The<Emphasis Type="Italic"> Trox-2</Emphasis> Hox/ParaHox gene of<Emphasis Type="Italic"> Trichoplax</Emphasis> (Placozoa) marks an epithelial boundary

Hox and ParaHox genes are implicated in axial patterning of cnidarians and bilaterians, and are thought to have originated by tandem duplication of a single ProtoHox gene followed by duplication of the resultant gene cluster. It is unclear what the ancestral role of Hox/ParaHox genes was before the divergence of Cnidaria and Bilateria, or what roles the postulated ProtoHox gene(s) played. Here we describe the full coding region, spatial expression and function of Trox-2, the single Hox/ParaHox-type gene identified in Trichoplax adhaerens (phylum Placozoa) and either a candidate ProtoHox or a ParaHox gene. Trox-2 is expressed in a ring around the periphery of Trichoplax, in small cells located between the outer margins of the upper and lower epithelial cell layers. Inhibition of Trox-2 function, either by uptake of morpholino antisense oligonucleotides or by RNA interference, causes complete cessation of growth and binary fission. We speculate that Trox-2 functions within a hitherto unrecognized population of possibly multipotential peripheral stem cells that contribute to differentiated cells at the epithelial boundary of Trichoplax.Edited by D. Tautz     

Genome-wide analysis of transposable elements and tandem repeats in the compact placozoan genome

   

The placozoan Trichoplax adhaerens has a compact genome with many primitive eumetazoan characteristics. In order to gain a better understanding of its genome architecture, we conducted a detailed analysis of repeat content in this genome. The transposable element (TE) content is lower than that of other metazoans, and the few TEs present in the genome appear to be inactive. A new phylogenetic clade of the gypsy-like LTR retrotransposons was identified, which includes the majority of gypsy-like elements in Trichoplax. A particular microsatellite motif (ACAGT) exhibits unexpectedly high abundance, and also has strong association with its nearby genes.     

Conserved biophysical features of the CaV2 presynaptic Ca2+ channel homologue from the early-diverging animal Trichoplax adhaerens

The dominant role of Ca_V2 voltage-gated calcium channels for driving neurotransmitter release is broadly conserved. Given the overlapping functional properties of Ca_V2 and Ca_V1 channels, and less so Ca_V3 channels, it is unclear why there have not been major shifts toward dependence on other Ca_V channels for synaptic transmission. Here, we provide a structural and functional profile of the Ca_V2 channel cloned from the early-diverging animal Trichoplax adhaerens, which lacks a nervous system but possesses single gene homologues for Ca_V1–Ca_V3 channels. Remarkably, the highly divergent channel possesses similar features as human Ca_V2.1 and other Ca_V2 channels, including high voltage–activated currents that are larger in external Ba²⁺ than in Ca²⁺; voltage-dependent kinetics of activation, inactivation, and deactivation; and bimodal recovery from inactivation. Altogether, the functional profile of Trichoplax Ca_V2 suggests that the core features of presynaptic Ca_V2 channels were established early during animal evolution, after Ca_V1 and Ca_V2 channels emerged via proposed gene duplication from an ancestral Ca_V1/2 type channel. The Trichoplax channel was relatively insensitive to mammalian Ca_V2 channel blockers ω-agatoxin-IVA and ω-conotoxin-GVIA and to metal cation blockers Cd²⁺ and Ni²⁺. Also absent was the capacity for voltage-dependent G-protein inhibition by co-expressed Trichoplax Gβγ subunits, which nevertheless inhibited the human Ca_V2.1 channel, suggesting that this modulatory capacity evolved via changes in channel sequence/structure, and not G proteins. Last, the Trichoplax channel was immunolocalized in cells that express an endomorphin-like peptide implicated in cell signaling and locomotive behavior and other likely secretory cells, suggesting contributions to regulated exocytosis.     

The cytoskeleton of the fiber cells of Trichoplax adhaerens (Placozoa)

Summary The cytoskeleton of Trichoplax adhaerens fiber cells was studied after chemical fixation, freeze-substitution, lysis of attached cells with nonionic detergents and by immunofluorescence. Cytoskeletal elements present in the cell bodies and reaching into the extensions include microtubules, intermediate filaments, 6–7 nm and 2–3 nm microfilaments. The latter seem to interconnect other cytoskeletal elements. Actin-like microfilaments are found both as networks and parallel strands. Immunofluorescence with antiactin shows the presence of actin in the cell body, underneath the plasmalemma and within the extensions. Both the results of immunofluorescence and the identification of 6–7 nm actin-like microfilaments support the concept of contractility of the fiber cells as the cause of the rapid shape changes of Trichoplax. Anti-tubulin fluorescence corresponds to the location of microtubules in the extensions as well as the cell bodies of the fiber cells. The extensions are withdrawn upon depolymerization of the microtubules by colchicine.     

Mediated electrochemical measurement of the inhibitory effects of furfural and acetic acid on <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> and <Emphasis Type="Italic">Candida shehatae</Emphasis>

The toxic effects of furfural and acetic acid on two yeasts, Saccharomyces cerevisiae and Candida shehatae, were evaluated using an electrochemical method. Intracellular redox activities were lowered by 40% and 78% for S. cerevisiae and C. shehatae, respectively, by 8 g furfural l^–1, and by 46% and 67%, respectively, by 8 g acetic acid l^–1. The proposed method can accurately measure the effects of inhibitors on cell cultures.Revisions requested 27 September 2004/17 November 2004; Revisions received 15 November 2004/10 December 2004     

Placozoa: at least two

It was shown that compensatory base changes (CBCs) in internal transcribed spacer 2 (ITS2) sequence-structure alignments can be used for distinguishing species. Using the ITS2 Database in combination with 4SALE — a tool for synchronous RNA sequence and secondary structure alignment and editing — in this study we present an in-depth CBC analysis for placozoan ITS2 sequences and their respective secondary structures. This analysis indicates at least two distinct species in Trichoplax (Placozoa) supporting a recently suggested hypothesis, that Placozoa is “no longer a phylum of one”. The first two authors contributed equally to this work.     

Effects of <Emphasis Type="Italic">N</Emphasis>- and <Emphasis Type="Italic">C</Emphasis>-terminal truncation of HP (2-20) from <Emphasis Type="Italic">Helicobacter pylori</Emphasis> ribosomal protein L1 (RPL1) on its anti-microbial activity

HP (2-20) [derived from the N-terminal region of Helicobacter pylori Ribosomal Protein L1 (RPL1)], a 19-mer peptide, possesses broad-spectrum anti-microbial activity. As the N- (residues 2–3) and C-terminal (residues 14–20) residues can be deleted without affecting antimicrobial activity, we have now determined the minimum chain length necessary for the retention of antimicrobial activity, and its mode of action. The N- (residues 2–3) and C-terminal (residues 17–20) truncated fragments [HP (4–16)] induce increased antibiotic activity against several bacterial strains without hemolysis. Flow cytometric analysis, scanning electron microscopy and fluorescence confocal microscopy revealed that HP (4–16) acted rapidly on the plasma membranes of the fungal cells in a salt- and energy-independent manner.Revisions requested 16 September 2004/1 November 2004; Revisions received 29 October 2004/8 December 2004     

Coordinated Feeding Behavior in Trichoplax,an Animal without Synapses

Trichoplax is a small disk-shaped marine metazoan that adheres to substrates and locomotes by ciliary gliding. Despite having only six cell types and lacking synapses Trichoplax coordinates a complex sequence of behaviors culminating in external digestion of algae. We combine live cell imaging with electron microscopy to show how this is accomplished. When Trichoplax glides over a patch of algae, its cilia stop beating so it ceases moving. A subset of one of the cell types, lipophils, simultaneously secretes granules whose content rapidly lyses algae. This secretion is accurately targeted, as only lipophils located near algae release granules. The animal pauses while the algal content is ingested, and then resumes gliding. Global control of gliding is coordinated with precise local control of lipophil secretion suggesting the presence of mechanisms for cellular communication and integration.     

Conidia production by <Emphasis Type="Italic">Beauveria bassiana</Emphasis> (for the biocontrol of a diamondback moth) during solid-state fermentation in a packed-bed bioreactor

Conidia of Beauveria bassiana CS-1, which have the potential for the control of the diamondback moth (Plutella xylostella), were produced by solid-state fermentation (SSF) using a packed-bed bioreactor with rice straw and wheat bran. As the packing density and the bed height were increased, the production of conidia decreased. In a packed-bed bioreactor under no aeration and no addition of polypropylene (PP) foam (control), the total average of conidia was 4.9 × 10⁸ g^-1. The production of conidia was affected more by the addition of PP foam as an inert support than forced aeration and was approx. 23 times higher than that of the control. The total average of conidia produced by B. bassiana was 1.1–1.2 × 10¹⁰ g^-1 . Revisions requested 6 September 2004/2 November 2004; Revisions received 1 November 2004/8 December 2004     

Introgressive hybridization of chars of the genus <Emphasis Type="Italic">Salvelinus</Emphasis> as inferred from mitochondrial DNA variation

Nucleotide sequence analysis of the mitochondrial cytochrome b gene in the genus Salvelinus revealed hybrids with S. leucomaenis in S. malma malma populations of the Northern Okhotsk Sea basin. Hybrids of S. m. malma and S. m. krascheninnikovi were found in S. m. malma populations from the Northern Okhotsk Sea basin and Kamchatka. The findings testify to a secondary contact and mtDNA transfer between these species and forms. It was assumed that introgressive hybridization took place both long ago and relatively recently and occurred in one direction: from S. leucomaenis or S. m. krascheninnikovi to S. m. malma.Translated from Genetika, Vol. 40, No. 12, 2004, pp. 1678–1685.Original Russian Text Copyright © 2004 by Radchenko.     

Antibacterial activity of larval saliva of the European paper wasp <Emphasis Type="Italic">Polistes dominulus</Emphasis> (Hymenoptera,Vespidae)

Summary. Microbiological tests demonstrated antibacterial activity (against Bacillus subtilis, Gram +, and Escherichia coli, Gram –) of larval salivary secretions of Polistes dominulus but failed to demonstrate its antifungal activity.Received 7 November 2003; revised 17 March 2004; accepted 29 March 2004.     

Cellular aggregate size as the critical factor for flavonoid production by suspension cultures of <Emphasis Type="Italic">Saussurea medusa</Emphasis>

Three previously established cell lines (yellow, red and white) of Saussurea medusa were investigated for jaceosidin and hispidulin production. Maximum yields of the jaceosidin and hispidulin were obtained in the red cell line at 75 ± 0.41 and 6.4 ± 0.31 mg l^-1. Production of jaceosidin and hispidulin correlated with the sizes of compact callus aggregates (CCA) and cellular viability. In the red cell line, the sizes of CCA were predominantly of 2–4mm diameter and accounted for 64% biomass. This line had a sustained cell viability over 10 successive sub-cultures.Revisions requested 3 September 2004/27 October 2004; Revisions received 22 October 2004/18 November 2004     

Blooms of Pseudo-nitzschia and domoic acid in the San Pedro Channel and Los Angeles harbor areas of the Southern California Bight, 2003–2004

Abundances of Pseudo-nitzschia spp. and concentrations of particulate domoic acid (DA) were determined in the Southern California Bight (SCB) along the coasts of Los Angeles and Orange Counties during spring and summer of 2003 and 2004. At least 1500 km² were affected by a toxic event in May/June of 2003 when some of the highest particulate DA concentrations reported for US coastal waters were measured inside the Los Angeles harbor (12.7 μg DA L⁻¹). Particulate DA levels were an order of magnitude lower in spring of 2004 (February and March), but DA concentrations per cell at several sampling stations during 2004 exceeded previously reported maxima for natural populations of Pseudo-nitzschia (mean = 24 pg DA cell⁻¹, range = 0–117 pg DA cell⁻¹). Pseudo-nitzschia australis dominated the Pseudo-nitzschia assemblage in spring 2004. Overall, DA-poisoning was implicated in >1400 mammal stranding incidents within the SCB during 2003 and 2004. Ancillary physical and chemical data obtained during our regional surveys in 2004 revealed that Pseudo-nitzschia abundances, particulate DA and cellular DA concentrations were inversely correlated with concentrations of silicic acid, nitrogen and phosphate, and to specific nutrient ratios. Particulate DA was detected in sediment traps deployed at 550 and 800 m depth during spring of 2004 (0.29–7.6 μg DA (g sediment dry weight)⁻¹). The highest DA concentration in the traps was measured within 1 week of dramatic decreases in the abundances of Pseudo-nitzschia in surface waters. To our knowledge these are the deepest sediment trap collections from which DA has been detected. Sinking of the spring Pseudo-nitzschia bloom may constitute a potentially important link between DA production in surface waters and benthic communities in the coastal ocean near Los Angeles. Our study indicates that toxic blooms of Pseudo-nitzschia are a recurring phenomenon along one of the most densely populated coastal stretches of the SCB and that the severity and magnitude of these events can be comparable to or greater than these events in other geographical regions affected by domoic acid.     

Age and growth of <Emphasis Type="Italic">Schizothorax waltoni</Emphasis> in the Yarlung Tsangpo River in Tibet,China

Age and growth were studied for Schizothorax waltoni in the middle reaches of the Yarlung Tsangpo River in Tibet, southwest of China, from April 2004 to September 2006. A total of 201 specimens were collected ranging from 110 to 580 mm in standard length (SL). In contrast to other otoliths, sectioned lapillus showed a clear pattern of alternating opaque and hyaline zones. Marginal increment analyses showed that the increments, each composed of one opaque and one hyaline zone, are deposited annually. Opaque edges were prevalent from May to August. The von Bertalanffy growth parameters based on sectioned otolith data were L _t  = 689.8{1 − exp[0.051 (t + 3.275)]} for males, and L _t  = 691.1{1 − exp[0.056 (t + 2.466)]} for females. The slow growth and long life indicate that S. waltoni is vulnerable to overfishing and that harvesting strategies for the species should be conservative.     

Production of an anti-fungal substance for biological control of <Emphasis Type="Italic">Phytophthora capsici</Emphasis> causing phytophthora blight in red-peppers by <Emphasis Type="Italic">Streptomyces halstedii</Emphasis>

The culture broth of Streptomyces halstedii AJ-7 suppressed the growth of Phytophthora capsici, which causes phytophthora blight in red-peppers, with less than 1% survival of the pathogen after 12 h of treatment. The low molecular fraction ( 10 kDa) of the culture broth retained anti-fungal activity against P. capsici after being held at 100 °C for 6 h.Revisions requested/26 August 2004; Revisions received 16 August 2004/10 December 2004     

Effect of seawater temperature on the productivity of <Emphasis Type="Italic">Laminaria japonica</Emphasis> in the Uwa Sea,southern Japan

Recent studies on global climate change report that increase in seawater temperature leads to coastal ecosystem change, including coral bleaching in the tropic. In order to assess the effect of increased seawater temperature on a temperate coastal ecosystem, we studied the inter-annual variation in productivity of Laminaria japonica using long-term oceanographic observations for the Uwa Sea, southern Japan. The annual productivity estimates for L. japonica were 2.7 ± 2.5 (mean ± SD) kg wet wt. m⁻¹ (length of rope) (2003/2004), 1.0 ± 0.6 kg wet wt. m⁻¹ (2004/2005) and 12.1 ± 12.5 kg wet wt. m⁻¹ (2005/2006). Our previous study using the same methodology at the same locality reported that the productivity was estimated for the 2001/2002 (33.3 ± 15.2 kg wet wt. m⁻¹) and 2002/2003 (34.0 ± 8.7 kg wet wt. m⁻¹) seasons. Productivity in 2003/2004 and 2004/2005 was significantly lower than in years 2001/2002, 2002/2003 and 2005/2006. A comparison of oceanographic conditions among the 5 years revealed the presence of threshold seawater temperature effects. When the average seawater temperature during the first 45 days of each experiment exceeded 15.5°C, productivity was reduced to about 10 % of that in cooler years. Moreover the analysis of growth and erosion rates indicates that when the seawater temperature was over 17.5°C, erosion rate exceeded growth rate. Thus, an increase of seawater temperature of just 1°C during winter drastically reduces the productivity of L. japonica in the Uwa Sea.     

Age-Related Changes in Oxygen Consumption in the Edible Mussel <Emphasis Type="Italic">Mytilus edulis</Emphasis> from the White Sea

We determined the rate of oxygen consumption in the White Sea edible mussel Mytilus edulis of different ages. The mass-specific rate of oxygen consumption proved to decrease with mussel age according to the equation: = 40.1/(1 – e ^–0.194t ), where is mass-specific rate of oxygen consumption and t is age. Allometric coefficients of the oxygen consumption rate–soft tissue weight relationship were also determined.     

Effect of an introgression from <Emphasis Type="Italic">Aegilops cylindrica</Emphasis> host on manifestation of productivity traits in winter common wheat F<Subscript>2</Subscript> plants

The effect of introgression of a chromosome 1D segment from Aegilops cylindrica to winter common wheat on productivity traits in F₂ plants was studied using storage protein loci as genetic markers. An allele of the gliadin-coding Gli-D1 locus served as a marker of the introgression. Using of two- and three-locus interaction models, it was shown that the introgression tagged with Gli-D1 affected the manifestation of productivity traits (productive tillering, grain weight per plant and grain number per plant) through interaction with other marker storage protein loci: Glu-B1, Glu-D1, and Gli-B2.Translated from Genetika, Vol. 40, No. 12, 2004, pp. 1662–1667.Original Russian Text Copyright © 2004 by Kozub, I. Sozinov, A. Sozinov.     

The fungicidal activity of an extracellular glycolipid from <Emphasis Type="Italic">Sympodiomycopsis paphiopedili</Emphasis> sugiyama <Emphasis Type="Italic">et al.</Emphasis>

The yeast Sympodiomycopsis paphiopedili (Ustilaginomycetes) produces an extracellular glycolipid, which possesses the maximum antifungal activity at a pH of the medium equal to 4.0–4.5. Among the approximately 300 tested species of yeastlike and mycelial fungi, more than 80% (including species pathogenic for plants, animals, and humans) were found to be sensitive to this glycolipid.Translated from Mikrobiologiya, Vol. 73, No. 6, 2004, pp. 841–845.Original Russian Text Copyright © 2004 by W. Golubev, T. Kulakovskaya, E. Kulakovskaya, N. Golubev.