Comment on "Drought-induced reduction in global terrestrial net primary production from 2000 through 2009"     

Samanta A  Costa MH  Nunes EL  Vieira SA  Xu L  Myneni RB 《Science (New York, N.Y.)》2011,333(6046):1093; author reply 1093

Zhao and Running (Reports, 20 August 2010, p. 940) reported a reduction in global terrestrial net primary production (NPP) from 2000 through 2009. We argue that the small trends, regional patterns, and interannual variations that they describe are artifacts of their NPP model. Satellite observations of vegetation activity show no statistically significant changes in more than 85% of the vegetated lands south of 70°N during the same 2000 to 2009 period.  相似文献   

Kinetics of morphogen gradient formation     

Kicheva A  Pantazis P  Bollenbach T  Kalaidzidis Y  Bittig T  Jülicher F  González-Gaitán M 《Science (New York, N.Y.)》2007,315(5811):521-525

In the developing fly wing, secreted morphogens such as Decapentaplegic (Dpp) and Wingless (Wg) form gradients of concentration providing positional information. Dpp forms a longer-range gradient than Wg. To understand how the range is controlled, we measured the four key kinetic parameters governing morphogen spreading: the production rate, the effective diffusion coefficient, the degradation rate, and the immobile fraction. The four parameters had different values for Dpp versus Wg. In addition, Dynamin-dependent endocytosis was required for spreading of Dpp, but not Wg. Thus, the cellular mechanisms of Dpp and Wingless spreading are different: Dpp spreading requires endocytic, intracellular trafficking.  相似文献   

Erasing the world's slow stain: strategies to beat multidrug-resistant tuberculosis     

Dye C  Williams BG  Espinal MA  Raviglione MC 《Science (New York, N.Y.)》2002,295(5562):2042-2046

Multidrug-resistant tuberculosis (MDR) is perceived as a growing hazard to human health worldwide. Judgments about the true scale of the problem, and strategies for containing it, need to come from a balanced appraisal of the epidemiological evidence. We conclude in this review that MDR is, and will probably remain, a locally severe problem; that epidemics can be prevented by fully exploiting the potential of standard short-course chemotherapy (SCC) based on cheap and safe first-line drugs; and that best-practice SCC may even reduce the incidence of MDR where it has already become endemic. On the basis of the available, imperfect data, we recommend a three-part response to the threat of MDR: widespread implementation of SCC as the cornerstone of good tuberculosis control, improved resistance testing and surveillance, and the careful introduction of second-line drugs after a sound evaluation of cost, effectiveness, and feasibility.  相似文献   

Effect of site and storage conditions on quality of industrial fresh pepper     

Marcos Guerra  Ricardo Magdaleno  Pedro A. Casquero 《Scientia Horticulturae》2011

The commercial expansion of roasted pepper as a high market value product have made that the period of time in which canning industries process the fresh pepper fruits needs to be extended. Fresh sweet pepper (Capsicum annuum L.) destined for industry grown in different sites was cold stored in order to analyse the effect of different sites and storage conditions on the quality of the product at harvest and during storage. Storage during 10 days at 8 °C was the best storage condition to improve quality of pepper destined for industry, because colour was improved, weight loss (1–1.6%) was lower than maximum permissible and decay incidence was only between 0% and 2.3%. Harvest should be delayed until pepper reaches the red state in order to increase the quality of the fruit. However, these results suggest that pepper growers should assure a high content of Ca (>0.6 g kg⁻¹) in the soil to avoid a high incidence of decay during storage when a late harvest is needed to guarantee the enhancement of colour in pepper fruit destined for industry. These storage conditions are in accordance with those found to improve the sensory quality of roasted pepper.  相似文献   

Do mature pine plantations resemble deciduous natural forests regarding understory plant diversity and canopy structure in historically modified landscapes?     

Reyes Tárrega  Leonor Calvo  Ángela Taboada  Elena Marcos  José Antonio Marcos 《European Journal of Forest Research》2011,130(6):949-957

We compared the structure of the arboreal layer and the diversity and species composition of the understory vegetation of three types of mature forest communities: oak (Quercus pyrenaica) and beech (Fagus sylvatica) forests and Scots pine (Pinus sylvestris) plantations. Our main aim was to determine whether differences in these variables existed and were due to the identity of the dominant tree species. We selected four stands or replicates per forest type located geographically close and with relatively similar conditions. We found no differences in the arboreal structure of oak and beech forests, which were characterised by great variability in tree size, while in case of plantations, this variability was lower at both the intra-stand (estimated by the coefficient of variation) and inter-stand (i.e. the four replicates harboured trees of similar sizes) scales. However, the highest variability in the canopy layer of natural forests was not consistently linked to greater understory species richness. Indeed, the lowest plant species richness was found in beech forests, while oak forests harboured the highest value at either the sampling unit (per m²) or stand scales. The greatest negative correlation between plant diversity and the environmental variables measured was found for litter depth, which was the highest in beech forests. The results obtained by the CCA indicated that the four replicates of each forest type clustered together, due to the presence of characteristic species. We concluded that pine plantations did not approach the environmental conditions of native forests, as plantations were characterised by singular understory species composition and low arboreal layer variability, compared to natural woodlands.  相似文献   

Molecular and serological detection of Babesia spp. in neotropical and exotic carnivores in Brazilian zoos     

André MR  Adania CH  Teixeira RH  Allegretti SM  Machado RZ 《Journal of zoo and wildlife medicine》2011,42(1):139-143

Large and small piroplasms have been observed in the blood smears of various wild carnivores, but few studies utilizing molecular characterization have been done. The goal of this present study was to investigate the presence of Babesia sp. by molecular and serologic techniques in exotic and neotropical carnivores maintained in captivity at Brazilian zoos. Blood and sera samples were collected from 146 Brazilian wild felids, 21 exotic felids, 1 genet (Genetta tigrina), 3 European wolves (Canis lupus), and 94 Brazilian wild canids in Brazilian zoos in the S?o Paulo and Mato Grosso states and in the Federal District. A total of 53 wild felids (31.74%) and 10 wild canids (10.31%) were seropositive for Babesia canis by Indirect Fluorescent Antibody Test (IFAT). Antibodies were detected in ocelots, little-spotted cats, margays, pampas cats, jaguars, pumas, jaguarundis, crab-eating foxes, and bush dogs. Babesia sp. DNA, with high similarity to B. leo, was detected in one pampas cat and one genet.  相似文献   

Sampling strategy to develop a core collection of Uruguayan maize landraces based on morphological traits   总被引：4，自引：0，他引：4  

Marcos Malosetti  Tabaré Abadie 《Genetic Resources and Crop Evolution》2001,48(4):381-390

Core collections were suggested to improve germplasmutilization. A core collection is a subset chosen to represent thediversity of a collection with a minimum of redundancies. Becausediversity is distributed between and within groups with differentdegrees of organization, an adequate classification of accessionsinto related groups should be performed prior to the selection of acore collection. Different classification strategies for theUruguayan Maize Collection were compared, and the best one was usedto select a core collection. The following classification strategieswere compared following a multivariate approach using the availablemaize data base: i) racial classification, ii) geographicorigin (south and north of the country), and iii) acombination of kernel type and geographic origin. The third optionwas considered the best classification rule, since it takes intoaccount two points which are closely related to the distribution ofdiversity: genotypic composition and geographic origin. The followingfive groups were identified in the collection: a) pop, b)floury, c) dent, d) southern flint-semiflints, ande) northern flint-semiflints. Eight core collections,each of 90 accessions, were selected, using different strategies toweight the groups in the core and to select the accessions from thegroups. The P, C, and L strategies were used and combined with eitherrandom selection within the group or the Relative Diversity method.Two samples of 90 accessions were obtained at random withoutconsidering the classification. The Relative Diversity methodcombined with the L strategy produced the best core collection, as itretained the highest percentage of the ranges for the 17 variablesincluded in the analysis. On average, 91% of the ranges wereretained in the core, confirming its representativeness.  相似文献   

Biochemical and molecular analysis of carotenoid biosynthesis in flavedo of orange (Citrus sinensis L.) during fruit development and maturation   总被引：8，自引：0，他引：8  

Rodrigo MJ  Marcos JF  Zacarías L 《Journal of agricultural and food chemistry》2004,52(22):6724-6731

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Participation of Rhipicephalus sanguineus (Acari: Ixodidae) in the epidemiology of canine visceral leishmaniasis     

Coutinho MT  Bueno LL  Sterzik A  Fujiwara RT  Botelho JR  De Maria M  Genaro O  Linardi PM 《Veterinary parasitology》2005,128(1-2):149-155

The vectorial competence of the tick Rhipicephalus sanguineus is discussed in relation to the epidemiology of canine visceral leishmaniasis, taking into account its strict association with dogs and the low indices of natural infection presented by its known vector, the phlebotomine sand fly Lutzomyia longipalpis. In order to evaluate natural infection by Leishmania chagasi and the infectivity of these parasites in the tick, 39 specimens (6 females, 11 males and 22 nymphs) of R. sanguineus were removed from 21 dogs showing diverse symptoms of zoonotic visceral leishmaniasis (ZVL). Six ticks (15.4%) gave positive results for the genus Leishmania using the PCR technique. To determine the infectivity of the parasites, 36 hamsters were inoculated orally and peritoneally with macerates of ticks removed from nine dogs symptomatic for visceral leishmaniasis. After 6 months the hamsters were sacrificed and necropsied. Serum was removed for IFAT, as well as spleen and liver fragments to make imprint smears and for PCR. Eight (88.9%) of these dogs presented ticks that were infective for 14 hamsters (41.2%), 12 (85.7%) of them infected peritoneally and two (14.3%) orally. PCR revealed 27 smears (40.9%) to be positive, 20 (62.5%) of them infected peritoneally and seven (20.6%) orally. IFAT showed 14 positive animals (41.2%). Based on these findings, we suggest that the vectorial capacity of R. sanguineus for L. chagasi should be evaluated further, opening new perspectives in the epidemiology of ZVL.  相似文献   

Characterization of Ehrlichia ruminantium replication and release kinetics in endothelial cell cultures     

Marcelino I  Veríssimo C  Sousa MF  Carrondo MJ  Alves PM 《Veterinary microbiology》2005,110(1-2):87-96

Ehrlichia ruminantium is the causative agent of Heartwater, a fatal tick-borne disease affecting ruminants in African countries and West Indies and can be used as an inactivated vaccine for wild and domestic animals. In order to improve E. ruminantium production yields we characterize E. ruminantium growth kinetics in terms of duplication time, maximum production yield, and peak of infectivity. After a 24 h period for E. ruminantium attachment/internalization and a lag phase of 12 h, the exponential growth occurred within 36-108 h post-infection (hpi) with a net increase of up to 2.2 orders of magnitude. Maximum E. ruminantium infectivity was observed at 120 hpi and was defined as the best time of harvesting (TOH) for propagation of E. ruminantium cultures. This study showed that considering the quality constraint of the final product (E. ruminantium vaccine), the E. ruminantium suspension should be harvested at 113 hpi. Overall, the characterization of E. ruminantium progression through the average infection cycle, not only can contribute to the maximization of E. ruminantium production yield, with important consequences for the large scale production and utilization of an inactivated Heartwater vaccine, but also to elucidate growth mechanisms of some of the other ehrlichial species, with emerging impact in human and animal health.  相似文献