The astacin metalloprotease moulting enzyme NAS-36 is required for normal cuticle ecdysis in free-living and parasitic nematodes

Nematodes represent one of the most abundant and species-rich groups of animals on the planet, with parasitic species causing chronic, debilitating infections in both livestock and humans worldwide. The prevalence and success of the nematodes is a direct consequence of the exceptionally protective properties of their cuticle. The synthesis of this cuticle is a complex multi-step process, which is repeated 4 times from hatchling to adult and has been investigated in detail in the free-living nematode, Caenorhabditis elegans. This process is known as moulting and involves numerous enzymes in the synthesis and degradation of the collagenous matrix. The nas-36 and nas-37 genes in C. elegans encode functionally conserved enzymes of the astacin metalloprotease family which, when mutated, result in a phenotype associated with the late-stage moulting defects, namely the inability to remove the preceding cuticle. Extensive genome searches in the gastrointestinal nematode of sheep, Haemonchus contortus, and in the filarial nematode of humans, Brugia malayi, identified NAS-36 but not NAS-37 homologues. Significantly, the nas-36 gene from B. malayi could successfully complement the moult defects associated with C. elegans nas-36, nas-37 and nas-36/nas-37 double mutants, suggesting a conserved function for NAS-36 between these diverse nematode species. This conservation between species was further indicated when the recombinant enzymes demonstrated a similar range of inhibitable metalloprotease activities

Multi-point temperature measuring equipment for crop environment, with some results on horizontal homogeneity in a maize crop. 2. Equipment used.

Details regarding equipment used in obtaining field data on crop environment temp. published earlier [see FCA 30, 5292] are reported. Pt resistance mounting and error analysis, calibration of these resistances and data logger requirements and modifications are dealt with. Equipment details regarding the actual collection of accurately scanned field temp. are discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission

Multi-point temperature measuring equipment for crop environment, with some results on horizontal homogeneity in a maize crop. 1. Field results.

The use of temperature measurements above, below and within plant stands in physiological and ecological studies is briefly reviewed and the choice of sensor and protection from radiation effects in measuring temperatures within a maize crop are discussed. The horizontal homogeneity of temperature was investigated. Measurements in 1973 and 1974 showed the greatest horizontal temperature difference at 1.8 m above ground level due to an increase in leaf area density just above the height where the crop became closed and air flow was reduced; at lower levels temperature differences increased as turbulence was reduced, and differences in soil surface conditions influenced temperature measurement. The need for a large number of measuring points in the lower parts of the canopy is emphasized. (Abstract retrieved from CAB Abstracts by CABI’s permission

Precisely timed regulation of enhancer activity defines the binary expression pattern of Fushi tarazu in the Drosophila embryo

The genes that drive development each typically have many different enhancers. Properly coordinating the action of these different enhancers is crucial to correctly specifying cell-fate decisions, yet it remains poorly understood how their activity is choregraphed in time. To shed light on this question, we used recently developed single-cell live imaging tools to dissect the regulation of Fushi tarazu (Ftz) in Drosophila melanogaster embryos. Ftz is a transcription factor that is expressed in asymmetric stripes by two distinct enhancers: autoregulatory and zebra. The anterior edge of each stripe needs to be sharply defined to specify essential lineage boundaries. Here, we tracked how boundary cells commit to either a high-Ftz or low-Ftz fate by measuring Ftz protein traces in real time and simultaneously quantifying transcription from the endogenous locus and individual enhancers. This revealed that the autoregulatory enhancer does not establish this fate choice. Instead, it perpetuates the decision defined by zebra. This is contrary to the prevailing view that autoregulation drives the fate decision by causing bi-stable Ftz expression. Furthermore, we showed that the autoregulatory enhancer is not activated based on a Ftz-concentration threshold but through a timing-based mechanism. We hypothesize that this is regulated by several ubiquitously expressed pioneer-like transcription factors, which have recently been shown to act as timers in the embryo. Our work provides new insight into how precisely timed enhancer activity can directly regulate the dynamics of gene regulatory networks, which may be a general mechanism for ensuring that embryogenesis runs like clockwork

Biosynthesis and enzymology of the Caenorhabditis elegans cuticle: identification and characterization of a novel serine protease inhibitor.

The nematode Caenorhabditis elegans represents an excellent model in which to examine nematode gene expression and function. A completed genome, straightforward transgenesis, available mutants and practical genome-wide RNAi approaches provide an invaluable toolkit in the characterization of nematode genes. We have performed a targeted RNAi screen in an attempt to identify components of the cuticle collagen biosynthetic pathway. Collagen biosynthesis and cuticle assembly are multi-step processes that involve numerous key enzymes involved in post-translational modification, trimer folding, procollagen processing and subsequent cross-linking stages. Many of these steps, the modifications and the enzymes are unique to nematodes and may represent attractive targets for the control of parasitic nematodes. A novel serine protease inhibitor was uncovered during our targeted screen, which is involved in collagen maturation, proper cuticle assembly and the moulting process. We have confirmed a link between this inhibitor and the previously uncharacterized bli-5 locus in C. elegans. The mutant phenotype, spatial expression pattern and the over-expression phenotype of the BLI-5 protease inhibitor and their relevance to collagen biosynthesis are discussed

Comparison of the Electronic Structures and Energetics of Ferroelectric LiNbO3 and LiTaO3

This paper explains the origin of the ferroelectric instability in LiNbO3 and LiTaO3 and compares the electronic structures and energetics of the two materials.Comment: 31 pages, 11 Postscript figure

Management and outcomes of myocardial infarction in people with impaired kidney function in England

Background: Acute myocardial infarction (AMI) causes significant mortality and morbidity in people with impaired kidney function. Previous observational research has demonstrated reduced use of invasive management strategies and inferior outcomes in this population. Studies from the USA have suggested that disparities in care have reduced over time. It is unclear whether these findings extend to Europe and the UK. Methods: Linked data from four national healthcare datasets were used to investigate management and outcomes of AMI by estimated glomerular filtration rate (eGFR) category in England. Multivariable logistic and Cox regression models compared management strategies and outcomes by eGFR category among people with kidney impairment hospitalised for AMI between 2015–2017. Results: In a cohort of 5 835 people, we found reduced odds of invasive management in people with eGFR < 60mls/min/1.73m2 compared with people with eGFR ≥ 60 when hospitalised for non-ST segment elevation MI (NSTEMI). The association between eGFR and odds of invasive management for ST-elevation MI (STEMI) varied depending on the availability of percutaneous coronary intervention. A graded association between mortality and eGFR category was demonstrated both in-hospital and after discharge for all people. Conclusions: In England, patients with reduced eGFR are less likely to receive invasive management compared to those with preserved eGFR. Disparities in care may however be decreasing over time, with the least difference seen in patients with STEMI managed via the primary percutaneous coronary intervention pathway. Reduced eGFR continues to be associated with worse outcomes after AMI