5,703 research outputs found
The historical range of the White-winged Wood-Duck in Indonesia
Details are provided of historical records of Cairina scutulata in Sumatra and Java. There are confirmed records from seven Sumatran provinces and West and Central Java. These records increase the likelihood that populations survive today in Riau, Bengkulu and elsewhere in Sumatra
A theory-based approach to understanding condom errors and problems reported by men attending an STI clinic
The official published version can be accessed from the link below - Copyright @ 2008 Springer VerlagWe employed the information–motivation–behavioral skills (IMB) model to guide an investigation of correlates for correct condom use among 278 adult (18–35 years old) male clients attending a sexually transmitted infection (STI) clinic. An anonymous questionnaire aided by a CD-recording of the questions was administered. Linear Structural Relations Program was used to conduct path analyses of the hypothesized IMB model. Parameter estimates showed that while information did not directly affect behavioral skills, it did have a direct (negative) effect on condom use errors. Motivation had a significant direct (positive) effect on behavioral skills and a significant indirect (positive) effect on condom use errors through behavioral skills. Behavioral skills had a direct (negative) effect on condom use errors. Among men attending a public STI clinic, these findings suggest brief, clinic-based, safer sex programs for men who have sex with women should incorporate activities to convey correct condom use information, instill motivation to use condoms correctly, and directly enhance men’s behavioral skills for correct use of condoms
Research Mentoring and Scientist Identity: Insights from Undergraduates and their Mentors
Background Mentored research apprenticeships are a common feature of academic outreach programs that aim to promote diversity in science fields. The current study tests for links between three forms of mentoring (instrumental, socioemotional, and negative) and the degree to which undergraduates psychologically identify with science. Participants were 66 undergraduate-mentor dyads who worked together in a research apprenticeship. The undergraduate sample was predominantly composed of women, first-generation college students, and members of ethnic groups that are historically underrepresented in science. Results Findings illustrated that undergraduates who reported receiving more instrumental and socioemotional mentoring were higher in scientist identity. Further, mentors who reported engaging in higher levels of negative mentoring had undergraduates with lower scientist identity. Qualitative data from undergraduates’ mentors provided deeper insight into their motivation to become mentors and how they reason about conflict in their mentoring relationships. Conclusions Discussion highlights theoretical implications and details several methodological recommendations
Size-scaling limits of impulsive elastic energy release from a resilin-like elastomer
Elastically-driven motion has been used as a strategy to achieve high speeds
in small organisms and engineered micro-robotic devices. We examine the
size-scaling relations determining the limit of elastic energy release from
elastomer bands with mechanical properties similar to the biological protein
resilin. The maximum center-of-mass velocity of the elastomer bands was found
to be size-scale independent, while smaller bands demonstrated larger
accelerations and shorter durations of elastic energy release. Scaling
relationships determined from these measurements are consistent with the
performance of small organisms which utilize elastic elements to power motion.
Engineered devices found in the literature do not follow the same size-scaling
relationships, which suggests an opportunity for improved design of engineered
devices.Comment: 9 pages, 4 figure
PMI: A Delta Psi(m) Independent Pharmacological Regulator of Mitophagy
Mitophagy is central to mitochondrial and cellular homeostasis and operates via the PINK1/Parkin pathway targeting mitochondria devoid of membrane potential (ΔΨm) to autophagosomes. Although mitophagy is recognized as a fundamental cellular process, selective pharmacologic modulators of mitophagy are almost nonexistent. We developed a compound that increases the expression and signaling of the autophagic adaptor molecule P62/SQSTM1 and forces mitochondria into autophagy. The compound, P62-mediated mitophagy inducer (PMI), activates mitophagy without recruiting Parkin or collapsing ΔΨm and retains activity in cells devoid of a fully functional PINK1/Parkin pathway. PMI drives mitochondria to a process of quality control without compromising the bio-energetic competence of the whole network while exposing just those organelles to be recycled. Thus, PMI circumvents the toxicity and some of the nonspecific effects associated with the abrupt dissipation of ΔΨm by ionophores routinely used to induce mitophagy and represents a prototype pharmacological tool to investigate the molecular mechanisms of mitophagy
A three-dimensional current meter for estuarine applications
A curr ent meter that is capable of measuring the high-frequency fluctuations of the three-dimensional velocity vector has been developed. The meter works on a doppler-shift principle. At high velocities, the meter has been shown to have an accuracy of better than 3%
Chandra and RXTE Spectra of the Burster GS 1826-238
Using simultaneous observations from Chandra and RXTE, we investigated the
LMXB GS 1826-238 with the goal of studying its spectral and timing properties.
The uninterrupted Chandra observation captured 6 bursts (RXTE saw 3 of the 6),
yielding a recurrence time of 3.54 +/- 0.03 hr. Using the proportional counter
array on board RXTE, we made a probable detection of 611 Hz burst oscillations
in the decaying phases of the bursts with an average rms signal amplitude of
4.8%. The integrated persistent emission spectrum can be described as the dual
Comptonization of ~ 0.3 keV soft photons by a plasma with kT_e ~ 20 keV and an
optical depth of about 2.6 (interpreted as emission from the accretion disk
corona), plus the Comptonization of hotter ~ 0.8 keV seed photons by a ~ 6.8
keV plasma (interpreted as emission from or near the boundary layer). We
discovered evidence for a neutral Fe K\alpha emission line, and we found
interstellar Fe L_II and Fe L_III absorption features. The burst spectrum can
be fit by fixing the disk Comptonization parameters to the persistent emission
best-fit values, and adding a blackbody. The blackbody/seed photon temperature
at the peak of the burst is ~ 1.8 keV and returns to ~ 0.8 keV over 200 s. The
blackbody radius is consistent with R_bb = 10.3-11.7 km assuming a distance of
6 kpc; however, by accounting for the fraction of the surface that is obscured
by the disk as a function of binary inclination, we determined the source
distance must actually be near 5 kpc in order for the stellar radius to lie
within the commonly assumed range of 10-12 km.Comment: Accepted for publication in ApJ; 13 pages, 6 figure
A Natural Plasmid Uniquely Encodes Two Biosynthetic Pathways Creating a Potent Anti-MRSA Antibiotic
Background
Understanding how complex antibiotics are synthesised by their producer bacteria is essential for creation of new families of bioactive compounds. Thiomarinols, produced by marine bacteria belonging to the genus Pseudoalteromonas, are hybrids of two independently active species: the pseudomonic acid mixture, mupirocin, which is used clinically against MRSA, and the pyrrothine core of holomycin.
Methodology/Principal Findings
High throughput DNA sequencing of the complete genome of the producer bacterium revealed a novel 97 kb plasmid, pTML1, consisting almost entirely of two distinct gene clusters. Targeted gene knockouts confirmed the role of these clusters in biosynthesis of the two separate components, pseudomonic acid and the pyrrothine, and identified a putative amide synthetase that joins them together. Feeding mupirocin to a mutant unable to make the endogenous pseudomonic acid created a novel hybrid with the pyrrothine via “mutasynthesis” that allows inhibition of mupirocin-resistant isoleucyl-tRNA synthetase, the mupirocin target. A mutant defective in pyrrothine biosynthesis was also able to incorporate alternative amine substrates.
Conclusions/Significance
Plasmid pTML1 provides a paradigm for combining independent antibiotic biosynthetic pathways or using mutasynthesis to develop a new family of hybrid derivatives that may extend the effective use of mupirocin against MRSA
Recommended from our members
The ErbB2ΔEx16 splice variant is a major oncogenic driver in breast cancer that promotes a pro-metastatic tumor microenvironment.
Amplification and overexpression of erbB2/neu proto-oncogene is observed in 20-30% human breast cancer and is inversely correlated with the survival of the patient. Despite this, somatic activating mutations within erbB2 in human breast cancers are rare. However, we have previously reported that a splice isoform of erbB2, containing an in-frame deletion of exon 16 (herein referred to as ErbB2ΔEx16), results in oncogenic activation of erbB2 because of constitutive dimerization of the ErbB2 receptor. Here, we demonstrate that the ErbB2ΔEx16 is a major oncogenic driver in breast cancer that constitutively signals from the cell surface. We further show that inducible expression of the ErbB2ΔEx16 variant in mammary gland of transgenic mice results in the rapid development of metastatic multifocal mammary tumors. Genetic and biochemical characterization of the ErbB2ΔEx16-derived mammary tumors exhibit several unique features that distinguish this model from the conventional ErbB2 ones expressing the erbB2 proto-oncogene in mammary epithelium. Unlike the wild-type ErbB2-derived tumors that express luminal keratins, ErbB2ΔEx16-derived tumors exhibit high degree of intratumoral heterogeneity co-expressing both basal and luminal keratins. Consistent with these distinct pathological features, the ErbB2ΔEx16 tumors exhibit distinct signaling and gene expression profiles that correlate with activation of number of key transcription factors implicated in breast cancer metastasis and cancer stem cell renewal
- …