Noncollagenous nature of the proteins of shark enamel

The proteins, soluble and insoluble at neutral pH, of relatively mature enamel of two different species of sharks were distinctly different from both collagen and embryonic enamel proteins and similar to the proteins isolated from mature human and bovine enamel.     

Maximum foraging ranges in solitary bees: only few individuals have the capability to cover long foraging distances

To preserve populations of endangered bee species, sound knowledge of their maximum foraging distance between nest and host plants is crucial. Previous investigations predicted maximum foraging distances of 100-200 m for small bee species and up to 1100 m for very large species based on mainly indirect methods. The present study applied a new and direct approach to experimentally investigate maximum foraging distances in solitary bees. One endangered and two common species of different body sizes, all of which restrict pollen foraging to a single plant genus, were established in a landscape lacking their specific host plants. Females were forced to collect pollen on potted host plants that were successively placed in increasing distance from fixed nesting stands. The maximum foraging distance recorded for the small Hylaeus punctulatissimus was 1100 m, for the medium sized Chelostoma rapunculi 1275 m and for the large Hoplitis adunca 1400 m, indicating that maximum foraging distances at species level have been underestimated. However, the capability to use resources on such a large spatial scale applied only to a small percentage of individuals as 50% of the females of H. punctulatissimus and H. adunca did not forage at distances longer than 100-225 m and 300 m, respectively. This finding suggests that a close neighbourhood of nesting and foraging habitat within few hundred meters is crucial to maintain populations of these species, and that threshold distances at which half of the population discontinues foraging are a more meaningful parameter for conservation practice than the species specific maximum foraging distances.     

Knot attributes and occlusion of naturally pruned branches of Fagus sylvatica

The aim of this study was to develop models on occluded branch characteristics for Fagus sylvatica (beech) based on 41 sample trees. A total of 717 beech branches were sampled; this information was then used to predict (1) the time for a complete occlusion, (2) the total radius of the occluded branch inside the trunk, (3) the branch insertion angle at the year of its death and during branch development, and (4) the dead branch portion of the occluded branch (loose knot). Generalized hierarchical mixed models with nonlinear forms were used in this analysis. The models explained between 6.3 and 52.2% of the total variance (including random effects 23.8–77.1%). The diameter of the occluded branch and the stem radial increment played dominant roles as predictors. Larger branches showed a significantly longer occlusion time, a larger occluded branch radius, a steeper insertion angle, and a higher loose knot portion. Simulations showed a biologically reasonable overall behavior of the models. The residual variation was tolerable for integrating the models into a growth simulation system.     

Resonance of scantlings indicates the stiffness even of small specimens of Eucalyptus from plantations

The aim of this study was to establish the relationship between the stiffness of scantlings, approaching structural size materials, and small specimens of 6-year-old Eucalyptus urophylla?×?grandis wood using a resonance technique. The correlation between the elastic modulus (E) of the scantlings in longitudinal vibration and small specimens in flexural vibration was r?=?75 when comparing the scantling values with the averaged values of the specimens per scantling. However, when the E of each single specimen was compared with its respective scantling, the coefficient of correlation decreased to r?=?0.64 in the longitudinal tests and r?=?0.61 in the flexural tests. A roughly linear correlation (r?=?0.59) between specific modulus and loss tangent was obtained for the small specimens of Eucalyptus. In short, the resonance technique rapidly provided a large, accurate data set of mechanical wood properties as required for high-throughput phenotyping in recent genetic studies.     

Polyuria and Polydipsia and Disturbed Vasopressin Release in 2 Dogs With Secondary Polycythemia

In dogs, secondary polycythemia (SP) may be associated with polyuria and polydipsia (PU/PD). The pathogenesis of this PU/PD has not yet been explained. We hypothesized that hyperviscosity and increased blood volume in SP might affect vasopressin (VP) release, resulting in PU/PD. This hypothesis was tested in 2 dogs with SP caused by renal neo-plasia and PU/PD. Osmoregulation of VP release was studied by a modified water deprivation test and by investigating the VP response to hypertonic saline infusion.
Water deprivation test results were consistent with an inability to produce concentrated urine despite increasing plasma osmolality. During hypertonic saline infusion, the osmotic threshold of VP release was markedly increased in both dogs, resulting in a delayed VP response to increasing plasma osmolality. The sensitivity of VP release was low normal in both dogs. We conclude that blood hyperviscosity and increased blood volume led to impaired VP release and polyuria.     

Crown and branch attributes of mid-aged Betula alnoides plantations in response to planting density

Both crown and branch characteristics greatly affect tree growth and timber quality, and their development is closely related to planting density (PD). Here crown and branch attributes of Betula alnoides were investigated in a 14-year-old experimental plantation in southern China with five planting densities ranging from 500 to 3333 stems per hectare (sph). The results showed that high PD significantly reduced crown and branch sizes. The ratios of crown diameter to stem diameter at breast height at the stand level and for dominant and co-dominant trees were almost constant regardless of PD. PD also had no significant influence on the number and angle of branches, and only planting with the highest density significantly increased branch density and mortality. Insertion angle (IA) of dead branches was greater than that of live branches and these differences were significant at the two low planting densities (833 and 500?sph). Linear mixed models revealed that branch diameter (BD) was negatively correlated with its relative height in the crown and IA. The binary-logistic regression model indicated that branch status (live or dead) was codetermined by BD and PD. These findings can help farmers cultivate high-quality wood of B. alnoides and obtain a higher economic return.     

Characterization of infectious bursal disease viruses isolated in 2007 from Delmarva commercial broiler chickens

A study was performed in 2007 to isolate and characterize infectious bursal disease viruses (IBDVs) in commercial broilers grown in the Delmarva (DMV) Peninsula region of the United States. Bursae of Fabricius were collected weekly from 1 to 4 wk of age from broilers on 10 farms with a history of poor performance. Microscopic pathology was used to determine the infectious bursal disease (IBD) status of the broilers. Bursae from 1- and 2-wk-old broilers did not show IBD microscopic lesions. Moreover, broilers on 1 of the 10 farms were IBD lesion free at 3 and 4 wk of age. However, 3 of 9 and 9 of 9 farms yielded broilers with IBD-affected bursae from 3- and 4-wk-old commercial broilers, respectively. Ten IBDV isolates were recovered from 3 of 3 lesion-positive bursal pools at 3 wk of age and 7 of 9 lesion-positive bursal pools at 4 wk of age. Analysis of the viral protein (VP) 2 genes identified all isolates as serotype 1 Delaware (Del) variant viruses. Five field isolates, each representing different molecular clades of the Delaware variant viruses, were selected for further study. Experimental infection of specific-pathogen-free white leghorn chickens with isolates DMV/4813/07, DMV/4947/07, DMV/4955/07, DMV/5038/07, and DMV/5041/07 produced gross and microscopic pathology of the bursa consistent with Delaware variant infection. Monoclonal antibody testing showed DMV/4813/07, DMV/4947/07, DMV/ 4955/07, and DMV/5041/07 to be similar to previous recognized variant viruses. However, DMV/5038/07 was found to be unreactive with the monoclonal antibodies that typically recognize reference strains STC, Del E, GLS, RS593, and AL2. In a challenge of immunity study, 10-day-old progeny from breeders immunized with a commercially available inactivated IBDV vaccine containing the Del E and classic strains were protected to a lesser degree against isolate DMV/5038/07 compared to Del E challenge based on microscopic lesion scores (P < 0.01) of the bursa. This result suggests the virus is antigenically different from the Del E strain contained in the vaccine. Collectively, the monoclonal antibody and progeny challenge of immunity findings suggest DMV/5038/07 is antigenically different from the Del E strain contained in the vaccine.