Immobilisation of phosphorus by iron-coated roots of submerged macrophytes

Hydrobiologia - To observe effects on the phosphorus retention mechanisms of a lake after re-colonisation by macrophytes, Potamogeton crispus L. and Elodea canadensis Michx. were planted in lab...     

Expanded thermal niche for a diving vertebrate: A leatherback turtle diving into near-freezing water

The global distribution of extant reptiles is more limited than that of mammals or birds, with low reptilian species diversity at high latitudes. Central to this limited geographical distribution is the ectothermic nature of reptiles, which means that they generally become torpid at cold temperatures. However, here we report the first detailed telemetry from a leatherback turtle (Dermochelys coriacea) diving in cold water at high latitude. An individual equipped with a satellite tag that relayed temperature-depth profiles dived continuously for many weeks into sub-surface waters as cold as 0.4 °C. Global warming will likely increase the foraging range of leatherback turtles further into temperate and boreal waters.     

Heritability of Eating Behavior Assessed Using the DEBQ (Dutch Eating Behavior Questionnaire) and Weight‐related Traits: The Healthy Twin Study

The heritability of eating behavior and body weight–related traits in Asian populations has not been reported. The purpose of this study was to estimate the heritability of eating behavior and the body weight–related traits of current weight and self‐reported past weight among twins and their families. Study subjects were 2,144 Korean, adult, same‐sex twins and their families at the ages between 20 and 65 years (443 monozygotic (MZ) and 124 dizygotic (DZ) twin pairs, and 1,010 individuals of their family). The Dutch Eating Behavior Questionnaire (DEBQ) was used to assess three eating behavior subscales measuring restraint, emotional eating, and external eating. A variance component approach was used to estimate heritability. After consideration of shared environmental effects and adjustment for age and sex effects, the heritability estimates ± s.e. among twins and their family members were 0.31 ± 0.036 for restraint, 0.25 ± 0.098 for emotional eating, 0.25 ± 0.060 for external eating, 0.77 ± 0.032 for measured current body weight, and 0.70 ± 0.051 for self‐reported weight at 20 years old. The three DEBQ subscales were associated with all weight related traits after adjustment for age and sex. These results suggest eating behaviors and weight‐related traits have a genetic influence, and eating behaviors are associated with obesity indexes. Our findings from Korean twin family were similar to those reported in Western populations.     

Stable ester conjugate between the Saccharomyces cerevisiae RAD6 protein and ubiquitin has no biological activity.

The RAD6 gene of Saccharomyces cerevisiae, which encodes a ubiquitin-conjugating enzyme, is required for DNA repair, DNA damage-induced mutagenesis and sporulation. To evaluate the biological relevance of the thioester adduct between RAD6 protein and ubiquitin, formed as an obligatory, transient intermediate during ubiquitin conjugation to substrates, we altered cysteine 88 in RAD6 to serine. Esterification with ubiquitin occurs at serine 88 in the mutant protein, but conjugation of ubiquitin to the test substrate histone H2A is inactivated. Phenotypically, strains harboring the rad6 Ser88 allele are indistinguishable from rad6 deletion (rad6 delta) mutant cells. These findings argue against ligation of ubiquitin at cysteine 88 acting as a functional switch of a cryptic biochemical activity in RAD6.     

Allium cepa L. Cultivars from Four Continents Compared by Flow Cytometry show Nuclear DNA Constancy

In 1965 Van't Hof estimated the nuclear DNA amount of an unidentifiedAllium cepa L. cultivar as 2C = 33.55 pg (Experimental CellResearch39: 8–58). This value has been adopted by commonusage as the main calibration standard for angiosperm DNA C-valueestimations. However, different cultivars have been used whileassuming species DNA C-value constancy. Surprisingly this assumptionhas never been tested. A. cepa is an outbreeder with telomericheterochromatic segments, so intraspecific variation in C-value,possibly correlated with environmental factors as seen in Zeamays L., might be expected. We used laser flow cytometry tocompare nuclear DNA amounts in roots of six A. cepa cultivarsused as calibration standards or from different environments.Tissues from one cultivar, or similar volumes of tissue fromtwo cultivars, were run and the variance between nuclei in 2Cpeaks compared. Only one shoulderless 2C peak was seen for allpairs of co-chopped cultivars. Thus, no large differences inC-value between cultivars from different environments were found.Moreover, comparing cultivars run singly or as pairs showedno evidence for increased variation in 2C peaks in the latter,and hence of critical differences in DNA amounts between ‘AilsaCraig’ and another cultivar. Such variation was insufficientto make their use as alternative calibration standards, or thepractice of imputing Van't Hof's original C-value estimate tothem, unacceptable for most practical purposes. Given the mechanismsknown which can generate genome size variation, the degree ofconstancy in DNA C-value found seems remarkable. Copyright 2000Annals of Botany Company Allium cepa, onion cultivars, calibration standards, DNA C-value constancy, flow cytometry     

Septum volume and food‐storing behavior are related in parids

The hippocampal formation (HF) of food‐storing birds is larger than non‐storing species, and the size of the HF in food‐storing Black‐Capped Chickadees (Poecile atricapillus) varies seasonally. We examined whether the volume of the septum, a medial forebrain structure that shares reciprocal connections with the HF, demonstrates the same species and seasonal variation as has been shown in the HF. We compared septum volume in three parid species; non‐storing Blue Tits (Parus caeruleus) and Great Tits (Parus major), and food‐storing Black‐Capped Chickadees. We found the relative septum volume to be larger in chickadees than in the non‐storing species. We also compared septum and nucleus of the diagonal band (NDB) volume of Black‐Capped Chickadees at different times of the year. We found that the relative septum volume varies seasonally in food‐storing birds. The volume of the NDB does not vary seasonally. Due to the observed species and seasonal variation, the septum, like the hippocampal formation of food‐storing birds, may be specialized for some aspects of food‐storing and spatial memory. © 2002 Wiley Periodicals, Inc. J Neurobiol 51: 215–222, 2002