The Global Regulatory Protein VelA Is Required for Symbiosis Between the Endophytic Fungus Epichloë festucae and Lolium perenne.

Epichloë species fungi form bioprotective endophytic symbioses with many cool-season grasses, including agriculturally important forage grasses. Despite its importance, relatively little is known about the molecular details of the interaction and the regulatory genes involved. The conserved velvet-domain protein VelA (or VeA) is a global regulator of a number of cellular and developmental functions in fungi. In this study, the E. festucae velA gene was functionally characterized in vitro and during interaction with perennial ryegrass. The velA gene is required in E. festucae for resistance to osmotic and cell wall-damaging stresses, repression of conidiation, and normal hyphal morphology during nutrient-limited in-vitro conditions. Expression of velA in E. festucae is light- and nitrogen-dependent and is tissue-specific in mature infected plants. In-planta studies showed that velA is required in E. festucae for a compatible interaction. Inoculating seedlings with mutant ΔvelA induced callose deposition and H2O2 production, and a high level of seedling death was observed. In surviving plants infected with ΔvelA mutant fungi, plants were stunted and we observed increased biomass and invasion of vascular bundles. Overall, this work characterizes a key fungal regulatory factor in this increasingly important model symbiotic association.

A morphological change in the fungal symbiont Neotyphodium lolii induces dwarfing in its host plant Lolium perenne.

The endophytic fungus Neotyphodium lolii forms symbiotic associations with perennial ryegrass (Lolium perenne) and infection is typically described as asymptomatic. Here we describe a naturally occurring New Zealand N. lolii isolate that can induce dwarfing of L. perenne and suppress floral meristem development in the dwarfed plants. Further to this we demonstrate that the observed host dwarfing correlates with a reversible morphological change in the endophyte that appears associated with colony age. Mycelium isolated from normally growing plants had a typical cottony appearance in culture whereas mycelium from dwarfed plants appeared mucoid. Cottony colonies could be induced to turn mucoid after prolonged incubation and seedlings inoculated with this mucoid mycelium formed dwarfed plants. Mucoid colonies on the other hand could be induced to form cottony colonies through additional further incubation and these did not induce dwarfing. The reversibility of colony morphology indicates that the mucoid dwarfing phenotype is not the result of mutation. Ten isolates from other locations in New Zealand could also undergo the reversible morphological changes in culture, induce dwarfing and had the same microsatellite genotype as the original isolate, indicating that a N. lolii genotype with the ability to dwarf host plants is common in New Zealand.

Evolution of the snow area index of the subarctic snowpack in central Alaska over a whole season. consequences for the air to snow transfer of pollutants.

The detailed physical characteristics of the subarctic snowpack must be known to quantify the exchange of adsorbed pollutants between the atmosphere and the snow cover. For the first time, the combined evolutions of specific surface area (SSA), snow stratigraphy, temperature, and density were monitored throughout winter in central Alaska. We define the snow area index (SAI) as the vertically integrated surface area of snow crystals, and this variable is used to quantify pollutants' adsorption. Intense metamorphism generated by strong temperature gradients formed a thick depth hoar layer with low SSA (90 cm(2) g-1) and density (200 kg m(-3)), resulting in a low SAI. After snowpack buildup in autumn, the winter SAI remained around 1000 m(2)/m(2) of ground, much lower than the SAI of the Arctic snowpack, 2500 m(2) m-(2). With the example of PCBs 28 and 180, we calculate that the subarctic snowpack is a smaller reservoir of adsorbed pollutants than the Arctic snowpack and less efficiently transfers adsorbed pollutants from the atmosphere to ecosystems. The difference is greater for the more volatile PCB 28. With climate change, snowpack structure will be modified, and the snowpack's ability to transfer adsorbed pollutants from the atmosphere to ecosystems may be reduced, especially for the more volatile pollutants.

Reduction in glucose levels in STZ diabetic rats by 4-(2,2-dimethyl-1-oxopropyl)benzoic acid: a prodrug approach for targeting the liver.

The overproduction of glucose by the liver in NIDDM patients markedly contributes to their fasting hyperglycemia and is a direct consequence of the increased oxidation of excess free fatty acids (FFA) being released from the adipocyte. 2-(1,1-Dimethylethyl)-2-(4-methylphenyl)[1,3]dioxolane (SAH51-641, 1) has previously been demonstrated to reduce glucose levels in animal models of diabetes by reducing fatty acid oxidation and hence depriving the system of the energy and cofactors necessary for gluconeogenesis. However, attempts at lowering glucose levels in vivo with 1 have been associated with toxicity in other organs such as the testes. An approach was developed utilizing the natural processing of triglyceride-like intermediates as a basis for selectively targeting the absorption, processing, and delivery of a prodrug to the liver. Compounds were identified by this method which lowered glucose levels in vivo without releasing toxic amounts of the active metabolites of 1 into circulation.

Physiological principles of therapy in head and neck cutaneous wounds.

It is essential that surgeons treating soft tissue wounds about the head and neck have a basic understanding of skin anatomy and physiology. The quality as well as the rate of healing is usually dependent on the type and extent of the original injury. Having a practical working knowledge of the pathophysiology of the various types of head and neck soft tissue injuries allows an intelligent choice of the most appropriate approach to a particular wound. The best functional and cosmetic results routinely are achieved by the wound's undergoing primary healing. Skin tapes and various sutures each exhibit certain benefits and disadvantages in primary closure of wounds. Skin tapes cause less inflammatory reaction but fail to close the subepithelial wound spaces. The inflammatory reaction and subsequent scarring caused by the various sutures depends upon the size of the suture needle, the diameter of the suture material and whether it is a monofilament or a woven suture. The essential nutrition of the wound must be maintained with the body providing adequate amounts of carbohydrates, proteins, trace elements and vitamins. The lack of adequate wound tissue perfusion by a normal or reversed oxygen gradient will lead to tissue necrosis and infection. The size of the inoculum of micro-organisms, the virulence of the organisms and host antimicrobial defense mechanisms determine if an infection will develop. The pharmacological action of each antibiotic must be understood in order to choose the proper antibiotic, its route of administration and to avoid unwanted side effects. Crushing tissue injuries, high velocity projectile tissue injuries and major burns of tissue may require several days to exhibit the true scope of the original injury. Most of these injuries must be treated by the open delayed method of wound treatment until the proper tissue conditions exist for healing. The proper timing and correct choice of autografts and tissue flaps from the surgeon's personal experience, study and conferring with other qualified surgeons. Upon gaining insight into the cellular and humoral antimicrobial defense system, the surgeon is able to provide the best conditions to allow these systems to function properly. Studies in the ultrastructures of skin along with the recently developed microbioassay techniques will allow a closer monitoring during the process of wound healing that will provide the basis for future techniques in the beneficial manipulation of wound healing.