Nucleation and growth of calcite on native versus pyrolyzed oyster shell folia

The thin sheets of calcite, termed folia, that make up much of the shell of an oyster are covered by a layer of discrete globules that has been proposed to consist of agglomerations of protein and mineral. Foliar fragments, treated at 475 degrees C for 36 h to remove organic matter, were imaged by atomic force microscopy (AFM) as crystals grew on the foliar surfaces in artificial seawater at calcite supersaturations up to 52-fold. Crystals were also viewed later by scanning electron microscopy. After pyrolysis, the foliar globules persisted only as fragile remnants that were quickly washed away during AFM imaging, revealing an underlying morphology on the foliar laths of a tightly packed continuum of nanometer-scale protrusions. At intermediate supersaturations, crystal formation was seen immediately almost everywhere on these surfaces, each crystal having the same distinctive shape and orientation, even at the outset with crystals as small as a few nanometers. In contrast, nucleation did not occur readily on non-pyrolyzed foliar surfaces, and the crystals that did grow, although slowly at intermediate supersaturations, had irregular shapes. Possible crystallographic features of foliar laths are considered on the basis of the morphology of ectopic crystals and the atomic patterns of various surfaces. A model for foliar lath formation is presented that includes cycles of pulsed secretion of shell protein, removal of the protein from the mineralizing solution upon binding to mineral, and mineral growth at relatively high supersaturation over a time frame of about 1 h for each turn of the cycle.     

Molecular systematics and biogeography of Nicrophorus in part--the investigator species group (Coleoptera: Silphidae) using mixture model MCMC

Burying beetles (Silphidae: Nicrophorus) are well-known for their biparental care and monopolization of small vertebrate carcasses in subterranean crypts. They have been the focus of intense behavioral ecological research since the 1980s yet no thorough phylogenetic estimate for the group exists. The relationships among the species, and the validity of some species, are poorly understood. Here, we infer the relationships and examine species boundaries among 50 individuals representing 15 species, primarily of the investigator species group, using a mixture-model Bayesian analysis. Two mitochondrial genes, COI and COII, were used, providing 2129 aligned nucleotides (567 parsimony-informative). The Akaike Information Criterion and Bayes Factors were used to select the best fitting model, in addition to Reversible Jump MCMC, which accommodated model uncertainty. A 21 parameter, three-partition GTR + G was the final model chosen. Despite a presumed Old World origin for the genus itself, the basal lineages and immediate outgroups of the investigator species group are New World species. Bayesian methods reconstruct the common ancestor of the investigator species group as New World and imply one later transition to the Old World with two return transitions to the New World. Prior hypotheses concerning the questionable validity of four species names, Nicrophorus praedator, Nicrophorus confusus, Nicrophorus encaustus and Nicrophorus mexicanus were tested. No evidence was found for the validity of the Nicrophorus investigator synonym N. praedator. We found evidence rejecting the species status of N. confusus (NEW SYNONYM of Nicrophorus sepultor). Weak evidence was found for the species status of N. encaustus and N. mexicanus, which are tentatively retained as valid. Our results strongly reject a recently published hypothesis that Nicrophorus interruptus (NEW STATUS as valid species) is a subspecies of N. investigator.     

Visual detection of labeled oligonucleotides using visible-light-polymerization-based amplification

DNA biochip technology holds potential for highly parallel, rapid, and sensitive genetic diagnostic screening of target pathogens and disease biomarkers. A primary limitation involves a simultaneous, sequence-specific identification of low copy number target polynucleotides using a clinically appropriate detection methodology that implements only inexpensive detection instrumentation. Here, a rapid (20 min), nonenzymatic method of signal amplification utilizing surface-initiated photopolymerization is presented in glass microarray format. Visible light photoinitiators covalently coupled to streptavidin were used to bind biotin-labeled capture sequences. Amplification was achieved through subsequent contact with a monomer solution and the appropriate light exposure to generate 20-240-nm-thick hydrogel layers exclusively from spots containing the biotin-labeled DNA. An amplification factor of 10(6) to 10(7) was observed as well as a detectable response generated from as low as approximately 10(4) labeled oligonucleotides using minimal instrumentation, such as an optical microscope or CCD camera.     

Significant improvement of quality for long oligonucleotides by using controlled pore glass with large pores

A key factor influencing the quality of long oligonucleotides is the choice of controlled pore glass (CPG) which is used as a solid support during oligonucleotide synthesis. We studied the influence of CPG pore size on the quality of 75-mer oligonucleotides. Using electrophoresis and HPLC, we demonstrated failure modes that can occur at certain oligo lengths with 1000A pore size, and compared yield and purity of 75-mer oligos using 1000A and larger pore size CPG. We showed that oligonucleotides with much better quality are obtained using CPG with pore sizes of 1400A and larger. We also identified the key characteristics for CPG selection that lead to the best CPG performance.     

Arbuscular mycorrhizal fungal communities change among three stages of primary sand dune succession but do not alter plant growth

Plant interactions with soil biota could have a significant impact on plant successional trajectory by benefiting plants in a particular successional stage over others. The influence of soil mutualists such as mycorrhizal fungi is thought to be an important feedback component, yet they have shown benefits to both early and late successional plants that could either retard or accelerate succession. Here we first determine if arbuscular mycorrhizal (AM) fungi differ among three stages of primary sand dune succession and then if they alter growth of plants from particular successional stages. We isolated AM fungal inoculum from early, intermediate or late stages of a primary dune succession and compared them using cloning and sequencing. We then grew eight plant species that dominate within each of these successional stages with each AM fungal inoculum. We measured fungal growth to assess potential AM functional differences and plant growth to determine if AM fungi positively or negatively affect plants. AM fungi isolated from early succession were more phylogenetically diverse relative to intermediate and late succession while late successional fungi consistently produced more soil hyphae and arbuscules. Despite these differences, inocula from different successional stages had similar effects on the growth of all plant species. Host plant biomass was not affected by mycorrhizal inoculation relative to un‐inoculated controls. Although mycorrhizal communities differ among primary dune successional stages and formed different fungal structures, these differences did not directly affect the growth of plants from different dune successional stages in our experiment and therefore may be less likely to directly contribute to plant succession in sand dunes.     

Shift in species composition in the Anopheles gambiae complex after implementation of long‐lasting insecticidal nets in Dielmo,Senegal

Long‐lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the cornerstones of malaria vector control. However, the effectiveness of these control tools depends on vector ecology and behaviour, which also largely determine the efficacy of certain Anopheles mosquitoes (Diptera: Culicidae) as vectors. Malaria vectors in sub‐Saharan Africa are primarily species of the Anopheles gambiae complex, which present intraspecific differences in behaviour that affect how they respond to vector control tools. The focus of this study is the change in species composition in the An. gambiae complex after the implementation of LLINs in Dielmo, Senegal. The main findings referred to dramatic decreases in the proportions of Anopheles coluzzii and An. gambiae after the introduction of LLINs, and an increase in the proportion of Anopheles arabiensis. Two years after LLINs were first introduced, An. arabiensis remained the most prevalent species and An. gambiae had begun to rebound. This indicated a need to develop additional vector control tools that can target the full range of malaria vectors.     

Description of Nicrophorus efferens,new species,from Bougainville Island (Coleoptera,Silphidae, Nicrophorinae)

A new species of Nicrophorus in the nepalensis species-group, Nicrophorus efferens Sikes and Mousseau, is described from Bougainville Island in the Solomon Islands archipelago. It is distinguished from the known species of the genus Nicrophorus and its likely closest relative, Nicrophorus reticulatus Sikes and Madge, based on external morphology. A comparison among the four Nicrophorus species known from the Solomon Island archipelago and Papua New Guinea is presented.