Non-destructive analysis of root growth in porous media

A technique is described for non-destructive observations and analysis of root growth in granular media, using time-lapse video in conjunction with a pressure cell. The pressure cell consists of one half of a traditional triaxial cell with a flat clear perspex front allowing growth of the root to be monitored using a video camera. The cell is connected to an external pressure supply, which is used to regulate precisely the confining pressure, and hence, the physical impedance to root growth. Preliminary results of the growth of root axes and the emergence of laterals of peas over a range of physical impedances are presented to illustrate the potential of this technique in studying root growth.     

Role of the Liver in Inflammation

INFLAMMATION leads to the appearance in plasma and inflammatory exudates of a protein with anti-inflammatory properties^1–4. The greatest concentration of this anti-inflammatory protein (AIP) occurs relatively late after injury², which suggests that it plays a role in the later stages of the inflammatory reaction and during healing. The synthesis of the protein is shown here to be similar to that of most other plasma proteins in that it occurs in the liver, which raises the question of the extent to which inflammation is influenced or controlled by the rates of synthesis of plasma proteins.     

The Metabolism and Translocation of Zeatin in Intact Radish Seedlings

After the roots of intact radish seedlings had taken up [³H]zeatinfor 1 h, the seedlings were transferred to nutrient lackingzeatin and extracted at intervals. After 23 h in the absenceof zeatin, 6 per cent of the radioactivity extracted per seedlingwas recovered from the de-ribbed cotyledon laminae, 4 per centfrom the hypocotyls, and 87 per cent from the roots. Per unitweight of tissue, the radioactivity extracted from the rootwas about 40 times that recovered from any other region. Zeatin was rapidly metabolized by the root tissue, and 4 to9 h after transfer of the seedlings to nutrient lacking zeatin,accounted for a negligible proportion of the radioactivity.Initially zeatin riboside 5'-monophosphate was the principalroot metabolite, but after 9 h, 7-glucosylzeatin (raphanatin)was the dominant metabolite. Conversion of zeatin to dihydrozeatinwas not detected. Raphanatin was also the major metabolite inthe cotyledon laminae where some free zeatin was detectable.The principal metabolites in hypocotyl extracts were AMP andzeatin riboside 5'-monophosphate but zeatin riboside was theonly significant source of radioactivity in the xylem sap. When [³H]zeatin was applied directly to cotyledon laminae, 99per cent of the radioactivity was localized in the treated laminae;however traces of zeatin were detected in the roots. In radish seedlings, zeatin riboside appears to be the translocationalform of zeatin, while raphanatin may be a storage form.     

Cloning and expression analysis of two distinct HIF-alpha isoforms – gcHIF-1alpha and gcHIF-4alpha – from the hypoxia-tolerant grass carp,Ctenopharyngodon idellus

Background  

Hypoxia-inducible factors (HIFs) are involved in adaptive and survival responses to hypoxic stress in mammals. In fish, very little is known about the functions of HIFs.     

Recovery and evolutionary analysis of complete integron gene cassette arrays from Vibrio

Background  

Integrons are genetic elements capable of the acquisition, rearrangement and expression of genes contained in gene cassettes. Gene cassettes generally consist of a promoterless gene associated with a recombination site known as a 59-base element (59-be). Multiple insertion events can lead to the assembly of large integron-associated cassette arrays. The most striking examples are found in Vibrio, where such cassette arrays are widespread and can range from 30 kb to 150 kb. Besides those found in completely sequenced genomes, no such array has yet been recovered in its entirety. We describe an approach to systematically isolate, sequence and annotate large integron gene cassette arrays from bacterial strains.