Biosynthesis of dehydroaltenusin by talaromyces flavus

A new metabolite, identical with dehydroaltenusin was isolated from a strain Talaromyces flavus B 5 which was selected from parental strain 51 C/I. Metabolite inhibited the growth of wooddamaging fungi, especially Ciadosporium sphaerospermum and P388 leukemid cells.     

The antibiotic PSX-1 Produced byPennicilium stipitatum is identical with botryodiplodin

Antibiotic PSX-1 exhibiting antitumour activity, formerly isolated from the filtrate of a culture of Penicillium stipitatum, was shown to be identical with botryodiplodin.     

Eine Studie über die Genese und Funktion des Interstitiums auf Grund der Untersuchungen an senescenten Hoden

Ohne Zusammenfassung     

A restricted polyhedral rearrangement of an aminosubstituted 12-vertex ferratricarbollide

The oxidation of anion [7,8-CH₂OCH₂-7,8-C₂B₉H₁₀]⁻ with aqueous FeCl₃ gives the 10-vertex nido-carborane 5,6-CH₂OCH₂-5,6-C₂B₈H₁₀ in 23% yield. Its interaction with Bu^tNC in the presence of proton sponge gives the tricarbollide anion [7,8-CH₂OCH₂-9-Bu^tNH-7,8,9-C₃B₈H₈]⁻ (44% yield) having a short linkage between carbon atoms. Further photochemical reaction of this anion with [CpFe(C₆H₆)]⁺ is accompanied by room-temperature polyhedral rearrangement giving ferratricarbollide 1-Cp-2,3-CH₂OCH₂-9-Bu^tNH-1,2,3,9-FeC₃B₈H₈ (5) in 89% yield. The process involves the migration of the amino-substituted carbon atom, while the separation of two other carbons (observed for the non-linked analogue) is restricted by the CH₂OCH₂ bridge. DFT calculations of the hypothetical non-rearranged isomer 1-Cp-2-Bu^tNH-1,2,3,4-FeC₃B₈H₁₀ revealed its strongly distorted geometry with the C2-C3 distance (2.347 Å) being clearly non-bonding, thus explaining the mild conditions of the polyhedral rearrangement. The structure of 5 was confirmed by X-ray diffraction.     

How do population genetic parameters affect germination of the heterocarpic species Atriplex tatarica (Amaranthaceae)?

Background and Aims

The heterocarpic species Atriplex tatarica produces two types of seeds. In this study, how basic population genetic parameters correlate with seed germinability under various experimental conditions was tested.

Methods

Population genetic diversity was ascertained in eight populations of A. tatarica by assessing patterns of variation at nine allozyme loci. Germinability of both seed types from all sampled populations was determined by a common laboratory experiment under different salinity levels. Basic population genetic parameters, i.e. percentage of polymorphic loci, average number of alleles per locus and observed heterozygosity were correlated with observed population germination characteristics.

Key Results

Atriplex tatarica possesses a remarkable heterocarpy, i.e. one type of seed is non-dormant and the other shows different dormancy levels in relation to experimental conditions. Significant negative correlations have been detected between germination of both seed types and the coefficient of inbreeding, and a significant negative correlation between germination of dormant seeds and other population genetic parameters, i.e. percentage of polymorphic loci and average number of alleles per polymorphic locus. Moreover, populations from the region characterized by a shorter growing season manifested higher germinability, i.e. had lower dormancy, than those from the lower-latitude one.

Conclusions

In general, germination of non-dormant seeds is probably not under strong genetic control. Hence, they germinate as soon as conditions are favourable, thus ensuring survival in the short term, but populations risk local extinction if conditions become adverse (i.e. a high-risk strategy). In contrast, germination of the dormant type of seeds is under stronger genetic control and is significantly correlated with basic population genetic parameters. These seeds ensure long-term reproduction and survival in the field by protracted germination, albeit in low quantities (i.e. A. tatarica also adopts a low-risk strategy).Key words: Amaranthaceae, Atriplex, inbreeding depression, population genetics, seed dimorphism     

2-Methylsorbic acid,an antifungal metabolite of Penicillium vermiculatum

Summary 2-Methylsorbic acid (MA), (2Z,4E)-2-methyl-2,4-hexadienoic acid, is a new metabolite of Penicillium vermiculatum. Antifungal activity of this acid was higher than that of sorbic acid or the bromoderivatives bromomethylsorbic acid and bromosorbic acid. MA suppressed the growth of Talaromyces flavus and germination of its conidia. In P. vermiculatum this acid lowered production of vermiculin and inhibited proteosynthesis in Saccharomyces cerevisiae. Correspondence to: B. Proksa     

Some non-anomerically C-C-linked carbohydrate amino acids related to leucine-synthesis and structure determination

(5'R)-5'-Isobutyl-5'-[methyl (4R)-2,3-O-isopropylidene-beta-L-erythrofuranosid-4-C-yl]-imidazolidin-2',4'-dione was synthesised starting from methyl 2,3-O-isopropylidene-alpha-D-lyxo-pentodialdo-1,4-furanoside via methyl 6-deoxy-6-isopropyl-2,3-O-isopropylidene-alpha-D-lyxo-hexofuranosid-5-ulose applying the Bucherer-Bergs reaction. Its 5'-R configuration was confirmed by X-ray crystallography. Corresponding alpha-amino acid-methyl (5R)-5-amino-5-C-carboxy-5,6-dideoxy-6-isopropyl-alpha-D-lyxo-hexofuranoside (alternative name: 2-[methyl (4R)-beta-L-erythrofuranosid-4-C-yl]-D-leucine) was obtained from the above hydantoin by acid hydrolysis of the isopropylidene group followed by basic hydrolysis of the hydantoin ring. Analogous derivatives with 5S configuration, formed in a minority, were also isolated and characterised.     

Czech alien flora and the historical pattern of its formation: what came first to Central Europe?

Temporal patterns of immigration to the country were analysed using 668 alien species in the flora of the Czech Republic for which the dates of the first record were available (64.8% of the total number of 1031 so-called neophytes, i.e. aliens introduced after the year 1500). After a period of initial slow increase lasting to the 1840s, the accumulation of neophytes over time could be best fitted by a linear model that explained 97% of the variance. The intensity of floristic research, which varied between periods, did not significantly affect the overall increase in the number of aliens. The effect of species traits on the year of introduction was evaluated, with continent of origin, introduction type (deliberate or accidental), life history, Grime's life strategy, onset of flowering, mode of dispersal and propagule size as explanatory variables. Species of European origin and CSR strategists arrived earlier than those with other origins and strategies. Deliberately introduced species appeared earlier than accidental arrivals, and those cultivated for utilitary reasons on average arrived earlier than ornamentals. Species capable of early flowering were remarkably more prevalent among early newcomers. A separate analysis of accidentally introduced American species also identified life history as a significant predictor of immigration time, with annuals being introduced earlier than biennials and perennials. The data contribute to an understanding of a crucial stage of the invasion process that has received little attention in the literature. The model "early alien" to Central Europe is a European species with a CSR strategy deliberately brought for cultivation as a utilitary plant. Once it escaped from cultivation, its establishment in the wild was favoured by its ability to flower early and, therefore, complete the life cycle.