Ontogeny and total sugar content of yacon tuberous roots and other three Smallanthus species (Heliantheae,Asteraceae), insights on the development of a semi-domesticated crop

The ontogeny of the tuberous roots of yacon (Smallanthus sonchifolius), an ancient Andean crop, is described for the first time along with three other wild species of Smallanthus: S. connatus, S. macroscyphus and S. siegesbeckius. Tuberous storage roots are present in the four species. Tuberization results from unusual secondary thickening. A meristematic endodermis maintains the primary cortex by generating cortex cells continuously. Secretory schizogenous canals develop adjacent to the endodermis in opposition to the phloem poles. Phellogen originates in the outer layers of the parenchymatic cortex. The four species develop a parenchymatous pith that stores mainly fructooligosacharides (FOS) and plays an important role in storing water, protecting the plant from drought stress and environmental hazards in the Andean climate. In yacon, domestication has produced a wide pith that stores water, reducing sugars and FOS with low degree of polimerization, that could have eventually made it more palatable as compared to the wild counterparts.     

Physicochemical changes in the hull of corn grains during their alkaline cooking

The alkaline cooking of corn in a solution of Ca(OH)2 to produce corn-based foods is oriented to make corn proteins available, to incorporate Ca to the cooked grains, and also to remove the corn hull. This process (nixtamalization) is known in Mexico and Guatemala from prehispanic times; however, the effect of the alkaline cooking on the corn hull remains poorly documented. In this work, the physicochemical changes that take place in the corn hull during its cooking in a saturated solution of Ca(OH)2 were studied using infrared, X-ray diffraction, 13C cross-polarization/magic-angle spinning (CP/MAS) NMR, confocal imaging microscopy, differential scanning calorimetry, and thermogravimetry techniques. The main effect of this treatment on the hull is the removal of hemicelluloses and lignin, increasing the hull permeability and, as a consequence, facilitating the entry of the alkaline solution into the corn kernel. No significant changes were observed in the cellulose fiber network, which remains as native cellulose I, with a crystalline index, according to 13C CP/MAS NMR spectra, of 0.60. The alkaline treatment does not allow the cellulose fibers to swell and their regeneration in the form of cellulose(II). It seems any attempt to make use of the Ca binding capacity of the hull to increase the Ca availability in nixtamalized corn-based foods requires a separated treatment for the hull and kernel. On alkaline cooking, the hull hemicellulose fraction dissolves, losing its ability to bind Ca as a way to incorporate this element into foods elaborated from nixtamalized corn.     

Mungbean [Vigna radiata (L.) Wilczek] globulins: purification and characterization

Vicilin type (8S) and basic 7S globulins and legumin type (11S) globulins were isolated from mungbean [Vigna radiata (L.) Wilczek]. The native molecular weights of the different globulin types were 360000 for legumin, 200000 for vicilin, and 135000 for basic 7S. Some of the 8S globulin apparently complexed and coeluted with the 11S on gel filtration. On SDS-PAGE, 11S was composed of two bands of 40000 and 24000, 8S was composed of 60000, 48000, 32000, and 26000 bands, and basic 7S was composed of 28000 and 16000 bands. The percent composition of total globulins was estimated to be as follow: 8S, 89%; basic 7S, 3.4%; and 11S, 7.6%. The basic 7S and 11S but not the 8S globulins were found to have disulfide bonds. The presence of carbohydrates by conjugated peroxidase reaction was observed in all bands of 8S, the acidic polypeptide of basic 7S, and its complex but not in 11S. The 28000 basic 7S band and its 42000 complex and the first three major bands of 8S cross-reacted with antibodies to all types of soybean conglycinin subunits (alpha, alpha', and beta), whereas the fourth band cross-reacted only with the anti-beta subunit. None of the mungbean globulins cross-reacted with anti-soybean glycinin. Basic 7S was found to be easily extracted with 0.15 M NaCl, 11S was extracted with 0.35 M NaCl,and 8S was extracted over a wide range of NaCl concentrations. The N-terminal sequences of the different subunits/fragments of the globulins were determined and found to have strong homology with storage proteins of other legumes and crops.     

Biodiversity conservation in human-modified landscapes of Mesoamerica: Past, present and future

Mesoamerica provides a unique context for biodiversity conservation in managed landscapes because of its geography, history of human intervention, and present conservation and development initiatives. The long and narrow form of the Mesoamerican landmass, and its division by a central mountain range, has served as both a bridge and a barrier. Conservation efforts in Mesoamerica are unique for the emphasis they place on regional connectivity through the Mesoamerican Biological Corridor and on biodiversity conservation in managed landscapes. The emphasis on conservation in agricultural systems has fostered innovations in payment for ecosystem services, and provides novel insights on the functional role that biodiversity plays in the provisioning of ecosystem services. The increasing rate of economic development in the region and the advent of new payment for ecosystem service schemes have provided new opportunities for forest regeneration and restoration. However, the small scale of private landholdings and the diversity of land uses featured in the region, while contributing to biodiversity conservation due to their structural and floristic complexity, present challenges for biodiversity monitoring and management.     

Coriander essential oil composition from two genotypes grown in different environmental conditions

The objective was to study the essential oil composition of coriander fruits in plants growing in environments differing in soil conditions and weediness level. Factorial field experiments were conducted in two locations from the Rolling Pampas, Argentina, and two coriander landraces (European and Argentinean) were tested under two levels of nitrogen fertilization and weediness. Data were evaluated with uni- and multivariate techniques. The variation in the oil composition was related to the relative proportion of the constituents and not to the presence/absence of a particular component. Weather conditions in 1997 favored linalool and camphor in both landraces. Location, fertilization, and weediness also affected the chemical profile. The European landrace showed a more stable concentration of the major components than the Argentinean landrace. These results, which show the relationships between some environmental conditions and the essential oil composition, are useful in the development of innovative strategies aimed to improve oil composition and to manage crop pests.     

Influence of Salinity in the Bioavailability of Zn in Sediments of the Gulf of Cádiz (Spain)

This study assesses the effect of salinity in bioavailability and toxicity of Zn by means of laboratory bioassays by observing contamination in both sediment and water, accumulation of Zn in biological tissues, and histopathological damage in the gills and guts tissues of Ruditapes philippinarum clams, which were exposed to different types of sediments from the Gulf of Cádiz (SW Spain) as well as two dilutions of toxic mud coming from an accidental mining spill. With this objective, the coefficients of distribution (K _D) for Zn between overlying water and sediments were calculated, the histopathological frequencies in the tissues of the gills and guts of clams were determined, and the biota-sediment bioaccumulation factors as well as the bioaccumulation factors were quantified in the different stations. Results showed that the greatest histopathological damages appeared when the salinity values decreased. Statistical results showed that salinity was inversely correlated with histopathological damage (p?<?0.01) for the lesion index for gills. The most outstanding results were observed in the two dilutions of toxic mud (0.3% and 7.9%) at a salinity value of 10. Salinity was inversely correlated with the concentration of Zn in biological tissues (p?<?0.05) and inversely correlated with the concentration of Zn in water and sediment. Zn mobilization to the overlying water is produced when salinity values decrease.     

Inoculation of wheat with Azospirillum brasilense and Pseudomonas fluorescens: Impact on the production and culturable rhizosphere microflora

Scientific evidence recognizes that the operation of a terrestrial ecosystem depends on soil microbial activity. Some Azospirillum strains produce plant growth regulators, increase the development of roots, and fix atmospheric nitrogen (N₂). Some Pseudomonas strains are capable of producing cytokinins and solubilizing organic phosphorus. A sustainability analysis requires a detailed knowledge of the interrelationships between the microorganisms added to the system and those present in the soil. This study examines the effect of three commercial inoculants Azospirillum brasilense Az1 and Az2 as well as Pseudomonas fluorescens Pf on biomass production, grain yield and rhizosphere colonization of wheat, combined with two levels of N-addition. Plate counts of rhizosphere soil showed that the inoculation and N-addition did not affect the number of P. fluorescens, whereas it significantly affected the number of Azospirillum. N-addition and inoculation did not change the communities of actinomycetes and bacteria but they changed the number of fungi at the rhizosphere of wheat plants. Community-level physiological profiles of carbon-source utilization of rhizosphere soil microbial communities were changed after inoculation with Az1, Az2 and Pf depending on the phenological stage of the crop. Although no significant responses were observed, in average, PGPB inoculation increased aerial biomass by 12%, root biomass by 40% and grain yield by 16%. These increases represent important earnings for the farmer and they may help to obtain a greater sustainability of the agroecosystems.     

First report of Enterocytozoon bieneusi from dairy cattle in Argentina

Fecal specimens were obtained from a total of 70 dairy calves less than two months old on 11 municipalities in Buenos Aires, Argentina. After removal of fecal debris by sieving and sucrose flotation, specimens were subjected to PCR to detect the presence of Enterocytozoon bieneusi. PCR revealed a 14.3% of prevalence for E. bieneusi with 10 positive calves from 7 municipalities. Gene sequence analysis conducted in all samples positives by PCR revealed the presence of six genotypes; four previously reported in cattle as well as humans (D, I, J, and BEB4), one never reported in cattle before but previously reported in humans (EbpC), and one novel genotype (BEB10). These results constitute the first molecular characterization of E. bieneusi in Argentina, and suggest a potential risk of zoonotic transmission in this area.     

ADVERSE EFFECTS OF HUMIC SUBSTANCES FROM DIFFERENT ORIGIN ON LUPIN AS RELATED TO IRON SOURCES

Humic substances improve the efficiency of different iron (Fe) sources overcoming Fe deficiency chlorosis of plants. However, applied at high rates, they can promote negative effects on plants. The main objective of this work was to study the potential adverse effect of three humic acids from different origin when they were applied with two effective Fe sources for plants: Fe- ethylenediaminedihydroxyphenylacetic acid (EDDHA) and Vivianite. To this end, an experiment with lupin (Lupinus albus L.) was performed involving two factors: (i) Fe source, and (ii) humic substances from three different origin (composted cork, leonardite, and compost obtained from a mixture of olive husk with cotton gin trash) applied at 0, 0.1, and 0.5 g organic carbon (C) kg^?1 of growing media. At the rates used, humic substances promoted adverse effects on plant development, chlorophyll meter readings, and Fe content in lupin grown in calcareous media. Overall, the effect on dry matter and Fe content in plants was more relevant when Fe was supplied with Vivianite, the effect on chlorophyll meter readings being more significant when Fe was applied as Fe-EDDHA. Differences were also observed depending on the source of humic substances, those from leonardite promoting the greatest decrease in dry matter in roots and shoots. These humic substances possessed the highest values of spectroscopy index for aromaticity (A₂₅₄ ). On the other hand, the application of humic substances from olive husk compost, which exhibited the lower aromaticity index, resulted in the smallest decrease in dry matter production and chlorophyll meter readings. Dry matter in roots decreased logarithmically with increased values of the estimates of the amounts of aromatic compounds accumulated in the growing media (R² = 0.92; P < 0.01) with Vivianite as Fe source. Thus, the effects decreasing dry matter production, particularly in roots, and chlorophyll meter readings can be ascribed at least partially to the presence of phytotoxic aromatic compounds in humic substances.     

Effect of the US3 protein of bovine herpesvirus 5 on the actin cytoskeleton and apoptosis

The US3 protein is a unique protein kinase only present in the Alphaherpesvirinae subfamily of the herpesviruses. Studies performed with several alphaherpesviruses demonstrated that the US3 protein is involved in cytoskeleton modifications during viral infection and displays anti-apoptotic activity. However, the US3 protein of BoHV-5 has not been studied up to now. As reported for other alphaherpesviruses, our results showed that BoHV-5 US3 confers resistance against apoptosis and induces cytoskeletal reorganization leading to cell rounding, actin stress fiber breakdown and cell projections that interconnect cells. The expression of a kinase-dead version of BoHV-5 US3 showed that the anti-apoptotic activity and the induction of cell projections are kinase-dependent whereas kinase activity is not absolutely required for actin stress fiber breakdown. Besides, the kinase-dead version of US3, but not the wild type protein, was found excluded from the nucleus. These results constitute the first report on the BoHV-5 US3 functions, and highlight that there are functional differences and similarities among US3 proteins of different alphaherpesviruses.