Application of a plant bioassay for the evaluation of ecotoxicological risks of heavy metals in sediments affected by mining activities

Purpose

The objective of this work was to evaluate the effectiveness of a plant bioassay (Phytotoxkit®) for screening ecotoxicological risks in sediments affected by mining activities.

Materials and methods

A total of 42 sediment samples affected by mining activities were studied, including 39 sediment samples from the Sierra Minera, Spain, an area affected by old extraction procedures, and three sediments from an area affected by opencast mining. These three samples were then mixed with limestone filler at 10, 20 and 30 %, providing nine stabilised samples. The total and soluble metal(loid) content (As, Cd, Cu, Fe, Pb and Zn) was determined in all samples, and the Phytotoxkit® bioassay was applied to determine the ecotoxicological effect of this procedure.

Results and discussion

The stabilised material had a neutral pH and low soluble metal(loid) concentration, similar to that of samples in which a natural attenuation process had taken place because of mixing with surrounding carbonate-rich materials. An ecotoxicological survey identified the low toxicity levels of the stabilised samples.

Conclusions

The applied bioassay is a good tool for screening metal(loid) contamination in areas affected by mining activities, since it provides information on both natural and simulated attenuation processes. The mixing of sediments with limestone filler could be applied to the remediation of zones affected by mining activities, because the toxicological effect on the tested organisms in the stabilised sediments was reduced significantly and the metal(loid) content was diminished.     

Inheritance and heritability of resistance to citrus leprosis

ABSTRACT The genetic inheritance of resistance to leprosis, the most important viral disease of citrus in Brazil, was characterized through the phenotypic assessment of 143 hybrids resulting from crosses between tangor 'Murcott' (Citrus sinensis x C. reticulata) and sweet orange 'Pêra' (C. sinensis), considered to be resistant and susceptible to the disease, respectively. All plants were grafted onto Rangpur lime (C. limonia) and inoculated with Citrus leprosis virus, cytoplasmic type through the infestation with viruliferous mites, Brevipalpus phoenicis. The experiments were arranged in a completely randomized block design with 10 replicates. Incidence and severity of the disease in leaves and stems as well as plant growth parameters (plant height and stem diameter) were recorded for 3 years after the infestation with the viruliferous mites. The average values of all variables were analyzed using principal component analysis, discriminant factorial analysis, estimation of the clonal repeatability coefficients, and frequency of the distributions of the average values for each measured variable. The principal component analysis resulted in the identification of at least two groups with resistance and susceptibility to leprosis, respectively. About 99% of all hybrids were correctly classified according to the discriminant factorial analysis. The broad-sense heritability coefficients for characteristics associated with incidence and severity of leprosis ranged from 0.88 to 0.96. The data suggest that the inheritance of resistance to leprosis may be controlled by only a few genes.     

Adjusted method of penis fixation during boar semi-automatic semen collection aiming to reduce bacterial contamination

Semen collection has an essential role in the initial bacterial load in boar ejaculates and extended semen. The study aimed to explore the efficacy of an adjusted penis fixation in a semi-automatic collection system on reducing bacterial contamination of ejaculates in two-boar studs with different scenarios. Historically, stud A had low levels of bacterial load in raw semen, while stud B had a high level of contamination. A total of 56 mature boars had their semen collected using two methods of penis fixation: (a) Traditional: The penis was fixed directly with the artificial cervix and transferred to the adjustable clamp; (b) Adjusted: The fixation was performed with one gloved-hand, and after exteriorization, the penis was gripped using the artificial cervix with the other gloved-hand and transferred to the adjustable clamp. The bacterial load (p = .0045) and the occurrence of ejaculates >231 CFU/ml (p = .0101) were reduced in the Adjusted compared to the Traditional method. Bacterial load was reduced when using the Adjusted method in stud B (p = .0011), which showed a greater occurrence of critical factors for bacterial contamination (p ≤ .0034). The Adjusted method reduced the occurrence of ejaculates >231 CFU/ml when the preputial ostium was dirty (p = .016) and the duration of semen collection was >7 min (p = .022) compared to the Traditional method. In conclusion, the Adjusted penis fixation was efficient in reducing bacterial load of ejaculates, mainly in boar stud B, which had high contamination challenges.     

Do carbon farming practices build bioavailable nitrogen pools?

Agricultural soils contain large amounts of nitrogen (N), but only a small fraction is readily available to plants. Despite several methods developed to estimate the bioavailability of N, there is no consensus on which extraction methods to use, and which N pools are critically important. In this study, we measured six soil N pools from 20 farms, which were part of a multi-year soil carbon sequestration on-farm experiment (Carbon action, 2019–2023). The aim was to quantify the N pools and to evaluate if farming practices that aim to build soil carbon pools, also build bioavailable N pools. We also aimed to test if the smaller and rapidly changing N pools could serve as an indicator for the slower change in soil organic matter. The measured N pools decreased in size, when moving from total N (7700 ± 1500 kg/ha) to slowly cycling (Illinois Soil Nitrogen Test ISNT-N: 1063 ± 220 kg/ha, autoclave citrate-extracted ACE protein N: 633 ± 440 kg/ha), water-soluble organic N (50 ± 17 kg/ha), potentially mineralizable N (33 ± 13 kg/ha) and finally readily plant available inorganic pools (nitrate and ammonium, total: 14 ± 8 kg/ha). In total, the measured pools covered only 18%–44% of total N, indicating a large unidentified N pool, which is either tightly bound to soil mineral fraction and not easily extractable or is bound to undecomposed plant residues and not hydrolysed by the methods. Of the large N pools (ISNT-N, ACE protein and unidentified residual N), clay, carbon (C) and C:Clay ratios explained most of the variability (R² = .90–.93), leaving a minor part of the variation to the management effect. A pairwise comparison of carbon farming and control plots concluded that farming practices had a small (3%–5%) but statistically significant (p < .05) effect on soil total N and ISNT-N pools, and a moderate and significant effect (18%, p < .01) on potentially mineralizable N. The large variation in protein N, water-soluble organic N and inorganic N reduced statistical significance, although individual C sequestration practices had large effects (−30% to +50%). In conclusion, carbon sequestration practices can build both slowly cycling N pools (ISNT) and increase the mineralisation rate of these pools to release plant available forms, resulting in an additional benefit to agriculture through reduced fertilizer application needs.     

Reproductive parameters of the chub mackerel <Emphasis Type="Italic">Scomber japonicus</Emphasis> estimated from human chorionic gonadotropin-induced final oocyte maturation and ovulation in captivity

ABSTRACT:   Final oocyte maturation and ovulation of captive chub mackerel Scomber japonicus with fully yolk-accumulated oocytes were induced by a single injection of human chorionic gonadotropin. Reproductive parameters, including spawning frequency and batch fecundity, which are required to estimate spawning biomass in pelagic fish by the daily egg production method, were analyzed. Germinal vesicle migration (GVM) occurred at 18–24 h post-injection, and the hydration and ovulation of oocytes were completed at 30 and 36 h post-injection, respectively. The results of the maturation process suggest that fish with GVM-stage ovaries captured in the daytime from the field are capable of spawning on the night following their capture. The oocytes used in the oocyte size-frequency distribution method for batch fecundity estimates should be at late GVM and more advanced stages. The results of sequential artificial insemination showed that the quality of ovulated eggs held in the ovarian lumen rapidly deteriorated as time progressed after ovulation. This indicates that the fertilization window for the ovulated eggs of chub mackerel lasts only a few hours, and spawning behavior should be performed within a few hours after ovulation in the wild population.     

Prediction of vascular invasion using a 7‐point scale computed tomography grading system in adrenal tumors in dogs

BackgroundPrevious studies evaluating the accuracy of computed tomography (CT) in detecting caudal vena cava (CVC) invasion by adrenal tumors (AT) used a binary system and did not evaluate for other vessels.ObjectiveTest a 7‐point scale CT grading system for accuracy in predicting vascular invasion and for repeatability among radiologists. Build a decision tree based on CT criteria to predict tumor type.MethodsRetrospective observational cross‐sectional case study. Abdominal CT studies were analyzed by 3 radiologists using a 7‐point CT grading scale for vascular invasion and by 1 radiologist for CT features of AT.AnimalsDogs with AT that underwent adrenalectomy and had pre‐ and postcontrast CT.ResultsNinety‐one dogs; 45 adrenocortical carcinomas (50%), 36 pheochromocytomas (40%), 9 adrenocortical adenomas (10%) and 1 unknown tumor. Carcinoma and pheochromocytoma differed in pre‐ and postcontrast attenuation, contralateral adrenal size, tumor thrombus short‐ and long‐axis, and tumor and thrombus mineralization. A decision tree was built based on these differences. Adenoma and malignant tumors differed in contour irregularity. Probability of vascular invasion was dependent on CT grading scale, and a large equivocal zone existed between 3 and 6 scores, lowering CT accuracy to detect vascular invasion. Radiologists'' agreement for detecting abnormalities (evaluated by chance‐corrected weighted kappa statistics) was excellent for CVC and good to moderate for other vessels. The quality of postcontrast CT study had a negative impact on radiologists'' performance and agreement.Conclusions and Clinical ImportanceFeatures of CT may help radiologists predict AT type and provide probabilistic information on vascular invasion.     

Detection and quantification of Anaplasma marginale DNA in blood samples of cattle by real-time PCR

A TaqMan-based real-time PCR assay was developed for the diagnosis of Anaplasma marginale infection of cattle. The established assay was proven to be highly specific, since no cross-reactions were observed with other Anaplasma species of ruminants, including the closely related Anaplasma centrale, or other haemoparasites of ruminants (Anaplasma bovis, Anaplasma ovis, Anaplasma phagocytophilum, Babesia bovis, Babesia bigemina, Theileria annulata and Theileria buffeli). The detection limit was equal to that of nested (n)PCR (10(1) copies of standard DNA and 3 x 10(1) infected erythrocytes ml(-1) of blood). The assay was also reproducible, as shown by satisfactory low intra-assay and inter-assay coefficients of variation. Fifty-four blood samples of ruminants (cattle, n = 51; sheep, n = 2; goats, n = 1), that had been tested previously by reverse line blot (RLB) hybridisation, were subjected to an nPCR assay and the newly established real-time PCR assay. By using real-time PCR, A. marginale DNA was detected in 39/51 bovine samples, with DNA titres ranging from 3.60 x 10(3) to 5.70 x 10(8) copies ml(-1) of blood, whereas sheep and goat samples tested negative. The concordance with nPCR was 100%, whereas a unique sample that had tested negative by RLB gave positive results by nPCR and real-time PCR. The established assay could overcome the limitations of existing diagnostic methods, allowing for simultaneous detection and quantification of the A. marginale DNA in bovine blood, that is essential to support the clinical diagnosis, to assess the carrier status of the animals and to evaluate the efficacy of vaccines and antirickettsial drugs.