Development and evaluation of a loop-mediated isothermal amplification (LAMP) assay for rapid detection of Actinobacillus pleuropneumoniae based the dsbE-like gene

This paper reports on the development and validation of a loop-mediated isothermal amplification assay (LAMP) for the rapid and specific detection of Actinobacillus pleuropneumoniae (A. pleuropneumoniae). A set of six primers were designed derived from the dsbE-like gene of A.pleuropneumoniae and validate the assay using 9 A. pleuropneumoniae reference/field strains, 132 clinical isolates and 9 other pathogens. The results indicated that positive reactions were confirmed for all A. pleuropneumoniae strains and specimens by LAMP at 63ºC for 60 min and no cross-reactivity were observed from other non-A.pleuropneumoniae including Haemophilus parasuis, Escherichia coli, Pasteurella multocida, Bordetella bronchiseptica, Streptococcus suis, Salmonella enterica, Staphylococcus, porcine reproductive and respiratory syndrome virus (PRRSV), and Pseudorabies virus. The detection limit of the conventional PCR was 10² CFU per PCR test tube, while that of the LAMP was 5 copies per tube. Therefore, the sensitivity of LAMP was higher than that of PCR. Moreover, the LAMP assay provided a rapid yet simple test of A. pleuropneumoniae suitable for laboratory diagnosis and pen-side detection due to ease of operation and the requirement of only a regular water bath or heat block for the reaction

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

The taxonomic and evolutionary significance of leaf longevity

The half‐lives of leaves of 202 taxa of vascular plants were estimated mostly from the literature and ranged from 1 to 350 wk. The longevity of leaves in the plant groups studied is in the order Pinophyta > Pteridophyta > Liliatae > Magnoliatae. Substantial differences are evident between the superorders of flowering plants proposed by Dahlgren and the subclasses proposed by Cronquist. The mean leaf half‐life for families of Magnoliatae was shown to be inversely related to their Advancement Index. Length of life of leaves, therefore, appears to have taxonomic significance, with more primitive vascular plants tending to have longer‐lived leaves than the more advanced. The ecological significance of leaf half‐life is less clear, except in that annual leaf fall is not necessarily associated with deciduousness. The capacity to shed individual leaves may give the angiosperms a flexibility in environmental response which allows them a competitive advantage over the gymnosperms except in the most stressful habitats

Diversity in the Grass Pistil and its Taxonomic Significance

Grass pistils show a great deal of diversity. Variations occur in the number of stigmatic branches, the point at which the styles diverge, the extent of development of hairs on the stigma and ovary, style colour and exsertion from the floret. ANOVA, contigency analysis and regression analysis showed that in the grasses of south-eastern Queensland, these attributes are related at various levels to the taxonomy of the grasses, and are, therefore, potentially useful in grass systematics. A system of 11 categories of pistils is proposed and illustrated

Where now for taxonomy?

With the increasing financial squeeze faced by taxonomists, the time may now have come to dispense with massive herbarium collections. Indeed, the clear-out might lead to a better quality of taxonomic research