Distribution and strain-dependent formation of volatile metabolites in the genus Ceratocystis

The accumulation of volatile metabolites in cultures of 34 strains comprising ten species of the genus Ceratocystis (Ascomycetes) has been investigated under defined culture conditions. The identified compounds include short-chain alcohols and esters, lower terpenes, terpenoids, and 2-phenylethyl acetate. Certain species can be recognized by a number of common volatiles traced in all strains, although the quantities of these constituents may vary enormously (up to a factor 1:1000) within one species. The formation of some metabolites is restricted to a few strains.     

The macrobenthos of the pristine stream, Skiftesåa, Høylandet, Norway

The species composition of aquatic insects in theboreal stream, Skiftesåa, was investigated usingemergence traps, Malaise traps and kick samples. Atleast 13 Ephemeroptera, 16 Plecoptera, 25 Trichopteraand 120 Chironomidae species were recorded. This faunais representative for non-polluted, northern streams.The production of macrobenthos was estimated to beonly about 1 g dry weight per year and m²,possibly due to the fluctuating flow of water.     

Sesquiterpene hydrocarbons from Lentinus lepideus

Several sesquiterpene hydrocarbons, mainly of the cadinane skeleton, have been identified in cultures of the brown rot fungus Lentinus lepideus. The main compounds are δ-cadinene, α- and γ-muurolene.     

Parental Nutrition and Chick Production in Captive Willow Ptarmigan (Lagopus L. Lagopus)

The breeding performance of captive willow ptarmigan on different diets has been studied. The nutritional factors tested were protein concentration, natural feed supplement and grass meal and flavonoid admixture, and effects on egg numbers, fertility, hatchability, chick weights at hatching and 0–14 days mortality have been recorded. The breeding performance of ptarmigan hen in captivity showed great individual variations. Egg numbers were not statistically different in groups fed the different diets. Hens fed a 15 % crude protein died tended to produce smaller chicks with significantly lower viability than chicks from hens fed a 20 % crude protein diet. Supplement of natural feed tended to increase the number of chicks hatched through a combination of tendency to higher egg numbers and improved fertility. These tendencies were, however, statistically nonsignificant. Inclusion of 34 % grass meal to the diet also tended (non-significantly) to improve fertility and hatchability, while inclusion of flavonoids had no positive effect on reproduction. Eggs from captive hens showed significantly lower fertility, and a tendency to lower hatchability than eggs from wild hens. The former difference was probably caused by the close cage confinements for the captive ptarmigan, while the latter condition probably was due to different start of incubation, most of the eggs from wild hens being started naturally.     

Preference for linking element -en- in Dutch noun-noun compounds: native speakers and second language learners of Dutch

In Dutch, variation occurs in the formation of noun-noun compound words. Some compounds always add the linking element -en- between the two nouns; some compounds never use such a linking element; and still others allow both options. The element -en- is homophonous with the regular plural ending in Dutch, and we therefore investigated if plural semantics creates a preference for the linking element -en- in novel Dutch noun-noun compounds. We also investigated if the preference for linking -en- is influenced by just meaning (i.e., a semantic plural), form (i.e., a formal plural), or perhaps both. The influence of native language on preferences for Dutch compounds was also investigated. In study 1, we tested native speakers of Dutch; in study 2, Frisian-Dutch bilinguals; and, in study 3, speakers of German with Dutch as a second language. Plurality played a role in the preferences for Dutch compound formation in all tested groups. For native speakers of Dutch, Frisian, and German, moreover, the preference for a linking element in novel Dutch compounds was influenced by both the semantic plural and the formal plural. However, these effects were smaller for the native speakers of German. These findings confirm the findings of earlier studies (e.g. Schreuder et al. in Language and Cognitive Processes 13(5):551–573, 1998) showing linking -en- to carry an intrinsic plural meaning. Kiparsky’s level-ordering hypothesis (Linguistics in the morning calm, pp. 3–91, 1982) and Pinker’s words-and-rules theory (Words and rules: the ingredients of language, 1999) are re-considered in light of the present findings.     

Origin, taxonomy and population structure of the allopolyploid peat mossSphagnum majus

The polyploid peat mossSphagnum majus shows considerable phenotypic plasticity along ecological gradients in mires. It is considered taxonomically heterogeneous, and two subspecies have been described. Isozyme analyses were carried out on populations ofS. majus from Central Norway and from eastern coast of North America in order to assess the origin, taxonomy and population structure of this species. High levels of fixed heterozygosity in the populations demonstrate thatS. majus is a genetic allopolyploid. At all loci screened, extant populations ofS. cuspidatum shared enzyme bands withS. majus. The other most likely progenitor based on morphology,S. annulatum, was fixed for enzyme bands not found inS. majus. The progenitor genotype ofS. annulatum may have been missed because of inadequate sampling or extinction. Alternatively, another extinct or undetected taxon may constitute the second progenitor. The observed patterns of genetic variation and linkage disequilibria were uncorrelated with the previously proposed subspecific classification ofS. majus. Lack of genetic divergence between continents suggests that the origins ofS. majus in Europe and North America were not independent. Low mutation rates and large effective population sizes may be important causing populations to diverge slowly, and may explain the observed patterns without hypothesising frequent long-distance dispersal.     

Atomic force microscopy and modeling of natural elastic fibrillin polymers

A central issue in the understanding of Marfan syndrome deals with the functional architecture of fibrillin-containing microfibrils. Fibrillin-rich microfibrils are long extracellular matrix fibrillar components exhibiting a 50 nm periodic beaded-structure with a width of around 20–25 nm after rotary shadowing and a 10–12 nm diameter when observed in ultra-thin sections. They are composed of fibrillin monomers more or less associated with many other components which are, for the most part, poorly characterized up to date. They are known to be elastic but few data have been accumulated to understand their properties. Atomic force microscopy (AFM) allowed us to morphologically differentiate fibrillin-rich microfibrils from other fibrillar components and to investigate the thin structure of these beaded filaments in their native state. They showed, in AFM, a periodic beaded structure ranging from 50 to 60 nm and a width of about 40 nm. The different sizes of fibrillin-containing microfibrils previously observed after rotary shadowing and in ultra-thin sections was resolved with our technique and is revealed to be 10 nm in diameter. Each beaded microfibril appears to be composed of heterogeneous beads connected by 2–3 arms. An orientation of the microfibrils has been shown, and allows us to propose a complementary model of microfibrillar monomer association.     

LTBP-2 specifically interacts with the amino-terminal region of fibrillin-1 and competes with LTBP-1 for binding to this microfibrillar protein.

LTBP-2 is a matrix protein of unknown function since, unlike other LTBPs, it does not form covalent complexes with latent TGF-beta. We have previously shown that LTBP-2 has widespread association with fibrillin-containing microfibrils in developing aorta and other tissues. We have now shown that full-length human recombinant LTBP-2 specifically binds to the amino-terminal region of fibrillin-1, but not to fibrillin-2, in solid phase assays and overlay blotting. The binding was enhanced by the inclusion of 2 mM Ca2+ ions in the assay buffer and abolished by 5 mM EDTA indicating that the interaction was directly or indirectly Ca2+ ion dependent. The K(d) for the interaction was calculated from the specific binding curve as 9.4 nM. A recombinant carboxyl-terminal fragment of LTBP-2 was shown to a) bind the amino-terminal fragment of fibrillin-1 and b) block completely the binding of full length LTBP-2 to fibrillin-1. This result indicates that the major fibrillin-1 binding site resides close to the carboxyl-terminus of LTBP-2. Further competitive binding studies showed that an analogous carboxyl terminal fragment of LTBP-1 was able to block the binding of LTBP-2 to fibrillin-1 and that the C-terminal fragment of LTBP-2 could block the interaction of the LTBP-1 fragment with the fibrillin. Thus the binding site for LTBP-2 on fibrillin-1 appears to be the same or in close proximity to that for LTBP-1. Immunohistochemical analysis of developing human aorta showed distinctive but extensively overlapping distributions for LTBPs-1 and -2. Both LTBPs showed extensive co-localization with fibrillin-1 and elastic lamellae but LTBP-2 had extensive signal throughout the medial layer whereas LTBP-1 showed strong localization only in the outer medial layer. The finding indicates that there is a possibility for LTBP-2 to compete with LTBP-1 for binding to fibrillin-containing microfibrils throughout the aortic wall but particularly in the outer medial region where the LTBP-1 is predominantly located. Overall, the results support the concept that that LTBP-2 may be an indirect negative modulator for storage of the large latent TGF-beta complex on microfibrils in aorta and other fibrillin-rich tissues.