Characterisation of quiescin-sulfhydryl oxidase and nematode astacin mutants using functional studies in caenorhabditis elegans.

Nematodes, both free-living and parasitic, are dependant upon their Extra Cellular Matrix (ECM) for multiple aspects of functionality. Two distinct ECMs are present in Caenorhabditis elegans, the basement membrane and the cuticle. The cuticle of C. elegans, like other nematodes is composed largely of collagen-like proteins, with the trimeric collagenous proteins forming approximately 80% of the cuticle. Cuticle collagens are believed to be highly processed in a manner similar to vertebrate collagen maturation, with collagens being; co-translationanly modified, folded into triple helices and proteolytically cleaved at the C- and N- termini. Cross-linking of mature triple helical collagens into higher order structures leads to the generation of a flexible yet robust cuticle. Disulphide bonding is crucial in the formation of the cuticle, with cysteine cross-linking mutants having been shown to produce severely disrupted cuticles and associated lethal phenotypes. During the life cycle, C. elegans progresses through four moults during which a new cuticle is synthesised and the old cuticle is shed. Moulting occurs by proteolytic digestion and shedding of an anterior cuticular cap which provides an opening for the nematode to escape the previous stage cuticle. Both free-living and parasitic nematodes shed and exsheath their cuticles in this manner. Two distinct phases of cuticle processing become apparent: cuticle synthesis and cuticle degradation. Of the enzymes involved with processing of cuticular collagens, the quiescin sulfhydryl oxidases (QSOX), and the nematode astacins (NAS) are of particular interest with regard to cuticle synthesis and proteolytic cleavage of cuticular collagens respectively. QSOX have been shown to be linked directly to the generation of disulphide bonds, and have also been shown to associate with other essential proteins of cuticle formation, namely the protein disulphide isomerases. There are three distinct QSOX family members found within the C. elegans genome, which have been shown to temporally coincide with lethargus (cuticle synthesis) and have been proven to spatially localise to the C. elegans hypodermis, the tissue responsible for cuticle secretion. Characterisation of qsox mutants reveals weak cuticular phenotypes when disrupted singly; but, in combination, silencing of qsox-1 and qsox-2 resulted in blistered cuticles and lethality, by RNA mediated interference and double knockouts respectively. This demonstrates the essential nature of the cuticle associated QSOX enzymes, and to my knowledge represents the first loss-of-function mutant in a QSOX enzyme. xv Investigation of the NAS enzymes focused on the group V astacins, members of which exhibit the only notable defects associated with disruption of C. elegans nas genes, namely: dumpy body shape, nas-35/dpy-31; hatching, nas-34/hch-1; and moult defects, nas-36 and 37. With regard to proteolytic degradation of cuticular components, NAS-36 and NAS-37 were of specific interest as mutants resulted in moult defective nematodes unable to digest and fully escape their previous stage cuticles; in addition, spatial expression illustrated an association of these gene products with regions of cuticle attachment and degradation. C. elegans NAS-36 and NAS-37 were also shown to digest isolated L3(2M) trichostrongylid cuticles of parasites of veterinary importance, suggesting that the metalloprotease and cuticle substrates involved in exsheathment is conserved between trichostrongylid and free-living nematodes. Conservation is poor between ecdysozoan and non-moulting organisms, meaning that proteins such as NAS-36 and 37 could become specific novel targets for anti-nematode drug development

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

An investigation of vegetation and other earth resource/feature parameters using LANDSAT and other remote sensing data. A: LANDSAT. B: Remote sensing of volcanic emissions

There are no author-identified significant results in this report

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

A Head-to-Head Comparison of the Standard Quality-Adjusted Life Year Model With the Annual Profile Model

Objectives: The standard quality-adjusted life year (QALY) model (SQM) assumes time-utility independence within constant health states and additive independence when health varies over time. The validity of SQM has been challenged through reported violations of these assumptions. An alternative approach that relaxes these assumptions is to assign a single valuation to an entire health profile: an integral assessment of disease severity over time. Here, we compare SQM with the annual profile model (APM) and test SQM for additive independence. Methods: Eighty-two respondents valued 6 episodic conditions, including 4 of short duration, with SQM and APM, using the time trade-off method. Inter-rater reliability was assessed using intraclass correlation coefficients. Face validity was tested by asking respondents how well they were able to imagine the health states under SQM and APM. We calculated SQM QALY values for a 1-year time period, allowing for a direct comparison with APM values. For the short-term conditions we expected higher QALY values for SQM, violating additive independence. Results: APM showed higher interrater reliability (intraclass correlation coefficient of 0.53 vs 0.18, respectively) and better face validity than SQM, with 6% (APM) vs 21% (SQM) of all respondents reporting difficulties. Additive independence of SQM was violated in 5 of the 6 conditions (including the 4 short duration health states), with higher QALY values under SQM (mean difference 0.04). Conclusion: The impact of short-term conditions is systematically underestimated under SQM when compared to a health profile model. APM is a less restrictive model and demonstrates better validity

An investigation of vegetation and other earth resource/feature parameters using LANDSAT and other remote sensing data. A: LANDSAT. B: Remote sensing of volcanic emissions

There are no author-identified significant results in this report

Lithologic mapping of mafic intrusions in East Greenland using Landsat Thematic Mapper data

The East Greenland Tertiary Igneous Province contains a variety of intrusive and extrusive rock types. The Skaergaard complex is the most well known of the intrusive centers. Landsat thematic mapping (TM) was used in conjunction with field spectrometer data to map these mafic intrusions. These intrusions are of interest as possible precious metal ore deposits. They are spectrally distinct from the surrounding Precambrian gneisses. However, subpixel contamination by snow, oxide surface coatings, lichen cover and severe topography limit the discrimination of lithologic units within the gabbro. Imagery of the Skaergaard and surrounding vicinity, and image processing and enhancement techniques are presented. Student theses and other publications resulting from this work are also listed