Contrasting impact of whole-tree-harvesting on chemical quality of plant foliage in coastal versus inland forest

Whole-tree-harvesting (WTH) is gaining support as a means to obtain more bioenergy from forests. One aspect that is scarcely addressed is its impact on the chemical quality of post-harvest plant growth, which may initiate ecological cascade effects through, for example, altered patterns of herbivory and decomposition. We measured C:N ratios and phenolic compounds in foliage from birch Betula spp. that had grown naturally after WTH and conventional harvest (CH) on two boreal sites in inland and more coastal Norway, three or five years after harvest. We found that carbon concentrations were higher after WTH compared to CH on the near-coastal site in spring and summer, but not on the inland site. The only observed change in nitrogen concentration after WTH was that it was lower compared to CH on the near-coastal site in autumn. In line with these changes, the C:N ratio was higher with WTH throughout the season on the near-coastal site, ostensibly favouring production or accumulation of plant defence metabolites. Expectedly, we observed altered concentrations of several phenolic compounds with WTH, particularly at the near-coastal site. Further studies are needed to clarify patterns, but our data strongly suggest that sustainability assessments of WTH should not ignore impact on plant chemical quality, and its potential consequences for trophic interactions.     

Variation and population structure at microsatellite and isozyme loci in wild cabbage ( Brassica oleracea L.) in Dorset (UK)

We examined variation at four isozyme and seven microsatellite loci in natural populations of Brassica oleracea L. on the coast of Dorset. All loci were polymorphic, and the diversity index of isozyme loci was similar to that of the microsatellites. Both microsatellites and isozymes showed significant spatial differentiation of genetic variation, but the scale differed between the marker types. Significant non-random mating at isozyme loci was detected within small groups of about five plants, in which adjacent individuals were separated by less than 5 m. On the other hand, non-random mating at microsatellite loci was only detected within the Dorset region as a whole. F_ST was significant for all loci and there was evidence of isolation by distance at both microsatellite and isozyme loci. From these data we infer that there is low but significant amounts of gene flow among B. oleracea populations in Dorset. The differences in the genetic structure between the two types of marker may be due to higher mutation rates at the microsatellite loci; however, the data suggest that stepwise gain or loss of single repeat units is not the principal mechanism.     

Effectiveness of in vitro Methods for Predicting in vivo Fertilizing Capacity of Boar Spermatozoa Cryopresemed with 2% or 4% Glycerol1

Contents: Thirteen ejaculates from each of two boars that were greatly different in post-thaw sperm quality were frozen in either 2 or 4% glycerol (final concentration/split-sample). Frozen-thawed sperm were evaluated in vitro, for motility, acrosomal integrity (NAR), plasma membrane integrity (PMI), and for sperm penetration (SPA) of zona-free hamster eggs. To evaluate in vivo fertilizing capacity, 52 sows were inseminated once, 30–34 hours after onset of estrus. Ova were recovered from the reproductive tract 2–4 days following insemination and evaluated for cleavage and sperm binding. The two boars differed significantly for all in vivo and in vitro parameters. Motility and PMI were higher (P < 0.05) for sperm frozen with 4% than 2% glycerol whereas NAR was higher with 2% glycerol. Higher numbers of sperm were bound to eggs in vivo for sperm frozen with 4% than with 2% glycerol (P < 0.05). The fertilization rate for sperm frozen with 4% glycerol was not significantly higher than the fertilization rate for sperm frozen with 2% glycerol (P = 0.12). On the basis of these data, 4% rather than 2% glycerol may be close to optimum when freezing boar semen in straws. However, more extensive in vivo fertility testing is required to confirm this trend. Low correlations were observed between in vitro (and in vivo) evaluation of sperm quality and fertility when the effect of boar and glycerol concentrations was kept constant. Inhalt: Die Brauchbarkeit von in vitro-Methoden für die Voraussage der in vivo-Befruch-tungskapazität von Eberspermatozoen nach Tiefgefrierung mit 2% oder 4% Glycerin Von 2 Ebern, die sich in der Qualität ihres Auftauspermas deutlich unterschieden, wur-den je 13 Ejakulate mit 2% oder 4% Glycerinanted (Endkonzentration — split sample) tiefgefroren. Die aufgetauten Samenproben wurden in vitro nach Motilität, akrosoma-ler Integrität (NAR), Plasmamembran-Integrität (PMI) und im Spermapenetrationstest (SPA) am zonafreien Hamstereiüberprüft. Zur Beurteilung der Befruchtungskapazität in vivo wurden 52 Sauen 30–34 h nach Brunstbeginn einmalig besamt. 2–4 Tage nach der Besamung wurden die Eier aus dem Genitaltrakt gewonnen und auf Teilung und auf Anheftung von Samenzellen an der Zona pellucida beurteilt. Die beiden Eber wa-ren in allen In vitro- und In vivo-Parametern signifikant verschieden. Motilitat und PMI waren besser (p <0,05) für Spermien, die in 4% Glycerin konserviert waren, NAR bes-ser in 2%igem Glycerin. Nach Konservierung in 4% Glycerin waren mehr Spermien an der Eihülle angeheftet als nach 2% Glycerin (p < 0,05). Aber die Befruchtungsraten waren nach 4% und 2% Glycerinkonservierung praktisch nicht verschieden (p = 0,12). Auf der Grundlage dieser Ergebnisse ist zu folgern, daβ die Tiefgefrierkonservierung von Pelletsperma mit 4% Glycerin günstiger ist als mit 2% Glycerin; dieser Trend muβ jedoch in umfangreicheren In vivo-Fertilitätstests noch bestätigt werden. Wenn die Ef-fekte Eber und Glycerinkonzentration konstant gehalten wurden, dann wurden nur niedrige Korrelationen zwischen In vitro- und In vivo-Beurteilung von Spermaqualität und Fruchtbarkeit erhalten.     

Short-term reduction in egg production in laying hens treated with an agonist of GnRH.

1. In two experiments laying hens were treated with an agonist of gonadotrophin releasing hormone (GnRH) to induce a reduction in the secretion of luteinising hormone (LH) and a pause in egg production. 2. In experiment 1, 70-week-old laying hens were either given daily subcutaneous injections of saline for 7 d, offered whole oats for 7 d (nutrient restriction), given daily injections of the GnRH agonist [D-Trp6-Pro9 N-ethyl amide]GnRH for 7 d at 50 micrograms/kg or 100 micrograms/kg or administered 4 biocompatible implants each containing 120 micrograms of the GnRH agonist. 3. Weekly egg production was monitored for 7 weeks and blood samples were taken at weekly intervals and assayed for plasma LH and oestradiol. Egg production was reduced in the birds treated with the agonist (28 to 46% reduction) but not to the same extent as in the birds offered whole oats (92.3% reduction). 4. The treatments also reduced plasma LH and oestradiol in treated hens but again to a greater extent in the birds offered whole oats than the birds treated with the agonist. Egg production and plasma LH and oestradiol increased following the termination of the treatments. 5. The birds fed whole oats suffered a reduction in weight of 16.7% over the treatment period whereas there were increases in the weights of the birds treated with saline, 50 micrograms of GnRH agonist and the implants of GnRH agonist, but no change in birds treated with 100 micrograms of GnRH agonist. 6. The birds fed oats lost feathers over the treatment period but the birds in the other treatment groups suffered no loss. 7. In experiment 2 laying hens were either injected daily with saline or 200 micrograms GnRH agonist and weekly egg production and plasma LH and oestradiol were measured. As egg production was reduced by almost 60% in the birds treated with the agonist but did not completely cease. Reductions in plasma LH and oestradiol were also observed. All variables increased to pretreatment levels once treatment ceased. 8. These data confirm the effects of severely depriving hens of nutrients on egg production and the secretion of LH and oestradiol.(ABSTRACT TRUNCATED AT 400 WORDS)     

Direct effects of induced parturition on subsequent reproductive performance of dairy cows from commercial herds in south-western Victoria

SUMMARY Reproductive performance was compared between cows whose previous parturition was induced and non-induced cows with similar calving dates, in 49 winter-calving, pasture-fed, commercial dairy herds in south-western Victoria. Parturition was induced in winter when most cows were between 27 and 35 weeks of pregnancy. Reproductive performance was assessed during the next mating period after induction which was mainly in spring of the same year. Percentages of cows in induced and untreated groups that were not pregnant after the mating period (9.0% and 7.2%, respectively) did not differ significantly. Induction tended to increase the percentage of cows of unknown pregnancy status. Mean percentages for induced and untreated groups were 11.5% and 7.9%, respectively. Induced and untreated groups calved at similar intervals after the planned start of calving in the following year, and the percentages of groups that required induction in that year did not differ significantly. The direct effects of induced parturition on reproduction were therefore concluded to be minimal. In seasonal calving herds, improvements in reproductive performance could be expected among cows whose calving dates were altered substantially by induction, due to increased intervals from calving to mating start date .     

The intestinal and serum humoral immune response of mice to orally administered antigens in liposomes: II. The response to liposome-entrapped bacterial proteins.

Effective oral adjuvants are needed to improve the intestinal immune responses to oral vaccines that are based on relatively low molecular weight antigens refined from veterinary pathogens. Liposomes prepared by different methods and composed of phospholipids of varying transition temperature were used to entrap cholera toxin (CT) and fed to mice. No significant increase in the intestinal antibody nor the serum IgA antibody response was detected but levels of serum IgG anti-CT antibody were significantly elevated in the group fed CT in phosphatidylcholine-based liposomes. Levels of antibody were significantly reduced in the groups fed CT in dipalmitoylphosphatidylcholine liposomes. Escherichia coli wall extract (ECWE) entrapped in certain liposome types and fed to mice elicited significantly increased serum anti-ECWE antibody responses but intestinal antibody responses were insignificantly different from the controls. These results suggest that orally administered liposomes fail to act as potent intestinal adjuvants for the entrapped antigens of bacterial origin used in this study.