Inheritance of downy mildew resistance at cotyledon and adult-plant stages in ‘Couve Algarvia’ (Brassica oleracea var. tronchuda)

Parasitic nematodes damage white clover (Trifolium repens) roots, negatively impacting forage yield and persistence. No single gene resistance to nematodes has been identified in white clover. Trifolium semipilosum (2n = 2x = 16) genotypes exhibiting either complete resistance or susceptibility to infection by the clover root-knot nematode (CRKN), Meloidogyne trifoliophila, were identified. F₁ progeny (n = 92) of a pair-cross between ‘TsR’, a plant heterozygous for the resistance phenotype and ‘TsS’, a plant homozygous for the susceptible phenotype, were challenged with infective CRKN juveniles and evaluated subsequently for root galling. Segregation analysis indicated the resistance phenotype may be conferred by a single dominant allele at a locus (designated TRKR, Trifolium Root-knot Resistance) subject to segregation distortion. TsR, TsS, and bulked resistant and bulked susceptible F₁ progeny (n = 12/bulk) were screened using T. repens microsatellite (SSR) markers. Three SSRs revealed polymorphism in TsR and the resistant bulk, of which prs090 and prs247 map to loci on T. repens linkage group D2. Progeny were genotyped with these three SSRs and 23 additional SSRs from T. repens groups D1 and D2. Linkage analysis in both TsR and TsS demonstrated macro-synteny between T. repens group D homoeologues and the T. semipilosum linkage group (designated D_Ts) containing the TRKR locus. Significant segregation distortion was detected in TsR, and recombination in the central region of the T. semipilosum linkage group was suppressed relative to T. repens in both parents. These data demonstrate the opportunities and challenges for comparative mapping in Trifolium and characterisation of loci conferring resistance to plant-parasitic nematodes.     

Clinically relevant multidrug resistant Salmonella enterica in swine and meat handlers at the abattoir

The presence of multidrug resistant (MDR) Salmonella serotypes in slaughtered swine, carcasses, meat and meat handlers is scarcely evaluated. Recently we demonstrated that diverse Salmonella serotypes are frequently present in swine, pork meat and carcasses, and meat handlers at Portuguese abattoirs. Here we have characterized their antibiotic resistance phenotypes and genotypes, helping elucidate the flow of MDR Salmonella in the food chain. Testing 60 Salmonella isolates from different serotypes, the highest frequencies of resistance were observed for tetracycline (T) [70% (n = 42/60), tet(A)/tet(B)/tet(G)], streptomycin (S) [63% (n = 38/60), aadA2/strA/strB], sulfamethoxazole (Sul) [62% (n = 37/60), sul1/sul2/sul3] and ampicillin (A) [57% (n = 34/60), bla_PSE-1/bla_TEM]. Thirty-seven percent (n = 22/60) carried class 1 integrons and multidrug resistance was frequently observed (63% n = 38/60), including those serotypes common to human infections [S. Typhimurium 78% n = 25/32; S. 4,[5],12:i:- 67% n = 2/3; S. Rissen 75% (n = 3/4); S. London 67% n = 2/3; S. Derby 55%; n = 6/11)]. The emergent S. 4,[5],12:i:- isolates were mostly characterized by ASSuT phenotype [bla_TEM/strA-strB/sul2/tet(B)], typical of the European clone, while for the first time the ST phenotype [strA-strB-tet(A)-tet(B)] was also observed. Moreover, we report a first finding of a MDR phenotype in S. London [ANSSuT; bla_TEM-strA-strB-sul2-tet(A)]. Our findings suggest that the abattoir environment and the slaughter operations seem not only to harbor MDR serotypes that originated in the pig reservoir, but also propagate them through cross-contamination processes, involving meat handlers. The present study suggests a probable relationship between swine and human salmonellosis throughout the food chain, which is of interest for epidemiological, animal health and public health purposes.     

Comparative study of acetylcholine synthesis in organs of freshwater teleosts

The activity of acetylcholine (ACh) synthesizing enzyme, choline acetyltransferase (ChAT), and the content of ACh were determined in the brain, heart, red trunk muscle and midgut of 12 freshwater teleost species belonging to eight families: carp (Cyprinus carpio), tench (Tinca tinca), silver carp (Hypophthalmichtys molitrix), bighead (Hypophthalmichtys nobilis), wels (Silurus glanis), cat fish (Ictalurus nebulosus), eel (Anguilla anguilla), rainbow trout (Oncorhynchus mykiss), pike (Esox lucius), pike-perch (Stizosteidon lucioperca), ruffe (Acerina cernua) and pumpkinseed (Lepomis gibbosus). The rate of ACh degradation in the same tissues was characterized by measuring the activity of acetylcholinesterase (AChE). Comparisons by statistical evaluation of cholinergic parameters in the corresponding organs were made between the species or families. The highest ACh concentration was found in the brain (between 9.6 and 16.0 nmol/g), and the gut (4.6 to 17.4 nmol/g), followed by the heart (1.4 to 3.9 nmol/g) and trunk muscle (1.2 to 3.8 nmol/g). Good correlations were found between the ACh content and the ChAT activity in all the organs studied. The correlation coefficients were 0.92 and 0.72 for the brain and heart, respectively. The activity of ChAT and the amount of ACh found in the brain and trunk muscle varied considerably from one family to another, but was of comparable degree within one family. It was concluded that differences in the cholinergic parameters may reflect different feeding and swimming behavioral patterns.     

Dietary protein, growth, nutrient utilization and body composition of juvenile blackspot seabream, Pagellus bogaraveo (Brunnich)

When considering new marine species for Mediterranean aquaculture, blackspot seabream emerges as a potential candidate. However, there are scarce data on the nutritional requirements and optimal growth conditions of this species. A 12‐week feeding trial was conducted to evaluate the effects of dietary protein on growth, nutrient utilization and body composition of blackspot seabream (23 g). Five isolipidic diets (12%) with graded levels of protein (20–60%) were distributed, twice a day, to duplicate groups of fish, until satiation. Growth increased significantly with increasing dietary protein up to 40%, but higher protein levels induced a similar daily growth index (1.4). Feed conversion ratio (FCR) decreased with increasing levels of dietary protein (4.2–1.6). No significant differences were detected in protein of whole body blackspot seabream among treatments, but fat percentage decreased with increasing dietary protein. Dry matter and energy digestibility showed a concomitant increase with the reduction in dietary wheat meal, attaining maximal values with high protein diets. These results suggested that the most favourable values for growth and FCR are obtained with diets containing 40% protein. However, the excessive lipid deposition reveals that more nutritional studies are necessary before the species can be established in aquaculture.     

Live storage and drying of storm-felled Norway spruce (Picea abies,L. Karst.) and Scots pine (Pinus sylvestris L.) trees

Storm-felled trees left in the forest for a shorter or longer period, affect the quality of the logs. The change in quality is mainly because of attack of fungi and insects, which in turn depends on the moisture content (MC) of the sapwood. The purpose of this study was to receive more knowledge about drying of storm-felled trees by investigating how fast winter storm-felled Norway spruce and Scots pine dried when left in the forest. Sixteen storm-felled spruces with part of the roots still in ground contact were selected from three stands and in addition to 10 pines from one of the stands. The trees were examined for MC in the sapwood until 21 months after the storm. This study indicates that wind-thrown trees with roots still connected to the soil can survive one summer without any value loss caused by draught, fungi and insects. The stand conditions can be of importance as the storm-felled trees in the stand, with scattered windthrow, were in best condition after one year, as they were shadowed by the trees still standing. Comparing spruces and pines with the stand with scattered windthrow, pines were more sensitive to drought and reached critical MC earlier.     

Insulin-receptor binding in skeletal muscle of trout

Two hundred rainbow trout (Oncorhynchus mykiss) age 0 +, weight range 11.3 – 11.5 g, were distributed randomly in two groups and maintained for five weeks on either 10% dextrin, or 20% dextrin diet. The fish were sampled 3–5 h and 18–20 h after the last feeding and insulin binding to partially purified insulin receptors in white and red skeletal muscles and to liver plasma membranes was assessed. Plasma insulin, plasma glucose, and liver glycogen content were analyzed in the same fish.Fish fed a diet with higher carbohydrate content (HC) had elevated insulin and glucose levels in peripheral blood, but lower liver glycogen contents compared to the fish fed a diet with lower carbohydrate content (LC). No growth retardation was observed in the fish from HC group.Three to five hours after the last feeding, insulin-receptor binding in white skeletal muscles was higher in HC group of fish, mostly because of an increase in number of high affinity binding sites. Eighteen to twenty hours after the last feeding this difference disappeared. In contrast, the specific binding of insulin to the liver plasma membranes appeared to be lower in the HC group of fish. The lower insulin binding to the liver plasma membranes observed 3–5 h after feeding, could be attributed to the lower quantity of binding sites, while the same phenomenon 18 h after feeding was likely a result of affinity changes. We conclude that higher glycemic levels observed in trout fed a HC diet as compared to LC group of fish, are not a consequence of impaired binding of insulin to its receptors in skeletal muscles.Presented in part at the Annual Meeting of American Society of Zoologists, December 26–30, 1989, Boston, U.S.A. Supported by a grant (Personal investigador en el extranjero) of Ministerio de Educacion y Ciencia, (CYCIT) Spain to J.G. and by grants of the U.S. National Science Foundation (DCB 8615551 and DCB 8915935 to E.P.) and North Atlantic Treaty Organization (NATO) 0926/87 to C. Ottolenghi and E.P.     

Dissolved organic carbon and nitrogen leaching from Scots pine, Norway spruce and silver birch stands in southern Sweden

The effects of three common tree species - Scots pine, Norway spruce and silver birch - on leaching of dissolved organic carbon and dissolved nitrogen were studied in an experimental forest with podzolised soils in southern Sweden. We analyzed soil water collected with lysimeters and modeled water fluxes to estimate dissolved C and N fluxes. Specific UV absorbance (SUVA) was analyzed to get information about the quality of dissolved organic matter leached from the different stands. Under the O horizon, DOC concentrations and fluxes in the birch stands were lower than in the spruce and pine stands; annual fluxes were 21 g m⁻² y⁻¹ for birch and 38 g m⁻² y⁻¹ and 37 g C m⁻² y⁻¹ for spruce and pine, respectively. Under the B horizon, annual fluxes for all tree species ranged between 3 and 5 g C m⁻² y⁻¹, implying greater loss of DOC in the mineral soil in the coniferous stands than in the birch stands. We did not find any effect of tree species on the quality of the dissolved organic matter, as measured by SUVA, indicating that the chemical composition of the organic matter was similar in leachates from all three tree species. Substantial amounts of nitrogen was leached out of the soil profile at the bottom of the B horizon from the pine and birch stands, whereas the spruce stands seemed to retain most of the nitrogen in the soil. These differences in N leaching have implications for soil N budgets.     

Quality of rolled barley flakes as affected by batch of grain and processing technique

Rolled barley flakes were prepared from three different batches of grain by pearling, steaming and rolling. Autoclaved and malted barleys from the three batches were also processed in the same way. Analysis of the nine products showed that both batch of barley and process had significant effects on chemical composition and viscosity. Puddings were prepared from the products and mechanical consistency, juiciness and grain consistency were graded on both newly prepared and heated puddings by a sensory taste panel. Batch of barley had no effect on mechanical consistency but significant effects on juiciness and grain consistency. Type of processing had significant effect on all three parameters for both newly prepared and heated puddings.     

Characterisation of transgenic oilseed rape expressing pea lectin in anthers for improved resistance to pollen beetle

In order to evaluate pea lectin as a resistance factor against the pollen beetle (Meligethes aeneus), transgenic oilseed rape (Brassica napus) has been produced wherein the pea lectin gene expression is driven by a pollen-specific promoter. The aim of the present study was to identify and characterise non-segregating transgenic and non-transgenic lines to be compared in various future tests for benefits and risks associated with such transgenic crop plants. Three doubled haploid (DH) populations (1436, 1440 and 1451) expected to include lectin-producing lines and two DH populations (1443 and 1449) expected to be free of lectin were produced. All five populations originated from different transformation events in the cultivar Westar. The relative amounts of DNA from the marker gene cassette were quantified by conventional as well as real-time PCR analyses and lectin concentrations were estimated by western blot analysis. Two populations with high lectin concentrations, 1436 and 1451, contained higher amounts of the marker DNA and thus more lectin gene copies as compared with 1440 which had lower concentrations of the lectin. As expected all DH lines from 1443 and 1449 were free of lectin. Maximum pea lectin concentration obtained corresponded to 3% of total soluble protein in the anthers. There were significant differences between the populations with respect to bud and flowering stage phenology as well as seed yields, but the differences were not related to their transgenic status. All in all there were 171 lines tested for phenology and transgenic status, out of which 89 with similar phenology were subjected to tests for lectin concentration and seed yield, and 20 of these lines were retested in the next generation. Finally two lines with high lectin concentrations and one with an intermediate level along with two matching non-transgenic lines were selected for future benefit/risk experiments.