15 research outputs found
The Ecological Conditions That Favor Tool Use and Innovation in Wild Bottlenose Dolphins (Tursiops sp.)
Dolphins are well known for their exquisite echolocation abilities, which enable them to detect and discriminate prey species and even locate buried prey. While these skills are widely used during foraging, some dolphins use tools to locate and extract prey. In the only known case of tool use in free-ranging cetaceans, a subset of bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia habitually employs marine basket sponge tools to locate and ferret prey from the seafloor. While it is clear that sponges protect dolphins' rostra while searching for prey, it is still not known why dolphins probe the substrate at all instead of merely echolocating for buried prey as documented at other sites. By âsponge foragingâ ourselves, we show that these dolphins target prey that both lack swimbladders and burrow in a rubble-littered substrate. Delphinid echolocation and vision are critical for hunting but less effective on such prey. Consequently, if dolphins are to access this burrowing, swimbladderless prey, they must probe the seafloor and in turn benefit from using protective sponges. We suggest that these tools have allowed sponge foraging dolphins to exploit an empty niche inaccessible to their non-tool-using counterparts. Our study identifies the underlying ecological basis of dolphin tool use and strengthens our understanding of the conditions that favor tool use and innovation in the wild
An Active Site Aromatic Triad in Escherichia coli DNA Pol IV Coordinates Cell Survival and Mutagenesis in Different DNA Damaging Agents
DinB (DNA Pol IV) is a translesion (TLS) DNA polymerase, which inserts a
nucleotide opposite an otherwise replication-stalling
N2-dG lesion in vitro, and
confers resistance to nitrofurazone (NFZ), a compound that forms these lesions
in vivo. DinB is also known to be part of the cellular
response to alkylation DNA damage. Yet it is not known if DinB active site
residues, in addition to aminoacids involved in DNA synthesis, are critical in
alkylation lesion bypass. It is also unclear which active site aminoacids, if
any, might modulate DinB's bypass fidelity of distinct lesions. Here we
report that along with the classical catalytic residues, an active site
âaromatic triadâ, namely residues F12, F13, and Y79, is critical for
cell survival in the presence of the alkylating agent methyl methanesulfonate
(MMS). Strains expressing dinB alleles with single point
mutations in the aromatic triad survive poorly in MMS. Remarkably, these strains
show fewer MMS- than NFZ-induced mutants, suggesting that the aromatic triad, in
addition to its role in TLS, modulates DinB's accuracy in bypassing
distinct lesions. The high bypass fidelity of prevalent alkylation lesions is
evident even when the DinB active site performs error-prone NFZ-induced lesion
bypass. The analyses carried out with the active site aromatic triad suggest
that the DinB active site residues are poised to proficiently bypass distinctive
DNA lesions, yet they are also malleable so that the accuracy of the bypass is
lesion-dependent
Serum levels of the proinflammatory cytokine interleukin-6 vary based on diagnoses in individuals with lumbar intervertebral disc diseases
Bus service quality prediction and attribute ranking: a neural network approach
Evaluation of service quality (SQ) based on user preferences has become a primary concern for the transportation authorities. The most significant attributes of public transportation systems are revealed through service quality analysis. This information serves as valuable input in constantly updating the quality of public transportation services. An appropriate tool is therefore mandatory in this regard. This paper represents a comparative study on the bus SQ prediction capabilities of three effective Artificial Neural Network (ANN) approaches, namely: Generalized Regression Neural Network (GRNN), Probabilistic Neural Network (PNN) and Pattern Recognition Neural Network (PRNN). To calibrate the parameters of the developed ANN models, data on usersâ perception toward bus services of Dhaka city, Bangladesh, have been used. Taking the public opinion as baseline, GRNN and PNN have proven to be better prediction models since both have achieved higher accuracy compared to PRNN. Among 22 selected SQ attributes, the most significant attributes have been ranked according to their influence on the usersâ decision making process. According to the GRNN and PNN models, punctuality and reliability, service frequency, seat availability and commuting experience are found to be the most significant attributes, which support the user-stated preferences
Correlated biofilm imaging, transport and metabolism measurements via combined nuclear magnetic resonance and confocal microscopy
The evolution of the host microbiome as an ecosystem on a leash
The human body carries vast communities of microbes that provide many benefits. Our microbiome is complex and challenging to understand, but evolutionary theory provides a universal framework with which to analyse its biology and health impacts. Here we argue that to understand a given microbiome feature, such as colonization resistance, host nutrition or immune development, we must consider how hosts and symbionts evolve. Symbionts commonly evolve to compete within the host ecosystem, while hosts evolve to keep the ecosystem on a leash. We suggest that the health benefits of the microbiome should be understood, and studied, as an interplay between microbial competition and host control