Using RAD‐seq to develop sex‐linked markers in a haplodiplontic alga

For many taxa, including isomorphic haplodiplontic macroalgae, determining sex and ploidy is challenging, thereby limiting the scope of some population demographic and genetic studies. Here, we used double‐digest restriction site‐associated DNA sequencing (ddRAD‐seq) to identify sex‐linked molecular markers in the widespread red alga Agarophyton vermiculophyllum. In the ddRAD‐seq library, we included 10 female gametophytes, 10 male gametophytes, and 16 tetrasporophytes from one native and one non‐native site (N = 40 gametophytes and N = 32 tetrasporophytes total). We identified seven putatively female‐linked and 19 putatively male‐linked sequences. Four female‐ and eight male‐linked markers amplified in all three life cycle stages. Using one female‐ and one male‐linked marker that were sex‐specific, we developed a duplex PCR and tested the efficacy of this assay on a subset of thalli sampled at two sites in the non‐native range. We confirmed ploidy based on the visual observation of reproductive structures and previous microsatellite genotyping at 10 polymorphic loci. For 32 vegetative thalli, we were able to assign sex and confirm ploidy in these previously genotyped thalli. These markers will be integral to ongoing studies of A. vermiculophyllum invasion. We discuss the utility of RAD‐seq over other approaches previously used, such as RAPDs (random amplified polymorphic DNA), for future work designing sex‐linked markers in other haplodiplontic macroalgae for which genomes are lacking.     

Mediation of Clathrin-Dependent Trafficking during Cytokinesis and Cell Expansion by Arabidopsis STOMATAL CYTOKINESIS DEFECTIVE Proteins

STOMATAL CYTOKINESIS DEFECTIVE1 (SCD1) encodes a putative Rab guanine nucleotide exchange factor that functions in membrane trafficking and is required for cytokinesis and cell expansion in Arabidopsis thaliana. Here, we show that the loss of SCD2 function disrupts cytokinesis and cell expansion and impairs fertility, phenotypes similar to those observed for scd1 mutants. Genetic and biochemical analyses showed that SCD1 function is dependent upon SCD2 and that together these proteins are required for plasma membrane internalization. Further specifying the role of these proteins in membrane trafficking, SCD1 and SCD2 proteins were found to be associated with isolated clathrin-coated vesicles and to colocalize with clathrin light chain at putative sites of endocytosis at the plasma membrane. Together, these data suggest that SCD1 and SCD2 function in clathrin-mediated membrane transport, including plasma membrane endocytosis, required for cytokinesis and cell expansion.     

Predictors of Ethno-Cultural Identity Conflict Among South Asian Immigrant Youth in New Zealand

The study tested a predictive model of ethno-cultural identity conflict (EIC) in a sample of 262 first-generation South Asian youth (aged 16–26, M = 19.4) in New Zealand. Hierarchical multiple regression was used to investigate the influence of: 1) attachment styles (preoccupied, dismissive, secure, and fearful); 2) family relations (intergenerational conflict and family cohesion); 3) ethnic (belonging, centrality, and exploration) and national identities; and 4) interactions between the components of ethnic and national identity. Controlling for demographic factors, results indicated that a preoccupied attachment style and experiences of acculturative intergenerational conflict exacerbated EIC, whereas family cohesion, ethnic identity centrality, and ethnic group belonging protected against EIC. It was also found that national identity moderated the effects of ethnic identity on EIC. Overall, these findings suggest positive self-regard, family cohesion, and integrated achieved identities should be promoted for immigrant youth.     

Immigrant Civic Engagement: New Translations

This study used a mixed methods methodology to investigate the reliability and validity of the Ounce Scale, an authentic, observational assessment of infants' and toddlers' development from birth through 42 months of age. Quantitative cross-sectional data were collected from 287 children and 124 teachers in seven urban Early Head Start programs; qualitative data were derived from interviews with 21 teachers and seven supervisors. Data were collected across eight age groups. Results showed moderate reliability of the Ounce Scale and provided evidence of agreement with criterion measures for concurrent validity. Receiver operating characteristic curve (ROC) analyses demonstrated very good levels of accuracy in predicting which children were at-risk or not at-risk. Hierarchical regression analyses indicated that, after controlling for child and family variables, the Ounce Scale contributed significantly to explaining the variance in children's performance on the criterion measures. Analysis of qualitative interview data elaborates on these findings in terms of the strength-based philosophy of the caregivers, the binary structure of the scale, the cultural context in which the scale was used, and the need for additional professional development. Discussion also centers on the relationship between norm-referenced and performance-based assessments in early childhood.     

Contested Citizenship and Social Exclusion: Adolescent Arab American Immigrants' Views of the Social Contract

Drawing from social contract theory, we explore how some adolescent Arab immigrants' (n = 99) sensitivity to the image of their ethnic group as enemies of America colors their interpretation of the social contract. Analyses of data collected in 1997 reveal that those youth who reported that the American media portray Arab people and nations as enemies of the United States are more attuned to personal experiences of prejudice based on their ethnic identity and are more dubious that the tenets of the social contract apply equally across groups. Negative images of Arab Americans were well in place prior to September 11, 2001, a pivotal moment that altered the lives of Arab Americans as well as the discourse on immigration and citizenship.     

Structure-Activity Relationships Among a New Class of Antiviral Heterosubstituted 2′,3′-Dideoxynucleoside Analogues

Abstract

3′-Oxa-4′-thiocytidine nucleoside analogues 14–17 were prepared from oxathiolanes 10 and 11, and evaluated for activity against HIV-1 and HBV in vitro. The nucleoside analogues were found to possess potent activities against HIV-1 in a panel of cell lines. Compound 16 is moderately active against HBV in 2.2.15 cells.     

Legacies of Prehistoric Agricultural Practices Within Plant and Soil Properties Across an Arid Ecosystem

Closely integrated research between archaeologists and ecologists provides a long-term view of human land use that is rare in the ecological literature, allowing for investigation of activities that lead to enduring environmental outcomes. This extended temporal perspective is particularly important in aridlands where succession occurs slowly and ecosystem processes are mediated by abiotic, geomorphic factors. Numerous studies show that impacts from ancient human actions can persist, but few have explored the types of practices or mechanisms that lead to either transient or long-term environmental change. We compared plant and soil properties and processes from a range of landscape patch types in the Sonoran Desert of the US Southwest that supported different, well-documented prehistoric farming practices from AD 750–1300. Our results show that the types of ancient human activities that leave long-term ecological legacies in aridlands are those that fundamentally alter “slow variables” such as soil properties that regulate the timing and supply of water. Prehistoric Hohokam floodwater-irrigation practices, but not dryland farming techniques, substantially altered soil texture, which was strongly associated with desert plant community and functional composition. However, prehistoric agriculture did not consistently alter long-term nutrient availability and thus had no impact on “fast variables” such as production of seasonal annual plants that are restricted to periods of ample rainfall. In this arid ecosystem, the inverse texture model explained patterns in plant functional composition at large scales, but is less predictive of production of short-lived desert annuals that experience a more mesic precipitation regime.     

Predicting bait uptake by feral cats,Felis catus,in semi‐arid environments

Feral cat control using aerial broadcasting of toxic baits continues to be used in the rangelands of Western Australia. The effectiveness of these operations has sometimes been compromised by different environmental factors that affect prey and cat numbers. This study demonstrates that the ratio of cats to their preferred prey (small mammals) can be used to predict the most effective time to bait. The regular baiting of three conservation sites offered an opportunity to study the relationship between feral cat abundance, the abundance of their prey and ingestion of toxic baits. Peron Peninsula on the mid‐west coast, Lorna Glen station in the northern Goldfields and the central Gibson Desert of Western Australia are sites where cat control using toxic baits has been routinely applied over the last 15 years. We postulated that bait ingestion by cats was linked to the availability of live prey. Small mammal abundance (capture rates in pit‐fall traps) and relative cat abundance (based on daily track counts) were assessed at these sites and the data used to produce a predator‐prey ratio index (PPRI). We used generalised linear mixed models to test the effect of prey abundance, prebaiting cat abundance and PPRI on baiting efficacy (BE). The best model for predicting efficacy of baiting contained only PPRI. This simple model was able to predict baiting success over the entire range of outcomes, from highly successful ( >75% cat reduction) to unsuccessful (0% cat reduction). The ability to predict feral cat BE in advance of planned toxic baiting operations will provide a valuable tool for wildlife managers involved in cat control.