Genetic relatedness of <Emphasis Type="Italic">Trichoderma</Emphasis> isolates antagonistic against <Emphasis Type="Italic">Fusarium oxysporum</Emphasis> f.sp. <Emphasis Type="Italic">dianthi</Emphasis> inflicting carnation wilt

Twenty-eight isolates of Trichoderma belonging to four different species were screened in vitro for their antagonistic ability against Fusarium oxysporum f.sp. dianthi causing carnation wilt. Three different levels of antagonism observed in dual plate assay were further confirmed by cell-free culture filtrate experiments. Isolates showing class I level of antagonism produced maximum lytic enzymes, chitinases and beta-1,3-glucanases. Genetic variability of 25 selected isolates was assessed by random amplified polymorphic DNA technique and the amplified products were correlated for their level of antagonism. Unweighed pair-group method with arithmetical averages cluster analysis revealed prominent inter-and intraspecific genetic variation among the isolates. Based on their genetic relationship, the isolates were mainly distributed into 3 major groups representing T. atroviride, T. pseudokoningii and T. harzianum, with 20-35% interspecific dissimilarity. However, the polymorphism shown by the isolates did not correlate to their level of antagonism.     

Seasonal distribution and dive behaviour of harp seals (<Emphasis Type="Italic">Pagophilus groenlandicus</Emphasis>) of the White Sea–Barents Sea stock

Eight adult female harp seals (Pagophilus groenlandicus) of the White Sea–Barents Sea stock were tagged with satellite-linked dive recorders during the nursing period and followed from breeding in late February 1995 until moulting in late April 1995. Another ten adult harp seals of both sexes were tagged and followed from moult in early May 1996 until breeding in late February the following year. Between breeding and moult the seals were distributed along the coasts of Kola of Russia and eastern Finnmark of Norway, coinciding in time and space with the spawning capelin (Mallotus villosus). Between moulting and breeding they encircled the entire Barents Sea, mostly in open water, using the water column from 20 to 300 m, and in so doing by and large reflecting the annual migrations of the capelin. Capelin is therefore assumed to be the main source of prey for the White Sea–Barents Sea stock of harp seals, to be substituted, in part, by amphipods (e.g. Themisto libellula) in mid-summer and polar cod (Boreogadus saida) and herring (Clupea pallasii) in late autumn and winter. These data provide a baseline for the evaluation of the effects of future climatic change in the rich Barents Sea ecosystem.     

The effect of crop rotation of six forest tree species on peat-bark substrate enzymatic activity

The paper focuses on the effect of a nine-year utilisation of the peat-bark substrate and crop rotation of six main forest tree species on changes in the substrate enzymatic activity during successive rotation cycles. The study was conducted in the forest nursery in the years 1989–1997. Seedlings of Scots pine Pinus sylvestris, Norway spruce Picea abies, European larch Larix decidua, pendiculate oak Quercus robur, common beech Fagus silvatica, and silver birch Betula overrucosa were grown on peat-bark substrate. The activity of soil enzymes: betaglucosidase, invertase, urease, asparginase, acid phosphatase and dehydrogenases was assessed. The succession of three 3-year crop rotation cycles with species following each other according to the rotation plan was subject to observations. The obtained results have confirmed recent suppositions that the tree species and their rotation modify soil enzymatic activity. The enzymatic activity of the peat-bark substrate changed after each three-year crop rotation cycle and decreased with time. After the second crop rotation cycle the activity of betaglucosidase, urease, asparginase was found to be lower, and the activity of invertase and dehydrogenases — higher. After three crop rotation cycles the positive effect of appropriate species rotation on the enzymatic activity of the substrate was noted.     

Vasa expression and germ-cell specification in the spider mite <Emphasis Type="Italic">Tetranychus urticae</Emphasis>

The specification of germ cells is an important process during the development of all animals. Expression of an evolutionarily conserved gene such as vasa can be used as a marker for germ cell fate. We have isolated a vasa-related gene from the two-spotted spider mite (Tetranychus urticae) and used it to examine the segregation of germ cells in this animal. In spider mites, vasa expression first appears in a group of cells that do not join the initial blastoderm surface. Instead, these cells remain in the interior of the blastoderm and then migrate to posterior regions of the embryo, where they form a cluster that appears in regions of the embryo consistent with the gonads. The expression pattern of this spider mite vasa homologue implies a novel process acts to specify germ cells in this species and that the specification of germ cells is an evolutionarily labile process.     

Expression and localization of human lysozyme in the endosperm of transgenic rice

In order to understand the characteristics of recombinant protein expression and sublocalization in rice ( Oryza sativa L.) endosperm, we examined the expression level of human lysozyme protein and its subcellular location in transgenic rice seeds driven by rice glutelin and globulin promoters and signal peptides. A time course of human lysozyme expression during endosperm development was analyzed. The results showed that the expression profile of recombinant protein accumulation in endosperm paralleled that of the two storage proteins. Immunofluorescence microscopy revealed that human lysozyme and storage proteins co-localized to type-II protein bodies. Both promoter-signal peptide parings targeted recombinant protein to the protein bodies. In addition, a transgenic line with a higher lysozyme expression level exhibited morphologically different protein bodies with an unbalanced composition of lysozyme and native storage proteins. The high-level expression of recombinant protein distorted the trafficking and sorting of native storage proteins in rice endosperm and affected the expression of native storage protein.     

Potential effects of physiological plastic responses to salinity on population networks of the estuarine crab <Emphasis Type="Italic">Chasmagnathus granulata</Emphasis>

Chasmagnathus granulata is a South American crab occurring in estuarine salt marshes of the Brazilian, Uruguayan and Argentine coasts. Life history is characterized by an export strategy of its larval stages. I reviewed information on experimental manipulation of salinity during embryonic and larval development (pre- and posthatching salinities), and on habitat characteristics of C. granulata in order to determine potential effects of larval response to salinity in the field and to suggest consequences for the population structure. Local populations are spread over coastal areas with different physical characteristics. Benthic phases occupy estuaries characterized by different patterns of salinity variation, and release larvae to coastal waters characterized by strong salinity gradients. The zoea 1 of C. granulata showed a strong acclimatory response to low salinity. This response operated only during the first weeks of development (during zoeae 1 and 2) since subsequent larval survival at low posthatching salinities was consistently low. Larvae developing at low salinity frequently followed a developmental pathway with five instead of four zoeal stages. The ability to acclimate and the variability in larval development (i.e. the existence of alternative developmental pathways) could be interpreted as a strategy to buffer environmental variability at spatial scales of local or population networks. Early survivorship and production of larvae may be relatively high across a rather wide range of variability in salinity (5–32‰). Plastic responses to low salinity would therefore contribute to maintain a certain degree of population connectivity and persistence regardless of habitat heterogeneity. Electronic Publication     

Nitric oxide signaling in yeast

As a cellular signaling molecule, nitric oxide (NO) is widely conserved from microorganisms, such as bacteria, yeasts, and fungi, to higher eukaryotes including plants and mammals. NO is mainly produced by NO synthase (NOS) or nitrite reductase (NIR) activity. There are several NO detoxification systems, including NO dioxygenase (NOD) and S-nitrosoglutathione reductase (GSNOR). NO homeostasis based on the balance between NO synthesis and degradation is important for the regulation of its physiological functions because an excess level of NO causes nitrosative stress due to the high reactivity of NO and NO-derived compounds. In yeast, NO may be involved in stress responses, but NO and its signaling have been poorly understood due to the lack of mammalian NOS orthologs in the genome. Even though the activities of NOS and NIR have been observed in yeast cells, the gene encoding NOS and the NO production mechanism catalyzed by NIR remain unclear. On the other hand, yeast cells employ NOD and GSNOR to maintain an intracellular redox balance following endogenous NO production, exogenous NO treatment, or environmental stresses. This article reviews NO metabolism (synthesis, degradation) and its regulation in yeast. The physiological roles of NO in yeast, including the oxidative stress response, are also discussed here. Such investigations into NO signaling are essential for understanding the NO-dependent genetic and physiological modulations. In addition to being responsible for the pathology and pharmacology of various degenerative diseases, NO signaling may be a potential target for the construction and engineering of industrial yeast strains.     

Large-scale production of foreign proteins via the novel plant transient expression system in <Emphasis Type="Italic">Pisum sativum</Emphasis> L.

Transient expression of foreign genes by Agrobacterium infiltration is a versatile technique that can be used as a rapid tool for functional protein production in plants. A reproducible protocol of large-scale production of foreign proteins via the novel plant transient expression system in Pisum sativum L. was established in our study. Non-detached plants from soil-independent culture were used as the target organ, and vacuum infiltrating mediated by Agrobacterium tumefaciens harboring green fluorescent protein (GFP) gene was performed. Step-by-step optimization was performed and showed that the quality of plant material as well as agro-infiltration conditions were the major factors influencing the gene expression. Monitoring the transient GFP expression daily, the highest expression level was achieved on the 8th day post-infiltration. Evidence of anti-acidic fibroblast growth factor-single chain variable fragment (anti-aFGF-scFv) gene expression in pea seedling was also achieved using agro-mediated vacuum infiltration system. Our work proves that the system is suitable for the largescale production of pharmaceutical proteins. The in planta infiltration system described here provides a powerful tool to explore easily gene expression in Pisum sativum L. avoiding tissue culture steps and the labor-intensive generation of transgenic plants.     

Seasonal and altitude effects on the structure of arthropod communities associated with <Emphasis Type="Italic">Tillandsia violacea</Emphasis> Baker (Bromeliaceae) in a temperate forest of Mexico

The canopy of forests has been considered “the last biotic frontier,” and study of its elements is very important in explaining the global functionality in ecosystems. Epiphytic plants and arthropods are essential elements in canopy habitats, and their relationships have been studied in order to understand the high diversity in tropical forests. Nevertheless, there are few studies on this development in temperate forests. The arthropod community was studied during the rainy and dry seasons at two altitudes, and a total of 240 T. violacea plants of three sizes were collected from Abies religiosa and Quercus spp. host trees. A total of 163,043 arthropods were collected and about 200 morphospecies identified. The highest abundance was obtained during the dry season, while high diversity was found during the rainy season. There was a significant effect of plant size, host trees and collecting season on abundance and diversity, and there were seasonal variations in community composition. The community hosted on A. religiosa epiphytes showed higher abundance and density than that of Quercus.     

Survey of <Emphasis Type="Italic">Alternaria</Emphasis> toxin contamination in food from the German market,using a rapid HPLC-MS/MS approach

A HPLC-MS/MS-based method for the quantification of nine mycotoxins produced by fungi of the genus Alternaria in various food matrices was developed. The method relies on a single-step extraction, followed by dilution of the raw extract and direct analysis. In combination with an analysis time per sample of 12 min, the sample preparation is cost-effective and easy to handle. The method covers alternariol (AOH), alternariol monomethyl ether (AME), tenuazonic acid (TeA), altenuene (ALT), iso-altenuene (isoALT), tentoxin (TEN), altertoxin-I (ATX-I), and the AAL toxins TA₁ and TA₂. Some Alternaria toxins which are either not commercially available or very expensive, namely AOH, AME, ALT, isoALT, and ATX-I, were isolated as reference compounds from fungal cultures. The method was extensively validated for tomato products, bakery products, sunflower seeds, fruit juices, and vegetable oils. AOH, AME, TeA, and TEN were found in quantifiable amounts and 92.1 % of all analyzed samples (n?=?96) showed low level contamination with one or more Alternaria toxins. Based on the obtained results, the average daily exposure to Alternaria toxins in Germany was calculated.