Paralytic shellfish poisoning toxin analysis of the genus <Emphasis Type="Italic">Alexandrium</Emphasis> (Dinophyceae) occurring in Korean coastal waters

ABSTRACT:   Paralytic shellfish poisoning (PSP) toxins produced by Alexandrium isolates from Korea were analyzed by high-pressure liquid chromography. Species designation of the regional isolates was determined by morphological criteria and ribotyping inferred from sequences of the 28S rDNA D1-D2 region. Toxin analysis performed at the exponential growth phase, revealed that the two strains of A. fraterculus were non-toxic, while the strains of A. tamarense and A. catenella were toxic. Toxic isolates DPC7 and DPC8 of A. catenella produced GTX1, 2, 3, 4, 5, dcGTX2, 3, C1, 2, neoSTX and STX with trace or non-detectable levels of C3 and C4, while isolates UL7, KDW981, SJW97043, SJW97046, KJC97111 and KJC97112 of A. tamarense produced GTX1, 2, 3, 4, dcGTX3, C1, 2, neoSTX with trace or non-detectable levels of C3, 4, dcSTX and STX, and no GTX5 and dcGTX2. The major toxins produced by A. catenella were C1 +2, and those of A. tamarense were C1 +2 and GTX4 in most of the isolates. A. tamarense strains other than SJW97046 produced a relatively high proportion of carbamate toxins, reflecting the high toxicity scores of shellfish intoxication in sampled coastal areas. Two representative toxic isolates, A. tamarense SJW97043 and A. catenella DPC7, were cultured for 30 days in batch mode and subjected to toxin analysis at 5-day intervals. Comparison of toxin productivity in terms of total toxin content, toxin components, and their variations with culture age revealed marked differences between the two strains.     

Immune response of sea bass <Emphasis Type="Italic">Dicentrarchus labrax</Emphasis> to <Emphasis Type="Italic">Tenacibaculum maritimum</Emphasis> antigens

ABSTRACT:   Seawater fishes are affected by a pathology commonly called 'myxobacteriosis', caused by Tenacibaculum maritimum (formerly Flexibacter maritimus ). The disease is characterized by fin erosion and necrotic ulcers of skin and muscle, and by low but constant mortality in cultured marine fish; in Italy is one of the most important and widely spread diseases affecting sea bass Dicentrarchus labrax , gilthead seabream Sparus aurata , sharp-snouted bream Diplodus puntazzo , white bream Diplodus sargus , and six-tooted bream Dentex dentex . In order to obtain an effective vaccine against the disease, formalin killed cells (FKC), extracellular products (ECPs) and crude lipopolysaccharide (LPS) preparations were obtained from the T. maritimum strain SPVId and injected intraperitoneally twice into the sea bass. The fish immune response to the preparations was studied: agglutinating antibody titer and in vitro phagocytosis were determined after the first and second injection in order to evaluate whether the preparations are immunogenic or not and if the booster effect took place. The results show that FKC and LPS preparations increased the antibody titer after the first injection when compared to the control sea bass. Moreover, all the preparations stimulated a secondary (booster) response. In vitro phagocytosis of the total blood was significantly higher for all the preparations when compared to the controls, but the crude LPS immunized sea bass showed the highest activity.     

Incorporation of Maize Gluten in Supplementary Feed and its Impact on Growth and Flesh Quality of Some Carps

Maize gluten (a byproduct from the starch industry) was used at four different levels (5, 10, 15 and 20% w/w) replacing the fish meal, a component of supplementary diet, under a semi-intensive culture system. The impact of different diets on the physico-chemical parameters of water, growth and flesh quality of catla, Catla catla; rohu, Labeo rohita; and mrigal, Cirrhina mrigala was studied. Growth in terms of body weight gain was highest when fed a diet having 5% maize gluten (replacing fish meal at 25% level) for all the fish species. However, incorporation of maize gluten at higher levels led to decline in growth, since maize gluten is deficient in essential amino acids like methionine, lysine and threonine, etc. The flesh quality in terms of total protein, total lipid, total sugar, moisture and total ash was also determined at the termination of the experiment to see whether there was any significant variation with the incorporation of maize gluten or not.     

Response of a Juvenile Cyprinid,Lake Minnow <Emphasis Type="Italic">Eupallasella perenurus</Emphasis> (Pallas), to Different Diets

Three commercial starters (Carp Starter, Uni Starter and Perla Plus) and one non-commercial, with frozen Chironomidae larvae as a reference diet, were evaluated for the intensive rearing of juvenile lake minnow Eupallasella perenurus, a cyprinid fish that is critically endangered in Poland. The growth, condition, survival, body deformities, and chemical body composition were studied. The 90-day laboratory experiment was performed at 22 °C with fish that were initially 24.6 mm (mean total lenth (TL)) and 0.11 g (mean body weight (BW)). Satisfactory fish growth was attained with all of the diets; however, the largest (p ≤ 0.05) final size (48.5 mm TL, 1.55 g BW) and the lowest condition coefficient (K = 1.34) were noted in fish fed the non-commercial starter. The final survival rates were very high (97.5–100%). Skeletal deformities (in 74 to 92% fish) were recorded exclusively in fish fed commercial starters. All commercial starters resulted in considerably higher lipid content and lower ash content than did the non-commercial starter and the reference diet. This suggests that both these factors might be responsible for body deformities. The present results proved that only the non-commercial starter is suitable for juvenile E. perenurus rearing under controlled condition, and that none of the commercial starters can be recommended.     

Improvement of paddy field drainage for mechanization

In Japan, land consolidation and drainage improvement for farm mechanization in paddy fields began during the 1960 s. It was not easy to use big machines in the muddy conditions caused by the clayey soil and heavy rainfall during the harvesting period. A number of investigations were carried out by many researchers, and factors relating to drainage were clarified. Not only surface drainage but also underdrainage was planned. However, drainage was not always sufficient, because the clayey surface soil was impermeable to ponding water. It became clear that underdrainage for a clayey paddy field for the harvest is quite different from underdrainage for an ordinary field. Field and soil characteristics, as well as water conditions, should be examined carefully before planning drainage improvement for farm mechanization.Dr. Toshio Tabuchi is an honorable member of the Japanese Society of Irrigation, Drainage and Reclamation Engineering (JSIDRE), a former Professor of the University of Tokyo, and a former President of JSIDRE     

Abundance of rare earth elements in rice paddy soils from three regions of Sri Lanka

Very few studies deal with the rare earth element (REE) content within paddy soil systems. This paper presents, for the first time, the distribution of REEs in paddy soils from three different regions in Sri Lanka. Seventy samples from the Kalutara and Kandy regions located in the Wet Zone and Anuradhapura region in the Dry Zone were selected for this study. ICP-MS measurements were performed on the soil samples to determine their respective REE concentrations. The sum content of all the REEs (REE) in these three regions were 182, 186 and 132 g/g, respectively. The mean concentrations for the 70 soil samples in µg/g were 35(La), 77 (Ce), 7.6 (Pr), 27.6 (Nd), 4.8 (Sm), 0.87 (Eu), 4.1 (Gd), 0.54 (Tb), 2.91 (Dy), 0.56 (Ho), 1.57 (Er), 0.21(Tm), 1.44 (Tb), and 0.23 (Lu). The chondrite-normalized REE patterns of the paddy soils from the three study areas were similar, which may be a reflection of comparable parent materials. Kalutara soils, which are richer in organic matter and kaolinite, showed a higher lighter REE content and lower heavy REE content with a more pronounced negative Eu anomaly with respect to the other regions. Whilst this may be a result of subtle differences in soil parent materials, it could also reflect secondary processes related to clay mineral and organic matter adsorption of REEs in paddy soils     

Imparting disperse and cationic dyeability to polypropylene through melt blending

The present paper deals with improvement in disperse dyeability as well as imparting of cationic dyeablility to difficultly dyeable polypropylene by a melt blending technique. Isotactic polypropylene (PP) was blended with fibre grade polybutylene terephthalate (PBT), cationic dyeable polyethylene terephthalate (CDPET) and polystyrene (PS), individually. The resulting binary blends were spun and drawn into fibres at draw ratio 2, 2.5, and 3. The compatibility of blends, structural changes of fibres in terms of X-ray crystallinity, relative crystallinity, sonic modulus, birefringence and thermal stability were examined. The blended fibres were found to be disperse dyeable by the conventional method of high temperature and high pressure dyeing. And this dyeability increased with increase in the level of substitution. PP/CDPET blend also exhibited dyeablility with cationic dyes in addition to that with disperse dyes. The optimum level of blending was predicted keeping in view of tenacity and thermal stability of melt blend fibres. The wash fastness properties of the dyed fibres were found to be of high rate.     

Enhanced physico-mechanical properties of polyester resin film using CaCO<Subscript>3</Subscript> filler

Bio-based CaCO₃ powder was synthesized via size reduction method from waste eggshells. The XRD analysis revealed that eggshell powder consists of CaCO₃ in calcite form. The inclusion level of CaCO₃ contents were varied of 5, 10, 15, 20 and 25 wt.% of prepared CaCO₃-polyester film. Effects of different proportions of prepared chicken eggshell and commercial CaCO₃ filler on the polyester resin composites films were compared by means of mechanical and physical test. It was found that the addition of CaCO₃ filler to the polyester films leads to improve the mechanical properties. The findings revealed that the best and optimum CaCO₃ filler content was 10 wt.% and among the prepared polyester films, eggshell CaCO₃-polyester films showed the best performance. The mechanical properties of CaCO₃-polyester films were measured in terms of tensile strength, elongation-at-break, tensile modulus, flexural strength and impact strength. For eggshell CaCO₃- polyester films, the maximum values of the aforementioned mechanical properties were 52.70 MPa, 4.63 %, 1868.70 MPa, 101.20 MPa and 8.40 kJ/m², respectively, whereas for commercial CaCO₃-polyester films those values were 48.12 MPa, 4.50 %, 1790.30 MPa, 97.50 MPa and 8.21 kJ/m², respectively. Further, water absorption of the composite films as a function of time had also been investigated at 10 wt.% filler content.     

Effect of pH on the physicochemical and heat-induced gel properties of scallop <Emphasis Type="Italic">Patinopecten yessoensis</Emphasis> actomyosin

Gelation is an important functional property of protein in meats. In this study, we prepared actomyosin from scallop Patinopecten yessoensis adductor muscles and studied the effects of pH on the physicochemical properties of the actomyosin preparation and on its heat-induced gel-forming properties. The results showed that the turbidity and surface hydrophobicity of scallop actomyosin increased with increases in the heating temperature, while the α-helical content concomitantly decreased. Higher turbidity and surface hydrophobicity and lower α-helical content were found to be easily obtained at lower pH values. A high water-holding capacity, strong gel strength, fine gel network and uniform ice crystals were all clearly observed at pH 7.0, indicating that a neutral pH was most beneficial for formation of the heat-induced scallop actomyosin gel. We therefore conclude that both the physicochemical properties of scallop actomyosin and its gel-forming ability during the heating process are pH dependent.