Mutation underlying resistance of Plasmodium berghei to atovaquone in the quinone binding domain 2 (Qo(2)) of the cytochrome b gene

The anti-malarial agent atovaquone specifically targets the cytochrome bc₁ complex and inhibits the parasite respiration. Resistance to this drug, a coenzyme Q analogue, is associated with mutations in the mitochondrial cytochrome b gene. We previously reported atovaquone resistant mutations in Plasmodium berghei, in the first quinone binding domain (Qo₁) of the cytochrome b gene (M133I and L144S) with V284F in the sixth transmembrane domain. However, in P. falciparum the most common mutations are found in the Qo₂ region. To obtain a better model for biochemical and genetic studies, we have now extended our study to isolate a wider range of P. berghei resistant strains, in particular those in the Qo₂. Here we report four new mutations (Y268N, Y268C, L271V and K272R), all in the Qo₂ domain. Two of these mutations are convergent to codon 268 (nt802–804) drug-induced mutation in P. falciparum.     

Gene order and recombination rate in homologous chromosome regions of the chicken and a passerine bird

Genome structure has been found to be highly conserved between distantly related birds and recent data for a limited part of the genome suggest that this is true also for the gene order (synteny) within chromosomes. Here, we confirm that synteny is maintained for large chromosomal regions in chicken and a passerine bird, the great reed warbler Acrocephalus arundinaceus, with few rearrangements, but in contrast show that the recombination-based linkage map distances differ substantially between these species. We assigned a chromosomal location based on sequence similarity to the chicken genome sequence to a set of microsatellite loci mapped in a pedigree of great reed warblers. We detected homologous loci on 14 different chromosomes corresponding to chicken chromosomes Gga1-5, 7-9, 13, 19, 20, 24, 25, and Z. It is known that 2 passerine macrochromosomes correspond to the chicken chromosome Gga1. Homology of 2 different great reed warbler linkage groups (LG13 and LG5) to Gga1 allowed us to locate the split to a position between 20.8 and 84.8 Mb on Gga1. Data from the 5 chromosomal regions (on Gga1, 2, 3, 5, and Z) with 3 or more homologous loci showed that synteny was conserved with the exception of 2 large previously unreported inversions on Gga1/LG5 and Gga2/LG3, respectively. Recombination data from the 9 chromosomal regions in which we identified 2 or more homologous loci (accounting for the inversions) showed that the linkage map distances in great reed warblers were only 6.3% and 13.3% of those in chickens for males and females, respectively. This is likely to reflect the true interspecific difference in recombination rate because our markers were not located in potentially low-recombining regions: several linkage groups covered a substantial part of their corresponding chicken chromosomes and were not restricted to centromeres. We conclude that recombination rates may differ strongly between bird species with highly conserved genome structure and synteny and that the chicken linkage map may not be suitable, in terms of genetic distances, as a model for all bird species.     

“One Health” or Three? Publication Silos Among the One Health Disciplines

The One Health initiative is a global effort fostering interdisciplinary collaborations to address challenges in human, animal, and environmental health. While One Health has received considerable press, its benefits remain unclear because its effects have not been quantitatively described. We systematically surveyed the published literature and used social network analysis to measure interdisciplinarity in One Health studies constructing dynamic pathogen transmission models. The number of publications fulfilling our search criteria increased by 14.6% per year, which is faster than growth rates for life sciences as a whole and for most biology subdisciplines. Surveyed publications clustered into three communities: one used by ecologists, one used by veterinarians, and a third diverse-authorship community used by population biologists, mathematicians, epidemiologists, and experts in human health. Overlap between these communities increased through time in terms of author number, diversity of co-author affiliations, and diversity of citations. However, communities continue to differ in the systems studied, questions asked, and methods employed. While the infectious disease research community has made significant progress toward integrating its participating disciplines, some segregation—especially along the veterinary/ecological research interface—remains.     

PROTEOLYTIC ENZYMES AND EXPERIMENTAL DEMYELINATION IN THE RAT AND MONKEY

Abstract— Visible lesions from monkeys with acute experimental allergic encephalomyelitis (EAE) induced by injection of purified myelin basic protein were assayed for acid proteinase, for a neutral proteinase at pH 6·5, and one lesion was measured for cathepsin A. Acid proteinase was increased to 152–176 per cent of levels in normal-appearing brain areas, neutral proteinase increased to 220–258 per cent, and the one lesion assayed for cathepsin A was 840 per cent of control. These enzymes were measured in the brain stem of Lewis rats with acute EAE as a result of basic protein injection and compared to Freund's adjuvant-injected controls. Acid proteinase was increased significantly to an average level of 128 per cent of control, the increase in neutral proteinase was not significant, and cathepsin A levels were 258 per cent of control, a highly significant increase. The rise in cathepsin A levels was not seen until the onset of paralytic symptoms. The brain stem of Wistar rats treated with whole spinal cord which show EAE in a milder form than the Lewis rat did not contain significantly higher enzyme levels than the control. The increases in acid proteinase and cathepsin A in brain stems were compared to levels of these enzymes in lymph nodes of EAE, Freund's adjuvant-injected controls and uninjected controls. The level of acid proteinase of lymph nodes/g protein did not change appreciably in the course of EAE development in the Lewis and Wistar rats and was about 3–4 times the activity in the brain stem. The cathepsin A in the inguinal lymph nodes of Wistar and Lewis rats injected with whole spinal cord in Freund's adjuvant increases to a level 2× that of the lymph nodes of the uninjected control. The cathepsin A levels in these activated lymph nodes was 6–8 × that of the control brain stem. The lymph nodes of Lewis and Wistar rats injected with Freund's adjuvant alone showed the same increase in cathepsin A as those from rats injected with spinal cord. The brain stem of rats undergoing severe demyelination as a result of chronic administration of triethyl tin did not show the enzyme increases. These results are compatible with the theory that proteolytic enzyme increases in EAE (and probably multiple sclerosis) are due to the invasion of mononuclear cells, some of which are probably lymphocytes. Whether or not these enzymes participate in the actual dissolution of myelin is unknown.     

Pre-clinical and clinical significance of heparanase in Ewing's sarcoma

Heparanase is an endoglycosidase that specifically cleaves heparan sulphate side chains of heparan sulphate proteoglycans, activity that is strongly implicated in cell migration and invasion associated with tumour metastasis, angiogenesis and inflammation. Heparanase up-regulation was documented in an increasing number of human carcinomas, correlating with reduced post-operative survival rate and enhanced tumour angiogenesis. Expression and significance of heparanase in human sarcomas has not been so far reported. Here, we applied the Ewing's sarcoma cell line TC71 and demonstrated a potent inhibition of cell invasion in vitro and tumour xenograft growth in vivo upon treatment with a specific inhibitor of heparanase enzymatic activity (compound SST0001, non-anticoagulant N-acetylated, glycol split heparin). Next, we examined heparanase expression and cellular localization by immunostaining of a cohort of 69 patients diagnosed with Ewing's sarcoma. Heparanase staining was noted in all patients. Notably, heparanase staining intensity correlated with increased tumour size (P = 0.04) and with patients' age (P = 0.03), two prognostic factors associated with a worse outcome. Our study indicates that heparanase expression is induced in Ewing's sarcoma and associates with poor prognosis. Moreover, it encourages the inclusion of heparanase inhibitors (i.e. SST0001) in newly developed therapeutic modalities directed against Ewing's sarcoma and likely other malignancies.