The potential of mass rearing of Monoksa dorsiplana (Pteromalidae) a native gregarious ectoparasitoid of Pseudopachymeria spinipes (Bruchidae) in South America

In Chile and Uruguay, the gregarious Pteromalidae (Monoksa dorsiplana) has been discovered emerging from seeds of the persistent pods of Acacia caven attacked by the univoltin bruchid Pseudopachymeria spinipes. We investigated the potential for mass rearing of this gregarious ectoparasitoid on an alternative bruchid host, Callosobruchus maculatus, to use it against the bruchidae of native and cultured species of Leguminosea seeds in South America.The mass rearing of M. dorsiplana was carried out in a population cage where the density of egg-laying females per infested seed was increased from 1:1 on the first day to 5:1 on the last (fifth) day. Under these experimental conditions egg-clutch size per host increased, and at the same time the mortality of eggs laid also increased. The density of egg-laying females influenced the sex ratio which tended towards a balance of sons and daughters, in contrast to the sex ratio of a single egg-laying female per host (1 son to 7 daughters). The mean weight of adults emerging from a parasitized host was negatively correlated with the egg-clutch size, i.e. as egg-clutch size increased, adult weight decreased.All these results show that mass rearing of the gregarious ectoparasitoid M. dorsiplana was possible under laboratory conditions on an alternative bruchid host C. maculatus. As M. dorsiplana is a natural enemy of larval and pupal stages of bruchidae, the next step was to investigate whether the biological control of bruchid C. maculatus was possible in an experimental structure of stored beans.     

Stable biopassive insulation synthesized by initiated chemical vapor deposition of poly(1,3,5-trivinyltrimethylcyclotrisiloxane)

The permanent implantation of electronic probes capable of recording neural activity patterns requires long-term electrical insulation of these devices by biopassive coatings. In this work, the material properties and neural cell compatibility of a novel polymeric material, poly(trivinyltrimethylcyclotrisiloxane) (poly(V3D3)), are demonstrated to be suitable for application as permanently bioimplanted electrically insulating films. The poly(V3D3) polymeric films are synthesized by initiated chemical vapor deposition (iCVD), allowing for conformal and flexible encapsulation of fine wires. The poly(V3D3) also exhibits high adhesive strength to silicon substrates, a common material of manufacture for neural probes. The poly(V3D3) films were found to be insoluble in both polar and nonpolar solvents, consistent with their highly cross-linked structure. The films are pinhole-free and extremely smooth, having a root-mean-square (rms) roughness of 0.4 nm. The material possesses a bulk resistivity of 4 x 1015 Ohm-cm exceeding that of Parylene-C, the material currently used to insulate neurally implanted devices. The iCVD poly(V3D3) films are hydrolytically stable and are demonstrated to maintain their electrical properties under physiological soak conditions, and constant electrical bias, for more than 2 years. In addition, biocompatibility studies with PC12 neurons demonstrate that this material is noncytotoxic and does not influence cell proliferation.     

The influence of habitat and adults on the spatial distribution of juvenile corals

Population distributions are affected by a variety of spatial processes, including dispersal, intraspecific dynamics and habitat selection. Within reef‐building coral communities, these processes are especially important during the earliest life stages when reproduction provides mobility among sessile organisms and populations experience the greatest mortality bottlenecks both before and immediately after settlement. Here, we used large‐area imaging to create photomosaics that allowed us to identify and map the location of 4681 juvenile (1–5 cm diameter) and 25 902 adult (>5 cm diameter) coral colonies from eight 100‐m² plots across the forereef of Palmyra Atoll. Using metrics of density, percent cover and the relative location of each colony within each plot, we examined abundance and spatial relationships between juvenile and adult coral taxa. Within coral taxa, juvenile density was generally positively related to the numerical density and percent cover of adults. Nearest neighbor analyses showed aggregation of juveniles near adults of the same taxon for two of the focal taxa (Pocillopora and Fungiids), while all other taxa showed random spatial patterning relative to adults. Three taxa had clustered distributions of juveniles overall. Additionally, we found that on a colony level, juveniles for five of nine focal taxa (accounting for >98% of all identified juveniles) associated with a specific habitat type, with four of those five taxa favoring unconsolidated (e.g. rubble) over consolidated substrata. The general lack of clustering in juvenile corals contrasts with consistent clustering patterns seen in adult corals, suggesting that adult spatial patterns are largely driven by processes occurring after maturity such as partial colony mortality, including fission and fragmentation. The association of many taxa with unconsolidated habitat also suggests that corals may play an important role in colonizing natural rubble patches that could contribute to reef stabilization over time.     

Biodiversity of Clostridium botulinum type E associated with a large outbreak of botulism in wildlife from Lake Erie and Lake Ontario

The genetic relatedness of Clostridium botulinum type E isolates associated with an outbreak of wildlife botulism was studied using random amplification of polymorphic DNA (RAPD). Specimens were collected from November 2000 to December 2008 during a large outbreak of botulism affecting birds and fish living in and around Lake Erie and Lake Ontario. In our present study, a total of 355 wildlife samples were tested for the presence of botulinum toxin and/or organisms. Type E botulinum toxin was detected in 110 samples from birds, 12 samples from fish, and 2 samples from mammals. Sediment samples from Lake Erie were also examined for the presence of C. botulinum. Fifteen of 17 sediment samples were positive for the presence of C. botulinum type E. Eighty-one C. botulinum isolates were obtained from plants, animals, and sediments; of these isolates, 44 C. botulinum isolates produced type E toxin, as determined by mouse bioassay, while the remaining 37 isolates were not toxic for mice. All toxin-producing isolates were typed by RAPD; that analysis showed 12 different RAPD types and multiple subtypes. Our study thus demonstrates that multiple genetically distinct strains of C. botulinum were involved in the present outbreak of wildlife botulism. We found that C. botulinum type E is present in the sediments of Lake Erie and that a large range of bird and fish species is affected.     

Nuclear membrane receptors for ET-1 in cardiovascular function

Plasma membrane endothelin type A (ET(A)) receptors are internalized and recycled to the plasma membrane, whereas endothelin type B (ET(B)) receptors undergo degradation and subsequent nuclear translocation. Recent studies show that G protein-coupled receptors (GPCRs) and ion transporters are also present and functional at the nuclear membranes of many cell types. Similarly to other GPCRs, ET(A) and ET(B) are present at both the plasma and nuclear membranes of several cardiovascular cell types, including human cardiac, vascular smooth muscle, endocardial endothelial, and vascular endothelial cells. The distribution and density of ET(A)Rs in the cytosol (including the cell membrane) and the nucleus (including the nuclear membranes) differ between these cell types. However, the localization and density of ET-1 and ET(B) receptors are similar in these cell types. The extracellular ET-1-induced increase in cytosolic ([Ca](c)) and nuclear ([Ca](n)) free Ca(2+) is associated with an increase of cytosolic and nuclear reactive oxygen species. The extracellular ET-1-induced increase of [Ca](c) and [Ca](n) as well as intracellular ET-1-induced increase of [Ca](n) are cell-type dependent. The type of ET-1 receptor mediating the extracellular ET-1-induced increase of [Ca](c) and [Ca](n) depends on the cell type. However, the cytosolic ET-1-induced increase of [Ca](n) does not depend on cell type. In conclusion, nuclear membranes' ET-1 receptors may play an important role in overall ET-1 action. These nuclear membrane ET-1 receptors could be targets for a new generation of antagonists.     

Movement of Weed Seeds in Reclamation Areas

The presence or absence of obstructions can affect seed dispersal. Reclamation activities often cause changes in the type and amount of such obstructions. The consequences of removing obstructions on the dispersal of undesirable species are unknown. In western North America, reclamation may often proceed in areas surrounded by the invasive Bromus tectorum L. (cheatgrass). The importance of preventing cheatgrass seed dispersal from surrounding landscapes is an unknown factor in reducing cheatgrass competition in these areas. I quantified cheatgrass seed dispersal in the early stages of reclamation, when soils were bare. Four groups of 100 sterilized, fluorescently marked cheatgrass seeds were released in each of three areas in NW Colorado, USA. Seeds were located at night using blacklights four times over 14 days, and the distance between each seed and the point of release was measured. Across sites, dispersal distance averaged 2.4 m, 5% of seeds traveled further than 7.6 m, and maximum recorded distance was 20.8 m. Maximum distances reported in this study are 50‐fold higher than previously reported for intact sagebrush ecosystems. I suggest that the difference is due to a lack of impediments to secondary dispersal on bare soil. When reclamation areas are surrounded by weeds such as cheatgrass, seeds dispersing from the perimeter may influence restoration outcome.     

The role of AMPK and mTOR in nutrient sensing in pancreatic beta-cells

The AMP-activated protein kinase (AMPK) is a central regulator of the energy status of the cell, based on its unique ability to respond directly to fluctuations in the ratio of AMP:ATP. Because glucose and amino acids stimulate insulin release from pancreatic beta-cells by the regulation of metabolic intermediates, AMPK represents an attractive candidate for control of beta-cell function. Here, we show that inhibition of AMPK in beta-cells by high glucose inversely correlates with activation of the mammalian Target of Rapamycin (mTOR) pathway, another cellular sensor for nutritional conditions. Forced activation of AMPK by AICAR, phenformin, or oligomycin significantly blocked phosphorylation of p70S6K, a downstream target of mTOR, in response to the combination of glucose and amino acids. Amino acids also suppressed the activity of AMPK, and this at a minimum required the presence of leucine and glutamine. It is unlikely that the ability of AMPK to sense both glucose and amino acids plays a role in regulation of insulin secretion, as inhibition of AMPK by amino acids did not influence insulin secretion. Moreover, activation of AMPK by AICAR or phenformin did not antagonize glucose-stimulated insulin secretion, and insulin secretion was also unaffected in response to suppression of AMPK activity by expression of a dominant negative AMPK construct (K45R). Taken together, these results suggest that the inhibition of AMPK activity by glucose and amino acids might be an important component of the mechanism for nutrient-stimulated mTOR activity but not insulin secretion in the beta-cell.     

An assay for the bacterial sweet spot

Glycosylation is critical for the proper folding and function of many eukaryotic proteins. A lack of native asparagine-linked glycosylation machinery has hampered production of eukaryotic proteins in Escherichia coli. This commentary by Danielle Tullman-Ercek discusses the work of Matt Delisa's group on an assay using beta-lactamase activity as a reporter for successful glycoprotein folding in the periplasm of E. coli. See accompanying article by Mansell et al. DOI: 10.1002/biot.201300026