An immunogenic Onchocerca volvulus antigen: a specific and early marker of infection

Onchocerciasis (river blindness) is a serious health problem and a severe obstacle to social and economic development, especially in Africa. A complementary DNA fragment coding for an Onchocerca volvulus antigen (OV-16) was cloned and expressed in the plasmid vector pCG808fx. Immune responses to this O. volvulus-specific recombinant antigen were detectable in patients with documented onchocerciasis; the antibody response was also detectable at 3 months and at more than 1 year before infection could otherwise be detected in humans and in chimpanzees experimentally infected with O. volvulus third-stage larvae.     

Evaluating tracer selection for catchment sediment fingerprinting

Purpose

Recent sediment fingerprinting research has shown the sensitivity of source apportionment results to data treatments, tracer number, and mixing model type. In light of these developments, there is a need to revisit procedures associated with tracer selection in sediment fingerprinting studies. Here, we evaluate the accuracy and precision of different procedures to select tracers for un-mixing sediment sources.

Materials and methods

We present a new approach to tracer selection based on identifying and removing tracers that exhibit non-conservative behaviour during sediment transport. This removes tracers on the basis of non-conservative behaviour identified using (1) tracer-particle size relationships and (2) source mixing polygons. We test source apportionment results using six sets of tracers with three different synthetic mixtures comprising one, five, and ten mixture samples. Source tracer data was obtained from an agricultural catchment in northwest England where time-integrated suspended sediment samples were also collected over a 12-month period. Source un-mixing used MixSIAR, a Bayesian mixing model developed for ecological food web studies, which is increasingly being applied in catchment sediment fingerprinting research.

Results and discussion

We found that the most accurate source apportionment results were achieved by the selection procedure that only removed tracers on the basis of non-conservative behaviour. Furthermore, accuracy and precision were improved with five or ten mixture samples compared to the use of a single mixture sample. Combining this approach with a further step to exclude additional tracers based on source group non-normality reduced accuracy, which supports relaxation of the assumption of source normality in MixSIAR. Source apportionment based on the widely used Kruskal-Wallis H test and discriminant function analysis approach was less accurate and had larger uncertainty that the procedure focused on excluding non-conservative tracers.

Conclusions

Source apportionment results are sensitive to tracer selection. Our findings show that prioritising tracer exclusion due to non-conservative behaviour produces more accurate results than selection based on the minimum number of tracers that maximise source discrimination. Future sediment fingerprinting studies should aim to maximise the number of tracers used in source un-mixing constrained only by the need to ensure conservative behaviour. Our procedure provides a quantitative approach for identifying and excluding those non-conservative tracers.

     

Effect of feeding sheep on naturally spoiled rice straw, clover hay and concentrate feed mixtures

The effects of feeding naturally contaminated feedstuffs to sheep were investigated through feeding of contaminated and uncontaminated clover hay, rice straw, and concentrate feed mixture were compared. The highest level of contamination with fungi was observed in the concentrate feed mixture followed by clover hay and rice straw. The most dominant mycotoxin in the contaminated feedstuffs was zearalenone. Contamination resulted in increases of crude protein, ash and silica in feedstuffs while both ether extract and crude fibre decreased. In vivo digestibility of different diet constituents in both contaminated and uncontaminated feedstuffs were determined using four mature Rahmani rams. Contamination resulted in significant increase in the digestibility of dry matter, crude fibre and energy. Contamination affected feed intake of the different feedstuffs particularly the concentrate feed mixture. A metabolism trial was also conducted to study the nitrogen and mineral balance. Retention of nitrogen and calcium was reduced when mouldy feeds were given. On the other hand, magnesium was relatively increased. Blood analysis for sheep at the end of the trials resulted in elevated values of inorganic phosphorus and phospholipid phosphorus and declined total nitrogen, calcium, cholesterol, calcium/phosphorus ratio and cholesterol/calcium ratio due to feeding on mouldy ration. Results of the urine analysis during the metabolism trials proved that mouldy ration increased the estimated values of the concentration of calcium, magnesium and vitamin C; whereas pH values, total nitrogen, ammonia nitrogen and inorganic phosphorus were declined during the feeding on the mouldy ration. Mouldy feeds tested, seemed to have toxic, nephritic and hepatic effect.     

Impacts of rainstorms on soil erosion and organic matter for different cover crop systems in the western coast agricultural region of Syria

More and more cultivated coastal territories of Syria are being affected by increasing land degradation processes, specifically, by soil erosion due to non‐sustainable soil management. The use of cover crops can be considered an ideal solution to reduce the negative impacts of extreme rainfall events on soil erosion. However, there is no enough information about the main cultivated areas of Syria due to the current conflicts and the very few types of research conducted there. Therefore, the main aim of this research was to assess soil erosion (soil loss and sediment concentration) and hydrological response (run‐off and infiltration) considering the impact of different types of cropping systems on soil organic matter. To achieve this goal, using erosion plots, five grouped natural rainfall events and soil samples were collected, and infiltration measurements were performed between November 2012 and April 2013 (rainy season) on three different cropping systems (wheat, vetch, bean and control) with different sloping gradients (8% and 20%) in Tartous governorate (W Syria). Our results showed a cumulative rainfall amount from 68.8 to 201 mm during the study period. The highest sediment yield was generated in the control and wheat plots, registering 0.468 and 0.368 kg m^?2, respectively, with an inclination of 8%. For an inclination of 20%, the control and wheat plots registered 1.145 and 0.967 kg m^?2, respectively. In comparison with the control plots, there was a decrease in the total eroded organic matter, which ranged from 0.0579 (control) to 0.0289 (bean) kg m^?2 year^?1 in the plots with 20% inclination, and from 0.0233 (control) to 0.0069 (bean) kg m^?2 year^?1 with 8% inclination. To sum up, bean and vetch play an effective role to mitigate soil erosion, delay run‐off and reduce sediment yield. The output of this research provides first insights into the impact of different land uses on soil loss. Also, it could help rural inhabitants and farmers to correctly manage their soils against soil erosion processes.     

Evaluation of ground-level and space-borne sensor as tools in monitoring nitrogen nutrition status in immature and mature oil palm

Monitoring nitrogen (N) in oil palm is crucial for the production sustainability. The objective of this study is to examine the capability of visible (Vis), near infrared (NIR) and a combination of Vis and NIR (Vis + NIR) spectral indices acquired from different sensors for predicting foliar N content of different palm age groups. The N treatments varied from 0 to 2 kg per palm, subjected according to immature, young mature and prime mature classes. The Vis + NIR indices from the ground level-sensor that is green + red + NIR (G + R + NIR) was the best index for predicting N for immature palms (R² = 0.91), while Vis indices blue + red (B + R) and Green Red Index from the space-borne sensor were significantly useful for N assessment of young and prime mature palms (R² = 0.70 and 0.50), respectively. The application of vegetation indices for monitoring N status of oil palm is beneficial to examine extensive plantation areas.     

Molecular and serological prevalence of Babesia bovis and Babesia bigemina in cattle from central region of Syria

A total of 207 bovine blood samples were collected from clinically healthy cattle bred in central region of Syria and examined by Giemsa-stained blood smears, nested PCR, ELISA, and IFAT to determine the molecular and serological prevalence of Babesia bovis and B. bigemina. All samples were negative to Babesia spp. by microscopic examination of blood smears. On the other hand, the overall prevalence of B. bovis and B. bigemina was 9.18% and 15.46% by nPCR, 15.46% and 18.84% by ELISA, and 18.36% and 21.74% by IFAT, respectively. Mixed infections were detected in a total of 5 samples (2.4%) by nPCR, 16 (7.73%) by ELISA and 27 (13.04%) by IFAT. Statistically significant differences in the prevalence of the two infections were observed on the basis of age and location. These data provide valuable information regarding the occurrence and epidemiology of B. bovis and B. bigemina infections in Syrian cattle, which can be employed in developing rational strategies for disease control and management.     

Evapotranspiration, seed yield and water use efficiency of drip irrigated sunflower under full and deficit irrigation conditions

Deficit irrigation occurrence while maintaining acceptable yield represents a useful trait for sunflower production wherever irrigation water is limited. A 2-year experiment (2003–2004) was conducted at Tal Amara Research Station in the Bekaa Valley of Lebanon to investigate sunflower response to deficit irrigation. In the plots, irrigation was held at early flowering (stage F1), at mid flowering (stage F3.2) and at early seed formation (stage M0) until physiological maturity. Deficit-irrigated treatments were referred to as WS1, WS2 and WS3, respectively, and were compared to a well-irrigated control (C). Reference evapotranspiration (ET_rye-grass) and crop evapotranspiration (ET_crop) were measured each in a set of two drainage lysimeters of 2 m × 2 m × 1 m size cultivated with rye grass (Lolium perenne) and sunflower (Helianthus annuus L., cv. Arena). Crop coefficients (K_c) in the different crop growth stages were derived as the ratio (ET_crop/ET_rye-grass).

Lysimeter measured crop evapotranspiration (ET_crop) totaled 765 mm in 2003 and 882 mm in 2004 for total irrigation periods of 139 and 131 days, respectively. Daily ET_crop achieved a peak value of 13.0 mm day⁻¹ at flowering time (stage F3.2; 80–90 days after sowing) when LAI was >6.0 m² m⁻². Then ET_crop declined to 6.0 mm day⁻¹ during seed maturity phase. Average K_c values varied from 0.3 at crop establishment (sowing to four-leaf stage), to 0.9 at late crop development (four-leaf stage to terminal bud), to >1.0 at flowering stage (terminal bud to inflorescence visible), then to values <1.0 at seed maturity phase (head pale to physiological maturity). Measured K_c values were close to those reported by the FAO.

Average across years, seed yield at dry basis on the well-irrigated treatment was 5.36 t ha⁻¹. Deficit irrigation at early (WS1) and mid (WS2) flowering stages reduced seed yield by 25% and 14% (P < 0.05), respectively, in comparison with the control. However, deficit irrigation at early seed formation was found to increase slightly seed yield in WS3 treatment (5.50 t ha⁻¹). We concluded that deficit irrigation at early seed formation (stage M0) increased the fraction of assimilate allocation to the head, compensating thus the lower number of seeds per m² through increased seed weight. In this experiment, while deficit irrigation did not result in any remarkable increase in harvest index (HI), water use efficiency (WUE) was found to vary significantly (P < 0.05) among treatments, where the highest (0.83 kg m⁻³) and the lowest (0.71 kg m⁻³) values were obtained from WS3 and WS1 treatments, respectively. Finally, results indicate that irrigation limitation at early flowering (stage F1) and mid flowering (stage F3.2) should be avoided while it can be acceptable at seed formation (stage M0).     

Deficit irrigation under water stress and salinity conditions: The MOPECO-Salt Model

In both arid and semi-arid areas the use of saline water for irrigation is a common practice, even though it may cause a drop in crop yield and progressive soil salinization. In order to determine the most suitable irrigation strategy for higher yield, profitability, and soil salinity management of certain crops, the MOPECO-Salt Model has been developed. This model was first validated in the Eastern Mancha Agricultural System in Albacete (Spain) through a test carried out on onion crop in April-September 2009, where the simulated yield was 2% lower than the observed one. The model was then tested at Tal Amara Research Station in the Central Bekaa Valley Agricultural System (Lebanon) using data from a 5-year experiment on the effects of deficit irrigation on two cultivars of potato (Spunta: July-October 2001, and June-September 2002; and Agria: March-August 2004, 2005, and 2007). Furthermore, these results were compared with those obtained through AquaCrop, which does not currently assess crop response to salinity. Differences between observed and simulated yields were lower than 3% for MOPECO-Salt and up to 12% for AquaCrop. According to findings from simulations, the irrigation strategies without leaching fraction employed in both areas are remediable since the off-season rainfall is sufficient to wash out soluble salts supplied with irrigation water. Results showed that as much as 14.4% water could be saved when this strategy was adopted for onion crops.     

The measurement of three cytokine transcripts in naïve and sensitized ovine peripheral blood mononuclear cells following in vitro stimulation with bluetongue virus serotype-23

Bluetongue (BT), a serious disease of sheep and some wild ruminants, is caused by bluetongue virus (BTV), a member of the family, Reoviridae. The current research thrust for controlling BT is on development of efficient vaccines, necessitating clear understanding of ovine immunology. At present, comparative studies on cytokine gene expression profiles of naïve and BTV-sensitized peripheral blood mononuclear cells (PBMC) in sheep have not been clearly understood. In the present study, PBMC from naïve and BEI-inactivated-saponin-adjuvanted BTV-1 vaccinated sheep were stimulated in vitro with heterologous BTV-23. At various intervals, RT-qPCR was carried out to estimate cytokine (interferon-gamma, interleukin-12 and interleukin-2) mRNA expressions that are linked to cell-mediated immunity. The results showed that PBMC cytokine profiles were relatively increased both temporally and quantitatively in immunized sheep PBMC compared to naïve ones, suggesting that BTV-1 vaccination may prime immune system that can cross-react with BTV-23 antigens.