Effect of Putative Deoxyribonucleic Acid Inhibitors on Macromolecular Synthesis in Saccharomyces cerevisiae

The effects of inhibitors of bacterial deoxyribonucleic acid (DNA) synthesis upon logarithmically growing cultures of Saccharomyces cerevisiae were investigated. Cell division, ribonucleic acid (RNA) synthesis, and DNA synthesis were measured after addition of nalidixic acid, fluorodeoxyuridine, or phenethyl alcohol to cultures of yeast growing in defined and complex media. Both nalidixic acid and fluorodeoxyuridine had only temporary effects on nucleic acid synthesis in cultures growing in defined medium, and little or no observable effect on cultures growing in complex medium. Neither compound inhibited colony formation on complex solid medium, although growth was slow on defined solid medium. Phenethyl alcohol caused complete inhibition of DNA synthesis, RNA synthesis, and cell division in cultures growing in defined medium. In cultures growing in complex medium, RNA synthesis and cell division were inhibited to a lesser extent. A slight increase in DNA was observed in the presence of the inhibitor.     

Endosomal vacuoles of the prepupal salivary glands of Drosophila play an essential role in the metabolic reallocation of iron

In the recent past, we demonstrated that a great deal is going on in the salivary glands of Drosophila in the interval after they release their glycoprotein‐rich secretory glue during pupariation. The early‐to‐mid prepupal salivary glands undergo extensive endocytosis with widespread vacuolation of the cytoplasm followed by massive apocrine secretion. Here, we describe additional novel properties of these endosomes. The use of vital pH‐sensitive probes provided confirmatory evidence that these endosomes have acidic contents and that there are two types of endocytosis seen in the prepupal glands. The salivary glands simultaneously generate mildly acidic, small, basally‐derived endosomes and strongly acidic, large and apical endosomes. Staining of the large vacuoles with vital acidic probes is possible only after there is ambipolar fusion of both basal and apical endosomes, since only basally‐derived endosomes can bring fluorescent probes into the vesicular system. We obtained multiple lines of evidence that the small basally‐derived endosomes are chiefly involved in the uptake of dietary Fe³⁺ iron. The fusion of basal endosomes with the larger and strongly acidic apical endosomes appears to facilitate optimal conditions for ferrireductase activity inside the vacuoles to release metabolic Fe²⁺ iron. While iron was not detectable directly due to limited staining sensitivity, we found increasing fluorescence of the glutathione‐sensitive probe CellTracker Blue CMAC in large vacuoles, which appeared to depend on the amount of iron released by ferrireductase. Moreover, heterologous fluorescently‐labeled mammalian iron‐bound transferrin is actively taken up, providing direct evidence for active iron uptake by basal endocytosis. In addition, we serendipitously found that small (basal) endosomes were uniquely recognized by PNA lectin, whereas large (apical) vacuoles bound DBA lectin.     

Butterflies of European islands: the implications of the geography and ecology of rarity and endemicity for conservation

Depending on their faunal content islands can function as important ‘vehicles’ for conservation. In this study, we examine data on 440 butterfly species over 564 European islands in 10 island groups. To determine the status of the butterfly fauna, we have adopted two approaches, island-focused and species-focused, examined using principal components analysis and regression modelling. In the former, we relate species richness, rarity and endemicity to island geography (area, elevation, isolation and location in latitude and longitude); in the latter, species occurrence on islands is examined in relation to distribution, range, range boundaries, and altitudinal limits on the continent as well as species’ ecology (number of host plants) and morphology (wing expanse). Species on islands are also assessed for their status on the continental mainland, their distributional dynamics (extinctions, distribution changes) and conservation status (Red Data Book, European Habitat Directive, Species of European Conservation Concern and Bern Convention listing. Unexpectedly, we find that a large fraction of the European butterfly species is found on the islands (63.4%; 59% on small islands) comprising some 6.2% of the land area of Europe. Although species occurring on the islands tend, on the whole, to have lower conservation status and are not declining over Europe, 45 species are endemics restricted to the islands. Species richness shows only a weak locational pattern and is related as expected to isolation from the continental source and island area; but, both rarity and endemicity have distinctive geographical bias to southern Europe, on islands now under increasing pressure from climate change and increasingly intensive human exploitation. The vulnerability of species on islands is emphasised in the relationship of island occurrence (% occurrence and presence/absence of species on any island) with continental distributions. A large proportion of the variation (84%) is accounted by continental distribution, the southern range limit and lower altitudinal limit. Most species (69%) occur on very few islands (<5%). In view of ongoing species dynamics on islands, migrations and extinctions of species, island repositories of species depend in large part on conservation of butterflies at continental sources. The unique faunas and rare species on islands also depend on appropriate concern being given to the island faunas. Conservation of European islands is thus a two-way process, sustaining sources and conserving island refuges. Residuals from the regressions (islands with more or fewer species, rare and endemic species; species occurring more or less frequently than expected on islands) provide warning signals of regions and islands deserving immediate attention.     

Genetic and physical mapping of a high recombination region on chromosome 7H(1) in barley

Approaches utilizing microlinearity between related species allow for the identification of syntenous regions and orthologous genes. Within the barley Chromosome 7H(1) is a region of high recombination flanked by molecular markers cMWG703 and MWG836. We present the constructed physical contigs linked to molecular markers across this region using bacterial artificial chromosomes (BAC) from the cultivar Morex. Barley expressed sequence tags (EST), identified by homology to rice chromosome 6 between the rice molecular markers C425A and S1434, corresponded to the barley syntenous region of Chromosome 7H(1) Bins 2–5 between molecular markers cMWG703-MWG836. Two hundred and thirteen ESTs were genetically mapped yielding 267 loci of which 101 were within the target high recombination region while 166 loci mapped elsewhere. The 101 loci were joined by 43 other genetic markers resulting in a highly saturated genetic map. In order to develop a physical map of the region, ESTs and all other molecular markers were used to identify Morex BAC clones. Seventy-four BAC contigs were formed containing 2–102 clones each with an average of 19 and a median of 13 BAC clones per contig. Comparison of the BAC contigs, generated here, with the Barley Physical Mapping Database contigs, resulted in additional overlaps and a reduction of the contig number to 56. Within cMWG703-MWG836 are 24 agriculturally important traits including the seedling spot blotch resistance locus, Rcs5. Genetic and physical analysis of this region and comparison to rice indicated an inversion distal of the Rcs5 locus. Three BAC clone contigs spanning the Rcs5 locus were identified. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Comparison of carbonate C and O stable isotope records across the Jurassic/Cretaceous boundary in the Tethyan and Boreal Realms

Carbon and oxygen stable isotope records were compared for Jurassic/Cretaceous (J/K) boundary sections located in the Tethyan Realm (Brodno, Western Slovakia, and Puerto Escaño, Southern Spain; bulk limestones), and the Boreal Realm (Nordvik Peninsula, Northern Siberia, belemnites). Since a detailed biostratigraphic correlation of these Tethyan and Boreal sections is impossible due to different faunal assemblages, correlation of the isotope records was based on paleomagnetic data. This novel approach can improve our understanding of the synchroneity of individual isotope excursions in sections where detailed biostratigraphic correlation is impossible. No significant excursions in either the carbon or oxygen isotope records to be used for future Boreal/Tethyan correlations were found around the J/K boundary (the upper Tithonian and lower Berriasian; magnetozones M20n to M18n) in the studied sections. At the Nordvik section, where a much longer section (middle Oxfordian–basal Boreal Berriasian) was documented, the transition from the middle Oxfordian to the Kimmeridgian and further to the Volgian is characterized by a decrease in belemnite δ¹⁸O values (from δ¹⁸O values up to + 1.6‰ vs. V-PDB in the Oxfordian to values between + 0.3 and ? 0.8‰ in the late Volgian and earliest Boreal Berriasian). This trend, which has previously been reported from the Russian Platform and Tethyan Realm sections, corresponds either to gradual warming or a decrease in seawater δ¹⁸O. Supposing that the oxygen isotope compositions of seawater in the Arctic/Boreal and Tethyan Realms were similar, then the differences between oxygen isotope datasets for these records indicate differences in temperature. The Boreal/Tethyan temperature difference of 7–9 °C in the middle and late Oxfordian decreases towards the J/K boundary, indicating a significant decrease in latitudinal climatic gradients during the Late Jurassic. Two positive carbon isotope excursions recorded for the middle Oxfordian and upper Kimmeridgian in the Nordvik section can be correlated with a similar excursion described earlier for the Russian Platform. Minor influence of biofractionation at the carbon isotopes, and the influence of migration of belemnites to deeper, slightly cooler water at the oxygen isotopes, cannot be excluded for the obtained belemnite data.     

Curcuma pygmaea sp. nov. (Zingiberaceae) from Vietnam and notes on two related species C. parviflora and C. thorelii.

Curcuma pygmaea?korni?k. & ?ída f. (Zingiberaceae), a new species from Vietnam, is described and illustrated. Notes on its closest allies in Curcuma subgenus Hitcheniopsis, C. parviflora Wall. and C. thorelii Gagnep., are provided and a lectotype of C. thorelii is designated.     

Bioactive compounds in sweet rowanberry fruits of interspecific Rowan crosses

Sweet rowanberries originated by the crossbreeding of wild rowanberries with other fruit species such as apples, medlars or black chokeberries. They are highly resistant to cold climate. In contrast with wild rowanberries, they have sweet mild taste and show less parasorbic acid toxicity, which can be eliminated, when the consumption is excessive, by heating. The objective of the work was to determine selected antioxidant properties in 6 cultivars. The analyses showed that the contents of total phenolics, total flavonoids and ascorbic acid were high. Similarly, antioxidant capacity (6.58–9.62 g of ascorbic acid equivalents kg^?1) was also high. The work brings novel data, in particular, when comparing the cultivars; moreover, results regarding reactive oxygen and nitrogen species scavenging activity in sweet rowanberries are being published for the first time. The sweet rowanberry extracts (10%) showed inhibitory ability on hydroxyl radical (16.12–24.73%), superoxide anion (26.74–34.02%), nitric oxide (24.75–31.39%), and lipid peroxidation (7.93–13.12%). The values obtained are even many times higher than those found in common commercial fruit species like apples. Therefore, sweet rowanberries appear to be a promising fruit species for human nutrition, especially due to their high content of bioactive substances and ease of cultivation in worse climatic and soil conditions.     

Does function follow form? Principal QTLs for Fusarium head blight (FHB) resistance are coincident with QTLs for inflorescence traits and plant height in a doubled-haploid population of barley

Fusarium head blight (FHB), an important disease of barley in many areas of the world, causes losses in grain yield and quality. Deoxynivalenol (DON) mycotoxin residues, produced by the primary pathogen Fusarium graminearum, pose potential health risks. Barley producers may not be able to profitably market FHB-infected barley, even though it has a low DON level. Three types of FHB resistance have been described in wheat: Type I (penetration), Type II (spread), and Type III (mycotoxin degradation). We describe putative measures of these three types of resistance in barley. In wheat, the three resistance mechanisms show quantitative inheritance. Accordingly, to study FHB resistance in barley, we used quantitative trait locus (QTL) mapping to determine the number, genome location, and effects of QTLs associated with Type-I and -II resistance and the concentration of DON in the grain. We also mapped QTLs for plant height, heading date, and morphological attributes of the inflorescence (seeds per inflorescence, inflorescence density, and lateral floret size). QTL analyses were based on a mapping population of F₁-derived doubled-haploid (DH) lines from the cross of the two-rowed genotypes Gobernadora and CMB643, a linkage map constructed with RFLP marker loci, and field evaluations of the three types of FHB resistance performed in China, Mexico, and two environments in North Dakota, USA. Resistance QTLs were detected in six of the seven linkage groups. Alternate favorable alleles were found at the same loci when different inoculation techniques were used to measure Type-I resistance. The largest-effect resistance QTL (for Type-II resistance) was mapped in the centromeric region of chromosome 2. All but two of the resistance QTLs coincided with QTLs determining morphological attributes of the inflorescence and/or plant height. Additional experiments are needed to determine if these coincident QTLs are due to linkage or pleiotropy and to more clearly define the biological basis of the FHB resistance QTLs. Plant architecture should be considered in FHB resistance breeding efforts, particularly those directed at resistance QTL introgression and/or pyramiding. Received: 22 November 1998 / Accepted: 2 June 1999     

Association of the NAD(P)H-bispecific nitrate reductase structural gene with the Nar7 locus in barley.

The NADH-specific and NAD(P)H-bispecific nitrate reductase genes from barley have been cloned and sequenced. To determine if the Nar7 locus encodes the NAD(P)H-bispecific nitrate reductase structural gene, a cross was made between a wild-type cultivar, Morex (Nar7 Nar7), and Az70 (nar7w nar7w), a mutant from the cultivar Steptoe that is deficient in NAD(P)H-bispecific nitrate reductase activity. A probe specific to the NAD(P)H-bispecific nitrate reductase structural gene detected restriction fragment length polymorphism between the parents. This probe was used to classify selected F2 progeny for restriction fragment length genotype. All the NAD(P)H nitrate reductase deficient F2 progeny (24/101) possessed the Az70 restriction fragment genotype. The absence of recombination between the NAD(P)H-bispecific nitrate reductase deficient genotype and the NAD(P)H-bispecific nitrate reductase restriction fragment length genotype indicates that the two traits are closely associated in inheritance and that Nar7 is probably the NAD(P)H-bispecific nitrate reductase structural gene.     

Cell migration and cortisone induction of sucrase activity in jejunum and ileum

The increase of sucrase activity in homogenates of jejunum and ileum of suckling rats after cortisone administration has been investigated. Serial tissue sections of villi and crypts were also assayed for sucrase activity and these results were compared with the migration of cells labelled with [(3)H]thymidine along the villus. By using a low dose of cortisone (0.5mg/day per 100g body wt.) it was found that the sensitivity of the small intestine producing system to cortisone stimulation increased during the suckling period. On the other hand, 5mg of cortisone/day per 100g body wt. produced practically the same increase of sucrase during the entire suckling period. Sucrase activity in homogenates of the entire small-intestinal wall was first detected 24h after the first injection of cortisone (5mg/day per 100g body weight) to 9-day-old animals and maximum activity both in the jejunum and ileum was reached by 120h. Jejunal activity was greater than ileal activity, but the rate of the increase was similar. The half-time of the increase was 23-27h, whereas enterocytes migrate from the base to the tip of the villi in approximately 72h. Comparison of sucrase activity in serial tissue sections of villi and crypts at various times after cortisone treatment showed that the leading edge of sucrase activity proceeds toward the tip of the villi at the same rate as the advancing edge of newly formed cells. Sucrase activity increased in the newly induced cells as they migrated to the tip of the villi. It was concluded that the increase of sucrase activity in suckling rats after cortisone stimulation is due to at least three factors: (1) increase of activity in newly differentiating cells, (2) increased percentage of villus cells with sucrase activity and (3) continued production or activation of sucrase activity as the cells migrate along the villi.