Introduction. Sexual conflict: a new paradigm?
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Animals↗
Biomedical subjects
T Chapman
Publications and source records attributed to T Chapman.
No evidence that experimental manipulation of sexual conflict drives premating reproductive isolation in Drosophila melanogaster.
Theoretical models predict that sexual conflict can drive reproductive isolation by decreasing the probability of matings between individuals from allopatric populations. A recent study in dung flies supported this prediction. To test the generality of this finding we used replicate lines of Drosophila melanogaster that had been selected under high, medium and low levels of sexual conflict, in which the females had evolved differences in their level of resistance to male-induced harm. We compared the proportion of virgin pairs that mated by set time points, for flies from the same replicate within each sexual conflict level vs. flies from different replicates within each sexual conflict level. The results did not support the prediction that, in D. melanogaster, sexual conflict drives population divergence via changes in female willingness to mate. The results were unlikely to be explained by differential inbreeding or by a lack of response to sexual conflict.
Animals↗
Exploring the views of second-year Foundation Programme doctors and their educational supervisors during a deanery-wide pilot Foundation Programme.
AIM: To explore the views of second-year Foundation Programme doctors (F2s) and their educational supervisors taking part in a deanery-wide pilot Foundation Programme, in order to gain an understanding of their perceptions of the available learning experiences, support and supervision. METHODS: 20 semi-structured interviews were undertaken with randomly selected F2 doctors and educational supervisors participating in the deanery-wide pilot Foundation Programme. RESULTS: F2 trainees received appropriate and sufficient support and supervision from a variety of sources during their placements; however, it was believed that additional training of educational supervisors was required. Trainees reported some problems with the perception of the role of an F2; further understanding of the purpose and role of the F2 programme is required at trust level. The portfolio was viewed positively as a record and a learning tool, but was thought to be too bureaucratic. Trainees believed that it was more beneficial to their careers to take part in a foundation programme as opposed to a traditional senior house officer post, but both trainees and educational supervisors expressed some concerns about the generic nature of some skills F2s were expected to acquire. CONCLUSIONS: This evaluation has highlighted successful aspects of the Foundation Programme, particularly with regard to the level of support and range of experiences provided for trainees. Issues of concern to both trainees and educational supervisors have been identified, which require additional understanding.
Attitude of Health Personnel↗
No detectable genetic correlation between male and female mating frequency in the stalk-eyed fly Cyrtodiopsis dalmanni.
There is much interest in explaining why female insects mate multiply. Females of the stalk-eyed fly Cyrtodiopsis dalmanni can mate several times each day in a lifetime which may span several months. There are many adaptive explanations, but one hypothesis that has received little rigorous empirical attention is that female multiple mating has evolved for non-adaptive reasons as a correlated response to selection for high male mating frequency rather than because of direct or indirect benefits accruing to females. We tested this hypothesis in stalk-eyed flies by measuring the mating frequency of females from lines that exhibited a direct response in males to artificial selection for increased ('high') and decreased ('low') male mating frequency. We found that the mating frequency of high-line females did not differ from that of low-line females. Hence, there was no support for a genetic correlation between male and female mating frequency in this species. Our study suggests that the genes which influence remating may not be the same in the sexes, and that females remate frequently in this species to gain as yet unidentified benefits.
Analysis of Variance↗
Direct and correlated responses to artificial selection on male mating frequency in the stalk-eyed fly Cyrtodiopsis dalmanni.
Traditionally it was thought that fitness-related traits such as male mating frequency, with a history of strong directional selection, should have little additive genetic variance and thus respond asymmetrically to bidirectional artificial selection. However, recent findings and theory suggest that a balance between selection for increased male mating frequency and opposing selection pressures on physiologically linked traits will cause male mating frequency to have high additive genetic variation and hence respond symmetrically to selection. We tested these hypotheses in the stalk-eyed fly, Cyrtodiopsis dalmanni, in which males hold harems comprising many females and so have the opportunity to mate at extremely high frequencies. We subjected male stalk-eyed flies to artificial selection for increased ('high') and decreased ('low') mating frequency in the presence of ecologically realistic, high numbers of females. High line males mated significantly more often than control or low line males. The direct response to selection was approximately symmetric in the high and low lines, revealing high additive genetic variation for, and no significant genetic constraints on, increased male mating frequency in C. dalmanni. In order to investigate trade-offs that might constrain male mating frequency under natural conditions we examined correlated responses to artificial selection. We measured accessory gland length, testis length and eyespan after 7 and 14 generations of selection. High line males had significantly larger accessory glands than low line males. No consistent correlated responses to selection were found in testis length or eyespan. Our results suggest that costs associated with the production and maintenance of large accessory glands, although yet to be identified, are likely to be a major constraint on mating frequency in natural populations of C. dalmanni.
Animals↗
Selected culturable enteric bacterial populations are modified by diet acidification and the growth promotant Tylosin.
AIMS: To determine the effect of diet acidification and an in-feed antibiotic growth promotant (Tylosin, Ty) on selected culturable bacterial populations in the gastrointestinal tract (GIT) of mice. METHODS AND RESULTS: Female C57Bl mice were given a standard diet supplemented with Acid Pak (AP) or Ty in the drinking water. After 21 days, lumen and adherent populations of Enterobacteriaceae, enterococci/streptococci, and lactic acid bacteria (LAB) from the ileum, caecum, colon and faeces were enumerated. General intestinal health was assessed by the frequency of haemolytic bacteria in the different intestinal compartments. Contrary to expectations, AP and Ty significantly increased haemolytic bacteria in the lumen of the caecum and colon (P<0.05). The small but significant growth-enhancing effect of Ty (P<0.05) was associated with decreases in enterococci/streptococci and surprisingly, LAB, as well as increases in coliforms. AP, which failed to improve growth rates, reduced coliforms, had limited effects on enterococci/streptococci, and specifically failed to promote the growth of LAB populations in all intestinal compartments. Ty supplementation was also associated with a significant increase in macrolide-resistant enterococci throughout the GIT. CONCLUSIONS: Dietary acidification is less effective than Ty in modulating the population dynamics of selected culturable populations of enteric bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: The mouse can provide a useful experimental model to examine the effects of new dietary supplements, formulations or regimes on changes in microbial population dynamics, including monitoring for antibiotic resistance.
Animals↗
Rapid identification of virulence genes in enterotoxigenic Escherichia coli isolates associated with diarrhoea in Queensland piggeries.
OBJECTIVE: To identify virulence genes in enterotoxigenic E coli (ETEC) isolates associated with diarrhoea in neonatal, 1 to 3 week-old and weaned pigs in southeast Queensland. DESIGN: Multiplex PCR and serotyping were applied to E coli isolates obtained over a 5-year period (1998-2002) from cases diagnosed at Toowoomba Veterinary Laboratory. PROCEDURE: A total of 126 isolates from 25 different Queensland piggeries were tested for haemolytic activity on 5% sheep blood agar and by multiplex PCR for the presence of five commonly recognised fimbrial (F4, F5, F6, F41 and F18) and three enterotoxin genes (STa, STb, LT). A subset of 62 representative isolates were serotyped by slide agglutination. For comparative purposes, multiplex PCR was also performed on the DNA of 31 ETEC isolates from 9 serotypes originating from piggeries in southern New South Wales. RESULTS: A total of 113 (89.7%) of the isolates from Queensland possessed ETEC virulence genes, including 14 of 15 isolates from neonatal pigs (93.3%), 18 of 23 isolates from 1 to 3 week old pigs (78.3%) and 81 of 88 isolates from weaned pigs (92.1%). F4:STa:STb:LT (serotype O149) was the most prevalent pathotype in neonatal and 1-3 week old pigs and F4:STa:STb:LT (serotype O149) and F18:STa:STb:LT (serotype O141) were most prevalent in weaned pigs. In comparison, isolates obtained from neonatal pigs from New South Wales belonged to a more diverse range of pathotypes and serotypes. CONCLUSION: Multiplex PCR was a rapid and specific method for detecting the presence of ETEC virulence genes in porcine E coli isolates. For isolates obtained from cases of suspected colibacillosis in Queensland, growth of a heavy pure culture of haemolytic E coli was a sensitive prognostic indicator of the presence of ETEC virulence genes in the isolate. ETEC pathotypes and serotypes remained stable in Queensland piggeries over the five-year study period and appear to have changed little over the last three decades.
Animals↗
Efficacy and tolerability of borage oil in adults and children with atopic eczema: randomised, double blind, placebo controlled, parallel group trial.
OBJECTIVE: To study the efficacy and tolerability of borage oil, which contains a high concentration of gamma linolenic acid, in children and adults with atopic eczema. DESIGN: Single centre, randomised, double blind, placebo controlled, parallel group trial. SETTING: Acute district general hospital in Nuneaton, England. PARTICIPANTS: 151 patients, of whom 11 failed to return for assessment, leaving an evaluable population of 140 (including 69 children). INTERVENTION: Adults received four capsules of borage oil twice daily (920 mg gamma linolenic acid), and children received two capsules twice daily, for 12 weeks. MAIN OUTCOME MEASURES: Change in total sign score at 12 weeks measured with the six area, six sign, atopic dermatitis (SASSAD) score (primary endpoint); symptom scores, assessed on visual analogue scales; topical corticosteroid requirement, assessed on a five point scale; global assessment of response by participants; adverse events and tolerability. RESULTS: The mean SASSAD score fell from 30 to 27 in the borage oil group and from 28 to 23 in the placebo group. The difference between the mean improvements in the two groups was 1.4 (95% confidence interval -2.2 to 5.0) points in favour of placebo (P = 0.45). No significant differences occurred between treatment groups in the other assessments. Subset analysis of adults and children did not indicate any difference in response. The treatments were well tolerated. CONCLUSION: Gamma linolenic acid is not beneficial in atopic dermatitis.
Adult↗
Influence of female reproductive anatomy on the outcome of sperm competition in Drosophila melanogaster.
Females as well as males can influence the outcome of sperm competition, and may do so through the anatomy of their reproductive tracts. Female Drosophila melanogaster store sperm in two morphologically distinct organs: a single seminal receptacle and, normally, two spermathecae. These organs have different temporal roles in sperm storage. To examine the association between sperm storage organ morphology and sperm competition, we used a mutant type of female with three spermathecae. Although the common measure of sperm competition, P(2), did not differ between females with two and three spermathecae, the pattern of sperm use over time indicated that female morphology did affect male reproductive success. The rate of offspring production by females with three spermathecae rose and fell more rapidly than by females with two spermathecae. If females remate or die before using up second male sperm, then second male reproductive success will be higher when they mate with females with three spermathecae. The results indicate that temporal patterns of sperm use as well as P(2) should be taken into account when measuring the outcome of sperm competition.
Animals↗
Microsatellite analysis reveals remating by wild Mediterranean fruit fly females, Ceratitis capitata.
Accurate estimates of remating in wild female insects are required for an understanding of the causes of variation in remating between individuals, populations and species. Such estimates are also of profound importance for major economic fruit pests such as the Mediterranean fruit fly (Ceratitis capitata). A major method for the suppression of this pest is the sterile insect technique (SIT), which relies on matings between mass-reared, sterilized males and wild females. Remating by wild females will thus impact negatively on the success of SIT. We used microsatellite markers to determine the level of remating in wild (field-collected) Mediterranean fruit fly females from the Greek Island of Chios. We compared the four locus microsatellite genotypes of these females and their offspring. Our data showed 7.1% of wild females remated. Skewed paternity among progeny arrays provided further evidence for double matings. Our lowest estimate of remating was 3.8% and the highest was 21%.
Animals↗
Retinopathy screening in children and adolescents with diabetes.
Diabetic retinopathy is a complication of diabetes that affects the blood vessels of the retina. The majority of patients with diabetic retinopathy exhibit background retinopathy. In approximately 10% of patients, background retinopathy will progress to sight-threatening retinopathy. The aims of our study were to measure the prevalence of retinopathy among our population and to assess the optimal time of screening children and adolescents with type 1 diabetes.
Adolescent↗
The generation and characterisation of antagonist RNA aptamers to MCP-1.
Monocyte chemoattractant protein-1 (MCP-1) has been implicated as a powerful pro-inflammatory mediator and may represent a potentially important, therapeutic opportunity for treatment of inflammatory disease and atherosclerosis. To further investigate the role of MCP-1 in inflammatory disorders we have isolated a series of RNA aptamers that bind specifically to mouse MCP-1. The highest affinity aptamers, designated ADR7 and ADR22, have been functionally characterised in vitro and in cell based assays. ADR7 and ADR22 have an affinity of 180 pM and 370 pM respectively for mouse MCP-1, they can antagonise MCP-1 binding to heparin and specifically antagonise MCP-1 induced chemotaxis in a cell based assay. An interesting feature of ADR22 but not ADR7 is that it is capable of antagonising the function of human MCP-1, demonstrating the high level of specificity of these aptamers and that the aptamers recognise MCP-1 in different ways. The aptamers may be used as a tool to further investigate the role of MCP-1 in inflammatory disorders and may also have a role as a therapeutic agent.
Animals↗
The Acp26Aa seminal fluid protein is a modulator of early egg hatchability in Drosophila melanogaster.
Drosophila melanogaster male accessory gland proteins (Acps) that are transferred in the ejaculate with sperm mediate post-mating competition for fertilizations between males. The actions of Acps include effects on oviposition and ovulation, receptivity and sperm storage. Two Acps that modulate egg production are Acp26Aa (ovulin) and Acp70A (the sex peptide). Acp26Aa acts specifically on the process of ovulation (the release of mature eggs from the ovaries), which is initiated 1.5 h after mating. In contrast, sperm storage can take as long as 6-9 h to complete. Initial ovulations after matings by virgin females will therefore occur before all sperm are fully stored and the extra eggs initially laid as a result of Acp26Aa transfer are expected to be inefficiently fertilized. Acp26Aa-mediated release of existing eggs should not cause a significant energetic cost or lead to a decrease in female lifespan assuming, as seems likely, that the energetic cost of egg laying comes from de novo egg synthesis (oogenesis) rather than from ovulation. We tested these predictions using Acp26Aa(1) mutant males that lack Acp26Aa but are normal for other Acps and Acp26Aa(2) males that transfer a truncated but fully functional Acp26Aa protein. Females mating with Acp26Aa(2) (truncation) males that received functional Acp26Aa produced significantly more eggs following their first matings than did mates of Acp26Aa(1) (null) males. However, as predicted above, these extra eggs, which were laid as a result of Acp26Aa transfer to virgin females, showed significantly lower egg hatchability. Control experiments indicated that this lower hatchability was due to lower rates of fertilization at early post-mating times. There was no drop in egg hatchability in subsequent non-virgin matings. In addition, as predicted above, females that did or did not receive Acp26Aa did not differ in survival, lifetime fecundity or lifetime progeny, indicating that Acp26Aa transfer does not represent a significant energetic cost for females and does not contribute to the survival cost of mating. Acp26Aa appears to remove a block to oogenesis by causing the clearing out of existing mature eggs and, thus, indirectly allowing oogenesis to be initiated immediately after mating. The results show that subtle processes coordinate the stimulation of egg production and sperm storage in mating pairs.
Animals↗
Seminal fluid-mediated fitness traits in Drosophila.
The seminal fluid of male Drosophila contains a cocktail of proteins that have striking effects on male and female fitness. In D. melanogaster, seminal fluid proteins affect female receptivity, ovulation, oogenesis, sperm storage, sperm competition and mating plug formation. In addition, the seminal fluid contains antibacterial peptides and protease inhibitors. Some seminal fluid-encoding genes also show high rates of evolutionary change, exhibiting both significant between-species divergence and within-species polymorphism. Seminal fluid protein genes are expressed only in males, begging the question of how and why the reproductive processes of females are influenced by males. In this review I address these issues by bringing together evidence for the function, evolution, diversification, and maintenance of variation in, seminal fluid-mediated traits.
Animals↗
Primary aortoduodenal fistula in a patient with a history of intravesical therapy for bladder cancer with bacillus Calmette-Guérin: review of primary aortoduodenal fistula without abdominal aortic aneurysm.
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Administration, Intravesical↗
Misleading results with the 14-3-3 assay for the diagnosis of Creutzfeldt-Jakob disease.
The definitive diagnosis of Creutzfeldt-Jakob disease (CJD) requires brain tissue analysis. A positive assay for the 14-3-3 protein in CSF has been suggested to be highly sensitive and specific in patients with CJD. The authors describe three patients for whom CSF 14-3-3 assays were falsely positive or falsely negative. Caution against overreliance on this putative biomarker is suggested in the diagnosis of CJD.
14-3-3 Proteins↗
It's time to strengthen the safety net.
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Child↗
The role of male accessory gland protein Acp36DE in sperm competition in Drosophila melanogaster.
A crucial factor determining sperm fertilization success in multiply mated Drosophila melanogaster females is the efficiency with which sperm are stored. This process is modulated by the accessory gland protein Acp36DE. In this study, we show that the effect of Acp36DE on sperm storage itself alters the outcome of sperm competition. As second-mating males, Acp36DE1 (null) males had significantly lower P2-values than Acp36DE2 (truncation) or Acp36DE+ (control) males, as might be expected as the null males' sperm are poorly stored. We used spermless males, which are null for Acp36DE, to show that, in the absence of sperm co-transfer, Acp36DE itself could not displace first-male sperm. The results therefore suggest that males null for Acp36DE suffer in sperm displacement because fewer sperm are stored or retained, not because Acp36DE itself displaces sperm. Acp36DE1 (null) males also gained significantly fewer fertilizations than controls when they were the first males to mate. Using spermless males, we also showed that significantly more second-male offspring were produced following the transfer of Acp36DE by spermless first-mating males. This implies that the transfer of Acp36DE itself by the first male facilitated the storage or use of the second male's sperm and that co-transfer with sperm is not necessary for Acp36DE effects on second-male sperm storage. Acp36DE may persist in the reproductive tract and aid the storage of any sperm including those of later-mating males or prime the female for future efficient sperm storage. Our results indicate that mutations in genes that affect sperm storage can drastically affect the outcome of sperm competition.
Animals↗