Phylogenetic relationships within the Alcidae (Charadriiformes: Aves) inferred from total molecular evidence

The Alcidae is a unique assemblage of Northern Hemisphere seabirds that forage by "flying" underwater. Despite obvious affinities among the species, their evolutionary relationships are unclear. We analyzed nucleotide sequences of 1,045 base pairs of the mitochondrial cytochrome b gene and allelic profiles for 37 allozyme loci in all 22 extant species. Trees were constructed on independent and combined data sets using maximum parsimony and distance methods that correct for superimposed changes. Alternative methods of analysis produced only minor differences in relationships that were supported strongly by bootstrapping or standard error tests. Combining sequence and allozyme data into a single analysis provided the greatest number of relationships receiving strong support. Addition of published morphological and ecological data did not improve support for any additional relationship. All analyses grouped species into six distinct lineages: (1) the dovekie (Alle alle) and auks, (2) guillemots, (3) brachyramphine murrelets, (4) synthliboramphine murrelets, (5) true auklets, and (6) the rhinoceros auklet (Cerorhinca monocerata) and puffins. The two murres (genus Uria) were sister taxa, and the black guillemot (Cepphus grylle) was basal to the other guillemots. The Asian subspecies of the marbled murrelet (Brachyramphus marmoratus perdix) was the most divergent brachyramphine murrelet, and two distinct lineages occurred within the synthliboramphine murrelets. Cassin's auklet (Ptychoramphus aleuticus) and the rhinoceros auklet were basal to the other auklets and puffins, respectively, and the Atlantic (Fratercula arctica) and horned (Fratercula corniculata) puffins were sister taxa. Several relationships among tribes, among the dovekie and auks, and among the auklets could not be resolved but resembled "star" phylogenies indicative of adaptive radiations at different depths within the trees.      

Responses of the specialist biological control agent,Aleochara bilineata,to vegetational diversity in canola agroecosystems

Plant biodiversity is known to affect insect populations, both herbivores and their natural enemies, and as a consequence, habitat management through increased plant species composition and abundance can be exploited for sustainable pest management. In agroecosystems where crop monocultures are the routine production practice, plant biodiversity can be increased by maintaining small populations of weeds, with potential beneficial effects arising from concomitant increases in the abundance of predator and parasitoid populations. We manipulated weed populations in both species of canola, Brassica rapa L. and Brassica napus L., to investigate responses of adults of Aleochara bilineata Gyllenhal (Coleoptera: Staphylinidae), an important natural enemy of root maggots (Delia spp., Diptera: Anthomyiidae). Larval root maggots feed on canola taproots, disrupting the flow of water and nutrients within the plants, causing substantial yield reductions. Aleochara bilineata is a predator–parasitoid that attacks all root maggot pre-imaginal life stages. Activity density of A. bilineata increased as monocotyledonous weed biomass declined. Significant preferences between canola species were observed, with A. bilineata associated most frequently with B. rapa compared with B. napus. Our research suggests that improved management of root maggot infestations in canola through enhancement of populations of the A. bilineata predator–parasitoid could be accomplished by reducing weed infestations; however, such recommendations should consider other predators in the system and the role of weeds in reducing root maggot oviposition and damage.     

Identification and mapping of polymorphic SSR markers from expressed gene sequences of barley and wheat

The growing availability of EST sequences from a range of crop plantsprovides a potentially valuable source of new DNA markers. We have examined theInternational Triticeae EST Cooperative database for the presence ofdinucleotide and trinucleotide simple sequence repeats. Analysis of 24,344 ESTsidentified 388 dinucleotide repeats and 978 trinucleotide repeats in ESTs,representing 1.6% and 4.0% of the total number of ESTs, respectively. To testthe utility and cross-species transferability of EST-derived SSR markers,primers were designed to the flanking regions of 41 barley SSRs and used toscreen 11 barley and 15 wheat varieties. Sixteen of the barley SSR markers werepolymorphic in barley and five were polymorphic in wheat. This represents arelatively high level of transferability of SSR markers between barley andwheat, which has important implications for the development of new markers andcomparative mapping of barley, wheat and other cereals. An additional 56 SSRsfrom wheat ESTs were tested in the same barley and wheat varieties. Four wheatEST SSR markers were polymorphic in wheat and one in barley. Chromosomallocations in barley and wheat were determined for the majority of polymorphicmarkers.     

Verbesina barrancae (Compositae, Heliantheae), a new species from Jalisco, Mexico

Verbesina barrancae, a new species of Compositae (Heliantheae) from Jalisco, México, is described and illustrated. It is morphologically similar toVerbesina crocata but differs in characteristics of inflorescence, anthers, and achenes as well as in form of pollen, size and number of spinules, size of colpus transversalis, and index of polar area.     

Protein phosphatase 2A controls the order and dynamics of cell-cycle transitions

Bistability of the Cdk1-Wee1-Cdc25 mitotic control network underlies the switch-like transitions between interphase and mitosis. Here, we show by mathematical modeling and experiments in Xenopus egg extracts that protein phosphatase 2A (PP2A), which can dephosphorylate Cdk1 substrates, is essential for this bistability. PP2A inhibition in early interphase abolishes the switch-like response of the system to Cdk1 activity, promoting mitotic onset even with very low levels of Cyclin, Cdk1, and Cdc25, while simultaneously inhibiting DNA replication. Furthermore, even if replication has already initiated, it cannot continue in mitosis. Exclusivity of S and M phases does not depend on bistability only, since partial PP2A inhibition prevents replication without inducing mitotic onset. In these conditions, interphase-level mitotic kinases inhibit Cyclin E-Cdk2 chromatin loading, blocking initiation complex formation. Therefore, by counteracting both Cdk1 activation and activity of mitotic kinases, PP2A ensures robust separation of S phase and mitosis and dynamic transitions between the two states.     

Series resistance compensation for whole-cell patch-clamp studies using a membrane state estimator

Whole-cell patch-clamp techniques are widely used to measure membrane currents from isolated cells. While suitable for a broad range of ionic currents, the series resistance (R(s)) of the recording pipette limits the bandwidth of the whole-cell configuration, making it difficult to measure rapid ionic currents. To increase bandwidth, it is necessary to compensate for R(s). Most methods of R(s) compensation become unstable at high bandwidth, making them hard to use. We describe a novel method of R(s) compensation that overcomes the stability limitations of standard designs. This method uses a state estimator, implemented with analog computation, to compute the membrane potential, V(m), which is then used in a feedback loop to implement a voltage clamp; we refer to this as state estimator R(s) compensation. To demonstrate the utility of this approach, we built an amplifier incorporating state estimator R(s) compensation. In benchtop tests, our amplifier showed significantly higher bandwidths and improved stability when compared with a commercially available amplifier. We demonstrated that state estimator R(s) compensation works well in practice by recording voltage-gated Na(+) currents under voltage-clamp conditions from dissociated neonatal rat sympathetic neurons. We conclude that state estimator R(s) compensation should make it easier to measure large rapid ionic currents with whole-cell patch-clamp techniques.     

Long distance dispersal in the assembly of floras: A review of progress and prospects in North America

Here, we review progress and prospects to explicitly test for long distance dispersal biogeographic events. Long distance dispersal represents a “jump” across some kind of barrier, such as a topographic feature or a zone of unsuitable climate and may include repeated jumps, or stepping‐stone dispersals. Long distance dispersals were considered integral for explaining the organization of biodiversity at large and small scales by early biogeographers, such as Darwin and Wallace. Darwin, Wallace, and others envisioned that long distance dispersals were predictable events because the vectors for dispersal, such as animals, winds, and currents, behaved in non‐random ways. However, these early biogeographers found that dispersal was hard to observe, and, later, with the advent of the theory of Continental Drift, vicariance became regarded as a better scientific explanation for the arrangement of biodiversity, because it represented a falsifiable hypothesis. Thus, long distance dispersal was reduced to a nuisance parameter in biogeography; a random possibility that could never fully be ruled out in a scenario in which evidence supported vicariance. Today, there is strong interest to more fully integrate long distance dispersal into understanding the assembly and organization of biodiversity on earth. In this review, we discuss progress and prospects for explicitly testing long distance dispersal hypotheses including through uses of molecular, morphological, paleontological, and informatics methods. We focus on hypothesis testing of long distance dispersals involved in the assembly of the flora of North America, which is a robust preliminary study system on account of its extant and extinct biodiversity being well‐catalogued.     

A high-throughput microscale method to release N-linked oligosaccharides from glycoproteins for matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis

This report describes a convenient method for the rapid and efficient release of N-linked oligosaccharides from low microgram amounts of glycoproteins. A 96-well MultiScreen assay system containing a polyvinylidene difluoride (PVDF) membrane is employed to immobilize glycoproteins for subsequent enzymatic deglycosylation. Recombinant tissue-type plasminogen activator (rt-PA) is used to demonstrate the deglycosylation of 0.1-50 micrograms of a glycoprotein. This method enabled the recovery of a sufficient amount of N-linked oligosaccharides released enzymatically with peptide N-glycosidase F (PNGaseF) from as little as 0.5 microgram rt-PA for subsequent analysis by matrix-assisted laser desorption/ionization time-of-flight (MALDI- TOF) mass spectrometry. The immobilization of rt-PA to the PVDF membrane did not sterically inhibit the PNGaseF-mediated release of oligosaccharides from rt-PA as determined by tryptic mapping experiments. Comparison of the oligosaccharides released from 50 micrograms of rt-PA by either the 96-well plate method or by a standard solution digestion procedure showed no significant differences in the profiles obtained by high-pH anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Both neutral and sialylated oligosaccharide standards spiked into wells were recovered equally as determined by HPAEC-PAD. One advantage of this approach is that reduction and alkylation can be performed on submicrogram amounts of glycoproteins with easy removal of reagents prior to PNGaseF digestion. In addition, this method allows 60 glycoprotein samples to be deglycosylated in 1 day with MALDI-TOF or HPAEC-PAD analysis being performed on the following day.