Phylogeny and taxonomy of the Prenolepis genus‐group of ants (Hymenoptera: Formicidae)

Abstract. We investigated the phylogeny and taxonomy of the Prenolepis genus‐group, a clade of ants we define within the subfamily Formicinae comprising the genera Euprenolepis, Nylanderia, gen. rev. , Paraparatrechina, gen. rev. & stat. nov. , Paratrechina, Prenolepis and Pseudolasius. We inferred a phylogeny of the Prenolepis genus‐group using DNA sequence data from five genes (CAD, EF1αF1, EF1αF2, wingless and COI) sampled from 50 taxa. Based on the results of this phylogeny the taxonomy of the Prenolepis genus‐group was re‐examined. Paratrechina (broad sense) species segregated into three distinct, robust clades. Paratrechina longicornis represents a distinct lineage, a result consistent with morphological evidence; because this is the type species for the genus, Paratrechina is redefined as a monotypic genus. Two formerly synonymized subgenera, Nylanderia and Paraparatrechina, are raised to generic status in order to provide names for the other two clades. The majority of taxa formerly placed in Paratrechina, 133 species and subspecies, are transferred to Nylanderia, and 28 species and subspecies are transferred to Paraparatrechina. In addition, two species are transferred from Pseudolasius to Paraparatrechina and one species of Pseudolasius is transferred to Nylanderia. A morphological diagnosis for the worker caste of all six genera is provided, with a discussion of the morphological characters used to define each genus. Two genera, Prenolepis and Pseudolasius, were not recovered as monophyletic by the molecular data, and the implications of this result are discussed. A worker‐based key to the genera of the Prenolepis genus‐group is provided.     

Triage of women with equivocal or low-grade cervical cytology results: a meta-analysis of the HPV test positivity rate

Consistent evidence underlines the utility of human papillomavirus (HPV) DNA testing in the management of women with equivocal cervical cytological abnormalities, but not in case of low-grade lesions. We performed a meta-analysis including studies where the high-risk probe of the Hybrid Capture-II is used to triage these two cytological categories. The triage test-positivity rate reflects the colposcopy referral workload.Data were pooled on the HPV test positivity rate in women with atypical squamous cells of undetermined significance (ASCUS/ASC-US) or low-grade squamous intraepithelial lesions (LSIL), derived from different cytological classification systems. The meta-analysis was restricted to studies, published between 1991 and 2007. A random-effect model was applied for meta-analytical pooling and the influence of covariates on the HPV positivity rate was analyzed by meta-regression. The variation by age was assessed within individual studies since age strata were not defined uniformly. On an average, 43% (95% CI: 40–46%) of women with ASCUS/ASC-US were high-risk HPV positive (range 23–74%). In women with LSIL, the pooled positivity rate was 76% (95% CI: 71–81%; range 55–89%). In spite of considerable inter-study heterogeneity, the difference in HPV positivity between the two triage groups was large and highly significant: 32% (95% CI: 27–38%). HPV rates dropped tremendously as age and cutoffs of test positivity increased. Other factors (cytological classification system, country, continent, collection method and year of publication) had no statistically significant impact, except in LSIL triage where HPV positivity was significantly lower in European compared to American studies. Women with LSIL, especially younger women, have high HPV positivity rates suggesting limited utility of reflex HPV triaging these cases. Research is needed to identify more specific methods to triage women with low-grade squamous cervical lesions.     

Molecular basis of bacterial defense against host lysozymes: X-ray structures of periplasmic lysozyme inhibitors PliI and PliC

Lysozymes play a key role in the innate immune system of vertebrates and invertebrates by hydrolyzing peptidoglycan, a vital component of the bacterial cell wall. Gram-negative bacteria produce various types of lysozyme inhibitors that allow them to survive the bactericidal action of lysozyme when their outer membrane is permeabilized. So far, three lysozyme inhibitor families have been described: the Ivy (inhibitor of vertebrate lysozyme) family, the MliC/PliC (membrane-associated/periplasmic lysozyme inhibitor of C-type lysozyme) family, and the PliI (periplasmic lysozyme inhibitor of I-type lysozyme) family. Here, we report high-resolution crystal structures of Salmonella typhimurium PliC (PliC-St) and Aeromonas hydrophila PliI (PliI-Ah). The structure of PliI-Ah is the first in the recently discovered PliI family of lysozyme inhibitors, while the structure of PliC-St is the first structure of a periplasmic lysozyme inhibitor from the PliC/MliC family. Using small-angle X-ray scattering, we demonstrate that both PliC-St and PliI-Ah form stable dimers in solution. The functional dimer architecture of PliC-St is very different from that of the recently described MliC from Pseudomonas aeruginosa (MliC-Pa), despite the close resemblance of their monomers. Furthermore, PliI-Ah has distinctly different monomer and dimer folds compared to PliC, MliC, and Ivy proteins. Site-directed mutagenesis suggests that the inhibitory action of PliI-Ah proceeds via an insertion of a loop containing the conserved SGxY motif into the active center of I-type lysozymes. This motif is related to the functional SGxxY motif found in the MliC/PliC family.     

RETRACTED: SENSORY SUGGESTIVENESS AND LABELING: DO SOY LABELS BIAS TASTE?1

Can labels suggestively influence sensory perceptions and taste? Using a “ Phantom Ingredient” taste test, we show that the presence or absence of a labeled ingredient (soy) and the presence or absence of a health claim negatively bias taste perceptions toward a food erroneously thought to contain soy. We found a label highlighting soy content made health claims believable but negatively influenced perceptions of taste for certain segments of consumers. Our results and discussion provide better direction for researchers who work with ingredient labeling as well as for those who work with soybean products.     

Microtubules and cyclic amp in human leukocytes: on the order of things

We have shown previously that the β-adrenergic agonist isoproterenol (2μM) and the phosphodiesterase inhibitor isobutylmethylxanthine (1 mM) produce a much greater increase in cyclic AMP in human leukocytes that have been pretreated with colchicine (or with other agents that affect microtubule assembly) than in control leukocytes. The effects of colchicines were both time- and dose-dependant. These and other data suggested that the generation of cyclic AMP is normally restricted by an intact system of cytoplasmic microtubules. If so, then the same time and dose dependencies might apply to other colchicines-induced changes in leukocyte function. We have now assayed the distribution of concanavalin A (Con A)-receptor complexes on the leukocyte membrane, taking into account that leukocytes competent to assemble microtubules show a uniform distribution of surface- bound Con A whereas microtubule-deficient cells accumulate Con A in surface caps. We have found that the effect of colchicine on capping is also both time- and dose dependent, and that the dose-response relationships conform to those required to increase cyclic AMP levels. These findings provide further evidence that both colchicine-induced Con-A capping and colchicine- induced cyclic AMP generation depend upon the relaxation of constraints normally imposed by cytoplasmic microtubules upon the plasma membrane, which limit, respectively, lateral mobility of the lectin-receptor complexes, and expression of hormone-sensitive adenylate cyclase. Moreover, colchicine-induced Con-A cap formation is not affected even by very large changes in leukocyte cyclic AMP levels. Thus, elevated cyclic AMP levels do not appear to promote the dissolution of microtubules; rather, the dissolution of microtubules permits the generation of increased amounts of cyclic AMP.     

Development of Trypanosoma (M.) theileri in Tabanids

Thus far the life cycle of Trypanosoma (Megatrypanum) theileri has not been studied. We collected tabanids during the mass hatching, when only few tabanids are infected with trypanosomes. Tabanids were caught immediately after attacking a bait cow to serve as controls or after they had been allowed to engorge on the Trypanosoma (M.) theileri-infected cow. Tabanids were kept in the laboratory and used to study the developmental cycle of T. (M.) theileri in the tabanid gut. From day 1 to day 10 the presumably unfed controls and the engorged tabanids were dissected and cytological smears made from the mid- and hindgut. In total 2.6% (1/38) of the controls and 39% (23/59) of the engorged tabanids were positive for trypanosomes in the 1991 season. From day 1 to day 4 after engorgement trypanosomes were found in the midgut. Epimastigotes with a length of 29 μm on day 1 after infection multiplied by inequal division to form smaller epimastigotes of 26 μm on day 3. On day 4 morphologically indistinguishable trypanosomes of 21 μm total length were found in both mid- and hindgut. From day 5 to day 10 trypanosomes were found only in the hindgut in which the transformation to metacyclics was demonstrated, i.e. epimastigotes transformed to amastigote stages of 5 μm in total length.     

Uptake of l-Phenylalanine in Synchronous Chlorella fusca. Characterization of the Uptake System

Phenylalanine uptake in Chlorella fusca was measured, using the membrane filter technique. The cells were synchronized, and harvested at specific points of the life cycle. Experiments with autospores showed that the uptake followed saturation kinetics, with a K_m= 5 μM. V_max, was 0.1 nmol/min × 10⁷ cells. The optimum temperature for the uptake was 40°C, and the activation energy was 1700 J/mol. The uptake showed a high specificity towards l -phenylalanine; presence of the unlabelled stereoisomer did not inhibit the uptake. Uptake of l -phenylalanine was inhibited in the presence of other analogues or other amino acids, but only if they were present in concentrations considerably higher than that of L-phenylalanine. Variations in the ratio of Na4⁺ to K⁺ in the external solution during uptake experiments did not have any influence upon the uptake rate of l -phenylalanine. The cells were able to take up the amino acid against a concentration gradient. At pool maximum the ratio between internal and external amino acid concentration was 1000/1. 2,4-Dinitro-phenol inhibited the uptake completely. Exchange between internal and external l -phenylalanine could not be demonstrated. The K_m value did not change during the life cycle of the cells. The uptake rate reached a maximum at the end of the light period, and fell to a minimum just before sporulation started. It is concluded that Chlorella fusca cells have a highly specific, active uptake system for l -phenylalanine. The system is constitutive, independent on the K or Na concentration, and the mechanism of uptake does not change during the life cycle of the cells.     

Fungal survival in ensiled swine faeces

The survival of several genera of fungi was determined in the ensiled solid fraction of swine faeces after 0, 7, 14, 28 and 56 days of ensiling. The experiment had two treatments, un-ensiled and ensiled manure, in a split-plot design. The manure was distributed into 50 containers; samples, taken at the specified times, were cultured in agar potato dextrose medium, incubated, and colony forming units (CFU/g) were counted and log-transformed. The ensiling process decreased the number of CFU after 56 days. Five fungal genera were identified (Absidia spp., Aspergillus spp., Penicillium spp., Rhizopus spp. and non-fructiferous fungi), and their vulnerability to the ensiling conditions varied, although most of them slowed their growth or disappeared after 14 days of ensiling.