Influence of environmental factors and individual traits on the diet of non-native hybrid bigheaded carp (Hypophthalmichthys molitrix × H. nobilis) in Lake Balaton,Hungary

Planktivorous silver carp and bighead carp (collectively, the bigheaded carps) have been stocked worldwide and their invasion has caused severe impacts on many freshwater ecosystems. Exploiting the chance provided by the specific hybrid bigheaded carp stock in Lake Balaton (Hungary) covering the entire morphological range between the two species (including gill raker morphology), we implemented a comprehensive study (1) to reveal the feeding habits of hybrid bigheaded carps living in a mesotrophic, lacustrine habitat and (2) to assess how biotic and abiotic environmental factors and gill raker morphology affect diet composition. We found that all bigheaded carps utilized primarily zooplankton and neglected the scarce and inefficiently digestible phytoplankton, irrespective of gill raker morphology. Moreover, we observed strikingly high levels of inorganic debris consumption, but the proportion of inorganic matter in the guts was not associated directly with the concentration of suspended inorganic particles. Variance in the diet composition of bigheaded carps was related mostly to environmental factors, including the wind-induced resuspension of inorganic particles and seasonally variable availability of food resources. In conclusion, the effects of abiotic environmental factors and available food resources could overwhelm the effect of gill raker morphology in shaping the feeding habits of bigheaded carps.

     

Biolistic transformation of animal tissue

Summary The biolistic technique transforms cells by bombardment with DNA-coated microprojectiles. It has been used to transform plants, microbes, and organelles. We adapted a standard Biolistic PDS-1000 device for use with animals and have successfully transformed tissues in live mice. The firefly luciferase gene was introduced into mouse skin and ear tissue. One day after transformation 344±74 and 1648±254 pg of luciferase were detected in skin and ear samples, respectively. Expression of the gene product was transient but detectable up to 7 days after bombardment. A further modification of the device allowed transient transformation of liver tissue in vivo. Liver contained 293±122 pg of luciferase 1 day postransformation. Expression of the gene in liver tissue was unchanged at Day 3 but declined to low levels by Day 5. This new device allowed a fourfold increase in gene expression in ear tissue extending a minimum of 14 days. This technology is applicable to a broad range of tissues and organs in situ and makes it possible to test numerous reporters and the tissue specificity of promoters. It may also be useful in protocols for somatic cell therapy. Presented in the Session-in-Depth Genetic Transformation and Genetic Analysis Using Microprojectile Bombardment at the 41st Annual Meeting of the Tissue Culture Association, Houston, Texas, June 10–13, 1990.     

Oxidation products of terpenes identified from Dendroctonus and Ips bark beetles

Exposure of adult males and females of Dendroctonus brevicomis and D. frontalis to camphene vapor resulted in oxidation of the terpene to a prominent product, which was identified as 6-hydroxy-camphene (camphenol). Exposure of D. brevicomis adults to myrcene vapor resulted in sex-specific oxidation of the hydrocarbon. A major product in both sexes was identified as 2-methyl-6-methylene-2,7-octadien-1-ol (myrcenol), whereas ipsdienol, a major product in males, was not detected in females. A compound detected in hindguts of feeding males of Ips pini and I. paraconfusus was attributed to the presence of 3-carene in the host (Pinus spp.) and subsequently identified as 1-methyl-5-(α-hydroxy-isopropyl)-cyclohexa-1,3-diene.     

LPS-activated complement, not LPS per se, triggers the early release of PGE2 by Kupffer cells

The intravenous injection of LPS rapidly evokes fever. We have hypothesized that its onset is mediated by prostaglandin (PG)E(2) quickly released by Kupffer cells (Kc). LPS, however, does not stimulate PGE(2) production by Kc as rapidly as it induces fever; but complement (C) activated by LPS could be the exciting agent. To test this hypothesis, we injected LPS (2 or 8 microg/kg) or cobra venom factor (CVF, an immediate activator of the C cascade that depletes its substrate, ultimately causing hypocomplementemia; 25 U/animal) into the portal vein of anesthetized guinea pigs and measured the appearance of PGE(2), TNF-alpha, IL-1beta, and IL-6 in the inferior vena cava (IVC) over the following 60 min. LPS (at both doses) and CVF induced similar rises in PGE(2) within the first 5 min after treatment; the rises in PGE(2) due to CVF returned to control in 15 min, whereas PGE(2) rises due to LPS increased further, then stabilized. LPS given 3 h after CVF to the same animals also elevated PGE(2), but after a 30- to 45-min delay. CVF per se did not alter basal PGE(2) and cytokine levels and their responses to LPS. These in vivo effects were substantiated by the in vitro responses of primary Kc from guinea pigs to C (0.116 U/ml) and LPS (200 ng/ml). These results indicate that LPS-activated C rather than LPS itself triggers the early release of PGE(2) by Kc.     

Comparison of protein patterns of Streptomyces griseus spores from surface and submerged cultures

Protein patterns of conidia produced by a Streptomyces griseus strain in submerged cultures and on solid media were compared. Cell-free extracts (30 000 X g supernatant) were prepared and analyzed on gradient SDS polyacrylamide gels. The protein patterns of both kinds of conidia were found to be practically identical, and they differed from protein patterns of the old vegetative hyphae in a characteristic way.     

Structural Changes in Radish Seedlings Exposed to Cadmium

Radish (Raphanus sativus L. cv. Redondo Vermelho) seedlings were analysed by light and scanning electron microscopy to characterize the structural changes caused by the exposure to 0.5 or 1.0 mM cadmium chloride for 24, 48 and 72 h. The analyses showed changes in the anatomical and morphological characteristics of roots, stems and leaves of two-week-old seedlings. In all tissues, pressure potential was decreased. Premature death with the disintegration of the epidermis and an increase in the number of root hairs was observed in roots exposed to Cd. The stem of seedlings exposed to Cd exhibited more cells layers in the cambial region. The main effects observed in leaves in response to Cd were stomatal closure, lack of cell wall thickening and alterations in the shape of the chloroplasts. It is suggested that the structural changes observed in seedlings treated with Cd were mainly caused by a Cd-induced decrease in water uptake.     

Population Genetic Patterns of Threatened European Mudminnow (Umbra krameri Walbaum, 1792) in a Fragmented Landscape: Implications for Conservation Management

The European mudminnow (Umbra krameri) is a Middle Danubian endemic fish species, which is characterised by isolated populations living mainly in artificial habitats in the centre of its range, in the Carpathian Basin. For their long term preservation, reliable information is needed about the structure of stocks and the level of isolation. The recent distribution pattern, and the population genetic structure within and among regions were investigated to designate the Evolutionary Significant, Conservation and Management Units (ESUs, CUs, MUs) and to explore the conservation biological value of the shrinking populations. In total, eight microsatellite loci were studied in 404 specimens originating from eight regions. The results revealed a pronounced population structure, where strictly limited gene flow was detected among regions, as well as various strengths of connections within regions. Following the results of hierarchical structure analyses, two ESUs were supposed in the Carpathian Basin, corresponding to the Danube and Tisza catchments. Our results recommend designating the borders of CUs in an 80–90km range and 16 clusters should be set up as MUs for the 33 investigated populations. How these genetic findings can be used to better allocate conservation resources for the long term maintenance of the metapopulation structure of this threathened endemic fish is discussed.     

Mating Type Gene (MAT1-2) of Trichophyton verrucosum

Trichophyton verrucosum is a zoophilic dermatophyte species that is the most frequent etiologic agent of bovine dermatophytosis throughout the world. Since no teleomorph of T. verrucosum has been found, polymerase chain reaction (PCR) analysis on the genome of T. verrucosum isolated from the Czech Republic and Japan was performed to confirm the presence of a mating type locus in the genome of the fungus and to clarify its classification and ecological characteristics. The mating type gene (MAT1-2) allele was detected by PCR analysis in all 22 isolates (four isolates from the Czech Republic and 18 isolates from Japan). The nucleotide sequence of the region exhibited 99–100 % identity among all isolates, including the reference strain of T. verrucosum. Phylogenetic analysis revealed that the sequences of the internal transcribed spacer region at the MAT1-2 locus clustered together in the isolates examined, forming a branch distinct from that of the other dermatophyte species. These results suggest that T. verrucosum is a clonal offshoot that has drifted away from Arthroderma benhamiae.