Histological mechanisms of the resistance conferred by the Ma gene against Meloidogyne incognita in Prunus spp

The Ma gene from Myrobalan plum is a TNL gene that confers a high-level resistance to all root-knot nematodes of major economic importance, including Meloidogyne incognita, M. javanica, M. arenaria, and M. enterolobii. The nematode behavior in the roots and the corresponding histological mechanisms of the Ma resistance to M. incognita in the resistant (R) accessions of the plum 'P.2175' and the interspecific hybrid P.2175×almond-peach '35', carrying the Ma1 allele (Ma1/ma), were characterized in comparison with the susceptible (S) accessions in the plum 'P.2032' and the interspecific hybrid P.2175×almond-peach '253' (ma/ma). Second-stage juveniles (J2s) were inoculated in micropropagated plantlets grown in soil substrate under controlled conditions at 25°C. Nematodes penetrated both R and S plants preferentially along the apical zone or close to the young lateral buds and moved via similar routes. Then they migrated into the cortex downward in the direction of the apex and turned up in the meristematic apical region to colonize the differentiating stele. In R accessions, motile J2s neither swelled nor developed into J3s, and initiation of feeding sites was never observed. This complete absence of gall symptoms is associated with cell necroses and corresponding hypersensitive-like reaction (HLR) phenotypes occurring either in the stele or in the meristematic apical region or in the cortex. Nematode attacks often disorganized the meristematic apical tissues of R accessions, which induced the development of subterminal lateral roots replacing primary terminal apices and, thus, provided an active resistance reaction to HLR damage.     

Effects of Prolonged Exposure to Low‐Dose Fumonisin B1 in Pigs

From the point of view of human exposure, fumonisins (FB₁, FB₂, FB₃, FB₄), a relatively recently (1988) discovered and identified group of mycotoxins, represent one of the five most important mycotoxin groups causing human disease. In an earlier experiment studying the effects of relatively low doses (10, 20 and 40 p.p.m.) of FB₁ in weaned piglets, it was established that the 4‐week feeding of 10 p.p.m. (mg/kg feed) FB₁ produced mild pulmonary oedema. This suggested the importance of studies with even lower doses of the toxin to determine the tolerable limits. The objective of this experiment was therefore to study the effects of prolonged (8‐week) exposure to still lower concentrations (0, 1, 5 and 10 mg/kg feed) of FB₁. The 8‐week feeding of FB₁ in low concentrations (1–10 p.p.m.) did not cause clinical signs and significant performance impairment in pigs, but rendered irreversible the chronic changes that had already developed in the animals in a dose‐dependent manner. Dissection revealed pathological alterations of the lungs in one of the animals given 1 p.p.m. (n=4), in two animals exposed to 5 p.p.m. (n=5), and in three animals given 10 p.p.m. (n=4). In all three treatment groups, proliferation of the connective tissue fibres, primarily of those around the lymphatic vessels, in the subpleural and interlobular connective tissue of the lungs, extending to the peribronchial and peribronchiolar areas, was seen. The results of this experiment call attention to the risk of prolonged low‐dose toxin exposure, which has very important public health implications.     

Conjugated linoleic acid depresses the delta9 desaturase index and stearoyl coenzyme A desaturase enzyme activity in porcine subcutaneous adipose tissue

Conjugated linoleic acid (CLA) has been shown to have an effect on subcutaneous fatty acid composition and has been reported to decrease stearoyl coenzyme A desaturase (SCD) activity by decreasing mRNA expression and(or) catalytic activity in rodents and rodent cell lines. This investigation was designed to study the effects of CLA, corn oil, or beef tallow supplementation on s.c. adipose tissue fatty acid composition, adiposity, SCD enzyme activity, and the delta9 desaturase index in piglets. Eighteen crossbred barrows 16 to 18 d of age were adapted to diet for 1 wk and then assigned randomly to one of three treatments: 1.5% added CLA, 1.5% added corn oil, or 1.5% added beef tallow. Barrows were penned individually and fed the supplemental oils for 35 d (to 25.6 +/- 0.6 kg BW). Subcutaneous adipose tissue samples were obtained after slaughter. Fatty acid composition of the s.c. adipose tissue differed for each fatty acid measured due to diet with the exception of 18:3. The concentrations of CLA trans-10, cis-12 and cis-9, trans-11 were elevated from nondetectable to 1.62 and 2.52 g/100 g lipid, respectively (P < 0.001 for both isomers). Conjugated linoleic acid decreased the delta9 desaturase index (P < 0.01) and SCD enzyme activity, expressed as nanomoles of palmitate converted to palmitoleate/(7 min x g of tissue) (P = 0.075) and nanomoles of palmitate converted to palmitoleate/(7 min 105 cells) (P= 0.056). Tallow-fed pigs had a greater proportion of large adipocytes (> 700 pL) and the greatest SCD activity. These data provide the first direct evidence that dietary CLA depresses SCD enzyme activity in porcine adipose tissue, which may in part be responsible for the depression of adiposity by CLA observed by others in market weight pigs.     

Growth,viscosity and beta‐glucanase activity of intestinal fluid in broiler chickens fed on barley‐based diets with or without exogenous beta‐glucanase

1. Three groups of birds were fed for up to 35 days on diets containing 500 g barley (cv. Condor) /kg diet, with or without exogenous β‐glucanase, either a commercial preparation or a recombinant endoglucanase.

2. Birds which received diets containing the exogenous enzymes grew faster for the first 3 weeks but after that there was no apparent difference in rate of growth.

3. β‐Glucanase activities in the crop and small intestine of birds given exogenous enzymes were generally higher than those of birds given only the basal diet.

4. Viscosity of intestinal fluid in birds given only the basal diet decreased with age but there was no corresponding increase in β‐glucanase activity. This discounts bacterial β‐glucanase as a contributory factor in the adaptation to β‐glucanase apparent in older birds.     

An improved polymerase chain reaction assay for the detection of Tritrichomonas foetus in cattle

An improved polymerase chain reaction test has been developed to detect Tritrichomonas foetus, the causative agent of trichomoniasis in cattle. The test amplifies a region of the 5.8S ribosomal RNA gene of T. foetus, and it is simple, sensitive, and specific when compared with traditional methods to examine field samples.     

Conjugated Linoleic Acid and Dietary Fats Differentially Affect Hepatic ACAT Activity and LDL-Cholesterol in Postweanling Pigs Fed Low-Fat Diets

Two separate studies tested the hypoth-esis that plasma low-density lipoprotein cholesterol (LDL-C) can be decreased by conjugated linoleic acid (CLA) by depressing hepatic acyl-coenzyme A: cholesterol acyltransferase (ACAT) activity. In the first experiment, 3 groups of 6 early-weaned piglets were fed low-fat diets containing either 1.5% CLA, 1.5% corn oil or 1.5% beef tallow;fat provided 8% of the energy intake. In the second experiment, 4 groups of 6 early-weaned piglets were fed high-fat di-ets containing either 15% beef tallow, 12% beef tal-low plus 3% CLA, 15% corn oil, or 12% corn oil plus 3% CLA; fat provided 29% of energy intake. Cholesterol was balanced across diets in both experi-ments. In pigs fed the low-fat diets, all dietary fats in-creased LDL-C and triacylglycerols and decreased high-density lipoprotein cholesterol (HDL-C) and very low-density lipoprotein cholesterol (VLDL-C). LDL-C was the same in pigs fed low-fat tallow or low-fat CLA diets. However, ACAT activity was near-ly 80% higher in pigs fed the low-fat tallow diet than in pigs fed the low-fat CLA diets. All high-fat diets increased LDL-C, HDL-C and triacylglycerols equally with no effect on VLDL-C. There were no unique fat-ty acid effects of the high-fat diets on ACAT activity.We conclude that supplemental fats had differential effects on hepatic ACAT activity and LDL-C, but on-ly in pigs fed low-fat diets.     

A wandering mind is an unhappy mind

We developed a smartphone technology to sample people's ongoing thoughts, feelings, and actions and found (i) that people are thinking about what is not happening almost as often as they are thinking about what is and (ii) found that doing so typically makes them unhappy.