Symposium Report: International Symposium on Ciliate Biology,India Habitat Centre,New Delhi,India, 04–06 April 2018

Ciliated protists have attracted wide interest among researchers from the Indian subcontinent in the last few years. An International Symposium on Ciliate Biology (ISCB) 2018 was held on 04–06 April 2018 at the India Habitat Centre, New Delhi, India. The symposium represented a synergy with International Research Coordination Network for Biodiversity of Ciliates (IRCN‐BC), an affiliate society of International Society of Protistologists (ISOP). The symposium provided a platform for Indian and International delegates to exchange knowledge, present their latest research findings, and establish collaborations as well as creating a networking opportunity for undergraduate and postgraduate students. Nine foreign delegates from 5 countries and 300 Indian delegates actively participated in the event which included 22 oral and 57 poster presentations.     

Anti‐helminth‐induced changes in the prevalence of entodiniomorphid ciliates in semi‐captive chimpanzees

Ciliates are some of the most abundant gut fauna in wild chimpanzees. However, their presence in captive populations is usually low presumably due to anti‐helmintic prophylaxis or feeding on low fibre diet. We studied a semi‐captive colony of chimpanzees at the Sweetwaters Sanctuary in Kenya subject to routine prophylactic dose of albendazole to clear chimpanzees of parasitic helminths. Fresh faecal samples from known individuals were collected before and subsequently after prophylaxis. The samples were fixed in 10% formalin and examined by the sedimentation method. Troglodytella abrassarti had 42.5% prevalence whereas other ciliates had 65% prevalence. The prevalence of the T. abrassarti and other ciliates significantly declined immediately after prophylaxis and then rose slowly thereafter. Our results suggest that ciliates are susceptible to anti‐helmintic prophylaxis and that treatment may eliminate ciliates or inhibit their proliferation within the host subsequently lowering their prevalence in the population. Variation in prevalence was not influenced by the age of the host. However, a steady recovery of ciliate prevalence was lower for male compared to female hosts. Our results imply that the intervals between prophylactic regimes could be prolonged differently for males and females to increase the prevalence of ciliates in captive populations.     

Evidence for longitudinal migration by a “sedentary” Brazilian flycatcher,the Ash‐throated Casiornis

The digitalization of museum collections and concurrent increase in citizen‐science initiatives is ushering in an era of unprecedented availability of primary biodiversity data. These changes permit a reappraisal of phenological patterns of tropical species. I examined spatio‐temporal variation in the distribution patterns of an ostensibly sedentary endemic Brazilian flycatcher, the Ash‐throated Casiornis (Casiornis fuscus), using both specimen data from museums and sighting records and rich media data from citizen‐science initiatives. I found compelling evidence for partial intratropical longitudinal migration to Amazonia and the Cerrado biomes from the species’ core range in the semi‐desert Caatinga biome and adjacent ecotones. These records from outside of the Caatinga were distributed during the height of the dry season from April to October, although the Caatinga is not entirely vacated at this time. This pattern of partial migration leads to a doubling of the distributional range of Ash‐throated Casiornises and strongly suggests that the species is a breeding near‐endemic of the Caatinga biome. This pattern was potentially previously not apparent because of significant biases in specimen collection between biomes, giving a false sense of abundance in the Brazilian Amazon.     

Exploration of Genetic Variations through Single‐cell Whole‐genome Sequencing in the Model Ciliate Tetrahymena thermophila

Ciliates are unicellular eukaryotes with separate germline and somatic genomes and diverse life cycles, which make them a unique model to improve our understanding of population genetics through the detection of genetic variations. However, traditional sequencing methods cannot be directly applied to ciliates because the majority are uncultivated. Single‐cell whole‐genome sequencing (WGS) is a powerful tool for studying genetic variation in microbes, but no studies have been performed in ciliates. We compared the use of single‐cell WGS and bulk DNA WGS to detect genetic variation, specifically single nucleotide polymorphisms (SNPs), in the model ciliate Tetrahymena thermophila. Our analyses showed that (i) single‐cell WGS has excellent performance regarding mapping rate and genome coverage but lower sequencing uniformity compared with bulk DNA WGS due to amplification bias (which was reproducible); (ii) false‐positive SNP sites detected by single‐cell WGS tend to occur in genomic regions with particularly high sequencing depth and high rate of C:G to T:A base changes; (iii) SNPs detected in three or more cells should be reliable (an detection efficiency of 83.4–97.4% was obtained for combined data from three cells). This analytical method could be adapted to measure genetic variation in other ciliates and broaden research into ciliate population genetics.     

Agroforestry coffee soils increase the insect‐suppressive potential offered by entomopathogenic fungi over full‐sun soils: A case proposing a “bait survival technique”

Entomopathogenic fungi are important natural enemies of insects. However, there is little information on the insect‐suppressive potential of these fungi and possible effects of farming management on this. Meanwhile, changes in natural landscapes due to agricultural intensification have caused considerable biodiversity loss and consequent decay of ecosystem services. However, the adoption of practices such as agroforestry in agroecosystems can foster abiotic and biotic conditions that conserve biodiversity, consequently restoring the provision of ecosystems services. Here, we assessed the effect of management systems (agroforestry or full‐sun) on the pest‐suppressive potential of entomopathogenic fungi in Brazilian coffee plantations. We used the insect bait method coupled with survival analyses to assess the speed of kill by entomopathogenic fungi and their presence in soil samples from both farming systems. We found that insects exposed to agroforestry soils died more quickly than insects exposed to full‐sun soils. Of the fungi isolated from the bait insects, Metarhizium was found most frequently, followed by Beauveria. Meanwhile, Fusarium was frequently isolated as primary or secondary infections. We propose that the differential survival of insects is indicative of a greater suppressive potential by entomopathogenic fungi in agroforestry, and that this could be promoted by the diversified landscape, microclimatic stability, and reduced soil disturbance in agroforestry systems. Furthermore, our results provide a useful demonstration of the potential use of the insect bait method to investigate pest‐suppressive potential through bait insect mortality, and we term this the “bait survival technique.”     

Symposium on “Symbiosis in Protozoa”: Introductory Remarks1,2

ABSTRACT. Attention, perhaps overdue, is drawn to the extent and significance of endosymbionts (xenosomes sensu lato) in the cytoplasm and nuclei of many protozoa from diverse taxonomic groups. Even more importantly, recent advances in the study of such intimate associations are reviewed and discussed and their impact on broader problems of cell biology and evolution are stressed. Workers inside and especially outside the fields of protozoology and parasitology have often neglected such data, failing to appreciate their relevance to significant problems in their own fields of investigation. The major topics covered by speakers in the Symposium (to which this paper serves only as an introduction) include the following, in order of their presentation: terminology for the symbiont-host relationship and a brief overview of the field; the evolutionary problem of the origin of contemporary associations, including cell organelles such as mitochondria and plastids; the adaptive value of endosymbionts to their protozoan hosts; mechanisms of establishment, maintenance, and integration of such foreign bodies/invaders in their unicellular eukaryotic host cells; and the extent of algal and bacterial endosymbioses in diverse protozoan groups. In all papers, the principal relatively well studied complexes used as examples are the following: various kinds of algae in the larger foraminifera and in ciliates, radiolarians, and acantharians; the several types of bacteria in the cytoplasm of Amoeba and of Pelomyxa; the endonuclear bacterial symbionts of Paramecium; the cytoplasmic prokaryotes in Paramecium and in Parauronema; and the methanogenic bacteria of certain ciliates.     

Insights on the concept of indicator populations derived from parentage‐based tagging in a large‐scale coho salmon application in British Columbia,Canada

For Pacific salmon, the key fisheries management goal in British Columbia (BC) is to maintain and restore healthy and diverse Pacific salmon populations, making conservation of salmon biodiversity the highest priority for resource management decision‐making. Salmon status assessments are often conducted on coded‐wire‐tagged subsets of indicator populations based on assumptions of little differentiation within or among proximal populations. In the current study of southern BC coho salmon (Oncorhynchus kisutch) populations, parentage‐based tagging (PBT) analysis provided novel information on migration and life‐history patterns to test the assumptions of biological homogeneity over limited (generally < 100 km) geographic distances and, potentially, to inform management of fisheries and hatchery broodstocks. Heterogeneity for location and timing of fishery captures, family productivity, and exploitation rate was observed over small geographic scales, within regions that are, or might be expected to be, within the area encompassed by a single‐tagged indicator population. These results provide little support for the suggestion that information gained from tagged indicator populations is representative of marine distribution, productivity, and exploitation patterns of proximal populations.     

Protozoan epibionts on Mysis relicta Loven, 1862 (Crustacea, Mysidacea) from Lake Lüšiai (Lithuania)

Protozoan epibionts were found on specimens of the mysid Mysis relicta collected in Lake Lü?iai (Lithuania). These protozoans belong to three genera of ciliates: Vorticella, Dendrosoma and Tokophrya, and were located on the antennae, carapace, appendages and abdomen of the basibiont. The ciliates of the genus Vorticella had a bell‐shaped body, with concave‐type striations and a very long contractile stalk. The stalk joined the body via a truncated and overlapping zone. The macronucleus was J‐shaped, and the contractile vacuole was anterolateral. Only one ciliate species of Vorticella has been found on mysids, although on species other than M. relicta, and this is therefore the first record of Vorticella on M. relicta, and the second on the order Mysidacea. The ciliates of the genus Dendrosoma had an irregular body directly attached to the substrate. Finger‐like actinophores arose from the body, with a bundle of tentacles at their ends. The macronucleus ramified into branches that followed the actinophores. These ciliates were included in the species D. astaci. The presence of this ciliate represents the first record of this genus on Mysis relicta. The ciliates of the genus Tokophrya had a pyramidal body, the apical surface of which showed two conspicuous actinophores, with a short, longitudinally striated stalk joining to the body via a narrow unstriated band. The macronucleus was spherical or ovoid, centrally located, and there was an apical contractile vacuole. Only one previous study has referred to the presence of this genus on Mysis relicta, and the data contained in it were compared with those of the present study. The biometrical data and taxonomical position of the ciliate epibionts was considered.     

Downscaling land‐use data to provide global 30″ estimates of five land‐use classes

Land‐use change is one of the biggest threats to biodiversity globally. The effects of land use on biodiversity manifest primarily at local scales which are not captured by the coarse spatial grain of current global land‐use mapping. Assessments of land‐use impacts on biodiversity across large spatial extents require data at a similar spatial grain to the ecological processes they are assessing. Here, we develop a method for statistically downscaling mapped land‐use data that combines generalized additive modeling and constrained optimization. This method was applied to the 0.5° Land‐use Harmonization data for the year 2005 to produce global 30″ (approx. 1 km²) estimates of five land‐use classes: primary habitat, secondary habitat, cropland, pasture, and urban. The original dataset was partitioned into 61 bio‐realms (unique combinations of biome and biogeographical realm) and downscaled using relationships with fine‐grained climate, land cover, landform, and anthropogenic influence layers. The downscaled land‐use data were validated using the PREDICTS database and the geoWiki global cropland dataset. Application of the new method to all 61 bio‐realms produced global fine‐grained layers from the 2005 time step of the Land‐use Harmonization dataset. Coarse‐scaled proportions of land use estimated from these data compared well with those estimated in the original datasets (mean R²: 0.68 ± 0.19). Validation with the PREDICTS database showed the new downscaled land‐use layers improved discrimination of all five classes at PREDICTS sites (P < 0.0001 in all cases). Additional validation of the downscaled cropping layer with the geoWiki layer showed an R² improvement of 0.12 compared with the Land‐use Harmonization data. The downscaling method presented here produced the first global land‐use dataset at a spatial grain relevant to ecological processes that drive changes in biodiversity over space and time. Integrating these data with biodiversity measures will enable the reporting of land‐use impacts on biodiversity at a finer resolution than previously possible. Furthermore, the general method presented here could be useful to others wishing to downscale similarly constrained coarse‐resolution data for other environmental variables.     

Exotic ladybirds for biological control of herbivorous insects – a review

Since the late 19th century, exotic ladybirds (Coleoptera: Coccinellidae) have been used extensively for suppressing herbivorous insects of economic importance. In recent decades, the introduction of non‐native biological control (BC) agents has been greatly limited due to the awareness of the potential non‐target effects of introductions. Nonetheless, recent episodes of biological invasions of economically important pests have raised the need to carefully consider whether the expected benefits of pest control go beyond the possible environmental risks of introduction. To better understand the factors that contributed to successful BC programs, here we review the literature behind classical and augmentative BC using exotic ladybirds. Additionally, by means of case studies, we discuss the BC efficacy of selected exotic species, e.g., Coccinella septempunctata L., Harmonia axyridis (Pallas), and Hippodamia variegata (Goeze), and their position within the communities of predators in the introduced areas of USA, Canada, and Chile. In Europe, much of the research on exotic ladybirds has been conducted on the undesired impact of H. axyridis. Therefore, we summarize the risk assessment data for this species and review the field research investigating the ecological impact on European aphidophagous predators. According to the BIOCAT database of classical BC programs, 212 ladybird species belonging to 68 genera have been released in about 130 years of BC activity, with 14.6% of introductions having resulted in partial, substantial, or complete control of the target pest. However, because post‐release evaluation of establishment and BC success has not always been conducted, this rate could underestimate the successful cases. Among other factors, ladybird establishment and pest suppression mostly depend on (1) intrinsic factors, i.e., high voracity, synchronized predator‐prey life cycle, and high dispersal ability, and (2) extrinsic factors, i.e., adaptability to the new environment and landscape composition. This review contributes to improved understanding of ladybirds as exotic BC agents.     

Predicting the consequences of species loss using size‐structured biodiversity approaches

Understanding the consequences of species loss in complex ecological communities is one of the great challenges in current biodiversity research. For a long time, this topic has been addressed by traditional biodiversity experiments. Most of these approaches treat species as trait‐free, taxonomic units characterizing communities only by species number without accounting for species traits. However, extinctions do not occur at random as there is a clear correlation between extinction risk and species traits. In this review, we assume that large species will be most threatened by extinction and use novel allometric and size‐spectrum concepts that include body mass as a primary species trait at the levels of populations and individuals, respectively, to re‐assess three classic debates on the relationships between biodiversity and (i) food‐web structural complexity, (ii) community dynamic stability, and (iii) ecosystem functioning. Contrasting current expectations, size‐structured approaches suggest that the loss of large species, that typically exploit most resource species, may lead to future food webs that are less interwoven and more structured by chains of interactions and compartments. The disruption of natural body‐mass distributions maintaining food‐web stability may trigger avalanches of secondary extinctions and strong trophic cascades with expected knock‐on effects on the functionality of the ecosystems. Therefore, we argue that it is crucial to take into account body size as a species trait when analysing the consequences of biodiversity loss for natural ecosystems. Applying size‐structured approaches provides an integrative ecological concept that enables a better understanding of each species' unique role across communities and the causes and consequences of biodiversity loss.     

Amylosucrase‐mediated β‐carotene encapsulation in amylose microparticles

The β‐carotene embedded amylose microparticles (BC‐AmMPs) were prepared in one‐step by utilizing the unique catalytic activity of amylosucrase from Deinococcus geothermalis (DgAS), which synthesizes linear amylose chains using sucrose as the sole substrate. Synthesized amylose chains self‐assembled with β‐carotene to form well‐defined spherical microparticles with an encapsulation yield of 65%. The BC‐AmMPs produced (average diameter ～8 µm) were bright orange due to the embedded β‐carotene, and this was confirmed by Raman analysis. XRD showed BC‐AmMPs had a B‐type amylose crystal structure with a degree of crystallinity lower than that of AmMPs. This lower crystallinity of AmMP after BC encapsulation was confirmed by DSC analysis. Decreased enthalpy of gelatinization (ΔH_gel) of BC‐AmMP implied that molecular order within the amylose microstructure was influenced by the presence of BC. The stability of BC against environmental stresses, such as UV light and oxidative stress, was significantly enhanced by its encapsulation. The authors propose a new approach to the preparation of an amylose based carrier system for active compounds or expensive food ingredients with poor stabilities during storage or processing. Given that amylose is a safe food material, the devised encapsulation system will find wide range of practical applications in the food industry. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1640–1646, 2017     

Role of mitogen‐activated protein kinase in Zn‐BC‐AM PDT‐induced apoptosis in nasopharyngeal carcinoma cells

Photodynamic therapy (PDT) with a recently developed photosensitizer Zn‐BC‐AM was found to effectively induce apoptosis in a well‐differentiated nasopharyngeal carcinoma (NPC) HK‐1 cell line. Sustained activation of p38 mitogen‐activated protein kinase (MAPK) and c‐jun N‐terminal kinase (JNK) as well as a transient increase in activation of extracellular signal‐regulated kinase (ERK) were observed immediately after Zn‐BC‐AM PDT. A commonly used p38 MAPK/JNK pharmacological inhibitor PD169316 was found to reduce PDT‐induced apoptosis of HK‐1 cells. PD169316 also prevented the loss of Bcl‐2 and Bcl‐xL in PDT‐treated HK‐1 cells. However, inhibition of JNK with SP600125 had no effect on Zn‐BC‐AM PDT‐induced apoptosis while inhibition of ERK with PD98059 or p38 MAPK with SB203580 significantly increased Zn‐BC‐AM PDT‐induced apoptosis. Further study showed that knockdown of the p38β isoform with siRNA also increased Zn‐BC‐AM PDT‐induced apoptosis, indicating that the anti‐apoptotic effect of PD169316 in PDT‐treated HK‐1 cells was probably independent of p38 MAPK or JNK activation. Taken together, the results suggest that inhibition of p38β and ERK may enhance the therapeutic efficacy of Zn‐BC‐AM PDT on NPC cells. It should be noted that data only based on the use of PD169316 should be interpreted in caution. Copyright © 2010 John Wiley & Sons, Ltd.     

Genomic insight into “sky island” species diversification in a mountainous biodiversity hotspot

“Sky island” species diversification contributes greatly to mountainous biodiversity. However, the underlying genomic divergence and the inferred drivers remain largely unknown. In this study, we examined the diversification history of five diploid species with three exclusively endemic to the sky islands (mountains) of the Himalaya–Hengduan Mountains biodiversity hotspot. All of them together comprise a clade of the genus Eutrema (Brassicaceae). We resequenced genomes of multiple individuals of the found populations for each species. We recovered the inconsistent phylogenetic relationships between plastome and nuclear‐genome trees for one species. Based on nuclear population genomic data, we detected high genetic divergence between five species with limited gene flow. Four species seemed to diverge mainly through geographical isolation, whereas one arose through hybrid origin. The origins of the sampled five species were dated to within the late Miocene when mountains were uplifted and climates oscillated. All species decreased their population sizes since the inferred origin of each species initially, but only two of them expanded after the Last Glacial Maximum. Together, these findings suggest that geographic isolation plays an important role in driving the sky island species diversification of the sampled species in addition to the occasional gene flow that might have led to the hybrid origin of some sky island species, similar to the species diversification of sea islands.     

The “<Emphasis Type="Italic">Tetrahymena pyriformis</Emphasis>” complex of cryptic species

Cryptic species are common among protists and have long been known in ciliates. The ciliate genus Tetrahymena contains a large group of morphologically indistinguishable species referred to as the ‘T. pyriformis’ complex. These species include those reproductively isolated by mating type as well as asexual species characterized by the absence of the germinal micronucleus. This paper examines the molecular diversity of the species and describes the biogeography of ‘T. pyriformis’ species. Most species are globally distributed, though the best studied species, T. thermophila, is confined to North America and gives evidence of population structure in local populations. Selfers and asexual species are common and arise from sexual species, a possible exploitation of nuclear dimorphism. It is argued that the cryptic species likely have different ecological roles and that the biodiversity of Tetrahymena in particular, and ciliates in general, is underestimated. Special Issue: Protist diversity and geographic distribution. Guest editor: W. Foissner.     

Conventional land‐use intensification reduces species richness and increases production: A global meta‐analysis

Most current research on land‐use intensification addresses its potential to either threaten biodiversity or to boost agricultural production. However, little is known about the simultaneous effects of intensification on biodiversity and yield. To determine the responses of species richness and yield to conventional intensification, we conducted a global meta‐analysis synthesizing 115 studies which collected data for both variables at the same locations. We extracted 449 cases that cover a variety of areas used for agricultural (crops, fodder) and silvicultural (wood) production. We found that, across all production systems and species groups, conventional intensification is successful in increasing yield (grand mean + 20.3%), but it also results in a loss of species richness (?8.9%). However, analysis of sub‐groups revealed inconsistent results. For example, small intensification steps within low intensity systems did not affect yield or species richness. Within high‐intensity systems species losses were non‐significant but yield gains were substantial (+15.2%). Conventional intensification within medium intensity systems revealed the highest yield increase (+84.9%) and showed the largest loss in species richness (?22.9%). Production systems differed in their magnitude of richness response, with insignificant changes in silvicultural systems and substantial losses in crop systems (?21.2%). In addition, this meta‐analysis identifies a lack of studies that collect robust biodiversity (i.e. beyond species richness) and yield data at the same sites and that provide quantitative information on land‐use intensity. Our findings suggest that, in many cases, conventional land‐use intensification drives a trade‐off between species richness and production. However, species richness losses were often not significantly different from zero, suggesting even conventional intensification can result in yield increases without coming at the expense of biodiversity loss. These results should guide future research to close existing research gaps and to understand the circumstances required to achieve such win‐win or win‐no‐harm situations in conventional agriculture.     

The changes in the predatory behavior of the microturbellarian <Emphasis Type="Italic">Stenostomum sphagnetorum</Emphasis> on two species of toxin-secreting ciliates of the genus <Emphasis Type="Italic">Spirostomum</Emphasis>

It is known that the microturbellarian Stenostomum sphagnetorum, a common ciliate predator, is very sensitive against different types of toxins produced by other ciliates for chemical defense, and consequently, it is not able to capture and ingests these ciliates. In particular, when the predator tries to attack one of these toxin-secreting ciliates, it is forced to regurgitate the captured prey in response to the toxin discharged from the ciliates. In this study it is shown that after repeated attacks by S. sphagnetorum against two species of toxic ciliates (Spirostomum ambiguum and Spirostomum teres), the predator acquires a behavior of prey selection that leads to the exclusion of these ciliates among the possible prey and to the distinction between edible and inedible (toxic) ciliates. This learned behavior, which is maintained for days, is lost only after the asexual reproduction of the microturbellarian. In addition, S. sphagnetorum learns to recognize and avoid specimens of S. ambiguum and S. teres artificially deprived of their toxins, strongly suggesting that the toxins are not exclusively associated in the prey recognition of the microturbellarian.