Migratory movements and wintering areas of Leach's Storm‐Petrels tracked using geolocators

Accumulating evidence suggests that Atlantic populations of Leach's Storm‐Petrels (Oceanodroma leucorhoa) are experiencing significant declines. To better understand possible causes of these declines, we used geolocators to document movements of these small (～50‐g) pelagic seabirds during migration and the non‐breeding period. During 2012 and 2013, movement tracks were obtained from two birds that traveled in a clock‐wise direction from two breeding colonies in eastern Canada (Bon Portage Island, Nova Scotia, and Gull Island, Newfoundland) to winter in tropical waters. The bird from Bon Portage Island started its migration towards Cape Verde in October, arrived at its wintering area off the coast of eastern Brazil in January, and started migration back to Nova Scotia in April. The bird from Gull Island staged off Newfoundland in November and then again off Cape Verde in January before its geolocator stopped working. Movements of Leach's Storm‐Petrels in our study and those of several other procellariiforms during the non‐breeding period are likely facilitated by the prevailing easterly trade winds and the Antilles and Gulf Stream currents. Although staging and wintering areas used by Leach's Storm‐Petrels in our study were characterized by low productivity, the West Africa and northeastern Brazilian waters are actively used by fisheries and discards can attract Leach's Storm‐Petrels. Our results provide an initial step towards understanding movements of Leach's Storm‐Petrels during the non‐breeding period, but further tracking is required to confirm generality of their migratory routes, staging areas, and wintering ranges.     

Perlecan domain 1 recombinant proteoglycan augments BMP-2 activity and osteogenesis

ABSTRACT: BACKGROUND: Many growth factors, such as bone morphogenetic protein (BMP)-2, have been shown to interact with polymers of sulfated disacharrides known as heparan sulfate (HS) glycosaminoglycans (GAGs), which are found on matrix and cell-surface proteoglycans throughout the body. HS GAGs, and some more highly sulfated forms of chondroitin sulfate (CS), regulate cell function by serving as co-factors, or co-receptors, in GF interactions with their receptors, and HS or CS GAGs have been shown to be necessary for inducing signaling and GF activity, even in the osteogenic lineage. Unlike recombinant proteins, however, HS and CS GAGs are quite heterogenous due, in large part, to post-translational addition, then removal, of sulfate groups to various positions along the GAG polymer. We have, therefore, investigated whether it would be feasible to deliver a DNA pro-drug to generate a soluble HS/CS proteoglycan in situ that would augment the activity of growth-factors, including BMP-2, in vivo. RESULTS: Utilizing a purified recombinant human perlecan domain 1 (rhPln.D1) expressed from HEK 293 cells with HS and CS GAGs, tight binding and dose-enhancement of rhBMP-2 activity was demonstrated in vitro. In vitro, the expressed rhPln.D1 was characterized by modification with sulfated HS and CS GAGs. Dose-enhancement of rhBMP-2 by a pln.D1 expression plasmid delivered together as a lyophilized single-phase on a particulate tricalcium phosphate scaffold for 6 or more weeks generated up to 9 fold more bone volume de novo on the maxillary ridge in a rat model than in control sites without the pln.D1 plasmid. Using a significantly lower BMP-2 dose, this combination provided more than 5 times as much maxillary ridge augmentation and greater density than rhBMP-2 delivered on a collagen sponge (InFuse[trade mark sign]). CONCLUSIONS: A recombinant HS/CS PG interacted strongly and functionally with BMP-2 in binding and cell-based assays, and, in vivo, the pln.247 expression plasmid significantly improved the dose-effectiveness of BMP-2 osteogenic activity for in vivo de novo bone generation when delivered together on a scaffold as a single-phase. The use of HS/CS PGs may be useful to augment GF therapeutics, and a plasmid-based approach has been shown here to be highly effective.     

Arrested succession in logging gaps: is tree seedling growth and survival limiting?

Thirty years after selective timber harvest in the Kibale National Park, Uganda, many abandoned logging gaps are dominated by Acanthus pubescens, and show little forest recovery. To examine if this arrested successional state was caused by limited tree seedling growth and survival, we planted seedlings of four forest tree species (Albizia grandibracteata, Mimusops bagshawei, Prunus africana and Uvariopsis congensis) in A. pubescens‐dominated logging gaps and in control areas of adjacent forest. To assess if clearing A. pubescens facilitates forest regeneration, we planted seedlings of two species (A. grandibracteata and U. congensis) in small clearings cut within the logging gaps. We examined mortality, growth, herbivory and site characteristics among the treatments. Finally, we described the physical attributes of the A. pubescens‐dominated gaps. Seedlings of all the four species survived and grew equally well in A. pubescens and forest treatments, and most site characteristics were also similar. Seedlings planted in clearings grew more than in either forest or A. pubescens sites. Very few established trees were found in A. pubescens sites, and most of these were near the forest edges. We also discussed the role of elephants (Loxodonta africana) and collapsing A. pubescens canopies in the maintenance of an arrested successional state in these logging gaps.