Regional distribution of microsomal xenobiotic and steroid metabolism in kidney microsomes from rainbow trout

The regional distribution of microsomal cytochrome P-450-mediated reactions with exogenous and endogenous substrates in the kidney of rainbow trout was studied. The cytochrome P-450-dependent 7-ethoxyresorufin- and 7-ethoxycoumarin-0-deethylase activities were significantly higher (3–4 and 10–14 fold, respectively) in the trunk kidney than in the head kidney, whereas ethylmorphine-N-demethylase activity was evenly distributed along the kidney. The microsomal cytochrome P-450-dependent steroid hydroxylases and steroid reducing enzymes when using androstenedione as substrate also exhibited a regional distribution in trout kidney. The 6β- and 16-hydroxylase activities as well as the 5α-reductase and 17 hydroxysteroid oxidoreductase activities were higher in the anterior part of the trunk kidney than in the head kidney and posterior trunk kidney.     

Understanding how built urban form influences biodiversity

This study seeks to contribute to a more complete understanding of how urban form influences biodiversity by investigating the effects of green area distribution and that of built form. We investigated breeding bird diversity in three types of housing development with approximately the same amount of tree cover. No significant differences in terms of bird communities were found between housing types in any of the survey periods. However, detached housing, especially with interspersed trees, had more neotropical insectivores and higher overall diversity of insectivores. Based on our results and theory we suggest a complementary approach to managing biodiversity in urban landscapes – instead of maximising the value and quality of individual patches efforts could go into enhancing over-all landscape quality at the neighbourhood scale by splitting up part of the green infrastructure. The relatively small differences in bird communities also suggest that different stakeholder groups may be engaged in management.     

Detection of quantitative trait loci in Pinus sylvestris L. across years

In an earlier study, we reported the characterisation of quantitative trait loci (QTLs) for economically important traits related to wood production for a specific year of measurement. However, validating the detected QTLs across years is important for any strategy for marker-assisted selection (MAS). Therefore, we evaluated the consistency of the QTLs across four years in 9 to 12 year-old trees. Data related to tree height were analysed in two ways. The total height was used to characterise QTLs likely to be useful in MAS, and the increment values to evaluate growth regulation. Among the 11 QTLs detected, 4 were found in both the 1996 and 1997 evaluations. QTL numbers and locations related to total height were found to be highly stable. However, the QTL effects progressively changed in successive years, following either an increasing, decreasing or curvilinear trend. Depending on their specific trends, some QTLs may not be expressed at all later in maturity, or they may be expressed at a higher level. This will have direct consequences on the applicability of molecular markers in early screening programs, since a study at the mature stage may also be required. More variation in QTL number and effect was observed relating to height increment than to total height, indicating significant differences in gene expression during the growth periods involved. This revised version was published online in August 2006 with corrections to the Cover Date.     

What is the evidence for sexual reproduction of Phytophthora infestans in Europe?

The biology of late blight of potato and tomato, caused by Phytophthora infestans, changed when sexual reproduction by the pathogen became possible in many parts of the world, including Europe. In northern Europe, especially Scandinavia, there is increasing evidence that the pathogen is reproducing sexually on a regular basis, although in other regions further south or to the west it appears to reproduce primarily in a clonal manner. The presence of both mating types, the production of viable oospores, and observations of fields with soilborne sources of inoculum are consistent with sexual reproduction. Studies with different marker systems have revealed a population structure without any dominating clonal lineages in Scandinavia, and that is most easily explained by sexual reproduction. Phytophthora infestans recovered from the soil can also be linked to parental genotypes using likelihood‐based methods when codominant markers are used. A synthesis of all the available data points to a second centre of sexual reproduction in northern Europe.     

Rheological characterisation of aqueous extracts of triticale grains and its relation to dietary fibre characteristics

Rheological properties of triticale extract are important determinants of the grain utility. Extracts of eight triticale cultivars and a wheat reference grown at two different locations i.e. Svalöv and Kölbäck were analysed for their viscoelastic properties. Extracts of triticale cultivars grown at Svalöv were significantly higher in elastic modulus (average 9.0 Pa), viscous modulus (average 12.7 Pa) and complex modulus (average 15.6 Pa) at 2.1 Hz than those grown at Kölbäck (average 3.1, 5.6 and 6.4 Pa, respectively). However phase angle was not affected by location, and all triticale extracts had phase angle >45°. Large inter-cultivar variation was also observed in viscoelastic properties of triticale extracts. Some of the triticale cultivars grown at Kölbäck (Dinaro, Cando, Talentro, and DED 145/02) and Svalöv (DED 145/02) were similar to wheat in their complex modulus values. When evaluating the contribution of arabinoxylan (AX) and β-glucan to rheological properties of triticale extracts by partial least square (PLS) regression, it was evident that β-glucan had little role and most of the contribution to viscoelastic properties came from AX. AX fine structure was more important in explaining variation in complex modulus of triticale extract than content and extractability, or molecular size.     

A heat-sensitive TRP channel expressed in keratinocytes

Mechanical and thermal cues stimulate a specialized group of sensory neurons that terminate in the skin. Three members of the transient receptor potential (TRP) family of channels are expressed in subsets of these neurons and are activated at distinct physiological temperatures. Here, we describe the cloning and characterization of a novel thermosensitive TRP channel. TRPV3 has a unique threshold: It is activated at innocuous (warm) temperatures and shows an increased response at noxious temperatures. TRPV3 is specifically expressed in keratinocytes; hence, skin cells are capable of detecting heat via molecules similar to those in heat-sensing neurons.     

Lack of trophic polymorphism despite substantial genetic differentiation in sympatric brown trout (Salmo trutta) populations

Sympatric populations occur in many freshwater fish species; such populations are typically detected through morphological distinctions that are often coupled to food niche and genetic separations. In salmonids, trophic and genetically separate sympatric populations have been reported in landlocked Arctic char, whitefish and brown trout. In Arctic char and brown trout rare cases of sympatric, genetically distinct populations have been detected based on genetic data alone, with no apparent morphological differences, that is “cryptic” structuring. It remains unknown whether such cryptic, sympatric structuring can be coupled to food niche separation. Here, we perform an extensive screening for trophic divergence of two genetically divergent, seemingly cryptic, sympatric brown trout populations documented to remain in stable sympatry over several decades in two interconnected, tiny mountain lakes in a nature reserve in central Sweden. We investigate body shape, body length, gill raker metrics, breeding status and diet (stomach content analysis and stable isotopes) in these populations. We find small significant differences for body shape, body size and breeding status, and no evidence of food niche separation between these two populations. In contrast, fish in the two lakes differed in body shape, diet, and nitrogen and carbon isotope signatures despite no genetic difference between lakes. These genetically divergent populations apparently coexist using the same food resources and showing the same adaptive plasticity to the local food niches of the two separate lakes. Such observations have not been reported previously but may be more common than recognised as genetic screenings are necessary to detect the structures.