Pathways for algal recolonisation in ephemeral streams

Our prior research showed that stream algae regrow rapidly from dry biofilm and suggested that ephemeral streams that lacked any permanent surface water showed much lower algal regrowth once streams recommenced flow. To determine whether the latter was true in a broader range of streams, we: sampled and cultured algae from a range of drought refuges in 9 streams, sampled algae from 18 streams in the week after flow recommenced and conducted a transplant experiment to identify the source of algal colonists. We found little specificity amongst algal taxa for different drought refuges and that the dry biofilm and leaf litter combined accounted for all taxa that regrew after flows recommenced. Regulation of streams with some permanent surface water is associated with increased algal regrowth from dry biofilm, not the presence of permanent surface water alone. Sources of algal recolonization may be dependent on the dominant algal composition within the stream, at a coarse taxonomic level.

Pathways for algal recolonization in seasonally-flowing streams

1. In semi-arid climates, seasonally-flowing streams provide most of the water required for human use, but knowledge of how water extraction affects ecological processes is limited. Predicted alterations in stream flows associated with the impacts of climate change further emphasize the need to understand these processes. Benthic algae are an important base for stream food webs, but we have little knowledge of how algae survive dry periods or respond to altered flow regimes.

2. We sampled 19 streams within the Grampians National Park, south-eastern Australia and included four components: a survey of different drought refuges (e.g. permanent pools, dry biofilm on stones and dry leaf packs) and associated algal taxa; a survey of algal regrowth on stones after flows recommenced to determine which refuges contributed to regrowth; reciprocal transplant experiments to determine the relative importance of algal drift and regrowth from dry biofilm in recolonization; direct measurement of algal drift to determine taxonomic composition in relation to benthic assemblage composition.

3. Algae showed little specificity for drought refuges but did depend on them; no species were found that were not present in at least one of the perennial pool, dry biofilm or leaf pack refuges. Perennial pools were most closely correlated with the composition of algal assemblages once flows resumed, but the loss or gain of perennial pools that might arise from stream regulation is unlikely to affect the composition of algal regrowth. However, regulated streams were associated with strong increases in algal density in dry biofilm, including increased densities of Cyanobacteria.

4. A model for algal recolonization in seasonally-flowing streams identified three pathways for algal recolonization (drift-dependent, dry biofilm-dependent and contributions from both), depending on whether streams are diatom-dominated or dominated by filamentous algae. The model predicted the effects of changes to stream flow regimes on benthic algal recolonization and provides a basis for hypotheses testable in streams elsewhere.

Hydrodynamics, nutrients and algae of Fitzroy and Merri River estuaries

Various physical, biological and chemical attributes were investigated for the Fitzroy and Merri River estuaries. This research found algal communities were most influenced by high nitrogen concentrations at times of low flow. Mangement of nutrients within each catchment is therefore of high importance to reduce the possibility of future blooms.

Sexual abuse in 'Disgrace' and 'Cereus Blooms at Night': the case for hope

Abuse is rife in Disgrace by J.M. Coetzee and Cereus Blooms at Night by Shani Mootoo. Sexual violence is in both narratives, part of their richly textured social, emotional and political worlds. Fiction involving various traumas seems bleak, almost hopeless, perhaps weighted by sadness. Yet both these novels, even through depictions of rupturing, disruptive rape, trigger a recognition of possibility and potential among characters and perhaps readers. It is in this open ended potential for betterment of some kind that hope lies. What is the nature of hope and to what extent is it present in these novels? In this paper, I explore the emotion of hope in relation to the notion of becoming as elaborated on by Gilles Deleuze and Felix Guattari particularly in A Thousand Plateaus. They expound on Remy Chauvin‟s term “aparallel evolution” in relation to becoming (Deleuze and Guattari, 11). Deleuze also states that becoming is not a “phenomena of imitation or assimilation”. Rather, it is an encounter, “a double capture” (Deleuze and Parnet 2) between heterogeneous elements. There is no end or destination in becoming; it is constant change. I examine the transformative potential of becoming to elicit signs of hope in these novels. David Lurie, the self-absorbed womaniser and arguably rapist, becomes-dog by the end of Disgrace. How does this contribute to any sense of redemption and consequently hope? And how does hope emanate from the beaten, broken, brutally raped Mala Ramchandin in Cereus Blooms at Night? At heart, this paper is an acknowledgment of the unique relation literature has with life and the enriching insight that it may provide into the expression of hope.

Population-level perspectives on global change : genetic and demographic analyses indicate various scales, timing, and causes of scyphozoan jellyfish blooms

Whether a perceived increase in the abundance of jellyfishes is related to changing marine environments has been considered primarily using large-scale analyses of multi-species assemblages. Yet jellyfish blooms-rapid increases in the biomass of pelagic coelenterate species-are single-species demographic events. Using published and new genetic analyses and population surveys, we investigate whether there may be a critical knowledge gap between the scales of recent analyses and the scales of natural phenomena. We find that scyphomedusae may show population genetic structure over scales of tens to hundreds of kilometers, that environments vary regionally and locally, and that populations of medusae can display uncorrelated dynamics on these scales. These findings suggest genetic differences between populations and/or environmental differences between sites are important determinants of population dynamics in these jellyfishes. Moreover, the local abundance of medusae may be most strongly correlated with preceding rather than current local environmental conditions, indicating there is a cumulative time-course to the formation of 'blooms'. Broad-scale macro-ecological analyses will need to build from coordinated, long-term, fine-grained studies to synthesize, rather than mask, population-level phenomena in larger-scale analyses. © 2014 Springer International Publishing Switzerland.

Ultra-small algal chitosan ocular nanoparticles with iron-binding milk protein prevents the toxic effects of carbendazim pesticide

AIM: To fabricate ultra-small algal chitosan nanoparticles (US CS NPs) for efficient delivery of bovine lactoferrin (bLf) to ocular tissues through topical administration to prevent carbendazim-induced toxicity. MATERIALS & METHODS: Rat eye model was used to evaluate the in vivo biodistribution the US CS NPs and bovine eye model was used for evaluating ex vivo biodistribution. Human lens epithelial cell line (HLEB-3) model was used to evaluate the in vitro toxicity, uptake mechanism and in vitro efficacy of the synthesized bLf-US CS NPs over carbendazim-induced ocular toxicity. RESULTS: The in vivo and ex vivo biodistribution results suggest that the ultra-small CS NPs efficiently internalize into the ocular tissues within 1 h after administering topically. Ultra-small algal nanocarriers to encapsulate bioactive antioxidant bLf protein and evaluated its potential in inhibiting carbendazim-induced human lens cell apoptosis and oxidative stress. CONCLUSION: US CS NPs could be explored for their potential for delivering various ocular drugs through topical administration for other eye diseases including cataract, glaucoma and age-related macular degeneration.

Apicoplast-localized lysophosphatidic acid precursor assembly is required for bulk phospholipid synthesis in toxoplasma gondii and relies on an algal/plant-like glycerol 3-phosphate acyltransferase

Most apicomplexan parasites possess a non-photosynthetic plastid (the apicoplast), which harbors enzymes for a number of metabolic pathways, including a prokaryotic type II fatty acid synthesis (FASII) pathway. In Toxoplasma gondii, the causative agent of toxoplasmosis, the FASII pathway is essential for parasite growth and infectivity. However, little is known about the fate of fatty acids synthesized by FASII. In this study, we have investigated the function of a plant-like glycerol 3-phosphate acyltransferase (TgATS1) that localizes to the T. gondii apicoplast. Knock-down of TgATS1 resulted in significantly reduced incorporation of FASII-synthesized fatty acids into phosphatidic acid and downstream phospholipids and a severe defect in intracellular parasite replication and survival. Lipidomic analysis demonstrated that lipid precursors are made in, and exported from, the apicoplast for de novo biosynthesis of bulk phospholipids. This study reveals that the apicoplast-located FASII and ATS1, which are primarily used to generate plastid galactolipids in plants and algae, instead generate bulk phospholipids for membrane biogenesis in T. gondii.