The use of bulked segregant analysis to accumulate RAPD markers near a locus for beet cyst nematode resistance in Beta vulgaris

Bulked segregant analysis (BSA) was used to accumulate RAPD markers near the beet cyst nematode resistance locus Hsl^pro-1 of sugar beet (Beta vulgaris L.). Graphical genotypes constructed from RFLP data were utilized to select F₂ individuals in (1) the construction of pools of plants used in the initial screening for polymorphisms, and (2) the selection of individual plants used to confirm the potential linkage. The pooled DNA samples were screened for polymorphisms using 668 RAPD primers. Forty-four candidate markers potentially linked to the region were analysed further using 14 segregating individuals. Close linkage was confirmed for 17 of the markers. Four of the RAPD markers were assigned map coordinates within the RFLP map. Three of these markers extended the RFLP map by 3cM. Altogether, the 8cM target interval contains 10 RFLP and 17 RAPD markers, corresponding to an average marker density of 0.3cM in the Hsl_pro-1 region.     

A high-throughput DNA extraction method for barley seed

A non-destructive, quick DNA extraction method for barley seed is described. The method is simple and consists of drilling out a sample from the seed, adding sodium hydroxide, heating in a microwave oven and neutralizing with Tris-HCl. The seed DNA extract can be used directly for PCR with extra cycles added to the PCR programme compared to PCR programmes used for leaf extracts. This protocol was developed in particular for a micro satellite marker genetically linked to barley yellow mosaic virus resistance, but it can be applied toother markers of interest for barley breeding. The quick seed extraction protocol makes it possible to handle thousands of samples per day. Extraction of DNA from seed also facilitates transfer of plant material compared to the long-distance transfer of leaf samples. This revised version was published online in July 2006 with corrections to the Cover Date.     

Autonomic innervation of the ovary of the Atlantic cod,Gadus morhua

The autonomic innervation of the ovary of the Atlantic cod was investigated using histochemical and physiological/pharmacological methods. The paired ovary receives autonomic innervation via branches of the posterior splanchnic nerve (vesicular nerve).Histochemical studies demonstrated vasoactive intestinal polypeptide (VIP)-immunoreactive, 5-hydroxytryptamine-immunoreactive and adrenergic nerve fibers, but a number of antisera raised against other peptides failed to reveal any specific reaction in the tissue preparations. It is concluded that the cod ovary receives a double antagonistic autonomic innervation of excitatory cholinergic fibers and non-adrenergic inhibitory fibers. The nature of the inhibitory neurotransmitter is not known.     

Regulation of cardiac output and gut blood flow in the sea raven,Hemitripterus americanus

Coeliac artery blood flow (F_ca) before and after feeding was recorded in the sea raven. To obtain basic information about the scope of cardiovascular adjustment in the sea raven, a separate series of experiments was performed, in which ventral (P_va), and dorsal (P_da) aortic blood pressure, heart rate (HR) and cardiac output (jaz) were monitored during rest and encouraged exercise.Measurements of coeliac artery flow showed that visceral blood flow is substantial, particularly after feeding, and variations in the visceral vascular conductance affect P_da directly. Simultaneous recordings of intestinal and dorsal aortic blood pressures showed no measurable difference in the two arterial pressures, refuting the idea of a vascular control at the level of the main coeliac artery. Thus, in the sea raven, the adrenergic tonus affecting the visceral vasculature presumably acts at the arteriolar level.Sea ravens encouraged to exercise increased theirjaz by 64%; 32% through HR and 25% through stroke volume. The increase injaz during encouraged exercise was sufficient to produce an elevation of both P_va and P_da, despite an increase of systemic vascular conductance, -adrenoceptor blockade with sotalol, however, severely impaired the increase injaz during exercise, and the change in P_da was reversed.During rest there were both an adrenergic and a cholinergic tonus affecting the HR, as revealed by the effects of injected pharmacological antagonists. Swimming activity decreased the cholinergic tonus, while the adrenergic tonus increased.     

A field evaluation of anthelmintics in horses in Sweden

A field evaluation of anthelmintics in 336 horses on 37 farms was conducted between February and May 1986 in Sweden. The herds, each comprising at least eight horses, had histories of grazing on permanent pastures and receiving regular treatments against parasites at least three times a year. Small strongyles were refractory to (pro)-benzimidazole drugs in all but one of 23 herds examined. There was an average reduction in egg output of approximately 60%, and approximately 30% of 205 horses examined were shedding less than 100 eggs g-1 7 days after treatment. There was great between-herd variation of both the faecal egg-count depression (6.4-90.4%) and drug efficacy (0.0-80.0%). The non-benzimidazole drugs under investigation were fully effective against mature small strongyles.     

Anoplocephala perfoliata in Horses in Sweden: Prevalence,Infection Levels and Intestinal Lesions

Distal ileum, caecum and proximal colon of 470 horses were examined for helminths during 1 year at an abattoir in central Sweden. The infection levels of the horse tapeworm Anoplocephala perfoliata, their stage of development, site of attachment and gross pathological lesions caused by the worm were recorded. Faecal samples from 395 of the horses were examined specifically for tapeworm segments and eggs in order to correlate these findings with the numbers in the alimentary canal. In total 65% of the horses were infected with A. perfoliata and the mean intensity of infection was 79 worms per infected horse with a maximum of 912. The level of infection was significantly higher in (1) 3rd and 4th than in 1st and 2nd quarter of the year; (2) older horses than in yearlings; (3) females than in males and geldings; (4) thoroughbreed and cold-blooded horses than in Swedish standardbreeds and ponies. The level of infection was unaffected by the usage of anthelminthics against nematodes. Of the horses examined 51% had 1-100 worms whereas 14% were infected with more than 100 worms. Of the tapeworm positive horses 72% had mixed infections with both adult and juvenile worms, 20% solely juveniles, and 8% solely adults. The severity of intestinal lesions exacerbated by increasing numbers of A. perfoliata. About 11% of the intestines examined had severe lesions, but there was no history of acute abdominal distress in any of the horses included in this study. Although the number of detectable eggs was significantly higher for horses heavily infected with A. perfoliata, the egg recovery among infected horses was only 35%. An additional field survey comprising 218 horses on 88 premises in central and southern parts of Sweden showed that the prevalence of A. perfoliata egg positive horses was the same as found on faecal examination during the abattoir survey.     

Rice-soil interactions in Vietnamese acid sulphate soils: impacts of submergence depth on soil solution chemistry and yields

Abstract. The aim of this study was to investigate the effects of water submergence depth on radial oxygen loss (ROL), soil solution chemistry and rice growth performance in acid sulphate soils in southern Vietnam. ROL was measured in a solution culture. In a separate pot experiment the impact of water submergence depth on rice growth and soil solution chemistry was studied. Three submergence depths were used in the two experiments (5, 10 and 15 cm). ROL declined with submergence depth and was significantly greater in young roots (with no root hairs) than in older roots. In the pot experiment rice growth and soil solution chemistry were clearly affected by the submergence depth. During the first crop at 5 cm submergence, there was a significantly higher yield and a higher oxidation state (pe+pH) compared to 10 or 15 cm submergence. The Fe concentration was significantly greater at the 5 cm depth compared to the 10 or 15 cm depth. SO₄^2– reduction was delayed at the 5 cm depth. Rice yield was c. 25% less at the 15 cm than at the 5 cm depth. During a second crop, there was a substantial SO₄^2- reduction and H₂S formation and almost no significant effects of submergence depth on either soil solution chemistry or crop yield. In a field experiment with a dry-season rice crop, yield and Fe, Al and SO₄^2– concentrations were higher at a shallow submergence depth than at greater depths in the same field, showing similar depth trends to those found during the first crop in the pot experiment. Farmers should be advised to use a shallow submergence depth and, if possible, avoid deep-rooted rice varieties. A conceptual model is suggested, which summarizes the relationships between ROL and soil solution chemistry.     

Epidemiology of porcine neonatal steatorrhoea in Sweden. 1. Prevalence and clinical significance of coccidal and rotaviral infections

A study of neonatal steatorrhoea in unweaned piglets was carried out in randomly visited herds. Isospora suis and rotavirus were shown to be incriminated in this type of enteric disease and these agents may be considered important enteropathogens for 1-3-week-old piglets in Sweden. More extensive studies of I. suis were undertaken in one large herd. It was found that steatorrhoea may appear in 4-day-old piglets but oocysts were not detected until some days latter. Piglets that were shedding I. suis were not necessarily steatorrhoeic but oocysts were more frequently found in steatorrhoeic faeces than in faeces of normal consistency. The earliest oocyst output was detected at 5 days of age, the average litterage at first appearance being 12.8 +/- 4.0 days. The occurrence of I. suis oocysts in piglets did not correlate with the oocyst output in sows, which almost exclusively included genus Eimeria. Repeated parasitological and virological examination of steatorrhoeic faecal samples from 5-10 litters per herd at an age of 1-3 weeks would be helpful for making a herd diagnosis.     

Component analysis of general resistance toPhytophthora infestans in clones from the Colombian potato collection

Summary Studies on the level of resistance to entrance and resistance to invasion within leaves indicated that the best genotypes in the Colombian material reached the level of cv. Record. No significant differences in resistance were found betweenS. tuberosum ssp.andigena andS. phureja clones. Resistance to entrance and resistance to invasion were correlated.

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Zusammenfassung Von 29 S?mlingen, die aus Selbstbefruchtung von 12 verschiedenen Klonen hervorgingen, wurden zwischen ein und fünfzehn Pflanzen auf Resistanz gegen das Eindringen und auf Resistenz gegen das Ausbreiten derPhytophthora infestans ins Blattwerk untersucht (Tablle 1). Die beiden Komponenten der Blattresistenz waren korreliert (r=0,63^***, Abb. 1). Keine signifikanten Unterschiede wurden im Ausmass der Blattresistenz zwischen den Klonen vonS. tuberosum ssp.andigena undS. phureja gefunden. Ein Vergleich mit den Feldresistenz-Standards zeigte, dass nur die besten Genotypen der kolumbianischen Kollektion den von der Sorte Record erbrachten mittleren Resistenzgrad erreichten (Tabelle 2).

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Résumé Une à quinze plantes, issues de 29 plants provenant de l'auto-pollinisation de 12 cl?nes différents ont été testées pour leur résistance à l'invasion du feuillage (tableau 1). Les 2 composants de la résistance foliaire sont corrélés (r=0,63^***, fig. 1). Aucune différence significative n'a été trouvée dans les niveaux de résistance foliaire entre les cl?nes deS. tuberosum ssp.andigena etS. phureja. Une comparaison avec les témoins de référence résistants au champ indique que seulement les meilleurs génotypes des collectes de Colombie atteignent le niveau moyen de résistance de la variété Record (tableau 2).

     

Boreal forests and tundra

The circumpolar boreal biomes coverca. 2 10⁹ ha of the northern hemisphere and containca. 800 Pg C in biomass, detritus, soil, and peat C pools. Current estimates indicate that the biomes are presently a net C sink of 0.54 Pg C yr^?1. Biomass, detritus and soil of forest ecosystems (includingca. 419 Pg peat) containca. 709 Pg C and sequester an estimated 0.7 Pg C yr^?1. Tundra and polar regions store 60–100 Pg C and may recently have become a net source of 0.17 Pg C yr^?1. Forest product C pools, including landfill C derived from forest biomass, store less than 3 Pg C but increase by 0.06 Pg C yr^?1. The mechanisms responsible for the present boreal forest net sink are believed to be continuing responses to past changes in the environment, notably recovery from the little ice-age, changes in forest disturbance regimes, and in some regions, nutrient inputs from air pollution. Even in the absence of climate change, the C sink strength will likely be reduced and the biome could switch to a C source. The transient response of terrestrial C storage to climate change over the next century will likely be accompanied by large C exchanges with the atmosphere, although the long-term (equilibrium) changes in terrestrial C storage in future vegetation complexes remains uncertain. This transient response results from the interaction of many (often non-linear) processes whose impacts on future C cycles remain poorly quantified. Only a small part of the boreal biome is directly affected by forest management and options for mitigating climate change impacts on C storage are therefore limited but the potential for accelerating the atmospheric C release are high.