Behavioural and morphological changes in ciliates induced by the predator Amoeba proteus

The predator Amoeba proteus induced behavioural and morphological changes in ciliates of the genus Euplotes. The frequency of avoidance behaviour in E. octocarinatus increased from 16±5% to 84±5% (SD) after 14 h of coexistence with the predator. The ciliate's width increased from 59±3 μm to 77±4 μm (SDM) within 48 h. Similar behavioural, but not morphological, change was induced in E. daidaleos, but neither morphological nor behavioural responses occurred in E. aediculatus. E. octocarinatus and E. daidaleos populations survived in the presence of A. proteus, whereas E. aediculatus populations became extinct by predation. Induced behavioural response seemed to be the reason for the low predation risk of E. octocarinatus and E. daidaleos. The results suggest that Euplotes ciliates have evolved specific defence mechanisms to various predators. Defensive changes are induced by a chemical substance released from A. proteus. This “kairomone” has a molecular weight between 5000 and 10000 Da. Proteolytic digestion of its activity indicated that the avoidance-inducing substance is a peptide. After the turbellarian Stenostomum sphagnetorum had induced a defensive morphology in E. octocarinatus or E. aediculatus, neither of these ciliates immediately avoided Amoeba proteus. Thus, Euplotes ciliates with a defensive morphology do not have behavioural defences in reaction to all predators.     

Connection between stop codon reassignment and frequent use of shifty stop frameshifting

Ciliated protozoa of the genus Euplotes have undergone genetic code reassignment, redefining the termination codon UGA to encode cysteine. In addition, Euplotes spp. genes very frequently employ shifty stop frameshifting. Both of these phenomena involve noncanonical events at a termination codon, suggesting they might have a common cause. We recently demonstrated that Euplotes octocarinatus peptide release factor eRF1 ignores UGA termination codons while continuing to recognize UAA and UAG. Here we show that both the Tetrahymena thermophila and E. octocarinatus eRF1 factors allow efficient frameshifting at all three termination codons, suggesting that UGA redefinition also impaired UAA/UAG recognition. Mutations of the Euplotes factor restoring a phylogenetically conserved motif in eRF1 (TASNIKS) reduced programmed frameshifting at all three termination codons. Mutation of another conserved residue, Cys124, strongly reduces frameshifting at UGA while actually increasing frameshifting at UAA/UAG. We will discuss these results in light of recent biochemical characterization of these mutations.     

Induction of defensive morphological changes in ciliates

Freshwater ciliates of the genusEuplotes change their morphology in response to the presence of predators. The morphological transformations limit the ability of the predators to ingest the ciliates. Induction of defensive morphology by the predatorsStenostomum sphagnetorum (Turbellaria),Lembadion bullinum (Ciliata),L. magnum, andAmoeba proteus (Rhizopoda) was studied inEuplotes aediculatus andE. octocarinatus. The results suggest the possibility of natural occurrence of predator-induced defensive morphology inEuplotes. A density of 1 predator ml⁻¹ was sufficient to induce significant changes in the morphology ofEuplotes. L. magnum was found at natural population densities of 5 individuals ml⁻¹. Transformations can take place within 2–4 h. Morphological changes are induced by signal substances released from the predators; direct contact between prey and predators is not necessary. The extent of transformation depends on the concentration of the signal substance. The size frequency distribution of the populations only had one peak that was related to predator density. All individuals of a population ofEuplotes changed their morphology according to the predator abundance. This may reduce energy costs for the prey by prevention of unnecessary morphological changes.Amoeba proteus induces morphological changes inE. octocarinatus, but not inE. aediculatus.     

Reciprocal phenotypic plasticity in a predator–prey system: inducible offences against inducible defences?

We describe one of the first examples of reciprocal phenotypic plasticity in a predator–prey system: the interaction between an inducible defence and an inducible offence. When confronted with the predatory ciliate Lembadion bullinum, the hypotrichous ciliate Euplotes octocarinatus develops protective lateral wings, which inhibit ingestion by the predator. We show that L. bullinum reacts to this inducible defence by expressing an inducible offence – a plastic increase in cell size and gape size. This counteraction reduced the effect of the defence, but did not completely neutralize it. Therefore, the defence remained beneficial for E. octocarinatus. From L. bullinum's point of view, the increase in feeding rate because of the offence was not larger than the increase in mean cell volume and apparently, did not increase the predator's fitness. Therefore, the inducible offence of L. bullinum does not seem to be an effective counter‐adaptation to the inducible defence of E. octocarinatus.     

Predation risk of typical ovoid and ‘winged’ morphs of Euplotes (Protozoa,Ciliophora)

Freshwater species of the genus Euplotes (Protozoa, Ciliophora) change their morphology in the presence of some of their predators. The ciliates develop extended lateral wings as well as dorsal and ventral projections which make engulfment by predators more difficult. In a series of laboratory experiments ingestion rates of four protozoan predators, the ciliates Lembadion bullinum, Dileptus anser, Stylonychia mytilus and Urostyla grandis, and one metazoan predator, the turbellarian Stenostomum sphagnetorum, on three species of Euplotes (E. octocarinatus, E. patella and E. aediculatus) were determined. It was calculated that the probability of rejection by a predator changed from 1:1 for ovoid morphs of Euplotes to about 2:1–20:1 for winged morphs of Euplotes, dependent on the prey and predator species that were combined. The nutritional condition of the prey also had some influence. In mixed-species cultures of prey and predators, transformed cells of E. octocarinatus survived for several months.     

“Candidatus Euplotechlamydia quinta,” a novel chlamydia-like bacterium hosted by the ciliate Euplotes octocarinatus (Ciliophora,Spirotrichea)

Our knowledge of ciliate endosymbiont diversity greatly expanded over the past decades due to the development of characterization methods for uncultivable bacteria. Chlamydia-like bacteria have been described as symbionts of free-living amoebae and other phylogenetically diverse eukaryotic hosts. In the present work, a systematic survey of the bacterial diversity associated with the ciliate Euplotes octocarinatus strain Zam5b-1 was performed, using metagenomic screening as well as classical full-cycle rRNA approach, and a novel chlamydial symbiont was characterized. The metagenomic screening revealed 16S rRNA gene sequences from Polynucleobacter necessarius, three previously reported accessory symbionts, and a novel chlamydia-like bacterium. Following the full-cycle rRNA approach, we obtained the full-length 16S rRNA gene sequence of this chlamydia-like bacterium and developed probes for diagnostic fluorescence in situ hybridizations. The phylogenetic analysis of the 16S rRNA gene sequences unambiguously places the new bacterium in the family Rhabdochlamydiaceae. This is the first report of chlamydia-like bacterium being found in Euplotes. Based on the obtained data, the bacterium is proposed as a new candidate genus and species: “Candidatus Euplotechlamydia quinta.”     

Amblyceps waikhomi,a New Species of Catfish (Siluriformes: Amblycipitidae) from the Brahmaputra Drainage of Arunachal Pradesh,India

Amblyceps waikhomi sp. nov. is described from the Nongkon stream which drains into the Noa Dehing River, a tributary of the Brahmaputra River, in Arunachal Pradesh, India. The new species can be distinguished from congeners (except A. torrentis) in having a deeper body depth at anus. It further differs from congeners (except A. mangois and A. serratum) in having fewer vertebrae, from A. mangois in lacking (vs. having) strongly-developed projections on the proximal lepidotrichia of the median caudal-fin rays, and in having a longer, wider, and deeper head; and from A. serratum in having a posteriorly smooth (vs. with 4–5 serrations) pectoral spine, and unequal jaw length (lower jaw longer and weakly-projecting anteriorly vs. equal upper and lower jaws). It additionally differs from A. murraystuarti, A. torrentis, A. apangi, A. laticeps, and A. cerinum in having a deeply forked (vs. emarginate or truncate) caudal fin. This species is the seventh amblycipitid species known to occur in the Ganga-Brahmaputra River system.     

Chemical ecology and insect conservation: optimising pheromone-based monitoring of the threatened saproxylic click beetle Elater ferrugineus

Elater ferrugineus is a saproxylic click beetle inhabiting old deciduous trees in Europe. It is threatened throughout its area of distribution due to habitat loss. No efficient monitoring method has been available for this species, but observed attraction of females to (R)-(+)-γ-decalactone, which is a male-produced sex pheromone of its prey, the scarab beetle Osmoderma eremita, has led to the development of an odour lure for monitoring. In addition, four esters have recently been identified from the pheromone-producing gland in female E. ferrugineus, and a blend of these esters is highly attractive to conspecific males in the field, revealing an alternative odour-based method for monitoring this species. However, no rigorous analysis has been performed to check whether all four esters show biological activity in male E. ferrugineus, and whether its own sex pheromone is a more potent lure than the prey kairomone for monitoring of E. ferrugineus. In this study, we reinvestigated the E. ferrugineus sex pheromone, using electrophysiological and behavioural analyses, and found that only one of the esters, 7-methyloctyl (Z)-4-decenoate, is active. In addition, trapping experiments revealed that 7-methyloctyl (Z)-4-decenoate is a much more efficient attractant for male E. ferrugineus than the prey pheromone is for conspecific females, or any sex of O. eremita. With a very efficient odour lure at hand, novel information about current distribution, local population sizes, and dispersal ranges in E. ferrugineus can now be obtained, which can aid in conservation efforts to protect this threatened insect and its habitat.     

Carriage of antibiotic-resistant bacteria in urban versus rural wild boars

The Western European population of wild boar (Sus scrofa) has increased its distribution over the past several decades, and some populations have colonized areas strongly influenced by human activity. Wild boars are known carriers of antibiotic-resistant bacteria acquired from the environment, and urban populations of wild boars may be more exposed than their rural counterparts. In this work, we compared the frequency of antibiotic resistance in indicator bacteria (Escherichia coli, Enterococcus faecalis, Enterococcus faecium) isolated from urban wild boars with that from rural wild boars in NE Spain. We further assessed whether bacterial isolates from the urban wild boars had a higher probability of showing antibiotic resistance when their host was highly associated to urban features. Seventy-two and 100 bacterial isolates from urban and rural habitat, respectively, were screened for antibiotic resistance against a set of antibiotics (13 per bacterial species). We found a significantly higher frequency of E. faecium showing resistance to tetracycline (70.0% vs 36.4%) and high-level resistance to streptomycin (30.0% vs 4.5%) in urban wild boars compared to rural wild boars (p?<?0.05). E. faecalis was more frequently resistant to trimethoprim in urban than rural wild boars (33.3% vs 0.0%, p?<?0.05). In isolates from urban origin, 55.6% of the likelihood of detecting antibiotic resistance depended only on the bacterial species, being more likely in the enterococci than in E. coli. These results suggest that urban wild boars may be more exposed to certain antibiotic-resistant bacteria or antibiotic resistance genes that they may acquire from the urban environment, although implications are uncertain.     

Taxonomy and distribution of selected species of the agarophyte genus Gelidium (Gelidiales,Rhodophyta)

Although the diverse uses of Gelidium as food and in the production of agar and paper pulp have increased research interest in this genus, the taxonomy and biogeography of several species of Gelidium remain largely unstudied. We conducted phylogenetic analyses of mitochondrial cox1 and plastid rbcL sequences of selected species of Gelidium. The data revealed that Gelidium allanii, Gelidium johnstonii, and Gelidium koshikianum, species that share a similar morphology, formed a monophyletic clade with a wide distribution around the Pacific rim. Because G. johnstonii Setchell & Gardner has nomenclatural priority over G. allanii V.J. Chapman and G. koshikianum Shimada et al., we synonymize the latter two species with the former. Based on the extremely low genetic divergences (0.0–0.2 % for rbcL and 0.0–0.4 % for cox1) between Korean and Mexican specimens of G. johnstonii and its sister relationship with Asian species, we consider that G. johnstonii may have been recently dispersed by anthropogenic agents. The New Zealand endemic Gelidium longipes and Gelidium crinale from Australia were compared with both rbcL and cox1, and were found to be identical. Although the transfer of G. logipes to G. crinale is necessary, the Australasian group within G. crinale is separated from other populations of the species, and we therefore recognize it as a subspecies. Biogeography of Gelidium on the basis of rbcL phylogeny of the 59 Gelidium species is briefly discussed.     

Adaptation of inducible defense in Euplotes daidaleos (Ciliophora) to predation risks by various predators

The extent of induced morphological defense in Euplotes daidaleos correlates to this ciliate's predation risk from the defense-inducing predator species. Euplotes daidaleos responded by morphological transformation only to organisms that are able to feed on typically formed Euplotes cells (63 ± 5 m cell width in E. daidaleos). Three of those potential predator species caused defensive changes to various degrees (Student's t-test, P < 0.1 to P < 0.0001): Lembadion bullinum (Ciliata) induced 82 ± 6 m cell width in E. daidaleos; Chaetogaster diastrophus (Oligochaeta) induced 85 = 6 m width; and Stenostomum sphagnetorum (Turbellaria) induced 89 ± 8 m width (at a density of 10 predators per milliliter, respectively). At higher predator densities (50 or 100 organisms per milliliter), Euplotes developed a correspondingly larger width (to a maximum of 103 ± 10 m in the presence of S. sphagnetorum). Euplotes did not respond to organisms (e.g., Blepharisma japonicum, Colpidium campylum, Didinium nasutum, Paramecium caudatum, Spirostomum ambiguum, Stentor coeruleus) that cannot feed on this ciliate species. Daphnia longispina and Bursaria truncatella predators, which can feed on large prey of 125, or 200 m in diameter, respectively, also had no effect on the morphology of Euplotes. The extent of defense in Euplotes that was induced by 10 predators per milliliter during 24 h decreased the predation risk from those predators to 67% in the presence of S. sphagnetorum, to 50% with L. bullinum, and to 15% with C. diastrophus, compared to the typical form of Euplotes. In a natural population, the defensive form of E. daidaleos was found with average cell widths of 88 ± 8 m. The results indicate that predator-induced defense in natural Euplotes populations is beneficial to this prey and that it is adapted to the predation abilities of Euplotes predators, whereby energetical costs related to defensive changes may be saved.     

Allozyme diversity levels in two congeneric Dioon spp. (Zamiaceae, Cycadales) with contrasting rarities

Allozyme diversity and population genetic structure studies were conducted in populations of two Mexican cycad species occurring in adjacent and closely related biogeographic regions. We evaluated if rarity traits in Dioon caputoi, a micro-endemic species, and Dioon merolae, a regional endemic with a wider distribution, influence levels of genetic diversity in different ways. We also explored if genetic structure differs in these species, considering that they have similar population histories. Our results indicate that D. caputoi harbors lower levels of genetic diversity and allelic richness (H _E = 0.358, P = 76.9, A _r = 1.86) than D. merolae (H _E = 0.446, P = 92.3, A _r = 2). However, genetic structure does not differ between the two species despite their contrasting geographic distributions (F _ST = 0.06 vs. 0.07; D. caputoi and D. merolae, respectively). The comparison of population genetic structure information with historical and geographical aspects of the populations suggests that the rarity of D. caputoi might be due to relatively recent local ecological factors.     

Two new deer truffle species,Elaphomyces marmoratus and Elaphomyces fuscus spp. nov., from a secondary forest in Japan

We describe two new species of deer truffle, Elaphomyces marmoratus and E. fuscus spp. nov., collected from a secondary forest dominated by Quercus serrata, in Tokyo, Japan. Both species have morphological similarities to E. muricatus and E. granulatus; however, the former has a gleba without a purplish color and the latter has reticulated ascospores more closely resembling E. asperulus. Molecular phylogenetic analyses also support the assignment of these specimens as new species. ITS rDNA homologies with known species were low (<91% and <97%). In addition, phylogenetic trees using neighbor-joining and maximum likelihood methods showed that the sequences of the two new species each formed a monophyletic group within section Elaphomyces with bootstrap support of 99%. Analyses of ectomycorrhizal roots collected concurrently with the ascomata revealed that E. marmoratus is associated with at least Pinus densiflora, while E. fuscus is associated with at least Q. serrata.     

A new Planthopper (Insecta: Hemiptera: Nogodinidae) from Chiapas amber, middle Miocene of Mexico

A new species of Planthopper, Nogodina chiapaneca sp. nov. from the Mexican Chiapas amber (southeast Mexico) is described. The new species belongs to Nogodinidae: Nogodinini: Nogodinina. This is the second nogodinid species described from Mexican amber. Both species belong to Nogodinina, a taxon with a Neotropical distribution. The only recent species of Nogodina, N. reticulata, ranges from Honduras to Brazil and is unknown from Mexico yet.     

Morphology and phylogeny of four marine or brackish water spirotrich ciliates (Protozoa,Ciliophora) from China,with descriptions of two new species

In this study, we investigated the morphology and molecular phylogeny of four marine or brackish spirotrichean ciliates found in China, namely: Caryotricha sinica sp. nov., Prodiscocephalus orientalis sp. nov., P. cf. borrori, and Certesia quadrinucleata. Caryotricha sinica is characterized by its small size, seven cirral rows extending posteriorly to about 65% of the cell length, and four transverse cirri. Prodiscocephalus orientalis differs from its congeners mainly by the number of cirri in the “head” region and on the ventral side. The SSU rDNA sequence of P. cf. borrori differs from that of other population of P. borrori by ca. 40 bp. Consequently, the nominal species P. borrori is considered to be a species-complex. New data are provided for Certesia quadrinucleata. The Chinese population of C. quadrinucleata, for example, has fewer left marginal cirri than the other populations for which such data are available. Phylogenetic analyses based on SSU rDNA sequence data show that the genus Caryotricha is monophyletic. All typical “discocephalids” with a discoid “head” form a strongly supported clade that is sister to the unstable uronychiids + pseudoamphisiellids clade within the Euplotia. The genus Certesia forms a sister group to the Euplotes clade, also within the Euplotia assemblage.     

Photosymbiotic ascidians from Pari Island (Thousand Islands,Indonesia)

Photosymbiotic ascidian fauna were surveyed in the subtidal zone off Pari Island in the Thousand Islands (Java Sea, Indonesia). Nine species were recorded: Didemnum molle, Trididemnum miniatum, Lissoclinum patella, L. punctatum, L. timorense, Diplosoma gumavirens, D. simile, D. simileguwa, and D. virens. All of these species have been previously recorded in the Ryukyu Archipelago, Japan. Diplosoma gumavirens and D. simileguwa were originally described from the Ryukyu Archipelago in 2009 and 2005, respectively, and all of the observed species are potentially widely distributed in Indo–West Pacific coral reefs.