Protein splicing converts the yeast TFP1 gene product to the 69-kD subunit of the vacuolar H(+)-adenosine triphosphatase

The TFP1 gene of the yeast Saccharomyces cerevisiae encodes two proteins: the 69-kilodalton (kD) catalytic subunit of the vacuolar proton-translocating adenosine triphosphatase (H(+)-ATPase) and a 50-kD protein. The 69-kD subunit is encoded by the 5' and 3' thirds of the TFP1 coding region, whereas the 50-kD protein is encoded by the central third. Evidence is presented that both the 69-kD and 50-kD proteins are obtained from a single translation product that is cleaved to release the 50-kD protein and spliced to form the 69-kD subunit.     

Two contrasting laboratory methods improve <Emphasis Type="Italic">Silphium integrifolium</Emphasis> Michx. germination rate to agronomically acceptable levels

Organic dormancy, the inability to germinate under favorable conditions, is a common problem in many crop species and their wild relatives, leading to more variable emergence, plant density, and growth rates, thus increasing costs, and lowering yield. To overcome these problems, several different methods have been developed for various crop and model plants. However, in the emerging crop being bred from wild and semi-domesticated Silphium, no such method has been established thus far. The objective of this study was to identify a dormancy-breaking assay to increase the seed germination rate. Seeds of three different Silphium integrifolium Michx. genotypes were treated with five chemical and one cold treatment, and dried before or after the treatment at 27 °C or 40 °C. Untreated, dried seeds were taken as control. Seeds soaked for 24 h in a ethephon/potassium nitrate solution followed by a 72 h drying step at 40 °C showed an increase of germination to up to 90?±?2% compared to control seeds (3?±?0% and 5?±?1%). We identified the minimum time frame of cold stratification needed to enhance seed germination in Silphium, and found that cold stratification was nearly as good as the chemical treatment. Our results provide two alternate ways to treat S. integrifolium seeds for breaking organic dormancy, which will help to facilitate future research in the Silphium domestication community. The fact that our optimal treatments were similar to protocols developed for sunflower suggests that these methods may also be applicable to many related economically important Asteraceae species.     

Urban forestry priorities of Massachusetts (USA) tree wardens

As part of a survey we sent to tree wardens (individuals responsible for public trees) in communities in Massachusetts, USA, we examined which urban forest management tools and activities were most important to tree wardens themselves. Tree wardens generally agreed that inter-departmental communication and Chapter 87 (a state law promulgating the powers of a tree warden) were more important than having a qualified tree warden, an advocacy/advisory group, or a management plan (measures recognized by the USDA Forest Service in the Community Accomplishment Reporting System). Nearly all tree wardens prioritized removing dead and hazard trees. We discuss management implications of our results, paying particular attention to the importance of state laws in supporting urban forest management.     

Synthesis of biotin conjugates of the antifungal compound cymoxanil

Biotin conjugates are of considerable value in investigating the mode of action of biologically active compounds. Two biotin conjugates related to the antifungal compound cymoxanil [1-(2-cyano-2-methoximinoacetyl)-3-ethyl urea] were prepared as the first step in an effort to employ display cloning to identify the compound's target site. In the first conjugate, prepared in five steps, the biotin moiety was attached at the position occupied by the ethyl group in cymoxanil. In the second conjugate, prepared in four steps, the biotin moiety was attached through the oxime functional group.     

Pharmacokinetics of ivermectin in zebu Gobra (Bos indicus)

Plasma disposition kinetics of ivermectin was evaluated in a West African cattle breed. Five clinically healthy zebu Gobra cattle (Bos indicus) weighing 220-270 kg were treated (0.2 mg kg-1) with a commercially available ivermectin formulation for cattle. Blood samples were collected by jugular puncture at different times between 0.5 h and 40 days post-treatment. After plasma extraction and derivatization, samples were analysed by HPLC with fluorescence detection. Ivermectin was detected in plasma between 30 min and 20 days post-treatment. The observed peak plasma concentration (Cmax) was 46.3+/-13.8 ng ml-1 and the time to reach Cmax (t(max)) was 0.9+/-0.2 day. The values for the absorption half-life (t1/2ab) and the elimination half-life (t1/2el) were 0.3+/-0.2 and 2.8+/-0.7 days, respectively. The calculated area under the concentration-time curve (AUC) was 185.2+/-12.1 ng day ml-1 and the mean residence time (MRT) was 4.2+/-1.3 days. The availability of ivermectin is low in zebu Gobra in comparison to other breeds cattle but equivalent to that reported in the yak and is likely to be due to physiological characteristics of this breed.     

Diversity patterns of indigenous arbuscular mycorrhizal fungi associated with rhizosphere of cowpea (Vigna unguiculata (L.) Walp.) in Benin,West Africa

Assessment of diversity and understanding factors underlying species distribution are fundamental themes in ecology. However, the diversity of native arbuscular mycorrhizal fungi (AMF) species in African tropical agro-ecosystems remains weakly known. This research was carried out to assess the morphological diversity of indigenous AMF species associated with rhizosphere of cowpea (Vigna unguiculata (L.) Walp.) in different agro-ecological zones (AEZ) of Benin and to examine the effects of soil chemical properties, climatic factors and agricultural practices on this diversity. Results showed that, in Benin, cowpea was grown by farmers in very exhausted soils, where available phosphorus and potassium were deficient. The indigenous AMF spore density was on average 202 spores per 100 g dry soil and there was no difference in the density among the agro-ecological zones (P = 0.56). Fifteen AMF morphospecies belonging to eight genera (Gigaspora, Scutellospora, Racocetra, Acaulospora, Funneliformis, Rhizophagus, Glomus and Claroideoglomus) were detected. The computed species richness estimators indicated that a limited number of additional undetected morphospecies are probably present in cowpea fields. According to analysis of similarity (ANOSIM), the arbuscular mycorrhizas community composition of the Sudanian zone and Guinean zone were not significantly different (r = −0.01; P = 0.517). The diversity of AMF morphospecies in the fields was weak with prevalence of Glomeraceae (92%). Furthermore, AMF diversity and evenness indices were negatively correlated with annual rainfall (P < 0.01) and with available phosphorus (P < 0.05). However, no significant correlation was observed between AMF diversity indices and soil organic carbon. Ultimately, this study tends to confirm that soil management practices (tillage, soil disturbance) have negative effect on AMF diversity.