Microbiological production of gluconic acid by Egyptian mould fungi

Summary A local strain of Asp. phoenicis proved to be a good gluconic acid producer. Previous experiments carried out on this organism were extended to investigate the influence of some culture conditions on the acid production when the submerged technique was applied. These included the investigation of the influence of the nature and concentration of the nutritive constituents of the fermentation medium.     

Inhibitory effects of dithiothreitol and sodium bisulfite on isolated rat ileum and atrium

The utility of sodium bisulfite and dithiothreitol as reducing agents in $\text{in}$$\text{vitro}$ preparations such as isolated rat atrium and ileum has been investigated. The right atria and 3 cm long ileal segments from male Sprague Dawley rats (250–350 g, sacrificed by cervical dislocation) were suspended in a 10 ml Magnus bath containing Tyrode's solution maintained at 37°C. Sodium bisulfite (0.955 - 9.55 mM) and dithiothreitol (5–50 μM) significantly depressed (P < .05) the duration of spontaneous atrial beating and the magnitude of methacholine-induced ileal contractions. The ileal inhibitory effects of these antioxidants became more pronounced with successive concentration-responses in the presence of methacholine but not with duration of exposure in the absence of methacholine, suggesting depletion of cellular energy stores by the antioxidants with successive ileal contractions. Depression of heart and intestinal tissues by bisulfite and dithiothreitol severelylimits their use as antioxidants to protect readily air oxidizable drugs during pharmacological testing with these standard tissue preparations.     

Evaporative Water Loss in Nine Insular Populations of the Lizard Anolis cristatellus Group in the British Virgin Islands

We studied water loss in eight insular populations of the lizard Anolis cristatellus wileyae and in one population of A. ernestwilliamsi in the British Virgin Islands. We found a strong negative correlation between habitat aridity and total and cutaneous water loss rate (ranging from 1.5–10.3 mg g^?1 h^?l) and a strong positive correlation between habitat aridity and integument resistance to water loss (28.5?199.0 s cm^?1). Water loss and integumentary resistance of A. ernestwilliamsi were similar to what would be predicted for A. cristatellus living in the same habitat. The Guana Island population of A. cristatellus was significantly different from all other populations. We believe two processes are responsible; phenotypic plasticity explains most of the observed variability, but genetic differentiation may be responsible for the distinction of lizards from Guana.     

Physiological roles of protein inhibitors

Protein inhibitors of proteases are widespread in nature. They are found in many sources, such as seeds, blood, eggs, and in many types of cells and tissues. Many physiological roles have been attributed to the protein inhibitors. Germination, wound healing, blood clotting, angiogenesis, etc., are some of the normal physiological activities in which protein inhibitors of proteases are involved. Lung destruction during emphysema and cartilage breakdown due to inflammation are two of the pathological conditions in which deficiency of protein inhibitors contributes to tissue breakdown by proteases.     

Generation of Escherichia coli intimin derivatives with differing biological activities using site-directed mutagenesis of the intimin C-terminus domain

Intimins, encoded by eae genes, are outer membrane proteins involved in attaching–effacing (A/E) lesion formation and host cell invasion by pathogenic bacteria, including enteropathogenic Escherichia coli (EPEC) and Citrobacter rodentium . A series of intimins, harbouring specific mutations close to the C-terminus, were constructed using pCVD438, which encodes the eae gene from EPEC strain E2348/69. These mutant plasmids were introduced into EPEC strain CVD206 and C. rodentium strain DBS255, which both contain deletion mutations in their eae genes. CVD206, CVD206(pCVD438) and CVD206(pCVD438) derivatives were assessed for their ability to promote A/E lesion formation or invasion of HEp-2 cells and to induce A/E lesions on fresh human intestinal in vitro organ cultures (IVOC). The pathogenicity of C. rodentium DBS255 harbouring these plasmid derivatives was also studied in mice. Here, we report that intimin-mediated A/E lesion formation can be segregated from intimin-mediated HEp-2 cell invasion. Moreover, adherence to IVOC, EPEC-induced microvillus elongation and colonization of the murine intestine by C. rodentium were also modulated by the modified intimins.