RESUMO
Schools in the United States are increasingly offering ethnic studies classes, which focus on exploring students' ethnic-racial identities (ERI) and critical analysis of systemic racism, to their diverse student bodies, yet scant research exists on their effectiveness for students of different ethnic-racial backgrounds in multiracial classrooms. A policy change to require all high school students in one school district to take an ethnic studies class facilitated a natural experiment for comparing the effects of quasi-random assignment to an ethnic studies class (treatment) relative to a traditional social studies class (control; e.g., U.S. Government, Human Geography). Student surveys and school administrative data were used to compare students' ERI development, well-being, and academic outcomes across ethnic studies and control classes. Participants (N = 535 9th graders; 66.1% ethnic studies) had diverse ethnic-racial (33.5% non-Latine White, 29.5% Black, 21.1% Latine, 10.7% biracial, 2.8% Asian, 2.2% Native American) and gender identities (44.7% female, 7.1% non-binary). Ethnic studies students reported marginally higher ERI exploration and resolution than controls, and sensitivity analyses showed a statistically significant effect on ERI among participants with complete midpoint surveys. Higher resolution was associated with better psychological well-being for all students and higher attendance for White students. Students with low middle school grades (GPA < 2.0) had better high school grades in core subjects when enrolled in ethnic studies than the control class. Overall, the results of this natural experiment provide preliminary support for ethnic studies classes as a method for promoting ERI development, well-being, attendance, and academic achievement for students from diverse ethnic-racial backgrounds.
RESUMO
Acculturation and psychopathology are linked in integrated, interactional, intersectional, and dynamic ways that span different types of intercultural contact, levels of analysis, timescales, and contexts. A developmental psychopathology approach can be useful to explain why, how, and what about psychological acculturation results in later adaptation or maladaptation for acculturating youth and adults. This review applies a conceptual model of acculturation and developmental psychopathology to a widely used framework of acculturation variables producing an Integrated Process Framework of Acculturation Variables (IP-FAV). This new comprehensive framework depicts major predisposing acculturation conditions (why) as well as acculturation orientations and processes (how) that result in adaptation and maladaptation across the life span (what). The IP-FAV is unique in that it integrates both proximal and remote acculturation variables and explicates key acculturation processes to inform research, practice, and policy.
Assuntos
Aculturação , Transtornos Mentais , Psicopatologia , Transtornos Mentais/epidemiologia , Transtornos Mentais/psicologia , Psicopatologia/métodos , Estados Unidos , Humanos , CriançaRESUMO
There is a pressing need for prevention programs that address increasing rates of epidemics and pandemics, including noncommunicable diseases. However, many populations face substantial systemic barriers to accessing traditional prevention programs. To minimize persistent service utilization gaps for underserved populations, the field requires effective, efficient, and sustainable methods to increase accessibility and cultural relevance of prevention programming to multiple audiences. Cultural adaptation is one such strategy, but it can be daunting for many preventionists. Therefore, this paper presents a step-by-step guide to streamline the cultural adaptation of prevention programs through digitization and use of a novel application of storyboarding methodology, called "blueprint storyboarding." This innovative approach to cultural adaptation is designed to increase systematicity through manualization, efficiency, cost-effectiveness, and adaptability for multiple cultures and developmental stages. We illustrate this novel method by describing how we applied the blueprint storyboarding approach after digitization to culturally adapt the JUS Media? Programme, a food-focused media literacy program designed to buffer media-related obesity risks for diverse youth.
Assuntos
Área Carente de Assistência Médica , Obesidade , Humanos , AdolescenteRESUMO
This mixed methods study examined parent-reported child screen media use before and during the COVID-19 pandemic by examining 2019-2020 changes in parent perceptions of media, screen media use (SMU), and problematic media use (PMU) in children aged 2-13 years (N = 129; 64 boys, 64 girls, 1 nonbinary; 90.7% White, 4.6% Hispanic/Latino, 0.8% Black, 8.5% multiethnic; primarily middle-to-high income). Quantitative analyses showed a significant SMU and PMU increase (medium effect size). There was a steeper increase in PMU among school-age (older) children. Together, the qualitative and quantitative results suggest that the PMU and SMU increase were influenced by distal, proximal, and maintaining factors including the COVID-19 pandemic, distance learning, child behaviors, other children, parental mediation, and positive media reinforcement.
Assuntos
COVID-19 , Pandemias , Criança , Comportamento Infantil , Feminino , Humanos , Masculino , Pais , SARS-CoV-2 , Estados Unidos/epidemiologiaRESUMO
We investigate whether media literacy and media use can moderate the association between U.S. media enjoyment and unhealthy eating among remotely acculturating "Americanized" adolescents and their mothers in Jamaica (n = 164 individuals/82 dyads; Madolescent.age = 12.83, SD = 0.48, 48% female; Mmother_age = 39.25, SD = 5.71). Socioeconomically diverse participants completed questionnaires reporting their degree of enjoyment of U.S. media (i.e., remote acculturation), media literacy (i.e., critical thinking about food media/advertising), and adherence to national dietary guidelines to reduce sugar/fat. Multilevel modeling showed that enjoying U.S. media and consuming high levels of U.S. TV plus Jamaican TV are associated with lower efforts to reduce sugar and fat. However, high media literacy, whether one's own or a close family member's, weakens or nullifies that association.
Assuntos
Mães , Prazer , Adolescente , Adulto , Criança , Emoções , Feminino , Humanos , Jamaica , Alfabetização , MasculinoRESUMO
Southeast Asian American (SEAA) adolescents and emerging adults navigate a multicultural, global world by utilizing cultural variability to play up and play down three cultural identities: their Asian/Asian American heritage culture, the White dominant culture in which they live, and a hip hop cultural identity. The latter is a unique cultural identity rooted in the global phenomenon of hip hop that includes dance, art, and music as well as resistance to the dominant, mainstream culture. Hip hop is a meaningful cultural identity for SEAA youth because it is a cultural identity transcendent of race/ethnicity, a means toward relational and identity harmony, a form of resistance, and because it facilitates belongingness to a local and a global community.
Assuntos
Comportamento do Adolescente/etnologia , Asiático/psicologia , Dança , Música , Identificação Social , Adolescente , Adulto , Sudeste Asiático/etnologia , Feminino , Humanos , Masculino , Estados Unidos/etnologia , Adulto JovemRESUMO
Remote acculturation (RA) is a modern form of non-migrant acculturation toward distant cultures prompted by indirect/intermittent globalization-related cultural exposure. RA theory holds that not only are global cultures now pouring into local neighborhoods, but many youth are also internalizing these remote cultures. How well do they fare? Prior studies in Jamaica and elsewhere have reported that U.S./Western-oriented adolescents exhibit poorer health habits. However, no studies have yet investigated adolescents' behavioral or academic adjustment in the context of RA, whether in Jamaica or elsewhere. Therefore, 245 adolescents and their mothers from high schools in Kingston, Jamaica (Madolescent_age = 13.3; Mmother_age = 40.2) completed questionnaires assessing their RA in terms of behaviors and values, as well as the adolescents' behavioral resilience and grades. SEM analyses revealed that RA was, indeed, linked to adolescent behavioral and academic adjustment in Jamaica. Overall, Jamaican orientation was associated with better adaptation whereas European American orientation was associated with worse.
Assuntos
Sucesso Acadêmico , Aculturação , Adaptação Psicológica , Comportamento do Adolescente/etnologia , Internacionalidade , Ajustamento Social , Adolescente , Adulto , Criança , Feminino , Humanos , Jamaica/etnologia , Masculino , População UrbanaRESUMO
How DNA metabolism is adapted to survival of organisms such as the bacterium Photobacterium profundum SS9 at high pressure is unknown. Previously, a high pressure-sensitive P. profundum SS9 transposon mutant (FL31) was identified, with an insertion in a putative rctB gene. The Vibrio cholerae RctB protein is essential for replication initiation at the origin of chromosome II, oriCII. Using a plasmid-based system in E. coli we have identified the replication origin of chromosome II from P. profundum SS9 and have shown that the putative rctB gene, disrupted in FL31, is essential for oriCII function. Moreover, we found that a region corresponding to the V. cholerae oriCII incompatibility region (incII) exerts an inhibitory effect on P. profundum oriCII. The truncated rctB gene in FL31 confers insensitivity to incII inhibition, indicating that the C-terminus of RctB is important for the negative regulation of replication. The RctB proteins of V. cholerae and P. profundum are partially interchangeable, but full functionality is achieved only with the cognate origin. Our findings provide the first characterization of the replication origin of chromosome II in a deep-sea bacterium.
Assuntos
Cromossomos Bacterianos/genética , Replicação do DNA , Photobacterium/genética , Origem de Replicação/genética , Adaptação Fisiológica/genética , Pressão Atmosférica , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Cromossomos Bacterianos/metabolismo , DNA Helicases/química , DNA Helicases/genética , DNA Helicases/metabolismo , DNA Bacteriano/genética , DNA Bacteriano/metabolismo , Escherichia coli/genética , Genes Bacterianos/genética , Mutação , Photobacterium/crescimento & desenvolvimento , Photobacterium/metabolismo , Plasmídeos/genética , Plasmídeos/metabolismo , Transativadores/química , Transativadores/genética , Transativadores/metabolismo , Vibrio cholerae/genéticaRESUMO
Globalization prompts remote acculturation toward U.S. culture in Jamaica; this study used a bioecological systems approach to examine its proximal impact on nutrition through U.S. cable TV consumption, and maternal influences in the home. Overall, 330 randomly selected adolescent-mother dyads from schools in Kingston, Jamaica (Madolescent_age = 13.8 years, SDadolescent_age = 1.8) completed questionnaires reporting American identity and behavioral preferences, daily time spent watching U.S.-produced TV programs, and frequency of eating unhealthy foods. Actor-partner interdependence models revealed that girls' American identity/behavior directly predicted their unhealthy eating, whereas girls' mothers and boys' American identity/behavior indirectly predicted unhealthy eating as mediated by their U.S. TV hours. Additionally, mothers' American identity/behavior predicted daughters' unhealthy eating as mediated by mothers' U.S. TV hours. Remote acculturation theory may facilitate more targeted research and prevention/intervention.
Assuntos
Aculturação , Identificação Social , Adolescente , Adulto , Criança , Emoções , Comportamento Alimentar/etnologia , Feminino , Alimentos , Humanos , Jamaica/etnologia , Masculino , Comportamento Materno , Relações Mãe-Filho/etnologia , Mães/psicologia , Inquéritos e Questionários , Televisão , Estados UnidosRESUMO
We explore the quantity (frequency) and quality (priority, atmosphere, structure) of family mealtimes and associations with nutritional and emotional health in Jamaica. Urban adolescents (Nâ¯=â¯330, Mâ¯=â¯13.8 years, SDâ¯=â¯1.8, 64% girls) and their mothers (Mâ¯=â¯41.4 years, SDâ¯=â¯7.8) completed questionnaires. On average, mothers reported having family meals 3-4 times/week and mealtime quality, but not quantity, was associated with health. Correlations revealed that mothers ate more unhealthily if they watched more TV during meals, and actor-partner independence modeling showed that high SES adolescents ate more unhealthily if their mothers had more difficulty finding time for family meals (and vice versa: partner interaction). Additionally, adolescents and mothers were more psychologically distressed if they themselves had more difficulty finding time for family meals, if they had less positive attitudes/behaviors around mealtime atmosphere (actor effects), or if they were high SES individuals placing lower importance on mealtimes (actor interaction). Overall, however many weekly meals Jamaican families are able to share together, what's important is to make those mealtimes count as quality time. Leisurely family meals with enjoyable conversation uninterrupted by television, such as the age-old Jamaican tradition of "Sunday Dinner", may nourish both body and soul.
Assuntos
Ingestão de Alimentos/psicologia , Família/psicologia , Comportamento Alimentar/psicologia , Refeições/psicologia , Mães/psicologia , Adolescente , Adulto , Emoções , Feminino , Humanos , Jamaica , Masculino , Saúde Mental , Estado Nutricional , Relações Pais-FilhoRESUMO
OBJECTIVES: Cultural variability (CV) is introduced as an overlooked dimension of cultural identity development pertaining to emphasizing and de-emphasizing the influence of a single cultural identity (i.e., cultural influence [CI]) on daily interactions and behaviors. The Cultural IDentity Influence Measure (CIDIM) is introduced as a novel measure of CI and CV, and hypothesis-driven validation is conducted in two samples along with exploration of associations between CV and well-being. METHOD: A multicultural sample of 242 emerging adults participated in a daily diary study (Mage = 19.95 years, SDage = 1.40) by completing up to eight daily online surveys containing the CIDIM, criterion measures (ethnic identity, other group orientation, ethnic identity salience and daily variability in salience, social desirability), and measures of personal and interpersonal well-being. A second validation sample (n = 245) completed a 1-time survey with the CIDIM and a subset of criterion measures. RESULTS: Results using both samples show evidence of CI and CV and demonstrate the validity, reliability, and domain-sensitivity of the CIDIM. Further, CV made unique and positive contributions to predicting interaction quality after accounting for ethnic salience and variability in ethnic salience. An analytic approach utilizing standard deviations produced near-identical results to multilevel modeling and is recommended for parsimony. CONCLUSIONS: Ethnic minority and majority individuals make daily adjustments to play up and play down the influence of cultural identity on their social interactions and behaviors, and these adjustments predict interpersonal well-being. Cultural influence and cultural variability contribute to our emerging understanding of cultural identity as dynamic and agentic. (PsycINFO Database Record
Assuntos
Adaptação Psicológica , Grupos Minoritários/psicologia , Autoimagem , Identificação Social , Adulto , Etnicidade , Feminino , Humanos , Masculino , Reprodutibilidade dos Testes , Inquéritos e QuestionáriosRESUMO
One impact of globalisation is that adolescents today are frequently exposed to the values, attitudes and norms of other nations without leaving their own backyards. This may lead to remote acculturation-cultural and psychological changes experienced by non-migrant individuals having indirect and/or intermittent contact with a geographically separate culture. Using quantitative and qualitative data, we examined multidimensional remote acculturation among 83 urban Zambian adolescents who are routinely exposed to U.S., U.K. and South African cultures through traditional and social media and materials/goods. Cluster analyses showed 2 distinct groups of adolescents. "Traditional Zambians, TZs" (55.4%) were significantly more oriented towards Zambian culture and reported a higher level of obligation to their families and greater interdependent self-construal compared with "Westernised Multicultural Zambians, WMZs" (44.6%), who were more oriented towards U.S., U.K. and South African cultures. Furthermore, remote acculturation predicted somewhat lower life satisfaction among WMZs. These results demonstrate that individuals' behaviours, values and identity may be influenced by multiple geographically distant cultures simultaneously and may be associated with psychological costs.
Assuntos
Aculturação , Diversidade Cultural , Etnicidade/psicologia , Psicologia do Adolescente , Qualidade de Vida/psicologia , População Urbana , Adolescente , Feminino , Humanos , Internacionalidade , Masculino , Identificação Social , Migrantes , ZâmbiaRESUMO
Remote acculturation is a modern form of non-immigrant acculturation identified among early adolescents in Jamaica as "Americanization". This study aimed to replicate the original remote acculturation findings in a new cohort of early adolescents in Jamaica (n = 222; M = 12.08 years) and to extend our understanding of remote acculturation by investigating potential vehicles of indirect and intermittent intercultural contact. Cluster analyses replicated prior findings: Relative to Traditional Jamaican adolescents (62%), Americanized Jamaican adolescents (38%) reported stronger European American cultural orientation, lower Jamaican orientation, lower family obligations, and greater conflict with parents. More U.S. media (girls) and less local media and local sports (all) were the primary vehicles of intercultural contact predicting higher odds of Americanization. U.S. food, U.S. tourism, and transnational communication were also linked to U.S. orientation. Findings have implications for acculturation research and for practice and policy targeting Caribbean youth and families.
RESUMO
yaiW is a previously uncharacterized gene found in enteric bacteria that is of particular interest because it is located adjacent to the sbmA gene, whose bacA ortholog is required for Sinorhizobium meliloti symbiosis and Brucella abortus pathogenesis. We show that yaiW is cotranscribed with sbmA in Escherichia coli and Salmonella enterica serovar Typhi and Typhimurium strains. We present evidence that the YaiW is a palmitate-modified surface exposed outer membrane lipoprotein. Since BacA function affects the very-long-chain fatty acid (VLCFA) modification of S. meliloti and B. abortus lipid A, we tested whether SbmA function might affect either the fatty acid modification of the YaiW lipoprotein or the fatty acid modification of enteric lipid A but found that it did not. Interestingly, we did observe that E. coli SbmA suppresses deficiencies in the VLCFA modification of the lipopolysaccharide of an S. meliloti bacA mutant despite the absence of VLCFA in E. coli. Finally, we found that both YaiW and SbmA positively affect the uptake of proline-rich Bac7 peptides, suggesting a possible connection between their cellular functions.
Assuntos
Peptídeos Catiônicos Antimicrobianos/metabolismo , Proteínas da Membrana Bacteriana Externa/metabolismo , Proteínas de Escherichia coli/metabolismo , Escherichia coli/efeitos dos fármacos , Escherichia coli/metabolismo , Lipoproteínas/metabolismo , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/metabolismo , Proteínas da Membrana Bacteriana Externa/genética , Brucella abortus/genética , Escherichia coli/genética , Proteínas de Escherichia coli/genética , Genes Supressores , Lipoproteínas/genética , Testes de Sensibilidade Microbiana , Salmonella typhimurium/genética , Sinorhizobium meliloti/genética , Transcrição Gênica , Transferases/genética , Transferases/metabolismoRESUMO
Sinorhizobium meliloti differentiates into persisting, nitrogen-fixing bacteroids within root nodules of the legume Medicago truncatula. Nodule-specific cysteine-rich antimicrobial peptides (NCR AMPs) and the bacterial BacA protein are essential for bacteroid development. However, the bacterial factors central to the NCR AMP response and the in planta role of BacA are unknown. We investigated the hypothesis that BacA is critical for the bacterial response towards NCR AMPs. We found that BacA was not essential for NCR AMPs to induce features of S. meliloti bacteroids in vitro. Instead, BacA was critical to reduce the amount of NCR AMP-induced membrane permeabilization and bacterial killing in vitro. Within M. truncatula, both wild-type and BacA-deficient mutant bacteria were challenged with NCR AMPs, but this resulted in persistence of the wild-type bacteria and rapid cell death of the mutant bacteria. In contrast, BacA was dispensable for bacterial survival in an M. truncatula dnf1 mutant defective in NCR AMP transport to the bacterial compartment. Therefore, BacA is critical for the legume symbiosis by protecting S. meliloti against the bactericidal effects of NCR AMPs. Host AMPs are ubiquitous in nature and BacA proteins are essential for other chronic host infections by symbiotic and pathogenic bacteria. Hence, our findings suggest that BacA-mediated protection of bacteria against host AMPs is a critical stage in the establishment of different prolonged host infections.
Assuntos
Peptídeos Catiônicos Antimicrobianos/farmacologia , Cisteína/metabolismo , Interações Hospedeiro-Patógeno/efeitos dos fármacos , Medicago truncatula/microbiologia , Sinorhizobium meliloti/efeitos dos fármacos , Sinorhizobium meliloti/fisiologia , Simbiose/efeitos dos fármacos , Sequência de Aminoácidos , Peptídeos Catiônicos Antimicrobianos/química , Proteínas de Bactérias/metabolismo , Medicago truncatula/efeitos dos fármacos , Viabilidade Microbiana/efeitos dos fármacos , Dados de Sequência Molecular , Mutação/genética , Estrutura Secundária de Proteína , Sinorhizobium meliloti/citologiaRESUMO
Adolescents are an emerging population in Haiti, particularly after the deadly 2010 earthquake. The steady penetration of U.S. culture into this poor, disaster-prone country begs the question: Do today's adolescents possess a similar fondness for their home country, culture, and traditional family values as did Haitians of old? Or are they more oriented towards U.S. culture? Early adolescents (n = 105, M = 12.87 yrs, SD = .86) in rural Haiti reported their cultural orientation towards Haitian culture and U.S. culture as well as their family obligations beliefs. Findings revealed high Haitian orientation, very high family obligations (boys especially), and very low U.S. orientation, although adolescents who interacted more frequently with U.S. tourists and those who consumed more U.S. fast food had higher U.S. culture orientation. Despite severe challenges, rural Haitian early adolescents demonstrate remarkable allegiance to their home country, culture, and traditional family values.
RESUMO
This brief report assesses parent-adolescent relationships, screen behaviors, and tridimensional acculturation as risk and promotive or protective factors for health among Black U.S. immigrant or refugee adolescents during the dual COVID-19 and racism or Whiteness pandemics. Eighty-nine immigrant- or refugee-origin adolescents completed online surveys (72% Somali American, 28% Jamaican American; 45% female; 15% foreign-born; M = 14.11 years). Regression analyses revealed that parental autonomy support, parental restrictive media mediation, and adolescent heritage culture identification were promotive of better screen media use behaviors. Only adolescent media literacy self-efficacy was related to higher screen time. Importantly, screen self-regulation was a better predictor of general health than screen time. Results highlight many parenting strengths in Black immigrant or refugee families and underscore the resilience-promoting power of parent-adolescent relationships. Health implications are discussed to provide guidance for future prevention efforts. (PsycInfo Database Record (c) 2024 APA, all rights reserved).
Assuntos
Aculturação , Negro ou Afro-Americano , COVID-19 , Emigrantes e Imigrantes , Relações Pais-Filho , Refugiados , Tempo de Tela , Humanos , Adolescente , Feminino , Masculino , Emigrantes e Imigrantes/psicologia , Emigrantes e Imigrantes/estatística & dados numéricos , Refugiados/psicologia , Refugiados/estatística & dados numéricos , COVID-19/psicologia , COVID-19/etnologia , Relações Pais-Filho/etnologia , Negro ou Afro-Americano/psicologia , Negro ou Afro-Americano/estatística & dados numéricos , Negro ou Afro-Americano/etnologia , Comportamento do Adolescente/psicologia , Comportamento do Adolescente/etnologia , Estados Unidos/etnologia , Poder Familiar/psicologia , Poder Familiar/etnologia , Adulto , PandemiasRESUMO
The capacity to conduct psychology research online has expanded more quickly than have ethics guidelines for digital research. We argue that researchers must proactively plan ways to engage ethically in online psychological research with vulnerable groups, including marginalized and immigrant youth and families. To that end, this article describes the ethical use of internet and cell phone technologies in psychological research with Black immigrant and refugee youth and families, which demands efforts to both deepen and extend the Belmont principles of respect for persons, beneficence, and justice. We describe and apply four research frameworks-community-based participatory research, transdisciplinary team science, representational ethics, and cross-cultural psychology-that can be integrated to offer practical solutions to ethical challenges in digital research with Black immigrant and refugee youth and families. Then, as an illustration, we provide a case example of this approach using the Food, Culture, and Health Study conducted with Black Jamaican American and Somali American youth and families, who experience tridimensional acculturation due to their race and have been disproportionately impacted by the dual pandemics of COVID-19 and racism/Whiteness. We offer this article as a road map for other researchers seeking to conduct ethical digital community-based psychological research with Black immigrant youth and families and other marginalized communities. (PsycInfo Database Record (c) 2024 APA, all rights reserved).
Assuntos
Emigrantes e Imigrantes , Refugiados , Humanos , Adolescente , Pesquisadores , Pesquisa Participativa Baseada na Comunidade , AculturaçãoRESUMO
The root nodules of certain legumes including Medicago truncatula produce >300 different nodule-specific cysteine-rich (NCR) peptides. Medicago NCR antimicrobial peptides (AMPs) mediate the differentiation of the bacterium, Sinorhizobium meliloti into a nitrogen-fixing bacteroid within the legume root nodules. In vitro, NCR AMPs such as NCR247 induced bacteroid features and exhibited antimicrobial activity against S. meliloti. The bacterial BacA protein is critical to prevent S. meliloti from being hypersensitive toward NCR AMPs. NCR AMPs are cationic and have conserved cysteine residues, which form disulfide (S-S) bridges. However, the natural configuration of NCR AMP S-S bridges and the role of these in the activity of the peptide are unknown. In this study, we found that either cysteine replacements or S-S bond modifications influenced the activity of NCR247 against S. meliloti. Specifically, either substitution of cysteines for serines, changing the S-S bridges from cysteines 1-2, 3-4 to 1-3, 2-4 or oxidation of NCR247 lowered its activity against S. meliloti. We also determined that BacA specifically protected S. meliloti against oxidized NCR247. Due to the large number of different NCRs synthesized by legume root nodules and the importance of bacterial BacA proteins for prolonged host infections, these findings have important implications for analyzing the function of these novel peptides and the protective role of BacA in the bacterial response toward these peptides.
Assuntos
Peptídeos Catiônicos Antimicrobianos/química , Peptídeos Catiônicos Antimicrobianos/farmacologia , Cisteína , Dissulfetos/química , Medicago truncatula/química , Nódulos Radiculares de Plantas/química , Sequência de Aminoácidos , Peptídeos Catiônicos Antimicrobianos/metabolismo , Proteínas de Bactérias/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Dados de Sequência Molecular , Especificidade de Órgãos , Oxirredução , Sinorhizobium meliloti/efeitos dos fármacos , Sinorhizobium meliloti/metabolismoRESUMO
Sinorhizobium meliloti forms a symbiosis with the legume alfalfa, whereby it differentiates into a nitrogen-fixing bacteroid. The lipid A species of S. meliloti are modified with very long-chain fatty acids (VLCFAs), which play a central role in bacteroid development. A six-gene cluster was hypothesized to be essential for the biosynthesis of VLCFA-modified lipid A. Previously, two cluster gene products, AcpXL and LpxXL, were found to be essential for S. meliloti lipid A VLCFA biosynthesis. In this paper, we show that the remaining four cluster genes are all involved in lipid A VLCFA biosynthesis. Therefore, we have identified novel gene products involved in the biosynthesis of these unusual lipid modifications. By physiological characterization of the cluster mutant strains, we demonstrate the importance of this gene cluster in the legume symbiosis and for growth in the absence of salt. Bacterial LPS species modified with VLCFAs are substantially less immunogenic than Escherichia coli LPS species, which lack VLCFAs. However, we show that the VLCFA modifications do not suppress the immunogenicity of S. meliloti LPS or affect the ability of S. meliloti to induce fluorescent plant defense molecules within the legume. Because VLCFA-modified lipids are produced by other rhizobia and mammalian pathogens, these findings will also be important in understanding the function and biosynthesis of these unusual fatty acids in diverse bacterial species.