Morphologic and molecular data suggest that Lynnella semiglobulosa n. g., n. sp. represents a new family within the subclass Choreotrichia (Ciliophora, Spirotrichea)

The morphology, morphogenesis, and phylogeny of an undescribed oligotrich sensu lato (s. lat.) ciliate, Lynnella semiglobulosa n. g., n. sp., found in Daya Bay, southern China, were investigated. This species shares some features with both oligotrichs sensu stricto and choreotrichs, but most morphological and morphogenetic characters as well as the phylogenetic analysis suggest that it should be assigned into subclass Choreotrichia temporarily. Lynnella semiglobulosa is distinguished from members of all known genera and families of the subclass Choreotrichia by a unique combination of characteristics of the buccal and somatic ciliatures. Thus, a new family Lynnellidae n. fam. and a new genus Lynnella n. g. are proposed for it. The new family is distinguished by an open adoral zone of membranelles (AZM) in which, however, there are no ventral membranelles; the distal and proximal portions of the new adoral zone lie close to each other forming an open circle in stomatogenesis. The new genus Lynnella is characterized by possessing two longitudinally oriented somatic kineties, one dorsal and one ventral, several proximal membranelles progressively lengthened toward the proximal end of adoral zone, and two macronuclear nodules. In phylogenetic analyses based on small subunit rRNA gene sequences, L. semiglobulosa clustered basally to all choreotrichs, but with relatively weak support; nevertheless, the possibility of a relationship with the subclass Oligotrichia was not rejected by the approximately unbiased nor Shimodaira-Hasegawa test. Based on morphological, morphogenetic, and molecular evidence of L. semiglobulosa, it is confirmed that the open AZM should be a plesiomorphic character of oligotrichs s. lat. as suggested previously.     

Microbial–meiofaunal interrelationships in coastal sediments of the Red Sea

Population density and biomass of bacteria and meiofauna were investigated seasonally in the sediments of the north-western bank of Red Sea. Samples of sediments were collected seasonally from three different stations to determine microphytobenthic biomass (chlorophyll a), protein, lipid, carbohydrate, and total organic matter concentrations. These investigations revealed that microbial components tended to increase their dominancy, whereas sensitive meiofauna were extremely reduced during the entire study period. Thus a very low density of the total meiofauna (with an annual average of 109 ± 26 ind./10 cm²) was recorded whilst the benthic microbial population densities exhibited higher values (ranging from 0.31 ± 0.02 × 10⁸ to 43.67 ± 18.62 × 10⁸/g dry sediment). These changes in the relative importance analysis of benthic microbial components versus meiofaunal ones seem to be based on the impact of organic matter accumulation on the function and structure of these benthic communities. Proteins, lipids and carbohydrates showed very low concentration values, and the organic matter mostly consisted of carbohydrates, reflecting lower nutritional values for benthic fauna in general and meiofauna in particular. The distribution of microbial and meiofaunal communities seems to be dependent on the quality of the organic matter rather than on its quantity. Total organic matter concentrations varied between 5.8 and 7.6 mg/g, with organic carbon accounting for only 32% of the total organic matter. Chlorophyll a attained very low values, fluctuating between 0.11 and 0.56 μg/g, indicating the oligotrophy of the studied area. The very low concentration of chlorophyll a in the Red Sea sediment suggests that the sedimentary organic matter, heterotrophic bacteria and/or protozoa constitute an alternative resource that is consumed by meiofauna when algae are less abundant. Protozoa, therefore, represent the “missing link in bacteria–meiofauna interaction in the Red Sea marine sediment ecosystem.     

Effects of citronella oil (Cymbopogon winterianus Jowitt ex Bor) on Spodoptera frugiperda (J. E. Smith) midgut and fat body

The armyworm, Spodoptera frugiperda, is the principal pest of corn in Brazil. Control is achieved primarily by synthetic insecticides, which cause problems for the agro-ecosystem. Alternative methods of control are under investigation and citronella (Cymbopogon winterianus) essential oil appears to be a promising agent. We investigated the effects of citronella oil using histological, histochemical and immunohistochemical methods. The midgut of larvae treated with citronella exhibited altered epithelium including cytoplasmic protrusions, columnar cell extrusion, pyknotic nuclei, and increased periodic acid-Schiff positive granules. Regenerative cells in the epithelium of the midgut increased in number, which facilitated subsequent regeneration of this tissue. After exposure to citronella, trophocytes, the principal cell type of the fat body, possessed enlarged vacuoles and mitotic bodies, and contained reduced amounts of glycogen, lipid, and protein. Citronella oil caused morphological changes of the midgut and reduction of stored resources in the fat body, which may adversely affect insect reproduction and survival.     

A Single-Pore Residue Renders the Arabidopsis Root Anion Channel SLAH2 Highly Nitrate Selective

In contrast to animal cells, plants use nitrate as a major source of nitrogen. Following the uptake of nitrate, this major macronutrient is fed into the vasculature for long-distance transport. The Arabidopsis thaliana shoot expresses the anion channel SLOW ANION CHANNEL1 (SLAC1) and its homolog SLAC1 HOMOLOGOUS3 (SLAH3), which prefer nitrate as substrate but cannot exclude chloride ions. By contrast, we identified SLAH2 as a nitrate-specific channel that is impermeable for chloride. To understand the molecular basis for nitrate selection in the SLAH2 channel, SLAC1 and SLAH2 were modeled to the structure of HiTehA, a distantly related bacterial member. Structure-guided site-directed mutations converted SLAC1 into a SLAH2-like nitrate-specific anion channel and vice versa. Our findings indicate that two pore-occluding phenylalanines constrict the pore. The selectivity filter of SLAC/SLAH anion channels is determined by the polarity of pore-lining residues located on alpha helix 3. Changing the polar character of a single amino acid side chain (Ser-228) to a nonpolar residue turned the nitrate-selective SLAH2 into a chloride/nitrate-permeable anion channel. Thus, the molecular basis of the anion specificity of SLAC/SLAH anion channels seems to be determined by the presence and constellation of polar side chains that act in concert with the two pore-occluding phenylalanines.     

Establishment of a new hypotrichous genus,Heterotachysoma n. gen. and notes on the morphogenesis of Hemigastrostyla enigmatica (Ciliophora,Hypotrichia)

A marine hypotrich ciliate, Heterotachysoma multinucleatum (Gong and Choi, 2007) n. comb., found in coastal waters near Qingdao, China, was investigated. Heterotachysoma multinucleatum is characterized by its dorsal ciliature arranged in Gonostomum-pattern. Additionally, a new genus, Heterotachysoma n. gen., is established which is mainly characterized by: 18-cirri pattern; flexible body; three dorsal kineties with no dorsomarginal kineties nor kinety fragmentation; one right and one left row of marginal cirri; caudal cirri absent. The genus Tachysoma is redefined, and three new combinations, T. multinucleatum, T. ovatum and T. dragescoi, are proposed. The morphogenesis of Hemigastrostyla enigmatica (Dragesco and Dragesco-Kernéis, 1986) Song and Wilbert, 1997, is also described. Compared with that of its congeners, the differences are mainly in the dorsal ciliature: (1) the dorsal kinety anlagen are formed de novo in H. enigmatica (vs. intrakinetally in H. paraenigmatica and H. elongata); (2) the dorsal kineties anlagen develop in secondary mode in H. enigmatica (vs. primary mode in H. paraenigmatica); (3) the kinetal fragment anterior to the right marginal row in both filial product is absent in both H. enigmatica and H. elongata (vs. present in H. paraenigmatica). These findings suggest that morphogenesis is not uniform among members of the genus Hemigastrostyla.     

Reproductive biology of the Suez Canal spider crab Schizophrys aspera (H. Milne Edwards, 1834: Crustacea: Brachyura: Majidae)

A reproductive biology study of the spider crab Schizophrys aspera (H. Milne Edwards, 1834) was conducted in the Suez Canal from July 2012 to June 2013. The annual sex ratio (Male:Female) of S. aspera was female biased with values of 1:1.25. Out of the four ovarian development stages of this crab, two stages were observed in the Suez Canal throughout the whole year. The ovigerous crab’s carapace width varied from 28 to 52 mm. This crab species can spawn during most of the year in the canal water, with a peak during late spring and early winter. The fecundity of ovigerous females ranged between 2349 and 13600 eggs with a mean of 5494 ± 1486 eggs. Female crabs that reached sexual maturity exhibited a minimum carapace width varying between 22 and 46 mm, and fifty percentage of all ovigerous females showed a carapace width of 36 mm.     

Sensilla coeloconica ringed by microtrichia in host‐seeking biting midges

The distribution and morphology of antennal sensilla coeloconica in parasitic and predaceous biting midges were studied in females of Forcipomyia (feeding on the blood of frogs), Atrichopogon (feeding on haemolymph), Austroconops, Culicoides (feeding on the blood of birds and mammals) and Brachypogon (feeding on haemolymph and dissolved tissues of insects) (all: Diptera: Ceratopogonidae). A Lower Cretaceous female of Archiculicoides (Diptera: Ceratopogonidae) from Lebanese amber, which fed on the blood of unknown vertebrates, was also examined. In sensilla coeloconica ringed by microtrichia, the peg is grooved longitudinally and protrudes distinctly from the pit. We suggest that the microtrichia encircling the protruding peg form a structure resembling a picket fence in order to maintain a higher level of humidity, which facilitates the capture and transport of odour molecules through the channels in the peg wall. Sensilla coeloconica ringed by microtrichia function as very effective chemoreceptors in host‐ and prey‐seeking activity. During the evolution of Ceratopogonidae, sensilla coeloconica with a fence of microtrichia have evolved twice in groups feeding on the blood of vertebrates (i.e. in the basal lineage: Lower Cretaceous or earlier) and in the subgenus Lasiohelea of Forcipomyia (Palaeogene). Sensilla coeloconica ringed by microtrichia are described for the first time in the relict genus Austroconops.     

Morphology and molecular phylogeny of two new species of Spirostrombidium (Ciliophora,Oligotrichia), with a key to the species of Spirostrombidium

Microscopic methods were used to investigate the morphological characterization of two novel oligotrich ciliates, Spirostrombidium paraurceolare sp. nov. and Spirostrombidium faurefremieti sp. nov., isolated from a mangrove wetland in Zhanjiang and an intertidal sandy beach in Qingdao, respectively. Spirostrombidium paraurceolare sp. nov. is characterized by three thigmotactic and 8–10 buccal membranelles, the girdle kinety spiralling around cell with one and a half whorls, and located at right anterior third of dorsal side anteriorly. Spirostrombidium faurefremieti sp. nov. can be recognized by a prominently deep and broad buccal cavity, two thigmotactic and 15–19 buccal membranelles, and the girdle kinety spiralling around cell with two whorls. The small subunit ribosomal RNA genes of these two species were sequenced and compared with those of their congeners to reveal nucleotide differences. Phylogenetic analyses revealed that the genus Spirostrombidium is non-monophyletic. Spirostrombidium faurefremieti sp. nov. falls into a clade comprising most congeners, but Spirostrombidium paraurceolare sp. nov. branches off and groups with Varistrombidium kielum with moderate support. A key to the identification of Spirostrombidium species is also provided.www.zoobank.org/urn:lsid:zoobank.org:pub:AB96BEE6-BE3A-4B95-B75A-3469B1C53ABB2