THE WHOOPING CRANE CROSS-FOSTERING EXPERIMENT: THE ROLE OF ANIMAL DAMAGE CONTROL

Predator losses of endangered species in reintroduction programs are unacceptable because of the scarcity of the species and the major commitment of staff time and funds. When the whooping crane (Grus americana) cross-fostering experiment (experiment) at Grays Lake National Wildlife Refuge (Grays Lake), Idaho was proposed in 1972, animal damage control (ADC) was considered unnecessary. Sandhill crane (G. canadensis tabida) nest success was high and coyotes (Canis latrans) and red foxes (Vulpes Vulpes) were uncommon. Canids increased by the mid-1970\u27s destroying whooping crane eggs and chicks. An ADC program initiated in 1976 has evolved into a major part of the experiment. The ADC program is costly and complex, requiring several permits and coordination among 5 state and federal agencies and 20+ private landowners. Current ADC effort uses several control methods and annually entails 40± hrs of helicopter time, 900± hrs of staff time and over 9600 km of vehicle use. Between 1975-84, 14 eggs and 23 to 58 flightless young whoopers were lost to predators, primarily coyotes. From 1976-84, 633 predators were removed from the control area; 72% were canids. The ADC program appears to have reduced predation on whooping crane eggs and chicks. Our experience at Grays Lake indicates that endangered species introduction programs should include ADC evaluations in preliminary planning processes

Crystal structure of the ffh and EF-G binding sites in the conserved domain IV of Escherichia coli 4.5S RNA.

BackgroundBacterial signal recognition particle (SRP), consisting of 4.5S RNA and Ffh protein, plays an essential role in targeting signal-peptide-containing proteins to the secretory apparatus in the cell membrane. The 4.5S RNA increases the affinity of Ffh for signal peptides and is essential for the interaction between SRP and its receptor, protein FtsY. The 4.5S RNA also interacts with elongation factor G (EF-G) in the ribosome and this interaction is required for efficient translation.ResultsWe have determined by multiple anomalous dispersion (MAD) with Lu(3+) the 2.7 A crystal structure of a 4.5S RNA fragment containing binding sites for both Ffh and EF-G. This fragment consists of three helices connected by a symmetric and an asymmetric internal loop. In contrast to NMR-derived structures reported previously, the symmetric loop is entirely constituted by non-canonical base pairs. These pairs continuously stack and project unusual sets of hydrogen-bond donors and acceptors into the shallow minor groove. The structure can therefore be regarded as two double helical rods hinged by the asymmetric loop that protrudes from one strand.ConclusionsBased on our crystal structure and results of chemical protection experiments reported previously, we predicted that Ffh binds to the minor groove of the symmetric loop. An identical decanucleotide sequence is found in the EF-G binding sites of both 4.5S RNA and 23S rRNA. The decanucleotide structure in the 4.5S RNA and the ribosomal protein L11-RNA complex crystals suggests how 4.5S RNA and 23S rRNA might interact with EF-G and function in translating ribosomes

Crystal structure of the ffh and EF-G binding sites in the conserved domain IV of Escherichia coli 4.5S RNA.

BackgroundBacterial signal recognition particle (SRP), consisting of 4.5S RNA and Ffh protein, plays an essential role in targeting signal-peptide-containing proteins to the secretory apparatus in the cell membrane. The 4.5S RNA increases the affinity of Ffh for signal peptides and is essential for the interaction between SRP and its receptor, protein FtsY. The 4.5S RNA also interacts with elongation factor G (EF-G) in the ribosome and this interaction is required for efficient translation.ResultsWe have determined by multiple anomalous dispersion (MAD) with Lu(3+) the 2.7 A crystal structure of a 4.5S RNA fragment containing binding sites for both Ffh and EF-G. This fragment consists of three helices connected by a symmetric and an asymmetric internal loop. In contrast to NMR-derived structures reported previously, the symmetric loop is entirely constituted by non-canonical base pairs. These pairs continuously stack and project unusual sets of hydrogen-bond donors and acceptors into the shallow minor groove. The structure can therefore be regarded as two double helical rods hinged by the asymmetric loop that protrudes from one strand.ConclusionsBased on our crystal structure and results of chemical protection experiments reported previously, we predicted that Ffh binds to the minor groove of the symmetric loop. An identical decanucleotide sequence is found in the EF-G binding sites of both 4.5S RNA and 23S rRNA. The decanucleotide structure in the 4.5S RNA and the ribosomal protein L11-RNA complex crystals suggests how 4.5S RNA and 23S rRNA might interact with EF-G and function in translating ribosomes