Genetic variation underlying protein expression in eggs of the marine mussel Mytilus edulis

Study of the genetic basis of gene expression variation is central to attempts to understand the causes of evolutionary change. Although there are many transcriptomics studies estimating genetic variance and heritability in model organisms such as humans there is a lack of equivalent proteomics studies. In the present study, the heritability underlying egg protein expression was estimated in the marine mussel Mytilus. We believe this to be the first such measurement of genetic variation for gene expression in eggs of any organism. The study of eggs is important in evolutionary theory and life history analysis because maternal effects might have profound effects on the rate of evolution of offspring traits. Evidence is presented that the egg proteome varies significantly between individual females and that heritability of protein expression in mussel eggs is moderate to high suggesting abundant genetic variation on which natural selection might act. The study of the mussel egg proteome is also important because of the unusual system of mitochondrial DNA inheritance in mussels whereby different mitochondrial genomes are transmitted independently through female and male lineages (doubly uniparental inheritance). It is likely that the mechanism underlying this system involves the interaction of specific egg factors with sperm mitochondria following fertilization, and its elucidation might be advanced by study of the proteome in females having different progeny sex ratios. Putative identifications are presented here for egg proteins using MS/MS in Mytilus lines differing in sex ratio. Ontology terms relating to stress response and protein folding occur more frequently for proteins showing large expression differences between the lines. The distribution of ontology terms in mussel eggs was compared with those for previous mussel proteomics studies (using other tissues) and with mammal eggs. Significant differences were observed between mussel eggs and mussel tissues but not between the two types of eggs.

Fingerprint profile of Ginkgo biloba nutritional supplements by LC/ESI-MS/MS

Ginkgo biloba is one of the most popular herb nutrition supplements, with terpene lactones and flavonoids being the two major active components. A fingerprint profile method was developed using a capillary HPLC/MS method which can identify more than 70 components from the G. biloba product. The method allows the flavonoids and terpene lactones to be detected simultaneously and information of both the parent ion and its fragmentation can be obtained in just one HPLC/MS run. Targeted post-acquisition analysis allows mass spectrometric information regarding the identification of flavonoid components to be easily distinguished from other data, however the same approach for terpene lactones was less successful due to dimer formation and requires further development. The fingerprint profiles of five commercial G. biloba nutritional supplements were obtained and compared; variation of some components among the samples was observed and fortification could be detected. In the quality control analysis of the G. biloba product this method could be viewed as complementary to specific quantitative analysis of some bioactive components of the herb.

The antibacterial activity against MRSA strains and other bacteria of a <500Da fraction from maggot excretions/secretions of Lucilia sericata (Diptera: Calliphoridae)

The application of Lucilia sericata larvae to chronic, infected wounds results in the rapid elimination of infecting microorganisms, including MRSA. Previously, we demonstrated in vitro antibacterial activity of native excretions/secretions (nES) from L. sericata and partially purified two low mass antibacterial compounds with masses of 0.5-10kDa and <500Da. The present study reports the antibacterial effects of the <500Da fraction (ES<500) on the growth and morphology of a range of bacteria, including 12 MRSA strains. Distinct morphological changes were observed in Bacillus cereus and Escherichia coli following exposure to ES<500. Flow cytometry and confocal microscopy analyses, in conjunction with turbidometric and CFU assays, revealed bacteriostatic activity of nES against S. aureus and E. coli. ES<500 also demonstrated bacteriostatic activity against S. aureus, however, bactericidal activity and the induction of a viable but non-culturable state were observed with ES<500-treated E. coli.

Solution structure of the novel dispersin protein of enteroaggregative Escherichia coli

Enteroaggregative Escherichia coli (EAEC), increasingly recognized as an important cause of infant and travelers' diarrhoea, exhibits an aggregative, stacked-brick pattern of adherence to epithelial cells. Adherence is mediated by aggregative adherence fimbriae (AAFs), which are encoded on the pAA virulence plasmid. We recently described a highly prevalent pAA plasmid-borne gene, aap, which encodes a protein (nicknamed dispersin) that is secreted to the bacterial cell surface. Dispersin-null mutants display a unique hyper-aggregating phenotype, accompanied by collapse of AAF pili onto the bacterial cell surface. To study the mechanism of this effect, we solved the structure of dispersin from EAEC strain 042 using solution NMR, revealing a stable beta-sandwich with a conserved net positive surface charge of +3 to +4 among 23 dispersin alleles. Experimental data suggest that dispersin binds non-covalently to lipopolysaccharide on the surface of the bacterium. We also show that the AAF organelles contribute positive charge to the bacterial surface, suggesting that dispersin's role in fimbrial function is to overcome electrostatic attraction between AAF and the bacterial surface.

A 5.8-kDa component of manuka honey stimulates immune cells via TLR4

Honey is used as a therapy to aid wound healing. Previous data indicate that honey can stimulate cytokine production from human monocytes. The present study further examines this phenomenon in manuka honey. As inflammatory cytokine production in innate immune cells is classically mediated by pattern recognition receptors in response to microorganisms, bacterial contamination of honey and the effect of blocking TLR2 and -4 on stimulatory activity were assessed. No vegetative bacteria were isolated from honey; however, bacterial spores were cultured from one-third of samples, and low levels of LPS were detected. Blocking TLR4 but not TLR2 inhibited honey-stimulated cytokine production significantly. Cytokine production did not correlate with LPS levels in honey and was not inhibited by polymyxin B. Further, the activity was reduced significantly following heat treatment, indicating that component(s) other than LPS are responsible for the stimulatory activity of manuka honey. To identify the component responsible for inducing cytokine production, honey was separated by molecular weight using microcon centrifugal filtration and fractions assessed for stimulatory activity. The active fraction was analyzed by MALDI-TOF mass spectroscopy, which demonstrated the presence of a number of components of varying molecular weights. Additional fractionation using miniaturized, reverse-phase solid-phase extraction resulted in the isolation of a 5.8-kDa component, which stimulated production of TNF-alpha via TLR4. These findings reveal mechanisms and components involved in honey stimulation of cytokine induction and could potentially lead to the development of novel therapeutics to improve wound healing for patients with acute and chronic wounds.

Mass spectrometric identification of Rab23 phosphorylation as a response to challenge by cytidine 3',5'-cyclic monophosphate in mouse brain

While the functions and mechanisms of action of adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP) are well established and are the basis of the action of a large number of successful pharmaceuticals, the role of a third naturally occurring cyclic nucleotide, cytidine 3',5'-cyclic monophosphate (cCMP), remains to be elucidated. Immobilized metal affinity chromatography (IMAC) was used to selectively extract proteins phosphorylated in mouse brain in response to challenge by cAMP, cGMP and cCMP, followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToFMS) and liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) of tryptic digests to identify Rab23 as the first protein reported to be phosphorylated only in response to cCMP.

New insights from MALDI-ToF MS, NMR, and GC-MS: mass spectrometry techniques applied to palynology

The present study for the first time describes the application of matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-ToF MS) to palynology. With an accessible mass range of up to about 350,000 Da at subpicomolar range, this technique is ideal for the characterisation of bio-macromolecules, such as sporopollenin, found in fossil and extant pollen and spore walls, which often can only be isolated in very small quantities. At this stage, the limited solubility of sporopollenin allows for the identification of sections of this biopolymer, but with the optimisation of MALDI-ToF matrices, further structure elucidation will become possible. Furthermore, gas chromatography-mass spectrometry (GC-MS) and (1)H nuclear magnetic resonance ((1)H NMR) spectroscopy data obtained from a number of experiments revealed that some previously reported data were misinterpreted. These results add support to the hypothesis that common plasticizers were wrongly described as sporopollenin compounds.

Analysis of urinary nucleosides. V. Identification of urinary pyrimidine nucleosides by liquid chromatography/electrospray mass spectrometry

Modified urinary nucleosides are potentially invaluable in cancer diagnosis, as they reflect altered RNA turnovers. High-performance liquid chromatography (HPLC) was combined with full-scan mass spectrometry, tandem mass spectrometry, MS(n) analysis and accurate mass measurements in order to identify pyrimidine nucleosides purified from urine. Potential nucleosides were assessed by their evident UV absorbance in the HPLC chromatogram and then further examined by the various mass spectrometric techniques. In this manner numerous pyrimidine nucleosides were identified in the urine samples from cancer patients including pseudouridine, cytidine, two methylcytidines and an acetylcytidine. Furthermore, a number of novel modified pyrimidine nucleosides were tentatively identified via critical interpretation of the combined mass spectrometric data.

Study of the mass spectrometric fragmentation of pseudouridine: comparison of fragmentation data obtained by matrix-assisted laser desorption/ionisation post-source decay, electrospray ion trap multistage mass spectrometry, and by a method utilising electrospray quadrupole time-of-flight tandem mass spectrometry and in-source fragmentation

Many nucleosides and their modified forms have been studied by mass spectrometry elaborating the detailed fragmentation pathways under MS2 and MS(n) conditions. Although the C-nucleoside pseudouridine has been fragmented and studied briefly, usually amongst many other nucleosides, it has not been investigated to the same extent as other nucleosides. In this report a number of different mass spectrometric techniques are applied to obtain a fuller picture of pseudouridine fragmentation. At the same time this study is used to compare different tandem mass spectrometric techniques, including a novel methodology utilising a quadrupole time-of-flight (Q-ToF) instrument for MS(n) analysis comparable with that available with an ion trap mass spectrometer.

Suppression of serum antibody responses by pertussis toxin after respiratory tract colonization by Bordetella pertussis and identification of an immunodominant lipoprotein

Pertussis toxin (PT), a virulence factor secreted by Bordetella pertussis, contributes to respiratory tract infection and disease caused by this pathogen. By comparing a wild-type (WT) B. pertussis strain to a mutant strain with an in-frame deletion of the ptx genes encoding PT (DeltaPT), we recently found that the lack of PT confers a significant defect in respiratory tract colonization in mice after intranasal inoculation. In this study, we analyzed serum antibody responses in mice infected with the WT or DeltaPT strain and found that infection with the DeltaPT strain elicited greater responses to several B. pertussis antigens than did infection with the WT, despite the lower colonization level achieved by the DeltaPT strain. The same enhanced antibody response was observed after infection with a strain expressing an enzymatically inactive PT; but this response was not observed after infection with B. pertussis mutant strains lacking filamentous hemagglutinin or adenylate cyclase toxin, nor when purified PT was administered with the DeltaPT inoculum, indicating a specific role for PT activity in this immunosuppressive effect. In particular, there were consistent strong serum antibody responses to one or more low-molecular-weight antigens after infection with the DeltaPT strain. These antigens were Bvg independent, membrane localized, and also expressed by the closely related pathogens Bordetella parapertussis and Bordetella bronchiseptica. Two-dimensional gel electrophoresis and mass spectrometry were used to identify one of the immunodominant low-molecular-weight antigens as a protein with significant sequence homology to peptidoglycan-associated lipoprotein in several other gram-negative bacterial species. However, a serum antibody response to this protein alone did not protect mice against respiratory tract infection by B. pertussis.

Plant proteome analysis by mass spectrometry: principles, problems, pitfalls and recent developments

The genome of several species has now been elucidated; these genomes indicate the proteomic potential of the cell. While identification of genomes has been, and continues to be, a technically and intellectually demanding process, the identification of the proteome contains inherently greater difficulties. The proteome of each living cell is dynamic, altering in response to the individual cell's metabolic state and reception of intracellular and extracellular signal molecules, and many of the proteins which are expressed will be post-translationally altered. Thus if the purpose of the proteome analysis is to aid the understanding of protein function and interaction, then it is identification of the proteins in their final state which is required: for this mass spectrometric identification of individual proteins, indicating site and nature of modifications, is essential. Here we review the principles of the methodologies involved in such analyses, give some indication of current achievements in plant proteomics, and indicate imminent and prospective technical developments.

Analysis of urinary nucleosides. IV. Identification of urinary purine nucleosides by liquid chromatography/electrospray mass spectrometry

Modified urinary nucleosides are potentially invaluable in cancer diagnosis. High-performance liquid chromatography (HPLC) was combined with full scan mass spectrometry (MS), tandem mass spectrometry and MSn analysis in order to identify purine nucleosides purified from urine. UV peaks evident in the chromatogram were examined by the various mass spectrometric techniques and adenosine, 1-methyladenosine, xanthosine, N1-methylguanosine, N2-methylguanosine, N2,N2-dimethylguanosine, N2,N2,N7-trimethylguanosine, inosine, and 1-methylinosine were each identified in the urine samples from cancer patients. The benefits of the use of LC/MS compared with HPLC alone are discussed.

Urinary modified nucleosides as tumor markers

Extracts of urinary nucleosides have been sequentially purified and examined by mass spectrometric analysis. Seventeen modified nucleosides have been unequivocally identified and a further five provisionally identified. While several nucleosides were found only in a small number of extracts, the occurrence and levels of others were found to correlate with the tumour type and stage.

Analysis of urinary nucleosides. III. Identification of 5'-deoxycytidine in urine of a patient with head and neck cancer

Modified nucleosides in the urine have been postulated to be diagnostic indices of disease, particularly of cancer. The urine of a patient with terminal head and neck cancer has been found to contain a modified nucleoside with a protonated molecule of m/z 228. By means of high-performance liquid chromatography/ion trap mass spectrometry (HPLC/ITMS) and capillary liquid chromatography/triple quadruple mass spectrometry (CapLC/TQMS) we have identified the compound as 5'-deoxycytidine. This is the first report of 5'-deoxycytidine in man: in addition to the elucidation of its structure, its possible origins and the potential significance of its occurrence are discussed.

Empty nest or revolving door? A prospective study of women's quality of life in midlife during the phase of children leaving and re-entering the home

BACKGROUND

This study documents changes in household composition and effects on women's quality of life of children leaving and returning home.

METHODS

A 9-year annual prospective study of a population-based sample of mid-aged Australian-born women who were premenopausal at baseline (N = 438) was conducted. Documentation was made of household composition and change, well-being, bothersome symptoms, daily hassles, feelings for partner and frequency of sexual activities.

RESULTS

There was an increase in the number of women living alone, and a reduction in number of households in which there were children or parents. Each year > 25% of women reported a change in household composition. In the first year after the last child departed (N = 155), there was an improvement in women's positive mood and total well-being and a reduction in negative mood and the number of daily hassles. This improvement in mood was confined to those women who at baseline were not worried about children leaving home. In the first year after children return home there was a trend towards reduced frequency of sexual activities but no mood changes.

CONCLUSIONS

For the majority of women, the departure of the last child from the household leads to positive changes in women's mood state and a reduced number of daily hassles. Return of offspring may have an adverse effect on sexual relating of the parents.

Are changes in sexual functioning during midlife due to aging or menopause?

OBJECTIVE

To determine whether changes in women's sexual functioning during midlife are due to aging or menopause.

DESIGN

Prospective, observational study.

SETTING

Population-based sample assessed in own homes.

PATIENT(S)

Four hundred thirty-eight Australian-born women aged 45-55 years and still menstruating at baseline. One hundred ninety-seven were studied for effects of the natural menopausal transition. Control group A (n = 44) remained premenopausal or early perimenopausal for 7 years. Control group B (n = 42) remained postmenopausal over 5 years.

INTERVENTION(S)

Nil; questionnaires and blood sampling annually.

MAIN OUTCOME MEASURE(S)

Shortened version of the Personal Experiences Questionnaire.

RESULT(S)

By the late perimenopause, there was a significant decline in the factors we had derived of sexual responsivity and total score, and there was an increase in the partner's problems factor. By the postmenopausal phase, there was a further decline in the factors sexual responsivity, frequency of sexual activities, libido, and in the total score, and a significant increase in vaginal dyspareunia and partner's problems. Sexual responsivity significantly declined in both control groups.

CONCLUSION(S)

Sexual responsivity is adversely affected by both aging and the menopausal transition. Other domains of female sexual functioning were significantly adversely affected when the women became postmenopausal. The relationship with the partner and his ability to perform sexually is adversely affected by the menopausal transition.

Short scale to measure female sexuality: adapted from McCoy Female Sexuality Questionnaire

This article examines sex-questionnaire data using the Personal Experiences Questionnaire (PEQ; Dennerstein, Hopper, & Burger, 1997). We used data from a population-based sample of 354 Australian mid-aged women and an optimization procedure in order to reduce the length of the PEQ while retaining items measuring the components of female sexual functioning and key determinants. Eight items were selected. We recommend retaining the item related to orgasm (rejected for parsimony only). Eight of the nine items were from the McCoy Female Sexuality Questionnaire, confirming the validity of this source scale. The original wording in the McCoy scale is recommended as considerable data has now become available on reliability and validity.

Factors contributing to positive mood during the menopausal transition

This study determined which variables affect women's positive mood state during the menopausal transition using nine prospective annual assessments of a population based sample of 267 Australian mid-aged women. Longitudinal data analysis carried out by analysis of covariance on Summary Statistics found that positive mood scores remained stable over time and were not related to natural menopausal transition, age, or education. In the early phase of the menopausal transition, positive mood was adversely influenced by baseline interpersonal stress (p = .009) and negative attitudes to aging (p = .026). The most important predictor of positive mood at the phase of late peri-/ postmenopause was positive mood in the premenopause (p = .000). Other factors affecting positive mood in the late peri-/postmenopause were changes in dysphoric symptoms (p = .000), major life events (p = .041), daily hassles (p = .014), marital status (p = .007), and work satisfaction (p = .001). Structural equation modelling found a goodness of fit index of .821.