Nippostrongylus brasiliensis infection in the rat: 1. Production of bile lgA and serum lgG antibodies by adult rats

Bile lgA and serum lgG antibody responses were assayed by a micro ELISA technique. Antibodies of both classes were produced by 14 days after infection against whole worm antigens and worm metabolic product antigens, by adult rats infected once with $\text{Nippostrongylus brasiliensis}$. Rats were reinfected on day 28 and titres of both classes of antibody against both antigens were greater 7 and 14 days after reinfection than after the initial infection. Bile lgA antibodies were produced against phosphorylcholine after a single infection with the parasite but no increased response occurred after reinfection. The possible significance of lgA and lgG antibody responses in relation to immunity to intestinal nematode infections is discussed.     

Streamlining leaf damage rating scales for the fall armyworm on maize

Journal of Pest Science - The fall armyworm (Spodoptera frugiperda, Lepidoptera: Noctuidae), which is native to the Americas, has recently invaded Africa and Asia. There, it has become a major pest...     

Sandbar shark aggregation in the central Mediterranean Sea and potential effects of tourism

1. An aggregation of sandbar sharks Carcharhinus plumbeus occurs every summer around the remote uninhabited islet of Lampione (Pelagie Islands Marine Protected Area, south-western Mediterranean Sea), attracting an increasing number of tourists for a shark watching experience.
2. Despite the ecological and socio-economic importance of this rare occurrence in Mediterranean waters, there is a lack of scientific data and lack of information as to the potential impact of tourist activities on the presence and behaviour of this shark species.
3. Using baited underwater videos, this study provides the first assessment of this shark aggregation, as well as a preliminary evaluation of the potential effects that boating and diving activities may have on sandbar sharks during two different periods within the tourism season (July and September 2019).
4. Overall, 241 sandbar shark sightings (with up to five individuals together) were recorded in July, whereas there were only six sightings in September. The average MaxN was 1.18 hr⁻¹ (±0.21 hr⁻¹ SE) and 0.22 hr⁻¹ (±0.10 hr⁻¹ SE) individuals in July and September respectively. Higher frequentation levels of divers and boats significantly reduced the number of shark sightings at the aggregation site.
5. This study emphasizes the need for further investigations on Mediterranean shark aggregations and the implementation of specific conservation measures, such as an increase of protection level in Lampione and better enforcement, aside from strategies that promote sustainable tourism, including restrictions on the number of boats and divers’ visits per day. In the meantime, a precautionary approach aimed at regulating the interactions between tourists and sharks should be implemented through the application of a self-regulatory code of conduct for divers when sharks aggregate around the island.

     

A 50-year record of quinolone and sulphonamide antimicrobial agents in Seine River sediments

Purpose  

Even though sediments may represent a reservoir for antimicrobial agents, little is known about the persistence of these molecules over time or their accumulation. In this study, six antimicrobial agents, oxolinic acid, flumequine, nalidixic acid, norfloxacin, sulphamethoxazole and trimethoprim, were investigated in a sediment core from the Seine River. This work aimed to (1) measure antimicrobial agent contamination levels in the sediment and identify their origins, (2) obtain information on the persistence of these compounds in sediment over long periods (>4 years) and (3) show the existence of a historical record in sediment of river contamination by antimicrobial agents.     

Features of follicular dendritic cells in ovine pharyngeal tonsil: an in vivo and in vitro study in the context of scrapie pathogenesis

Although the alimentary tract has been suggested as the most likely portal of entry in natural scrapie, a growing amount of data indicates that the respiratory system and more specifically the pharyngeal tonsils serve as a natural portal of entry for scrapie. This study describes for the first time the broad cell populations in the lymphoid compartment of pharyngeal tonsils and more specifically inside the lymphoid follicles where the scrapie agent accumulates during the period of latency. Follicular dendritic cells (FDCs), stromal cells located in the light zone of the germinal centre of lymphoid follicles, seem to be the principal causal factor in the accumulation of the infectious agent in transmissible spongiform encephalopathy (TSE) diseases. Knowing that efficient lymphoreticular prion propagation requires PrPc expression, we analysed the expression of PrPc with the mouse monoclonal antibody Pri 909 both in situ and on FDC-cluster-enriched cell suspensions. In situ, a positive staining was observed in the germinal centre of pharyngeal lymph follicles. The germinal centre labelling was due to the presence of a follicular dendritic network as revealed after immunogold staining of isolated FDC clusters. Our results suggest that the pharyngeal lymphoreticular system and more specifically PrPc expressing follicular dendritic cells could serve as a prion "reservoir" during the latency phase, thus playing a key role during the scrapie lymphoinvasion.     

CRISPR/Cas9-Targeted Knockout of Rice Susceptibility Genes OsDjA2 and OsERF104 Reveals Alternative Sources of Resistance to Pyricularia oryzae

Rice genes OsDjA2 and OsERF104, encoding a chaperone protein and an APETELA2/ ethylene-responsive factor, respectively, are strongly induced in a compatible interaction with blast fungus, and also have function in plant susceptibility validated through gene silencing. Here, we reported the CRISPR/Cas9 knockout of OsDjA2 and OsERF104 genes resulting in considerable improvement of blast resistance. A total of 15 OsDjA2 (62.5%) and 17 OsERF104 (70.8%) T₀ transformed lines were identified from 24 regenerated plants for each target and used in downstream experiments. Phenotyping of homozygous T₁ mutant lines revealed not only a significant decrease in the number of blast lesions but also a reduction in the percentage of diseased leaf area, compared with the infected control plants. Our results supported CRISPR/Cas9-mediated target mutation in rice susceptibility genes as a potential and alternative breeding strategy for building resistance to blast disease.     

Patterns of algal recovery and small-scale effects of canopy removal as a result of human trampling on a Mediterranean rocky shallow community

The ecological importance of marine algae is widely known but in shallow coastal areas the composition and structure of algal communities may be affected by different human activities. Recovery from different trampling disturbances of two competing morphological groups (i.e. macroalgae and algal turfs) and effects of macroalgal canopy removal on the dominant associated fauna were examined using controlled trampling experiments. Six months after trampling disturbance was removed, the two morphological groups closely resembled control (untrampled) conditions, both in terms of cover and canopy (%). In particular, macroalgal recovery seemed to be very rapid: the higher the impact on the system the more rapid the recovery rate. In the short-term, the removal of macroalgal fronds (i.e. canopy) caused evident changes in invertebrate and crypto-benthic fish densities although these indirect effects were species-specific. Erect macroalgae are very sensitive to disturbance and even relatively low intensities of human use may be non-sustainable for this shallow assemblage. The present findings suggest some interesting options for the management of Mediterranean rocky shallow areas. This is crucial for coastal areas that are intended to be maintained in natural condition for conservation purposes.     

Possible correlations between the characteristics of Potato leafroll virus isolates occurring in different geographical regions in Tunisia

Biological and molecular characterization supported by transmission efficiency, symptom expression and Open Reading Frame 0 (ORF0) nucleotide sequence analysis were carried out to assess nine isolates of Potato leafroll virus (PLRV) collected from three Tunisian geographic and bioclimatic zones. Plant-to-plant transmission by Tunisian Myzus persicae aphid clones showed high transmission efficiency for all isolates tested. Symptom expression analysis on a Physalis floridana plant test distinguished viral isolates as very severe, severe and mild. The ORF0 sequences of the Tunisian PLRV isolates showed an assignment to two aggregates when compared with GenBank PLRV sequences. A significant correlation between symptom severity and ORF0 nucleotide sequence or between symptom severity and geographic origins of the PLRV isolates was established. However, the transmission efficiency and the ORF0 sequence were not affected by the bioclimatic origin. No significant correlation between transmission and symptom or between transmission and the ORF0 sequence was detected.