Evaluation of fertigation scheduling for sugarcane using a vadose zone flow and transport model

Micro-irrigation has become an optimal means for providing water and nutrients to crops. There is an ample space for improving fertilizer use efficiency with micro-irrigation, if the movement and reactions of fertilizers in the soil are well understood. However, the rhizosphere dynamics of nutrients is very complex, depending on many factors such as soil temperature, pH, water content, and soil and plant characteristics. Many factors cannot be easily accurately quantified. However, using state-of-the-art modelling techniques, useful and reliable information can be derived.An attempt was made to evaluate the reactive transport of urea in the root zone of a sugarcane crop under drip irrigation, and to quantify the fluxes of urea, ammonium, and nitrate into the crop roots, volatilization fluxes, and deep drainage using a numerical model. This quantification helped in designing an optimal fertigation schedule. Various parameters used in the model were taken from either the literature or the field study. A typical scenario, based on the recommended total quantity of urea for sugar cane crop under drip irrigation in India, was tested using HYDRUS-2D. The total amount of urea was divided into fortnightly doses, depending on the stage of crop growth. For this scenario, the modelled crop uptake was found to be 30% higher than the crop demand. Consequently, an optimal fertigation schedule was developed that reduced the use of urea by 30% while at the same time providing enough N for its assimilation at all stages of crop growth. This type of modelling study should be used before planning field experiments for designing optimal fertigation schedules.     

Lipopolysaccharides from Commensal and Opportunistic Bacteria: Characterization and Response of the Immune System of the Host Sponge Suberites domuncula

Marine sponges harbor a rich bacterioflora with which they maintain close relationships. However, the way these animals make the distinction between bacteria which are consumed to meet their metabolic needs and opportunistic and commensal bacteria which are hosted is not elucidated. Among the elements participating in this discrimination, bacterial cell wall components such as lipopolysaccharides (LPS) could play a role. In the present study, we investigated the LPS chemical structure of two bacteria associated with the sponge Suberites domuncula: a commensal Endozoicomonas sp. and an opportunistic Pseudoalteromonas sp. Electrophoretic patterns indicated different LPS structures for these bacteria. The immunomodulatory lipid A was isolated after mild acetic acid hydrolysis. The electrospray ionization ion-trap mass spectra revealed monophosphorylated molecules corresponding to tetra- and pentaacylated structures with common structural features between the two strains. Despite peculiar structural characteristics, none of these two LPS influenced the expression of the macrophage-expressed gene S. domuncula unlike the Escherichia coli ones. Further research will have to include a larger number of genes to understand how this animal can distinguish between LPS with resembling structures and discriminate between bacteria associated with it.     

Germinability of <Emphasis Type="Italic">Vicia sativa</Emphasis> L. seeds After 10 Years of Storage in a Base Collection

The germinability of the Vicia sativa L. seed samples in the base collection at the Centro de Recursos Fitogenéticos (Spain) was controlled in 1986 and 1996. The mean germination of the collection, assessed by One-Sample T Test, was higher than 85%, suggesting its viability was properly maintained along the period. However, changes in germination along the same period assessed by Paired-Samples T Test showed a slight decrease in its global germinability. More data on the viability of stored seeds worldwide – including communication of unpublished data – are needed. Viability assays should be performed according to standard, internationally coordinated protocols and statistical analysis, within an adequate documentation system that assures the integrity of accession information.     

钼镉联合胁迫对山羊肾脏细胞凋亡相关基因表达的影响

本研究以波尔山羊为实验动物,旨在观察钼镉联合胁迫对山羊肾脏细胞凋亡相关基因表达的影响。选用63头健康波尔山羊随机分成7组,每组3个重复,选用七钼酸铵([(NH4)6Mo7O24·4H2O])作为实验钼源,氯化镉(Cd Cl2)作为实验镉源,按每kg山羊体质量添加钼、镉对照组(Mo 0 mg/kg+Cd 0 mg/kg),低镉低钼组(Mo 15mg/kg+Cd 0.5 mg/kg),低镉中钼组(Mo 30 mg/kg+Cd 0.5 mg/kg),低镉高钼组(Mo 45 mg/kg+Cd 0.5 mg/kg),高镉低钼组(Mo 15 mg/kg+Cd 1.0 mg/kg),高镉中钼组(Mo 30 mg/kg+Cd 1.0 mg/kg),高镉高钼组(Mo 45 mg/kg+Cd1.0 mg/kg),实验期50 d。并于当天、第25、50天每组各剖杀3头山羊取肾组织进行相关实验,观察不同剂量钼、镉对山羊肾脏细胞凋亡相关基因表达等的影响。结果显示,与对照组相比,在实验第25、50天时,实验组山羊肾脏bcl-2 mRNA表达量下降(P0.01),bax mRNA、caspase-3 mRNA和cytc mRNA表达量上升(P0.05或P0.01);山羊钼镉联合胁迫导致肾线粒体抗氧化功能降低、自由基含量升高,导致细胞促凋亡基因表达量上升,抗凋亡基因的表达量下降,提示钼镉联合胁迫对山羊肾脏有明显损伤。     

Note: A comparison of molecular diagnostic procedures for the detection of aster yellows phytoplasmas (16Sr-I) in leafhopper vectors

Different molecular procedures were compared for the detection of aster yellows phytoplasmas (AYP) in the leafhopper vectorsMacrosteles quadripunctulatus (Kirschbaum),Euscelidius variegatus (Kirschbaum) andEuscelis incisus (Kirschbaum). Polymerase chain reaction (PCR) with universal and group-specific primers designed on the 16S-rDNA sequence was most sensitive in nested assays. A dot-blot procedure with an oligoprobe designed on the 16S-rDNA was less sensitive and consistent to detect phytoplasmas in total insect DNA, but consistently detected amplicons from direct PCR. The dot-blot assay with a probe based on a phytoplasma plasmid sequence detected AYP in most vector specimens and did not react with DNAs from leafhoppers infected by flavescence dorée and psyllids infected by apple proliferation phytoplasmas. This last assay is almost devoid of contamination risks, faster and cheaper compared to PCR, therefore it has to be preferred for field-scale analysis of leafhopper populations. http://www.phytoparasitica.org posting Feb. 24, 2004.     

An in vitro study of hematopoietic progenitor cells from peripheral blood of rabbits

The purpose of this study was to isolate and cultivate a subpopulation of pluripotent stem cells (PSCs) from the peripheral blood of rabbits, which are frequently used in veterinary research as an animal model. Pluripotent stem cells, as described in human beings, are fibroblast-like cells that exhibit a CD34 marker, specific from other hematopoietic stem cells. Commonly used human commercial media has been researched for culturing rabbit PSCs. These findings allow us to contemplate the direct application of this simple and standardized methodology in several areas of study, such as of the pharmacological effect of many drugs on hematopoietic cells, veterinary practice, and even the study of new strategies in cellular therapy for some human diseases.     

Molecular characterization of Pseudomonas syringae isolates from fruit trees and raspberry in Serbia

Infection of fruit trees by Pseudomonas syringae is a potentially serious problem that may limit the establishment and sustained productivity of pome and stone fruit orchards in Serbia. To estimate possible diversity of Pseudomonas syringae fruit trees strains, we collected a set of strains in several areas of Serbia. The samples were taken from infected orchards with raspberry, plum, cherry, sour cherry, peach, pear and apple trees. Genetic diversity of P. syringae strains isolated from fruit trees was determined by using SpeI macrorestriction analysis of genomic DNAs by pulsed-field gel electrophoresis (PFGE) and REP-PCR. Molecular analysis showed that most of isolates had unique profiles, with the exception of isolates from plum and cherry that displayed profiles identical to each other and similar to P. syringae pv. morsprunorum. The study presented here clearly demonstrates the discriminative power of molecular techniques in enabling a detailed analysis of the genetic variations between strains of P. syringae from different pome and stone fruit hosts in Serbia.