Influence of drought, salt stress and abscisic acid on the resistance of tomato to Botrytis cinerea and Oidium neolycopersici

Abiotic stress may affect plant response to pathogen attack through induced alterations in growth regulator and gene expression. Abscisic acid (ABA) mediates several plant responses to abiotic stress. The effects of drought, salt stress and ABA on the interaction of tomato ( Lycopersicon esculentum ) with the biotrophic fungus Oidium neolycopersici and the necrotrophic fungus Botrytis cinerea were investigated. Drought stress resulted in a twofold increase in endogenous ABA as well as a 50% reduction in B. cinerea infection and a significant suppression of O. neolycopersici on tomato cv. Moneymaker. Salt stress did not affect B. cinerea infection, but significantly reduced infection by O. neolycopersici , with no obvious increase in endogenous ABA. Compared with the wild type, the ABA-deficient sitiens mutant was more resistant to O. neolycopersici and B. cinerea . Exogenous ABA resulted in increased susceptibility of sitiens to both pathogens, but did not increase the basal susceptibility of wild-type plants. It is concluded that, in tomato, drought and salt stress stimulate different, but possibly overlapping, pathogen-defence pathways which may not necessarily involve ABA. Meanwhile, basal endogenous ABA levels suppress the resistance of tomato to O. neolycopersici and B. cinerea , but an ABA increase above the basal level, resulting from exogenous application, does not increase susceptibility to these pathogens.     

Man-Specific,GalNAc/T/Tn-Specific and Neu5Ac-Specific Seaweed Lectins as Glycan Probes for the SARS-CoV-2 (COVID-19) Coronavirus

Seaweed lectins, especially high-mannose-specific lectins from red algae, have been identified as potential antiviral agents that are capable of blocking the replication of various enveloped viruses like influenza virus, herpes virus, and HIV-1 in vitro. Their antiviral activity depends on the recognition of glycoprotein receptors on the surface of sensitive host cells—in particular, hemagglutinin for influenza virus or gp120 for HIV-1, which in turn triggers fusion events, allowing the entry of the viral genome into the cells and its subsequent replication. The diversity of glycans present on the S-glycoproteins forming the spikes covering the SARS-CoV-2 envelope, essentially complex type N-glycans and high-mannose type N-glycans, suggests that high-mannose-specific seaweed lectins are particularly well adapted as glycan probes for coronaviruses. This review presents a detailed study of the carbohydrate-binding specificity of high-mannose-specific seaweed lectins, demonstrating their potential to be used as specific glycan probes for coronaviruses, as well as the biomedical interest for both the detection and immobilization of SARS-CoV-2 to avoid shedding of the virus into the environment. The use of these seaweed lectins as replication blockers for SARS-CoV-2 is also discussed.     

Viruses isolated from Culicoides midges in South Africa during unsuccessful attempts to isolate bovine ephemeral fever virus

Five viruses, unrelated to bovine ephemeral fever virus (BEFV), were isolated from Culicoides biting-midges collected during the summer months of the years 1968-69 and 1969-70 near a cattle herd in which cases of BEF occurred and at an open horse stable at Onderstepoort. These viruses were investigated by means of serological, electron-microscopical and physicochemical tests. It was established that 2 isolates, Cul. 1/69 and Cul. 2/69, were related to each other and belonged to the Palyam subgroup of the genus Orbivirus, that isolate Cul. 3/69 belonged to the equine encephalosis subgroup of the genus Orbivirus, while Cul. 1/70 was related to Akabane virus, which belongs to the Simbu subgroup of the family Bunyaviridae. One isolate, Cul. 5/69, though prevalent in the cattle population, could not be identified at this point. A brief serological survey indicated that the cattle in the nearby herd possessed antibodies against all the isolates except Cul. 3/69. BEFV could not be isolated in mice or in cultured cells from the wild-caught Culicoides.     

Transmission of jaagsiekte (ovine pulmonary adenomatosis) by means of a permanent epithelial cell line established from affected lungs.

An epithelial cell line, designated JS-15,4, has been established in culture from jaagiekte lesions and subcultured in vitro for almost 2 years. It exhibits morphological and other features of transformed cells and has been shown by electron microscopy to consist of type B ovine alveolar epithelial cells. Jaagiekte was successfully transmitted to 3 new-born lambs by the intratracheal injection of cells following immunosuppressive treatment with either anti-thymocyte immunoglobulin alone or combined with anti-macrophage immunoglobulin. Incubation periods as short as 10 weeks were recorded. Evidence was also obtained that natural transmission may result from the inhalation of viable cells.     

Light and electron microscopic observations on the development of Babesia bigemina in larvae, nymphae and non-replete females of Boophilus decoloratus

In Boophilus decoloratus infected by transovarian passage with B. bigemina, primary schizogony occurred as a continuous repetitive process in all 3 stages of the tick's life cycle spent on the host. The primary schizonts and the large merozoites (= vermicules) produced by them were observed in the gut epithelium, haemocytes, muscles, ad peritracheal cells. Secondary schizogony which led to the formation of small merozoites (= infective forms) occurred mainly in the salivary glands, but was also observed in the cortex of the synganglion. Mature small merozoites were observed in nymphal and adult ticks only. An infective stabilate was prepared from nymphae collected on Day 14 and Day 15 post larval infestation. The infections resulting from intravenous injection of the stabilate had a prepatent period of 8 days.     

Negative staining of a non-haemadsorbing strain of African swine fever virus.

Since the application of negative staining, preceded by fixation, prevents the disruption and distortion of the capsid of the African swine fever virus, improved contrast and evaluation of the appearance and size of virus particles in the electron microscope is possible and, in addition, the icosahedral shape of the virus is demonstrable. The mature virus particle contains at least 2 capsid layers and an outer envelope.     

Tetanus in the dog: review and a case-report of concurrent tetanus with hiatal hernia

: Tetanus with hiatal hernia was diagnosed in a four-month-old female sheepdog pup. The animal was treated with tetanus antitoxin, antibiotics, fluids and intensive nursing care for three weeks and subsequently made a full recovery.     

Deposition and depletion of five anticoccidials in eggs

Anticoccidials are compounds that are widely used as feed additives to prevent and treat coccidiosis. They are licensed for use in a prescribed concentration and during a certain time interval for broilers and pullets but not for laying hens. It was shown in the past that carry-over at the feeding mill is found to be the main reason for the presence of residues in eggs. An animal experiment was set up to investigate the effect of carry-over at the feeding mill on the presence of residues of anticoccidials in eggs. For the compounds diclazuril, robenidine, halofuginone and nicarbazin in combination with narasin, two concentration levels were tested: the maximum allowed concentration for broilers (100%) and a concentration corresponding to 5% carry-over during feed preparation. Also dimetridazole was included in the experiment but only at one concentration level. Eggs were sampled during treatment (14 days) and for a period of 30 days after withdrawal of the anticoccidial-containing feed. Residues were determined, and deposition and depletion curves were generated. Analyses were performed by ELISA and LC-MS/MS. For all compounds, substantial residues could be found in the 5% groups, which points out the risk of carry-over at the feeding mill. The distribution of the residues between egg yolk and white was determined by analyzing both fractions.