Liming and reacidification reactions of a forest lake ecosystem,lake Lysevatten,in SW Sweden

Long-term monitoring, 1973 to 1987, of reactions to liming and reacidification of a forest lake ecosystem near the Swedish west coast is reported in this study. Treatment of Lake Lysevatten with a slag product of limestone in 1974 resulted in neutralization and a positive alkalinity. Prolonged dissolution proceeded for about 7 yr whereby 86% dissolved. During 1984–86 Lake Lysevatten approached maximum reacidification with high Al concentrations and an affected biota. Asellus aquaticus L. decreased and dominance within chironomid groups approached preliming conditions. However, the most obvious biological change was the development of the filamentous algal genus Mougeotia and increased growth of Sphagnum. Populations of both plants increased notably when pH declined to about 5. Our study suggests that extensive reacidification (pH < 6.0) of limed lakes should be avoided by successive treatments to prevent development of destabilized lake ecosystems.     

Agronomic characterization of diploid hybrid families derived from crosses between haploids of the common potato and three wild Argentinian tuber-bearing species

Five diploid hybrid families derived from crosses between haploids of three Argentinian cultivars and three diploid wild species,Solanum gourlayi, S. chacoense andS. spegazzinii, were evaluated in a field experiment in Balcarce. All plants were androsterile and, thus, could not be screened for 2n pollen production. Data on agronomic tuber traits were statistically analyzed. Differences among families were non-significant for tuber number/plant, but were significant for tuber weight/plant and dry matter content (with values above 21.0% in two of them). The relative frequencies of tubers in the categories established for size, skin texture, and eye depth were family dependent, but they were familiy independent in the categories established for tuber shape and skin color. Great morphological variability was detected for all the traits studied, and plants with high yield and high dry matter content were identified. These families can be used as sources of germplasm in breeding and to explore heterotic responses in 2x × 4x crosses, given the capacity of some plants to produce 2n eggs, as found in a related investigation.     

Rarity and decline in bumblebees - A test of causes and correlates in the Irish fauna

Bees are believed to be in decline across many of the world’s ecosystems. Recent studies on British bumblebees proposed alternative theories to explain declines. One study suggested that greater dietary specialization among the rarer bumblebee species makes them more susceptible to decline. A second study disputed this theory and found that declines in British bumblebees were correlated with the size of species’ European ranges, leading to the suggestion that climate and habitat specialization may be better indicators of the risk of decline. Here we use a new and independent dataset based on Irish bumblebees to test the generality of these theories. We found that most of the same bumblebee species are declining across the British Isles, but that, within Ireland, a simple food-plant specialization model is inadequate to explain these declines. Furthermore, we found no evidence of a relationship between declines in Irish bumblebees and the size of species’ European ranges. However, we demonstrate that the late emerging species have declined in Ireland (and in Britain), and that these species show a statistically significant westward shift to the extremity of their range, probably as a result of changing land use. Irish data support the finding that rare and declining bumblebees are later nesting species, associated with open grassy habitats. We suggest that the widespread replacement of hay with silage in the agricultural landscape, which results in earlier and more frequent mowing and a reduction in late summer wildflowers, has played a major role in bumblebee declines.     

Bayesian estimation in maternally ancestral animal models for weaning weight of beef cattle

The Bayesian approach was implemented for fitting several maternally ancestral models for weaning weight data of Angus calves. The goal was to evaluate to what extent genetic evaluation models with additive grand maternal effects (G), or with an ancestrally structured covariance matrix for maternal environmental effects (E), or with a sire × year interaction (ISY), or combinations thereof (GE, GSY, ESY, GESY), redistribute the additive variability and reduce the negative magnitude of the additive correlation between direct and maternal effects (r(AoAm)), when compared with the regular maternal animal model (I). All animals with records had known dams and maternal granddams. The sampling scheme induced low autocorrelations among all variables and tended to converge quickly. The signs of the estimates of r(AoAm) were consistently negative for all models fitted. The magnitudes of the estimates of r(AoAm) from models E, G, GE, ESY, and GESY were almost one-third of those from models I and ISY. Inclusion of the sire × year interaction had some effect in reducing the negative magnitude of r(AoAm), but also reduced the size of the estimates of direct (h(0)(2)) and maternal (h(m)(2)) heritabilities. In comparison, models E or G reduced the negative magnitude of r(AoAm) by 0.50 units and produced more favorable estimates of H(0)(2) and h(m)(2) than models I and ISY. The estimate of h(0)(2) from G was similar to the one from I; however, the estimated h(m)(2) was 0.04 units greater, whereas the estimate of r(AoAm) was much less negative (-0.21 vs. -0.71) than the respective estimates from I. The environmental correlation between the weaning weights of dams and their daughters (λ) was estimated to be -0.28 ± 0.03 in E and ESY, and -0.21 ± 0.03 in GE and GESY. Inclusion of the sire × year interaction effect by itself did not have much of an impact in the reduction of the estimated magnitude of r(AoAm). Rank correlations among EBV for direct effects were larger than 0.94 and did not show any appreciable difference among models, whereas the rank correlation among maternal breeding values displayed differences in the ranking between I and the other models. Models E and ESY recovered the largest amount of total additive variability with maternal effects.     

Leptospirosis in Colombia: Isolation ofLeptospira SPP. from the kidneys of brown rats (Rattus Norvegicus) trapped on infected piggeries

Summary Leptospira interrogansserotypes pomonaand icterohaemorrhagiaewere isolated from the kidneys of Rattus norvegicustrapped on pomonainfected piggeries.The isolation of pomonafrom one of 111cultured kidneys, although of interest, strongly suggests that this rat does not play an important part in the epidemiology of infection by this serotype. Kidney tubular degeneration, focal mononuclear infiltrations and fibroplasia are morphological traces which remain after an attack of leptospirosis. The high percentage (48.6)of these lesions found in the rat kidneys examined does not seem to be related to serotype pomonabut to icterohaemorrhagiae.The importance of this last serotype in swine in the Cauca Valley has yet to be assessed.

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Leptospirosis En Colombia: Aislamiento DeLeptospira SPP. De Riñones De Ratas Pardas (Rattus Norvegicus) Atrapadas En Porquerizas Infectadas

Resumen Se aislóLeptospira interrogans serotipospomona eicterohaemorrhagiae de riñones deRattus norvegicus atrapadas en porquerizas infectadas porpomona. El aislamiento depomona de 1/111 riñones cultivados, aunque de interés, sugiere que esta rata no desempeña parte importante en la epidemiología de las infecciones por este serotipo.Degeneración tubular renal, infiltración mononuclear focal y fibroplasia son huellas morfológicas que quedan después de un ataque de leptospirosis. El alto porcentaje (48.6) de estas lesiones encontradas en los riñones de las ratas examinadas no parece estar relacionado con el serotipopomona sino con elicterohaemorrhagiae. La importancia de este último seroptipo en cerdos en el Valle del Cauca no se ha evaluado todavía.

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Leptospiroses En Colombie: Isolement DeLeptospira SPP. De Reins De Rats Bruns (Rattus Norvegicus) Captures Dans Des Porcheries

Résumé Les sérotypespomona eticterohaemorrhagiae deLeptospira interrogans ont été isolés de reins deRattus norvegicus capturés dans des porcheries infectées de (pomona?). L'isolement depomona sur une seule des 111 cultures de rein effectuées, bien qu'interessant, suggère fortement que ce rat ne joue pas un rôle important dans l'épidémiologie de l'infection par ce sérotype.La dégénerescence tubulaire des reins, des infiltrations ponctuelles par des monocucléaires et l'aspect fibreux constituent les traces morphologiques qui demeurent après une attaque de leptospirose. Le pourcentage élevé (48,6) de ces lésions trouvées dans les les reins des rats examinés semble être plus en rapport avec le sérotypeicterohaemorrhagiae qu'avec le sérotypepomona. L'importance du sérotypeicterohaemorrhagiae chez le porc de la Cauca Valley est encore à vérifier.

     

Evaluation of endotoxaemia in the prognosis and treatment of scouring merino lambs

This study looked at measurement of endotoxaemia as a tool in determining prognosis and probable response to treatment in scouring lambs. One hundred eighty-three lambs in the first 15-20 days of life, from eight Merino sheep farms located in the region of La Serena, south-west Spain, were used in this experiment. Scouring and normal/control lambs were selected following a clinical examination, the scouring group was further divided into subgroups, specifically those that did or did not survive 72 h following treatment. At the time of the clinical examination, faecal and blood samples were taken. Faecal culture and commercial faecal antigen tests for detection of enteropathogens in faeces and serum endotoxin measurement using chromogenic lymulus amoebocyte lysate (LAL) were carried out. Scouring lambs received 0.07 mg/kg liveweight halofuginone once a day for 3 days, a single oral dose of 0.20 mg/kg liveweight of spectinomycin and oral rehydration fluid. The pathogens isolated were Cryptosporidium spp. and Escherichia coli. The case fatality rate was 51% in the scouring lambs. Postmortem findings were consistent with enterotoxigenic E. coli infection. The concentration of endotoxin was 0.18 +/- 0.12 ng/ml in the control group, 0.35 +/- 0.17 ng/ml in the surviving lambs and 0.46 +/- 0.14 ng/ml in the non-surviving lambs. Significant differences between groups were found. Case fatality rate of the scouring lambs with endotoxaemia below 0.30 ng/ml was 0%, while it was 100% above 0.50 ng/ml. These results may be utilized as a prognostic indicator in lambs affected by E. coli and Cryptosporidium that will help aid in decision-making as to whether to treat a lamb or not based on its chances of survival.     

Phase I biotransformation of albendazole in lancet fluke (Dicrocoelium dendriticum)

Dicroceliosis, a lancet fluke infection, is a frequent parasitosis of small ruminants and the anthelmintic drug albendazole (ABZ) is effective in control of this parasitosis. The aim of our project was to study the metabolism of ABZ and ABZ sulphoxide (ABZ.SO) in lancet fluke. Both invitro (subcellular fractions of fluke homogenates) and exvivo experiments (adult flukes cultivated in medium) were performed for this purpose. ABZ was metabolised invitro by lancet fluke NADPH-dependent enzymes by two oxidative steps (sulphoxidation and sulphonation). The apparent kinetic parameters of these reactions have been determined. In the exvivo experiments, only ABZ sulphoxidation was observed. The stereospecificity in ABZ sulphoxidation invitro was slight, with preferential formation of (+)-ABZ.SO enantiomer. In contrast (−)-ABZ.SO formation predominated in exvivo experiments. Sulphoreduction of ABZ.SO occurred neither invivo nor exvivo. The detection of ABZ oxidative metabolites indicates the presence of drug metabolising oxidases in lancet fluke.