Diel Surface Temperature Range Scales with Lake Size

Ecological and biogeochemical processes in lakes are strongly dependent upon water temperature. Long-term surface warming of many lakes is unequivocal, but little is known about the comparative magnitude of temperature variation at diel timescales, due to a lack of appropriately resolved data. Here we quantify the pattern and magnitude of diel temperature variability of surface waters using high-frequency data from 100 lakes. We show that the near-surface diel temperature range can be substantial in summer relative to long-term change and, for lakes smaller than 3 km², increases sharply and predictably with decreasing lake area. Most small lakes included in this study experience average summer diel ranges in their near-surface temperatures of between 4 and 7°C. Large diel temperature fluctuations in the majority of lakes undoubtedly influence their structure, function and role in biogeochemical cycles, but the full implications remain largely unexplored.     

Detecting the movement and spawning activity of bigheaded carps with environmental DNA

Bigheaded carps are invasive fishes threatening to invade the Great Lakes basin and establish spawning populations, and have been monitored using environmental DNA (eDNA). Not only does eDNA hold potential for detecting the presence of species, but may also allow for quantitative comparisons like relative abundance of species across time or space. We examined the relationships among bigheaded carp movement, hydrography, spawning and eDNA on the Wabash River, IN, USA. We found positive relationships between eDNA and movement and eDNA and hydrography. We did not find a relationship between eDNA and spawning activity in the form of drifting eggs. Our first finding demonstrates how eDNA may be used to monitor species abundance, whereas our second finding illustrates the need for additional research into eDNA methodologies. Current applications of eDNA are widespread, but the relatively new technology requires further refinement.     

Smoking and Subclinical ILD in RA versus the Multi-Ethnic Study of Atherosclerosis

A population-based cohort showed an association between cigarette smoking and subclinical parenchymal lung disease defined as regions of increased computed tomography (CT) lung densitometry. This technique has not been applied to the rheumatoid arthritis (RA) population where associated ILD is highly prevalent. The association between cumulative cigarette smoking and volume of areas of high attenuation (HAA: >-600 and <-250 Hounsfield Units) on full inspiratory CT was compared in 172 RA participants and 3,969 controls in a general population sample. Multivariable regression models were used to adjust for demography, anthropometrics, percent emphysema, and CT parameters. The mean cumulative cigarette smoking exposure was 25 (IQR 10–42) and 15(IQR 5–31) pack-years for the RA and non-RA cohorts, respectively. Mean HAA was 153(±57) cm³ and 129(±50) cm³ in the RA and non-RA cohorts, respectively. Each 10 cigarette pack-year increment was associated with a higher HAA by 0.03% (95% CI, 0.007–0.05%) in RA patients and by 0.008% (95% CI, 0.003–0.01%) in those without RA (interaction p = 0.001). Cigarette smoking was associated with higher lung attenuation; with a magnitude of association more pronounced in those with RA than in the general population. These data suggest that cigarette smoking may be a more potent ILD risk factor for RA patients than in the general population.     

Habituation and dishabituation mediated by the peripheral and central neural circuits of the siphon of aplysia

The siphon withdrawal response evoked by a weak tactile (water drop) or light stimulus is mediated primarily by neurons in the siphon. Central neurons (abdominal ganglion) contribute very little since the response amplitude and latency are not changed following removal of the abdominal ganglion. Similarly, habituation and dishabituation of this withdrawal response are not different after removal of the abdominal ganglion, indicating that the peripheral neural circuit in the isolated siphon can mediate habituation itself, and thus has many of the properties attributed to central neurons. Responses evoked by electrical stimulation of the siphon nerve habituate, depending upon the stimulus intensity and interval. These habituated responses may be dishabituated by tactile or light stimulation of the siphon. These results show that each neural system, peripheral and central, has an excitatory modulatory influence on the other. Normally adaptive siphon responses must be shaped by the integrated activity of both of these neural systems.     

Stimulation of (Na+K+)-ATPase of rat liver plasma membrane by amino acids

The effect of twelve l-amino acids on the activity of liver plasma membrane (Na⁺K⁺)-ATPase has been tested. Histidine and arginine significantly enhanced the activity. The activtion by histidine showed saturation kinetics with an apparent K_a of about 8 mM, and was evident over a wide range of Na⁺ concentrations. The same amino acid did not significantly affect the Mg²⁺-dependent ATPase activity.     

Survival of Neisseria gonorrhoeae in the Mail

Cultures of Neisseria gonorrhoeae, which used Thayer-Martin slants as transport medium, survived at least 1 day in the mail.     

Microbial Sulfate Reduction and Its Potential Utility as an Acid Mine Water Pollution Abatement Procedure

The presence of high concentrations of sulfate, iron, and hydrogen (acid) ions in drainage from coal mines and other areas containing waste pyritic materials is a serious water pollution problem. Sulfate can be removed from solution by microbial reduction to sulfide and subsequent precipitation as FeS. A mixed culture of microorganisms degraded wood dust cellulose, and the degradation products served as carbon and energy sources for sulfate-reducing bacteria. Metabolism of carbon compounds resulted in a net pH increase in the system. Oxidation-reduction potential (Eh) and temperature and carbon supplements were studied in an effort to accelerate the sulfate reduction process, with the ultimate objective of utilizing the process as a pollution abatement procedure.     

Lipid Composition and Temperature Adaptation of the Nervous System of the Leech Hirudo medicinalis L.

The lipid composition of the nervous system of the leech Hirudo medicinalis was investigated following acclimatization of animals at 25 degrees C and 5 degrees C. Choline, ethanolamine, and serine plus inositol phosphoglycerides are the major phospholipid classes of the leech ganglionic chain; minor amounts of lysophosphatidylcholine, phosphatidic acid, and sphingomyelin are also present. Neither the phospholipid pattern nor the cholesterol to total phospholipid molar ratio was dependent on the acclimatization temperature, whereas the fatty acid patterns of choline and serine plus inositol phosphoglycerides were significantly affected. Both for choline and serine plus inositol phosphoglycerides, a significant increase of the unsaturation index and a decrease of saturated to unsaturated fatty acid ratio was observed in animals acclimatized at 5 degrees C in comparison with those acclimatized at 25 degrees C. These observations, which point to increased lipid fluidity of the nervous system of cold-adapted leeches, are strengthened by results obtained by the fluorescence polarization method using 1,6-diphenyl-1,3,5-hexatriene as a probe: a decrease of the fluorescence polarization value was observed throughout the temperature range selected (5-40 degrees C).