Cucujolide biosynthesis in the merchant and rusty grain beetles

Most known aggregation pheromones of cucujid grain beetles are macrolides called “cucujolides”. It has recently been shown by us that cucujolide I[4(E),8(E)-4,8-dimethyldecadien-10-olide] is of terpenoid origin, and that cucujolide II[3(Z)-dodecen-11-olide] is of fatty acid. The objectives of this study were to determine if farnesol could serve as a precursor of cucujolide I in vivo; to study the conversion of fatty acids to cucujolide II; and to study the stereochemistry of the lactonization reactions leading to cucujolides I and II. Experiments were performed through application of stable isotope-labeling techniques, using the merchant grain beetle, Oryzaephilus mercator (Fauvel), and/or the rusty grain beetle, Cryptolestes ferrugineus (Stephens), as study insects. Exogenous (E,E)-farnesol was converted to cucujolide I. Dual-labeling studies with D and ¹⁸O indicate that this conversion proceeded with retention of the hydroxyl oxygen. Lauric and 11-hydroxydodecanoic acids were not effective precursors of cucujolide II, whereas 3(Z)-dodecenoic acid and 11-hydroxy-3(Z)-dodecenoic acid were effective precursors of cucujolide II. These data support the hypothesis that the biosynthetic route from fatty acids to cucujolide II involves chain shortening through β-oxidation to a 3(Z)-dodecenoic acid intermediate and oxidation at carbon-11 to form a 11-hydroxy-3(Z)-dodecenoic acid intermediate, followed by cylization. Dual-labeling studies with D and ¹⁸O indicate that this cyclization proceeded with retention of the C-11 hydroxyl of the 11-hydroxy-3(Z)-dodecenoic acid intermediate.     

Collaborating with recreational fishers to inform fisheries management: Estimating population abundance for an iconic freshwater crayfish

Can the abundance of fish populations be effectively determined by the collection of scientific research with support from recreational fishers? Collecting and analysing fishing data from recreational fishers to aid management are not new; however, engaging fishers in a scientific survey design to produce specific population estimates is rarely undertaken. We engaged recreational fishers to assist with field sampling to provide an estimate Murray Crayfish (Euastacus armatus von Martens, 1866) abundance at three sites on the Edward River which were recently impacted by an extreme blackwater disturbance. Employing mark‐resight models, fishers undertook crayfish surveys and produced research data which estimated adult population sizes of Murray Crayfish in the studied reaches ranging between 94.27 ± 24.72 individuals (Below Stevens) and 450.01 ± 175.30 individuals (Twin Rivers). Both the effective undertaking of the mark‐resight designs in collaboration with fishers and acquiring population abundance estimates for Murray Crayfish in a river reach are concepts which have not previously been published and are important attributes for the management of aquatic species.     

FlyXCDB—A Resource for Drosophila Cell Surface and Secreted Proteins and Their Extracellular Domains

Genomes of metazoan organisms possess a large number of genes encoding cell surface and secreted (CSS) proteins that carry out crucial functions in cell adhesion and communication, signal transduction, extracellular matrix establishment, nutrient digestion and uptake, immunity, and developmental processes. We developed the FlyXCDB database (http://prodata.swmed.edu/FlyXCDB) that provides a comprehensive resource to investigate extracellular (XC) domains in CSS proteins of Drosophila melanogaster, the most studied insect model organism in various aspects of animal biology. More than 300 Drosophila XC domains were discovered in Drosophila CSS proteins encoded by over 2500 genes through analyses of computational predictions of signal peptide, transmembrane (TM) segment, and GPI-anchor signal sequence, profile-based sequence similarity searches, gene ontology, and literature. These domains were classified into six classes mainly based on their molecular functions, including protein–protein interactions (class P), signaling molecules (class S), binding of non-protein molecules or groups (class B), enzyme homologs (class E), enzyme regulation and inhibition (class R), and unknown molecular function (class U). Main cellular functions such as cell adhesion, cell signaling, and extracellular matrix composition were described for the most abundant domains in each functional class. We assigned cell membrane topology categories (E, secreted; S, type I/III single-pass TM; T, type II single-pass TM; M, multi-pass TM; and G, GPI-anchored) to the products of genes with XC domains and investigated their regulation by mechanisms such as alternative splicing and stop codon readthrough.     

Type‐III secretion pore formed by flagellar protein FliP

During assembly of the bacterial flagellum, protein subunits that form the exterior structures are exported through a specialized secretion apparatus energized by the proton gradient. This category of protein transport, together with the similar process that occurs in the injectisomes of gram‐negative pathogens, is termed type‐III secretion. The membrane‐embedded part of the flagellar export apparatus contains five essential proteins: FlhA, FlhB, FliP, FliQ and FliR. Here, we have undertaken a variety of experiments that together support the proposal that the protein‐conducting conduit is formed primarily, and possibly entirely, by FliP. Chemical modification experiments demonstrate that positions near the center of certain FliP trans‐membrane (TM) segments are accessible to polar reagents. FliP expression sensitizes cells to a number of chemical agents, and mutations at predicted channel‐facing positions modulate this effect. Multiple assays are used to show that FliP suffices to form a channel that can conduct a variety of medium‐sized, polar molecules. Conductance properties are strongly modulated by mutations in a methionine‐rich loop that is predicted to lie at the inner mouth of the channel, which might form a gasket around cargo molecules undergoing export. The results are discussed in the framework of an hypothesis for the architecture and action of the cargo‐conducting part of the type‐III secretion apparatus.     

Overview,opportunities and outlook for Australian spiny lobster fisheries

Australia’s lobster fisheries are relatively small in volume (9500t) compared with global production (289,000t), but are the country’s most valuable in terms of both overall production and value of export (2014 Gross Value of Production of $610 million AUD). Further, they support commercial, recreational and indigenous fishers along most of the continent’s coastline. Here we review similarities and key differences between these lobster fisheries, based on biological characteristics, fishery data collection, assessment and management methods, and supply chain considerations. A diverse range of palinurid lobsters occur in Australia, but only three genera, distributed across eight different management jurisdictions, support significant fisheries. Catches of western rock lobster Panulirus cygnus dominate landings (61%), followed by southern rock lobster Jasus edwardsii, tropical lobster Panulirus ornatus and the eastern rock lobster Sagmariasus verreauxi. Large-scale environmental influences such as climate change are impacting on these fisheries in similar or different ways forcing new management and raising the need for greater resilience in current supply chains. Although these are separate fisheries, the integrated nature of the dominant Chinese export markets suggests potentially important economic and market-related interactions. Our overview highlights the critical role of continued monitoring of recruitment pulses, in combination with robust harvest strategies, to ensure that harvests respond adequately and fisheries achieve biological and economic sustainability. Approaches that also include socio-cultural considerations (triple bottom line) are important given many fisheries include indigenous Australians. Our integrated analysis of Australian lobster fisheries highlights differences and similarities with spiny lobster fisheries worldwide and lessons from opportunities, including adapting to new free trade agreements, enhancing the reputation of wild lobsters as a whole, sharing expertise, and better alignment of supply and demand.     

A comparative cytogenetic study of 17 <Emphasis Type="Italic">Avena</Emphasis> species using Am1 and (GAA)<Subscript>6</Subscript> oligonucleotide FISH probes

Fluorescence in situ hybridization (FISH) was performed to explore the genomic and species relationships among 17 taxa using Am1 (oligo-Am1) and (GAA)₆ oligonucleotide probes. Oligo-Am1 (51 bp) hybridized strongly over almost the entire length of all chromosomes in the C genome. Six translocations between the A and C genomes were found in AACC tetraploids and AACCDD hexaploids, four minor translocations between the C and D genomes were found in AACCDD hexaploids, and two large translocations between the C and D genomes were found in A. sativa. In the 17 Avena species, (GAA)₆ regions mainly appear as sharp, thin bands at pericentromeric positions in the A, B, and C genomes and at termini in the B genome. However, no (GAA)₆ signal loci were observed in the D genome. The (GAA)₆ signal number was constant in both AA and CC diploids, though with different signal intensities. The (GAA)₆ signal pattern was diverse in AABB, AACC, and AACCDD polyploids, with each species exhibiting one signal pattern. The (GAA)₆ signal number was consistent in diploids and varied in polyploids, describing an intragenomic relationship among Avena species. This study is the first to test these two oligonucleotides, which are based on synthesized repeat units (18–51 bp), in the genus Avena. Our approach paves the way for future studies in which FISH probes can be used to assign other landmark genomic sequence oligonucleotides to physical chromosomes.     

Phosphorus deficiency increases nodule phytase activity of faba bean–rhizobia symbiosis

The effect of phosphorus deficiency on growth, nodulation and phytase activity was studied in glasshouse for four symbioses involving two faba bean cultivars, namely Aguadulce (AG) and Alfia (AL), and two local rhizobial isolates, namely RhF1 and RhF2. The P deficiency was applied by adding 25 µmol of Pi plant^?1 week^?1 to nutrient solution, whereas the sufficient control received 125 µmol plant^?1 week^?1. At flowering stage, the plants were harvested for assessment of growth and nodulation, P and N contents in organs as well as activities of phytase and phosphatases in nodules. The latter were highly stimulated by P deficiency, particularly for AL–RhF1 symbiosis for which shoot growth and P content were not affected by P deficiency. Using in situ RT-PCR, the expression of a plant histidine acid phytase HAP gene was detected in the nodule cortex under P deficiency. It is concluded that high nodule phytase activity constitutes a mechanism for faba bean plants to adapt their nitrogen fixation to P deficiency.     

A review of <Emphasis Type="Italic">Solanum mauritianum</Emphasis> biocontrol: prospects,promise and problems: a way forward for South Africa and globally

The invasive tree Solanum mauritianum Scopoli remains one of the world’s most widespread environmental weeds. Despite biocontrol providing one of the few viable long-term solutions to tackling S. mauritianum invasions globally, only South Africa and, more recently, New Zealand, have programmes in place. Ongoing biocontrol efforts against S. mauritianum are reviewed here with particular reference to South Africa. The South African programme has suffered a troubled history, with considerable research efforts culminating in the eventual release and establishment of only two insect agents, Gargaphia decoris Drake and Anthonomus santacruzi Hustache. The difficulties experienced have hindered research into new agents, causing apprehension in using biocontrol internationally. However, recent studies have demonstrated that biocontrol may be deserving of renewed investment, particularly within an integrated management context. In this review, we advocate for the revival of the S. mauritianum biocontrol programme in South Africa, and discuss possible avenues for future research internationally.     

Retention of Nitrogen Following Wildfire in a Chaparral Ecosystem

Wildfires alter nitrogen (N) cycling in Mediterranean-type ecosystems, resetting plant and soil microbial growth, combusting plant biomass to ash, and enhancing N availability in the upper soil layer. This ash and soil N pool (that is, wildfire N) is susceptible to loss from watersheds via runoff and leaching during post-fire rains. Plant and soil microbial recovery may mitigate these losses by sequestering N compounds in new biomass, thereby promoting landscape N retention in N-limited chaparral ecosystems. We investigated the relative balance between wildfire N loss, and plant and soil microbial N uptake and stream N export for an upland chaparral watershed in southern California that burned (61%) in a high-intensity wildfire in 2009 by using a combination of stream, vegetation, soil microbial, and remote sensing analyses. Soil N in the burn scar was 440% higher than unburned soil N in the beginning of the first post-fire wet season and returned within 66 days to pre-fire levels. Stream N export was 1480% higher than pre-fire export during the first post-fire rain and returned within 106 days over the course of the following three rainstorms to pre-fire levels. A watershed-scale N mass balance revealed that 52% of wildfire N could be accounted for in plant and soil microbial growth, whereas 1% could be accounted for in stream export of dissolved nitrogen.     

Diel variability in nitrogenous nutrient uptake at photic and subphotic depths

Diel patterns in nitrogen uptake were investigated at threepositions along an offshore orientated transect in the SouthernBenguela Upwelling System. Both photic and sub-photic depthswere targeted in the ¹⁵N tracer experiments. An appreciableproportion of nitrogen uptake was found to occur at sub-photicdepths during both the day and the night. The importance ofsub-photic uptake decreased offshore but remained non-trivialat all locations. Although NH₄ dominated this uptake, NO₃ removalat depth did account for an important fraction of the totalwater column NO₃ uptake, particularly over the shelf at night.For example, sub-photic NO₃ uptake at night for the inshorestations averaged 68% of the total for the water column decliningto 3% offshore. The impact of sub-photic NO₄ uptake on new productionwill depend on whether the NO₃ is incorporated into primaryassimilation pathways or is transported to the sediments ininorganic form. Whereas sub-photic/photic uptake decreased offshore,night/day uptake ratios increased with distance from the coast,approaching unity at the offshore location. This effect wasmost obvious for the photic communities This finding supportsthe belief that dark nitrogen uptake assumes increased importanceas nutrients become less available. Photic zone f-ratios weresmaller at night (mean = 0.14) than during the day (mean = 0.28)indicating a greater importance of reduced nitrogen uptake duringthe dark hours This emphasis on NH₄ utilization at night canbe explained purely in terms of energy efficiency. Such die1phasing in f-ratios needs to be accounted for in scaling totalproduction to new proifudon.