Globally, plant-soil feedbacks are weak predictors of plant abundance

Plant-soil feedbacks (PSFs) have been shown to strongly affect plant performance under controlled conditions, and PSFs are thought to have far reaching consequences for plant population dynamics and the structuring of plant communities. However, thus far the relationship between PSF and plant species abundance in the field is not consistent. Here, we synthesize PSF experiments from tropical forests to semiarid grasslands, and test for a positive relationship between plant abundance in the field and PSFs estimated from controlled bioassays. We meta-analyzed results from 22 PSF experiments and found an overall positive correlation (0.12 ≤  r ¯  ≤ 0.32) between plant abundance in the field and PSFs across plant functional types (herbaceous and woody plants) but also variation by plant functional type. Thus, our analysis provides quantitative support that plant abundance has a general albeit weak positive relationship with PSFs across ecosystems. Overall, our results suggest that harmful soil biota tend to accumulate around and disproportionately impact species that are rare. However, data for the herbaceous species, which are most common in the literature, had no significant abundance-PSFs relationship. Therefore, we conclude that further work is needed within and across biomes, succession stages and plant types, both under controlled and field conditions, while separating PSF effects from other drivers (e.g., herbivory, competition, disturbance) of plant abundance to tease apart the role of soil biota in causing patterns of plant rarity versus commonness.

Anisakis simplex, a relevant etiologic factor in acute urticaria

Anisakis simplex, a parasite of fish and cephalopods, can induce IgE-mediated reactions. This study aimed to determine the etiologic role of A. simplex in patients affected by urticaria/angioedema (AE) or anaphylaxis. We studied 100 adult subjects suffering acute episodes of urticaria/AE, by anamnesis, prick tests with A. simplex and fish-mix extracts, and total and specific IgE to both A. simplex and cod. The following criteria of A. simplex allergy were considered: 1) urticaria/AE within 6 h after fish ingestion; 2) specific IgE to A. simplex; 3) positive prick test to A. simplex extract; 4) exclusion of other suspected causes. Double-blind, placebo-controlled food challenge was not carried out because ethical considerations forbid challenge with a parasite. Specific IgE to A. simplex (> 0.7 kU/l) was found in 22 subjects, but only eight were diagnosed as having A. simplex allergy. Other allergens were involved in 37 patients, and 55 cases were considered idiopathic. Specific IgE to fish (> 0.7 kU/l) was found in two patients, but only one was diagnosed as having fish allergy. We concluded that A. simplex is an important etiologic factor in acute urticaria. We suggest that it should be considered in cases of urticaria/AE or anaphylaxis, especially after fish ingestion.

Use of the colonic carcinoma cell line CaCo-2 for in vivo amplification and detection of enteric viruses

The use of the continuous cell line CaCo-2 as an in vivo amplification system for the detection of fastidious human enteric viruses is reported. CaCo-2 cells showed an increased sensitivity to laboratory strains of group A rotavirus 3, reovirus 3, astrovirus 1, poliovirus 1, coxsackievirus A 24, enterovirus 70, and adenovirus 5, 40 and 41, when compared to a routine host cell line for each virus. Nucleic acids from wild-type infectious rotavirus, astrovirus, and adenovirus 40 in stool samples of patients with acute gastroenteritis could be amplified after infection of CaCo-2 cells with trypsin-pre-treated virus inocula. Virus diagnosis was carried out subsequently by dot-blot hybridisation with specific cDNA probes. An amplification factor between 10 and 1,000x was obtained by infection of CaCo-2 cells, thus enabling specific detection of low numbers of a wide range of enteric viruses, and the differentiation between infectious and noninfectious particles.

Disinfection of human enteric viruses in water by copper and silver in combination with low levels of chlorine

The efficacy of copper and silver ions, in combination with low levels of free chlorine (FC), was evaluated for the disinfection of hepatitis A virus (HAV), human rotavirus (HRV), human adenovirus, and poliovirus (PV) in water. HAV and HRV showed little inactivation in all conditions. PV showed more than a 4 log10 titer reduction in the presence of copper and silver combined with 0.5 mg of FC per liter or in the presence of 1 mg of FC per liter alone. Human adenovirus persisted longer than PV with the same treatments, although it persisted significantly less than HRV or HAV. The addition of 700 micrograms of copper and 70 micrograms of silver per liter did not enhance the inactivation rates after the exposure to 0.5 or 0.2 mg of FC per liter, although on some occasions it produced a level of inactivation similar to that induced by a higher dose of FC alone. Virus aggregates were observed in the presence of copper and silver ions, although not in the presence of FC alone. Our data indicate that the use of copper and silver ions in water systems may not provide a reliable alternative to high levels of FC for the disinfection of viral pathogens. Gene probe-based procedures were not adequate to monitor the presence of infectious HAV after disinfection. PV does not appear to be an adequate model viral strain to be used in disinfection studies. Bacteroides fragilis bacteriophages were consistently more resistant to disinfection than PV, suggesting that they would be more suitable indicators, although they survived significantly less than HAV or HRV.

Comparison of immunological and molecular hybridization detection methods for the detection of hepatitis A virus in sewage

Immune electron microscopy (IEM), radioimmunoassay (RIA) and molecular hybridization with a digoxigenin-labelled cDNA probe were compared for the detection of wild-type human hepatitis A virus (HAV) in raw and treated sewage. In the same experiments, classic tests for culturable enteroviruses were carried out. With the hybridization probes, HAV was detected in three of the 13 affluent samples (23%) and in eight out of 13 effluent samples (61%). For four of the effluent samples, positivity revealed by IEM was confirmed by the cDNA probe. In contrast, two of the samples shown as positive by IEM were negative with the probes. Detection of HAV by RIA was negative in all cases. Demonstration of HAV was higher in effluent than in affluent. No particular relationship was established between demonstration of HAV, on the one hand, and the various concentrations of enteroviruses observed in the same samples on the other. Overall, if all the results, irrespective of the type of water (affluent or effluent), are taken together, 50% of the sewage samples tested were found to contain HAV by one or another method of detection.

Serum iron, serum ferritin and tissue ferritin during development in ducks

Serum ferritin and tissue ferritin from kidney, heart, small intestine, spleen and liver from ducks during development from 16 to 112 days of age were measured by radioimmunoassay using rabbit anti-duck liver ferritin antibodies and goat second antibody. Serum iron concentration and tissue ferritin iron content are given. Serum ferritin concentration, tissue ferritin and ferritin iron content increase gradually during development. The decrease in all these parameters at 8 weeks of age might be due to molting.