Defective GM3 Synthesis in Cog2 Null Mutant CHO Cells Associates to Mislocalization of Lactosylceramide Sialyltransferase in the Golgi Complex

The conserved oligomeric Golgi (COG) complex is a eight subunit (COG1 to 8) tethering complex involved in the retrograde trafficking of multiple Golgi processing proteins. Here we studied the glycolipid synthesis status in ldlC cells, a Cog2 null mutant CHO cell line. Biochemical studies revealed a block in the coupling between LacCer and GM3 synthesis, resulting in decreased levels of GM3 in these cells. Uncoupling was not attributable to decreased activity of the glycosyltransferase that uses LacCer as acceptor substrate (SialT1). Rather, immunocytochemical experiments evidenced a mislocalization of SialT1 as consequence of the lack of Cog2 in these cells. Co-immunoprecipitation experiments disclose a Cog2 mediated interaction of SialT1 with the COG complex member Cog1. Results indicate that cycling of some Golgi glycolipid glycosyltransferases depends on the participation of the COG complex and that deficiencies in COG complex subunits, by altering their traffic and localization, affect glycolipid composition.     

A zoonotic ringworm outbreak caused by a dysgonic strain of Microsporum canis from stray cats

BackgroundCats are frequent carriers of Microsporum canis and veterinary students are at high risk of exposure and acquisition of the organism a la infección.ObjectivesAn outbreak of zoonotic ringworm carried by a litter of stray cats is described. Four veterinary students, four dogs, and six cats living in five separate locations were affected. All had direct or indirect contact with the infected kitten litter. We tried to identify the causal dermatophyte.MethodsConventional and mycological culture methods were used.ResultsMicroscopic features of scrapings and hairs treated with 20% KOH strongly suggested a M. canis etiology, and a diagnosis of ringworm was empirically supported by successful treatment of humans and animals. Nevertheless, cultures failed to show the expected morphology.ConclusionsCulture features of our strain are compared with those described by other authors for dysgonic M. canis strains. Epidemiological features are also discussed.     

Binding of arachidonic acid and two flavonoid inhibitors to human 12- and 15-lipoxygenases: a steered molecular dynamics study

The lipoxygenases (LOX) are a family of non-heme iron-containing dioxygenases which catalyze the stereospecific insertion of molecular oxygen into arachidonic acid, leading to hydroxy derivatives as end products. In this work, we docked arachidonic acid and two of its competitive inhibitors, flavonoids baicalein and quercetin, into the binding pockets of human 12- and 15-lipoxygenase. Steered molecular dynamics (SMD) simulations were employed to study the unbinding processes of the substrate and inhibitors from the two isoforms.     

Transcriptional response to alcohol exposure in Drosophila melanogaster

Background  

Alcoholism presents widespread social and human health problems. Alcohol sensitivity, the development of tolerance to alcohol and susceptibility to addiction vary in the population. Genetic factors that predispose to alcoholism remain largely unknown due to extensive genetic and environmental variation in human populations. Drosophila, however, allows studies on genetically identical individuals in controlled environments. Although addiction to alcohol has not been demonstrated in Drosophila, flies show responses to alcohol exposure that resemble human intoxication, including hyperactivity, loss of postural control, sedation, and exposure-dependent development of tolerance.     

Bacterial swimming strategies and turbulence

Most bacteria in the ocean can be motile. Chemotaxis allows bacteria to detect nutrient gradients, and hence motility is believed to serve as a method of approaching sources of food. This picture is well established in a stagnant environment. In the ocean a shear microenvironment is associated with turbulence. This shear flow prevents clustering of bacteria around local nutrient sources if they swim in the commonly assumed "run-and-tumble" strategy. Recent observations, however, indicate a "back-and-forth" swimming behavior for marine bacteria. In a theoretical study we compare the two bacterial swimming strategies in a realistic ocean environment. The "back-and-forth" strategy is found to enable the bacteria to stay close to a nutrient source even under high shear. Furthermore, rotational diffusion driven by thermal noise can significantly enhance the efficiency of this strategy. The superiority of the "back-and-forth" strategy suggests that bacterial motility has a control function rather than an approach function under turbulent conditions.     

Ultrastructural evidences of HCV infection in hepatocytes of chronically HCV-infected patients

In this study, 13 samples of liver biopsies from patients with chronic hepatitis C were studied by transmission electron microscopy (EM) and immunoelectron microscopy (IEM). The 13 biopsies showed ultrastructural cell damage typical of acute viral hepatitis. In four of the 13 liver biopsies enveloped virus-like particles (VLPs) inside cytoplasmic vesicles and in the cytoplasm of hepatocytes were observed. We also detected the presence of unenveloped VLPs mainly in the cytoplasm and in the endoplasmic reticulum. IEM using anti-core, E1 and E2 monoclonal antibodies (mAbs) confirmed the specific localization of these proteins, in vivo, inside cytoplasm and endoplasmic reticulum. Thus, this work provided evidence for hepatocellular injury related to HCV infection. It also suggested the presence of HCV-related replicating structures in the cytoplasm of hepatocytes and raised the possibility of hepatitis C virion morphogenesis in intracellular vesicles.     

The question of uniqueness of ancient bacteria

Microorganisms are associated with a variety of ancient geological materials. However, conclusive proof that these organisms are as old as the geological material and not more recent introductions has generally been lacking. Over the years, numerous reports of the isolation of ancient bacteria from geological materials have appeared. Most of these have suffered from the fact that the protocol for the surface sterilization of the sample was either poorly defined, inadequate or rarely included data to validate the overall effectiveness of the sterilization protocol. With proper sterility validation and isolation protocol, a legitimate claim for the isolation of an ancient microbe can be made. Biochemical, physiological, or morphological data indicate that these ancient microbes are not significantly different from modern isolates. As the role (decomposition) of modern and ancient microbes has not changed over time, it is probably unreasonable to expect these organisms to be vastly different. A discussion on the reasons for the homogeneity of ancient and modern microbes is presented. Journal of Industrial Microbiology & Biotechnology (2002) 28, 32–41 DOI: 10.1038/sj/jim/7000174 Received 20 May 2001/ Accepted in revised form 16 June 2001