The Effects of Soil Solarization and Compost on Soil Suppressiveness against Fusarium Oxysporum f. sp. Melonis

Soil suppressiveness against Fusarium was tested using solarized and non-solarized soils combined with composts of three maturation levels, and a non-amended control. The soils were sampled on three dates: after previous year solarization but before current year solarization (0 weeks), at the end of the solarization period of the current year (4 weeks), and 4 weeks later (recovery time). Melon seedlings were inoculated with Fusarium spores and disease severity was assessed. The study showed a reduction of soil suppressiveness capacity against Fusarium oxysporum f. sp. melonis after 1 year of solarization (0 weeks). Fusarium disease severity in artificially inoculated melon plants, expressed by area under the disease progress curve, was higher in solarized soil than in non-solarized soil. Compost addition lowered the disease severity, both in the solarized and in the non-solarized soils. However, suppression was not obtained at the end of the solarization period, whereas compost beneficial effect was found at this time.     

Greenhouse gas emissions between 1993 and 2002 from land-use change and forestry in Mexico

In this paper we present the Mexican inventory of greenhouse gas (GHG) emissions from the land-use sector. It involved integration of forest inventory, land-use and soil data in a GIS to estimate the net flux of GHG between 1993 and 2002.     

Protection by polyphenols of postprandial human plasma and low-density lipoprotein modification: the stomach as a bioreactor

Recent studies dramatically showed that the removal of circulating modified low-density lipoprotein (LDL) results in complete prevention of atherosclerosis. The gastrointestinal tract is constantly exposed to food, some of it containing oxidized compounds. Lipid oxidation in the stomach was demonstrated by ingesting heated red meat in rats. Red wine polyphenols added to the rats' meat diet prevented lipid peroxidation in the stomach and absorption of malondialdehyde (MDA) in rat plasma. In humans, postprandial plasma MDA levels rose by 3-fold after a meal of red meat cutlets. MDA derived from meat consumption caused postprandial plasma LDL modification in human. The levels of plasma MDA showed a 75% reduction by consumption of red wine polyphenols during the meat meal. Locating the main biological site of action of polyphenols in the stomach led to a revision in the understanding of how antioxidants work in vivo and may help to elucidate the mechanism involved in the protective effects of polyphenols in human health.     

Spray Drying of Chitosan Acid Salts: Process Development,Scaling Up and Physicochemical Material Characterization

We investigated a spray drying process for preparing water-soluble salts of high molecular weight chitosan (CH) intended for pharmaceutical excipient applications. CH was derived from chitin of marine lobster origin (Panulirus argus). The effects of organic acid (acetic or lactic acid) and the ratio (difference) of inlet/outlet air temperature (140/90 °C or 160/100 °C) on spray drying were studied. The yield of spray-dried CH salt powders ranged from 50% to 99% in laboratory and industrial-scale processes. The spray-dried dry powder of CH salts consisted of spherical agglomerated particles with an average diameter of 36.2 ± 7.0 µm (CH acetate) and 108.6 ± 11.5 µm (CH lactate). After dispersing the spray-dried CH salt powder samples in purified water, the mean particle sizes obtained for the CH acetate salts were 31.4 nm (batch A001), 33.0 nm (A002) and 44.2 nm (A003), and for the CH lactate salts 100.8 nm (batch L001), 103.2 nm (L002) and 121.8 nm (L003). The optimum process conditions for spray drying were found: an inlet air temperature of 160 ± 5 °C, an outlet temperature of 100 ± 5 °C and an atomizer disk rotational speed of 18,200 min⁻¹. The X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) results confirmed the amorphous state of the CH salts. The ¹H nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectra of CH acetate and lactate salts verified that the spray drying process does not affect the polymer backbone. In conclusion, both laboratory and industrial-scale spray drying methods for preparing water-soluble acid salts of CH are reproducible, and the physicochemical properties of the corresponding CH acid salts are uniform.     

A quick methodology to identify sexual seedlings in citrus breeding programs using SSR markers

In citrus breeding and genetics, it is very important to distinguish between zygotic and nucellar seedlings in order to eliminate unwanted genotypes. Usually, isozyme marker shave been employed to determine the genetic origin of young plants. In this work we propose the use of SSR markers as an alternative methodology and compare them with isozymes in this kind of screenings. Two different populations were analysed: one derives from an interspecific cross and the other from selfing. We conclude that, in most cases, microsatellites are more efficient than isozymic markers to identify the sexual origin of citrus seedlings, given their higher level of polymorphism and the scarce number of polymorphic isozymes in some populations. We describe a quick and efficient methodology for SSR analysis, including a fast DNA extraction in microcentrifuge tubes, and visualization through silver staining, which eliminates the need for a labelling step. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Acidic Probe LysoSensor™ is not Useful for Acrosome Evaluation of Cryopreserved Ram Spermatozoa

To try new acrosomal probes for assessing ram spermatozoa, we compared the LysoSensor^? probe, which labels acidic organelles, with the frequently used peanut agglutinin acrosomal probe (PNA‐PE; phycoerythrin as fluorescent moiety). The previous microscopic observations showed a lack of relationship of LysoSensor^? with acrosomal status. Semen was obtained from five rams and frozen in four pools. Each pool was analysed carrying out a triple staining propidium ioide/PNA‐PE/LysoSensor^? Green DND‐189 to test acrosome labelling, and a double staining SYBR‐14/PI, to assess sperm viability. Stained samples were analysed by flow cytometry. All measurements were replicated. Data were processed using agreement and repeatability tests. LysoSensor^? labelling did not agree with PNA (mean of differences: 30.8%; coefficient of agreement: 22.6%), confirming microscopic observations. Nevertheless, when LysoSensor^? was compared with SYBR‐14/PI, the agreement was high (mean of differences: ?0.05%; coefficient of agreement: 5.07%). Repeatability of both methods was high and similar. LysoSensor^? did not seem to specifically stain the acrosome, but it may accumulate in the cytoplasm and label viable spermatozoa. Therefore, LysoSensor^? might not be used as an acrosomal probe in ram spermatozoa, but it could be used in other kind of studies, taking advantage of its pH sensitivity.     

Potato germplasm development for warm climates: genetic enhancement of tolerance to heat stress

Complex potato hybrids were derived through unilateral sexual polyploidization between Solanum tuberosum cv. Atlantic and 11 diploid hybrids that produced 2n pollen through co-orientation of second division spindles. The hybrids represented the following genomic compositions: TAPB, TAPC, and TAPM where T = S. tuberosum, A = S. andigena, P = S. phureja, B = S. berthaultii, C = S. chacoense, and M = S. microdontum. The B, C, and M components of the hybrids had been selected from heat tolerant accessions. The heat tolerance and agronomic performance of the hybrids were assessed under both controlled environments and field tests. The hybrids exhibited good tuberization potential (tuber number, tuber weight and percent plants producing tubers) under heat stress conditions in controlled environments. Under severe heat stress conditions in the field in Israel, many of the hybrids tuberized when Atlantic failed to produce any tubers at all. Under more moderate heat stress in Virginia, the complex hybrids exhibited total tuber yield not significantly different from Atlantic, although the tuber set per plant was greater. However, the complex hybrids were more tolerant to heat necrosis and hollow heart than Atlantic. Total glycoalkaloids in field-grown tubers did not exceed the acceptable limit for 13 of 26 selections examined. This revised version was published online in July 2006 with corrections to the Cover Date.     

Circulating immune complexes in bovine leukemia virus (BLV)-infected cattle.

Circulating immune complexes (ICs) were detected in the sera of bovine leukemia virus (BLV)-seropositive cattle. Immune complexes were precipitated in 2.5% polyethylene glycol (PEG) and further dissociated. Bovine leukemia virus antigens, IgG and IgM molecules were detected after solubilization in the presence of sodium dodecyl sulphate, and quantitated by enzyme-linked immunosorbent assay (ELISA) assays. Mean values of IgG and IgM in BLV-containing ICs did not significantly differ from those obtained from ICs originating from BLV-seronegative animals. However, differences were found in the composition of ICs from older BLV-positive animals as compared to those obtained from young animals. The ratio of IgG/IgM was 5.02 in animals aged 5-10 years, while this ratio was 11.66 in animals of less than 5 years of age and 10.19 in controls. This might indicate a possible increase in the contribution of IgM molecules to the structural composition of ICs in BLV-infected cattle as related to age or stage of infection.