeability of synthetic CD–E₂ conjugate was explored by cell reporter assays and confocal fluorescence microscopy. In simile with reported dendrimer–E₂ conjugates, CD–E₂ was found to be a stable, extranuclear receptor selective estrogen that penetrated into the cytoplasm.     

Stability of microbubbles prepared by co-axial electrohydrodynamic atomisation

Previous studies have indicated that microbubbles prepared by co-axial electrohydrodynamic atomisation (CEHDA) are less stable than those prepared by other methods such as sonication and microfluidic techniques. The aim of this investigation was to determine the reasons for this observation and how this might be addressed in future work. Microbubbles were prepared by CEHDA using (i) a glycerol–air system, (ii) a glycerol–Tween 80–air system and (iii) a glycerol–zirconia–air system and also by simple agitation of (i) and (ii), in order to compare the effect upon the dissolution rate of microbubbles of different materials and processing methods. Both theoretical examination and the experimental results indicated that all three quantities were important in controlling the rate of microbubble dissolution, namely: surface tension at the gas/liquid interface, the effective diffusivity of gas through this interface and the initial concentration of gas dissolved in the surrounding liquid. However, it was the difference in gas concentration in the surrounding liquid that was indicated as the primary reason for the differences in stability observed with different processing methods. It was concluded, therefore, that improved stability could be achieved for microbubbles prepared using CEHDA by saturating the collecting fluid with gas and/or maintaining a high concentration of microbubbles during collection.

Assessing the Impacts of Agrobiodiversity Maintenance on Food Security Among Farming Households in Sri Lanka’s Dry Zone

Farmers’ maintenance of agrobiodiversity is fundamental to global food security, particularly in a world increasingly affected by climate change. Biodiversity helps to buffer agroecosystems from stresses like climatic variability, and the crop genetic diversity conserved with biodiverse agroecosystems is critical for plant breeding both locally and globally. Yet, despite these benefits, few studies have directly assessed the implications of household–level agrobiodiversity maintenance on household food security. Drawing on survey data collected in Sri Lanka’s Hambantota District, we evaluated the plant diversity maintained by small–scale farming households in both homegardens and crop fields and determined the relationships between this diversity and their households’ food security. We also considered how a suite of additional demographic, household, community, and farm characteristics relate to both the plant diversity maintained by a household and their food security. Similar to previous studies, the age of the agricultural decision-maker and the age and size of households’ homegardens positively correlated with the overall species richness of farming systems. Older homegardens were also identified to be more evenly distributed in their species abundance, and market–oriented households had significantly higher species richness but lower Shannon Indices. Most notably, household socioeconomic status and material wealth were important to both agrobiodiversity maintenance and household food security, while no significant relationships between species richness and food security measures were detected. These findings suggest that effort aiming to increase the food security of small–scale farming households in Sri Lanka, and elsewhere, should target those farming households with a paucity of socioeconomic assets, as these households lack both agroecological and economic resources to overcome shocks, such as those associated with climate change.     

Selective modulation of amyloid-β peptide degradation by flurbiprofen, fenofibrate, and related compounds regulates Aβ levels

Gamma‐secretase modulators (GSMs) include selected non‐steroidal anti‐inflammatory drugs such as flurbiprofen that selectively lowers the neurotoxic amyloid‐β peptide Aβ_1–42. GSMs are attractive targets for Alzheimer’s disease, in contrast to ‘inverse GSMs,’ such as fenofibrate, which selectively increase the level of Aβ_1–42. A methodology for screening of Aβ modulating drugs was developed utilizing an Aβ‐producing neuroblastoma cell line stably transfected with mutant human amyloid precursor protein, immunoprecipitation of Aβ peptides, and mass spectroscopic quantitation of Aβ_1–37/Aβ_1–38/Aβ_1–40/Aβ_1–42 using an Aβ internal standard. The unexpected conclusion of this work was that in this system, drug effects are independent of γ‐secretase. The methodology recapitulated reported results for modulation of Aβ by GSMs. However, control experiments in which exogenous Aβ_1–40/Aβ_1–42 was added (i) to drug‐treated wild‐type cells or (ii) to conditioned media from these wild‐type cells, gave comparable patterns of Aβ modulation. These results, suggesting that drugs modulate the ability of cell‐derived factors to degrade Aβ, was interrogated by adding protease inhibitors and performing molecular weight cut‐off fractionation. The results confirmed that modulation of Aβ_1–40/Aβ_1–42 was mediated by selective proteolysis. Treatment of N2a cells with flurbiprofen or fenofibric acid selectively enhanced Aβ_1–42 clearance by extracellular proteolysis; treatment with HCT‐1026 or fenofibrate (esters of flurbiprofen and fenobric acid) inhibited clearance of Aβ_1–40 and Aβ_1–42.