Differences in the high-temperature tolerance of <Emphasis Type="Italic">Aphis craccivora</Emphasis> (Hemiptera: Aphididae) on cotton and soybean: implications for ecological niche switching among hosts

To forecast the effects of climate change and extreme temperature events on insect population dynamics, the high-temperature tolerance of insects must be taken into account. We compared the life-history characteristics of cowpea aphid (Aphis craccivora Koch) across different temperature regimes on two different host plants, soybean (a preferred host) and cotton (a non-preferred host). Most demographic parameters were superior for the aphid on soybean than on cotton. Temperatures affected aphid development more on cotton than on soybean. The intrinsic rate of increase, reproduction rate, number of progeny per adult, and longevity were significantly higher on soybean than on cotton for the same temperature regime. Temperatures that fluctuated to extreme levels caused a rapid decline in each of these parameters for aphids fed on cotton, but not for those fed on soybean. To our knowledge, this is the first report to note that the high-temperature tolerance of A. craccivora is host-specific (cotton vs. soybean). Our findings may partly explain the observed niche switching of the cowpea aphid (Aphis craccivora) from cotton to soybean at the beginning of summer when the temperature goes up in the Xinjiang cotton-growing zone (Northwest China). This host mediation of high-temperature tolerance in aphids should be taken into account when modeling population dynamics under the influence of global warming, host adaptation, and the risk analysis of alien pest invasions.     

Significance of a new field oviposition record for Graphium eurypylus (L.) (Lepidoptera: Papilionidae) on Michelia champaca (Magnoliaceae)

Abstract  Phytochemical similarities among ancient Angiosperms presumably played a role in the ecological and evolutionary diversification of the swallowtail butterflies (Papilionidae). Host family feeding specialisation is typical of most Papilionidae species, but field records of oviposition are rare for most swallowtail butterflies. It is even more uncommon to witness oviposition and larval feeding on new host plant species, especially in plant families not previously reported for the butterfly species. Oviposition by a female on a new host, or even on a toxic plant, may represent ancestral behaviour (with a loss of larval acceptance, detoxification or processing abilities) or novel behaviour (providing genetic variation for a potential expansion of host range, or host shift). We document the oviposition, larval use and pupation of the Annonaceae specialised and geographically widespread Graphium eurypylus on a Magnoliaceae species, all under field conditions in Queensland, Australia. This is the first time such field observations of oviposition and larval feeding on Michelia champaca (Magnoliaceae) have been documented anywhere for this species.     

Comprehensive Census of Bacteria in Clean Rooms by Using DNA Microarray and Cloning Methods

A census of clean room surface-associated bacterial populations was derived from the results of both the cloning and sequencing of 16S rRNA genes and DNA microarray (PhyloChip) analyses. Samples from the Lockheed Martin Aeronautics Multiple Testing Facility (LMA-MTF), the Kennedy Space Center Payload Hazard and Servicing Facility (KSC-PHSF), and the Jet Propulsion Laboratory Spacecraft Assembly Facility (JPL-SAF) clean rooms were collected during the various assembly phases of the Phoenix and Mars Science Laboratory (MSL) spacecraft. Clone library-derived analyses detected a larger bacterial diversity prior to the arrival of spacecraft hardware in these clean room facilities. PhyloChip results were in agreement with this trend but also unveiled the presence of anywhere from 9- to 70-fold more bacterial taxa than cloning approaches. Among the facilities sampled, the JPL-SAF (MSL mission) housed a significantly less diverse bacterial population than either the LMA-MTF or KSC-PHSF (Phoenix mission). Bacterial taxa known to thrive in arid conditions were frequently detected in MSL-associated JPL-SAF samples, whereas proteobacterial lineages dominated Phoenix-associated KSC-PHSF samples. Comprehensive bacterial censuses, such as that reported here, will help space-faring nations preemptively identify contaminant biomatter that may compromise extraterrestrial life detection experiments. The robust nature and high sensitivity of DNA microarray technologies should prove beneficial to a wide range of scientific, electronic, homeland security, medical, and pharmaceutical applications and to any other ventures with a vested interest in monitoring and controlling contamination in exceptionally clean environments.Planetary protection efforts work toward protecting (i) solar system bodies from contamination by terrestrial biological material (forward contamination), thus preserving opportunities for future scientific investigation, and (ii) the Earth from harmful contamination by materials returned from outer space (back contamination) (5). These approaches apply directly to the control and eradication of microorganisms present on the surfaces of spacecraft intended to land, orbit, fly by, or be in the vicinity of extraterrestrial bodies. Consequently, current planetary protection policies require that spacecraft be assembled and readied for launch in controlled clean room environments. To achieve these conditions and maintain compliance with good manufacturing practice regulations, robotic spacecraft components are assembled in ultraclean facilities. Much like facilities in the medical, pharmaceutical, and semiconductor sectors, National Aeronautics and Space Administration (NASA) spacecraft assembly clean rooms (SAC) are kept extremely clean and are maintained to the highest of industry standards (17). Filtered air circulation, controlled temperature and humidity, routine exposure to disinfectants and surfactants, and nutrient-limiting, oligotrophic conditions make it very challenging for microorganisms to persist in such environments, but these measures by no means eradicate biological contaminants entirely (18). Several investigations, both culture based and culture independent, have demonstrated that a variety of bacterial taxa are repeatedly isolated under clean room conditions (18, 24, 26; P. Vaishampayan, S. Osman, G. Andersen, and K. Venkateswaran, submitted for publication). However, despite a growing understanding of the diverse microbial populations present in SAC, predicting the true risk of any such microbes’ compromising the findings of extraterrestrial life detection efforts remains a significant challenge (30). A better understanding of the distribution and frequency at which high-risk contaminant microbes are encountered on spacecraft surfaces would significantly aid in assessing the threat of forward contamination (33).The purification of nucleic acids, subsequent PCR amplification, and shuttling of 16S ribosomal “fingerprint” genes from noncultivable microorganisms into genetically amenable lab strains of Escherichia coli have evolved into a gold standard of molecular means to elucidate the microbial diversity in a given sample. In theory, the cloning and sequencing of 16S ribosomal genes from each and every cell present, regardless of cultivability and inclusive of novel taxa, would result in a comprehensive survey of microbial communities on the surfaces of SAC and colocated spacecraft (24, 26). Unfortunately, the full-length sequencing of all 16S rRNA genes from environmental samples would be prohibitively expensive, making the approach unfeasible for generating comprehensive phylogenetic profiles of complex microbial communities.Attempting to infer population membership from clone libraries limited to hundreds or thousands of sequences has proven to be insufficient for detecting extremely low-abundance organisms. Recent analyses of phylogenetic DNA extracted from soil, water, and air revealed that laboriously derived clone libraries severely under-represent complex bacterial communities compared to very rapid (i.e., requiring only hours) DNA microarray approaches (1, 6, 11, 23, 36). One of the reasons for this is the high sensitivity of PhyloChip methodologies, which are able to detect organisms present in amounts below 10⁻⁴ abundance of the total sample (12). Numerous validation experiments using sequence-specific PCR have confirmed that taxa identified by the microarray were indeed present in the original environmental samples, despite their absence in corresponding clone libraries (3). This highlights the utility of the method compared to classical cloning. Although the analysis of each sample by the PhyloChip provides detailed information on microbial composition, the highly parallel and reproducible nature of this array allows tracking community dynamics over time and treatment. Even without prior sequence information, PhyloChip can identify specific microbial interactions that are key to particular changing environments.A comprehensive census of the microbial communities on the surfaces in three NASA SAC supporting two distinct missions was conducted. To ensure that the maximum diversity of resident microbiota was uncovered, subsamples from each clean room surface sampling were subjected to both DNA microarray protocols and conventional cloning and sequencing of 16S rRNA genes. This study, to our knowledge the first of its kind, focused on comparing the microbial diversity profiles resulting from DNA microarray analyses and conventional cloning and sequencing of 16S rRNA genes arising from a variety of low-biomass surfaces.     

Serum adiponectin is positively associated with lung function in young adults,independent of obesity: The CARDIA study

Rationale

Adipose tissue produces adiponectin, an anti-inflammatory protein. Adiponectin deficiency in mice is associated with abnormal post-natal alveolar development.

Objective

We hypothesized that lower serum adiponectin concentrations are associated with lower lung function in humans, independent of obesity. We explored mediation of this association by insulin resistance and systemic inflammation.

Methods and Measurements

Spirometry testing was conducted at years 10 and 20 follow-up evaluation visits in 2,056 eligible young adult participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Body mass index, serum adiponectin, serum C-reactive protein (a marker of systemic inflammation), and insulin resistance were assessed at year 15.

Main Results

After controlling for body mass index, years 10 and 20 forced vital capacity (FVC) were 81 ml and 82 ml lower respectively (p = 0.004 and 0.01 respectively) in the lowest vs. highest adiponectin quartiles. Similarly, years 10 and 20 forced expiratory volume in one second (FEV₁) were 50 ml and 38 ml lower (p = 0.01 and 0.09, respectively) in the lowest vs. highest adiponectin quartiles. These associations were no longer significant after adjustment for insulin resistance and C-reactive protein. Serum adiponectin was not associated with FEV₁/FVC or peak FEV₁.

Conclusions

Independent of obesity, lower serum adiponectin concentrations are associated with lower lung function. The attenuation of this association after adjustment for insulin resistance and systemic inflammation suggests that these covariates are on a causal pathway linking adiponectin and lung function.     

Detection of Neu1 Sialidase Activity in Regulating TOLL-like Receptor Activation

Mammalian Toll-like receptors (TLRs) are a family of receptors that recognize pathogen-associated molecular patterns. Not only are TLRs crucial sensors of microbial (e.g., viruses, bacteria and parasite) infections, they also play an important role in the pathophysiology of infectious diseases, inflammatory diseases, and possibly in autoimmune diseases. Thus, the intensity and duration of TLR responses against infectious diseases must be tightly controlled. It follows that understanding the structural integrity of sensor receptors, their ligand interactions and signaling components is essential for subsequent immunological protection. It would also provide important opportunities for disease modification through sensor manipulation. Although the signaling pathways of TLR sensors are well characterized, the parameters controlling interactions between the sensors and their ligands still remain poorly defined. We have recently identified a novel mechanism of TLR activation by its natural ligand, which has not been previously observed ^1,2. It suggests that ligand-induced TLR activation is tightly controlled by Neu1 sialidase activation. We have also reported that Neu1 tightly regulates neurotrophin receptors like TrkA and TrkB ³, which involve Neu1 and matrix metalloproteinase-9 (MMP-9) cross-talk in complex with the receptors ⁴. The sialidase assay has been initially use to find a novel ligand, thymoquinone, in the activation of Neu4 sialidase on the cell surface of macrophages, dendritic cells and fibroblast cells via GPCR Gαi proteins and MMP-9 ⁵. For TLR receptors, our data indicate that Neu1 sialidase is already in complex with TLR-2, -3 and -4 receptors, and is induced upon ligand binding to either receptor. Activated Neu1 sialidase hydrolyzes sialyl α-2,3-linked β-galactosyl residues distant from ligand binding to remove steric hinderance to TLR-4 dimerization, MyD88/TLR4 complex recruitment, NFkB activation and pro-inflammatory cell responses. In a collaborative report, Neu1 sialidase has been shown to regulate phagocytosis in macrophage cells ⁶. Taken together, the sialidase assay has provided us with powerful insights to the molecular mechanisms of ligand-induced receptor activation. Although the precise relationship between Neu1 sialidase and the activation of TLR, Trk receptors has yet to be fully elucidated, it would represent a new or pioneering approach to cell regulation pathways.Download video file.^{(57M, mov)}     

Using multiple biomarkers and determinants to obtain a better measurement of oxidative stress: a latent variable structural equation model approach

Purpose: Since oxidative stress involves a variety of cellular changes, no single biomarker can serve as a complete measure of this complex biological process. The analytic technique of structural equation modeling (SEM) provides a possible solution to this problem by modelling a latent (unobserved) variable constructed from the covariance of multiple biomarkers.

Methods: Using three pooled datasets, we modelled a latent oxidative stress variable from five biomarkers related to oxidative stress: F₂-isoprostanes (FIP), fluorescent oxidation products, mitochondrial DNA copy number, γ-tocopherol (Gtoc) and C-reactive protein (CRP, an inflammation marker closely linked to oxidative stress). We validated the latent variable by assessing its relation to pro- and anti-oxidant exposures.

Results: FIP, Gtoc and CRP characterized the latent oxidative stress variable. Obesity, smoking, aspirin use and β-carotene were statistically significantly associated with oxidative stress in the theorized directions; the same exposures were weakly and inconsistently associated with the individual biomarkers.

Conclusions: Our results suggest that using SEM with latent variables decreases the biomarker-specific variability, and may produce a better measure of oxidative stress than do single variables. This methodology can be applied to similar areas of research in which a single biomarker is not sufficient to fully describe a complex biological phenomenon.     

Genomic network analysis of environmental and livestock F-type plasmid populations

F-type plasmids are diverse and of great clinical significance, often carrying genes conferring antimicrobial resistance (AMR) such as extended-spectrum β-lactamases, particularly in Enterobacterales. Organising this plasmid diversity is challenging, and current knowledge is largely based on plasmids from clinical settings. Here, we present a network community analysis of a large survey of F-type plasmids from environmental (influent, effluent and upstream/downstream waterways surrounding wastewater treatment works) and livestock settings. We use a tractable and scalable methodology to examine the relationship between plasmid metadata and network communities. This reveals how niche (sampling compartment and host genera) partition and shape plasmid diversity. We also perform pangenome-style analyses on network communities. We show that such communities define unique combinations of core genes, with limited overlap. Building plasmid phylogenies based on alignments of these core genes, we demonstrate that plasmid accessory function is closely linked to core gene content. Taken together, our results suggest that stable F-type plasmid backbone structures can persist in environmental settings while allowing dramatic variation in accessory gene content that may be linked to niche adaptation. The association of F-type plasmids with AMR may reflect their suitability for rapid niche adaptation.Subject terms: Environmental microbiology, Genomics