Sphingolipidomics of drug resistant Candida auris clinical isolates reveal distinct sphingolipid species signatures

Independent studies from our group and others have provided evidence that sphingolipids (SLs) influence the antimycotic susceptibility of Candida species. We analyzed the molecular SL signatures of drug-resistant clinical isolates of Candida auris, which have emerged as a global threat over the last decade. This included Indian hospital isolates of C. auris, which were either resistant to fluconazole (FLC^R) or amphotericin B (AmB^R) or both drugs. Relative to Candida glabrata and Candida albicans strains, these C. auris isolates were susceptible to SL pathway inhibitors such as myriocin and aureobasidin A, suggesting that SL content may influence azole and AmB susceptibilities. Our analysis of SLs confirmed the presence of 140 SL species within nine major SL classes, namely the sphingoid bases, Cer, αOH-Cer, dhCer, PCer, αOH-PCer, αOH-GlcCer, GlcCer, and IPC. Other than for αOH-GlcCer, most of the SLs were found at higher concentrations in FLC^R isolates as compared to the AmB^R isolates. SLs were at intermediate levels in FLC^R + AmB^R isolates. The observed diversity of molecular species of SL classes based on fatty acyl composition was further reflected in their distinct specific imprint, suggesting their influence in drug resistance. Together, the presented data improves our understanding of the dynamics of SL structures, their synthesis, and link to the drug resistance in C. auris.     

Palmitate exacerbates bisphenol A toxicity via induction of ER stress and mitochondrial dysfunction

Combined exposure to dietary nutrients and environmental chemicals may elicit significantly different physiological effects than single exposures. Exposure to dietary saturated fats and environmental toxins is a physiologically-significant dual exposure that is particularly associated with lower socioeconomic status, potentially placing these individuals at heightened risk of xenobiotic toxicities. However, no prior studies have examined interactions between specific lipids and environmental xenobiotics in modulating cellular health. Using primary mouse embryonic fibroblasts, we have discovered that prior exposure to the saturated fatty acid, palmitate, exacerbates cellular toxicity associated with the industrial plasticizer, bisphenol A (BPA). Cell death upon BPA exposure following palmitate pre-treatment was greater than that occurring with either exposure alone. Mechanistically, cell death was preceded by increased endoplasmic reticulum stress and loss of mitochondrial membrane potential in palmitate plus BPA exposed cells, leading to increased caspase-3 cleavage and subsequent apoptosis. Interestingly, inclusion of the unsaturated fatty acid, oleate, along with palmitate during the pre-treatment period completely abrogated the ER stress, mitochondrial toxicity, and cell death induced by subsequent exposure to BPA. Thus, our data identify for the first time an important interaction between a fatty acid and an environmental toxin and have implications for developing nutritional interventions to mitigate the deleterious effects of such xenobiotic exposures.     

Biogenic nanoporous silicon carrier improves the efficacy of buparvaquone against resistant visceral leishmaniasis

Visceral leishmaniasis is a vector-borne protozoan infection that is fatal if untreated. There is no vaccination against the disease, and the current chemotherapeutic agents are ineffective due to increased resistance and severe side effects. Buparvaquone is a potential drug against the leishmaniases, but it is highly hydrophobic resulting in poor bioavailability and low therapeutic efficacy. Herein, we loaded the drug into silicon nanoparticles produced from barley husk, which is an agricultural residue and widely available. The buparvaquone-loaded nanoparticles were several times more selective to kill the intracellular parasites being non-toxic to macrophages compared to the pure buparvaquone and other conventionally used anti-leishmanial agents. Furthermore, the in vivo results revealed that the intraperitoneally injected buparvaquone-loaded nanoparticles suppressed the parasite burden close to 100%. By contrast, pure buparvaquone suppressed the burden only by 50% with corresponding doses. As the conclusion, the biogenic silicon nanoparticles are promising carriers to significantly improve the therapeutic efficacy and selectivity of buparvaquone against resistant visceral leishmaniasis opening a new avenue for low-cost treatment against this neglected tropical disease threatening especially the poor people in developing nations.     

Inheritance and molecular mapping of a gibberellin-insensitive dwarf mutant in groundnut (<Emphasis Type="Italic">Arachis hypogaea</Emphasis> L.)

A dark green dwarf mutant, TGM 167, was isolated from a gamma ray + sodium azide mutagenised population of cultivated groundnut breeding line, TFDRG 5. The mutant had a 45.8% reduction in height due to its shorter internodal length. Further, it was found to be insensitive towards exogenous GA₃ application, although it had nearly the same level of endogenous GA₃ as the parent. Genetic analysis revealed that the dwarfism is under the control of a single dominant gene. This dominant dwarfing gene was mapped with an SSR marker TC3H02 at a distance of 9.7 cM.     

Allergenicity assessment of Allium sativum leaf agglutinin, a potential candidate protein for developing sap sucking insect resistant food crops

Background

Mannose-binding Allium sativum leaf agglutinin (ASAL) is highly antinutritional and toxic to various phloem-feeding hemipteran insects. ASAL has been expressed in a number of agriculturally important crops to develop resistance against those insects. Awareness of the safety aspect of ASAL is absolutely essential for developing ASAL transgenic plants.

Methodology/Principal Findings

Following the guidelines framed by the Food and Agriculture Organization/World Health Organization, the source of the gene, its sequence homology with potent allergens, clinical tests on mammalian systems, and the pepsin resistance and thermostability of the protein were considered to address the issue. No significant homology to the ASAL sequence was detected when compared to known allergenic proteins. The ELISA of blood sera collected from known allergy patients also failed to show significant evidence of cross-reactivity. In vitro and in vivo assays both indicated the digestibility of ASAL in the presence of pepsin in a minimum time period.

Conclusions/Significance

With these experiments, we concluded that ASAL does not possess any apparent features of an allergen. This is the first report regarding the monitoring of the allergenicity of any mannose-binding monocot lectin having insecticidal efficacy against hemipteran insects.     

Options for active case detection of visceral leishmaniasis in endemic districts of India, Nepal and Bangladesh, comparing yield, feasibility and costs

Background

The VL elimination strategy requires cost-effective tools for case detection and management. This intervention study tests the yield, feasibility and cost of 4 different active case detection (ACD) strategies (camp, index case, incentive and blanket approach) in VL endemic districts of India, Nepal and Bangladesh.

Methodology/Principal Findings

First, VL screening (fever more than 14 days, splenomegaly, rK39 test) was performed in camps. This was followed by house to house screening (blanket approach). An analysis of secondary VL cases in the neighborhood of index cases was simulated (index case approach). A second screening round was repeated 4–6 months later. In another sub-district in India and Nepal, health workers received incentives for detecting new VL cases over a 4 month period (incentive approach). This was followed by house screening for undetected cases. A total of 28 new VL cases were identified by blanket approach in the 1^st screening round, and used as ACD gold standard. Of these, the camp approach identified 22 (sensitivity 78.6%), index case approach identified 12 (sensitivity – 42.9%), and incentive approach identified 23 new VL cases out of 29 cases detected by the house screening (sensitivity – 79.3%). The effort required to detect a new VL case varied (blanket approach – 1092 households, incentive approach – 978 households; index case approach – 788 households had to be screened). The cost per new case detected varied (camp approach $21 – $661; index case approach $149 – $200; incentive based approach $50 – $543; blanket screening $112 – $629). The 2^nd screening round yielded 20 new VL cases. Sixty and nine new PKDL cases were detected in the first and second round respectively.

Conclusions/Significance

ACD in the VL elimination campaign has a high yield of new cases at programme costs which vary according to the screening method chosen. Countries need the right mix of approaches according to the epidemiological profile, affordability and organizational feasibility.     

Development of a DNA sensor using a molecular logic gate

This communication reports the increase in fluorescence resonance energy transfer (FRET) efficiency between two laser dyes in the presence of deoxyribonucleic acid (DNA). Two types of molecular logic gates have been designed where DNA acts as input signal and fluorescence intensity of different bands are taken as output signal. Use of these logic gates as a DNA sensor has been demonstrated.     

Compost tea as soil drench: an alternative approach to control bacterial wilt in brinjal

An experiment was conducted in the field laboratory, Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh, to evaluate the efficacy of compost tea and poultry litter extract along with their economic feasibility of their usage in controlling bacterial wilt of brinjal under natural incidence condition. A significant variation was observed among the treatments on the incidence and severity of bacterial wilt in brinjal. The results showed that the lowest wilt incidence was recorded in T₂ (Compost tea as soil drenching), T₅ (Poultry litter as soil application) and T₆ (IPM Lab Biopesticide as soil application) while the highest wilt incidence was recorded in control treatment in both counting periods. Similar trend regarding the performance of these treatments was observed on the bacterial wilt severity of brinjal. The effects of compost tea and poultry litter extract on the growth and yield parameters of eggplant were observed to be significant. The results revealed that plant height, number of branches per plant, number of fruits per plant and fruit yield per ha were recorded as maximum in T₂ (Compost tea as soil drenching), followed by T₅ (Poultry litter as soil application) and T₆ (IPM Lab Biopesticide as soil application), while the minimum plant height, number of branches per plant, number of fruits per plant and fruit yield were recorded in control treatment (T₁). The other treatments showed significant effect in increasing all the growth and yield parameters of brinjal as compared to control. Benefit cost analyses (BCR) showed that T₆ (IPM Lab Biopesticide as soil application) resulted in the highest BCR (99.21) as compared to control, followed by T₇ (BAU-Biofungicide as foliar spray) and T₂ (Compost tea as soil drenching) with BCR 35.7 and 19.5, respectively. The results indicated that an investment of Tk. 1.00 may lead to a profit up to Tk. 99.21 by soil application of IPM Lab Biopesticide which gave the maximum profit in the present study. T₇ (BAU-Biofungicide as foliar spray) followed T₂ (Compost tea as soil drenching) where the investment Tk. 1.00 returned a profit of Tk. 35.70 and Tk. 19.5, respectively. Soil drenching of compost tea showed comparatively lower BCR but the highest percent increase of gross margin was obtained when compost tea was applied as soil drench (T₂). Therefore, it may be concluded that soil drenching of compost tea may be an alternative approach to control bacterial wilt of brinjal along with other possible organic amendments.