Assembly rules for protein networks derived from phylogenetic-statistical analysis of whole genomes

Background: We report an analysis of a protein network of functionally linked proteins, identified from a phylogenetic statistical analysis of complete eukaryotic genomes. Phylogenetic methods identify pairs of proteins that co-evolve on a phylogenetic tree, and have been shown to have a high probability of correctly identifying known functional links. Results: The eukaryotic correlated evolution network we derive displays the familiar power law scaling of connectivity. We introduce the use of explicit phylogenetic methods to reconstruct the ancestral presence or absence of proteins at the interior nodes of a phylogeny of eukaryote species. We find that the connectivity distribution of proteins at the point they arise on the tree and join the network follows a power law, as does the connectivity distribution of proteins at the time they are lost from the network. Proteins resident in the network acquire connections over time, but we find no evidence that 'preferential attachment' - the phenomenon of newly acquired connections in the network being more likely to be made to proteins with large numbers of connections - influences the network structure. We derive a 'variable rate of attachment' model in which proteins vary in their propensity to form network interactions independently of how many connections they have or of the total number of connections in the network, and show how this model can produce apparent power-law scaling without preferential attachment. Conclusion: A few simple rules can explain the topological structure and evolutionary changes to protein-interaction networks: most change is concentrated in satellite proteins of low connectivity and small phenotypic effect, and proteins differ in their propensity to form attachments. Given these rules of assembly, power law scaled networks naturally emerge from simple principles of selection, yielding protein interaction networks that retain a high-degree of robustness on short time scales and evolvability on longer evolutionary time scales.

Risk factors for tick attachment to smallholder dairy cattle in Tanzania

A cross-sectional study was conducted in Tanga and Iringa regions of Tanzania, and a longitudinal study in Tanga, to investigate tick-control methods and other factors influencing tick attachment to the cattle of smallholder dairy farms. Most farmers reported applying acaricides at intervals of 1-2 weeks, most used acaricides that require on-farm dilution and most farmers incorrectly diluted the acaricides. Rhipicephalus appendiculatus and Boophilus spp. ticks were those most-frequently encountered on the cattle, but few cattle carried ticks of any species (only 13 and 4.6% of tick counts of the cattle yielded adult R. appendiculatus and Boophilus spp., respectively). Animals were more likely to carry one or more adult Boophilus spp. ticks if they also carried one or more R. appendiculatus adults (OR = 14.4, CI = 9.2, 22.5). The use of pour-on acaricides was associated with lower odds that animals carried a R. appendiculatus tick (OR = 0.29, CI = 0. 18, 0.49) but higher odds that they carried a Boophilus spp. tick (OR = 2.48, CI = 1.55, 3.97). Animals > 4 months old and those with a recent history of grazing had higher odds of carrying either a R. appendiculatus (ORs = 3.41 and 2.58, CIs = 2.34, 4.98 and 1.80, 3.71), or a Boophilus spp. tick (ORs = 5.70 and 2.18, CIs = 2.34, 4.98 and 1.49. 3.25), but zero-grazing management did not prevent ticks attaching to cattle even when combined with high-frequency acaricide treatments. The odds that animals carried ticks varied amongst the agro-ecological zones (AEZs) and administrative districts where the farms were situated-but there was still considerable residual variation in tick infestation at the farm level. (c) 2004 Elsevier B.V. All rights reserved.

The structure of echovirus type 12 bound to a two-domain fragment of its cellular attachment protein decay-accelerating factor (CD 55)

Echovirus type 12 (EV12), an enterovirus of the Picornaviridae family, uses the complement regulator, decay-accelerating factor (DAF, CD55) as a cellular receptor. We have calculated a three-dimensional reconstruction of EV12 bound to a fragment of DAF, consisting of short consensus repeat domains 3 and 4, from cryo-negative stain electron microscopy data (EMD #1057). This shows that, as for an earlier reconstruction of the related echovirus type 7 bound to DAF, attachment is not within the viral canyon but occurs close to the two-fold symmetry axes. Despite this general similarity, our reconstruction reveals a receptor interaction that is quite different from that observed for EV7. Fitting of the crystallographic co-ordinates for DAF34 and EV11 into the reconstruction shows a close agreement between the crystal structure of the receptor fragment and the density for the virus-bound receptor, allowing unambiguous positioning of the receptor with respect to the virion (PDB #1UPN). Our finding that the mode of virus-receptor interaction in EV12 is distinct from that seen for EV7 raises interesting questions regarding the evolution and biological significance of the DAF-binding phenotype in these viruses.

Dissociative electron attachment to dinitrogen pentoxide, N2O5

Electron attachment was studied in gaseous dinitrogen pentoxide, N2O5, for incident electron energies between a few meV and 10 eV. No stable parent anion N2O5- was observed but several anionic fragments (NO3-, NO2-, NO-, O-, and O-2(-)) were detected using quadrupole mass spectrometry. Many of these dissociative pathways were found to be coupled and provide detailed information on the dynamics of N2O5 fragmentation. Estimates of the cross sections for production of each of the anionic fragments were made and suggest that electron attachment to N2O5 is amongst the most efficient attachment reactions recorded for nonhalogenated polyatomic systems. (C) 2004 American Institute of Physics.

Place attachment and sense of belonging in the offices

Examines the concept of “place attachment” as defined in various disciplines and develops an effective conceptual approach that can be applied to facilities management. Describes the development of a model-matchmaking process adapted from Passini's model of cognitive mapping. Findings that the emergence of the new economy is undermining our ability to form attachments with people, places and companies. However, one of the unintended effects of this is that it has strengthened the value of place and aroused a longing for community. Moreover, loyalty to an organisation is increasingly determined by social and place attachment. Proposes that further research needs to be undertaken to “engineer out” the negative impacts of flexibility associated with loss of place. States that place attachment presents a challenging view of the world that is contrary to all the received wisdom in facilities management, where flexibility has always assumed an unchallenged position in relation to buildings and people. Concludes that this research area presents many pragmatic design and operational questions for facilities managers.

The mother-infant relationship and infant attachment in a south African peri-urban settlement

A sample of 147 mother-infant dyads was recruited from a peri-urban settlement outside Cape Town and seen at 2- and 18-months postpartum. At 18 months, 61.9% of the infants were rated as securely attached (B); 4.1% as avoidant (A); 8.2% as resistant (C); and 25.8% disorganized (D). Postpartum depression at 2 months, and indices of poor parenting at both 2 and 18 months, were associated with insecure infant attachment. The critical 2-month predictor variables for insecure infant attachment were maternal intrusiveness and maternal remoteness, and early maternal depression. When concurrent maternal sensitivity was considered, the quality of the early mother-infant relationship remained important, but maternal depression was no longer predictive. Cross-cultural differences and consistencies in the development of attachment are discussed.

Socioemotional development in adolescents at risk for depression: the role of maternal depression and attachment style

We examined the impact on adolescent socioemotional functioning of maternal postnatal depression (PND) and attachment style. We also investigated the role of earlier aspects of the child's development-attachment in infancy, and 5-year representations of family relationships. Ninety-one mother-child pairs, recruited in the postnatal period, were followed tip at 13 years. Adolescents were interviewed about their friendships, and their level of emotional sensitivity and maturity were rated. Emotional sensitivity was heightened in girls whose mothers experienced PND; notably, its occurrence was also linked to insecure attachment in infancy and raised awareness of emotional components of family relationships at 5 years. High emotional sensitivity was also associated with adolescent depressed mood. Raised social maturity was predicted by a secure maternal attachment style and, for girls, by exposure to maternal PND. Precursors of adolescent social maturity were evident in the narrative coherence of 5-year family representations. Higher social maturity in the friendship interview was also associated with overall good adjustment.

Discrepancy between parental reports of infants' receptive vocabulary and infants' behaviour in a preferential looking task

Two experiments are described which explore the relationship between parental reports of infants' receptive vocabularies at 1; 6 (Experiment 1a) or 1-3, 1;6 and 1;9 (Experiment 1b) and the comprehension infants demonstrated in a preferential looking task. The instrument used was the Oxford CD1, a British English adaptation of the MacArthur-Bates CD1 (Words & Gestures). Infants were shown pairs of images of familiar objects, either both name-known or both name-unknown according to their parent's responses on the CD1. At all ages, and on both name-known and name-unknown trials, preference for the target image increased significantly from baseline when infants heard the target's label. This discrepancy suggests that parental report underestimates infants' word knowledge.

The role played by the interaction between genetic factors and attachment in the stress response in infancy

Background: The importance of understanding which environmental and biological factors are involved in determining individual differences in physiological response to stress is widely recognized, given the impact that stress has on physical and mental health. Methods: The child-mother attachment relationship and some genetic polymorphisms (5-HTTLPR, COMT and GABRA6) were tested as predictors of salivary cortisol and alpha amylase concentrations, two biomarkers of hypothalamic-pituitary-adrenocortical (HPA) axis and sympathetic adrenomedullary (SAM) system activity, during the Strange Situation (SS) procedure in a sample of more than 100 healthy infants, aged 12 to 18 months. Results: Individual differences in alpha amylase response to separation were predicted by security of attachment in interaction with 5-HTTLPR and GABRA6 genetic polymorphisms, whereas alpha amylase basal levels were predicted by COMT x attachment interaction. No significant effect of attachment, genetics and their interaction on cortisol activity emerged. Conclusions: These results help to disentangle the role played by both genetic and environmental factors in determining individual differences in stress response in infancy. The results also shed light on the suggestion that HPA and SAM systems are likely to have different characteristic responses to stress.

Improving quality of mother-infant relationship and infant attachment in socioeconomically deprived community in South Africa: randomised controlled trial

Objective To assess the efficacy of an intervention designed to improve the mother-infant relationship and security of infant attachment in a South African peri-urban settlement with marked adverse socioeconomic circumstances. Design Randomised controlled trial. Setting Khayelitsha, a peri-urban settlement in South Africa. Participants 449 pregnant women. Interventions The intervention was delivered from late pregnancy and for six months postpartum. Women were visited in their homes by previously untrained lay community workers who provided support and guidance in parenting. The purpose of the intervention was to promote sensitive and responsive parenting and secure infant attachment to the mother. Women in the control group received no therapeutic input from the research team. Main outcome measures Primary outcomes: quality of mother-infant interactions at six and 12 months postpartum; infant attachment security at 18 months. Secondary outcome: maternal depression at six and 12 months. Results The intervention was associated with significant benefit to the mother-infant relationship. At both six and 12 months, compared with control mothers, mothers in the intervention group were significantly more sensitive (6 months: mean difference=0.77 (SD 0.37), t=2.10, P<0.05, d=0.24; 12 months: mean difference=0.42 (0.18), t=-2.04, P<0.05, d=0.26) and less intrusive (6 months: mean difference=0.68 (0.36), t=2.28, P<0.05, d=0.26; 12 months: mean difference=-1.76 (0.86), t=2.28, P<0.05, d=0.24) in their interactions with their infants. The intervention was also associated with a higher rate of secure infant attachments at 18 months (116/156 (74%) v 102/162 (63%); Wald=4.74, odds ratio=1.70, P<0.05). Although the prevalence of maternal depressive disorder was not significantly reduced, the intervention had a benefit in terms of maternal depressed mood at six months (z=2.05, P=0.04) on the Edinburgh postnatal depression scale). Conclusions The intervention, delivered by local lay women, had a significant positive impact on the quality of the mother-infant relationship and on security of infant attachment, factors known to predict favourable child development. If these effects persist, and if they are replicated, this intervention holds considerable promise for use in the developing world. Trial registration Current Controlled Trials ISRCTN25664149.

Infant-mother attachment and the growth of externalizing problems across the primary-school years

Background:  Some contend that attachment insecurity increases risk for the development of externalizing behavior problems in children. Method:  Latent-growth curve analyses were applied to data on 1,364 children from the NICHD Study of Early Child Care to evaluate the association between early attachment and teacher-rated externalizing problems across the primary-school years. Results:  Findings indicate that (a) both avoidant and disorganized attachment predict higher levels of externalizing problems but (b) that effects of disorganized attachment are moderated by family cumulative contextual risk, child gender and child age, with disorganized boys from risky social contexts manifesting increases in behavior problems over time. Conclusions:  These findings highlight the potentially conditional role of early attachment in children’s externalizing behavior problems and the need for further research evaluating causation and mediating mechanisms.

Infant Attachment Security and the Timing of Puberty: Testing an Evolutionary Hypothesis

Life-history theories of the early programming of human reproductive strategy stipulate that early rearing experience, including that reflected in infant-parent attachment security, regulates psychological, behavioral, and reproductive development. We tested the hypothesis that infant attachment insecurity, compared with infant attachment security, at the age of 15 months predicts earlier pubertal maturation. Focusing on 373 White females enrolled in the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development, we gathered data from annual physical exams from the ages of 9½ years to 15½ years and from self-reported age of menarche. Results revealed that individuals who had been insecure infants initiated and completed pubertal development earlier and had an earlier age of menarche compared with individuals who had been secure infants, even after accounting for age of menarche in the infants’ mothers. These results support a conditional-adaptational view of individual differences in attachment security and raise questions about the biological mechanisms responsible for the attachment effects we discerned.

The significance of insecure attachment and disorganization in the development of children's externalizing behavior: A meta-analytic study

This study addresses the extent to which insecure and disorganized attachments increase risk for externalizing problems using meta-analysis. From 69 samples (N = 5,947), the association between insecurity and externalizing problems was significant, d = 0.31 (95% CI: 0.23, 0.40). Larger effects were found for boys (d = 0.35), clinical samples (d = 0.49), and from observation-based outcome assessments (d = 0.58). Larger effects were found for attachment assessments other than the Strange Situation. Overall, disorganized children appeared at elevated risk (d = 0.34, 95% CI: 0.18, 0.50), with weaker effects for avoidance (d = 0.12, 95% CI: 0.03, 0.21) and resistance (d = 0.11, 95% CI: −0.04, 0.26). The results are discussed in terms of the potential significance of attachment for mental health.