Ubiquity of ice nucleation in lichen – possible atmospheric implications

Ice nucleation has previously been described in only a few lichens from a single location. Here we greatly extend this work and suggest that in lichens ice nucleation is a water harvesting adaption. Fifty-seven lichen samples from a variety of widespread locations were tested for ice nucleation by differential scanning calorimetry (DSC). Samples initiated freezing in the range –5.1° to –20°C and the median freezing temperature was –7.2°C. The vapour pressure difference between ice and water is significant at this temperature, and so ice grows at the expense of water (Bergeron–Findeisen process). Therefore, the ability to form ice at these temperatures provides a useful water-harvesting mechanism for lichens. Ice nucleation appears to be ubiquitous in lichens and is more likely to be associated with the mycobiont and may influence atmospheric processes

The benzodiazepine class of compounds as a potential for the treatment of cutaneous leishmaniasis

Cutaneous leishmaniasis is endemic in over 70 countries in the tropics and neotropics. Several Leishmania species are the causative agent of this form of the disease and are transmitted to humans and animals by a bite of a phlebotomies sandfly. Antileishmanial drugs including antimonials, Amphotericin B, pentamidine, paromomycin, allupurinol and miltefosine have been the treatment of choice over recent years. However, toxicity, difficulty of administration and emergence of resistance have limited the number of chemotherapeutic options available hence underlying the urgency for the identification of new classes of compounds with antileishmanial activity. The benzodiazepine class of compounds whose core structure entails the fusion of a benzene and diazepine ring have been used over the past 50 years as psychoactive drugs in the treatment of anxiety, insomnia and as an anticonvulsants. The aim of this study was to explore the antileishmanial effects of this class of compounds on stationary phase promastigotes of old and new world Leishmania species (L. aethiopica, L. major, L. tropica and L. mexicana) using the 3-(4,5-dimethylthiazol+2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium(MTS) assay for assessing parasite viability. An array of compounds with modifications brought about at the benzene and diazepine structures were tested over a range of concentrations over a 24-hour period for all species mentioned above. The three most active compounds (RRP223, RRP262 and RRP 199) displayed a different range of activity with inhibition of parasite growth at micromolar range in all 4 species. These findings implicate selective activity and demonstrate Leishmanicidal potential in the benzodiazepine class of compounds

Autism-associated CHD8 keeps proliferation of human neural progenitors in check by lengthening the G1 phase of the cell cycle

De novo mutations (DNMs) in chromodomain helicase DNA binding protein 8 (CHD8) are associated with a specific subtype of autism characterized by enlarged heads and distinct cranial features. The vast majority of these DNMs are heterozygous loss-of-function mutations with high penetrance for autism. CHD8 is a chromatin remodeler that preferentially regulates expression of genes implicated in early development of the cerebral cortex. How CHD8 haploinsufficiency alters the normal developmental trajectory of the brain is poorly understood and debated. Using long-term single-cell imaging, we show that disruption of a single copy of CHD8 in human neural precursor cells (NPCs) markedly shortens the G1 phase of the cell cycle. Consistent with faster progression of CHD8+/− NPCs through G1 and the G1/S checkpoint, we observed increased expression of E cyclins and elevated phosphorylation of Erk in these mutant cells – two central signaling pathways involved in S phase entry. Thus, CHD8 keeps proliferation of NPCs in check by lengthening G1, and mono-allelic disruption of this gene alters cell-cycle timing in a way that favors self-renewing over neurogenic cell divisions. Our findings further predict enlargement of the neural progenitor pool in CHD8+/− developing brains, providing a mechanistic basis for macrocephaly in this autism subtype

Using early feedback to start a conversation with students

Theme 5. You belong here: Strategies and practices to support all students in feeling they truly belong - Student voice approaches to ensure all voices are heard. Almost every student in HE will have experienced dissatisfaction with assessment outcomes during their degree. Arguably, this is an encouraging sign as it suggests learners are keen to perform well and, by extension, to learn. Nevertheless, a poor outcome can feed students’ feeling of inadequacy and of not belonging. We propose that when students are better equipped with assessment and feedback literacy, their learning experience remains a positive and inclusive one, independently from undesirable assessment outcomes. Our approach is to involve learners in the feedback cycle, provide opportunities to deliver, discuss and apply feedback, making sure their voice is heard

Bioconjugated solid lipid nanoparticles (SLNs) for targeted prostate cancer therapy

Prostate cancer is one of the prominent causes of cancer mortality in men all over the world and a challenge to treat. In this study, transferrin (Tf) bioconjugated solid lipid nanoparticles (SLNs) were developed and loaded with curcumin (CRC) for active targeting of prostate cancer cells. Curcumin is an anticancer agent, but its clinical applications are impeded due to the poor water solubility and bioavailability. Prepared blank Tf-SLNs showed minimal cytotoxicity while Tf-CRC-SLNs demonstrated significant in-vitro anti-proliferative activity compared to CRC-SLNs alone. Cellular uptake of Tf-CRC-SLNs were found to be significantly higher (p < 0.05/=0.01) compared to unconjugated SLNs or pure drug alone. Bioconjugated Tf-CRC-SLNs also showed improved early apoptotic and late apoptotic or early necrotic populations (6.4% and 88.9% respectively) to CRC-SLNs and CRC solution. Most importantly, in-vivo studies with Tf-CRC-SLNs in mice bearing prostate cancer revealed significant tumour regression (392.64 mm3 after 4 weeks, p < 0.001) compared to the control group. The findings of this work encourage future investigations and further in-vivo clinical studies on the potential of bioconjugated SLNs for cancer cure

Leishmania aethiopica cell‐to‐cell spreading involves caspase‐3, AkT, and NF‐κB but not PKC‐δ activation and involves uptake of LAMP‐1‐positive bodies containing parasites

Development of human leishmaniasis is dependent on the ability of intracellular Leishmania parasites to spread and enter macrophages. The mechanism through which free promastigotes and amastigotes bind and enter host macrophages has been previously investigated; however, little is known about intracellular trafficking and cell-to-cell spreading. In this study, the mechanism involved in the spreading of Leishmania aethiopica and Leishmania mexicana was investigated. A significant increase in phosphatidylserine (PS) exhibition, cytochrome C release, and active caspase-3 expression was detected (P < 0.05) during L. aethiopica, but not L. mexicana spreading. A decrease (P < 0.05) of protein kinase B (Akt) protein and BCL2-associated agonist of cell death (BAD) phosphorylation was also observed. The nuclear factor kappa-light-chain enhancer of activated B cells (NF-kB) signaling pathway and pro-apoptotic protein protein kinase C delta (PKC-δ) were downregulated while inhibition of caspase-3 activation prevented L. aethiopica spreading. Overall suggesting that L. aethiopica induces host cell’s apoptosis during spreading in a caspase-3-dependent manner. The trafficking of amastigotes within macrophages following cell-to-cell spreading differed from that of axenic parasites and involved co-localization with lysosomal-associated membrane protein 1 (LAMP-1) within 10 min postinfection. Interestingly, following infection with axenic amastigotes and promastigotes, co-localization of parasites with LAMP-1-positive structures took place at 1 and 4 h, respectively, suggesting that the membrane coat and LAMP-1 protein were derived from the donor cell. Collectively, these findings indicate that host cell apoptosis, demonstrated by PS exhibition, caspase-3 activation, cytochrome C release, downregulation of Akt, BAD phosphorylation, NF-kB activation, and independent of PKC-δ expression, is involved in L. aethiopica spreading. Moreover, L. aethiopica parasites associate with LAMP-rich structures when taken up by neighboring macrophages

Evaluation of 3D printability and biocompatibility of microfluidic resin for fabrication of solid microneedles

In this study, we have employed Digital Light Processing (DLP) printing technology for the fabrication of solid microneedle (MN) arrays. Several arrays with various geometries, such as cones, three-sided pyramids and four-sided pyramids, with different height to aspect ratios of 1:1, 2:1 and 3:1, were printed. Post-processing curing optimizations showed that optimal mechanical properties of the photocurable resin were obtained at 40 °C and 60 min. Ex vivo skin studies showed that piercing forces, penetration depth and penetration width were affected by the MN geometry and height to aspect ratio. Cone-shaped MNs required lower applied forces to penetrate skin and showed higher penetration depth with increasing height to aspect ratio, followed by three-sided and four-sided printed arrays. Cytotoxicity studies presented 84% cell viability of human fibroblasts after 2.5 h, suggesting the very good biocompatibility of the photocurable resin. Overall, DLP demonstrated excellent printing capacity and high resolution for a variety of MN designs

The challenges of teaching and learning during a pandemic become an opportunity: reflections on a student and academic partnership

The current pandemic has forced us to implement major changes in the way we communicate, interact and work, all of which have had a massive impact upon all aspects of our lives. Academics and students alike have had to adapt very quickly to the new situation and the challenges encountered, although viewed from different perspectives, are largely similar. Changes are often unsettling and taxing, especially when they are not the result of a personal choice, but they can also offer great opportunities, the most significant of which is for lecturers and learners to develop best practice together, in partnership (Kurczek and Johnson, 2014). This article reflects upon how sharing our experience of a students-and- staff partnership at the University of Greenwich 2021 SHIFT conference has affected our experience of teaching and learning during a pandemic

Systematic comparison of the functional physico-chemical characteristics and biocidal activity of microbial derived biosurfactants on blood-derived and breast cancer cells

Hypothesis The cytotoxicity of biosurfactants on cell membranes may be influenced by composition of their hydrophilic head and hydrophobic tails. It is hypothesised that they form mixed micelles which exert a detergent-like effect that disrupts the plasma membrane. The functional physico-chemical and biocidal characteristics of four biosurfactants were concurrently investigated to determine which of their structural characteristics may be tuned for greater efficacy. Experiments Rhamnolipid-95, rhamnolipid-90, surfactin and sophorolipid were characterised using FTIR, LC-MS, HPLC, surface tension and critical micelle concentration. Their biocidal activity against HEK 293, MCF-7 and THP-1 cell lines were investigated by MTT assay, using doxorubicin as cytotoxic control. Growth curves were established for all cell lines using trypan blue (TB) and MTT assays, corresponding doubling time (DT) and growth rate were obtained and compared. Findings HEK 293 cell-line had the highest growth rate amongst the three cell lines. For TB assay, growth of HEK 293 > THP-1 and for MTT, HEK 293 > MCF-7 while the DT was in the order of THP-1 > MCF-7 > HEK 293. Sophorolipid showed anti-proliferative activity comparable to doxorubicin on THP-1 > MCF-7 > HEK 293. THP-1 showed high sensitivity to sophorolipid with IC50 of 10.50, 25.58 and 6.78 (μg/ml) after 24, 48 and 72 hr respectively. However, sophorolipid was cytotoxic from 24-72 hr on HEK 293 cell lines with IC50 of 21.53, 40.57 and 27.53 μg/ml respectively. Although, doxorubicin showed higher anti-proliferative activity than all biosurfactants, it had poorer selectivity index for the same time durations compared to the biosurfactants. This indicates that biosurfactants were more effective for slowing the growth of the tested cancer cell lines and hence may be potential candidates for use in human cancer therapy. Physico-chemical characteristics of the biosurfactants suggest that their mechanism of action may be due to activity on the cell membrane

An in vitro evaluation of epigallocatechin gallate (eGCG) as a biocompatible inhibitor of ricin toxin

The catechin, epigallocatechin gallate (eGCG), found in green tea, has inhibitory activity against a number of protein toxins and was investigated in relation to its impact upon ricin toxin (RT) in vitro. The IC50 for RT was 0.08 ± 0.004 ng/mL whereas the IC50 for RT + 100 μM eGCG was 3.02 ± 0.572 ng/mL, indicating that eGCG mediated a significant (p < 0.0001) reduction in ricin toxicity. This experiment was repeated in the human macrophage cell line THP-1 and IC50 values were obtained for RT (0.54 ± 0.024 ng/mL) and RT + 100 μM eGCG (0.68 ± 0.235 ng/mL) again using 100 μM eGCG and was significant (p = 0.0013). The documented reduction in ricin toxicity mediated by eGCG was found to be eGCG concentration dependent, with 80 and 100 μg/mL (i.e. 178 and 223 μM respectively) of eGCG mediating a significant (p = 0.0472 and 0.0232) reduction in ricin toxicity at 20 and 4 ng/ml of RT in Vero and THP-1 cells (respectively). When viability was measured in THP-1 cells by propidium iodide exclusion (as opposed to the MTT assays used previously) 10 ng/mL and 5 ng/mL of RT was used. The addition of 1000 μM and 100 μM eGCG mediated a significant (p = 0.0015 and < 0.0001 respectively) reduction in ricin toxicity relative to an identical concentration of ricin with 1 μg eGCG. Further, eGCG (100 μM) was found to reduce the binding of RT B chain to lactose-conjugated Sepharose as well as significantly (p = 0.0039) reduce the uptake of RT B chain in Vero cells. This data suggests that eGCG may provide a starting point to refine biocompatible substances that can reduce the lethality of ricin