The Mercury-Tolerant Microbiota of the Zooplankton Daphnia Aids in Host Survival and Maintains Fecundity under Mercury Stress.

Many aquatic organisms can thrive in polluted environments by having the genetic capability to withstand suboptimal conditions. However, the contributions of microbiomes under these stressful environments are poorly understood. We investigated whether a mercury-tolerant microbiota can extend its phenotype to its host by ameliorating host survival and fecundity under mercury-stress. We isolated microbiota members from various clones of Daphnia magna, screened for the mercury-biotransforming merA gene, and determined their mercury tolerance levels. We then introduced the mercury-tolerant microbiota, Pseudomonas-10, to axenic D. magna and quantified its merA gene expression, mercury reduction capability, and measured its impact on host survival and fecundity. The expression of the merA gene was up-regulated in Pseudomonas-10, both in isolation and in host-association with mercury exposure. Pseudomonas-10 is also capable of significantly reducing mercury concentration in the medium. Notably, mercury-exposed daphnids containing only Pseudomonas-10 exhibited higher survival and fecundity than mercury-exposed daphnids supplemented with parental microbiome. Our study showed that zooplankton, such as Daphnia, naturally harbor microbiome members that are eco-responsive and tolerant to mercury exposure and can aid in host survival and maintain host fecundity in a mercury-contaminated environment. This study further demonstrates that under stressful environmental conditions, the fitness of the host can depend on the genotype and the phenotype of its microbiome

Assessing the Biking Suitability in National Highways: The Case of Palayan City, Nueva Ecija, Philippines

The conundrum of the Philippines’ public transportation has been a long- standing issue. With this, the Philippine government has been moving toward more sustainable public transportation systems such as cycling. Culturally and traditionally, cycling has never been mainstreamed or fostered in the country’s public transportation system. However, bicycles were considered an alternate means of transportation in the new normal. Thus, this study assessed if biking would be suitable on national highways, particularly in Palayan City, Nueva Ecija. Several factors can influence the use of cycling, such as physical and environmental factors, level of service, and width of inner and outer lanes of national highways. In this study, considering the physical and environmental criteria, the four selected barangays (Atate, Singalat, Caimito, and Santolan) are suitable for bike lane development as they cover 0.85 to 6.0% of the total land area and are densely located on flat to gently sloping areas. These barangays are also mostly covered with cultivated area. Furthermore, as for data collected from the vehicle count survey in 2021 versus 2022, the level of service (LOS) as calculated is LOS B against all the peak hour traffic, where reasonably free flow speed is maintained. However, compared to the 2021 vehicle count survey, there is an increase in passenger car units (pcu) in 2022 as COVID-19 ends. In consideration of the road width, the outermost lane has a width of 3.05 m, which corresponds to the DPWH-prescribed minimum measurement of 2.44 m. With these results, developing bike lanes on national highways is suitable

Adaptation and acclimatization to ocean acidification in marine ectotherms: an in situ transplant experiment with polychaetes at a shallow CO₂ vent system

Metabolic rate determines the physiological and life-history performances of ectotherms. Thus, the extent to which such rates are sensitive and plastic to environmental perturbation is central to an organism's ability to function in a changing environment. Little is known of long-term metabolic plasticity and potential for metabolic adaptation in marine ectotherms exposed to elevated pCO₂. Consequently, we carried out a series of in situ transplant experiments using a number of tolerant and sensitive polychaete species living around a natural CO₂ vent system. Here, we show that a marine metazoan (i.e. Platynereis dumerilii) was able to adapt to chronic and elevated levels of pCO₂. The vent population of P. dumerilii was physiologically and genetically different from nearby populations that experience low pCO₂, as well as smaller in body size. By contrast, different populations of Amphiglena mediterranea showed marked physiological plasticity indicating that adaptation or acclimatization are both viable strategies for the successful colonization of elevated pCO₂ environments. In addition, sensitive species showed either a reduced or increased metabolism when exposed acutely to elevated pCO₂. Our findings may help explain, from a metabolic perspective, the occurrence of past mass extinction, as well as shed light on alternative pathways of resilience in species facing ongoing ocean acidification

The very fast evolution of Sakurai's object

V4334 Sgr (a.k.a. Sakurai's object) is the central star of an old planetary nebula that underwent a very late thermal pulse a few years before its discovery in 1996. We have been monitoring the evolution of the optical emission line spectrum since 2001. The goal is to improve the evolutionary models by constraining them with the temporal evolution of the central star temperature. In addition the high resolution spectral observations obtained by X-shooter and ALMA show the temporal evolution of the different morphological components.Comment: 2 pages, 2 figures to appear in the Proceedings of the IAU Symp. 323: "Planetary nebulae: Multi-wavelength probes of stellar and galactic evolution". Eds. X.-W. Liu, L. Stanghellini and A. Karaka

Aligned Carbon Nanotube Reinforcement of Aerospace Carbon Fiber Composites: Substructural Strength Evaluation for Aerostructure Applications

https://www.aiaa.org/ProceedingsDetail.aspx?id=5776Vertically aligned carbon nanotubes (VACNTs) are placed between all plies in an aerospace carbon fiber reinforced plastic laminate (unidirectional plies, [(0/90/±45)2]s) to reinforce the interlaminar region in the z-direction. Significant improvement in Mode I and II interlaminar toughness have been observed previously. In this work, several substructural in-plane strength tests relevant to aerostructures were undertaken: bolt/tension-bearing, open hole compression, and L-shape laminate bending. Improvements are observed for the nanostitched samples: critical bearing strength by 30%, open-hole compression ultimate strength by 10%, and L-shape laminate energy (via increased deflection) of 40%. The mechanism of reinforcement is not compliant interlayer creation, but rather is a fiberstitching mechanism, as no increase in interlayer thickness occurs with the nanostitches. Unlike traditional (large-fiber/tow/pin) stitching or z-pinning techniques that damage inplane fibers and reduce laminate in-plane strengths, the nano-scale CNT-based ‘stitches’ improve in-plane strength, demonstrating the potential of such an architecture for aerospace structural applications. The quality of VACNT transfer to the prepreg laminates has not been optimized and therefore the noted enhancement to strength may be considered conservative. Ongoing work has been undertaken to both improve VACNT transfer and expand the data set.Massachusetts Institute of Technology (Nano-Engineered Composite aerospace STructures (NECST) Consortium

Selective changes in inhibition as determinants for limited hyperexcitability in the insular cortex of epileptic rats

The insular cortex (IC) is involved in the generalization of epileptic discharges in temporal lobe epilepsy (TLE), while seizures originating in IC can mimic the epileptic phenotype seen in some TLE patients. Few studies have however addressed the changes occurring in the IC in TLE animal models. Here, we analyzed the immunohistochemical and electrophysiological properties of IC networks in non-epileptic control and pilocarpine-treated epileptic rats. Neurons identified with a neuron-specific nuclear protein antibody showed similar counts in the two types of tissue but parvalbumin- and neuropeptide Y-positive interneurons were significantly decreased (parvalbumin, approx. -35%; neuropeptide Y, approx. -38%; P<0.01) in the epileptic IC. Non-adapting neurons were more frequently seen in the epileptic IC during intracellular injection of depolarizing current pulses. In addition, single-shock electrical stimuli elicited network-driven epileptiform responses in 87% of epileptic and in 22% of non-epileptic control neurons (P<0.01) but spontaneous postsynaptic potentials had similar amplitude, duration and intervals of occurrence in the two groups. Finally, pharmacologically isolated, GABAA receptor-mediated inhibitory postsynaptic potentials had more negative reversal potential (P<0.01) and higher peak conductance (P<0.05) in epileptic tissue. These data reveal moderate increased network excitability in the IC of pilocarpine-treated epileptic rats. We propose that such limited degree of hyperexcitability originates from loss of parvalbumin- and neuropeptide Y-positive interneurons that is compensated by an increased drive for GABAA receptor-mediated inhibition

Structure of the Yersinia pestis tip protein LcrV refined to 1.65 A resolution

This is the publisher's version, also available electronically from http://scripts.iucr.org/cgi-bin/paper?S1744309113008579.The human pathogen Yersinia pestis requires the assembly of the type III secretion system (T3SS) for virulence. The structural component of the T3SS contains an external needle and a tip complex, which is formed by LcrV in Y. pestis. The structure of an LcrV triple mutant (K40A/D41A/K42A) in a C273S background has previously been reported to 2.2 Å resolution. Here, the crystal structure of LcrV without the triple mutation in a C273S background is reported at a higher resolution of 1.65 Å. Overall the two structures are similar, but there are also notable differences, particularly near the site of the triple mutation. The refined structure revealed a slight shift in the backbone positions of residues Gly28-Asn43 and displayed electron density in the loop region consisting of residues Ile46-Val63, which was disordered in the original structure. In addition, the helical turn region spanning residues Tyr77-Gln95 adopts a different orientation