The global eradication of poliomyelitis: progress and problems

Encouraged by the success of the global smallpox eradication certified in 1980, the global poliomyelitis eradication program was launched in 1988 by the World Health Organization (WHO). In addition to routine polio immunization included in the Expanded Program of Immunization (EPI), two major activities were planned: mass polio vaccination campaigns and surveillance of all cases of acute flaccid paralysis. In 2000, the disease had been eliminated from most countries in the world. However, as of 2002, the community acceptance of vaccination was endangered in some countries by rumors about assumed adverse effects of oral polio vaccine. The rejection of polio immunization provided a worrying resurgence of polio in Northern Nigeria, followed by re-infection of 21 countries, whereas resurgence of the disease also was observed in Northern India. Supplementary vaccination activities were resumed, additional resources were mobilized and, in 2007, most re-infected countries became polio-free again. Today, polio remains endemic in only four countries. The goal of global polio eradication has now been set at 2010, but doubts have been expressed about the feasibility of its achievement.     

Treatment with the Mycoparasite Pythium oligandrum Triggers Induction of Defense-Related Reactions in Tomato Roots When Challenged with Fusarium oxysporum f. sp. radicis-lycopersici

ABSTRACT The influence exerted by the mycoparasite Pythium oligandrum in triggering plant defense reactions was investigated using an experimental system in which tomato plants were infected with the crown and root rot pathogen Fusarium oxysporum f. sp. radicis-lycopersici. To assess the antagonistic potential of P. oligandrum against F. oxysporum f. sp. radicis-lycopersici, the interaction between the two fungi was studied by scanning and transmission electron microscopy (SEM and TEM, respectively). SEM investigations of the interaction region between the fungi demonstrated that collapse and loss of turgor of F. oxysporum f. sp. radicis-lycopersici hyphae began soon after close contact was established with P. oligandrum. Ultrastructural observations confirmed that intimate contact between hyphae of P. oligandrum and cells of the pathogen resulted in a series of disturbances, including generalized disorganization of the host cytoplasm, retraction of the plasmalemma, and, finally, complete loss of the protoplasm. Cytochemical labeling of chitin with wheat germ agglutinin (WGA)/ovomucoid-gold complex showed that, except in the area of hyphal penetration, the chitin component of the host cell walls was structurally preserved at a time when the host cytoplasm had undergone complete disorganization. Interestingly, the same antagonistic process was observed in planta. The specific labeling patterns obtained with the exoglucanase-gold and WGA-ovomucoid-gold complexes confirmed that P. oligandrum successfully penetrated invading cells of the pathogen without causing substantial cell wall alterations, shown by the intense labeling of chitin. Cytological investigations of samples from P. oligandrum-inoculated tomato roots revealed that the fungus was able to colonize root tissues without inducing extensive cell damage. However, there was a novel finding concerning the structural alteration of the invading hyphae, evidenced by the frequent occurrence of empty fungal shells in root tissues. Pythium ingress in root tissues was associated with host metabolic changes, culminating in the elaboration of structural barriers at sites of potential fungal penetration. Striking differences in the extent of F. oxysporum f. sp. radicis-lycopersici colonization were observed between P. oligandrum-inoculated and control tomato plants. In control roots, the pathogen multiplied abundantly through much of the tissues, whereas in P. oligandrum-colonized roots pathogen growth was restricted to the outermost root tissues. This restricted pattern of pathogen colonization was accompanied by deposition of newly formed barriers beyond the infection sites. These host reactions appeared to be amplified compared to those seen in nonchallenged P. oligandrum-infected plants. Most hyphae of the pathogen that penetrated the epidermis exhibited considerable changes. Wall appositions contained large amounts of callose, in addition to be infiltrated with phenolic compounds. The labeling pattern obtained with gold-complexed laccase showed that phenolics were widely distributed in Fusarium-challenged P. oligandrum-inoculated tomato roots. Such compounds accumulated in the host cell walls and intercellular spaces. The wall-bound chitin component in Fusarium hyphae colonizing P. oligandrum-inoculated roots was preserved at a time when hyphae had undergone substantial degradation. These observations provide the first convincing evidence that P. oligandrum has the potential to induce plant defense reactions in addition to acting as a mycoparasite.     

Presence of Shiga toxin-producing E. coli O157:H7 in a survey of wild artiodactyls

This study was carried out to evaluate the role of wild artiodactyls as reservoirs of Escherichia coli O157:H7 for livestock and humans. Retroanal mucosal swabs samples from 206 red deer (Cervus elaphus), 20 roe deer (Capreolus capreolus), 6 fallow deer (Dama dama) and 11 mouflon (Ovis musimon), collected during the hunting season (autumn-winter) in South-western Spain, were screened. Samples were pre-enriched in modified buffered peptone water, concentrated by an immunomagnetic separation technique and cultured onto selective cefixime tellurite sorbitol MacConkey agar. Polymerase chain reaction (PCR) was used to detect the presence of genes coding O157 and H7 antigens and the virulence factors verocytotoxin, intimin and enterohaemolysin. Three E. coli O157:H7 isolates were obtained from red deer (1.5%). Two of them showed inability to ferment sorbitol and lack of beta-d-glucuronidase (GUD) activity, however, the other strain investigated was an atypical sorbitol-fermenting E. coli O157:H7 with GUD(+) activity. This is the first report pointing to red deer as a reservoir of E. coli O157:H7 in Spain.     

Effect of temperature and moisture on rates of carbon mineralization in a Mediterranean oak forest soil under controlled and field conditions

We examined the relationship between carbon mineralization (C_min), moisture and temperature in a Mediterranean forest soil under controlled and field conditions. We studied the following. 1 The temperature sensitivity at three soil depths: soil samples were incubated at 4, 10, 20 and 30°C at optimal water content of 60% of water holding capacity (WHC). Values of C_min of the top layer were more than 12 times faster than those measured in deeper layers. We found a temperature sensitivity factor (Q₁₀) of 3.3, 2.7 and 2.2 for the 0–5 cm, 5–10 cm and 10–20 cm layers, respectively. 2 The relationship between C_min, moisture and temperature (top layer). The sensitivity of C_min to fluctuating moisture depended on temperature. However, the Q₁₀ was not significantly affected by soil moisture. We fitted a multiple polynomial model that predicted C_min as a multiplicative function of temperature and moisture (R² > 0.99). 3 The response of C_min of soil to rewetting after 1 and 24 hours. In all cases, the response was rapid. The soil incubated at 60% WHC or less responded positively to a sudden increase in water content, with the largest increase in the 20% WHC treatment. The model predicted C_min in the field well when rewetting effects were taken into account (R² > 0.81). These results indicate that sudden changes in soil moisture can lead to increased carbon mineralization during the dry summer. It is necessary to include such responses in models as they may represent a substantial loss of carbon in the overall carbon balance of Mediterranean ecosystems.     

New Saccharomyces cerevisiae baker's yeast displaying enhanced resistance to freezing

Three procedures were used to obtain new Saccharomyces cerevisiae baker's yeasts with increased storage stability at -20, 4, 22, and 30 degrees C. The first used mitochondria from highly ethanol-tolerant wine yeast, which were transferred to baker's strains. Viability of the heteroplasmons was improved shortly after freezing. However, after prolonged storage, viability dramatically decreased and was accompanied by an increase in the frequency of respiratory-deficient (petite) mutant formation. This indicated that mitochondria were not stable and were incompatible with the nucleus. The strains tested regained their original resistance to freezing after recovering their own mitochondria. The second procedure used hybrid formation after protoplast fusion and isolation on selective media of fusants from baker's yeast meiotic products resistant to parafluorphenylalanine and cycloheximide, respectively. No hybrids were obtained when using the parentals, probably due to the high ploidy of the baker's strains. Hybrids obtained from nonisogenic strains manifested in all cases a resistance to freezing intermediate between those of their parental strains. Hybrids from crosses between meiotic products of the same strain were always more sensitive than their parentals. The third method was used to develop baker's yeast mutants resistant to 2-deoxy-d-glucose (DOG) and deregulated for maltose and sucrose metabolism. Mutant DOG21 displayed a slight increase in trehalose content and viability both in frozen doughs and during storage at 4 and 22 degrees C. This mutant also displayed a capacity to ferment, under laboratory conditions, both lean and sweet fresh and frozen doughs. For industrial uses, fermented lean and sweet bakery products, both from fresh and frozen doughs obtained with mutant DOG21, were of better quality with regard to volume, texture, and organoleptic properties than those produced by the wild type.     

Analyses of seven new whole genome sequences of cassava brown streak viruses in Mozambique reveals two distinct clades: evidence for new species

Cassava brown streak disease (CBSD) caused by Cassava brown streak virus (CBSV) and Uganda cassava brown streak virus (UCBSV) is a major constraint to cassava production in Mozambique. Full genome sequences of CBSD-associated virus isolates contribute to the understanding of genetic diversity and the development of new diagnostic primers that can be used for early detection of the viruses for sustainable disease management. This study determined seven new whole CBSV genomes from total RNA isolated from cassava leaves with CBSD symptoms collected from Nampula and Zambezia in Mozambique. Phylogenetic analyses of the new genomes with published CBSV and UCBSV sequences in GenBank grouped the CBSV isolates from Mozambique into two distinct clades together with CBSV isolates from Tanzania. Clade 1 and 2 isolates shared low nucleotide (79.1–80.4%) and amino acid (86.5–88.2%) sequence identity. Further, comparisons within the seven new CBSV isolates, and between them and the single published complete CBSV sequence (CBSV_MO_83_FN434436) from Mozambique, revealed nucleotide sequence identities of 79.3–100% and 79.3–98%, respectively, and amino acid identities of 86.7–100% and 86.7–98.8%. In addition, using RDP4, a recombination analysis comprising all CBSV and UCBSV genome sequences from GenBank detect 11 recombination events. Using several comprehensive evolutionary models and statistical programs, it was confirmed that CBSV and UCBSV are distinct virus species, with an additional probable new species (clade 2).     

Genetic diversity of <Emphasis Type="Italic">Patellifolia patellaris</Emphasis> from the Iberian Peninsula,a crop wild relative of cultivated beets

The genetic diversity of Patellifolia patellaris has been investigated to generate information required for the organisation of a systematic genetic resources conservation action combining the best elements of the ex situ and in situ conservation concept. To this end, ten occurrences of the species were sampled on the Iberian Peninsula in Portugal and Spain. A total of 271 individuals was analysed using 24 microsatellite markers. The factorial analysis separated the material into two occurrences from Portugal, two occurrences sampled east of Gibraltar and six occurrences from the eastern Spanish coast. The pairwise genetic distance between occurrences and the complementary compositional differentiation among occurrences were calculated. The genetic distance values were used to construct an Unweighted Pair Group Method with Arithmetic Mean tree, which can be separated into four equidistant clusters. Two clusters are located in Portugal and two further clusters in Spain. The factorial analysis as well as the genetic distance and differentiation analysis indicate that the two occurrences from Portugal are clearly genetically different from the Spanish group of occurrences. Both occurrences have low population sizes and are therefore highly endangered. In situ conservation actions are urgently required for both occurrences. Further investigations are needed to organise better informed conservation actions for P. patellaris, namely to study genetic relationships between occurrences on the Spanish mainland and occurrences distributed on the Canary Islands, Madeira and Cape Verde Islands as well as in Morocco.     

A disease and production index (DPI) for selection of cacao (Theobroma cacao) clones highly productive and tolerant to pod rot diseases

Frosty pod rot (FPR) (Moniliophthora roreri), along with black pod rot (Phytophthora species) and witches’ broom disease (Moniliophthora perniciosa) constitute the main phytosanitary problems limiting cacao (Theobroma cacao) production causing severe yield losses. One of the main sought after methods of pod rot management is the selection of tolerant cacao genotypes. Typically, the selection is carried out through the quantification of the percentage of diseased pods (PDP). However, PDP does not consider the relative productivity, or production potential (PT) of the genotype. Production potential can vary among cacao genotypes. Consequently, genotypes with similar PT can have similar or vastly different disease tolerance levels as measured by PDP. The disease and production index (DPI) was developed to integrate a genotype's tolerance to M. roreri and other diseases as measured by PDP, with its PT. Here, we evaluated the number of healthy pods, number of diseased pods, and weight of fresh seed for 29 clones grown in replicated five-tree plots over 4 years. The data obtained was used to calculate PDP and DPI for each clone for three different disease combinations: frosty pod rot alone, pod rots other than frosty pod rot, and the combination of all pod rots. Multivariate analysis verified that DPI discriminated between clones based on productivity and disease tolerance. Surprisingly, there was a close ranking of clones between resistance to FPR and resistance to all other pod rots. The DPI can be used in breeding programmes focused on the selection of high yielding disease-tolerant cacao genotypes.     

Application of Molecular Marker-Assisted Selection (MAS) for Disease Resistance in a Practical Potato Breeding Programme

The company Appacale started applying molecular markers in 1998 with the implementation of RYSC3 marker of resistance to Potato virus Y (PVY). Since then, five more molecular markers have been implemented, and now it is possible to select for PVY, Globodera rostochiensis and Globodera pallida resistance with this technology. The markers used have allowed the selection of breeding clones with resistance to one or more pathogens that are currently part of the breeding programme, new cultivars or even being used as resistant parents. The results obtained are presented, as well as the advantages and setbacks found in applying Molecular-Assisted Selection from the point of view of a practical breeding programme developed in a small company.     

Sustainability of tropical dry forests: Two case studies in southeastern and central Brazil

In this study, we review the current available information on the social–ecological context of Brazilian tropical dry forests (TDFs), a vegetation type that covers approximately 3% of the country territory. For this purpose, we conducted a comparative analysis of two case studies, one study in the north of Minas Gerais state and the other in Paranã River Basin, situated in southeastern and central Brazil, respectively. We compiled published bibliographical and census-based data for the two regions, concerning the historical human occupation and land use and the environmental and development policies affecting TDF management and sustainable use. Brazilian TDFs usually occur in semi-arid climates, and have been intensely converted mainly to extensive pasturelands in large farms, thus leading to high income concentration in those areas. Our case studies involve less-developed regions that support populations with very low human development indices, which is the norm for Brazilian TDFs. Many of these are traditional populations, such as indigenous and slave descendents, with peculiar cultural practices only recently considered in government policies proposed for the forest management. Though the two regions have similar land use histories, current social–ecological scenarios are very different. In the north of Minas Gerais, TDF conversion policies were debated intensely for the last 15 years, recently resulting in a state law specifically generated to regulate TDF use. Also, this region has 20 conservation units (CUs), some of them delimited inside the territories of the several traditional populations that inhabit TDF areas. This process caused enduring conflicts that can affect both CUs’ effectiveness and the sustenance of these populations. In the Paranã River Basin, there is no specific policy towards TDFs, whose use is regulated by the 43-year-old Brazilian Federal Forest Code. There are only four CUs in this region, and most traditional populations were expelled from their original territories and consequently lost their cultural identity. Government sustainability strategies are limited to the establishment of CUs, a response that may disregard social demands and cultural practices, depending on the local context. Given the uniqueness and threat level to TDFs, specific and more diversified policies towards land use should be established for these ecosystems in order to stimulate low-impact activities that maintain ecosystem services and improve the livelihoods of TDF inhabitants.