Closing the mitochondrial circle on paraphyly of the Monogenea (Platyhelminthes) infers evolution in the diet of parasitic flatworms

Relationships between the three classes of Neodermata (parasitic Platyhelminthes) are much debated and restrict our understanding of the evolution of parasitism and contingent adaptations. The historic view of a sister relationship between Cestoda and Monogenea (Cercomeromorphae; larvae bearing posterior hooks) has been dismissed and the weight of evidence against monogenean monophyly has mounted. We present the nucleotide sequence of the complete mitochondrial (mt) genome of Benedenia seriolae (Monogenea: Monopisthocotylea: Capsalidae), the first complete non-gyrodactylid monopisthocotylean mt genome to be reported. We also include nucleotide sequence data for some mt protein coding genes for a second capsalid, Neobenedenia sp. Analyses of the new mt genomes with all available platyhelminth mt genomes provide new phylogenetic hypotheses, which strongly influence perspectives on the evolution of diet in the Neodermata. Our analyses do not support monogenean monophyly but confirm that the Digenea and Cestoda are each monophyletic and sister groups. Epithelial feeding monopisthocotyleans on fish hosts are basal in the Neodermata and represent the first shift to parasitism from free-living ancestors. The next evolutionary step in parasitism was a dietary change from epithelium to blood. The common ancestor of Digenea + Cestoda was monogenean-like and most likely sanguinivorous. From this ancestral condition, adult digeneans and cestodes independently evolved dietary specialisations to suit their diverse microhabitats in their final vertebrate hosts. These improved perspectives on relationships fundamentally enhance our understanding of the evolution of parasitism in the Neodermata and in particular, the evolution of diet.     

SOME MORPHOLOGICAL VARIATIONS IN THE DIATOM CYMBELLA CISTULA1,2

Several populations of Cymbella cistula (Ehr.) Kirchn. were studied. An epiphytic population contained smaller specimens than any reported by recent authors. The size range of members of the epiphytic population included specimens as small as 24 μ long by 11 μ wide. These small specimens could be mistaken for C. cistula var. maculata (Kütz.) V. H., but differ in having isolated puncta, which, may be indistinct, and somewhat coarser striae.     

Evaluation of biodegradation potential of foam embedded Burkholderia cepacia G4

Foam embedded Burkholderia cepacia G4 removed up to 80 % and 60 % of a 3 mg/l solution of trichloroethylene (TCE) and a 2 mg/l solution of benzene, respectively. Removal of TCE and benzene decreased more than 50% when readily metabolizable carbon sources were present. TCE degradative activity was observed with G4 cells induced with phenol or benzene prior or after immobilization of cells. © Rapid Science Ltd. 1998     

Seasonal prevalence of mosquitoes collected from light traps in the Republic of Korea, 2007

Adult mosquito surveillance was conducted using New Jersey light traps from 1 May to 15 October during 2007 at 14 US Army and three Air Force installations and two US Army training sites located in six provinces in the Republic of Korea to determine threshold levels to initiate pesticide applications based on trap indices. A total of 24 013 adult mosquitoes (19 763 [82.3%] females and 4250 [17.1%] males) comprising 16 species (including five members of the Anopheles Hyrcanus Group) and belonging to seven genera were collected. Females of the most commonly collected species were members of the Anopheles Hyrcanus Group (52.1%), followed by, Culex tritaeniorhynchus Giles (20.6%), Culex pipiens Coquillett (13.8%), and Aedes vexans nipponii (Theobald) (11.6%). Trap indices varied widely for species over their range, due in part, to geographical distribution and degree of association with urban or rural communities.     

Activation of murine lymphocytes by cyclic guanosine 3′,5′-monophosphate: Specificity and role in mitogen action

Cyclic guanosine 3′,5′-monophosphate (cyclic GMP) stimulates nucleic acid synthesis in lymphocytes, and has been implicated as the intracellular effector of the actions of mitogenic agents on these cells. In the present study, we examined the specificity of the mitogenic activity of cyclic GMP and of its 8-bromo (Br) derivatives, and the effects of the T cell mitogens, concanavalin A, phytohemagglutinin, and staphylococcal entertoxin B (SEB) on the cyclic GMP content and guanylate cyclase activity of mouse splenic lymphocytes. Cyclic GMP and guanosine modestly increased the incorporation of [³H]thymidine into DNA by cultured lymphocytes, but were far less effective than their 8-Br-derivatives. However, on a molar basis the mitogenic activity of both 8-Br-guanosine and 8-Br-5′-GMP exceeded that of 8-Br-cyclic GMP, when tested in the presence and absence of serum in the culture media. Combined addition of maximal doses of these nucleotides did not give additive stimulatory effects, suggesting an action on a common subpopulation of cells, and possibly a common mechanism. By contrast, cyclic AMP, 8-Br-cyclic AMP, 8-Br-adenosine, cholera toxin and prostaglandin E₁ suppressed both basal [³]thymidine incorporation and stimulation of this parameter by T-cell line mitogens and the guanosine nucleotides. Rapid effects of concanavalin A, phytohemagglutinin, SEB, guanosine, 5′-GMP, 8-Br-guanosine, and 8-Br-5′-GMP on the cyclic GMP content of murine lymphocytes could not be demonstrated. Similarly, concanalin A, phytohemagglutinin and SEB failed to alter guanylate cyclase activity when added directly to cellular homogenates or pre-incubated with intact cels. Conversely, carbamylcholine rapidly increased lymphocyte cyclic GMP but was not mitogenic.These results are consistent with the hypothesis that cyclic GMP and cyclic AMP are antagonistic in their influence on lymphocyte mitogenesis. However, they also demonstrate that related nucleotides are more potent mitogens than cyclic GMP and suggest that activation of murine lymphocytes by concanavalin A, phytohemagglutinin and SEB may not be mediated by rapid increases in cellular cyclic GMP content. Since high concentrations of exogenous cyclic GMP and related nucleotides must be used to influence DNA synthesis, the biologic significance of this effect remains uncertain.     

Effects of maturation and aging on collateral ventilation in sheep

We studied collateral ventilation as a function of age by measuring the resistance (Rcoll) and time constant (Tcoll) of collateral airflow in young (2-10 mo), mature (16-24 mo), and old sheep (6-13 yr). Rcoll was 0.50 +/- 0.11 cmH2O X ml-1 X min (SE) in young sheep and decreased significantly to 0.05 +/- 0.02 and 0.02 +/- 0.01 cmH2O X ml-1 X min in mature and old sheep, respectively. Tcoll was 34.4 +/- 7.9 (SE) s in young sheep and decreased to 5.7 +/- 0.9 and 10.2 +/- 3.1 s in mature and old sheep, respectively. We conclude that a marked decrease in Rcoll and Tcoll occurs between birth and maturity but changes little with further aging. In the young an increased resistance and time constant of collateral airflow may accentuate ventilation perfusion imbalance and impair the removal of secretions in disease states.     

Use of Pyocin 78-C2 in the Treatment of Pseudomonas aeruginosa Infection in Mice

Purified pyocin, administered parenterally to mice infected with sensitive strains of Pseudomonas aeruginosa, afforded significant protection against two of the three strains studied.     

Assembly and disassembly properties of microtubules formed in the presence of GTP, 5'-guanylyl imidodiphosphate, and 5'-guanylyl methylenediphosphate

We have examined the properties of microtubules formed in the presence of GTP, 5'-guanylyl imidodiphosphate (GMPP(NH)P), and 5'-guanylyl methylenediphosphate (GMPP(CH2)P) to identify features of the assembly or disassembly reactions uniquely related to hydrolysis. The assembly of microtubules with GTP or GMPP(NH)P was similar in terms of rates and extents of assembly, the length distributions, and podophyllotoxin-induced depolymerization. The greater rapidity of GMPP(CH2)P-supported assembly, however, resulted in shorter, more numerous microtubules and the rate of podophyllotoxin-induced depolymerization was consistent with an increased number of concentration of microtubules. Experiments with GTP or analogue incorporation and release indicated that GTP-tubule turnover corresponded to a rate of about 8% of the microtubule protein taken up or released per h. With GMPP(NH)P- and GMPP(CH2)P-tubules, the rates of label uptake by unlabeled microtubules were considerably lower than observed with guanosine triphosphate. We suggest that exchange experiments can reflect contributions from head-to-tail polymerization and polymer length redistribution, but it is not as yet possible to evaluate the relative contributions of each process.