Differential habitat use between demographic states of black bears in managed timber forests

The long-term effects of intensive forest harvest on sensitive demographic stages of the American black bear (Ursus americanus) have been often overlooked. Much of Maine, USA, is covered in forests that are hospitable to bears and commercial timber harvest. To investigate the potential effects of differing intensities of disturbance on black bears, and on females with cubs particularly, we designed a large-scale natural experiment with 197 motion-sensitive camera sites dispersed over representative forest stands in northern and central Maine. Using multi-state occupancy models, we distinguished the overall trends in space use by females with young versus adult bears without young. Forest disturbance at large spatial scales was positively associated with the probability of use for both demographic groups and the availability of hardwood trees was an additional important factor for habitat use by females with young. Our study illustrates the use of motion-sensitive cameras to monitor and understand habitat use by distinct life-history stages of animals living in human-modified landscapes, and results indicate that managers can maintain black bear habitat in areas of active forest harvest by ensuring the availability of hardwood species.     

Can peroxygenase and microperoxidase substitute cytochrome P450 in biosensors

Aromatic peroxygenase (APO) from the basidiomycetous mushroom Agrocybe aegerita (AaeAPO) and microperoxidases (MPs) obtained from cytochrome c exhibit a broad substrate spectrum including hydroxylation of selected aromatic substrates, demethylation and epoxidation by means of hydrogen peroxide. It overlaps with that of cytochrome P450 (P450), making MPs and APOs to alternate recognition elements in biosensors for the detection of typical P450 substrates. Here, we discuss recently developed approaches using microperoxidases and peroxygenases in view of their potential to supplement P450 enzymes as recognition elements in biosensors for aromatic compounds. Starting as early as the 1970s, the direct electron transfer between electrodes and the heme group of heme peptides called microperoxidases has been used as a model of oxidoreductases. These MP-modified electrodes are used as hydrogen peroxide detectors based on the catalytic current generated by electrically contacted microperoxidase molecules. A similar catalytic reaction has been obtained for the electrode-immobilised heme protein AaeAPO. However, up to now, no MP-based sensors for substrates have been described. In this review, we present biosensors which indicate 4-nitrophenol, aniline, naphthalene and p-aminophenol based on the peroxide-dependent substrate conversion by electrode-immobilised MP and AaeAPO. In these enzyme electrodes, the signal is generated by the conversion of all substrates, thus representing in complex media an overall parameter. The performance of these sensors and their further development are discussed in comparison with P450-based electrodes.