Comparison of different methods of census of juvenile salmonids (Salmonidae) in the small river Mikocheva (Western Kamchatka)

Seinings of the lowland bed of a typical small river of Western Kamchatka demonstrated that of several methods for the census of juveniles of salmonids (Salmonidae) the most accurate result in comparison with complete removal is obtained by three-fold seining with calculation of abundance by the Zippin method. In comparison with a seine, a drive-in trap and electrofishing possess a lower average catching efficiency and a higher selectivity. The average density of fish estimated by the results of seining at the investigated stretch was 0.55–0.57 specimens/m².     

Consumption of aquatic subsidies by soil invertebrates in coastal ecosystems

Routes of aquatic allochthonous inputs (aquatic subsidies) to detrital food webs are studied, as is the effect of aquatic subsidies on the functional and taxonomic structure of soil invertebrate communities in coastal ecosystems. The study took place in the coastal zone of an oxbow lake of the Pra River in the Oka Reserve. The results indicate a strong dependence of soil animals in the coastal habitats on aquatic subsidies. Isotopic analysis shows that aquatic resources enter soil food webs not only via predators feeding on flying insects or aquatic prey, but also via saprophages decomposing organic debris of aquatic origin. The contribution of aquatic subsidies to the energy balance of soil invertebrates decreases rapidly with increasing distance from the lake. The fraction of aquatic carbon in tissues of collembolans and saprophages is negligible already a few meters from the water edge. The dependence of predatory invertebrates on aquatic resources can be traced at somewhat greater distance (tens of meters).     

Plant-growth regulators from common starfish (<Emphasis Type="Italic">Asterias amurensis</Emphasis> Lütken) waste

Starfish waste has been shown to be an effective compost material not only in the promotion of plant growth but also in terms of having insecticidal activity. In the present study, plant growth regulation by chemicals from starfish was examined. The aqueous fraction from a hot water extract of the starfish Asterias amurensis Lütken showed plant-growth activity, while the aqueous fraction from a methanol extract inhibited growth of Brassica campestris. The lipophilic fraction from the methanol extract also exhibited a plant growth-promoting effect. The active components from each extract were identified. Asterubine from the hot water extract promoted plant growth. A ceramide from the lipophilic fraction showed root growth promoting effect, and three glucocerebrosides had promotive effects on the entire plant. Asterosaponins were identified as the main growth inhibitors in the aqueous fraction of the methanol extract. These active compounds from starfish waste could be analyzed as potential plant growth regulators in agricultural applications in the future.     

Heliothrix oregonensis,gen. nov., sp. nov., a phototrophic filamentous gliding bacterium containing bacteriochlorophyll a

An unusual filamentous, gliding bacterium was found in a few hot springs in Oregon where it formed a nearly unispecific top layer of microbial mats. It contained a bacteriochlorophyll a-like pigment and an abundance of carotenoids. There were no chlorosomes or additional chlorophylls. The organism was aerotolerant and appeared to be photoheterotrophic. It was successfully co-cultured with an aerobic chemoheterotroph in a medium containing glucose and casamino acids. Although it has many characteristics in common with the genus Chloroflexus, the lack of chlorosomes and bacteriochlorophyll c and the aerobic nature of this organism indicate that it should be placed in a new genus. This conclusion is supported by 5S rRNA nucleotide sequence data.     

Inositol 1,4,5-trisphosphate (IP3) induced rapid formation of thromboxane B2 in saponin-permeabilised human platelets: mechanism of IP3 action

The mechanism of IP3-induced activation of saponin-permeabilised platelets has been examined. Saponin permeabilization resulted in the leakage of low-Mr substances into and from the cells without loss of cytoplasmic proteins. Addition of IP3 rapidly induced a dose-related formation of thromboxane B2 and release into the medium, leading to the responses of shape change, aggregation and [14C]5HT release. These responses were inhibited by the thromboxane A2 receptor antagonist AH23848. The IP3-induced release of 45Ca from intracellular stores was not affected by indomethacin. Synthesis of thromboxane was inhibited if Ca2+ elevation was prevented by using Ca-EGTA buffers during permeabilization. These studies indicate that IP3-induced activation was due to Ca2+ mobilisation leading to phospholipase activation and thromboxane synthesis.