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Ciliated protists are ideal material for studying the origin and evolution of sex, because of their nuclear dimorphism (containing both germline micronucleus and somatic macronucleus in the same cytoplasm), special sexual processes (conjugation and autogamy), and high diversity of mating-type systems. However, the study of sexual process is limited to only a few species, due to the difficulties in inducing or observing conjugation. In the present study, we investigate the conjugation process in Paramecium multimicronucleatum: (1) of the three prezygotic divisions, all micronuclei undergo the first two divisions (meiosis I, II), while a variable number of nuclei undergo the third division (mitosis); (2) the synkaryon divides three times after fertilization, giving rise to eight products that differentiate into four macronuclear anlagen and four micronuclei; (3) cells restore the vegetative stage after two successive cell fissions during which the macronuclear anlagen are distributed into daughter cells without division, while micronuclei divide mitotically; (4) the parental macronucleus begins to fragment following the first meiotic division and finally degenerates completely; (5) the entire process takes about 110 h, of which about 85 h are required for macronuclear development. In addition, we describe for the first time the process of genomic exclusion occurring between amicronucleate and micronucleate cells of P. multimicronucleatum, during which the micronucleate cell contributes a pronucleus to the amicronucleate cell, resulting in both exconjugants being homozygotes. These results provide new insights into the diversity of sexual processes and lay an important cytological basis for future in-depth studies of mating systems in ciliates.

The COVID-19 pandemic has had a great impact on the mental health of the medical staff in China, especially those on the first-line (frontline) of the pandemic. But the profile of the mental problem of nationwide Chinese medical staff is still unclear, especially about the sleep problems.There are five databases (PubMed, Embase, CNKI, Wanfang Database and Web of Science) searched to identify the published studies on the mental health of the medical staff in China during the COVID-19 outbreak. The pooled prevalence of mental problems of Chinese medical staff during the pandemic were calculated, especially for the first-line medical staff. Subgroup analysis and meta-regression analysis were performed to identify the potential impact factors.A total of 71 articles including 98,533 participants are included in this meta-analysis. The results showed that the pooled prevalence of the mental problems was as follows: anxiety problem 27%, depression problem 29%, sleep problem 40%. Subgroup analysis showed that there were significant differences in the prevalence of anxiety and depression problems between first-line and non-first-line medical staff (p0.01). Sex had a significant impact on the sleep of first-line medical staff (p0.01).There may be heterogeneity among the included studies. The analysis of potential influencing factors remains limited.The prevalence of adverse mental problems among medical staff is high during the COVID-19 outbreak. We need to pay special attention to the mental health of first-line medical staff, especially the sleep problems of female first-line workers.

A hallmark of working memory (WM) is its limited capacity. While visual and verbal domains of WM are able to store multiple items, the capacity of parametric vibrotactile WM (vtWM) has not yet been established for supra-threshold, one-dimensional sensory vibrotactile frequencies. The present study extends the standard delayed match-to-sample vibrotactile discrimination task to determine the capacity of the vtWM and its cognitive mechanism. Here, by presenting subjects with 2 to 6 vibratory frequencies sequentially in each trial, the present study demonstrates that it is possible to retain about only two vibrotactile frequencies information in vtWM. The results also showed that the capacity of vtWM does not depend on whether sequentially presented vibrotactile frequencies are delivered to the same or to different fingers. At the same time, the rate of correct report depends on sequence length and when in the sequence the stimuli are presented, suggesting the dynamic updating of vtWM similar to that of visual WM.

Previous studies of multiple object tracking suggested that spatiotemporal features (e.g., speed, direction, location) and surface features (e.g., color, shape, size) can guide perceptual grouping. However, it is still unclear how target-distractor distinctiveness and target-background similarity affect grouping effects in attentive tracking. To address these two questions, three experiments have been carried out in the current study. In Experiment 1, we manipulated the target-distractor distinctiveness and found that tracking performance logarithmically improved when the target-distractor distinctiveness linearly increased. In Experiment 2a and 2b, we varied the target-background similarity and found that too high or too low target-background similarity damaged the tracking performance, while only the middle target-background similarity resulted in the best tracking performance. These findings reveal that not only target-distractor distinctiveness but also target-background similarity plays a vital role in guiding the attention of perceptual grouping in attentive tracking. The guidance induced by target-distractor distinctiveness is constrained by the spatial resolution, while the guidance induced by target-background similarity is constrained by the efficiency of object segmentation. Additionally, our results showed that tracking capacity varied with the target-distractor distinctiveness and the target-background similarity, even though the number of targets being tracked was fixed. It suggests that there may be a trade-off between the difficulty of tracking and the number of targets that can be tracked. Thus, tracking capacity is more likely to be limited by the flexible attention resources rather than the number of fixed slots.

Heterotrichous ciliates play an important role in aquatic ecosystem energy flow processes and many are model organisms for research in cytology, regenerative biology, and toxicology. In the present study, we combine both morphological and molecular data to infer phylogenetic relationships at family-genus level and propose new evolutionary hypotheses for the class Heterotrichea. The main results include: (1) 96 new ribosomal DNA sequences from 36 populations, representing eight families and 13 genera, including three poorly annotated genera, Folliculinopsis, Ampullofolliculina and Linostomella; (2) the earliest-branching families are Spirostomidae in single-gene trees and Peritromidae in the concatenated tree, but the family Peritromidae probably represents the basal lineage based on its possession of many "primitive" morphological characters; (3) some findings in molecular trees are not supported by morphological evidence, such as the family Blepharismidae is one of the most recent branches and the relationship between Fabreidae and Folliculinidae is very close; (4) the systematic positions of Condylostomatidae, Climacostomidae, and Gruberiidae remain uncertain based either on morphological or molecular data; and (5) the monophyly of each genus included in the present study is supported by the molecular phylogenetic trees, except for Blepharisma in the SSU rDNA tree and Folliculina in the ITS1-5.8S-ITS2 tree.

Erlotinib is an oral tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR) pathway. Although our previous study has proved the efficacy of Erlotinib in head and neck squamous cell carcinoma (HNSCC), it has also demonstrated poor clinical response rates and disappointing results in clinical trials for HNSCC to date. In this study, we discovered elevated cell proliferation and invasion ability in erlotinib-resistant HNSCC cells. The contributions of miRNAs within extracellular vesicles (EVs) during the formation of chemoresistance were investigated in this study. Among up-regulated miRNAs in EVs derived from resistant cells, miR-7704, miR-21-5p and miR-3960 showed the most pro-tumorigenic alterations after transfection. Conversely, let-7i-5p, miR-619-5p and miR-30e-3p demonstrated tumor suppressive effects. By performing qRT-PCR and Western blot analysis, we found Vimentin played a pivotal role in modulating erlotinib resistance. Additionally, immune system was highlighted in the GO and KEGG analyses. Transfection of miR-7704, miR-21-5p significantly elevated CTLA-4 and LAG3 mRNA levels. Meanwhile, miR-3960 increased the relative mRNA expression of TIM3 in HNSCC cells. Transfection of let-7i-5p, miR-619-5p and miR-30e-3p decreased these checkpoint factors. To conclude, the present study described the roles of EVs-transmitted miRNAs on erlotinib resistance. Targeting the disregulated immune system could be the effective method to overcome erlotinib-resistance in HNSCC cells. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s12079-020-00546-7) contains supplementary material, which is available to authorized users.

Most eukaryotes employ a combination of transcriptional and post-transcriptional silencing mechanisms to suppress transposons, yet ciliates employ a more extreme approach. They separate germline and somatic functions into distinct nuclei, enabling the elimination of transposons from the active somatic genome through diverse small RNA-mediated genome rearrangement pathways during sexual processes.

Two colonial sessilid peritrichs, Epistylis qingdaoensis n. sp. and Carchesium cyclopidarum Nenninger, 1948, were isolated from a marine crustacean and a freshwater mayfly, respectively. Morphological characters for each species were revealed by in vivo observations and silver staining methods. Epistylis qingdaoensis n. sp. is characterized by the apperance of the colony which is up to 250 μm high and usually contains fewer than eight zooids, the single-layered peristomial lip, the conspicuously conical peristomial disc, and the structure of infundibular polykinety 3 which comprises three isometric ciliary rows. Carchesium cyclopidarum is recognized by the colony height of about 600 μm, the small zooid size of 35-50 × 20-30 μm, and the low number of silverlines. Phylogenetic analyses based on small subunit ribosomal DNA sequences were performed to reveal their evolutionary relationships. Surprisingly, neither species clustered with its congeners. Epistylis qingdaoensis n. sp. nested within a clade of Zoothamnium species that was sister to a clade comprising core Epistylis species and several Zoothamnium species. Carchesium cyclopidarum nested within a clade comprising solitary peritrichs and was distantly related to the type species of Carchesium, C. polypinum. These findings imply for the first time that Carchesium is non-monophyletic.

To assess the dental health of orphan and non-orphan children in Fuyang City, China.A total of 332 orphan children were selected from social child welfare institutes and 590 non-orphan children were selected from the Experimental Primary and Middle Schools through random sampling in Fuyang City, China. The indices for Decayed, Missing, Filling (DMF) in orphan and non-orphan children were determined by dental inspections to assess their dental health. The periodontal status of orphan and non-orphan children aged 12-15 years was determined using the percentages of bleeding gingiva and dental calculus.In the age range of 3 to 5 years, the percentage of caries (81%) and the mean DMF (4.41; SD: 2.06; 95% CI: 3.82 to 5.00) of orphan children were statistically significantly higher than the percentage of caries (64%) and the mean DMF of the non-orphan control cohort (3.29; SD: 2.05; 95% CI: 2.87 to 3.71; p0.05). In the age range of 12 to 15 years, the percentage of caries (50.8%) and the mean DMF (1.28; SD: 1.26; 95% CI: 1.12 to 1.43) of orphan children were statistically significantly higher than the percentage of caries (34.5%) and the mean DMF (1.11; SD: 1.24; 95% CI: 1.01 to 1.23; p0.05) of non-orphan children. For orphan children ages 3 to 5 years, the percentage of restorations was statistically significantly lower (p0.05) than that of non-orphan children (30%). For orphan children ages 12 to 15 years, the percentage of restorations was 3.9%, statistically significantly lower (p0.05) than that of non-orphan children (19.4%). In orphan children ages 12 to 15 years, the percentages of bleeding gingiva (76.0%) and dental calculus (69.3%) were statistically significantly higher (p0.05) than those of the non-orphan children (46.2% and 39.1%, respectively). There was no statistically significant difference in the evaluation indicators above between different genders within the groups studied, except the percentage of restorations.The dental health of orphan children in Fuyang City is worse than that of non-orphan children of the same age ranges. The values determined in this study can be used as a starting metric to measure the effectiveness of dental health care programs in improving the dental health of both orphan and non-orphan children.

Semaphorin 3A (Sema3A) has been recognized as a crucial regulator of morphogenesis and homeostasis over a wide range of organ systems. However, its function in cutaneous wound healing is poorly understood. In our study, we demonstrated that Sema3A adenovirus plasmids transfection limited keratinocyte proliferation and decreased migrative capacity as assessed by in vitro wound healing assay. Sema3A transduction inhibited TGF-β1-mediated keratinocyte migration and EMT process. Besides, we applied mice with K14-Cre-mediated deletion of Sema3A and found that Sema3A depletion postponed wound closure with decreased re-epithelialization and matrix growth. Contrary to the results obtained with full-length Sema3A plasmids transfection, increased keratinocyte migration with recombinant Sema3A proteins resulted in quicker closure of the wounding area after a scratch. Further, exogenously applied recombinant Sema3A worked with EGF to maintain the activation of EGFR by interacting with NRP1 and thereby regulated the internalization of the EGFR-NRP1 complex. Taken together, these results indicated a paradoxical role of autonomous and non-autonomous Sema3A expression during wound healing. Combined administration of recombinant EGF and Sema3A proteins could accelerate the process of wound repair, thus providing promising treatment prospects in the future.

Sequence-based approaches, such as analyses of ribosome DNA (rDNA) clone libraries and high-throughput amplicon sequencing, have been used extensively to infer evolutionary relationships and elucidate the biodiversity in microbial communities. However, recent studies demonstrate both rDNA copy number variation and intra-individual (intra-genomic) sequence variation in many organisms, which challenges the application of the rDNA-based surveys. In ciliates, an ecologically important clade of microbial eukaryotes, rDNA copy number and sequence variation are rarely studied. In the present study, we estimate the intraindividual small subunit rDNA (SSU rDNA) copy number and sequence variation in a wide range of taxa covering nine classes and 18 orders of the phylum Ciliophora. Our studies reveal that: (i) intra-individual sequence variation of SSU rDNA is ubiquitous in all groups of ciliates detected and the polymorphic level varies among taxa; (ii) there is a most common version of SSU rDNA sequence in each cell that is highly predominant and may represent the germline micronuclear template; (iii) compared with the most common version, other variant sequences differ in only 1-3 nucleotides, likely generated during macronuclear (somatic) amplification; (iv) the intra-cell sequence variation is unlikely to impact phylogenetic analyses; (v) the rDNA copy number in ciliates is highly variable, ranging from 103 to 106, with the highest record in Stentor roeselii. Overall, these analyses indicate the need for careful consideration of SSU rDNA variation in analyses of the role of ciliates in ecosystems.

In animal germlines, transposons are silenced at the transcriptional or post-transcriptional level to prevent deleterious expression. Ciliates employ a more direct approach by physically eliminating transposons from their soma, utilizing piRNAs to recognize transposons and imprecisely excise them. Ancient, mutated transposons often do not require piRNAs and are precisely eliminated. Here, we characterize the Polycomb Repressive Complex 2 (PRC2) in Paramecium and demonstrate its involvement in the removal of transposons and transposon-derived DNA. Our results reveal a striking difference between the elimination of new and ancient transposons at the chromatin level and show that the complex may be guided by Piwi-bound small RNAs (sRNAs). We propose that imprecise elimination in ciliates originates from an ancient transposon silencing mechanism, much like in plants and metazoans, through sRNAs, repressive methylation marks, and heterochromatin formation. However, it is taken a step further by eliminating DNA as an extreme form of transposon silencing.

A hallmark of working memory (WM) is its limited capacity. While visual and verbal domains of WM are able to store multiple items, the capacity of parametric vibrotactile WM (vtWM) has not yet been established for supra-threshold, one-dimensional sensory vibrotactile frequencies. The present study extends the standard delayed match-to-sample vibrotactile discrimination task to determine the capacity of the vtWM and its cognitive mechanism. Here, by presenting subjects with 2 to 6 vibratory frequencies sequentially in each trial, the present study demonstrates that it is possible to retain about only two vibrotactile frequencies information in vtWM. The results also showed that the capacity of vtWM does not depend on whether sequentially presented vibrotactile frequencies are delivered to the same or to different fingers. At the same time, the rate of correct report depends on sequence length and when in the sequence the stimuli are presented, suggesting the dynamic updating of vtWM similar to that of visual WM.

Determination and comparisons of complete mitochondrial genomes (mitogenomes) are important to understand the origin and evolution of mitochondria. Mitogenomes of unicellular protists are particularly informative in this regard because they are gene-rich and display high structural diversity. Ciliates are a highly diverse assemblage of protists and their mitogenomes (linear structure with high A+T content in general) were amongst the first from protists to be characterized and have provided important insights into mitogenome evolution. Here, we report novel mitogenome sequences from three representatives (Strombidium sp., Strombidium cf. sulcatum, and Halteria grandinella) in two dominant ciliate lineages. Comparative and phylogenetic analyses of newly sequenced and previously published ciliate mitogenomes were performed and revealed a number of important insights. We found that the mitogenomes of these three species are linear molecules capped with telomeric repeats that differ greatly among known species. The genomes studied here are highly syntenic, but larger in size and more gene-rich than those of other groups. They also all share an AT-rich tandem repeat region which may serve as the replication origin and modulate initiation of bidirectional transcription. More generally we identified a split version of ccmf, a cytochrome c maturation-related gene that might be a derived character uniting taxa in the subclasses Hypotrichia and Euplotia. Finally, our mitogenome comparisons and phylogenetic analyses support to reclassify Halteria grandinella from the subclass Oligotrichia to the subclass Hypotrichia. These results add to the growing literature on the unique features of ciliate mitogenomes, shedding light on the diversity and evolution of their linear molecular architecture.

To investigate parental acceptance of the use of general anesthesia with mask inhalation (GAMI) in the treatment of ankyloglossia.Parents of children with ankyloglossia received questionnaires to analyze the related factors of their acceptance of GAMI.From July 2017 to November 2020, 131 parents of children with ankyloglossia in our hospital were enrolled and received investigation questionnaires. A total of 129 valid questionnaires were returned. The level of acceptance was evaluated using the visual analogue scale (VAS). We described the parental acceptance in a statistical method and performed univariant and multivariate analyses to identify related factors using SPSS 20.0.A total of 129 (98.5%) parents completed the questionnaires. Only one patient (0.8%) experienced short-term (4 hours) abdominal bloating after surgery with GAMI. The average VAS regarding parental acceptance of the use of GAMI in the treatment was 43.80 mm (± 29.49), with only 17.8% of parents exhibiting a high level of acceptance of the anesthesia technique, while they had a relatively high level of satisfaction after surgery.Parents had a low level of acceptance of using GAMI in the treatment of ankyloglossia before surgery due to various factors.

How to achieve protein diversity by genome and transcriptome processing is essential for organismal complexity and adaptation. The present work identifies that the macronuclear genome of Halteria grandinella, a cosmopolitan unicellular eukaryote, is composed almost entirely of gene-sized nanochromosomes with extremely short nongenic regions., How to achieve protein diversity by genome and transcriptome processing is essential for organismal complexity and adaptation. The present work identifies that the macronuclear genome of Halteria grandinella, a cosmopolitan unicellular eukaryote, is composed almost entirely of gene-sized nanochromosomes with extremely short nongenic regions. This challenges our usual understanding of chromosomal structure and suggests the possibility of novel mechvanisms in transcriptional regulation. Comprehensive analysis of multiple data sets reveals that Halteria transcription dynamics are influenced by: (i) nonuniform nanochromosome copy numbers correlated with gene-expression level; (ii) dynamic alterations at both the DNA and RNA levels, including alternative internal eliminated sequence (IES) deletions during macronucleus formation and large-scale alternative splicing in transcript maturation; and (iii) extremely short 5′ and 3′ untranslated regions (UTRs) and universal TATA box-like motifs in the compact 5′ subtelomeric regions of most chromosomes. This study broadens the view of ciliate biology and the evolution of unicellular eukaryotes, and identifies Halteria as one of the most compact known eukaryotic genomes, indicating that complex cell structure does not require complex gene architecture.

Previous studies on perceptual grouping found that people can use spatiotemporal and featural information to group spatially separated rigid objects into a unit while tracking moving objects. However, few studies have tested the role of objects' self-motion information in perceptual grouping, although it is of great significance to the motion perception in the three-dimensional space. In natural environments, objects always move in translation and rotation at the same time. The self-rotation of the objects seriously destroys objects' rigidity and topology, creates conflicting movement signals and results in crowding effects. Thus, this study sought to examine the specific role played by self-rotation information on grouping spatially separated non-rigid objects through a modified multiple object tracking (MOT) paradigm with self-rotating objects. Experiment 1 found that people could use self-rotation information to group spatially separated non-rigid objects, even though this information was deleterious for attentive tracking and irrelevant to the task requirements, and people seemed to use it strategically rather than automatically. Experiment 2 provided stronger evidence that this grouping advantage did come from the self-rotation per se rather than surface-level cues arising from self-rotation (e.g. similar 2D motion signals and common shapes). Experiment 3 changed the stimuli to more natural 3D cubes to strengthen the impression of self-rotation and again found that self-rotation improved grouping. Finally, Experiment 4 demonstrated that grouping by self-rotation and grouping by changing shape were statistically comparable but additive, suggesting that they were two different sources of the object information. Thus, grouping by self-rotation mainly benefited from the perceptual differences in motion flow fields rather than in deformation. Overall, this study is the first attempt to identify self-motion as a new feature that people can use to group objects in dynamic scenes and shed light on debates about what entities/units we group and what kinds of information about a target we process while tracking objects.

The class Oligohymenophorea is one of the most diverse assemblage of ciliated protists, which are particularly important in fundamental biological studies including understanding the evolutionary relationships among the lineages. Phylogenetic relationships within the class remain largely elusive, especially within the subclass Peniculia, which contains the long-standing problematic taxa Urocentrum and Paranassula. In the present study, we sequenced the genomes and/or transcriptomes of six non-culturable oligohymenophoreans using single-cell sequencing techniques. Phylogenomic analysis was performed based on expanded taxon sampling of 85 taxa, including 157 nuclear genes encoding 36,953 amino acids. The results indicate that: (1) urocentrids form an independent branch that is sister to the clade formed by Scuticociliatia and Hymenostomatia, which, together with the morphological data, supports the establishment of a new subclass, Urocentria n. subcl., within Oligohymenophorea; (2) phylogenomic analysis and ortholog comparison reveal a close relationship between Paranassula and peniculines, providing corroborative evidence for removing Paranassula from Nassulida and elevating it as an order, Paranassulida, within the subclass Peniculia; (3) based on the phylogenomic analyses and morphological data, we hypothesize that Peritrichia is the earliest diverging clade within Oligohymenophorea while Scuticociliatia and Hymenostomatia share the most common ancestor, followed successively by Urocentria and Peniculia. In addition, stop codon analyses indicate that oligohymenophoreans widely use UGA as the stop codon, while UAR are reassigned to glutamate (peritrichs) or glutamine (others), supporting the evolutionary hypothesis.

Our group previously identified that the NOTCH1 Abruptex domain contains the most mutations in Chinese OSCC patients, including a hotspot mutation (C1133Y). FBXW7 is an E3 ubiquitin ligase that regulates a network of proteins, including NOTCH1, via degradation. In this study, we first described the co-localization of isoform specific FBXW7-FBXW7β and NOTCH1C1133Y mutation in the same cytoplasmic sites. Gain- and loss-of-function assays were performed to examine the tumor suppressor role of FBXW7β in the proliferation and invasion of OSCC cells. The co-expression of NOTCH1C1133Y and FBXW7β significantly attenuated tumor growth. Meanwhile, FBXW7β reversed the oncogenic phenotype and the activation of the AKT/ERK/NFκB pathway induced by NOTCH1C1133Y mutation. FBXW7β downregulated the stability of NOTCH1C1133Y protein and promoted protein ubiquitination. This was the first time that we selected a NOTCH1 hotspot mutation detected in clinical samples and identified the function of FBXW7β that mediated NOTCH1 mutation degradation in OSCC. The newly identified interaction between FBXW7β and NOTCH1C1133Y protein provides new insights into the progression of OSCC, especially regarding Abruptex domain mutations, and represents a valuable target for OSCC therapy.

Previous studies have identified that both CKLF-like MARVEL transmembrane domain-containing member (CMTM6) and Neuropilin-1 (NRP1) played an essential part in regulating tumorigenesis and immune response. However, the potential connection between CMTM6 and NRP1 in oral squamous cell carcinoma (OSCC) remains unknown. In this study, we investigated the clinicopathologic significance of CMTM6 and NRP1 in OSCC. We examined the co-expression of CMTM6 and NRP1 in both OSCC tissues and cell lines. Co-overexpression of CMTM6 and NRP1 was generally highly expressed in cancer tissues and is associated with poor prognosis. Gain- and loss-of-function assays confirmed the oncogenic properties of CMTM6 in OSCC cells. Depletion of NRP1 abrogated tumorigenesis induced by CMTM6. By performing co-immunoprecipitation (co-IP), we discovered a potential interaction between CMTM6 and NRP1. Meanwhile, the stability of CMTM6 was significantly decreased in the NRP1-silencing cells, indicating the involvement of NRP1 in the degradation process of CMTM6. The crosstalk between CMTM6 and NRP1 provided a new insight into the progression of OSCC, which may indicate an alternative strategy for OSCC treatment.

This document contains supplementary methods, 6 supplementary figures, and 2 supplementary tables.

Surface features can be used during multiple object tracking (MOT). Previous studies suggested that surface features might be stored in visual working memory to assist object tracking, and attentive tracking and visual working memory share common attentional resources. However, it is still unknown whether features of both the target and distractor sets will be stored, or features of the target and distractor sets are processed differently. Moreover, how feature distinctiveness and similarity between the target and distractor sets affect tracking and allocation of attentional resources are still not clear. First, we manipulated the colour complexity of the target set (CT) and the colour complexity of the distractor set (CD), respectively, in two experiments, where colours of the target and distractor sets were always distinct, to test their effects on tracking performance. If features of the target and distractor sets are stored, manipulating feature complexity of the target and distractor sets would significantly affect tracking performance. Second, this study tested whether tracking performance was affected by different levels of distinctiveness between the target and distractor sets (DTD) and explored how distinctiveness affected tracking and allocation of attentional resources. Results showed that DTD and CT significantly affect tracking performance and allocation of attentional resources, but not CD. These results indicated that when targets and distractors have distinct features, only the surface features of the targets are maintained in visual working memory. And when targets have the same colour with the distractors, they are more difficult and consume more attentional resources to track.

Our vision systems utilize attention to process dynamic visual information everyday. Multiple object tracking (MOT) is widely used for studying sustained attention in dynamic environments. Previous research reported inter-target grouping based on feature similarity (e.g., targets sharing the same color, size, or shape) can facilitate tracking. A recent study also found that symmetric relation among targets in MOT tasks can automatically improve tracking performance, and a greater grouping effect based on symmetry and feature was observed. However, grouping based on multiple feature cues didn't produce a greater grouping effect than grouping based on one feature cue. Why were groupings based on symmetry and feature additive, but two feature-based groupings were not? How stimulus-driven inter-target groupings based on color or symmetry improve the goal-directed target tracking process remains unknown. We hypothesized that symmetry-based and feature-based groupings would involve different cortical and subcortical areas, and color-based and color-shape-based groupings would be manifested in significant activity in the same regions. This study used functional magnetic resonance imaging (fMRI) to identify cortical and subcortical areas involved in feature-based and symmetry-based groupings respectively during tracking. The results of our experiment showed that lateral occipital (LO) cortex is involved in symmetry-based grouping during tracking. Bilateral putamen, temporal parietal junction (TPJ), and frontal eye field (FEF) are involved in the feature-based grouping. Our findings likely indicate that stimulus-driven inter-target symmetry-based grouping and feature-based grouping improve goal-directed target tracking in different ways.

Acute hepatopancreatic necrosis disease (AHPND) has caused a severe decline of global shrimp production and economic losses. One of the causative agents for AHPND is Vibrio parahaemolyticus (VpAHPND), bearing toxin genes pirABvp. In this study, potential probiotic bacteria CDM8 and CDA22, isolated from the hindgut of healthy Penaeus vannamei, were rod-shaped and motile with a single polar flagellum, and they can form yellow colonies, produce oxidase and hydrolyze gelatin. The possibility of their application against VpAHPND was evaluated. Both strains were found to display antagonistic activity against VpAHPND, which could be inhibited by catalase, and they were identified as Pseudoalteromonas spp. based on phylogenetic analysis. These two bacteria produced extracellular antibacterial compounds, according to the disc diffusion assay. Furthermore, CDM8 or CDA22 as a feed additive could (i) significantly decrease the presumptive Vibrio counts in the hindgut of shrimp (P. vannamei) after being fed for 21 days, compared to that in shrimp fed with the mixture of CDM8 and CDA22 and the commercial feed, and (ii) strikingly reduce the cumulative mortality (vs the control group: 36.7% or 76.7% vs 96.7%) of shrimp when challenged with VpAHPND. In addition, they could decrease copy numbers of pirAvp gene in shrimp, according to the quantitative PCR results. However, there is no synergistic relationship between CDM8 and CDA22 when used together as feed additives. All these results suggested that bacteria CDM8 and CDA22 were anti-VpAHPND probiotic candidates and potential biological control agents against AHPND in shrimp aquaculture.

Some of the most extreme genome wide rearrangements are found in ciliates, which are unique in possessing both germline micronucleus and somatic macronucleus in every cell/organism. A series of DNA rearrangement events, including DNA elimination, chromosomal fragmentation, gene unscrambling and alternative processing, happen during macronuclear development. To assess the molecular evolution of macronuclear and germline-limited sequences in different cryptic species of Chilodonella uncinata, we characterized the actin, α-tubulin and β-tubulin genes in the micronucleus and macronucleus genomes of USA-SC2 strain and compared them with other strains (i.e. cryptic species). Three main results are: (i) rearrangement patterns between germline and soma are conserved for each gene among the cryptic species of C. uncinata; (ii) in contrast, the germline-limited regions are highly divergent in sequence and length among the cryptic species; (iii) pointer shifting is frequent among the cryptic species. We speculate that pointer sequences may serve as the buffer between the conserved macronuclear destined sequences and rapidly-evolving internal eliminated sequences. The data combined with previous studies demonstrate the plasticity of gene rearrangement among different groups of ciliates and add to the growing data for the role of genome rearrangements in species differentiation.

The morphology and infraciliature of two Frontonia species, F. shii spec. nov. and F. paramagna Chen et al., 2014, isolated from a freshwater pond in northeastern China, were investigated using living observation and silver staining methods Frontonia shii spec. nov. is recognized by the combination of the following characters: freshwater Frontonia, size in vivo about 220–350 × 130–250 μm, elliptical in outline; 128–142 somatic kineties; three or four vestibular kineties, six or seven postoral kineties; peniculi 1–3 each with four kineties; single contractile vacuole with about 10 collecting canals. The improved diagnosis for F. paramagna is based on the current and previous reports. Comparisons among freshwater Frontonia are also provided. The small subunit ribosomal rRNA gene (SSU rDNA) sequences of the two species are characterized and phylogenetic analyses based on these sequences show that both species fall into the core clade of the genus Frontonia, and this genus is not monophyletic.

Ciliated protists are a large group of single-celled eukaryotes with separate germline and somatic nuclei in each cell. The somatic genome is developed from the zygotic nucleus through a series of chromosomal rearrangements, including fragmentation, DNA elimination, de novo telomere addition, and DNA amplification. This unique feature makes them perfect models for research in genome biology and evolution. However, genomic research of ciliates has been limited to a few species, owing to problems with DNA contamination and obstacles in cultivation. Here, we introduce a method combining telomere-primer PCR amplification and high-throughput sequencing, which can reduce DNA contamination and obtain genomic data efficiently. Based on this method, we report a draft somatic genome of a multimacronuclear ciliate, Uroleptopsis citrina. 1) The telomeric sequence in U. citrina is confirmed to be C4A4C4A4C4 by directly blunt-end cloning. 2) Genomic analysis of the resulting chromosomes shows a “one-gene one-chromosome” pattern, with a small number of multiple-gene chromosomes. 3) Amino acid usage is analyzed, and reassignment of stop codons is confirmed. 4) Chromosomal analysis shows an obvious asymmetrical GC skew and high bias between A and T in the subtelomeric regions of the sense-strand, with the detection of an 11-bp high AT motif region in the 3′ subtelomeric region. 5) The subtelomeric sequence also has an obvious 40 nt strand oscillation of nucleotide ratio. 6) In the 5′ subtelomeric region of the coding strand, the distribution of potential TATA-box regions is illustrated, which accumulate between 30 and 50 nt. This work provides a valuable reference for genomic research and furthers our understanding of the dynamic nature of unicellular eukaryotic genomes.

We recently established a new species, Homalogastra binucleata, with a morphological description and phylogenetic analyses based on SSU rRNA gene sequence data (Liu et al., 2020). Helmut Berger (Salzburg, Austria) commented that Homalogastra binucleata Liu et al., 2020 is a junior primary homonym of H. binucleata Song, 1993, the latter having been transferred to the genus Uronemita by Liu et al. (2016). According to article 57.2 of the ICZN (1999), the junior primary homonym, Homalogastra binucleata Liu et al., 2020, is permanently invalid. It is replaced by Homalogastra similis nom. nov.

Two oxytrichid ciliates, Stylonychia (Metastylonychia) nodulinucleata Shi and Li, 1993 and Gastrostyla steinii Engelmann, 1862; collected from Huguangyan Maar Lake and Shenzhen Mangrove Nature Protection Area, southern China, respectively, were investigated using standard methods. The uncommon species Stylonychia (Metastylonychia) nodulinucleata can be recognized by its large body size, the conspicuous caudal cirri in vivo, and a moniliform macronucleus. We provide the first record of the small subunit ribosomal RNA (SSU rRNA) gene sequence for the species. The division of Stylonychia into two subgenera based on morphological and morphogenetic data is supported by the phylogenetic analyses, in which Stylonychia (Metastylonychia) nodulinucleata is placed as a sister branch to the clade including all the sequences of Stylonychia (Stylonychia) mytilus complex. The first brackish water population of Gastrostyla steinii is described in detail, with emphasis on its morphogenesis, which corresponds well with previous populations. In the phylogenetic trees, all the available Gastrostyla sequences, except for Gastrostyla sp. Y2 (KT780432) (probably a misidentification), nest together in the big group of the subfamily Stylonychinae with moderate to high support (ML/BI, 91%/0.95), very likely revealing the monophyly of the genus Gastrostyla.

Most ciliate phylogenetic analyses have largely relied on the nuclear small subunit ribosome DNA (nSSU-rDNA) locus. However, single locus or multi-loci from the same genome or chromosome may not be sufficient enough to elucidate phylogenetic relationships among ciliate taxa. Therefore, in addition to nSSU-rDNA, the mitochondrial small subunit ribosome DNA (mtSSU-rDNA) was applied in this study. We expanded the taxon sampling especially within the class Phyllopharyngea. Phylogenetic analyses based on nSSU-rDNA and mtSSU-rDNA, independently, as well as concatenated were performed and revealed the following: (1) mtSSU-rDNA is more variable than nSSU-rDNA, and is better at elucidating relationships at lower levels, e.g. intra-/inter-specific or generic relationships; (2) the validity of the two genera Mirodysteria and Spirodysteria is challenged based on their similar morphology with Dysteria and the analyses from both mtSSU-rDNA and nSSU-rDNA; (3) Brooklynella is confirmed to be an intermediate taxon between Dysteriidae and Hartmannulidae, and may represent a distinct family; (4) Trithigmostoma should remain in Chilodonellidae; (5) the separation of Paraspathidium from Litostomatea is supported and it groups with prostomateans and plagiopyleans. In summary, results from mtSSU-rDNA corroborated those of nSSU-rDNA for highly supported clades, and the mtSSU-rDNA tree with its secondary structure gave topologies that could be explained by the morphology; therefore it can be useful in some cases towards better resolution of robust phylogenies.

The morphology and infraciliature of one freshwater ciliate, Cyclidium sinicum spec. nov., isolated from a farmland pond in Harbin, northeastern China, was investigated using living observation and silver staining methods. Cyclidium sinicum spec. nov. could be distinguished by the following features: body approximately 20–25×10–15 µm in vivo; buccal field about 45–50 % of body length; 11 somatic kineties; somatic kinety n terminating sub-caudally; two macronuclei and one micronucleus; M1 almost as long as M2; M2 triangle-shaped. The genus Cyclidium is re-defined as follows: body outline usually oval or elliptical, ventral side concave, dorsal side convex; single caudal cilium; contractile vacuole posterior terminal; adoral membranelles usually not separated; paroral membrane ‘L’-shaped, with anterior end terminating at the level of anterior end of M1; somatic kineties longitudinally arranged and continuous. Phylogenetic trees based on the SSU rDNA sequences showed that C. sinicum spec. nov. clusters with the type species, Cyclidium glaucoma, with full support. Cyclidium is not monophyletic with members of the clade of Cyclidium+Protocyclidium+Ancistrum+Boveria.

The Cel6A deficiency has become one of the limiting factors for cellulose saccharification in biochemical conversion of cellulosic biomass to fuels and chemicals. The work attempted to use codon optimization to enhance Trichoderma reesei Cel6A expression in Pichia pastoris. Two recombinants P. pastoris GS115 containing AOX1 and GAP promotors were successfully constructed, respectively. The optimal temperatures and pHs of the expressed Cel6A from two recombinants were consistent with each other, were also in the extremely similar range to that reported on the native Cel6A from T. reesei. Based on the shake flask fermentation, AOX1 promotor enabled the recombinant to produce 265U/L and 300mg/L of the Cel6A enzyme, and the GAP promotor resulted in 145U/L and 200mg/L. High cell density fed batch (HCDFB) fermentation significantly improved the enzyme titer (1100U/L) and protein yield (2.0g/L) for the recombinant with AOX1 promotor. Results have showed that the AOX1 promotor is more suitable than the GAP for the Cel6A expression in P. pastoris. And the HCDFB cultivation is a favorable way to express the Cel6A highly in the methanol inducible yeast.