Population genetic analysis of a medicinally significant Australian rainforest tree, Fontainea picrosperma C.T. White (Euphorbiaceae): biogeographic patterns and implications for species domestication and plantation establishment

Background: Fontainea picrosperma, a subcanopy tree endemic to the rainforests of northeastern Australia, is of medicinal significance following the discovery of the novel anti-cancer natural product, EBC-46. Laboratory synthesis of EBC-46 is unlikely to be commercially feasible and consequently production of the molecule is via isolation from F. picrosperma grown in plantations. Successful domestication and plantation production requires an intimate knowledge of a taxon’s life-historyattributes and genetic architecture, not only to ensure the maximum capture of genetic diversity from wild source populations, but also to minimise the risk of a detrimental loss in genetic diversity via founder effects during subsequent breeding programs designed to enhance commercially significant agronomic traits. Results: Here we report the use of eleven microsatellite loci (PIC = 0.429; PID = 1.72 × 10−6 ) to investigate the partitioning of genetic diversity within and among seven natural populations of F. picrosperma. Genetic variation among individuals and within populations was found to be relatively low (A = 2.831; HE = 0.407), although there was marked differentiation among populations (PhiPT = 0.248). Bayesian, UPGMA and principal coordinates analyses detected three main genotypic clusters (K = 3), which were present at all seven populations. Despite low levels of historical gene flow (Nm = 1.382), inbreeding was negligible (F = -0.003); presumably due to the taxon’s dioecious breeding system. Conclusion: The data suggests that F. picrosperma was previously more continuously distributed, but that rainforest contraction and expansion in response to glacial-interglacial cycles, together with significant anthropogenic effects have resulted in significant fragmentation. This research provides important tools to support plantation establishment, selection and genetic improvement of this medicinally significant Australian rainforest species

Antiproliferative activity of PEP005, a novel ingenol angelate that modulates PKC functions, alone and in combination with cytotoxic agents in human colon cancer cells

PEP005 is a novel ingenol angelate that modulates protein kinases C (PKC) functions by activating PKCδ and inhibiting PKCα. This study assessed the antiproliferative effects of PEP005 alone and in combination with several other anticancer agents in a panel of 10 human cancer cell lines characterised for expression of several PKC isoforms. PEP005 displayed antiproliferative effects at clinically relevant concentrations with a unique cytotoxicity profile that differs from that of most other investigated cytotoxic agents, including staurosporine. In a subset of colon cancer cells, the IC50 of PEP005 ranged from 0.01–140 μM. The antiproliferative effects of PEP005 were shown to be concentration- and time-dependent. In Colo205 cells, apoptosis induction was observed at concentrations ranging from 0.03 to 3 μM. Exposure to PEP005 also induced accumulation of cells in the G1 phase of the cell cycle. In addition, PEP005 increased the phosphorylation of PKCδ and p38. In Colo205 cells, combinations of PEP005 with several cytotoxic agents including oxaliplatin, SN38, 5FU, gemcitabine, doxorubicin, vinorelbine, and docetaxel yielded sequence-dependent antiproliferative effects. Cell cycle blockage induced by PEP005 in late G1 lasted for up to 24 h and therefore a 24 h lag-time between PEP005 and subsequent exposure to cytotoxics was required to optimise PEP005 combinations with several anticancer agents. These data support further evaluation of PEP005 as an anticancer agent and may help to optimise clinical trials with PEP005-based combinations in patients with solid tumours

Transcriptional control and the role of silencers in transcriptional regulation in eukaryotes.

Mechanisms controlling transcription and its regulation are fundamental to our understanding of molecular biology and, ultimately, cellular biology. Our knowledge of transcription initiation and integral factors such as RNA polymerase is considerable, and more recently our understanding of the involvement of enhancers and complexes such as holoenzyme and mediator has increased dramatically. However, an understanding of transcriptional repression is also essential for a complete understanding of promoter structure and the regulation of gene expression. Transcriptional repression in eukaryotes is achieved through 'silencers', of which there are two types, namely 'silencer elements' and 'negative regulatory elements' (NREs). Silencer elements are classical, position-independent elements that direct an active repression mechanism, and NREs are position-dependent elements that direct a passive repression mechanism. In addition, 'repressors' are DNA-binding trasncription factors that interact directly with silencers. A review of the recent literature reveals that it is the silencer itself and its context within a given promoter, rather than the interacting repressor, that determines the mechanism of repression. Silencers form an intrinsic part of many eukaryotic promoters and, consequently, knowledge of their interactive role with enchancers and other transcriptional elements is essential for our understanding of gene regulation in eukaryotes

PEP005 (ingenol mebutate) gel, a novel agent for the treatment of actinic keratosis: Results of a randomized, double-blind, vehicle-controlled, multicentre, phase IIa study

The sap of the plant Euphorbia peplus is a traditional remedy for skin conditions, including actinic keratosis. The active constituent of the sap is ingenol mebutate (ingenol-3-angelate), formerly known as PEP005. This randomized, double-blind, vehicle-controlled, phase IIa study investigated the safety (and secondarily the efficacy) of two applications of ingenol mebutate gel in 58 patients with biopsy-confirmed actinic keratosis. Five preselected lesions were treated with ingenol mebutate gel, 0.0025%, 0.01% or 0.05%, or vehicle gel, on days 1 and 2 (Arm A) or days 1 and 8 (Arm B). There were no significant differences in tolerability or efficacy between Arms A and B. Treatment was well tolerated. The most common local skin responses were dose-related erythema, flaking/scaling/dryness and scabbing/crusting. Efficacy was greatest with ingenol mebutate gel, 0.05%, which resulted in complete clinical clearance of 71% of treated lesions (P < 0.0001 vs vehicle gel). In addition, 67% of patients treated with ingenol mebutate gel, 0.05% had clinical clearance of at least four of five treated lesions (P = 0.0185 vs vehicle gel). Ingenol mebutate gel is being developed as a short-course topical therapy for actinic keratosis and non-melanoma skin cancer

Seeing the forest through the trees: Applications of species distribution models across an Australian biodiversity hotspot for threatened rainforest species of Fontainea

Southern Fontainea (Fontainea australis) and Coastal Fontainea (F. oraria) are two closely-related, rare plant species endemic to the subtropical rainforests of central, eastern Australia. Both species have threatened conservation status, with their contemporary and projected distribution poorly known. We aimed to use species distribution models (SDMs) to identify (1) the potential range under current conditions, (2) suitable habitat area conserved in protected areas and (3) responses under future environmental conditions of the species. Using a presence-pseudo-absence approach, and a set of bioclimatic variables, combined with topographic factors, we modelled the spatial dynamics of Southern Fontainea and Coastal Fontainea. We present comparisons among regression (GLM) and Random Forest (RF) SDMs for current and projected future conditions under low (SSP 1–2.6) and high (SSP 5–8.5) emission scenarios for the period 2081–2100 from an ensemble of three CMIP6 climate models. On-ground surveys verified the contemporary distribution of Southern Fontainea across the study extent. GLM-and RF-based models identified similar areas of suitable habitat under current conditions, but both models indicated that less than half of the suitable Southern Fontainea habitat is under protected tenure. GLM-based SDMs suggest an expansion of suitable areas of Southern and Coastal Fontainea under both low-and high-emission climate projections. By contrast, RF-based SDMs indicated a severe decline of suitable habitat under future climate projections. The steep slopes and gullies of the mountain ranges, which span the Queensland and New South Wales border of central, eastern Australia, seem likely to provide long-term, stable climate refugia for Southern Fontainea. Models generated under current conditions identified novel areas that could support undiscovered populations of Southern and Coastal Fontainea. These findings have significant conservation implications for the critically endangered Coastal Fontainea, which is projected to lose suitable habitat under a high-emission climate scenario

Boron Effects on Fruit Set, Yield, Quality and Paternity of Hass Avocado

Boron plays a critical role in pollination and fertilization and can affect fruit set and yield. We applied 0 g, 15 g (manufacturer recommendation) or 30 g boron pre-flowering to Hass avocado trees to determine the effects on fruit set, fruitlet paternity, yield, fruit size, mineral nutrient concentrations and fatty acid composition. The boron applications did not significantly affect the initial fruit set at 3 or 6 weeks after peak anthesis or the proportions of self-pollinated fruitlets or mature fruit. Approximately 88–92% of the mature fruit were self-pollinated. However, applying 30 g boron per tree reduced the fruit set at 10 weeks after peak anthesis by 56% and the final yield by 25%. Attaining > 90% of the maximum yield was associated with foliar boron concentrations being below 104 mg/kg at 6 weeks after peak anthesis and between 39 and 68 mg/kg at 28 weeks after peak anthesis. Applying 15 g boron per tree increased the fruit mass by 5%, fruit diameter by 2%, flesh mass by 9%, flesh boron concentration by 55%, and the relative abundance of unsaturated fatty acids by 1% compared with control trees. Applying the recommended amount of boron provided a good yield of high-quality avocado fruit but applying boron at double the recommended rate reduced the yield