Microcephalin, a gene regulating brain size, continues to evolve adaptively in humans

The gene Microcephalin (MCPH1) regulates brain size and has evolved under strong positive selection in the human evolutionary lineage. We show that one genetic variant of Microcephalin in modern humans, which arose approximately 37,000 years ago, increased in frequency too rapidly to be compatible with neutral drift. This indicates that it has spread under strong positive selection, although the exact nature of the selection is unknown. The finding that an important brain gene has continued to evolve adaptively in anatomically modern humans suggests the ongoing evolutionary plasticity of the human brain. It also makes Microcephalin an attractive candidate locus for studying the genetics of human variation in brain-related phenotypes.     

Release of bromide following rewetting of a naturally drained acid gully mire

Abstract. Currently there is growing interest in the restoration of drained peatlands in Britain. In order to investigate some of the effects of changes in land management practices on the biogeochemistry of peatlands, a field experiment was designed to manipulate the hydrological conditions in a naturally drained acid gully mire in Mid-Wales. We report preliminary results of the effects of experimentally rewetting the mire on the hydrochemistry of bromide in the peat-water. Results show that rewetting had a dramatic effect on the concentrations of bromide, which increased substantially. Peak values approached 1 mg/dm³ in some samples following rewetting, compared with typical values < 0.05 mg/dm³ under the drained conditions. Bromide was positively and significantly correlated with Dissolved Organic Carbon (DOC) in the peat-water, which suggests that Br^- is derived from breakdown of organic matter in the reducing conditions following rewetting. The bromide mobilized by rewetting may be leached out of the system and/or re-assimilated by the wetland vegetation. Further monitoring is needed to determine whether the observed hydrochemical response of bromide to rewetting of the mire has any longer-term effects.     

COLOR FLOW DOPPLER IMAGING AND DOPPLER SPECTRAL ANALYSIS OF THE BRAIN OF NEONATAL DOGS

Doppler ultrasonography was performed on the cerebral arteries o f 19 neontal dogs.Vascular structures were identified using anatomic preparations of brains pre-injected with a radiopaque silicone rubber product and cleared using a modified tissue clearing technique. Brain sections were subsequently radiographed of examined under a steromicroscope. Color flow Doppler imagin was used to facilitate positioning of the Doppler calipers for measurement of peak systolic velocity, minimum diastolic velocity, and resistance index. Blood flow velocities in the internal carotid and middle cerebral arteries were lower when measured intransvere images than in sagittal images. The rostral cerebral arteries could be measured using either plane but values obtained from different locations or using different methods of measurement were statistically different. Blood flow velocities generally increased during the first month after birth. Arterial signals were diphasic with flow throughout diastole. Resistance indices most often were between 0.6 and 0.7 and did not exceed 0.86.     

Finishing lamb performance responses to bovine and porcine somatotropins administered by Alzet pumps.

Daily injection of ovine and bovine somatotropin (oST and bST, respectively) has been shown to improve performance and carcass quality of finishing lambs. To evaluate responses to continuously released bST and porcine ST (pST), which have 99 and 91% sequence homology with oST, respectively, finishing lambs were implanted with 2-wk Alzet pumps containing bST or pST, which was released at rates of 2 or 4 mg/d. Six-week growth rate and feed efficiency responses to bST were greater than those to pST (P less than .05). Overall feed efficiency was improved 15% and growth rate was increased 16% in lambs treated with 4 mg/d of bST compared with control lambs and neither trait was affected in pST-treated lambs. Performance responses were reflected by changes in circulating glucose, blood urea nitrogen, and insulin-like growth factor I (IGF-I) concentrations. Scatchard analysis of sera with relative binding of greater than 30% revealed that average binding capacities and affinities of pST-treated lambs were 7.0 mg/liter and 6.0 x 10(9) liters/mol, respectively, and of bST-treated lambs were .8 mg/liter and 1.3 x 10(9) liters/mol, respectively. In addition, lambs with high-capacity pST antibodies had lower 6-wk IGF-I concentrations than those of controls, suggesting that these antibodies may have been attenuating responsiveness to pST. It is concluded that continuously released bST, but not pST, improves performance of finishing lambs.