Salmonella Typhimurium employs spermidine to exert protection against ROS-mediated cytotoxicity and rewires host polyamine metabolism to ameliorate its survival in macrophages.

Salmonella infection entails a cascade of attacks and defence measures. After breaching the intestinal epithelial barrier, Salmonella is phagocytosed by macrophages, where the bacteria encounter multiple stresses, to which it employs relevant countermeasures. Our study shows that, in Salmonella, the polyamine spermidine activates a stress response mechanism by regulating critical antioxidant genes. Salmonella Typhimurium mutants for spermidine transport and synthesis cannot mount an antioxidative response, resulting in high intracellular ROS levels. These mutants are also compromised in their ability to be phagocytosed by macrophages. Furthermore, it regulates a novel enzyme in Salmonella, Glutathionyl-spermidine synthetase (GspSA), which prevents the oxidation of proteins in E. coli. Moreover, the spermidine mutants and the GspSA mutant show significantly reduced survival in the presence of hydrogen peroxide in vitro and reduced organ burden in the mouse model of Salmonella infection. Conversely, in macrophages isolated from gp91phox-/- mice, we observed a rescue in the attenuated fold proliferation previously observed upon infection. We found that Salmonella upregulates polyamine biosynthesis in the host through its effectors from SPI-1 and SPI-2, which addresses the attenuated proliferation observed in spermidine transport mutants. Thus, inhibition of this pathway in the host abrogates the proliferation of Salmonella Typhimurium in macrophages. From a therapeutic perspective, inhibiting host polyamine biosynthesis using an FDA-approved chemopreventive drug, D, L-α-difluoromethylornithine (DFMO), reduces Salmonella colonisation and tissue damage in the mouse model of infection while enhancing the survival of infected mice. Therefore, our work provides a mechanistic insight into the critical role of spermidine in stress resistance of Salmonella. It also reveals a bacterial strategy in modulating host metabolism to promote their intracellular survival and shows the potential of DFMO to curb Salmonella infection.

Spermidine constitutes a key determinant of motility and attachment of Salmonella Typhimurium through a novel regulatory mechanism.

Spermidine is a poly-cationic molecule belonging to the family of polyamines and is ubiquitously present in all organisms. Salmonella synthesizes, and harbours specialized transporters to import spermidine. A group of polyamines have been shown to assist in Salmonella Typhimurium's virulence and regulation of Salmonella pathogenicity Inslad 1 (SPI-1) genes and stress resistance; however, the mechanism remains elusive. The virulence trait of Salmonella depends on its ability to employ multiple surface structures to attach and adhere to the surface of the target cells before invasion and colonization of the host niche. Our study discovers the mechanism by which spermidine assists in the early stages of Salmonella pathogenesis. For the first time, we report that Salmonella Typhimurium regulates spermidine transport and biosynthesis processes in a mutually inclusive manner. Using a mouse model, we show that spermidine is critical for invasion into the murine Peyer's patches, which further validated our in vitro cell line observation. We show that spermidine controls the mRNA expression of fimbrial (fimA) and non-fimbrial adhesins (siiE, pagN) in Salmonella and thereby assists in attachment to host cell surfaces. Spermidine also regulated the motility through the expression of flagellin genes by enhancing the translation of sigma-28, which features an unusual start codon and a poor Shine-Dalgarno sequence. Besides regulating the formation of the adhesive structures, spermidine tunes the expression of the two-component system BarA/SirA to regulate SPI-1 encoded genes. Thus, our study unravels a novel regulatory mechanism by which spermidine exerts critical functions during Salmonella Typhimurium pathogenesis.

Decoding the invasive nature of a tropical pathogen of concern: The invasive non-Typhoidal Salmonella strains causing host-restricted extraintestinal infections worldwide.

Invasive-Non-Typhoidal Salmonella (iNTS) are the major cause of health concern in the low-income, under-developed nations in Africa and Asia that lack proper sanitation facilities. Around 5% of the NTS cases give rise to invasive, extraintestinal diseases leading to focal infections like osteomyelitis, meningitis, osteoarthritis, endocarditis and neonatal sepsis. iNTS serovars like S. Typhimurium, S. Enteritidis, S. Dublin, S. Choleraesuis show a greater propensity to become invasive than others which hints at the genetic basis of their emergence. The major risk factors attributing to the invasive diseases include immune-compromised individuals having co-infection with malaria or HIV, or suffering from malnutrition. The rampant use of antibiotics leading to the emergence of multi-drug resistant strains poses a great challenge in disease management. An extensive understanding of the iNTS pathogenesis and its epidemiology will open up avenues for the development of new vaccination and therapeutic strategies to restrict the spread of this neglected disease.

Absence of proline-peptide transporter YjiY in Salmonella Typhimurium leads to secretion of factors which inhibits intra-species biofilm formation.

Salmonella is a genus of widely spread Gram negative, facultative anaerobic bacteria, which is known to cause »th of diarrheal morbidity and mortality globally. It causes typhoid fever and gastroenteritis by gaining access to the host gut through contaminated food and water. Salmonella utilizes its biofilm lifestyle to strongly resist antibiotics and persist in the host. Although biofilm removal or dispersal has been studied widely, the inhibition of the initiation of Salmonella Typhimurium (STM WT) biofilm remains elusive. This study demonstrates the anti-biofilm property of the cell-free supernatant obtained from a carbon-starvation induced proline peptide transporter mutant (STM ΔyjiY) strain. The STM ΔyjiY culture supernatant primarily inhibits biofilm initiation by regulating biofilm-associated transcriptional network that is reversed upon complementation (STM ΔyjiY:yjiY). We demonstrate that abundance of FlgM correlates with the absence of flagella in the STM ΔyjiY supernatant treated WT cells. NusG works synergistically with the global transcriptional regulator H-NS. Relatively low abundances of flavoredoxin, glutaredoxin, and thiol peroxidase might lead to accumulation of ROS within the biofilm, and subsequent toxicity in STM ΔyjiY supernatant. This work further suggests that targeting these oxidative stress relieving proteins might be a good choice to reduce Salmonella biofilm.

Variation in normative values of major clinical biochemistry analytes in healthy reproductive-age women in India: A subset of data from a National Indian Council of Medical Research-Polycystic Ovary Syndrome task force study.

OBJECTIVES: Clinical biochemistry reference intervals (RIs) play a crucial role in interpreting patient test results and making informed clinical decisions. Using data from an ongoing Indian Council of Medical Research-National task force study on healthy women, normative ranges for commonly analyzed biochemical analytes were established. MATERIALS AND METHODS: A.total of 13,181 women of reproductive age (18-40 years) were recruited from different urban and rural regions of the country, of which 9898 women signed an informed consent were included. Among these, women having features of hyperandrogenism, menstrual cycle irregularities, and comorbidities were excluded. RIs of 22 analytes were computed in the remaining 938 women controls. To estimate the 95% range of the reference distribution, the limits of the 2.5th percentile and the 97.5th percentile were used in the study. RESULTS: Mean ± standard deviation of age and body mass index of participants was 30.12 ± 6.32 years and 22.8 ± 3.36 kg/m2 respectively. Centiles (2.5th-97.5th) of liver function parameters, lipid parameters, glycaemic parameters, and renal parameters are presented. No significant difference in analytes was observed in relation to the area of residence, and age groups except in albumin (P = 0.03). The distribution of most of the parameters was consistent with the various RI studies conducted in India as well as other countries. CONCLUSION: This is the first study generating biochemical RIs data among a large representative sample of healthy reproductive-age women recruited using a robust design across the country. The resource may serve as a reference range for common biochemical analytes for future in this age group.

Syntaxin 3 SPI-2 dependent crosstalk facilitates the division of Salmonella containing vacuole.

Intracellular membrane fusion is mediated by membrane-bridging complexes of soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs). SNARE proteins are one of the key players in vesicular transport. Several reports shed light on intracellular bacteria modulating host SNARE machinery to establish infection successfully. The critical SNAREs in macrophages responsible for phagosome maturation are Syntaxin 3 (STX3) and Syntaxin 4 (STX4). Reports also suggest that Salmonella actively modulates its vacuole membrane composition to escape lysosomal fusion. Salmonella containing vacuole (SCV) harbours recycling endosomal SNARE Syntaxin 12 (STX12). However, the role of host SNAREs in SCV biogenesis and pathogenesis remains unclear. Upon knockdown of STX3, we observed a reduction in bacterial proliferation, which is concomitantly restored upon the overexpression of STX3. Live-cell imaging of Salmonella-infected cells showed that STX3 localises to the SCV membranes and thus might help in the fusion of SCV with intracellular vesicles to acquire membrane for its division. We also found the interaction STX3-SCV was abrogated when we infected with SPI-2 encoded Type 3 secretion system (T3SS) apparatus mutant (STM ∆ssaV) but not with SPI-1 encoded T3SS apparatus mutant (STM ∆invC). These observations were also consistent in the mice model of Salmonella infection. Together, these results shed light on the effector molecules secreted through T3SS encoded by SPI-2, possibly involved in interaction with host SNARE STX3, which is essential to maintain the division of Salmonella in SCV and help to maintain a single bacterium per vacuole.

Salmonella Typhimurium PgtE is an essential arsenal to defend against the host resident antimicrobial peptides.

Salmonella enterica serovar Typhimurium is a common cause of gastroenteritis in humans and occasionally causes systemic infection. Salmonella's ability to survive and replicate within macrophages is an important characteristic during systemic infection. The outer membrane protease PgtE of S. enterica is a member of the Omptin family of outer membrane aspartate proteases which has well-characterized proteolytic activities in-vitro against a wide range of physiologically relevant substrates. However, no study has been done so far that draws a direct correlation between these in-vitro observations and the biology of the pathogen in-vivo. The main goals of this study were to characterize the pathogenesis-associated functions of pgtE and study its role in the intracellular survival and in-vivo virulence of Salmonella Typhimurium. Our study elucidated a possible role of Salmonella Typhimurium pgtE in combating host antimicrobial peptide- bactericidal/ permeability increasing protein (BPI) to survive in human macrophages. The pgtE-deficient strain of Salmonella showed attenuated proliferation and enhanced colocalization with BPI in U937 and Thp1 cells. In the presence of polymixin B, the attenuated in-vitro survival of STM ΔpgtE suggested a role of PgtE against the antimicrobial peptides. In addition, our study revealed that compared to the wild type Salmonella, the pgtE mutant is replication-deficient in C57BL/6 mice. Further, we showed that PgtE interacts directly with several antimicrobial peptides (AMPs) in the host gut. This gives the pathogen a survival advantage and helps to mount a successful infection in the host.

The mucormycosis and stroke: The learning curve during the second COVID-19 pandemic.

BACKGROUND: The Angio-invasive Rhino-orbito-cerebral mucormycosis (ROCM) producing strokes is a less explored entity. Our hospital, a stroke-ready one, had an opportunity to manage mucormycosis when it was identified as the nodal center for mucormycosis management. We are sharing our experiences and mistakes in managing the cerebrovascular manifestations of ROCM. METHODS: We conducted a prospective observational study during the second wave of the COVID-19 pandemic from 1st May 2021 to 30th September 2021, where consecutive patients aged more than 18 years with microbiologically confirmed cases of ROCM were included. Clinical details (timing of stroke onset after ROCM symptoms, GCS, NIHSS), imaging findings (ASPECTS, the territory of stroke, the pattern of infarct, hemorrhagic transformation, cavernous sinus thrombosis), angiogram findings, management details (IV thrombolysis), and outcomes (mRS at discharge and duration of hospital stay) were documented. We also compared the demographics, clinical features (NIHSS), radiological findings, treatment details, duration of hospital stay, and functional outcome at the discharge of the ROCM stroke patients with stroke patients without ROCM. RESULTS: Stroke developed in 42% of patients with ROCM, predominantly anterior circulation border zone ischemic infarcts. Strokes occurred after a median of five days from the onset of ROCM symptoms. The most common vessel involved was the ophthalmic artery, followed by the cavernous ICA. We could not thrombolyse ROCM stroke patients. ROCM patients who developed stroke compared with patients without stroke had a more infiltrative fungal infection and higher inflammatory markers. Mucormycosis associated stroke patients had higher in-hospital mortality and poor functional outcomes. T CONCLUSION: Due to delayed recognition of stroke symptoms, none received reperfusion strategies, leading to poor functional outcomes. For early stroke detection, ROCM cases need frequent monitoring and education of patients and their relatives about the ALS acronym (loss of ambulation, limb weakness, and loss of speech).

Diagnostic ability of superficial vascular density measured by optical coherence tomography angiography to differentiate high myopic eyes from eyes with primary open angle glaucoma.

Purpose: To determine if high myopia and glaucoma can be differentiated based on the measurement of superficial vascular density in the peripapillary and macular areas by using Optical Coherence Tomography Angiography (OCTA). Methods: This prospective, observational, cross-sectional, comparative study was conducted on patients between 40 and 60 years of age diagnosed as primary open-angle glaucoma (POAG) or high myopia and compared with age-matched controls. The main outcome measures were the difference in SVD% in peripapillary and macular areas in POAG and high myopic eyes. Detailed ophthalmic examination and OCTA of the disc and peripapillary area and macula were performed. The SVD in each zone was calculated using ImageJ software and their difference were analyzed. Results: In total, 128 eyes of 70 patients were enrolled. Peripapillary SVD% in controls was 45.07 ± 3.44, 40.36 ± 8.27 in high myopia, and 31.80 ± 9.008 in POAG. The mean difference in peripapillary SVD% of POAG to control was - 13.479, of POAG to high myopia was -8.777 (both P < 0.001), and of high myopia to controls was -4.701 (P = 0.012). Macular SVD% in controls was 27.30 ± 3.438, 22.33 ± 6.011 in high myopia, and 21.21 ± 5.598 in POAG. The mean difference in macular SVD% of POAG to controls was -6.088, of high myopia to controls was -4.965 (both P < 0.001), and of POAG to high myopia was -1.122 (P = 0.984; not statistically significant). Conclusion: OCTA is a useful diagnostic tool in distinguishing glaucomatous and myopic eyes. The measurement of peripapillary SVD has a greater discriminatory ability than that of the macular area.

Salmonella Typhimurium U32 peptidase, YdcP, promotes bacterial survival by conferring protection against in vitro and in vivo oxidative stress.

YdcP, a U32 peptidase, is characterized as a putative collagenase with a role in several bacterial infections. However, its role in the pathogenesis of Salmonella Typhimurium remains elusive. Here, we investigated the role of U32 peptidase, YdcP, in the intracellular survival of S. Typhimurium (STM). Our study revealed a novel function of YdcP in protecting wild-type Salmonella from in vitro and in vivo oxidative stress. The ydcP knockout strain showed attenuated intracellular proliferation within the murine and human macrophages. Incubation of wild-type Salmonella with H2O2 induced the transcript level expression of ydcP. Moreover, deleting ydcP increased the susceptibility of the bacteria to in vitro oxidative stress. STM ΔydcP showed increased colocalization with the gp91phox subunit of the NADPH phagocytic oxidase in RAW264.7 cells. Further, we observed a reduction in the expression of bacterial anti-oxidant genes in STM ΔydcP growing within the RAW264.7 cells. The delay in the death of BALB/c mice infected with STM ΔydcP proved the association of ydcP with the in vivo pathogenesis of Salmonella. Finally, the attenuated growth of the ydcP mutant in wild-type C57BL/6 mice and the recovery of their growth inhibition in gp91phox-/- C57BL/6 mice endorsed the role of ydcP in protecting Salmonella from in vivo oxidative stress. Together, our study depicts a novel role of Salmonella Typhimurium YdcP, a putative U32 peptidase in rendering protection against oxidative stress.

Improved chromosome-level genome assembly of the Glanville fritillary butterfly (Melitaea cinxia) integrating Pacific Biosciences long reads and a high-density linkage map.

BACKGROUND: The Glanville fritillary (Melitaea cinxia) butterfly is a model system for metapopulation dynamics research in fragmented landscapes. Here, we provide a chromosome-level assembly of the butterfly's genome produced from Pacific Biosciences sequencing of a pool of males, combined with a linkage map from population crosses. RESULTS: The final assembly size of 484 Mb is an increase of 94 Mb on the previously published genome. Estimation of the completeness of the genome with BUSCO indicates that the genome contains 92-94% of the BUSCO genes in complete and single copies. We predicted 14,810 genes using the MAKER pipeline and manually curated 1,232 of these gene models. CONCLUSIONS: The genome and its annotated gene models are a valuable resource for future comparative genomics, molecular biology, transcriptome, and genetics studies on this species.

Long-term spatiotemporal genetic structure of an accidental parasitoid introduction, and local changes in prevalence of its associated Wolbachia symbiont.

Population bottlenecks associated with founder events strongly impact the establishment and genetic makeup of populations. In addition to their genotype, founding individuals also bring along parasites, as well as symbionts that can manipulate the phenotype of their host, affecting the host population establishment, dynamics and evolution. Thus, to understand introduction, invasion, and spread, we should identify the roles played by accompanying symbionts. In 1991, the parasitoid wasp, Hyposoter horticola, and its associated hyperparasitoid were accidentally introduced from the main Åland islands, Finland, to an isolated island in the archipelago, along with their host, the Glanville fritillary butterfly. Though the receiving island was unoccupied, the butterfly was present on some of the small islands in the vicinity. The three introduced species have persisted locally ever since. A strain of the endosymbiotic bacterium Wolbachia has an intermediate prevalence in the parasitoid H. horticola across the main Åland population. The infection increases its susceptibility of to hyperparasitism. We investigated the establishment and spread of the parasitoid, along with patterns of prevalence of its symbiont using 323 specimens collected between 1992 and 2013, from five localities across Åland, including the source and introduced populations. Using 14 microsatellites and one mitochondrial marker, we suggest that the relatively diverse founding population and occasional migration between islands might have facilitated the persistence of all isolated populations, despite multiple local population crashes. We also show that where the hyperparasitoid is absent, and thus selection against infected wasp genotypes is relaxed, there is near-fixation of Wolbachia.

An elegant nano-injection machinery for sabotaging the host: Role of Type III secretion system in virulence of different human and animal pathogenic bacteria.

Various Gram-negative bacteria possess a specialized membrane-bound protein secretion system known as the Type III secretion system (T3SS), which transports the bacterial effector proteins into the host cytosol thereby helping in bacterial pathogenesis. The T3SS has a special needle-like translocon that can sense the contact with the host cell membrane and translocate effectors. The export apparatus of T3SS recognizes these effector proteins bound to chaperones and translocates them into the host cell. Once in the host cell cytoplasm, these effector proteins result in modulation of the host system and promote bacterial localization and infection. Using molecular biology, bioinformatics, genetic techniques, electron microscopic studies, and mathematical modeling, the structure and function of the T3SS and the corresponding effector proteins in various bacteria have been studied. The strategies used by different human pathogenic bacteria to modulate the host system and thereby enhance their virulence mechanism using T3SS have also been well studied. Here we review the history, evolution, and general structure of the T3SS, highlighting the details of its comparison with the flagellar export machinery. Also, this article provides mechanistic details about the common role of T3SS in subversion and manipulation of host cellular processes. Additionally, this review describes specific T3SS apparatus and the role of their specific effectors in bacterial pathogenesis by considering several human and animal pathogenic bacteria.

Bioaerosols in the landfill environment: an overview of microbial diversity and potential health hazards.

Landfilling is one of the indispensable parts of solid waste management in various countries. Solid waste disposed of in landfill sites provides nutrients for the proliferation of pathogenic microbes which are aerosolized into the atmosphere due to the local meteorology and various waste disposal activities. Bioaerosols released from landfill sites can create health issues for employees and adjoining public. The present study offers an overview of the microbial diversity reported in the air samples collected from various landfill sites worldwide. This paper also discusses other aspects, including effect of meteorological conditions on the bioaerosol concentrations, sampling techniques, bioaerosol exposure and potential health impacts. Analysis of literature concluded that landfill air is dominated by microbial dust or various pathogenic microbes like Enterobacteriaceae, Staphylococcus aureus, Clostridium perfringens, Acinetobacter calcoaceticus and Aspergillus fumigatus. The bioaerosols present in the landfill environment are of respirable sizes and can penetrate deep into lower respiratory systems and trigger respiratory symptoms and chronic pulmonary diseases. Most studies reported higher bioaerosol concentrations in spring and summer as higher temperature and relative humidity provide a favourable environment for survival and multiplication of microbes. Landfill workers involved in solid waste disposal activities are at the highest risk of exposure to these bioaerosols due to their proximity to solid waste and as they practise minimum personal safety and hygiene measures during working hours. Workers are recommended to use personal protective equipment and practise hygiene to reduce the impact of occupational exposure to bioaerosols.

Economic Model Predictive Control for optimal struvite recovery.

Resource recovery from municipal wastewater has been a prime focus for a decade. Although several recovery processes already exist in the market today, the high cost of material, inherent disturbance in the influent quality, lack of real time monitoring of critical parameters, and lack of a robust automation system may result in suboptimal performance. This work attempts to construct a model based predictive control for optimal operation of a struvite recovery unit in a full scale WRRF. A multi-parameter based predictive control has been developed by implementing an Economic Model Predictive Controller (EMPC) for optimal dosing of magnesium hydroxide in a struvite recovery unit. The EMPC used customized objective function for real-time optimization of performance and economical parameters of the crystallization unit. The effectiveness of the proposed EMPC controller is verified through tests conducted on the Benchmark Simulation Model No. 2 (BSM2d.). The results obtained from the simulator-based evaluation of EMPC demonstrate a significant improvement in resource recovery at reduced operational costs. The economic advantages of implementing an EMPC compared to proportional and constant magnesium dosage has also been enumerated.

Implementing an Extended Kalman Filter for estimating nutrient composition in a sequential batch MBBR pilot plant.

Online monitoring of water quality parameters can provide better control over various operations in wastewater treatment plants. However, a lack of physical online sensors, the high price of the available online water-quality analyzers, and the need for regular maintenance and calibration prevent frequent use of online monitoring. Soft-sensors are viable alternatives, with advantages in terms of price and flexibility in operation. As an example, this work presents the development, tuning, implementation, and validation of an Extended Kalman Filter (EKF) on a grey-box model to estimate the concentration of volatile fatty acids (VFA), soluble phosphates (PO4-P), ammonia nitrogen (NH4-N) and nitrate nitrogen (NO3-N) using simple and inexpensive sensors such as pH and dissolved oxygen (DO). The EKF is implemented in a sequential batch moving bed biofilm reactor (MBBR) pilot scale unit used for biological phosphorus removal from municipal wastewater. The grey-box model, used for soft sensing, was constructed by fitting the kinetic data from the pilot plant to a reduced order version of ASM2d model. The EKF is successfully validated against the standard laboratory measurements, which confirms its ability to estimate various states during the continuous operation of the pilot plant.

Rhizospheric life of Salmonella requires flagella-driven motility and EPS-mediated attachment to organic matter and enables cross-kingdom invasion.

Salmonella is an established pathogen of the members of the kingdom Animalia. Reports indicate that the association of Salmonella with fresh, edible plant products occurs at the pre-harvest state, i.e. in the field. In this study, we follow the interaction of Salmonella Typhimurium with the model plant Arabidopsis thaliana to understand the process of migration in soil. Plant factors like root exudates serve as chemo-attractants. Our ex situ experiments allowed us to track Salmonella from its free-living state to the endophytic state. We found that genes encoding two-component systems and proteins producing extracellular polymeric substances are essential for Salmonella to adhere to the soil and roots. To understand the trans-kingdom flow of Salmonella, we fed the contaminated plants to mice and observed that it invades and colonizes liver and spleen. To complete the disease cycle, we re-established the infection in plant by mixing the potting mixture with the fecal matter collected from the diseased animals. Our experiments revealed a cross-kingdom invasion by the pathogen via passage through a murine intermediate, a mechanism for its persistence in the soil and invasion in a non-canonical host. These results form a basis to break the life-cycle of Salmonella before it reaches its animal host and thus reduce Salmonella contamination of food products.

The first draft genomes of the ant Formica exsecta, and its Wolbachia endosymbiont reveal extensive gene transfer from endosymbiont to host.

BACKGROUND: Adapting to changes in the environment is the foundation of species survival, and is usually thought to be a gradual process. However, transposable elements (TEs), epigenetic modifications, and/or genetic material acquired from other organisms by means of horizontal gene transfer (HGTs), can also lead to novel adaptive traits. Social insects form dense societies, which attract and maintain extra- and intracellular accessory inhabitants, which may facilitate gene transfer between species. The wood ant Formica exsecta (Formicidae; Hymenoptera), is a common ant species throughout the Palearctic region. The species is a well-established model for studies of ecological characteristics and evolutionary conflict. RESULTS: In this study, we sequenced and assembled draft genomes for F. exsecta and its endosymbiont Wolbachia. The F. exsecta draft genome is 277.7 Mb long; we identify 13,767 protein coding genes, for which we provide gene ontology and protein domain annotations. This is also the first report of a Wolbachia genome from ants, and provides insights into the phylogenetic position of this endosymbiont. We also identified multiple horizontal gene transfer events (HGTs) from Wolbachia to F. exsecta. Some of these HGTs have also occurred in parallel in multiple other insect genomes, highlighting the extent of HGTs in eukaryotes. CONCLUSION: We present the first draft genome of ant F. exsecta, and its endosymbiont Wolbachia (wFex), and show considerable rates of gene transfer from the symbiont to the host. We expect that especially the F. exsecta genome will be valuable resource in further exploration of the molecular basis of the evolution of social organization.

Increased fluctuation in a butterfly metapopulation leads to diploid males and decline of a hyperparasitoid.

Climate change can increase spatial synchrony of population dynamics, leading to large-scale fluctuation that destabilizes communities. High trophic level species such as parasitoids are disproportionally affected because they depend on unstable resources. Most parasitoid wasps have complementary sex determination, producing sterile males when inbred, which can theoretically lead to population extinction via the diploid male vortex (DMV). We examined this process empirically using a hyperparasitoid population inhabiting a spatially structured host population in a large fragmented landscape. Over four years of high host butterfly metapopulation fluctuation, diploid male production by the wasp increased, and effective population size declined precipitously. Our multitrophic spatially structured model shows that host population fluctuation can cause local extinctions of the hyperparasitoid because of the DMV. However, regionally it persists because spatial structure allows for efficient local genetic rescue via balancing selection for rare alleles carried by immigrants. This is, to our knowledge, the first empirically based study of the possibility of the DMV in a natural host-parasitoid system.

Spatial and temporal genetic structure at the fourth trophic level in a fragmented landscape.

A fragmented habitat becomes increasingly fragmented for species at higher trophic levels, such as parasitoids. To persist, these species are expected to possess life-history traits, such as high dispersal, that facilitate their ability to use resources that become scarce in fragmented landscapes. If a specialized parasitoid disperses widely to take advantage of a sparse host, then the parasitoid population should have lower genetic structure than the host. We investigated the temporal and spatial genetic structure of a hyperparasitoid (fourth trophic level) in a fragmented landscape over 50 × 70 km, using microsatellite markers, and compared it with the known structures of its host parasitoid, and the butterfly host which lives as a classic metapopulation. We found that population genetic structure decreases with increasing trophic level. The hyperparasitoid has fewer genetic clusters (K = 4), than its host parasitoid (K = 15), which in turn is less structured than the host butterfly (K = 27). The genetic structure of the hyperparasitoid also shows temporal variation, with genetic differentiation increasing due to reduction of the population size, which reduces the effective population size. Overall, our study confirms the idea that specialized species must be dispersive to use a fragmented host resource, but that this adaptation has limits.