Biofouling Community Assemblage in Coastal Waters Adjacent to Port of Colombo, West Coast of Sri Lanka

Port of Colombo which controls majority of country's foreign cargo has been the major trading canter of the country for decades. Although, the port has been subjected to Port biological baseline surveys for non-indigenous species, adjacent coastal waters have obtained limited attention. Hence present study was conducted in three sampling locations; Dikkowita Fisheries Harbour, Kirulapone canal opening, Panadura Fisheries Harbour along the coastal waters adjacent to Port of Colombo. Panadura Fisheries Harbour was taken as the reference point due to its distance from Colombo Port and relatively low international shipping activities. Combination of environmental surveys with photo quadrant sampling, and submerged structure sampling was conducted to detect fouling and associated organisms. A modified version of survey procedure and protocol developed by Marine Biological Association of United Kingdom was followed for the study. Convenience sampling method was used to select sampling points where four replicates of quadrants were randomly placed within 12 m long belt transect. Coral Point Count with Excel Extension version 4.1 software was used to quantify the abundance of the species by estimating the percentage cover and the individual count from each photo quadrant. Environmental surveys were carried out once in two months’ intervals along the inter-tidal zone of each study location. Artificial structures having four substrate types were deployed at a depth of 2 m from the water surface in all 3 sampling locations and sampled once in two months’ intervals. Randomised Complete Block Design analysis were conducted using number of individuals, percentage area covers, study locations, monsoon seasons and tide hitting attributes as variables. A total of 49 taxa were recorded during the course of the study. Highest number of species were recorded from phylum Mollusca. Oysters species were the dominant macro fouling organisms in terms of percentage area cover in Dikkowita (33.39% cover) and Wellawatte (49.80% cover) study locations. Recording the presence of three Non-indigenous species; Isognomon alatus, Cassostrea virginica, Ostrea edulis together with four globally known invasive species: Balanus amphitrite, B. reticulatus, Perna viridis, was alarming. Randomised Complete Block Design analysis for both biofouling organisms number and percentage area coverage confirmed a significant paired interaction between tide hitting attributes and study locations. Similarly, significant paired interactions were yielded between monsoon seasons and study locations. Submerged structure sampling recorded tube-worm species as the climax species in the wooden substrate, conversely no climax species were observed on other substrate types.Keywords: Biofouling, Port of Colombo, Port biological baseline survey, Non-indigenous specie

Temperature Effects on Force and Actin–Myosin Interaction in Muscle:A Look Back on Some Experimental Findings

Observations made in temperature studies on mammalian muscle during force development, shortening, and lengthening, are re-examined. The isometric force in active muscle goes up substantially on warming from less than 10 °C to temperatures closer to physiological (>30 °C), and the sigmoidal temperature dependence of this force has a half-maximum at ~10 °C. During steady shortening, when force is decreased to a steady level, the sigmoidal curve is more pronounced and shifted to higher temperatures, whereas, in lengthening muscle, the curve is shifted to lower temperatures, and there is a less marked increase with temperature. Even with a small rapid temperature-jump (T-jump), force in active muscle rises in a definitive way. The rate of tension rise is slower with adenosine diphosphate (ADP) and faster with increased phosphate. Analysis showed that a T-jump enhances an early, pre-phosphate release step in the acto-myosin (crossbridge) ATPase cycle, thus inducing a force-rise. The sigmoidal dependence of steady force on temperature is due to this endothermic nature of crossbridge force generation. During shortening, the force-generating step and the ATPase cycle are accelerated, whereas during lengthening, they are inhibited. The endothermic force generation is seen in different muscle types (fast, slow, and cardiac). The underlying mechanism may involve a structural change in attached myosin heads and/or their attachments on heat absorption

The impact of adjusting for baseline in pharmacogenomic genome-wide association studies of quantitative change.

In pharmacogenomic studies of quantitative change, any association between genetic variants and the pretreatment (baseline) measurement can bias the estimate of effect between those variants and drug response. A putative solution is to adjust for baseline. We conducted a series of genome-wide association studies (GWASs) for low-density lipoprotein cholesterol (LDL-C) response to statin therapy in 34,874 participants of the Genetic Epidemiology Research on Adult Health and Aging (GERA) cohort as a case study to investigate the impact of baseline adjustment on results generated from pharmacogenomic studies of quantitative change. Across phenotypes of statin-induced LDL-C change, baseline adjustment identified variants from six loci meeting genome-wide significance (SORT/CELSR2/PSRC1, LPA, SLCO1B1, APOE, APOB, and SMARCA4/LDLR). In contrast, baseline-unadjusted analyses yielded variants from three loci meeting the criteria for genome-wide significance (LPA, APOE, and SLCO1B1). A genome-wide heterogeneity test of baseline versus statin on-treatment LDL-C levels was performed as the definitive test for the true effect of genetic variants on statin-induced LDL-C change. These findings were generally consistent with the models not adjusting for baseline signifying that genome-wide significant hits generated only from baseline-adjusted analyses (SORT/CELSR2/PSRC1, APOB, SMARCA4/LDLR) were likely biased. We then comprehensively reviewed published GWASs of drug-induced quantitative change and discovered that more than half (59%) inappropriately adjusted for baseline. Altogether, we demonstrate that (1) baseline adjustment introduces bias in pharmacogenomic studies of quantitative change and (2) this erroneous methodology is highly prevalent. We conclude that it is critical to avoid this common statistical approach in future pharmacogenomic studies of quantitative change

An analysis of the temperature dependence of force, during steady shortening at different velocities, in (mammalian) fast muscle fibres

We examined, over a wide range of temperatures (10–35°C), the isometric tension and tension during ramp shortening at different velocities (0.2–4 L0/s) in tetanized intact fibre bundles from a rat fast (flexor hallucis brevis) muscle; fibre length (L0) was 2.2 mm and sarcomere length ~2.5 μm. During a ramp shortening, the tension change showed an initial inflection of small amplitude (P1), followed by a larger exponential decline towards an approximate steady level; the tension continued to decline slowly afterwards and the approximate steady tension at a given velocity was estimated as the tension (P2) at the point of intersection between two linear slopes, as previously described (Roots et al. 2007). At a given temperature, the tension P2 declined to a lower level and at a faster rate (from an exponential curve fit) as the shortening velocity was increased; the temperature sensitivity of the rate of tension decline during ramp shortening at different velocities was low (Q10 0.9–1.5). The isometric tension and the P2 tension at a given shortening velocity increased with warming so that the relation between tension and (reciprocal) temperature was sigmoidal in both. In isometric muscle, the temperature T0.5 for half-maximal tension was ~10°C, activation enthalpy change (∆H) was ~100 kJ mol−1 and entropy change (∆S) ~350 J mol−1 K−1. In shortening, these were increased with increase of velocity so that at a shortening velocity (~4 L0/s) producing maximal power at 35°C, T0.5 was ~28°C, ∆H was ~200 kJ mol−1 and ∆S ~ 700 J mol−1 K−1; the same trends were seen in the tension data from isotonic release experiments on intact muscle and in ramp shortening experiments on maximally Ca-activated skinned fibres. In general, our findings show that the sigmoidal relation between force and temperature can be extended from isometric to shortening muscle; the implications of the findings are discussed in relation to the crossbridge cycle. The data indicate that the endothermic, entropy driven process that underlies crossbridge force generation in isometric muscle (Zhao and Kawai 1994; Davis, 1998) is even more pronounced in shortening muscle, i.e. when doing external work

Force generation examined by laser temperature-jumps in shortening and lengthening mammalian (rabbit psoas) muscle fibres

We examined the tension change induced by a rapid temperature jump (T-jump) in shortening and lengthening active muscle fibres. Experiments were done on segments of permeabilized single fibres (length (L0) ∼2 mm, sarcomere length 2.5 μm) from rabbit psoas muscle; [MgATP] was 4.6 mm, pH 7.1, ionic strength 200 mm and temperature ∼9°C. A fibre was maximally Ca2+-activated in the isometric state and a ∼3°C, rapid (< 0.2 ms), laser T-jump applied when the tension was approximately steady in the isometric state, or during ramp shortening or ramp lengthening at a limited range of velocities (0–0.2 L0 s−1). The tension increased to 2- to 3 × P0 (isometric force) during ramp lengthening at velocities > 0.05 L0 s−1, whereas the tension decreased to about < 0.5 × P0 during shortening at 0.1–0.2 L0 s−1; the unloaded shortening velocity was ∼1 L0 s−1 and the curvature of the force–shortening velocity relation was high (a/P0 ratio from Hill's equation of ∼0.05). In isometric state, a T-jump induced a tension rise of 15–20% to a new steady state; by curve fitting, the tension rise could be resolved into a fast (phase 2b, 40–50 s−1) and a slow (phase 3, 5–10 s−1) exponential component (as previously reported). During steady lengthening, a T-jump induced a small instantaneous drop in tension, followed by recovery, so that the final tension recorded with and without a T-jump was not significantly different; thus, a T-jump did not lead to a net increase of tension. During steady shortening, the T-jump induced a pronounced tension rise and both its amplitude and the rate (from a single exponential fit) increased with shortening velocity; at 0.1–0.2 L0 s−1, the extent of fibre shortening during the T-jump tension rise was estimated to be ∼1.2% L0 and it was shorter at lower velocities. At a given shortening velocity and over the temperature range of 8–30°C, the rate of T-jump tension rise increased with warming (Q10 ≈ 2.7), similar to phase 2b (endothermic force generation) in isometric muscle. Results are discussed in relation to the previous findings in isometric muscle fibres which showed that a T-jump promotes an early step in the crossbridge–ATPase cycle that generates force. In general, the finding that the T-jump effect on active muscle tension is pronounced during shortening, but is depressed/inhibited during lengthening, is consistent with the expectations from the Fenn effect that energy liberation (and acto-myosin ATPase rate) in muscle are increased during shortening and depressed/inhibited during lengthening

Sustainable Use of Biomass Boiler Ash as a Reinforcement Filler for Polyamide 6 Composite

The use of biomass combustion ash as a reinforcing filler has taken the attention in recent years to reduce the overall production cost and increase the mechanical properties of plastics. This study evaluates the effect of biomass boilers ash (BBA) as a reinforcing filler on polyamide 6 composites (PA6). The chemical composition and thermal stability of BBA were analyzed by X-ray fluorescence (XRF), Thermogravimetric analysis (TGA), and Differential thermal analysis (DTA) thermographs. Test samples were prepared by varying the ash content (2.5%, 5%, 7.5%, and 10%), and also samples were prepared without adding ash as a control. Moreover, surface modification was carried out by using N-2 (Aminoethyl) 3-aminopropyl triethoxy diamino-silane as a possible coupling agent for BBA  and it was tested by varying the coupling agent concentration (0.5%, 1%, and 2%) by dry process and the samples were prepared by extrusion and injection molding processes. Comparative analysis of the degree of crystallinity, mechanical properties including tensile, flexural, and thermal properties were tested. The highest degree of crystallinity was obtained with 7.5% BBA-filled composites. The addition of 2% surface-modified BBA (SBBA) filled composites (PA6 / 10% Ash 2% CA) showed an increase of tensile strength and elongation at break than the 10% unmodified BBA (UBBA) (PA6/ 10% Ash) filled composites. Stress at peak and bending modulus values in the flexural test data were increased up to 10%. But it was significantly reduced with the increasing of modifying agent concentration due to the increment of stiffness of the composite

Diversity and Distribution of Ichthyofauna and Decapods within Colombo Port, Sri Lanka

The taxonomic composition of ichthyofauna and decapods inhabited in Colombo port were studied. Sampling was carried out for nine months from April to December 2013 using multiple sampling techniques such as crab traps, hook and lines, gee-minnow traps, fish cage traps, cast nets, scoop nets as well as visual observations. Out of the 45 species of ichthyofauna, 44 species were belonging to Class Actinopterygii, and only one species belonged to Class Chondrichthyes. 5 species of crabs of the families Xanthidae, Portunidae, Grapsidae, and Menippidae were also recorded. The highest number of species were recorded from the site South Jetty followed by Passenger Jetty, Tug and Launch and South Asia Gateway Terminal. According to the findings, 30 species of fishes and 4 species of crabs were new records for the Colombo port environment. Two near threaten fishes, Epinephelus malabaricus and Epinephelus coioides were also recorded.KEYWORDS: Taxonomic composition, Colombo port, Near Threaten, Fish, Crab

Zooplankton Assemblage in Hambanota Port and Adjacent Coastal Waters of Sri Lanka

Present study was to investigate zooplankton assemblage in Hambantota port andadjacent coastal waters in Sri Lanka. Samples were collected from the port before thecommencement of commercial operations in order to have baseline information onzooplankton assemblage that can be used in the future to study any community change.Species composition, abundance, spatial distribution and diversity of zooplankton wereinvestigated over a period of six months from January 2011 to June 2011. Monthlysamples were collected from both inner-harbor and outer-harbor. Physico-chemicalparameters such as temperature, pH, salinity, density, conductivity, nitrate,orthophosphate, DO, BOD5 and Ch a were also measured. Zooplankton diversity, speciesrichness and evenness were calculated using Shannon-Weiner diversity index (Hˊ ),Simpson‟s index (D) and Pielou‟s evenness (E). A total of 72 zooplankton types wereidentified throughout the research project mainly Calanus sp., Paracalanus sp.,Sapphirina sp., Acartia tranteri, Barnacle nauplii, Crustacean cypris larvae, Oikopleurasp., Tunicate larvae, Brachionus calyciflorus calyciflorus, Brachionus forficula, Fishlarvae, Discorbis sp., Actinula larvae and Sagitta sp.. Copepod nauplii dominated thezooplankton. According to percentage occurrences arthropods (71%), protozoans (10%)and ichthyoplankton (9%) were abundant in the inner harbor. In the outer harbor alsoarthropods (66%), ichthyoplankton (11%) and protozoans (7%) were recorded in highernumbers. Highest species diversity (Hˊ =2.685), highest species richness (S=39) andhighest evenness (E=0.856) were recorded from outer harbor locations (HFHB1 andHPM). Several species such as Ceratium furca, Chaetoceros sp., Thalassiosira sp.,Rhizosolenia sp. and Protoperidinium sp. known to form harmful algal blooms were alsoobserved in this study.Key words: Zooplankton assemblage, Hambantota port, Ballast water, Invasive AlienSpecies (IAS

Molecular Dynamics Study of Nanoparticles and Non-Ionic Surfactant at an OilWater Interface

Nanoparticles (NPs) and surfactants can spontaneously concentrate at the interface between two immiscible liquids, such as oil and water. Systems of high oil-water interfacial area, such as emulsions, are the basis of many industries and consumer products. Although NPs and surfactants are currently incorporated into many of these applications, their mutual interfacial behavior is not completely understood. Here we present molecular dynamics simulations of NPs and non-ionic surfactant in the vicinity of an oil-water interface. It was found that in low concentration the surfactants and NPs show cooperative behavior in lowering the oil-water interfacial tension, while at higher surfactant concentration this synergy is attenuated. It was also found that binding of surfactants to the NP surface decreases the surfactant efficiency in lowering the interfacial tension, while concurrently creating a barrier to NP aggregation