6-Bromohypaphorine from Marine Nudibranch Mollusk Hermissenda crassicornis is an Agonist of Human α7 Nicotinic Acetylcholine Receptor

6-Bromohypaphorine (6-BHP) has been isolated from the marine sponges Pachymatisma johnstoni, Aplysina sp., and the tunicate Aplidium conicum, but data on its biological activity were not available. For the nudibranch mollusk Hermissenda crassicornis no endogenous compounds were known, and here we describe the isolation of 6-BHP from this mollusk and its effects on different nicotinic acetylcholine receptors (nAChR). Two-electrode voltage-clamp experiments on the chimeric α7 nAChR (built of chicken α7 ligand-binding and glycine receptor transmembrane domains) or on rat α4β2 nAChR expressed in Xenopus oocytes revealed no action of 6-BHP. However, in radioligand analysis, 6-BHP competed with radioiodinated α-bungarotoxin for binding to human α7 nAChR expressed in GH₄C₁ cells (IC₅₀ 23 ± 1 μM), but showed no competition on muscle-type nAChR from Torpedo californica. In Ca²⁺-imaging experiments on the human α7 nAChR expressed in the Neuro2a cells, 6-BHP in the presence of PNU120596 behaved as an agonist (EC₅₀ ~80 μM). To the best of our knowledge, 6-BHP is the first low-molecular weight compound from marine source which is an agonist of the nAChR subtype. This may have physiological importance because H. crassicornis, with its simple and tractable nervous system, is a convenient model system for studying the learning and memory processes.     

鱼肉与大豆蛋白复合挤压组织化特性研究

以鱼肉、大豆蛋白为主要原料,通过双螺杆挤压技术将其内部结构进行重新组合。在确定原料比例的基础上,依次研究了物料含水率、喂料速度、螺杆转速及机筒的四区温度对产品组织化程度的影响,并采用Box-Behnken中心组合试验对这些变量进行了分析,得出最佳挤压条件为:物料含水率30%、进料速度35 r/min、螺杆转速175 r/min、挤压机五区温度90℃→100℃→110℃→145℃→110℃时,在这种条件下挤出物的组织化程度可达到2.12。     

Near‐surface paleosols in coastal sands at the outlet of Hadera stream (Israel) in the light of archeology and luminescence chronology

Catenary changes, archeology, micromorphology, and magnetic mineralogy of paleosols in coastal sands, Israel, were investigated under chronostratigraphic control by available luminescence datings from adjacent sites. At the outlet of Hadera stream, eolianites (Hebrew: “kurkar”) underlie paleosols with Epipaleolithic (approx. 17–20 ky) artifacts at the top and occasional Mousterian (>40 ky) artifacts in the subsoil. The optically stimulated–luminescence/infrared stimulated–luminescence (OSL/IRSL) dates (>50–12 ky) from adjacent sites roughly agree with the archeological findings. The paleosols show a magnetically depleted Vertisol superimposed on a magnetically enhanced cumulative Chromic Luvisol (WRB) (USDA: Rhodoxeralf, Israeli class.: Hamra). The latter contain approx. 0.25 mm thick, isotropic clay infillings distinctly separated from the soil matrix. These infillings are tentatively interpreted as the result of strong environmental disturbances, such as surface desiccation, subsequent waterlogging, and enhanced dust deposition, presumably at the time of the Last Glacial Maximum. In addition to the massive accumulation of eolian dust, diverse pedogeomorphic changes lagging in time from the onset of climatic deterioration may have taken place in coastal settings. Recurrent desiccation cracks may have exposed subsurface materials repeatedly to sunlight, consequently resetting the luminescence signal. The eolianite sequences are thus distinct from loess/paleosol sequences from temperate climates and have to be treated more rigorously at a site‐specific level.     

Sperm cryopreservation in the Far‐Eastern wildcat (Prionailurus bengalensis euptilurus)

The Far‐Eastern wildcat (Prionailurus bengalensis euptilurus) is a rare and poorly investigated nondomestic felid species. An attempt of freezing and cryopreserving Far‐Eastern wildcat spermatozoa in CaniPlus Freeze (CPF) medium is reported. Sperm was collected by electroejaculation from five adult Far‐Eastern wildcat captive‐born males. Epididymal spermatozoa from five adult randomly bred domestic cat males were used as a reference. The viability of frozen–thawed spermatozoa evaluated by double staining with SYBR Green I and PI followed by the subsequent confocal laser scanning microscopy (CLSM) was 38.2% ± 3.0% for the domestic cat and 38.0% ± 10.2% for the Far‐Eastern wildcat. The motility of frozen–thawed spermatozoa was 30.8% ± 9.8% for the domestic cat and 33.7% ± 15.1% for the Far‐Eastern wildcat. Sperm morphology was assessed by light microscopy. The total percentage of normal spermatozoa after freezing and thawing was 51.9 ± 5.9 for the domestic cat and 55.0% ± 6.4% for the Far‐Eastern wildcat. Defects of flagella were the most frequently observed abnormalities in both species (32.2% ± 4.8% and 30.8% ± 4.4% of all reported anomalies for the domestic cat and Far‐Eastern wildcat, respectively). Domestic cat epididymal and Far‐Eastern ejaculatory spermatozoa fertilized in vitro‐matured oocytes of the domestic cat (30.0% ± 5.5% and 35.5% ± 15.0%, respectively). Taken together, these results suggest that the freezing of Far‐Eastern wildcat spermatozoa with CPF medium is a suitable method for Felidae cryopreservation.     

Endoparasites of the Siberian tiger (Panthera tigris altaica)

There have been few reports on the diversity and prevalence of parasitic fauna of the endangered Siberian tiger, which inhabits the territory of the Russian Far East. The present review attempts to summarize the information about the parasitic fauna of wild Siberian tigers, which includes 15 helminths and 3 protozoan species. The most prevalent parasitic species was found to be Toxocara cati, followed by Toxascaris leonina. Another commonly recorded Platyhelminth species is Paragonimus westermani, which causes a lethal infection of the lung parenchyma in Siberian tigers. However, the information about infections by this fluke in the Siberian tigers is scarce, although P. westermani infections pose a serious health hazard to tiger populations. The nematodes Aelurostrongylus abstrusus and Thominx aerophilus are found in Siberian tigers with an occurrence rate of 2.3% and 19%, respectively. The information on the parasitic infestations of captive populations of Siberian tigers is also presented along with the sources of infection and hazards for the wild tiger populations in their natural environment.     

Marine Natural Products Acting on the Acetylcholine-Binding Protein and Nicotinic Receptors: From Computer Modeling to Binding Studies and Electrophysiology

For a small library of natural products from marine sponges and ascidians, in silico docking to the Lymnaea stagnalis acetylcholine-binding protein (AChBP), a model for the ligand-binding domains of nicotinic acetylcholine receptors (nAChRs), was carried out and the possibility of complex formation was revealed. It was further experimentally confirmed via competition with radioiodinated α-bungarotoxin ([¹²⁵I]-αBgt) for binding to AChBP of the majority of analyzed compounds. Alkaloids pibocin, varacin and makaluvamines С and G had relatively high affinities (K_i 0.5–1.3 μM). With the muscle-type nAChR from Torpedo californica ray and human neuronal α7 nAChR, heterologously expressed in the GH₄C₁ cell line, no competition with [¹²⁵I]-αBgt was detected in four compounds, while the rest showed an inhibition. Makaluvamines (K_i ~ 1.5 μM) were the most active compounds, but only makaluvamine G and crambescidine 359 revealed a weak selectivity towards muscle-type nAChR. Rhizochalin, aglycone of rhizochalin, pibocin, makaluvamine G, monanchocidin, crambescidine 359 and aaptamine showed inhibitory activities in electrophysiology experiments on the mouse muscle and human α7 nAChRs, expressed in Xenopus laevis oocytes. Thus, our results confirm the utility of the modeling studies on AChBPs in a search for natural compounds with cholinergic activity and demonstrate the presence of the latter in the analyzed marine biological sources.     

Model of apparent and real priming effects: Linking microbial activity with soil organic matter decomposition

The most frequently used models simulating soil organic matter (SOM) dynamics are based on first-order kinetics. These models fail to describe and predict such interactions as priming effects (PEs), which are short-term changes in SOM decomposition induced by easily available C or N sources. We hypothesized that if decomposition rate depends not only on size of the SOM pool, but also on microbial biomass and its activity, then PE can be simulated. A simple model that included these interactions and that consisted of three C pools - SOM, microbial biomass, and easily available C - was developed. The model was parameterized and evaluated using results of ¹²C-CO₂ and ¹⁴C-CO₂ efflux after adding ¹⁴C-labeled glucose to a loamy Haplic Luvisol. Experimentally measured PE, i.e., changes in SOM decomposition induced by glucose, was compared with simulated PE. The best agreement between measured and simulated CO₂ efflux was achieved by considering both the total amount of microbial biomass and its activity. Because it separately described microbial turnover and SOM decomposition, the model successfully simulated apparent and real PE.The proposed PE model was compared with three alternative approaches with similar complexity but lacking interactions between the pools and neglecting the activity of microbial biomass. The comparison showed that proposed new model best described typical PE dynamics in which the first peak of apparent PE lasted for 1 day and the subsequent real PE gradually increased during 60 days. This sequential decomposition scheme of the new model, with immediate microbial consumption only of soluble substrate, was superior to the parallel decomposition scheme with simultaneous microbial consumption of two substrates with different decomposability. Incorporating microbial activity function in the model improved the fit of simulation results with experimental data, by providing the flexibility necessary to properly describe PE dynamics. We conclude that microbial biomass should be considered in models of C and N dynamics in soil not only as a pool but also as an active driver of C and N turnover.     

Production of somatic hybrids between S. tuberosum L. and late blight resistant Mexican wild potato species

Interspecific somatic hybrids between dihaploid breeding clones of potato, S. tuberosum and two accessions of wild Mexican species S. pinnatisectum and the hybrid line S. pinnatisectum × S. bulbocastanum were regenerated following electrofusion of mesophyll protoplasts to combine important agricultural traits of S. tuberosum and a high level of late blight resistance from selected wild accessions. In two fusion combinations 239 calli were regenerated; 162 from 195 calli analysed were identified as hybrids by means of isozyme analysis of peroxidases and, for some hybrid clones, by RAPD analysis. Depending on the fusion combination, 47–89 percent of the somatic hybrids had the expected ploidy level and 7–16 percent were mixoploids. Somatic hybrids were phenotypically intermediate as compared to their parents and some of them were able to be backcrossed sexually with potato. Fertility and crossability depended on combination and ploidy level of the somatic hybrids. In tests with detached leaves the wild partner clones had a high late blight resistance score of 8,6 and 8,9; the susceptible tuberosum-partners of 2,8 and 3,5, respectively. Nearly 25 percent of somatic hybrids had a resistance level of 6 or higher in the first year of assessment. The average resistance value of most somatic hybrids was lower than the average parental level. The reasons for variation in resistance values are discussed in connection with the practical application of fusion hybrids. This revised version was published online in July 2006 with corrections to the Cover Date.