Photoinduced DNA and Protein Cleavage Activity of Ferrocene-Conjugated Ternary Copper(II) Complexes

Ferrocene-conjugated ternary copper(II) complexes [Cu(L)(B)](ClO4)(2), where L is FcCH(2)N(CH2Py)(2) (Fc = (eta(5)-C5H4)Fe-II(eta(5)-C5H5)) and B is a phenanthroline base, viz., 2,2'-bipyridine (bpy, 1), 1, 10-phenanthroline (phen, 2), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 3), and dipyrido[3,2-a:2',3'-c]phenazine (dppz, 4), have been synthesized and characterized by various spectroscopic and analytical techniques. The bpy complex 1, as its hexafluorophosphate salt, has been structurally characterized by X-ray crystallography. The molecular structure shows the copper(II) center having an essentially square-pyramidal coordination geometry in which L with a pendant ferrocenyl (Fc) moiety and bpy show respective tridentate and bidentate modes of binding to the metal center. The complexes are redox active, showing a reversible cyclic voltammetric response of the Fc(+)-Fc couple near 0.5 V vs SCE and a quasi-reversible Cu(II)-Cu(I) couple near 0.0 V. Complexes 2-4 show binding affinity to calf thymus (CT) DNA, giving binding constant (K-b) values in the range of 4.2 x 10(4) to 2.5 x 10(5) M-1. Thermal denaturation and viscometric titration data suggest groove binding and/or a partial intercalative mode of binding of the complexes to CT DNA. The complexes show good binding propensity to the bovine serum albumin (BSA) protein, giving K-BSA values of similar to 10(4) M-1 for the bpy and phen complexes and similar to 10(5) M-1 for the dpq and dppz complexes. Complexes 2-4 exhibit efficient chemical nuclease activity in the presence of 3-mercapto-propionic acid (MPA) as a reducing agent or hydrogen peroxide (H2O2) as an oxidizing agent. Mechanistic studies reveal formation of hydroxyl radicals as the reactive species. The dpq and dppz complexes are active in cleaving supercoiled (SC) pUC19 DNA on photoexposure to visible light of different wavelengths including red light using an argon-krypton mixed gas ion laser. Mechanistic investigations using various inhibitors reveal the fort-nation of hydroxyl radicals in the DNA photocleavage reactions. The dppz complex 4, which shows efficient photoioduced BSA cleavage activity, is a potent multifunctional model nuclease and protease in the chemistry of photodynamic therapy (PDT) of cancer.

Copper(II) Complexes of l-Arginine as Netropsin Mimics Showing DNA Cleavage Activity in Red Light

Copper(II) complexes [Cu(L-arg)(2)](NO3)(2) (1) and [Cu(L-arg)(B)Cl]Cl (2-5), where B is a heterocyclic base, namely, 2,2'-bipyridine (bpy, 2), 1,10-phenanthroline (phen, 3), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 4), and dipyrido[3,2-a:2',3'-c)phenazine (dppz, 5), are prepared and their DNA binding and photoinduced DNA cleavage activity studied. Ternary complex 3, structurally characterized using X-ray crystallography, shows a square-pyramidal (4 + 1) coordination geometry in which the N,O-donor L-arginine and N,N-donor 1,10-phenanthroline form the basal plane with one chloride at the elongated axial site. The complex has a pendant cationic guanidinium moiety. The one-electron paramagnetic complexes display a metal-centered d-d band in the range of 590-690 nm in aqueous DMF They show quasireversible cyclic voltammetric response due to the Cu(II)/Cu(I) couple in the range of -0.1 to -0.3 V versus a saturated calomel electrode in a DMF-Tris HCl buffer (pH 7.2). The DNA binding propensity of the complexes is studied using various techniques. Copper(II) bis-arginate 1 mimics the minor groove binder netropsin by showing preferential binding to the AT-rich sequence of double-strand (ds) DNA. DNA binding study using calf thymus DNA gives an order: 5 (L-arg-dppz) >= 1 (biS-L-arg) > 4 (L-arg-dpq) > 3 (L-arg-phen) >> 2 (L-arg-bpy). Molecular docking calculations reveal that the complexes bind through extensive hydrogen bonding and electrostatic interactions with ds-DNA. The complexes cleave supercoiled pUC19 DNA in the presence of 3-mercaptopropionic acid as a reducing agent forming hydroxyl ((OH)-O-center dot) radicals. The complexes show oxidative photoinduced DNA cleavage activity in UV-A light of 365 nm and red light of 647.1 nm (Ar-Kr mixed-gas-ion laser) in a metal-assisted photoexcitation process forming singlet oxygen (O-1(2)) species in a type-II pathway. All of the complexes, barring complex 2, show efficient DNA photocleavage activity. Complexes 4 and 5 exhibit significant double-strand breaks of DNA in red light of 647.1 nm due to the presence of two photosensitizers, namely, L-arginine and dpq or dppz in the molecules.

Spatial Variability of the Depth of Weathered and Engineering Bedrock using Multichannel Analysis of Surface Wave Method

In this paper an attempt has been made to evaluate the spatial variability of the depth of weathered and engineering bedrock in Bangalore, south India using Multichannel Analysis of Surface Wave (MASW) survey. One-dimensional MASW survey has been carried out at 58 locations and shear-wave velocities are measured. Using velocity profiles, the depth of weathered rock and engineering rock surface levels has been determined. Based on the literature, shear-wave velocity of 330 ± 30 m/s for weathered rock or soft rock and 760 ± 60 m/s for engineering rock or hard rock has been considered. Depths corresponding to these velocity ranges are evaluated with respect to ground contour levels and top surface levels have been mapped with an interpolation technique using natural neighborhood. The depth of weathered rock varies from 1 m to about 21 m. In 58 testing locations, only 42 locations reached the depths which have a shear-wave velocity of more than 760 ± 60 m/s. The depth of engineering rock is evaluated from these data and it varies from 1 m to about 50 m. Further, these rock depths have been compared with a subsurface profile obtained from a two-dimensional (2-D) MASW survey at 20 locations and a few selected available bore logs from the deep geotechnical boreholes.

Bounds on isoperimetric values of trees

Let G = (V, E) be a finite, simple and undirected graph. For S subset of V, let delta(S, G) = {(u, v) is an element of E : u is an element of S and v is an element of V - S} be the edge boundary of S. Given an integer i, 1 <= i <= vertical bar V vertical bar, let the edge isoperimetric value of G at i be defined as b(e)(i, G) = min(S subset of V:vertical bar S vertical bar=i)vertical bar delta(S, G)vertical bar. The edge isoperimetric peak of G is defined as b(e)(G) = max(1 <= j <=vertical bar V vertical bar)b(e)(j, G). Let b(v)(G) denote the vertex isoperimetric peak defined in a corresponding way. The problem of determining a lower bound for the vertex isoperimetric peak in complete t-ary trees was recently considered in [Y. Otachi, K. Yamazaki, A lower bound for the vertex boundary-width of complete k-ary trees, Discrete Mathematics, in press (doi: 10.1016/j.disc.2007.05.014)]. In this paper we provide bounds which improve those in the above cited paper. Our results can be generalized to arbitrary (rooted) trees. The depth d of a tree is the number of nodes on the longest path starting from the root and ending at a leaf. In this paper we show that for a complete binary tree of depth d (denoted as T-d(2)), c(1)d <= b(e) (T-d(2)) <= d and c(2)d <= b(v)(T-d(2)) <= d where c(1), c(2) are constants. For a complete t-ary tree of depth d (denoted as T-d(t)) and d >= c log t where c is a constant, we show that c(1)root td <= b(e)(T-d(t)) <= td and c(2)d/root t <= b(v) (T-d(t)) <= d where c(1), c(2) are constants. At the heart of our proof we have the following theorem which works for an arbitrary rooted tree and not just for a complete t-ary tree. Let T = (V, E, r) be a finite, connected and rooted tree - the root being the vertex r. Define a weight function w : V -> N where the weight w(u) of a vertex u is the number of its successors (including itself) and let the weight index eta(T) be defined as the number of distinct weights in the tree, i.e eta(T) vertical bar{w(u) : u is an element of V}vertical bar. For a positive integer k, let l(k) = vertical bar{i is an element of N : 1 <= i <= vertical bar V vertical bar, b(e)(i, G) <= k}vertical bar. We show that l(k) <= 2(2 eta+k k)

The efficacy of a vitamin D3 metabolite for improving the myofibrillar tenderness of meat from Bos indicus cattle

The influence of a once only administration of a metabolite of vitamin D3 (HY [middle dot] D(R)-25-hydroxy vitamin D3) on myofibrillar meat tenderness in Australian Brahman cattle was studied. Ninety-six Brahman steers of three phenotypes (Indo-Brazil, US and US/European) and with two previous hormonal growth promotant (HGP) histories (implanted or not implanted with Compudose(R)) were fed a standard feedlot ration for 70 d. Treatment groups of 24 steers were offered daily 10 g/head HY [middle dot] D(R) (125 mg 25-hydroxyvitamin D3) for 6, 4, or 2 d before slaughter. One other group of 24 steers was given the basal diet without HY [middle dot] D(R). Feed lot performance, blood and muscle samples and carcass quality data were collected at slaughter. Calcium, magnesium, potassium, sodium, iron and Vitamin D3 metabolites were measured in plasma and longissimus dorsi muscle. Warner-Bratzler (WB) shear force (peak force, initial yield) and other objective meat quality measurements were made on the longissimus dorsi muscle of each steer after ageing for 1, 7 and 14 d post-mortem at 0-2 [deg]C.There were no significant effects of HY [middle dot] D(R) supplements on average daily gain (ADG, 1.28-1.45 kg/d) over the experimental period. HY [middle dot] D(R) supplements given 6 d prior to slaughter resulted in significantly higher (P (R)) by phenotype/HGP interaction for peak force (P = 0.028), in which Indo-Brazil steers without previous HGP treatment responded positively (increased tenderness) to HY [middle dot] D(R) supplements at 2 d when compared with Indo-Brazil steers previously given HGP. There were no significant effects of treatment on other phenotypes. HY [middle dot] D(R) supplements did not affect muscle or plasma concentrations of calcium, potassium or sodium, but did significantly decrease plasma magnesium and iron concentrations when given 2 d before slaughter. There were no detectable amounts of 25-hydroxyvitamin D3 in the blood or muscle of any cattle at slaughter.

Photo-induced double-strand DNA and site-specific protein cleavage activity of L-histidine (mu-oxo)diiron(III) complexes of heterocyclic bases

Three oxo-bridged diiron(III) complexes of L-histidine and heterocyclic bases [Fe-2(mu-O)(L-his)(2)(B)(2)](ClO4)(2) (1-3), where B is 2,2'-bipyridine (bpy),1,10-phenanthroline (phen), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq), were prepared and characterized. The bpy complex 1 was structurally characterized by X-ray crystallography. The molecular structure showed a {Fe-2(mu-O)} core in which iron(III) in a FeN4O2 coordination is bound to tridentate monoanionic L-histidine and bidentate bpy ligands. The Fe center dot center dot center dot Fe distance is similar to 3.5 angstrom. The Fe-O-Fe unit is essentially linear, giving a bond angle of similar to 172 degrees. The complexes showed irreversible cyclic voltammetric cathodic response near -0.1 V vs. SCE in H2O-0.1 M KCl. The binuclear units displayed antiferromagnetic interaction between two high-spin (S = 5/2) iron(III) centers giving a -J value of -110 cm(-1). The complexes showed good DNA binding propensity giving a binding constant value of similar to 10(5) M-1. Isothermal titration calorimetric data indicated single binding mode to the DNA. The binding was found to be driven by negative free energy change and enthalpy. The dpq complex 3 showed oxidative double-strand DNA cleavage on exposure to UV-A and visible light. The phen complex 2 displayed single-strand photocleavage of DNA. The DNA double-strand breaks were rationalized from theoretical molecular docking calculations. Mechanistic investigations showed formation of hydroxyl radicals as the reactive species through photodecarboxylation of the L-histidine ligand. The complexes exhibited good binding propensity to bovine serum albumin (BSA) protein in Tris-HCl/NaCl buffer medium. The dpq complex 3 showed UV-A light-induced site-specific oxidative BSA cleavage forming fragments of similar to 45 kDa and similar to 20 kDa molecular weights via SOH pathway.

An RNS based transform Architecture for H.264/AVC

This paper presents the architecture and the VHDL design of an integer 2-D DCT used in the H.264/AVC. The 2-D DCT computation is performed by exploiting it’s orthogonality and separability property. The symmetry of the forward and inverse transform is used in this implementation. To reduce the computation overhead for the addition, subtraction and multiplication operations, we analyze the suitability of carry-free position independent residue number system (RNS) for the implementation of 2-D DCT. The implementation has been carried out in VHDL for Altera FPGA. We used the negative number representation in RNS, bit width analysis of the transforms and dedicated registers present in the Logic element of the FPGA to optimize the area. The complexity and efficiency analysis show that the proposed architecture could provide higher through-put.

Quality of life changes during conformal radiation therapy for prostate carcinoma

BACKGROUND: The objective of this study was to describe prospectively quality of life (QOL) before and after radiotherapy for patients with prostate carcinoma. METHODS: Forty-three patients with T1-T3 prostate carcinoma who underwent conformal external beam radiation therapy were randomized either to the complete European Organization for Research and Treatment of Cancer (EORTC) QOL questionnaire (EORTC QLQ-C30) or the Medical Outcomes Study Group Short Form Health Survey (SF-36) at baseline, at 3 weeks and 6 weeks after initial treatment, and at 6 weeks and 5 months after the completion of radiotherapy. The measures were self-reported patient QOL, and values are given as the mean +/- standard error of the mean. Changes in QOL are described from baseline to the end of treatment in both questionnaire groups. RESULTS: Emotional role functioning, as measured with the SF-36 questionnaire, significantly improved from 68.2 +/- 9.9 at baseline to 93.3 +/- 5.2 at the end of therapy (P = 0.02). The EORTC QLQ-C30 questionnaire revealed consistent values of emotional functioning during treatment (72.7 +/- 5.9 at baseline) but showed a significant improvement 6 weeks after therapy (89.0 +/- 4.4; P = 0.01). Role functioning deteriorated from 80.1 +/- 6.5 at baseline to 62.5 +/- 8.8 at the end of radiotherapy (P = 0.02). Symptoms of fatigue were shown to increase significantly from 26.9 +/- 6.0 at baseline to 37.7 +/- 7.6 at the end of therapy (P = 0.02). No significant changes in the other dimensions were observed in either questionnaire. CONCLUSIONS: After radiotherapy for prostate carcinoma, patients experience a temporary deterioration of fatigue and role functioning, as measured with the EORTC QLQ-C-30. Despite physical deterioration, the authors observed an improvement in emotional functioning scores with both questionnaires. This may have been due to psychological adaptation and coping.

Power system stability implications from electromechanical wave propagation

Electromechanical wave propagation characterizes the first-swing dynamic response in a spatially delayed manner. This paper investigates the characteristics of this phenomenon in two-dimensional and one-dimensional power systems. In 2-D systems, the wave front expands as a ripple in a pond. In 1-D systems, the wave front is more concentrated, retains most of its magnitude, and travels like a pulse on a string. This large wave front is more impactful upon any weak link and easily causes transient instability in 1-D systems. The initial disturbance injects both high and low frequency components, but the lumped nature of realistic systems only permits the lower frequency components to propagate through. The kinetic energy split at a junction is equal to the generator inertia ratio in each branch in an idealized continuum system. This prediction is approximately valid in a realistic power system. These insights can enhance understanding and control of the traveling waves.

Net radiation dynamics: performance of 20 daily net radiation models as related to model structure and intricacy in two climates.

We compared daily net radiation (Rn) estimates from 19 methods with the ASCE-EWRI Rn estimates in two climates: Clay Center, Nebraska (sub-humid) and Davis, California (semi-arid) for the calendar year. The performances of all 20 methods, including the ASCE-EWRI Rn method, were then evaluated against Rn data measured over a non-stressed maize canopy during two growing seasons in 2005 and 2006 at Clay Center. Methods differ in terms of inputs, structure, and equation intricacy. Most methods differ in estimating the cloudiness factor, emissivity (e), and calculating net longwave radiation (Rnl). All methods use albedo (a) of 0.23 for a reference grass/alfalfa surface. When comparing the performance of all 20 Rn methods with measured Rn, we hypothesized that the a values for grass/alfalfa and non-stressed maize canopy were similar enough to only cause minor differences in Rn and grass- and alfalfa-reference evapotranspiration (ETo and ETr) estimates. The measured seasonal average a for the maize canopy was 0.19 in both years. Using a = 0.19 instead of a = 0.23 resulted in 6% overestimation of Rn. Using a = 0.19 instead of a = 0.23 for ETo and ETr estimations, the 6% difference in Rn translated to only 4% and 3% differences in ETo and ETr, respectively, supporting the validity of our hypothesis. Most methods had good correlations with the ASCE-EWRI Rn (r2 > 0.95). The root mean square difference (RMSD) was less than 2 MJ m-2 d-1 between 12 methods and the ASCE-EWRI Rn at Clay Center and between 14 methods and the ASCE-EWRI Rn at Davis. The performance of some methods showed variations between the two climates. In general, r2 values were higher for the semi-arid climate than for the sub-humid climate. Methods that use dynamic e as a function of mean air temperature performed better in both climates than those that calculate e using actual vapor pressure. The ASCE-EWRI-estimated Rn values had one of the best agreements with the measured Rn (r2 = 0.93, RMSD = 1.44 MJ m-2 d-1), and estimates were within 7% of the measured Rn. The Rn estimates from six methods, including the ASCE-EWRI, were not significantly different from measured Rn. Most methods underestimated measured Rn by 6% to 23%. Some of the differences between measured and estimated Rn were attributed to the poor estimation of Rnl. We conducted sensitivity analyses to evaluate the effect of Rnl on Rn, ETo, and ETr. The Rnl effect on Rn was linear and strong, but its effect on ETo and ETr was subsidiary. Results suggest that the Rn data measured over green vegetation (e.g., irrigated maize canopy) can be an alternative Rn data source for ET estimations when measured Rn data over the reference surface are not available. In the absence of measured Rn, another alternative would be using one of the Rn models that we analyzed when all the input variables are not available to solve the ASCE-EWRI Rn equation. Our results can be used to provide practical information on which method to select based on data availability for reliable estimates of daily Rn in climates similar to Clay Center and Davis.

Numerical studies of gypsum plasterboard and MGO board lined LSF walls exposed to fire

Fire resistance of cold-formed light gauge steel frame (LSF) wall systems is enhanced by lining them with single or multiple layers of wall boards with varying thermal properties. These wall boards are gypsum plasterboards or Magnesium Oxide (MgO) boards produced by different manufacturers. Thermal properties of these boards appear to show considerable variations and this can lead to varying fire resistance levels (FRL) for their wall systems. Currently FRLs of wall systems are determined using full scale fire tests, but they are time consuming and expensive. Recent research studies on the fire performance of LSF wall systems have used finite element studies to overcome this problem, but they were developed based on 1-D and 2-D finite element platform capable of performing either heat transfer or structural analysis separately. Hence in this research a 3-D finite element model was developed first for LSF walls lined with gypsum plasterboard and cavity insulation materials. Accurate thermal properties of these boards are essential for finite element modelling, and thus they were measured at both ambient and elevated temperatures. This experimental study included specific heat, relative density and thermal conductivity of boards. The developed 3-D finite element model was then validated using the available fire tests results of LSF walls lined with gypsum plasterboard, and is being used to investigate the fire performance of different LSF wall configurations. The tested MgO board exhibited significant variations in their thermal properties in comparison to gypsum plasterboards with about 50% loss of its initial mass at about 500 ºC compared to 16% for gypsum plasterboards. Hence the FRL of MgO board lined LSF wall systems is likely to be significantly reduced. This paper presents the details of this research study on the fire performance of LSF wall systems lined with gypsum plasterboard and MgO board including the developed 3-D finite element models, thermal property tests and the results.

Commercial application of polychaete sand filters for wastewater remediation and broodstock feeds

Summary Prototype sand-worm filtration beds were constructed at two prawn farms and one fish farm to assess and demonstrate their polychaete (marine worm) production and wastewater remediation capacities at semi-commercial scale. Wastewater treatment properties were monitored and worms produced were assessed and either sold for bait or used by the farms’ hatcheries as broodstock (prawn or fish breeder) feed. More than 34 megalitres of prawn- and fish-pond water was beneficially treated in the 116-319-d trial. The design of the polychaete-assisted sand filters (PASFs) constructed at each farm affected their water handling rates, which on average ranged from 315 to 1000 L m-2 d-1 at the three farms. A low profile design incorporating shallow bunded ponds made from polyethylene liner and timber stakes provided the easiest method of construction. This simple design applied at broad scale facilitated the highest quantities of treated water and the greatest worm production. Designs with higher sides increased the head pressure above the sand bed surface, thus increasing the amount of water that could be treated each day. Most water qualities were affected in a similar way to that demonstrated in the previous tank trials: dissolved oxygen, pH, total suspended solids and chlorophyll a levels were all consistently significantly lowered as pond water percolated through the sand bed, and dissolved forms of nitrogen and phosphorus were marginally increased on several occasions. However, unlike the previous smaller-scale tank trials, total nitrogen (TN) and total phosphorus (TP) levels were both significantly lowered by these larger-scale PASFs. The reasons for this are still unclear and require further research. Maximum TN and TP removals detected in the trial were 48.8% and 67.5%, respectively, and average removals (in unfed beds) at the three farms ranged from 20.0 to 27.7% for TN and from 22.8 to 40.8% for TP. Collectively, these results demonstrate the best suspended solids, chlorophyll and macronutrient removal capacities so far reported for any mariculture wastewater treatment methodology to date. Supplemental feeding of PASFs with fish meal was also investigated at one farm as a potential means of increasing their polychaete biomass production. Whilst fed beds produced higher biomass (152 ± 35 g m-2) compared with unfed beds (89 ± 17 g m-2) after 3.7 months of operation, the low number of replicates (2) prevented statistically significant differences from being demonstrated for either growth or survival. At harvest several months later, worm biomass production was estimated to be similar to, or in slight excess of, previously reported production levels (300-400 g m-2). Several qualities of filtered water appear to have been affected by supplemental feeding: it appeared to marginally lower dissolved oxygen and pH levels, and increased the TN and TP levels though not so much to eliminate significant beneficial water treatment effects. Periodic sampling during an artificial-tide demonstrated the tendency for treated-water quality changes during the first hour of filtration. Total nitrogen and ammonia peaked early in the tidal flow and then fell to more stable levels for the remainder of the filtration period. Other dissolved nutrients also showed signs of this sand-bed-flushing pattern, and dissolved oxygen tended to climb during the first hour and become more stable thereafter. These patterns suggest that the routine sampling of treated water undertaken at mid-inflow during the majority of the wider study would likely have overestimated the levels of TN and dissolved nutrients discharged from the beds, and hence underestimated the PASFs treatment efficacies in this regard. Analyses of polychaete biomass collected from each bed in the study revealed that the worms were free from contamination with the main prawn viruses that would create concerns for their feeding to commercial prawn broodstock in Australia. Their documented proximal and nutritional contents also provide a guide for hatchery operators when using live or frozen stock. Their dry matter content ranged from 18.3 to 22.3%, ash ranged from 10.2 to 14.0%, gross energy from 20.2 to 21.5 MJ kg-1, and fat from 5.0 to 9.2%. Their cholesterol levels ranged from 0.86 to 1.03% of dry matter, whilst total phospholipids range from 0.41 to 0.72%. Thirty-one different fatty acids were present at detectable (≥0.005% of dry matter) levels in the sampled worm biomass. Palmitic acid was by far the most prevalent fatty acid detected (1.21 ± 0.18%), followed by eicosapentaenoic (EPA) (0.48 ± 0.03%), stearic (0.46 ± 0.04%), vaccenic (0.38 ± 0.05%), adrenic (0.35 ± 0.02%), docosadienoic (0.28 ± 0.02%), arachidonic (AA) (0.22 ± 0.01%), palmitoleic (0.20 ± 0.04%) and 23 other fatty acids with average contents of less than 0.2% of dry matter. Supplemental feeding with fish meal at one farm appeared to increase the docosahexaenoic acid (DHA) content of the worms considerably, and modify the average AA : EPA : DHA from 1.0 : 2.7 : 0.3 to 1.0 : 2.0 : 1.1. Consistent with previous results, the three most heavily represented amino acids in the dry matter of sampled worms were glutamic acid (8.5 ± 0.2%), aspartic acid (5.5 ± 0.1%) and glycine (4.9 ± 0.5%). These biomass content results suggest that worms produced in PASF systems are well suited to feeding to prawn and fish broodstock, and provide further strong evidence of the potential to modify their contents for specific nutritional uses. The falling wild-fishery production of marine bloodworms in Queensland is typical of diminishing polychaete resources world-wide and demonstrates the need to develop sustainable production methods here and overseas. PASF systems offer the dual benefits of wastewater treatment for environmental management and increased productivity through a valuable secondary crop grown exclusively on waste nutrients.

Polychaete-assisted sand filters

The objective of this study was to investigate the productivity and functionality of sand filters stocked with marine worms for wastewater treatment at mariculture facilities. Medium bedding sand which is commonly available in coastal sedimentary deposits and nereidid polychaetes (Perinereis nuntia and P. helleri) from Moreton Bay in southeast Queensland were combined and studied in down-flow sand filtration beds. This combination appears to provide a new option for brackish wastewater treatment whereby the activities of the worms help to prevent sand filters from blocking with organic debris and their biomass offers a valuable by-product. Phytoplankton-rich pond waters percolating through sand-worm beds were reliably treated in several useful ways: suspended solids and chlorophyll a levels were consistently reduced by >50% by the process, and nutrients were converted into bio-available dissolved forms. Dissolved oxygen, redox and pH levels were also lowered significantly by the process. Water treatment rates of approx 1500 L m-2 d-1 were routinely achieved. P. nuntia appeared more suitable than P. helleri for stocking directly into sand filtration beds as nectochaetes, but generally exhibited slower growth. Survival and growth were influenced by stocking density. Sand-filter beds stocked with juvenile worms and fed only with eutrophic pond water demonstrated polychaete production capacities in the order of 300-400 g m-2 (eg. P. helleri: 328 g m-2 in 16 weeks). These results show how nereidid polychaetes can be reliably produced within simple, low-maintenance sand filters, and provide data necessary for the functional integration of this novel wastewater treatment system into contemporary seafood farming systems.

Polychaete-assisted sand filters – prawn farm wastewater remediation trial

Medium bedding sand which is commonly available in coastal sedimentary deposits, and a marine polychaete-worm species from Moreton Bay recently classified as Perinereis helleri (Nereididae), were deployed in a simple low-maintenance sand filter design that potentially has application at large scale. Previous work had shown that this physical and biological combination can provide a new option for saline wastewater treatment, since the worms help to prevent sand filter blocking with organic debris and offer a profitable by-product. To test the application of this new concept in a commercial environment, six 1.84 m2 Polychaete-assisted sand filters were experimentally tested for their ability to treat wastewater from a semi-intensive prawn culture pond. Polychaetes produced exclusively on the waste nutrients that collected in these gravity-driven sand filters were assessed for their production levels and nutritional contents. Water parameters studied included temperature, salinity, pH, dissolved oxygen (DO), oxidation/ reduction potential (redox), suspended solids, chlorophyll a, biological oxygen demand (BOD), and common forms of nitrogen and phosphorus. Pond water which had percolated through the sand bed had significantly lower pH, DO and redox levels compared with inflow water. Suspended solids and chlorophyll a levels were consistently more than halved by the process. Reductions in BOD appeared dependant on regular subsurface flows. Only marginal reductions in total nitrogen and phosphorus were documented, but their forms were altered in a potentially useful way: dissolved forms (ammonia and orthophosphate) were generated by the process, and this remineralisation also seemed to be accentuated by intermittent flow patterns. Flow rates of approximately 1,500 L m-2 d-1 were achieved suggesting that a 1 ha polychaete bed of this nature could similarly treat the discharge from a 10 ha semi-intensive prawn farm. Sixteen weeks after stocking sand beds with one-month-old P. helleri, over 3.6 kg of polychaete biomass (wet weight) was recovered from the trial. Production on a sand bed area basis was 328 g m-2. Similar (P>0.05) overall biomass production was found for the two stocking densities tested (2000 and 6000 m-2; n = 3), but survival was lower and more worms were graded as small (<0.6 g) when produced at the higher density (28.2 ± 1.5 % and approx. 88 %, respectively) compared with the lower density (46.8 ± 4.4 % and approx. 76 %, respectively). When considered on a weight for weight basis, about half of the worm biomass produced was generally suitable for use as bait. The nutritional contents of the worms harvested were analysed for different stocking densities and graded sizes. These factors did not significantly affect their percentages of dry matter (DM) (18.23 ± 0.57 %), ash (19.77 ± 0.80 % of DM) or gross energy 19.39 ± 0.29 MJ kg-1 DM) (n = 12). Although stocking density did not affect the worms’ nitrogen and phosphorus contents, small worms had a higher mean proportion of nitrogen and phosphorus (10.57 ± 0.17 % and 0.70 ± 0.01 % of DM, respectively) than large worms (9.99 ± 0.12 % and 0.65 ± 0.01 % of DM, respectively) (n = 6). More lipid was present in large worms grown at the medium density (11.20 ± 0.19 %) compared with the high density (9.50 ± 0.31 %) and less was generally found in small worms (7.1-7.6 % of DM). Mean cholesterol and total phospholipid levels were 5.24 ± 0.15 mg g-1 and 13.66 ± 2.15 mg g-1 DM, respectively (n = 12). Of the specific phospholipids tested, phosphatidyl-serine or sphingomyelin were below detection limits (<0.05 mg g-1), whilst mean levels of phosphatidyl-ethanolamine, phosphatidyl-inositol, phosphatidyl-choline and lysophosphatidyl-choline were 6.89 ± 1.09, 0.89 ± 0.26, 4.04 ± 1.17 and 1.84 ± 0.37 mg g-1, respectively (n = 12). Culture density generally had a more pronounced effect on phospholipid contents than did size of worms. By contrast, worm size had a more pronounced effect on total fatty acid contents, with large worms containing significantly higher (P<0.001) levels on a DM basis (46.88 ± 2.46 mg g-1) than smaller worms (27.76 ± 1.28 mg g-1). A very broad range of fatty acids were detected with palmitic acid being the most heavily represented class (up to 14.23 ± 0.49 mg g-1 DM or 27.28 ± 0.22 % of total fatty acids). Other heavily represented classes included stearic acid (7.4-8.8 %), vaccenic acid (6.8-7.8 %), arachidonic acid (3.5-4.4 %), eicosapentaenoic acid (9.9-13.8 %) and docosenoic acid (5.7-7.0 %). Stocking density did not affect (P>0.05) the levels of amino acids present in polychaete DM, but there was generally less of each amino acid tested on a weight per weight basis in large worms than in small worms. This difference was significant (P<0.05) for the most heavily represented classes being glutamic acid (73-77 mg g-1), aspartic acid (50-54 mg g-1), and glycine (46-53 mg g-1). These results demonstrate how this polychaete species can be planted and sorted at harvest according to various strategies aimed at providing biomass with specific physical and nutritional qualities for different uses.

Light thresholds derived from seagrass loss in the coastal zone of the northern Great Barrier Reef, Australia

There is a world-wide trend for deteriorating water quality and light levels in the coastal zone, and this has been linked to declines in seagrass abundance. Localized management of seagrass meadow health requires that water quality guidelines for meeting seagrass growth requirements are available. Tropical seagrass meadows are diverse and can be highly dynamic and we have used this dynamism to identify light thresholds in multi-specific meadows dominated by Halodule uninervis in the northern Great Barrier Reef, Australia. Seagrass cover was measured at similar to 3 month intervals from 2008 to 2011 at three sites: Magnetic Island (MI) Dunk Island (DI) and Green Island (GI). Photosynthetically active radiation was continuously measured within the seagrass canopy, and three light metrics were derived. Complete seagrass loss occurred at MI and DI and at these sites changes in seagrass cover were correlated with the three light metrics. Mean daily irradiance (I-d) above 5 and 8.4 mol m(-2) d(-1) was associated with gains in seagrass at MI and DI, however a significant correlation (R = 0.649, p < 0.05) only occurred at MI. The second metric, percent of days below 3 mol m(-2) d(-1), correlated the most strongly (MI, R = -0.714, p < 0.01 and DI, R = -0.859, p = <0.001) with change in seagrass cover with 16-18% of days below 3 mol m(-2) d(-1) being associated with more than 50% seagrass loss. The third metric, the number of hours of light saturated irradiance (H-sat) was calculated using literature-derived data on saturating irradiance (E-k). H-sat correlated well (R = 0.686, p <0.01; and DI, R = 0.704, p < 0.05) with change in seagrass abundance, and was very consistent between the two sites as 4 H-sat was associated with increases in seagrass abundance at both sites, and less than 4 H-sat with more than 50% loss. At the third site (GI), small seasonal losses of seagrass quickly recovered during the growth season and the light metrics did not correlate (p > 0.05) with change in percent cover, except for I-d which was always high, but correlated with change in seagrass cover. Although distinct light thresholds were observed, the departure from threshold values was also important. For example, light levels that are well below the thresholds resulted in more severe loss of seagrass than those just below the threshold. Environmental managers aiming to achieve optimal seagrass growth conditions can use these threshold light metrics as guidelines; however, other environmental conditions, including seasonally varying temperature and nutrient availability, will influence seagrass responses above and below these thresholds. (C) 2012 Published by Elsevier Ltd.