Guard cell anion channel SLAC1 is regulated by CDPK protein kinases with distinct Ca2+ affinities.

In response to drought stress, the phytohormone abscisic acid (ABA) induces stomatal closure. Thereby the stress hormone activates guard cell anion channels in a calcium-dependent, as well as -independent, manner. Open stomata 1 protein kinase (OST1) and ABI1 protein phosphatase (ABA insensitive 1) represent key components of calcium-independent ABA signaling. Recently, the guard cell anion channel SLAC1 was identified. When expressed heterologously SLAC1 remained electrically silent. Upon coexpression with Ca(2+)-independent OST1, however, SLAC1 anion channels appear activated in an ABI1-dependent manner. Mutants lacking distinct calcium-dependent protein kinases (CPKs) appeared impaired in ABA stimulation of guard cell ion channels, too. To study SLAC1 activation via the calcium-dependent ABA pathway, we studied the SLAC1 response to CPKs in the Xenopus laevis oocyte system. Split YFP-based protein-protein interaction assays, using SLAC1 as the bait, identified guard cell expressed CPK21 and 23 as major interacting partners. Upon coexpression of SLAC1 with CPK21 and 23, anion currents document SLAC1 stimulation by these guard cell protein kinases. Ca(2+)-sensitive activation of SLAC1, however, could be assigned to the CPK21 pathway only because CPK23 turned out to be rather Ca(2+)-insensitive. In line with activation by OST1, CPK activation of the guard cell anion channel was suppressed by ABI1. Thus the CPK and OST1 branch of ABA signal transduction in guard cells seem to converge on the level of SLAC1 under the control of the ABI1/ABA-receptor complex.

Venus flytrap trigger hairs are micronewton mechano-sensors that can detect small insect prey.

Venus flytraps detect moving insects via highly sensitive, action potential (AP)-producing trigger hairs, which act as high-sensitivity levers, crucial for prey capture and digestion. Controlled stimulation revealed that they can trigger APs for deflections >2.9°, angular velocities >3.4° s-1 and forces >29 µN. Hairs became desensitized and subsequently responded to fast consecutive stimulations; desensitization increased at lower temperatures. Recording of ant trigger hair contact events revealed that even small insects exceed the hairs' sensitivity threshold.

AUX1-mediated root hair auxin influx governs SCFTIR1/AFB-type Ca2+ signaling.

Auxin is a key regulator of plant growth and development, but the causal relationship between hormone transport and root responses remains unresolved. Here we describe auxin uptake, together with early steps in signaling, in Arabidopsis root hairs. Using intracellular microelectrodes we show membrane depolarization, in response to IAA in a concentration- and pH-dependent manner. This depolarization is strongly impaired in aux1 mutants, indicating that AUX1 is the major transporter for auxin uptake in root hairs. Local intracellular auxin application triggers Ca2+ signals that propagate as long-distance waves between root cells and modulate their auxin responses. AUX1-mediated IAA transport, as well as IAA- triggered calcium signals, are blocked by treatment with the SCFTIR1/AFB - inhibitor auxinole. Further, they are strongly reduced in the tir1afb2afb3 and the cngc14 mutant. Our study reveals that the AUX1 transporter, the SCFTIR1/AFB receptor and the CNGC14 Ca2+ channel, mediate fast auxin signaling in roots.

A genomewide catalogue of single nucleotide polymorphisms in white-beaked and Atlantic white-sided dolphins.

The field of population genetics is rapidly moving into population genomics as the quantity of data generated by high-throughput sequencing platforms increases. In this study, we used restriction-site-associated DNA sequencing (RADSeq) to recover genomewide genotypes from 70 white-beaked (Lagenorhynchus albirostris) and 43 Atlantic white-sided dolphins (L. acutus) gathered throughout their north-east Atlantic distribution range. Both species are at a high risk of being negatively affected by climate change. Here, we provide a resource of 38,240 RAD-tags and 52,981 nuclear SNPs shared between both species. We have estimated overall higher levels of nucleotide diversity in white-sided (π = 0.0492 ± 0.0006%) than in white-beaked dolphins (π = 0.0300 ± 0.0004%). White-sided dolphins sampled in the Faroe Islands, belonging to two pods (N = 7 and N = 11), showed similar levels of diversity (π = 0.0317 ± 0.0007% and 0.0267 ± 0.0006%, respectively) compared to unrelated individuals of the same species sampled elsewhere (e.g. π = 0.0285 ± 0.0007% for 11 Scottish individuals). No evidence of higher levels of kinship within pods can be derived from our analyses. When identifying the most likely number of genetic clusters among our sample set, we obtained an estimate of two to four clusters, corresponding to both species and possibly, two further clusters within each species. A higher diversity and lower population structuring was encountered in white-sided dolphins from the north-east Atlantic, in line with their preference for pelagic waters, as opposed to white-beaked dolphins that have a more patchy distribution, mainly across continental shelves.

Eimeria auratae n. sp. (Apicomplexa: Eimeriidae) infecting the lizard Mabuya aurata in Saudi Arabia.

Eimeria auratae n. sp. was described from the gall bladder of the lizard Mabuya aurata collected at Al-Hofuf village, eastern region, Saudi Arabia. Morphology of sporulated as well as non-sporulated oocysts were studied. Sporulated oocysts were ellipsoidal 22-31.5x13.5-21.8 (27.7x18.5) microm with smooth brownish-yellow bilayered wall, 1.1 (0.9-1.3) microm. Micropyle, polar granule and oocyst residuum were absent. Sporocysts were ellipsoidal 10.5-12.8x7.5-9 (11.8x8.5) microm. Sporocyst residuum was present but Stieda body was absent. Sporozoites were crescent-shaped, blunt at one end and slightly tapered at the other. Eimeria species from Scincidae were compared.

Trichodinid ectoparasites (Ciliophora: Peritrichida) of some River Nile fish, Egypt.

Four species of trichodinid ectoparasites (Ciliophora: Peritrichida) were collected from the gills of the following River Nile fish in Egypt: Hydrocynus forskalii, Mormyrus kannume, Schilbe mystus. These species are: Trichodina heterodentata Duncan, 1977, Trichodina fahaka sp. n., Trichodinella epizootica Raabe, 1950, Tripartiella dactylodentata sp. n. Photomicrographs and morphometric data are presented for each species.

Identification of Acanthamoeba strains isolated from a freshwater course in Saudi Arabia.

A total of 40 freshwater samples, collected from Wadi Hanifah, were cultured on non-nutrient agar + 1% NaCl for the detection of Acanthamoeba. Thirty three strains of Acanthamoeba were isolated and subcultured for further identification according to cyst morphology. The isolated strains of Acanthamoeba were found belonging to 4 species which were A. astronyxis, A. comandoni, A. culbertsoni and A. quina. The optimum and maximum tolerated temperatures for growth as well as the pathogenicity of each strain for mice were also recorded. This water source is hazardous for human use.

Five new myxosporean species (Myxozoa: Myxosporea) infecting the Nile tilapia Oreochromis niloticus in Bahr Shebin, Nile Tributary, Nile Delta, Egypt.

Five new myxosporean species belonging to three different genera were described from the Nile tilapia Oreochromis niloticus in Bahr Shebin, Nile Tributary, Nile Delta, Egypt. These species are: Zschokkella nilei sp. n., Ortholinea africanus sp. n., Triangula egyptica sp. n., Myxobolus fomenai sp. n., and Myxobolus branchiophilus sp. n. Morphometry, light microscopy, and hand drawing of mature spores and plasmodia were presented for each species.

Four new species of Ceratomyxa Thelohan 1892 (Myxozoa: Myxosporea: Ceratomyxidae) infecting the gallbladder of some Red Sea fishes.

Four new Ceratomyxa species were described from the gallbladder of four Red Sea fishes at Suez and Hurghada, Egypt. These species are Ceratomyxa bassoni sp. n. from Plectorhinchus gaterinus (Forsskal 1775) at Suez and Hurghada, Ceratomyxa entzerothi sp. n. from Valamugil seheli (Forsskal 1775) at Suez and Hurghada, Ceratomyxa swaisi sp. n. from Saurida undosquamis (Richardson 1848) at Suez only and Ceratomyxa hurghadensis sp. n. from Fistularia commersonii Ruppell 1838 at Hurghada only. Their taxonomic affinities to other species are discussed.

Light and electron microscopic studies on Kudoa pagrusi sp. n. (Myxosporea: Multivalvulida) infecting the heart of sea bream Pagrus pagrus (L.) from the Red Sea.

A new multivalvulid species, Kudoa pagrusi sp. n., was described from the sea bream Pagrus pagrus. The cysts were oval to ellipsoidal and restricted to the cardiac muscles. The mean spore measurements were 7.0 microm in length and 6.4 microm in width as well as in thickness, while the mean polar capsule measurements were 3.7 microm in length and 1.5 microm in width. The ultrastructural features of the present species proved that the spore have four polar capsules with four shell valves that are the main criteria for genus Kudoa.

Redescription of the rare heterotrichid ciliate, Copemetopus subsalsus Villeneuve-Brachon, 1940.

The morphology and infraciliature of the rare heterotrichid ciliate Copemetopus subsalsus Villeneuve-Brachon, 1940 were studied in live and protargol-impregnated specimens and also by scanning electron microscopy. It is characterized by a dumbbell-shaped macronucleus, a specific dorsal brush cilia, an oblique peristome, and a distinct S-shaped adoral zone of membranelles equipped with whip-shaped anterior adoral membranelles.

Effect of gonadal steroid hormones on the metabolic rate of the cold-acclimated gonadectomized male and female Chalcides ocellatus (Forskal).

Male and female Chalcides ocellatus were gonadectomized and cold acclimated at 15 degrees for 1 week. Lizards were injected with testosterone and estradiol, and their oxygen consumption was determined at 15 degrees. Testosterone and estradiol caused a significant increase in the whole body rate of oxygen consumption in male and female lizards, respectively.