An improved host-vector system for Candida maltosa using a gene isolated from its genome that complements the hiss mutation of Saccharomvces cerevisiae

Summary The host-vector system of an n-lkaneassimilating-yeast, Candida maltosa, which we previously constructed using an autonomously replicating sequence (ARS) region isolated from the genome of this yeast, utilizes C. maltosa J288 (leu2 ^–) as a host. As this host had a serious growth defect on n-alkane, we developed an improved host-vector system using C. maltosa CHI (his) as host. The vectors were constructed with the Candida ARS region and a DNA fragment isolated from the genome of C. maltosa. Since this DNA fragment could complement histidine auxotrophy of both C. maltosa CH1 and S. cerevisiae (hiss ^–), we termed the gene contained in this DNA fragment C-HIS5. The vectors were characterized in terms of transformation frequency and stability, and the nucleotide sequence of C-HISS was determined. The deduced amino acid sequence (389 residues) shared 51% homology with that of HISS of S. cerevisiae (384 residues; Nishiwaki et al. 1987).     

A pharmacological and histological examination of the microcirculation of the rat subcutaneous air-pouch: microcirculation of the rat air-pouch

The effects of histamine, 5-hydroxytryptamine (5-HT) and prostaglandin E2 (PGE2) on plasma protein extravasation in the rat subcutaneous air-pouch have been studied. Both histamine and 5-HT produced increases in plasma protein extravasation which were inhibited by specific receptor antagonists. Plasma protein extravasation induced by PGE2 was partially inhibited by either a 5-HT receptor antagonist (methysergide) or by a combination of H1 and H2 receptor antagonists (mepyramine and cimetidine). A combination of all three antagonists further reduced plasma protein extravasation. These results suggest that PGE2 increases vascular permeability indirectly via the degranulation of mast cells. This supposition was confirmed by histological evidence of extensive mast cell degranulation following the injection of PGE2 but not following histamine, 5-HT or saline injection. Using a technique of vascular labelling, following the intravenous injection of Monastral blue dye, plasma extravasation induced by histamine, 5-HT or PGE2 was observed to be restricted to post-capillary venules and was not observed in arterioles or capillaries. Electron microscopic examination of the tissue revealed the presence of monastral blue particles trapped between endothelial cells. These findings suggest that the microcirculation of the rat subcutaneous air-pouch behaves in an analogous manner to that of other tissues.     

The maitotoxin-evoked Ca2+ entry into synaptosomes is enhanced by cholera toxin

Effects of the Gs protein-mediated adenylate cyclase facilitatory system on Ca2+ entry into synaptosomes were studied, using two specific toxins. A putative Ca2+-channel agonist, maitotoxin (MTX), increased the 45Ca2+ entry and [Ca2+]i, determined with Quin-II, into synaptosomes of the rat brainstem, which were not attenuated by nifedipine. However, another Ca2+-channel agonist, BAY K-8644 did not alter the 45Ca2+ entry nor [Ca2+]i. The MTX-induced increase of the 45Ca2+ entry was significantly enhanced by addition of dibutyryl cyclic adenosine monophosphate and by the pretreatment with cholera toxin. These findings support the view that stimulation of presynaptic receptors coupled to the Gs-adenylate cyclase system may lead to a facilitation of the release of neurotransmitters, through a cAMP dependent enhancement of the opening of the Ca2+ channels located on nerve terminals.     

Movement of Aedes aegypti (Diptera: Culicidae) released in a small isolated village on Hainan Island, China

A mark-release-recapture experiment was conducted in a small isolated village on Hainan Island, China, to examine the dispersal and movement of adult Aedes aegypti (L.). Two cohorts of mosquitoes marked with uniquely colored fluorescent dye were released at two different sites and recaptured for 6 d at every house in the village using human bait collections. The distribution pattern of houses around release site affected dispersal. The recapture rate of females released at the center of the village was higher (3.49%) than females released at the edge of the village (2.47%). The average day of recapture differed significantly between sexes, but not cohorts. The average day of recapture of females and males released at the center was 2.5 and 1.54 d, respectively. The total number of mosquitoes recaptured was the greatest at premises near the release site, and decreased at a constant rate of 0.43-0.48 with increasing distance from the release site. The proportion of nulliparous females decreased during the first 4 d and proportion of females with developing or mature ovaries increased during the latter half of the experiment. The daily survival rate for females and males released at the center of the village was estimated by log-regression to be 0.763 and 0.52, respectively.     

Ulcerative proctitis, rectal prolapse, and intestinal pseudo-obstruction in transgenic mice overexpressing hepatocyte growth factor/scatter factor

Hepatocyte growth factor/scatter factor (HGF/SF) can stimulate growth of gastrointestinal epithelial cells in vitro; however, the physiological role of HGF/SF in the digestive tract is poorly understood. To elucidate this in vivo function, mice were analyzed in which an HGF/SF transgene was overexpressed throughout the digestive tract. Nearly a third of all HGF/SF transgenic mice in this study (28 of 87) died by 6 months of age as a result of sporadic intestinal obstruction of unknown etiology. Enteric ganglia were not overtly affected, indicating that the pathogenesis of this intestinal lesion was different from that operating in Hirschsprung's disease. Transgenic mice also exhibited a rectal inflammatory bowel disease (IBD) with a high incidence of anorectal prolapse. Expression of interleukin-2 was decreased in the transgenic colon, indicating that HGF/SF may influence regulation of the local intestinal immune system within the colon. These results suggest that HGF/SF plays an important role in the development of gastrointestinal paresis and chronic intestinal inflammation. HGF/SF transgenic mice may represent a useful model for the study of molecular mechanisms associated with a subset of IBD and intestinal pseudo-obstruction. Moreover, our data identify previously unappreciated side effects that may be encountered when using HGF/SF as a therapeutic agent.     

Slight difference in primary amino acid sequence of p17 matrix protein of HIV-1 exerts profound influence on its antigenicity

Summary.  HIV-1 p17 antigen has been studied for its biological significance in vitro as well as its immunological roles in vivo. By immunological approach of antibody-binding to HIV-1 p17 antigens of several subtypes in combination with computerized analysis of those tertial structures, it became evident that, irrelevant of similarity of linear amino acid sequence of different HIV-1 subtypes, a few amino acid substitutions close to or distant from specified epitope(s) affected their tertial structure resulting in change in ability of its binding to selected antibody. ELISA employing two monoclonal antibodies, A144 and C415, could detect p17 of subtypes A and B, but not of subtypes C, D, and E. Since the epitope site corresponding to A144 has been reported to be important for biological activity of p17 of HIV-1, change in tertial structure around this epitope may explain some difference in biology of HIV-1, such as infectivity of subtypes B and E. Accepted January 9, 1998 Received October 24, 1997     

EBI1-ligand chemokine (ELC) attracts a broad spectrum of lymphocytes: activated T cells strongly up-regulate CCR7 and efficiently migrate toward ELC

EBI1-ligand chemokine (ELC) is a CC chemokine constitutively expressed in various lymphoid tissues and a high-affinity functional ligand for EBI1/CCR7, a seven transmembrane G-protein-coupled receptor originally identified as an Epstein-Barr virus (EBV)-inducible gene. Here we examined chemotactic activity of ELC on peripheral blood leukocytes. ELC attracted both CD4+ and CD8+ T cells, particularly efficiently after activation with IL-2 or with phytohemagglutinin (PHA) plus IL-2, as well as CD19+ B cells, but not CD16+ NK cells, CD14+ monocytes or neutrophils. Among CD3+ T cells, ELC attracted both CD45RO- naive and CD45RO+ memory subsets. ELC also induced vigorous calcium mobilization in T cells stimulated with IL-2 with an ED50 of 3 nM. ELC fused with the secreted form of alkaline phosphatase (ELC-SEAP) specifically bound to lymphocytes and this binding was blocked only by ELC among 10 CC chemokines so far tested. Notably, lymphocytes stimulated with IL-2 or T cells expanded by PHA plus IL-2 showed much higher levels of binding than fresh lymphocytes. Consistently, CCR7 mRNA was detected in CD4+ and CD8+ T cells as well as B cells, but not in NK cells, monocytes or neutrophils, and was dramatically increased in T cells upon treatment with IL-2 or with PHA plus IL-2. Like ELC mRNA, CCR7 mRNA was expressed in various lymphoid tissues. By in situ hybridization, ELC and CCR7 mRNA were detected in the parafollicular and inner cortical regions of a lymph node, and in the parafollicular regions of an appendix. Collectively, ELC and CCR7 may be involved in the trafficking of a broad spectrum of lymphocytes, especially activated T cells, into and within various lymphoid tissues.      

Aldosterone

Aldosterone is one the representative cardiovascular hormones involved in the blood pressure and body-fluid homeostasis. Elevation of aldosterone leads to systemic hypertension through its action on the mineralocorticoid receptor (MR) in the kidney. More recent studies demonstrated that aldosterone may produce target organ damage through its direct actions on the non-epithelial MR of the heart in addition to its systemic effects. Clinical experience in primary aldosteronism supports the concept that aldosterone is a risk factor of cardiovascular complications, since concentric type of cardiac hypertrophy is most common in primary aldosteronism among various types of endocrine hypertension. Clinical mega-trial in congestive heart failure (RALES study, EPHESUS study) demonstrated blocking angiotensin II action is not sufficient for cardioprotection unless aldosterone action is equally blocked. An important phenomenon related to this issue is the aldosterone breakthrough which implies a reelevation of plasma aldosterone during chronic administration of ACE inhibitors and Angiotensin receptor antagonists. Normal level of aldosterone could still be a risk factor. Combination of ACE inhibitor or ARB with aldosterone antagonist could result in a better cardioprotection in cardiovascular diseases. Although spironolactone has been the only one aldosterone antagonist, a new antagonist eplerenone has been developed. Eplerenone is specific to MR and is practically devoid of the major side effect gynecomastia of spironolactone. Another topic of aldosterone is its very quick cardiovascular effect presumably via a non-genomic action. All these recent findings support that this adrenocortical steroid hormone is as important as angiotensin II. Determining aldosterone levels is therefore much morel important than before in the diagnosis and treatment of cardiovascular diseases.