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  1. Fulltext Sexual reproduction and genetic polymorphism within the cosmopolitan marine diatom Pseudo-nitzschia pungens
    Kim JH, Ajani P, Murray SA, Kim JH, Lim HC, Teng ST, et al.
    Sci Rep, 2020 06 30;10(1):10653.
    PMID: 32606343 DOI: 10.1038/s41598-020-67547-9
    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.
  2. Abiotic and biotic factors controlling sexual reproduction in populations of Pseudo-nitzschia pungens (Bacillariophyceae)
    Kim JH, Ajani PA, Murray SA, Kang SM, Kim SH, Lim HC, et al.
    Harmful Algae, 2023 Mar;123:102392.
    PMID: 36894213 DOI: 10.1016/j.hal.2023.102392
    Pseudo-nitzschia pungens is a widely distributed marine pennate diatom. Hybrid zones, regions in which two different genotypes may interbreed, are important areas for speciation and ecology, and have been reported across the globe for this species. However, sexual reproduction between differing clades in the natural environment is yet to be observed and is difficult to predict. Here we carried out experiments using two mono-clonal cultures of P. pungens from different genotypes to measure the frequency and timing of sexual reproduction across varying biotic (growth phases and cell activity potential) and abiotic conditions (nutrients, light, turbulence). We found the mating rates and number of zygotes gradually decreased from exponential to late stationary growth phases. The maximum zygote abundance observed was 1,390 cells mL-1 and the maximum mating rate was 7.1%, both which occurred during the exponential growth phase. Conversely, only 9 cells mL-1 and a maximum mating rate of 0.1% was observed during the late stationary phase. We also found the higher the relative potential cell activity (rPCA) in parent cells, as determined by the concentration of chlorophyll a per cell and the ratio of colony formation during parent cultivations, revealed higher mating rates. Furthermore, sexual events were reduced under nutrient enrichment conditions, and mating pairs and zygotes were not formed under aphotic (dark) or shaking culture conditions (150 rpm). In order to understand the sexual reproduction of Pseudo-nitzschia in the natural environment, our results highlight that it is most likely the combination of both biotic (growth phase, Chl. a content) and abiotic factors (nutrients, light, turbulence) that will determine the successful union of intraspecific populations of P. pungens in any given region.
  3. Feasibility of psychological screening in a tertiary epilepsy clinic
    Lim KS, Wong KY, Chee YC, Fong SL, Yu X, Ng CG, et al.
    Epilepsy Behav, 2023 Nov;148:109455.
    PMID: 37774547 DOI: 10.1016/j.yebeh.2023.109455
    OBJECTIVE: People with epilepsy (PWE) have a high prevalence of developing depression and anxiety. The objective is to determine the feasibility of brief screening tools to screen for depression and anxiety in epilepsy, and the predictive factors.

    METHOD: This is a cross-sectional study in the neurology clinic in a tertiary teaching hospital in Kuala Lumpur. The screening tools used were the Neurological Disorders Depression Inventory for Epilepsy (NDDI-E) and the General Anxiety Disorder Form (GAD-7).

    RESULTS: Five hundred and eighty-five patients were recruited in this study, and 50.8% of them were male, predominantly Chinese (46.7%), with a mean age of seizure onset of 21.8 ± 16.1 years. The majority had focal seizures (75.0%), and 41.9% had seizure remission. There were 15.5% who scored ≥15 in the NDDI-E, and 17.0% had moderate or severe anxiety (scored ≥10 in the GAD-7). In a regression model to predict the NDDI-E score, the age of seizure onset recorded a higher beta value (β = -0.265, p =

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