Bryophytes as food: comparative consumption and utilization of mosses by a generalist insect herbivore

Compared with angiosperms, bryophytes are seldom fed upon by insects, despite being commonly used for shelter. Bryophytes are assumed to be unpalatable, and three classes of mechanisms have been suggested as possible barriers to bryophagy: chemical defenses, low digestibility, and low nutrient content. However, very few studies have tested these hypotheses. The present study examines pre‐ and post‐ingestive defenses of mosses. The acceptability and quality of four species of moss –Bryum argenteum Hedw. (Bryales: Bryaceae), Climacium americanum Brid. (Leucodontales: Climaciaceae), Leucobryum glaucum (Hedw.) (Dicranales: Leucobryaceae), and Sphagnum warnstorfii Russ. (Sphagnales: Sphagnaceae) – were compared with two control diets using the generalist caterpillar, Trichoplusia ni Hübner (Lepidoptera: Noctuidae: Plusiinae). In no‐choice trials, caterpillars consumed much less of any of the mosses than lettuce or wheat germ. The only moss consumed in sufficient quantities to evaluate post‐ingestive responses was C. americanum. Digestibility, assimilation, and overall utilization efficiency of C. americanum did not differ from that of lettuce, although C. americanum and lettuce were both less digestible than artificial diet. Choice assays using leaf discs showed that ethanol extract of L. glaucum, the least consumed moss, was deterrent, implying that chemical defenses play a major role in deterring feeding on L. glaucum. This study suggested that pre‐ingestive mechanisms are more important than post‐ingestive mechanisms in discouraging herbivory on mosses, and offered evidence that mosses are not simply nutrient poor.     

Iterative in vivo assembly of large and complex transgenes by combining the activities of phiC31 integrase and Cre recombinase

We have used the phiC31 integrase to introduce large DNA sequences into a vertebrate genome and measure the efficiency of integration of intact DNA as a function of insert size. Inserts of 110 kb and 140 kb in length may be integrated with about 25% and 10% efficiency respectively. In order to overcome the problems of constructing transgenes longer than approximately 150 kb we have established a method that we call; 'Iterative Site Specific Integration' (ISSI). ISSI combines the activities of phiC31 integrase and Cre recombinase to enable the iterative and serial integration of transgenic DNA sequences. In principle the procedure may be repeated an arbitrary number of times and thereby allow the integration of tracts of DNA many hundreds of kilobase pairs long. In practice it may be limited by the time needed to check the accuracy of integration at each step of the procedure. We describe two ISSI experiments, in one of which we have constructed a complex array of vertebrate centromeric sequences of 150 kb in size. The principle that underlies ISSI is applicable to transgenesis in all organisms. ISSI may thus facilitate the reconstitution of biosynthetic pathways encoded by many different genes in transgenic plants, the assembly of large vertebrate loci as transgenes and the synthesis of complete genomes in bacteria.     

Maternal lineages and Alzheimer disease risk in the Old Order Amish

Old Order Amish, founded by a small number of Swiss immigrants, exist in culturally isolated communities across rural North America. The consequences of genetic isolation and inbreeding within this group are evident by increased frequencies of many monogenic diseases and several complex disorders. Conversely, the prevalence of Alzheimer disease (AD), the most common form of dementia, is lower in the Amish than in the general American population. Since mitochondrial dysfunction has been proposed as an underlying cause of AD and a specific haplogroup was found to affect AD susceptibility in Caucasians, we investigated whether inherited mitochondrial haplogroups affect risk of developing AD dementia in Ohio and Indiana Amish communities. Ninety-five independent matrilines were observed across six large pedigrees and three small pedigrees then classified into seven major European haplogroups. Haplogroup T is the most frequent haplogroup represented overall in these maternal lines (35.4%) while observed in only 10.6% in outbred American and European populations. Furthermore, haplogroups J and K are less frequent (1.0%) than in the outbred data set (9.4–11.2%). Affected case matrilines and unaffected control lines were chosen from pedigrees to test whether specific haplogroups and their defining SNPs confer risk of AD. We did not observe frequency differences between AD cases compared to controls overall or when stratified by sex. Therefore, we suggest that the genetic effect responsible for AD dementia in the affected Amish pedigrees is unlikely to be of mitochondrial origin and may be caused by nuclear genetic factors.     

Comprehensive thermodynamic analysis of 3' double-nucleotide overhangs neighboring Watson-Crick terminal base pairs

Thermodynamic parameters are reported for duplex formation of 48 self-complementary RNA duplexes containing Watson–Crick terminal base pairs (GC, AU and UA) with all 16 possible 3′ double-nucleotide overhangs; mimicking the structures of short interfering RNAs (siRNA) and microRNAs (miRNA). Based on nearest-neighbor analysis, the addition of a second dangling nucleotide to a single 3′ dangling nucleotide increases stability of duplex formation up to 0.8 kcal/mol in a sequence dependent manner. Results from this study in conjunction with data from a previous study [A. S. O'Toole, S. Miller and M. J. Serra (2005) RNA, 11, 512.] allows for the development of a refined nearest-neighbor model to predict the influence of 3′ double-nucleotide overhangs on the stability of duplex formation. The model improves the prediction of free energy and melting temperature when tested against five oligomers with various core duplex sequences. Phylogenetic analysis of naturally occurring miRNAs was performed to support our results. Selection of the effector miR strand of the mature miRNA duplex appears to be dependent upon the identity of the 3′ double-nucleotide overhang. Thermodynamic parameters for 3′ single terminal overhangs adjacent to a UA pair are also presented.     

Systematic review of effective strategies for reducing screen time among young children

Screen-media use among young children is highly prevalent, disproportionately high among children from lower-income families and racial/ethnic minorities, and may have adverse effects on obesity risk. Few systematic reviews have examined early intervention strategies to limit TV or total screen time; none have examined strategies to discourage parents from putting TVs in their children's bedrooms or remove TVs if they are already there. In order to identify strategies to reduce TV viewing or total screen time among children <12 years of age, we conducted a systematic review of seven electronic databases to June 2011, using the terms "intervention" and "television," "media," or "screen time." Peer-reviewed intervention studies that reported frequencies of TV viewing or screen-media use in children under age 12 were eligible for inclusion. We identified 144 studies; 47 met our inclusion criteria. Twenty-nine achieved significant reductions in TV viewing or screen-media use. Studies utilizing electronic TV monitoring devices, contingent feedback systems, and clinic-based counseling were most effective. While studies have reduced screen-media use in children, there are several research gaps, including a relative paucity of studies targeting young children (n = 13) or minorities (n = 14), limited long-term (>6 month) follow-up data (n = 5), and few (n = 4) targeting removing TVs from children's bedrooms. Attention to these issues may help increase the effectiveness of existing strategies for screen time reduction and extend them to different populations.     

Protein interaction profiling of the p97 adaptor UBXD1 points to a role for the complex in modulating ERGIC-53 trafficking

UBXD1 is a member of the poorly understood subfamily of p97 adaptors that do not harbor a ubiquitin association domain or bind ubiquitin-modified proteins. Of clinical importance, p97 mutants found in familial neurodegenerative conditions Inclusion Body Myopathy Paget's disease of the bone and/or Frontotemporal Dementia and Amyotrophic Lateral Sclerosis are defective at interacting with UBXD1, indicating that functions regulated by a p97-UBXD1 complex are altered in these diseases. We have performed liquid chromatography-mass spectrometric analysis of UBXD1-interacting proteins to identify pathways in which UBXD1 functions. UBXD1 displays prominent association with ERGIC-53, a hexameric type I integral membrane protein that functions in protein trafficking. The UBXD1-ERGIC-53 interaction requires the N-terminal 10 residues of UBXD1 and the C-terminal cytoplasmic 12 amino acid tail of ERGIC-53. Use of p97 and E1 enzyme inhibitors indicate that complex formation between UBXD1 and ERGIC-53 requires the ATPase activity of p97, but not ubiquitin modification. We also performed SILAC-based quantitative proteomic profiling to identify ERGIC-53 interacting proteins. This analysis identified known (e.g. COPI subunits) and novel (Rab3GAP1/2 complex involved in the fusion of vesicles at the cell membrane) interactions that are also mediated through the C terminus of the protein. Immunoprecipitation and Western blotting analysis confirmed the proteomic interaction data and it also revealed that an UBXD1-Rab3GAP association requires the ERGIC-53 binding domain of UBXD1. Localization studies indicate that UBXD1 modules the sub-cellular trafficking of ERGIC-53, including promoting movement to the cell membrane. We propose that p97-UBXD1 modulates the trafficking of ERGIC-53-containing vesicles by controlling the interaction of transport factors with the cytoplasmic tail of ERGIC-53.