Association of β-globin polymorphisms and tolerance to haemonchosis in ewes and lambs of different sheep breeds

Gastrointestinal nematodes (GIN), especially Haemonchus contortus, represent a significant challenge for sheep production. Given the global concern about GIN anthelmintic resistance, alternative control methods able to reduce the dependence on these drugs are highly advisable. Since previous studies have shown that sheep carrying the Hb-A allele of β-globin are more resistant to H. contortus, this study aimed to investigate the relationship between the different haplotypes (Hb-AA, Hb-AB and Hb-BB) and phenotypes in Santa Inês (SI), Texel (TX) and White Dorper (DO) breeds infected with H. contortus. Blood samples were collected from 180 ewes and 123 lambs of the three breeds for DNA extraction followed by qPCR using a hydrolysis probe to identify the β-globin haplotypes. Phenotypic data, including fecal egg count (FEC), packed cell volume (PCV), FAMACHA score and body condition score for ewes and lambs, as well as weight gain for lambs, were collected. The genotypic frequencies of β-globin for ewes and lambs were, respectively: 21.7% and 21.4% Hb-AA, 50% and 50% Hb-AB and 28.3% and 28.6% Hb-BB in SI; 0% and 0% Hb-AA, 18.6% and 9.4% Hb-AB and 81.4% and 90.6% Hb-BB in TX; and 0% and 0% Hb-AA, 13.1% and 0% Hb-AB and 86.9% and 100% Hb-BB in DO. In ewes, mean PCV differed (p<0.05) between the three haplotypes, with higher PCV in Hb-AA animals, followed by Hb-AB and Hb-BB. When considering each breed separately, SI Hb-AA ewes presented higher PCV (p<0.05), highlighting that even in a breed already considered resistant, animals with Hb-AA haplotype showed superior performance. Lambs with the Hb-AA haplotype exhibited a higher (p<0.05) mean PCV compared to those with Hb-AB and Hb-BB. The same pattern was found in SI when analyzing each breed separately. No significant association was found between β-globin haplotypes and FEC, FAMACHA score, body condition score, or weight gain. Nevertheless, given that anemia is the major clinical sign of haemonchosis, our findings on PCV reinforce that sheep carrying the Hb-A allele of β-globin are more tolerant to haemonchosis. This study may support the development of a valuable tool, targeting genetic selection for GIN control, reducing the dependence on anthelmintics and boosting sheep production worldwide.

From the laboratory to the field: efficacy of entomopathogenic nematodes to control the cattle tick

BACKGROUND

The control of ticks is challenged by the resistance of tick populations to chemical acaricides. In this study, we evaluated, under laboratory conditions, the efficacy of Heterorhabditis bacteriophora against Rhipicephalus (Boophilus) microplus engorged females with varying body weights (150, 200, 250, 300 or 350 mg per female) or from eight different geographical populations. We also determined the efficacy of H. bacteriophora for tick control under field conditions.

RESULTS

R. microplus engorged females with varying body weights exposed to 150 juveniles of H. bacteriophora resulted in a high control efficacy (97.5% to 98.4%). Tests with females from different geographical populations comprised eight tick strains treated with H. bacteriophora and their respective control groups. The biological parameters of females exposed to nematode treatments did not differ significantly and resulted in 89% to 99% of control efficacy. Trials conducted under field conditions were performed in field plots with Megathyrsus maximus grass. Treatment groups received eight cadavers of Tenebrio molitor fully colonized with H. bacteriophora at 1 week prior to the release of female ticks, whereas control groups were untreated. On the first day of the experiment, six engorged females were distributed in each plot. On day 42 and day 63, the apical portion of the grasses with R. microplus larvae were collected and quantified. The population of R. microplus larvae was reduced up to 73.1% in plots treated with H. bacteriophora at day 63 after treatment.

CONCLUSION

R. microplus engorged females with varying body weights or from different geographical populations were highly susceptible to H. bacteriophora. The field test demonstrated the efficacy of H. bacteriophora in reducing R. microplus larvae in infested pastures. © 2022 Society of Chemical Industry.

Epicardial slices: an innovative 3D organotypic model to study epicardial cell physiology and activation

The epicardium constitutes an untapped reservoir for cardiac regeneration. Upon heart injury, the adult epicardium re-activates, leading to epithelial-to-mesenchymal transition (EMT), migration, and differentiation. While interesting mechanistic and therapeutic findings arose from lower vertebrates and rodent models, the introduction of an experimental system representative of large mammals would undoubtedly facilitate translational advancements. Here, we apply innovative protocols to obtain living 3D organotypic epicardial slices from porcine hearts, encompassing the epicardial/myocardial interface. In culture, our slices preserve the in vivo architecture and functionality, presenting a continuous epicardium overlaying a healthy and connected myocardium. Upon thymosin β4 treatment of the slices, the epicardial cells become activated, upregulating epicardial and EMT genes, resulting in epicardial cell mobilization and differentiation into epicardial-derived mesenchymal cells. Our 3D organotypic model enables to investigate the reparative potential of the adult epicardium, offering an advanced tool to explore ex vivo the complex 3D interactions occurring within the native heart environment.

The vascular clock: a new insight into endothelial cells and pericytes crosstalk

Background/Introduction

Circadian rhythms, defined as biological oscillations with a period of circa 24h, regulate many physiological processes in the cardiovascular system, such as vascular function, vascular tone, blood pressure, heart rate and thrombus formation [1]. The vasculature responds to the main pacemaker located in the brain, but it also possesses its own clock. Indeed, a molecular clock has been identified in endothelial cells (EC) and smooth muscle cells (SMC). The disruption of the circadian clock profoundly affects cardiovascular functionality with adverse cardiovascular events such as myocardial infarction or stroke showing a 24h rhythmicity with a peak incidence in the early morning. Among several mechanisms affected by circadian dysregulation, angiogenesis plays a fundamental role in homeostasis and development of new blood vessels. EC and pericytes (PC) are the two main cell populations in the capillaries, and their physical and paracrine interaction drives and regulates the sprouting. However, the presence and the role of circadian rhythms in pericytes and whether the molecular clock affects the endothelial/pericyte interactions remain unexplored.

Purpose

The aim of this study is to identify a molecular clock in human vascular pericytes and elucidate the impact of the circadian clock on the formation of new blood vessels.

Methods

Human primary PC were synchronised and the rhythmicity of clock genes measured by luminescence, immunofluorescence, and qPCR. Synchronised PC were co-cultured with Bmal1::LUC human primary EC. The effect of PC synchronisation and circadian clock disruption by shRNA on EC clock genes and angiogenic potential were measured by luminescence and Matrigel assay, respectively. A macroporous polyurethane scaffold was developed for 3D co-cultures.

Results

PC presented rhythmic expression of the principal circadian genes with a circa 24h period but in our experimental setting, EC did not show circadian rhythmicity. Synchronised PC supported the rhythmic expression of the clock gene Bmal1 in EC in a contact co-culture system, suggesting a secondary form of EC molecular clock regulation. Non-contact co-cultures failed to synchronise EC. Furthermore, when the clock was disrupted in PC, their capacity to support EC's tube-forming capacity on Matrigel was impaired; clock disruption in EC did not affect angiogenesis, supporting the hypothesis that a disrupted clock in perivascular cells affects angiogenesis. In a 3D tissue engineering scaffold seeded with both EC and PC, the synchronisation of the clock led to the development of organised vascular-like structures around the scaffold's pores, as compared to the non-synchronised condition where cells appeared disorganised.

Conclusion

This study defines for the first time the existence of an endogenous molecular circadian clock in perivascular cells and suggests implications for circadian clock synchronisation in physiological and therapeutic angiogenesis.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): University of Surrey Doctoral CollegeUniversity of Surrey Bioprocess and Biochemical Engineering (BioProChem) Group.

Acute blockade of endogenous melatonin by Luzindole, with or without peripheral LPS injection, induces jejunal inflammation and morphological alterations in Swiss mice

This study investigated the acute blockade of endogenous melatonin (MLT) using Luzindole with or without systemic lipopolysaccharide (LPS) challenge and evaluated changes in inflammatory and oxidative stress markers in the mouse jejunum. Luzindole is an MT1/MT2 MLT receptor antagonist. Both receptors occur in the small intestine. Swiss mice were treated with either saline (0.35 mg/kg, ip), Luzindole (0.35 mg/kg, ip), LPS (1.25 mg/kg, ip), or Luzindole+LPS (0.35 and 1.25 mg/kg, ip, respectively). Jejunum samples were evaluated regarding intestinal morphometry, histopathological crypt scoring, and PAS-positive villus goblet cell counting. Inflammatory Iba-1, interleukin (IL)-1β, tumor necrosis factor (TNF)-α, nuclear factor (NF)-kB, myeloperoxidase (MPO), and oxidative stress (NP-SHs, catalase, MDA, nitrate/nitrite) markers were assessed. Mice treated with Luzindole, LPS, and Luzindole+LPS showed villus height shortening. Crypt damage was worse in the LPS group. Luzindole, LPS, and Luzindole+LPS reduced the PAS-goblet cell labeling and increased Iba-1-immunolabelled cells compared to the saline group. Immunoblotting for IL-1β, TNF-α, and NF-kB was greater in the Luzindole group. The LPS-challenged group showed higher MPO activity than the saline and Luzindole groups. Catalase was reduced in the Luzindole and Luzindole+LPS groups compared to saline. The Luzindole group showed an increase in NP-SHs, an effect related to compensatory GSH activity. The acute blockade of endogenous MLT with Luzindole induced early changes in inflammatory markers with altered intestinal morphology. The other non-detectable deleterious effects of Luzindole may be balanced by the unopposed direct action of MLT in immune cells bypassing the MT1/MT2 receptors.

Thymol: Effects on reproductive biology and Gene's organ morphology in Rhipicephalus sanguineus sensu lato engorged females (Acari: Ixodidae)

Thymol is a monoterpene with proven acaricidal activity on different tick species and life stages. The objective of this work was to evaluate the effect of thymol on the reproductive biology of engorged females of Rhipicephalus sanguineus sensu lato and the morphological changes caused in the cells of the tubular and accessory glands of Gené's organ. The females were exposed to thymol by immersion. Seven groups were established: group I (distilled water), group II (30% ethanol), group III (thymol 1.25 mg/mL), group IV (thymol 2.5 mg/mL), group V (thymol 5.0 mg/mL), group VI (thymol 10.0 mg/mL), and group VII (thymol 20.0 mg/mL), with 20 replicates for each treatment. The ticks were kept in a BOD incubator at 27 ± 1 °C and RH > 80 ± 10%. Ten females from each group were evaluated daily until death, and the remaining ten were kept in the incubator under the same conditions for five days and then dissected for the removal of Gené's organ to note possible damage to cell morphology by scanning electron microscopy (SEM) and hematoxylin-eosin (HE) techniques. Thymol demonstrated 63% and 98% efficacy in groups VI (10.0 mg/mL) and VII (20.0 mg/mL), respectively. In these groups, the cells of the tubular and accessory glands of Gené's organ showed signs of damage: irregular eosin staining, rupture and deformation of the cellular limit, presence of fragmented nuclei, changes in cytoplasmic homogeneity and areas with deformation (folds) in the basal region.

Thymol action on cells and tissues of the synganglia and salivary glands of Rhipicephalus sanguineus sensu lato females (Acari: Ixodidae)

Thymol is a monoterpene present in plants of the families Lamiaceae, Verbenaceae and Apiaceae. Despite its proven acaricidal activity, little is known about the mechanism of action of thymol in ticks. Thus, the aim of this study was to perform a morpho-histochemical analysis of the synganglion and salivary glands of partially engorged females of the brown dog tick, Rhipicephalus sanguineus sensu lato (s.l.), exposed to thymol at different concentrations. Five groups were established: Control Group I (distilled water), Control Group II (ethanol 30%), Group III (thymol 1.25 mg/mL), Group IV (thymol 2.5 mg/mL) and Group V (thymol 5.0 mg/mL). The females were exposed to the treatments by the immersion method and subsequently kept in a climatic chamber (27 ± 1 °C and relative humidity 80 ± 10%) for five days. After this period, the synganglion and salivary glands were removed, and the hematoxylin/eosin morphological technique was applied. The von Kossa staining method with counterstaining neutral red was performed on the salivary glands. The results showed that females exposed to thymol had damaged synganglia, with pyknotic nuclei and vacuoles in the cortex and subperineurial regions, as well as rupture of the neural lamellae. The salivary glands showed type I acini with a dilated lumen. Cells with extremely vacuolated cytoplasm and fragmented nuclei were observed in type II and III acini. Type II acini of the females exposed to thymol revealed different calcium staining when compared to the Control Groups I and II. We therefore conclude that the salivary glands and synganglion are subject to changes in morphology and calcium levels when exposed to thymol at concentrations of 1.25, 2.5 and 5.0 mg/mL, demonstrating that this monoterpene has acaricidal potential on partially engorged females of R. sanguineus (s.l.).

Acaricidal activity of thymol against larvae of Rhipicephalus microplus (Acari: Ixodidae) under semi-natural conditions

This is the first study to investigate the activity of thymol on Rhipicephalus microplus larvae under semi-natural conditions. For this purpose, tests were conducted in pots with Brachiaria decumbens seedlings containing cattle tick larvae. Thymol, diluted in ethanol 50° GL, was tested at concentrations of 2.5, 5.0, 10.0, 15.0, and 20.0 mg/mL, along with the control group treated with the solvent alone. Each treatment was composed of five pots (1 pot = a repetition). The experiment was performed in three steps. On the first day, the larvae were applied at the base of the signalgrass. Twenty-four hours later, approximately 25 mL of the solution was applied with thymol on the top of the vegetation in each pot. The survival of the larvae was measured 24 h after application of the solutions. Each pot was analyzed individually, and the grass fillets contained larvae were cut with scissors, placed in Petri dishes, and taken to the laboratory to count the number of living larvae. At the highest concentrations (10, 15, and 20 mg /mL), the number of live larvae declined by more than 95 % in relation to the control group. The lethal concentration 50 % (LC50) and LC90 values were 3.45 and 9.25 mg/ml, respectively. The application of thymol in semi-natural conditions starting concentration of 10 mg/mL significantly reduced the number of living R. microplus larvae.

Wet weather water quality modelling of a Portuguese urban catchment: difficulties and benefits

This paper discusses the use of water quality deterministic modelling together with an integrated approach to assess the impact of urban stormwater discharges into ephemeral watercourses, based on the study of a Portuguese catchment. The description of the main aspects, difficulties and benefits found during data collection and model calibration and verification is presented, and the associated uncertainties and errors discussed. Experimental results showed a strong short- and long-term impact of sewer discharges on rivers, and confirmed deposition, resuspension and transport of pollutants as important processes for the water quality. However, the resuspension of riverbed sediment pollutants during storms was probably more significant than the direct impact of the urban discharges. The HydroWorks model was used since it allows for the calculation of pollutant build-up on catchment surfaces and in gully pots, their wash-off, and the deposition and erosion of sediments in sewers. However, it uses several constants, which could not be independently calibrated, increasing the uncertainty already associated with the data. River flows have quite different magnitude from the sewer system overflows, which, together with the difficulties in evaluating river flow rates, makes the integrated modelling approach rather complex and costly.