Dendritic cells in cattle: phenotype and function

Dendritic cells are professional antigen presenting cells derived from the bone marrow and distributed throughout body tissues where they are located in sites that are suitable for antigen uptake. They are central to the induction of immune responses in naive animals and thus have become targets in strategies that are aimed at modulating resistance to infection. Studies in cattle have shown that the dendritic cells are phenotypically heterogeneous and that the different phenotypes have different biological properties. The molecular basis for this variation has begun to be investigated and has led to the identification of a member of the SIRPalpha family of signal regulatory proteins (MyD1) on a subset of dendritic cells in afferent lymph. Uptake of antigen by cattle dendritic cells is by a number of mechanisms that can involve endocytosis via clathrin coated pits or via caveolae as well as macropinocytosis.     

Analyses of genes encoding Theileria parva p104 and polymorphic immunodominant molecule (PIM) reveal evidence of the presence of cattle-type alleles in the South African T. parva population

Restriction fragment length polymorphism analysis of PCR products (PCR-RFLP) and sequencing of the variable region of the p104 and PIM genes was performed on samples obtained from South African T. parva parasites originating from cattle on farms with suspected theileriosis and from buffalo. p104 and PIM PCR-RFLP profiles similar to those of the T. parva Muguga stock, an isolate that causes ECF in Kenya, were obtained from three of seven cattle samples collected on a farm near Ladysmith in KwaZulu-Natal Province. Amino acid sequences of the p104 and PIM genes from two of these samples were almost identical to the T. parva Muguga p104 and PIM sequences. This result supports findings from a recent p67 study in which p67 alleles similar to those of the T. parva Muguga stock were identified from the same samples. While these results suggest the presence of a cattle-derived T. parva parasite, reports of cattle-to-cattle transmission could not be substantiated and ECF was not diagnosed on this farm. Although extensive diversity of p104 and PIM gene sequences from South African T. parva isolates was demonstrated, no sequences identical to known cattle-type p104 and PIM alleles were identified from any of the buffalo T. parva samples analyzed. 'Mixed' PIM alleles containing both cattle- and buffalo-type amino acid motifs were identified for the first time, and there appeared to be selection of cattle-type and 'mixed'-type PIM sequences in the cattle samples examined.     

Effect of dextransucrase cellobiose acceptor products on the growth of human gut bacteria

The selective fermentation by human gut bacteria of gluco-oligosaccharides obtained from the reaction between the glucosyl group of sucrose and cellobiose, catalyzed by dextransucrases (DSR) from Leuconostoc mesenteroides , has been evaluated. Oligosaccharides were fractionated according to their molecular weight, and their effect on the growth of different bacterial groups was studied. To determine the structure (position and configuration of glycosidic linkages)-function relationship, their properties were compared to those of DSR maltose acceptor products (DSRMal) and of recognized prebiotic carbohydrates (fructo-oligosaccharides, FOS). Cellobiose acceptor products (DSRCel) showed bifidogenic properties similar to those of FOS. However, no significant differences related to molecular weight or isomeric configurations were found for DSRCel and DSRMal products.     

Timing and order of different insecticide classes drive control of Drosophila suzukii; a modeling approach

The spotted-wing drosophila, Drosophila suzukii Matsumura, is an invasive pest causing significant damage to soft skinned fruits. Control of D. suzukii is critical since there is no tolerance for infested fruit in the market. While most insecticides control one or more D. suzukii life-stages (e.g., egg, larvae, and adult), the impact of insecticides that are toxic to immature stages  is unclear on the subsequent generation of a field population. Insecticides were applied at field recommended rates on cherries and blueberries in the laboratory to determine immature D. suzukii mortality. Spinetoram, cyantraniliprole, malathion, methomyl, spinosad, and phosmet resulted in relatively high mortality of all immature life stages. Zeta-cypermethrin, cyclaniliprole, and fenpropathrin resulted in lower mortality of egg and all larval instars. Malathion was also applied to lowbush blueberries with different fruit sizes (small, medium, and large) in the laboratory and there was no statistical difference in mortality rates depending on fruit sizes. Mortality data from the laboratory experiments were used to parameterize a refined D. suzukii population model. The model revealed that the timing and order of different insecticide classes are important to control D. suzukii population. Model runs that included early applications of more effective insecticides resulted in high immature mortality and greater reduction of D. suzukii populations compared to treatments applied later.

     

Metabolism of bromoxynil octanoate in growing wheat

[¹⁴C]ring-Bromoxynil octanoate was applied to the leaves of wheat seedlings, which were cultivated in a growth cabinet under controlled conditions for 14 days. Fractionation of the metabolites present in the treated leaves, which accounted for about 63% of the radioactivity applied, indicated a complex metabolic pathway resulting from initial hydrolysis to free bromoxynil, followed by three consecutive or concurrent steps (a) hydrolysis of the cyano group to the amide and carboxylic acid, followed by decarboxylation to 2,6-dibromophenol (0.5% of the ¹⁴C applied), (b) replacement of one or both bromine atoms by hydroxy groups to 3-bromo-4,5-dihydroxybenzonitrile (1.3 %) and 3,4,5-trihydroxybenzo-nitrile (0.6 %) or their hydrolysis products, (c) replacement of one or both bromine atoms by hydrogen, giving 3-bromo-4-hydroxybenzonitrile (1.9 %) and 4-hydroxy-benzonitrile (0.6%) or their hydrolysis products. Some of the phenolic acids or phenols formed are natural plant constituents. The metabolites identified represented in all about 11 % of the herbicide applied, but no individual metabolite accounted for more than a small proportion of it.     

Determination of the efficacy of pyrantel pamoate at the therapeutic dose rate against the tapeworm Anoplocephala perfoliata in equids using a modification of the critical test method

A total of 59 equids (54 horses and five Shetland ponies) were treated with pyrantel pamoate once, at the dose rate of approximately 6.6 mg base kg-1, during the period November 1985-January 1988. The drug was administered as a paste formulation (51 equids) intraorally or as a suspension formulation by stomach tube (eight equids). The purpose of treatment was to evaluate the activity of pyrantel pamoate (at the therapeutic dose rate) for removal of the tapeworm, Anoplocephala perfoliata, by a modified (24-h) critical test. The presence or absence of tapeworms was not determined for the equids before treatment. Twenty-three (39%) of the 59 treated equids were found to be infected with A. perfoliata (from one to 180 specimens per infected equid) at necropsy. Removals varied from 67 to 100% (average 88%) for the 18 infected equids treated with the paste formulation. For the five infected equids treated with the suspension, removals were 58-100% (average 75%). The combined average removal of A. perfoliata for both formulations was 87%. Two abnormal (triradiate) specimens of A. perfoliata were recovered; one from each of two different equids.     

Multiple hereditary ocular anomalies in a herd of cattle

A Brahman x Santa Gertrudis herd of cows bred to a Hereford bull was evaluated because of a 3-year history of several calves born with congenital blindness. Multiple congenital ocular anomalies in 2 calves included microphthalmos, microcornea, microcoria, heterochromia iridis, microlentia, cataracts, retinal dysplasia, retinal detachment, anterior segment dysgenesis, acorea, and proliferation of the anterior neuroectoderm. On the basis of the lack of environmental factors and persistence of an intermittent problem when breeding to a single bull, a genetic defect was diagnosed as the probable cause. Dominant inheritance with varied expressivity may have best explained the lack of obvious signs in the bull, with emergence of various anterior and posterior segment defects in offspring from unrelated cows.