Control of stomatal distribution on the Arabidopsis leaf surface

Stomata regulate gas exchange and are distributed across the leaf epidermis with characteristic spacing. Arabidopsis stomata are produced by asymmetric cell divisions. Mutations in the gene TOO MANY MOUTHS (TMM) disrupt patterning by randomizing the plane of formative asymmetric divisions and by permitting ectopic divisions. TMM encodes a leucine-rich repeat-containing receptor-like protein expressed in proliferative postprotodermal cells. TMM appears to function in a position-dependent signaling pathway that controls the plane of patterning divisions as well as the balance between stem cell renewal and differentiation in stomatal and epidermal development.     

Subnanometer-Diameter Wires Isolated in a Polymer Matrix by Fast Polymerization

The preparation and analysis of inorganic-organic polymer nanocomposites consisting of inorganic nanowires and multiwire "cables" in a random-coil organic polymer host is reported. Dissolution of inorganic (LiMo3Se3)n wires in a strongly coordinating monomer, vinylene carbonate, and the use of a rapid polymerization in the presence of a cross-linking agent produce nanocomposites without phase separation. Polymerization of dilute solutions yields a material containing mostly (Mo3Se3(-))n mono- and biwires, 6 to 20 angstroms in diameter and 50 to 100 nanometers long. Polymerization of more concentrated liquid crystalline solutions yields a nanocomposite containing oriented multiwire cables, 20 to 40 angstroms in diameter and up to 1500 nanometers long, that display optical anisotropy and electrical conductivity.     

Finding genes that underlie complex traits

Phenotypic variation among organisms is central to evolutionary adaptations underlying natural and artificial selection, and also determines individual susceptibility to common diseases. These types of complex traits pose special challenges for genetic analysis because of gene-gene and gene-environment interactions, genetic heterogeneity, low penetrance, and limited statistical power. Emerging genome resources and technologies are enabling systematic identification of genes underlying these complex traits. We propose standards for proof of gene discovery in complex traits and evaluate the nature of the genes identified to date. These proof-of-concept studies demonstrate the insights that can be expected from the accelerating pace of gene discovery in this field.     

Halothane induced vasomotion of coronary, renal and iliac arterial rings in malignant hyperthermia susceptible swine.

Animals were identified as porcine malignant hyperthermia susceptible by halothane testing and were slaughtered at 90 kg of body weight. Coronary, renal and iliac arteries were isolated, dissected and 5 mm rings were mounted in 20 mL organ baths with modified Krebs solution maintained at 37 degrees C and oxygenated with 95% O2, 5% CO2. Halothane at 0%, 0.5%, 2% and 5% concentration was bubbled in the organ baths and mechanical responses were recorded over a period of 25 min. Halothane free arteries remained quiescent and the arteries from the halothane sensitive and from the halothane resistant groups reacted similarly. All arteries in the presence of halothane responded with an initial contraction of short duration followed by a relaxation and both phenomena occurred in a concentration-dependent fashion. The iliac artery was the most sensitive to halothane and responded to 0.5% concentration while coronary and renal arteries maintained the resting tension of 4 g. These results demonstrate that vascular smooth muscle, like skeletal muscle and unlike respiratory smooth muscle, has a direct pharmacological response to halothane. These observations led to the postulate that halothane by its transient but significant vasoconstrictive action could be a contributing factor to initiate the fulminant reactions occurring in malignant hyperthermia.     

Retrospective evaluation of potential causes associated with clinically relevant hyperlactatemia in dogs with lymphoma

The aim of this study was to determine whether or not canine lymphoma could be associated with a clinically relevant type B hyperlactatemia (> 2.5 mmol/L). The medical database from the University of Montreal Veterinary Medical Teaching Hospital was searched for confirmed cases of canine lymphoma with a blood lactate measurement. Information retrieved included stage, clinical observations compatible with causes of type A and B hyperlactatemia other than cancer, hepatic involvement, and drugs administered. Twenty (40%) dogs were hyperlactatemic. Five dogs (10%) were classified as having cancer-related hyperlactatemia. Seventy-five percent of hyperlactatemic dogs had clinical evidence of type A hyperlactatemia. In addition to lymphoma, 70% of hyperlactatemic dogs had evidence of an additional cause of type B hyperlactatemia. A significant association (P = 0.01) was identified between corticosteroid administration and hyperlactatemia. Cytological, echographic, and/or biochemical tests revealed hepatic changes in all hyperlactatemic dogs. Lymphoma alone may not be sufficient to explain clinically relevant hyperlactatemia in dogs.