Metabolic responses to exogenous bovine somatotropin in Friesian cows of low or high genetic merit

Basal hormone/metabolite concentrations and responses to intravenous challenges of glucose, insulin and epinephrine were examined in Friesian cows from selection lines of low or high genetic merit treated with recombinantly-derived bovine somatotropin (bST) or control formulation in a 2 x 2 factorial design. Cows from the low genetic merit (low breeding index, LBI) line had previously been shown to be more responsive to the galactopoietic effects of bST (50 mg/day) than those from the high breeding index (HBI) line. Despite this, comparisons of metabolic differences were not confounded by differences in energy balance because bST treatment had also caused an increase in voluntary intake of cut pasture. Circulating levels of somatotropin, insulin-like growth factor-I (IGF-I) and insulin were greater in bST-treated than control cows but neither bST treatment nor selection line influenced basal concentrations of glucose, non-esterified fatty acids (NEFA), beta-hydroxybutyrate, urea or creatinine. Treatment with bST produced a small increase in sensitivity of cows to the lipolytic effects of epinephrine and this effect was similar in both selection lines. HBI cows had greater circulating insulin levels following the glucose challenge than LBI cows but bST treatment did not affect the insulin response to exogenous glucose. Whereas bST treatment retarded the glycogenolytic response to epinephrine and the clearance of blood glucose in response to insulin in LBI cows, it had no effect on epinephrine-stimulated glycogenolysis, and caused enhanced glucose clearance in response to insulin, in HBI cows. Results are consistent with bST altering the homeorhetic control of metabolism but do not adequately explain the greater responsiveness of LBI cows to the galactopoietic effects of bST.     

Characterizing the complexity of landscape boundaries by remote sensing

This paper presents a method for characterizing the complexity of landscape boundaries by remote sensing. This characterization is supported by a new boundary typology, that takes into account points where three or more landcovers converge (i.e., convergency points or coverts). Landscape boundary richness and diversity indices were proposed and calculated over 19 landscapes in South-East Brazil. Results showed that landscape boundaries, especially convergency points, provided an enrichment in landscape pattern analysis. Landcover boundary diversities were significantly related to landcover shape: elongated riparian units had the highest values for boundary diversity and coverts proportion indices. On the other hand, landscape analysis showed that indices of shape, richness, diversity and coverts proportion provided an additional evaluation of landcover spatial distribution within the landscape.     

DNA sequences coding for the F18 fimbriae and AIDA adhesin are localised on the same plasmid in Escherichia coli isolates from piglets

The adhesin-involved-in-diffuse-adherence (AIDA) afimbrial adhesin is produced by human, but not by animal, Escherichia coli, with the exception of German porcine verotoxigenic Escherichia coli (VTEC) [Clin. Diagn. Lab. Immunol. 8 (2001) 143]. Presence and localisation of DNA sequences (aidA) coding for and production of an AIDA adhesin were investigated in a collection of Belgian VTEC and non-VTEC E. coli isolated from piglets at weaning time. The 174 isolates were also studied by colony hybridisation for the presence of DNA sequences coding for the Stx2e verocytotoxin and the F18 fimbrial adhesin (fed): 71 were Stx2+F18+AIDA+, 26 were F18+AIDA+, 12 were AIDA+, two were Stx2+AIDA+, and one was Stx2+ only. Fifty-four of the 58 (F18+)AIDA+ isolates tested positive in a western blotting assay with an immune serum raised against the AIDA protein. Hybridisation with the AIDA gene probe on plasmid DNA profiles identified a probe-positive plasmid band in the 10 AIDA+ and in 24 of the 25 F18+AIDA+ isolates studied. Moreover in F18+AIDA+ isolates, only one plasmid band hybridised with both F18 and AIDA probes. These results confirm the presence of aidA-related genes in not only VTEC, but also non-VTEC, isolates from piglets and the production of an antigenically AIDA-related protein by the majority of probe-positive E. coli. Moreover the plasmid DNA hybridisation results suggest a localisation on the same plasmid of the aidA- and fed-related DNA sequences.     

Adaptations of glucose metabolism in multiparous sows: effects of pregnancy and feeding level

This experiment was undertaken to determine whether pregnancy affects glucose metabolism and insulin sensitivity in sows fed at different levels. Four replicates of six multiparous Large White sows were involved. In each replicate, four sows were inseminated on the first postweaning estrus (pregnant group) and the two remaining were kept nonpregnant. Half of the sows of each group were fed 2.5 kg/d (low level) and the others 4 kg/d (high level) of the same standard pregnancy diet. Jugular catheters were implanted 2 to 3 d after estrus. Plasma concentrations of glucose, insulin, and FFA were determined before and during the 4 h following the morning meal at 10, 30, 59, 87, 93, 101, and 110 d of gestation and at equivalent periods for the nonpregnant sows. Intravenous glucose tolerance tests were performed at 33, 71, 85, 96, and 108 d by i.v. injection of 0.5 g glucose/kg BW. Compared with the glycemia before the meal, all the sows showed hyperglycemia 30 min after the initiation of the meal and hypoglycemia thereafter, with a minimum reached at approximately 75 min. Insulinemia increased from 20 min after food access, reached a maximum at 40 min, and returned to the basal level after 180 min. The higher feeding level increased plasma insulin and lowered plasma glucose levels. Glycemia and insulinemia profiles changed from 87 d onward in the pregnant sows. The peak of glucose induced by the meal was higher, and the subsequent period of hypoglycemia almost disappeared. The area under the insulin curve was unchanged, but insulin secretion was delayed. The glucose tolerance tests showed that between d 85 and 108 the half-life of injected glucose increased and insulin secretion was delayed in the pregnant sows. Compared to the following stages, plasma FFA were high before and after the meal at 10 d, which most likely was a residual effect from the previous gestation/lactation cycle. They were lower from 30 to 101 d in the pregnant and nonpregnant sows. At 110 d, fasting FFA were high again in the pregnant sows only, very likely in relation to the preparation for lactation. This experiment showed that insulin sensitivity decreases after 85 d of pregnancy in multiparous sows.     

Chitosan Stimulates Defense Reactions in Grapevine Leaves and Inhibits Development of Botrytis Cinerea

Chitosan (β-1,4-linked glucosamine oligomer) derived from crab shells conferred a high protection of grapevine leaves against grey mould caused by Botrytis cinerea. Under controlled conditions, it was shown to be an efficient elicitor of some defense reactions in grapevine leaves and to inhibit directly the in vitro development of B. cinerea. Treatment of grapevine leaves by chitosan led to marked induction of lipoxygenase (LOX), phenylalanine ammonia-lyase (PAL) and chitinase activities, three markers of plant defense responses. Dose-response curves show that maximum defense reactions (PAL and chitinase activities) and strong reduction of B. cinerea infection were achieved with 75–150 mg l⁻¹ chitosan. However, greater concentrations of chitosan did not protect grapevine leaves with the same efficiency, but inhibited mycelial growth in vitro. Present results underlined the potency of chitosan in inducing some defense responses in grapevine leaves which in turn might improve resistance to grey mould.     

Resistance in water yam (Dioscorea alata) cultivars in the French West Indies to anthracnose disease based on tissue culture-derived whole-plant assay

Reactions of 60 water yam ( Dioscorea alata ) cultivars to three isolates of the yam anthracnose fungal pathogen ( Colletotrichum gloeosporioides ) were evaluated using tissue culture-derived whole-plant assay. Three disease parameters: single score on a scale of 0–6 at the seventh day after inoculation (SD7); area under the disease progress curve (AUDPC); and disease progress rate ( R _d) were compared, and cultivars were classified into disease-response groups using a rank-sum method based on AUDPC scores for the two most virulent isolates. A wide range of variation in resistance of the D. alata cultivars, and significant effects of pathogen isolate and isolate–cultivar interactions, were observed for all disease parameters. The three disease parameters were positively correlated; however, four cultivars showed great dispersions from the regression lines for comparisons of SD7 with the multiple assessments based AUDPC and R _d. The 60 cultivars were separated into resistant ( n  = 12), moderately resistant ( n  = 19), moderately susceptible ( n  = 18) and susceptible ( n  = 11) groups. The potential of the tissue culture-derived whole-plant assay to resistance breeding programmes and further understanding of the yam anthracnose pathosystem is discussed.