Phylogeography and population differentiation in terrestrial island populations of Banksia arborea (Proteaceae)

The Banded Iron Formations (BIFs) of south‐western Australia are terrestrial islands characterized by high species richness and endemism. Regional endemics occur across multiple formations without inhabiting the intervening landscape matrix. We investigated whether the occurrence on BIF terrestrial islands has led to genetic differentiation among the eight known populations of the regional endemic, Banksia arborea. Genetic structure was assessed using three chloroplast DNA sequence markers and 11 nuclear microsatellite loci. Phylogenetic relationships were assessed with statistical parsimony and Bayesian methods. Dates of haplotype divergence were estimated using the time to most recent common ancestor of B. arborea and Banksia purdieana, as well as a conservative angiosperm chloroplast (cp)DNA mutation rate. Population genetic diversity and structure was assessed amongst and within populations by genotyping 24 geographically clustered individuals from each BIF and three subpopulations within the Die Hardy Range BIF. Indirect gene flow estimates were determined using a method based on the frequency of private alleles. Banksia arborea showed low genetic diversity in (cp)DNA and a complex structural pattern, with genetic differentiation of some BIF populations and an absence of differentiation amongst others, reflecting either retention of ancestral polymorphism across northern BIF populations or more recent connectivity of these populations. There was little evidence of pollen dispersal both between BIFs and within the large BIF known as Die Hardy Range. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 860–872.     

In vivo Laser Axotomy in C. elegans

Neurons communicate with other cells via axons and dendrites, slender membrane extensions that contain pre- or post-synaptic specializations. If a neuron is damaged by injury or disease, it may regenerate. Cell-intrinsic and extrinsic factors influence the ability of a neuron to regenerate and restore function. Recently, the nematode C. elegans has emerged as an excellent model organism to identify genes and signaling pathways that influence the regeneration of neurons^1-6. The main way to initiate neuronal regeneration in C. elegans is laser-mediated cutting, or axotomy. During axotomy, a fluorescently-labeled neuronal process is severed using high-energy pulses. Initially, neuronal regeneration in C. elegans was examined using an amplified femtosecond laser⁵. However, subsequent regeneration studies have shown that a conventional pulsed laser can be used to accurately sever neurons in vivo and elicit a similar regenerative response^1,3,7.We present a protocol for performing in vivo laser axotomy in the worm using a MicroPoint pulsed laser, a turnkey system that is readily available and that has been widely used for targeted cell ablation. We describe aligning the laser, mounting the worms, cutting specific neurons, and assessing subsequent regeneration. The system provides the ability to cut large numbers of neurons in multiple worms during one experiment. Thus, laser axotomy as described herein is an efficient system for initiating and analyzing the process of regeneration.     

Brooding of pelagic-type larvae in Ophiopeza spinosa: reproduction and development in a tropical ophiodermatid brittlestar

Abstract. Ophiopeza spinosa , a small ophiodermatid ophiuroid, is locally abundant in shallow water rubble habitat at Lizard Island, northern Great Barrier Reef, Australia. This species is a protantric hermaphrodite. The switch from reproduction as a male to a female is progressive, involving a simultaneous hermaphrodite as a transitional stage. Members of O. spinosa brood their young in the respiratory bursae. Cohorts of eggs (280 μm diameter) develop synchronously in the gonad and are spawned as a group into the bursa. Despite non-pelagic development, the larvae of O. spinosa are a vitellaria type typical of broadcast-spawning ophiodermatids, providing a link to an ancestral form with a dispersive larva. The vitellaria has prominent ciliary bands and swims in the same manner as pelagic vitellaria. In vitro , the larvae developed to the juvenile stage independent of the parent. There was no evidence of extraembryonic nutrition; a proportion of the maternal provisions were retained through metamorphosis. This is the first ophiuroid known to brood a pelagic-type vitellaria larva. Juveniles appear to leave the parent at the two- to three-arm segment stage, slightly larger than the newly settled juveniles of ophiodermatids with pelagic vitellariae. The presence of functional larvae in the bursa suggests a recent switch to the incubatory life history in O. spinosa and the possibility of a reversal back to a dispersive life history. O. spinosa have the potential to both brood and broadcast their young.     

Information-based methods for predicting gene function from systematic gene knock-downs

Background  

The rapid annotation of genes on a genome-wide scale is now possible for several organisms using high-throughput RNA interference assays to knock down the expression of a specific gene. To date, dozens of RNA interference phenotypes have been recorded for the nematode Caenorhabditis elegans. Although previous studies have demonstrated the merit of using knock-down phenotypes to predict gene function, it is unclear how the data can be used most effectively. An open question is how to optimally make use of phenotypic observations, possibly in combination with other functional genomics datasets, to identify genes that share a common role.     

Infection of DBA/2 or C3H/HeJ mice by intraperitoneal injection of vaccinia virus elicits activated macrophages,cytolytic and cytostatic for S91-melanoma tumor cells

Summary Murine peritoneal macrophages harvested 3–4 days after IP injection of vaccinia virus lysed S91-melanoma tumor cells in vitro; enhanced tumoricidal activity was measured with effector macrophages prepared 5–6 days after vaccinia virus infection. Treatment of virus-elicited macrophages prepared from DBA/2 mice with anti-asialo-GM1 antiserum, anti-Thy 1.2 antiserum or anti-Ia^d antiserum in the presence of complement so that cells sensitized with antibodies were lysed, did not reduce the measured level of tumoricidal activity indicating that macrophages [Ia(–); asialo GM1(–)] and not natural killer cells [asialo GM1(+); Thy 1.2(±)] or T-cells [Thy 1.2(+)] were responsible for mediating the lysis of S91-melanoma tumor cells. When incubated with virus-elicited macrophages but not thioglycollate-elicited macrophages, the ability of S91-melanoma tumor cells, to synthesize DNA was completely blocked. The results of these experiments support the view that one aspect of antitumor immunity enhanced during immunotherapy with vaccinia virus is the activation of macrophages which have cytolytic as well as cytostatic effects on melanoma tumor cells.     

Turning cells red: signal transduction mediated by erythropoietin

Erythropoietin (EPO) is the crucial cytokine regulator of red blood-cell production. Since the discovery of EPO in 1985 and the isolation of its cognate receptor four years later, there has been significant interest in understanding the unique ability of this ligand-receptor pair to promote erythroid mitogenesis, survival and differentiation. The development of knockout mice has elucidated the precise role of the ligand, receptor and downstream players in murine erythroid development. In this review, we summarize EPO-mediated signaling pathways and examine their significance in vivo.     

Responses of mycorrhizal and non-mycorrhizal<Emphasis Type="Italic"> Erica cinerea</Emphasis> and<Emphasis Type="Italic"> Vaccinium macrocarpon</Emphasis> to<Emphasis Type="Italic"> Glomus mosseae</Emphasis>

An investigation was carried out on the mycorrhizal colonisation, growth and nutrition of two members of the Ericaceae in close proximity to an arbuscular mycorrhizal (AM) association. This was undertaken by separating mycorrhizal (EM) and non-mycorrhizal (NEM) Erica cinerea and Vaccinium macrocarpon from AM (inoculated by Glomus mosseae) and non-mycorrhizal (NAM) Plantago lanceolata using a 30 µm nylon mesh in a sand culture/pot system. Ericoid mycorrhizal colonisation by Hymenoscyphus ericae on root systems of E. cinerea and V. macrocarpon was in the range 14–22% and 58–69%, respectively. The presence of AM P. lanceolata had no effect on the ericoid mycorrhizal colonisation of E. cinerea and V. macrocarpon. NEM E. cinerea showed reductions in shoot biomass and shoot nitrogen concentrations after exposure to AM P. lanceolata after incubations of 6 and 9 weeks but there were no differences in dry mass, length, and nitrogen and phosphorus concentrations of the root systems between the treatment combinations. Reductions were also found, after incubations of 6 and 9 weeks, in shoot dry mass, leaf area and shoot nitrogen concentrations of NEM V. macrocarpon in the presence of AM P. lanceolata but no changes occurred in the length and dry mass of the root systems. There were no differences in maximum photosynthesis in V. macrocarpon between treatment combinations but NEM V. macrocarpon in the presence of AM P. lanceolata had the lowest transpiration rates and stomatal conductance and the highest nitrogen- and phosphorus-use efficiencies compared with the other treatment combinations. These results are discussed in relation to the type of interaction found in these compatible and incompatible mycorrhizal associations.     

Salmonella spp., Vibrio spp., Clostridium perfringens, and Plesiomonas shigelloides in Marine and Freshwater Invertebrates from Coastal California Ecosystems

The coastal ecosystems of California are highly utilized by humans and animals, but the ecology of fecal bacteria at the land–sea interface is not well understood. This study evaluated the distribution of potentially pathogenic bacteria in invertebrates from linked marine, estuarine, and freshwater ecosystems in central California. A variety of filter-feeding clams, mussels, worms, and crab tissues were selectively cultured for Salmonella spp., Campylobacter spp., Escherichia coli-O157, Clostridium perfringens, Plesiomonas shigelloides, and Vibrio spp. A longitudinal study assessed environmental risk factors for detecting these bacterial species in sentinel mussel batches. Putative risk factors included mussel collection near higher risk areas for livestock or human sewage exposure, adjacent human population density, season, recent precipitation, water temperature, water type, bivalve type, and freshwater outflow exposure. Bacteria detected in invertebrates included Salmonella spp., C. perfringens, P. shigelloides, Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio alginolyticus. Overall, 80% of mussel batches were culture positive for at least one of the bacterial species, although the pathogens Campylobacter, E. coli-O157, and Salmonella were not detected. Many of the same bacterial species were also cultured from upstream estuarine and riverine invertebrates. Exposure to human sewage sources, recent precipitation, and water temperature were significant risk factors for bacterial detection in sentinel mussel batches. These findings are consistent with the hypothesis that filter-feeding invertebrates along the coast concentrate fecal bacteria flowing from land to sea and show that the relationships between anthropogenic effects on coastal ecosystems and the environmental niches of fecal bacteria are complex and dynamic.     

Alternate Reproductive Tactics in an African Dung Beetle, Circellium bacchus (Scarabeidae)

Male-male competition is recognized as a potent force of sexual selection. When intra-sexual competition is strong then selection theory predicts that alternative male phenotypes will evolve. Circellium bacchus is a large, hornless, ball-rolling dung beetle with extensive variation in size and subject to intense male-male contest competition. We proposed that small male C. bacchus, which are unlikely to be successful in male contest competition, would adopt the alternative reproductive tactic of sneaking copulations. This alternative tactic is likely to influence not only behavior, but morphology with an expectation that sneaking males would invest more resources in testes development. Investigation of testis allometry revealed that smaller male C. bacchus beetles had relatively larger testes than their bigger conspecifics. Furthermore, as resources may be limited during larval development, differential investment in testes development should result in adult male beetles either competing for fertilizations or for access to mates. This is seen in C. bacchus as two alternate male phenotypes; smaller beetles with a relatively low body mass invest proportionately more in testes development compared to larger, heavier form in which testes size does not scale with condition. To our knowledge this study provides the first investigation of alternative phenotypes in the reproductive tactics of a ball-rolling dung beetle species.     

The effect of two biological control agents, the weevil Neochetina eichhorniae and the mirid Eccritotarsus catarinensis on water hyacinth, Eichhornia crassipes , grown in culture with water lettuce, Pistia stratiotes

We assessed the effect of two biological control agents, the mirid Eccritotarsus catarinensis (Carvalho) and the weevil Neochetina eichhorniae (Warner), singly or in combination, on the competitive ability of their host plant, water hyacinth, Eichhornia crassipes (Mart.) Solms-Laub., grown in a screen house, in competition with another aquatic plant (Pistia stratiotes L.). Water hyacinth plant growth characteristics measured included fresh weight, leaf and petiole lengths, number of inflorescences produced, and new shoots. Without herbivory, water hyacinth was 18 times more competitive than water lettuce (across all experimental combinations of initial plant densities), as estimated from fresh weights. Both insect species, singly or in combination, reduced water hyacinth plant growth characteristics. E. catarinensis alone was less damaging than the weevil and under normal conditions, i.e., floating water hyacinth, is not expected to increase control of water hyacinth beyond that of the weevil. When combined with the weevil, half the inoculum of weevils and half the inoculum of mirids produced the same growth reduction as the full inoculum of the weevil. Under conditions where the weevils are not effective because water hyacinths are seasonally rooted in mud, the mirid, which lives entirely on leaves, should become a useful additional biological control agent. Handling Editor: John Scott.