Isolation and characterization of chitinolytic bacterium, Escherichia fergusonii AMC01 from insectivorous bat, Taphozous melanopogon.

Chitinases are capable of hydrolyzing insoluble chitin into its oligo and monomeric parts and have received increased consideration because of their wide scope of biotechnological applications. The commercial application of microbial chitinase is appealing due to the relative ease of enormous production and to meet the current world demands. This study aimed at isolation and characterization of chitin degrading bacteria from the gut of Indian tropical insectivorous black-bearded tomb bat, Taphozous melanopogon. The isolated bacterial strains were characterized through biochemical analysis and nucleic acid-based approaches by 16S ribosomal RNA amplification and sequencing. The BLAST (Basic Local Alignment Search Tool) and phylogenetic analysis showed that the bacterial strain exhibited a close resemblance with Escherichia fergusonii. The chitinolytic activity of the E. fergusonii AMC01 was identified using supplemented colloidal chitin with agar medium. Compiling all, these findings would facilitate in constructing a database and presumably promote the use of E. fergusonii AMC01 as an efficient strain for the chitinase production.

Structure of distress call: implication for specificity and activation of dopaminergic system.

We conducted a set of playback experiments aimed at understanding whether distress-call structure in the greater short-nosed fruit bat Cynopterus sphinx is specific in encoding information relating to stress that attracts conspecifics. We tested the specificity by playing their distress call and its modified version at a foraging site for free-ranging bats, as well as under captive conditions involving either a small group or individuals. In a separate playback experiment, bats showed a significantly greater response when the natural call as opposed to a modified call was played back to captive as well as free-ranging bats at the foraging site. Under captive conditions, bats showed less of a response to the playback of distress calls when in a group than when alone. We subsequently found that tyrosine hydroxylase (TH) and its transcription factor-nuclear receptor related factor 1 (Nurr-1); and the dopamine transporter (DAT) and its receptor (D1DR) were elevated significantly in the amygdala of bats both emitting and responding to a distress call, but not in the case of bats responding to the modified call. These results suggest that distress-call structure encodes information on the state of stress that is capable of being conveyed to conspecifics.

Silent katydid females are at higher risk of bat predation than acoustically signalling katydid males.

Males that produce conspicuous mate attraction signals are often at high risk of predation from eavesdropping predators. Females of such species typically search for signalling males and their higher motility may also place them at risk. The relative predation risk faced by males and females in the context of mate-finding using long-distance signals has rarely been investigated. In this study, we show, using a combination of diet analysis and behavioural experiments, that katydid females, who do not produce acoustic signals, are at higher risk of predation from a major bat predator, Megaderma spasma, than calling males. Female katydids were represented in much higher numbers than males in the culled remains beneath roosts of M. spasma. Playback experiments using katydid calls revealed that male calls were approached in only about one-third of the trials overall, whereas tethered, flying katydids were always approached and attacked. Our results question the idea that necessary costs of mate-finding, including risk of predation, are higher in signalling males than in searching females.

Distress call-induced gene expression in the brain of the Indian short-nosed fruit bat, Cynopterus sphinx.

Individuals in distress emit audible vocalizations to either warn or inform conspecifics. The Indian short-nosed fruit bat, Cynopterus sphinx, emits distress calls soon after becoming entangled in mist nets, which appear to attract conspecifics. Phase I of these distress calls is longer and louder, and includes a secondary peak, compared to phase II. Activity-dependent expression of egr-1 was examined in free-ranging C. sphinx following the emissions and responses to a distress call. We found that the level of expression of egr-1 was higher in bats that emitted a distress call, in adults that responded, and in pups than in silent bats. Up-regulated cDNA was amplified to identify the target gene (TOE1) of the protein Egr-1. The observed expression pattern Toe1 was similar to that of egr-1. These findings suggest that the neuronal activity related to recognition of a distress call and an auditory feedback mechanism induces the expression of Egr-1. Co-expression of egr-1 with Toe1 may play a role in initial triggering of the genetic mechanism that could be involved in the consolidation or stabilization of distress call memories.