Cryptobia (Trypanoplasma) salmositica and salmonid cryptobiosis

Salmonid cryptobiosis is caused by Cryptobia (Trypanoplasma) salmositica. The haemoflagellate has been reported from all species of Pacific Oncorhynchus spp. on the west coast of North America. It is normally transmitted by the freshwater leech, Piscicola salmositica, in streams and rivers, and sculpins, Cottus spp., are considered important reservoir hosts. The pathogen can also survive on the body surface of fish because it has a contractile vacuole to osmoregulate when the fish is in fresh water. This allows for direct transmission between fish, especially in aquaculture facilities. The parasite divides rapidly by binary fission in the blood to cause disease, the severity of which is directly related to parasitaemia. Cryptobia salmositica has a mitochondrium and it normally undergoes aerobic respiration; however, if its mitochondrium is damaged it will switch to glycolysis. Its glycolytic enzymes and catalase are contained in glycosomes. Cysteine protease is a metabolic enzyme, and its neutralization inhibits oxygen consumption and multiplication of the parasite. An important virulent factor in cryptobiosis is a secretory metalloprotease. The protective mechanism involves production of complement fixing antibodies, phagocytosis by macrophages, and cell-mediated cytotoxicity. Recovered fish are protected, probably for life as the immunity is non-sterile. Clinical signs of the disease include anaemia, anorexia, splenomegaly, general oedema and abdominal distension with ascites. The metabolism and swimming performance of infected fish are significantly reduced and the bioenergetic cost of the disease is very considerable. Fish are susceptible to hypoxia and their immune system is depressed during acute cryptobiosis. Severity of the disease and mortality rates vary significantly between species and stocks of salmon. Protective strategies include selective breeding of Cryptobia-resistant fish. This is innate resistance to infection and it is controlled by a dominant Mendelian locus. In these fish the parasite is lysed via the alternative pathway of complement activation. In Cryptobia-tolerant fish (infected with the pathogen but which do not suffer from disease) the metalloprotease secreted by the parasite is neutralized by alpha2 macroglobulin. Hence, the production of a transgenic Cryptobia-tolerant salmon is an option. This strategy has the advantage in that human intervention (e.g. vaccination, chemotherapy) is not required once the transgenic fish is produced. Acquired immunity is another option; a single dose of the attenuated live vaccine protects fish for at least 2 years. The protective mechanism in vaccinated fish is similar to that in recovered fish. The trypanocidal drug, isometamidium chloride, is an effective therapeutic and prophylactic agent. It accumulates in the mitochondrium of the parasite and significantly disrupts aerobic respiration by causing lesions in the organelle. Efficacy of the drug is significantly increased after its conjugation to antibodies. This immuno-chemotherapeutic strategy has the advantage in that it will lower the drug dosage and hence side-effects of chemotherapy. It will probably reduce the accumulation of the drug in fish, an important consideration in food fish.     

Effects of Dietary Supplementation of Barodon on Growth Performance,Innate Immunity and Disease Resistance of Juvenile Olive Flounder,Paralichthys olivaceus,Against Streptococcus iniae

This study was conducted to evaluate the effects of dietary supplementation of Barodon, an anionic alkali mineral complex, on growth, feed utilization, humoral innate immunity and disease resistance of olive flounder. A basal experimental diet was used as a control and supplemented with 0.1, 0.2, 0.3, 0.4, or 0.5% Barodon. Triplicate groups of fish (26.4 ± 0.2 g) were fed one of the diets to apparent satiation twice daily for 10 wk. The growth performance was enhanced (P < 0.05) linearly and quadratically in fish fed diets containing Barodon compared with that in fish fed the control. Feed utilization was significantly improved by Barodon supplementation. Serum lysozyme and antiprotease activities were increased quadratically in Barodon fed groups. Also, significantly higher superoxide dismutase activity was found in Barodon‐fed fish. Dietary supplementation of 0.1–0.3% Barodon resulted in significant enhancement of fish disease resistance against Streptococcus iniae. The findings in this study indicate that dietary supplementation of Barodon can enhance growth, feed utilization, innate immunity, and disease resistance of olive flounder and that the optimum level seems to be 0.1% in diets.     

The effect of temperature on the energy budget of the Manila clam, <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis>

In this study, the energy budget of the Manila clam, Ruditapes philippinarum, was evaluated after one-week acclimation periods at 5, 10, 15, 20, and 25°C. Small clams (151 ± 12 mg DW) and large clams (353 ± 16 mg DW) were fed with the microalgae, Isochrysis galbana. Filtration rate, ingestion rate, assimilation efficiency, oxygen-consumption rate, and ammonia excretion rate were measured. Both filtration rate and ingestion rate of small and large clams were found to be related to temperature. The highest Q ₁₀ values were measured in the range 15–20°C for both small and large clams. Assimilation efficiency of both small and large clams was not significantly influenced by temperature, although the maximum mean values were detected at 20°C. Oxygen consumption rate and ammonia excretion rate of small and large clams were found to be related directly to temperature over the entire range, with a maximum being detected at 25°C. The highest Q ₁₀ value was estimated in the range 10–15°C with regard to oxygen consumption rate, and in the range of 15–20°C with regard to ammonia excretion rate. Scope for growth (SFG) was positive at all temperatures, achieving a maximum value at 20°C in both small and large clams, primarily as a consequence of the enhanced ingestion rate which offset the concomitant elevation in the metabolic rate. In this study we have estimated the thermal optimum for this species at 20°C.     

Utilization of monolinolein as a substrate for conjugated linoleic acid production by Bifidobacterium breve LMC 520 of human neonatal origin

This study was designed to isolate bifidobacteria from human intestines that efficiently converts monolinolein, a monoglyceride form of linoleic acid, into conjugated linoleic acid (CLA), as well as to optimize culture conditions for improving CLA production during milk fermentation. Among 150 screened neonatal bifidobacteria, Bifidobacterium breve LMC 520 showed the highest CLA-producing ability and was tested with different types of fat substrates at various concentrations to determine the optimal conditions for CLA production. Monolinolein was tested as a substrate for CLA production. The incubation time optimized for CLA production was 24 h, and CLA production was proportionally increased with monolinolein concentration. The incubation of LMC 520 with commercial starter strains caused minimal reduction in CLA production. Our results demonstrate that the CLA-producing ability of B. breve LMC 520 could offer beneficial effects when utilized as a starter culture for the development of functional dairy products.     

Mutational optimization of the coelenterazine-dependent luciferase from Renilla

Renilla luciferase (RLUC) is a popular reporter enzyme for gene expression and biosensor applications, but it is an unstable enzyme whose catalytic mechanism remains to be elucidated. We titrated that one RLUC molecule can turn over about one hundred molecules of coelenterazine substrate. Mutagenesis of active site residue Pro220 extended the half-life of photon emission, yielding brighter luminescence in E. coli. Random mutagenesis uncovered two new mutations that stabilized and increased photon emission in vivo and in vitro, while ameliorating substrate inhibition. Further amended with a previously identified mutation, a new triple mutant showed a threefold improved k_cat, as well as elevated luminescence in Arabidopsis. This advances the utility of RLUC as a reporter protein, biosensor, or resonance energy donor.     

Functional efficacy analysis of Angelica gigas Nakai on chicken myoblast cells through cell‐based in vitro assay

The value‐added products in livestock industry is one of the key issues in order to maximize the revenue and to create a new business model. Numerous studies have suggested application of herbal plants as feed additives to increase health, productivity, and/or high‐quality product in livestock. In this study, the first experiment was designed to develop in vitro evaluation system by using primary chicken myoblast (pCM) cells isolated from pectoralis major of 10‐day‐old male embryos. Subsequently, to evaluate effects of Korean Danggui Angelica gigas Nakai (AGN), we optimized the concentration of AGN root extract for treatment of primary pCM cells. After the treatment of AGN root extract, we compared proliferation and differentiation capacity, and also examined the gene expression. In the second experiment, the next generation sequencing analysis was performed to compare the different patterns of the global gene expression in pCM cells treated with AGN extract. Three up‐regulated (pancreas beta cells, fatty acid metabolism and glycolysis) and one down‐regulated (adipogenesis) gene sets were characterized suggesting that the AGN extract affected the metabolic pathways for the utilization of fat and glucose in chicken muscle cells. Furthermore, we validated the expression patterns of the up‐regulated genes (GCLC, PTPN6, ISL1, SLC25A13, TGFBI, and YWHAH) in the AGN‐treated pCM cells by quantitative RT‐PCR. These results demonstrated that the treatment of AGN extract decreased proliferation and differentiation of pCM cells, and affected the metabolic pathways of glucose and fatty acids. Moreover, AGN extract derived from byproducts such as stem and leaf also showed the reduced proliferation patterns on AGN‐treated pCM cells. Taken together, pCM cell‐based in vitro assay system could be primarily and efficiently applied for evaluating the biofunctional efficacy of various feed additive candidates.     

三种水稻钻心害虫防治标准的商榷

为探求害虫防治时期,和发生数量方面的防治标准,以三化螟(Tryporyza incertulas (Wlk.)、二化螟(Chilo suppressalis Wlk.)和稻瘿蚊(Pachydiplosis oryzae Wood-mason)三种水稻钻心害虫为材料,探討钻心类害虫防治标准的規律,提出如下意見: 1.关于防治时期的标准,認为可将施药时虫态的发育进度百分率数字,换算为概率单位,在概率单位为4—6时,相当于15.87—84.13％时的害虫相对发生数量,占全世代总发生数量的68.268％,可見在該段短时間(一般約十数天)的虫数,代表了虫羣的大半数,可看作标准的盛发期,在此时間数列范围內,似可作为防治时期的标准。 2.关于发生数量的防治标准,以三化螟及稻瘿蚊为例进行討論:認为应以幼虫侵入作物后至老熟(或蛹化)期間,每虫所能造成的被害株数为基础,求出幼虫密度的防治标准,然后根据調查时的不同虫态,再伸算各該虫态的防治标准。本文列举了各虫态密度防治标准的計算公式,并以广州及南京两地的三化螟和广东信宜的稻瘿蚊为例,作出在各种具体条件下,虫口密度防治标准检索表。     

Effect of matrigel on the osteogenic potential of canine adipose tissue-derived mesenchymal stem cells

Adipose tissue-derived mesenchymal stem cells (Ad-MSCs) are a promising source of cells for bone tissue engineering. Matrigel is a basement membrane extract containing multiple extracellular components. This mixture may promote the osteogenic differentiation of MSCs and provide a more appropriate microenvironment for transplanted cells. Here, we investigated the effect of Matrigel on the osteogenic potential of Ad-MSCs. Canine Ad-MSCs were cultured in 2D and 3D matrices and implanted into subcutaneous pouches of dogs either with or without Matrigel. Culture mineralization, cell adhesion efficiency, cell proliferation, osteoid matrix production and alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase activities were quantified and compared. Ad-MSCs grown in 2D cultures with Matrigel showed higher levels of calcium deposition and ALP activity than those grown in the absence of Matrigel under osteogenic conditions. In 3D cultures, the cells cultivated with Matrigel showed greater attachment, proliferation and osteogenic differentiation than those grown without Matrigel. In vivo, Ad-MSCs implanted with Matrigel showed higher osteogenic potential than those without Matrigel. In conclusion, these data suggest that the use of Matrigel can increase the osteogenic potential of canine Ad-MSCs.     

Protein digestibility of porcine colostrum by neonatal pigs

Colostrum plays an important role in neonatal growth and development. However, little is known about the digestion of macronutrients in colostrum of any species. This study was conducted with the neonatal piglet model to determine the digestibility of proteins in porcine colostrum. Twelve, 1-d-old, male piglets were selected from 3 litters (4 pigs/litter) and housed individually in metabolism crates with heating lamps to maintain a temperature of 35 °C. Colostrum (13 L) was collected from 400 sows (30 to 40 mL/sow) within 12 h postpartum after injection of oxytocin. All piglets were fed colostrum containing 0.25% (DM basis) chromium oxide as an external marker based on the following feeding program: 6 meals/d for an entire 3-d period; with 40 mL/meal for d 1 (240 mL/d), 55 mL/meal for d 2 (330 mL/d), and 70 mL/meal for d 3 (420 mL/d). Colostrum was hand-fed using baby milk bottles. Entire fecal samples with the chromium green color were collected each day after colostrum feeding. Fecal collection was terminated before the fading of the green color. Fecal samples were weighed (10.3 ± 1.0 g/pig), stored in − 20 °C, freeze-dried, and thoroughly ground for chemical analysis. Blood samples were collected at 0900 h of d 3 to obtain plasma samples for amino acid and immunoglobulin (Ig) G analysis. Digestibilities of crude protein and DM in colostrum, defined as the percentage of ingested colostral crude proteins and DM that disappeared in the gut, averaged 96.9 ± 0.4% and 98.3 ± 0.2%, respectively. Digestibility of total amino acids (protein-bound plus free amino acids) in the colostrum was 98.3 ± 0.1%, with the values being 98.5 ± 0.3, 98.2 ± 0.4, and 98.3 ± 0.3%, respectively, for Lys, Thr, and Arg. Plasma and colostral IgG content were 3.4 ± 0.3 and 3.8 ± 0.7 g/L, respectively. In conclusion, protein-bound and free amino acids in porcine colostrum were highly digestible and available to neonatal pigs.