Heterochromatic marks are associated with the repression of secondary metabolism clusters in Aspergillus nidulans

Fungal secondary metabolites are important bioactive compounds but the conditions leading to expression of most of the putative secondary metabolism (SM) genes predicted by fungal genomics are unknown. Here we describe a novel mechanism involved in SM‐gene regulation based on the finding that, in Aspergillus nidulans, mutants lacking components involved in heterochromatin formation show de‐repression of genes involved in biosynthesis of sterigmatocystin (ST), penicillin and terrequinone A. During the active growth phase, the silent ST gene cluster is marked by histone H3 lysine 9 trimethylation and contains high levels of the heterochromatin protein‐1 (HepA). Upon growth arrest and activation of SM, HepA and trimethylated H3K9 levels decrease concomitantly with increasing levels of acetylated histone H3. SM‐specific chromatin modifications are restricted to genes located inside the ST cluster, and constitutive heterochromatic marks persist at loci immediately outside the cluster. LaeA, a global activator of SM clusters in fungi, counteracts the establishment of heterochromatic marks. Thus, one level of regulation of the A. nidulans ST cluster employs epigenetic control by H3K9 methylation and HepA binding to establish a repressive chromatin structure and LaeA is involved in reversal of this heterochromatic signature inside the cluster, but not in that of flanking genes.     

Coagulation factor XIII: A useful polymorphic genetic marker

Summary The plasmas of two groups of subjects were examined for blood coagulation Factor XIII-A (FXIII-A, F13A) by electrophoresis in agarose using a Tris-EDTA-borate buffer to separate the common variants, F13A^*1, F13A^*2, and F13A^*3. Dimeric subunits were visualized in UV light as monodansyl cadaverine bound to casein at the position of the transglutaminase activity representing F13A. One test group consisted of 307 members of three large Caucasian families. The other consisted of 148 consecutive patients whose plasmas had been sent to the clinical laboratory for determination of prothrombin time. Segregation analysis and father-to-son transmission confirmed that F13A is inherited as an autosomal co-dominant trait. The allelic frequencies in the random sample were F13A^*1=0.82 and F13A^*2=0.18. This sample included both blacks and whites, and the gene frequencies were not significantly different in the two races. The gene frequencies among the unrelated spouses of the three white families were A^*1=0.75, A^*2=0.24, A^*3=0.01. Genetic equilibrium was present in both groups.The degree of polymorphism, the availability of blood, the ease of assessment, the absence of selective pressure, and the uniformity of gene frequencies in two major American ethnic groups make F13A a very useful marker for linkage studies and paternity testing. F13A has been provisionally assigned to chromosome 6. Linkage analysis of our family data did not provide evidence of linkage to two chromosome 6 markers, properdin factor B (BF) and glyoxalase 1 (GLO). The highest lod score (Z) was between F13A and the Kidd (Jk) blood group (Z=0.68 at -0.24).     

Genes and people in the caspian littoral: A population genetic study in northern Iran

Data for the distribution of alleles controlling two blood group systems and secretor status, for hemoglobin types, five serum protein groups and 15 red cell enzyme systems has been obtained. Eleven of the systems showed polymorphic variation and these systems have been used to calculate genetic distances using Morton's Kinship measure. No systematic relationship between genetic distance and geographic location of linguistic affiliation is apparent. There is, however, an apparent cline of decreasing frequency of PGD^c from east to west and also significant differences in the frequency of G6PD deficiency corresponding to variation in the ecology of the region. Genetic distance comparisons with other selected populations reveal that the Turkic and Turkoman speaking peoples in the Caspian area cluster with the Kurds, Greeks and Iranis. The Persian speakers are genetically remote from these populations; they are, however, close to the Parsis who migrated from Iran to India at the end of the Seventh Century A.D. Several unusual genetic variants were detected, including a novel MDH pheno-type, a superoxide dismutase phenotype identical with the Scandinavian type, and rare forms of LDH, PGM locus 2, ceruloplasmin, diaphorase, peptidases and PHI.     

Effects of Hunting on Response Behaviors of Wild Reindeer

ABSTRACT Because wild reindeer (Rangifer tarandus) are hunted in southern Norway, reindeer may perceive all recreationists as threats. Potential adverse effects of hunting on reindeer behavior may be exacerbated by other forms of recreation because the number of skiers and hikers in areas inhabited by reindeer has also increased. The Norefjell-Reinsjøfjell wild reindeer area is used extensively for recreation and tourism. Reindeer hunting was introduced in the area in 1992, and harvest rate has been stable at about 38% of winter herd size. We recorded behavioral responses of reindeer to a person approaching directly on foot or skis during 1992 and again in 2002–2006. Compared to 1992, flight-initiation distance increased and fewer groups assessed the observer before taking flight during 2002–2006. In winter, when reindeer are usually comparably more vigilant than in other seasons, flight-initiation distance increased from only 60 m to 115 m and escape distance decreased from 400 m to 210 m. Neither alert distance, calf carcass weights (23.6 ± 0.7 [SE] kg to 22.4 ± 0.2 kg), nor reindeer herd size (661 ± 73 to 579 ± 15) changed during the 15 years of our study. Reindeer appeared to habituate to the observer because they initiated flight at shorter distances as the number of approaches on the same day increased. In Norefjell-Reinsjøfjell, encounters with a person on foot or skis did not result in behavioral responses likely to entail substantial energy costs for reindeer; therefore, hunting at current levels appears compatible with other recreational activities.     

The Simulium vernum group (Diptera: Simuliidae) in Europe: multiple character sets for assessing species status

The value of using characters from multiple sources – chromosomes, ecology, gene sequences, and morphology – to evaluate the species status of closely related black flies is demonstrated for three European members of the Simulium vernum group: Simulium crenobium (Knoz, 1961), Simulium juxtacrenobium Bass & Brockhouse, 1990, and Simulium vernum s.s. Macquart, 1826. Simulium juxtacrenobium is a chromosomally, molecularly, and morphologically distinct species that diverged from S. crenobium and S. vernum s.s. about 2 Mya. It is specialized for intermittent streams, is univoltine, and is recorded for the first time from northern Europe, based on collections from Finland and Sweden, representing a range extension of about 1800 km. In contrast, S. crenobium, although confirmed as a distinct species, differs from S. vernum s.s. by only a few larval and chromosomal characters, and by a breeding habitat restricted to mountain spring brooks. Whereas all four character sets independently support the specific distinctness of S. juxtacrenobium and S. vernum s.s., multiple character sets are required to establish the specific validity of S. crenobium.     

Structure, diversity, and evolution of the 45-bp VNTR in intron 5 of the USH1C gene

Usher syndrome type IC is a rare, autosomal recessive sensorineural disorder caused by mutations in the USH1C gene, which encodes a PDZ-domain protein named harmonin. The Acadian-specific 216G-->A mutation in exon 3 and a variant 9-repeat VNTR allele (designated VNTR(t,t)) in intron 5 are in complete linkage disequilibrium. (The usual form of the allele is referred to as VNTR(t).) To gain insight into the structure, diversity, and evolution of the VNTR, we analyzed individuals from seven different populations, as well as nonhuman primates and rodents. The 2-, 3-, and 6-repeat VNTR alleles were the most common. Four novel alleles containing 1, 5, 7, and 10 repeats were detected with frequencies of 0.002, 0.029, 0.005, and 0.001, respectively. The USH1C VNTR region is highly conserved among primates, but not between primates and rodents. Five unrelated individuals had a 3-repeat VNTR(t,t) allele. Haplotype analysis indicates that the 9-repeat VNTR(t,t) and the 3-repeat VNTR(t,t) alleles arose independently. However, the 9-repeat VNTR(t,t) and 6-repeat VNTR(t) alleles shared the same haplotype, suggesting an expansion from 6(t) to 9(t,t).     

Diet and population size structure of the Arctic shanny,Stichaeus punctatus (Pisces: Stichaeidae), at sites in eastern Newfoundland and the eastern Arctic

Synopsis The size structure and diet of the Arctic shanny,Stichaeus punctatus, were studied at two sites, one at Nuvuk Islands in the Arctic, and one at Newman Sound, in eastern Newfoundland. The Newfoundland population showed peaks corresponding to 0+,1+, and an accumulation of older individuals, while the Nuvuk population was dominated by 2+ and 3+ combined, and individuals aged 6+ and older. Epiphytic, harpacticoid copepods were the most important food items for the smaller Arctic shanny, but the importance of harpacticoid copepods decreased with increasing fish size. Harpacticoid copepods are thus a link between the macro-algae and the young stages of the Arctic shanny. Since Arctic shanny are the main food used by black guillemots to feed chicks, these copepods are also an indirect link between benthic algal production and these seabirds.     

Tightly linked flanking microsatellite markers for the Usher syndrome type I locus on the short arm of chromosome 11.

Usher syndrome type I is an autosomal recessive disease characterized by profound congenital hearing impairment and vestibular dysfunction followed by the onset of progressive pigmentary retinopathy in childhood or early adolescence. A locus (USH1C) for one form of this disease was previously assigned to the short arm of chromosome 11 through linkage studies in the Acadian population of southwestern Louisiana. Linkage analyses of a set of microsatellite markers in 27 Acadian families provide evidence that USH1C lies between D11S861 and D11S928. Three markers (D11S419, D11S921, and D11S899) that lie between the flanking markers show no recombination with USH1C, and all 54 chromosomes with the abnormal allele at the disease locus have identical alleles for D11S419 and D11S921. This haplotype was found on only 10 of 50 chromosomes with the normal allele at the disease locus, suggesting a strong founder effect. Of the 54 chromosomes with the abnormal allele, 12 had a divergent allele at D11S899. These results suggest that USH1C is in the 2-3-cM interval between D11S861 and D11S899.