Apirhabdus apintestini gen. nov., sp. nov., a member of a novel genus of the family Enterobacteriaceae, isolated from the gut of the western honey bee Apis mellifera

A Gram-negative, motile, rod-shaped bacterial strain, CA-0114T, was isolated from the midgut of a western honey bee, Apis mellifera. The isolate exhibited ≤96.43 % 16S rRNA gene sequence identity (1540 bp) to members of the families Enterobacteriaceae and Erwiniaceae. Phylogenetic trees based on genome blast distance phylogeny and concatenated protein sequences encoded by conserved genes atpD, fusA, gyrB, infB, leuS, pyrG and rpoB separated the isolate from other genera forming a distinct lineage in the Enterobacteriaceae. In both trees, the closest relatives were Tenebrionicola larvae YMB-R21T and Tenebrionibacter intestinalis BIT-L3T, which were isolated previously from Tenebrio molitor L., a plastic-eating mealworm. Digital DNA-DNA hybridization, orthologous average nucleotide identity and average amino acid identity values between strain CA-0114T and the closest related members within the Enterobacteriaceae were ≤23.1, 75.45 and 76.04 %, respectively. The complete genome of strain CA-0114T was 4 451669 bp with a G+C content of 52.12 mol%. Notably, the apparent inability of strain CA-0114T to ferment d-glucose, inositol and l-rhamnose in the API 20E system is unique among closely related members of the Enterobacteriaceae. Based on the results obtained through genotypic and phenotypic analysis, we propose that strain CA-0114T represents a novel species and genus within the family Enterobacteriaceae, for which we propose the name Apirhabdus apintestini gen. nov., sp. nov. (type strain CA-0114T=ATCC TSD-396T=DSM 116385T).

Probiotics and in-hive fermentation as a source of beneficial microbes to support the gut microbial health of honey bees

Managed populations of honey bees (Apis mellifera Linnaeus; Hymenoptera: Apidae) are regularly exposed to infectious diseases. Good hive management including the occasional application of antibiotics can help mitigate infectious outbreaks, but new beekeeping tools and techniques that bolster immunity and help control disease transmission are welcome. In this review, we focus on the applications of beneficial microbes for disease management as well as to support hive health and sustainability within the apicultural industry. We draw attention to the latest advances in probiotic approaches as well as the integration of fermented foods (such as water kefir) with disease-fighting properties that might ultimately be delivered to hives as an alternative or partial antidote to antibiotics. There is substantial evidence from in vitro laboratory studies that suggest beneficial microbes could be an effective method for improving disease resistance in honey bees. However, colony level evidence is lacking and there is urgent need for further validation via controlled field trials experimentally designed to test defined microbial compositions against specific diseases of interest.

Delivery mechanism can enhance probiotic activity against honey bee pathogens

Managed honey bee (Apis mellifera) populations play a crucial role in supporting pollination of food crops but are facing unsustainable colony losses, largely due to rampant disease spread within agricultural environments. While mounting evidence suggests that select lactobacilli strains (some being natural symbionts of honey bees) can protect against multiple infections, there has been limited validation at the field-level and few methods exist for applying viable microorganisms to the hive. Here, we compare how two different delivery systems-standard pollen patty infusion and a novel spray-based formulation-affect supplementation of a three-strain lactobacilli consortium (LX3). Hives in a pathogen-dense region of California are supplemented for 4 weeks and then monitored over a 20-week period for health outcomes. Results show both delivery methods facilitate viable uptake of LX3 in adult bees, although the strains do not colonize long-term. Despite this, LX3 treatments induce transcriptional immune responses leading to sustained decreases in many opportunistic bacterial and fungal pathogens, as well as selective enrichment of core symbionts including Bombilactobacillus, Bifidobacterium, Lactobacillus, and Bartonella spp. These changes are ultimately associated with greater brood production and colony growth relative to vehicle controls, and with no apparent trade-offs in ectoparasitic Varroa mite burdens. Furthermore, spray-LX3 exerts potent activities against Ascosphaera apis (a deadly brood pathogen) likely stemming from in-hive dispersal differences, whereas patty-LX3 promotes synergistic brood development via unique nutritional benefits. These findings provide a foundational basis for spray-based probiotic application in apiculture and collectively highlight the importance of considering delivery method in disease management strategies.

A kin-selection model of fairness in heterogeneous populations

Humans and other primates exhibit pro-social preferences for fairness. These preferences are thought to be reinforced by strong reciprocity, a policy that rewards fair actors and punishes unfair ones. Theories of fairness based on strong reciprocity have been criticized for overlooking the importance of individual differences in socially heterogeneous populations. Here, we explore the evolution of fairness in a heterogeneous population. We analyse the Ultimatum Game in cases where players' roles in the game are determined by their status. Importantly, our model allows for non-random pairing of players, and so we also explore the role played by kin selection in shaping fairness. Our kin-selection model shows that, when individuals condition their behaviour on their role in the game, fairness can be understood as either altruistic or spiteful. Altruistic fairness directs resources from less valuable members of a genetic lineage to more valuable members of the same lineage, whereas spiteful fairness keeps resources away from the competitors of the actor's high-value relatives. When individuals express fairness unconditionally it can be understood as altruistic or selfish. When it is altruistic, unconditional fairness again serves to direct resources to high-value members of genetic lineages. When it is selfish, unconditional fairness simply improves an individual's own standing. Overall, we expand kin-selection based explanations for fairness to include motivations other than spite. We show, therefore, that one need not invoke strong reciprocity to explain the advantage of fairness in heterogeneous populations.

Disentangling the microbial ecological factors impacting honey bee susceptibility to Paenibacillus larvae infection

Paenibacillus larvae is a spore-forming bacterial entomopathogen and causal agent of the important honey bee larval disease, American foulbrood (AFB). Active infections by vegetative P. larvae are often deadly, highly transmissible, and incurable for colonies but, when dormant, the spore form of this pathogen can persist asymptomatically for years. Despite intensive investigation over the past century, this process has remained enigmatic. Here, we provide an up-to-date synthesis on the often overlooked microbiota factors involved in the spore-to-vegetative growth transition (corresponding with the onset of AFB disease symptoms) and offer a novel outlook on AFB pathogenesis by focusing on the 'collaborative' and 'competitive' interactions between P. larvae and other honey bee-adapted microorganisms. Furthermore, we discuss the health trade-offs associated with chronic antibiotic exposure and propose new avenues for the sustainable control of AFB via probiotic and microbiota management strategies.

No obvious transcriptome-wide signature of indirect selection in termites

The evolution of sterile helper castes in social insects implies selection on genes that underlie variation in this nonreproductive phenotype. These focal genes confer no direct fitness and are presumed to evolve through indirect fitness effects on the helper's reproducing relatives. This separation of a gene's phenotypic effect on one caste and its fitness effect on another suggests that genes for this and other forms of reproductive altruism are buffered from selection and will thus evolve closer to the neutral rate than genes directly selected for selfish reproduction. We test this hypothesis by comparing the strength of selection at loci associated in their expression with reproductive versus sterile castes in termites. Specifically, we gather caste-biased gene expression data from four termite transcriptomes and measure the global dN/dS ratio across gene sets and phylogenetic lineages. We find that the majority of examined orthologous gene groups show patterns of nucleotide substitution that are consistent with strong purifying selection and display little evidence for distinct signatures of direct versus indirect selection in reproductive and sterile castes. For one particular species (Reticulitermes flavipes), the strength of purifying selection is relaxed in a reproductive nymph-biased gene set, which opposes the nearly neutral idea. In other species, the synonymous rate (dS) alone was often found to be the highest in the sterile worker caste, suggesting a more subtle signature of indirect selection or an altogether different relationship between caste-biased expression and rates of molecular evolution.

Lactobacillus spp. attenuate antibiotic-induced immune and microbiota dysregulation in honey bees

Widespread antibiotic usage in apiculture contributes substantially to the global dissemination of antimicrobial resistance and has the potential to negatively influence bacterial symbionts of honey bees (Apis mellifera). Here, we show that routine antibiotic administration with oxytetracycline selectively increased tetB (efflux pump resistance gene) abundance in the gut microbiota of adult workers while concurrently depleting several key symbionts known to regulate immune function and nutrient metabolism such as Frischella perrera and Lactobacillus Firm-5 strains. These microbial changes were functionally characterized by decreased capped brood counts (marker of hive nutritional status and productivity) and reduced antimicrobial capacity of adult hemolymph (indicator of immune competence). Importantly, combination therapy with three immunostimulatory Lactobacillus strains could mitigate antibiotic-associated microbiota dysbiosis and immune deficits in adult workers, as well as maximize the intended benefit of oxytetracycline by suppressing larval pathogen loads to near-undetectable levels. We conclude that microbial-based therapeutics may offer a simple but effective solution to reduce honey bee disease burden, environmental xenobiotic exposure, and spread of antimicrobial resistance.

Daisley et al. show that antibiotic treatment with oxytetracycline impairs the gut microbiota and immune system of honey bees, and reduces capped brood counts. They also show that supplementation with lactobacilli during antibiotic recovery can reverse the harmful effects of the antibiotic treatment. Their findings offer a simple microbial-based solution that aims to reduce honey bee disease burden, environmental pollution by xenobiotics, and spread of antimicrobial resistance.

Gene-regulatory context of honey bee worker sterility

The highly organized societies of the Western honey bee Apis mellifera feature a highly reproductive queen at the center of attention and a large cohort of daughters that suppress their own reproduction to help rear more sisters, some of whom become queens themselves. This reproductive altruism is peculiar because in theory it evolves via indirect selection on genes for altruism that are expressed in the sterile workers but not in the reproductive queens. In this study we attempt to situate lists of genes previously implicated in queenright worker sterility into a broader regulatory framework. To do so we use a model bee brain transcriptional regulatory network as a template to infer how sets of genes responsive to ovary-suppressing queen pheromone are functionally interconnected over the model's topology. We predict that genes jointly involved in the regulation of worker sterility should be tightly networked, relative to genes whose functions are unrelated to each other. We find that sets of mapped genes - ranging in size from 17 to 250 - are well dispersed across the network's substructural scaffolds, suggesting that ovary de-activation involves genes that reside within more than one transcriptional regulatory module. For some sets, however, this dispersion is biased into certain areas of the network's substructure. Our analysis identifies the regions enriched for sterility genes and likewise identifies local hub genes that are presumably critical to subnetwork function. Our work offers a glimpse into the gene regulatory context of honey bee worker sterility and uses this context to identify new candidate gene targets for functional analysis. Finally, to the extent that any sterility-related modules identified here have evolved via selection for worker altruism, we can assume that this selection was indirect and of the type specifically invoked by inclusive fitness theory.

Missing Microbes in Bees: How Systematic Depletion of Key Symbionts Erodes Immunity

Pesticide exposure, infectious disease, and nutritional stress contribute to honey bee mortality and a high rate of colony loss. This realization has fueled a decades-long investigation into the single and combined effects of each stressor and their overall bearing on insect physiology. However, one element largely missing from this research effort has been the evaluation of underlying microbial communities in resisting environmental stressors and their influence on host immunity and disease tolerance. In humans, multigenerational bombardment by antibiotics is linked with many contemporary diseases. Here, we draw a parallel conclusion for the case in honey bees and suggest that chronic exposure to antimicrobial xenobiotics can systematically deplete honey bees of their microbes and hamper cross-generational preservation of host-adapted symbionts that are crucial to health.

Relish as a Candidate Marker for Transgenerational Immune Priming in a Dampwood Termite (Blattodae: Archeotermopsidae)

Natural selection should favor the transfer of immune competence from one generation to the next in a context-dependent manner. Transgenerational immune priming (TGIP) is expected to evolve when species exploit pathogen-rich environments and exhibit extended overlap of parent-offspring generations. Dampwood termites are hemimetabolous, eusocial insects (Blattodea: Archeotermopsidae) that possess both of these traits. We predict that offspring of pathogen-exposed queens of Zootermopsis angusticollis will show evidence of a primed immune system relative to the offspring of unexposed controls. We found that Relish transcripts, one of two immune marker loci tested, were enhanced in two-day-old embryos when laid by Serratia-injected queens. These data implicate the immune deficiency (IMD) signaling pathway in TGIP. Although an independent antibacterial assay revealed that embryos do express antibacterial properties, these do not vary as a function of parental treatment. Taken together, Z. angusticollis shows transcriptional but not translational evidence for TGIP. This apparent incongruence between the transcriptional and antimicrobial response from termites suggests that effectors are either absent in two-day-old embryos or their activity is too subtle to detect with our antibacterial assay. In total, we provide the first suggestive evidence of transgenerational immune priming in a termite.

Novel probiotic approach to counter Paenibacillus larvae infection in honey bees

American foulbrood (AFB) is a highly virulent disease afflicting honey bees (Apis mellifera). The causative organism, Paenibacillus larvae, attacks honey bee brood and renders entire hives dysfunctional during active disease states, but more commonly resides in hives asymptomatically as inactive spores that elude even vigilant beekeepers. The mechanism of this pathogenic transition is not fully understood, and no cure exists for AFB. Here, we evaluated how hive supplementation with probiotic lactobacilli (delivered through a nutrient patty; BioPatty) affected colony resistance towards a naturally occurring AFB outbreak. Results demonstrated a significantly lower pathogen load and proteolytic activity of honey bee larvae from BioPatty-treated hives. Interestingly, a distinctive shift in the microbiota composition of adult nurse bees occurred irrespective of treatment group during the monitoring period, but only vehicle-supplemented nurse bees exhibited higher P. larvae loads. In vitro experiments utilizing laboratory-reared honey bee larvae showed Lactobacillus plantarum Lp39, Lactobacillus rhamnosus GR-1, and Lactobacillus kunkeei BR-1 (contained in the BioPatty) could reduce pathogen load, upregulate expression of key immune genes, and improve survival during P. larvae infection. These findings suggest the usage of a lactobacilli-containing hive supplement, which is practical and affordable for beekeepers, may be effective for reducing enzootic pathogen-related hive losses.

P14.30 Treatment outcomes of newly-diagnosed glioblastoma multiforme (GBM) by O6-methylguanine DNA methyltransferase promoter (MGMT) status: a multi-country study

INTRODUCTION

This study evaluated the relationship of MGMT status with first-line (1L) treatment outcomes of patients with newly-diagnosed GBM in France, Germany, Italy, Spain, the UK (EU5), and Canada.

MATERIALS AND METHODS

Medical oncologists and neuro-oncologists across EU5 and Canada completed a point in time, cross-sectional survey for the next 8 GBM patients seen between May and July 2016 within EU5 and Canada. All results apart from time to progression (TTP) were presented for patients receiving 1L active drug treatment. TTP was calculated from initiation of 1L treatment to initiation of second-line treatment. Results presented are statistically significant (p<0.05) unless otherwise specified. Bases vary depending on data availability.

RESULTS

A total of 241 physicians reported on 1747 patients with GBM. 875 were receiving 1L active drug treatment at time of survey. Mean age was 59.7 years (median=61) and 34.6% were women. Mean life expectancy was 14.9 months (median=12) at diagnosis and mean TTP was 8.5 months (median=7.3). Surgery was performed in 62% of patients (n=546) prior to 1L drug treatment; 38% of patients (n=329) had no surgery. Patients with surgery had a higher life expectancy at diagnosis vs patients with no surgery prior to 1L (mean=16.4 vs 12.2 months; median=15.0 vs 12.0). Patients who received corticosteroids (n=524) vs no corticosteroids during radiotherapy (n=64) had a shorter life expectancy at diagnosis (mean=15.0 vs 16.8 months, p=0.07; median=12.5 vs 13.9) and were more likely to have 8 or more inpatient days due to GBM (21% vs 8%, p=0.07) in the last 3 months prior to the survey. 62% of patients (n=541) had an MGMT-status recorded (tested: methylated or unmethylated), and 38% (n=334) were untested/ awaiting results (untested) at 1L. MGMT-tested patients had better life expectancy at diagnosis (mean=16.1 vs 12.9 months; median=15.0 vs 12.0) and longer TTP (mean=8.9 vs 7.8 months; median=7.8 vs 6.4) than untested patients. Among MGMT-tested patients, 58% were methylated and 42% were unmethylated. Methylated patients had similar life expectancy at diagnosis (mean=15.9 vs 16.3 months, p=0.85; median=15.0 vs 15.0) and TTP (mean=9.0 vs 8.8 months, p=0.42; median=8.0 vs 7.5) as unmethylated patients.

CONCLUSIONS

This analysis provides valuable insights into the 1L treatment outcomes of GBM patients in EU5 and Canada. Patients who did not undergo surgery had worse treatment outcomes. Steroid use appears to be associated with worse outcomes and higher healthcare resource utilization. Patient treatment outcomes varied depending on whether they are MGMT tested.

P14.36 Treatment patterns by O6-methylguanine DNA methyltransferase promoter (MGMT) status in newly-diagnosed glioblastoma multiforme (GBM): a multi-country chart review study

INTRODUCTION

This study explored the relationship between MGMT testing and treatment patterns of patients with newly-diagnosed GBM from France, Germany, Italy, Spain, the UK (EU5), and Canada.

MATERIALS AND METHODS

Medical oncologists and neuro-oncologists across EU5 and Canada completed a point in time, cross-sectional survey for the next eight GBM patients seen between May and July 2016 (GBM Disease-specific ProgrammeTM). Statistically significant differences (p<0.05) between groups are presented.

RESULTS

A total of 241 physicians reported on 1,747 GBM patients. 1L patients had mean age 59.7 years (SD=12.3) and 36% were female. Of 1,113 (64%) patients who had an MGMT test performed with results recorded (tested), 58% (n=651) were methylated and 42% (n=462) were unmethylated. The remaining 634 patients (36%) were MGMT untested or awaiting MGMT results at time of survey (untested). Overall, 63% of patients received surgery prior to their 1L drug therapy, 78% received radiotherapy (RT; mean 4.3 sessions) in conjunction with 1L drug therapy, 90% received corticosteroids during RT, and 89% received temozolomide (TMZ). Patients who received corticosteroids during RT received similar drug treatments to those that did not, but were less likely to receive surgery prior to 1L treatment (65% vs 83%). MGMT-tested patients were more likely to receive surgery (66% vs 57%) and RT (81% vs 71%) than untested patients. Tested patients were also more likely to receive TMZ (92% vs 83%), and less likely to receive procarbazine+/lomustine+/vincristine (PCV; 3% vs 7%) or other chemotherapies (5% vs 11%). For 1L patients that experienced side effects, the most common effects included fatigue (74%), nausea (60%), and appetite loss (59%). Untested patients were more likely to stop their 1L drug treatment due to progression/recurrence of GBM (44% vs 36%). Patients who received surgery prior to 1L treatment were more likely to receive TMZ than those who did not (93% vs 82%). Among MGMT tested patients at 1L, methylated patients were more likely to receive RT (84% vs 78%) and TMZ (95% vs 89%) than unmethylated patients, and less likely to receive PCV (2% vs 5%) or other chemotherapy (4% vs 7%). Methylated patients with reported treatment-related side effects were less likely to experience dehydration (0% vs 10%), loss of strength/unusual weakness (5% vs 25%), memory problems (16% vs 35%), and nausea (51% vs 75%).

CONCLUSIONS

More than one-third of GBM patients in EU5 and Canada are not tested for MGMT-methylation. Untested patients are less likely to receive standard treatments than tested patients. Generally, TMZ is used in most patients regardless of MGMT testing and status. MGMT-methylated patients are more likely to receive standard treatments and experience fewer side effects than MGMT-unmethylated patients.

Taxonomy of the genus Longipeditermes Holmgren (Termitidae, Nasutitermitinae) from the Greater Sundas, Southeast Asia

More than 200 colonies of the genus Longipeditermes were collected in our field surveys across the Sundaland region of Southeast Asia from 1998 to 2014. Two species, L. kistneri Akhtar &amp; Ahmad and L. logipes Holmgren, are recognized and redescribed with color photographs of the workers and major soldiers. We use variation in characters of soldier caste (head capsules, antennae, and pronotum) and worker caste (antennae and mandibles) to distinguish these two species. Longipeditermes kistneri seems to prefer high-altitude forests (above 1,000 m) and has so far been found exclusively in Java and Sumatra, while L. logipes seems to prefer lowland and swamp forests and is widespread in the Greater Sundas.

Analysis of the Drosophila melanogaster anti-ovarian response to honey bee queen mandibular pheromone

Queen mandibular pheromone (QMP) is a potent reproductive signal to which honey bee workers respond by suppressing their ovaries and adopting alloparental roles within the colony. This anti-ovarian effect of QMP on workers can, surprisingly, be induced in other insects, including fruit flies, in which females exposed to synthetic QMP develop smaller ovaries with fewer eggs. In this study, we use the Drosophila melanogaster model to identify the components of synthetic QMP required for the anti-ovarian effect. We found that virgin females respond strongly to 9-oxo-2-decenoic acid and 10-hydroxy-2-decenoic acid (10HDA), suggesting that the decenoic acid components of QMP are essential for the anti-ovarian response. Further, a nuclear factor of activated T-cells reporter system revealed neurones expressing the olfactory receptors Or-56a, Or-49b and Or-98a are activated by QMP in the antenna. In addition, we used olfactory receptor GAL4 drivers and a neuronal activator (a neuronal activating bacterial sodium channel) to test whether the candidate neurones are potential labelled lines for a decenoic acid response. We identified Or-49b as a potential candidate receiver of the 10HDA signal. Finally, the anti-ovarian response to synthetic QMP is not mediated by decreasing the titre of the reproductive hormones ecdysone and juvenile hormone.

A novel screen for genes associated with pheromone-induced sterility

For honey bee and other social insect colonies the ‘queen substance’ regulates colony reproduction rendering workers functionally sterile. The evolution of worker reproductive altruism is explained by inclusive fitness theory, but little is known of the genes involved or how they regulate the phenotypic expression of altruism. We previously showed that application of honeybee queen pheromone to virgin fruit flies suppresses fecundity. Here we exploit this finding to identify genes associated with the perception of an ovary-inhibiting social pheromone. Mutational and RNAi approaches in Drosophila reveal that the olfactory co-factor Orco together with receptors Or49b, Or56a and Or98a are potentially involved in the perception of queen pheromone and the suppression of fecundity. One of these, Or98a, is known to mediate female fly mating behaviour, and its predicted ligand is structurally similar to a methyl component of the queen pheromone. Our novel approach to finding genes associated with pheromone-induced sterility implies conserved reproductive regulation between social and pre-social orders, and further helps to identify candidate orthologues from the pheromone-responsive pathway that may regulate honeybee worker sterility.

A new species of open-air processional column termite, Hospitalitermes nigriantennalis sp. n. (Termitidae), from Borneo

A new species of open-air processional column termite is here described based on the soldier and worker castes from eight colonies in north Barito, central Kalimantan. Hospitalitermes nigriantennalis sp. n. is readily distinguished in the field from related Hospitalitermes spp. by the light brown to orangish coloration of the soldier head capsule that, further, is with vertex yellowish and nasus brownish. The soldier antenna and the maxillary and labial palps are blackish. By contrast, soldiers from other species of Hospitalitermes from this region have a uniformly black head capsule and antennae. Finally, Hospitalitermes nigriantennalis sp. n. has a minute indentation in the middle of the posterior part of head capsule, which further helps to differentiate this new species from other Hospitalitermes from the Indo-Malayan and Austro-Malayan regions.

Structure and function of gene regulatory networks associated with worker sterility in honeybees

A characteristic of eusocial bees is a reproductive division of labor in which one or a few queens monopolize reproduction, while her worker daughters take on reproductively altruistic roles within the colony. The evolution of worker reproductive altruism involves indirect selection for the coordinated expression of genes that regulate personal reproduction, but evidence for this type of selection remains elusive. In this study, we tested whether genes coexpressed under queen‐induced worker sterility show evidence of adaptive organization within a model brain transcriptional regulatory network (TRN). If so, this structured pattern would imply that indirect selection on nonreproductive workers has influenced the functional organization of genes within the network, specifically to regulate the expression of sterility. We found that literature‐curated sets of candidate genes for sterility, ranging in size from 18 to 267, show strong evidence of clustering within the three‐dimensional space of the TRN. This finding suggests that our candidate sets of genes for sterility form functional modules within the living bee brain's TRN. Moreover, these same gene sets colocate to a single, albeit large, region of the TRN's topology. This spatially organized and convergent pattern contrasts with a null expectation for functionally unrelated genes to be haphazardly distributed throughout the network. Our meta‐genomic analysis therefore provides first evidence for a truly “social transcriptome” that may regulate the conditional expression of honeybee worker sterility.

A genetic test of sexual size dimorphism in pre-emergent chinook salmon

Sex differences in early development may play an important role in the expression of sexual size dimorphism at the adult stage. To test whether sexual size dimorphism is present in pre-emergent chinook salmon (Oncorhynchus tshawytscha), alevins were reared at two temperatures (10 °C and 15 °C) and sexed using the OtY1 marker on the Y-chromosome. Linear mixed models were used to test for sex differences in alevin size within families while controlling for the random effects of sire and dam nested within sire. Males and females did not differ in weight at 10 °C but males were heavier than females at 15 °C. Sex accounted for 2% of the within-family variance in weight. In addition, at 15°C, the relationship between weight and sex was greater in families with larger eggs. Whereas male-biased sexual size dimorphism was present at the juvenile stage, female-biased sexual size dimorphism was present at sexual maturity. Males were also younger than females at sexual maturity. A head start on growth by males may underlie their earlier maturation at a smaller size, thus leading to female-biased SSD at the adult stage.

Genes underlying altruism

William D. Hamilton postulated the existence of 'genes underlying altruism', under the rubric of inclusive fitness theory, a half-century ago. Such genes are now poised for discovery. In this article, we develop a set of intuitive criteria for the recognition and analysis of genes for altruism and describe the first candidate genes affecting altruism from social insects and humans. We also provide evidence from a human population for genetically based trade-offs, underlain by oxytocin-system polymorphisms, between alleles for altruism and alleles for non-social cognition. Such trade-offs between self-oriented and altruistic behaviour may influence the evolution of phenotypic diversity across all social animals.

Cold tolerance of the eastern subterranean termite, Reticulitermes flavipes (Isoptera: Rhinotermitidae), in Ontario

We characterized the cold tolerance of natural populations of the Eastern subterranean termite (Reticulitermes flavipes (Kollar) [Isoptera, Rhinotermitidae]) in southwestern Ontario, Canada. We measured cold tolerance in workers from six colonies of termites established from Pelee Island in Lake Erie, and Point Pelee National Park. The mean critical thermal minimum, at which termites entered chill coma, ranged from 8.1 to 5.7°C. Mean supercooling points (SCP, the temperature at which individuals freeze) ranged from -4 to -4.6°C, and did not differ significantly between colonies, nor was SCP dependent on body size. Individuals survived brief exposure to low temperatures, as long as they did not freeze, but internal ice formation was always lethal, suggesting a freeze avoiding strategy. The LT50 (temperature at which 50% of individuals were killed by a 1 h exposure) was -5.1°C, but all individuals could survive -2°C for at least 72 h. Low temperature acclimation (12°C, 7 d) or hardening (4°C, 2 h) had no impact on the SCP, but acclimation did slightly increase the critical thermal minimum, making the termites less cold tolerant. We conclude that R. flavipes is not particularly cold tolerant, and likely relies on burrowing deep into the soil to avoid exposure to temperature to extremes.

Genetic evidence for multiple invasions of the eastern subterranean termite into Canada

Social insects are among the world's most successful species at invading new environments. Their characteristic division of labor can influence their capacity to colonize new habitats, often with negative ecological or economic impact. The social Hymenoptera (i.e., ants, bees, and wasps), are well studied in this regard, but much less is known about the invasive biology of termites (Isoptera). In this study we use province-wide sampling and a population genetic analysis to infer the minimum number of eastern subterranean termite [Reticulitermes flavipes (Kollar)] introductions into Ontario (Canada). Structure analysis of multilocus microsatellite genotypes grouped the 30 collection points into K = 3 genetic clusters, suggesting as many three independent introductions into southern Ontario. Levels of genetic diversity were higher in termites from the Pelee region than in termites from Toronto and other Ontario cities, suggesting that these Pelee termite populations are potentially older and native to Ontario. A single origin scenario, in which all populations stem from a single source, therefore is not supported by the genetic data. Instead, our analysis suggests multiple independent introductions of this highly social, subterranean termite into Ontario, where the species is now well established as a structural pest of urban habitats.

Identification of mycosis-related genes in the eastern subterranean termite by suppression subtractive hybridization

The Eastern subterranean termite Reticulitermes flavipes (Isoptera, Rhinotermitidae) is a cosmopolitan, structural pest that is the target of research into termite innate immunity. In this study, we use suppression subtractive hybridization to construct a normalized cDNA library of genes excessively expressed upon fungal infection. At 24 h postinfection with Metarhizium anisopliae, the library revealed 182 expressed sequence tag (EST) clones that potentially represent immune responsive genes. The nucleotide sequence from a majority (97%) of ESTs assembled into a small number (n = 13) of contiguous sequences, with the remainder (n = 6) representing singletons. Our screen therefore captured as many as 19 different mRNAs highly expressed in response to the fungal pathogen at this time. Primary sequencing of all loci revealed that approximately half (n = 10) contained open reading frames with significant similarity to known proteins. These clones represent nuclear and mitochondrial coding genes, as well as putative long noncoding RNA genes. Quantitative polymerase chain reaction analysis of coding genes on independently infected groups of worker termites confirms in each case that the transcripts identified from the library are up-regulated postfungal infection. The genes identified here are relevant to future studies on termite biocontrol and social insect immunity.

Taxonomic Notes on Nasutitermes and Bulbitermes (Termitidae, Nasutitermitinae) from the Sunda region of Southeast Asia based on morphological and molecular characters

The Sunda region of Southeastern Asia is rich in termite fauna, but termites from this region have been poorly described. In this study, we described eight species from two diverse genera from this region, and from the family Termitidae. We describe Bulbitermes 4 spp. and Nasutitermes 4 spp. from new field collections. Where possible we examine original holotype specimens, and describe the essential morphological characters for soldier and worker castes. We devise two new bifurcating keys to guide the field identification of each species. In addition, we develop a nucleotide sequence profile for the COI gene. From this molecular character matrix, we use Neighbour-Joining analysis to test the monophyly of each morphospecies and genus. We find that the morphological and molecular characters are highly concordant, whereby all taxa appear to represent distinct molecular clades. For termites, there is therefore agreement between the morphological taxonomic characters used to sort species from a bifurcating key and the molecular taxonomic characters used to sort species on a bifurcating tree. This joint analysis suggests that DNA barcoding holds considerable promise for termite taxonomy, especially for diverse clades like Bulbitermes and Nasutitermes for which a global morphological key would be intractable.

Hospitalitermes krishnai, a new nasute termite (Nasutitermitinae, Termitidae, Isoptera), from southern Sumatra, Indonesia

A new species of nasute termite, Hospitalitermes krishnaisp. n., is described from soldiers and workers discovered in Lampung Province, Sumatra. This species can be distinguished from other related Hospitalitermes species from Southeast Asia by the anterior part of head capsule that is much smaller than the posterior part, head capsule that is moderately constricted behind the antennal sockets, and relatively deep depression between the head and nasus and, finally, the short and robust nasus measuring less than half as long as head capsule. Moreover, in profile the nasus is slightly up-curved but slightly decurved at the apical tip. We name this new species after Professor Kumar Krishna in recognition of his life-long contributions to termite taxonomy, systematics and biology.

Genome-wide analysis of genes related to ovary activation in worker honey bees

A defining characteristic of eusocial animals is their division of labour into reproductive and nonreproductive specialists. Here, we used a microarray study to identify genes associated with functional sterility in the worker honey bee Apis mellifera. We contrasted gene expression in workers from a functionally sterile wild-type strain with that in a mutant (anarchist) strain selected for high rates of ovary activation. We identified a small set of genes from the brain (n = 7) and from the abdomen (n = 5) that are correlated in their expression with early stages of ovary activation. Sterile wild-type workers up-regulated two unknown genes and a homologue of Drosophila CG6004. By contrast, reproductive anarchist workers up-regulated genes for the yolk protein vitellogenin, venom peptides and a member of the AdoHycase superfamily, among others. The differentially expressed genes identified are likely to be involved in early differentiation into sterile and reproductive worker phenotypes and may therefore form part of the gene networks associated with the regulation of honey bee worker sterility. Our study may have lacked sufficient power to detect all but a minority of biologically relevant changes taking place; however, the differential expression of vitellogenin and a putative AdoHycase suggests that our screen has captured core reproductive genes and that ovary activation may involve an epigenetic mechanism.

Experimental manipulation of ovary activation and gene expression in honey bee (Apis mellifera) queens and workers: testing hypotheses of reproductive regulation

A fundamental issue in sociobiology is to understand how social insect females regulate their individual reproduction to maximize colony and personal fitness. Although the social cues mediating reproductive output within castes of the honey bees (Apis mellifera) are understood at a basic level, the underlying gene regulatory networks are not. In this study, we investigate the expression of 25 genes whose function suggests a role in the gene networks that regulate ovary activation--a functional determinant of reproductive skew. To this end, we used CO2 narcosis to manipulate ovary activation in queens and workers, and then quantified concomitant changes in gene expression using quantitative polymerase chain reaction. Of the 25 genes studied, ten were differentially expressed between treated and control groups in at least one caste. Two of these genes, a ribosomal protein and a tyramine receptor, were differentially expressed between treatments and controls in both castes. We use the expression pattern of all differentially expressed genes to test hypotheses for the caste-specific regulation of ovary activation in honey bees.

Molecular-genetic analyses of dispersal and breeding behaviour in the Australian termite Coptotermes lacteus: evidence for non-random mating in a swarm-dispersal mating system

We used microsatellite DNA markers to infer the dispersal and breeding behaviour of Coptotermes lacteus, a termite whose large mounds are a conspicuous feature of Australia’s central east coast. We genotyped a subsample of neuter offspring for each of 38 colonies sampled over two spatially separated populations, one in a natural forest and the other in an exotic radiata pine plantation. All colonies showed offspring genotype frequencies consistent with a single reproductive pair. This result confirms that stable monogamy is the normal breeding arrangement for this species and that multi-reproductive colonies are rare. The two study populations were significantly differentiated and the distance separating them (~150 km) is therefore an effective constraint on gene flow. The populations themselves, however, were not noticeably subdivided above the level of colony. This lack of within-population viscosity is unexpected for weakly dispersing species and suggests that local gamete dispersal is in fact quite effective in C. lacteus. Nonetheless, dispersing sexuals do not appear to mate randomly. Instead, all four microsatellite loci are deficient in heterozygotes, indicating that populations are substantially inbred, irrespective of habitat. Evidence from hierarchical F-statistics, spatial genetic autocorrelation and relatedness calculations suggests that deviations from Hardy–Weinberg equilibrium may result from either a preference for non-sibling relatives over totally unrelated mates, or from random mating with viscosity – though evidence for the latter hypothesis was not detected. These findings suggest that swarm-dispersal mating systems, usually considered to produce outbreeding and panmixia, can instead involve a notable degree of non-random mating.

Immune pathways and defence mechanisms in honey bees Apis mellifera

Social insects are able to mount both group-level and individual defences against pathogens. Here we focus on individual defences, by presenting a genome-wide analysis of immunity in a social insect, the honey bee Apis mellifera. We present honey bee models for each of four signalling pathways associated with immunity, identifying plausible orthologues for nearly all predicted pathway members. When compared to the sequenced Drosophila and Anopheles genomes, honey bees possess roughly one-third as many genes in 17 gene families implicated in insect immunity. We suggest that an implied reduction in immune flexibility in bees reflects either the strength of social barriers to disease, or a tendency for bees to be attacked by a limited set of highly coevolved pathogens.

Towards a molecular definition of worker sterility: differential gene expression and reproductive plasticity in honey bees

We show that differences in the reproductive development of honey bee workers are associated with locus-specific changes to abundance of messenger RNA. Using a cross-fostering field experiment to control for differences related to age and environment, we compared the gene expression profiles of functionally sterile workers (wild-type) and those from a mutant strain in which workers are reproductively active (anarchist). Among the set of three genes that are significantly differentially expressed are two major royal jelly proteins that are up-regulated in wild-type heads. This discovery is consistent with sterile workers synthesizing royal jelly as food for developing brood. Likewise, the relative underexpression of these two royal jellies in anarchist workers is consistent with these workers' characteristic avoidance of alloparental behaviour, in favour of selfish egg-laying. Overall, there is a trend for the most differentially expressed genes to be up-regulated in wild-type workers. This pattern suggests that functional sterility in honey bee workers may generally involve the expression of a suite of genes that effectively 'switch' ovaries off, and that selfish reproduction in honey bee workers, though rare, is the default developmental pathway that results when ovary activation is not suppressed.

Effects of carbon dioxide narcosis on ovary activation and gene expression in worker honeybees, Apis mellifera

In an effort to uncover genes associated with ovary activation in honey bee workers, the extent to which eight candidate genes co-varied in their expression with experimentally-induced changes in worker reproductive state was examined. Groups of caged, queenless workers narcotized with CO(2) on consecutive days early in adult life showed a significantly lower level of ovary activation than did groups of untreated workers. This same experimental treatment, by contrast, is known to accelerate ovary activation and induce egg laying in virgin honey bee queens--an observation that suggests that CO(2) narcosis has contrasting effects in queen versus worker ovary activation. Experimentally-induced changes to worker reproductive state were associated with changes in gene expression. Vitellogenin, an egg yolk precursor, and transferrin, an iron transporter, were two transcripts found to be significantly down-regulated as a function of the ovary-inhibiting treatment. CO(2) narcosis did not effect the expression of six other genes selected as putative markers for processes that may underlie ovary activation. The show that the expression of vitellogenin and transferrin is correlated with ovary activation in workers, and may therefore be part of the gene network involved in the regulatory control of functional sterility in honeybees.

Molecular sexing of prey remains permits a test of sex-biased predation in a wintering population of western sandpipers

Population sex ratios in monogamous birds are often male biased. One factor that can affect population sex ratios is sex-biased predation. However, most estimates of sex-biased predation in birds have focused on species with obvious sexual colour dimorphism or body size dimorphism. Data on sexually monomorphic birds are generally lacking. In the present study, we adopt a PCR-based sexing procedure to help test for sex-biased predation in a wintering population of western sandpipers (Calidris mauri), a shorebird that shows only subtle sexual size dimorphism. Specifically, by comparing the a priori determined sex ratio of live birds wintering at a site in western Mexico to the molecular estimate obtained from depredated birds at this same site, we were able to perform a population-specific test for sex bias in predator-induced mortality. The proportion of females estimated from living (ca. 25%) versus dead (ca. 24%) individuals was in fact not significantly different, indicating that the strong male bias in this population is not due to differential predation. However, molecular sexing of prey remains is a hitherto unexploited test of sex-biased predation in birds, and is potentially applicable to any species for which prey remains can be gathered. We discuss our results in the context of alternate ecological hypotheses for population sex biases.

Evaluating alternative hypotheses for the origin of eusociality in corbiculate bees

We use a likelihood-based statistical test to evaluate the extent to which the available molecular data sets can be used to falsify alternative phylogenetic hypotheses describing the inter-relationship among corbiculate bee tribes. Based on the results of this test, we explore three alternative models of behavioural character state evolution and evaluate the support each model has for single-origin versus dual-origin hypotheses for 'highly' eusocial behaviour. We show that only one of four data sets could statistically reject any of the 15 possible outgroup-rooted phylogenetic hypotheses. However, a cytochrome b data set rejected all but three alternative topologies. Using this information, a simple model of behavioural character state evolution, in which transitions between solitary/communal, 'primitively' eusocial, and 'highly' eusocial are unconstrained, supports single-origin hypotheses for 'highly' eusocial behaviour, in spite of phylogenetic uncertainty. By contrast, an ordered model, in which 'highly' eusocial is constrained to be an evolutionarily terminal state, supports a dual-origins hypothesis. Our results show that the molecular phylogenetic evidence favouring a dual-origins hypothesis for 'highly' eusocial behaviour is, at present, conditional on information from one gene (cyt b) and on specific, though likely realistic, assumptions regarding the nature of eusocial evolution.

On the origin of termite workers: weighing up the phylogenetic evidence

Resolving the phylogenetic history of a 'true' worker caste in termites is essential to our understanding of termite eusocial evolution. Whether this caste is ancient and monophyletic or derived and polyphyletic will have a tremendous impact on our interpretation of termite eusocial history and remains an outstanding question in termite biology. Recent work has begun to re-examine this question in light of new phylogenetic information, but new questions have now arisen about how best to model character state changes in termite caste systems. In the present paper, we compare the models of Grandcolas and D'Haese [J. Evol. Biol. 15 (2002) 885] and Thompson et al. [J. Evol Biol. 13 (2000) 8691 and attempt to make explicit how these proposals differ with respect to the number of, and homology between, character states. We highlight the support each model has for the two principal, but competing, evolutionary hypotheses outlined above.

Isolation and characterization of a termite transferrin gene up-regulated on infection

PCR-based subtractive hybridization was used to isolate genes preferentially expressed in a termite (Mastotermes darwiniensis) following exposure to an entomopathogenic fungus. The subtraction procedure yielded a cDNA clone encoding a putative transferrin that, when sequenced to its ends, is the largest (728 amino acids) for any insect transferrin characterized to date. Cysteines and residues comprising putative iron-binding sites are conserved in both N- and C-terminal lobes, suggesting structural and functional similarity to diferric vertebrate transferrins. A quantitative PCR assay confirmed a significant increase in transferrin expression following infection, suggesting its up-regulation is part of the innate immune response. However, codon-based tests for selection among known insect transferrins revealed only a small proportion of codon-sites positively selected. Thus, unlike certain vertebrate transferrin lineages, no widespread evidence for pathogen-mediated positive selection was detected at this locus.

Elevated extracellular [K+] inhibits death-receptor- and chemical-mediated apoptosis prior to caspase activation and cytochrome c release

Efflux of intracellular K(+) and cell shrinkage are features of apoptosis in many experimental systems, and a regulatory role has been proposed for cytoplasmic [K(+)] in initiating apoptosis. We have investigated this in both death-receptor-mediated and chemical-induced apoptosis. Using Jurkat T cells pre-loaded with the K(+) ion surrogate (86)Rb(+), we have demonstrated an efflux of intracellular K(+) during apoptosis that was concomitant with, but did not precede, other apoptotic changes, including phosphatidylserine externalization, mitochondrial depolarization and cell shrinkage. To further clarify the role of K(+) ions in apoptosis, cytoprotection by elevated extracellular [K(+)] was studied. Induction of apoptosis by diverse death-receptor and chemical stimuli in two cell lines was inhibited prior to phosphatidylserine externalization, mitochondrial depolarization, cytochrome c release and caspase activation. Using a cell-free system, we have demonstrated a novel mechanism by which increasing [K(+)] inhibited caspase activation. In control dATP-activated lysates, Apaf-1 oligomerized to a biologically active caspase processing approximately 700 kDa complex and an inactive approximately 1.4 MDa complex. Increasing [K(+)] inhibited caspase activation by preventing formation of the approximately 700 kDa complex, but not of the inactive complex. Thus intracellular and extracellular [K(+)] markedly affect caspase activation and the initiation of apoptosis induced by both death-receptor ligation and chemical stress.

Phylogenetic analysis and trait evolution in Australian lineages of drywood termites (Isoptera, Kalotermitidae)

A phylogenetic analysis of Australian drywood termites (Isoptera, Kalotermitidae) based on partial sequence from the cytochrome oxidase II (COII) and cytochrome b genes is presented. In addition to providing new information on the evolutionary relationships among 25 species from seven genera, we evaluate the relative likelihoods of alternative topological hypotheses, including those derived from morphology-based classifications. We also test the applicability of a molecular clock for estimating the age of the Kalotermitidae and infer the evolution of species-specific variation for habitat type and soldier caste phragmosis by mapping this information onto the independently derived phylogeny. Maximum-likelihood analysis of both nucleotide and protein sequences from a multigene data set jointly support a single topology, which is shown to be the best estimate of the true phylogeny among the alternatives tested. Our results support the monophyly of all genera but question the discrimination between Procryptotermes and Cryptotermes. A basal dichotomy among generic groups suggests two principle lines of divergence within the family. Intergeneric relationships show mixed congruence to previous proposals, resulting in one morphology-based classification being rejected. A molecular clock hypothesis is not supported due to significant among-lineage rate heterogeneity in the COII gene. Patterns revealed through trait mapping suggest that the most recently diverged taxa tend to occupy the driest habitats and that these same taxa reflect a defensive transition away from large mandibulate soldiers toward small phragmotic soldiers. The association between habitat and defensibility supports the hypothesis that these two characters have been tightly linked throughout the social diversification of termites.

Angulated screw placement in the lateral condylar buttress plate for supracondylar femoral fractures

Certain supracondylar femoral fractures are not amenable to internal fixation with fixed angle devices. In these instances, the condylar buttress plate is the recommended alternative; however, this is a less rigid device. Because of the decreased rigidity and strength of this device, there is a tendency toward varus angulation and malunion. In six fresh-frozen human knee specimens, segmental osteotomies were created to mimic supracondylar femoral fractures. The medial cortex was completely removed to make the fracture unstable to varus deformity. The fracture was fixed with a lateral condylar buttress plate using 4.5 mm screws. Each specimen was tested once with all the screws installed perpendicular to the plate, and again with the middle screw, just proximal to the fracture, angled 45 degrees diagonally across the fracture into the subchondral bone of the medial femoral condyle. For the construct with all screws placed perpendicular to the buttress plate, the initial stiffness was 410 N/mm, and after 1000 cycles it was 230 N/mm. With a screw placed diagonally across the fracture site, stiffness increased to 833 N/mm on the first cycle, and 796 N/mm after 1000 cycles. In all specimens with the screws placed perpendicular to the plate, the distal fragment had a permanent varus deformity after 1000 cycles, under no load, of 0.91 mm. For the diagonal screw condition, the average magnitude for all six specimens was 0.42 mm. This simple means of screw angulation in the plate strengthened the overall construct to resist the tendency toward varus deformity. The attractive features include the ease of application, and the use of an existing construct.