Antimicrobial activity of honey from the stingless bee Trigona carbonaria determined by agar diffusion,agar dilution,broth microdilution and time‐kill methodology

Aims: The aim of this study was to determine the spectrum of antimicrobial activity of 11 samples of stingless bee honey compared to medicinal, table and artificial honeys. Methods and Results: Activity was assessed by agar diffusion, agar dilution, broth microdilution and time‐kill viability assays. By agar dilution, minimum inhibitory concentration (MIC) ranges were 4% to >10% (w/v) for Gram‐positive bacteria, 6% to >16% (w/v) for Gram‐negative bacteria and 6% to >10% (w/v) for Candida spp. By broth microdilution, all organisms with the exception of Candida albicans and Candida glabrata were inhibited at ≤32% (w/v). Geometric MIC (w/v) means for stingless bee honeys ranged from 7·1% to 16·0% and were 11·7% for medicinal honey and 26·5% for table honey. Treatment of organisms with 20% (w/v) stingless bee honey for 60 min resulted in decreases of 1–3 log for Staphylococcus aureus, >3 log for Pseudomonas aeruginosa and <1 log for C. albicans. Similar treatment with each control honey resulted in decreases of <1 log for all organisms. Conclusions: Stingless bee honey has broad‐spectrum antibacterial activity although activity against Candida was limited. Stingless bee honey samples varied in activity and the basis for this remains to be determined. Significance and Impact of the Study: Stingless bee honey had similar activity to medicinal honey and may therefore have a role as a medicinal agent.     

X-linked megalocornea caused by mutations in CHRDL1 identifies an essential role for ventroptin in anterior segment development

X-linked megalocornea (MGC1) is an ocular anterior segment disorder characterized by an increased cornea diameter and deep anterior chamber evident at birth and later onset of mosaic corneal degeneration (shagreen), arcus juvenilis, and presenile cataracts. We identified copy-number variation, frameshift, missense, splice-site and nonsense mutations in the Chordin-like 1 gene (CHRDL1) on Xq23 as the cause of the condition in seven MGC1 families. CHRDL1 encodes ventroptin, a bone morphogenic protein antagonist with a proposed role in specification of topographic retinotectal projections. Electrophysiological evaluation revealed mild generalized cone system dysfunction and, in one patient, an interhemispheric asymmetry in visual evoked potentials. We show that CHRDL1 is expressed in the developing human cornea and anterior segment in addition to the retina. We explored the impact of loss of ventroptin function on brain function and morphology in vivo. CHRDL1 is differentially expressed in the human fetal brain, and there is high expression in cerebellum and neocortex. We show that MGC1 patients have a superior cognitive ability despite a striking focal loss of myelination of white matter. Our findings reveal an unexpected requirement for ventroptin during anterior segment development and the consequences of a lack of function in the retina and brain.     

An assessment of orchids’ diversity in Penang Hill,Penang, Malaysia after 115 years

A comprehensive study on the orchid diversity in Penang Hill, Penang, Malaysia was conducted from 2004 to 2008 with the objective to evaluate the presence of orchid species listed by Curtis (J Strait Br R Asiat Soc 25:67–173, 1894) after more than 100 years. A total of 85 species were identified during this study, of which 52 are epiphytic or lithophytic and 33 are terrestrial orchids. This study identified 57 species or 64.8% were the same as those recorded by Curtis (1894), and 78 species or 66.1% of Turner’s (Gardens’ Bull Singap 47(2):599–620, 1995) checklist of 118 species for the state of Penang including 18 species which were not recorded by Curtis (1894) and the current study but are actually collected from Penang Hill. A comparison table of the current findings against Curtis (1894) and Turner (1995) is provided which shows only 56 species were the same in all three studies. The preferred account for comparison was Curtis’ (1894) list as his report was specifically for the areas around Penang Island especially Penang Hill, Georgetown and Ayer Itam areas. Our study reveals that about 50% of Curtis’ collection localities have been converted to residential areas and agricultural land, and this probably explains the decreasing numbers of species found in the current study especially for the terrestrial species as epiphytic species have better adaptation capabilities towards environmental changes. Seven species were identified as new records to Penang Hill as they were not recorded by Curtis (1894). None of the three species recorded as endemic to Penang by Turner (1995) was recollected during the current study, of which only Zeuxine rupestris was in Curtis’ (1894) list. Overall, we concluded that Penang hill harbours at least 136 species of orchids of which 78 species or 57.4% were recollected in this study. This also indicates that this area is still suitable for orchid growth even though it is surrounded by rapid development and mass conversion of forested land into fruit orchards and residential area. The designation of Penang Hill as a Permanent Forest Reserve would better guarantee the survival of some orchid species unless human interventions and climatic changes occur.     

Impact of Measurement Error on Testing Genetic Association with Quantitative Traits

Measurement error of a phenotypic trait reduces the power to detect genetic associations. We examined the impact of sample size, allele frequency and effect size in presence of measurement error for quantitative traits. The statistical power to detect genetic association with phenotype mean and variability was investigated analytically. The non-centrality parameter for a non-central F distribution was derived and verified using computer simulations. We obtained equivalent formulas for the cost of phenotype measurement error. Effects of differences in measurements were examined in a genome-wide association study (GWAS) of two grading scales for cataract and a replication study of genetic variants influencing blood pressure. The mean absolute difference between the analytic power and simulation power for comparison of phenotypic means and variances was less than 0.005, and the absolute difference did not exceed 0.02. To maintain the same power, a one standard deviation (SD) in measurement error of a standard normal distributed trait required a one-fold increase in sample size for comparison of means, and a three-fold increase in sample size for comparison of variances. GWAS results revealed almost no overlap in the significant SNPs (p<10⁻⁵) for the two cataract grading scales while replication results in genetic variants of blood pressure displayed no significant differences between averaged blood pressure measurements and single blood pressure measurements. We have developed a framework for researchers to quantify power in the presence of measurement error, which will be applicable to studies of phenotypes in which the measurement is highly variable.     

A Novel Splice-Site Mutation in ALS2 Establishes the Diagnosis of Juvenile Amyotrophic Lateral Sclerosis in a Family with Early Onset Anarthria and Generalized Dystonias

The diagnosis of childhood neurological disorders remains challenging given the overlapping clinical presentation across subgroups and heterogeneous presentation within subgroups. To determine the underlying genetic cause of a severe neurological disorder in a large consanguineous Pakistani family presenting with severe scoliosis, anarthria and progressive neuromuscular degeneration, we performed genome-wide homozygosity mapping accompanied by whole-exome sequencing in two affected first cousins and their unaffected parents to find the causative mutation. We identified a novel homozygous splice-site mutation (c.3512+1G>A) in the ALS2 gene ({"type":"entrez-nucleotide","attrs":{"text":"NM_020919.3","term_id":"209364519","term_text":"NM_020919.3"}}NM_020919.3) encoding alsin that segregated with the disease in this family. Homozygous loss-of-function mutations in ALS2 are known to cause juvenile-onset amyotrophic lateral sclerosis (ALS), one of the many neurological conditions having overlapping symptoms with many neurological phenotypes. RT-PCR validation revealed that the mutation resulted in exon-skipping as well as the use of an alternative donor splice, both of which are predicted to cause loss-of-function of the resulting proteins. By examining 216 known neurological disease genes in our exome sequencing data, we also identified 9 other rare nonsynonymous mutations in these genes, some of which lie in highly conserved regions. Sequencing of a single proband might have led to mis-identification of some of these as the causative variant. Our findings established a firm diagnosis of juvenile ALS in this family, thus demonstrating the use of whole exome sequencing combined with linkage analysis in families as a powerful tool for establishing a quick and precise genetic diagnosis of complex neurological phenotypes.     

Examination of the Cytotoxic and Embryotoxic Potential and Underlying Mechanisms of Next-Generation Synthetic Trioxolane and Tetraoxane Antimalarials

Semisynthetic artemisinin-based therapies are the first-line treatment for P. falciparum malaria, but next-generation synthetic drug candidates are urgently required to improve availability and respond to the emergence of artemisinin-resistant parasites. Artemisinins are embryotoxic in animal models and induce apoptosis in sensitive mammalian cells. Understanding the cytotoxic propensities of antimalarial drug candidates is crucial to their successful development and utilization. Here, we demonstrate that, similarly to the model artemisinin artesunate (ARS), a synthetic tetraoxane drug candidate (RKA182) and a trioxolane equivalent (FBEG100) induce embryotoxicity and depletion of primitive erythroblasts in a rodent model. We also show that RKA182, FBEG100 and ARS are cytotoxic toward a panel of established and primary human cell lines, with caspase-dependent apoptosis and caspase-independent necrosis underlying the induction of cell death. Although the toxic effects of RKA182 and FBEG100 proceed more rapidly and are relatively less cell-selective than that of ARS, all three compounds are shown to be dependent upon heme, iron and oxidative stress for their ability to induce cell death. However, in contrast to previously studied artemisinins, the toxicity of RKA182 and FBEG100 is shown to be independent of general chemical decomposition. Although tetraoxanes and trioxolanes have shown promise as next-generation antimalarials, the data described here indicate that adverse effects associated with artemisinins, including embryotoxicity, cannot be ruled out with these novel compounds, and a full understanding of their toxicological actions will be central to the continuing design and development of safe and effective drug candidates which could prove important in the fight against malaria.