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.     

Complete genome sequence and comparative analysis of the industrial microorganism Streptomyces avermitilis

Species of the genus Streptomyces are of major pharmaceutical interest because they synthesize a variety of bioactive secondary metabolites. We have determined the complete nucleotide sequence of the linear chromosome of Streptomyces avermitilis. S. avermitilis produces avermectins, a group of antiparasitic agents used in human and veterinary medicine. The genome contains 9,025,608 bases (average GC content, 70.7%) and encodes at least 7,574 potential open reading frames (ORFs). Thirty-five percent of the ORFs (2,664) constitute 721 paralogous families. Thirty gene clusters related to secondary metabolite biosynthesis were identified, corresponding to 6.6% of the genome. Comparison with Streptomyces coelicolor A3(2) revealed that an internal 6.5-Mb region in the S. avermitilis genome was highly conserved with respect to gene order and content, and contained all known essential genes but showed perfectly asymmetric structure at the oriC center. In contrast, the terminal regions were not conserved and preferentially contained nonessential genes.     

Inhibition of recombinant dipeptidyl peptidase III by synthetic hemorphin-like peptides

In order to find the most effective antagonist for dipeptidyl peptidase III degrading enkephalin, we synthesized hemorphin-like pentapeptides with aliphatic or aromatic amino acids at the N-termini, such as VVYPW, LVYPW, IVYPW, YVYPW, FVYPW and WVYPW. Among those pentapeptides, IVYPW and WVYPW showed the strongest inhibitory activity toward rDPP III. The K(i) values of IVYPW and WVYPW were 0.100+/-0.011 and 0.126+/-0.015 microM (mean+/-S.E.), respectively. The order of K(i) values was Ile> or =Trp>Phe> or =Tyr>Leu>Ala>Val>Ser>Gly. rDPP III activity is inhibited in a non-competitive manner by these peptides. The peptide VYPW did not inhibit rDPP III activity, but the sequence is essential for the expression of inhibitory activity.     

Mother–young distance in Japanese Black cattle at pasture

Distance between dam and offspring (1–121 days old) in a herd of Japanese Black cattle (Bos taurus) grazing a tropical grass (Paspalum notatum) pasture (1.5 ha) was investigated during 7-h grazing periods over grazing seasons from May (spring) to October (autumn). The mother–young distance was not constant throughout the grazing period, repeatedly increasing and decreasing. Although significant periodicity was always detected in the mother–young distance, there was no consistent dominant cycle, indicating the complexity of the within-day pattern of mother–young distance. The mean mother–young distance over the grazing period increased as a calf aged, reaching a plateau at an age of about 33 days. The mean distance of a calf from its mother was usually shorter than that from a non-mother cow, with the difference between the mean distances decreasing sharply until a calf became about 35 days old. The results and literature show that mutual independence of mother and young rapidly develops in the first 30–50 days after parturition. Electronic Publication     

Community dynamic models of two dioecious tree species

The effects of dioecy on community dynamics were examined by using transition matrix models for two dioecious tree species, one a superior competitor with a narrow dispersal range and the other an inferior competitor with a wide dispersal range. The models are based on tree-by-tree replacements in each identical microsite occupied by either male or female canopy trees of the superior competitor and canopy trees of the inferior competitor. Coexistence of the two species is possible not only because of a trade-off between competitive and dispersal abilities but also because of the existence of a competitor gap, which the superior competitor cannot occupy. The competitor gap is created under the male trees of the superior competitor. The inferior competitor occupies the competitor gap because of its wide dispersal range. The relative abundance of the two species depends on the dispersal ability and sex ratios of the superior competitor. The decreasing dispersal ability and the female abundance of the superior competitor increase the competitor gap, which allows the regeneration of the inferior competitor.An erratum to this article can be found at     

Involvement of inorganic polyphosphate in expression of SOS genes

Inorganic polyphosphate (poly(P)) is a linear polymer that has been found in every organism so far examined. To elucidate the functions of poly(P) in the regulation of gene expression, the level of cellular poly(P) in Escherichia coli was reduced to a barely detectable concentration by overproduction of exopolyphosphatase (exopoly(P)ase) with a plasmid encoding yeast exopoly(P)ase (Shiba et al., Proc. Natl. Acad. Sci. USA 94 (1997) 11210-11215). It was found that exopoly(P)ase-overproducing cells were more sensitive to UV or mitomycin C (MMC) than were control cells. Poly(P) accumulation was observed after treatment with MMC, whereas the poly(P) level was below the detectable level in cells that overproduced exopoly(P)ase. When exopoly(P)ase-overproducing cells were transformed again by a multiple copy number plasmid that carries the polyphosphate kinase gene (ppk), the cells accumulated a great amount of poly(P) and restored the UV and MMC sensitivities to the level of control cells. In exopoly(P)ase-overproducing cells, the expression of recA and umuDC were not induced by MMC. In addition, a strain containing multiple copies of ppk accumulated not only a large amount of poly(P) but also recA mRNA. Since recA expression was induced in a recA-deletion strain harboring a plasmid with the ppk gene, poly(P) could be necessary for regulating the expression of SOS genes without depending on the RecA-LexA regulatory network.     

Molecular Cloning and DNA Analysis of the Orotidine-5′-Phosphate Decarboxylase Gene from the Yeast Saccharomyces exiguus Yp74L-3

The orotidine-5′-phosphate decarboxylase gene of Saccharomyces exiguus Yp74L-3 was cloned as a DNA fragment complementing a ura4 mutation of this yeast. The coding region of the gene is 807 bp in length, and represents 68.7% similarity to the corresponding gene of S. cerevisiae (URA3). The cloned URA4 gene was shown to be located on the 790-kbp Chromosome (chr) VIII of S. exiguus Yp74L-3. The neighbor-joining phylogenetic tree based on the orotidine-5′-phosphate decarboxylase coding sequences indicates that S. exiguus Yp74L-3 is closely related to Kluyveromyces yeasts, as well as to a S. cerevisiae laboratory strain. Received: 4 February 2000 / Accepted: 3 July 2000     

Analysis of human abnormal walking using a multi-body model: joint models for abnormal walking and walking aids to reduce compensatory action

This paper proposes new models of diseased joints and evaluates the effectiveness of walking aids such as a cane and a brace for compensating for lost functions due to joint disorders. The ZMJ concept described in the previous work (Yamashita and Tagawa, 1988. In: Radharaman (Ed.), Robotics and Factories of the Future'87. Springer, New York, pp. 670-677) is modified into three joint models as follows: a passive element joint (PEJ) which has a spring at the diseased joint; a constrained range joint (CRJ), the motion of which stays within some constrained relative angle; a partial moment joint (PMJ) which can produce a partial amount of the moment produced about the joint in normal walking. A cane can enlarge a supporting area and adjust the posture of the upper torso to be upright. An ischial weight-bearing brace is effective for conservative management of hip disorders by reducing a load to the joint (Shiba et al., 1998. Clinical Orthopaedics and Related Research 351, 149-157). Walking aids like a cane or brace have been conveniently used by the handicapped. Abnormal walking was simulated for each joint model. Dynamic effects of a cane and a brace on abnormal walking were examined by the multi-body walking model.     

Highly divergent sequences of the pollen self-incompatibility (S) gene in class-I S haplotypes of Brassica campestris (syn. rapa) L

Self-incompatibility (SI) enables flowering plants to discriminate between self- and non-self-pollen. In Brassica, SI is controlled by the highly polymorphic S locus. The recently identified male determinant, termed SP11 or SCR, is thought to be the ligand of S receptor kinase, the female determinant. To examine functional and evolutionary properties of SP11, we cloned 14 alleles from class-I S haplotypes of Brassica campestris and carried out sequence analyses. The sequences of mature SP11 proteins are highly divergent, except for the presence of conserved cysteines. The phylogenetic trees suggest possible co-evolution of the genes encoding the male and female determinants.     

Characterization of Solt, a novel SoxLZ/Sox6 binding protein expressed in adult mouse testis

SoxLZ/Sox6, a member of the Sox protein family, contains a leucine zipper motif in addition to an HMG box, which is its DNA binding domain. Here we have identified a novel SoxLZ/Sox6 binding protein, termed Solt, which we obtained independently using both a far-Western blot and a yeast two-hybrid screen. Like SoxLZ/Sox6 mRNA, Solt mRNA was exclusively expressed in the testis in mouse. Solt contains an unusual leucine zipper, which bound to the leucine zipper region of SoxLZ/Sox6 in vitro. In transient transfection assays in CHO cells with SoxLZ/Sox6 containing the transactivational region of herpes simplex virus VP16, expression of a reporter gene that carries a cis binding region for Sox proteins was significantly enhanced by the co-expression of Solt and Ca(2+)/calmodulin-dependent protein kinase IV.