The chemical structure of rabbit immunoglobulin IgG

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Life just got complicated

The fossil record of ancient life is, in general, poor. Certainly, fossils are abundant in many rock successions and may reveal remarkable details about evolution and environmental change, but they typically consist of disarticulated or broken skeletal material, such as shells, bones and teeth. Even worse, the record of entirely (or largely) soft-bodied organisms, such as jellyfish and worms, is extremely scant, despite the fact that such animals dominate modern marine environments and presumably did so in the past. The reason is obvious — such organisms are highly susceptible to post-mortem decay and typically decompose more rapidly than the ‘normal’ processes of fossilisation operate. This significantly blurs our view of ancient life, with obvious consequences for those interested in understanding evolution and past ecosystems

The Trypanosoma cruzi enzyme TcGPXI is a glycosomal peroxidase and can be linked to trypanothione reduction by glutathione or tryparedoxin.

Trypanosoma cruzi glutathione-dependent peroxidase I (TcGPXI) can reduce fatty acid, phospholipid, and short chain organic hydroperoxides utilizing a novel redox cycle in which enzyme activity is linked to the reduction of trypanothione, a parasite-specific thiol, by glutathione. Here we show that TcGPXI activity can also be linked to trypanothione reduction by an alternative pathway involving the thioredoxin-like protein tryparedoxin. The presence of this new pathway was first detected using dialyzed soluble fractions of parasite extract. Tryparedoxin was identified as the intermediate molecule following purification, sequence analysis, antibody studies, and reconstitution of the redox cycle in vitro. The system can be readily saturated by trypanothione, the rate-limiting step being the interaction of trypanothione with the tryparedoxin. Both tryparedoxin and TcGPXI operate by a ping-pong mechanism. Overexpression of TcGPXI in transfected parasites confers increased resistance to exogenous hydroperoxides. TcGPXI contains a carboxyl-terminal tripeptide (ARI) that could act as a targeting signal for the glycosome, a kinetoplastid-specific organelle. Using immunofluorescence, tagged fluorescent proteins, and biochemical fractionation, we have demonstrated that TcGPXI is localized to both the glycosome and the cytosol. The ability of TcGPXI to use alternative electron donors may reflect their availability at the corresponding subcellular sites

Human and environmental factors associated with HIV/AIDS high-risk behaviour in homosexual and bisexual men in the West Midlands, United Kingdom

HIV/AIDS prevention needs of homosexual and bisexual men from the West Midlands Region (UK) were investigated (N=1,750). Data analysis revealed that unsafe sex was associated with youth, and belief that safer sex was boring, difficult, and not right Furthermore, unsafe sex was associated with two indicators of social deprivation: low educational attainment, and unskilled occupation The results also indicated that unsafe sex was associated with increased visitations to gay cottages/tow-paths, and the acceptance of money or gifts in exchange for sex. Moreover, unsafe sex was associated with gay mass media as a source of HIV information, knowledge of positive HIV status, and perceived risk of contracting HIV. However, data analysis revealed that unsafe sex was not associated with marital status and four measures of social support The results demonstrated that although HIV/AIDS knowledge levels were generally high, attitude barriers continued to exert a negative influence on health protective behaviour. The evidence suggested that both human and environmental factors contributed to unsafe sex, and that the Health Belief Model provided little utility in HIV / AIDS prevention research. Evidence from this investigation exposed the pressing need to target health promotional services at groups of gay men who were most at risk for HIV infection, notably the young and those who experienced social deprivation. Recommendations based on the Ottawa Charter were offered on how best to target such services. Key Words - AIDS, prevention, social deprivation, gay me

GM Risk Assessment:Pollen carriage from Brassica napus to B. rapa varies widely between pollinators

© 2017 Gesellschaft für Ökologie Characterizing insect pollen carriage between closely related plant species is especially challenging where source species possess morphologically identical pollen and share many pollinators in common. Here, we use an SNP-based assay using the plant DNA barcoding locus matK to characterize pollen carriage between cultivated Brassica napus and wild Brassica rapa in three sites across southern England. The assay differentiated B. napus and B. rapa pollen carried by honey bees (Apis melifera), bumblebees (Bombus spp.), mining bees (Andrena spp.) and hoverflies (Syrphidae) captured on B. napus plants 1–2 m from wild B. rapa, and on B. rapa plants at various distances from the crop. Apis individuals foraging on B. rapa and carrying B. napus pollen were rarely found beyond 10 m from the crop. However, Bombus and Andrena individuals captured on B. rapa occasionally carried crop pollen up to 300 m from the source field. Hoverflies carried less pollen overall but featured high proportions of B. napus pollen even at the most distant capture points. We predict that different pollinator species will evoke markedly different patterns of interspecific hybrid formation. We conclude that more exhaustive surveys of this kind will help parameterize future mechanistic models to predict the distribution of hybrids between Genetically Modified B. napus and B. rapa on a landscape scale

The Receptor-Like Kinase SERK3/BAK1 Is Required for Basal Resistance against the Late Blight Pathogen Phytophthora infestans in Nicotiana benthamiana

BACKGROUND The filamentous oomycete plant pathogen Phytophthora infestans causes late blight, an economically important disease, on members of the nightshade family (Solanaceae), such as the crop plants potato and tomato. The related plant Nicotiana benthamiana is a model system to study plant-pathogen interactions, and the susceptibility of N. benthamiana to Phytophthora species varies from susceptible to resistant. Little is known about the extent to which plant basal immunity, mediated by membrane receptors that recognise conserved pathogen-associated molecular patterns (PAMPs), contributes to P. infestans resistance. PRINCIPAL FINDINGS We found that different species of Phytophthora have varying degrees of virulence on N. benthamiana ranging from avirulence (incompatible interaction) to moderate virulence through to full aggressiveness. The leucine-rich repeat receptor-like kinase (LRR-RLK) BAK1/SERK3 is a major modulator of PAMP-triggered immunity (PTI) in Arabidopsis thaliana and N. benthamiana. We cloned two NbSerk3 homologs, NbSerk3A and NbSerk3B, from N. benthamiana based on sequence similarity to the A. thaliana gene. N. benthamiana plants silenced for NbSerk3 showed markedly enhanced susceptibility to P. infestans infection but were not altered in resistance to Phytophthora mirabilis, a sister species of P. infestans that specializes on a different host plant. Furthermore, silencing of NbSerk3 reduced the cell death response triggered by the INF1, a secreted P. infestans protein with features of PAMPs. CONCLUSIONS/SIGNIFICANCE We demonstrated that N. benthamiana NbSERK3 significantly contributes to resistance to P. infestans and regulates the immune responses triggered by the P. infestans PAMP protein INF1. In the future, the identification of novel surface receptors that associate with NbSERK3A and/or NbSERK3B should lead to the identification of new receptors that mediate recognition of oomycete PAMPs, such as INF1.This work was supported by the Gatsby Charitable Foundation, BBSRC, Nuffield Foundation and the German Research Foundation (DFG). SS was supported by a personal research fellowship (SCHO1347/1-1). JPR is an Australian Research Council Future Fellow (FT0992129). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Towards an Understanding of Changing-Look Quasars: An Archival Spectroscopic Search in SDSS

The uncertain origin of the recently-discovered `changing-looking' quasar phenomenon -- in which a luminous quasar dims significantly to a quiescent state in repeat spectroscopy over ~10 year timescales -- may present unexpected challenges to our understanding of quasar accretion. To better understand this phenomenon, we take a first step to building a sample of changing-look quasars with a systematic but simple archival search for these objects in the Sloan Digital Sky Survey Data Release 12. By leveraging the >10 year baselines for objects with repeat spectroscopy, we uncover two new changing-look quasars, and a third discovered previously. Decomposition of the multi-epoch spectra and analysis of the broad emission lines suggest that the quasar accretion disk emission dims due to rapidly decreasing accretion rates (by factors of >2.5), while disfavoring changes in intrinsic dust extinction for the two objects where these analyses are possible. Broad emission line energetics also support intrinsic dimming of quasar emission as the origin for this phenomenon rather than transient tidal disruption events or supernovae. Although our search criteria included quasars at all redshifts and transitions from either quasar-like to galaxy-like states or the reverse, all of the clear cases of changing-look quasars discovered were at relatively low-redshift (z ~ 0.2 - 0.3) and only exhibit quasar-like to galaxy-like transitions.Comment: 15 pages, 8 figures. Updated to accepted versio

Combined electrical resistivity tomography and ground penetrating radar to map Eurasian badger (Meles Meles) burrows in clay-rich flood embankments (levees)

Globally, earth embankments are used to protect against flooding. Raised above the surrounding water table, these embankments make ideal habitats for many burrowing animals whose burrows can impact their structural integrity. Ground Penetrating Radar (GPR) is commonly used to identify and map animal burrows and other small cavities. However, the depth of investigation of a GPR survey can be severely limited in saline and clay-rich environments, soil properties commonly associated with flood embankments. In contrast, Electrical Resistivity Tomography (ERT) can image subsurface voids in conductive ground conditions but has been rarely used to image animal burrows. Here we aim to assess the efficacy of ERT and GPR to image two badger burrow networks, called ‘setts’, located in clay embankments on the River Ouse, Yorkshire, UK. The two setts were excavated to validate the geophysical results, and the soil was characterised through logging and geotechnical analysis to develop a ground model of the site. We find that ERT can accurately resolve tunnels down to 1.5 m depth, map the structure of a multi-entrance badger sett and successfully identify the end of the tunnels. This result compares favourably to the GPR surveys, which mapped all but the deepest tunnels, limited by its penetration depth due to clay soils. Our results show that ERT can be used as a primary survey tool for animal burrows in clay-rich environments and can be validated using co-located GPR surveys if penetration depth is sufficient. The implications of this study may allow embankment managers to map burrow networks, assess flood embankment stability, minimise repair costs, and reduce unexpected failures during flood events. Additionally, a better understanding of how, for example, local heterogeneities impact badgers' burrow geometry may be achievable using these geophysical methods, as they provide a non-destructive, repeatable method for imaging setts

Associations between gestational anthropometry, maternal HIV, and fetal and early infancy growth in a prospective rural/semi-rural Tanzanian cohort, 2012-13.

BACKGROUND: Healthcare access and resources differ considerably between urban and rural settings making cross-setting generalizations difficult. In resource-restricted rural/semi-rural environments, identification of feasible screening tools is a priority. The objective of this study was to evaluate gestational anthropometry in relation to birth and infant growth in a rural/semi-rural Tanzanian prospective cohort of mothers and their infants. METHODS: Mothers (n = 114: 44 HIV-positive) attending antenatal clinic visits were recruited in their second or third trimester between March and November, 2012, and followed with their infants through 6-months post-partum. Demographic, clinical, and infant feeding data were obtained using questionnaires administered by a Swahili-speaking research nurse on demographic, socioeconomic, clinical, and infant feeding practices. Second or third trimester anthropometry (mid-upper arm circumference [MUAC], triceps skinfold thickness, weight, height), pregnancy outcomes, birth (weight, length, head circumference) and infant anthropometry (weight-for-age z-score [WAZ], length-for-age z-score [LAZ]) were obtained. Linear regression and mixed effect modeling were used to evaluate gestational factors in relation to pregnancy and infant outcomes. RESULTS AND DISCUSSION: Gestational MUAC and maternal HIV status (HIV-positive mothers = 39%) were associated with infant WAZ and LAZ from birth to 6-months in multivariate models, even after adjustment for infant feeding practices. The lowest gestational MUAC tertile was associated with lower WAZ throughout early infancy, as well as lower LAZ at 3 and 6-months. In linear mixed effects models through 6-months, each 1 cm increase in gestational MUAC was associated with a 0.11 increase in both WAZ (P < 0.001) and LAZ (P = 0.001). Infant HIV-exposure was negatively associated with WAZ (β = -0.65, P < 0.001) and LAZ (β = -0.49, P < 0.012) from birth to 6-months. CONCLUSIONS: Lower gestational MUAC, evaluated using only a tape measure and minimal training that is feasible in non-urban clinic and community settings, was associated with lower infant anthropometric measurements. In this rural and semi-rural setting, HIV-exposure was associated with poorer anthropometry through 6-months despite maternal antiretroviral access. Routine assessment of MUAC has the potential to identify at-risk women in need of additional health interventions designed to optimize pregnancy outcomes and infant growth. Further research is needed to establish gestational MUAC reference ranges and to define interventions that successfully improve MUAC during pregnancy