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

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

On the relevance of animal behavior to the management and conservation of fishes and fisheries

There are many syntheses on the role of animal behavior in understanding and mitigating conservation threats for wildlife. That body of work has inspired the development of a new discipline called conservation behavior. Yet, the majority of those synthetic papers focus on non-fish taxa such as birds and mammals. Many fish populations are subject to intensive exploitation and management and for decades researchers have used concepts and knowledge from animal behavior to support management and conservation actions. Dr. David L. G. Noakes is an influential ethologist who did much foundational work related to illustrating how behavior was relevant to the management and conservation of wild fish. We pay tribute to the late Dr. Noakes by summarizing the relevance of animal behavior to fisheries management and conservation. To do so, we first consider what behavior has revealed about how fish respond to key threats such as habitat alteration and loss, invasive species, climate change, pollution, and exploitation. We then consider how behavior has informed the application of common management interventions such as protected areas and spatial planning, stock enhancement, and restoration of habitat and connectivity. Our synthesis focuses on the totality of the field but includes reflections on the specific contributions of Dr. Noakes. Themes emerging from his approach include the value of fundamental research, management-scale experiments, and bridging behavior, physiology, and ecology. Animal behavior plays a key role in understanding and mitigating threats to wild fish populations and will become more important with the increasing pressures facing aquatic ecosystems. Fortunately, the toolbox for studying behavior is expanding, with technological and analytical advances revolutionizing our understanding of wild fish and generating new knowledge for fisheries managers and conservation practitioners.publishedVersio

Childhood socioeconomic position and objectively measured physical capability levels in adulthood: a systematic review and meta-analysis

<p><b>Background:</b> Grip strength, walking speed, chair rising and standing balance time are objective measures of physical capability that characterise current health and predict survival in older populations. Socioeconomic position (SEP) in childhood may influence the peak level of physical capability achieved in early adulthood, thereby affecting levels in later adulthood. We have undertaken a systematic review with meta-analyses to test the hypothesis that adverse childhood SEP is associated with lower levels of objectively measured physical capability in adulthood.</p> <p><b>Methods and Findings:</b> Relevant studies published by May 2010 were identified through literature searches using EMBASE and MEDLINE. Unpublished results were obtained from study investigators. Results were provided by all study investigators in a standard format and pooled using random-effects meta-analyses. 19 studies were included in the review. Total sample sizes in meta-analyses ranged from N = 17,215 for chair rise time to N = 1,061,855 for grip strength. Although heterogeneity was detected, there was consistent evidence in age adjusted models that lower childhood SEP was associated with modest reductions in physical capability levels in adulthood: comparing the lowest with the highest childhood SEP there was a reduction in grip strength of 0.13 standard deviations (95% CI: 0.06, 0.21), a reduction in mean walking speed of 0.07 m/s (0.05, 0.10), an increase in mean chair rise time of 6% (4%, 8%) and an odds ratio of an inability to balance for 5s of 1.26 (1.02, 1.55). Adjustment for the potential mediating factors, adult SEP and body size attenuated associations greatly. However, despite this attenuation, for walking speed and chair rise time, there was still evidence of moderate associations.</p> <p><b>Conclusions:</b> Policies targeting socioeconomic inequalities in childhood may have additional benefits in promoting the maintenance of independence in later life.</p&gt

Age and gender differences in physical capability levels from mid-life onwards: The Harmonisation and meta-analysis of data from eight UK cohort studies

Using data from eight UK cohorts participating in the Healthy Ageing across the Life Course (HALCyon) researchprogramme, with ages at physical capability assessment ranging from 50 to 90+ years, we harmonised data on objectivemeasures of physical capability (i.e. grip strength, chair rising ability, walking speed, timed get up and go, and standingbalance performance) and investigated the cross-sectional age and gender differences in these measures. Levels of physicalcapability were generally lower in study participants of older ages, and men performed better than women (for example,results from meta-analyses (N = 14,213 (5 studies)), found that men had 12.62 kg (11.34, 13.90) higher grip strength thanwomen after adjustment for age and body size), although for walking speed, this gender difference was attenuated afteradjustment for body size. There was also evidence that the gender difference in grip strength diminished with increasingage,whereas the gender difference in walking speed widened (p,0.01 for interactions between age and gender in bothcases). This study highlights not only the presence of age and gender differences in objective measures of physicalcapability but provides a demonstration that harmonisation of data from several large cohort studies is possible. Theseharmonised data are now being used within HALCyon to understand the lifetime social and biological determinants ofphysical capability and its changes with age

Pentastomiasis (armillifer armillatus infestation)

ArticleThe original publication is available at http://www.samj.org.zaPentastomiasis, also known as ‘tongue worm’ infestation or porocephalosis, is a parasitic zoonosis endemic to western and central Africa. In 1847, Pruner described the first human infection by a pentastomid in Cairo. The definitive hosts are snakes and other reptiles, while the intermediate hosts are carnivorous mammals and, rarely, humans. Most cases of human pentastomiasis are caused by two species of pentastomids, both of which have characteristics of arthropods and annelids, viz. Armillifer armillatus and Linguatula serrata.Publishers' Versio