Phylogeny of the lizard subfamily Lygosominae (Reptilia: Scincidae), with special reference to the origin of the new world taxa

Phylogenetic relationships of the three lygosomine skink genera occurring both in the Old World and the New World (Mabuya, Scincella and Sphenomorphus) were inferred from mitochondrial DNA sequence of 12S and 16S rRNA genes. Results strongly suggested the non-monophyly for any of these three genera. Within the Mabuya group, Asian members appear to have diverged first, leaving the Neotropical and the Afro-Malagasy Mabuya as sister groups. These relationships, together with the absence of extant or fossil representatives of the Mabuya group from North America, strongly suggest the trans-Atlantic dispersals of Mabuya from Africa to Neotropics. Our results also indicated a closer affinity of the New World Scincella with the New World Sphenomorphus than with the Old World Scincella. Such relationships suggest the trans-Beringian dispersal of the common ancestor from Asia and its subsequent divergence into the North American Scincella and the Neotropical Sphenomorphus.     

Cloning and characterization of the fur gene from Moraxella bovis

A homologue of the ferric uptake regulator gene (fur) was isolated from Moraxella bovis by degenerate polymerase chain reaction and cloning. Fur protein of M. bovis exhibited 72.1% amino acid identity with Acinetobacter calcoaceticus Fur. Western blot analysis showed a decrease of Fur expression in response to sufficient-iron conditions compared with deficient-iron conditions. An electrophoretic mobility-shift assay indicated that Fur protein binds to DNA fragments containing a putative Fur-box derived from the upstream region of the M. bovis fur gene. Fur of M. bovis may regulate the expression of iron transport systems in response to iron limitation in the environment.     

Ability of CD8(+) T cell anti-feline immunodeficiency virus activity correlated with peripheral CD4(+) T cell counts and plasma viremia

In the host defense mechanism against feline immunodeficiency virus (FIV) infection, CD8(+) T cells specifically attack virus-infected cells and suppress the replication of the virus in a non-cytolytic manner by secreting soluble factors. In this study, we measured CD8(+) T cell anti-FIV activity in 30 FIV-infected cats. We investigated its relationship with the number of peripheral blood lymphocytes, particularly the CD4(+) T cell and CD8(+) T cell counts, and the relationship between anti-FIV activity and the number of T cells of CD8alpha(+)beta(lo) and CD8alpha(+)beta(-) phenotypes. A clearly significant correlation was observed between anti-FIV activity and the number of CD4(+) T cells. A weaker anti-FIV activity was associated with a greater decrease in the number of CD4(+) T cells. However, there was no significant correlation between anti-FIV activity and the number of B or CD8(+) T cells. Compared with SPF cats, FIV-infected cats had significantly higher CD8alpha(+)beta(lo) T cell and CD8alpha(+)beta(-) T cell counts, but, no significant correlation was observed between these cell counts and anti-FIV activity. This anti-FIV activity significantly correlated with plasma viremia, which was detected in cats with a weak anti-FIV activity. These results suggest that the anti-FIV activity of CD8(+) T cells plays an important role in plasma viremia and the maintenance of CD4(+) T cells in the body. It is unlikely that CD8alpha(+)beta(lo) or CD8alpha(+)beta(-) T cells appearing after FIV infection represent a phenotype of CD8(+) cells with anti-FIV activity.     

Chloramphenicol resistance transposable element TnSs1 of Streptococcus suis,a transposon flanked by IS6-family elements

A new transposon, designated TnSs1, which contains a chloramphenicol acetyltransferase gene flanked by direct repeats of an IS6-family element was found in a field isolate of Streptococcus suis. Polymerase chain reaction and hybridization analyses indicated that another field isolate carried the same transposon in a different location on the chromosome. A transposition assay done with a thermosensitive suicide vector showed that, among the seven TnSs1 mutants tested in this study, six formed a cointegrate between the S. suis genome and the vector with the generation of the third copy of the insertion sequence element, and one harbored one copy of TnSs1 on the chromosome as a result of a subsequent resolution step. On transposition, TnSs1 duplicated an 8-bp sequence at the target site.     

Interaction between leukemic-cell VLA-4 and stromal fibronectin is a decisive factor for minimal residual disease of acute myelogenous leukemia

Bone-marrow minimal residual disease (MRD) causes relapse after chemotherapy in patients with acute myelogenous leukemia (AML). We postulate that the drug resistance is induced by the attachment of very late antigen (VLA)-4 on leukemic cells to fibronectin on bone-marrow stromal cells. We found that VLA-4-positive cells acquired resistance to anoikis (loss of anchorage) or drug-induced apoptosis through the phosphatidylinositol-3-kinase (PI-3K)/AKT/Bcl-2 signaling pathway, which is activated by the interaction of VLA-4 and fibronectin. This resistance was negated by VLA-4-specific antibodies. In a mouse model of MRD, we achieved a 100% survival rate by combining VLA-4-specific antibodies and cytosine arabinoside (AraC), whereas AraC alone prolonged survival only slightly. In addition, overall survival at 5 years was 100% for 10 VLA-4-negative patients and 44.4% for 15 VLA-4-positive patients. Thus, the interaction between VLA-4 on leukemic cells and fibronectin on stromal cells may be crucial in bone marrow MRD and AML prognosis.     

Correlations of calcium accumulations in arteries, veins, cartilages, ligaments, and bones in single humans

To show the relationships of calcium accumulation in the thoracic aorta to the other tissues, calcium contents were determined with a microwave-induced plasma-atomic emission spectrometer on arteries, veins, cartilages, ligaments, and bones. These tissues were resected from 18 individuals, consisting of 11 men and 7 women who died in the age range 59–91 yr. As thoracic and abdominal aortas are routinely used for radiographic examination of arterial calcification, they appear to be standard tissues of the calcium accumulation. The calcium accumulations were determined in the femoral artery, the superior and inferior venae cavae, the internal jugular vein, cartilages of the articular disk of the temporomandibular joint and the intervertebral disk, both the ligaments of the anterior cruciate ligament and the ligamentum capitis femoris, and the calcaneus, in contrast with the thoracic aorta. As calcium increased in the thoracic aorta, it increased in the femoral artery, the articular disk of the temporomandibular joint, the intervertebral disk, both ligaments of the anterior cruciate ligament, and the ligamentum capitis femoris, but it did not increase in veins, such as the superior and inferior venae cavae and the internal jugular vein. In contrast, it decreased in the calcaneus.     

Neospora caninum:Tachyzoites Express a Potent Type-I Nucleoside Triphosphate Hydrolase,but Lack Nucleoside Diphosphate Hydrolase Activity

Asai, T., Howe, D. K., Nakajima, K., Nozaki, T., Takeuchi, T., and Sibley, L. D.Neospora caninum: Tachyzoites Express Type-I Nucleoside Triphosphate Hydrolase1. But Lack Nucleoside Diphosphate Hydrolase Activity.Experimental Parasitology90,277–285. We have identified type I nucleoside triphosphate hydrolase (NTPase; EC 3.6.1.3) activity, previously thought to be restricted to the virulent strains ofToxoplasma gondii, in the cell extracts ofNeospora caninumtachyzoites. Sequence analysis of a complete cDNA from Nc-1 strain indicated thatN. caninumNTPases shared approximately 69% identity to the NTPases ofT. gondiiand are most similar to the NTPase-I isozyme. Southern blot analysis of genomic DNA and sequence analysis of two independentNTPclones from the Nc-1 strain revealed the presence of multiple genes, at least two of which are transcribed. Substrate specificity andK_mvalues for MgATP²⁻and MgADP⁻hydrolysis for recombinant or partially purified native NcNTPase were the same as those for the type I isozyme (NTPase-I). Significantly, no type II enzyme (NTPase-II) activity for NDP hydrolysis was detected in cell extracts ofN. caninum, although it is universally present in allT. gondiistrains that have been tested. This intriguing difference between these two closely related apicomplexan parasites may provide insight into the function of the NTPases during intracellular parasitism.     

Signalling Pathways for Cardiac Hypertrophy

Mechanical stretch is an initial factor for cardiac hypertrophy in response to haemodynamic overload (high blood pressure). Stretch of cardiomyocytes activates second messengers such as phosphatidylinositol, protein kinase C, Raf-1 kinase and extracellular signal-regulated protein kinases (ERKs), which are involved in increased protein synthesis. The cardiac renin–angiotensin system is linked to the formation of pressure-overload hypertrophy. Angiotensin II increases the growth of cardiomyocytes by an autocrine mechanism. Angiotensin II-evoked signal transduction pathways differ among cell types. In cardiac fibroblasts, angiotensin II activates ERKs through a pathway including the Gβγ subunit of Gi protein, Src family tyrosine kinases, Shc, Grb2 and Ras, whereas Gq and protein kinase C are important in cardiac myocytes. In addition, mechanical stretch enhances the endothelin-1 release from the cardiomyocytes. Further, the Na⁺–H⁺ exchanger mediates mechanical stretch-induced Raf-1 kinase and ERK activation followed by increased protein synthesis in cardiomyocytes. Not only mechanical stress, but also neurohumoral factors induce cardiac hypertrophy. The activation of protein kinase cascades by norepinephrine is induced by protein kinase A through β-adrenoceptors as well as by protein kinase C through -adrenoceptors.