Verrucosamide,a Cytotoxic 1,4-Thiazepane-Containing Thiodepsipeptide from a Marine-Derived Actinomycete

A new cytotoxic thiodepsipeptide, verrucosamide (1), was isolated along with the known, related cyclic peptide thiocoraline, from the extract of a marine-derived actinomycete, a Verrucosispora sp., our strain CNX-026. The new peptide, which is composed of two rare seven-membered 1,4-thiazepane rings, was elucidated by a combination of spectral methods and the absolute configuration was determined by a single X-ray diffraction study. Verrucosamide (1) showed moderate cytotoxicity and selectivity in the NCI 60 cell line bioassay. The most susceptible cell lines were MDA-MB-468 breast carcinoma with an LD₅₀ of 1.26 µM, and COLO 205 colon adenocarcinoma with an LD₅₀ of 1.4 µM. Also isolated along with verrucosamide were three small 3-hydroxy(alkoxy)-quinaldic acid derivatives that appear to be products of the same biosynthetic pathway.     

Maintaining Genetic Resources of Peach Palm (<Emphasis Type="Italic">Bactris gasipaes</Emphasis> Kunth): The Role of Seed Migration and Swidden-fallow Management in Northeastern Peru

Knowledge of the effects of farmer practices on population genetic parameters of peach palm (Bactris gasipaes Kunth) is relevant to the improvement and conservation of the palm’s genetic resources. Microsatellite markers were used to assess genetic diversity and population structure of peach palm in swidden-fallow agroforestry systems in northeastern Peru. The study covered eight communities, comprising two study areas 160 km apart – one occupied by indigenous Amerindians and the other by mixed race campesinos. Simultaneous analysis of an ex situ peach palm germplasm collection provided a means to compare population genetic parameters. Farmers who were surveyed on seed selection practices for peach palm reported that an average of only four palms (4.3 for campesino and 1.5 for indigenous populations) were used to provide seed for the establishment of the forest gardens sampled. As expected, inbreeding coefficients observed within communities were relatively high (f = 0.105 − 0.210), however, observed heterozygosities within communities were also high (0.625–0.741). A metapopulation approach was used to describe migration within and among regions, implying a hierarchical structure of gene flow which maintains relatively high levels of genetic diversity. Seed migration was found to occur over longer distances (≤600 km) and at a higher frequency (46% of palms sampled) in the indigenous study area, and a proportionally greater number of alleles was found (49 vs. 43 over three loci) with twice as many private alleles occurring only in the indigenous populations. The farmers’ practice of preserving remnant palms through successive swidden generations may have contributed to the maintenance of alleles by reducing the severity of founder effects. Although the campesino study area exhibited a significant (20% of the variation; p < 0.01) isolation-by-distance relationship across 35 km distance, in general, both study populations had relatively limited genetic structure (θ = 0.012–0.03), which is believed to have resulted from the exchange of seeds over long distances and periods of time.     

Alley cropping of maize with calliandra and leucaena in the subhumid highlands of Kenya: Part 2. Biomass decomposition, N mineralization, and N uptake by maize

A major challenge in developing agroforestry approaches that utilize tree-leaf biomass for provision of N to crops is to ensure synchrony between the N released from decomposing prunings and N demand by crops. A study was conducted in the subhumid highlands of Kenya to assess the rate of decomposition and mineralization of soil-incorporated Calliandra calothyrsus Meissner (calliandra) and Leucaena leucocephala (Lam.) de Wit (leucaena) tree biomass and maize roots (Zea mays L.) both in an alley cropping and a sole cropping system. The amount of mineralized N peaked four weeks after planting (WAP) maize in all the treatments during both seasons of 1995. Cumulative mineralized N at week 20 ranged from 114 to 364 kg N ha⁻¹ season⁻¹, the absolute control treatment giving the lowest and the prunings-incorporated treatments giving the highest amounts in the two seasons. Total N uptake by maize, ranging from 42 to 157 kg ha⁻¹ season⁻¹, was lowest in the 'alley-cropped, prunings-removed' treatments, and highest in the 'non alley-cropped-prunings-incorporated' treatments. The apparent N recovery rate by maize was highest in the fertilizer applied treatments in the two seasons. Decomposition rate constants (kD) ranged from 0.07 to 0.21 week⁻¹, and the rates among the different plant residues were as follows: leucaena < calliandra < maize roots. Nitrogen release rate constants (kN), ranging from 0.04 to 0.25 week⁻¹, followed a similar pattern as the rate of decomposition with leucaena releasing the highest amount of N followed by calliandra and lastly by maize roots. This revised version was published online in June 2006 with corrections to the Cover Date.     

Multipurpose tree prunings as a source of nitrogen to maize under semiarid conditions in Zimbabwe

When multipurpose-tree (MPT) prunings are used as a source of nitrogen to annual corps in agroforestry systems, it is important that high levels of N recovery are attained. In order to test the effect of pruning quality and method of pruning application on N-recovery rates, a field experiment was conducted using prunings of five MPT species and two methods of application (surface versus incorporation). There was an interaction of pruning quality and method of pruning application on N recovery and maize grain yield. For most MPT species used, incorporated prunings gave high nitrogen recovery compared to surface applied prunings. In order to achieve synchrony between N supply from prunings and N demand by a maize crop, relatively large amounts of N should be released into the soil before peak N demand by the maize crop. This could be achieved by incorporating adequate quantities of high quality prunings such as those ofCajanus cajan andLeucaena leucocephala. Florida Agricultural Experiment Station Journal Series Number R-05489.     

Identification of soybean strains resistant to Xanthomonas campestris pv. glycines

Summary Soybean germplasm was screened for resistance to bacterial pustule disease. The etiological agent, Xanthomonas campestris pv. glycines, was isolated from the leaves of field grown soybean in Maharashtra, India. The screening of soybean stocks was carried out by excised leaf inoculation method. A differential susceptibility to the pathogen was observed in the tested stocks. Two stocks P-4-2 and P-169-3 were found to be completely resistant to the pathogen and displayed an incompatible reaction. Four cultivars, EC-34160, Bragg, Kalitur and PK-472 displayed moderate resistance and the remaining stocks were susceptible to the attack of the pathogen. The stocks P-4-2 and P-169-3 remained resistant even to a high concentration of 10⁹ colony forming units (cfu)/ml of the pathogen.     

Characterization, quantification, and bioactivities of anthocyanins in Cornus species

Cornus mas, Cornus officinalis, Cornus controversa, and Cornus kousa (Cornaceae) bear edible fruits that are consumed in parts of Europe and Asia. This study undertook the investigation of the presence and levels of anthocyanins in the fruits of these Cornus species by HPLC. The anthocyanins present in Cornelian cherries, C. mas, are delphinidin 3-O-beta-galactopyranoside (1), cyanidin 3-O-beta-galactopyranoside (2), and pelargonidin 3-O-beta-galactopyranoside (3). C. officinalis contains only anthocyanins 1-3, similar to C. mas, but in different proportions. However, C. controversa contains anthocyanins 1-3 among other anthocyanins, but Chinese dogwood, C. kousa, did not contain 1-3. The contents of pure anthocyanins 1, 2, and 3 in 1 kg of fresh fruits of C. mas, C. officinalis, and C. controversa were 280, 1079, and 710 ppm; 11, 77, and 230 ppm; and 600, 1000, and 700 ppm, respectively. In cyclooxygenase (COX)-I and -II enzyme inhibitory assays, anthocyanins 1-3 (all 40 microM) showed activities of 9.2 and 11.7%; 7.6 and 12.4%; and 5.3 and 7.8%, respectively, compared to Naproxen (54.3 and 41.3%; 10 microM), ibuprofen (47.5 and 39.8%; 10 microM), Celebrex (46.2 and 66.3%; 1.67 ppm), and Vioxx (23.8 and 88.1%, 1.67 ppm). In the antioxidant assay, anthocyanins 1-3 (all 40 microM) showed activities of 70.2, 60.1, and 40.3%, respectively. At 10 microM concentration, commercial synthetic antioxidants tert-butylhydroquinone, butylated hydroxytoluene, butylated hydroxyanisole, and vitamin E gave 83.2, 79.7, 82.1, and 10.2% of antioxidant activity, respectively.     

A non-destructive approach for assessing decay in preservative treated wood

This study investigated the suitability of the non-destructive vibration-impulse excitation technique to assess the attack of preservative-treated wood in contact with the ground. Small stakes (10×5×100 mm³) of treated and untreated Scots pine sapwood were exposed to decay in laboratory-scale terrestrial ecosystems. Different soils were used to prove the influence of different types of wood destroying micro-organisms. Wood decay was monitored periodically for one year by determining mass losses and changes in dynamic modulus of elasticity. The results show a large variability in resistance against attacking fungi, depending on wood preservative and soil type. The non-destructive approach using the dynamic modulus of elasticity proved to be a good and sensitive tool for assessing the attack of stakes in laboratory soil testing.