The role of endosymbionts in the evolution of haploid-male genetic systems in scale insects (Coccoidea)

There is an extraordinary diversity in genetic systems across species, but this variation remains poorly understood. In part, this is because the mechanisms responsible for transitions between systems are often unknown. A recent hypothesis has suggested that conflict between hosts and endosymbiotic microorganisms over transmission could drive the transition from diplodiploidy to systems with male haploidy (haplodiploidy, including arrhenotoky and paternal genome elimination [PGE]). Here, we present the first formal test of this idea with a comparative analysis across scale insects (Hemiptera: Coccoidea). Scale insects are renowned for their large variation in genetic systems, and multiple transitions between diplodiploidy and haplodiploidy have taken place within this group. Additionally, most species rely on endosymbiotic microorganisms to provide them with essential nutrients lacking in their diet. We show that species harboring endosymbionts are indeed more likely to have a genetic system with male haploidy, which supports the hypothesis that endosymbionts might have played a role in the transition to haplodiploidy. We also extend our analysis to consider the relationship between endosymbiont presence and transitions to parthenogenesis. Although in scale insects there is no such overall association, species harboring eukaryote endosymbionts were more likely to be parthenogenetic than those with bacterial symbionts. These results support the idea that intergenomic conflict can drive the evolution of novel genetic systems and affect host reproduction.

The evolution of hermaphroditism by an infectious male-derived cell lineage: an inclusive-fitness analysis

There has been much recent interest in the role for genetic conflicts to drive the evolution of genetic systems. Here we consider the evolution of hermaphroditism in the scale insect tribe Iceryini and the suggestion that this has been driven by conflict between a female and an infectious male tissue derived from her father. We perform an inclusive-fitness analysis to show that, owing to genetic relatedness between father and daughter, there is scope for collaboration as well as conflict over the establishment of the infectious tissue. We also consider the evolutionary interests of a maternally inherited bacterial symbiont that has been implicated in mediating the tissue's establishment. More generally, our analysis reveals that genetic conflicts can drive the evolution of hermaphroditism.

A team approach: implementing a model of care for preventing osteoporosis related fractures

The implementation of a multidisciplinary team-based model of care has led to significant increases in identification of patients with osteoporosis who are at risk of refracture, together with improved treatment uptake and ongoing management.

INTRODUCTION

Osteoporosis-related fractures and consequent hospital admissions are largely preventable; however, little attention has been paid to how to achieve this, in particular, through improved models of care. Presentation to emergency departments (ED) with minimal trauma fracture (MTF) provides opportunity for patients at risk to be identified, referred and managed through a systematic process ensuring prompt intervention and continuing follow-up. This study is aimed to design and implement a care model for people over 50 years of age, presenting to ED with an MTF.

METHOD

Established a multidisciplinary fracture prevention team to identify and capture at-risk patients for referral and management. Clinical data revealed the extent of lost opportunities. An electronic flagging system and data acquisition tool were developed and piloted. Established a referral pathway to detect, manage and follow-up patients, coordinated by a fracture prevention nurse.

RESULTS

Increased awareness of osteoporosis as a cause of MTF, better identification of at-risk patients across departments and services and development of a flagging and referral protocol has resulted in 100% capture of at-risk patients presented to ED. As a result there has been a significant increase in patients attending the fracture prevention clinic (FPC) (p < 0.001) from 11% in 2007 to 29% in 2008 and a significantly reduced time between fracture and when patients are seen in the FPC (p < 0.001).

CONCLUSION

A multipronged systematic team approach to identifying and capturing patients with a high risk of refracture and a dedicated nurse coordinator role has created efficiencies in the detection and management of osteoporosis.

Transoral surgery: an anatomic study

The transoral approaches have become commonplace in modern neurosurgical practice for treatment of ventral midline lesions of the clivus and upper cervical spine. Although the standard technique of transoral surgery is conceptually simple, anatomic relationships are not so readily appreciated. The present study was undertaken in an effort to define more clearly the midline anatomic relationships as they pertain to the standard transoral and transpalatine operations. The anatomic relationships involved in planning microsurgical transoral approaches were examined in 15 human cadavers. Landmarks approximating the midline of the skull base and the upper cervical spinal canal were defined to assist the surgeon's orientation. Measurements were made in axial, sagital, and parasagittal planes to various neurovascular structures in the posterior cranial fossa and upper cervical spinal canal. The study revealed that, for the standard transoral and transoral-transpalatine dissections, the carotid arteries, abducens nerves, interior petrosal sinuses, hypoglossal nerves, and vertebral arteries would be a greatest risk being 0.76, 1.06, 1.51, 1.34, and 1.52 cm from the midline at specified locations. The measurements and the computed tomography images provide a useful reference for the surgeon.

Genomic conflict in scale insects: the causes and consequences of bizarre genetic systems

It is now clear that mechanisms of sex determination are extraordinarily labile, with considerable variation across all taxonomic levels. This variation is often expressed through differences in the genetic system (XX-XY, XX-XO, haplodiploidy, and so on). Why there is so much variation in such a seemingly fundamental process has attracted much attention, with recent ideas concentrating on the possible role of genomic conflicts of interest. Here we consider the role of inter- and intra-genomic conflicts in one large insect taxon: the scale insects. Scale insects exhibit a dizzying array of genetic systems, and their biology promotes conflicts of interest over transmission and sex ratio between male- and female-expressed genes, parental- and offspring-expressed genes (both examples of intra-genomic conflict) and between scale insects and their endosymbionts (inter-genomic conflict). We first review the wide range of genetic systems found in scale insects and the possible evolutionary transitions between them. We then outline the theoretical opportunities for genomic conflicts in this group and how these might influence sex determination and sex ratio. We then consider the evidence for these conflicts in the evolution of sex determination in scale insects. Importantly, the evolution of novel genetic systems in scale insects has itself helped create new conflicts of interest, for instance over sex ratio. As a result, a major obstacle to our understanding of the role of conflict in the evolution of sex-determination and genetic systems will be the difficulty in identifying the direction of causal relationships. We conclude by outlining possible experimental and comparative approaches to test more effectively how important genomic conflicts have been.

The evolution and suppression of male suicide under paternal genome elimination

Different genetic systems can be both the cause and the consequence of genetic conflict over the transmission of genes, obscuring their evolutionary origin. For instance, with paternal genome elimination (PGE), found in some insects and mites, both sexes develop from fertilized eggs, but in males the paternally derived chromosomes are either lost (embryonic PGE) or deactivated (germline PGE) during embryogenesis and not transmitted to the next generation. Evolution of germline PGE requires two transitions: (1) elimination of the paternal genome during spermatogenesis; (2) deactivation of the paternal genome early in development. Hypotheses for the evolution of PGE have mainly focused on the first transition. However, maternal genes seem to be responsible for the deactivation and here we investigate if maternal suppression could have evolved in response to paternally expressed male suicide genes. We show that sibling competition can cause such genes to spread quickly and that inbreeding is necessary to prevent fixation of male suicide, and subsequent population extinction. Once male-suicide has evolved, maternally expressed suppressor genes can invade in the population. Our results highlight the rich opportunity for genetic conflict in asymmetric genetic systems and the counterintuitive phenotypes that can evolve as a result.

Sexual conflict, sex allocation and the genetic system

Decisions over what sex ratio to produce can have far-reaching evolutionary consequences, for both offspring and parents. However, the extent to which males and females come into evolutionary conflict over aspects of sex allocation depends on the genetic system: when genes are passed to the next generation unequally by the two sexes (as in haplodiploidy, for example), this biased transmission can facilitate a range of conflicts not seen in diploids. However, much less attention has been paid to these forms of sexual conflict, not least because it has not always been clear how the conflicts could be realized. Here we consider how biased gene transmission, as expressed in different genetic systems, enhances the opportunity for sex ratio conflict and give empirical examples that confirm that males and females have the opportunity to influence sex ratios.

Short communication: the number of HIV major NRTI mutations correlates directly with other antiretroviral-associated mutations and indirectly with replicative capacity and reduced drug susceptibility

While it is known that selection for specific HIV-1 drug resistance-associated mutations (DRM) occurs following ART failure, the patterns of resistance mutations, reduced susceptibility (RS), and replicative capacity (RC) that appear as the number of major NRTI mutations increases have been less well-studied. These changes were examined as a function of the number of major NRTI mutations using patient-derived HIV samples submitted for resistance testing between 2003-2005 (n = 35,222) that were grouped by number of NRTI-DRMs present. In the absence of NRTI-DRMs, few (3.4%) samples had RS to one or more NRTI, 33.6% to one or more NNRTI, and 12.6% to one or more PI. With one NRTI-DRM, 94% had RS to one or more NRTI, 50% to one or more NNRTI, and 33% to one or more PI. Increases in NRTI-DRMs were accompanied by increased prevalence of NNRTI and PI DRMs and RS. With one NRTI-DRM, the mean number of NRTIs with RS was 1.7, while when five NRTI-DRMs were present, RS to > or =5 NRTIs was observed. PI-DRM and RS increased at a slower rate than NNRTI-DRM and RS. RC declined from a mean of 97.8% for samples without NRTI-DRMs to 68.9% with one NRTI-DRM, possibly due to reduced fitness conferred by K65R or M184I/V, to an RC of 43.9% for samples with seven to eight NRTI-DRMs. The relatively high percent of samples with NNRTI-DRM but without NRTI-DRMs may result from selection following virologic failure, and/or transmission of virus uniquely resistant to NNRTI.

Effects of treating postnatal depression on mother-infant interaction and child development: systematic review

BACKGROUND

Postnatal depression has detrimental effects on the child's cognitive and emotional development.

AIMS

To assess the benefits of treating postnatal depression for mother-infant interaction and child development.

METHOD

A systematic search was made of 12 electronic bibliographic databases for randomised controlled trials and controlled clinical trials on treatment of mothers with postnatal depression, where outcomes were assessed in children; findings were assessed.

RESULTS

Only eight trials met the inclusion criteria. Of those included, interventions varied widely but all involved therapies directed at the mother-infant relationship. One study with intensive and prolonged therapy showed cognitive improvement, whereas two others with briefer interventions improved maternal-infant relationships but did not affect the child's cognitive or behavioural development. All five studies assessing only mother-infant relationships showed improvements.

CONCLUSIONS

Cognitive development in children of depressed mothers, along with better mother-infant relationships, might be improved with sustained interventions. Trials assessing treatments for postnatal depression would benefit from looking more closely at benefits for children as well as mothers, using validated objective measures.

Molecular basis of antagonism between K70E and K65R tenofovir-associated mutations in HIV-1 reverse transcriptase

The K70E mutation in HIV-1 reverse transcriptase was observed in 10% of virologic non-responders of the abacavir/lamivudine/tenofovir arm of ESS30009, alone, or in mixtures with K65R by population sequencing. Clonal analysis of six ESS30009 K70E isolates failed to identify double mutants carrying K65R+K70E. Site-directed K70E mutants had a replication capacity of 97+/-29%, but only 2.4+/-0.9% for K65R+K70E and 0.01% for K65R+K70E+M184V mutants. K65R+K70E phenotypic fold changes for abacavir, lamivudine and tenofovir were comparable to reported values for K65R alone. In molecular dynamic simulations, the epsilon-amino group of K65 was positioned 2.7+/-0.1A from the gamma-phosphate of the dTTP ligand and stabilized the triphosphate. In the R65 mutant, this distance increased to 4.2+/-0.4A and the interaction energy with the ligand was less favorable, but the K70 epsilon-amino group was repositioned closer to the gamma-phosphate and had a more favorable interaction energy. In the double mutant, E70 could not stabilize the gamma-phosphate, resulting in a more severe defect. The net effect of the atomic-level changes in the double mutant may be to destabilize the pyrophosphate leaving group of the ligand, more severely affecting the catalytic rate of the polymerization reaction than the R65 single mutation.

Bilirubin as an antioxidant in micelles and lipid bilayers: its contribution to the total antioxidant capacity of human blood plasma

The antioxidant capacities, antioxidant activities, k(inh), and stoichiometric factors, n, of water-soluble derivatives of bilirubin (BR), BR-human serum albumin (BR-HSA), and BR-ditaurate disodium conjugate (BRC) were determined in aqueous/lipid dispersions of sodium dodecyl sulfate (SDS) micelles/methyl linoleate and in bilayers of dilinoleoylphosphatidylcholine (DLPC) during initiation by water-soluble azo-bis-amidinopropane dihydrochloride (ABAP). The inhibition rate constants for BRC and BR-HSA were similar in micelles (k(inh) approximately 1.3 x 10(4) M(-1) s(-1)), where n approximately 2, whereas the k(inh) for BR-HSA dropped by (1/2) in bilayers. The dimethyl ester of bilirubin (BRDE) gave a k(inh) only one-tenth that of the vitamin E analog, pentamethylhydroxychroman (PMHC) in SDS micelles/methyl linoleate when initiated by lipid-soluble azo-bis-2,4-dimethylvaleronitrile (DMVN). Biliverdin hydrochloride (BVHCl) was NOT an effective peroxyl radical-trapping agent in the micellar phase during initiation by ABAP or DMVN containing methyl linoleate but it inhibited oxygen uptake in the aqueous phase. Both BRC and BR-HSA extended the total radical antioxidant parameter (TRAP) of human blood plasma and their contribution to TRAP was in the range of 5-10% of the natural TRAP of blood plasma, depending on the BR content determined in the blood plasma.

Promoting early detection in leprosy--a literature review to identify proven and potential interventions addressing patient-related delay

OBJECTIVES

The objective of the literature review was to identify proven and potential interventions to promote early diagnosis and start of treatment in leprosy, specifically, forms of intervention addressing needs at the local or primary level.

DESIGN

Using a structured search procedure, we identified recent leprosy-related publications describing proven interventions. To identify potential interventions the search was extended to publications assessing knowledge and attitudes towards leprosy and extended again to identify publications relating to patient-related delay in the context of other infectious diseases.

RESULTS

The review identified just 19 publications reporting leprosy-related interventions that included a form of evaluation of which only 10 directly addressed patient-related delay. These included health education interventions focussed on people directly affected by leprosy, their family members and other key individuals or groups within the local community. We identified no reports of interventions focussed specifically on the needs of women.

CONCLUSIONS

Our conclusion is that the evidence base available to inform the choice of small-scale interventions to promote early detection at the primary level is extremely limited. There is an urgent need to develop and extend the range of proven interventions, specifically those that address the needs of women, those that explore and develop the health promotion potential of people previously affected by,leprosy and those that exploit the potential of individuals with leadership roles within the community. This will require careful attention to planning, implementation, evaluation and reporting of interventions.

The relation between socioeconomic and demographic factors and tumour stage in women diagnosed with breast cancer in Denmark, 1983-1999

The authors investigated the association between socioeconomic position and stage of breast cancer at the time of diagnosis in a nationwide Danish study. All 28 765 women with a primary invasive breast cancer diagnosed between 1983 and 1999 were identified in a nationwide clinical database and information on socioeconomic variables was obtained from Statistics Denmark. The risk of being diagnosed with a high-risk breast cancer, that is size >20 mm, lymph-node positive, ductal histology/high histologic grade and hormone receptor negative, was analysed by multivariate logistic regression. The adjusted odds ratio (OR) for high-risk breast cancer was reduced with longer education with a 12% reduced risk (95% confidence interval (CI), 0.80,0.96) in women with higher education and increased with reduced disposable income (low income group: OR, 1.22; 95% CI, 1.10,1.34). There was an urban–rural gradient, with higher risk among rural women (OR 1.10; 95 % CI, 1.02, 1.18) and lower risk among women in the capital suburbs (OR, 0.85; 95% CI, 0.78, 0.93) and capital area (OR, 0.93; 95% CI, 0.84–1.02). These factors were significant only for postmenopausal women, although similar patterns were observed among the premenopausal women, suggesting a subgroup of aggressive premenopausal breast cancers less influenced by socioeconomic factors.