The microbiological transformation of some ent-kaur-16-ene 7-, 15- and 18-alcohols by Gibberella fujikuroi

The effect of the 7-, 15- and 18-hydroxyl groups on the microbiological transformation of some diterpenoids by Gibberella fujikuroi has been studied. An 18-substituent appears to exert an inhibitory effect on transformations involving reaction at the 6β opposition.     

Triterpene-based plant defenses

Pentacyclic triterpenes are abundant in the plant kingdom and have a wide array of pharmacological activities. They also have insect antifeedant effects and therefore apparently play a role in plant defense. In this paper, we describe the insecticidal activity of pentacyclic triterpenes of plant origin from different chemical classes on several insect pests (Spodoptera littoralis, Leptinotarsa decemlineata and Myzus persicae), their phytotoxic properties and their selective cytotoxic effects on insect-derived Sf9 and mammalian CHO cells. We also discuss the role they play in plant defense based on these activities.     

A Minimal Optical Trapping and Imaging Microscopy System

We report the construction and testing of a simple and versatile optical trapping apparatus, suitable for visualizing individual microtubules (∼25 nm in diameter) and performing single-molecule studies, using a minimal set of components. This design is based on a conventional, inverted microscope, operating under plain bright field illumination. A single laser beam enables standard optical trapping and the measurement of molecular displacements and forces, whereas digital image processing affords real-time sample visualization with reduced noise and enhanced contrast. We have tested our trapping and imaging instrument by measuring the persistence length of individual double-stranded DNA molecules, and by following the stepping of single kinesin motor proteins along clearly imaged microtubules. The approach presented here provides a straightforward alternative for studies of biomaterials and individual biomolecules.     

Biotransformation of 7α-hydroxy- and 7-oxo-ent-atis-16-ene derivatives by the fungus Gibberella fujikuroi

The microbiological transformation of 7α,19-dihydroxy-ent-atis-16-ene by the fungus Gibberella fujikuroi gave 19-hydroxy-7-oxo-ent-atis-16-ene, 13(R),19-dihydroxy-7-oxo-ent-atis-16-ene, 7α,11β,19-trihydroxy-ent-atis-16-ene and 7α,16β,19-trihydroxy-ent-atis-16-ene, while the incubation of 19-hydroxy-7-oxo-ent-atis-16-ene afforded 13(R),19-dihydroxy-7-oxo-ent-atis-16-ene and 16β,17-dihydroxy-7-oxo-ent-atisan-19-al. The biotransformation of 7-oxo-ent-atis-16-en-19-oic acid gave 6β-hydroxy-7-oxo-ent-atis-16-en-19-oic acid, 6β,16β,17-trihydroxy-7-oxo-19-nor-ent-atis-4(18)-ene and 3β,7α-dihydroxy-6-oxo-ent-atis-16-en-19-oic acid.     

Naphthohydroquinones and lignans from the roots of Plocama pendula, a Canary Island paleoendemism

Two naphthohydroquinones, mollugin 6-methyl ether and plocanaphthin, have been obtained from the roots of Plocama pendula (Rubiaceae), a paleoendemism of the Canary Islands. The former is a new compound, while the latter has now been isolated for the first time from nature. Other compounds obtained from this species were the lignans syringaresinol, pinoresinol and lariciresinol, and the coumarin scopoletin.     

Fujenal, a diterpenoid saga of neighbouring group participation

The chemistry, the biosynthesis and the biotransformations related to fujenal and its analogues are reviewed. Despite the opportunity for free rotation about the C-9:C-10 bond, the chemistry of the ring B of this diterpenoid is dominated by neighbouring group participation between C-6, C-7 and C-19.     

An efficient marker-assisted backcrossing strategy for enhancing barley (Hordeum vulgare L.) production under acidity and aluminium toxicity

To feed the predicted extra two billion people by 2050, crop production must increase on existing cultivated land at a rate that challenges our current capability. Acid soils and aluminium (Al³⁺) toxicity restrict productivity worldwide but also offer the greatest opportunity for increases in global food production. Our understanding of the physiology, genetic control and the identification of genomic regions underlying Al resistance in important staple crops has increased greatly over the past 20 years, enabling the application of molecular breeding. In this study, we report the application of an efficient marker-assisted backcrossing (MAB) strategy for the introgression of the HvAACT1 gene which confers Al resistance in barley (Hordeum vulgare L.). We conducted foreground and background selection using microsatellite (SSR) markers linked to HvAACT1 and SSR-based linkage maps, along with embryo rescue and a cost-effective DNA preparation method shortening the breeding cycle to ~18 months. The MAB strategy enabled the development of homozygous (BC₃F₂) Al-resistant lines with the smallest introgressed region and 98.7 % of the recurrent parent genome. The Al-resistant line yielded significantly more seeds (121 %) than its isogenic line in soil-based assays containing 12 % of Al saturation. This MAB strategy could be extended to other staple crops with similar molecular toolboxes, expanding their cultivation onto acid soils, and contributing to greater yield stability and food security, particularly in developing countries.