Fecundity of Euphausia lucens (Hansen) - laboratory evidence for multiple broods

There has been much controversy in the past as to how many broods euphausiids are capable of producing per season. Several authors have suggested that multiple broods are possible, although this has not been demonstrated in the laboratory. In the present study, two Euphausia lucens females were shown to spawn continuously over a period of at least 2.5 months. The euphausiids produced ≈ 33–40 broods during this period, representing 134–192% of their body carbon. Daily egg production rates varied from 0 to 86 eggs, representing a mean of 3–4% of their body carbon d⁻¹. Egg production rates were often severely depressed during moulting, and were also somewhat lower during experimental manipulation (changing food conditions). The results suggest that egg production by E. lucens, and perhaps by many other euphausiid species, are considerably higher than was previously thought.     

The presence of the potentially toxic genera Ostreopsis and Coolia (Dinophyceae) in the North Aegean Sea, Greece

The examination of macrophyte, water and sediment samples, collected at depths less than 1.5 m from 50 different sites along the North Aegean coasts, has revealed, for the first time in Greek coastal waters, the presence of two Ostreopsis species (O. ovata and O. cf. siamensis) and Coolia monotis in the majority of the sampling sites (94% and 100%, respectively). Other epiphytic dinoflagellates of the genera Prorocentrum and Amphidinium and diatoms were accompanying species in this epiphytic community. Morphometric features, plate formula and thecal ornamentation were used for species identification. O. ovata cells were smaller in dorsoventral (DV) diameter and width (W) (26.18–61.88 μm and 13.09–47.60 μm, respectively) in comparison with O. cf. siamensis (35.70–65.45 μm and 23.80–49.98 μm, respectively). In contrast, the anterioposterior (AP) diameter of O. cf. siamensis was smaller (14.28–26.18 μm) resulting in DV/AP ≈ 3, whereas the above ratio for O. ovata was less than 2 (AP ranging between 14.28–35.70 μm). Moreover, the theca of O. ovata cells was ornamented with scattered pores, which fluctuated in a wider range (0.07–0.32 μm) than those of O. cf. siamensis (0.23–0.29 μm). Coolia monotis cells were almost round with average DV diameter 26.88 μm, AP 25.66 μm and width 26.76 μm. Small and large cells were recorded in both field and culture populations of Ostreopsis spp. and C. monotis, while hyaline cysts were observed for O. ovata. The presence of O. ovata and O. cf. siamensis exhibited a clear seasonal pattern dominating (maximum abundance up to 4.05 × 10⁵ cells gr⁻¹ fwm) the period from midsummer to late autumn in years 2003 and 2004, while C. monotis was found also in winter and spring months.     

Evidence for two Qa-like quinone binding sites in the reaction centre of Rhodopseudomonas viridis

The oxidation-reduction potential of the iron-quinone electron acceptors in the reaction centre of Rhodopseudomonas viridis has been reinvestigated. In chromatophores treated with o-phenanthroline to remove the secondary acceptor Q_b, two steps were observed in the reduction of the primary electron acceptor Q_a with E_m ≈ − 100 and ≈ − 330 mV. In isolated reaction centres only one step was observed in the reduction of Q_a with E ≈ −150 mV. Reconstitution of the reaction centres with additional menaquinone resulted in an increase in the Q_a EPR signal and reconstitution of the low-potential step in the oxidation-reduction titration. Reconstitution with ubiquinone resulted in the recovery of the secondary quinone Q_b. The addition of ubiquinone did not reconstitute the low-potential step of Q_a reduction, or affect the reconstitution of this step by menaquinone. It is concluded that menaquinone can bind to two sites on the reaction centre. Both have properties of the Q_a site but with different pK values. It is unlikely that either is the same as the Q_b site.     

Ultrastructural description of the life cycle of Nosema monorchis n. sp. (Microspora, Nosematidae), hyperparasite of Monorchis parvus (Digenea, Monorchiidae), intestinal parasite of Diplodus annularis (Pisces, Teleostei)

Life cycle stages of a new species of the genus Nosema Naegeli, 1857 (Microspora, Nosematidae), were examined by light and electron microscopy. It parasitizes the gut and the uterus of the digenean Monorchis parvus (Monorchiidae), in Diplodus annularis (Pisces, Teleostei). All stages were in close contact with the cytoplasm of the host cell and were probably all diplokaryotic. The divisions of meronts and sporonts were recognizable by the formation of spindle plaques at the surface of the nucleus. Spores were oval, measured 3.2±0.3×2.5±0.2 μm on ultrathin sections, and had a polar filament with 16–17 coils. The polaroplast presented two parts: an anterior region with closely packed lamellae and a posterior part with wider lamellae. This Nosema species is compared with the other microsporidian parasites of digeneans. This new species is named Nosema monorchis n. sp., after the generic name of its host.     

Trapping, loss and annihilation of excitations in a photosynthetic system: II. Experiments with the purple bacteria Rhodospirillum rubrum and Rhodopseudomonas capsulata

In this paper a number of experiments with the purple bacteria Rhodospirillum rubrum and Rhodopseudomonas capsulata is described in which the total fluorescence yield and/or the total fraction of reaction centers closed after a picosecond laser pulse were measured as a function of the pulse intensity. The conditions were such that the reaction centers were either all in the open or all in the closed state before the pulse arrived. These experiments are analysed using the theoretical formalism discussed in the preceding paper (Den Hollander, W.T.F., Bakker J.G.C., and Van Grondelle, R., Biochim. Biophys. Acta 725, 492–507). From the experimental results the number of connected photosynthetic units, λ, the rate of energy transfer between neighboring antenna molecules, k_h, and the rate of trapping by an open reaction center, k^o_t, can be estimated. For R. rubrum it is found that λ = 14−17, k_h = (1−2)·10¹² s⁻¹ and k^o_t = (4−6)·10¹¹ s⁻¹, for Rps. capsulata λ ≈ 30, k_h ≈ 4·10¹¹ s⁻¹ and k^o_t ≈ 3·10¹¹ s⁻¹. The findings are discussed in terms of current models for the structure of the antenna and the kinetic properties of the decay processes occurring in these purple bacteria.     

Factors affecting the growth characteristics of alginate-entrapped Chlorella

Previous studies have shown that growth of immobilized Chlorella emersonii is restricted to the periphery of calcium alginate gel beads. Results presented here show that CO₂, the growth-limiting factor, is responsible for this zonation. Light intensity (6–30 klx), though not saturating for photosynthesis, is not responsible for the effect. High concentrations of CO₂ (≈ 2%) were necessary to produce alginate beads containing high cell stocking densities without acute cell zonation. These findings are discussed in the context of other work on immobilized algal cells.     

On the embryology and mode of reproduction of selected diploid species of Hieracium s.l. (Asteraceae) from Bulgaria

Three diploid taxa – Hieracium transylvanicum (subgenus Hieracium), Hieracium caespitosum subsp. brevipilum and Hieracium pavichii (subgenus Pilosella) – from five natural Bulgarian populations were investigated embryologically. The peculiarities of the male and female gametophytes, embryo- and endospermogenesis were established in each species. The results suggest that the species propagate sexually as expected from their diploid chromosome number. However, some forms of apomixis have also been observed, e.g. somatic apospory and integumental embryony in H. pavichii. The presence of apomixis in a diploid taxon shows that polyploidy is not an obligatory prerequisite for apomixis and the two phenomena are independent. The embryological plasticity detected in H. pavichii and H. transylvanicum suggests they may have higher opportunities for adaptation and successful reproduction.     

The use of specific lysine modifications to locate the reaction site of cytochrome c with sulfite oxidase

The reduction of cytochrome c by beef liver sulfite oxidase was found to be strongly inhibited by high ionic strength, indicating the importance of electrostatic interactions to the reaction. The reaction rates of sulfite oxidase with singly trifluoroacetylated or trifluoromethylphenylcarbamylated cytochrome c derivatives were studied to determine the role of individual lysines in the reaction. The reaction rate was decreased by modification of the lysines immediately surrounding the heme crevice, the decreases following the order: Lys 13 > Lys 25 Lys 79 ≈ Lys 87 > Lys 8 ≈ Lys 27 ≈ Lys 72. Modification of lysines 22, 55, 88, 99, and 100 had no effect on the reaction rate. These results indicate that the interaction site on cytochrome c for sulfite oxidase is at the heme crevice region, and overlaps considerable with that for cytochrome oxidase.     

On the trophic fate of Phaeocystis pouchetii (Hariot). II. Grazing rates of Calanus hyperboreus (Krøyer) on diatoms and different size categories of Phaeocystis pouchetii

Experiments were conducted with CIV and C V copepodites of Calanus hyperboreus (Krøyer) to determine if they would feed on the prymnesiophyte Phaeocystis pouchetii (Hariot). We used analysis of gut pigment to estimate ingestion and clearance rates. In applying this methodology we have demonstrated that pigments can be completely extracted from whole animals within 90 min, and that laborious procedures of tissue homogenization and centrifugation are not required. We conducted two experiments. In the first experiment Stage IV copepodites were exposed to ≈1 mg C·1⁻¹ of either P. pouchetii flagellates, small colonies (25–200 μm), large colonies (> 200 μm) or mixed diatoms > 25 μm (primarily Chaetoceros socialis Lauder and Nitzschia grunowii Hasle). Ingestion rates and daily rations were almost four times greater on both sizes of colonies than on either Phaeocystis pouchetii flagellates or mixed diatoms. Daily rations of copepodites feeding on colonies ranged from 8.1 to 12.4% · day⁻¹, well within the range previously reported for Calanus hyperboreus or sympatric copepods of similar size. From the second experiment we determined that Stage V copepodites obtained a daily ration of 6.2 to 10.8% · day⁻¹ when feeding on small colonies of Phaeocystis pouchetii. We conclude that a diet of P. pouchetii colonies should sustain the metabolic and growth requirements of Calanus hyperboreus copepodites.     

Millardia meltada, a new host for Acanthocheilonema viteae and a simple technique for separation of microfilariae from peripheral blood

, and 1992. Millardia meltada, a new host for Acanthocheilonema viteae and a simple technique for separation of microfilariae from peripheral blood. International Journal for Parasitology 22: 1165–1168. Millardia meltada were infected with Acanthocheilonema viteae and examined for their susceptibility. The morbidity of infected M. meltada was low compared with that of jirds. On day 47 post-infection (p.i.), 13 of 14 M. meltada developed microfilaremia. Male M. meltada then showed gradually increasing microfilaremia with a peak level of 7000 per 30 μl blood at week 20 p.i., which was much higher than that (3000) of male jirds. In contrast, microfilarial densities of female M. meltada were markedly low with a peak level of 200 during weeks 10–12 p.i. A simple centrifugation technique with Lympholyte-M was devised for microfilarial separation from the peripheral blood of infected M. meltada and yielded approximately 17 × 10⁵ viable microfilariae from 1 ml of blood. This method also makes it possible to collect microfilariae from the same individuals repeatedly. M. meltada, coupled with this microfilarial separation technique, serves as a useful animal model for microfilarial studies of A. viteae.     

Respiration and nitrogen excretion of Polinices alderi (Forbes) and Polinices catena (da Costa) (Gastropoda : Naticidae)

Measurements were made of oxygen consumption and NH₃-N excretion, at different temperatures, for two species of gastropod molluscs, Polinices alderi (Forbes) and P. catena (da Costa), preying on bivalve molluscs. Previous observations, for P. alderi, that the rate of oxygen consumption is influenced by diet were confirmed. The effect of temperature on the rates of respiration and excretion was compared for the two species. Oxygen consumption was temperature dependent, with Q₁₀ values of ≈2, in the temperature range 10–20°C, for both species. NH₃-N excretion was relatively insensitive to temperature over the same range. The ratio of oxygen consumed to nitrogen excreted (O:N ratio) was relatively independent of size for both species, but was influenced by diet.     

The population dynamics of Orthopyxis crenata (Hartlaub, 1901) (Hydroza, Cnidaria), an epiphyte of Halimeda tuna in the northwestern Mediterranean

O. crenata on the alga Halimeda tuna were sampled every 2 wk for a year off Tossa de Mar, northeastern Spain. The hydroids were most abundant from November to April when three cohorts, identified by size frequency, were present. From April to October the population consisted of two cohorts, except in June and July when the population density was low and only one cohort, of young hydroids, was identifiable. The paucity of O. crenata in summer was attributed to the high rate of turnover of host thalli, interspecifuc competition with other epiphytes, and a possible shortage of suitable planktonic prey. Recruitment was predominantly asexual, by stolons, and occurred throughout the year. Gonozoids were found only from late October to early December when recruitment by planula larvae also occurred. In winter, when the cohorts lived for the maximum of ≈6 wk, colony sizes quintuplicated and triplicated in successive 15-day periods. Although colonies (ramets) of O. cretana on H. tuna have a short life span reproduction and dispersal to other thalli by stolons means that the genets can survive beyond the life of a host, and perhaps indefinitely.     

Effectiveness of Petasites hybridus preparations in the prophylaxis of migraine: A systematic review

The objective of this review was to evaluate the strength of evidence of effectiveness for Petasites hybridus in the prophylaxis of migraine. Several databases and other sources were searched to identify randomised-controlled trials investigating P. hybridus preparations. Two trials totalling 293 patients (60 and 233 patients) were included in this review. Both trials investigated the proprietary Petasites root extract Petadolex^®. The trials were described in narrative way, taking into consideration methodological quality scores. Pooling of data was not carried out due to the heterogeneity of the results. The extract at higher dose (150 mg) showed a greater decreased frequency of migraine attacks and a greater number of responders (improvement >50%) after treatment over 3–4 months than the extract at lower dose (100 mg) and placebo. Moderate evidence of effectiveness is, thus, available for a higher than the recommended dose of the proprietary Petasites root extract Petadolex^® in the prophylaxis of migraine. Further rigorous studies are required to confirm effectiveness and safety in long-term use before treatment with Petasites root extract can be recommended as an alternative option in the treatment schedule for the prophylaxis of migraine.     

Fragmentation in Madracis mirabilis (Duchassaing and Michelotti): how common is size-specific fragment survivorship in corals?

Fragmentation is an important asexual mode of reproduction for many coral species and other marine invertebrates. General life history theory and models of coral fragmentation predict that intra- and inter-specific variation in fragment size should be positively related to survival and inversely related to dispersal distance. To test these predictions I examined fragmentation in the Caribbean branching coral Madracis mirabilis, which produces relatively small fragments. The effects of intra-specific variation in fragment size on fragment survival and dispersal in M. mirabilis were examined by following the fate of 60 labeled fragments for 11 months at three sites. Fragment dispersal distance was limited (generally <20 cm), was not significantly related to fragment size, and varied among sites, being greatest at a shallow forereef site. Although the smallest fragments displayed the lowest survivorship (≈50%), there was no apparent increase in survivorship with size among larger fragments (i.e., those 5–15 cm in length), and there was no overall significant relationship between fragment size and survivorship. In contrast, fragment survivorship varied greatly among sites (29–81%), being the highest at two forereef sites (10 and 20 m depth) and lowest at a lagoon site with high sedimentation (10 m depth). Although natural fragments of M. mirabilis are smaller than almost any other known fragmenting coral species, they can have a high rate of survivorship in forereef environments. The results of this and other studies do not support the predicted general inter- and intra-specific relationships between fragment size and survivorship and suggest that fragment survivorship is highly context and species specific, and is also greatly influenced by factors other than fragment size.     

Early development and pathogenesis of Lobatostoma manteri Rohde (Trematoda: Aspidogastrea)

The prosobranch Planaxis sulcatus is reported as a new natural host of Lobatostoma manteri at Heron Island, Great Barrier Reef. Planaxis sulcatus and Cerithium moniliferum were experimentally infected with large numbers of eggs. The larvae hatch in the stomach and migrate immediately along the ducts of the digestive gland into the digestive follicles. The larvae feed on the secretion and probably epithelial cells of the follicles. The acetabulum is used for adhesion to the epithelium and contributes to its erosion. In heavily infected snails, the digestive follicles disappear gradually and the larvae live in cavities lined by a flattened epithelium, parts of which show secretory activity. In snails dissected 47–49 and 65–66 days after infection, the cavities are fused, forming several large spaces which communicate with each other; only small parts of the epithelium are still secretory. Concentrations of amoebocytes occur in the walls of the digestive gland and in the wall between digestive gland and stomach of infected Planaxis. Some young worms were found in the stomach of Planaxis. No tissue reactions were seen around the stomach except in the wall between digestive gland and stomach. In Cerithium with 65–67 days old infection, the cavities contain much detritus and disintegrating cells, the epithelium is practically non-secretory and surrounded by loose connective tissue. In larvae with a body length of approximately 0·5–0·6 mm, the acetabulum begins to divide into alveoli and its anterior end grows forward; the anterior alveoli gradually increase in size and new alveoli are formed in the posterior undivided zone. In two specimens of approximately 1·3 mm body length, the whole adhesive disk was divided into half the number of alveoli usually found in adults. Allometric shifts during growth of the worms are analysed.     

Antiviral property and mechanisms of a sulphated polysaccharide from the brown alga Sargassum patens against Herpes simplex virus type 1

A sulphated polysaccharide (SP-2a) from the brown alga Sargassum patens (Kütz.) Agardh (Sargassaceae) was found to significantly inhibit the in vitro replication of both the acyclovir (ACV)-sensitive and -resistant strains of Herpes simplex virus type 1 (HSV-1), in dose-dependent manners, with 50% inhibitions occurring with 1.5–5.3 μg/ml of the polysaccharide. SP-2a exhibited extracellular virucidal activity only against the ACV-sensitive strains, but not the resistant strain, at the concentration of 100 μg/ml. The strongest antiviral activities against the different strains of HSV-1 were observed when this polysaccharide was present during and after adsorption of the virus to host cells. The inhibitory effect of SP-2a on virus adsorption occurred dose-dependently in all the HSV-1 strains tested, and the adsorption of the ACV-resistant DM2.1 strain was reduced by 81.9% (relative to control) with 4 μg/ml of the polysaccharide. This study clearly demonstrated that the antiviral mode of action of SP-2a is mediated mainly by inhibiting virus attachment to host cells, and this sulphated polysaccharide might have different modes of action against the ACV-sensitive and -resistant strains of HSV-1.     

Sulfate reduction in lake sediments inhabited by the isoetid macrophytes Littorella uniflora and Isoetes lacustris

Sulfur cycling was examined in sediments inhabited with the isoetids Littorella uniflora and Isoetes lacustris in the oligotrophic soft-water Lake Kalgaard, Denmark. Based on short-term tracer incubations sulfate reduction was measured along a transect from the shore (0.6 m) to profundal sediments (4.6 m). The sulfate reduction rates were low (0.008–0.8 mmol m⁻² d⁻¹) in the sandy shallow sediments with low organic content (<1.3 mmol C g⁻¹ sed DW) and high redox potentials (>100 mV), whereas sulfate reduction was higher at the deeper sites (2.7–4.6 mmol m⁻² d⁻¹) with high organic content (max. 11.5 mmol C g⁻¹ sed DW) and lower redox potentials (<100 mV). High concentrations of dissolved organic carbon (DOC) were found in the low particulate organic sediments (up to 18.4 mM), and most of the DOC pool consisted of acetate (40–77%). Reoxidation of sulfides due to root oxygen release was probably important at all sites and a positive efflux of sulfate across the sediment–water interface was measured, attaining rates (up to 4.8 mmol m⁻² d⁻¹) similar to the sulfate reduction rates. Reoxidation of sulfides was also manifested by high fraction (>80%) of reduced sulfides being accumulated as elemental sulfur or pyrite (chromium reducible sulfur, CRS). The largest pools of CRS were found in high organic sediment with vertical distributions resembling those of the sulfate reduction rates. The overall effect of isoetid growth on sulfur cycling in the rhizosphere is a suppression of sulfate reduction in low organic sediments and the governing of sulfide reoxidation in sediments with higher organic content.     

The flagellates of the termite Hodotermopsis sjoestedti: Immunological and ultrastructural characterization of four new species in the genera Spirotrichonympha, Spironympha and Microjoenia

Four species of spirotrichonymphids representing three genera Spirotrichonympha, Spironympha and Microjoenia symbiotic in the termite Hodotermopsis sjoestedti, have been studied by light and immunofluorescence microscopy and transmission electron microscopy. The genus Spirotrichonympha represented by Spirotrichonympha cincta n. sp. is characterized by a compound axostyle composed of several fibers or subaxostyles, and this species has peculiar undescribed structures associated with the flagellar lines. The genus Spironympha is characterized by flagellar lines restricted to the anterior area and a simple tubular axostyle limited by 1–3 layers of microtubules. The two new Spironympha species Spironympha obtusa and Spironympha oblonga are distinguished by peculiarities in the flagellar lines and the axostyle, as revealed by immunofluorescence and electron microscopy. The genus Microjoenia represented by Microjoenia minuta n. sp. has radiating flagellar lines and an axostyle with two microtubular rows originating from the pelta-axostyle rows covering the anterior cap. Four new species were named and one was assigned to the SSU rRNA sequences provided by the molecular phylogenetic studies by Ohkuma et al. [2000. Phylogenetic identification of hypermastigotes, Pseudotrichonympha, Spirotrichonympha, Holomastigotes, and parabasalian symbionts in the hindgut of termites. J. Eukaryot. Microbiol. 47, 249–259; 2005. Molecular phylogeny of parabasalids inferred from small subunit rRNA sequences, with emphasis on the Hypermastigea. Mol. Phylogenet. Evol. 35, 646–655].     

Biotransformation of paeonol by Panax ginseng root and cell cultures

Panax ginseng root and cell cultures were shown to biotransform paeonol (1) into its 2-O-β-d-glucopyranoside (2). P. ginseng root cultures were also able to biotransform paeonol (1) into its 2-O-β-d-xylopyranoside (3), 2-O-β-d-glucopyranosyl(1 → 6)-β-d-glucopyranoside (4) and 2-O-β-d-xylopyranosyl(1 → 6)-β-d-glucopyranoside (5), and its demethylated derivate, 2′,4′-dihydroxyacetophenone (6). Compounds 3 and 4 are new glycosides. It is the first example that the administrated compound was converted into its xylopyranoside by plant biotransformation.