Greater stress and trauma mediate race-related differences in epigenetic age between Black and White young adults in a community sample

Black Americans suffer lower life expectancy and show signs of accelerated aging compared to other Americans. While previous studies observe these differences in children and populations with chronic illness, whether these pathologic processes exist or how these pathologic processes progress has yet to be explored prior to the onset of significant chronic illness, within a young adult population. Therefore, we investigated race-related differences in epigenetic age in a cross-sectional sample of young putatively healthy adults and assessed whether lifetime stress and/or trauma mediate those differences. Biological and psychological data were collected from self-reported healthy adult volunteers within the local New Haven area (399 volunteers, 19.8% Black, mean age: 29.28). Stress and trauma data was collected using the Cumulative Adversity Inventory (CAI) interview, which assessed specific types of stressors, including major life events, traumatic events, work, financial, relationship and chronic stressors cumulatively over time. GrimAge Acceleration (GAA), determined from whole blood collected from participants, measured epigenetic age. In order to understand the impact of stress and trauma on GAA, exploratory mediation analyses were then used. We found cumulative stressors across all types of events (mean difference of 6.9 p = 2.14e-4) and GAA (β = 2.29 years [1.57-3.01, p = 9.70e-10] for race, partial η2 = 0.091, model adjusted R2 = 0.242) were significantly greater in Black compared to White participants. Critically, CAI total score (proportion mediated: 0.185 [0.073-0.34, p = 6e-4]) significantly mediated the relationship between race and GAA. Further analysis attributed this difference to more traumatic events, particularly assaultive traumas and death of loved ones. Our results suggest that, prior to development of significant chronic disease, Black individuals have increased epigenetic age compared to White participants and that increased cumulative stress and traumatic events may contribute significantly to this epigenetic aging difference.

Double Impact: A Dyadic Discrimination Model for Poor, Minority, and Pregnant Couples

Frequent daily discrimination compounds the negative health impacts of those with multiple marginalized identities, including pregnant mothers and their children. We used a dyadic, moderated, mediated model of 296 young, expectant, poor, urban, primarily minority couples. In this study, we explored if a multiple pathway discrimination model explained the relationship between multiple marginalized identities and health (depression and stress). We also examined if a mediated (discrimination moderated by gender) model, within a minority-stress and intersectional framework explained the relationship with depression and stress for couples. We observed that frequent daily discrimination was associated with negative health outcomes (depression and stress). Women reported significantly more depression than men. Frequent daily discrimination mediated the relationship between multiple marginalized identities and depression and stress and having a partner with multiple marginations increased one's personal depression and stress. Our observations suggest that discrimination's impact on health is experienced during pregnancy and the more marginalized identities one carries, the more impact it may have. Further, having a partner with multiple marginalized identities also impacts the depression and stress reported by women. Inventions to address depression and stress outcomes may be strengthened by considering multiple marginalized identities and include couples.

Examining the Effects of Fathers' Residency Status on Childhood Obesity

OBJECTIVE

To examine whether fathers' residency status is associated with increased BMI z-scores among young and pre-adolescent children.

METHODS

Propensity score matching was used to examine the effects of fathers' residency status on child BMI z-scores for children between the ages of 2-5 and 9-11 years old. Fathers self-reported their residency status as either being residential or nonresidential, based on the amount of time they lived in the same household as the child enrolled in the study. We conducted a series of cross-sectional matched analyses using three waves of data from 1448 families who participated in the Fragile Families and Child Wellbeing Study.

RESULTS

We did not find a difference in BMI z-scores among children based on their father's residency status for children between the ages of 2-5 years old but did find a marginally significant difference in BMI z-scores for children between 9 and 11 years old.

CONCLUSIONS FOR PRACTICE

Our findings suggest that fathers' residency status is not associated with increased BMI z-scores among young children but may be slightly predictive of differences in BMI z-scores among pre-adolescent children. The results from our study begin to explore the scientific gains of analyzing the influence of diverse family structures on childhood obesity outcomes. Our focus on fathers' residency status adds to the literature by highlighting some of the risks and resources that fathers from diverse family structures bring to family functioning and children's health and wellbeing.

The Stress and Resilience Town Hall: A systems response to support the health workforce during COVID-19 and beyond

OBJECTIVE

The COVID-19 pandemic is a traumatic stressor resulting in anxiety, depression, post-traumatic stress, and burnout among healthcare workers. We describe an intervention to support the health workforce and summarize results from its 40-week implementation in a large, tri-state health system during the COVID-19 pandemic.

METHOD

We conducted 121 virtual and interactive Stress and Resilience Town Halls attended by 3555 healthcare workers. Town hall participants generated 1627 stressors and resilience strategies that we coded and analyzed using rigorous qualitative methods (Kappa = 0.85).

RESULTS

We identify six types of stressors and eight types of resilience strategies reported by healthcare workers, how these changed over time, and how town halls were responsive to emerging health workforce needs. We show that town halls dedicated to groups working together yielded 84% higher mean attendance and more sharing of stressors and resilience strategies than those offered generally across the health system, and that specific stressors and strategies are reported consistently while others vary markedly over time.

CONCLUSIONS

The virtual and interactive Stress and Resilience Town Hall is an accessible, scalable, and sustainable intervention to build mutual support, wellness, and resilience among healthcare workers and within hospitals and health systems responding to emerging crises, pandemics, and disasters.

Intimate Partner Violence Among Low-Income Fathers: Testing a Stress-Coping Model

This research used a stress-coping conceptual framework to examine intimate partner violence (IPV) among men who are fathers. The current study examined how perceived stress explained associations between stressors (e.g., employment status, psychological and physical female-to-male partner violence [FMPV], substance use, criminal justice system involvement) and male-perpetrated physical and psychological IPV. Participants were 1,971 low-income, ethnically diverse fathers involved in a statewide fatherhood program. Findings indicated that, across African American, White, and Hispanic/Latino men, male-reported FMPV and criminal justice involvement were associated with psychological and/or physical IPV via perceived stress. Employment status and alcohol use were associated with psychological IPV via perceived stress among African American men only. Implications for community-based fatherhood programs are discussed.

Social Network Characteristics among Racial/Ethnic Minority Young Adult Males with Prior Criminal Justice System Involvement

Research examining social networks and delinquency risk rarely focuses on the unique period of young adulthood. Young adults who have been involved in the criminal justice system (CJS) may associate with high-risk peers or be less central in their social networks, especially in urban, low-resourced contexts. We used social network analysis to examine prior CJS involvement with network composition and centrality among racial/ethnic minority young adult males (n=119). Participants with CJS involvement were highly connected to each other and had high-risk peers, but were no more or less central in their networks. Understanding delinquency risks for racial/ethnic minority young adult males identifies prevention and intervention targets during the transition to adulthood.

Psychological and relational correlates of intimate partner violence profiles among pregnant adolescent couples

We sought to identify relationship and individual psychological factors that related to four profiles of intimate partner violence (IPV) among pregnant adolescent couples: no IPV, male IPV victim only, female IPV victim only, mutual IPV, and how associations differ by sex. Using data from a longitudinal study of pregnant adolescents and partners (n = 291 couples), we used a multivariate profile analysis using multivariate analysis of covariance with between and within-subjects effects to compare IPV groups and sex on relationship and psychological factors. Analyses were conducted at the couple level, with IPV groups as a between-subjects couple level variable and sex as a within-subjects variable that allowed us to model and compare the outcomes of both partners while controlling for the correlated nature of the data. Analyses controlled for age, race, income, relationship duration, and gestational age. Among couples, 64% had no IPV; 23% male IPV victim only; 7% mutual IPV; 5% female IPV victim only. Relationship (F = 3.61, P < .001) and psychological (F = 3.17, P < .001) factors differed by IPV group, overall. Attachment anxiety, attachment avoidance, relationship equity, perceived partner infidelity, depression, stress, and hostility each differed by IPV profile (all P < .01). Attachment anxiety, equity, depression and stress had a significant IPV profile by sex interaction (all P < .05). Couples with mutual IPV had the least healthy relationship and psychological characteristics; couples with no IPV had the healthiest characteristics. Females in mutually violent relationships were at particularly high risk. Couple-level interventions focused on relational issues might protect young families from developing IPV behaviors. Aggr. Behav. 43:26-36, 2017. © 2016 Wiley Periodicals, Inc.

Reflections on a Community Psychology Setting and the Future of the Field

The 50th anniversary of the Swampscott Conference offers an opportunity to reflect on a community psychology setting, The Consultation Center at Yale, that was formed in response to the 1963 Community Mental Health Act and the 1965 Swampscott Conference. The Center has flourished as a community psychology setting for practice, research, and training for 39 of the 50 years since Swampscott. Its creation and existence over this period offers an opportunity for reflection on the types of settings needed to sustain the field into the future.

A Strengths-Based Approach to Prisoner Reentry: The Fresh Start Prisoner Reentry Program

Scholars have called for a strengths-based approach to prisoner reentry, yet there are few available program models that outline how to integrate this approach into the current reentry program landscape. The present article highlights a strengths-based prisoner reentry program that provided services to men both pre- and post-release from prison to the community in the United States. Qualitative findings from focus groups provide preliminary support for the strengths-based approach and highlight men's strengths and needs as well as challenges related to the program's implementation. The reentry program then drew from participants' reports to inform program development activities. Implications and recommendations for integrating strengths-based approaches into prisoner reentry interventions are discussed.

The behavioral ecology of variation in social insects

Understanding the ecological relevance of variation within and between colonies has been an important and recurring theme in social insect research. Recent research addresses the genomic and physiological factors and fitness effects associated with behavioral variation, within and among colonies, in regulation of activity, cognitive abilities, and aggression. Behavioral variation among colonies has consequences for survival and reproductive success that are the basis for evolutionary change.

Ant Genetics: Reproductive Physiology, Worker Morphology, and Behavior

Many exciting studies have begun to elucidate the genetics of the morphological and physiological diversity of ants, but as yet few studies have investigated the genetics of ant behavior directly. Ant genomes are marked by extreme rates of gene turnover, especially in gene families related to olfactory communication, such as the synthesis of cuticular hydrocarbons and the perception of environmental semiochemicals. Transcriptomic and epigenetic differences are apparent between reproductive and sterile females, males and females, and workers that differ in body size. Quantitative genetic approaches suggest heritability of task performance, and population genetic studies indicate a genetic association with reproductive status in some species. Gene expression is associated with behavior including foraging, response to queens attempting to join a colony, circadian patterns of task performance, and age-related changes of task. Ant behavioral genetics needs further investigation of the feedback between individual-level physiological changes and socially mediated responses to environmental conditions.

The Influence of General Discrimination and Social Context on Young Urban Expecting Couples' Mental Health

Young expecting parents face a great deal of challenges as they transition into parenthood. This paper sought to identify racial and gender differences in the relationship between general discrimination, neighborhood problems, neighborhood cohesion, and social support on the depressive and stress symptoms among young expecting couples. Results indicated perceived general discrimination and less social support was associated with increased stress and depression. More neighborhood problems were related to increased depression and more neighborhood cohesion was related to less stress. Moderator analyses showed that the influence of general discrimination and stress was stronger for women than men. In addition, neighborhood cohesion was protective on stress for Blacks and Whites but not for Hispanics. These results indicate the need to address the broader social context for young expectant couples.

Adherence to Traditionally Masculine Norms and Condom-Related Beliefs: Emphasis on African American and Hispanic Men

Although studies have shown that adherence to traditional masculine norms (i.e., Status, Toughness, Antifemininity) affect men's attitudes toward sexual health, there is little research on how men's adherence to these norms affect them in the context of heterosexual, dyadic relationships. Among 296 young pregnant couples, we investigated the extent to which adherence to traditional masculine norms affected male and female partners' own condom-related beliefs (i.e., condom self-efficacy, positive condom attitudes) and that of their partners. We tested an interdependence model using a dyadic-analytic approach to path analysis. We also tested for differences across gender and race-ethnicity (i.e., African American, Hispanic). Results showed that adherence to the Antifemininity and Toughness masculine norms predicted negative condom-related beliefs, whereas, overall, adherence to the Status norm predicted positive condom-related beliefs. Men's and women's adherence to traditional norms about masculinity were associated with their partner's condom self-efficacy, and moderated associations based on gender and race-ethnicity were detected. In contrast, each dyad member's traditional masculine norms were not associated with his or her partner's positive condom attitudes. Taken together, findings indicated that the roles of traditional masculinity and condom-related beliefs in sexual health should be addressed within the context of relationships and associations between masculine norms and condom-related beliefs are not uniformly negative.

Fathers Matter: Involving and Engaging Fathers in the Child Welfare System Process

Research suggests that children with involved and engaged fathers tend to have more positive outcomes relative to physical, cognitive, and social emotional health. Of children who become involved in the child welfare system, involving multiple parents in the case (e.g. mother and father) often results in a greater chance of a child returning home, fewer placement episodes, and reduced trauma that may be caused by separation anxiety. With the rise of single parenting homes (which are mostly maternal) in the United States, child welfare agencies are examining the efficacy of engaging multiple caregivers (esp. fathers) in the child welfare process. Research suggests that in order to involve fathers in child welfare processes, practices and policies must be intentional in implementing systems and protocols that encourage involvement of all parents regardless of relationship status of the parents. However, few child welfare agencies are required to inquire about fathers or involve fathers in the child's case. The purpose of this paper is to highlight efforts of the Connecticut Comprehensive Outcome Review (CCOR) process and discuss challenges and lessons learned from interviews and listening forums/focus groups that included social workers and fathers who are involved in the child welfare system in the state of Connecticut. Recommendations and considerations on engaging and involving fathers are discussed.

Implementation of an in-patient pediatric mortality reduction intervention, Gondar University Hospital, Ethiopia

SETTING

Gondar University Hospital (GUH) is a resource-limited tertiary care hospital in northern Ethiopia.

OBJECTIVE

To evaluate the aggregate effect of care standardization, institutional guidelines, and simulation-based training on pediatric mortality at a resource-limited hospital.

DESIGN

Uncontrolled pre-post study. GUH in-patients aged from 30 days to 14 years were included in the program evaluation (baseline 11 September-18 November 2010; intervention 19 September-9 December 2011). Interns attached to the GUH pediatrics department from 6 September to 9 December 2011 were included in the training evaluation. Institution-specific management guidelines were prepared for choking, respiratory distress, dehydration, sepsis, congestive heart failure, coma, and seizure. Approval for the protocols was obtained from each pediatric faculty member. Interns received a 3.5 h simulation-based training in triage, procedural skills, and protocol usage. Primary outcome was overall deaths (%); secondary outcomes were deaths within 24 h of admission (%) and median pre/post-training emergency management test scores (%).

RESULTS

No difference in mortality (OR 0.72, 95%CI 0.40-1.29, P = 0.265) or first 24 h mortality (crude OR 0.97, 95%CI 0.37-2.55) was observed. Trainee examination scores improved from 33% to 74% (P < 0.001).

CONCLUSION

Combining care standardization, management protocols, and simulation-based training did not reduce mortality among pediatric in-patients. Focused, simulation-based training improved short-term test scores among interns.

Dependence of necrophoric response to oleic acid on social context in the ant,Pogonomyrmex badius

The response of the southern harvester ant,Pogonomyrmex badius, to oleic acid was found to depend on social context. Social context was specified as the number of ants engaging in each of five categories of behavior. When a large percentage of the colony is doing midden work or nest maintenance, papers treated with oleic acid are taken to the midden, as previously reported. However, when a large percentage of the colony is foraging or convening, treated papers are taken into the nest as if they were food items.

Associations of a sexually transmitted disease diagnosis during a relationship with condom use and psychosocial outcomes: (short) windows of opportunity

Few studies have examined whether and how receiving an sexually transmitted disease (STD) diagnosis while in a romantic relationship relates to condom use and psychosocial sexual outcomes. Using dyadic data, we examined associations of a personal or a partner's STD diagnosis during a relationship with condom use, monogamy intentions, condom intentions and attitudes, and STD susceptibility and communication. Because beliefs about how the STD was acquired may shape associations with behavior and cognitions, gender and suspecting that one's partner had other sexual partners (i.e., partner concurrency) were examined as moderators. Participants were 592 individuals in 296 couples expecting a baby; 108 individuals had been diagnosed with an STD during the relationship. Personal STD diagnosis was unrelated to outcomes or was associated with increased risk. A partner's diagnosis related to more positive condom intentions and attitudes. Among men who suspected concurrency, both a personal and a partner's STD diagnosis were associated with less condom use. Receiving the STD diagnosis during pregnancy was associated with greater susceptibility and marginally greater condom use. Results suggest potential benefits of enhancing communication and encouraging joint risk reduction counseling among couples, engaging men more fully in preventive efforts, and capitalizing on the short window during which risk reduction occurs.

The role of prevention in promoting continuity of health care in prisoner reentry initiatives

Most incarcerated individuals will return to the community, and their successful reentry requires consideration of their health and how their health will affect their families and communities. We propose the use of a prevention science framework that integrates universal, selective, and indicated strategies to facilitate the successful reentry of men released from prison. Understanding how health risks and disparities affect the transition from prison to the community will enhance reentry intervention efforts. To explore the application of the prevention rubric, we evaluated a community-based prisoner reentry initiative. The findings challenge all involved in reentry initiatives to reconceptualize prisoner reentry from a program model to a prevention model that considers multilevel risks to and facilitators of successful reentry.

The many faces of manhood: examining masculine norms and health behaviors of young fathers across race

This study examined the relationship between the traditional masculine norms ("status," "toughness" and "antifemininity") of 296 ethnically and racially diverse, young men transitioning to fatherhood and substance use (smoking, alcohol, marijuana, hard drugs) and health behaviors (diet, exercise). Participants were recruited from urban obstetric clinics in the Northeast United States. Logistic and multiple regression equations were constructed to examine the relationship between masculine norms and health behaviors. Moderator effects were also examined. Masculine norm "status" was most endorsed and "antifemininity" was least endorsed. African American young men had higher masculine norm scores than Latino and Whites. Different masculine norms were associated with health-promoting and health-undermining behaviors. Different racial groups who had higher scores on some masculine norms were more likely to engage in either health-promoting or health-undermining behaviors when compared with other ethnic groups in this study. These results observed different relationships between the traditional masculine norms measured and the substance use and health behaviors of diverse, young men transitioning to fatherhood. This may have implications for intervention strategies and future research.

Examining Masculine Norms and Peer Support within a Sample of Incarcerated African American Males

The adherence to masculine norms has been suggested to be influenced by social settings and context. Prisons have been described as a context where survival is dependent on adhering to strict masculine norms that may undermine reintegration back into the larger society. This study attempted to examine the relationship between masculine norms, peer support, and an individual's length of incarceration on a sample of 139 African American men taking part in a pre-release community re-entry program. Results indicate that peer support was associated with length of incarceration and the interaction between the endorsement of masculine norms and peer support significantly predicted the length of incarceration for African American men in this sample. Implications for incarcerated African American men and future research directions are discussed.

Engaging fathers in child protection services: A review of factors and strategies across ecological systems

Current policy regarding child protection services places increasing demands for providers to engage fathers whose children are involved in the child protection process. This requisite brings to the fore the ongoing challenges that fathers have historically faced in working within these systems. Despite this need, there is little empirical evidence regarding the factors and strategies that impact the engagement of fathers in interventions relevant to child protection services. This comprehensive and systemic review synthesizes the available literature regarding factors and strategies that may foster paternal involvement in the child protection system and their services. We organize the literature concerning paternal engagement in child and family services around an ecological model that examines paternal engagement from individual, family, service provider, program, community, and policy levels. We consider factors and strategies along a continuum of engagement through intent to enroll, enrollment, and retention. This review advances theory by elucidating key factors that foster father engagement. The review also highlights the gaps in the literature and provides strategies for how researchers can address these areas. Future directions in the arenas of practice and policy are discussed.

Social networks and the spread of Salmonella in a sleepy lizard population

Although theoretical models consider social networks as pathways for disease transmission, strong empirical support, particularly for indirectly transmitted parasites, is lacking for many wildlife populations. We found multiple genetic strains of the enteric bacterium Salmonella enterica within a population of Australian sleepy lizards (Tiliqua rugosa), and we found that pairs of lizards that shared bacterial genotypes were more strongly connected in the social network than were pairs of lizards that did not. In contrast, there was no significant association between spatial proximity of lizard pairs and shared bacterial genotypes. These results provide strong correlative evidence that these bacteria are transmitted from host to host around the social network, rather than that adjacent lizards are picking up the same bacterial genotype from some common source.

Increasing Outreach, Connection, and Services to Low-Income Non-Custodial Fathers: How Did We Get Here and What Do We Know

This paper documents a model for outreaching, connecting, and serving low-income, ethnically diverse, non-custodial fathers. Men are engaged "where they are" by building their strengths and addressing their needs. The Male Involvement Network's (MIN) collaborative model was created in Connecticut to help fathers become positive and healthy role models by increasing their attachment to their children and families (Smith, 2003). This clinically informed, case management model addresses their physical, emotional, mental, economic and spiritual health needs. Through a relational approach and social modeling it includes skill development in education, economic stability, family/child support, and mental and physical health. Implications for testing this approach are suggested.

Promoting Responsible Fatherhood Programming: Factors Affecting Low-Income Fathers' Involvement in Child Protection Services and Court-Restricted Access to Their Children

This study investigates how unemployment, traumatic sexual experiences, substance use, intimate partner violence, and parental involvement collectively contribute to involvement with child protective system (CPS) and court-restricted access to children among low-income, ethnically diverse fathers. Participants were 164 fathers involved in a statewide fatherhood program. The majority of the fathers in the program were unemployed (76%) and ethnic minorities (66%). Logistic regression revealed that traumatic sexual experiences and number of children were significant predictors of CPS involvement, whereas employment and traumatic sexual experience were associated with court-restricted access to their children. The results elucidate that clinicians and father-hood programs may need to attend to the history of traumatic experiences, as well as other contextual factors, of fathers and identify how, through trauma-focused interventions, to positively affect them and their children.

Adolescent fathers involved with child protection: social workers speak

This study examined adolescent paternity through structured interviews with their social workers. It adds to the literature by exploring if there were young men involved with the child protection services (CPS) system who are fathers, identifying their unique needs, and beginning discussions on working with these young men. CPS social workers from six area offices and one juvenile detention facility completed surveys for each father on their caseload. A 3.5% rate of adolescent paternity was observed across these offices. Information about the nature of the young men's involvement with CPS, their involvement with their children, and their unique needs as fathers are provided. This paper also identifies some practice and policy implications for adolescent fathers and CPS charged with their care.

An Experimental Test of the Rhizopine Concept in Rhizobium meliloti

In some Rhizobium-legume symbioses, compounds known as rhizopines are synthesized by bacteroids and subsequently catabolized by free-living cells of the producing strain. It has been suggested than rhizopines act as proprietary growth substrates and enhance the competitive ability of the producing strain in its interactions with the diverse microbial community found within the rhizosphere. Wild-type, rhizopine-producing Rhizobium meliloti L5-30 and mutant L5-30 strains deficient for either rhizopine synthesis or catabolism were inoculated onto lucerne host plants in competition experiments. These experiments demonstrated that no apparent advantage resulted from the ability to synthesize a rhizopine, whereas the ability to catabolize rhizopine provided a clear advantage when an organism was in competition with a strain without this ability. The results suggest that when an organism is in competition with a catabolism-deficient mutant, the ability to catabolize rhizopine results in enhanced rates of nodulation. The results of the experiments were not consistent with the hypothesis that the sole role of rhizopines is to act as proprietary growth substrates for the free-living population of the producing strain.

Mentoring urban Black Middle-School Male Students: Implications for Academic Achievement

Researchers have called for innovative and culturally responsive intervention programs to enhance male, African American middle school students' academic achievement. Mentoring has received considerable attention as a novel remedy. Although anecdotal evidence supports the positive role of mentoring on academic achievement, these results are not consistent. The Benjamin E. Mays Institute (BEMI) builds on the ideals of mentoring to counter the effects academic underachievement among adolescent Black males by building a model that is Afro-centric, uses pro-social modeling, and emphasizes cultural strengths and pride, and single-sex instruction in a dual-sex educational environment. Sixty-one middle-school Black males were enrolled (BEMI: n=29; Comparison: n=32) in this study. Results revealed that students in the BEMI program had significantly greater academic attachment scores and academic success than their non-mentored peers. Additionally, racial identity attitudes of immersion/emersion and internalization and identification with academics were also significantly associated with standardized achievement tests and GPA. Policy and practice implications are discussed.

A molecular phylogeny of enteric bacteria and implications for a bacterial species concept

A molecular phylogeny for seven taxa of enteric bacteria (Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Hafnia alvei, Klebsiella oxytoca, Klebsiella pneumoniae, and Serratia plymuthica) was made from multiple isolates per taxa taken from a collection of environmental enteric bacteria. Sequences from five housekeeping genes (gapA, groEL, gyrA, ompA, and pgi) and the 16S rRNA gene were used to infer individual gene trees and were concatenated to infer a composite molecular phylogeny for the species. The isolates from each taxa formed tight species clusters in the individual gene trees, suggesting the existence of 'genotypic' clusters that correspond to traditional species designations. These sequence data and the resulting gene trees and consensus tree provide the first data set with which to assess the utility of the recently proposed core genome hypothesis (CGH). The CGH provides a genetically based approach to applying the biological species concept to bacteria.

Mechanisms of mitochondrial protein import

Mitochondria import most of their proteins from the cytosol. Precursor forms of most matrix proteins as well as some IM and IMS proteins are synthesized on cytoplasmic ribosomes with N-terminal cleavable signal sequences. Many other mitochondrial proteins including IM carrier proteins contain internal targeting sequences. Three multisubunit translocases, one in the OM and two in the IM, participate in the import process. These translocases co-operate with cytosolic chaperones, chaperone-like soluble proteins in the IMS as well as chaperones in the matrix. Insertion of carrier proteins into the IM only requires a membrane potential. On the other hand, translocation of preproteins across the IM into the matrix requires (i) a membrane potential, (ii) GTP hydrolysis, which occurs at the outer side of the IM, and (iii) ATP-dependent interactions occurring at the matrix side. Following import, the cleavable signal sequence of most preproteins is removed in one step by the MPP. In some cases, removal of the signal sequence is achieved in two steps; first by MPP and second by either mitochondrial intermediate peptidase or by IM peptidases. Imported proteins must be folded properly to perform their functions.

Degradation of the kinesin Kip1p at anaphase onset is mediated by the anaphase-promoting complex and Cdc20p

Kip1p of Saccharomyces cerevisiae is a bipolar kinesin in the conserved bimC kinesin subfamily that mediates mitotic spindle-pole separation. Here, we show that Kip1p is regulated immediately after anaphase initiation by its rapid degradation. Degradation required the ubiquitin protein ligase called the anaphase-promoting complex, the anaphase-promoting complex activating protein Cdc20, and a unique 43-aa sequence in Kip1p. Degradation also required import of Kip1p into the nucleus, but occurred independently of spindle association. A mutation that stabilized Kip1p impaired anaphase progression. The timing of degradation suggests that Kip1p functions primarily during spindle assembly and metaphase, and that Kip1p degradation facilitates structural changes in the mitotic spindle as anaphase progresses.

Host and geographical factors influence the thermal niche of enteric bacteria isolated from native Australian mammals

The thermal profiles of 118 bacterial strains, representing six species of the family Enterobacteriaceae, isolated from a variety of native Australian mammals were determined under in vitro conditions. Each of the bacterial species had a unique thermal profile and differed in their minimum or maximum temperature for growth and in their response to changing temperatures. The taxonomic classification of the host from which the bacterial strains were isolated explained a significant amount of the variation in thermal profile among strains of a species. Host effects were detected at all taxonomic levels: order, family, genus, and species. The locality (State or Territory) or climate zone from which the strain was collected explained a significant amount of the variation in the thermal profile of Citrobacter freundii, Enterobacter cloacae and Klebsiella pneumoniae strains. Genetically similar strains, as determined by allozyme profiles, had similar thermal profiles for the bacterial species Hafnia alvei and Escherichia coli. The results of this study indicate that there are potentially many aspects of host biology that may determine the thermal profile of these bacteria.

Qualitative and quantitative differences in cuticular hydrocarbons between laboratory and field colonies of Pogonomyrmex barbatus

Ants held in the laboratory and field ants of the species Pogonomyrmex barbatus have quantitative differences in their cuticular hydrocarbons and a qualitative difference in their methyl-branched hydrocarbons. Laboratory-held workers showed twice the hydrocarbon content as field ants. This difference was mainly due to higher amounts of straight-chain alkanes and methyl-branched alkanes in laboratory ants, whereas the proportion of the alkenes remained the same for both groups. In addition to the absence of some hydrocarbons in the field colonies, one of the methyl-branched hydrocarbons differed in amount and branching pattern between the two groups of ants. Whereas, notable peaks of 2-methylalkanes were identified in ants kept in the laboratory, these compounds could not be identified in ants living in their natural habitat. However, a trace amount of 4-methyltriacontane was found in lieu of the 2-methyltriacontane counterpart in field ants. Possible explanations for both qualitative and quantitative differences are discussed.

New World monkey efficacy trials for malaria vaccine development: critical path or detour?

Neither GMP malaria antigens nor GMP vaccines have been compared for efficacy in monkeys and humans. It is too risky to base categorical (go/no go) development decisions on results obtained using partially characterized (non-GMP) antigens, adjuvants that are too toxic for human use or unvalidated primate models. Such practices will lead to serious errors (e.g. failure to identify and stop flawed efforts, rejection of effective vaccine strategies) and unjustifiable delays. Successful malaria vaccine development will emphasize definitive field trials in populations at risk of malaria to define and improve vaccine efficacy.

J-domain protein, Jac1p, of yeast mitochondria required for iron homeostasis and activity of Fe-S cluster proteins

J-proteins are molecular chaperones with a characteristic domain predicted to mediate interaction with Hsp70 proteins. We have previously isolated yeast mutants of the mitochondrial Hsp70, Ssq1p, in a genetic screen for mutants with altered iron homeostasis. Here we describe the isolation of mutants of the J-domain protein, Jac1p, using the same screen. Mutant jac1 alleles predicted to encode severely truncated proteins (lacking 70 or 152 amino acids) were associated with phenotypes strikingly similar to the phenotypes of ssq1 mutants. These phenotypes include activation of the high affinity cellular iron uptake system and iron accumulation in mitochondria. In contrast to iron accumulation, Fe-S proteins of mitochondria were specifically deficient. In jac1 mutants, like in ssq1 mutants, processing of the Yfh1p precursor protein from intermediate to mature forms was delayed. In the genetic backgrounds used in this study, jac1 null mutants were found to be viable, permitting analysis of genetic interactions. The Deltajac1 Deltassq1 double mutant was more severely compromised for growth than either single mutant, suggesting a synthetic or additive effect of these mutations. Overexpression of Jac1p partially suppressed ssq1 slow growth and vice versa. Similar mitochondrial localization and similar mutant phenotypes suggest that Ssq1p and Jac1p are functional partners in iron homeostasis.

Self-association and precursor protein binding of Saccharomyces cerevisiae Tom40p, the core component of the protein translocation channel of the mitochondrial outer membrane

The precursor protein translocase of the mitochondrial outer membrane (Tom) is a multi-subunit complex containing receptors and a general import channel, of which the core component is Tom40p. Nuclear-encoded mitochondrial precursor proteins are first recognized by surface receptors and then pass through the import channel. The Tom complex has been purified; however, the protein-protein interactions that drive its assembly and maintain its stability have been difficult to study. Here we show that Saccharomyces cerevisiae Tom40p expressed in bacteria and purified to homogeneity associates efficiently with itself. The self-association is very strong and can withstand up to 4 M urea or 1 M salt. The tight self-association does not require the N-terminal segment of Tom40p. Furthermore, purified Tom40p preferentially recognizes the targeting sequence of mitochondrial precursor proteins. Although the binding of the targeting sequence to Tom40p is inhibited by urea concentrations in excess of 1 M, it is moderately resistant to 1 M salt. Simultaneous self-assembly and precursor protein binding suggest that Tom40p contains at least two different domains mediating these processes. The experimental approach described here should be useful for analysing protein-protein interactions involving individual or groups of components of the mitochondrial import machinery.

Novel wax esters and hydrocarbons in the cuticular surface lipids of the red harvester ant, Pogonomyrmex barbatus

The cuticular surface lipids of the red harvester ant, Pogonomyrmex barbatus, were found to contain minor amounts of novel wax esters, in addition to the major components, hydrocarbons. The wax esters ranged in carbon number from C19 to C31 and consisted of esters of both odd- and even-numbered alcohols and acids. Each wax ester with a given carbon number eluted at several different retention times indicating possible methyl branching in either the fatty acid or alcohol moiety, or in both moieties. Each eluting peak of wax esters consisted of a mixture of wax esters of the same carbon number in which the fatty acid moiety ranged from C8 to C18, and the alcohol moiety ranged from C8 to C17. Some wax esters were largely found on the head indicating they may be of a glandular origin. The hydrocarbons consisted of: n-alkanes, C23 to C33; odd-numbered n-alkenes, C27 to C35; and the major components, methyl-branched alkanes, C26 to over C49. Notable components of the methyl-branched alkanes were 2-methyltriacontane, and the novel trimethylalkanes with a single methylene between the first and second branch points, 13,15,19-trimethylhentriacontane and 13,15,21-trimethyltritriacontane.

Distinct roles for two N-terminal cleaved domains in mitochondrial import of the yeast frataxin homolog, Yfh1p

The yeast frataxin homolog (Yfh1p) participates in mitochondrial iron homeostasis. The phenotypic defects of the Delta yfh1 mutant include drastic accumulation of iron in mitochondria and slow growth. The Yfh1p precursor protein contains two N-terminal domains that are sequentially cleaved by the matrix processing peptidase on import into mitochondria, generating the mature protein. We have precisely mapped these two cleavage sites. Mutations blocking the first or the second cleavage of Yfh1p do not interfere with its in vitro import or with its ability to complement phenotypes of the Delta yfh1 mutant strain. Distinct roles have been ascertained for the two cleaved domains of Yfh1p. The first cleaved domain (domain I) is sufficient for in vitro mitochondrial import of a non-mitochondrial passenger protein. However, neither domain I nor other matrix-targeting signals alone can support efficient in vitro import of mature Yfh1p. The second cleaved domain (domain II) is required as a spacer between a targeting signal and mature Yfh1p. Likewise, when Yfh1p constructs lacking domain I or II are expressed in vivo, they fail to attain appreciable steady-state amounts in mitochondria and cannot complement phenotypes of the Delta yfh1 mutant.

A trade-off in task allocation between sensitivity to the environment and response time

Task allocation is the process that adjusts the number of workers in each colony task in response to the environment. There is no central coordination of task allocation; instead workers use local cues from the environment and from other workers to decide which task to perform. We examine two aspects of task allocation: the sensitivity to the environment of task distribution, and the rate of response to environmental changes. We investigate how these two aspects are influenced by: (1) colony size, and (2) behavioral rules used by workers, i.e. how a worker uses cues from the environment and from social interactions with other workers in deciding which task to perform. We show that if workers use social cues in their choice of task, response time decreases with increasing colony size. Sensitivity of task distribution to the environment may decrease or not with colony size, depending on the behavioral rules used by workers. This produces a trade-off in task allocation: short response times can be achieved by increasing colony size, but at the cost of decreased sensitivity to the environment. We show that when a worker's response to social interactions depends on the local environment, sensitivity of task distribution to the environment is not affected by colony size and the trade-off is avoided.

Variations in antibiotic resistance profile in Enterobacteriaceae isolated from wild Australian mammals

We carried out a retrospective analysis of 946 strains of Enterobacteriaceae isolated from wild Australian mammals between 1993 and 1997. The prevalence of resistance to fixed concentrations of 32 antimicrobial agents was determined, and the respective roles that taxonomic family of the host, state of origin and bacterial species play in defining prevalence and range of resistance were investigated. Our results demonstrated a low but widespread prevalence of antimicrobial resistance in wild isolates. Only amikacin, ciprofloxacin, meropenem and gentamicin inhibited growth in all 946 samples. There was extensive variation in the combination of antibiotics to which isolates were resistant, and multiple antibiotic resistance was common. Geographical location and host group significantly influenced the antibiotic resistance profile of an isolate, whereas bacterial species influenced both the resistance profile of an isolate and the number of antibiotics it was resistant to. The role of these factors in determining observed antibiotic resistance profiles suggests that any study measuring resistance in wild isolates should include the broadest possible range of bacterial species, host species and sampling locations. As such, this study provides an important new baseline for future measurements of antibiotic resistance in the Australian environment.

Maturation of frataxin within mammalian and yeast mitochondria: one-step processing by matrix processing peptidase

Friedreich's ataxia is a neurodegenerative disease caused by mutations in the nuclear gene encoding frataxin (FRDA). FRDA is synthesized with an N-terminal signal sequence, which is removed after import into mitochondria. We have shown that FRDA was imported efficiently into isolated mammalian or yeast mitochondria. In both cases, the processing cleavage that removed the N-terminal signal sequence occurred in a single step on import, generating mature products of identical mobility. The processing cleavage could be reconstituted by incubating the FRDA preprotein with rat or yeast matrix processing peptidase (MPP) expressed in Escherichia coli. We used these assays to evaluate the import and processing of an altered form of FRDA containing the disease-causing I154F mutation. No effects on import or maturation of this mutated FRDA were observed. Likewise, no effects were observed on import and maturation of the yeast frataxin homolog (Yfh1p) carrying a homologous I130F mutation. These results argue against the possibility that the I154F mutation interferes with FRDA function via effects on maturation. Other mutations can be screened for effects on FRDA biogenesis as described here, by evaluating import into isolated mitochondria and by testing maturation with purified MPP.

The kinesin-related protein Kip1p of Saccharomyces cerevisiae is bipolar

Kip1p is a mitotic spindle-associated kinesin-related protein in Saccharomyces cerevisiae that participates in spindle pole separation. Here, we define the domain arrangement and polypeptide composition of the Kip1p holoenzyme. Electron microscopy of rotary shadowed Kip1p molecules revealed two globular domains 14 nm in diameter connected by a 73-nm long stalk. When the Kip1p domain homologous to the kinesin motor domain was decorated with an unrelated protein, the diameter of the globular domains at both ends of the stalk increased, indicating that Kip1p is bipolar. Soluble Kip1p isolated from S. cerevisiae cells was homomeric, based on the similarity of the sedimentation coefficients of native Kip1p from S. cerevisiae and Kip1p which was purified after expression in insect cells. The holoenzyme molecular weight was estimated using the sedimentation coefficient and Stokes radius, and was most consistent with a tetrameric composition. Kip1p exhibited an ionic strength-dependent transition in its sedimentation coefficient, revealing a potential regulatory mechanism. The position of kinesin motor-related domains at each end of the stalk may allow Kip1p to cross-link either parallel or antiparallel microtubules during mitotic spindle assembly and pole separation.

The distribution of enteric bacteria from Australian mammals: host and geographical effects

Bacteria of the family Enterobacteriaceae were isolated from 642 mammalian hosts, representing 16 families and 79 species, collected from throughout Australia. Escherichia coli was the most common of the 24 enteric species recovered and represented almost half of the isolates. Association analysis revealed that most other species of bacteria were less likely to be recovered from hosts in which E. coli was present. The composition of the enteric community of a host was found to be determined by both the taxonomic family to which the host belonged and the geographical area from which the host was collected. Hosts collected from the northern areas of Queensland and the Northern Territory had more diverse enteric communities than hosts collected from New South Wales or Western Australia. Hosts of the families Petauridae and Vespertilionidae had more diverse enteric communities than did members of the Macropodidae or Phalangeridae. The probability of occurrence of Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Hafnia alvei, Klebsiella oxytoca and K. pneumoniae in a host was found to vary with respect to host family and/or host locality. The non-random distribution of these species demonstrates the presence of extensive population structure and may suggest the existence of adaptations specific to both the primary and secondary habitats of these enteric bacteria.

The genetic structure of enteric bacteria from Australian mammals

A total of 246 isolates representing five species of the family Enterobacteriaceae, taken from a variety of Australian mammal species, were characterized using multi-locus enzyme electrophoresis. Genome diversity estimates varied significantly among species, with the Klebsiella pneumoniae sample exhibiting the lowest diversity and the Citrobacter freundii sample the highest. Multi-locus linkage disequilibrium estimates revealed that alleles were non-randomly associated in all five species samples, but the magnitude of the estimates differed significantly among species. Escherichia coli had the lowest linkage disequilibrium estimate and Klebisella oxytoca the largest. Molecular analyis of variance was used to determine the extent to which population structure explained the observed genetic variation in a species. Two population levels were defined: the taxonomic family of the host from which the isolate was collected and the geographical locality where the host was collected. The amount of explained variation varied from 0% for K. oxytoca to 22% for K. pneumoniae. Host locality explained a significant amount of the genetic variation in the C. freundii (12%), E. coli (5%), Hafnia alvei (17%) and K. pneumoniae (22%) samples. Host family explained a significant fraction of the variation in E. coli (6%) H. alvei (7%) and K. pneumoniae (20%). Estimates of effective population size for all five species, based on the probability that two randomly chosen isolates will be identical, failed to reveal any relationship between the effective population size and the genetic diversity of a species.

A multisubunit complex of outer and inner mitochondrial membrane protein translocases stabilized in vivo by translocation intermediates

Translocation of nuclear encoded preproteins into the mitochondrial matrix requires the coordinated action of two translocases: one (Tom) located in the outer mitochondrial membrane and the other (Tim) located in the inner membrane. These translocases reversibly cooperate during protein import. We have previously constructed a chimeric precursor (pPGPrA) consisting of an authentic mitochondrial precursor at the N terminus (Delta(1)-pyrroline-5-carboxylate dehydrogenase, pPut) linked, through glutathione S-transferase, to protein A. When pPGPrA is expressed in yeast, it becomes irreversibly arrested during translocation across the outer and inner mitochondrial membranes. Consequently, the two membranes of mitochondria become progressively "zippered" together, forming long stretches in which they are in close contact (Schülke, N., Sepuri, N. B. V., and Pain, D. (1997) Proc. Natl. Acad. Sci. U. S. A. 94, 7314-7319). We now demonstrate that trapped PGPrA intermediates hold the import channels stably together and inhibit mitochondrial protein import and cell growth. Using IgG-Sepharose affinity chromatography of solubilized zippered membranes, we have isolated a multisubunit complex that contains all Tom and Tim components known to be essential for import of matrix-targeted proteins, namely Tom40, Tom22, Tim17, Tim23, Tim44, and matrix-localized Hsp70. Further characterization of this complex may shed light on structural features of the complete mitochondrial import machinery.

The ecological role of bacteriocins in bacterial competition

Bacteriocins are an abundant class of antimicrobial molecules that appear to mediate population dynamics within species. The bacteriocins of Escherichia coli have served as a model for exploring the ecological role of these potent toxins. Studies suggest that colicins provide a competitive edge in nutrient-poor environments and that there might be a trade-off between the costs and benefits of colicin production.

Immunization with SPf66 and subsequent infection with homologous and heterologous Plasmodium falciparum parasites

In an area of intense transmission, a malaria vaccine could reduce infection due to the parasite types represented in the vaccine, but have no detectable effect on the overall frequency of infection if it did not protect against infection with heterologous parasites. These studies were performed to determine whether immunization with SPf66 decreased infection with homologous parasites containing the 11 amino acid peptide from merozoite surface protein-1 (MSP-1) in SPf66, or increased infection due to heterologous parasites containing heterologous (alternative) MSP-1 sequences. Based on this 11 amino acid peptide (YSLFQKEKMVL), three forward primers (S,Q,V) were designed to amplify the MSP-1 sequence present in SPf66, and 3 additional forward primers (G,H,I) to amplify the alternative MSP-1 sequence (YGLFHKEKMIL). This strategy was validated by polymerase chain reaction (PCR) amplification and dideoxy sequencing with 14 cloned laboratory isolates, which demonstrated that each primer amplified one MSP-1 sequence or the other, but not both. The technique was then used to examine filter paper blots from an SPf66 vaccine study of 69 subjects in Saradidi, Kenya. In that study, the prevalence of infection with YSLFQKEKMVL or YGLFHKEKMIL type parasites was unaffected by immunization with SPf66 (based on PCR amplification with the S, Q, V, G, H and I primers, respectively). These results suggest that immunization with SPf66 does not produce a selective effect in vivo. They demonstrate a molecular method to test for selection in vivo as an indirect measure of vaccine efficacy.

Efficacy and safety of atovaquone/proguanil as suppressive prophylaxis for Plasmodium falciparum malaria

Currently recommended prophylactic regimens for Plasmodium falciparum malaria are associated with a high incidence of adverse events and/or suboptimal efficacy. In a double-blind, placebo-controlled, randomized clinical trial in western Kenya, adult volunteers received a treatment course of atovaquone/proguanil hydrochloride (250 mg/100 mg per tablet) to eliminate preexisting infection. Immediately thereafter, subjects were randomized to one of the three prophylactic regimens to receive one atovaquone/proguanil tablet daily (n = 68), two atovaquone/proguanil tablets daily (n = 65), or placebo (n = 65) for 10 weeks. The study endpoint for any subject was the development of parasitemia, evident on blood smear, during prophylaxis. Of the evaluable subjects, all in the low-dose (54 of 54) and high-dose (54 of 54) atovaquone/proguanil groups remained malaria-free during the 10-week prophylaxis period, in contrast to only 48% (26 of 54) in the placebo group (P < .001). Both atovaquone/proguanil prophylactic regimens were as well tolerated as placebo. Thus, atovaquone/proguanil appears to be highly efficacious and safe as prophylaxis for P. falciparum malaria.