Search

In both plants and animals, nucleotide-binding leucine-rich repeat (NLR) immune receptors play critical roles in pathogen recognition and activation of innate immunity. In plants, NLRs recognise pathogen-derived effector proteins and initiate effector-triggered immunity (ETI). However, the molecular mechanisms that link NLR-mediated effector recognition and downstream signalling are not fully understood. By exploiting the well-characterised tomato Prf/Pto NLR resistance complex, we identified the 14-3-3 proteins TFT1 and TFT3 as interacting partners of both the NLR complex and the protein kinase MAPKKKα. Moreover, we identified the helper NRC proteins (NLR-required for cell death) as integral components of the Prf /Pto NLR recognition complex. Notably our studies revealed that TFTs and NRCs interact with distinct modules of the NLR complex and, following effector recognition, dissociate facilitating downstream signalling. Thus, our data provide a mechanistic link between activation of immune receptors and initiation of downstream signalling cascades.

Multiple sclerosis (MS) is a complex disease of the CNS thought to require an environmental trigger. Gut dysbiosis is common in MS, but specific causative species are unknown. To address this knowledge gap, we used sensitive and quantitative PCR detection to show that people with MS were more likely to harbor and show a greater abundance of epsilon toxin-producing (ETX-producing) strains of C. perfringens within their gut microbiomes compared with individuals who are healthy controls (HCs). Isolates derived from patients with MS produced functional ETX and had a genetic architecture typical of highly conjugative plasmids. In the active immunization model of experimental autoimmune encephalomyelitis (EAE), where pertussis toxin (PTX) is used to overcome CNS immune privilege, ETX can substitute for PTX. In contrast to PTX-induced EAE, where inflammatory demyelination is largely restricted to the spinal cord, ETX-induced EAE caused demyelination in the corpus callosum, thalamus, cerebellum, brainstem, and spinal cord, more akin to the neuroanatomical lesion distribution seen in MS. CNS endothelial cell transcriptional profiles revealed ETX-induced genes that are known to play a role in overcoming CNS immune privilege. Together, these findings suggest that ETX-producing C. perfringens strains are biologically plausible pathogens in MS that trigger inflammatory demyelination in the context of circulating myelin autoreactive lymphocytes.

To promote the financial capabilities of student loan borrowers, practitioners must understand the experiences and needs of borrowers across the life course. A national survey ( n = 1,874) conducted by MIT AgeLab explored perceived loan-related effects across the life course and sources of advice for borrowers. Across age groups, repaying student loans had most regularly imposed negative perceived effects on multiple domains of borrowers’ financial well-being. Younger borrowers reported more negative perceived effects of loans across domains, whereas older borrowers reported fewer negative perceived effects. Few participants had sought professional advice about student loan repayment, although younger borrowers were more likely to have sought loan-related advice in general; perceived levels of helpfulness of advice and comfort consulting with contacts were mixed. Financial social work is uniquely situated to act as a resource for multiple generations of student loan borrowers and their families.

Financial self-efficacy is associated with positive financial behaviors. This study investigated factors associated with financial self-efficacy among student loan borrowers based on original data collected through an online national survey of student loan borrowers between age 25 and 75. Results revealed that perceived student loan literacy prior to accruing higher education debt was significantly associated with current financial self-efficacy, while general financial literacy during repayment did not appear to be correlated with financial self-efficacy. This study draws on social cognitive theory to suggest that student loan literacy prior to accruing debt may act as a mastery experience, improving financial self-efficacy when the repayment period arrives. Given the increasing prevalence of student loans across all generations, this study underscores the need for early education and mentoring from financial professionals about student loan borrowing.

As college costs rise in the United States, many parents are forced to make difficult decisions about how to pay for their children’s higher education. Stress and conflict accompany financial issues and play a role in the financial picture for many families. Using Hill’s (Hill, Social casework 39:139–150, 1958) ABC-X model of family stress as a framework, this study describes results of a national survey of parents contributing to student loan payments for their child’s education and explores how this experience may play a role in familial conflict. Findings suggest marked gender differences in the relationship between contribution reason and the experience of conflict. Results also carry implications for financial professionals, suggesting a need for family-focused and gender-conscious financial education both before and during the student loan repayment process.

With student loan borrowing becoming an increasingly common experience in U.S. households, it is crucial to understand the interpersonal manifestation of education debt within family systems. This study sought to understand how accruing and repaying student loan debt for one’s own higher education relates to family dynamics and communication within families. Leveraging Family Communication Patterns Theory, this study asked: How do student loan borrowers describe loan-related family communication patterns prior to loan accrual and during the repayment period? Utilizing qualitative and quantitative data collected through a concurrent nested mixed methods study design, findings from this study profile family communication typologies leading up to, and during, student loan repayment. Study findings suggest that the ways in which families communicate about student loans prior to loan accrual and during repayment (a) relate to family financial socialization processes and (b) play at least a partial role in how they experience student loans as part of their overall family dynamics. This study proposes a model of loan-related family communication dynamics and offers implications for future scholarship and practice.

During the ongoing spread of COVID-19 and its variants, older adults remain an age group particularly at-risk for poorer health outcomes, not only related to infection with COVID-19, but also due to disruptions in access to preventive health services, including routine vaccination. In the U.S., older adults have generally had high uptake of the COVID-19 vaccines, but differences persist regionally and between older adults from minority racial backgrounds. The purpose of the following study was to better understand how groups of Black and white-identifying adults ages 65+ described the impact of the COVID-19 pandemic on their preventive health behavior and healthcare use, including what contributed to their decision to receive or not receive a primary COVID-19 vaccination series. Seventy-five participants were purposively sampled and stratified into virtual focus groups based on their age, racial identity, vaccination status, and relationship to a local community. Findings leverage data from a pre-group questionnaire and focus groups conducted in November 2021. Analyses revealed differences among sub-groups about how the pandemic has impacted their relationship to their local community. Participants described the extent of the pandemic’s disruption to their healthcare access, including modifications to in-person care, use of telehealth, and engagement in new health behaviors. Decision-making related to the COVID-19 vaccine differed among the vaccinated and unvaccinated and white and Black-identifying groups, including factors related to interpersonal and systemic trust, independent research, and bodily autonomy. Implications of this research for public health and practitioners working with older adults will be discussed.

Reduced expression of 2'-3′-cyclic nucleotide 3′-phosphodiesterase (Cnp) in humans and mice causes white matter inflammation and catatonic signs. These consequences are experimentally alleviated by...

Costs of caregiving go beyond physical, mental, and emotional; the financial costs are astronomical. On average, family caregivers spend 26% of their income on caregiving (AARP 2021). As the need for family caregivers grows due to longer lifespans (AARP 2020), incorporating the topic of caregiving into financial planning for longevity conversations becomes increasingly necessary. Drawing on data from the MIT AgeLab Caregiver Panel, a research panel of over 1400 family caregivers, and from the MIT AgeLab Preparing for Longevity Advisory Network, a research panel of over 900 financial professionals, this presentation will describe mixed methods research findings that highlight caregivers’ and financial professionals’ attitudes and perceptions toward caregiving as a topic within client-advisor conversations. Results demonstrate that many caregivers wish they had financially planned for the costs of caregiving more than they did. However, caregivers rarely turn to their financial advisors for support; many perceive their value to be strictly financial and are unaware of their advisors’ ability to support them. Despite caregivers’ doubts, most financial professionals feel equipped and willing to have caregiving-related conversations with clients. Additionally, while over three-quarters of financial professionals reported making referrals to outside resources for caregiving-related support, some critical avenues – including social workers and therapists, support groups, and respite care providers – were underutilized. Implications of these findings for caregivers and professionals of various industries will also be discussed.

For many family caregivers, COVID-19 has presented new obstacles to providing elder-care while balancing additional responsibilities such as work or childcare. Three survey waves explored impacts over the course of the pandemic. Family caregivers demonstrated resilience, taking a variety of measures to care for and protect family; caregivers were also more confident in their ability to protect loved ones age 60+ from contracting COVID-19 than non-caregivers. However, COVID-19’s toll on caregivers was evident. Caregivers reported higher personal burnout than non-caregivers, and across all three survey waves, consistently reported greater degrees of worry in regards to COVID-19 in general, as well as its impacts on domains including the health and wellbeing of themselves and family members, and near and far term finances. This presentation will highlight how caregivers’ perceptions and impacts of COVID-19 have evolved over the course of the pandemic, and implications of these findings for life tomorrow.

In the midst of the COVID-19 pandemic, many caregivers have been tasked with a unique role; not only to keep themselves safe and healthy, but also to protect and find new ways to aid their care recipients, many of whom are older adults at relatively high risk for severe complications from COVID-19. These challenging circumstances have driven caregivers to quickly adapt as they continue to manage their personal lives and caregiving responsibilities. Utilizing three waves of survey data from the MIT AgeLab Caregiver Panel, this presentation will examine the attitudes, experiences and worries of family caregivers at several time points along the course of the COVID-19 pandemic, as well as caregivers’ preparations and coping behaviors along the way. Differences between caregiving situations will also be discussed.

Hippocampal sharp wave ripples (SWRs) represent irregularly occurring synchronous neuronal population events that are observed during phases of rest and slow wave sleep. SWR activity that follows learning involves sequential replay of training-associated neuronal assemblies and is critical for systems level memory consolidation. SWRs are initiated by CA2 or CA3 pyramidal cells and require initial excitation of CA1 pyramidal cells as well as participation of parvalbumin (PV) expressing fast spiking (FS) inhibitory interneurons. These interneurons are relatively unique in that they represent the major neuronal cell type known to be surrounded by perineuronal nets (PNNs), lattice like structures composed of a hyaluronin backbone that surround the cell soma and proximal dendrites. Though the function of the PNN is not completely understood, previous studies suggest it may serve to localize glutamatergic input to synaptic contacts and thus influence the activity of ensheathed cells. Noting that FS PV interneurons impact the activity of pyramidal cells thought to initiate SWRs, and that their activity is critical to ripple expression, we examine the effects of PNN integrity on SWR activity in the hippocampus. Extracellular recordings from the stratum radiatum of horizontal murine hippocampal hemisections demonstrate SWRs that occur spontaneously in CA1. As compared to vehicle, pretreatment (120 min) of paired hemislices with hyaluronidase, which cleaves the hyaluronin backbone of the PNN, decreases PNN integrity and increases SWR frequency. Pretreatment with chondroitinase, which cleaves PNN side chains, also increases SWR frequency. Together, these data contribute to an emerging appreciation of extracellular matrix as a regulator of neuronal plasticity and suggest that one function of mature perineuronal nets could be to modulate the frequency of SWR events.

Previous research shows that social isolation is associated with increased mortality rates among older adults. However, in the face of the novel coronavirus (COVID-19), social distancing was prescribed as a potentially lifesaving measure, particularly for older adults. In this session, MIT AgeLab researchers will present findings from a mixed methods study with the MIT AgeLab 85+ Lifestyle Leaders, a panel study of octogenarians and nonagenarians that began in September 2015. In March 2020, AgeLab researchers began conducting a series of telephone interviews (n=15) with Lifestyle Leaders and collected quantitative data via an online survey (n=25). Together, the interviews and survey inquired about Lifestyle Leaders’ attitudes and behaviors related to COVID-19, as well as their uses of technology throughout the crisis. Findings suggest that fears about the impacts of coronavirus transcended multiple domains of the Lifestyle Leaders’ lives, including their physical, socioemotional, and financial wellbeing. Lifestyle Leaders were asked about functional and emotional repercussions of social distancing and other precautions they had taken to reduce the spread of COVID-19 and to protect themselves from contracting the virus. Special attention was paid to differences in lived experiences of the COVID-19 crisis among Lifestyle Leaders who were living independently versus those who were living in assisted living or continuing care retirement communities. Findings from this study suggest that socially-connected emergency preparedness measures will become increasingly important for the growing number of octogenarians and nonagenarians.

Reduced expression of 2'-3'-cyclic nucleotide 3'-phosphodiesterase (

A correction to this paper has been published: https://doi.org/10.1007/s10834-021-09772-6

Previous research demonstrates that student loan debt disproportionately affects women and is being repaid increasingly by older adults. Utilizing data collected through a mixed methods study at the MIT AgeLab (involving focus groups and a large national survey), we examine the impacts of repaying student loans on older women’s financial wellbeing. Findings focus on multiple areas, including the timing in which older women repaying student loans were able to pay down other debts, change jobs, get married, and pursue further education. Analysis also revealed that student loans impacted the amount that 63% of older women in the study were able to contribute to their retirement savings. Findings from this study suggest that repaying student loan debt for oneself and/or a family member can compromise older women’s near-term and longer-term financial being. Policy reforms are needed to support older women repaying student loans.

The repercussions of novel coronavirus (COVID-19) within the United States and across the globe are vast. Researchers at the MIT AgeLab conducted a national online survey (N=1200) related to COVID-19 in March 2020 with the goal of exploring participants’ COVID-19-related attitudes, hygiene and consumer behaviors, and their use of technology to work, make purchases, stay informed, and stay socially connected. In this presentation, AgeLab researchers will describe findings among a sub-population of study participants deemed to be at highest health risks for the virus: adults ages 60 and over. Findings demonstrate that the largest group of participants stayed informed about COVID-19 primarily through online sources. As a result of the virus, most had made changes to their health and hygiene practices, including implementing social distancing measures, and the majority had changed at least one of their purchasing behaviors, most often buying more products than usual online. Second only to participants’ physical health concerns related to COVID-19 were their financial health concerns, both related to near-term finances and longer-term financial goals. From this study, policy and practice implications emerge across public, private, and non-profit sectors that, taken together, can prepare older adults and their loved ones to survive and thrive during global emergencies.

Currently, approximately 44 million people in the United States carry the weight of over 1.4 trillion dollars of student loan debt. As the cost of education continues to rise, the decision of taking on student loans is increasingly a family decision rather than an individual one. While the majority of research focuses on younger borrowers, little research has been done to understand the experiences of parents and grandparents taking on student loans for a loved one. In order to financially and emotionally manage this burden, borrowers may benefit from support from their social networks, including family and friends. For many, navigating these difficult conversations presents a challenge of its own. This presentation will spotlight an MIT AgeLab mixed methods study about how student loan borrowers between the ages of 51 and 75 experience and manage their student loans within family systems and how these loans may impact family dynamics. Data were collected through focus groups and a national survey. Preliminary findings suggest that older borrowers demonstrate several distinct communication typologies within their families in regards to finances, particularly regarding student loan accrual and repayment. Each of the four primary communication styles regarding loans impact borrowers’ financial and emotional wellbeing throughout the life course, as well as perceived relationship dynamics. Moreover, older borrowers are more likely to report family conflict if student loans are less frequently discussed with family members. Findings also suggest strategies to help parents and grandparents facilitate conversations abound student loans based on their unique family communication styles.

Hippocampal sharp wave ripples (SWRs) represent irregularly occurring synchronous neuronal population events that are observed during phases of rest and slow wave sleep. SWR activity that follows learning involves sequential replay of training-associated neuronal assemblies and is critical for systems level memory consolidation. SWRs are initiated by CA2 or CA3 pyramidal cells and require initial excitation of CA1 pyramidal cells as well as subsequent participation of parvalbumin (PV) expressing fast spiking (FS) inhibitory interneurons. These interneurons are relatively unique in that they represent the major neuronal cell type known to be surrounded by perineuronal nets (PNNs), lattice like structures composed of a hyaluronin backbone that surround the cell soma and proximal dendrites. Though the function of the PNN is not completely understood, previous studies suggest it may serve to localize glutamatergic input to synaptic contacts and thus influence the activity of ensheathed cells. Noting that FS PV interneurons impact the activity of pyramidal cells thought to initiate SWRs, and that their activity is critical to ripple expression, we examine the effects of PNN integrity on SWR activity in the hippocampus. Extracellular recordings from the stratum radiatum of 490 micron horizontal murine hippocampal hemisections demonstrate SWRs that occur spontaneously in CA1. As compared to vehicle, pretreatment (120 min) of paired hemislices with hyaluronidase, which cleaves the hyaluronin backbone of the PNN, decreases PNN integrity and increases SWR frequency. Pretreatment with chondroitinase, which cleaves PNN side chains, also increases SWR frequency. Together, these data contribute to an emerging appreciation of extracellular matrix as a regulator of neuronal plasticity and suggest that one function of mature perineuronal nets could be to modulate the frequency of SWR events.

Saving for retirement and the ability to provide care for a loved one can be dramatically affected by student loan debt. Currently, approximately 44 million people of all ages in the United States carry the weight of over 1.4 trillion dollars of student loan debt. Student loan borrowers of all ages may experience lower financial preparedness for retirement as well as decreased ability to provide care for family members, including aging parents. While older adults hold a relatively small proportion of student loans, they are the fastest growing subset of student loan borrowers and have disproportionately high rates of student loan defaults. As a result of their defaults, the Social Security retirement benefits of Americans ages 65 and older experienced a 500% increase in offsets over the last decade. This presentation will spotlight an MIT AgeLab mixed methods study about how student loan borrowers between the ages of 51 and 75 experience student loans within family systems and perceive and prioritize longevity planning in light of their student loans. Data collected for this study include focus groups and a large national survey. Preliminary findings suggest that for older borrowers, student loans are generally one of several financial constraints that can inform spending and saving decisions. For most, student loan payments are regarded as stunting overall retirement savings while the minority regard the two separately. Older borrowers also tend to have increased financial and familial responsibilities, including caring for aging parents, that compete for borrowers’ limited financial and temporal resources.

Introduction: Our previous work demonstrates that resveratrol, a naturally occurring polyphenol, protects against cerebral ischemia when administered 2 or 14 days prior to injury. Resveratrol activates Sirt1, an NAD + -dependent deacylase that regulates cellular metabolism. It has been postulated that neuronal Sirt1 directly mediates this neuroprotection but it remains to be empirically tested. Objective: The objective of this study was to generate an inducible, neuronal-specific Sirt1 knockout mouse and determine whether neuronal Sirt1 is necessary for resveratrol-induced ischemic tolerance. Methods: Twenty to twenty-five gram neuronal-specific Sirt1 knockout mice (Sirt1neu-/-) and WTs were induced with tamoxifen. Mice were randomized for 1) western blot; 2) resveratrol preconditioning (RPC; 10 mg/kg resveratrol i.p.) or vehicle (1.5% DMSO; 0.9% saline) treatment 2 days prior to 60 minute middle cerebral artery occlusion (MCAo); 3) untargeted primary metabolomics by GC-TOF-MS; or 4) transcription factor activation profiling. Twenty-four hours following MCAo, neurological score was used to assess functional outcome and infarct volume was quantified by TTC staining. Results: Tamoxifen treatment removed WT Sirt1 protein from major brain regions but not from heart (Figure 1A, n=3). In WT, RPC reduced infarct volume by 43.7% and improved neurological score by nearly 3 points, however these effects were lost in Sirt1neu-/- (Figure 1B, n=5-9). Compared to WT, metabolic profiles from Sirt1neu-/- displayed significantly altered glycolysis metabolites (Figure 1C, n=8). Activation of hypoxia inducible factor (HIF) was reduced by 48% in Sirt1neu-/- (Figure 1D, n=3). Conclusions: We generated and utilized an inducible, neuronal-specific knockout mouse to demonstrate that neuronal Sirt1 specifically is required for RPC-induced ischemic tolerance. Additionally, Sirt1 regulates glycolysis in the brain, possibly through its interaction with HIF.

Cytoplasmic recognition of pathogen virulence effectors by plant NB-LRR proteins leads to strong induction of defence responses termed effector triggered immunity (ETI). In tomato, a protein complex containing the NB-LRR protein Prf and the protein kinase Pto confers recognition of the Pseudomonas syringae effectors AvrPto and AvrPtoB. Although structurally unrelated, AvrPto and AvrPtoB interact with similar residues in the Pto catalytic cleft to activate ETI via an unknown mechanism. Here we show that the Prf complex is oligomeric, containing at least two molecules of Prf. Within the complex, Prf can associate with Pto or one of several Pto family members including Fen, Pth2, Pth3, or Pth5. The dimerization surface for Prf is the novel N-terminal domain, which also coordinates an intramolecular interaction with the remainder of the molecule, and binds Pto kinase or a family member. Thus, association of two Prf N-terminal domains brings the associated kinases into close promixity. Tomato lines containing Prf complexed with Pth proteins but not Pto possessed greater immunity against P. syringae than tomatoes lacking Prf. This demonstrates that incorporation of non-Pto kinases into the Prf complex extends the number of effector proteins that can be recognized.

Tomato Prf encodes a nucleotide-binding domain shared by Apaf-1, certain R proteins, and CED-4 fused to C-terminal leucine-rich repeats (NBARC-LRR) protein that is required for bacterial immunity to Pseudomonas syringae and sensitivity to the organophosphate fenthion. The signaling pathways involve two highly related protein kinases. Pto kinase mediates direct recognition of the bacterial effector proteins AvrPto or AvrPtoB. Fen kinase is required for fenthion sensitivity and recognition of bacterial effectors related to AvrPtoB. The role of Pto and its association with Prf has been characterized but Fen is poorly described. We show that, similar to Pto, Fen requires N-myristoylation and kinase activity for signaling and interacts with the N-terminal domain of Prf. Thus, the mechanisms of activation of Prf by the respective protein kinases are similar. Prf–Fen interaction is underlined by coregulatory mechanisms in which Prf negatively regulates Fen, most likely by controlling kinase activity. We further characterized negative regulation of Prf by Pto, and show that regulation is mediated by the previously described negative regulatory patch. Remarkably, the effectors released negative regulation of Prf in a manner dependent on Pto kinase activity. The data suggest a model in which Prf associates generally with Pto-like kinases in tightly regulated complexes, which are activated by effector-mediated disruption of negative regulation. Release of negative regulation may be a general feature of activation of NBARC-LRR proteins by cognate effectors.

The Pto gene of tomato (Solanum lycopersicum) confers specific recognition of the unrelated bacterial effector proteins AvrPto and AvrPtoB. Pto resides in a constitutive molecular complex with the nucleotide binding site-leucine rich repeats protein Prf. Prf is absolutely required for specific recognition of both effectors. Here, using stable transgenic lines, we show that expression of Pto from its genomic promoter in susceptible tomatoes was sufficient to complement recognition of Pseudomonas syringae pv. tomato (Pst) bacteria expressing either avrPto or avrPtoB. Pto kinase activity was absolutely required for specific immunity. Expression of the Pto N-myristoylation mutant, pto(G2A), conferred recognition of Pst (avrPtoB), but not Pst (avrPto), although bacterial growth in these lines was intermediate between resistant and susceptible lines. Overexpression of pto(G2A) complemented recognition of avrPto. Transgenic tomato plants overexpressing wild-type Pto exhibited constitutive growth phenotypes, but these were absent in lines overexpressing pto(G2A). Therefore, Pto myristoylation is a quantitative factor for effector recognition in tomato, but is absolutely required for overexpression phenotypes. Native expression of Pto in the heterologous species Nicotiana benthamiana did not confer resistance to P. syringae pv. tabaci (Pta) expressing avrPto or avrPtoB, but recognition of both effectors was complemented by Prf co-expression. Thus, specific resistance conferred solely by Pto in N. benthamiana is an artefact of overexpression. Finally, pto(G2A) did not confer recognition of either avrPto or avrPtoB in N. benthamiana, regardless of the presence of Prf. Thus, co-expression of Prf in N. benthamiana complements many but not all aspects of normal Pto function.

Immunity in tomato (Solanum lycopersicum) to Pseudomonas syringae bacteria expressing the effector proteins AvrPto and AvrPtoB requires both Pto kinase and the NBARC-LRR (for nucleotide binding domain shared by Apaf-1, certain R gene products, and CED-4 fused to C-terminal leucine-rich repeats) protein Prf. Pto plays a direct role in effector recognition within the host cytoplasm, but the role of Prf is unknown. We show that Pto and Prf are coincident in the signal transduction pathway that controls ligand-independent signaling. Pto and Prf associate in a coregulatory interaction that requires Pto kinase activity and N-myristoylation for signaling. Pto interacts with a unique Prf N-terminal domain outside of the NBARC-LRR domain and resides in a high molecular weight recognition complex dependent on the presence of Prf. In this complex, both Pto and Prf contribute to specific recognition of AvrPtoB. The data suggest that the role of Pto is confined to the regulation of Prf and that the bacterial effectors have evolved to target this coregulatory molecular switch.

Crack turning or delamination behavior of AA 2050-T87 and AA 7050-T7451 ESE(T) and hourglass coupons under cyclic fatigue conditions is presented. Fatigue crack growth rate curves, fracture surface examinations, and the preferred manner of crack growth for each alloy are discussed in an effort to better understand fatigue crack growth behavior of aluminum-lithium alloys in structural components under service conditions.

Novoe Vremia (New Times), one of Russia’s leading newspapers, acquired a reputation as anti‐Jewish or Judeophobic in the late 1870s and retained this distinction in later years. But in the course o...

How generalist parasites with wide host ranges can evolve is a central question in parasite evolution. Albugo candida is an obligate biotrophic parasite that consists of many physiological races that each specialize on distinct Brassicaceae host species. By analyzing genome sequence assemblies of five isolates, we show they represent three races that are genetically diverged by ∼1%. Despite this divergence, their genomes are mosaic-like, with ∼25% being introgressed from other races. Sequential infection experiments show that infection by adapted races enables subsequent infection of hosts by normally non-infecting races. This facilitates introgression and the exchange of effector repertoires, and may enable the evolution of novel races that can undergo clonal population expansion on new hosts. We discuss recent studies on hybridization in other eukaryotes such as yeast, Heliconius butterflies, Darwin's finches, sunflowers and cichlid fishes, and the implications of introgression for pathogen evolution in an agro-ecological environment. DOI: http://dx.doi.org/10.7554/eLife.04550.001, eLife digest Many microorganisms live as parasites inside another living organism, and gain nutrients at their host's expense. Plants and animals have immune systems that serve to protect against this kind of exploitation, but successful parasites have evolved ways to avoid detection by their hosts' immune systems, and/or to suppress hosts' defence mechanisms. Parasites often avoid detection by releasing molecules that interfere with specific aspects of a host's immune system. The same molecules, however, can be recognised by the immune systems of other species and trigger defence responses that eradicate the parasites; this explains why most parasites can colonise only a limited number of host species. It is less clear how parasites evolve to become ‘generalists’ that can infect many host species. However, some generalist parasites have several distinct subgroups—each of which is specialised to infect a limited number of host species. Albugo candida is a generalist parasite that infects over 200 plant species, including mustard greens, oilseed and vegetable crops. Even though its looks and its lifestyle resemble those of a fungus, A. candida is actually an oomycete: a group of organisms that are more closely related to golden-brown algae than they are to fungi. About 24 subgroups (or ‘races’) of this generalist parasite have been identified to date, but it remains unclear how these subgroups have evolved. McMullan, Gardiner et al. tested different isolates of A. candida—four from southeast England and one from western Canada—which had been collected from different plant species and confirmed that each could only infect a narrow range of plant hosts. Next, the genome sequences of these five A. candida strains were assembled and compared. This analysis revealed that the five strains represented three distinct subgroups (or races) of A. candida. Moreover, some parts of one subgroup's genome were most similar to those found in a second subgroup; and other parts were more like sections of the third subgroup's genome. McMullan, Gardiner et al. point out that such ‘mosaic-like genomes’ indicate crossbreeding between the different subgroups. But as A. candida must infect a plant in order to reproduce, and different subgroups infect different host plants, how can different subgroups meet in order to mate and reproduce? In answer to this question, McMullan, Gardiner et al. showed that a plant that is infected with one subgroup of A. candida becomes susceptible to co-infection with other subgroups, including those that couldn't normally infect this plant species on their own. These findings reveal that generalist parasites can therefore evolve new subgroups via a mechanism that is similar to the way that crossbreeding (or hybridization) between existing species can lead to the evolution of new species. DOI: http://dx.doi.org/10.7554/eLife.04550.002

Does the creation of a deemed servant-master relationship, between pilot and ship-owner or master through section 76 (2) of the National Ports Act (hereafter the NPA); accurately reflect the de facto relationship in which the parties stand? Can the provision's importation of the doctrine of vicarious liability and consequent foisting of liability on the ship-owner be defined as logical, just and practical? It will be argued after having had recourse to the manner in which these roles have come to be defined and understood in South African labour jurisprudence, the governing law, respective positions occupied by ship-owner and port authority, broad-based considerations of policy, and key tenets of the rationale underpinning the concept of vicarious liability; that the answer to the above-raised questions is are sounding no. In addition, the writer will submit that the privatisation of pilotage services presents a solution, alternate to the irrational imposition of the doctrine of vicarious liability, which is palatable to government, ship-owning interests and pilot. a) Introduction Typically, claims arising from consequences of pilot error satisfy the definition of a 'maritime claim' contained in s 1 (1) (e) and s 1 (1) (l) of the Admiralty Jurisdiction Regulation Act. As a result thereof; a South African court sitting in admiralty has jurisdiction to hear such claims. As to the identification of the appropriate law; s 6 (2) dictates that South African statute, if relevant, trumps pre-existing English admiralty law and is the law to be applied. The NPA, chiefly through sections 75 and 76, regulates the extent of the pilot's liability for his/her acts or omissions whilst a vessel is under compulsory pilotage. Thus, the Act is applicable to disputes arising from pilot error, before a South African court sitting in admiralty.

Individuals suffering from substance-use disorders develop strong associations between the drug's rewarding effects and environmental cues, creating powerful, enduring triggers for relapse. We found that dephosphorylated, nuclear histone deacetylase 5 (HDAC5) in the nucleus accumbens (NAc) reduced cocaine reward-context associations and relapse-like behaviors in a cocaine self-administration model. We also discovered that HDAC5 associates with an activity-sensitive enhancer of the Npas4 gene and negatively regulates NPAS4 expression. Exposure to cocaine and the test chamber induced rapid and transient NPAS4 expression in a small subpopulation of FOS-positive neurons in the NAc. Conditional deletion of Npas4 in the NAc significantly reduced cocaine conditioned place preference and delayed learning of the drug-reinforced action during cocaine self-administration, without affecting cue-induced reinstatement of drug seeking. These data suggest that HDAC5 and NPAS4 in the NAc are critically involved in reward-relevant learning and memory processes and that nuclear HDAC5 limits reinstatement of drug seeking independent of NPAS4.

The major virulence strategy of phytopathogenic bacteria is to secrete effector proteins into the host cell to target the immune machinery. AvrPto and AvrPtoB are two such effectors from Pseudomonas syringae, which disable an overlapping range of kinases in Arabidopsis and Tomato. Both effectors target surface-localized receptor-kinases to avoid bacterial recognition. In turn, tomato has evolved an intracellular effector-recognition complex composed of the NB-LRR protein Prf and the Pto kinase. Structural analyses have shown that the most important interaction surface for AvrPto and AvrPtoB is the Pto P+1 loop. AvrPto is an inhibitor of Pto kinase activity, but paradoxically, this kinase activity is a prerequisite for defense activation by AvrPto. Here using biochemical approaches we show that disruption of Pto P+1 loop stimulates phosphorylation in trans, which is possible because the Pto/Prf complex is oligomeric. Both P+1 loop disruption and transphosphorylation are necessary for signalling. Thus, effector perturbation of one kinase molecule in the complex activates another. Hence, the Pto/Prf complex is a sophisticated molecular trap for effectors that target protein kinases, an essential aspect of the pathogen's virulence strategy. The data presented here give a clear view of why bacterial virulence and host recognition mechanisms are so often related and how the slowly evolving host is able to keep pace with the faster-evolving pathogen., Author Summary The bacteria Pseudomonas syringae is a pathogen of many crop species and one of the model pathogens for studying plant and bacterial arms race coevolution. In the current model, plants perceive bacteria pathogens via plasma membrane receptors, and recognition leads to the activation of general defenses. In turn, bacteria inject proteins called effectors into the plant cell to prevent the activation of immune responses. AvrPto and AvrPtoB are two such proteins that inhibit multiple plant kinases. The tomato plant has reacted to these effectors by the evolution of a cytoplasmic resistance complex. This complex is compromised of two proteins, Prf and Pto kinase, and is capable of recognizing the effector proteins. How the Pto kinase is able to avoid inhibition by the effector proteins is currently unknown. Our data shows how the tomato plant utilizes dimerization of resistance proteins to gain advantage over the faster evolving bacterial pathogen. Here we illustrate that oligomerisation of Prf brings into proximity two Pto kinases allowing them to avoid inhibition by the effectors by transphosphorylation and to activate immune responses.

The evolutionary importance of hybridization and introgression has long been debated. Hybrids are usually rare and unfit, but even infrequent hybridization can aid adaptation by transferring beneficial traits between species. Here we use genomic tools to investigate introgression in Heliconius, a rapidly radiating genus of neotropical butterflies widely used in studies of ecology, behaviour, mimicry and speciation. We sequenced the genome of Heliconius melpomene and compared it with other taxa to investigate chromosomal evolution in Lepidoptera and gene flow among multiple Heliconius species and races. Among 12, 669 predicted genes, biologically important expansions of families of chemosensory and Hox genes are particularly noteworthy. Chromosomal organization has remained broadly conserved since the Cretaceous period, when butterflies split from the Bombyx (silkmoth) lineage. Using genomic resequencing, we show hybrid exchange of genes between three co-mimics, Heliconius melpomene, Heliconius timareta and Heliconius elevatus, especially at two genomic regions that control mimicry pattern. We infer that closely related Heliconius species exchange protective colour-pattern genes promiscuously, implying that hybridization has an important role in adaptive radiation. © 2012 Macmillan Publishers Limited.

Biotrophic eukaryotic plant pathogens require a living host for their growth and form an intimate haustorial interface with parasitized cells. Evolution to biotrophy occurred independently in fungal rusts and powdery mildews, and in oomycete white rusts and downy mildews. Biotroph evolution and molecular mechanisms of biotrophy are poorly understood. It has been proposed, but not shown, that obligate biotrophy results from (i) reduced selection for maintenance of biosynthetic pathways and (ii) gain of mechanisms to evade host recognition or suppress host defence. Here we use Illumina sequencing to define the genome, transcriptome, and gene models for the obligate biotroph oomycete and Arabidopsis parasite, Albugo laibachii. A. laibachii is a member of the Chromalveolata, which incorporates Heterokonts (containing the oomycetes), Apicomplexa (which includes human parasites like Plasmodium falciparum and Toxoplasma gondii), and four other taxa. From comparisons with other oomycete plant pathogens and other chromalveolates, we reveal independent loss of molybdenum-cofactor-requiring enzymes in downy mildews, white rusts, and the malaria parasite P. falciparum. Biotrophy also requires “effectors” to suppress host defence; we reveal RXLR and Crinkler effectors shared with other oomycetes, and also discover and verify a novel class of effectors, the “CHXCs”, by showing effector delivery and effector functionality. Our findings suggest that evolution to progressively more intimate association between host and parasite results in reduced selection for retention of certain biosynthetic pathways, and particularly reduced selection for retention of molybdopterin-requiring biosynthetic pathways. These mechanisms are not only relevant to plant pathogenic oomycetes but also to human pathogens within the Chromalveolata., Author Summary Plant pathogens that cannot grow except on their hosts are called obligate biotrophs. How such biotrophy evolves is poorly understood. In this study, we sequenced the genome of the obligate biotroph white rust pathogen (Albugo laibachii, Oomycota) of Arabidopsis. From comparisons with other oomycete plant pathogens, diatoms, and the human pathogen Plasmodium falciparum, we reveal a loss of important metabolic enzymes. We also reveal the appearance of defence-suppressing “effectors”, some carrying motifs known from other oomycete effectors, and discover and experimentally verify a novel class of effectors that share a CHXC motif within 50 amino acids of the signal peptide cleavage site. Obligate biotrophy involves an intimate association within host cells at the haustorial interface (where the parasite penetrates the host cell's cell wall), where nutrients are acquired from the host and effectors are delivered to the host. We found that A. laibachii, like Hyaloperonospora arabidopsidis and Plasmodium falciparum, lacks molybdopterin-requiring biosynthetic pathways, suggesting relaxed selection for retention of, or even selection against, this pathway. We propose that when defence suppression becomes sufficiently effective, hosts become such a reliable source of nutrients that a free-living phase can be lost. These mechanisms leading to obligate biotrophy and host specificity are relevant not only to plant pathogenic oomycetes but also to human pathogens.

Infections and Defense Bacteria secrete effectors to suppress immunity in plant and animal hosts resulting in an evolutionary arms race between bacteria and their eukaryotic hosts. One important aspect of plant immunity against bacteria is based on disease resistance protein complexes, which recognize specific bacterial effectors and activate signal transduction. A strain of the bacteria Pseudomonas that infects tomato and Arabidopsis plants injects its effector protein, AvrPtoB, into plant cells. Two plant protein kinases, Fen and Pto, then stimulate disease defense responses that may restrain or halt the infection. Ntoukakis et al. (p. 784 ) show that the balance between resistance and susceptibility triggered by AvrPtoB is determined by the kinase activity Pto within a disease resistance complex.

The Pto gene of tomato (Solanum lycopersicum) confers specific recognition of the unrelated bacterial effector proteins AvrPto and AvrPtoB. Pto resides in a constitutive molecular complex with the nucleotide binding site-leucine rich repeats protein Prf. Prf is absolutely required for specific recognition of both effectors. Here, using stable transgenic lines, we show that expression of Pto from its genomic promoter in susceptible tomatoes was sufficient to complement recognition of Pseudomonas syringae pv. tomato (Pst) bacteria expressing either avrPto or avrPtoB. Pto kinase activity was absolutely required for specific immunity. Expression of the Pto N-myristoylation mutant, pto(G2A), conferred recognition of Pst (avrPtoB), but not Pst (avrPto), although bacterial growth in these lines was intermediate between resistant and susceptible lines. Overexpression of pto(G2A) complemented recognition of avrPto. Transgenic tomato plants overexpressing wild-type Pto exhibited constitutive growth phenotypes, but these were absent in lines overexpressing pto(G2A). Therefore, Pto myristoylation is a quantitative factor for effector recognition in tomato, but is absolutely required for overexpression phenotypes. Native expression of Pto in the heterologous species Nicotiana benthamiana did not confer resistance to P. syringae pv. tabaci (Pta) expressing avrPto or avrPtoB, but recognition of both effectors was complemented by Prf co-expression. Thus, specific resistance conferred solely by Pto in N. benthamiana is an artefact of overexpression. Finally, pto(G2A) did not confer recognition of either avrPto or avrPtoB in N. benthamiana, regardless of the presence of Prf. Thus, co-expression of Prf in N. benthamiana complements many but not all aspects of normal Pto function.

Chemical structure diagrams, just as in engineering drawings, maps, and other technical diagrams, consist of solid and dashed lines (bonds), characters (atom symbols), and other symbols such as brackets, parentheses, wedges (stereo-up bonds) or dashed wedges (stereo-down bonds). In addition to recognizing these low-level elements of such drawings, other artifacts may be present — bonds intersections may be crossings or atom nodes, character strings may represent underlying chemical structure, and circles are sometimes used to represent ring-alternating bonding — requiring a considerable knowledge base of chemistry to be able to interpret correctly. This paper discusses the general processes used in the program Kekule 1 that embodies this interpretation ability with more detailed explanations of how some problems relating to polygon approximation, dashed line and dashed wedge finding, and optical character recognition were solved.

The use of metal for currency defined by weight can be shown by texts and material from the Near East from some time in the second millennium B.C. to the introduction of Greek‐style coinage to those areas by Alexander. The long tradition of weighing currency is shown by the elaborate weight systems of these regions and the presence of the element of weighing in the words which first meant weight and then transferred their meaning to denomination. The use of seals for identification has combined with the use of metal for currency to provide the first coins in groups where the development from currency to coinage is visible. The hoard of Lydian coins at Ephesus is one such, but an even earlier one from Zincirli provides the model of the seal for the inscription as well as the uninscribed pieces for the surface to be inscribed. As such, they illustrate the earliest surviving example of the critical moment when a piece of metal exchangeable by weight is transferred to a coin by having it first made i...

Sheila Collins, Miriam Balmuth, and Priscilla Jean discuss a pioneering program in workplace literacy begun in 1988 by two cooperating trade union organizations in New York City. In this initiative, the unions were responding to the changing needs of their members in today's shifting labor market, which has made traditional literacy programs irrelevant to improving the lives of most of today's workers. The authors discuss new conceptions of literacy that inform this initiative; in particular, the shift in focus from "worker literacy"to "workplace literacy." They present four case studies of specific programs various trade unions have developed based on their members' particular needs and workplace settings. These programs illustrate principles of workplace literacy aimed at providing adult workers with the kind of education they need to advance in their jobs and to take greater control over their lives at work and in their communities.

The underlying cellular mechanisms of catatonia, an executive “psychomotor” syndrome that is observed across neuropsychiatric diseases, have remained obscure. In humans and mice, reduced expression of the structural myelin protein CNP is associated with catatonic signs in an age-dependent manner, pointing to the involvement of myelin-producing oligodendrocytes. Here, we showed that the underlying cause of catatonic signs is the low-grade inflammation of white matter tracts, which marks a final common pathway in Cnp-deficient and other mutant mice with minor myelin abnormalities. The inhibitor of CSF1 receptor kinase signaling PLX5622 depleted microglia and alleviated the catatonic symptoms of Cnp mutants. Thus, microglia and low-grade inflammation of myelinated tracts emerged as the trigger of a previously unexplained mental condition. We observed a very high (25%) prevalence of individuals with catatonic signs in a deeply phenotyped schizophrenia sample (n = 1095). Additionally, we found the loss-of-function allele of a myelin-specific gene (CNP rs2070106-AA) associated with catatonia in 2 independent schizophrenia cohorts and also associated with white matter hyperintensities in a general population sample. Since the catatonic syndrome is likely a surrogate marker for other executive function defects, we suggest that microglia-directed therapies may be considered in psychiatric disorders associated with myelin abnormalities.