Air-breathing behavior and physiological responses to hypoxia and air exposure in the air-breathing loricariid fish, Pterygoplichthys anisitsi

Hypoxic water and episodic air exposure are potentially life-threatening conditions that fish in tropical regions can face during the dry season. This study investigated the air-breathing behavior, oxygen consumption, and respiratory responses of the air-breathing (AB) armored catfish Pterygoplichthys anisitsi. The hematological parameters and oxygen-binding characteristics of whole blood and stripped hemoglobin and the intermediate metabolism of selected tissue in normoxia, different hypoxic conditions, and after air exposure were also examined. In normoxia, this species exhibited high activity at night and AB behavior (2–5 AB h^?1). The exposure to acute severe hypoxia elicited the AB behavior (4 AB h^?1) during the day. Under progressive hypoxia without access to the water surface, the fish were oxyregulators with a critical O₂ tension, calculated as the inspired water O₂ pressure, as 47 ± 2 mmHg. At water O₂ tensions lower than 40 mmHg, the fish exhibited continuous apnea behavior. The blood exhibited high capacity for transporting O₂, having a cathodic hemoglobin component with a high Hb–O₂ affinity. Under severe hypoxia, the fish used anaerobic metabolism to maintain metabolic rate. Air exposure revealed physiological and biochemical traits similar to those observed under normoxic conditions.     

Influence of time of day on measurement with chlorophyll meters and canopy reflectance sensors of different crop N status

Precision Agriculture - Optical sensors are a promising approach for assessing nitrogen (N) status of vegetable crops. However, their potential may be undermined if time of day influences...     

The effects of nitrogen rate and the ratio of NO3:NH4 on Bemisia tabaci populations in hydroponic tomato crops

Nitrogen fertilization is one of the factors that influences Bemisia tabaci (Gennadius) population density. The aim of this study was to determine the effects of three N application rates (75, 205 and 335 mg/l) and three ratios of NO₃⁻:NH₄⁺ ions (92:8, 75:25 and 55:45) in standard nutrient solution (205 mg/l N) on the population density of B. tabaci. The experiments were conducted on spring-summer hydroponic crops of tomato. The effect of plant stratum on the whitefly population was also determined. The aggregation of B. tabaci adults as well as their oviposition rate was higher at 205 and 335 mg/l N than on plants grown at 75 mg/l N. By the end of the experiment (60 d after infestation), the number of nymphs on plants at 205 mg/l N was higher than on plants at 75 mg/l N. The number of pupae was lowest on plants supplied with 75 mg/l N. An increase in NH₄⁺ percentage in standard nutrient solution (from 25% to 45% of the total N) reduced adult population density and oviposition rate. The density of nymphs and pupae, at 60 d after infestation, was lower on the tomato plants grown at 75:25 and 55:45 NO₃⁻:NH₄⁺ ratios compared to the 92:8 ratio. The 75:25 and 55:45 NO₃⁻:NH₄⁺ ratios resulted in a higher incidence of blossom-end rot of tomato fruit, with a lower incidence of disorder at 75:25 than at the 55:45 ratio. Plant stratum influenced adult whitefly distribution in two years of the study. Middle stratum leaves were more attractive to adults in both years. The results demonstrate the effects of N fertilization (N rate and the ratio of NO₃⁻:NH₄⁺) and plant stratum on B. tabaci population density.     

Detection of antibodies against Anaplasma marginale in milk using a recombinant MSP5 indirect ELISA

An indirect enzyme linked immunosorbent assay (iELISA) for diagnosis of anaplasmosis using undiluted individual milk samples from dairy cows was developed. The recombinant 19 kDa major surface protein 5 (rMSP5) of Anaplasma marginale was used as antigen. A monoclonal antibody against bovine IgG1 conjugated with peroxidase and the chromogen 3,5,3',5'-tetramethylbenzidine were used in the test. Strong and weak, positive and negative milk samples were set up as reference controls. Results were expressed as percentage of positivity (PP) contrasting with the strongest positive control. The test was evaluated in two groups (G1 and G2) of lactating dairy cows from herds located in A. marginale non-endemic areas of Argentina. The infection status of both groups, G1 (n=128) sampled after anaplasmosis outbreak, and G2 (n=216) free of anaplasmosis was established by polymerase chain reaction (PCR). Serum samples of cows from G1 and G2 were analyzed by card agglutination test (CAT) and competitive ELISA (cELISA), while the novel iELISA was evaluated in their corresponding milk samples. At a cutoff of 42 PP, the ELISA has 98% sensitivity and 95% specificity. A significant difference (P<0.0001) was found between the mean PP value of negative samples from G1 (17.4+/-14.9), and G2 (8.6+/-7.1). The agreement and kappa (kappa) value between iELISA and PCR was 96%, kappa=0.919; between iELISA and CAT was 97%, kappa=0.880; and between iELISA and cELISA was 97%, kappa=0.899. These results strongly support the usefulness of iELISA to detect A. marginale antibodies in milk. Additional studies are necessary to define the ability of the milk iELISA to detect not only acutely infected, but also carrier cattle.     

Impacts of land use and cropland management on soil organic matter and greenhouse gas emissions in the Brazilian Cerrado

The Brazilian Cerrado is a large and expanding agricultural frontier, representing a hotspot of land-use change (LUC) from natural vegetation to farmland. It is known that this type of LUC impacts soil organic matter (SOM) dynamics, particularly labile carbon (C) pools (living and non-living), decreasing soil health and agricultural sustainability, as well as increasing soil greenhouse gas (GHG) emissions, and accelerating global climate change. In this study, we quantified the changes in the quantity and quality of SOM and GHG fluxes due to changes in land use and cropland management in the Brazilian Cerrado. The land uses studied were native vegetation (NV), pasture (PA) and four croplands, including the following management types: conventional tillage with a single soybean crop (CT), and three no-tillage systems with two crops cultivated in the same year (i.e., soybean/sorghum (NT_SSo), soybean/millet (NT_SMi) and maize/sorghum (NT_MSo)). Soil and gases were sampled in the rainy season (November, December and January) and dry season (May, July and September). The highest soil C and nitrogen (N) stocks (6.7 kg C m⁻² and 0.5 kg N m⁻², 0–0.3-m layer) were found under NV. LUC reduced C stocks by 25% in the CT and by 10% in the PA and NT. Soil N stocks were 30% lower in the PA and NT_MSo and 15% lower in the croplands with soybean compared to NV. δ¹³C values clearly distinguished between the C-origin from NV (−25‰) and that from other land uses (−16‰). Soil (0–0.1 m) under NV also presented higher labile-C (625 g C m⁻²), microbial-C (70 g C m⁻²) and microbial-N (5.5 g N m⁻²), whereas other land uses presented values three times lower. GHG emissions (expressed as C-equivalent) were highest in the NV (1.2 kg m⁻² year⁻¹), PA (1.3 kg m⁻² year⁻¹) and NT_MSo (0.9 kg m⁻² year⁻¹) and were positively related to the higher SOM turnover in these systems. Our results suggest that in order to maintain SOM, it is necessary to adopt “best” management practices, that provide large plant residue inputs (above- and belowground). This can be seen as a pathway to achieving high food production with low GHG emissions.     

Stand Establishment and Persistence of Perennial Cool-Season Grasses in the Intermountain West and the Central and Northern Great Plains

The choice of plant materials is an important component of revegetation following disturbance. To determine the utility and effectiveness of various perennial grass species for revegetation on varied landscapes, a meta analysis was used to evaluate the stand establishment and persistence of 18 perennial cool-season grass species in 34 field studies in the Intermountain and Great Plains regions of the United States under monoculture conditions. Combined across the 34 studies, stand establishment values ranged from 79% to 43% and stand persistence values ranged from 70% to 0%. Intermediate wheatgrass (Thinopyrum intermedium [Host] Barkworth & D. R. Dewey), tall wheatgrass (Thinopyrum ponticum [Podp.] Z.-W. Liu & R.-C. Wang), crested wheatgrass (Agropyron spp.), Siberian wheatgrass (Agropyron fragile [Roth] P. Candargy), and meadow brome (Bromus riparius Rehmann) possessed the highest stand establishment (≥ 69%). There were no significant differences among the 12 species with the largest stand persistence values. Basin wildrye (Leymus cinereus (Scribn. & Merr.) Á. Löve), Altai wildrye (Leymus angustus [Trin.] Pilg.), slender wheatgrass (Elymus trachycaulus [Link] Gould ex Shinners), squirreltail (Elymus spp.), and Indian ricegrass (Achnatherum hymenoides [Roem. & Schult.] Barkworth) possessed lower stand persistence (≤ 32%) than the majority of the other species, and Indian ricegrass (0%) possessed the lowest stand persistence of any of the species. Correlations between environmental conditions and stand establishment and persistence showed mean annual study precipitation to have the most consistent, although moderate effect (r = ～0.40) for establishment and persistence. This relationship was shown by the relatively poor stand establishment and persistence of most species at sites receiving less than 310 mm of annual precipitation. These results will be a tool for land managers to make decisions concerning the importance of stand establishment, stand persistence, and annual precipitation for revegetation projects on disturbed sites.     

Epidemiology of canine cutaneous round cell tumours on the canary archipelago in Spain

In this study we undertook a comprehensive analysis of a Pet Tumour Registry of the Canary Archipelago (PTR-CA) in Spain to investigate the epidemiology of canine cutaneous round cell tumours. From a database of 2526 tumours collected from 2003 to 2020, we conducted a longitudinal analysis of the main trends in diagnosis, age, multiplicity and anatomical distribution as well as a case–control study comparing these cases with the contemporaneous canine population of the Canary Archipelago to analyse breed distribution. In line with former studies, we found histiocytomas mostly affect young dogs (2, IQR 1–5) and mast cell tumours affect middle-to-old dogs (8, IQR 6–10) with grade 1 affecting at younger ages (6.5, IQR 6–8) than both grade 2 (8, IQR 6–10 years) and grade 3 (9, IQR 7–11). Histiocytomas and plasmacytomas showed a similar anatomical distribution appearing mainly on the face, head and neck regions while mast cell tumours occur mainly on limbs and trunk. Higher risk for mast cell tumours and histiocytomas were found for Bulldog-related breeds such as Boxer (OR_MCT = 23.61, CI95%: 19.12–29.15, OR_HCT = 10.17, CI95%: 6.60–15.67), Boston Terrier (OR_MCT 19.47, CI95%: 7.73–49.05, OR_HCT 32.61, CI95%: 11.81–90.07) and Pug (OR_MCT 8.10, CI95%: 5.92–11.07, OR_HCT 7.87, CI95%: 4.66–13.28) while Chihuahua dogs showed significantly less risk (OR_MCT 0.18, CI95%: 0.09–0.33, OR_HCT 0.41, CI95%: 0.21–0.78). Notably, the Canarian Mastiff, a local breed, had a low risk of suffering from a mast cell tumour which raises the question of whether this relates to a genetic peculiarity of this breed or some husbandry and environmental factor.     

Surveillance of swine influenza viruses in sentinel familial farms in Hung Yen province in Northern Vietnam in 2013–2014

From May 2013 to April 2014, 15 swine family‐run farms (17 pig litters) in two districts in Hung Yen province, near Hanoi, were virologically and epizootiologically monitored for swine influenza viruses (SIV) monthly. No SIV was isolated from nasal swabs. Maternal antibodies were detected in 10 litters, and seroconversion against SIV was detected in six litters. There was a marked difference in patterns of SIV transmission in the two districts. Van Lam district which has low density of swine with mainly smallholder farms had low intensity of SIV, with much of the infection caused by H1N1 2009 pandemic‐like viruses A(H1N1)pdm09, likely originated from humans. In contrast, Van Giang district, which has high swine density and larger farms, had high levels of typical SIV (triple reassortants H3N2 and H3N2 Binh Duong lineage viruses) circulating within swine. With one exception, the SIV lineages detected were those we concurrently isolated from studies in a large central abattoir in Hanoi. Influenza‐like illness symptoms reported by farmers were poorly correlated with serological evidence of SIV infection.     

Seasonal dynamics of Microcystis spp. and their toxigenicity as assessed by qPCR in a temperate reservoir

Blooms of toxic cyanobacteria are becoming increasingly frequent, mainly due to water quality degradation. This work applied qPCR as a tool for early warning of microcystin(MC)-producer cyanobacteria and risk assessment of water supplies. Specific marker genes for cyanobacteria, Microcystis and MC-producing Microcystis, were quantified to determine the genotypic composition of the natural Microcystis population. Correlations between limnological parameters, pH, water temperature, dissolved oxygen and conductivity and MC concentrations as well as Microcystis abundance were assessed. A negative significant correlation was observed between toxic (with mcy genes) to non-toxic (without mcy genes) genotypes ratio and the overall Microcystis density. The highest proportions of toxic Microcystis genotypes were found 4-6 weeks before and 8-10 weeks after the peak of the bloom, with the lowest being observed at its peak. These results suggest positive selection of non-toxic genotypes under favorable environmental growth conditions. Significant positive correlations could be found between quantity of toxic genotypes and MC concentration, suggesting that the method applied can be useful to predict potential MC toxicity risk. No significant correlation was found between the limnological parameters measured and MC concentrations or toxic genotypes proportions indicating that other abiotic and biotic factors should be governing MC production and toxic genotypes dynamics. The qPCR method here applied is useful to rapidly estimate the potential toxicity of environmental samples and so, it may contribute to the more efficient management of water use in eutrophic systems.