Effect of diet on the weight of brown adipose tissue in rodents

Interscapular brown adipose tissue (BAT) weighed more in rats given access to a solution of sucrose in addition to a nutritionally complete basal diet than in rats eating only a basal diet. This incremental effect of drinking sucrose solution occurs across a variety of dietary conditions. In the first experiment, rats were fed diets containing either 9%, 18%, 27% or 36% casein. Rats given access to a sucrose solution had significantly larger brown fat pads than controls when the diets contained 9 or 18% casein, but not when diets contained either 27% or 36% casein. The second experiment examined the weight of brown adipose tissue as a function of the type of protein and the percentage of fat in the diet. Animals given a sucrose solution had significantly more BAT than animals not given sucrose. Neither the type of protein (casein or soy protein) nor the percentage of fat (14.5% or 36.4%) in the diet influenced the weight of BAT. Animals given access to either a sucrose solution or a glucose solution had significantly heavier BAT than animals given access to a fructose solution, granulated sucrose or water.     

Noncovalent Intermolecular Forces in Phycobilisomes of Porphyridium cruentum

Using sensitized fluorescence as a measure of intactness of phycobilisomes isolated from Porphyridium cruentum, the effects of various environmental perturbations on phycobilisome integrity were investigated. The rate of phycobilisome dissociation in 0.75 ionic strength sodium salts proceeds in the order: SCN⁻ > NO₃⁻ > Cl⁻ > C₆H₅O₇³⁻ > SO₄²⁻ > PO₄³⁻, as predicted from the lyotropic series of anions and their effects on hydrophobic interactions in proteins. Similarly, increasing temperature (to 30 C) and pH values approaching the isoelectric points of the biliproteins stabilize phycobilisomes. Deuterium substitution at exchangeable sites on the phycobiliproteins decreases the rate of phycobilisome dissociation, while substitution at nonexchangeable sites increases rates of dissociation. It is concluded that hydrophobic intermolecular interactions are the most important forces in maintaining the phycobilisome structure. Dispersion forces also seem to contribute to phycobilisome stabilization. The adverse effects of electrostatic repulsion must not be ignored; however, it seems that the requirement of phycobilisomes of high salt concentrations is not simply countershielding of charges on the proteins.     

Vasopressin content of rat brain

Vasopressin was extracted and measured from various areas of rat brain. Vasopressin in quantities many times that in circulating blood was found in most areas of brain except for cerebellum. The highest concentration of vasopressin were found in the amygdala, septum, thalamus and striatum. Homozygous Brattleboro rat brain contained negligible amounts of vasopressin. The rat brain extract reacted identically with standard vasopressin in the radioimmunoassay over a 40-fold dilution range and migrated with vasopressin on Sephadex G-25 chromatography.     

Modelling expected trout ranges under current and future water temperature regimes in the Eastern Cape,South Africa

Different values have resulted in conflicts between anglers and conservation lobbies in the management of trout in South Africa. Key to the conflict is the demarcation of boundaries to areas in which brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss currently occur, or are likely to establish following stocking for angling. To provide a longer-term perspective on these areas, we developed models to link salmonid biological thermal thresholds to elevation. These, when applied spatially using a digital elevation model with a probability of occurrence model, provided the basis for estimating potentially available thermal habitat for these two cold water species. Here, we acknowledge that other variables (stocking history; river connectivity) also play a role in understanding trout distributions. Using a simple scenario of an increase in mean daily water temperatures of 2 °C, we demonstrated that both brown and rainbow trout are likely to exhibit considerable range reductions in the future. Because it is possible that these range restrictions will result in an increasing desire to introduce trout into areas above their current distribution limits for the maintenance of angling opportunities, conservation managers should prioritise these areas, with management interventions seeking to understand what will help to limit introductions.     

ACC deaminase from plant growth-promoting bacteria affects crown gall development

In addition to the well-known roles of indoleacetic acid and cytokinin in crown gall formation, the plant hormone ethylene also plays an important role in this process. Many plant growth-promoting bacteria (PGPB) encode the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which can degrade ACC, the immediate precursor of ethylene in plants, to alpha-ketobutyrate and ammonia and thereby lower plant ethylene levels. To study the effect of ACC deaminase on crown gall development, an ACC deaminase gene from the PGPB Pseudomonas putida UW4 was introduced into Agrobacterium tumefaciens C58, so that the effect of ACC deaminase activity on tumour formation in tomato and castor bean plants could be assessed. Plants were also coinoculated with A. tumefaciens C58 and P. putida UW4 or P. putida UW4-acdS- (an ACC deaminase minus mutant strain). In both types of experiments, it was observed that the presence of ACC deaminase generally inhibited tumour development on both tomato and castor bean plants.     

1-Aminocyclopropane-1-carboxylate deaminase from Pseudomonas putida UW4 facilitates the growth of canola in the presence of salt

The growth of canola plants treated with either wild-type Pseudomonas putida UW4 or a 1-aminocyclopropane-1-carboxylate (ACC) deaminase minus mutant of this strain was monitored in the presence of inhibitory levels of salt, i.e., 1.0 mol/L at 10 degrees C and 150 mmol/L at 20 degrees C. This strain is psychrotolerant with a maximal growth rate of approximately 30 degrees C and the ability to proliferate at 4 degrees C. Although plant growth was inhibited dramatically by the addition of 1.0 mol/L salt at 10 degrees C and only slightly by 150 mmol/L salt at 20 degrees C under both sets of conditions, the addition of the wild type but not the mutant strain of P. putida UW4 significantly improved plant growth. This result confirms the previous suggestion that bacterial strains that contain ACC deaminase confer salt tolerance to plants by lowering salt-induced ethylene synthesis.     

Clathrin adaptors mediate two sequential pathways of intra-Golgi recycling

The pathways of membrane traffic within the Golgi apparatus are not fully known. This question was addressed using the yeast Saccharomyces cerevisiae, in which the maturation of individual Golgi cisternae can be visualized. We recently proposed that the AP-1 clathrin adaptor mediates intra-Golgi recycling late in the process of cisternal maturation. Here, we demonstrate that AP-1 cooperates with the Ent5 clathrin adaptor to recycle a set of Golgi transmembrane proteins, including some that were previously thought to pass through endosomes. This recycling can be detected by removing AP-1 and Ent5, thereby diverting the AP-1/Ent5–dependent Golgi proteins into an alternative recycling loop that involves traffic to the plasma membrane followed by endocytosis. Unexpectedly, various AP-1/Ent5–dependent Golgi proteins show either intermediate or late kinetics of residence in maturing cisternae. We infer that the AP-1/Ent5 pair mediates two sequential intra-Golgi recycling pathways that define two classes of Golgi proteins. This insight can explain the polarized distribution of transmembrane proteins in the Golgi.     

Determination of 1-aminocycopropane-1-carboxylic acid (ACC) to assess the effects of ACC deaminase-containing bacteria on roots of canola seedlings

Previously, it was proposed that plant growth-promoting bacteria that possess the enzyme, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, can reduce the amount of ethylene produced by a plant and thereby promote root elongation. To test this model, canola seeds were imbibed in the presence of the chemical ethylene inhibitor, 2-aminoethoxyvinyl glycine (AVG), various strains of plant growth-promoting bacteria, and a psychrophilic bacterium containing an ACC deaminase gene on a broad host range plasmid. The extent of root elongation and levels of ACC, the immediate precursor of ethylene, were measured in the canola seedling roots. A modification of the Waters AccQ.Tag Amino Acid Analysis Method was used to quantify ACC in the root extracts. It was found that, in the presence of the ethylene inhibitor, AVG, or any one of several ACC deaminase-containing strains of bacteria, the growth of canola seedling roots was enhanced and the ACC levels in these roots were lowered.