High Potential Species Research Articles

Records of epigeal spiders in Bahia Blanca in the temperate region of Argentina

Ecological surveys of diversity and seasonal patterns of spiders in relation with cadavers have rarely been conducted, despite the high potential species diversity and abundance of spiders. The composition, abundance, guilds and seasonality of the spiders of Bahía Blanca, in the temperate region of Argentina were analysed. The study was performed in a semi-rural area between 2010 and 2011, using pitfall traps that were checked daily during 168 ± 7 days in winter, 38 days in spring, 30 days in summer, and 71 days in autumn. A total of 972 spiders were recorded belonging to 22 families and 65 species/morphospecies. The most abundant families were: Lycosidae, Zodariidae, Thomisidae, Theridiidae and Salticidae. The guild with more specimens was represented by ground hunters followed by specialists and ambush hunters, and the guild with the greatest number of species corresponded also to the ground hunters. Considering all specimens, adults prevailed with respect to juveniles, and males were more abundant than females. The more abundant species were Leprolochus birabeni, Steatoda sp. 1, Thomisidae sp. 33, Thomisidae sp. 32, Ostearius melanopygius and Metaltella simoni.

Aspects of the reproductive biology of the freshwater/brackish amphipod Quadrivisio lutzi (Crustacea, Amphipoda) from an unstable coastal lagoon of southeastern Brazil

The amphipod Quadrivisio lutzi (Shoemaker, 1933) (Maeridae) inhabits the coastal lagoons of southeastern Brazil, which are highly unstable environments. Drastic reduction in the abundance and distribution of this amphipod on these lagoons has been observed. The constant recovery of its populations suggests that this species may show a reproductive strategy that helps it to persist on these environments. Therefore, our aim was to study the reproductive biology of this species in Carapebus lagoon and to answer the question if its reproductive strategy contributes to a rapid population recovery. The size-range at sexual maturity was determined by the relative growth of the gnathopods and by the number of articles in antennal flagella. Brood size, egg diameter, size at first maturity and other relative reproductive parameters were obtained, which were compared to other species using a multivariate Principal Component Analysis (PCA). Females reach maturity at smaller size-range (2.9-3.9 mm body length (BL) than males (4.9 -5.9 mm BL). Mean egg diameter was small (0.35 ± 0.08 mm) and fecundity was high (20.2 ± 9.2 eggs/female; maximum 48 eggs). The relative reproductive parameters observed in Q. lutzi suggest it as iteroparous species. The PCA situated Q. lutzi within the species of high reproductive potential, characterized by small female size at first maturity, small egg diameter, large brood size and iteroparity, which have been largely considered adaptations that allow rapid recovery of population sizes. Therefore, we concluded that the reproductive strategy of this species contributes to its survival in the highly unstable Carapebus lagoon at southeastern Brazil.

Free-living heterotrophic flagellates of the sublittoral and bathyal zones of the Kara Sea

The first data are presented on the species diversity and community structure of deep-sea benthic heterotrophic flagellates in the Arctic (the Kara Sea). Thirty-three species and forms of heterotrophic flagellates were found, with kinetoplastids, stramenopiles, apusomonadids, and choanoflagellates being predominant. The species diversity of the studied region was characterized by a high beta-diversity and a low alphadiversity, which is indicative of a substantially higher potential species richness of flagellates in the Kara Sea. The total number of species of flagellates decreased with increasing depth (from 15 to 554 m); peculiar features of the species composition of deep-sea flagellates were not revealed. However, the flagellate communities within two different biotopes (the upper layer of the bottom sediments and the loose, flocculent layer on the surface of sediments together with near-bottom suspended matter) had similar taxonomic and trophic structures, but differed in the ratio of species with different feeding strategies. Attached or free-swimming flagellates were predominant in the loose surfacelayer, whereas rapidly gliding species that are able to actively search for and capture food predominated in the bottom sediments.

Forage yield and quality of Leucaena leucocephala and Guazuma ulmifolia in mixed and pure fodder banks systems in Yucatan, Mexico

In tropical areas of Mexico, Leucaena leucocephala is widely used in silvopastoral systems. However, little information exists on other native woody species of high forage potential, such as Guazuma ulmifolia. The aim of this study was to evaluate the components of biomass, forage yield and quality, and availability of N in fodder banks of L. leucocephala, G. ulmifolia, and a mixture of both species during dry and rainy seasons, under sub-humid tropical conditions. The experimental unit was a 5 × 10 m plot, containing three rows with 2 m between rows; each row had 20 plant positions with 0.50 m between plants. Within each plant position there was either a single plant, in the case of pure-crop, or two plants, in the case of mixed of both species. A complete randomized block design with three repetitions was used. In both seasons, there were a significantly greater proportion of leaves in the G. ulmifolia fodder banks (71 %) and in mixed fodder banks (69 %) than in L. leucocephala fodder banks (64 %). Consequently, these systems had leaf-to-stem ratios of 2.4, 2.2 and 1.9, respectively. The forage yield of fodder banks was not influenced by season. The mixed fodder bank had greater forage yield (5.1 t DM ha−1) than the L. leucocephala fodder bank (3.4 t DM ha−1) in each season. Additionally, the mixed fodder bank accumulated more forage yield during the experimental period (10.2 t DM ha−1 year−1) than G. ulmifolia (9.0 t DM ha−1 year−1) or L. leucocephala (6.9 t DM ha−1 year−1). The concentrations of CP, C and C:N were not influenced by season. Forage NDF and ADF concentrations were greater in the rainy season (476 g kg−1 DM) compared with the dry season (325 g kg−1 DM). Mixed fodder banks had the greatest N yield (185.9 kg ha−1) and consequently the greatest availability of N (371.8 kg N ha−1 year−1). We conclude that mixed fodder banks of L. leucocephala and G. ulmifolia are a better option for improving productivity and forage quality in comparison with pure fodder banks in Yucatan, Mexico.

Evaluation of microalgal diets for the intensive cultivation of the tropical calanoid copepod,Parvocalanus crassirostris

As their natural prey, copepods are considered the ideal diets for hatchery culture of fish larvae. However, intensive cultivation of copepods has proven difficult and low culture productivity is the norm, which severely limits their use in aquaculture. This study investigated the effects of algal diets on a range of productivity-related parameters, including egg production, hatching success, naupliar and copepodite survival, post-embryonic development time, population growth and sex ratio of a small-sized tropical copepod, Parvocalanus crassirostris, which has been identified as a high potential species for aquaculture. The diets tested included three live algal diets: Isochrysis sp. (T-Iso), Pavlova 50 (Pav) and the diatom Chaetoceros muelleri (Cht); two algal paste diets: Isochrysis sp. (P-Iso) and Thalassiosira weissflogii (P-TW), as well as four mixed algae treatments composed of three binary algae diets (T-Iso + Pav, T-Iso + Cht and Pav + Cht) and a tri-algal diet (T-Iso + Pav + Cht). All parameters examined except sex ratio were significantly affected by the diets. The binary algal diet T-Iso + Cht produced significant higher total egg production over female lifespan (121.0 ± 5.9 eggs) than all other treatments (P < 0.05). Survival during naupliar and copepodite stage was significantly superior when P. crassirostris were fed either the mixed diet of T-Iso + Cht or the monoalgal diets of Cht or T-Iso (P < 0.05) than other diets. These three treatments also had the fastest time of development to adults (ranging from 6.2 to 6.7 days). With an initial 100 adults, the T-Iso + Cht treatment produced the highest population growth over a 15-day cultivation period, which was significantly higher than other treatments (P < 0.001). In contrast, the algal paste treatments, including (P-Iso) produced overall the worst results for various parameters examined. However, the sex ratio of P. crassirostris was not significantly affected by diets and was always heavily skewed towards females (>84% were females) across all treatments. Based on the results of this study, T-Iso + Cht is recommended for intensive cultivation of P. crassirostris.

Species diversity and community structure of rove beetles (Coleoptera: Staphylinidae) attracted to dung of sika deer in coniferous forests of southwest Japan

AbstractInsect communities of mammal dung have been known as excellent model ecosystems for scientific study. Ecological surveys of diversity and seasonal patterns of coprophilous rove beetles in relation to wild mammals have rarely been conducted, although the high potential species diversity and abundance of the rove beetles are known. In order to investigate biodiversity of these beetles, we analyzed species composition, abundance, feeding guild and seasonality of rove beetles that were attracted to sika deer Cervus nippon dung by using dung‐baited pitfall traps for a 1.5‐year study in two plantations (cypress, cedar) and one secondary natural forest (pine) in Fukuoka Prefecture, southwest Japan. Consequently, saprophagous Anotylus sp. (Oxytelinae) was dominant in all forests. Analyses of feeding guild structure showed the number of individuals were dominated by saprophagous beetles, but the number of species were dominated by predatory beetles. Seasonal effects suggested that the species richness and abundance of rove beetles are possibly regulated by scarabaeoid dung beetles. These findings feature one example of a coprophilous rove beetle community.

Chemodiversity of Ursane‐ and Oleanane‐Type Triterpenes in Amazonian Burseraceae Oleoresins

The oleoresins exuded from species of the Burseraceae family present high potential due to their biological and pharmacological properties. The evaluation of the chemodiversity of the oleoresins of 23 Amazonian species of Burseraceae provided a profile of the principal constituents, viz., the ursane-type triterpenes α-amyrin (1), α-amyrenone (3), and brein (5) and the oleanane-type triterpenes β-amyrin (2), β-amyrenone (4), and maniladiol (6), and allowed to determine which of these species have the highest biotechnological potential and which ones are rich in other, potentially new, triterpenes or volatile compounds of interest for the cosmetics industry. The oleoresin compositions obtained by GC-FID and GC/MS analyses were submitted to principal component analysis (PCA) and hierarchical clustering on principal components (HCPC), which divided the 23 samples in five clusters. Protium giganteum and Trattinnickia peruviana, constituting the first cluster, presented high oleoresin contents of 3 and 4 (28.8 and 16.3% on average, resp.). The seven species of Burseraceae composing the second cluster were potential producers of new triterpenes and volatile compounds. Dacryodes hopkinsii and five Protium species (third cluster) presented average contents for all the triterpenes analyzed. The highest contents of 5 and 6 (averages of 3.9 and 5.4%, resp.) were observed in P. heptaphyllum ssp. ullei and T. glaziovii (fourth cluster). Finally, the six Protium species forming the fifth cluster showed high contents of 1 and 2 (48.0 and 19.9% on average, resp.). Moreover, this study allowed the description of the triterpene composition of 13 not previously investigated species.

Conventional and molecular cytogenetics of the pikeperch (Sander luciopercaL.)

Pikeperch (Sander lucioperca L.) is a percid fish species of high commercial value and potential for being aquacultured in Europe. As such, pikeperch needs to be karyologically studied with special attention dedicated to arrangement of the homologous chromosomes into pairs and chromosomal location of the chosen DNA sequences. The karyotype of the pikeperch consists of 48 small chromosomes: One pair of metacentric chromosomes, 15 pairs of submetacentric chromosomes and eight pairs of subtelo-acrocentric chromosomes (FN = 80). Original data on the chromosomal distribution of early and late replication regions, segments resistant to AluI, DdeI, HinfI and HaeIII restriction endonucleases and identification of the C-banded heterochromatin presented herein have been used to arrange pikeperch chromosomes into the karyotype. After Primed in situ labeling (PRINS) technique with primers enabling amplification of 5S rDNA sequences, hybridization spots observed on the short (p) arms of two the largest pikeperch submetacentric chromosomes (no. 2). Fluorescence in situ hybridization (FISH) with telomeric PNA (Peptide Nucleic Acid) probe enabled recognition of the conservative telomeric DNA sequences on the pikeperch chromosomes. No interstitial signals were observed. The specimens studied did not show any morphologically differentiated sex chromosomes.

Exploring the possible applications of catechin (gel) for oral care of the elderly and disabled individuals

Summary The oral cavity contains more than hundreds of microbial species. An increase in the number of these microorganisms like high pathogenic potential species, such as cariogenic and periodontopathic bacteria, and the change of microbial biota may result in, not only oral infection, but also systemic diseases, such as infective endocarditis and aspiration pneumonia. It is very important to control the growth of these microorganisms and its biota just after oral cleaning in order to suppress disease onset. In this regard, it is useful to use the anti-microbial component which acts against pathogenic microorganisms. Here, we highlight the importance of catechin, and feature its possible oral, especially periodontal applications. By combining catechin with gel (catechin gel), antimicrobial activity of catechin was prolonged in gel and catechin anti-oxidization property was observed. Catechin gel inhibited the growth of the Actinomyces, periodontopathic bacteria and Candida strains tested, but did not inhibit that of the oral streptococci that are important in the normal oral flora. In contrast, commercially available moisture gels containing antimicrobial components showed antimicrobial activity against all of the tested strains including the oral streptococci. This show that catechin has selective antimicrobial activity, attributable to hydrogen peroxide production. This paper reviews previous works using catechin and, likewise, catechin gel may be show its possible oral application for prevent dental caries and periodontal disease.

Improving representativeness of genebank collections through species distribution models, gap analysis and ecogeographical maps

An efficient germplasm collecting method was evaluated using six Lupinus species and the Spanish Lupinus collection as a study case. This method includes the application of geographic information systems, ecogeographical land characterization maps, species distribution models and gap analysis to identify prioritized collecting sites. To evaluate the efficiency of this collecting method, field collecting expeditions were carried out focusing on prioritized sites and the results of these collections were analyzed. Prioritized sites were identified using spatial and ecogeographical gaps, and potential species richness maps. The spatial gaps corresponded to populations non-included in the collection but recorded by other information sources while ecogeographical gaps corresponded to spatial gaps that were located in ecogeographical categories (obtained from the ecogeographical map) that were scarcely represented in the collection. A potential Lupinus species richness map was obtained by adding the information of single maps of Lupinus species distribution models. Subsequently, prioritized sites were obtained in ecogeographical gaps with high potential species richness values. Collecting expeditions were made in Spain in 2006, 2007 and 2008. Results showed that using the efficient germplasm collecting methodology was highly positive not only from a quantitative viewpoint (between 7.8 and 11% increase) but also in qualitative terms, focusing collection efforts in ecogeographical categories with low or null representation in the Spanish Lupinus collection (41% of the new accessions). Phenotypic differences related to adaptation to environment were observed in the field between the populations that grow in low or null represented categories and those that grow in highly represented categories.

Effect of inland salt-affected soil on physiological and growth characters of Eucalypt tree (Eucalyptus camaldulensis Dehnh.)&lt;br&gt;

Eucalyptus tree is a high potential plant species as a deep root system for water absorption to prevent the salt rise-up, a large bushy to cover the surface area and to detoxify the toxic salt ions. The aim of this research is to investigate the responses of Eucalyptus camaldulensis to different sites of inland salinity. Survival percentage of salt-stressed eucalypt was decreased, relating to salt contamination and negatively correlated with proline accumulation. Water use efficiency in the salt-stressed leaves was negatively related to electro conductivity (EC) values in the salt-affected soil. Chlorophyll a (Chla) and total chlorophyll (TC) degradations were positively related to maximum quantum yield of photosystem II (PSII) (Fv/Fm) (r2=0.89) and quantum efficiency of PSII (?PSII) (r2=0.95), leading to low net photosynthetic rate (Pn) (r2=0.79) and to reduce the growth characteristics in term of plant height and circumstance. The survived eucalypt plants in the severe salinity land containing high salt contamination (1.7-2.0% salt) may be further applied as potential plant species to remediate the inland salinity soil.

Calibration of the forest growth model 3-PG to eucalypt plantations growing in low rainfall regions of Australia

In Australia, tools are required to assess likely commercial and environmental benefits of growing saw logs in regions of low-medium rainfall. The widely used 3-PG model was considered appropriate given that it has a relatively low demand for data and can be applied spatially. Two species of high potential for saw log production in such regions are Eucalyptus cladocalyx (sugar gum) and Corymbia maculata (spotted gum). For both of these species, we harvested 12 trees over a range of sizes (from 4 to 52 cm diameter at breast height) to derive 3-PG parameters, including stem density, specific leaf area, relationships between stem diameter and mass, and the branches and bark fraction. We also collated stem diameter data together with data on stocking and survival from 55 stands of E. cladocalyx, and 37 stands of C. maculata. By simulating growth at each of these sites using 3-PG, we calibrated parameters determining sensitivity to frost, optimum temperature for growth, and rates of litterfall to attain an efficiency of prediction of stem diameter of 80% for both species. It was also ensured that prediction of biomass of tree components were in the order of that calculated based on allometric relationships, although efficiencies of these predictions were particularly poor for foliage. We found 3-PG gave a 9–34% greater efficiency of prediction of stem diameter than when using stand age alone as an explanatory variable, indicating that even when only the most basic of site information is available (i.e. rainfall, temperature, solar radiation, number of frost days as well as some information regarding stocking and management), 3-PG can potentially account for some variations in growth across a wide range of sites. Accuracy of 3-PG predictions could be further improved by better quantifying site data (i.e. fertility rating, soil texture and available water) and improving model structure to better predict soil water availability, survival, and partitioning of biomass between tree components.

A novel boron-doped diamond (BDD)-coated platinum mesh electrode for spectroelectrochemistry

A boron-doped diamond (BDD)-coated platinum (Pt) mesh electrode has been fabricated for the first time and applied in thin-layer double-potential-step chronoabsorptometry of two high-potential redox species, Ru(bpy)33+/2+ and Fe(phen)33+/2+, in aqueous solutions. The BDD-coated mesh exhibited its characteristic as a diamond electrode by a low voltammetric background current and well-defined voltammetric responses. Moreover, in double-potential-step chronoabsorptometry with a thin-layer cell, the redox species reached a steady state rapidly and reversibly, to allow the determination of the E0′ value for Ru(bpy)33+/2+ in both alkaline (pH 8) and acidic (pH 5) solutions and for Fe(phen)33+/2+ in alkaline solutions. In contrast, on a bare Pt electrode, the Ru(bpy)33+/2+ and Fe(phen)33+/2+ redox waves are largely buried in that of water oxidation, and spectroelectrochemical responses are highly irreversible, due probably to the attack of O2 or OH radical on the redox species examined. The BDD-coated Pt mesh electrode will thus be an effective tool for measuring high-E0′ components in biosystems.

The antileishmanial activity assessment of unusual flavonoids from Kalanchoe pinnata

The importance of flavonoids for the antileishmanial activity of Kalanchoe pinnata was previously demonstrated by the isolation of quercitrin, a potent antileishmanial flavonoid. In the present study, the aqueous leaf extract from the medicinal plant K. pinnata (Crassulaceae) afforded a kaempferol di-glycoside, named kapinnatoside, identified as kaempferol 3- O-α- l-arabinopyranosyl (1 → 2) α- l-rhamnopyranoside ( 1). In addition, two unusual flavonol and flavone glycosides already reported, quercetin 3- O-α- l-arabinopyranosyl (1 → 2) α- l-rhamnopyranoside ( 2) and 4′,5-dihydroxy-3′,8-dimethoxyflavone 7- O-β- d-glucopyranoside ( 3), have been isolated. Their structures were determined via analyses of mono and bi-dimensional 1H and 13C NMR spectroscopic experiments and HR-MALDI mass spectra. Because of its restricted occurrence and its abundance in K. pinnata, flavonoid ( 2) may be a chemical marker for this plant species of high therapeutic potential. The three flavonoids were tested separately against Leishmania amazonenis amastigotes in comparison with quercitrin, quercetin and afzelin. The quercetin aglycone – type structure, as well as a rhamnosyl unit linked at C-3, seem to be important for antileishmanial activity.

SUSTAINABLE NATIVE FLORICULTURE?

The Centre for Native Floriculture (CNF) commenced in May 2003 at The University of Queensland, Gatton. The CNF is a joint initiative with the Queensland State Government, with funding for an initial 3-year period. The phase-out of bush-picking under the South East Queensland Forests Agreement was a catalyst for the Centres establishment. The CNF vision is: ‘to help create an internationally competitive and environmentally sustainable native floriculture industry that provides significant employment opportunities in Queensland’. The Centre is comprised of three research, development and extension programs. The Value Chain Program assists native floriculture industry groups in developing efficient consumer-orientated production, handling and marketing systems for select high potential species. These value chain systems will serve as models for realizing the market potential of and regional fiscal returns on other native ornamental species identified as crop ideotypes that are sought after by end-users (e.g. florists). The Floriculture Program supports the value chain by working to enhance germplasm for the native floriculture industry through selection and breeding, optimize cultivation protocols and overcome any technical barriers that arise. Such barriers include propagation constraints, disease problems and post-harvest limitations. The Capacity Building Program operates to transfer technology and other skills (e.g. value chain management principles) to industry members, train operatives for the industry and promote native floriculture. Conservation of native flora is encouraged through cultivation and community engagement. Protection of biodiversity is advocated via regional production systems that spare natural areas and educate the public as to the biological, floricultural and aesthetic values of native flora. Eco-agricultural tourism focused on wildflowers both in nature and in cultivation is also advocated by the CNF.

Modeling potential species richness and urban buildout to identify mitigation sites along a California highway

One-foot resolution imagery is used to develop a detailed land cover map for part of Highway 99 in the San Joaquin Valley of California, US. The land cover map is used to model the probability of occurrence of 12 endangered or threatened species and as input to an urban growth model to examine the likelihood of development of every map unit. The combination of the two model predictions permits the categorization of every map unit with a potential endangered species richness index and predicted degree of development. Polygons with high potential endangered species richness were ranked according to the degree of development pressure. This planning approach is computationally intensive, but the input data are relatively easy to assemble, consisting of: a detailed, and fine-scale, land cover map; species presence locations; state-wide climate and landcover maps; a parcel ownership map; population growth projections; and a digital map of the county general plan.

QUEENSLAND'S CENTER FOR NATIVE FLORICULTURE

The Center for Native Floriculture (CNF) is a joint initiative of The University of Queensland and the Queensland State Government. The Center's activities build upon past contributions by University staff and students in research, development and extension in native floriculture. Activities focus on Queensland's diverse and extensive native flora and their use in the cut-flower and foliage, flowering and foliage pot plant, bedding plant, and, home garden and landscape industry sectors. The gradual phase-out of bush-picking under the South East Queensland Regional Forests Agreement was a catalyst for the Center's establishment. The CNF vision is 'to help create an internationally competitive and environmentally sustainable native floriculture industry that provides significant employment opportunities in Queensland'. The Center recognizes the value of 'conservation through cultivation'. In support of Queensland's 'Smart State' agenda, the CNF aims to deliver a mix of public (e.g. employment opportunities) and private (e.g. revenue streams) good outcomes. The Center is composed of three integrated Programs. The Value Chain Program assists native floriculture industry groups in developing efficient consumer-orientated production, handling and marketing systems for novel high economic potential species. These value chains serve as models for further realizing the market potential of, and fiscal returns on, yet other native ornamental species identified (e.g. through market research) as being desired by end-users (e.g. florists). The Floriculture Program supports the industry and the Value Chain Program by research and development to enhance germplasm available to the industry (viz. through exploration, selection and breeding), to optimize cultivation protocols, and, to overcome any technical barriers that arise. Technical barriers typically include propagation constraints, disease problems and post-harvest quality limitations. The Capacity Building Program works to develop and maintain infrastructure (e.g. research nursery facilities) in general support of CNF activities and to extend both technology and skills (e.g. plant propagation) to industry members.

Patterns and uncertainties of species' range shifts under climate change

AbstractAlthough bioclimatic modelling is often used to estimate potential impacts of likely climate changes, little has been done to assess the reliability and variability of projections. Here, using four niche‐based models, two methods to derive probability values from models into presence–absence data and five climate change scenarios, I project the future potential habitats of 1350 European plant species for 2050. All 40 different projections of species turnover across Europe suggested high potential species turnover (up to 70%) in response to climate change. However variability in the potential distributional changes of species across climate scenarios was obscured by a strong variability in projections arising from alternative, yet equally justifiable, niche‐based models. Therefore, projections of future species distributions and derived community descriptors cannot be reliably discussed unless model uncertainty is quantified explicitly. I propose and test an alternative way to account for modelling variability when deriving estimates of species turnover (with and without dispersal) according to a range of climate change scenarios representing various socio‐economic futures.

Spectroscopic studies of the tungsten-containing formaldehyde ferredoxin oxidoreductase from the hyperthermophilic archaeon Thermococcus litoralis.

The electronic and redox properties of the iron-sulfur cluster and tungsten center in the as-isolated and sulfide-activated forms of formaldehyde ferredoxin oxidoreductase (FOR) from Thermococcus litoralis (Tl) have been investigated by using the combination of EPR and variable-temperature magnetic circular dichroism (VTMCD) spectroscopies. The results reveal a [Fe4S4]2+,+ cluster (Em=-368mV) that undergoes redox cycling between an oxidized form with an S=0 ground state and a reduced form that exists as a pH- and medium-dependent mixture of S=3/2 (g=5.4; E/D=0.33) and S=1/2 (g=2.03, 1.93, 1.86) ground states, with the former dominating in the presence of 50% (v/v) glycerol. Three distinct types of W(V) EPR signals have been observed during dye-mediated redox titration of as-isolated Tl FOR. The initial resonance observed upon oxidation, termed the "low-potential" W(V) species (g=1.977, 1.898, 1.843), corresponds to approximately 25-30% of the total W and undergoes redox cycling between W(IV)/ W(V) and W(V)/W(VI) states at physiologically relevant potentials (Em= -335 and -280 mV, respectively). At higher potentials a minor "mid-potential" W(V) species, g= 1.983, 1.956, 1.932, accounting for less than 5 % of the total W, appears with a midpoint potential of -34 mV and persists up to at least + 300 mV. At potentials above 0 mV, a major "high-potential" W(V) signal, g= 1.981, 1.956, 1.883, accounting for 30-40% of the total W, appears at a midpoint potential of +184 mV. As-isolated samples of Tl FOR were found to undergo an approximately 8-fold enhancement in activity on incubation with excess Na2S under reducing conditions and the sulfide-activated Tl FOR was partially inactivated by cyanide. The spectroscopic and redox properties of the sulfide-activated Tl FOR are quite distinct from those of the as-isolated enzyme, with loss of the low-potential species and changes in both the mid-potential W(V) species (g= 1.981, 1.950, 1.931; Em = -265 mV) and high-potential W(V) species (g=1.981, 1.952, 1.895; Em = +65 mV). Taken together, the W(V) species in sulfide-activated samples of Tl FOR maximally account for only 15% of the total W. Both types of high-potential W(V) species were lost upon incubation with cyanide and the sulfide-activated high-potential species is converted into the as-isolated high-potential species upon exposure to air. Structural models are proposed for each of the observed W(V) species and both types of mid-potential and high-potential species are proposed to be artifacts of ligand-based oxidation of W(VI) species. A W(VI) species with terminal sulfido or thiol ligands is proposed to be responsible for the catalytic activity in sulfide-activated samples of Tl FOR.

Improving multipurpose tree and shrub species for agroforestry systems

With the aid of an example of ICRAF's tree improvement research programme for the highlands of Eastern and Central Africa, a logical approach to selection and breeding of multipurpose trees and shrubs in agroforestry context is proposed. Criteria for selection of high priority species are proposed. Some species of high potential for agroforestry development in Sub Sahara Africa are proposed. The necessary sequential research steps are discussed.