Is zinniol a true phytotoxin? Evaluation of its activity at the cellular level against <Emphasis Type="Italic">Tagetes erecta</Emphasis>

Zinniol, a non-host selective phytotoxin commonly produced by fungi of the Alternaria genus, has been reported as the metabolite responsible for the phytotoxicity of the lipophilic fraction of A. tagetica. While both the lipophilic fraction and zinniol have been shown to produce necrosis on leaves of susceptible marigold (Tagetes erecta) plants, the true role of zinniol in the infectious process remains uncertain. Using marigold cell cultures as a model, we evaluated the effects of zinniol and the lipophilic fraction at the cellular level and showed that pure zinniol is not markedly phytotoxic at concentrations known to induce necrosis in leaves of T. erecta. Moreover, the effects of zinniol on cell membranes and DNA fragmentation are less intense than those caused by the lipophilic fraction. These results suggest that zinniol may not play a significant role in the A. tagetica–T. erecta interaction and, consequently, its classification as a non-host selective phytotoxin is questionable.     

European Eel Sperm Diluent for Short‐term Storage

The sperm of European eel shows a high density and the time of spermatozoa motility is very short after activation with sea water. These characteristics make difficult the sperm handling and its quality assessment. Several diluents were previously described for the Japanese eel obtaining over 3 weeks’ conservation times under refrigeration, but they rendered bad results in the European species. In the present study, several diluents were developed taking as basis the P1 medium, and using different dilution ratios (1 : 50, 1 : 100) and two pH (6.5, 8.5). The effect of the addition of bovine serum albumin (BSA, 2% w/v) was also evaluated. At 24 h, undiluted samples already showed significant lower motility and viability than sperm samples diluted in the different media. The results for diluents with pH 6.5 and 8.5 were different. Spermatozoa diluted in media at pH 6.5 cannot be activated at 24 h, while samples diluted in the diluents with pH 8.5 and added with BSA did not show significant differences with respect to the fresh sperm motility until 48 h. The viability (percentage of alive cells) did not show differences until 1 week, independent of the dilution ratio. After 1 week, the motility was approximately 30% in the media containing BSA, which presented no differences for head size of the spermatozoa (perimeter and area) until 72 h and 1 week, respectively. In conclusion, the combination of one medium having similar physico‐chemical characteristics to the seminal plasma, including pH 8.5, and supplemented with BSA can be used in different dilution ratios for the sperm’s short‐term storage, preserving its motility capacity.     

Local and regional environmental variation influences the growth of tropical trees in selection trials in the Republic of Panama

Native Neotropical trees are being increasingly planted for restoration purposes and timber production, but we lack species-specific data on growth responses to different regional climates and local environmental variation. We used regression trees and variance components to quantify the effects of within- and among-site environmental variation on the basal area (BA) of 21 Neotropical and two exotic tree species at three selection trials in the Republic of Panama. Sites represented distinct regional climates in which annual rainfall varied from 1100 to 2226 mm, with dry seasons of 4.1–6.7 months. Local environmental variables included measures of slope steepness and position, soil texture, soil color, and indicators of soil condition, such as subsoil rockiness.     

Gemmamyces bud blight of Picea pungens: a sudden disease outbreak in Central Europe

Due to its high tolerance to acid rain, the North American Colorado blue spruce (Picea pungens) has been among the most frequent substitute tree species used in reforestation programmes in spruce mountain forests in the Ore and Sudeten Mountains in the Czech Republic after destruction by sulphur dioxide pollution in the second half of the last century. This species was planted on more than 8800 ha of destroyed mountain forest stands in the Ore Mountains alone. New plantations prospered until a massive outbreak of the gemmamyces bud blight, first identified in 2009. The causal agent, Gemmamyces piceae, induced massive bud blight in infected trees – bud loss progressively increased to 70–80% or more, and because the trees were not able to replace the natural loss of older needles, they quickly withered and died. Many plantations disrupted by the pathogen had to be cut down. Although several resistant genotypes have been identified, the cultivation of this species in forest stands has no future in this area. Because this disease was also identified in several ornamental plantations in the area, the bud blight epidemic haunts public green space administrators and nursery and Christmas tree plantation owners. Other pathogens and pests, such as Lophodermium piceae, Sirococcus conigenus and Elatobium abietinum, have also been identified as involved in the damage to P. pungens.     

Laboratory Evaluation of Zinc Phosphide as a Rodenticide against Bandicota bengalensis

Abstract

The toxicity and efficacy of the acute rodenticide zinc phosphide (Zn₃P₂) was evaluated in the laboratory against the lesser bandicoot rat (Bandicota bengalensis), from Rangoon, Burma. The acute LD50 and LD95 doses of orally-administered zinc phosphide for B. bengalensis were found to be 25.0 mg/kg and 113.0 mg/kg of body weight respectively. When caged bandicoots were given a choice between plain and poison baits, the optimum rodenticidal concentrations in the bait was found to be 2.5%. Symptoms of poisoning appear from 32 minutes to 3 hours after feeding starts, giving individual animals time to consume from 10 to over 27 LD50 doses of 25% zinc phosphide before feeding stops. Death occurred in a minimum of 4 to 5 hours following either oral dosing or free choice feeding. There appears to be aversion to the poison at higher concentrations in food baits. The relative merits of zinc phosphide and pyriminyl as rodenticides against the lesser bandicoot in Rangoon will have to be determined in a series of comparative field trials.     

Phenolic compositions of grapes and wines from cultivar cabernet sauvignon produced in chile and their relationship to commercial value

The phenolic composition of wine depends on, among other factors, the grapes used to make it. In this sense, knowledge of the chemical composition of grapes and its association with the resulting wines is an important tool to determine if there is a relationship between the phenolic composition of grapes and the price that these wines obtain in the market. For this purpose, grape skins and seeds from the cultivar Cabernet Sauvignon from the central region of Chile, in 2009 and 2010 vintages from two ripening points, were subjected to chemical and phenolic analyses, as were the wines made from these grapes. Grapes and the corresponding wines from three retail price wine categories, U.S. $6-8, U.S. $28-30, and U.S. $150-160, were evaluated. No differences were found across the price categories in the chemical analysis of grapes. Berry skins and wines from the higher price categories presented a higher concentration only of total tannins, and the differences in their concentrations were only among the different fractions of proanthocyanidins in the skins, seeds, and wines; there were no differences in their proportions. A seasonal effect influenced the concentrations of certain compounds in grapes and led to a decrease in the concentration of total phenols, total tannins, and total anthocyanins between sampling dates as harvesting moved toward the common commercial grape harvest in Chilean viticulture.     

Mercury content in volcanic soils across Europe and its relationship with soil properties

Purpose  

Volcanoes are a natural source of Hg, whose deposition can occur in neighbouring soils. This study examines the role of soil compounds in the geochemical behaviour of total Hg (Hg _T ) in volcanic soils. An estimation of Hg from lithological origin is also assessed to ascertain the relevance of other sources in Hg _T accumulated in volcanic soils.     

Soil P fractions in a volcanic soil chronosequence of Central Mexico and their relationship to foliar P in pine trees

Phosphorus (P) is a major plant nutrient, however, its availability in volcanic ash soils is presumed to be small, due to its specific sorption on short‐range order minerals. We analyzed distinct P fractions in volcanic ash soils of different age (60 to > 100,000 y BP) under pine forests in Central Mexico to investigate their changes along a chronosequence of Regosols, Andosols, and Lixisols, and to evaluate if P availability limits tree growth at any particular stage. Top soil and subsoil samples were first analyzed by the Tiessen and Moir method, which failed to extract exhaustively “organic” and “occluded P”, and “P associated with apatite”. Therefore, we modified the fractionation scheme by including a “recalcitrant organic P” fraction obtained from the difference between P determined in air‐dried subsamples and subsamples burned at 300°C; P adsorbed to short‐range order minerals was assessed in an extraction with NH₄‐oxalate, and P in primary minerals by subtracting the sum of all other fractions from total P contents determined by XRF. This we did after discovering that primary P occurred in the form of fluorapatite included in plagioclase, volcanic glass or olivine. We also measured P contents in pine needles and related these with the “mobile soil P” fractions. The results show that “organic P” reaches maximum contents in 10,000‐y old soil, as does P associated with short‐range order minerals, while P occluded into crystalline oxides increases constantly over time. After 100,000 y, 31% of total P still remains in the form of primary P in A horizons. “Mobile P” was constant > 40 mg kg^?1 in Regosols and Andosols and related positively with foliar P contents, which were within adequate nutritional ranges. Only in Lixisols small “mobile P” concentrations in soil correspond with inadequate P contents in pine needles.