Sexual reproduction and genetic polymorphism within the cosmopolitan marine diatom Pseudo-nitzschia pungens

Different clades belonging to the cosmopolitan marine diatom Pseudo-nitzschia pungens appear to be present in different oceanic environments, however, a ‘hybrid zone’, where populations of different clades interbreed, has also been reported. Many studies have investigated the sexual reproduction of P. pungens, focused on morphology and life cycle, rather than the role of sexual reproduction in mixing the genomes of their parents. We carried out crossing experiments to determine the sexual compatibility/incompatibility between different clades of P. pungens, and examined the genetic polymorphism in the ITS2 region. Sexual reproduction did not occur only between clades II and III under any of experimental temperature conditions. Four offspring strains were established between clade I and III successfully. Strains established from offspring were found interbreed with other offspring strains as well as viable with their parental strains. We confirmed the hybrid sequence patterns between clades I and III and found novel sequence types including polymorphic single nucleotide polymorphisms (SNPs) in the offspring strains. Our results implicate that gene exchange and mixing between different clades are still possible, and that sexual reproduction is a significant ecological strategy to maintain the genetic diversity within this diatom species.

Maximizing biomass and lipid production in Ettlia sp. by ultraviolet stress in a continuous culture

Lipid production in microalgae can be induced by various stress factors. However, stress induced lipid accumulation requires considerable time leading to the decrease in lipid productivity. Here, we attempted to increase the lipid productivity while maintaining the high growth of Ettlia sp. by optimizing nitrogen concentration and UV exposure in a continuous culture. The biomass and lipid productivities of Ettlia sp. cultured with 150 mg N L^-1 and UV-A added PAR were 1.67 ± 0.08 g L^-1 d^-1 and 0.55 ± 0.05 g L^-1 d^-1, respectively. Lipid productivity and lipid content were around 43.7% and 33.7% higher, respectively in UV-A treatment compared to the control. Moreover, gene-expression patterns related to antioxidant defense and intracellular ROS levels indicated that UV-A affected certain ROS and antioxidants pathways and successfully induced the lipid accumulation in Ettlia sp. This strategy to activate lipid accumulation can be applied in other microalgae without affecting their growth.

Dynamics of Amoebophrya parasites during recurrent blooms of the ichthyotoxic dinoflagellate Cochlodinium polykrikoides in Korean coastal waters

During the bloom events of the harmful dinoflagellate Cochlodinium polykrikoides in August and October, 2012, infections by two different Amoebophrya species were observed in Korean coastal waters. To investigate the dynamics of the two parasites and their relative impact on the host populations, a quantitative real-time PCR (qPCR) method was applied to detect and quantify the parasites in the free-living and parasitic stages. Each specific primer set of the target species, Amoebophrya sp. 1 and sp. 2 was designed on the large subunit (LSU) and the first internal transcribed spacer (ITS1) of ribosomal RNA (rRNA) gene, respectively. Dynamics of the two Amoebophrya species via qPCR assay showed distinct patterns during the C. polykrikoides bloom events. Amoebophrya sp. 1 showed peaks during both bloom events in August and October with relatively low copies (10⁶ to 10⁷ copies L^-1), while Amoebophrya sp. 2 appeared only during the bloom event in October with very high copies (10⁹ to 10¹⁰ copies L^-1). Overall, the qPCR measurements for the dynamics of two Amoebophrya species in the parasitic stage (> 5 μm fractions) were consistent with parasite prevalence through microscopic observations. Amoebophrya sp. 1 infections were observed during both bloom events in August and October with relatively low parasite prevalence (0.1-1.5%), while Amoebophrya sp. 2 infections were detected only during the bloom event in October with high prevalence (up to 45%). Taken together, Amoebophrya sp. 1 may be a generalist and C. polykrikoides may not be its primary host, while Amoebophrya sp. 2 may be a specialist which can substantially impact host population dynamics.

Pelagibaca bermudensis promotes biofuel competence of Tetraselmis striata in a broad range of abiotic stressors: dynamics of quorum-sensing precursors and strategic improvement in lipid productivity

BACKGROUND

Amelioration of biofuel feedstock of microalgae using sustainable means through synthetic ecology is a promising strategy. The co-cultivation model (Tetraselmis striata and Pelagibaca bermudensis) was evaluated for the robust biofuel production under varying stressors as well as with the selected two-stage cultivation modes. In addition, the role of metabolic exudates including the quorum-sensing precursors was assessed.

RESULTS

The co-cultivation model innovated in this study supported the biomass production of T. striata in a saline/marine medium at a broad range of pH, salinity, and temperature/light conditions, as well as nutrient limitation with a growth promotion of 1.2-3.6-fold. Hence, this developed model could contribute to abiotic stress mitigation of T. striata. The quorum-sensing precursor dynamics of the growth promoting bacteria P. bermudensis exhibited unique pattern under varying stressors as revealed through targeted metabolomics (using liquid chromatography-mass spectrometry, LC-MS). P. bermudensis and its metabolic exudates mutually promoted the growth of T. striata, which elevated the lipid productivity. Interestingly, hydroxy alkyl quinolones independently showed growth inhibition of T. striata on elevated concentration. Among two-stage cultivation modes (low pH, elevated salinity, and nitrate limitation), specifically, nitrate limitation induced a 1.5 times higher lipid content (30-31%) than control in both axenic and co-cultivated conditions.

CONCLUSION

Pelagibaca bermudensis is established as a potential growth promoting native phycospheric bacteria for robust biomass generation of T. striata in varying environment, and two-stage cultivation using nitrate limitation strategically maximized the biofuel precursors for both axenic and co-cultivation conditions (T and T-PB, respectively). Optimum metabolic exudate of P. bermudensis which act as a growth substrate to T. striata surpasses the antagonistic effect of excessive hydroxy alkyl quinolones [HHQ, 4-hydroxy-2-alkylquinolines and PQS (pseudomonas quorum signal), 2-heptyl-3-hydroxy-4(1H)-quinolone].

Revealing the distinct habitat ranges and hybrid zone of genetic sub-populations within Pseudo-nitzschia pungens (Bacillariophyceae) in the West Pacific area

Genetic sub-populations (clades) of cosmopolitan marine diatom Pseudo-nitzschia pungens might have distinct habitats, and their hybrid zone is suspected in higher latitude area of the West Pacific area, however, it is still unrevealed because of technical difficulties and lack of evidences in natural environments. The aim of this study is to investigate the habitat characteristics of each clade of P. pungens on geographical distribution with the habitat temperature ranges of each clade and to reveal their hybrid zone in the West Pacific area. We employed the 137 number of nucleotide sequences of P. pungens and its sampling data (spatial and temporal scale) originated from the West Pacific area, and used field application of qPCR assay for intra-specific level of P. pungens. Only two genotypes, clade I and III, were identified in the West Pacific area. Clade I was distributed from 39 to 32.3°N, and clade III were from 1.4 to 34.4°N. The estimated habitat temperature for the clade I and clade III ranges were 8.1-26.9 °C and 24.2-31.2 °C, respectively. The latitudinal distributions and temperature ranges of each clade were significantly different. The qPCR assay employed, and results suggested that the hybrid zone for clade I and III has been observed in the southern Korean coasts, and clade III might be introduced from the Southern Pacific area. The cell abundances of clade III were strongly related with the higher seawater temperature and warm current force. This study has defined distinct habitat characteristics of genetically different sub-populations of P. pungens, and revealed its hybrid zone in natural environment for the first time. We also provided strong evidences about dispersion of the population of clade III to higher latitude in the West Pacific area.

Distinct Bloom Dynamics of Toxic and Non-toxic Microcystis (Cyanobacteria) Subpopulations in Hoedong Reservoir (Korea)

Despite the importance of understanding the bloom mechanisms that influence cyanobacterial toxin production, the dynamics of toxic Microcystis subpopulations are largely unknown. Here, we quantified both toxic and entire (i.e., toxic and non-toxic) Microcystis populations based on the microcystin synthetase E (mcyE) and 16S ribosomal RNA genes. Samples were collected from pelagic water and sediments twice per week from October to December 2011, and we investigated the effects of physicochemical factors (pH, water temperature, dissolved oxygen, nutrients, etc.) and biological factors (ciliates and zooplankton) on the abundance of toxic and non-toxic Microcystis. During the study period, Microcystis blooms were composed of toxic and non-toxic subpopulations. Resting stage Microcystis in sediment may be closely linked to Microcystis populations in pelagic water and may contribute to the toxic subpopulation composition in surface Microcystis blooms. In pelagic water, the toxic and entire Microcystis population had a significant positive correlation with the pH and water temperature (p < 0.05). However, their responses to changes in environmental factors were thought to be distinct. The ratio of the toxic to non-toxic Microcystis subpopulations was significantly (p < 0.05) enhanced by a lower pH and water temperature and an increase in protozoan grazers, reflecting environmental stresses. These results suggest that the toxic and non-toxic subpopulations of Microcystis have distinct tolerance levels against these stressors. The intracellular microcystin (MC) concentration was positively associated with the abundance of the mcyE-positive Microcystis. By comparison, the MC concentration in pelagic water body (extracellular) increased when Microcystis was lysed due to environmental stresses.

Intraspecific bloom succession in the harmful dinoflagellate Cochlodinium polykrikoides (Dinophyceae) extended the blooming period in Korean coastal waters in 2009

Although there have been extensive studies on dinoflagellate blooms in recent decades, the mechanism that allows the maintenance of blooms over long periods remains uncertain, and studies on genetically differentiated subpopulations may provide insights into this mechanism. In this study, the influence of two genetically distinct subpopulations of the dinoflagellate Cochlodinium polykrikoides, referred to as Group I and IV, on bloom duration in Korean coastal waters (KCW) was examined using a quantitative PCR (qPCR) assay. In this study, a C. polykrikoides bloom occurred over a longer period in 2009 (49 days), whereas the bloom period was shorter in 2010 (35 days). The qPCR results indicate that intraspecific bloom succession between Groups I and IV occurred in 2009, whereas only a single subpopulation (Group I) was responsible for the bloom in 2010. Based on the statistical analysis, the Group I and Group IV blooms occurred under significantly different environmental conditions (p ≤ 0.05) in terms of water temperature, pH, and phosphate concentration, and these subpopulations exhibited significantly different relationships with environmental factors, particularly water temperature (p < 0.01). This variability may allow blooms to continue through intraspecific bloom succession even after environmental conditions change. Southern KCW are affected by outer regions via the Tsushima Warm Current (TWC) every summer. Group IV (≤1108 ± 69 cells L^-1) was primarily observed along the route of the TWC in summer 2009, when the bloom of this subpopulation occurred in southern KCW. These results suggest that Group IV transported via the TWC may have influenced the bloom dynamics of this subpopulation in summer 2009.

Light intensity as major factor to maximize biomass and lipid productivity of Ettlia sp. in CO2-controlled photoautotrophic chemostat

The optimal culture conditions are critical factors for high microalgal biomass and lipid productivity. To optimize the photoautotrophic culture conditions, combination of the pH (regulated by CO₂ supply), dilution rate, and light intensity was systematically investigated for Ettlia sp. YC001 cultivation in a chemostat during 143days. The biomass productivity increased with the increase in dilution rate and light intensity, but decreased with increasing pH. The average lipid content was 19.8% and statistically non-variable among the tested conditions. The highest biomass and lipid productivities were 1.48gL^-1d^-1 and 291.4mgL^-1d^-1 with a pH of 6.5, dilution rate of 0.78d^-1, and light intensity of 1500μmolphotonsm^-2s^-1. With a sufficient supply of CO₂ and nutrients, the light intensity was the main determinant of the photosynthetic rate. Therefore, the surface-to-volume ratio of a photobioreactor should enable efficient light distribution to enhance microalgal growth.

Ecological assessment of an algaecidal naphthoquinone derivate for the mitigation of Stephanodiscus within a mesocosm

The novel eco-friendly algaecidal naphthoquinone derivate was used to control harmful algal bloom causing species Stephanodiscus and, its effect was assessed on other undesired and non-targeted microbial communities. We conducted a mesocosm experiment to investigate the effects of this novel algaecide on native microbial communities rearing in water collected from Nakdonggang River. Upon treatment of the mesocosm with the naphthoquinone derivate the concentration of Chl-a decreased from 20.4 μg L^-1 to 9.5 μg L^-1 after 2 days. The turbidity has also shown decrement (exhibited 15.5 NTU on the 7th day). The concentrations of DOC and phosphate in the treatment were slightly higher than those in the control due to the decomposition of dead Stephanodiscus, whereas the DO and pH in the treated condition were slightly lower than those in the control; which was due to increment of organic acids and higher degradation activity. Results showed that bacterial abundance were not significantly different but community composition were slightly different as revealed by NGS (Next generation sequencing). The variation in HNF (Heterotrophic nanoflagellates) revealed that the bacterial community composition changed following the change in bacterial abundance. During the treatment, the abundance of Stephanodiscus was significantly reduced by more than 80% after 6 days, and the abundance of ciliates and the dominant species, Halteria grandinella, had shown marked decline. The abundance of zooplankton sharply decreased to 5 ind. L^-1on the 8th day but increased again by the end of the study period. The Shannon-Wiener diversity index of phytoplankton, ciliates and zooplankton in the treated mesocosm increased significantly after 4, 7 and 8 days, respectively. The marked changes in the ecosystem structure were observed in treatment compare to control. However, the beneficial microalgal populations were not affected which indicated possibility of restoration of treated ecosystem and regain of healthy community structure after certain period.

Identification of Azadinium species and a new azaspiracid from Azadinium poporum in Puget Sound, Washington State, USA

The identification of a new suite of toxins, called azaspiracids (AZA), as the cause of human illnesses after the consumption of shellfish from the Irish west coast in 1995, resulted in interest in understanding the global distribution of these toxins and of species of the small dinoflagellate genus Azadinium, known to produce them. Clonal isolates of four species of Azadinium, A. poporum, A. cuneatum, A. obesum and A. dalianense were obtained from incubated sediment samples collected from Puget Sound, Washington State in 2016. These Azadinium species were identified using morphological characteristics confirmed by molecular phylogeny. Whereas AZA could not be detected in any strains of A. obesum, A. cuneatum and A. dalianense, all four strains of A. poporum produced a new azaspiracid toxin, based on LC-MS analysis, named AZA-59. The presence of AZA-59 was confirmed at low levels in situ using a solid phase resin deployed at several stations along the coastlines of Puget Sound. Using a combination of molecular methods for species detection and solid phase resin deployment to target shellfish monitoring of toxin at high-risk sites, the risk of azaspiracid shellfish poisoning can be minimized.

Improvement of cyanobacterial-killing biologically derived substances (BDSs) using an ecologically safe and cost-effective naphthoquinone derivative

In previous studies, naphthoquinone (NQ) compounds have been shown to be effective, selective, and ecologically safe algicides for controlling harmful algal blooming species (HABs) or winter bloom species, such as Stephanodiscus hantzschii. However, there are no reports on NQ-based algicides for use with cyanobacterial blooming species. In this study, we developed 31 NQ compounds to investigate algicides for mitigating cyanobacterial blooms. In addition, to better apply these compounds in the field, we reduced the number of production steps to develop a cost-effective algicide. In preliminary testing, we screened NQ compounds that showed the best algicidal activity on target cyanobacteria, including Aphanizomenon, Dolichospermum, Microcystis, Oscillatoria, and Nostoc species. The compound NQ 2-0 showed the highest algicidal activity (90%) at a low concentration (≥1μM) on target algae. These were very limiting algicidal effects of 1µM NQ 2-0 observed against non-target algae, such as diatoms (Stephanodiscus hantzschii, Cyclotella meneghiniana, Synedra acus, and Aulacoseira granulata) or green algae (Cosmarium bioculatum and Scenedesmus quadricauda), and the effect did not exceed 15-25% (except against S. quadricauda). NQ 2-0 (1μM) showed no eco-toxicity, as represented by the survival rates of Pseudokirchneriella subcapitata (100%), Daphnia magna (100%), and Danio rerio (100%). Additionally, a chronic eco-toxicity assessment showed no toxicity toward the survival, growth or reproduction of D. magna. Moreover, NQ 2-0 quickly dissipated from field water samples and had a half-life of approximately 3.2 days. These results suggest that NQ 2-0 could be a selective and ecologically safe algicide to mitigate harmful cyanobacterial blooms.

Development of a qPCR assay for tracking the ecological niches of genetic sub-populations within Pseudo-nitzschia pungens (Bacillariophyceae)

Three genetic sub-populations (clade I, II and III) of Pseudo-nitzschia pungens, the potential toxic marine diatom, are known to have distinguishable growth characteristics under different culture conditions and distinct distributed patterns in the world. However, to date their exact eco-physiological traits are unrevealed in fields due to lack of the method to detect and/or measure abundances of each sub-populations, hence, the qPCR (quantitative real-time polymerase chain reaction) assay was developed to detect and quantify the P. pungens cells of each clade. Designed two specific primer sets, Pcla12F/R (for clade I and II) and Pcla3F/R (for clade III) only could amplify each target genomic DNA. The, significant linear relationships (R²>0.998) was established between C_t (threshold cycle) value and the log of cell abundance for each clade. Through the melting curve analysis, comparisons for gene copy numbers among the three clades and spike test for field study, our qPCR assay was reliable to quantify the cell numbers of each clade. There was strong linear correlation (R²>0.990) between cell abundances as estimated by qPCR assay and direct counting via light microscope in spike test, and 0.24 (clade I), 0.25 (clade II) and 0.33 (clade III) P. pungens cells per mL were detected markedly upon the use of specific two-primer set. Finally, developed qPCR assay was applied on field samples successfully. Our study implicate that our qPCR assay is an accurate and sensitive technique to estimate the cell abundances of each clade of P. pungens in field works.

Phycospheric Native Bacteria Pelagibaca bermudensis and Stappia sp. Ameliorate Biomass Productivity of Tetraselmis striata (KCTC1432BP) in Co-cultivation System through Mutualistic Interaction

Effective sustainable algal cultivation techniques are essential for mass production of the marine microalga Tetraselmis for biofuel and array of co-products. The phycospheric communities affect the microalgal growth and metabolism through various allelochemical and nutrient interactions; hence, their potential to affect the quantity and quality of both biomass and bioproducts is significant. In the present study, we have screened the phycospheric communities of biofuel producing Tetraselmis striata (KCTC1432BP). A total of 26 bacterial strains were isolated and identified from the phycosphere of T. striata mass culture. Then, each bacterial strain was tested in co-cultivation conditions with T. striata for evaluating its growth promoting and inhibitory effects. Among these all strains, two promising strains (Pelagibaca bermudensis KCTC 13073BP and Stappia sp. KCTC 13072BP) were selected because of their maximum growth promoting effects and mutualistic interactions. The growth rate, biomass productivity, lipid contents, and fatty acids were analyzed during their combined growth in O3 media and compared with axenic growth of T. striata. Later, growth promoting mechanisms in the co-cultivation environment were investigated for these promising bacterial strains under replete and limited conditions of nutrients (nitrate, phosphate, and vitamin B₁₂). The growth promoting potential of P. bermudensis was illustrated by the two fold enhancement in biomass productivity. These bacteria are promising for microalgal cultivation without any negative effects on the native seawater bacterial communities, as revealed by next generation sequencing analysis. This study represents, to date, the first report highlighting the role of phycospheric growth promoting bacteria of promising biofuel feedstock T. striata.

A mutualistic interaction between the bacterium Pseudomonas asplenii and the harmful algal species Chattonella marina (Raphidophyceae)

Several studies on various Chattonella species have reported that bacteria may play an important role in Chattonella bloom initiation, however, no studies have described how these bacteria promote the growth of C. marina. The interaction between C. marina and bacteria was investigated for identification and characterization of potential growth-promoting bacteria. In preliminary tests, the growth promoting effect of Pseudomonas species (25 strains) was investigated and P. asplenii (≥2.27) was determined as a growth-promoting bacteria for both C. marina strains (CCMP 2049 and 2050). This bacterium exerted optimal growth-promoting effects on C. marina, causing an increase in the initial density of P. asplenii to approximately 1×10⁷cellsmL^-1, which was used as the initial density in this study. To determine whether the growth-promoting activity was direct or indirect, P. asplenii was incubated in the algal media and then a filtrate of this culture was added to both C. marina strains. The P. asplenii filtrate stimulated the growth of C. marina and maintained the growth-promoting effects after high temperature (121°C for 20min) and pressure (15psi) treatment. Thus, P. asplenii is able to promote C. marina growth through the release of a heat-resistant substance, such as inorganic nutrients. A nutrient analysis indicated that this bacterium elevated the phosphate concentration. Interestingly, P. asplenii was unable to survive in phosphate-limited media but could grow in phosphate-limited media incubating C. marina. Moreover, this bacterium could secrete significantly more phosphate in the presence of C. marina (p<0.0001). These results suggested that P. asplenii and C. marina may have a mutualistic interaction.

An Improved Quantitative Real-Time PCR Assay for the Enumeration of Heterosigma akashiwo (Raphidophyceae) Cysts Using a DNA Debris Removal Method and a Cyst-Based Standard Curve

The identification and quantification of Heterosigma akashiwo cysts in sediments by light microscopy can be difficult due to the small size and morphology of the cysts, which are often indistinguishable from those of other types of algae. Quantitative real-time PCR (qPCR) based assays represent a potentially efficient method for quantifying the abundance of H. akashiwo cysts, although standard curves must be based on cyst DNA rather than on vegetative cell DNA due to differences in gene copy number and DNA extraction yield between these two cell types. Furthermore, qPCR on sediment samples can be complicated by the presence of extracellular DNA debris. To solve these problems, we constructed a cyst-based standard curve and developed a simple method for removing DNA debris from sediment samples. This cyst-based standard curve was compared with a standard curve based on vegetative cells, as vegetative cells may have twice the gene copy number of cysts. To remove DNA debris from the sediment, we developed a simple method involving dilution with distilled water and heating at 75°C. A total of 18 sediment samples were used to evaluate this method. Cyst abundance determined using the qPCR assay without DNA debris removal yielded results up to 51-fold greater than with direct counting. By contrast, a highly significant correlation was observed between cyst abundance determined by direct counting and the qPCR assay in conjunction with DNA debris removal (r2 = 0.72, slope = 1.07, p < 0.001). Therefore, this improved qPCR method should be a powerful tool for the accurate quantification of H. akashiwo cysts in sediment samples.

Can the algicidal material Ca-aminoclay be harmful when applied to a natural ecosystem? An assessment using microcosms

We assessed the ability of an artificial clay (Ca-aminoclay) to suppress harmful algal bloom species (HABs) such as Cochlodinium polykrikoides and Chattonella marina and investigated the ecological responses in the closed and open microcosm systems. The Ca-aminoclay induced rapidly and selectively cell lysis in the HABs. However, applying Ca-aminoclay could cause adverse impacts in terms of biological and environmental changes. The bacterioplankton abundance increased and then, the abundances of heterotrophic nanoflagellates and ciliates increased rapidly. Extremely poor environmental conditions such as increase in nutrients and development of anoxic conditions were sustained continuously in a closed system, while the environmental conditions in open systems deteriorated before recovering to the initial conditions. We evaluated the potential for the occurrence of a bloom of another phytoplankton after HABs had been controlled using the Ca-aminoclay. The Ca-aminoclay controlled blooms of Chattonella marina in mixed cell cultures containing a Tetraselmis chui. However, T. chui increased over time and then bloomed. Therefore, caution should be taken when considering the direct application of Ca-aminoclay in natural environments even though it offers the rapid removal of HABs.

Dynamics of bacterial community structure during blooms of Cochlodinium polykrikoides (Gymnodiniales, Dinophyceae) in Korean coastal waters

Recent studies of dinoflagellates have reported that blooms can be closely related to the characteristics of the associated bacteria, but studies of the correlation between the toxic dinoflagellate, Cochlodinium polykrikoides and their associated bacterial community composition has not been explored. To understand this correlation, changes in bacterial community structure through the evolution of a C. polykrikoides bloom in Korean coastal waters via clone library analysis were investigated. Although there were no apparent changes in physio-chemical factors during the onset of the C. polykrikoides bloom, the abundance of bacteria bourgeoned in parallel with C. polykrikoides densities. Alpha-, gamma-proteobacteria and Flavobacteria were found to be dominant phyletic groups during C. polykrikoides blooms. The proportion of gamma-proteobacteria was lower (11.8%) during peak of the bloom period compared to the post-bloom period (26.2%). In contrast, alpha-proteobacteria increased in dominance during blooms. Among the alpha-proteobacteria, members of Rhodobacterales abruptly increased from 38% of the alpha-proteobacteria before the bloom to 74% and 56% during the early bloom and peak bloom stages, respectively. Moreover, multiple sites concurrently hosting C. polykrikoides blooms also contained high portions of Rhodobacterales and principal component analysis (PCA) demonstrated that Rhodobacterales had a positive, significant correlation with C. polykrikoides abundances (p≤0.01, Pearson correlation coefficients). Collectively, this study reveals the specific clades of bacteria that increase (Rhodobacterales) and decrease (gamma-proteobacteria) in abundance C. polykrikoides during blooms.

Evaluation of rapid cell division in non-uniform cell cycles

To better understand the mechanisms of development of harmful algal blooms (HABs), accurate estimates of species-specific in situ growth rates are needed. HABs are caused by rapid cell division by the causative microorganisms. To accurately estimate the in situ growth rates of harmful algae having non-uniform and/or irregular cell cycles, we modified a standard equation based on the cell cycle, and calculated the in situ growth rate to describe the process of bloom development in nature. Sampling of a developing bloom of Heterosigma akashiwo in Pohang Bay, Korea, was conducted every 3 h from 15:00 on August 2 to 07:00 on August 4, 2006. The amount of H. akashiwo DNA was measured using flow cytometry following tyramide signal amplification-fluorescence in situ hybridization. On August 2, the percentage of G1 phase cells decreased from 15:00 to 19:00 then increased until 22:00; it then decreased until 07:00 on August 3, followed by an increase to 10:00. This indicates the ability of the cells in nature to undergo more than one round of division per day. During the following night two rounds of division did not occur. The in situ growth rates estimated using the modified equation ranged from 0.31 to 0.53 d(-1) . We conclude that the use of this equation enables more accurate estimates of bloom formation by rapidly dividing cells.

Identification of key factors influencing primary productivity in two river-type reservoirs by using principal component regression analysis

To understand the factors controlling algal production in two lakes located on the Han River in South Korea, Lake Cheongpyeong and Lake Paldang, a principal component regression model study was conducted using environmental monitoring and primary productivity data. Although the two lakes were geographically close and located along the same river system, the main factors controlling primary productivity in each lake were different: hydraulic retention time and light conditions predominantly influenced algal productivity in Lake Cheongpyeong, while hydraulic retention time, chlorophyll a-specific productivity, and zooplankton grazing rate were most important in Lake Paldang. This investigation confirmed the utility of principal component regression analysis using environmental monitoring data for predicting complex biological processes such as primary productivity; in addition, the study also increased the understanding of explicit interactions between environmental variables. The findings obtained in this research will be useful for the adaptive management of water reservoirs. The results will also aid in the development of management strategies for water resources, thereby improving total environmental conservation.

Effects of the algicide, thiazolidinedione derivative TD49, on microbial communities in a mesocosm experiment

We investigated the effects of the algicide thiazolidinedione derivative TD49 on microbial community in mesocosm experiments. The TD49 concentration exponentially decreased over time, with half-life of 3.5 h, following addition in the seawater (R2=0.98, P<0.001). Among microbial communities, heterotrophic bacteria and heterotrophic nanoflagellates (HNFs) grew well in all treatments following the addition of TD49. The abundance of HNFs lagged behind the increase in heterotrophic bacteria by 24 h in the 0.2 and 0.4 μM TD49 concentrations (R2=0.28, P<0.05), and by 48 h in the 0.6 and 1.0 μM TD49 concentrations (R2=0.30, P<0.05). This implies a strong concentration-dependent top-down effect of TD49 on microbial communities, with indications that the degradation of planktonic organisms, including the target alga, led to high heterotrophic bacteria concentrations, which in turn stimulated the population growth of predatory HNF. However, total ciliate numbers remained relatively low in the TD49 treatments relative to the control and blank groups, suggesting limited carbon flow from bacteria to these grazers even though the abundance of aloricate ciliates gradually increased toward the end of the experimental period, particularly at the high TD49 concentrations. TD49 appears to provide an environmentally safe approach to the control of harmful algal blooms (HABs) in aquatic ecosystems.

Identification of the resting cyst of Cochlodinium polykrikoides Margalef (Dinophyceae, Gymnodiniales) in Korean coastal sediments

This study provides the first morphological features of resting cysts of Cochlodinium polykrikoides collected from Korean coastal sediments. Evidence for the existence of resting cysts of C. polykrikoides is based on the morphological and molecular phylogenetic data of the germinated cells and a resting cyst. The morphology of the resting cysts differed from that reported previously in sediments and culture experiments. The distinct feature is that the cyst body was covered by the reticulate ornaments and spines.

Intraspecific diversity and distribution of the cosmopolitan species Pseudo-nitzschia pungens (Bacillariophyceae): morphology, genetics, and ecophysiology of the three clades

Three clades of Pseudo-nitzschia pungens, determined by the internal transcribed space (ITS) region, are distributed throughout the world. We studied 15 P. pungens clones from various geographical locations and confirmed the existence of the three clades within P. pungens, based on ITS sequencing and described the three subgroups (IIIaa, IIIab, and IIIb) of clade III. Clade III (clade IIIaa) populations were reported for the first time in Korean coastal waters and the East China Sea. In morphometric analysis, we found the ultrastructural differences in the number of fibulae, striae, and poroids that separate the three clades. We carried out physiological tests on nine clones belonging to the three clades growing under various culture conditions. In temperature tests, only clade III clones could not grow at lower temperatures (10°C and 15°C), although clade I and II clones grew well. The estimated optimal growth range of clade I clones was wider than that of clades II and III. Clade II clones were considered to be adapted to lower temperatures and clade III to higher temperatures. In salinity tests, clade II and III clones did not grow well at a salinity of 40. Clade I clones were regarded as euryhaline and clade II and III clones were stenohaline. This supports the hypothesis that P. pungens clades have different ecophysiological characteristics based on their habitats. Our data show that physiological and morphological features are correlated with genetic intraspecific differentiation in P. pungens.

An outbreak of lymphomas in a layer chicken flock previously infected with fowlpox virus containing integrated reticuloendotheliosis virus

Visceral lymphomas occurred in a 236-day-old layer flock previously diagnosed with reticuloendotheliosis virus (REV)-integrated fowlpox virus (FPV) infection at the age of 77 days. Common pathologic lesions were multiple neoplastic nodules of homogeneous lymphocytes in the livers and spleens of all submitted chickens. All neoplastic tissues were positive for the REV envelope (env) gene by PCR. In a retrospective molecular study of FPV-infected 77-day-old chickens from the same flock, we identified nearly full-length REV provirus integrated into the genome of FPV as well as the REV env gene in trachea samples, whereas only the REV LTR region was present in the FPV strain used to vaccinate this flock. The 622-bp REV env gene nucleotide sequence derived from the trachea and neoplastic tissues was identical. Commercial ELISA of serum samples revealed that all chickens aged between 17 and 263 days in this flock were positive for REV but not for avian leukosis virus. Taken together, the evidence suggests that the visceral lymphomas were caused by a REV-integrated FPV field strain. FPV infections of commercial chickens should be followed up by careful monitoring for manifestations of REV infection, including lymphomas and immune depression, considering the ease with which the REV provirus appears to be able to integrate into the FPV genome.

Molecular survey of enteric viruses in commercial chicken farms in Korea with a history of enteritis

Several enteric viruses have increasingly received attention as potential causative agents of runting-stunting syndrome (RSS) in chickens. A molecular survey was performed to determine the presence of a broad range of enteric viruses, namely chicken astrovirus (CAstV), avian nephritis virus (ANV), chicken parvovirus (ChPV), infectious bronchitis virus (IBV), avian rotavirus (AvRV), avian reovirus (ARV), and fowl adenovirus (FAdV), in intestinal samples derived from 34 commercial chicken flocks that experienced enteritis outbreaks between 2010 and 2012. Using techniques such as PCR and reverse-transcription PCR, enteric viruses were identified in a total of 85.3% of investigated commercial chicken flocks in Korea. Furthermore, diverse combinations of 2 or more enteric viruses were simultaneously identified in 51.7% of chicken farms positive for enteric viruses. The rank order of positivity for enteric viruses was as follows: ANV (44.1%), CAstV (38.2%), ChPV (26.5%), IBV (20.6%), ARV (8.8%), AvRV (5.9%), and FAdV (2.9%). Additionally, other pathogens such as Escherichia coli, Salmonella spp., Eimeria spp., and FAdV were detected in 79% of chicken flocks positive for enteric viruses using PCR, bacterial isolation, and microscopic examination. The results of our study indicate the presence of several enteric viruses with various combinations in commercial chicken farms that experienced enteritis outbreaks. Experimental studies are required to further understand the roles of enteric viruses in RSS in commercial chickens.

Structural characteristics of ternary In(x)Ga(1-x)As nanowires on Si (111) grown via Au-catalyzed VLS

We have characterized the structural properties of the ternary In(x)Ga(1-x)As nanowires (NWs) grown on silicon (Si) substrates using metalorganic chemical vapor deposition (MOCVD). Au catalyzed vapor-liquid-solid (VLS) mode was used for the NW growth. The density of the In(x)Ga(1-x)As NW array grown under optimized condition exceeds 1 x 10(8)/cm2. X-ray diffraction (XRD) spectra confirm the In composition (x = 0.9-0.3) of the In(x)Ga(1-x)As nanowires which bandgap energy can cover the entire near-infrared (NIR) range. Massive stacking faults and twin planes were observed but no misfit dislocation was found along the NWs as confirmed by transmission electron microscopy (TEM). The energy-dispersive X-ray spectroscopy (EDS) analysis shows the gradual variation of In composition along the NW.

DISCRIMINATIVE POWER OF NUCLEAR rDNA SEQUENCES FOR THE DNA TAXONOMY OF THE DINOFLAGELLATE GENUS PERIDINIUM (DINOPHYCEAE)(1)

The genus Peridinium Ehrenb. comprises a group of highly diversified dinoflagellates. Their morphological taxonomy has been established over the last century. Here, we examined relationships within the genus Peridinium, including Peridinium bipes F. Stein sensu lato, based on a molecular phylogeny derived from nuclear rDNA sequences. Extensive rDNA analyses of nine selected Peridinium species showed that intraspecies genetic variation was considerably low, but interspecies genetic divergence was high (>1.5% dissimilarity in the nearly complete 18S sequence; >4.4% in the 28S rDNA D1/D2). The 18S and 28S rDNA Bayesian tree topologies showed that Peridinium species grouped according to their taxonomic positions and certain morphological characters (e.g., epithecal plate formula). Of these groups, the quinquecorne group (plate formula of 3', 2a, 7″) diverged first, followed by the umbonatum group (4', 2a, 7″) and polonicum group (4', 1a, 7″). Peridinium species with a plate formula of 4', 3a, 7″ diverged last. Thus, 18S and 28S rDNA D1/D2 sequences are informative about relationships among Peridinium species. Statistical analyses revealed that the 28S rDNA D1/D2 region had a significantly higher genetic divergence than the 18S rDNA region, suggesting that the former as DNA markers may be more suitable for sequence-based delimitation of Peridinium. The rDNA sequences had sufficient discriminative power to separate P. bipes f. occultaum (Er. Lindem.) M. Lefèvre and P. bipes f. globosum Er. Lindem. into two distinct species, even though these taxa are morphologically only marginally discriminated by spines on antapical plates and the shape of red bodies during the generation of cysts. Our results suggest that 28S rDNA can be used for all Peridinium species to make species-level taxonomic distinctions, allowing improved taxonomic classification of Peridinium.

Artemisia fukudo essential oil attenuates LPS-induced inflammation by suppressing NF-kappaB and MAPK activation in RAW 264.7 macrophages

In the present study, the chemical constituents of Artemisia fukudo essential oil (AFE) were investigated using GC-MS. The major constituents were alpha-thujone (48.28%), beta-thujone (12.69%), camphor (6.95%) and caryophyllene (6.01%). We also examined the effects of AFE on the production of nitric oxide (NO), prostaglandin E(2) (PGE(2)), tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6, in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages. Western blotting and RT-PCR tests indicated that AFE has potent dose-dependent inhibitory effects on pro-inflammatory cytokines and mediators. We investigated the mechanism by which AFE inhibits NO and PGE(2) by examining the level of nuclear factor-kappaB (NF-kappaB) activation within the mitogen-activated protein kinase (MAPK) pathway, which is an inflammation-induced signal pathway in RAW 264.7 cells. AFE inhibited LPS-induced ERK, JNK, and p38 phosphorylation. Furthermore, AFE inhibited the LPS-induced phosphorylation and degradation of Ikappa-B-alpha, which is required for the nuclear translocations of the p50 and p65 NF-kappaB subunits in RAW 264.7 cells. Our results suggest that AFE might exert an anti-inflammatory effect by inhibiting the expression of pro-inflammatory cytokines. Such an effect is mediated by a blocking of NF-kappaB activation which consequently inhibits the generation of inflammatory mediators in RAW264.7 cells. AFE may be useful for treating inflammatory diseases.

Informative characteristics of 12 divergent domains in complete large subunit rDNA sequences from the harmful dinoflagellate genus, Alexandrium (Dinophyceae)

The genus Alexandrium includes organisms of interest, both for the study of dinoflagellate evolution and for their impacts as toxic algae affecting human health and fisheries. Only partial large subunit (LSU) rDNA sequences of Alexandrium and other dinoflagellates are available, although they contain much genetic information. Here, we report complete LSU rDNA sequences from 11 strains of Alexandrium, including Alexandrium affine, Alexandrium catenella, Alexandrium fundyense, Alexandrium minutum, and Alexandrium tamarense, and discuss their segmented domains and structure. Putative LSU rRNA coding regions were recorded to be around 3,400 bp long. Their GC content (about 43.7%) is among the lowest when compared with other organisms. Furthermore, no AT-rich regions were found in Alexandrium LSU rDNA, although a low GC content was recorded within the LSU rDNA. No intron-like sequences were found. The secondary structure of the LSU rDNA and parsimony analyses showed that most variation in LSU rDNA is found in the divergent (D) domains with the D2 region being the most informative. This high D domain variability can allow members of the diverse Alexandrium genus to be categorized at the species level. In addition, phylogenetic analysis of the alveolate group using the complete LSU sequences strongly supported previous findings that the dinoflagellates and apicomplexans form a clade.

Complete sequence and secondary structure of the large subunit ribosomal RNA from the harmful unarmored dinoflagellate Akashiwo sanguinea

This is the first report of the complete DNA sequence of the gene encoding the ribosomal large subunit (LSU rDNA, 3336 bp) from the naked gymnodinioid dinoflagellate Akashiwo sanguinea. No introns were found in the LSU rDNA coding region and secondary structures were predicted for both the LSU and 5.8S rRNAs. The predicted LSU structure showed most of the features seen in the consensus secondary structure model proposed for the eukaryotic nuclear LSU rRNAs. However, six helices (C1_1, C1_2, C1_3, D10, D20_1 and H1_2) are not present in the A. sanguinea LSU structure. Particularly, the C branch area (or D2 domain), was extremely reduced compared to the eukaryotic consensus sequence due to nucleotide deletion. Phylogenetic resolution against 12 divergent (D) domains and cores in LSU rDNA showed that the D1, D2 and D12 domains were highly variable and could be used as genetic markers within low taxonomic levels, particularly in the gymnodinioid complex.

Nuclear rDNA and chloroplast rbcL, rbcS and IGS sequence data, and their implications from the Japanese, Korean, and North American harmful algae, Heterosigma akashiwo (Raphidophyceae)

The toxic Heterosigma akashiwo has been found in coastal environments and its algal blooms have been associated with mass mortality in marine organisms and farmed fish. Over the last two decades, H. akashiwo has expanded its geographical range on a worldwide scale, though all populations are suspected to be a single species. To find strong molecular evidence, supporting this hypothesis we determined nuclear 18S, ITS and LSU rDNA, and chloroplast rbcL, rbcS and flanking IGS sequences from six isolates located in North America, Japan and Korea. We compared individual loci from molecular regions (e.g., 26.7kbp of DNA sequence) and found all the isolates to have an identical genotype. Further, the long sequences allow us to compare all the partial sequences that have been reported from samples obtained in ten countries. All these sequence are nearly identical. This suggests that they have dispersed recently from one location. The sequences revealed here can be used as an additional option for making molecular comparisons of sequences from the same isolate.

Cryptic long internal repeat sequences in the ribosomal DNA ITS1 gene of the dinoflagellate Cochlodinium polykrikoides (dinophyceae): a 101 nucleotide six-repeat track with a palindrome-like structure

Extremely long PCR fragments were generated by PCR amplification of ITS and 5.8S rDNA from Cochlodinium polykrikoides against other dinoflagellates. These patterns were consistent among geographically different isolates of C. polykrikoies. DNA sequencing reactions revealed that the PCR products were 1,166 bp in length and consisted of 813 bp of ITS1, 160 bp of 5.8S rDNA and 193 bp of ITS2. Thus, the long length was caused mainly by the long ITS1 sequence. Cryptically, the ITS1 contained a tract of 101 bp that occurs six times in tandem. The six repeated elements had identical nucleotide sequences. ITS1, therefore, separated three distinct regions: the 5' end (122 bp), the six parallel repeats (606 bp), and the 3' region (85 bp). Interestingly, both the single and six-repeat sequences should be palindrome-like sequences. In inferred secondary structures, both repeat sequences formed a long helical structure. This is the first reported discovery of comparatively long internal repeats in the ITS1 of dinoflagellates.

A low-density oligonucleotide array study for parallel detection of harmful algal species using hybridization of consensus PCR products of LSU rDNA D2 domain

A low-density oligonucleotide array approach based on the hybridization of consensus PCR products of LSU rDNA was developed in order to simultaneously detect various harmful algae. A set of oligonucleotide probes for the hybridization of specific LSU rDNA D2 regions was developed for the identification of 10 representative harmful microalgae. Each probe was spotted onto a streptoavidin-coated glass slide by pipetting. Universal primers were designed within the conserved regions adjacent to the D2 regions of all harmful algae and used to PCR amplify the complete D2 regions. The PCR products were hybridized to the oligonucleotides arrayed on the slide. The array produced unique hybridization patterns for each species of harmful algae and allowed us to differentiate the closely related species. Furthermore, we were able to simultaneously detect several predominant HAB species from a mixture of culture strains and from a natural sample. These results show that DNA microarray can be a new technical platform for parallel discrimination of harmful algae and has great potential to alter the manner in which researchers monitor these microorganisms.

Protein C and/or S deficiency presenting as peripheral arterial insufficiency

Although protein C and/or S deficiency has frequently been associated with venous thromboembolic events, instances of arterial thromboses have been reported. However, the exact incidence of protein C and/or S deficiency in patients with peripheral arterial insufficiency has not been established. Furthermore, given the lack of adequate studies to define the natural history and angiographic findings of these patients, the treatment has not been well delineated. Therefore, we conducted a prospective study to investigate the prevalence, characteristic angiographic findings and optimal treatments in patients with peripheral arterial insufficiency associated with protein C and/or S deficiency. Between September 2000 and August 2004, 133 patients who presented with peripheral arterial insufficiency underwent hypercoagulability tests before the initiation of any treatments. Of these, 11 patients (8.3%) with protein C and/or S deficiency were included in this study. There were nine males and two females. The ages ranged from 38 years to 72 years (mean 57 years). All patients showed characteristic angiographic findings: long segment thrombotic occlusion of a main peripheral artery without evidence of atherosclerosis or with mild atherosclerotic changes in the aorta and other major arterial trees. Surgical or endovascular procedures were performed in nine patients: bypass graft in four, thrombectomy in four and catheter-directed thrombolysis in one. Conservative treatment with full anticoagulation was performed in two patients. All patients received pre- and post-operative anticoagulation. Except for one amputated case, clinical and vascular laboratory improvements were achieved in 10 patients. Mean follow-up period was 21 months (range 4-45 months). However, one patient, in whom re-vascularization surgery was performed successfully, discontinued warfarin therapy himself at 10 months after surgery, graft occlusion and limb loss occurred at 30 months after surgery. This initial experience suggests that protein C and/or S deficiency may be an independent risk factor for peripheral arterial insufficiency. Patients who present with peripheral arterial insufficiency and protein C and/or S deficiency demonstrate characteristic angiographic findings. Once the diagnosis of protein C and/or S deficiency is made, patients should be treated with life-long anticoagulation.

Integrated method for single-cell DNA extraction, PCR amplification, and sequencing of ribosomal DNA from harmful dinoflagellates Cochlodinium polykrikoides and Alexandrium catenella

A simplified technique was developed for DNA sequence-based diagnosis of harmful dinoflagellate species. This protocol integrates procedures for DNA extraction and polymerase chain reaction (PCR) amplification into a single tube. DNA sequencing reactions were performed directly, using unpurified PCR products as the DNA template for subsequent sequencing reactions. PCR reactions using DNA extracted from single cells of Cocodinium polykrikoides and Alexandrium catenella successfully amplified the target ribosomal DNA regions. DNA sequencing of the unpurified PCR products showed that DNA sequences corresponded to the expected locus of ribosomal DNA regions of both A. catenella and C. polykrikoides (each zero genetic distance and 100% sequence similarity). Using the protocol described in this article, there was little DNA loss during the purification step, and the technique was found to be rapid and inexpensive. This protocol clearly resolves the taxonomic ambiguities of closely related algal species (such as Alexandrium and Cochlodinium), and it constitutes a significant breakthrough for the molecular analysis of nonculturable dinoflagellate species.

Cytomegalovirus infection of the graft duodenum and urinary bladder after simultaneous pancreas–kidney transplantation

Cytomegalovirus (CMV) is an important cause of morbidity after solid organ transplantation. We report a case of CMV infection involving the transplanted duodenum that developed after simultaneous pancreas-kidney transplantation. The patient, a 30-year-old woman with insulin-dependent diabetes undergoing hemodialysis due to chronic renal failure, received a simultaneous cadaveric pancreas-kidney transplantation. The exocrine secretion was diverted using bladder drainage. Immunosuppression was maintained by a combination of tacrolimus, mycophenolate mofetil, and steroids together with OKT3 induction. Both the donor and the recipient were serologically positive for CMV IgG CMV prophylaxis consisted of a short course of parenteral gancyclovir. The patient was discharged on postoperative day 39 with normal pancreas and kidney function. She presented 2 months after transplantation with hematuria. Cystoscopic pancreas allograft biopsy specimens showed evidence of tissue invasive CMV infection in the graft duodenum and bladder. The CMV antigenemia test was positive. At 4 months after transplantation, the patient underwent surgery with the diagnosis of acute abdomen. The surgical findings consisted of a diffuse acute purulent peritonitis due to perforation of the duodenal graft. We sutured the perforation with nonreabsorbable material. The CMV antigenemia test was negative. Eight days later, the patient developed massive hematuria. At surgery, the graft was removed. The patient was discharged from the hospital with normal renal function. Pathological study of the removed graft showed the duodenal segment to have multiple wide ulcers with CMV inclusions in epithelial cells.

The origin of cells that repopulate patellar tendons used for reconstructing anterior cruciate ligaments in man

Cryopreserved patellar tendon allografts are often recommended for reconstruction of anterior cruciate ligaments (ACLs) because living donor fibroblasts are thought to promote repair. Animal studies, however, indicate that ligaments regenerate from recipient rather than donor cells. If applicable to man, these observations suggest that allograft cell viability is unimportant. We therefore used short tandem repeat analysis with polymerase chain reaction (PCR) amplification to determine the source of cells in nine human ACLs reconstructed with cryopreserved patellar tendon allografts. PCR amplification of donor and recipient DNA obtained before operation and DNA from the graft obtained two to ten months after transplantation revealed the genotype of cells and showed only recipient cells in the graft area. Rather than preserve the viability of donor cells, a technique is required which will facilitate the introduction of recipient cells into patellar tendon allografts.

Tenelectrodes: a new stimulator for inching technique in the diagnosis of carpal tunnel syndrome

This study was designed to evaluate the usefulness of a new multielectrode stimulator, TenElectrodes, in the diagnosis and localization of the compression site in the wrists of carpal tunnel syndrome (CTS) patients. Antidromic inching technique (IT) of the median nerve at the wrist was performed with the TenElectrodes, on 46 controls and 21 CTS patients. In controls, mean conduction delay per centimeter (CD/cm) was 0.21 milliseconds (ms), and maximal CD/cm was 0.27 ms in the segment 3 to 4 centimeters distal to the distal wrist crease. The abnormal cut-off value, calculated as the maximal CD/cm + 2SD, was 0.45 ms. In the CTS group, the maximal CD/cm was 0.56 ms in the segment 2 to 3 centimeters distal to the distal wrist crease, and the CD/cm values in all segments between the distal wrist crease and 4 cm distal to the distal wrist crease were greater than 0.45 ms. Antidromic IT using TenElectrodes may be an easy, fast and accurate method as the electrodes of the stimulator are aligned at 1-cm intervals and are adjustable to the wrist contour by springs.

Deep venous thrombosis associated with protein C and/or S deficiency: management with catheter-directed thrombolysis

We performed this study to evaluate the efficacy of catheter-directed thrombolysis with urokinase in treating acute symptomatic iliofemoral deep venous thrombosis associated with protein C and/or S deficiency. A total of 42 consecutive patients with deep venous thrombosis were seen between September 2000 and August 2002. Of these, catheter-directed thrombolysis via the popliteal vein was performed in 5 patients (11.9%) with acute iliofemoral deep venous thrombosis associated with protein C and/or S deficiency. Average duration of symptoms was 4.2 days (range, 1-7 days). The average urokinase dose was 2.7 million IU (range, 0.6 million to 7.0 million IU) infused over an average of 33.1 h (range, 16-67 h). Lysis was complete in all five treated cases. Two cases had underlying iliac venous stenoses (>50%) that were treated with angioplasty and stent placement. In one patient in whom recanalization of a right iliac vein occlusion was successful, thrombosis occurred in the treated vein within 3 weeks of intervention despite full anticoagulation therapy, and further intervention was required. There were no complications or clinically detectable pulmonary emboli. The technical and clinical success rates were 100%. This initial experience suggests that catheter-directed thrombolysis for treatment of acute symptomatic iliofemoral deep venous thrombosis associated with protein C and/or S deficiency is safe and effective.

Teratogenic effects of N-ethyl-N-nitrosourea (ENU) on larvae of the self-fertilizing fish Rivulus marmoratus (Cyprinodontiformes, Rivulidae)

We showed that N-Ethyl-N-Nitrosourea (ENU) induces teratogenesis in larvae of the self-fertilizing fish Rivulus marmoratus. We discuss this and the issue of carcinogenesis caused by ENU.

Peripheral arterial insufficiency associated with protein C deficiency

Two patients with protein C deficiency who presented with peripheral arterial insufficiency were successfully managed. One patient was managed with bypass surgery for focal gangrene followed by full anticoagulation whilst the other patient was managed with full anticoagulation. Both patients showed characteristic arteriographic findings. Patients who present with peripheral arterial insufficiency demonstrating thrombotic occlusion of main peripheral artery without atherosclerosis and other risk factors should be evaluated for hypercoagulable states.

Cloning and sequences of beta-actin genes from Rhodeus notatus and the silver carp Hypophthalmichthys molitrix (cyprinidae) and the phylogeny of Cyprinid fishes inferred from beta-actin genes

Complete beta-actin genes from Rhodeus notatus and Hypophthalmichthys molitrix (silver carp) were amplified by polymerase chain reaction and cloned into pCRII vector for further characterization. The beta-actin genes of these two fishes were 1718 and 1755 bp in sequence length, respectively, and both of them contained 5 exons and 4 introns. The exon and intron boundaries were identified with the GT/AG rule. The phylogenetic implications of beta-actin gene in the family Cyprinidae were shortly discussed.

Korean population genetic data for eleven STR loci

Allele frequency and forensic parameters for eleven STR loci were surveyed in a random sample from the Korean population.