Big brown bats are challenged by acoustically-guided flights through a circular tunnel of hoops.

Mines and caves provide essential roosting places for bats, but often they are obstructed to prevent entry by humans. To allow bats to access their roosts, metal corrugated culvert pipes are sometimes installed. Wildlife surveys indicate, however, that bats may abandon caves having corrugated culvert entrances. Culverts may be confusing to bats due to the complex patterns of echoes returned by the regular, ring-like corrugations. We tested the hypothesis that a circular tunnel composed of successive hoops is difficult for big brown bats (Eptesicus fuscus) to navigate. Experiments challenged bats with flights through a tunnel of round plastic hoops or a corridor flanked left and right by rows of plastic hanging chains. The bats swerved sideways and left the pathway on more flights in the hoop tunnel compared to only rarely in the chain corridor. Even during successful flights through the hoops, bats changed the temporal patterning of their echolocation pulses to compress them into more sonar sound groups. From prior research, this active reaction is an indicator of a perceptually more difficult task. To allow bats access to mines through culverts without affecting their echolocation behavior, smoothing or masking the regular corrugations inside with concrete may be effective.

C9ORF72 repeat expansions in cases with previously identified pathogenic mutations.

OBJECTIVE: To identify potential genetic modifiers contributing to the phenotypic variability that is detected in patients with repeat expansions in chromosome 9 open reading frame 72 (C9ORF72), we investigated the frequency of these expansions in a cohort of 334 subjects previously found to carry mutations in genes known to be associated with a spectrum of neurodegenerative diseases. METHODS: A 2-step protocol, with a fluorescent PCR and a repeat-primed PCR, was used to determine the presence of hexanucleotide expansions in C9ORF72. For one double mutant, we performed Southern blots to assess expansion sizes, and immunohistochemistry to characterize neuropathology. RESULTS: We detected C9ORF72 repeat expansions in 4 of 334 subjects (1.2% [or 1.8% of 217 families]). All these subjects had behavioral phenotypes and also harbored well-known pathogenic mutations in either progranulin (GRN: p.C466LfsX46, p.R493X, p.C31LfsX35) or microtubule-associated protein tau (MAPT: p.P301L). Southern blotting of one double mutant with a p.C466LfsX46 GRN mutation demonstrated a long repeat expansion in brain (>3,000 repeats), and immunohistochemistry showed mixed neuropathology with characteristics of both C9ORF72 expansions and GRN mutations. CONCLUSIONS: Our findings indicate that co-occurrence of 2 evidently pathogenic mutations could contribute to the pleiotropy that is detected in patients with C9ORF72 repeat expansions. These findings suggest that patients with known mutations should not be excluded from further studies, and that genetic counselors should be aware of this phenomenon when advising patients and their family members.