Yield response of rice (Oryza sativa L.) genotypes to different types of drought under rainfed lowlands - Part 2. Selection of drought resistant genotypes

Drought frequently reduces grain yield of rainfed lowland rice. A series of experiments were conducted in drought-prone northeast Thailand to study the magnitude and consistency of yield responses of diverse, rainfed lowland rice genotypes to drought stress environments and to examine ways to identify genotypes that confer drought resistance. One hundred and twenty-eight genotypes were grown under non-stress and four different types of drought stress conditions. The relationship of genotypic variation in yield under drought conditions to genetic yield potential, flowering time and flowering delay, and to a drought response index (DRI) that removed the effect of potential yield and flowering time on yield under stress was examined. Drought stress that developed prior to flowering generally delayed the time of flowering of genotypes, and the delay in flowering was negatively associated with grain yield, fertile panicle percentage and filled grain percentage. Genotypes with a longer delay in flowering time had extracted more water during the early drought period, and as a consequence, had higher water deficits. They were consistently associated with a larger yield reduction under drought and in one experiment with a smaller DRI. Genotypes, however, responded differently to the different drought stress conditions and there was no consistency in the DRI estimates for the different genotypes across the drought stress experiments. The results indicate that with the use of irrigated-control and drought test environments, genotypes with drought resistance can be identified by using DRI or delay in flowering. However, selections will differ depending on the type of drought condition. The inconsistency of the estimates in DRI and flowering delay across different drought conditions reflects the nature of the large genotype-by-environment interactions observed for grain yield under various types of drought in rainfed lowland conditions. (C), 2002 Elsevier Science B.V. All rights reserved.

Yield response of rice (Oryza sativa L.) genotypes to different types of drought under rainfed lowlands - Part 3. Plant factors contributing to drought resistance

A series of experiments were conducted in drought-prone northeast Thailand to examine the magnitude of yield responses of diverse genotypes to drought stress environments and to identify traits that may confer drought resistance to rainfed lowland rice. One hundred and twenty eight genotypes were grown under non-stress and four different types of drought stress conditions. Under severe drought conditions, the maintenance of PWP of genotypes played a significant role in determining final grain yield. Because of their smaller plant size (lower total dry matter at anthesis) genotypes that extracted less soil water during the early stages of the drought period, tended to maintain higher PWP and had a higher fertile panicle percentage, filled grain percentage and final grain yield than other genotypes. PWP was correlated with delay in flowering (r = -0.387) indicating that the latter could be used as a measure of water potential under stress. Genotypes with well-developed root systems extracted water too rapidly and experienced severe water stress at flowering. RPR which showed smaller coefficient of variation was more useful than root mass density in identifying genotypes with large root system. Under less severe and prolonged drought conditions, genotypes that could achieve higher plant dry matter at anthesis were desirable. They had less delay in flowering, higher grain yield and higher drought response index, indicating the importance of ability to grow during the prolonged stress period. Other shoot characters (osmotic potential, leaf temperature, leaf rolling, leaf death) had little effect on grain yield under different drought conditions. This was associated with a lack of genetic variation and difficulty in estimating trait values precisely. Under mild stress conditions (yield loss less than 50%), there was no significant relationship between the measured drought characters and grain yield. Under these mild drought conditions, yield is determined more by yield potential and phenotype than by drought resistant mechanisms per se. (C) 2002 Elsevier Science B.V. All rights reserved.

Development and characterization of polymorphic microsatellite markers in taro (Colocasia esculenta)

Microsatellite-containing sequences were isolated from enriched genomic libraries of taro (Colocasia esculenta (L.) Schott). The sequencing of 269 clones yielded 77 inserts containing repeat motifs. The majority of these (81.7%) were dinucleotide or trinucleotide repeats. The GT/CA repeat motif was the most common, accounting for 42% of all repeat types. From a total of 43 primer pairs designed, 41 produced markers within the expected size range. Sixteen (39%) were polymorphic when screened against a restricted set of taro genotypes from Southeast Asia and Oceania, with an average of 3.2 alleles detected on each locus. These markers represent a useful resource for taro germplasm management, genome mapping, and marker-assisted selection.

Short report: Molecular evaluation of the efficacy of chloroquine treatment of uncomplicated Plasmodium falciparum malaria in East Timor

The efficacy of chloroquine treatment of uncomplicated Plasmodium falciparum malaria in East Timor was investigated via molecular tools. Genotyping of the polymorphic markers msp1 and msp2 was performed to investigate the number and type of parasite alleles in pre- and posttreatment blood samples collected from 48 patients. Patients were infected with a minimum of 8 msp1 and 14 msp2 allelic types of parasite, and 43% of the patients had more than one allelic type before treatment. The genotyping also revealed that 66.7% of the patients were infected with at least one identical allelic type of parasite before and after treatment and therefore were likely to have experienced recrudescence. All parasites in pre- and posttreatment blood samples carried the K76T mutation in pfcrt, regardless of the clinical response to chloroquine. The sequence polymorphism patterns in pfcrt in the majority of parasites examined were identical to those observed in Bougainville, Papua New Guinea.

Prediction of Golgi Type II membrane proteins based on their transmembrane domains

Motivation: A major issue in cell biology today is how distinct intracellular regions of the cell, like the Golgi Apparatus, maintain their unique composition of proteins and lipids. The cell differentially separates Golgi resident proteins from proteins that move through the organelle to other subcellular destinations. We set out to determine if we could distinguish these two types of transmembrane proteins using computational approaches. Results: A new method has been developed to predict Golgi membrane proteins based on their transmembrane domains. To establish the prediction procedure, we took the hydrophobicity values and frequencies of different residues within the transmembrane domains into consideration. A simple linear discriminant function was developed with a small number of parameters derived from a dataset of Type II transmembrane proteins of known localization. This can discriminate between proteins destined for Golgi apparatus or other locations (post-Golgi) with a success rate of 89.3% or 85.2%, respectively on our redundancy-reduced data sets.

A genomewide survey of developmentally relevant genes in Ciona intestinalis - IV. Genes for HMG transcriptional regulators, bZip and GATA/Gli/Zic/Snail

Many kinds of transcription factors and regulators play key roles in a variety of developmental processes. In the present survey, genes encoding proteins with conserved HMG-box, bZip domains, and some types of zinc finger motifs were surveyed in the completely sequenced genome of Ciona intestinalis. In the present analysis, 21 HMG-box-containing genes and 26 bZip genes were identified as well as four small groups of zinc finger genes in the Ciona genome. The results also showed that a less redundant set of genes is present in the Ciona genome compared with vertebrate genomes. In addition, cDNA clones for almost all genes identified have been cloned and distributed as a Ciona intestinalis Gene Collection Release I. The present comprehensive analysis therefore provides a means to study the role of these transcription factors in developmental processes of basal chordates.

Complete genomic sequence of the Australian south-west genotype of Sindbis virus: Comparisons with other Sindbis strains and identification of a unique deletion in the 3 '-untranslated region

Our previous studies have shown that two distinct genotypes of Sindbis (SIN) virus occur in Australia. One of these, the Oriental/Australian type, circulates throughout most of the Australian continent, whereas the recently identified south-west (SW) genetic type appears to be restricted to a distinct geographic region located in the temperate south-west of Australia. We have now determined the complete nucleotide and translated amino acid sequences of a SW isolate of SIN virus (SW6562) and performed comparative analyses with other SIN viruses at the genomic level. The genome of SW6562 is 11,569 nucleotides in length, excluding the cap nucleotide and poly (A) tail. Overall this virus differs from the prototype SIN virus (strain AR339) by 23% in nucleotide sequence and 12.5% in amino acid sequence. Partial sequences of four regions of the genome of four SW isolates were determined and compared with the corresponding sequences from a number of SIN isolates from different regions of the World. These regions are the non-structural protein (nsP3), the E2 gene, the capsid gene, and the repeated sequence elements (RSE) of the 3'UTR. These comparisons revealed that the SW SIN viruses were more closely related to South African and European strains than to other Australian isolates of SIN virus. Thus the SW genotype of SIN virus may have been introduced into this region of Australia by viremic humans or migratory birds and subsequently evolved independently in the region. The sequence data also revealed that the SW genotype contains a unique deletion in the RSE of the 3'UTR region of the genome. Previous studies have shown that deletions in this region of the SIN genome can have significant effects on virus replication in mosquito and avian cells, which may explain the restricted distribution of this genotype of SIN virus.

Invertebrate D2 type dopamine receptor exhibits age-based plasticity of expression in the mushroom bodies of the honeybee brain

We have isolated a cDNA clone from the honeybee brain encoding a dopamine receptor, AmDop2, which is positively coupled to adenylyl cyclase. The transmembrane domains of this receptor are 88% identical to the orthologous Drosophila D2 dopamine receptor, DmDop2, though phylogenetic analysis and sequence homology both indicate that invertebrate and vertebrate D2 receptors are quite distinct. In situ hybridization to mRNA in whole-mount preparations of honeybee brains reveals gene expression in the mushroom bodies, a primary site of associative learning. Furthermore, two anatomically distinct cell types in the mushroom bodies exhibit differential regulation of AmDop2 expression. In all nonreproductive females (worker caste) and reproductive males (drones) the receptor gene is strongly and constitutively expressed in all mushroom body interneurons with small cell bodies. In contrast, the large cell-bodied interneurons exhibit dramatic plasticity of AmDop2 gene expression. In newly emerged worker bees (cell-cleaning specialists) and newly emerged drones, no AmDop2 transcript is observed in the large interneurons whereas this transcript is abundant in these cells in the oldest worker bees (resource foragers) and older drones. Differentiation of the mushroom body interneurons into two distinct classes (i.e., plastic or nonplastic with respect to AmDop2 gene expression) indicates that this receptor contributes to the differential regulation of distinct neural circuits. Moreover, the plasticity of expression observed in the large cells implicates this receptor in the behavioral maturation of the bee.

Learning the dynamics of embedded clauses

Recent work by Siegelmann has shown that the computational power of recurrent neural networks matches that of Turing Machines. One important implication is that complex language classes (infinite languages with embedded clauses) can be represented in neural networks. Proofs are based on a fractal encoding of states to simulate the memory and operations of stacks. In the present work, it is shown that similar stack-like dynamics can be learned in recurrent neural networks from simple sequence prediction tasks. Two main types of network solutions are found and described qualitatively as dynamical systems: damped oscillation and entangled spiraling around fixed points. The potential and limitations of each solution type are established in terms of generalization on two different context-free languages. Both solution types constitute novel stack implementations - generally in line with Siegelmann's theoretical work - which supply insights into how embedded structures of languages can be handled in analog hardware.

Lectures and other types of teaching

A questionnaire on lectures was completed by 351 students (84% response) and 35 staff (76% response) from all five years of the veterinary course at the University of Queensland. Staff and students in all five years offered limited support for a reduction in the number of lectures in the course and the majority supported a reduction in the number of lectures in the clinical years. Students in the clinical years only and appropriate staff agreed that the number of lectures in fifth year should be reduced but were divided as to whether lectures in fifth year should be abolished. There was limited support for replacement of some lectures by computer assisted learning (CAL) programs, but strong support for replacement of some lectures by subject-based problem based learning (PBL) and strong support for more self-directed learning by students. Staff and students strongly supported the inclusion of more clinical problem solving in lectures in the clinical years and wanted these lectures to be more interactive. There was little support for lectures in the clinical years to be of the same type as in the preclinical years.

Characterization of the types of the Neotropical Pseudisobrachium (Hymenoptera: Bethylidae), with a key to species

Atualmente é difícil reconhecer a identidade de muitas espécies neotropicais de Pseudisobrachium Kieffer, 1904, principalmente por que as descrições e ilustrações disponíveis não são suficientes para permitir identificações precisas. Para resolver este problema, foram examinadas 115 espécies válidas, além de seus sinônimos juniores. Foram realizados doze atos nomenclaturais, e reconhecidas 110 espécies válidas para a região Neotropical. Foram designados dois lectótipos: Pristocera crassicornis Westwood and Pristocera haemorrhoidalis Westwood. Foram propostas sete sinonímias novas para espécies: Pseudisobrachium retusum Evans syn. nov. de P. pauxillum Evans; P. cunco Perez syn. nov. de P. erythrocephalum Evans; P. navajo Evans, P. rectangulatum Evans, P. emarginatum Evans e P. foutsi Evans syn. nov. de P. flavinervis Fouts; P. acuminatum Waichert & Azevedo syn. nov. de P. latum Waichert & Azevedo. Foi proposta a seguinte sinonímia nova para gênero: Parisobrachium Kieffer syn. nov. de Dissomphalus Ashmead. Foi estabelecida a seguinte combinação nova e revalidado o nome: Dissomphalus albipes (Kieffer) comb. nov. e nom. rev. de Pseudisobrachium paraguayense Kieffer.

The coexistence of peace and conflict in South America: toward a new conceptualization of types of peace

South America's predominant democratic regimes and its increasing interdependence on regional trade have not precluded the emergence of militarized crises between Colombia and Venezuela or the revival of boundary claims between Chile and Peru. This way, how can we characterize a zone that, in spite of its flourishing democracy and dense economic ties, remain involved in territorial disputes for whose resolution the use of force has not yet been discarded? This article contends that existing classifications of zones of peace are not adequate to explain this unusual coexistence. Thus, its main purpose is to develop a new analytical category of regional peace for assessing this phenomenon: the hybrid peace. It aims to research the evolution of security systems in South America during the previous century and build a new, threefold classification of peace zones: negative peace zones, hybrid peace zones, and positive peace zones.

Effect of cattle manure on sunflower production and water use in two types of soil

The aim of the present study was to evaluate water consumption, use efficiency and yield components of sunflower variety Embrapa 122 V/2000 cultivated in two types of soil (Fluvissol and Haplic Luvisol) subjected to increasing doses of cattle manure. The experiment was carried out in a greenhouse at Universidade Estadual da Paraíba. The experimental design was completely randomized in a factorial scheme. The irrigation was performed every other day, replacing the water absorbed by the plants. The water consumption and the use efficiency were evaluated, being the use efficiency determined by the ratio of the total dry mass of sunflower and the amount of water used to produce it in each treatment. Plants were harvested at 95 days after sowing when the following parameters were evaluated: number of seeds per plant, weight of seeds per plant, weight of 1000 seeds and the outer diameter of the capitulum (head). The results showed that the sunflower was positively affected by cattle manure application, increasing the production components and the water use efficiency, regardless of the type of soil. Excepting for the 1000 seeds weight and the water use efficiency, the type of soil affected significantly the water use, the number and weight of seeds per plant. The plants cultivated in Haplic Luvisol had a better performance.